JPH02254214A - Controller for soot blower - Google Patents

Abstract

PURPOSE:To minimize the increase of unburnt portion in combustion gas, the lowering of a denitration rate, the generation of corrosion at the rear flow part of a boiler and the occurrence of variations in draft by controlling the operation of a soot blower when a boiler load is lowered. CONSTITUTION:The title controller is provided with a synthesized condition priority operating device 107 that performs minimum multivalent logical operation on the basis of the input of both signals produced from a foul condition priority operating device 104 and a boiler condition priority operating device 106; a candidate starting place selector 108 that selects higher priority from among signals produced from the synthesized condition priority operating device 107; and a candidate boiler load operating device 109 that allows a soot blower 27 to be actuated on the basis of both a boiler load signal outputted from a boiler load operating device 110 which produces a signal corresponding to a boiler load, and a signal outputted from the candidate starting place selector 108. An actuation signal produced from the main body of a soot blower control section 100 (soot blower starting place decision operating device 108) is inputted into a soot blower actuating device 29, so that the selected soot blower 27 starts its actuation. According to this method, the lowering of a denitration rate, corrosion at the rear flow part of a boiler and the occurrence of variations in draft can be minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for a soot blower disposed, for example, on a heat transfer surface of a boiler device, and the present invention relates to a control device for a soot blower disposed on a heat transfer surface of a boiler device. The present invention relates to a soot blower control device suitable for determining a starting point.

[Conventional technology]

In a typical boiler system, heat exchangers such as a superheater, reheater, and economizer are arranged in the furnace, ice wall, and gas passage connected to it. A fluid to be heated, such as steam, is heated by high-temperature combustion gas generated in the furnace.

When this boiler device is operated, ash, soot, etc. adhere to and accumulate on the heat transfer surface of the heat exchanger, reducing the heat exchange performance on the heat transfer surface. Furthermore, the combustion gas temperature at the furnace outlet increases, the steam temperature and pressure rise at the superheater outlet decreases, and the spray injection flow rate decreases, and the amount of heat absorbed by the reheater is insufficient. This causes various problems such as an excessive amount of recirculating gas having to be input or an excessive rise in the boiler outlet gas temperature resulting in an unhealthy boiler condition.

Therefore, it is necessary to start a soot blower using steam as an injection medium at an appropriate time to remove ash, soot, etc. adhering to the heat transfer surface of the heat exchanger.

Conventionally, the location and timing of starting the soot blower was determined by estimating the contamination state on the heat transfer surface of each heat exchanger.
The size of the dirt was displayed on a CRT screen, and the operator issued a command to start the soot blower for areas with a large degree of dirt.

[Problems to be Solved by the Invention] However, such a soot blower control device has the following problems.

Since the operator must constantly monitor the CRT screen, the operator's work efficiency is poor.

Originally, the soot blower is activated when the boiler condition becomes unhealthy and the degree of contamination is large, but it should not be activated unnecessarily when the boiler load is reduced. In other words, it is necessary to cooperate with the boiler load and suppress the activation of the soot blower compared to when the rated boiler load is applied. Conventional soot blower control devices do not have a function in this regard, and determine whether to start the soot blower regardless of the boiler load.

-S, when the boiler load decreases, the gas flow rate decreases and the gas temperature decreases. However, in the prior art, the nude blower is activated when the degree of contamination is large and the boiler condition deteriorates, so heat is absorbed by the steam side, further lowering the gas temperature. When the gas temperature decreases, the combustibility of the fuel decreases, so the amount of unburned fuel increases, and soot and dust are discharged from the boiler when the soot blower is activated. Furthermore, the flue gas flue at the boiler outlet is usually equipped with a denitrification device and an air preheater. The denitrification rate of this denitrification device depends on the exhaust gas temperature, and as the gas temperature decreases, the denitrification rate also decreases. Furthermore, the air preheater warms the combustion air used in the boiler, but if the temperature of the exhaust gas becomes too low, it will be cooled by the outside air and the NOx in the exhaust gas will change to nitric acid, corroding the air preheater. There is also.

