JP4645441B2 - Method for controlling operation of cement kiln and method for producing cement - Google Patents

Description

  The present invention relates to a control method for stabilizing the operation of a cement kiln and a method for producing cement using the same.

  It is known that the temperature of the raw material in the cement kiln greatly affects the quality of the clinker, the control of the particle size, the proper adhesion of the coating that protects the refractory from the pulverized coal combustion frame, and the like. However, since only the temperature in the vicinity of the raw material outlet of the cement kiln can be actually measured, conventionally, the raw material temperature in the cement kiln cannot be used as a parameter for operation control of the cement kiln.

As a prior art related to operation control of a cement kiln, for example, a method described in Non-Patent Document 1 is known. In this method, the SO ₂ concentration of the kiln bottom (raw material inlet side) of the cement kiln that depends on the raw material temperature and the firing atmosphere in the cement kiln is continuously measured, and the measured value is a parameter for grasping the operation status. It is used as one. However, in Non-Patent Document 1, only a simple correlation is obtained in which the SO ₂ concentration increases as the raw material temperature in the cement kiln increases, and a quantitative relationship between the SO ₂ concentration and the temperature distribution of the raw material is obtained. Since the relationship was not yet understood, for example, the temperature of the raw material in the cement kiln could not be estimated from the SO ₂ concentration, or the operation control of the cement kiln could not be performed based on this. Actually, the situation is grasped by utilizing the fact that the SO ₂ concentration increases when the coating mainly composed of gypsum is dropped and when the combustion of coal is incomplete combustion and CO is generated. Stayed at the level.

Peter Dover, “Sulphur dioxide cycles in kilns-Practical methods for reducing build-up and blockage problems”, UK, 26th International Cement Seminar (26th Proc Int Cem Semin), 1990, p. 151-169

  The present invention has been made in view of such circumstances, and it is possible to easily grasp the temperature distribution of the raw material in the cement kiln and to control the operation of the cement kiln by performing operation control of the cement kiln based on this. It is an object of the present invention to provide a method for controlling the operation of a cement kiln capable of stabilizing the cement and a method for producing a cement using the same.

The operation control method for a cement kiln according to the first aspect of the present invention uses a process simulation to calculate the SO ₂ concentration of the gas discharged from the kiln bottom of the cement kiln and the temperature distribution of the raw material in the cement kiln. The first step for determining the relationship, the second step for measuring the SO ₂ concentration of the gas discharged from the kiln bottom, and estimating the temperature distribution of the raw material in the cement kiln from the measured value, and the raw material in the cement kiln so that the temperature distribution is kept constant, it was closed and a third step of adjusting the pulverized coal combustion burner, and the process simulation, the model the cement burning process by combining a plurality of unit operations model One unit and the unit operations set in each of the unit operation models are sequentially executed in accordance with the combination order of the unit operation models, and the series of operations is performed. The second step of analyzing the mass balance and heat balance in the cement kiln is repeated by repeating until a predetermined convergence condition is satisfied, and the first step is applied to a region where the raw material is not granulated. As a unit operation model, it is assumed that a part of the combustion gas flowing into the region reaches an equilibrium state with the raw material, and the flow division model that divides the flow of combustion gas at the corresponding division ratio and the flow division model An equilibrium calculation model that calculates and outputs each flow rate and composition data when one of the generated combustion gases and the raw material existing in the region reaches an equilibrium state, and the equilibrium calculation model reaches the equilibrium state with the raw material. Has the function of calculating and outputting the flow rate and composition data of the combustion gas when the combustion gas mixed with the other combustion gas divided by the flow rate division model A predetermined unit operation model is used, the division ratio is X, the reaction interface between the combustion gas and the raw material in the region is A, the mass transfer coefficient of the volatile substance between the combustion gas and the raw material in the region is k, and the region is Assuming that the flow rate of the inflowing combustion gas is Q, the division ratio X is set by X = A · k / Q, and flows into the region as a unit operation model applied to the region where the raw material is granulated. Formed by a first flow rate division model that forms a flow of gas corresponding to each volatile matter of interest by dividing the flow of combustion gas according to the quantity of the volatile matter of interest, and the first flow rate division model. The separator model for separating other volatile substances so that only one volatile substance of interest is included in each of the gas flows, and each gas separated from the other volatile substances by the above separator model. Assuming that some of these components reach equilibrium with the raw materials, the second flow rate splitting model that divides the flow of each gas at the corresponding split ratio and each volatile substance remaining in the raw material particles constitute A third flow rate division that generates a flow of the raw material corresponding to the flow of each gas divided by the second flow rate division model by dividing the flow of the raw material flowing into the region according to the size of the nucleus to be performed Calculate the flow rate and composition data when the model, each gas divided by the second flow rate division model, and the corresponding raw material divided by the third flow rate division model reach an equilibrium state. In the second flow rate division model, the gas division ratio corresponding to the volatile substance i is Xi, the reaction interface between the combustion gas and the raw material in the region is A, and the volatile substance i The mass transfer coefficient is ki, the flow rate before the gas corresponding to the volatile substance i is Qi, and the gas division ratio Xi corresponding to the volatile substance i is set by Xi = A · ki / Qi. The mass transfer amount between the raw material and the combustion gas in the above region is obtained for each volatile substance i by a combination of operation models .

The operation control method for a cement kiln according to the present invention as set forth in claim 2 uses the process simulation to set the raw material immediately before being put into the cement kiln as a 1Cy raw material, the SO ₃ concentration of the 1Cy raw material and the inside of the cement kiln. A first step for determining the relationship with the temperature distribution of the raw material, a second step for measuring the SO ₃ concentration of the 1Cy raw material, and estimating the temperature distribution of the raw material in the cement kiln from the measured value, so that the temperature distribution of the raw material is kept constant, it was closed and a third step of adjusting the pulverized coal combustion burner, and the process simulation, modeling cement burning process by combining a plurality of unit operations model The unit operations set in each of the unit operation models are sequentially executed in accordance with the combination order of the first step and the unit operation models. And a second step of analyzing the material balance and the heat balance in the cement kiln by repeating the series of operations until a predetermined convergence condition is satisfied. In the first step, the raw material is granulated. As a unit operation model to be applied to a region that is not, a flow rate division model that considers that a part of the combustion gas flowing into the region reaches an equilibrium state with the raw material, and divides the flow of the combustion gas at a corresponding division rate; An equilibrium calculation model for calculating and outputting each flow rate and composition data when one combustion gas divided by the flow rate division model and the raw material existing in the region reach an equilibrium state, and the equilibrium calculation model The flow rate and composition data of the combustion gas when the combustion gas that has reached equilibrium with the raw material is mixed with the other combustion gas divided by the flow rate division model are calculated. A predetermined unit operation model having a function of outputting is used, the division ratio is X, the reaction interface between the combustion gas and the raw material in the region is A, and the mass transfer coefficient of the volatile substance between the combustion gas and the raw material in the region is k, where Q is the flow rate of the combustion gas flowing into the region, and the division ratio X is set by X = A · k / Q, and as a unit operation model applied to the region where the raw material is granulated, A first flow rate dividing model that forms a gas flow corresponding to each of the volatile substances of interest by dividing the flow of the combustion gas flowing into the region according to the quantity of the volatile substances of interest; A separator model that separates other volatile substances so that only one volatile substance of interest is included in each of the gas flows formed by the flow division model, and other volatile substances in the separator model. Assuming that a part of the flow of each gas separated from each other reaches an equilibrium state with the raw material, a second flow rate division model that divides each gas flow at a division ratio corresponding to each of the gas flows, and the residual gas in the raw material particles The flow of the raw material corresponding to the flow of each gas divided by the second flow rate division model is divided by dividing the flow of the raw material flowing into the region according to the size of the nucleus formed by each volatile substance. Each flow rate when the generated third flow rate division model, each gas divided by the second flow rate division model, and the corresponding raw material divided by the third flow rate division model reach an equilibrium state. And the equilibrium calculation model that calculates and outputs the composition data, and in the second flow rate splitting model, the gas splitting ratio corresponding to the volatile substance i is Xi, and the reaction between the combustion gas and the raw material in the above region Suppose that the surface is A, the mass transfer coefficient of the volatile substance i is ki, the flow rate of the gas corresponding to the volatile substance i is Qi, and the gas division ratio Xi corresponding to the volatile substance i is Xi = A · ki / Qi is set, and the mass transfer amount between the raw material and the combustion gas in the above region is obtained for each volatile substance i by combining these unit operation models .

