CN115507379A - A gas boiler air volume control method - Google Patents

Abstract

The invention provides a gas boiler air volume control method, the gas boiler air volume control method includes: step S100, calculate the oxygen set value according to the boiler load; step S200, the oxygen set value and the obtained Comparing the oxygen measurement values to obtain the oxygen deviation value; step S300, calculate the air volume preset value according to the boiler load; step S400, calculate the air volume set value according to the oxygen volume deviation value and the air volume preset value; step S500, obtain the air volume preset value; The regulator compares the air volume setting value with the obtained air volume measurement value to obtain the air volume deviation value; step S600, controlling the air supply volume of the blower according to the air volume deviation value. The present invention fully considers the influence of the change of the oxygen amount on the preset value of the air volume, and uses the deviation value of the oxygen amount as the correction of the preset value of the air volume in the adjustment of the air volume to obtain the set value of the air volume, thereby improving the accuracy of the air volume control.

Description

A gas boiler air volume control method

technical field

The invention relates to the technical field of gas boilers, in particular to a gas boiler air volume control method.

Background technique

Gas boilers are widely used in self-owned power plants such as steel mills and coal chemical plants. By-product blast furnace gas, converter gas, coke oven gas, semi-coke tail gas and other fuels are used to generate electricity, which can realize clean and efficient use of energy. According to different production processes, steel mills and coal chemical plants often produce more than a single by-product, while gas boiler fuels have better adaptability, and generally have several fuel working conditions. These vary with the composition of the fuel and the changes in the flow rate of the fuel that require different air supply volumes.

At present, the gas boiler air volume control method usually directly compares the air volume preset value calculated according to the boiler load with the air volume measurement value to directly obtain the air volume deviation value, and controls the air supply volume according to the air volume deviation value. However, this gas boiler air volume control method does not fully consider the influence of oxygen volume changes on the air volume preset value, resulting in inaccurate air volume deviation values.

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

Contents of the invention

The purpose of the present invention is to provide a gas boiler air volume control method to solve the problem of low accuracy of the existing gas boiler air volume control method.

In order to solve the above technical problems, the present invention provides a gas boiler air volume control method, including: step S100, calculate the oxygen set value according to the boiler load; Oxygen volume measurement values are compared to obtain the oxygen volume deviation value; Step S300, calculate the air volume preset value according to the boiler load; Step S400, calculate the air volume set value according to the oxygen volume deviation value and the air volume preset value; Step S500, adjust the air volume The device compares the air volume setting value with the obtained air volume measurement value to obtain the air volume deviation value; step S600, controlling the air supply volume of the blower according to the air volume deviation value.

Optionally, in step S200, the oxygen measurement value is an average value of effective oxygen values obtained at multiple measurement points.

Optionally, in step S200, when comparing the oxygen amount set value with the obtained oxygen amount measured value, if the oxygen amount measured value is less than the oxygen amount set value, the output air volume deviation value is a positive number, if the oxygen amount If the measured value is greater than the set value of the oxygen volume, the output air volume deviation value is a negative number.

Optionally, in step S400, the air volume set value is obtained by summing the air volume deviation value and the air volume preset value. If the air volume deviation value is negative, the air volume preset value is less than the air volume set value. If the air volume deviation value is positive If the number is higher, the preset value of air volume is greater than the set value of air volume.

Optionally, in step S500, by using the air volume regulator to compare the air volume set value with the obtained air volume measurement value to obtain the air volume deviation value, the air volume measurement value is subtracted from the air volume set value, when the air volume deviation value is positive When the number is small, the air supply volume decreases, and when the air volume deviation value is negative, the air supply volume increases.

Optionally, step S600 also includes calculating the real-time air supply volume, wherein, when the air supply volume is greater than the preset value, the supplementary fan is controlled to be turned off; when the air supply volume is smaller than the preset value, the supplementary fan is controlled to be turned on, and the air supply fan is adjusted simultaneously power.

Optionally, a step S800 is further included between step S500 and step S600, summing up the air volume deviation values by the boiler main control feedforward to obtain the corrected air volume deviation value.