Furthermore, as the boiler load decreases, the gas flow steepness decreases, so when the soot blower is started, pressure fluctuations within the boiler furnace also increase. Normally, the inside of the boiler is set to have a negative pressure by making the forced draft fan stronger than the forced draft fan, but when the gas flow rate decreases, the pressure will fluctuate due to the activation of the soot blower. ．． This causes the damper opening degree within the boiler to vary. L
7. Therefore, in order to suppress this draft fluctuation, it is necessary to suppress the activation of the soot blower as much as possible.

If the soot blower is started indiscriminately when the boiler load is reduced in this way, there are problems such as an increase in unburned matter, a decrease in the denitrification rate, corrosion, and draft fluctuations.

The purpose of the present invention is to solve the problems of the above-mentioned prior art,
To provide a stable and efficient soot blower control device even when the load of a boiler to which the soot blower device is attached decreases.

[Means to solve the problem]

The present invention provides a soot blower control device that includes a device that detects the dirt status of heat transfer surfaces of a plurality of heat exchangers provided in a boiler, and operates a soot blower that cleans these heat transfer surfaces based on a detection signal from the device. , a dirt status calculator that calculates the dirt status of the heat transfer surface of each heat exchanger and a dirt status priority setting device that outputs a value according to the dirt status to calculate the starting priority of the soot blower. 94
．． The start priority of the soot blower is determined by signals from the f-priority calculator, the boiler status calculator that calculates the operating status of each heat exchanger, and the boiler status priority setter that outputs a value according to the operating status of the boiler. Priority is given to the smaller value of the fouling state priority and boiler condition B priority for each heat transfer surface obtained from the boiler state priority computing unit to be calculated, the fouling state priority computing unit, and the boiler state priority computing unit. A composite state priority calculator that selects the heat transfer surface based on the priority of the heat transfer surface, and a activation candidate point that selects the soot blower that cleans the heat transfer surface with a higher priority based on the output from the composite state priority calculator. Based on the signals from the selector, the boiler load calculator which generates a signal suitable for the boiler load, and the boiler load calculator and the start candidate point selector, the start candidate point selector selects a starting point when the boiler load is above a predetermined value. A boiler load compensation calculator 714 is provided to start the soot blower.

(Function) The present invention does not start the soot blower to clean the heat exchanger heat transfer surface only when the boiler condition worsens or dirt increases, but because the soot blower drive is controlled according to the boiler load. In particular, by suppressing the soot blower drive when the boiler load decreases, the unburned content in the boiler combustion gas increases.
It becomes possible to reduce the reduction in the denitrification rate of the denitrification equipment, the occurrence of corrosion in the downstream part of the boiler, and the occurrence of draft fluctuations.

[Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 8 is a schematic configuration diagram of a boiler apparatus equipped with a blower control circuit according to an embodiment.

In FIG. 8, 1 is a boiler device, and the high temperature combustion gas generated in the furnace 2 is transferred to the heat transfer surface of the heat exchanger by the pressure difference generated by the induced draft fan II, that is, the furnace water wall 12, the superheater 3, It sequentially passes through the reheater 4 and the economizer 5, imparts heat to the water and steam in the heat exchanger, damper 511, denitrification device 52,
It communicates with the air preheater 7 and is discharged to the outside of the system.

Coal, which is fuel, is supplied to the pulverizer 9 from the coal feeder R21, and then passes through the pulverized coal pipe 13 and the burner wind box 8 to the burner 1.
It is burned in 5. On the other hand, the combustion air is supplied by the forced draft fan 10.
The coal passes through the main air passage 17 and is supplied to the burner 15 along with pulverized coal via the pulverizer 9.

The recirculated gas passes through the recirculated gas flue 26 by the ventilator 14 and enters the furnace 2 from the hopper 25 .

The amount of recirculated gas is controlled by a recirculated gas flow control valve 24.

Water, which is the fluid to be heated, is sent to the carbon-saving layer 5 by the water supply pump 6, and then passes through the furnace ice wall 12 and the superheater 3, where it absorbs heat and rises in temperature, becoming high-temperature, high-pressure steam and flowing through the main steam pipe 18. and is sent to a high-pressure turbine (not shown) outside the system.

