JPH0454844B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Application of the Invention] 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 equipped with a computing unit that determines a starting point.

[Background of the invention]

In a normal boiler system, heat exchangers such as a superheater, reheater, and energy saver are arranged in the furnace water wall and the gas passage connected to it, and the water and steam supplied to these heat exchangers are The fluid to be heated 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 rises, the spray injection flow rate decreases as the steam temperature and pressure rise in the superheater decreases, and the amount of heat absorbed by the reheater is insufficient. Therefore, various troubles occur, such as having to input an excessive amount of recirculation gas, or causing the boiler outlet gas temperature to rise excessively, 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 for starting a soot blower was determined by estimating the level of contamination on the heat transfer surface of each heat exchanger, displaying the size of the contamination on a CRT screen, and then operating the soot blower in areas with a large degree of contamination. A staff member had issued a command to start the soot blower.

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

(1) Operators' work efficiency is poor because they must constantly monitor the CRT screen.

(2) Originally, a soot blower was started to prevent the steam temperature from becoming unstable.
It should not be activated only based on the degree of contamination of the heat transfer surface. In other words, the steam temperature becomes unstable,
In addition, the soot blower should be activated only when the heat transfer surface is highly contaminated. Conventional control devices do not have a function in this regard, and make activation decisions based solely on the level of dirt.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a soot blower control device that eliminates the above-mentioned drawbacks of the prior art, prevents the steam temperature of a device equipped with a soot blower from becoming unstable, and is highly efficient.

[Summary of the invention]

In order to achieve this object, the present invention provides a contamination state calculator that calculates the contamination state of the heat transfer surface of a heat exchanger and a contamination state priority setting device that calculates the startup priority of the soot blower based on signals from a contamination state priority setter. a boiler condition priority calculator that calculates the activation priority of the soot blower based on the signals from the boiler status calculator and the boiler condition priority setter that calculate the operating status of the heat exchanger; a priority calculator that calculates the priority based on the dirt status priority output from the dirt status priority calculator and the boiler status priority output from the boiler status priority calculator;
The present invention is characterized by comprising a soot blower activation point determining arithmetic unit which sets the higher one of the priorities as the soot blower activation priority.

[Embodiments of the invention]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 8 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 the heat exchanger group, that is, the furnace water wall section 1 by the pressure difference generated by the induced draft fan 11.
2. The air passes through a superheater 3, a reheater 4, and an economizer 5 in order, giving heat to the water and steam in the heat exchanger, and then passes through an air preheater 7 and is discharged outside the system.

Coal, which is a fuel, is supplied from a coal feeder 21 to a pulverizer 9, and then passes through a pulverized coal pipe 13 and a burner wind box 8 to be burned in a burner 15. On the other hand, the combustion air is passed through the main air passage 17 by the forced draft fan 10, passes through the pulverizer 9, carries pulverized coal, and blows into the burner 1.
5.

The recirculated gas enters the furnace 2 from the hopper 25 through the recirculated gas flue 26 by the ventilator 14 . 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 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 rises in temperature, becoming high-temperature, high-pressure steam and passing through the main steam pipe. 18 to a high-pressure turbine (not shown) outside the system.

Steam that has become low temperature and low pressure after being used in the high-pressure turbine passes through the low-temperature reheat steam pipe 19, enters the reheater 4, absorbs heat, becomes high temperature and high pressure again, and passes through the high-temperature reheat steam pipe 20 to the low pressure outside the system. to a turbine (not shown). Note that when it is necessary to control the steam temperature in the superheater 3, low-temperature water is injected into the steam in the superheater 3 by the spray 23.

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

Furthermore, if the gas temperature at the furnace outlet 22 is too high, this will adversely affect the material and life of the superheater 3, so the recirculation gas flow 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 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) and the ratio of the gas amount due to combustion, that is, the recirculated gas amount ratio), the gas temperature at the furnace outlet 22, and the boiler outlet 16
In this example, the gas temperature of is defined as the boiler operating state.

