JPH0735892B2 - Recovery boiler soot blow controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial field of application) The present invention is a recovery boiler that burns black liquor generated in a pulp manufacturing process to generate steam and recovers a raw material for chemicals for chip digestion. The present invention relates to a soot blow control device, and more particularly to a soot blow control device in which the operation control means of the soot blow lance when the combustion state of the recovery boiler is lowered is improved.

(Prior Art) In a pulp manufacturing plant, black liquor discharged as a waste liquid from a chip cooking process is introduced into a heating section, where it is heated by steam and then injected into a furnace of a recovery boiler by an injection gun. Then, the jetted black liquor floats and dries to land on the bottom of the furnace to form a char bed, so that combustion air is sent into the furnace to burn the char bed. The combustion exhaust gas generated at this time is finally discharged from the chimney through the water cooling wall of the combustion chamber, the super heater (superheater) in the upper part of the furnace, the main body bank in the exhaust gas passage line, the heat transfer part such as the economizer. Then, water is sent from the water supply line so as to pass through the economizer, the main body bank, the super heater, and the combustion chamber water cooling wall. Then, heat is exchanged in these heat transfer parts and is taken out as main steam.
Further, the reduction reaction is performed in the high temperature atmosphere on the char bed, and sodium sulfate (Na ₂ SO ₄ ) and the like in the black liquor becomes sodium sulfate (Na ₂ S), and sodium carbonate (Na ₂ CO ₃ ) and the like are added to the boiler. It is configured to be recovered from the spoutro at the bottom of the furnace as smelt which is a raw material of the chemical used in the chip cooking step.

By the way, in the recovery boiler as described above, the dust generated by the combustion sum of the char bed adheres to the heat transfer portion, which causes the heat exchange efficiency to decrease with time. Therefore, in order to remove dust adhering to the surface of the heat transfer part, usually, a plurality of soot blow lances are installed toward each heat transfer part on the boiler wall surface, etc., and these soot blow lances are controlled by an operation control signal from the controller. Dust is removed by sequentially operating each heat transfer unit in a fixed order.

However, the conventional recovery boiler of this type has the following problems. That is, since the recovery boiler has a structure for burning the entire fuel deposit called a char bed in the furnace, it is difficult to maintain a uniform combustion state, resulting in local combustion failure. However, the deterioration of the combustion state was unavoidable. Especially, when the low excess air combustion in which the combustion air is throttled is performed aiming at the high efficiency operation, such a problem becomes remarkable. On the other hand, soot blow by the soot blow lance is performed according to the set order regardless of whether the combustion state in the furnace is good or bad. Therefore, if soot-blowing is performed on the heat transfer part such as the super heater while the combustion state is decreasing, dust may drop on the char bed or low temperature steam may be blown into the furnace to improve the combustion state. There is a risk that the deterioration may worsen and the poor combustion may spread, eventually leading to a complete misfire.

(Problems to be Solved by the Invention) As described above, in the conventional soot blow control device, the soot blow operation is controlled regardless of the combustion state in the furnace of the boiler. By doing so, the combustion state may be further reduced. However, if all sootblowing operations are prohibited when the combustion state is lowered, the heat exchange efficiency will be significantly reduced due to the adhesion of dust to the heat transfer section, leading to a decrease in the main steam temperature and a decrease in the main steam flow rate, and the recovery boiler. This will have an adverse effect on the connected turbine and each process.

Therefore, the present invention, for the soot blow lance that may reduce the combustion state by soot blow, it may be possible not to perform the soot blow operation when the combustion state is lowered, there is no risk of progressing the deterioration of the combustion state,
An object of the present invention is to provide a soot blow control device for a recovery boiler that does not adversely affect the turbine connected to the recovery boiler and each process.

