JPH07117224B2 - Sootblower control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soot blower control device attached to, for example, a boiler device or a cracking reforming furnace, and to maintain the functions of the boiler device and the cracking reforming furnace. The present invention relates to a soot blower control device having a computing means for determining the starting point of the soot blower.

[0002]

2. Description of the Related Art In a conventional boiler system, heat exchangers such as a superheater, a reheater, and a economizer are arranged in a water wall of a furnace and a gas passage connected to the water wall, and the heat exchangers are supplied to these heat exchangers. The heated fluid such as water or steam is heated by the high-temperature combustion gas generated in the furnace.

When this boiler device is in operation, ash, soot, etc. adhere to and accumulate on the heat transfer surface of the heat exchanger, and the heat exchange performance deteriorates. In addition to this, the furnace outlet gas temperature rises, the temperature of the steam in the superheater rises, the spray injection amount becomes insufficient as the pressure rise decreases, and the heat absorption amount in the reheater becomes insufficient. Various troubles occur such that the recirculated gas must be injected excessively and the boiler outlet gas temperature rises excessively to make the operating condition of the boiler unhealthy.

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

Conventionally, the soot blower start-up point is determined and the start-up timing is estimated by estimating the heat transfer surface dirt state of each heat exchanger, and the size of the dirt is displayed on a CRT screen to show the degree of dirt. On the other hand, the operator issued a soot blower start command.

[0006]

However, such a sootblower control device has the following problems.

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

(2) Originally, the soot blower is started in order to prevent the boiler state from becoming unhealthy, and should not be started only by the degree of dirt on the heat transfer surface. In other words, the soot blower should be started only when the boiler state becomes unhealthy, such as when the steam temperature is out of the allowable range, and the degree of contamination is large. The conventional control device does not have a function related to this point, and makes a start judgment only based on the degree of dirt.

The object of the present invention is to solve the above-mentioned drawbacks of the prior art, to prevent the operating state of equipment such as boiler equipment and cracking / reforming furnace equipped with soot blowers from becoming unhealthy, and to improve efficiency. To provide a good sootblower controller.

[0010]

In order to achieve this object, the present invention provides an example of detecting a heat transfer surface contamination state of a heat exchanger.
For example, a gas flow meter, an air flow meter, and other dirt condition detection means, and the operating condition of the heat exchanger, such as steam temperature.
An operating state detecting means such as a meter, a dirty state priority calculating means for determining a soot blower starting priority of the heat exchanger according to the dirty state of the heat transfer surface detected by the dirty state detecting means, and the operation An example detected by the state detection means
For example , determine the soot blower startup priority of the heat exchanger according to the operating conditions such as steam conditions.
The priority output from the operating state priority calculating means such as a step and the dirty state priority calculating means is compared with the priority output from the operating state priority calculating means, and the priority of both is lower. And a priority determining means for selecting one.

[0011]

Embodiments of the present invention will now be described with reference to the drawings.
FIG. 7 is a schematic configuration diagram of a boiler device including a sootblower control device according to the embodiment.

Reference numeral 1 in the figure denotes a boiler device, in which a high temperature combustion gas generated in a furnace 2 is heated by a pressure difference generated by an induced draft fan 11, that is, a heat exchanger group, that is, a water wall 12 of a furnace, a superheater 3, and a reheater. After passing through the vessel 4 and the economizer 5 in sequence, heat is given to the water and steam in the heat exchangers, and further passes through the air preheater 7 to be discharged to the outside of the system.

Coal, which is a fuel, is supplied from the coal feeder 21 to the differential coal machine 9, and then burned in the burner 15 through the differential coal pipe 13 and the burner wind box 8. On the other hand, the combustion air passes through the main air passage 17 by the forced draft fan 10, passes through the differential coal machine 9, and is supplied to the burner 15 together with the differential coal.

The recirculated gas passes through the recirculated gas flue 26 by the blower 14 into the hopper 25 or the furnace 2. The recirculation gas amount is controlled by the flow rate control valve 24.

Water, which is the fluid to be heated, is sent to the economizer 5 by the water supply pump 6, and further the water wall portion 12 of the furnace and the superheater 3 are supplied.
As it passes through the main steam pipe 18, it absorbs heat and rises in temperature to become high-temperature, high-pressure steam, which is sent to a high-pressure turbine (not shown) outside the system.

