JPH068682B2 - Droplet size control device for jet black liquor in recovery boiler - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement in a droplet diameter control device for black liquor that is jetted as droplets to a recovery boiler in a pulp production process.

[Conventional technology]

Generally, in a pulp production process, a recovery boiler is used that burns black liquor generated as a waste liquid in a chip cooking process to generate steam and recovers a raw material for chemicals for chip cooking. In this recovery boiler, black liquor is sprayed into the furnace by the black liquor injection mechanism, this black liquor is suspended and dried to form a char bed at the bottom of the furnace, and steam is generated by burning this char bed, In addition, the drug raw material is recovered by the reduction reaction at that time. Therefore, in order for this jet black liquor to operate the boiler stably,
And plays an important role in obtaining a good combustion state. In other words, if the droplet size of the jetted black liquor is too large, the dry state is poor and the water drops onto the char bed without completely evaporating, so the heat required for drying is taken away at the bottom of the furnace and at the same time the combustion is delayed. And the formation of a high-temperature reducing atmosphere necessary for the reduction reaction in the furnace may be hindered, and combustion failure may occur. In addition, the amount of accumulated charbed may be too high and may fall off, which may clog the air outlet. On the other hand, if the droplet size of the jetted black liquor is too small, it will dry quickly and burn before the black liquor reaches the char bed, so the amount of heat generated near the furnace bottom will be insufficient. Also, there is a possibility that the formation of the high-temperature reducing atmosphere may be hindered, the amount of scattered dust may increase, and the amount of dust attached to the boiler tube may increase, which may hinder the operation.

Therefore, it is necessary to control the droplet size of the jetting black liquor so that the time until the jetting black liquor reaches the char bed and the time for floating drying coincide with each other. However, it was difficult to directly control the droplet size of the jet black liquor. conventionally,
The boiling temperature of the black liquor is estimated from the concentration of the jetted black liquor, and the set value of the black liquor temperature is set to a value that is a certain temperature lower than this boiling temperature,
The droplet size of the jetted black liquor is controlled by adjusting the temperature of the black liquor to reach this set temperature. In this case, paying attention to the fact that the charbed level increases when the droplet size is large, and conversely decreases when the droplet size is small, and the set value of the black liquor temperature is set so that the charbed level becomes constant. There was also compensation. Further, when the jetting pressure of the black liquor to be jetted is high, the droplet size becomes small, and conversely, when the jetting pressure is low, it becomes large. There was also.

[Problems to be solved by the invention]

However, if the furnace temperature of the recovery boiler changes, the floating drying time of the jet black liquor injected into the boiler changes. Therefore, even if the black liquor temperature is set so that an appropriate droplet diameter is obtained by the conventional droplet diameter control means, the set value is not an appropriate droplet diameter due to the change in the furnace temperature. There was a fear. The charbed level compensating means and the injection pressure compensating means cannot fully compensate for such deviation of the set value. Therefore, when the temperature in the furnace changes, the droplet size of the jetted black liquor changes, and an optimum combustion state cannot be obtained.

Therefore, the present invention can obtain a proper droplet size of the jet black liquor with respect to changes in the furnace temperature in the recovery boiler, can always maintain an optimum combustion state, and save labor and stabilize the pulp production process. An object of the present invention is to provide a droplet size control device for jet black liquor in a recovery boiler to be obtained.

[Means for solving problems]

The present invention is characterized by taking the following means in order to solve the above problems and achieve the object. That is,
The boiling point of the black liquor is estimated based on the temperature of the black liquor injected into the recovery boiler, and the set temperature of the black liquor is calculated based on the estimated boiling point, and the furnace temperature of the recovery boiler is set. The temperature of the black liquor is detected, the set temperature of the black liquor is compensated based on the detected temperature in the furnace, and the temperature of the black liquor is adjusted to the compensated set temperature.

[Action]

By taking such means, even if the temperature inside the furnace of the recovery boiler changes, the deviation of the black liquor temperature set value for obtaining the optimum droplet size due to the temperature change inside the furnace is compensated.