Optionally, it also includes a fuel fluctuation control method for adjusting the boiler main control feedforward, the fuel fluctuation control method includes: setting a monitoring position and an adjustment position on the gas main pipeline of the boiler, and at the monitoring position along the gas A plurality of pressure monitoring units are arranged in sequence in the flow direction, and the adjustment position is located downstream of the monitoring position and is provided with a main flow regulating valve; the gas pressure is monitored through each pressure monitoring unit at the monitoring position, and based on the monitored gas pressure Calculation of fluctuations to obtain the change in gas heat supply due to gas fluctuations ΔQ _gas ; calculate the time t1 required for the gas to run from the monitoring position to the adjustment position; if ΔQ _gas >0, after time t1, reduce the main The opening of the flow regulating valve to improve the stability of the main steam parameters of the gas boiler; if ΔQ _gas <0, after time t1, increase the opening of the main flow regulating valve to improve the stability of the main steam parameters of the gas boiler; If _ΔQgas =0, keep the opening of the main flow regulating valve unchanged.

Optionally, the method further includes: further adjusting the main feed water flow of the boiler to achieve the control target when the main flow regulating valve is adjusted to the maximum opening and still fails 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:

Among them, η is the thermal efficiency of the boiler, h _out is the specific enthalpy of the feed water after heat exchange, and h _in is the specific enthalpy of the feed water before heat exchange.

A gas boiler air volume control method provided by the present invention has the following beneficial effects:

Firstly, through a supplementary air duct that communicates with the atmosphere at one end and communicates with the front air duct of the air preheater at the other end, a supplementary fan is set on the supplementary air duct, and one end of the front air duct of the air preheater communicates with the atmosphere , the other end communicates with the air inlet of the air preheater. Therefore, when the air volume required by the boiler increases, the air volume can be supplemented into the front air duct of the air preheater through the supplementary fan and the supplementary air duct, and then passed through the air preheater. The air inlet of the air preheater supplements the air volume to the air preheater, so that the air volume can be supplemented to the furnace through the air duct after the air preheater, which is connected to the air outlet of the air preheater at one end and communicated with the furnace at the other end, so as to meet the needs of the gas boiler The working condition of larger air supply volume, and it is more economical than replacing the blower and motor to adapt to the working condition of large air supply volume.

Secondly, by fully considering the influence of the oxygen change on the preset value of the air volume, the deviation value of the oxygen amount is used as the correction of the preset value of the air volume in the adjustment of the air volume to obtain the set value of the air volume, thereby improving the accuracy of the air volume control.

Thirdly, by fully considering the influence of the boiler main control feedforward on the air volume deviation, the boiler main control feedforward sums the air volume deviation to obtain the corrected air volume deviation, thereby improving the accuracy of air volume control.

Secondly, the present invention sets a monitoring position upstream of the boiler burner. When gas fluctuations occur during the operation of the boiler, the opening of the flow regulating valve can be adjusted in advance according to the heat supply value fluctuations corresponding to the gas fluctuations monitored at the monitoring position. Adjustment, so as to maintain the stability of the heat released by gas combustion per unit time, and then improve the stability of the main steam parameters of the gas boiler.

Description of drawings

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

Fig. 2 is the control flowchart of gas boiler air volume control method in the embodiment of the present invention;

Fig. 3 is a schematic diagram of the gas pipeline of the fuel fluctuation control system provided by the embodiment of the present invention.

101-front duct of air preheater; 102-air preheater; 103-rear duct of air preheater; 104-front flue of heat exchanger; 105-supplementary air duct; 106-supplementary fan; ;108-Air supply branch pipe; 109-Flue gas gas heat exchanger; 110-Flue after heat exchanger; 111-Gas pipe before heat exchanger; 112-Gas pipe after heat exchanger; 113-Desulfurization tower; 114- 115-Blower inlet adjustment damper; 116-Blower outlet baffle door; 117-Supplementary fan inlet muffler; 118-Supplementary fan inlet adjustment damper; 119-Supplementary fan outlet baffle door; 120-Supplementary air duct Isolation door; 121-supplementary branch pipe isolation door;

200-gas main pipeline; 210-monitoring position; 211-pressure monitoring unit; 212-calorific value meter; 220-main flow regulating valve; 300-boiler burner; 400-gas storage bypass; 410-external gas source; 420-bypass regulating valve; 430-quick cut valve 430; 500-gas branch pipe; 510-branch flow regulating valve; 520-pressure monitoring device; 530-cut valve; 230-electric blind valve; cut valve.

detailed description

The gas boiler air supply and smoke temperature regulating system proposed by the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description. It should be noted that all the drawings are in a very simplified form and use imprecise scales, and are only used to facilitate and clearly assist the purpose of illustrating the embodiments of the present invention.