The operation control method for a cement kiln according to the present invention as set forth in claim 3 uses a process simulation to measure chloride concentration such as KCl and SO ₂ concentration of gas discharged from the kiln bottom of the cement kiln, and cement kiln. The first step of determining the relationship with the temperature distribution of the raw material in the inside, and the concentration of chloride such as KCl and SO ₂ concentration of the gas discharged from the kiln bottom are measured, and the temperature of the raw material in the cement kiln is determined from these measured values. a second step of estimating a distribution, so that the temperature distribution of the material in the cement kiln is kept constant, it was closed and a third step of adjusting the pulverized coal combustion burner, and the process simulation, cement A first step of modeling the firing process by a combination of a plurality of unit operation models, and the unit operation model in accordance with a combination order of the unit operation models. A second step of analyzing the mass balance and heat balance in the cement kiln by sequentially executing the unit operations set for each of the above and repeating the series of operations until a predetermined convergence condition is satisfied. In the first step, as a unit operation model to be applied to a region where the raw material is not granulated, it is assumed that a part of the combustion gas flowing into the region reaches an equilibrium state with the raw material, and a division ratio corresponding thereto is used. Calculate the flow rate and composition data when the flow rate division model that divides the flow of combustion gas, and one combustion gas divided by the flow rate division model and the raw material existing in the region reach an equilibrium state. The output of the equilibrium calculation model, the combustion gas that has reached equilibrium with the raw material in the equilibrium calculation model, and the other combustion gas divided in the flow rate division model are mixed. A predetermined unit operation model having a function of calculating and outputting the flow rate and composition data of the gas, the division ratio X, the reaction interface of the combustion gas and the raw material in the region A, and the combustion gas in the region The division ratio X is set by X = A · k / Q, where k is the mass transfer coefficient of the volatile material between the raw materials and Q is the flow rate of the combustion gas flowing into the region, and the raw material is granulated. As a unit operation model applied to a certain area, the flow of the combustion gas flowing into the above area is divided according to the quantity of the volatile substance of interest, thereby forming a gas flow corresponding to each of the volatile substances of interest. Separator model for separating other volatile substances so that only one volatile substance of interest is included in each of the first flow rate division model and the gas flow formed by the first flow rate division model. A second flow rate division that divides each gas flow at a division ratio corresponding to each gas flow obtained by separating other volatile substances in the separator model and assuming that a part of each gas flow reaches an equilibrium state with the raw material. Each gas divided by the second flow rate division model by dividing the flow of the raw material flowing into the region according to the model and the size of the nucleus formed by each volatile substance remaining in the raw material particles The third flow rate dividing model that generates the flow of the raw material corresponding to the flow of the gas, the gas divided by the second flow rate dividing model, and the raw material divided by the third flow rate dividing model corresponding thereto are balanced. And an equilibrium calculation model that calculates and outputs each flow rate and composition data when reaching the state, and in the second flow rate splitting model, the gas split rate corresponding to the volatile substance i is Xi, The division ratio of the gas corresponding to the volatile substance i, where A is the reaction interface between the combustion gas and the raw material in the region, the mass transfer coefficient of the volatile substance i is ki, and the flow rate before dividing the gas corresponding to the volatile substance i is Qi. Xi is set by Xi = A · ki / Qi, and the mass transfer amount between the raw material and the combustion gas in the above region is obtained for each volatile substance i by combining these unit operation models. Is.

The operation control method for a cement kiln according to the present invention described in claim 4 uses a process simulation to set the raw material immediately before being put into the cement kiln as a 1Cy raw material, and the SO ₃ concentration and Cl concentration of the 1Cy raw material. The first step of obtaining the relationship with the temperature distribution of the raw material in the cement kiln, the second step of measuring the SO ₃ concentration and the Cl concentration of the 1Cy raw material, and estimating the temperature distribution of the raw material in the cement kiln from these measured values a step, so that the temperature distribution of the material in the cement kiln is kept constant, it was closed and a third step of adjusting the pulverized coal combustion burner, and the process simulation, cement burning process a plurality of units A first step of modeling by a combination of operation models, and each unit operation model according to the combination order of the unit operation models And sequentially executing the set unit operations and repeating the series of operations until a predetermined convergence condition is satisfied, thereby having a second step of analyzing the mass balance and heat balance in the cement kiln, In the first step, as a unit operation model to be applied to a region where the raw material is not granulated, it is assumed that a part of the combustion gas flowing into the region reaches an equilibrium state with the raw material, and combustion is performed at a corresponding division ratio. Calculate and output the flow rate composition model that divides the gas flow and each flow rate and composition data when one combustion gas divided by the flow rate division model and the raw material existing in the region reach an equilibrium state. The combustion gas when mixing the combustion gas that has reached the equilibrium state with the raw material in the equilibrium calculation model and the other combustion gas divided in the flow rate division model. And a predetermined unit operation model having a function of calculating and outputting the flow rate and composition data of the gas, the division ratio X, the reaction interface of the combustion gas and the raw material in the region A, and the combustion gas and the raw material in the region The division ratio X is set by X = A · k / Q, where k is the mass transfer coefficient of the volatile substances between them and Q is the flow rate of the combustion gas flowing into the region, and the raw material is granulated. As a unit operation model applied to the region, the flow of the combustion gas flowing into the region is divided according to the amount of the volatile material of interest to form a gas flow corresponding to each of the volatile materials of interest. A separator model that separates other volatile substances so that only one volatile substance of interest is included in each of the gas flows formed in the first flow quantity division model, A second flow rate splitting model that divides each gas flow at a corresponding split rate, assuming that a part of each gas flow separated from other volatile substances by the separator model reaches an equilibrium state with the raw material. And by dividing the flow of the raw material flowing into the region according to the size of the nuclei formed by the volatile substances remaining in the raw material particles, the gas divided by the second flow rate division model is divided. The third flow rate dividing model for generating the flow of the raw material corresponding to the flow, each gas divided by the second flow rate dividing model, and the raw material divided by the third flow rate dividing model corresponding to the third flow dividing model And an equilibrium calculation model that calculates and outputs each flow rate and composition data when the gas reaches the gas flow rate. In the second flow rate division model, the gas division rate corresponding to the volatile substance i is Xi, The division ratio Xi of the gas corresponding to the volatile substance i, where A is the reaction interface between the combustion gas and the raw material in the region, the mass transfer coefficient of the volatile substance i is ki, and the flow rate before the division of the gas corresponding to the volatile substance i is Qi. Is set by Xi = A · ki / Qi, and by combining these unit operation models, the mass transfer amount between the raw material and the combustion gas in the above region is obtained for each volatile substance i. It is.

  Here, as a method of equilibrium calculation, a method is adopted in which a product that may be generated is given in advance, and the product is determined so that the free energy of the system is minimized while maintaining mass balance. be able to. In this method, there is no theoretical limit to the number of product substances that can be set, and it is not necessary to set a reaction formula, so that complex equilibrium calculations can be easily performed. By calculating the mass transfer amount based on the difference between the vapor phase partial pressure of the volatile component obtained in this equilibrium calculation and the gas phase partial pressure in the freeboard gas, the mass transfer amount of complex chemical species and volatile components can be accurately and accurately determined. It can be easily calculated.

According to a fifth aspect of the present invention, there is provided a method for manufacturing a cement according to the present invention, wherein the cement kiln is controlled by the operation control method according to any one of the first to fourth aspects to manufacture a clinker, and the cement is manufactured from the clinker. It is characterized by this.

According to the present invention, in the first step, the concentration of the specific substance (SO ₂ concentration, chloride concentration such as KCl) contained in the gas discharged from the kiln bottom of the cement kiln and the temperature distribution of the raw material in the cement kiln Or the relationship between the concentration (SO ₃ concentration, Cl concentration) of the specific substance contained in the 1Cy raw material and the temperature distribution of the raw material in the cement kiln, and in the second step, the concentration of the specific substance Because the temperature distribution of the raw material in the cement kiln was estimated from the measured value, and then, in the third step, the pulverized coal combustion burner was adjusted so that the temperature distribution of the raw material was kept constant. Various problems caused by changes in temperature distribution of raw materials (for example, clinker quality variation, cyclone clogging, refractory deterioration, etc.) can be resolved and stable over a long period of time. The cement kiln can be operated in a wet state.