The steam that has been used in the high-pressure turbine and has become low temperature and low pressure passes through the low-temperature reheat steam pipe 19 and enters the reheater 4, where it absorbs heat.
It becomes high temperature and high pressure again, and is sent to a low pressure turbine (not shown) outside the system through a high temperature reheat steam pipe 20. In addition, if it is necessary to reduce the steam temperature in superheater 3, spray 2
3 supplies low temperature water to the superheater 3.

When the temperature and pressure of the steam sent to the high-temperature reheat steam pipe 20 are below the specified values, the amount of recirculated gas is adjusted by the recirculated gas flow rate control valve 24 in order to improve the heat transfer efficiency in the reheater 4. increase.

Additionally, if the gas temperature at the furnace outlet 22 is too high,
This will adversely affect the material and life of the superheater 3.

Furthermore, if the gas temperature at the boiler outlet 16 is higher than the specified value, the boiler efficiency may be low.

The amount of spray supplied to the superheater 3 by the above-mentioned spray 23 (for generalization, take the ratio of the amount of spray to the amount of main steam, that is, the spray ratio), the amount of recirculated gas (for generalization, the amount of recirculated gas) In this embodiment, the boiler operating state is defined as the ratio of the gas amount due to combustion and the recirculated gas amount ratio), the gas temperature at the furnace outlet 22, and the gas temperature at the boiler outlet 16.

In the boiler device having such a configuration, by burning the supplied pulverized coal in the burner 15, the heat transfer surface of the furnace ice wall portion 12, the superheater 3, the reheater 4, and the coal saver 5 is heated as described above. Ash, soot, etc. adhere to and accumulate on the boiler, reducing heat transfer efficiency and causing unhealthy boiler operating conditions. A soot blower 27 is arranged corresponding to each heat exchanger in order to blow away the ash, soot, etc. that has adhered to the heat transfer surface described above, but in order to avoid complicating the drawing, in FIG. Only the soot blower 27 compatible with the above is shown.

Next, the soot blower control device will be explained.

A gas thermometer 30 and an oxygen concentration meter 31 are provided at the boiler outlet 16 to check the properties of the combustion gas.

Built-in air flow meter 33 for measuring the amount of combustion air supplied to the burner 15, gas flow meter 34 for measuring the amount of combustion gas supplied to the hopper 25, a dry bulb thermometer 44, and a wet bulb thermometer 45. The air condition measuring boxes 28 are arranged respectively.

A feed water flow meter 35 is installed on the outlet side of the feed water pump 6, a spray feed water flow meter 40 and a spray feed water thermometer 41 are installed on the inlet side of the spray 23, and a feed water flow meter 41 for spraying is installed in the low temperature reheat steam pipe 19 for estimating the flow rate. Low-temperature reheat steam pressure gauges 43 are respectively arranged.

In addition, a thermometer and a pressure gauge are installed on the inlet and outlet sides of each heat exchanger to ascertain the properties of water and steam. Only those related to 5 are shown. That is, a thermometer 36 and a pressure gauge 37 are disposed on the inlet side of the economizer 5, and a thermometer 38 and a pressure gauge 39 are disposed on the outlet side, respectively.

A coal feeding needle 42 is provided on the exit side of the coal feeding machine 21, and a coal property setting device 3 is further provided for grasping the combustion properties of pulverized coal.
2 is placed on the coal supply route.

As shown in FIG. 2, the soot blower control unit main body 100 includes a recirculation gas flow rate adjustment valve 24, a gas thermometer 30, an oxygen concentration meter 31, an air flow meter 33, a gas flow meter 34, a water supply flow meter 35, and a thermometer. 36, pressure gauge 37, thermometer 38, pressure gauge 39, feed water flow meter for spray 40, feed water thermometer for spray 41, coal feed needle 42, low temperature reheat steam pressure gauge 43, dry bulb thermometer 44, wet bulb temperature Detection signals from a total of 45 and setting signals from a coal property setting device 32, a boiler load 46, etc. are respectively input.