Embodiment one,

Referring to Fig. 1, Fig. 1 is a schematic structural diagram of a gas boiler air supply and flue temperature regulating system in an embodiment of the present invention. This embodiment provides a gas boiler air supply and flue temperature regulating system, including: Heater front air duct 101, the air inlet is connected to the other end of the air preheater front air duct 101 and the air preheater 102, one end communicates with the air outlet of the air preheater 102 and the other end communicates with the furnace The air preheater rear duct 103, one end of the heat exchanger front flue 104 communicated with the flue gas outlet of the air preheater 102, one end communicated with the atmosphere and the other end connected with the air preheater front duct A supplementary air passage 105 connected with 101, a supplementary fan 106 arranged on the supplementary air passage 105, and a blower 107 arranged on the front air passage 101 of the air preheater.

Through the supplementary air passage 105 that one end communicates with the atmosphere and the other end communicates with the air preheater front duct 101, a supplementary fan 106 is set on the supplementary air duct 105, and the front air duct 101 of the air preheater One end is communicated with the atmosphere, and the other end is communicated with the air inlet of the air preheater 102. Therefore, when the air volume required by the boiler increases, it can be blown into the front air duct 101 of the air preheater through the supplementary fan 106 and the supplementary air duct 105. Supplement the air volume, and then supplement the air volume to the air preheater 102 through the air inlet of the air preheater 102, so as to pass through the back air of the air preheater whose one end communicates with the air outlet of the air preheater 102 and the other end communicates with the furnace Road 103 supplements the air volume to the furnace, so as to adapt to the working conditions that the gas boiler needs a larger air supply volume, and it is more economical than replacing the air blower 107 and the motor to adapt to the working conditions of a large air supply volume.

Referring to FIG. 1 , the gas boiler air supply and flue temperature regulating system further includes a supplementary air branch pipe 108 whose one end communicates with the supplementary air duct and the other end communicates with the rear air duct 103 of the air preheater. On the one hand, by setting the supplementary air branch pipe 108, the front air duct 101 of the air preheater can be communicated with the rear air duct 103 of the air preheater, so that the part of the air volume sent by the air blower 107 into the front air duct 101 of the air preheater can be reduced. Entering the furnace from the air duct 103 after the air preheater, the air volume supplemented by the supplementary fan can also directly enter the rear air duct 103 of the air preheater from the supplementary air branch pipe 108, and then enter the furnace. In this way, different air volumes can be provided for different working conditions, and the temperature of the flue gas passing through the air preheater 102 can be adjusted to prevent the temperature of the flue gas entering the flue 104 before the heat exchanger from being too high or too low.

Referring to Fig. 1, the gas boiler air supply and flue temperature regulating system also includes a flue gas gas heat exchanger 109, and one end communicates with the flue gas outlet of the flue gas gas heat exchanger 109 and the other end communicates with the chimney The back flue 110 of the heat exchanger, the other end of the front flue 104 of the heat exchanger communicates with the flue gas inlet of the flue gas gas heat exchanger 109 .

Referring to Figure 1, the gas boiler air supply and flue temperature regulating system also includes a gas pipe 111 in front of the heat exchanger with one end connected to the gas inlet of the flue gas gas heat exchanger 109 and the other end connected to the gas pipe network , a post-heat exchanger gas pipe 112 that communicates with the gas outlet of the flue gas gas heat exchanger 109 at one end and communicates with the burner of the boiler at the other end.

Referring to FIG. 1 , the gas boiler air supply and flue temperature regulating system further includes a desulfurization tower 113 , and the desulfurization tower 113 is arranged on the flue 110 after the heat exchanger.

Referring to FIG. 1 , the number of the front air duct 101 of the air preheater and the rear air duct 103 of the air preheater are two, and the number of the supplementary air duct 105 and the supplementary air branch pipe 108 is one.

Referring to FIG. 1 , the air supply and flue temperature regulating system of the gas boiler also includes a blower inlet muffler 114 , and the blower inlet silencer 114 is arranged on the front air duct 101 of the air preheater and is located between the atmosphere and the blower 107 between.

