JPH0663601B2 - 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 an injection gun provided in the black liquor injection mechanism, and this black liquor is suspended and dried to form a char bed at the bottom of the furnace, and this char bed burns. To generate steam,
In addition, the drug raw material is recovered by the reduction reaction at that time. Therefore, this jet black liquor plays an important role for stable operation of the boiler and for 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. I was compensated. Further, if the jetting pressure of the black liquor jetted from the jetting gun is high, the droplet size becomes small, and conversely, if the jetting pressure is low, it becomes large. Therefore, the jetting pressure of this jetting gun is detected to detect the black liquid temperature. The set value was compensated.

[Problems to be solved by the invention]

However, the type of injection gun used in the recovery boiler is fixed, and it may be necessary to replace the injection gun with a desired gun diameter according to the change in load. At present, the amount of steam generated is being changed from the viewpoint of energy saving, and load changes are occurring at any time. For this reason, gun replacement is frequent. In the actual operation, the operator may replace the injection gun depending on the shape of the bed in the furnace, the combustion state, the scattered dust state, the spray state of the injection gun, and the like. In this way, when the spray gun is replaced, the spray pressure changes according to the gun diameter and the like, so the viscous surface tension that determines the droplet size changes, and the floating drying time also changes. Therefore, the conventional injection pressure compensating means cannot perform sufficient compensation, and the optimum droplet diameter cannot be obtained. Further, since the change in the injection pressure is not such a change that the charbed level is remarkably changed, the charbed level compensating means could not sufficiently fulfill its function. As a result, when the injection gun was replaced, the droplet size of the injection black liquor changed, and the optimum combustion state could not be obtained.

Therefore, the present invention can obtain the proper droplet size of the jetted black liquor when the information regarding the black liquor jetting mechanism is changed, for example, when the jet gun is replaced, and can always maintain the optimum combustion state, thus saving labor in the pulp production process. It is an object of the present invention to provide a droplet diameter control device for jet black liquor in a recovery boiler that can be stabilized and stabilized.

[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 concentration 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 black liquor is collected in the recovery boiler. The ejection pressure of the ejected black liquor mechanism is detected, the information regarding the black liquor ejection mechanism is further set, and the setting of the black liquor is performed based on the information regarding the set black liquor ejection mechanism and the detected ejection pressure. The temperature is compensated, and the temperature of the black liquor is adjusted to the compensated set temperature.

[Action]

By taking such a measure, even if the injection gun is replaced, the deviation due to the replacement of the injection gun of the black liquor temperature set value at which the optimum droplet size is obtained can be 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 mainly changes depending on the pressure, temperature, concentration and black liquor properties of the black liquor, and also depends on the black liquor injection mechanism. Generally, it is attempted to obtain an appropriate droplet diameter by adjusting the black liquor temperature or selecting an appropriate injection gun. 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.

When the black liquor flow rate is fixed and the spray gun is replaced with a spray gun with a small diameter, the spray pressure of the black liquor increases,
The droplet size becomes smaller. On the contrary, when the injection gun having a large diameter is replaced, the injection pressure becomes low. In this case, the pressure compensating means compensates for increasing the temperature of the black liquor, but since the gun diameter has changed, an appropriate particle diameter cannot be obtained with the same function for calculating the pressure compensation value. .

Conventionally, a value that is 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,
The constant temperature difference from the boiling point is adjusted empirically by the operator 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 is
Even if the diameter of the injection gun changes, the function for calculating the pressure compensation value is the same. Therefore, even if the caliber of the injection gun becomes small and the injection pressure of the black liquor becomes high and the black liquor temperature is compensated for, the proper particle size cannot be obtained. Therefore, the operator has to empirically adjust the black liquor temperature set value by looking at the combustion state in the furnace, the shape of the char bed, etc., and it has been difficult to obtain an appropriate set value.

In the present invention, a function for calculating a pressure compensation value is set in advance according to information about the black liquor injection mechanism, for example, the diameter and shape of the injection gun, and the black liquor temperature set value is automatically compensated based on this function. The proper black liquor temperature set value is calculated by

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.
A jetting black liquor 11 is made into droplets by a jetting gun 12 and is put into the inside of 10. The jetted black liquor 11 is floating-dried in the recovery boiler 10 and is landed on the bottom of the furnace to form a char bed.
Form 13. Then, the reduction reaction is performed by the high temperature atmosphere on the char bed 13, and the sodium sulfate (Na
₂ SO ₄ ) etc. are reduced by sodium sulfide (Na ₂
S), is recovered from the spoutro 15 as a smelt 14 together with sodium carbonate (Na ₂ CO ₃ ) and the like and is reused as a pulp cooking chemical.