Next, a schematic configuration of the soot blower control section main body 100 will be explained with reference to FIG. 1. As shown in the figure, a heat transfer surface contamination state calculator 101 and a contamination state priority setting device 103
are paired, and both signals are input to the dirt status priority calculator 104. Further, the boiler status calculator 102 and the boiler status priority setting unit 105 form a pair, and both signals are input to the boiler status priority calculator 106. The dirt status B priority calculator 1
04 has a function of calculating the activation priority of the soot blower based on the dirt status of the heat transfer surface. On the other hand, the boiler condition priority calculator 106 has a function of calculating the activation priority of the soot blower based on the boiler condition. A composite state priority calculator 107 that performs a minimum type multi-valued logical operation upon input of both signals 106 and 106; and an activation candidate location selector that selects a higher priority from the signals from the composite state B priority calculator 107. 108, a boiler load compensation calculator 109 that drives the soot blower 27 from both signals from the boiler load signal outputted from the boiler load calculator 110 that generates a signal commensurate with the boiler load, and the start candidate point selector 108. We are prepared.

A drive signal from the soot blower control unit main body 100 (the soot blower activation point determining calculator 108) is input to the soot blower driving device 29, and the selected soot blower 27 is thereby activated.

The contamination condition calculator 101 in FIG. Calculate the contamination state of the heat transfer surface.

The calculation formula for calculating the contamination state of the heat transfer surface is as follows: Kf, dirt condition index Uc: Current heat transfer coefficient Us: Standard state heat transfer coefficient Furthermore, Uc is determined by the following formula.

here, A; Heat transfer area of heat exchanger Q; Endothermic amount △t; Logarithmic average temperature difference The heat transfer area A is determined from design data.

The amount of heat absorbed Q is It is determined by

Here, F: Water, steam flow rate H: Enthalpy calculation formula Ts, Ps: Temperature and pressure of water and steam, suffixes i and o indicate the inlet side and outlet side, and the logarithmic average temperature difference Δt is, In the case of countercurrent flow, Tg is the gas temperature, and 11 o indicates the inlet side and the outlet side.

The water and steam temperatures Tsi and Tso are detected by thermometers placed at the entrance and exit of each heat exchanger.
Measure with thermometer 36.38.

The gas temperatures Tgj and Tgo are determined by the following calculation formula.

Tg i=Tgo+
(5) Wg °Cpg Here, Cpg: Gas specific heat (constant) Wg: Measured value with gas flow rate gas thermometer 30 is 1! ff Let the outlet gas temperature of the coal economizer 5 be Tgo, and calculate the inlet gas temperature 'T''gi of the coal economizer 5 from the heat absorption amount Q of the coal economizer 5 obtained by the above equation (3) and the gas flow rate Wg. Similarly, if the inlet gas temperature Tgi of this economizer 5 is the outlet gas temperature of the reheater 4,
The artificial gas temperature of reheater 4 is calculated, and finally superheater 3
The inlet gas temperature of the furnace, that is, the gas temperature of the furnace outlet 22, can be set as follows.

The gas flow rate Wg is the recirculation gas amount measured by the gas flow meter 34,
Combustion air measured by air flow meter 33, air quality data measured by dry bulb thermometer 44 and wet bulb thermometer 45, coal feed needle 4
2 and the signal from the coal property setting device 32. Note that the specific method for measuring the gas flow rate is detailed in "Heat Accounting Method for Land Boilers 2 J (JIs B 8222)" of the Japanese Industrial Standards, so the explanation thereof will be omitted here.

Us in the above formula (1) is determined by the following formula.

Us=f (Tg, Ts, Vg, Vs) (6)
Here, vg, gas flow rate s; water, steam flow rate The boiler condition calculator 102 calculates the furnace outlet temperature obtained based on the equation (5), the boiler outlet gas temperature measured by the gas thermometer 30, and the spray temperature. Ratio of spray amount and feed water flow rate (=main steam instant) based on signals from feed water flow meter 40 and feed water flow meter 35, coal feed clear meter 42, coal property setting device 32, constricted air flow meter 33, dry bulb thermometer 44 and wet bulb thermometer 45
The ratio between the amount of combustion gas calculated based on the signal from the gas flow meter 34 and the amount of recirculated gas measured by the gas flowmeter 34 (recirculated gas amount ratio) is calculated.

