CN115507379A - Air quantity control method for gas boiler - Google Patents

Abstract

The invention provides a method for controlling the air volume of a gas boiler, which comprises the following steps: step S100, calculating an oxygen set value according to the boiler load; step S200, comparing the set value of the oxygen amount with the obtained measured value of the oxygen amount through an oxygen amount regulator to obtain a deviation value of the oxygen amount; step S300, calculating an air volume preset value according to the load of the boiler; step S400, calculating according to the oxygen amount deviation value and the air volume preset value to obtain an air volume set value; step S500, comparing the air volume set value with the obtained air volume measured value through an air volume regulator to obtain an air volume deviation value; and step S600, controlling the air volume of the blower according to the air volume deviation value. According to the invention, the influence of oxygen amount change on the preset air volume value is fully considered, and the oxygen amount deviation value is used as the correction of the preset air volume value in air volume adjustment to obtain the set air volume value, so that the accuracy of air volume control is improved.

Description

Air quantity control method for gas boiler

Technical Field

The invention relates to the technical field of gas boilers, in particular to a method for controlling air quantity of a gas boiler.

Background

The gas boiler is widely applied to self-contained power plants such as steel mills, coal chemical plants and the like, and can realize clean and efficient utilization of energy by utilizing fuels such as byproduct blast furnace gas, converter gas, coke oven gas, semi coke tail gas and the like to generate electricity. Steel mills and coal chemical plants often produce more than a single byproduct according to different production processes, and gas boilers have good fuel adaptability and generally have several fuel working conditions. These air supply amounts are different depending on the composition of the fuel and the variation in the flow rate of the fuel.

Currently, a method for controlling air volume of a gas boiler generally compares an air volume preset value calculated according to a load of the boiler with an air volume measured value directly to obtain an air volume deviation value, and controls the air volume according to the air volume deviation value. However, the method for controlling the air volume of the gas boiler does not fully consider the influence of the oxygen change on the preset air volume value, so that the obtained deviation value of the air volume is inaccurate.

Therefore, it is necessary to improve the existing air volume control method of the gas boiler to improve the accuracy of air volume control.

Disclosure of Invention

The invention aims to provide a method for controlling the air volume of a gas boiler, which aims to solve the problem of low accuracy of the existing method for controlling the air volume of the gas boiler.

In order to solve the technical problem, the invention provides a method for controlling the air volume of a gas boiler, which comprises the following steps: step S100, calculating an oxygen set value according to the boiler load; step S200, comparing the oxygen set value with the obtained oxygen measured value through an oxygen regulator to obtain an oxygen deviation value; step S300, calculating an air volume preset value according to the load of the boiler; step S400, calculating according to the oxygen amount deviation value and the air volume preset value to obtain an air volume set value; step S500, comparing the air volume set value with the obtained air volume measured value through an air volume regulator to obtain an air volume deviation value; and step S600, controlling the air volume of the blower according to the air volume deviation value.

Alternatively, in step S200, the measured oxygen amount value is an average value of the effective oxygen amount values obtained at a plurality of measurement points.

Optionally, in step S200, when the oxygen amount set value is compared with the obtained oxygen amount measured value, if the oxygen amount measured value is smaller than the oxygen amount set value, the output air volume deviation value is a positive number, and if the oxygen amount measured value is greater than the oxygen amount set value, the output air volume deviation value is a negative number.

Optionally, in step S400, a set air volume value is obtained by summing the deviation value of the air volume and the preset air volume value, where if the deviation value of the air volume is a negative number, the preset air volume value is smaller than the set air volume value, and if the deviation value of the air volume is a positive number, the preset air volume value is larger than the set air volume value.

Optionally, in step S500, the air volume setting value and the obtained air volume measured value are compared by the air volume regulator to obtain an air volume deviation value, the air volume setting value is subtracted from the air volume measured value, when the air volume deviation value is a positive number, the air volume is decreased, and when the air volume deviation value is a negative number, the air volume is increased.

Optionally, step S600 further includes calculating a real-time air supply amount, wherein when the air supply amount is greater than a preset value, the supplementary blower is controlled to be turned off, and when the air supply amount is less than the preset value, the supplementary blower is controlled to be turned on, and meanwhile, the power of the air supply blower is adjusted.

Optionally, a step S800 is further included between step S500 and step S600, and the air volume deviation value of the main control feed forward of the boiler is summed to obtain a corrected air volume deviation value.

Optionally, the method further includes a fuel fluctuation control method for adjusting the main control feed-forward of the boiler, where the fuel fluctuation control method includes: the method comprises the steps that a monitoring position and a regulating position are arranged on a main gas pipeline of a boiler, a plurality of pressure monitoring units are sequentially arranged at the monitoring position along the gas flowing direction, and the regulating position is located at the downstream of the monitoring position and is provided with a main flow regulating valve; the coal gas pressure is monitored by each pressure monitoring unit at the monitoring position, and the variation delta Q of the coal gas heat supply amount caused by the coal gas fluctuation is calculated and obtained based on the monitored coal gas pressure fluctuation _{Gas (coal gas)} (ii) a Calculating the time t1 required by the coal gas to run from the monitoring position to the adjusting position; if Δ Q _{Gas (es)} When the flow rate is more than 0, after the time t1, the opening degree of the main flow regulating valve is reduced so as to improve the stability of main steam parameters of the gas boiler; if Δ Q _{Gas (es)} If the value is less than 0, after time t1, the opening degree of the main flow regulating valve is increased so as to improve the stability of main steam parameters of the gas boiler; if Δ Q _{Gas (es)} And =0, the opening of the main flow regulating valve is kept unchanged.

