JPS62172108A - Soot blower control device - Google Patents

Abstract

PURPOSE:To stabilize the steam temperature of a heating surface on the downstream side, by a method wherein, with a soot blower started, only the specified heating surface of a heat exchanger is not cleaned, and a heating surface positioned on the upper stream side and a heating surface positioned on the downstream side are cleaned in conjunction with each other. CONSTITUTION:In a boiler device 1, by burning supplied pulverized coal by means of a burner 15, ash and soot are adhered and deposited to the heating surfaces of a furnace water wall part 12, a superheater 3, a reheater 4, and an economizer 5 to reduce heat transmission efficiency and bring a boiler into an unsound operating state. In order to blow off adhered and deposited ash and soot, a soot blower 27 depending upon each heat exchanger is disposed. When the soot blower 27 is started to clean a heating surface, the endotherm of the heating surface is increased, and a gas temperature at an outlet is decreased. However, since, after a heating surface having the high degree of synthetic state priority 209 is cleaned, a heating surface having the low degree of synthetic state priority 210 is also cleaned in linkage, endotherm of a heating surface on the downstream side can be prevented from reduction.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a control device for a soot blower attached to, for example, a boiler device or a cracking and reforming furnace. The present invention relates to a soot blower control device suitable for determining the starting point of a soot blower.

[Conventional technology]

In a typical boiler system, heat exchangers such as a superheater, reheater, and economizer are arranged in the furnace ice wall and the gas passage connected to it, and the water and energy supplied to these heat exchangers are 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 increases at the superheater outlet, the spray injection flow rate decreases as the interface pressure decreases, and the suction in the reheater decreases the spray injection flow rate. The lack of 5ffi causes various troubles 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.

[Problem that the invention seeks to solve]

However, such a soot blower control device has the following problems.

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

(2) Originally, the soot blower is activated to prevent the steam temperature from going out of the permissible range, and should not be activated only due to the degree of contamination on the heat transfer surface. In other words, the soot blower should be activated only when the steam temperature is outside the allowable range and the heat transfer surface where the steam temperature has been lowered is highly contaminated. Conventional control JI devices do not have a function in this regard, and the activation is determined based solely on the level of dirt.

An object of the present invention is to provide soot blower control that eliminates the drawbacks of the prior art described above, does not cause the temperature to exceed the allowable range, and determines the starting point of the soot blower for a heat transfer surface that is considerably contaminated. ■It provides equipment.

[Means for solving problems]

In order to achieve the above-mentioned objects, the present invention has a contamination condition calculator that calculates the contamination condition of the heat transfer surface of a heat exchanger, and a contamination condition priority calculator that calculates the contamination condition based on signals from a contamination condition priority setting device. an operating state priority calculator that calculates the operating state from a signal from the operating state priority setting device and a signal of the operating state of the heat exchanger; and a dirt status priority calculator output from the dirt status priority calculator. , a composite state priority calculator is provided for selecting a smaller priority of the operating state priorities outputted from the operating state priority calculator, and at least two composite states G are selected from the composite state priority and the outlet gas temperature signal. (If the heat exchanger with the higher composite state priority is located upstream of the two composite state priorities and is equipped with a soot blower activation point determiner that selects the priority, the soot blowers are connected in the order of the composite state priorities.・It is controlled to assist in cleaning.

[Effect]

The present invention does not clean only a specific heat transfer surface of a heat exchanger by activating a soot blower, but cleans the heat transfer surface located on the upstream side and the heat transfer surface located on the downstream side in conjunction with each other. The steam temperature on the side heat transfer surface can be stabilized.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 6 is a schematic configuration diagram of a boiler device equipped with a soot blower control device according to an embodiment.

1 in the figure is a boiler device, and the high-temperature combustion gas generated in the furnace 2 is transferred to a group of heat exchangers, namely the furnace ice wall section 12, heater 3, reheater 4 due to the pressure difference caused by the induced draft fan 11.
, the energy saver 5, heat is given to the water and steam in the heat exchanger, and the air is further passed through the air preheater 7 and discharged outside the system.