Referring to Fig. 1, the gas boiler air supply and flue temperature regulating system also includes a blower inlet regulating damper 115, the blower inlet regulating damper 115 is arranged on the front air duct 101 of the air preheater and is located at the blower inlet silencer Between the device 114 and the air blower 107, it is used to adjust the air volume entering the air blower 107.

Referring to Fig. 1, the air supply and flue temperature regulating system of the gas boiler also includes a blower outlet baffle door 116, and the blower outlet baffle door 116 is arranged on the front air duct 101 of the air preheater and is located at the blower outlet. Between 107 and the air preheater, it is used to control the flow and closure of the front air duct 101 of the air preheater.

Referring to FIG. 1 , the gas boiler air supply and flue temperature regulating system also includes a supplementary fan inlet muffler 117, and the supplementary fan inlet muffler 117 is arranged on the supplementary air duct 105 and is located between the atmosphere and the supplementary air duct. Between the fan 106.

Referring to FIG. 1 , the gas boiler air supply and flue temperature regulating system also includes a supplementary fan inlet adjustment damper 118, which is arranged on the supplementary air duct 105 and located between the muffler and the Between the supplementary blower 106 , it is used to adjust the air volume entering the supplementary blower 106 .

Referring to Fig. 1, the gas boiler air supply and flue temperature regulating system also includes a supplementary fan outlet baffle door 119, the supplementary fan outlet baffle door 119 is arranged on the supplementary air duct 105 and is located in the air preheating Between the device 102 and the supplementary fan 106, it is used to control the circulation and closure of the supplementary air duct 105.

Referring to FIG. 1 , the gas boiler air supply and flue temperature regulating system further includes a supplementary air duct insulation door arranged on the supplementary air duct 105 and located between the supplementary air branch pipe 108 and the air preheater 102 120.

Referring to FIG. 1 , the air supply and flue temperature regulating system of the gas boiler further includes an isolation door 121 for the supplementary air branch pipe 108 arranged on the supplementary air branch pipe 108 .

The gas boiler air supply and smoke temperature regulating system also includes an air volume controller, which is used to control the blower 107, the blower outlet baffle door 116, the supplementary blower according to the fuel working conditions of the boiler. 106 and the opening and closing of the supplementary fan outlet baffle door 119, the opening and closing of the supplementary air passage isolation door 120 and the supplementary air duct 108 isolation door 121 are controlled according to the boiler exhaust gas temperature.

When the amount of air required for boiler fuel combustion is not large, the supplementary fan 106, supplementary fan outlet baffle door 119, supplementary air duct isolation door 120, supplementary air branch pipe 108 isolation door 121 can be closed, and cold air flows from the air preheater. The front air channel 101 enters the air preheater 102, then enters the rear air channel 103 of the air preheater, and then flows out into the boiler furnace. At this time, if the exhaust gas temperature of the boiler is low, open the supplementary air passage isolation door 120 and the supplementary air branch pipe 108 isolation door 121, and part of the cold air enters the air preheater front air duct 101 from one end of the air preheater front duct 101 After that, it can enter the supplementary air duct 105 from the front air duct 101 of the air preheater, and then enter the supplementary air branch pipe 108, and then enter the rear air duct 103 of the air preheater from the supplementary air branch pipe 108 and flow out to the boiler furnace. The cold air enters the air preheater 102 from the front air duct 101 of the air preheater, then enters the rear air duct 103 of the air preheater, and then flows out into the furnace of the boiler. In this way, the temperature of the flue gas in the front flue 104 of the heat exchanger and the flue gas after the heat exchanger 110 can be avoided from being too low, causing the sulfur dioxide produced by combustion to easily corrode the flue 110 after the heat exchanger and affect desulfurization at low temperatures The desulfurization effect of tower 113.

When the amount of air supply required for boiler fuel combustion is large, open the supplementary fan 106, supplementary fan outlet baffle door 119, supplementary air duct isolation door 120, close the supplementary air branch pipe 108 isolation door 121, and cool air from the air preheater The front air channel 101 and the supplementary air channel 105 enter the air preheater 102, then enter the air preheater rear air channel 103, and then flow out into the boiler furnace. At this time, if the exhaust gas temperature of the boiler is low, close the supplementary air passage isolation door 120, open the supplementary air branch pipe 108 isolation door 121, and a part of cold air enters the rear air duct 103 of the air preheater from the supplementary air duct 105 through the supplementary air branch pipe 108 After entering the furnace, a part of cold air enters the air preheater 102 from the air preheater front duct 101, then enters the air preheater rear air duct 103 from the air preheater 102, and then flows out into the boiler furnace.