Optionally, the method further includes: when the main flow regulating valve is regulated to the maximum opening and still cannot reach the control target, the main feed water flow of the boiler is further regulated to reach the control target.

Optionally, the adjustment amount of the main feed water flow of the boiler is calculated according to the following formula:

wherein eta is the thermal efficiency of the boiler, h _out Specific enthalpy value, h, after heat exchange for water supply _in The enthalpy value is the specific enthalpy value before the heat exchange of the feed water.

The invention provides a method for controlling the air quantity of a gas boiler, which has the following beneficial effects:

the air supply device comprises a supplementary air duct, a supplementary fan, an air preheater, a hearth, a blower and a fan, wherein one end of the supplementary air duct is communicated with the atmosphere, the other end of the supplementary air duct is communicated with the front air duct of the air preheater, the supplementary fan is arranged on the supplementary air duct, one end of the front air duct of the air preheater is communicated with the atmosphere, and the other end of the front air duct of the air preheater is communicated with the air inlet of the air preheater.

Secondly, the influence of oxygen amount change on the air volume preset value is fully considered, and the oxygen amount deviation value is used as correction of the air volume preset value in air volume adjustment to obtain an air volume set value, so that the accuracy of air volume control is improved.

And thirdly, the influence of the main control feed forward of the boiler on the air volume deviation value is fully considered, and the main control feed forward of the boiler sums the air volume deviation value to obtain a corrected air volume deviation value, so that the accuracy of air volume control is improved.

Secondly, the invention sets a monitoring bit at the upstream of the boiler burner, when the coal gas fluctuation occurs in the operation process of the boiler, the opening of the flow regulating valve can be regulated in advance according to the fluctuation of the heat supply value corresponding to the coal gas fluctuation monitored by the monitoring bit, thereby maintaining the stability of the heat released by the coal gas combustion in unit time and further improving the stability of the main steam parameter of the coal gas boiler.

Drawings

FIG. 1 is a schematic structural diagram of an air supply and flue gas temperature regulating system of a gas boiler in an embodiment of the invention;

FIG. 2 is a control flow chart of a method for controlling the air volume of a gas boiler in the embodiment of the invention;

fig. 3 is a schematic diagram of a gas pipeline of the fuel fluctuation control system according to an embodiment of the present invention.

101-air preheater front air duct; 102-an air preheater; 103-air preheater rear air duct; 104-heat exchanger front flue; 105-supplementary air ducts; 106-make-up fan; 107-a blower; 108-air supply branch pipes; 109-flue gas heat exchanger; 110-heat exchanger rear flue; 111-heat exchanger front gas pipe; 112-heat exchanger rear gas tube; 113-a desulfurizing tower; 114-blower inlet silencer; 115-blower inlet damper; 116-blower outlet flapper door; 117-make-up fan inlet silencer; 118-make-up fan inlet damper; 119-supplementary fan outlet damper; 120-supplementary duct isolation door; 121-supplement branch pipe isolation door;

200-a main gas pipeline; 210-monitoring bits; 211-a pressure monitoring unit; 212-heat value instrument; 220-main flow regulating valve; 300-boiler burner; 400-gas storage bypass; 410-an external source gas source; 420-a bypass regulating valve; 430-quick-cut valve 430; 500-gas branch pipes; 510-branch flow regulating valve; 520-a pressure monitoring device; 530-a shut-off valve; 230-electric blind plate valves; 240-hydraulic quick-cut valve.

Detailed Description

The air supply and smoke temperature adjusting system of the gas boiler provided by the invention is further explained in detail by combining the attached drawings and the specific embodiment. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

The first embodiment,

Referring to fig. 1, fig. 1 is a schematic structural diagram of an air supply and flue gas temperature adjusting system of a gas boiler in an embodiment of the present invention, and the embodiment provides an air supply and flue gas temperature adjusting system of a gas boiler, including: the air preheater comprises an air preheater front air channel 101 with one end communicated with the atmosphere, an air inlet, an air preheater 102 connected with the other end of the air preheater front air channel 101, an air preheater rear air channel 103 with one end communicated with an air outlet of the air preheater 102 and the other end communicated with a hearth, a heat exchanger front flue 104 with one end communicated with a flue gas outlet of the air preheater 102, a supplementary air channel 105 with one end communicated with the atmosphere and the other end communicated with the air preheater front air channel 101, a supplementary fan 106 arranged on the supplementary air channel 105, and a blower 107 arranged on the air preheater front air channel 101.

The air supply device comprises a supplementary air duct 105, one end of the supplementary air duct 105 is communicated with the atmosphere, the other end of the supplementary air duct 105 is communicated with the air pre-heater front air duct 101, a supplementary fan 106 is arranged on the supplementary air duct 105, one end of the air pre-heater front air duct 101 is communicated with the atmosphere, and the other end of the air pre-heater front air duct 101 is communicated with an air inlet of an air pre-heater 102.

Referring to fig. 1, the air supply and flue gas temperature adjustment system of the gas boiler further includes an air supply branch pipe 108 having one end communicating with the air supply duct and the other end communicating with the air preheater rear air duct 103. Can with on the one hand through setting up air supply branch pipe 108 wind channel 101 before the air heater with wind channel 103 intercommunication behind the air heater for the partial amount of wind that the air feeder 107 sent into wind channel 101 before the air heater can be followed wind channel 103 gets into in the furnace behind the air heater, also can make the amount of wind that the air supply machine supplyed can directly get into from air supply branch pipe 108 wind channel 103 behind the air heater reentrant in the furnace, so can provide different amount of wind for different operating modes, and the temperature of the adjustable flue gas that passes through air heater 102, the temperature of flue gas in avoiding getting into heat exchanger front flue 104 is too high or low excessively.