Coal, which is fuel, is supplied from a coal feeder 21 to a pulverizer 9, and then passed through a pulverized coal pipe 13. Burner 1 through burner wind box 8
It is burned in 5. On the other hand, the combustion air is supplied by forced draft fan 1.
0 passes through the main air passage 17, passes through the pulverizer 9, and is supplied to the burner 15 along with pulverized coal.

The recirculated gas is supplied by the ventilator 14 until the amount of recirculated gas i! i2
6 and enters the furnace 2 from the hopper part 25.

The amount of recirculation gas is adjusted by a recirculation gas flow rate control valve 24.

Water, which is the fluid to be heated, is sent to the energy saver 5 by the water supply pump 6, and then passes through the furnace water wall 12 and the superheater 3, where it absorbs heat and becomes high-temperature, high-pressure steam, passing through the main steam pipe 18. and sent to a high-pressure turbine (not shown) outside the system.

The low temperature, low pressure steam used in the high pressure turbine is
It passes through the low-temperature reheating 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 control the steam temperature in the superheater 3, the spray 2
3, low temperature water is injected into the steam of 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.

In addition, if the gas temperature at the furnace outlet 22 is too high,
Since this will adversely affect the material and lifespan of the superheater 3, the recirculation gas flow rate control valve 24 is closed to reduce the amount of recirculation gas.

Further, if the gas temperature at the boiler outlet 16 is higher than the specified value, this indicates that the boiler efficiency is low.

The amount of spray injected into the superheater 3 by the above-mentioned spray 23 (for forming -, take the ratio of the spray amount to the main steam amount, that is, the spray ratio), the amount of recirculated gas (for forming -, take the ratio of the spray amount to the main steam amount, that is, the spray ratio), In this embodiment, the boiler operating state is defined as the ratio of the gas amount to the gas amount due to combustion, that is, 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 I having such a configuration, by burning the supplied pulverized coal in the burner 15, the furnace ice wall portion 12. Superheater 3. Ash, soot, etc. adhere to and accumulate on the heat transfer surfaces of the reheater 4 and the economizer 5, reducing heat transfer efficiency and making the boiler in an unhealthy operating state. In order to blow off the adhering ash, soot, etc. mentioned above, a soot blower 27 is arranged corresponding to each heat exchanger, but in order to avoid complicating the drawing, in FIG. Only the following are 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 in order to grasp the properties of the combustion gas, and an inlet pressure gauge 47 and an oxygen concentration meter 47 are provided to detect gas flow passing through the heat exchanger.
Outlet pressure, total 48 is placed.

An air flow meter 33 is installed in the main air duct 17 to measure the amount of combustion air supplied to the burner 15. A gas flow meter 34 is installed in the recirculation gas flue 26 to measure the amount of combustion gas supplied to the hopper 25. Dry bulb thermometer 44 and wet bulb thermometer 45
Air condition measuring boxes 28 each containing a built-in air conditioner are arranged.

A water supply flow meter 35 is provided on the outlet side of the water supply system of the water supply pump 6, and a spray water supply flow meter 40 is provided on the inlet side of the sprayer 23.
and a spray feed water thermometer 41, and a low temperature reheat steam pressure gauge 43 for estimating the flow rate are disposed on the outlet side of the low temperature reheat steam pipe 19, respectively.

In addition, thermometers and pressure gauges are installed on the inlet and outlet sides of each heat exchanger to gauge the properties of water and tea.
In order to simplify the drawing, only those related to the economizer 5 are shown in FIG. 6. That is, a population thermometer 36 and a pressure gauge 37 are installed on the inlet side of the economizer 5, and an outlet thermometer 3 is installed on the outlet side.
8 and a pressure gauge 39 are respectively arranged.

A coal feed needle 42 is provided on the exit side of the coal feeder 2, and a coal property setting device 4 is further provided for grasping the combustion properties of the pulverized coal.
6 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 control valve 24. Gas thermometer 30. Oxygen concentration meter 31. Air flow meter 33. Gas flow meter 34. Water supply flow meter 35. Inlet thermometer 36° Pressure gauge 37. Outlet thermometer 38
．． Pressure gauge 39. Water supply flow meter for spray 40. Spray water supply thermometer 41° Charcoal supply needle 42. Low temperature reheat steam pressure gauge 4
3. Dry bulb thermometer 44. Wet bulb thermometer 45. Inlet pressure gauge 47
．． A detection signal from an outlet pressure gauge 48 and a setting signal from a coal property setting device 46 are respectively input.