The contamination state priority setting unit 103 is capable of calculating and setting a numerical value between O and 1 according to the degree of contamination of the heat transfer surface of each heat exchanger.

The dirty state priority means the activation priority of the soot blower 27 of the heat exchanger relative to other heat exchangers.

FIG. 3 shows the relationship between the contamination state priority (Y) and the contamination state index (Kf) on the heat transfer surface of each heat exchanger.

The inclination angle (gradient) and lower limit value of the characteristic line in FIG. 3 vary depending on the heat exchanger and operating conditions, and are set based on simulations, operator experience, etc.

In the dirt state priority calculator 104, the dirt state priority calculator 10
1, and the dirt state priority Yj is calculated by the function of the dirt state priority setter 103.The calculation of this dirt state priority Y is illustrated in FIG. K
fl and Kru are the lower @ value and upper limit of the soil condition index, and Yl and Yu are the lower limit and upper limit of the soil condition priority Y.

As it is clear from this figure becomes. Note that j indicates the type of heat exchanger.

In the dirty state priority operator 104, the dirty state calculator 101
The signal Kf' N obtained by is used as a function of the type of heat exchanger) and the dirt state priority setter 103 to calculate the dirt state priority YJ.

The boiler condition priority setting device 105 is capable of calculating and setting a numerical value between O and 1 according to the degree of unhealthiness of the boiler condition. The boiler condition priority is the soot blower 27 compared to the dirty condition priority.
This means the function to check the startup priority of . As described above, in this embodiment, the furnace outlet gas temperature, spray amount ratio, recirculation gas amount ratio, and boiler outlet gas temperature are defined as the boiler operating state.

For example, the spray amount ratio is related to the decrease in the amount of heat absorbed by the furnace ice wall portion 12 and the superheater 3, and the recirculation gas amount ratio is related to the reduction in the amount of heat absorbed by the furnace water wall portion 12.
, is related to a decrease in the amount of heat absorbed by the reheater 4.

The boiler status priority calculator 106 calculates the boiler status priority X using the functions from the boiler status calculator 102 and the boiler status priority setter 105.

The boiler status priority X is shown in Fig. 4, Fig. 5 (a), (b),
°ζ will be explained using (c) and (d).

In FIG. 4, the vertical axis indicates the boiler condition priority I\X, the horizontal axis indicates the boiler condition index Z, and shows the relationship between them, and Ze and ztl indicate the lower limit value and upper limit value.

In addition, in Fig. 5 (a) and (b), the vertical axis shows the soot blower starting priority, and the horizontal axis shows the spray amount ratio, and in Fig. 5 (C) and (d), the vertical axis shows the soot blower starting priority, and the horizontal axis shows the soot blower starting priority. The recirculation gas amount ratio is shown and the relationship between them is shown.

As shown in FIG. 5(a), when the spray amount ratio is larger than the spray reference value, the amount is related to the furnace ice wall portion 12, and the function in FIG. 5(a) is used as the boiler state priority.

If the spray amount ratio is smaller than the spray level value, the amount will be related to the superheater 3, and FIG. 5(b) will be used.

In addition, if the recirculation gas amount ratio is larger than the recirculation gas amount reference value, the amount will be involved in the reheater 4, and as shown in FIG.
).

On the other hand, if the recirculation gas amount ratio is smaller than the recirculation gas amount reference value, the amount will be involved in the furnace ice wall section 12, and the fifth
Use diagram (d).

In the boiler status priority calculator 106, the boiler status calculator 1
The boiler state B priority xj is calculated using the boiler state index Zj from 02 and the function of the boiler state priority setter 105.

In other words, the boiler condition index Z related to the furnace ice wall section 12 is set in two ways by the boiler condition priority setting device 105.
When the spray amount ratio is larger than the spray reference value and the recirculation gas amount ratio is smaller than the recirculation gas amount reference value, two types of soot blower activation priority are calculated by the boiler type B priority/iii calculator 106. Among the degrees, the one with the larger value is set as the soot blower activation priority of the boiler state furnace water wall section 12.

Furthermore, only one type of soot blower activation priority for the superheater 3 and reheater 4 can be obtained.