The flue gas can flow from the boiler furnace through the air preheater 102 into the front flue 104 of the heat exchanger, then flow into the flue gas gas heat exchanger 109, then flow into the rear flue 110 of the heat exchanger, and finally flow 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 gas heat exchanger 109, then flow into the gas pipe 112 behind the heat exchanger, and then flow into the boiler furnace.

Wherein, the cold air and the flue gas can conduct heat exchange in the air preheater 102 to cool the flue gas for the first time, and the coal gas and the flue gas can be exchanged at the flue gas gas heat exchanger 109 Heat exchange to cool the flue gas a second time.

When the boiler is running at low load (near the maximum continuous evaporation of 60% of the boiler), the amount of air supply required for boiler fuel combustion is not large and the temperature of the flue gas discharged from the boiler is relatively low, so turn off the supplementary fan 106 1. Supplement the fan outlet baffle door 119, open the supplementary air passage 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. The cold air enters the front air duct 101 of the air preheater from one end of the front air duct 101 of the air preheater, and part of it enters the air preheater 102 from the other end of the front air duct 101 of the air preheater, and then flows into the air preheater Part of the cold air enters the furnace from one end of the supplementary air duct 105 through the supplementary air duct 105, the supplementary air branch pipe 108, and the rear air duct 103 of the air preheater. Since part of the cold air does not pass through the air preheater 102, the amount of cold air that exchanges heat with the flue gas at the air preheater 102 can be reduced, so that the air passing through the air preheater 102 and the gas heat exchanger can be reduced. The flue gas is maintained at about 140°, which meets the reaction temperature required for the dry desulfurization of baking soda in the desulfurization tower 113, and prevents the temperature of the flue gas from passing through the gas heat exchanger above the dew point temperature, forming low-temperature corrosion and affecting the flue gas gas heat exchanger 109 service life.

When the boiler is running under high load (near the maximum continuous evaporation capacity of the boiler at 100%), if the air supply volume required for boiler fuel combustion is not large and the exhaust gas temperature of the boiler is high, the supplementary fan 106 and supplementary fan can be turned off The outlet baffle door 119 , the supplementary air channel isolation door 120 on the supplementary air channel 105 and the isolation door 121 on the supplementary air branch pipe 108 on the supplementary air branch pipe 108 . The cold air enters the front air duct 101 of the air preheater from one end of the front air duct 101 of the air preheater, and all enters the air preheater 102 from the other end of the front air duct 101 of the air preheater, and flows through the air preheating Then flow into the air duct 103 after the air preheater 102, and then flow into the boiler furnace. Since all the air entering the furnace of the boiler 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 large extent and the efficiency of the boiler can be improved. When the air supply volume required for boiler fuel combustion is large and the temperature of the boiler exhaust gas is high, the supplementary fan 106, the supplementary fan outlet baffle door 119, the supplementary air duct isolation door 120 on the supplementary air duct 105 can be opened, and the supplementary air duct can be closed. The supplementary air branch pipe 108 on the air branch pipe 108 isolating the door 121, the cold air enters the front air passage 101 of the air preheater from one end of the air preheater front duct 101 and the supplementary air duct 105, and all the cold air enters from the front air duct 101 of the air preheater. The other end of the channel 101 enters the air preheater 102, flows through the air preheater 102, then flows into the rear air channel 103 of the air preheater, and then flows into the boiler furnace. Since all the air entering the furnace of the boiler 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 large extent and the efficiency of the boiler can be improved.