On the other hand, the organic components in the jet black liquor 11 are charbed 13 by the combustion air 16a supplied to the furnace bottom of the recovery boiler 10.
Reductively burns on the surface of. The incompletely combusted portion is completely combusted in the upper portion of the char bed 13 by the combustion air 16b supplied to the central portion of the recovery boiler 10. Then, the combustion gas rises as shown by an arrow A in the figure, exchanges heat with the working fluid in the boiler heat transfer tube 17 to generate steam, and is then discharged as an exhaust gas to the outside of the system as shown by an arrow B in the figure. It has become a thing.

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 cooking chemical 20 and steam 21. Has become. At this time, the waste liquid 23 discharged from the chip digester 18 is contacted with the air 25 in the oxidation tower 24 to be oxidized, concentrated in the concentrator 26, and then mixed with the sodium sulfate 28 in the mixing tank 27 to be black. It becomes liquid 29. Then, the black liquor 29 is heated by the steam 31 in the heater 30, and the jet black liquor supply line 32 serves as the jet black liquor 11.
Is sprayed from the injection gun 12 into the recovery boiler 10 via the.

On the other hand, in the jet black liquor supply line 32, a temperature detector 33 for detecting the temperature of the jet black liquor 11 and a solid content concentration which is a function of the refractive index of the black liquor solution are estimated by a photorefractive densitometer. A solid content concentration estimator 34 and a pressure detector 35 for detecting the injection pressure are provided. The output terminal of the solid content concentration estimator 34 is connected to the boiling point calculator 36. The boiling point calculator 36 estimates and calculates the boiling point of the black liquor 29 from the solid content concentration estimated by the solid content concentration estimator 34. The output end of the boiling point calculator 36 is the first It is connected to the adder 37. The first adder 37 adds the boiling point calculated by the boiling point calculator 36 and the constant temperature difference set by the temperature difference setting unit 38 to calculate the set value of the black liquor temperature. Therefore, the output terminal of the first adder 37 is the second adder 39.
Connected to.

On the other hand, the output end of the pressure detector 35 is connected to one input end of the pressure compensation value calculator 40.
An injection gun type setting device 41 is connected to the other input end of the. The pressure compensation value calculator 40 sets a function for calculating a pressure compensation value in advance according to the type of injection gun, and the function (caliber, shape) of the injection gun set by the injection gun type setting value 41 is set. Etc.) and calculates a pressure compensation value from the injection pressure value detected by the pressure detector 35 based on this selected function, the output end of which is the second addition Connected to the container 38.

In the second adder 38, the black liquor temperature set value given from the first adder 37 and the pressure compensation value calculator 40
The temperature compensation value of the black liquor is compensated by adding the pressure compensation value given from the output of the temperature regulator 42 to the one input terminal of the temperature regulator 42. The temperature detector 33 is connected to the input end of the. The temperature controller 42 is a jet black liquor detected by the temperature detector 33.
The opening of the steam control valve 43 is adjusted so that the temperature of 11 becomes the black liquor temperature set value compensated by the load calculated by the second adder 39. Control valve
The amount of steam 31 supplied to the adder 30 is adjusted according to the opening degree of 43, and the temperature of the jet black liquor 11 heated by the heater 30 is controlled.

In the present embodiment configured as described above, the recovery boiler
The injection gun 12 according to changes in the amount of steam generated by 10
When replacing the
Set 12 types. Then, the pressure compensation value calculator 40
, A function for calculating the pressure compensation value is selected according to the set injection gun, and the pressure compensation value is calculated based on the selected function and the injection pressure value detected by the pressure detector 35. To be done.

FIG. 2 is a diagram showing the functional relationship between the injection pressure and the pressure compensation value according to the type of various injection guns (in this case, three types), and the function f1 is the first adder as the injection pressure rises. This is the case of an injection gun that has a functional relationship that gradually decreases the set temperature calculated in 37, and the function f2 is an injection gun that has a functional relationship that lowers the set temperature to a moderate level as the injection pressure rises. And the function f3 is the case of an injection gun that has a functional relationship such that the set temperature is greatly reduced as the injection pressure rises. These functional relationships are stored in, for example, a table. When the type of the injection gun 12 is set by the injection gun type setting device 41, the functional relationships corresponding to the types of the guns are read out, and the functional relationships are read out. Based on the above, the pressure compensation value is calculated by the injection pressure detected by the pressure detector 35.