Next, a schematic configuration of the soot blower control unit main body 100 will be explained with reference to FIG. 1. As shown in the figure, a heat transfer surface contamination condition calculator 101 and a contamination condition priority setting device 102 form a pair, and a signal is inputted to a contamination condition priority calculation device 103. Also, superheater 3. The steam temperature of the reheater 4, the superheater spray amount, and the signal from the separately arranged operating state priority setting device 104 are used to input signals to the operating state priority calculator 105 which calculates the operating state priority. It has become. The dirt status priority calculator 103
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 operating state priority calculator 105 calculates the superheater 3. It has a function of calculating the activation priority of the soot blower based on the steam temperature of the reheater 4 and the amount of superheater spray.

Further, a composite state priority computing unit 106 performs a minimum type multi-value logical operation based on the signal input from the dirty state priority computing unit 103 and the operating state priority computing unit 105, and from the computing unit 106 and the boiler status computing unit 101. The soot blower activation point determination calculator 107 determines the activation point of the soot blower based on the signal.

A drive signal from the soot blower control unit main body 10o (soot blower activation point determining calculator 107) is input to the soot blower driving device 29, and the selected soot blower 27 is activated accordingly.

The contamination condition calculator 101 calculates the contamination condition of the furnace ice wall section 12 based on signals from each detector that monitors the contamination condition of the heat transfer surface. Superheater 3. The contamination state of the heat transfer surfaces of the reheater 4 and the economizer 5 is calculated.

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

A・ΔLm UC-(2) here, A: Heat transfer area of heat exchanger Q; Endothermic amount Δtm: indicates logarithmic average temperature difference.

The heat transfer area A is determined from the design data, and the heat absorption iQ is
It is determined from the heat balance on the water and steam sides of the heat exchanger.

The logarithmic average temperature difference Δtm is determined from the temperature of the water/steam on the heat transfer surface and the inlet/outlet temperature of the gas.

The water/steam temperature can be measured with a thermometer placed at the entrance/exit of each heat exchanger, and in the case of the economizer 5, it can be measured with an inlet thermometer 36 and an outlet thermometer 38.

Gasmet poetry Tgi and Tgo are calculated using the following formula.

Here, Tgi H heat exchanger inlet (gas upstream side) gas temperature TgoH heat exchanger outlet (gas downstream side) Gas temperature Wg; Gas flow rate cpg; Measured value with gas specific heat gas thermometer 30 is converted to economizer 5 outlet gas temperature T
go, and the inlet gas temperature T g i of the economizer 5 is determined from the heat absorption amount Q of the economizer 5 and the gas flow NWg.

Using this inlet gas temperature Tgi as the outlet gas temperature of the reheater 4, the inlet gas temperature of the reheater 4 is calculated.

The gas temperature on the upstream side is calculated sequentially from the gas downstream side, and finally the inlet gas temperature of the superheater 3, that is, the furnace outlet 2
It is possible to estimate up to 2 gas temperatures.

The gas flow IWg can be determined in proportion to the pressure difference between the inlet pressure gauge 47 and the outlet pressure gauge 48 and the square of the overgas velocity of 1iTl.

Further, Us in formula (1) is obtained by the following formula.

Us=f (Tg, Ts, Vg) (4) where, Tg: gas temperature TS; temperature of water and steam g: gas flow rate, which can be determined from the gas flow rate Vg.

Next, the contamination state priority setter 102 sets the maximum allowable contamination degree and minimum contamination degree for each heat transfer surface.

The term "contamination state" refers to the start-up priority of the soot blower belonging to the heat exchanger relative to other heat exchangers depending on the contamination state. The soot blower activation priority will be explained with reference to FIG. 3. In FIG. 3, the vertical axis represents the soiled state soot blower activation priority, and the horizontal axis represents the soiled state.

The upper and lower limits of the line in FIG. 3 vary depending on the heat exchanger, and are set by simulation or the like.

In the dirt state priority calculator 103, the dirt state priority calculator 10
The dirt state priority yj is calculated using the signal Kfj from the dirt state priority setter 102 and the signal from the dirt state priority setter 102. j represents the type of heat exchanger.