In the composite state priority calculator 107, the dirt state priority and boiler state priority are obtained for each heat transfer surface j based on the signals from the dirt state priority calculator i04 and the boiler state priority calculator 106. The state priority and boiler state priority are compared, and the priority with the smaller value is selected as the composite state priority.

The situation is shown in FIG. If written in the formula, Mj=mi
n(yj, x, i) (8) FIG. 6 is a diagram showing an example of the calculation result by the composite state priority calculation unit 107, and the marks in the figure indicate the results output from the dirty state priority calculation unit 104, respectively. The ○ mark indicates the priority regarding the boiler state outputted from the boiler state priority calculator 106, and the mark 201 indicates the furnace fouling state priority, and the O mark 202 indicates the furnace outlet gas. With temperature priority,
Both are related to the furnace ice wall, so they are shown on the same line. - Mark 203 is the superheater dirt condition priority, and ○ mark 204 is the spray flow rate ratio priority, and since both are related to the superheater, they are shown on the same line of that item.・The mark 205 is the reheater dirty state priority, and the ○ mark 206
is the recirculation gas amount ratio priority, and since both are related to the reheater, they are shown on the same line of that item.・Mark 207
indicates the economizer dirt status priority, and 208 marked with a circle indicates the boiler outlet gas temperature priority, and since both are related to the economizer, they are shown on the same line.

The heat transfer surface fouling condition priority and the boiler condition priority are compared for one heat exchanger, and as a result, the lower priority is automatically selected. That is, in the case of FIG. 6, the priority marked with * is selected by the composite state priority calculator 107.

The activation candidate location selector 108 selects candidates in descending order of composite state priority based on the composite state priorities from the composite state priority calculator 107. Figure 7 shows the situation.

In FIG. 7, as shown in FIG. 7, as a result of comparing the synthetic state priorities, the furnace outlet gas temperature priority 202 for each heat exchanger
Superheater dirty condition priority 203, reheater dirty condition priority 2
05 and the economizer dirt status priority 207 are selected, and among these, the furnace outlet gas temperature priority 202, which has a higher priority, and is indicated by the * mark in the figure, is selected as a candidate location.

Next, the boiler load compensation calculator 109 starts a predetermined soot blower 27 based on the output signal from the startup candidate location selector 108, but at this time, the boiler load is determined via the boiler load calculator 1.10. and when the boiler load is 50% or more of the rated value, the soot blower drive unit 2
9, the soot blower 27 is driven to remove soot.

However, when the boiler load is less than 50% of the rating,
Even if there is an output signal from the activation candidate location selector 108, activation of the soot blower 27 is stopped.

For the sake of simplicity, 50% of the boiler load rating is used as the branching point in the explanation, but in reality, various values such as 30% of the rating are used depending on the boiler type and capacity.

Furthermore, depending on the location of the heat transfer surface, for example, the furnace part has a rating of 6
0% is the turning point, 50% for superheater and 4 for reheater.
According to the present invention, it is also possible to perform subtraction in the boiler 9 load compensation calculator 109 so that the subtraction point is 0% and 30% for the economizer.

FIG. 9 is a diagram showing another embodiment of the present invention.

The difference from FIG. 1 is that a new memory 111 is added and the result after starting the soot blower 27 is transferred to the memory 111.
The system is configured so that it can be stored in memory, and a decision can be made at the next startup.

In FIG. 9, 102 to 108 and 29.27 are the same as in FIG. 1, and their explanation will be omitted. When a request to start the soot blower 27 is issued from the start candidate location selector 108, the boiler load at this time is read by the boiler load calculator 110 and written in the memory 111. and,
After starting the soot blower 27 by the soot blower driving device 29, the draft fluctuation and/or the denitrification rate are read from a detector (not shown) in the boiler, and the results are stored in the memory 1.
11 is stored in correspondence with the previous boiler load.

1, the draft fluctuations and the results of denitrification 54 after activating the suction 1 no'+rl machine every time the boiler load changes are stored in the memory lli. When the draft fluctuation and denitrification rate are within predetermined tolerance values, the soot blower is started according to the request from the startup candidate point selector 108, but the boiler load decreases and the draft fluctuation or denitrification rate is within the allowable range after starting the j2 soot blower. When the value exceeds this value, this is determined before the next soot blower activation, and activation of the soot blower is suppressed.