Referring to fig. 1, the air supply and smoke temperature adjusting system of the gas boiler further includes a flue gas-gas heat exchanger 109, and a heat exchanger rear flue 110 having one end communicated with a flue gas outlet of the flue gas-gas heat exchanger 109 and the other end communicated with the chimney, and the other end of the heat exchanger front flue 104 is communicated with a flue gas inlet of the flue gas-gas heat exchanger 109.

Referring to fig. 1, the air supply and flue gas temperature adjustment system of the gas boiler further includes a heat exchanger front gas pipe 111 having one end communicated with the gas inlet of the flue gas-gas heat exchanger 109 and the other end communicated with the gas pipe network, and a heat exchanger rear gas pipe 112 having one end communicated with the gas outlet of the flue gas-gas heat exchanger 109 and the other end communicated with the burner of the boiler.

Referring to fig. 1, the air supply and flue gas temperature regulation system of the gas boiler further comprises a desulfurizing tower 113, and the desulfurizing tower 113 is arranged on the heat exchanger rear flue 110.

Referring to fig. 1, the number of the air pre-heater front air passage 101 and the air pre-heater rear air passage 103 is two, and the number of the supplementary air passage 105 and the supplementary air branch 108 is one.

Referring to fig. 1, the air supply and smoke temperature adjusting system of the gas boiler further includes a blower inlet silencer 114, and the blower inlet silencer 114 is disposed on the air preheater front air duct 101 and between the atmosphere and the blower 107.

Referring to fig. 1, the gas boiler supply air and flue gas temperature regulating system further includes a blower inlet damper 115, wherein the blower inlet damper 115 is disposed on the air preheater front air duct 101 and located between the blower inlet silencer 114 and the blower 107, and is used for regulating the air volume entering the blower 107.

Referring to fig. 1, the air supply and temperature regulation system of the gas boiler further includes a blower outlet damper 116, and the blower outlet damper 116 is disposed on the air preheater front air duct 101 between the blower 107 and the air preheater for controlling the circulation and closing of the air preheater front air duct 101.

Referring to fig. 1, the air supply and flue gas temperature regulation system of the gas boiler further comprises a supplementary blower inlet silencer 117, and the supplementary blower inlet silencer 117 is disposed on the supplementary air duct 105 and between the atmosphere and the supplementary blower 106.

Referring to fig. 1, the system for adjusting supply air and smoke temperature of a gas boiler further comprises a supplementary blower inlet damper 118, wherein the supplementary blower inlet damper 118 is disposed on the supplementary air duct 105 and between the silencer and the supplementary blower 106, and is used for adjusting the air volume entering the supplementary blower 106.

Referring to fig. 1, the system for adjusting supply air and smoke temperature of a gas boiler further comprises a supplementary blower outlet damper 119, wherein the supplementary blower outlet damper 119 is disposed on the supplementary air duct 105 and between the air preheater 102 and the supplementary blower 106, and is used for controlling the circulation and closing of the supplementary air duct 105.

Referring to fig. 1, the system for adjusting supply air and smoke temperature of a gas boiler further includes a supplementary air duct isolation door 120 disposed on the supplementary air duct 105 and between the air supply branch 108 and the air preheater 102.

Referring to fig. 1, the air supply and flue gas temperature adjusting system for a gas boiler further comprises an air supply branch pipe 108 isolation door 121 arranged on the air supply branch pipe 108.

The air supply and smoke temperature regulating system of the gas boiler further comprises an air volume controller, wherein the air volume controller is used for controlling the opening and closing of the air supply fan 107, the air supply fan outlet baffle door 116, the supplementary air fan 106 and the supplementary fan outlet baffle door 119 according to the fuel working condition of the boiler, and controlling the opening and closing of the supplementary air duct isolation door 120 and the supplementary air branch pipe 108 isolation door 121 according to the smoke temperature of the boiler.

When the air supply quantity required by the combustion of the boiler fuel is not large, the supplementary fan 106, the supplementary fan outlet baffle door 119, the supplementary air duct isolation door 120 and the supplementary air branch pipe 108 isolation door 121 can be closed, and cold air enters the air preheater 102 from the air preheater front air duct 101, then enters the air preheater rear air duct 103 and then flows out of the boiler furnace. At the moment, if the exhaust gas temperature of the boiler is low, the supplementary air duct isolation door 120 and the supplementary air branch 108 isolation door 121 are opened, part of cold air enters the air duct 101 in front of the air preheater from one end of the air duct 101 in front of the air preheater, then enters the supplementary air duct 105 from the air duct 101 in front of the air preheater, then enters the supplementary air branch 108, then enters the air duct 103 behind the air preheater from the supplementary air branch 108 and flows out to the boiler furnace, and part of cold air enters the air preheater 102 from the air duct 101 in front of the air preheater and then enters the air duct 103 behind the air preheater and then flows out to the boiler furnace. Therefore, the over-low temperature of the flue gas in the heat exchanger front flue 104 and the heat exchanger rear flue 110 can be avoided, so that the sulfur dioxide generated by combustion is easy to corrode the heat exchanger rear flue 110 at low temperature and influence the desulfurization effect of the desulfurization tower 113.

When the air supply quantity required by the combustion of the boiler fuel is large, the supplementary fan 106, the supplementary fan outlet baffle door 119 and the supplementary air duct isolation door 120 are opened, the supplementary air branch pipe 108 isolation door 121 is closed, and cold air enters the air preheater 102 from the air preheater front air duct 101 and the supplementary air duct 105, then enters the air preheater rear air duct 103, and then flows out to the boiler furnace. At this time, if the exhaust gas temperature of the boiler is low, the supplementary air duct isolation door 120 is closed, the supplementary air branch 108 isolation door 121 is opened, a part of cold air enters the air preheater rear air duct 103 from the supplementary air duct 105 through the supplementary air branch 108 and then enters the furnace, a part of cold air enters the air preheater 102 from the air preheater front air duct 101, enters the air preheater rear air duct 103 from the air preheater 102, and then flows out to the boiler furnace.