FIG. 1 is a diagram showing a process flow of a cement firing step, in which 1 is a preheater, 2 is a cement kiln, and 3 is a clinker cooler.
The preheater 1 has a plurality of cyclones 4 interconnected in the vertical direction, and in the process of sending the powder raw material supplied to the uppermost stage 4a to the lower cyclone, the gas etc. discharged from the cement kiln 2 It is designed to preheat powder raw materials. The cyclone 4 (1Cy) in the lowermost stage 4b is connected to the cement kiln 2, so that the raw material (1Cy raw material) preheated to a predetermined temperature (about 800 ° C.) by the preheater 1 is continuously fed into the cement kiln 2. It is configured.

  The cement kiln 2 has a substantially cylindrical main body 2a that is rotatable and is disposed in a state where its axis is slightly inclined with respect to the horizontal direction. The cement kiln 2 has one end (hereinafter referred to as a kiln butt) of the main body 2a connected to the pre-heater 1, while the other end (hereinafter referred to as a kiln front) is connected to the clinker cooler 3 from the kiln butt. The inflowing raw material is configured to sequentially move toward the front of the kiln by the rotation of the main body 2a. A pulverized coal combustion burner 5 is installed on the front side of the kiln of the main body 2a, and the combustion gas generated by burning the pulverized coal with this pulverized coal combustion burner 5 flows from the front of the kiln to the bottom of the kiln as shown in FIG. In other words, it is blown in the direction opposite to the flow of the raw material. The raw material generates a melt in the process of moving from the kiln bottom to the kiln, and thereafter gradually increases in particle size, and reaches a certain particle size when reaching the front of the kiln. The raw material discharged from before the kiln is cooled by the clinker cooler 3 and then taken out as a clinker. The clinker thus produced is mixed with gypsum and ground in a subsequent finishing process to be finished into a powdery cement.

In the cement firing step shown in FIG. 1, first, crystal water is released by decomposition of the clay mineral at the top of the preheater 1 (about 500 ° C.). The thermal decomposition of limestone starts from about 800 ° C. (lower part of the preheater 1), and CaO is generated by this thermal decomposition. And by this solid phase reaction of CaO with Al ₂ O ₃ , Fe ₂ O ₃ and SiO ₂ , CA (CaO · Al ₂ O ₃ ), C ₃ A (3CaO · Al ₂ O ₃ ), C ₂ S (2CaO) _{· SiO 2), C 4 AF} (2CaO · Al 2 O 3 -2CaO · Fe 2 O 3 solid solution) or the like is gradually generated until about 1200 ° C.. When the temperature reaches about 1250 ° C., C ₃ A, C ₄ AF and the like start to dissolve, and a liquid phase is generated. C ₂ S reacts with CaO through this liquid phase, so that C ₃ S (3CaO · SiO ₂ ) is produced. When the maximum temperature reaches about 1450 ° C., CaO in the raw material is almost lost. Thereafter, the temperature of the raw material is gradually lowered by the secondary air from the clinker cooler 3 in the cement kiln 2, reaches about 1250 ° C. at the raw material outlet, and is rapidly cooled to about 200 ° C. in the clinker cooler 3. In this process, C ₃ A (3CaO · Al ₂ O ₃ ) and C ₄ AF (2CaO · Al ₂ O ₃ -2CaO · Fe ₂ O ₃ solid solution) are precipitated from the liquid phase in the gap between C ₂ S and C ₃ S. Go.

Next, an embodiment of the operation control method for a cement kiln according to the present invention will be described.
This operation control method is included in the raw material temperature of the firing zone of the cement kiln 2 (for example, in the range of 2 to 17 m from the front of the kiln) and the desorption zone (also in the range of 17 to 30 m), and the kiln bottom gas or 1Cy raw material. The first step for determining the relationship between the concentration of the specific substance (the SO ₂ concentration of the kiln butt gas, the chloride concentration of KCl etc. of the kiln butt gas, the SO ₃ concentration of the 1 Cy raw material, the Cl concentration of the 1 Cy raw material), and the above specified The second step of measuring the concentration of the substance and estimating the temperature distribution of the raw material in the cement kiln 2 from the measured value, and the third step of adjusting the pulverized coal combustion burner so that the temperature distribution of the raw material is kept constant And have.

  First, in the first step, the relationship between the concentration of the specific substance contained in the kiln butt gas or 1Cy raw material and the temperature distribution of the raw material in the cement kiln 2 is obtained using process simulation (described later).

FIG. 2 is a graph showing the relationship between the temperature change in the cement kiln 2 and the SO ₂ concentration and KCl concentration of the kiln bottom gas. In this graph, the reference temperature (for example, the block average raw material temperature of FIG. 8) in which the raw material temperatures of the firing zone (K6 and K7 blocks in FIG. 8 described later) and the desorption zone (K3 to K5 blocks in FIG. 8) are set in advance. Each gas concentration when the temperature is changed and one or both of the raw material temperatures of the firing zone and the desorption zone are changed from the reference temperature.
According to this graph, it can be understood that when the raw material temperature of one of the desorption zone and the firing zone is increased, the SO ₂ concentration of the kiln bottom gas is increased, and when both temperatures are increased, the effects are totaled. Since the change in the SO ₂ concentration with respect to the temperature change is larger in the calcined zone, it is possible to grasp a rough temperature change in the calcined zone by measuring only the SO ₂ concentration.

On the other hand, it can be seen that the KCl concentration of the kiln bottom gas decreases conversely when the raw material temperature in the firing zone increases, and does not change much even if the raw material temperature in the desorption zone changes.
Therefore, if the KCl concentration is measured in addition to the SO ₂ concentration of the kiln bottom gas, it is possible to accurately grasp the change in the raw material temperature in the desorption zone and the firing zone from the change in both.
The gas concentration in the kiln bottom is greatly influenced by the chemical composition of the clinker, in particular K ₂ O, Na ₂ O, SO ₃ and Cl, in addition to the temperature of the raw material. Therefore, in the simulation, the chemical composition of the clinker is an important input parameter, and it is possible to grasp an accurate temperature by periodically reviewing this chemical composition.

FIG. 3A is a graph showing the relationship between the temperature change of the desorption zone and the SO ₃ concentration and Cl concentration of the 1Cy material, and FIG. 3B is the temperature change of the firing zone and the SO ₃ concentration of the 1Cy material. It is a graph which shows the relationship with Cl concentration. According to these graphs, changes in the SO ₃ concentration and Cl concentration of the 1Cy raw material are almost the same as changes in the SO ₂ concentration and KCl concentration of the kiln bottom gas, and when the raw material temperature in the desorption zone increases, the SO ₃ concentration It can be seen that both the Cl concentration and the Cl concentration increase, while the SO ₃ concentration increases but the Cl concentration decreases when the raw material temperature in the calcining zone increases. That is, if the SO ₃ concentration and the Cl concentration of the 1Cy raw material are measured, it is possible to accurately grasp the change in the raw material temperature in the desorption zone and the firing zone, similarly to the SO ₂ concentration and the KCl concentration of the kiln bottom gas. .

FIG. 4 shows the gas concentrations of SO ₂ , KCl, NaCl, and HCl at the kiln bottom when the temperature of the desorption zone and the firing zone and the SO ₃ concentration and Cl concentration in the clinker are changed as input parameters, and the 1Cy raw material. is a table showing the calculation results of SO ₃ concentration and Cl concentration. FIG. 5 is a chart showing an estimation formula of the raw material temperature in the desorption zone obtained by multivariate regression analysis using the data of FIG.

In FIG. 5, R ² is a determination coefficient, and the closer this value is to 1, the higher the estimation accuracy. The numerical values on the right side of the R ² value are the clinker SO ₃ concentration (%), Cl concentration (ppm), kiln bottom gas SO ₂ concentration (%), SO ₂ and KCl concentration ratio, KCl concentration (%), NaCl Concentration (%), concentration ratio of KCl and NaCl, concentration ratio of KCl and HCl, 1Cy raw material SO ₃ concentration (%) and Cl concentration (ppm) It is a coefficient value, and the numerical value at the right end is a constant term. The numerical value in parentheses below each coefficient value and the constant term represents the t value by t test. The t value indicates that the coefficient is significant at the significance level of 95% when the absolute value is about 2 or more. That is, as an estimation formula for the raw material temperature in the desorption zone, a regression equation having a high R ² and consisting of significant variables is 6, 7, 12, 13, 14, 16.