The operating state priority setter 104 sets upper and lower allowable operating state limits for each heat transfer surface.

The furnace water wall 12 corresponds to the superheater spray amount, the superheater 3 corresponds to the main steam temperature, and the reheater 4 corresponds to the reheated steam temperature, and the boiler conditions of other heat transfer surfaces are not set.

The upper and lower limits of settings are set based on design data, simulation, etc.

The operating state c and priority calculator 105 determine the operating state based on the signal from the operating state 1 priority setting device 104 and the values of the superheater spray amount, main steam temperature, and reheat steam temperature, which are external signals. Priority xj is 1? Calculate A. The calculation method is the same as the content of the dirt status calculator 101.

Based on the signals from the dirty state priority computing unit 103 and the operating state priority computing unit 105, the combined state priority computing unit 10
In step 6, the dirty state priority and the operating state priority are compared for each heat exchanger, and the smaller priority is selected. Note that there is no operating state for the economizer 5.

FIG. 4 shows how the priority is selected.

If described in the formula, M j = min (X L Y j) Fig. 4 is a diagram showing an example of the calculation result by the composite state priority calculation unit 106, and the mark in the figure indicates the dirty state priority calculation R. '? = 10
The priority regarding the dirt status output from 3, ○
The marks indicate the priorities output from the operating state priority calculator 105, and the mark 201 indicates the priority of the furnace ice wall section 12.
The contamination state priority, 202 marked with a circle, is the gas temperature priority at the furnace outlet 22, and since both are related to the furnace water wall 12, they are shown in the same award for that item. The mark 203 is the dirt status priority of the superheater 3, and the symbol 204 is the spray flow rate priority.Since both are related to the superheater 3, they are shown on the same line.・The mark 205 is reheat 234
206 is the priority of the contamination state, and 206 marked with an O is the priority of the recirculation gas amount ratio, and since both are related to the reheater 4, the items are shown on the same line.

The symbol 208 marked with a circle is the boiler outlet gas temperature priority, which is shown on the line of that item because it is related to the nodal bulge.

The contamination status priority of the heat transfer surface and the operating status priority for one heat exchanger are compared, and as a result, the lowest one, 14, is automatically selected as the priority. That is, in the case of FIG. 4, the priority marked with * is selected.

The soot blower starting point determiner 107 determines the optimum starting point and timing based on the signal from the composite state priority calculator 106 and the boiler outlet gas temperature signal from the contamination state calculator 101. When the boiler outlet gas temperature decreases to the specified value, first, the composite state fR priority calculator 106
Among the signals, the highest composite state priority 2
09. Find the lower composite state priority 210. This situation is shown in FIG. In Fig. 5, the mark 209 indicates a high composite state f, (fj6 priority, and the mark 210 indicates a low composite priority. As shown, the heat transfer surface of the furnace ice wall portion 12 has a high composite state priority. If the temperature reaches 209, check whether the heat transfer surface of the reheater 4 on the downstream side of the gas has become a low composite state priority of 210.If the heat transfer surface of the reheater 4 on the downstream side is low. When the composite state priority is 210, the heat transfer surface of the furnace ice wall portion 12 that has a high composite state priority of 209,
The heat transfer surface of the reheater 4, which has a low synthesis state priority of 210, is determined as the optimum heating point. Clean the heat transfer surface of state 209 first,
The heat transfer blood with the next lowest synthesis state priority 210 is cleaned.

As described above, according to the soot blower control device of the present invention, the boiler condition becomes unhealthy (the main steam temperature, the reheat steam temperature decreases,
At least two locations (locations exhibiting a high composite state priority 209 and a low composite state priority 210) are determined by increasing the amount of spray (increased spray amount) and having large heat transfer surface contamination.

Generally, when the soot blower 27 is activated to clean a certain heat transfer surface, the amount of heat absorbed by that heat transfer surface increases and the outlet gas temperature decreases. Therefore, the amount of heat absorbed by the gas downstream heat transfer surface increases, and if the steam airflow is different (hand steam, reheated steam), the steam temperature corresponding to the downstream heat transfer surface decreases, resulting in an unhealthy boiler condition (steam (Decrease in plant efficiency due to temperature drop).