The flue gas may flow from the boiler furnace through the air preheater 102 into the heat exchanger front flue 104, then into the flue gas heat exchanger 109, then into the heat exchanger back flue 110, and finally into the chimney.

The gas can flow into the front gas pipe 111 of the heat exchanger from the gas pipe network, then flow into the flue gas heat exchanger 109, then flow into the rear gas pipe 112 of the heat exchanger, and then flow into the boiler furnace.

Wherein the cold air and the flue gas may be heat exchanged at the air preheater 102 to cool the flue gas for a first time, and the gas and the flue gas may be heat exchanged at the flue gas heat exchanger 109 to cool the flue gas for a second time.

When the boiler is operated in a low-load state (around 60% of the maximum continuous evaporation capacity of the boiler), the air supply quantity required by the combustion of the fuel of the boiler is not large and the temperature of the smoke exhausted from the boiler is relatively low, the supplementary fan 106 and the supplementary fan outlet baffle door 119 are closed, and the supplementary air duct isolation door 120 on the supplementary air duct 105 and the supplementary air branch pipe 108 isolation door 121 on the supplementary air branch pipe 108 are opened. Cold air enters the front air channel 101 of the air preheater from one end of the front air channel 101 of the air preheater, and part of the cold air enters the air preheater 102 from the other end of the front air channel 101 of the air preheater, then flows into the rear air channel 103 of the air preheater, and then flows into a boiler furnace; part of cold air enters the hearth from one end of the supplementary air duct 105 through the supplementary air duct 105, the supplementary air branch 108 and the air preheater rear air duct 103 in sequence. Because part of the cold air does not pass through the air preheater 102, the amount of the cold air exchanging heat with the flue gas at the air preheater 102 can be reduced, so that the temperature of the flue gas passing through the air preheater 102 and the gas heat exchanger can be maintained at about 140 ℃, the reaction temperature required by the dry desulfurization of the sodium bicarbonate in the desulfurizing tower 113 is met, and the problem that the temperature of the flue gas passing through the gas heat exchanger is higher than the dew point temperature, low-temperature corrosion is formed, and the service life of the flue gas-gas heat exchanger 109 is influenced is avoided.

When the boiler is operated under a high load (near the maximum continuous evaporation capacity of the 100 percent boiler), if the air supply quantity required by the combustion of the boiler fuel is not large, the exhaust temperature of the boiler is higher, and the supplementary fan 106, the supplementary fan outlet baffle door 119, the supplementary air duct isolation door 120 on the supplementary air duct 105 and the supplementary air branch duct 108 isolation door 121 on the supplementary air branch duct 108 can be closed. Cold air enters the air pre-heater front air channel 101 from one end of the air pre-heater front air channel 101, and all enters the air pre-heater 102 from the other end of the air pre-heater front air channel 101, flows through the air pre-heater 102, then flows into the air pre-heater rear air channel 103, and then flows into a boiler furnace. Because all the air entering the boiler furnace needs to exchange heat with the flue gas flowing through the air preheater 102, the temperature of the flue gas can be reduced to a greater extent, and the boiler efficiency is improved. When the air supply quantity required by the combustion of the boiler fuel is large, the boiler exhaust gas temperature is high, the supplementary fan 106, the supplementary fan outlet baffle door 119 and the supplementary air duct isolation door 120 on the supplementary air duct 105 can be opened, the supplementary air branch 108 isolation door 121 on the supplementary air branch 108 is closed, cold air enters the air preheater front air duct 101 from one end of the air preheater front air duct 101 and the supplementary air duct 105, and all cold air enters the air preheater 102 from the other end of the air preheater front air duct 101, flows through the air preheater 102, then flows into the air preheater rear air duct 103, and then flows into the boiler furnace. Because all the air entering the boiler furnace needs to exchange heat with the flue gas flowing through the air preheater 102, the temperature of the flue gas can be reduced to a greater extent, and the boiler efficiency is improved.

When the boiler operates in a low temperature environment, for example, in a northern winter environment, the temperature of the gas entering the flue gas heat exchanger 109 from the gas pipe in front of the flue gas heat exchanger 109 is low, which results in a low temperature of the flue gas entering the rear flue 110 of the heat exchanger after passing through the flue gas heat exchanger 109, and at this time, if the air supply volume required by the combustion of the boiler fuel is not large, the supplementary air duct isolation door 106 and the supplementary air duct isolation door 120 on the supplementary air duct 105 and the supplementary air branch duct 108 isolation door 121 on the supplementary air branch duct 108 are opened. Cold air enters the front air channel 101 of the air preheater from one end of the front air channel 101 of the air preheater, and part of the cold air enters the air preheater 102 from the other end of the front air channel 101 of the air preheater, then flows into the rear air channel 103 of the air preheater, and then flows into a boiler furnace; part of cold air enters the hearth from one end of the supplementary air duct 105 through the supplementary air duct 105, the supplementary air branch 108 and the air preheater rear air duct 103 in sequence. Since part of the cool air does not pass through the air preheater 102, the amount of cool air exchanging heat with the flue gas at the air preheater 102 can be reduced, so that the flue gas passing through the air preheater 102 and the gas heat exchanger can be maintained at a higher temperature.

