JPH028238B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a heating temperature control method and device for a forced combustion gas kiln, and its field of application is a forced combustion gas kiln used for heat treatment of objects to be heated such as ceramic products. (Prior Art) As shown in Fig. 5, a burner f is placed on the side surface of the lower part of a furnace a filled with objects to be heated such as ceramic products.
In the forced combustion type gas kiln, in which forced combustion gas flame is blown into the kiln ceiling b and discharged from the flame exhaust port d provided in the kiln floor c to the chimney e, the initial stage of heating is A gradient occurs between the temperature of the kiln ceiling b and the temperature of the kiln floor c, and it takes time to average the temperature distribution inside the kiln. Figure 6 shows the forced combustion type gas kiln a that uses LP gas and has a kiln capacity of 4M ³ as shown in Figure 5. Temperature measurement sensors are installed on the kiln ceiling section "Ten A" and the kiln floor section "Root B". In order to suppress the temperature difference between "Heaven A" and "Root B" as much as possible, the gas pressure scale P shown on the vertical axis on the right side of the figure
According to (m/mAq), the first 2 hours is 50m/mAq
After that time, increase the pressure stepwise as shown in the diagram, and after 7.5 hours have passed, increase the maximum pressure.
By supplying fuel at 450 m/mAq, dry dough of ceramic fired products was packed into the kiln as usual and combustion control was performed, and the temperature rise over time of "Ten A" and "Root B" was measured. The graph shown is
Despite heating to minimize the temperature difference between "Ten A" and "Root B", after 1 hour of heating, "Ten A" rose to 440℃, but "Root B" is 260
℃, a temperature gradient of about 180°C had already occurred, and the temperature gradient continued after that, and it took about 9 hours until "Ten A" and "Root B" reached almost the same temperature and the temperature gradient almost disappeared. The graph in Figure 6 recognizes that even if there is a temperature gradient between "Top A" and "Root B", it is possible to carry out sinter firing, and the gas supply amount is maximized after 7.5 hours. , the temperature of "Heaven A" is
After reaching 1120℃, it takes 2 hours to raise the kiln temperature to 1230℃, and the amount of gas required is 173.8Kg (8Hr), assuming that the firing time is until the temperature gradient is almost eliminated. The amount within the baking time is
The total usage amount was 60.5Kg (2Hr) and 234.3Kg (10Hr). (Problems to be Solved by the Invention) The problems to be solved by the present invention are to reduce gas consumption and shorten time. In other words, if the temperature gradient between "Heaven A" and "Root B" is large as shown in Figure 5,
The time required for the temperature gradient to almost disappear increases, and the amount of gas consumed also increases in proportion to that time. In the past, this has been overlooked as a matter of course, but the present invention takes this point into account and aims to develop a method and device that shorten the required time as much as possible, and at the same time, make it possible to reduce gas consumption. be. (Means for Solving the Problems) The present invention aims to solve the problems mentioned in the previous section. In an inverted-flame gas kiln, a gas flame is blown into the kiln ceiling and discharged into the chimney from a flame exhaust port in the kiln floor. The present invention relates to a heating temperature control method for a forced combustion gas kiln characterized by adding flame diluting gas such as outside air or exhaust gas that acts to weaken the buoyancy of the gas. Further, the second invention is characterized in that the combustion flame blowing burner disposed below the forced combustion type upside-down gas kiln is provided with a blowing pipe for diluting gas such as outside air or exhaust gas to suppress the buoyancy of the blown gas flame. This relates to a heating temperature control device for a forced combustion gas kiln. A preferred embodiment of the invention will now be described. (Example) Figs. 1 to 3 show an example of the second invention of the present invention, Fig. 1 is a longitudinal sectional front view of a collapsed type forced combustion gas kiln to which the second invention is applied, and Fig. 2 is the same side view, 3rd