〔Example〕

Hereinafter, the basic principle for carrying out the present invention will be described. The droplet size of the black liquor injected to the recovery boiler depends on the black liquor injection mechanism, but mainly the pressure, temperature, concentration, and
Varies depending on black liquor properties. Then, generally, the temperature of the black liquor is adjusted to obtain an appropriate droplet size. In this case, if the temperature of the black liquor is increased, the viscosity and the surface tension are reduced, and the ejected droplet size is reduced. Therefore, since the surface area per volume is large, the drying time is shorter than the floating time. Then, if the temperature of the black liquor is raised too much, the combustion is carried out during the suspension. On the other hand, when the temperature of the black liquor is lowered, the droplet size becomes larger and the surface area per volume becomes smaller, so that the drying time becomes longer than the floating time. Therefore, it takes a drying time after landing on the char bed and absorbs heat required for drying from the surroundings, which impedes the reduction reaction at high temperature.

Moreover, even if the droplet size of the black liquor sprayed from the black liquor jetting mechanism is the same, when the temperature inside the furnace of the recovery boiler is high, the amount of heat given to the droplets from the surroundings increases and the drying time Due to the shorter length, drying may end before landing on the char bed, and combustion may start during suspension. On the other hand, when the temperature in the furnace is low, the floating time is shorter than the drying time, and the droplets are not dried within the time until landing on the char bed.

By the way, conventionally, a value lower than the boiling point of the black liquor by a certain temperature is set as an appropriate value of the black liquor temperature, and the black liquor temperature is adjusted to match the appropriate value.
At this time, an operator empirically adjusts the constant temperature difference from the boiling point while observing the combustion state. In addition, the set temperature was compensated by changing the charbed level or the black liquor pressure as needed. However, this conventional black liquor temperature control means, when the furnace temperature of the recovery boiler changes,
The operator has to empirically adjust the black liquor temperature setting value by looking at the combustion state in the furnace and the shape of the char bed,
It was difficult to obtain a proper set value.

Therefore, in the present invention, the furnace temperature is detected, and the black liquor temperature set value is automatically compensated as a function of this furnace temperature to obtain an appropriate black liquor temperature set value.

FIG. 1 is a system diagram showing the configuration of the first embodiment of the present invention. In the figure, 10 is a recovery boiler, and the injection black liquor 11 is made into droplets by the injection gun 12 and is injected into the boiler 10. The jetted black liquor 11
Is float-dried in the recovery boiler 10 and landed on the bottom of the furnace to form a char bed 13. Then, a reduction reaction by a high-temperature atmosphere above the char bed 13 is carried out, sodium sulfide by the reduction reaction, such as sodium sulfate in the injection black liquor _{11 (Na 2 SO 4) (} Na 2 S) , and the sodium carbonate _(Na 2 CO ₃ ) And the like as smelt 14 and collected from the spoutro 15 and reused as a pulp cooking chemical.

On the other hand, the organic components in the jet black liquor 11 undergo reduction combustion on the surface of the char bed 13 by the combustion air 16 a supplied to the furnace bottom portion of the recovery boiler 10. Further, the incompletely combusted portion is the combustion air 1 supplied to the central portion of the recovery boiler 10.
6b completely burns in the upper part of the char bed 13. Then, the combustion gas rises as shown by arrow A in the figure,
After exchanging heat with the working fluid in the boiler heat transfer tube 17 to generate steam, it is discharged as exhaust gas to the outside of the system as shown by an arrow B in the figure.

Further, in FIG. 1, reference numeral 18 denotes a chip digester, which produces a pulp 22 by digesting a chip material 19 put in the chip digester 18 with a chip digesting chemical 20 and steam 21. Has become. At this time, the waste liquid 23 discharged from the chip digester 18 is
In the oxidation tower 24, it is contacted with the air 25 to be oxidized, concentrated in the concentrator 26, and then mixed with the sodium sulfate 28 in the mixing tank 27 to become black liquor 29. And this black liquor 9
Is heated by the steam 31 in the heater 30 and is sprayed as the black liquor 11 from the injection gun 12 into the recovery boiler 10 through the black liquor supply line 32.