No. According to the regression equation of No. 6, the raw material temperature in the desorption zone can be estimated from the SO ₂ concentration and the KCl concentration of the kiln bottom gas, and the clinker SO ₃ concentration and Cl concentration are added as explanatory variables. If the regression equation of 7 is used, the estimation accuracy is further increased. No. The regression equation of 12 estimates the raw material temperature of the desorption zone from the KCl concentration of the kiln bottom gas and the concentration ratio of the KCl and NaCl of the kiln bottom gas, and the Cl concentration of the clinker is added as an explanatory variable to this. No. No. 13 regression equation, which uses the concentration of NaCl instead of the concentration ratio of KCl and NaCl in kiln bottom gas, is No. 13. 14 regression equations. No. The 16 regression equations estimate the raw material temperature in the desorption zone from the SO ₃ concentration and Cl concentration of the 1Cy raw material. Thus, the material temperature of the desorption zone, it is possible to estimate the combination of the SO ₂ concentration and KCl concentration in kiln inlet gas, or a combination of KCl concentration and the concentration of NaCl in the kiln inlet gas, SO ₃ concentration and of clinker The accuracy can be further improved by using the Cl concentration. It can also be seen that the material temperature in the desorption zone can be estimated by the SO ₃ concentration and the Cl concentration of the 1Cy material.

FIG. 6 is a chart showing an estimation formula of the raw material temperature of the calcining zone obtained by multivariate regression analysis using the data of FIG. As shown in FIG. 6, as an estimation formula for the raw material temperature of the calcining zone, a regression equation having a high R ² and composed of significant variables is No. It was 1,3,6,9,10,13.
No. According to the regression equation of No. 1, the raw material temperature of the firing zone can be estimated only from the SO ₂ concentration of the kiln bottom gas. As shown in the regression equation in FIG. 6, if the SO ₃ concentration of the clinker and the Cl concentration of the clinker and the KCl concentration of the kiln butt gas are added as explanatory variables in addition to the SO ₂ concentration of the kiln butt gas, the estimation accuracy is further increased. Become. No. The regression equation 3 estimates the raw material temperature of the firing zone from the SO ₂ concentration of the kiln bottom gas and the SO ₃ concentration of the clinker. The regression equation of No. 9 is based on the SO ₃ concentration of clinker and the KCl concentration of kiln bottom gas. From the clinker SO ₃ concentration and Cl concentration, the KCl concentration of the kiln bottom gas, and the KCl and NaCl concentration ratio of the kiln bottom gas, The 13 regression equations estimate the raw material temperature of the calcining zone from the SO ₃ concentration and Cl concentration of the clinker and the SO ₃ concentration and Cl concentration of the 1Cy raw material, respectively. Thus, the raw material temperature of the firing zone can be estimated only from the SO ₂ concentration of the kiln bottom gas, and by using the SO ₃ concentration and Cl concentration of the clinker, the KCl concentration of the kiln bottom gas, and the like for this. The accuracy can be further increased. Similarly, the raw material temperature of the firing zone can be estimated from the combination of the SO ₃ concentration of the clinker and the KCl concentration of the kiln bottom gas.

Thus, after obtaining the regression equation for estimating the raw material temperature of the desorption zone and the firing zone in the first step, the process proceeds to the second step. In the second step, first, the concentration of the substance corresponding to the explanatory variable of the regression equation obtained in the first step is measured, and then the temperature distribution of the raw material in the cement kiln 2 is estimated from the measured value. For example, the SO ₂ concentration and KCl concentration of kiln butt gas are measured, and the measured values are shown in No. 5 of FIG. 6 can be estimated, the raw material temperature in the desorption zone can be estimated, and the measured value of the SO ₂ concentration is shown in No. 6 of FIG. Substituting into the regression equation of 1 makes it possible to estimate the raw material temperature of the firing zone. Further, the SO ₃ concentration and the Cl concentration of the 1Cy raw material were measured, and these measured values were obtained as No. 1 in FIG. The raw material temperature in the desorption zone can also be estimated by substituting into the 16 regression equations. Further, the measured value of the SO ₃ concentration and Cl concentration of 1Cy material, the SO ₃ concentration and Cl concentration of clinker, No. 6 It is also possible to estimate the raw material temperature of the calcining zone by substituting into the 13 regression equations.

  In the third step, it is determined whether or not the temperature distribution obtained in the second step matches a preset temperature distribution. If both match, as a result of the determination, the pulverized coal combustion burner 5 is set to the current state. Keep it as it is. On the other hand, when both do not correspond, the flow rate of the primary air blown from the vicinity of the pulverized coal flow of the pulverized coal combustion burner 5 is adjusted. Specifically, increasing the primary air results in pre-baking (the temperature at the bottom of the kiln lowers, but the maximum temperature at the front of the kiln is high, and the type that fires at once), while reducing the primary air reduces the back-firing ( The maximum temperature on the front side of the kiln does not increase, but the temperature on the bottom side of the kiln is high, and it is a type that is carefully baked), so using such properties, the temperature distribution of the raw material in the cement kiln 2 becomes the desired temperature Adjust the primary air flow rate as follows. The method for adjusting the temperature distribution of the raw material in the cement kiln 2 is not limited to this. For example, the temperature distribution of the raw material in the cement kiln 2 can also be obtained by modifying the pulverized coal combustion burner or changing the raw material composition. Can be adjusted.

  Next, a process simulation used for obtaining the relationship between the concentration of the specific substance contained in the kiln bottom gas or 1Cy raw material and the temperature distribution of the raw material in the cement kiln 2 in the first step will be described.

  Process simulation is a mathematical model of phenomena that occur mainly in mixing equipment, distillation towers, reaction towers, etc. in chemical engineering plants, and calculates the material balance and heat balance. The processing includes a CPU, RAM, and storage device. A known computer having an input device and a display device is used. The storage device of the computer stores a storage area for storing various processing programs (process simulation software, etc.) executed by the CPU and control data, and various data (definition data for unit operation models, etc.) handled by the program. A storage area is provided, and the CPU executes a program stored in the storage device so that the following steps are performed.

  In the present embodiment, each unit operation model is set in accordance with a first step of modeling a chemical process occurring in the cement kiln 2 or the preheater 1 by a combination of a plurality of unit operation models and a unit operation model combination order. The unit operation is sequentially executed, and the series of operations is repeated until a predetermined convergence condition is satisfied, thereby having a second step of analyzing the material balance and the heat balance in the cement kiln 2 and the preheater 1.

Here, as the unit operation model, for example, an equilibrium calculation model, a flow rate division model, a mixed calculation model, a stoichiometric reaction model, and the like are prepared in advance.
Each unit operation model defines each function and conditions to be set in advance, and each unit operation model has stream information (for example, data on raw materials and gas components, flow rate, temperature, pressure, etc.). Is input, a predetermined calculation based on defined functions and setting conditions (reactor size, operating conditions, etc.) is performed, and the calculation results (raw materials and gas components, flow rate, temperature, pressure, etc.) are output. It has come to be.

  Equilibrium calculation model sets chemical equilibrium calculation and phase equilibrium calculation so that the free energy of the generated substance is minimized by setting in advance the types and phases of substances (product substances) that may be generated. And has the function of determining the type, phase and flow rate of the product. Further, the flow rate division model has a function of dividing a stream of gas or raw material at a preset division rate, and the mixing calculation model has a function of mixing a plurality of streams. The stoichiometric reaction model is a function for calculating the type and flow rate of a product using a preset reaction equation and reaction rate, the heater model is a function for calculating outlet temperature and enthalpy change, and the separator model is Each has a function of dividing a specific component at a given ratio. Each unit operation model is connected to each other along a raw material or gas stream (including an assumed stream), and unit operations are sequentially executed in the connection order.

  For example, when a certain chemical process is modeled by a combination of unit operation models as shown in FIG. 7, if information on the stream F1 is given, information on the stream F2 is calculated in the unit operation model A. Next, the information of the stream F3 is calculated in the unit operation model B. However, since the information of the stream F5 is unknown, the expected value (or initial value) of the information of the stream F5 and the information of the stream F2 are used. Thus, information of the stream F3 is calculated. Then, after the information of the stream F4 is calculated in the unit operation model C, the stream F4 is divided at a predetermined division rate in the unit operation model D (flow rate division model), and each of the divided streams F5 and F6 is divided. Are calculated respectively. Next, the calculated value of the information of the stream F5 is compared with the predicted value, and if the difference falls within a predetermined range (when a predetermined convergence condition is satisfied), the calculation ends, while the predetermined value If it does not fall within the range, the calculations in the unit operation models B, C, and D are repeated until the difference from the previous calculation value falls within the predetermined range. As a result, when the calculation is completed, the mass balance and heat balance of the system are satisfied.