[Structure of the Invention] (Means for Solving Problems) The present invention sets a soot blow operation sequence of a plurality of soot blow lances by an order setting means, and performs a soot blow among the plurality of soot blow lances to recover a recovery boiler. If the soot blow lance that may lower the combustion state inside is registered by the registration means and the deterioration of the combustion state in the recovery boiler is detected by the combustion state decrease detection means, this time based on the setting order of the order setting means The determining means determines whether or not the soot blow lance performing the soot blow is the soot blow lance registered by the registration means, and as a result, when the soot blow lance performing the soot blow is registered by the recording means this time Soot blow operation It is obtained so as to stop.

(Operation) With the soot-blowing control device for the recovery boiler that takes such means, when the soot-blowing start command is given to the soot-blowing lance that may lower the combustion state when the combustion state of the recovery boiler is lowered, This start command output is prohibited to prevent the progress of combustion state deterioration due to soot blow.

(Example) An example in which the device of the present invention is incorporated in a pulp manufacturing plant will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a recovery boiler in a pulp manufacturing plant including a soot blow control device of the present invention. In the figure, reference numeral 1 denotes a combustion chamber of a recovery boiler, in which the black liquor A discharged as waste liquid from the chip cooking process
Is sprayed and introduced by a spray gun 3 through a black liquor tank 2 and a heating section (not shown).
To form. The combustion of the char bed 4 is promoted by the combustion air B supplied from the upper and lower air supply ports 5a and 5b, and at this time, the reduction reaction is performed in the high temperature atmosphere on the char bed 4, and the sodium sulfate in the black liquor (Na ₂ SOO ₄ ) becomes sodium sulfide (Na ₂ S),
₂ CO ₃ ), etc., and from the spoutro 6 at the bottom of the combustion chamber, smelt C, which is the raw material of the chemical used in the chip cooking process.
Will be collected as. Further, the combustion exhaust gas D generated by the combustion of the char bed 4 is discharged from the chimney 8 through the exhaust gas passage line 7.

On the other hand, in order to effectively use the heat quantity of the exhaust gas D, a water cooling wall is provided around the combustion chamber 1, a super heater 9 is provided on the upper part, and a main body bank 10 and an economizer 11 are provided in the middle of the exhaust gas passage line 7. , Water supply line 12
Water E supplied from the economizer 11 and body bang 1
0, heat is exchanged by passing through heat transfer parts such as the super heater 9 and the water cooling wall of the combustion chamber, and is taken out as F from the main steam line 13. Further, in order to remove adhered dust that prevents heat exchange in the superheater 9, the main bank 10 and the economizer 11, etc., these superheater 9, main body bank 10 and economizer 11 are not shown.
A plurality of steam blow soot blow lances are provided on the wall surface of the boiler. The soot blow lance is controlled by a soot blow control device 15 that performs a control operation based on the output detected by a furnace temperature detector 14 provided in the combustion chamber 1.

The soot blow control device 15 specifically has the configuration shown in FIG. That is, reference numeral 20 in FIG. 2 denotes a combustion state determination unit which determines the combustion state in the combustion chamber 1 based on the temperature detection signal M from the in-furnace temperature detector 14. The determination unit 20 has a low level when it determines that the combustion state is normal, and a high level when it determines that the combustion state has deteriorated due to blackout (misfire), black port (combustion deterioration), or the like. The combustion state signal S1 is output to the skip signal generator 21. Reference numeral 22 denotes a soot blow request command unit, which is a soot blow request unit at a time interval preset by a tie, or in accordance with heat conversion efficiency decrease information or ventilation resistance increase information by a measurement sensor provided at or near each heat transfer unit. Start request signal
S2 is output, and the request signal S2 is output by the lance determination unit 23.
Given to. Examples of the measurement sensor include a temperature sensor that measures the temperature of the input / output section of each heat transfer section, or a pressure sensor that measures the pressure difference of the combustion exhaust gas between the inlet and the outlet of each heat transfer section. In response to the input of the soot blow activation request signal S2, the lance determining unit 23 determines the soot blow lance so as to perform the soot blow according to the activation order of the soot blow lance preset by the setting means (not shown), and the lance determination signal
S3 is sent to the soot blow start command unit 24 and the lance comparison unit 26.