On the other hand, the jet black liquor 11 is connected to the jet black liquor supply line 32.
There are provided a temperature detector 33 for detecting the temperature and a solid content concentration estimator 34 for estimating the solid content concentration which is a function of the refractive index of the black liquor solution by a photorefractive densitometer.
The output terminal of the solid content concentration estimator 34 is the boiling point calculator 35.
Connected to. The boiling point calculator 35 calculates the black liquor 2 from the solid content concentration estimated by the solid content concentration estimator 34.
The boiling point of 9 is estimated and calculated, and the output terminal of the boiling point calculator 35 is connected to the first adder 36. The first adder 36 calculates the set value of the black liquor temperature by adding the boiling point calculated by the boiling point calculator 35 and the constant temperature difference set by the temperature difference setting unit 37. There
The output terminal of the first adder 36 is connected to the second adder 38.

Further, in FIG. 1, reference numeral 39 is a furnace temperature detector for detecting the temperature in the recovery boiler 10. The output end of the furnace temperature detector 39 is connected to a furnace temperature compensation value calculator 40. There is. The furnace temperature compensation value calculator 40 calculates a furnace temperature compensation value for compensating the black liquor temperature set value based on the furnace temperature detected by the furnace temperature detector 39. The output terminal is connected to the second adder 38.

In the second adder 38, the first adder 3
The black liquor temperature set value given from 6 and the in-furnace temperature compensation value given from the in-furnace temperature compensation calculator 40 are added to compensate the black liquor temperature set value, the output end of which is a temperature controller. The temperature detector 33 is connected to the other input terminal of the temperature controller 41. The temperature controller 41 sets the black liquor temperature set value in which the temperature of the jet black liquor 11 detected by the temperature detector 33 is compensated by the furnace temperature calculated by the second adder 38. Therefore, the opening of the steam control valve 42 is adjusted, and the amount of the steam 31 supplied to the heater 30 is adjusted according to the opening of the steam control valve 42. The temperature of the jetted black liquor 11 heated by heating is controlled.

In the present embodiment thus configured, the temperature inside the recovery boiler 10 is detected by the furnace temperature detector 39.
Then, the in-reactor temperature compensation value calculator 40 calculates the in-reactor temperature compensation value based on the in-reactor temperature detected by the in-reactor temperature detector 39.

FIG. 2 is a diagram showing the relationship between the in-furnace temperature and the in-reactor temperature compensation value. When the normal in-reactor temperature, that is, the in-reactor temperature reference value P, the in-reactor temperature compensation value is set to 0 [° C.]. To do. Then, as the temperature inside the furnace becomes higher, the drying time of the liquid droplets becomes shorter, so that the furnace temperature compensation value calculator 40 lowers the black liquor temperature set value calculated by the first adder 36. The inside temperature compensation value is calculated, and conversely, the inside temperature compensation value is calculated so that the black liquor temperature set value is increased when the inside temperature decreases.

On the other hand, in the first adder 36, a black liquor temperature set value that is lower than the boiling point of the black liquor 29 estimated and calculated by the boiling point calculator 35 by a constant temperature set by the temperature difference setter 37 is calculated,
It is provided to the second adder 38. Then, this second
In the adder 38, the black liquor temperature set value and the in-furnace temperature compensation value are added, and the black liquor temperature set value compensated by the in-furnace temperature is calculated. Then, the compensated black liquor temperature set value is output to the temperature controller 41, and in this temperature regulator 41, the temperature of the jetted black liquor 11 detected by the temperature detector 33 and the compensated black liquor temperature setting value are set. The value is compared, and a valve opening command signal is output to the steam control valve 42 based on the deviation. As a result, the amount of the steam 31 supplied to the heater 30 is controlled, and the temperature of the injected black liquor 11 becomes equal to the black liquor temperature set value compensated by the furnace temperature,
The droplet size of the jetted black liquor becomes an appropriate size.