However, after cleaning the heat transfer surface with a high composite state priority of 209, cleaning work is also performed on the heat transfer surface with a low composite state priority of 210, resulting in a decrease in the amount of heat absorbed by the downstream heat transfer surface. can be prevented.

Furthermore, if a heat transfer surface with a low composite state priority 210 is located on the gas upstream side of a high composite state priority 209, the heat transfer surface with a low composite state priority 210 is ignored and is not cleaned by the soot blower 27. .

Thereby, the amount of steam 7 required for cleaning the heat transfer surface can be reduced.

〔Effect of the invention〕

(1) Stabilization of boiler steam temperature The present invention lowers the steam temperature and determines the areas with large contamination on the heat transfer surface, so when the soot blower is activated, the contamination on the heat transfer surface is removed and at the same time the steam temperature is stabilized. become.

Even if the heat transfer surface is heavily contaminated, the soot blower will not be activated if the deviation of the steam temperature from the reference value is not large. If the soot blower is started simply due to dirt on the heat transfer surface, the amount of heat absorbed may increase excessively and the steam temperature may become too high.

This stabilizes the boiler steam temperature.

(2) Reduction in the amount of soot blower injection medium used Even if the heat transfer surface is only slightly contaminated, the steam temperature may deviate significantly from the reference value. In this case, even if the soot blower is started, there is little dirt on the heat transfer surface, so there is little effect in removing ash. Therefore, starting the soot blower is wasted. The present invention eliminates soot blower activation in such cases. Therefore, the amount of injection medium used by the soot blower can be reduced.

[Brief explanation of drawings]

All figures are for detailed explanation of the present invention.
Figure 2 is a block diagram of the soot blower control device, Figure 2 is a block diagram of the soot blower control unit, Figure 3 is a characteristic diagram showing the relationship between the soot blower activation priority and the contamination state in each heat exchanger, and Figure 4 is the combined state. FIG. 5 is an explanatory diagram showing an example of the calculation result by the priority calculation unit. FIG. 5 is an explanatory diagram showing an example of the calculation result by the soot blower operating point determination calculation unit. FIG. It is a schematic block diagram of the boiler apparatus provided with the apparatus. ■・・・Boiler equipment, 3・・・Superheater, 4
... Reheater 5 ... Energy saver, 27 ...
... Soot blower, 30 ... Gas temperature, 31
...Oxygen concentration meter, 33... Air flow rate old 34... Gas flow meter, 35... Water supply flow meter, 36... Inlet Thermometer, 37...
Pressure gauge, 38... Outlet thermometer, 39...
・Pressure gauge, 40... Spray water supply flow meter, 4
1...Spray water supply thermometer, 42...
・Coal feed needle, 43...Low temperature reheat steam pressure gauge, 4
4... Dry bulb thermometer, 45... Wet bulb thermometer, 46 Old... Coal property setting device, 47... Inlet pressure gauge, 48... ...Outlet pressure gauge, 100...
. . . Soot blower control unit main body, 101 . . . Contamination state calculator, 102 .
・・・・・・Due to operating condition, advance setting device, 105...
...Operating state priority calculator, 106...Synthetic state i ■Priority calculator, 108...Soot blower starting point determiner, 209...High synthetic state priority , 210...low synthetic state priority. K gu Seisei Paho 2 □ Picture 3 Figure 4 + V 2 Leg Chi Reito Figure 6

Claims (1)

[Claims] A dirt status calculator that calculates the dirt status of the heat transfer surface of the heat exchanger, a dirt status priority calculator that calculates the dirt status based on the signals from the dirt status priority setter, and an operating state priority calculator that calculates the operating state from the signal and the signal of the operating state of the heat exchanger; a dirt priority output from the dirt priority calculator; and a dirt priority output from the operating state priority calculator. a composite state priority calculator for selecting the smaller priority of the operating state priorities, and a soot blower activation point determiner for selecting at least two composite priorities from the composite state priorities and the outlet gas temperature signal; A soot blower control device characterized in that when a heat exchanger with a higher combined state priority among two combined state priorities is located on the upstream side, the soot blowers are controlled to be cleaned in conjunction with each other in the order of the combined state priorities. .