On the other hand, reference numeral 25 is a lance registration unit for registering a soot blow lance that may adversely affect the combustion state in the boiler by soot blow, for example, a soot blow lance for the super heater 9, and a lance comparison unit 26 from the lance determination unit 23. Each time the lance determination signal S3 is given, the lance registration unit 25 is searched, and it is determined whether or not the soot brolan determined by the lance deciding unit 23 is the soot brolan registered in the lance registering unit 25. LOW level if not registered, HIG if registered
The lance registration signal S4 having the H level is output to the skip signal generator 21. As means for registering the soot blolance, means for the operator to input in advance by using an input device such as a keyboard, and how in the past the heat exchange efficiency or the ventilation resistance changed by performing soot blow by each soot lance There is a means for mechanically registering by monitoring.

The skip signal generation unit 21 is a combustion state signal S1 from the combustion state determination unit 20 and a lance registration signal from the lance comparison unit 26.
The logical product with S4 is taken, and when the logical product is established
When both 4 are at the high level, the skip signal S5 is output to the soot blow start command section 24 and the skip lance control section 27. The soot blow start command section 24 normally outputs a soot blow start signal S6 to the corresponding soot blow lance in response to the lance decision signal S3 from the lance decision section 23 to start the soot blow operation. When S5 is given, the output of the soot blow activation signal S6 at that time is stopped and the corresponding soot blow lance information is stored in the skip lance storage section 28. On the other hand, the skip lance control unit 27 sequentially reads the soot blow lance information stored in the skip lance storage unit 28 in response to the fall of the skip signal S5, and the soot blow start request signal S2 is sent from the soot blow request command unit 22. The soot blow start command unit 24 is given a command to output the soot blow start signal S6 to the corresponding soot blow lance by determining the time when the soot blow is not output.

Thus, the soot blow control device 15 is configured to operate according to the procedure shown in FIG. That is, first, as a step (hereinafter abbreviated as ST) 1, the soot blow request command section 22 sends a soot blow start request signal S2.
Is output, the lance determining unit 23 determines the soot brolans that can be operated this time according to a preset operation sequence of the soot brolans. Then ST
The lance comparison unit 26 determines whether or not the soot blow lance determined by the lance determination unit 23 is registered in the lance registration unit 25, and if not registered, the soot blow start command unit 24 determines the corresponding soot blow lance. The soot blow start signal S6 is sent to the lance. On the other hand, if the soot blow lance started this time is registered in ST2, the combustion state signal S1 from the combustion state determination unit 20 is set in ST3.
Determines whether the combustion state in the combustion chamber 1 has deteriorated. If not, the soot blow start command unit
The soot blow start signal S6 is sent to the corresponding soot blow lance by 24. On the other hand, when the combustion state is low, the skip signal generator 21 sends the skip signal S5 to prohibit the output of the soot blow start signal S6 to the corresponding soot blow lance, and at the same time, the soot blow lance information is skipped. It is stored in the storage unit 28.

After that, in ST4, it is determined whether or not the combustion state in the combustion chamber 1 is recovered, and if recovered, it is determined in ST5 whether the soot blow activation request signal S2 is output by the skip lance control unit 27. If it is not output, control is performed so that the soot blow start signal S6 is sent to the soot blow lance stored in the skip lance storage section 28. On the other hand, when the soot blow start request signal S2 is output, after the soot blow operation for the soot blow lance determined according to the request signal S2, the soot blow start signal S6 for the soot blow lance stored in the skip lance storage unit 28 is output. Control to send.