As described above, according to this embodiment, the in-reactor temperature compensation value is calculated based on the relationship between the in-reactor temperature and the droplet diameter according to the change in the in-reactor temperature of the recovery boiler 10, and the in-reactor temperature compensation value is calculated. Compensates the black liquor temperature setting value. Therefore, the change in the black liquor temperature set value due to the change in the furnace temperature can be easily compensated, and the temperature of the jet black liquor 11 can be set to a temperature at which an optimum droplet size can always be obtained. As a result, the recovery boiler 10 is always operated in an optimal combustion state, and labor saving and stabilization of the pulp production process can be achieved.

Next, another embodiment of the present invention will be described.

FIG. 3 is a system diagram showing the configuration of the main part in the second embodiment of the present invention. The present embodiment is a char bed level that compensates the black liquor temperature set value calculated by the first adder 36 in the first embodiment according to the level of the char bed 13 accumulated in the recovery boiler 10. Compensation means and ejection pressure compensating means for compensating the black liquor temperature set value according to the ejection pressure of the ejection black liquor 11 are provided.

In FIG. 3, reference numeral 43 is a scanning pyrometer for detecting the temperature of the char bed 13 together with the temperature inside the furnace of the recovery boiler 10. The detection signal of the scanning pyrometer 43 is a furnace temperature calculator 44 and the char bed level. It is given to the calculator 45. The furnace temperature calculator 4
Reference numeral 4 is for calculating the furnace temperature from the output signal of the scanning pyrometer 43, and the output is given to the furnace temperature compensation value calculator 40, and the furnace temperature is calculated in the same manner as in the first embodiment. The compensation value is calculated.

On the other hand, the charbed level compensation calculator 45 calculates the charbed level from the output signal of the scanning pyrometer 43, and the output thereof is given to the charbed level controller 46, and this level controller 4
6, the charbed level is adjusted by the charbed level setter 47 to be the set charbed level, and the charbed level compensation value is output to the first adder 36. Then, in the first adder 36,
The boiling point temperature estimated by the boiling point calculator 35 and the temperature difference set by the temperature difference setter 37 are added together to calculate a black liquor temperature set value compensated according to the char bed level.

On the other hand, in FIG. 3, reference numeral 48 denotes a pressure detector which is provided in the jet black liquor supply line 32 and detects the jet pressure of the jet black liquor 11. The detection signal from the pressure detector 48 is a pressure compensation value calculator 49. Is output to. Then, the pressure compensation value calculator 49 calculates the pressure compensation value for the preset detected pressure, and the third adder 50 calculates the black liquor temperature set value output from the first adder 36. Is added. As a result, the black liquor temperature set value compensated according to the injection pressure is calculated and output to the second adder 38.

Generally, during operation of the recovery boiler 10, the injection gun 12 may be partially changed in order to stabilize the shape and position of the char bed level 13 and the combustion state. Even with the same injection gun 12, the injection black liquor 11 adheres to the vicinity of the injection port, or due to secular change, the injection gun 12
The characteristics of may change. Therefore, the compensation by the injection pressure as described above is required.

In this way, the black liquor temperature set value calculated from the boiling point and the constant temperature difference is used as the char bed level compensation value output from the char bed level controller 46 and the pressure compensation value calculator 4
By compensating with the pressure compensation value output from 9, the set value of the black liquor temperature can be set with higher accuracy. Therefore, the droplet diameter of the sprayed black liquor 11 sprayed into the recovery boiler 10 can be set to a more appropriate value. As a result, the recovery boiler 10 is operated in an optimal combustion state as compared with the first embodiment, and labor saving and stabilization of the pulp production process are improved.