For example, when modeling the above-described cement firing process, the stream information input to the unit operation model is data such as raw material and combustion gas components, flow rate, temperature, pressure, and the like.
In this embodiment, as shown in FIG. 8, as a block for calculating mass transfer between chlorine and sulfur gas and raw material and generation of clinker mineral, as shown in FIG. Divided into K1-K8). In addition, the average raw material temperature and length of each block are set as shown in FIG. 8, and in each block, heat exchange is not calculated and necessary for heating and reaction of the raw material that is heated according to the set raw material temperature distribution. It is assumed that a sufficient amount of heat is supplied from the gas, and the gas temperature gradually decreases toward the raw material inlet. Note that the temperature of the raw material can be determined by incorporating a heat exchange model between the combustion gas and the raw material into the simulation without being set here.

  In the cement kiln 2, as shown in FIG. 9A, mass transfer occurs between the combustion gas and the raw material due to volatilization or condensation of volatile substances. Further, since the flow of the combustion gas and the raw material is an opposite flow, and the flow velocity of one of the combustion gases is relatively large, the combustion gas and the raw material do not reach an equilibrium state.

  Therefore, in the present embodiment, as shown in FIG. 9 (b), it is considered that only a part of the combustion gas flowing into a certain region (for example, region S) in the cement kiln 2 reaches an equilibrium state with the raw material, Each of the flow rate division model M1 that divides the flow of the combustion gas at the corresponding division ratio, and when one combustion gas divided by the flow rate division model M1 and the raw material existing in the region S reach an equilibrium state. The equilibrium calculation model M2 that calculates and outputs the flow rate and composition data of the gas, and the other combustion gas divided by the flow rate division model M1 and the combustion gas that has reached the equilibrium state by the equilibrium calculation model M2 (output from the equilibrium calculation model M2) Used as an equilibrium calculation model (or mixed calculation model) M3 for calculating and outputting the flow rate and composition data of the combustion gas when mixing the flow rate and composition data).

  The amount of volatilization / condensation of chlorine and sulfur can be expressed by the difference between the vapor pressure in the vicinity of the raw material of the volatile substance and the vapor pressure of the gas above the raw material (freeboard), the mass transfer coefficient, and the reaction interface. .

Here, J _i is the mass transfer (volatilization / condensation) amount of the volatile substance i, A is the reaction interface, k _i is the mass transfer coefficient of the volatile substance i, P _eqi is the equilibrium vapor pressure near the raw material of the volatile substance i, _Pi is the vapor pressure in the free board gas of the volatile substance i. Further, in the above model in which the mass transfer is expressed by partial equilibrium, the mass transfer amount is expressed by Formula 2.

In _Equation 2, Q _eq is the amount of free board gas that reaches equilibrium with the raw material. Then, from the equations 1 and 2, the following relational expression can be obtained.

  Therefore, the division ratio when the freeboard gas having the flow rate Q flowing into the region is divided by the flow division model is as shown in Equation 4.

For example, if the gas boundary film diffusion on the raw material bed is dominant and the diffusion coefficient of each volatile substance i is not greatly different at less than 1250 ° C. before the raw material is granulated in the kiln 2, various volatilization The division rate X of the flow rate division model can be obtained from the mass transfer coefficient k as the average value of the condensed material.
However, when the temperature becomes 1250 ° C. or higher and the raw material is granulated to become a clinker, the clinker pore diffusion of volatile substances cannot be ignored. In this case, the mass transfer coefficient calculated by the unreacted nucleus model described later depends on the unreacted radius, that is, the radius at which the volatile material is not volatilized, and this radius differs between chlorine and sulfur (for example, Since the radius of chlorine having a larger volatility is smaller), it is necessary to determine k _i for each substance i (chlorine and sulfur). In this case, as shown in Equation 5, it is necessary to determine X _i by dividing the free board gas into a gas (flow rate Q _i ) containing only the substance i as a volatile substance.

  Hereinafter, the method for calculating the mass transfer coefficient will be described separately when the raw material is not granulated (K1 to K2 block) and when the raw material is granulated (K3 to K8 block).

(1) No raw material granulation
In the literature (SH Tscheng, and AP Watkinson, The Canadian Journal of Chemical Engineering, 57, 433 (1979)), Watkinson et al. It is said that it will be about 10 times the theoretical value. With reference to this, in the present embodiment, the Sherwood number Sh is obtained by the mathematical formula of formula 6, but it may be obtained by using a mathematical formula other than this.

  Here, Sh is the Sherwood number, Re is the Reynolds number, and Sc is the Schmitt number. The Reynolds number and the Schmidt number can be obtained by the following equations 7 and 8.

In the above equation, d is the kiln inner diameter (m), V _f is the free board gas flow rate (m / s), ρ _f is the free board gas density (kg / m ³ ), and μ _f is the free board gas viscosity (kg / ms). ), D is the diffusion coefficient (m ² / s).

The gas boundary film mass transfer coefficient K _f can be obtained from Equation 9 using the Sherwood number described above.

Here, the diffusion coefficient D, a major diffusion material SO _2, the other components from the N ₂ predominates, using the mutual diffusion coefficient of SO ₂ and N _2.

(2) Raw material granulation Cement raw material produces a melt (oxide solution) at around 1250 ° C, and the melt reaches about 25% of the total temperature at around 1450 ° C, which is the highest temperature. Since the cement kiln 2 rotates at 1 to 3 rpm, the raw material is gradually granulated after the melt is formed, and becomes a clinker having a diameter of about 30 mm when it reaches before the kiln. At this time, it is said that the molten salt containing calcium sulfate as a main component is granulated, and the molten salt is said to be unevenly distributed in the center, but in this embodiment, the granulation is completed relatively quickly. The molten salt is considered to be uniformly distributed in the clinker. When the temperature further rises, it is considered that sulfates and chlorides diffuse through the pores and volatilize from the outer periphery, and the interface gradually moves to the center. In contrast to this phenomenon, the present embodiment uses an unreacted nucleus model that assumes that there are unreacted portions (unreacted nuclei) inside the particles and that the particle diameter decreases with the reaction.
In addition, since it is considered that there is a slight gas flow between the clinker particles in the clinker bed, as shown below, the gas boundary film diffusion is also examined, and the overall substance of clinker pore diffusion and gas boundary film diffusion is examined. Calculate the movement coefficient.

<Gas film diffusion material transfer coefficient k _f >
Since the gas flow rate in the clinker bed is considered to decrease rapidly with the bed depth, as shown in FIG. 10, there is a surface layer on the bed surface where the gas flow rate in the bed is equal to the freeboard gas velocity, In the deeper part, the gas flow is considered to be zero, and the average gas flow velocity of the entire bed is calculated by tens. Here, the calculation is performed assuming that the depth of the bed surface layer is twice the particle diameter and the particle diameter is 30 mm.

In Equation 10, U is the gas flow rate in the clinker bed, S _s is the surface layer area (m ² ) in the clinker bed cross section, S _b is the clinker bed cross-sectional area (m ² ), and V _sl is the gas flow rate in the surface layer. (Free board gas flow rate), d _s is the thickness (m) of the surface layer.
In the present embodiment, the Ranz-Marshall equation is used as an equation representing mass transfer between the clinker particles and the gas flowing therearound. Since the mass transfer coefficients can be calculated separately for the main diffusion substances SO ₂ and KCl, the subscript of the target substance i is added to each of the diffusion coefficient, the Sherwood number, and the Schmitt number.

In the above formulas, Sh _i is the Sherwood number, Re is the Reynolds number, Sc _i is the Schmitt number, d _p is the clinker particle diameter (m), ρ _c is the gas density in the clinker bed (kg / m ³ ), and μ _c is Gas viscosity in clinker bed (kg / ms), D _i is the diffusion coefficient (m ² / s) of substance i. Diffusion coefficient, with respect to SO _2, the mutual diffusion coefficient of SO ₂ and N _2, with respect to KCl, using mutual diffusion coefficient of KCl and N _2, respectively.

The gas boundary film mass transfer coefficient k _fi can be obtained by Equation 14 using the Sherwood number described above.