Now, the injection gun 12 is changed to f3 from the injection gun having the relationship of the function f2.
It is assumed that the injection gun has a relationship of. Here, when the injection pressure detected by the pressure detector 35 changes from P1 to P2, α is calculated as the pressure compensation value in the conventional pressure compensating means, whereas the pressure compensation value calculator of this embodiment is calculated. At 40, β is calculated.

On the other hand, in the first adder 37, a black liquor temperature set value which is lower than the boiling point of the black liquor 29 estimated by the boiling point calculator 36 by a constant temperature set by the temperature difference setter 38 is calculated, Is given to the adder 39. Then, in the second adder 39, the black liquor temperature set value and the pressure compensation value calculator 40
The pressure compensating value calculated in step 1 is added to calculate the black liquor temperature set value compensated by the injection pressure. Then, this compensated black liquor temperature set value is output to the temperature controller 42, and in this temperature regulator 42, 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 43 based on the deviation. As a result, the amount of steam 31 supplied to the heater 30 is controlled, and the temperature of the jet black liquor 11 becomes equal to the black liquor temperature set value compensated by the jet pressure,
The droplet size of the jetted black liquor becomes an appropriate size.

As described above, according to the present embodiment, the pressure compensation value is calculated based on the relationship between the type of the injection gun 12 and the injection pressure, and the black liquor temperature set value is compensated by this pressure compensation value. Therefore, it is possible to easily compensate for the change in the black liquor temperature set value due to the replacement of the jet gun 12, and it is possible to set the temperature of the jet black liquor 11 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 37 in the first embodiment according to the level of the char bed 13 accumulated in the recovery boiler 10. It is equipped with compensation means.

In FIG. 3, reference numeral 44 is a char bed level detector for detecting the level of the char bed 13,
The detection signal of 44 is output to the char bed level adjuster 45, and in this level adjuster 45, the char bed level is adjusted to the char bed level set by the char bed level setter 46, and as the char bed level compensation value, First
Is output to the adder 37. Then, in the first adder 37, the boiling point temperature estimated by the boiling point computing unit 36 and the temperature difference set by the temperature difference setting unit 38 are added together and compensated according to the charbed level. The black liquor temperature set value is calculated.

In this way, the black liquor temperature set value calculated from the boiling point and the constant temperature difference is compensated by the char bed level compensation value output from the char bed level adjuster 45, so that the black liquor temperature of the black liquor temperature can be more accurately determined. A set value can be set. Therefore, the injection black liquor injected into the recovery boiler 10
The droplet size of 11 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 the present embodiment, first, when calculating the boiling point from the solid content concentration in the boiling point calculator 36, 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. Incidentally, the boiling point is estimated 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 47. In the temperature difference setter 38, a predetermined temperature difference is set based on the black liquor property set by the black liquor property setter 47, and the boiling point calculator 36 is set by the first adder 37. The black liquor temperature set value is obtained by adding the boiling point estimated and calculated and the temperature difference set by the temperature difference setter 38. By doing so, even if the black liquor property changes depending on the type of the chip material 19 to be put into the chip digesting step, the black liquor temperature set value with which an appropriate droplet size can be obtained can be accurately calculated.

Further, in the present embodiment, a scanning pyrometer 48 is provided instead of the char bed level detector 44, and the furnace temperature and char by the furnace temperature calculator 49 and the char bed level calculator 50 are detected from the detection signals of the scanning pyrometer 48. Calculate bed level. Then, the output of the charbed level calculator 50 is given to the charbed level adjuster 45, and the black liquor temperature set value is compensated by the first adder 37 in the same manner as in the second embodiment. On the other hand, the output of the furnace temperature calculator 9 is given to the furnace temperature compensation value calculator 51 to calculate the furnace temperature compensation value based on the furnace temperature, and the third adder 52 calculates the furnace temperature compensation value. And the black liquor temperature set value are added to compensate for the furnace temperature. By doing so, an appropriate droplet size can be obtained even if the temperature in the furnace changes.

Further, in this embodiment, the combustion air 16a, 16b supplied into the recovery boiler 10 is detected by the air flow rate detectors 53, 54,
A load compensation value calculator 55 calculates a load compensation value based on the outputs of the air flow rate detectors 53, 54, and a fourth adder 56 adds the load compensation value and the black liquor temperature set value. To compensate for the air flow rate (load). By doing so, an appropriate droplet size can be obtained even if the combustion air flow rate (load) changes.