In other words, if you start the soot blower when the boiler load is 50% of the rated value, the draft fluctuation will be 5% or less and the denitrification rate will be 9.
If the soot blower is started when the boiler load is 30% of the rated value, the memory 111 stores that the draft fluctuation was 20% and the denitrification rate was 70%. do. At this time, the allowable value for draft fluctuation is 10% or less, and the allowable value for denitrification rate is 75%.
Based on the above, if the boiler load is around 30% when the soot blower is started next time, the soot blower will not be started immediately, but will be started after a predetermined period of time, and compared to normal startup,
Reduce the frequency of startup times. Then, store the results in memory for future reference.

By doing so, it is possible to suppress the activation of the soot blower when the boiler load is reduced, so that it is possible to prevent a sudden drop in exhaust gas temperature, and at the same time, it is possible to reduce the number of occurrences of draft fluctuations.

FIG. 10 is a diagram showing another embodiment of the present invention. 1st
In FIG. 0, the same symbols as in FIG. 1 indicate the same operations. What is different from Fig. 1 is the boiler load compensation calculator 10.
9 is eliminated, and the soot blower drive device 29 is directly driven by the output of the activation candidate location selector 108. Furthermore, a dirt state u(+previous load compensator 112 is inserted between the dirt state priority calculator 104 and the composite state priority calculator 107).

With this configuration, as shown in Fig. 11, the degree of contamination B(, Y) is compensated for depending on the size of the boiler load.In other words, if there is no compensation, when the contamination condition index is Kf, The dirty state priority is Y1, but with the compensation of the present invention, the dirty state priority becomes Y,° when the boiler load is 40%.Therefore, this dirty state priority Y+
Since the soot blower activation point is determined by the next composite form B/l&priority calculator 107 based on ', this means that the priority of soot blower activation is reduced by the amount of compensation. In other words, even if the dirt is large, as the boiler load decreases, it will be considered that there is little dirt, and the activation of the soot blower will be suppressed accordingly.

In this embodiment, compensation is applied based on the boiler load, but the same effect can be obtained by using the flff coal seam temperature measured by the gas thermometer 30 in FIG. 8.

〔Effect of the invention〕

According to the present invention, the soot blower is operated appropriately according to the contamination state of the heat transfer surface of each part of the boiler and the operating state of the boiler,
In addition to cleaning the heat transfer surface, by suppressing the operation of the soot blower at low loads, it increases the unburned content in the boiler and reduces the denitrification rate of the denitrification device installed downstream of the boiler to remove NOx from the exhaust gas. , corrosion of the downstream part of the boiler, occurrence of draft fluctuations in the boiler, etc. can be reduced.

[Brief explanation of drawings]

Fig. 1 is a control system diagram of a soot blower according to an embodiment of the present invention, Fig. 2 is a block diagram of a control device of the soot blower, and Fig. 3 is a characteristic showing the relationship between contamination condition B priority and contamination condition index. The curve diagram, Figure 4, is a characteristic curve diagram showing the relationship between boiler condition priority and boiler condition index, Figures 5 (a) and (b).
, (C), and (d) are characteristic curve diagrams showing the relationship between soot blower activation priority, spray amount ratio, and recirculation gas amount ratio.
FIG. 7 is an explanatory diagram showing an example of the calculation result by the composite B priority calculation unit, FIG. 7 is an explanatory diagram showing an example of the calculation result by the soot blower activation point determination calculation unit, and FIG. 8 is the soot blower control device. 9 and 10 are control system diagrams of a soot blower according to another embodiment of the present invention, and FIG. 11 is a diagram for explaining another embodiment. . 1... Boiler device, 3... Superheater, 4... Reheater, 5... Energy saver, 27... Soot blower, 30...
・Gas temperature, 31...Oxygen concentration meter, 32...Coal property setting device, 33...Air flow meter, 34...Gas flow meter, 35...Water supply flow meter, 36...Temperature Total, 37.
...Pressure gauge, 38...Thermometer, 39...Pressure gauge, 4
0...Water supply for spray? In) meter, 41...Spray feed water thermometer, 42...Coal feed indicator, 43...Low temperature reheat steam pressure gauge, 44...Dry bulb thermometer, 45...Wet bulb temperature Total, 46... Boiler load, 52... Damper,
100... Soot blower control unit main body, 101... Contamination status calculator, 102... Boiler status calculator, 103
... Dirt status JU4 priority setter, 104... Dirt status priority calculator, 105... Boiler status priority setter,
106... Boiler state priority computing unit, 107... Combined state priority computing unit, lO8... Starting candidate location selector, 109...: Boiler load compensation computing unit, 110... Boiler load computing unit , 111...Memory, 112...Dirty state priority load compensator. Figure 2 Applicant Pubcock Hitachi Co., Ltd. Agent Patent Attorney Takeshi Kawakita Cho Figure Tongue - Contamination condition index (f) Figure 38: Thermometer 39: Pressure gauge 51: Damper 52: Denitration equipment 1: Boiler 2: Furnace 3: Superheater 15: Burner 16: Boiler outlet [] 2.1: Regulating valve for recirculation gas flow f+ 25: Hopper 26: Recirculation gas flue