In such a boiler device 1, by burning the supplied pulverized coal in the burner 15, the furnace water wall section 12, superheater 3, reheater 4,
Ash, soot, etc. adhere to and accumulate on the heat transfer surface of the economizer 5, reducing heat transfer efficiency and making the boiler in an unhealthy operating state. In order to blow off the adhering ash and medium mentioned above, a soot blower 27 is arranged corresponding to each heat exchanger, but in order to avoid complicating the drawing, in FIG. only shown in the figure.

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 ascertain the properties of the combustion gas.

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, and 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. , an air condition measuring box 28 containing a dry bulb thermometer 44 and a wet bulb thermometer 45 are respectively 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 and a spray water supply temperature meter 41 are provided on the inlet side of the spray 23.
On the outlet side of the low temperature reheat steam pipes 19, low temperature reheat steam pressure gauges 43 for estimating the flow rate are arranged.

In addition, a thermometer and a pressure gauge are installed on the inlet and outlet sides of each heat exchanger in order to ascertain the properties of water and steam. Only those related to the above are illustrated. That is,
An inlet thermometer 36 and a pressure gauge 3 are installed on the inlet side of the economizer 5.
7, there is also an outlet thermometer 38 and a pressure gauge 3 on the outlet side.
9 are arranged respectively.

A coal feed meter 42 is provided on the exit side of the coal feeder 21, and a coal property setting device 46 for determining the combustion properties of pulverized coal is further placed on the coal feed path.

As shown in FIG. 2, the soot blower control unit main body 100 includes a recirculation gas flow rate control 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, an inlet temperature Total 36,
Pressure gauge 37, outlet thermometer 38, pressure gauge 39, spray water supply flow meter 40, spray water supply thermometer 4
1. Detection signals from the coal feed meter 42, low temperature reheat steam pressure gauge 43, dry bulb thermometer 44, wet bulb thermometer 45, etc. and setting signals from the coal property setting device 46 are inputted respectively. It's summery.

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 103 are paired together, and a signal is inputted to a contamination condition priority calculation device 104. Further, the boiler status calculator 102 and the boiler status priority setting unit 105 are paired, and a signal is inputted to the boiler status priority calculator 106. The dirt status priority calculator 104
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 status priority calculator 106 has a function of calculating the activation priority of the soot blower based on the boiler status.

Further, there is a combined state priority computing unit 107 that performs a minimum type multi-value logical operation based on the signal input from the dirty state priority computing unit 104 and the boiler state priority computing unit 106; A soot blower starting point determination calculator 1 that determines the starting point of the soot blower based on the signal of
It is equipped with 08.

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

The contamination state calculator 101 detects contamination on the heat transfer surfaces of the furnace water wall 12, superheater 3, reheater 4, and energy saver 5 based on signals from each detector that monitors the contamination state of the heat transfer surfaces. Compute the state.

The formula for calculating the contamination state of the heat transfer surface is: Kf＝Uc／Us (1) here, Kf: dirt condition index Uc: Current thermal conductivity Us: Standard state heat transfer coefficient Furthermore, Uc is determined by the following formula.

Uc=A・Δt/Q (2) here, A: Heat transfer area of heat exchanger Q; Endothermic amount Δt: Logarithmic mean temperature difference The heat transfer area A is determined from design data.

The amount of heat absorbed Q is F×H(Tsi, Psi)+Q=H(Tso, Pso)×F (3) It is determined by

Here, F: Water/steam flow rate H: Enthalpy calculation formula Ts, Ps: Temperature/pressure of water/steam, and suffixes i and o indicate the inlet side and outlet side.

The logarithmic average temperature Δt is Δt=(Tgi−Tso)−Tgo−Tsi)/In(Tgi−Tso/Tgo−
Tsi) (4) Here, Tg is the gas temperature, and i and o indicate the inlet side and outlet side.

The water/steam temperatures Tsi and Tso are measured by thermometers placed at the entrance and exit of each heat exchanger, and in the case of the energy saver 5, an exit thermometer 38 and an inlet thermometer 36.