Example II,

Referring to fig. 2, fig. 2 is a control flowchart of a method for controlling air volume of a gas boiler in an embodiment of the present invention, and the embodiment provides a method for controlling air volume of a gas boiler, including:

step S100, calculating an oxygen set value according to the boiler load;

step S200, comparing the set value of the oxygen amount with the obtained measured value of the oxygen amount through an oxygen amount regulator to obtain a deviation value of the oxygen amount;

step S300, calculating an air volume preset value according to the load of the boiler;

step S400, calculating according to the oxygen amount deviation value and the air volume preset value to obtain an air volume set value;

step S500, comparing the air volume set value with the obtained air volume measured value through an air volume regulator to obtain an air volume deviation value;

and step S600, controlling the air volume of the blower according to the air volume deviation value.

In step S100 and step S300, the boiler load is the amount of steam generated per unit time. For example, boiler steam is used to drive a steam turbine, which is used to do work externally. When the boiler does work, the more the work is done in unit time, the larger the load of the boiler is, otherwise, the smaller the load of the boiler is.

In step S200, the measured value of oxygen amount is an average value of the effective oxygen amount values obtained at the plurality of measurement points. For example, if there are five measurement points, and the oxygen amount value measured by one measurement point is obviously wrong, the oxygen amount value measured by the measurement point is deleted, and the oxygen amount values measured by the other four measurement points are averaged to obtain the oxygen amount measurement value.

In step S200, when the oxygen amount set value is compared with the obtained oxygen amount measured value, if the oxygen amount measured value is smaller than the oxygen amount set value, the output air volume deviation value is a positive number, and if the oxygen amount measured value is larger than the oxygen amount set value, the output air volume deviation value is a negative number.

Step S700 is further included between step S100 and step S200 to manually modify the oxygen level set point. The accuracy of the control of the air volume of the blower can be further improved by manually correcting the oxygen volume set value.

In step S400, a preset air volume value is obtained by summing the deviation value of the air volume and the preset air volume value, wherein if the deviation value of the air volume is negative, the preset air volume value is smaller than the preset air volume value, and if the deviation value of the air volume is positive, the preset air volume value is larger than the preset air volume value.

In step S500, the air volume setting value is subtracted from the air volume measurement value by comparing the air volume setting value with the obtained air volume measurement value by the air volume adjuster to obtain an air volume deviation value, and when the air volume deviation value is a positive number, the air volume is decreased, and when the air volume deviation value is a negative number, the air volume is increased.

In step S600, the control air volume is decreased when the air volume deviation value is positive, and is increased when the air volume deviation value is negative.

Step S600 also comprises calculating real-time air supply quantity, wherein when the air supply quantity is greater than a preset value, the supplementary fan is controlled to be closed, and when the air supply quantity is less than the preset value, the supplementary fan is controlled to be opened, and meanwhile, the power of the air feeder is adjusted.

Step S800 is further included between step S500 and step S600, and the air volume deviation value of the boiler main control feed-forward is summed to obtain a corrected air volume deviation value. Wherein, the boiler main control feedforward is a feedforward air quantity value obtained by calculating according to coal gas fluctuation. When the feed air volume value is increased, the larger the air volume deviation value is, the larger the required air volume is, and when the feed air volume value is reduced, the smaller the air volume deviation value is, the smaller the required air volume is. That is, the coal gas fluctuation affects the magnitude of the deviation value of the air volume in real time, so if the air volume is to be accurately controlled in real time, the control of the coal gas fluctuation is also critical.

Example III,

In this embodiment, the smaller the coal gas fluctuation is, the more advantageous the air volume control is, and based on this, this embodiment provides a fuel fluctuation control method, which is:

a monitoring position 210 and a regulating position are arranged on a main gas pipeline 200 of the boiler, a plurality of pressure monitoring units 211 are sequentially arranged at the monitoring position 210 along the gas circulation direction, and the regulating position is positioned at the downstream of the monitoring position 210 and is provided with a main flow regulating valve 220;

the gas pressure is monitored by monitoring the pressure monitoring units 211 at the site 210, and the variation quantity delta Q of the gas heat supply quantity caused by the gas fluctuation is calculated based on the monitored gas pressure fluctuation _{Gas (coal gas)} (ii) a Calculating the time t1 required for the gas to run from the monitoring site 210 to the regulating site;

if Δ Q _{Gas (coal gas)} If the time is more than 0, after t1, the opening degree of the main flow regulating valve 220 is reduced so as to improve the stability of main steam parameters of the gas boiler;

if Δ Q _{Gas (es)} Less than 0, and after time t1, the opening degree of the main flow regulating valve 220 is increased so as to improve the main flow of the gas boilerSteam parameter stability;

if Δ Q _{Gas (es)} =0, and the opening degree of the main flow rate adjustment valve 220 is kept unchanged.

The monitoring position 210 is a section, i.e. has a certain axial length of the pipeline, for example, a monitoring section of the main gas pipeline 200, which facilitates the arrangement of the monitoring equipment.

The number of the gas pressure measuring points (i.e. the pressure monitoring units 211) is preferably 3 or more than 3, so as to ensure the accuracy and reliability of pressure monitoring. The distance between two adjacent gas pressure measuring points is preferably in the range of 1-20 m, and more preferably controlled in the range of 5-15 m.

In one embodiment, the gas heat supply is calculated using the following formula:

Q _{gas (es)} ＝qm _{Qi (Qi)}

Wherein q is a gas heat value, and real-time monitoring can be carried out by arranging a heat value instrument 212 on a pipeline; m is _{Qi (Qi)} Is the gas flow rate, m _{Qi (Qi)} Can be obtained by monitoring gas pressure conversion.