<Clinker pore diffusion material transfer coefficient k _c >
As mentioned above, since the final volatility differs between chlorine and sulfur, a double nucleus model was established in which unreacted nuclei were set for each. FIG. 11 shows a conceptual diagram thereof. This double nucleus model consists of P1: oxide solution and molten salt (chloride and sulfate) filled from the inside of the particle, P2: oxide solution and molten salt (but no chloride) (Only sulfate) and P3: a portion where the pores are filled only with the oxide solution.

Further, in this double nucleus model, the concentration distributions of SO ₂ gas and KCl gas are as shown in FIG. As can be seen from this concentration distribution, the SO ₂ gas generated by the decomposition of the sulfate has the equilibrium concentration at the outer periphery of the sulfate nucleus (P2) and the concentration gradient inside the gas boundary film as the driving force for diffusion. In addition, the KCl gas has an equilibrium concentration at the outer periphery of the chloride + sulfate nucleus (P1) and a concentration gradient inside the gas boundary film as the driving force for diffusion. Therefore, the flux per unit time on a spherical surface of a certain radius r _i (i = chlorine, sulfur) is proportional to the concentration gradient in the radial direction, as shown in Equation 15, and the proportionality constant is the effective diffusion coefficient in the pores. Become. By integrating this from the particle radius R to r _i , with the concentrations at that time being P _i and P _eqi , the equation 17 can be obtained. Here, since k _ci = J / A / (P _eqi -P _i ) from Equation ^1, by substituting J = dN / dt and A = 4πR ^2, as shown in Equation 18, the clinker pore The mass transfer coefficient k _ci can be obtained.

In Equation 18, M _i is an abundance ratio where the amount of chlorine and sulfur is 1 when the particles are uniformly present in the granulated particles. The mass transfer coefficient k _ci when the abundance ratio becomes M _i due to volatilization can be obtained from _Equation 18. FIG. 12 shows a conceptual diagram of changes in unreacted nuclei after raw material granulation. In addition, about sulfur, after K3 block which starts granulation, condensation exceeds volatilization, and abundance ratio may increase. In this case, the radius of the unreacted nuclei was not changed, and the concentration of the internal sulfur was uniformly increased by condensation. In FIG. 12, although M _s3 <M _s4 , the unreacted nucleus radius is unchanged (r _s3 = r _s4 = R), so the mass transfer coefficient of SO ₂ in the K3 and K4 blocks is M _s3 = M Calculate with _s4 = 1. The effective diffusion coefficient in the pores was set to about 1/10 of the diffusion coefficient in consideration of the porosity of the clinker and the degree of bending of the pores.

<General mass transfer coefficient>
The overall mass transfer coefficient k _i can be obtained from the gas boundary membrane diffusion mass transfer coefficient k _fi and the clinker pore diffusion mass transfer coefficient k _ci obtained as described above using the following equation.

  Next, a connection example of unit operation models in each block of the cement kiln 2 will be described. FIG. 13 is a diagram showing a connection example of the unit operation model (counterflow model: no raw material granulation) in the K2 block where the raw material is not granulated. This model is also applied to the K1 block.

  As shown in FIG. 13, in the K2 block, a flow rate division model 2, a heater model 2, an equilibrium calculation model 2 and a separator model 2 are used as unit operation models.

That is, in this model, it is assumed that a part of the freeboard gas with the flow rate Q reaches an equilibrium state with the raw material, and in the flow rate splitting model 2, the split ratio X (the mass transfer coefficient k _{f of} Formula 9 After dividing the freeboard gas flow by the division ratio obtained using the above, the equilibrium calculation model 2 performs the equilibrium calculation of the gas and the raw material divided by the flow rate division model 2, and the gas generated by this equilibrium calculation model Is separated from the solid phase or liquid phase in the separator model 2 and mixed with the freeboard gas stream. In addition, the amount of heat necessary for heating the raw material flow to the temperature set in the equilibrium calculation model 2 and the amount of heat necessary for the reaction are removed from the heater model 2 through the heat stream, so that the K2 block exits. The temperature of the free board gas flow is calculated.

  FIG. 14 is a diagram showing a connection example of the unit operation model (counterflow model: with raw material granulation) in the K6 block when the raw material is granulated to become a clinker. This model is also applied to the K3 to K5, K7 and K8 blocks.

  As shown in FIG. 14, in the K6 block, as the unit operation model, the flow division models 6-1, 6-2, 6-3, 6-4, 6-5, the heater model 6, and the equilibrium calculation model 6- 1,6-2 and separator models 6-1, 6-2, 6-3, 6-4 are used.

In this model, in order to grasp the mass transfer amount of the volatile material separately for chlorine and sulfur using the above-mentioned double nucleus model (FIG. 11), first, the flow rate dividing models 6-1 and 6-2 are used. And the separator models 6-1 and 6-2, the free board gas stream, the first gas stream containing a chloride gas such as KCl or NaCl as a volatile substance, and the gas component containing sulfur such as SO ₂ as a volatile substance. Split into a second gas stream containing. Specifically, first, the freeboard gas flow is divided by the flow rate division model 6-1 so that the later-described division ratios X _Cl and X _s become 1 or less, respectively, and then one of them is divided into the flow rate division model 6-2. Subdivide further. Next, a gas component containing sulfur such as SO ₂ is separated from one gas stream divided by the flow rate dividing model 6-2 by the separator model 6-1, and a first gas stream containing a chlorine content (flow rate Q _Cl Similarly, the separator model 6-2 separates a gas component containing a chlorine component such as KCl or NaCl from the other gas flow divided by the flow rate division model 6-2, thereby including a sulfur component. A second gas stream (flow rate Q _s ) is formed.
Thereafter, the first and second gas streams (flow rates Q _Cl , Q _s ) are divided by the flow rate dividing models 6-3 and 6-4, and the division ratios X _Cl and X _s (Equation 19 general mass transfer) are obtained. Each division is performed at a division ratio obtained using the coefficient k _i .

In this model, the raw material flow is distributed to the first raw material stream and the second raw material stream by the flow rate dividing model 6-5. Specifically, the molar flow rate of chlorine and sulfur at the inlet of the K3 block is set to 1, and the flow rate ratio of chlorine at the inlet of the K4 to K8 block is M _{Cl4 to} M _Cl8 and the flow rate ratio of sulfur is M _S4. ˜M _S8 , the quantity ratio Rs to be distributed to the second raw material stream is obtained by Rs = (M _S −M _Cl ) / M _S , and using this ratio, the raw material stream is divided into the first raw material stream and the second raw material stream. And split into After the division, in the separator 6-3, the chloride contained in the second raw material stream is separated, and the chloride is mixed with the first raw material stream, whereby the raw material stream composed of the molten salt portion of chloride / sulfate. Is connected to the equilibrium calculation model 6-1 and a raw material stream consisting of a molten salt portion consisting only of sulfate is connected to the equilibrium calculation model 6-2.

Thereafter, in the equilibrium calculation model 6-1, the equilibrium calculation of the raw material stream composed of the molten salt portion of chloride / sulfate and the first gas stream divided by the flow rate division model 6-3 is performed. -2 performs an equilibrium calculation of the raw material stream composed of a molten salt portion composed only of sulfate and the second gas stream divided by the flow rate division model 6-4, and generates the equilibrium calculation models 6-1 and 6-2. In the separator model 6-4, the gas to be separated is separated from the solid phase or liquid phase and mixed into the freeboard gas stream. In addition, the amount of heat necessary for heating the raw material stream to the temperature set in the equilibrium calculation models 6-1 and 6-2 and the amount of heat necessary for the reaction are removed from the heater model 6 through the heat stream. Calculate the temperature of the freeboard gas stream at the outlet of the K6 block.
As described above, the mass transfer amount of the volatile substance can be derived by dividing into the chlorine and sulfur, that is, considering the difference between the two in the clinker pore diffusion.

It is also possible to separately provide a raw material stream corresponding to the portion P3 not containing the molten salt of the double nucleus model of FIG. 11 and to divide the raw material stream into three parts, but the equilibrium vapor pressure of KCl or SO ₂ is It is almost determined by the composition of the molten salt, and even if it is divided into three, it is considered that the composition of each molten salt portion in P1 and P2 is not much different from the case of dividing into two, so in this model, it is divided into two. . Further, as shown in FIG. 11, the partial pressure of SO ₂ in the molten salt portion (P1) of chloride / sulfate and the molten salt portion (P2) of only sulfate is equal, and there is no volatilization of SO ₂ from P1. Therefore, in this model, a gas containing sulfur such as SO ₂ is not set as a substance that may be generated in the equilibrium calculation model 6-1.