The present invention is not limited to the above-mentioned embodiments. For example, although the solid content concentration estimator 34 is provided in the jet black liquor supply line 32 in each of the above-described embodiments, the same effect can be obtained even if the solid content concentration estimator 34 is provided at the inlet of the mixing tank 27.
Further, a gamma ray densitometer may be used as the densitometer used in the solid content concentration estimator 34, or a solid content concentration detected by the densitometer using a density meter and a temperature detector. May be compensated for to make an accurate estimation. In the second and third embodiments, the case where the charbed level compensation value output from the charbed level adjuster 45 is given to the adder 37 to compensate the black liquor temperature set value has been described. The value is added to the second to fourth adders 39, 52,
It may be provided to any one of the adders 56 to compensate the black liquor temperature set value. Of course, various modifications can be made without departing from the scope of the present invention.

[Advantages of the Invention] As described in detail above, 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 based on the estimated boiling point, the black liquor Along with calculating the set temperature, detecting the injection pressure of the black liquor injection mechanism for injecting black liquor into the recovery boiler, and further setting the information regarding the black liquor injection mechanism, the information regarding this set black liquor injection mechanism The set temperature of the black liquor is compensated based on the detected injection pressure, and the temperature of the black liquor is adjusted to the compensated set temperature.

Therefore, according to the present invention, even if the injection gun is replaced, the deviation due to the replacement of the injection gun of the black liquor temperature set value that obtains the optimum droplet size can be compensated, so that the injection gun can be replaced. On the other hand, it is possible to obtain a proper droplet size of jetted black liquor, maintain an optimum combustion state at all times, and save labor and stabilize the pulp production process. Can be provided.

[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 relation between injection pressure and load compensation value for various injection guns. Showing the figure,
FIG. 3 and FIG. 4 are system diagrams showing the configuration of the main parts in the second and third embodiments of the present invention. 10 …… Recovery boiler, 11 …… Injection black liquor, 12 …… Injection 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 ... Pressure detector, 36 ... Boiling point calculator, 37 ... First adder, 38 ... Temperature difference setter, 39 ... Second Adder, 40 ... Pressure compensation value calculator, 41 ... Injection gun type setting device, 42 ... Temperature controller,
43 …… Steam control valve, 44 …… Char bed level detector,
45 …… Char bed level adjuster, 46 …… Char bed level adjuster.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yohei Shioshikoshi, 1-1, Jujo-cho, Yatsushiro-shi, Kumamoto Prefecture, Joujo Paper Co., Ltd. Yatsushiro Mill (72) Inventor, Takashi Tanihara 4-chome, Shimaya, Osaka, Osaka No. 35 Kawasaki Heavy Industries, Ltd. Osaka Plant (72) Inventor Yasumitsu Kurosaki 1-1, Kawasaki-cho, Akashi City, Hyogo Prefecture Kawasaki Heavy Industries Ltd., Akashi Plant (72) Inventor Toshiyuki Ibed 1-1 Kawasaki-cho, Akashi-shi, Hyogo Prefecture Issue Kawasaki Heavy Industries, Ltd. Akashi Plant (72) Inventor Shiro Nakabayashi 1-1 Kawasaki-cho, Akashi-shi, Hyogo Prefecture Kawasaki Heavy Industries Ltd. Akashi Plant (72) Inventor Kazuyuki Iizuka 1-1-1, Shibaura, Minato-ku, Tokyo No. TOSHIBA Head Office Office (72) Inventor Ryuichi Kuwata No. 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Factory (72) Inventor A. Kumaki Fuchu, Tokyo Toshiba-cho, address 1 Toshiba Fuchu in the factory (72) inventor Kinhisa 嚴雄 Fuchu, Tokyo Toshiba-cho, address 1 Toshiba Fuchu in the factory

Claims (3)

[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, injection pressure detection means for detecting the injection pressure of a black liquor injection mechanism for injecting black liquor into the recovery boiler, and black liquor injection mechanism setting means for setting information regarding the black liquor injection mechanism. , The set temperature calculated by the black liquor temperature setting means on the basis of the information about the black liquor injector set by the black liquor injection mechanism setting means and the injection pressure detected by the injection pressure detecting means. Compensated set temperature compensating means, and black liquor temperature adjusting means for adjusting the temperature of the black liquor to the set temperature compensated by the set temperature compensating means. Drop size control device. 2. The set temperature compensating means is provided with a char bed level compensating means for compensating according to the level of the char bed accumulated in the recovery boiler. A droplet size control device for jet black liquor in the recovery boiler according to the item 1). 3. The information relating to the black liquor injection mechanism set by the black liquor injection mechanism setting means is the caliber or shape of the injection gun and the like.
Item 6. A droplet diameter control device for jetted black liquor in the recovery boiler according to the item.