Correspondingly, a gas calorific value meter 212 is further arranged at the monitoring position 210, the gas calorific value meter 212 can be used for monitoring the gas calorific value on line, and the gas calorific value meter 212 can be arranged on the same cross section of the main gas pipeline 200 opposite to one of the pressure monitoring units 211, can be arranged between two adjacent pressure monitoring units 211, or can be arranged at the downstream of each pressure monitoring unit 211.

In actual operation, the fluctuation of the gas heat value is small, so in the embodiment, the influence of the fluctuation of the gas flow on the operation of the boiler is mainly considered.

The monitoring site 210 is at a certain distance from the regulating site to ensure that corresponding treatment can be performed in advance when the gas fluctuates. In one embodiment, the distance between the monitoring bit 210 and the adjusting bit is greater than 20m, for example, controlled in the range of 20-100 m.

The adjustment location is at a distance from the boiler burner 300, which is also preferably above 20m, for example in the range of 20 to 100 mm.

Further, when the time t1 required for the gas to run from the monitoring position 210 to the adjusting position is calculated, the position of the gas pressure measuring point of the central position or the central position of the monitoring position 210 is used as the initial running position of the gas, and the gas flow rate can be calculated on the basis of the gas pressure monitored at the initial running position and in combination with the pipe diameter and the like.

Further, when calculating Δ Q _{Gas (es)} When the pressure fluctuation of the coal gas is measured, the pressure difference between every two adjacent coal gas pressure measuring points is calculated, and the average value of the pressure differences is taken as the pressure fluctuation of the coal gas. When the pressure difference between every two adjacent gas pressure measuring points is calculated, the monitoring data of the downstream gas pressure measuring point is preferably subtracted by the monitoring data of the upstream gas pressure measuring point. Because the gas fluctuation is generally a creep process rather than a mutation process, the calculation mode can ensure the accuracy and reliability of the monitoring result.

The main flow control valve 220 is an automatic valve, and may be a flow control valve such as an electric butterfly valve.

Further preferably, when the opening degree of the main flow regulating valve 220 is regulated, the regulation aims at: the fluctuation range of the temperature of the middle point of the boiler is controlled within 0-10 ℃, and the effect of improving the stability of the main steam parameters of the gas boiler can be achieved.

In the case where the fluctuation of the gas calorific value is not large, it is preferable that the opening degree of the main flow rate adjustment valve 220 is increased or decreased by 1% to 10% correspondingly for every 1KPa of decrease or increase of the gas pressure.

Further preferably, the control method further includes:

when the main flow regulating valve 220 is regulated to the maximum opening and still cannot reach the control target, the control target is further achieved by regulating the main feed water flow of the boiler. Wherein, after the flow regulating valve is opened to the maximum opening, the main feed water flow of the boiler is further regulated.

When the boiler operates, in order to ensure the stability of main steam parameters, the fuel and the feed water should satisfy the following relations:

Q _{water (I)} ＝ηQ _{Gas (es)}

Wherein, Q water is heat absorbed by water supply heat exchange; eta is the thermal efficiency of the boiler.

Q _{Water (I)} ＝m _{Water (W)} (h _out -h _in )

Wherein m is _{Water (W)} The main feed water flow of the boiler; h is a total of _out Specific enthalpy value, h, after heat exchange for water supply _in The enthalpy value is the specific enthalpy value before the heat exchange of the feed water. For h _out And h _in The table look-up operation of (1) is generally referred to in the current engineering in handbook of water and steam thermal property charts; the parameters of boiler feedwater and main steam are applicable to the water and superheated steam meter in this manual. Specifically, the enthalpy value h of the main boiler feed water ratio can be obtained by inquiring 'water and superheated steam table' according to the temperature and pressure parameters of the main boiler feed water _in (ii) a According to the temperature and pressure parameters of the main steam of the boiler, the enthalpy value h of the main steam ratio of the boiler can be obtained by inquiring' water and a superheated steam table _out 。

Therefore, the formula for calculating the main feed water flow of the boiler is as follows:

although the boiler thermal efficiency η is different under different loads, the boiler thermal efficiency η does not change suddenly because the fluctuation of the gas is generally a continuous process, so that the boiler thermal efficiency η at two adjacent monitoring moments can be approximately considered to be kept unchanged. However, it is preferable to recalculate the boiler thermal efficiency η after each adjustment of the opening degree of the main flow regulating valve 22012, and the specific calculation method is a conventional technique in the art and will not be described herein.

Accordingly, the adjustment amount of the main feed water flow of the boiler is calculated according to the following formula:

wherein eta is the thermal efficiency of the boiler, h _out Specific enthalpy value, h, after heat exchange for water supply _in The enthalpy value is the specific enthalpy value before the heat exchange of the feed water.

The frequency of a frequency converter of the feed pump can be adjusted according to the calculation result to achieve the purpose of adjusting the main feed water flow of the boiler. The regulating quantity of main feed water flow of boiler is equal to delta m _{Water (W)} Obviously, the ideal regulating target is provided, but the regulating quantity of the main feed water flow of the boiler is close to the delta m in consideration of the actual working condition _{Water (W)} It is considered reasonable that the specific difference should satisfy the requirement of ensuring the fluctuation range of the boiler intermediate point temperature to be 0-10 ℃.

Further, the method further comprises:

the time t2 required for the gas to be transmitted from the monitoring position 210 to the boiler burner 300 and the time t3 required for the feed water to be transmitted from the feed water pump to the boiler water wall are obtained,

if t2 is larger than t3, the main feed water flow of the boiler is adjusted in a lagging mode, and the lag time is t2-t3. Or external source gas is supplemented into the gas main pipeline 200 to improve the stability of main steam parameters of the gas boiler, wherein the external source gas supplementing point is positioned at the downstream of the monitoring position 210 and can be positioned at the upstream or downstream of the adjusting position, the time of the external source gas reaching the boiler burner 300 is preferably the same as t3, the external source gas is supplemented when a gas fluctuation signal is monitored, and the ventilation time of the external source gas is t2-t3. The gas main pipe 200 may be connected to a gas storage bypass 400, the gas storage bypass 400 is connected to an external gas source 410, and the gas storage bypass 400 is provided with a bypass control valve 420 and a quick-cut valve 430, so as to control the flow rate of the external gas through the bypass control valve 420.