FIG. 4 is a system diagram showing the structure of the main part of the third embodiment of the present invention. The same parts as those in FIGS. 1 and 3 are designated by the same reference numerals, and detailed description thereof will be omitted. In this embodiment, first, when the boiling point calculator 35 estimates and calculates the boiling point from the solid content concentration, the functional relationship between the solid content concentration and the boiling point for the black liquor property obtained based on the type of the chip material 19 is preset. The boiling point is estimated and calculated from the solid content concentration estimated by the solid content concentration estimator 34 based on the black liquor property set by the black liquor property setting device 51. The temperature difference setter 37 sets a predetermined temperature difference based on the black liquor property set by the black liquor property setter 51, and the boiling point calculator 35 in the first adder 36. The black liquor temperature set value is obtained by adding the calculated boiling point and the temperature difference set by the temperature difference setting device 37. By doing so, even if the black liquor property changes depending on the type of the chip material 19 that is put into the chip digesting step, the black liquor temperature set value with which a proper droplet diameter can be obtained can be accurately calculated.

Further, in this embodiment, the combustion air 16a, 16b supplied into the recovery boiler 10 is detected by the air flow rate detectors 52, 53, and the load compensation value calculator is based on the outputs of these air flow rate detectors 52, 53. Calculate the load compensation value at 54,
In the fourth adder 55, the air flow rate (load) is compensated by adding the load compensation value and the black liquor temperature set value. By doing so, an appropriate droplet size can be obtained even if the combustion air flow rate (load) changes.

Further, in the present embodiment, a function for calculating the pressure compensation value according to the type of the injection gun 12 is set in advance in the pressure compensation value calculator 49, and the injection gun type setting unit 56 sets the injection. The pressure compensation value calculator 49 calculates the pressure compensation value from the type of the gun 12 and the injection pressure detected by the pressure detector 48, and the third adder 50 calculates the pressure compensation value as the black liquor temperature set value. To compensate the black liquor temperature set value. By doing so, an appropriate droplet diameter can be obtained even if the injection gun 12 is replaced.

The present invention is not limited to the above-mentioned embodiments. For example, in each of the above embodiments, the solid content concentration estimator 34
Although the above description is provided for the jet black liquor supply line 32, the same effect can be obtained by providing the jet black liquor supply line 32 at the inlet of the mixing tank 27. A gamma ray type densitometer may be used as the densitometer used in the solid content concentration estimator 34.
The solid content concentration detected by the densitometer may be compensated by using a densitometer, a temperature detector, and the like so that the estimation can be accurately performed. Further, in the second embodiment, the case where the scanning pyrometer 43 is provided to detect the temperature in the furnace and the charbed level is shown, but a fixed pyrometer, a thermocouple thermometer, or the like is also possible. Further, the furnace temperature detector and the charbed level detector may be separately provided. Further, in the second embodiment, the case where the black liquor temperature set value is compensated by the char bed level compensating means and the injection pressure compensating means is shown, but only one compensating means may be used. In the second and third embodiments, the case where the charbed level compensation value output from the charbed level adjuster 46 is given to the adder 36 to compensate the black liquor temperature set value is shown. The value may be given to any one of the second to fourth adders 38, 50, 55 to compensate the black liquor temperature set value. Of course, various modifications can be made without departing from the scope of the present invention.

〔The invention's effect〕

As described above in detail, the present invention estimates the boiling point of the black liquor based on the concentration of the black liquor injected into the recovery boiler, and calculates the set temperature of the black liquor based on the estimated boiling point. Along with, the furnace temperature of the recovery boiler is detected, the set temperature of the black liquor is compensated based on the detected furnace temperature, and the temperature of the black liquor is adjusted to the compensated set temperature. It was done.

Therefore, according to the present invention, even if the temperature inside the furnace of the recovery boiler changes, it is possible to compensate for the deviation of the black liquor temperature set value for obtaining the optimum droplet size due to the temperature change inside the furnace. Injecting black liquor in the recovery boiler, which can obtain the proper droplet size of the injected black liquor with respect to changes in the furnace temperature in the furnace, can always maintain the optimum combustion state, and can save labor and stabilize the pulp production process. It is possible to provide a droplet diameter control device of the above.