The steam used in the high-pressure turbine and having a low temperature and a low pressure enters the reheater 4 through the low temperature reheat steam pipe 19 and absorbs heat, becomes a high temperature and a high pressure again, and becomes a high temperature reheat steam pipe 2.
At 0, it is sent to a low pressure turbine (not shown) outside the system. When it is necessary to control the steam temperature in the superheater 3, low-temperature water is supplied to the superheater 3 by the spray 23.

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

If the gas temperature at the furnace outlet 22 is too high, the material and life of the superheater 3 will be adversely affected, so the flow control valve 24 is closed to reduce the amount of recirculated gas.

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

The spray amount supplied to the superheater 3 by the above-mentioned spray 23 (for generalization, the ratio of the spray amount and the main steam amount, that is, the spray ratio is taken), the recirculation gas amount (for generalization, Ratio of circulating gas amount and gas amount by combustion,
Immediate Chi take recycle gas volume ratio), the gas temperature and later to superheater 3 of boiler outlet 16, the reheater 4 steam conditions such as
Is defined as the operating state of the heat exchanger in this example.
It Therefore, a gas thermometer 30, an oxygen concentration meter 31, which will be described later,
Air flow meter 33, gas flow meter 34, thermometers 36, 38,
Pressure gauges 37, 39, water supply flow meter for spray 40, play
Feed water thermometer 41, coal supply meter 42, low temperature reheat steam pressure gauge
43, dry bulb thermometer 44, wet bulb thermometer 45, coal property setting
The device 46 or the like serves as a detection means for detecting the driving state, and each detection means
As shown in Fig. 2, the detection signal from the soot blower controller
Each is input to the main body 100. In this example, overheating
The operating conditions of the heat exchanger, taking the steam conditions of the heat exchanger 3 and reheater 4 as an example.
The state will be explained.

In the boiler device 1 having such a structure,
By burning the supplied differential coal with the burner 15,
As described above, ash, soot, etc. adhere to and accumulate on the heat transfer surfaces of the furnace water wall unit 12, the superheater 3, the reheater 4, and the economizer 5, which reduces the heat transfer efficiency and operates the boiler. The state becomes unhealthy. The soot blower 27 is arranged corresponding to each heat exchanger in order to blow off the ash and medium adhered as described above, but only the soot blower 27 corresponding to the economizer 5 is shown in FIG. 7 to avoid complication of the drawing. it's shown.

Next, the sootblower controller will be described. 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.

An air quantity meter 33 for measuring the quantity of combustion air supplied to the burner 15, a gas flow meter 34 for measuring the quantity of combustion gas supplied to the hopper 25, and a dry bulb thermometer 4
4 and an air condition measuring box 2 incorporating a wet bulb thermometer 45
8 are arranged respectively.

At the outlet side of the water supply pump 6, a water supply flow meter 35
However, on the inlet side of the spray 23, the water supply flow meter 4 for spraying
0 and the feed water thermometer 41 for spraying, the low temperature reheat steam pipe 19
Low temperature reheat steam pressure gauges 43 for estimating the flow rate are arranged therein.

Further, on the inlet side and the outlet side of each heat exchanger,
Although a thermometer and a pressure gauge are provided to grasp the properties of water and steam, only those related to the economizer 5 are shown in FIG. 7 for simplicity of the drawing. That is, a thermometer 36 and a pressure gauge 37 are arranged on the inlet side of the economizer 5, and a thermometer 38 and a pressure gauge 39 are arranged on the outlet side thereof.

[0026] The outlet side of the Kyusumiki 21 coal feed meter 42 is provided and coal properties setter 46 for further understanding the fuel property of the fine powder coal disposed on the coal supply path.

As shown in FIG. 2, the sootblower control unit main body 100 includes a recirculation gas flow rate adjusting valve 24 and a gas thermometer 3.
0, oxygen concentration meter 31, air flow meter 33, gas flow meter 3
4, feed water flow meter 35, thermometer 36, pressure gauge 37, thermometer 38, pressure gauge 39, spray feed water flow meter 40, spray feed water thermometer 41, coal feed meter 42, low temperature reheat steam pressure gauge 43 The detection signals from the dry-bulb thermometer 44, the wet-bulb thermometer 45, and the like, and the setting signal from the coal property setting device 46 are input.