If t2 is less than t3, before the main feed water flow of the boiler is adjusted in place, the opening degree of the branch pipe flow adjusting valve 510 on the gas branch pipeline 500 on the inlet side of the boiler burner 300 is reduced, so that the stability of the main steam parameters of the gas boiler is improved. Further, after the time t3 is reached, the opening degree of the branch pipe flow regulating valve 510 is reset to the position before the coal gas fluctuates, so that the stability of the subsequent boiler operation is further improved.

Based on the scheme, the time of the coal gas fluctuation reaching the boiler burner 300 and the time of feed water reaching the water-cooled wall of the boiler are fully considered, the reliability of the adjusting operation is ensured, the running stability of the coal gas boiler can be further improved, and the main steam parameters under various working conditions can be controlled within a target range.

The main gas pipe 200 preferably transports steel mill gas, such as blast furnace gas. The main steam parameters are preferably not lower than 22.12Mpa and not lower than 540 ℃, and the supercritical gas boiler can be suitable for supercritical gas generator sets, ultra-supercritical gas generator sets and the like.

Although the fluctuation of the gas can be reduced by the fuel fluctuation control method to reduce the regulation and control of the air volume, the fluctuation of the gas can not be avoided, so that the air volume control method of the gas boiler in the second embodiment needs to be provided to regulate and control the air volumes of the blower and the supplementary fan.

Example four,

The embodiment of the invention provides a fuel fluctuation control system, which comprises a gas main pipeline 200 and a plurality of gas branch pipelines 500 which are connected with various boiler burners 300 in a one-to-one correspondence manner, wherein the gas main pipeline 200 is provided with a monitoring position 210 and an adjusting position, the monitoring position 210 is provided with a gas calorific value instrument 212 and a plurality of pressure monitoring units 211 which are sequentially distributed along the gas flowing direction, and the adjusting position is positioned at the downstream of the monitoring position 210 and is provided with a main flow regulating valve 220.

The pressure monitoring unit 211 may employ a pressure measuring device such as a pressure transmitter.

The monitoring site 210 is at a certain distance from the regulating site to ensure that corresponding treatment can be performed in advance when the gas fluctuates. In one embodiment, the distance between the monitoring bit 210 and the adjusting bit is greater than 20m, for example, controlled in the range of 20-100 m.

The adjustment location is at a distance from the boiler burner 300, which is also preferably above 20m, for example in the range of 20 to 100 m.

The monitoring position 210 is a section, i.e. has a certain axial length of the pipeline, for example, a monitoring section of the main gas pipeline 2001, which facilitates the arrangement of the monitoring equipment.

The number of the gas pressure measuring points (i.e. the pressure monitoring units 211) is preferably 3 or more than 3, so as to ensure the accuracy and reliability of pressure monitoring. The distance between two adjacent gas pressure measuring points is preferably in the range of 1-20 m, and more preferably controlled in the range of 5-15 m.

The gas calorific value meter 212 may be disposed on the same cross section of the main gas pipeline 200 opposite to one of the pressure monitoring units 211, may be disposed between two adjacent pressure monitoring units 211, or may be disposed downstream of each pressure monitoring unit 211.

The main flow control valve 220 is an automatic valve, and may be a flow control valve such as an electric butterfly valve.

Further, the system further comprises a main controller and a comparator, wherein the main controller is used for:

acquiring monitoring data of the gas calorific value instrument 212 and monitoring data of each pressure monitoring unit 211;

sending the monitoring data of each pressure monitoring unit 211 to a comparator for comparison, and obtaining a comparison result of the comparator;

and calculating the variation delta Q of the gas heat supply amount caused by gas fluctuation according to the comparison result _{Gas (es)} And controls the opening degree of the main flow rate adjustment valve 220 according to a predetermined strategy.

Further, the predetermined policy may refer to the related contents in the third embodiment, for example, the predetermined policy includes:

if Δ Q _{Gas (coal gas)} If the time is more than 0, after t1, the opening degree of the main flow regulating valve 220 is reduced so as to improve the stability of main steam parameters of the gas boiler;

if Δ Q _{Gas (es)} If the value is less than 0, after the time t1, the opening degree of the main flow regulating valve 220 is increased so as to improve the stability of main steam parameters of the gas boiler;

if Δ Q _{Gas (es)} =0, and the opening degree of the main flow rate adjustment valve 220 is kept unchanged.

Further, the main controller is also used for adjusting the frequency of a frequency converter of the main water supply pump so as to enable the supplied gas quantity to be matched with the main water supply flow. For related contents, reference may be made to the third embodiment, which is not described herein again.

Further, as shown in fig. 3, fig. 3 is a schematic diagram of a gas pipeline of a fuel fluctuation control system according to an embodiment of the present invention, a branch gas flow rate adjusting valve 510 is disposed on the gas branch pipeline 500, a pressure monitoring device 520 may be further disposed on the gas branch pipeline 500, and both the branch gas flow rate adjusting valve 510 and the pressure monitoring device 520 are electrically connected to a main controller. In addition, the gas branch pipe 500 is further provided with a shut-off valve 530, for example, a hydraulic shut-off valve 530 is adopted, so that the reliability of the system operation can be further improved.