In the present embodiment configured as described above, the char bed 4 formed in the combustion chamber 1 burns to generate the combustion exhaust gas D, and the water E flowing through the water supply line 12 becomes the economizer 11.
Heat is exchanged with the combustion exhaust gas D at each heat transfer portion of the main body bank 10, the super heater 9, and the water cooling wall of the combustion chamber to become main steam F, which is supplied from the main steam line 13 to a turbine or the like. Further, the temperature in the combustion chamber 1 is constantly detected by the furnace temperature detector 14, and the detection signal M is given to the combustion state determination unit 20 of the soot blow control device 15. Then, the combustion state determination unit 20 determines whether or not the combustion state in the combustion chamber 1 is reduced due to a blackout or a black port. If the combustion state is not reduced, a soot blow start request is made every time. Soot blow is performed by a predetermined soot blow lance in accordance with the start-up order determined by the lance determining unit 23, and the dust attached to the corresponding heat transfer unit is removed.

On the other hand, if it is determined that the combustion state has deteriorated,
A lance that is registered in advance in the lance registration unit 25, that is, a soot blow operation that may lower the combustion state by the soot blow operation is prohibited to prevent the soot blow operation from progressing, and the progress of the combustion state decrease is prevented. The heat exchange efficiency is secured by operating only the soot blow lance that does not affect the combustion state even by the soot blow operation. Then, if the combustion state in the combustion chamber 1 is restored, soot blow is performed by the soot blow lance that is prohibited, and the dust adhering to the heat transfer portion is removed.

Therefore, according to the present embodiment, when the combustion state in the combustion chamber 1 is lowered, soot blow by the soot blow lance that adversely affects the combustion state is prohibited, that is, when combustion at the bottom of the recovery boiler is unstable. Since the operation of soot blow, which may disturb combustion, is restricted, it is possible to prevent the progress of deterioration of the combustion state due to dust drop due to soot blow, low temperature steam injection, etc., and shorten the recovery time. Things will come. Therefore, the occurrence of blackout, black port, etc. can be suppressed to a minimum, which is suitable for performing low excess air combustion in which the combustion air B is throttled particularly for high efficiency operation. Further, since the soot blow lance that does not affect the combustion state is soot blown as usual, the dust in the corresponding heat transfer portion is removed and a predetermined heat exchange efficiency can be secured. Therefore, the desired main steam F
Therefore, there is no risk of adversely affecting the turbine or each process connected to the recovery boiler.

The present invention is not limited to the above embodiment.
For example, in the above embodiment, the furnace temperature detector 14 is provided in the combustion chamber 1 as a means for determining the combustion state in the combustion chamber 1, and the combustion state is determined based on the temperature in the combustion chamber 1. However, the main steam flow rate detector may be installed in the main steam line 13, and the determination may be made based on the flow rate of the main steam F. Also, the SO ₂ concentration and NOx contained in the combustion exhaust gas D
The determination may be made based on the detected values of the concentration, CO ₂ concentration, CO concentration, etc., or these may be combined in a timely manner to make an integrated determination. Further, in the above-described embodiment, the case is shown in which the soot blow operation is interrupted at the time of combustion recovery for the soot blow lance in which the soot blow operation is prohibited due to the deterioration of the combustion state, but after the combustion recovery, according to the preset soot blow order. You may make it operate. Furthermore, in the above-mentioned embodiment, the soot blow lance has been described as a single body, but it goes without saying that it can be applied even if it forms a group structure. In addition, it goes without saying that various modifications can be made without departing from the scope of the present invention.

[Effects of the Invention] As described in detail above, according to the present invention, the soot-blowing operation sequence of a plurality of soot-blowing lances is set by the order setting means, and soot-blowing is performed among the plurality of soot-blowing lances in the recovery boiler. If the soot blow lance that may reduce the combustion state of the soot blower is registered by the registration means, and the decrease in the combustion state in the recovery boiler is detected by the combustion state decrease detection means, the soot blow lance is set based on the setting order of the order setting means. The determination means determines whether or not the soot brow lance that performs the soot blow lance is registered by the registration means, and as a result, when the soot brow lance that performs the soot blow this time is registered by the registration means, Prohibit soot blow operation Therefore, for soot blow lances that may lower the combustion state due to soot blow, the soot blow operation may not be performed when the combustion state decreases, that is, when the combustion at the bottom of the recovery boiler is unstable. Can limit the operation of soot blow, which may disturb the combustion of the fuel, and does not cause the deterioration of the combustion state to progress, and it does not adversely affect the turbine or each process connected to the recovery boiler. A soot blow control device for a boiler can be provided.