Next, a schematic structure of the sootblower control unit main body 100 will be described with reference to FIG. A state priority setter 10 2 dirty dirty state calculator 101 of the heat transfer surface, as shown in the figure is a pair, the state of soiling priority calculator 103
The signal is to be input to. Also, the superheater 3,
The steam temperature signal of the reheater 4 is output from the steam temperature detecting means.
Is adapted to be input to the steam condition priority setter 104 and steam conditions priority calculator 105.

[0029] The dirty state priority calculator 10 3 has a function for calculating a start priority of sootblowers is judged in terms of the state of soiling of the heat transfer surface. On the other hand, steam condition priority calculator 105, superheater 3, reheater 4 steam conditions or al Heat
It has the function of determining the operating status of the exchanger and calculating the start priority of the sootblower.

Further, a combined state priority calculator 106 for performing a minimum type multi-valued logical operation by signal input to the dirt condition priority calculator 103 and the steam condition priority calculator 105.
And a soot blower start point determination calculator 107 that determines the start point of the soot blower based on signals from the calculator 106 and the dirt state calculator 101.

The drive signal from the sootblower control unit main body 100 (the sootblower activation point determining arithmetic unit 107) is input to the sootblower driving device 29, and the sootblower 27 selected by the drive signal is activated.

The fouling state calculator 101 transfers the fouling water of the furnace water wall 12, the superheater 3, the reheater 4, and the economizer 5 on the basis of signals from the detectors for monitoring the fouling state of the heat transfer surface. Calculate the hot surface contamination status.

The calculation formula for calculating the heat transfer surface fouling state is as follows: Kf = Uc / Us (1) where Kf; fouling state index Uc; current heat transmission coefficient Us; reference state heat transmission coefficient Further, Uc is It is calculated by the following formula.

Uc = A · Δt / Q (2) Here, A: heat transfer area of the heat exchanger Q: endothermic amount Δt; logarithmic average temperature difference The heat transfer area A is obtained from design data.

The heat absorption amount Q is obtained by F × H (Tsi, Psi) + Q = H (Tso, Pso) × F (3)

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

The logarithmic mean temperature difference Δt is in the case of countercurrent,

[0038]

[Equation 4]

Where Tg is the gas temperature, suffixes i and o are on the inlet side,
The exit side is shown.

The water / steam temperatures Tsi and Tso are thermometers arranged at the inlet and outlet of each heat exchanger, and are measured by the thermometers 36 and 38 in the economizer 5.

The gas temperatures Tgi and Tgo are calculated by the following formulas.

Tgi = Tgo + (Q / Wg · Cpg) (5) Here, Cpg; gas specific heat (constant) Wg; gas flow rate measured value by the gas thermometer 30 is the outlet gas temperature T of the economizer 5.
Let go, the inlet gas temperature Tgi of the economizer 5 is calculated from the heat absorption amount Q of the economizer 5 and the gas flow rate Wg obtained by the equation (3). Similarly, using the inlet gas temperature Tgi of the economizer 5 as the outlet gas temperature of the reheater 4, the inlet gas temperature of the reheater 4 is calculated, and finally the inlet gas temperature of the superheater 3, that is, the furnace outlet 22. The gas temperature of can be estimated.

The gas flow rate Wg is determined by the recirculated gas amount by the gas flow meter 34, the combustion air amount by the air flow meter 33, the air property data by the dry bulb thermometer 44 and the wet bulb thermometer 45, and the coal feeding meter 42. It is calculated based on the supplied coal amount and a signal from the coal property setting device 46. The specific method of measuring the gas flow rate is described in detail in the Japanese Industrial Standards "Heat accounting method for land boilers" (JISB 8222), and the description thereof is omitted here.

Us in the equation (1) is obtained by the following equation.

Ds = f (Tg, Ts, Vg, Vs) where: Vg: Gas flow rate Vs: Water, steam flow rate In the dirty state priority setting device 102, each heat exchanger 1
Numerical values between 0 and 1 can be calculated and set according to the degree of contamination of the heat transfer surfaces of 2, 3, 4, and 5. The dirty state priority means sootblower start priority of the heat exchanger to the other heat exchanger.

The relationship between the fouling state priority and the fouling state index in each heat exchanger will be described with reference to FIG. The figure (a) is a characteristic diagram of the furnace water wall 12, the figure (b) is a characteristic diagram of the superheater 3, the figure (c) is a characteristic diagram of the reheater 4, and the figure (d) is economizing. It is a characteristic view of the container 5.