Further, as shown in fig. 3, a gas storage bypass 400 is connected to the main gas pipe 200, the gas storage bypass 400 is connected to an external gas source 410, and a bypass regulating valve 420 and a shut-off valve 530 are disposed on the gas storage bypass 400. The external source gas source 410 may be an external source gas storage tank or the like, and the external source gas may be the same kind of gas as the gas supplied from the main gas pipe 200, for example, both of them are blast furnace gas, and the external source gas storage tank may be fully stored in advance at the initial stage of operation. The bypass point of the gas storage bypass 400 is preferably located downstream of the monitoring bit 210 and may be located upstream or downstream of the regulating bit.

The main controller is further configured to:

acquiring the time t2 required by the coal gas to be transmitted from the monitoring position 210 to the boiler burner 300 and the time t3 required by the feed water to be transmitted from the feed water pump to the boiler water-cooled wall; sending the t2 and the t3 to a comparator for comparison and obtaining a comparison result of the comparator; and executing the set strategy according to the comparison result. The setting policy can refer to the related contents in the third embodiment.

In addition, as shown in fig. 3, preferably, a heat exchanger is further disposed at the tail end of the main gas pipeline 200, and the heat exchanger is preferably a flue gas heat exchanger 109, so that the waste heat of the flue gas discharged from the boiler can be utilized to improve the combustion effect of the gas.

Optionally, as shown in fig. 3, an electric blind valve 230 and a hydraulic quick-cutting valve 240 are further disposed on the main gas pipe 200, so that the reliability of the system operation can be further improved.

The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.

Claims (10)

1. A method for controlling the air volume of a gas boiler is characterized by comprising the following steps:

step S100, calculating an oxygen amount set value according to the boiler load;

step S200, comparing the set value of the oxygen amount with the obtained measured value of the oxygen amount through an oxygen amount regulator to obtain a deviation value of the oxygen amount;

step S300, calculating an air volume preset value according to the load of the boiler;

step S400, calculating according to the oxygen amount deviation value and the air volume preset value to obtain an air volume set value;

step S500, comparing the air volume set value with the obtained air volume measured value through an air volume regulator to obtain an air volume deviation value;

and step S600, controlling the air volume of the blower according to the air volume deviation value.

2. The air volume control method of a gas boiler according to claim 1, wherein the oxygen amount measurement value is an average value of effective oxygen amount values obtained at a plurality of measurement points in step S200.

3. The air volume control method of a gas boiler as claimed in claim 1, wherein in step S200, when the oxygen amount set value is compared with the obtained oxygen amount measured value, if the oxygen amount measured value is smaller than the oxygen amount set value, the deviation value of the output air volume is a positive number, and if the oxygen amount measured value is larger than the oxygen amount set value, the deviation value of the output air volume is a negative number.

4. The air volume control method of a gas boiler as claimed in claim 1, wherein in step S400, the air volume set value is obtained by summing an air volume deviation value and an air volume preset value, wherein the air volume preset value is smaller than the air volume set value if the air volume deviation value is negative, and is larger than the air volume set value if the air volume deviation value is positive.

5. The air quantity control method of the gas boiler as claimed in claim 1, wherein in step S500, the air quantity setting value and the obtained air quantity measured value are compared by the air quantity controller to obtain the air quantity deviation value by subtracting the air quantity setting value from the air quantity measured value, the air quantity is decreased when the air quantity deviation value is a positive number, and the air quantity is increased when the air quantity deviation value is a negative number.

6. The air quantity control method of the gas boiler as claimed in claim 1, wherein the step S600 further comprises calculating a real-time air quantity, wherein the supplementary blower is controlled to be turned off when the air quantity is greater than a preset value, and the supplementary blower is controlled to be turned on while adjusting the power of the blower when the air quantity is less than the preset value.

7. The air volume control method of the gas boiler as claimed in claim 1, further comprising a step S800 between the steps S500 and S600 of summing the air volume deviation values by the boiler main control feedforward to obtain a corrected air volume deviation value.

8. The air volume control method of the gas boiler as set forth in claim 7, further comprising a fuel fluctuation control method for regulating a main control feed forward of the boiler, the fuel fluctuation control method comprising:

the method comprises the steps that a monitoring position and a regulating position are arranged on a main gas pipeline of a boiler, a plurality of pressure monitoring units are sequentially arranged at the monitoring position along the gas flowing direction, and the regulating position is located at the downstream of the monitoring position and is provided with a main flow regulating valve;

monitoring the gas pressure by monitoring each pressure monitoring unit at a position, and calculating to obtain the variable quantity delta Q gas of the gas heat supply quantity caused by the gas fluctuation based on the monitored gas pressure fluctuation; calculating the time t1 required by the coal gas to run from the monitoring position to the adjusting position;

if Δ Q _{Gas (es)} More than 0, after time t1, reducing the opening of the main flow regulating valve to improve the main flow of the gas boilerSteam parameter stability;

if Δ Q _{Gas (es)} Less than 0, after time t1, increasing the opening of the main flow regulating valve to improve the stability of main steam parameters of the gas boiler;

if Δ Q _{Gas (es)} And =0, the opening of the main flow regulating valve is kept unchanged.

9. The air volume control method of a gas boiler as claimed in claim 8,

further comprising:

when the main flow regulating valve is regulated to the maximum opening and still cannot reach the control target, the main feed water flow of the boiler is further regulated to reach the control target.

10. The air volume control method of the gas boiler as set forth in claim 9, wherein the adjustment amount of the main feed water flow of the boiler is calculated according to the following formula:

wherein eta is the thermal efficiency of the boiler, h _out Specific enthalpy value, h, after heat exchange for water supply _in The enthalpy value is the specific enthalpy value before the heat exchange of the feed water.

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