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

Tgi=Tgo+Q/Wg・Cpg (5) Here, Cpg: Gas specific heat (constant) Wg: Gas flow rate The value measured with the gas thermometer 30 is taken as the outlet gas temperature Tgo of the economizer 5, and calculated using the above equation (3). The amount of heat absorbed by the economizer 5 Q and the gas flow rate Wg determine the amount of heat absorbed by the economizer 5.
Calculate the inlet gas temperature Tgi. Similarly, the inlet gas temperature of the reheater 4 is calculated by taking the inlet gas temperature Tgi of the economizer 5 as the outlet gas temperature of the reheater 4, and finally the inlet gas temperature of the superheater 3, that is, the furnace outlet 22 gas temperature can be estimated.

The gas flow rate Wg is based on the amount of recirculated gas measured by the gas flow meter 34, the amount of combustion air measured by the air flow meter 33, the air quality data measured by the dry bulb thermometer 44 and the wet bulb thermometer 45, and the amount of supplied coal determined by the coal feed meter 42. and a signal from the coal property setting device 46. The specific method for measuring this gas flow rate is the "Heat Accounting Method for Land Boilers" of the Japanese Industrial Standards.
(JIS B 8222), so the explanation will be omitted here.

Us in the above formula (1) is determined as follows.

Ds=f(Tg, Ts, Vg, Vs) (6) where, Vg: gas flow rate Vs: water, steam flow rate The boiler condition calculator 102 calculates the furnace outlet 22 based on the formula (5). , the gas temperature at the boiler outlet 16 measured by the gas thermometer 30, the spray amount and feed water flow rate (=main steam amount) based on the signals from the spray feed water flow meter 40 and the feed water flow meter 35.
, the combustion gas amount calculated based on the signals from the coal feed meter 42, coal property setting device 46, air flow meter 33, dry thermometer 44, and wet bulb thermometer 45, and the regeneration rate by the gas flow meter 34. Calculate and collect the ratio of circulating gas amounts (recirculating gas amount ratio) and the boiler efficiency calculated from the signals from all detectors.

In addition, the boiler efficiency by the heat input/output method is determined by the following.

Boiler efficiency = effective heat output / total heat input × 100 (7) For calculating this boiler efficiency, follow the Japanese Industrial Standards'"Heat Accounting Method for Land Boilers" (JIS B 8222)
Since it is explained in detail in , the explanation will be omitted here.

The contamination state priority setting unit 103 is configured to calculate and set a numerical value between 0 and 1 according to the degree of contamination of the heat transfer surface of each heat exchanger. The dirty state priority means the soot blower activation priority of the heat exchanger relative to other heat exchangers.

The relationship between the contamination state priority g and the contamination state index Kf in each heat exchanger will be explained with reference to FIG. 3. Figure a is a characteristic diagram of the furnace water wall section 12, Figure b
is a characteristic diagram of the superheater 3, c is a characteristic diagram of the reheater 4, and d is a characteristic diagram of the economizer 5.

The inclination angle (gradient) and upper and lower limits of the characteristic line in this figure vary depending on the heat exchanger and operating conditions, and are set based on simulations, operator experience, and the like.

The dirt state priority calculator 104 calculates the dirt state priority Yj using the signal Kjf from the dirt state calculator 101 and the dirt state priority setter 103.
Figure 4 diagrammatically illustrates the calculation of this priority level Y.
In the figure, Kfl and Kfu are the lower and upper limits of the soil condition index, and Yl and Yu are the lower and upper limits of the priority.

As is clear from this figure, when Kf ^j K ^j fl, Y ^j = Y ^j l When K ^j fl < Kf ^j K ^j fu, Y ^j = α ^j Kf ^j + β ^j Kf ^j > K ^j fu. becomes Y ^j =Y ^j u . Note that j represents the type of heat exchanger.

The boiler condition priority setting device 105 is capable of calculating and setting a numerical value between 0 and 1 according to the degree of unhealthiness of the boiler condition. The boiler condition priority means a function to check the soot blower activation priority in terms of the boiler condition with respect to the dirt condition priority.