The inclination angle (gradient) and the upper and lower limit values of the characteristic line in this figure differ depending on the heat exchanger and the operating state, and are set by simulation and the experience of the operator.

In the dirty state priority calculator 103, the signal from the dirty state calculator 101 and the dirty state priority setter 1 are used.
02, the dirt state priority is calculated.

In the steam condition priority setting device 104, the superheater 3
It has a function of calculating a value from 0 to 1 in accordance with the outlet steam temperature of 1 and the upper and lower limit allowable values of the outlet steam temperature of the reheater 4.

That is, the temperature of the main steam decreases as the amount of heat absorbed by the superheater 3 decreases, and rises as the amount of heat absorbed by the water wall 12 of the furnace decreases. On the other hand, the reheated steam temperature decreases due to the decrease in the heat absorption amount of the reheater 4, and rises due to the decrease in the heat absorption amount of the furnace water wall portion 12 and the superheater 3.

The relationship between the main steam temperature, the reheat steam temperature and the soot blower starting priority will be described with reference to FIG. In this figure, the vertical axis is the soot blower start priority according to steam conditions,
The horizontal axis shows the steam temperature.

As shown in FIG. 4A, when the main steam temperature is higher than the reference value (500 ° C.), the water wall portion 1 of the furnace is
The soot blower startup priority by the steam condition in 2 becomes large.

On the other hand, as shown in FIG. 6B, when the main steam temperature is lower than the reference value (500 ° C.), the soot blower starting priority due to the steam condition in the superheater 3 becomes high.

As shown in FIG. 7C, when the reheater steam temperature is higher than the reference value (520 ° C.), the soot blower start priority is given to the steam condition in the furnace water wall 12 or the superheater 3. The degree becomes great.

[0055] As shown in FIG. 2 (d), when the reheater steam temperature is greater than the reference value (520 ° C.), the reheater 4
Soot blower startup priority is high due to the steam conditions in.

It is related to the characteristics of the fouling state index of the water wall of the furnace and the fouling state priority.

The inclination angles and upper and lower limit allowable values of the lines in FIGS. 4A to 4D are determined by design data and simulation.

In the steam condition priority calculator 105, the main steam temperature and the reheat steam temperature, which are signals from outside the control device,
The function of the steam condition priority calculator 105 calculates the steam condition priority Xj.

The furnace water wall 12 is shown in FIG.
(C) and the superheater 3 have two types of priorities as shown in FIGS. 4 (b) and 4 (c), so that the larger value is the steam condition priority of the heat exchanger.

In response to signals from the fouling state priority calculator 103 and the steam condition priority calculator 105, the combined state priority calculator 106 indicates the fouling condition priority and the steam condition priority for each heat exchanger j. Compare and select the smaller priority. This state is shown in FIG.

FIG. 5 is a diagram showing an example of the calculation result by the combined state priority calculator 106, in which the mark .circle-solid. Indicates the priority relating to the stain state output from the stain state priority calculator 103, and .largecircle. The marks indicate the priorities relating to the steam conditions output from the steam condition priority calculator 105, respectively, and 201 in the ● mark indicates the fouling condition priority of the furnace, and 202 in the ○ mark.
Indicates the furnace outlet gas temperature priority, and both are related to the water wall of the furnace, and are shown on the same line as the item.

The mark 203 indicates the priority of the state of the overheater dirt, and ○
The spray flow rate priority of 204 is shown on the same line as the item because both are related to the superheater.

Numeral 205 indicates the reheater dirty state priority, and
The symbol 206 indicates the recirculation gas amount ratio priority, which is shown on the same line as the item because both are related to the reheater.

The symbol 207 indicates the degree of priority of the state of dirt of the economizer, and ○
The mark 208 indicates the boiler outlet gas temperature priority, and since both are related to the economizer, they are shown on the same line as the item.

The fouling state priority of the heat transfer surface and the steam 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. 5, the priority marked with * is selected.

The soot blower operating point determining calculator 107 determines the soot blower starting point based on the boiler efficiency signal from the dirty state calculator 101 and the signal from the combined state priority calculator 106.