[Brief description of drawings]

1 to 3 are views showing an embodiment of the present invention, wherein FIG. 1 is a schematic configuration diagram of a recovery boiler in a pulse manufacturing plant including the device of the present invention, and FIG. 2 is a soot blow control device. FIG. 3 is a block diagram showing the specific configuration of FIG. 3, and FIG. 3 is a flowchart for explaining the operation of the soot blow control device. 1 ... Combustion chamber, 4 ... Char bed, 9 ... Super heater, 10 ... Main bank, 11 ... Economizer, 12 ... Water supply line, 13 ... Main steam line, 14 ... Reactor temperature detector, 15 ... Soot blow control device, 20 ... Combustion state determination unit, 21 ... Skip signal generation unit, 22 ... Soot blow request command unit, 23 ... Lance determination unit, 24 ... Soot blow start command unit, 25 ... Lance Registration department, 26 …… Lance comparison department,
27 …… Skip lance control section, 28 …… Skip lance storage section.

Front page continuation (72) Yohei Shioshikoshi, 1-chome, 1-chome, Jujo-cho, Yatsushiro-shi, Kumamoto Inside the Yatsushiro Mill, Tojo Paper Co., Ltd. (72) Masaru Nishimura 4-135, Shimaya, Konohana-ku, Osaka City, Osaka Prefecture Kawasaki Heavy Industry Co., Ltd. Osaka Plant (72) Inventor Toshiyuki Ibed 1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries Ltd. Akashi Plant (72) Inventor Shiro Nakabayashi 1-1, Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industry Co., Ltd. Akashi Plant (72) Inventor Kazuyuki Iizuka 1-1-1, Shibaura, Minato-ku, Tokyo Inside Toshiba Headquarters Co., Ltd. (72) Inventor Ryuichi Kuwata 1 Toshiba Town Fuchu City, Tokyo Toshiba Fuchu Plant Co., Ltd. (72) Inventor Akio Kumaki No. 1 in Toshiba Fuchu factory, Fuchu-shi, Tokyo (72) Inventor Atsushi Muramatsu No. 1 in Toshiba Fuchu, Tokyo, Fuchu factory (56) References Sho 60-149816 (JP, A) JP-A-57-87528 (JP, A)

Claims (2)

[Claims] 1. A soot blow control device for a recovery boiler, wherein a plurality of soot blow lances are installed toward a heat transfer section provided in a recovery boiler, and these soot blow lances are sequentially operated to remove dust adhering to the heat transfer section. An order setting means for setting a soot blow operation order of the plurality of soot blow lances, and a registration means for registering a soot blow lance that may lower a combustion state in the recovery boiler by performing soot blow among the plurality of soot blow lances. And a combustion state decrease detecting means for detecting a decrease in the combustion state in the recovery boiler, and when the combustion state decrease detecting means detects the combustion state decrease, soot blow is performed this time based on the setting order of the order setting means. Soot brow lance is registered by the registration means And a soot-blowing prohibition means for prohibiting the current soot-blowing operation by the soot-blowing when the so-to-blowing for performing the soot-blowing this time is registered by the registration means. A soot-blowing control device for a recovery boiler, comprising: 2. The soot blow prohibiting means comprises means for interrupting soot blow by a soot blow lance that prohibits soot blow operation when a combustion state recovery is detected by the combustion state decrease detecting means. A soot blow control device for a recovery boiler according to item (1).