In this embodiment, the boiler state is defined as the ratio of the superheater spray amount to the main steam amount, the ratio of the recirculated gas amount to the economizer outlet gas amount, and the gas temperature at the furnace outlet.

This superheater spray amount ratio is due to the increase in the amount of heat absorption at the furnace water wall and the decrease in the amount of heat absorption at the superheater, and the recirculation gas amount ratio is due to the decrease in the amount of heat absorption at the furnace water wall, Related to increase in heat value.

Figure 5 shows the relationship between each of these detected values, calculated values, and soot blower activation priority. Figure 5a is a characteristic diagram showing the relationship between the boiler status according to the spray amount ratio and the soot blower activation priority; It is related to the characteristics of the contamination state index and contamination state priority of the furnace water wall shown in Figure a. FIG. 5b is a characteristic diagram showing the relationship between the boiler condition and the soot blower activation priority according to the spray amount ratio, and is related to the characteristics of the superheater fouling condition index and the fouling condition priority shown in FIG. 3b.

Fig. 5c is a characteristic diagram showing the relationship between the boiler condition and the soot blower startup priority depending on the recirculation gas amount ratio, and is related to the characteristics of the reheater fouling condition index and the fouling condition priority shown in Fig. 3c. ing. Figure 5d is a characteristic diagram showing the relationship between the boiler condition and the soot blower startup priority depending on the recirculation gas amount ratio, and is related to the characteristics of the economizer fouling condition index and fouling condition priority shown in Figure 3d. ing.

That is, as shown in FIG. 5a, when the spray amount ratio is larger than the spray reference value, the amount is related to the furnace water wall 12, and the function shown in FIG. 5a is used.

As shown in FIG. 5b, when the spray amount ratio is smaller than the spray reference value, the amount is related to the superheater 3, and the function shown in FIG. 5b is used.

In addition, as shown in Figure 5c, the recirculation gas amount ratio is
When the amount of recirculated gas is larger than the reference value, the amount is related to the reheater 4, and the function shown in FIG. 5c is used.

As shown in Figure 5d, if the recirculation gas amount ratio is smaller than the recirculation gas amount reference value, the furnace water wall 1
2, and the function shown in Figure 5d is used.

The boiler state priority calculator 106 calculates the boiler state priority Xj using the boiler state Zj from the boiler state calculator 102 and the function from the boiler state priority setter 105.

In this case, two boiler conditions related to the furnace water wall 12 are set by the boiler condition priority setting device 105, but the spray amount ratio is larger than the spray reference value and the recirculation gas amount ratio is the recirculation gas reference value. If it is smaller than the value, the boiler status priority calculator 106
Of the two soot blower activation priorities calculated in , the larger value is taken as the boiler state furnace soot blower activation priority.

Note that one soot blower activation priority can be obtained for each of the superheater 3 and the reheater 4, but the economizer 5 is not defined in this embodiment.

The combined state priority calculator 107 multiplies the dirty state priority by the boiler state priority for each heat exchanger j based on the signals from the dirty state priority calculator 104 and the boiler state priority calculator 106, and then synthesizes the result. The priorities are calculated, and the higher priority among the combined priorities is set as the soot blower activation priority.

FIG. 6 is a diagram showing an example of the calculation result by the composite state priority calculator 107, in which ● marks are the priorities related to the dirt status respectively output from the dirt state priority calculator 104, and ○ marks are for the boiler. It shows the priorities regarding the boiler status outputted from the status priority calculator 106, where 201 marked with ● is the furnace fouling state priority, 202 marked with ○ is the furnace outlet gas temperature priority, and both are the furnace water wall. It is shown on the same line as the item because it is related to the section. ●marked 20
3 is the superheater dirt state priority, and 204 marked with a circle 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. 205 marked with ● is the reheater dirt state priority, and 206 marked with ○ 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. ●
The mark 207 indicates the economizer dirty state priority.