In this way, by combining a plurality of unit operation models, it is possible to model the chemical process in each block of the cement kiln 2 and the preheater 1, and in accordance with the combination order of these unit operation models, By sequentially executing the unit operations set in (2) and repeating the series of operations until a predetermined convergence condition is satisfied, the material balance and heat balance in the cement kiln 2 and the preheater 1 can be analyzed. At that time, if the conditions such as the temperature of the desorption zone and the firing zone, the SO ₃ concentration and the Cl concentration in the clinker are changed, the data shown in FIG. The gas concentrations of SO ₂ , KCl, NaCl, HCl, 1 Cy source SO ₃ concentration, Cl concentration, etc. can be obtained.

  Then, the data obtained by the process simulation is subjected to the multivariate regression analysis as described above, thereby deriving the raw material temperature estimation formulas (FIGS. 5 and 6) of the desorption zone and the calcining zone. The temperature distribution of the raw material in the cement kiln 2 can be estimated by actually measuring the concentration of the substance corresponding to the explanatory variable.

  Therefore, according to this embodiment, the temperature distribution of the raw material in the cement kiln 2 can be used as an operation control parameter for the cement kiln 2, and the pulverized coal combustion is performed so that the temperature distribution of the raw material is kept constant. By adjusting the burner 5, various problems caused by changes in the temperature distribution of the raw materials (for example, clinker quality variation, cyclone blockage, refractory deterioration, etc.) can be eliminated. The cement kiln can be operated in a stable state over a long period of time.

In the present embodiment, the SO ₂ concentration and chloride concentration contained in the kiln bottom gas, or the SO ₃ concentration and Cl concentration contained in the 1Cy raw material are measured, and the raw material in the cement kiln is measured based on the measurement result. Although the temperature distribution is estimated, the present invention is not limited to this. For example, the temperature distribution of the raw material in the cement kiln is obtained by combining the above-described substance concentration and other substance concentrations. Can also be estimated. For example, the O ₂ concentration is measured in the same manner as the SO ₂ concentration and chloride concentration of the kiln bottom gas, and the measured value is used for estimating the raw material temperature distribution in the cement kiln, or the kiln bottom gas or 1 Cy It is also possible to measure the concentration of other volatile components such as lead contained in the raw material, etc., and to use the measured value for estimating the raw material temperature distribution in the cement kiln.

It is a schematic block diagram which shows a cement baking process. And temperature changes in the cement kiln is a graph showing the relationship between the SO ₂ concentration and KCl concentration in kiln inlet gas. And temperature changes in the cement kiln is a graph showing the relationship between the SO ₃ concentration and Cl concentration of 1Cy material represents (a) the desorption zone, the temperature change of (b) firing zone. When changing the SO ₃ concentration and the Cl concentration in the feed temperature and the clinker in the cement kiln as an input parameter is a chart showing a change in the concentration of each substance contained in the kiln inlet gas and 1Cy material. It is a graph which shows the estimation formula of the raw material temperature of the desorption zone calculated | required by multivariate regression analysis. It is a graph which shows the estimation formula of the raw material temperature of the baking zone calculated | required by multivariate regression analysis. It is a figure for demonstrating the general flow of a process simulation. It is a figure which shows the block structure of a cement kiln. It is a figure which shows the flow of the combustion gas and raw material in a cement kiln. It is a figure for demonstrating the surface area of a clinker bed. It is a schematic diagram which shows an unreacted nucleus model. It is a conceptual diagram of an unreacted nucleus change. It is a figure which shows the example of a connection of a unit operation model when the raw material is not granulated. It is a figure which shows the example of a connection of a unit operation model when a raw material is granulated and it becomes a clinker.

Explanation of symbols

1 Preheater 2 Cement kiln 5 Pulverized coal combustion burner

Claims (5)