That is, when the boiler efficiency becomes lower than the preset value, the place where the combined state priority shows the largest value is determined as the soot blower starting place. This is shown in FIG. 6, and as shown in FIG. 5, the comparison result of the combined state priority shows that the furnace outlet gas temperature priority 202, the superheater fouling state priority 203, and the reheater fouling for each heat exchanger. The state priority 205 and the economizer dirty state priority 207 are respectively selected, but the highest priority among these is selected, and in this case, the furnace outlet gas temperature priority 202 is selected.
Then, based on the selection result, the soot blower 27 corresponding to the furnace water wall portion 12 is driven to clean the heat transfer surface.

As described above, one heat exchanger that needs to start the soot blower most is selected from the plurality of heat exchangers to clean the heat transfer surface, and then data is collected from each detector again. Select the sootblower activation point by the same process.

Further, as shown in FIG. 5, a heat exchanger having a lower priority is selected for each heat exchanger in the calculation result of the combined state priority, and soot blowers are selected in descending order of priority among the selected heat exchangers. It is also possible to start up and then collect data from each detector again and select the sootblower start-up point by a similar process.

[0070]

The present invention is configured as described above, and if the fouling state priority is higher than the operating condition priority such as steam condition priority , the heat exchanger operation is unhealthy. Is smaller, the starting priority of the soot blower may be selected to be the smaller operating state priority.

On the other hand, for example, when the operating condition priority such as the steam condition priority is higher than the fouling condition priority, the heat transfer surface is less contaminated, and therefore the uncleanness of the operating condition is caused even when the soot blower is started. It is determined that there is another reason why the operation is unhealthy because of the small degree of elimination, and after all, the dirt state priority having a smaller start priority of the sootblower may be selected.

Therefore, it is possible to provide an efficient soot blower control device without the operating condition of the device becoming unhealthy.

[Brief description of drawings]

FIG. 1 is a block diagram of a sootblower control device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a sootblower control body.

FIG. 3 is a characteristic diagram showing a relationship between a soot blower starting priority and a fouling state index in each heat exchanger.

FIG. 4 is a characteristic diagram showing a relationship between a main steam temperature, a reheat steam temperature and a soot blower starting priority.

FIG. 5 is an explanatory diagram showing an example of a calculation result by a combined state priority calculator.

FIG. 6 is an explanatory diagram showing an example of a calculation result by a calculator by a soot blower starting point determination calculator.

FIG. 7 is a schematic configuration diagram of a boiler device including a soot blower control device according to an embodiment.

[Explanation of symbols]

 1 Boiler device 3 Superheater 4 Reheater 5 Coal saver 27 Soot blower 30 Gas thermometer 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 Spray 41 Spray feed water thermometer 42 Coal supply amount meter 43 Low-temperature reheat steam pressure gauge 44 Dry-bulb thermometer 45 Ball thermometer 46 Coal property setter 100 Sootblower control unit 101 Fouling state calculator 102 Fouling state priority setting device 103 Dirty state priority calculator 104 Steam condition priority setter 105 Steam condition priority calculator 106 Combined state priority calculator 107 Sootblower start point determination calculator 201 Furnace fouling condition priority 202 Furnace outlet gas temperature priority 203 Overheated dirt State priority 204 Spray flow rate ratio priority 205 Reheater dirt state priority 2 6 recirculated gas amount ratio priority 207 economizer fouling condition priority 208 boiler outlet gas temperature priority

Claims (3)

[Claims] 1. A fouling state detecting means for detecting a fouling state of a heat transfer surface of a heat exchanger, an operating state detecting means for detecting an operating state of the heat exchanger, and a fouling state detecting means. The soot blower start-up priority of the heat exchanger is determined according to the dirty state of the heat transfer surface, and the soot blower of the heat exchanger is determined according to the operating state detected by the operating state detecting means. The operating state priority calculating means for determining the startup priority, and the priority output from the dirty state priority calculating means and the priority output from the operating state priority calculating means are compared, and the priority of both is calculated. A soot blower control device comprising: a priority determining means for selecting a lower one. 2. The heat exchanger according to claim 1, wherein a plurality of the heat exchangers are provided, and the fouling state detecting means, the operating state detecting means, the fouling state priority calculating means, the operating state priority calculating means and the priority determining means. Therefore, the soot blower control device is configured such that the soot blower starting priority for each heat exchanger is determined, and the soot blower is started in order from the higher one of the soot blower starting priorities. 3. The method according to claim 1 or 2,
The soot blower control device, wherein the heat exchanger is a heat exchanger of a boiler device.