Claims (3)

[Claims] (1) A soot blower control device that is equipped with a device that detects the dirt status of heat transfer surfaces of a plurality of heat exchangers provided in a boiler, and operates a soot blower that cleans these heat transfer surfaces based on a detection signal from this device, Contamination condition priority that calculates the starting priority of the soot blower based on signals from a contamination condition calculator that calculates the contamination condition of the heat transfer surface of each heat exchanger and a contamination condition priority setting device that outputs a value according to the contamination condition. The soot blower startup priority is calculated based on the signals from the temperature calculator, the boiler status calculator that calculates the operating status of each heat exchanger, and the boiler status priority setter that outputs a value according to the boiler operating status. The priority of the smaller value of the dirt status priority and boiler status priority for each heat transfer surface obtained from the boiler status priority calculator, the dirty status priority calculator, and the boiler status priority calculator is a composite state priority calculator that selects a heat transfer surface as a priority; an activation candidate location selector that selects a soot blower that cleans a heat transfer surface that has a high priority based on the output from the composite state priority calculator; A boiler load calculator that generates a signal appropriate for the boiler load, and a soot blower selected by the start candidate point selector when the boiler load exceeds a predetermined value based on signals from the boiler load calculator and the start candidate point selector. What is claimed is: 1. A soot blower control device comprising a boiler load compensation calculator. (2) In claim (1), the relationship between the boiler load value at the time of starting the soot blower, the boiler draft fluctuation value when the soot blower is operated, and/or the fluctuation value of the denitrification rate of the denitrification device is stored, and A soot blower control device comprising a device that allows a boiler load compensation calculator to output a soot blower activation signal only when the boiler load value is within a predetermined range. (3) A soot blower control device that is equipped with a device that detects the dirt status of the heat transfer surfaces of a plurality of heat exchangers installed in the boiler, and operates a soot blower that cleans these heat transfer surfaces based on a signal from this device. Contamination condition priority that calculates the starting priority of the soot blower based on signals from a contamination condition calculator that calculates the contamination condition of the heat transfer surface of the heat exchanger and a contamination condition priority setting device that outputs a value according to the contamination condition. a computing unit, a boiler load computing unit that generates a signal commensurate with the boiler load, and a fouling status priority load compensator that compensates the output of the fouling status priority computing unit using the output of the boiler load computing unit;
Boiler status priority calculation that calculates the starting priority of the soot blower based on signals from the boiler status calculator that calculates the operating status of each heat exchanger and the boiler status priority setter that outputs numerical values according to the boiler operating status The smaller value of the dirty state priority and boiler state priority for each heat transfer surface obtained from the dirty state priority load compensator and boiler state priority calculator is assigned to that heat transfer surface. The present invention includes a composite state priority calculator that selects the priority, and an activation candidate location selector that selects the soot blower that cleans the heat transfer surface that has a high priority based on the output from the composite state priority calculator. Characteristic soot blower control device.