A first step of using a process simulation to determine the relationship between the SO ₂ concentration of the gas discharged from the kiln bottom of the cement kiln and the temperature distribution of the raw material in the cement kiln;
A _{second step} of measuring the SO ₂ concentration of the gas discharged from the kiln bottom and estimating the temperature distribution of the raw material in the cement kiln from the measured value;
So that the temperature distribution of the material in the cement kiln is kept constant, it was closed and a third step of adjusting the pulverized coal combustion burner,
The process simulation includes a first step of modeling a cement firing process by a combination of a plurality of unit operation models, and unit operations set for each of the unit operation models in accordance with a combination order of the unit operation models. A second step of analyzing the material balance and heat balance in the cement kiln by sequentially executing and repeating the series of operations until a predetermined convergence condition is satisfied,
In the first step, as a unit operation model applied to the region where the raw material is not granulated,
A flow rate division model that considers that a part of the combustion gas flowing into the region reaches an equilibrium state with the raw material, and divides the flow of the combustion gas at a corresponding division rate;
An equilibrium calculation model for calculating and outputting each flow rate and composition data when one combustion gas divided by the flow rate division model and the raw material existing in the region reach an equilibrium state;
It has a function of calculating and outputting the flow rate and composition data of the combustion gas when the combustion gas that has reached an equilibrium state with the raw material in the equilibrium calculation model and the other combustion gas divided in the flow rate division model are mixed. While using a predetermined unit operation model,
X is the division ratio, A is the reaction interface between the combustion gas and the raw material in the region, k is the mass transfer coefficient of the volatile matter between the combustion gas and the raw material in the region, and Q is the flow rate of the combustion gas flowing into the region. The division ratio X is set by X = A · k / Q,
As a unit operation model applied to the area where the raw material is granulated,
A first flow rate splitting model that forms a gas flow corresponding to each of the volatile substances of interest by dividing the flow of the combustion gas flowing into the region according to the quantity of the volatile substances of interest;
A separator model that separates other volatile substances so that only one volatile substance of interest is included in each of the gas flows formed in the first flow rate division model,
A second flow rate division model that divides each gas flow at a division ratio corresponding to each gas flow, in which part of each gas flow separated from the other volatile substances by the separator model reaches an equilibrium state with the raw material. When,
By dividing the flow of the raw material flowing into the region according to the size of the nuclei formed by the volatile substances remaining in the raw material particles, the flow of each gas divided by the second flow rate division model is divided. A third flow rate splitting model for generating a corresponding raw material flow;
Calculate and output each flow rate and composition data when each gas divided by the second flow rate division model and the corresponding raw material divided by the third flow rate division model reach an equilibrium state. Using an equilibrium calculation model and
In the second flow rate division model, the gas division ratio corresponding to the volatile substance i corresponds to Xi, the reaction interface between the combustion gas and the raw material in the above region corresponds to A, the mass transfer coefficient of the volatile substance i corresponds to ki, and the volatile substance i corresponds. Qi is the flow rate before the gas is divided, and the gas division ratio Xi corresponding to the volatile substance i is set by Xi = A · ki / Qi,
A cement kiln operation control method characterized in that a mass transfer amount between a raw material and a combustion gas in the above region is obtained for each volatile substance i by a combination of these unit operation models . A first step of using a process simulation to determine the relationship between the SO ₃ concentration of the 1Cy raw material and the temperature distribution of the raw material in the cement kiln using the raw material immediately before being put into the cement kiln as the 1Cy raw material;
A second step of measuring the SO ₃ concentration of the 1Cy raw material and estimating the temperature distribution of the raw material in the cement kiln from the measured value;
So that the temperature distribution of the material in the cement kiln is kept constant, it was closed and a third step of adjusting the pulverized coal combustion burner,
The process simulation includes a first step of modeling a cement firing process by a combination of a plurality of unit operation models, and unit operations set for each of the unit operation models in accordance with a combination order of the unit operation models. A second step of analyzing the material balance and heat balance in the cement kiln by sequentially executing and repeating the series of operations until a predetermined convergence condition is satisfied,
In the first step, as a unit operation model applied to the region where the raw material is not granulated,
A flow rate division model that considers that a part of the combustion gas flowing into the region reaches an equilibrium state with the raw material, and divides the flow of the combustion gas at a corresponding division rate;
An equilibrium calculation model for calculating and outputting each flow rate and composition data when one combustion gas divided by the flow rate division model and the raw material existing in the region reach an equilibrium state;
It has a function of calculating and outputting the flow rate and composition data of the combustion gas when the combustion gas that has reached an equilibrium state with the raw material in the equilibrium calculation model and the other combustion gas divided in the flow rate division model are mixed. While using a predetermined unit operation model,
X is the division ratio, A is the reaction interface between the combustion gas and the raw material in the region, k is the mass transfer coefficient of the volatile matter between the combustion gas and the raw material in the region, and Q is the flow rate of the combustion gas flowing into the region. The division ratio X is set by X = A · k / Q,
As a unit operation model applied to the area where the raw material is granulated,
A first flow rate splitting model that forms a gas flow corresponding to each of the volatile substances of interest by dividing the flow of the combustion gas flowing into the region according to the quantity of the volatile substances of interest;
A separator model that separates other volatile substances so that only one volatile substance of interest is included in each of the gas flows formed in the first flow rate division model,
A second flow rate division model that divides each gas flow at a division ratio corresponding to each gas flow, in which part of each gas flow separated from the other volatile substances by the separator model reaches an equilibrium state with the raw material. When,
By dividing the flow of the raw material flowing into the region according to the size of the nuclei formed by the volatile substances remaining in the raw material particles, the flow of each gas divided by the second flow rate division model is divided. A third flow rate splitting model for generating a corresponding raw material flow;
Calculate and output each flow rate and composition data when each gas divided by the second flow rate division model and the corresponding raw material divided by the third flow rate division model reach an equilibrium state. Using an equilibrium calculation model and
In the second flow rate division model, the gas division ratio corresponding to the volatile substance i corresponds to Xi, the reaction interface between the combustion gas and the raw material in the above region corresponds to A, the mass transfer coefficient of the volatile substance i corresponds to ki, and the volatile substance i corresponds. Qi is the flow rate before the gas is divided, and the gas division ratio Xi corresponding to the volatile substance i is set by Xi = A · ki / Qi,
A cement kiln operation control method characterized in that a mass transfer amount between a raw material and a combustion gas in the above region is obtained for each volatile substance i by a combination of these unit operation models . A first step of using a process simulation to determine the relationship between the SO ₂ concentration and chloride concentration of the gas discharged from the kiln bottom of the cement kiln and the temperature distribution of the raw material in the cement kiln;
A second step of measuring the SO ₂ concentration and chloride concentration of the gas discharged from the kiln bottom and estimating the temperature distribution of the raw material in the cement kiln from the measured values;
So that the temperature distribution of the material in the cement kiln is kept constant, it was closed and a third step of adjusting the pulverized coal combustion burner,
The process simulation includes a first step of modeling a cement firing process by a combination of a plurality of unit operation models, and unit operations set for each of the unit operation models in accordance with a combination order of the unit operation models. A second step of analyzing the material balance and heat balance in the cement kiln by sequentially executing and repeating the series of operations until a predetermined convergence condition is satisfied,
In the first step, as a unit operation model applied to the region where the raw material is not granulated,
A flow rate division model that considers that a part of the combustion gas flowing into the region reaches an equilibrium state with the raw material, and divides the flow of the combustion gas at a corresponding division rate;
An equilibrium calculation model for calculating and outputting each flow rate and composition data when one combustion gas divided by the flow rate division model and the raw material existing in the region reach an equilibrium state;
It has a function of calculating and outputting the flow rate and composition data of the combustion gas when the combustion gas that has reached an equilibrium state with the raw material in the equilibrium calculation model and the other combustion gas divided in the flow rate division model are mixed. While using a predetermined unit operation model,
X is the division ratio, A is the reaction interface between the combustion gas and the raw material in the region, k is the mass transfer coefficient of the volatile matter between the combustion gas and the raw material in the region, and Q is the flow rate of the combustion gas flowing into the region. The division ratio X is set by X = A · k / Q,
As a unit operation model applied to the area where the raw material is granulated,
A first flow rate splitting model that forms a gas flow corresponding to each of the volatile substances of interest by dividing the flow of the combustion gas flowing into the region according to the quantity of the volatile substances of interest;
A separator model that separates other volatile substances so that only one volatile substance of interest is included in each of the gas flows formed in the first flow rate division model,
A second flow rate division model that divides each gas flow at a division ratio corresponding to each gas flow, in which part of each gas flow separated from the other volatile substances by the separator model reaches an equilibrium state with the raw material. When,
By dividing the flow of the raw material flowing into the region according to the size of the nuclei formed by the volatile substances remaining in the raw material particles, the flow of each gas divided by the second flow rate division model is divided. A third flow rate splitting model for generating a corresponding raw material flow;
Calculate and output each flow rate and composition data when each gas divided by the second flow rate division model and the corresponding raw material divided by the third flow rate division model reach an equilibrium state. Using an equilibrium calculation model and
In the second flow rate division model, the gas division ratio corresponding to the volatile substance i corresponds to Xi, the reaction interface between the combustion gas and the raw material in the above region corresponds to A, the mass transfer coefficient of the volatile substance i corresponds to ki, and the volatile substance i corresponds. Qi is the flow rate before the gas is divided, and the gas division ratio Xi corresponding to the volatile substance i is set by Xi = A · ki / Qi,
A cement kiln operation control method characterized in that a mass transfer amount between a raw material and a combustion gas in the above region is obtained for each volatile substance i by a combination of these unit operation models . A first step of using a process simulation to determine the relationship between the SO ₃ concentration and the Cl concentration of the 1Cy raw material and the temperature distribution of the raw material in the cement kiln using the raw material immediately before being put into the cement kiln as the 1Cy raw material. ,
A second step of measuring the SO ₃ concentration and the Cl concentration of the 1Cy raw material and estimating the temperature distribution of the raw material in the cement kiln from the measured values;
So that the temperature distribution of the material in the cement kiln is kept constant, it was closed and a third step of adjusting the pulverized coal combustion burner,
The process simulation includes a first step of modeling a cement firing process by a combination of a plurality of unit operation models, and unit operations set in each of the unit operation models in accordance with a combination order of the unit operation models. A second step of analyzing the mass balance and heat balance in the cement kiln by sequentially executing and repeating the series of operations until a predetermined convergence condition is satisfied,
In the first step, as a unit operation model applied to the region where the raw material is not granulated,
A flow rate division model that considers that a part of the combustion gas flowing into the region reaches an equilibrium state with the raw material, and divides the flow of the combustion gas at a corresponding division rate;
An equilibrium calculation model for calculating and outputting each flow rate and composition data when one combustion gas divided by the flow rate division model and the raw material existing in the region reach an equilibrium state;
It has a function of calculating and outputting the flow rate and composition data of the combustion gas when the combustion gas that has reached an equilibrium state with the raw material in the equilibrium calculation model and the other combustion gas divided in the flow rate division model are mixed. While using a predetermined unit operation model,
X is the division ratio, A is the reaction interface between the combustion gas and the raw material in the region, k is the mass transfer coefficient of the volatile matter between the combustion gas and the raw material in the region, and Q is the flow rate of the combustion gas flowing into the region. The division ratio X is set by X = A · k / Q,
As a unit operation model applied to the area where the raw material is granulated,
A first flow rate splitting model that forms a gas flow corresponding to each of the volatile substances of interest by dividing the flow of the combustion gas flowing into the region according to the quantity of the volatile substances of interest;
A separator model that separates other volatile substances so that only one volatile substance of interest is included in each of the gas flows formed in the first flow rate division model,
A second flow rate division model that divides each gas flow at a division ratio corresponding to each gas flow, in which part of each gas flow separated from the other volatile substances by the separator model reaches an equilibrium state with the raw material. When,
By dividing the flow of the raw material flowing into the region according to the size of the nuclei formed by the volatile substances remaining in the raw material particles, the flow of each gas divided by the second flow rate division model is divided. A third flow rate splitting model for generating a corresponding raw material flow;
Calculate and output each flow rate and composition data when each gas divided by the second flow rate division model and the corresponding raw material divided by the third flow rate division model reach an equilibrium state. Using an equilibrium calculation model and
In the second flow rate division model, the gas division ratio corresponding to the volatile substance i corresponds to Xi, the reaction interface between the combustion gas and the raw material in the above region corresponds to A, the mass transfer coefficient of the volatile substance i corresponds to ki, and the volatile substance i corresponds. Qi is the flow rate before the gas is divided, and the gas division ratio Xi corresponding to the volatile substance i is set by Xi = A · ki / Qi,
A cement kiln operation control method characterized in that a mass transfer amount between a raw material and a combustion gas in the above region is obtained for each volatile substance i by a combination of these unit operation models . To produce a clinker cement kiln operation control to the operation control method according to any one of claims 1 to 4, a manufacturing method of cement, characterized in that the production of cement from the clinker.

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