The contamination state priority of the heat transfer surface and the boiler state priority are multiplied for one heat exchanger, resulting in:
The highest priority among the combining priorities 208 to 211 is automatically selected. That is, in the case of FIG. 6, the superheater combination priority 209 is selected.

In the soot blower starting point determination calculator 108,
Based on the boiler efficiency signal from the boiler state calculator 102 and the signal from the composite state priority calculator 107, the soot blower activation point is determined.

That is, when the boiler efficiency becomes lower than a preset value, the location where the composite state priority shows the largest value is determined as the soot blower activation location. This situation is shown in Figure 7.As shown in Figure 6, as a result of comparing the composite state priorities, composite priority 209 marked with an * in Figure 7 is selected and corresponds to the superheater. A soot blower (not shown) is driven to clean the heat transfer surface of the superheater 3.

After selecting the heat exchanger that requires the most soot blower operation from among the multiple heat exchangers and cleaning the heat transfer surface, data is collected from each detector again and the same process is performed. Select the location where the soot blower will operate through the process.

In addition, as shown in FIG. 6, a high priority one is selected for each heat exchanger based on the calculation result of the composite state priority, and the soot blowers are operated in the order of the highest priority among the selected ones, Thereafter, it is also possible to collect data from each detector again and select the soot blower operating point using the same process.

〔Effect of the invention〕

The present invention has the above-mentioned configuration, and since the heat transfer surface with high synthesis priority is cleaned, the soot blower can be controlled efficiently, and the steam temperature does not become unstable, so that it can be used for cleaning. The amount of steam generated can be kept to a minimum.

[Brief explanation of drawings]

The figures are all for explaining the embodiments of the present invention, and Fig. 1 is a block diagram of the soot blower control device, Fig. 2 is a block diagram of the soot blower control main body, and Fig. 3 a, b, c, and d are each A characteristic diagram showing the relationship between the contamination state priority and the contamination state index in the heat exchanger. Figure 4 is an explanatory diagram illustrating the calculation of the contamination state priority. Figure 5 a, b, c, and d are each detection. A characteristic diagram showing the relationship between values, calculated values, and soot blower activation priority, Fig. 6 is an explanatory diagram showing an example of the calculation result by the composite state priority calculation unit, and Fig. 7 is a calculation by the soot blower activation point determination calculation unit. An explanatory diagram showing one example of the results, FIG. 8 is a schematic configuration diagram of a boiler device equipped with a soot blower control device according to an example. 1... Boiler device, 3... Superheater, 4... Reheater, 5
... Economizer, 27... Soot blower, 30... Gas temperature, 31... Oxygen concentration meter, 33... Air flow meter, 34
...Gas flow meter, 35... Water supply flow meter, 36... Thermometer, 37... Pressure gauge, 38... Thermometer, 39... Pressure gauge, 40... Water supply flow meter for spray, 41... Water supply temperature meter for spray, 42... Supply Coal amount meter, 43... Low temperature reheat steam pressure gauge, 44... Dry bulb thermometer, 45... Wet bulb thermometer, 46... Coal property setting device, 100... Soot blower control unit main body, 101... Contamination condition calculator, 10
2...Boiler condition calculator, 103...Dirty condition priority setting device, 104...Dirty condition priority calculator, 105
...Boiler state priority setting device, 106...Boiler state priority calculation unit, 107...Composition state priority calculation unit,
108... Soot blower starting point determination calculator, 20
8,209,210,211...Composition priority.

Claims (1)

[Scope of Claims] 1. A dirt status calculator that calculates the dirt status of the heat transfer surface of the heat exchanger; and a dirt status priority calculator that calculates the activation priority of the soot blower based on the signal from the dirt status priority setter. , a boiler status calculator that calculates the operating status of the heat exchanger and a boiler status priority calculator that calculates the starting priority of the soot blower based on the signal from the boiler status priority setter; and the dirt status priority calculator. a priority calculator that calculates a priority based on the dirt status priority output from the boiler status priority calculator and the boiler status priority output from the boiler status priority calculator; 1. A soot blower control device, comprising: a soot blower activation point determination calculator as a priority.