The figure is a longitudinal sectional view of a part of another embodiment. A gas burner 8 is inserted into each gas flame inlet 2 provided horizontally and vertically at the bottom of both sides of the kiln 1, and a large number of flame exhaust channels 4 are provided inside the kiln floor 3, which communicate with a chimney 7 at the rear. A large number of flame exhaust ports 5 are provided on the upper surface of the kiln floor 3 and communicate with the flame exhaust path 4, and a gas flame abutting wall is provided between the gas flame inlet 2 and the upper surface of the kiln floor 3. 6
is set low. A gas supply pipe 9 and an air supply pipe 10 whose supply amount is controlled by a blower 11 are connected to the gas burner 8 outside the gas furnace 1 . The second aspect of the present invention is that in the above-described known kiln configuration, an exhaust gas return pipe 12 is passed through the inside of the chimney 7, a Shiritzko fan 13 is interposed in the return pipe 12, and a gas flame is blown into the tip of the exhaust gas return pipe 12. It opens at the outer periphery of the tip of the gas flame spout of the burner 8 inserted into the mouth 2. The exhaust gas return pipe can be passed through the inside of the gas burner 8, and its tip can be opened as shown by the chain line in FIG. The amount of exhaust gas sucked into the exhaust gas return pipe 12 is determined by a manual operation, and flame dilution gas is blown into the kiln. The temperature of the blowing is 700-500℃
It is. In the above, the third exhaust gas return pipe 12 is replaced with the exhaust gas return pipe 12.
As shown in the figure, an independent outside air blowing pipe 14 may be provided, and the blowing amount may be determined by a valve 15. The temperature of the flame dilution gas blown in from the outside air suction pipe 14 is 15°C to 25°C. A first aspect of the present invention uses the furnace illustrated in FIGS. 1 to 3 to control the heating temperature. (Function) Fig. 4 shows the kiln shown in Fig. 3 (see Fig. 1) used, and the dry dough of the ceramic fired product is stuffed in the usual way, and the kiln is placed in the "Ten A" and the kiln floor part "Root B". A temperature measurement sensor was installed at the bottom, and through trial and error, the correlation ratio between the supply pressure of diluted outside air and the supply pressure of LP gas was determined according to the gas pressure scale P (m/mAq) shown on the vertical axis on the right side of the figure. , FIG. 6 is a graph of the measurement results obtained by applying the heating temperature control of the first invention based on the outside air supply shown by the dotted line and the LP gas supply shown by the solid line, and FIG.
The graphs in FIG. 4 and FIG. 6 can be compared with each other because they are graphs of combustion control performed with the outside air blowing pipe 14 closed (see figure). FIG. 7 is a graph in which the heat curve of FIG. 4 and the heat curve of FIG. 6 are shown together to facilitate comparison in order to clarify this comparison. The first aspect of the present invention shown in the graph of FIG. 4 is to set the supply pressure of combustion gas to 65 m/mAq for the first 1 hour, which is slightly higher than the supply pressure in FIG.
Increase the pressure to 100 m/mAq for 1 hour, further increase the pressure every 0.5 hours, and after 6.0 hours, increase the gas supply pressure to 600 m/mAq, and supply outside air as flame dilution gas from the beginning. This figure shows the result of combustion control in which the supply was stopped after 6.5 hours had passed, when the thermal gradient between "Ten A" and "Root B" disappeared, and the combustion gas flame was used to perform scorching. Flame diluting gas (outside air) is added to lower the temperature of the flame and weaken the buoyancy of the gas flame, which lowers the temperature of the flame and weakens the buoyancy of the gas flame, so it reaches ``Heaven A''. The total amount of gas flames is suppressed,
Before the gas flame rises to "Top A", a part of it falls to "Root B" through the gap between the heated materials, and the heat curve of "Top A" shown by the solid line and "Rot B" shown by the dotted line are separated. "The temperature gradient of the heat curve is maintained at around 50℃, and the temperature gradient can be reduced to zero after about 6.5 hours. The average kiln temperature at that time is 1120℃ to 1130℃, and then It is clearly shown that the amount of gas flame blown into the first and second halves of the kiln firing, which is carried out by raising the kiln temperature to 1230°C, can be kept larger than the graph in Figure 6. The required amount of gas is 161.9, assuming that the firing time is until the temperature gradient disappears.