[Brief description of drawings]

1 and 2 are diagrams showing a first embodiment of the present invention. FIG. 1 is a system diagram showing the configuration, and FIG. 2 is a diagram showing the relationship between the temperature inside the furnace and the compensation value for the temperature inside the furnace. FIG. 3, FIG. 3 and FIG. 4 are system diagrams showing the main parts of the second and third embodiments of the present invention. 10 ... recovery boiler, 11 ... jet black liquor, 12 ... jet gun,
13 ... Char bed, 18 ... Chip digester, 19 ... Chip material, 20 ... Chip cooking chemical, 29 ... Black liquor, 30 ... Heater, 31 ... Steam, 32 ... Spray black liquor supply line, 33 ...
Temperature detector, 34 ... Solid content concentration estimator, 35 ... Boiling point calculator, 36 ... First adder, 37 ... Temperature difference setter, 38 ...
Second adder, 39 ... Reactor temperature detector, 40 ... Reactor temperature compensation value calculator, 41 ... Temperature controller, 42 ... Steam control valve,
43 ... Scanning Pyrometer, 44 ... Furnace temperature calculator, 45 ... Charbed level calculator, 46 ... Charbed level adjuster, 47 ... Charbed level setter,
48 ... Pressure detector, 49 ... Pressure compensation value calculator, 50 ... Third adder.

Front page continuation (72) Yohei Shiogoshi, 1-1, Jojo-cho, Yatsushiro-shi, Kumamoto Inside the Yatsushiro Mill, Tojo Paper Co., Ltd. (72) Takashi Tanihara 4-135, Shimaya, Konohana-ku, Osaka, Osaka Prefecture Kawasaki Heavy Industry Co., Ltd. Osaka Plant (72) Inventor Yasumitsu Kurosaki 1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industry Co., Ltd. Akashi Plant (72) Inventor Toshiyuki Ibed 1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries (72) Inventor Shiro Nakabayashi 1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries Ltd. Akashi Factory (72) Inventor Kazuyuki Iizuka 1-1-1, Shibaura, Minato-ku, Tokyo In the Toshiba headquarters office (72) Inventor Ryuichi Kuwata 1 in Toshiba Fuchu, Tokyo Fuchu-shi, Tokyo (72) Inventor Ao Kumaki 1 in Toshiba Fuchu, Tokyo, Fuchu-shi, Ltd. (72) Inventor Takahisa Chika, 1st Toshiba-cho, Fuchu-shi, Tokyo Toshiba Corporation In the middle Plant (56) Reference Patent Sho 57-210217 (JP, A)

Claims (2)

[Claims] 1. A recovery boiler for injecting a chip material and a chip cooking chemical in a chip cooking step, burning black liquor obtained as a waste liquid to generate steam, and recovering a raw material of the chip cooking chemical, Boiling point estimating means for estimating the boiling point of the black liquor based on the concentration of the black liquor injected into the recovery boiler, and black for calculating the set temperature of the black liquor based on the boiling point estimated by the boiling point estimating means. Liquid temperature setting means, furnace temperature detecting means for detecting the furnace temperature of the recovery boiler, and settings calculated by the black liquor temperature setting means based on the furnace temperature detected by the furnace temperature detecting means A recovery boiler comprising: a set temperature compensating means for compensating the temperature; and a black liquor temperature adjusting means for adjusting the temperature of the black liquor to the set temperature compensated by the set temperature compensating means. Micro liquid droplet size diameter control apparatus. 2. The set temperature compensating means compensates according to the level of the char bed accumulated in the recovery boiler, and the compensating means according to the injection pressure of the black liquor injected into the recovery boiler. The droplet diameter control device for jetted black liquor in a recovery boiler according to claim (1), characterized in that it is provided with either or both of the jetting pressure compensating means.