Kg (6.5Hr), the amount within the sleeping time is 32.4Kg (1Hr)
The total usage amount is 194.3Kg (7.5Hr), and the supply amount of dilution gas (outside air) during the combustion time is 4435M ³ (6.5Hr)
It was hot. Below is a table that makes the comparison clear.

[Table] (Note) 〓Firing gas amount〓 is the amount of gas consumed during the firing time. 〓Hey
The amount of gas 〓 is the amount of gas consumed during the sleeping time.
FIG. 4 is a graph illustrating the effect of the first aspect of the present invention, and the effect of the present invention can be inferred from this graph. (Effect) The first aspect of the present invention is to add flame diluting gas such as outside air or exhaust gas to the gas flame blown from the burner into the inside of the kiln, which acts to lower the temperature of the gas flame and weaken the buoyancy of the flame. This method suppresses the rise of flame gas to the kiln ceiling and allows some of it to pass through the objects to be fired on the kiln floor during its rise and fall to the kiln floor. Even if the gas is sent to the
Unlike the conventional heating method in which the temperature of the kiln ceiling is raised and then the kiln floor is heated using the heating power, the heating temperature of the kiln floor is low and does not produce a noticeable temperature gradient, and only a slight temperature gradient occurs. However, it is possible to perform almost ideal combustion control that averages out the kiln temperature quickly in terms of time, so even if a large amount of combustion gas is blown in from the beginning of heating and the combustion consumption is increased, the result will be lower. In terms of shortening the time it takes for the temperature gradient to disappear, it can reduce fuel consumption and maintain a large amount of flame gas injection at the beginning of the firing process and at the end of the temperature gradient elimination. , there is no risk of new temperature gradients occurring, and if the heating time can be shortened and the kiln operating rate can be improved, the effect and fuel saving effect will be significant, and the kiln heating temperature control can be sufficiently effective. . Further, the second invention simplifies the construction of the kiln by having a diluent gas blowing pipe for lowering the temperature of the blown gas flame and suppressing the buoyancy of the flame opened on the outer periphery of the combustion flame blowing burner. 1st
This invention has the effect of easily implementing the invention.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view of a forced combustion type gas kiln according to the second invention of the present invention, FIG. 2 is a side view of the same, FIG. 3 is a partial longitudinal sectional front view showing another embodiment, and FIG. The figure is a graph showing the heat curve of the second invention of the present invention, and also shows the respective supply curves of combustion gas and flame dilution gas. Fig. 6 is a graph showing the heat curve of conventional heating temperature control, and Fig. 7 also shows the supply pressure of combustion gas, and Fig. 7 is a graph of the second invention of the present invention shown in Fig. 4. The heat curve of
7 is a graph showing the heat curve of the conventional method shown in FIG. 6. 1 → Kiln, 2 → Gas flame inlet, 3 → Kiln floor, 4 → Flame exhaust path, 7 → Chimney opening, 8 → Gas burner, 12 → Exhaust gas return pipe, 14 → Outside air blowing pipe.

Claims (1)

[Claims] 1. An overturned flame type in which a forced combustion gas flame is blown from a burner placed on the lower side of the kiln, the gas flame is blown up to the kiln ceiling, and is discharged into the chimney from a flame exhaust port provided on the kiln floor. In a gas kiln, a forced combustion gas kiln is characterized in that a flame diluting gas such as outside air or exhaust gas is added to the gas flame blown into the kiln from a burner to lower the temperature of the flame and weaken the buoyancy of the gas flame. How to control the heating temperature of a kiln. 2. A blowing pipe for diluent gas such as outside air or exhaust gas is opened in the combustion flame blowing burner placed below the forced combustion type upside-down gas kiln to lower the temperature of the blown gas flame and suppress the buoyancy of the gas flame. A heating temperature control device for a forced combustion gas kiln, characterized in that the heating temperature control device is provided with a forced combustion type gas kiln.