When the boiler operates in a low-temperature environment, such as in winter in the north, 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 relatively low, resulting in The temperature of the flue gas in the flue 110 after entering the gas heat exchanger 109 is relatively low. At this time, if the air supply volume required for boiler fuel combustion is not large, close the supplementary fan 106 and the outlet baffle of the supplementary fan. The door 119 opens the supplementary air channel isolation door 120 on the supplementary air channel 105 and the isolation door 121 on the supplementary air branch pipe 108 on the supplementary air branch pipe 108 . The cold air enters the front air duct 101 of the air preheater from one end of the front air duct 101 of the air preheater, and part of it enters the air preheater 102 from the other end of the front air duct 101 of the air preheater, and then flows into the air preheater Part of the cold air enters the furnace from one end of the supplementary air duct 105 through the supplementary air duct 105, the supplementary air branch pipe 108, and the rear air duct 103 of the air preheater. Since part of the cold air does not pass through the air preheater 102, the amount of cold air that exchanges 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 The gas is maintained at a higher temperature.

Embodiment two,

Referring to FIG. 2, FIG. 2 is a control flow chart of a gas boiler air volume control method in an embodiment of the present invention. This embodiment provides a gas boiler air volume control method, including:

Step S100, calculating the oxygen setting value according to the boiler load;

Step S200, comparing the set value of the oxygen amount with the measured value of the oxygen amount obtained by the oxygen amount regulator to obtain an oxygen amount deviation value;

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

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

Step S500, comparing the air volume setting value with the obtained air volume measurement value through the air volume regulator to obtain the air volume deviation value;

Step S600, controlling the air supply volume of the air blower according to the air volume deviation value.

In this 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, and the steam turbine is used to do work externally. When the boiler is doing work, the more work done per unit time, the larger the boiler load, and vice versa.

In step S200, the oxygen measurement value is an average value of effective oxygen values obtained at multiple measurement points. For example, there are five measurement points, and the oxygen value measured by one of the measurement points is obviously wrong, then delete the oxygen value measured by the measurement point, and calculate the average value of the oxygen value measured by the remaining four measurement points. Oxygen measurements are available.

In step S200, when comparing the oxygen amount set value with the obtained oxygen amount measured value, if the oxygen amount measured value is less than the oxygen amount set value, the output air volume deviation value is a positive number, if the oxygen amount measured value is greater than the oxygen amount If the set value of air volume is set, the output air volume deviation value is a negative number.

Between step S100 and step S200, step S700 is also included to manually correct the set value of the oxygen amount. By manually correcting the oxygen setting value, the accuracy of the air volume control of the blower can be further improved.

In step S400, the air volume setting value is obtained by summing the air volume deviation value and the air volume preset value. If the air volume deviation value is negative, the air volume preset value is less than the air volume setting value. The set value is greater than the air volume set value.

In step S500, the air volume setting value is compared with the obtained air volume measurement value through the air volume regulator to obtain the air volume deviation value, which is to subtract the air volume setting value from the air volume measurement value, and when the air volume deviation value is a positive number, send The air volume decreases, and when the air volume deviation value is negative, the air supply volume increases.

In step S600, when the air volume deviation value is a positive number, the air supply volume is controlled to decrease, and when the air volume deviation value is a negative number, the air supply volume is controlled to increase.

Step S600 also includes calculating the real-time air supply volume, wherein, when the air supply volume is greater than the preset value, the supplementary fan is controlled to be turned off, and when the air supply volume is smaller than the preset value, the supplementary fan is controlled to be turned on, and the power of the blower fan is adjusted at the same time.

A step S800 is also included between step S500 and step S600 , summing the air volume deviation values by the boiler main control feedforward to obtain a corrected air volume deviation value. Among them, the boiler main control feed-forward is the feed-forward air volume value calculated according to the gas fluctuation. When the front feed air volume value increases, the fuel volume increases, and the greater the air volume deviation value, the greater the required air supply volume. When the current feed air volume value decreases, the fuel volume decreases, and the air volume deviation value increases. The smaller the air volume required, the smaller it will be. That is to say, gas fluctuations affect the magnitude of the air volume deviation in real time. Therefore, if you want to control the air supply volume in real time and accurately, the control of gas fluctuations is also critical.

Embodiment three,

In this embodiment, the smaller the gas fluctuation is, the more favorable it is for air volume control. Based on this, this embodiment provides a fuel fluctuation control method, the method is:

A monitoring position 210 and an adjustment position are set on the gas main pipeline 200 of the boiler, and a plurality of pressure monitoring units 211 are arranged in sequence along the gas flow direction at the monitoring position 210, and the adjustment position is located downstream of the monitoring position 210 and is set There is a main flow regulating valve 220;

The gas pressure is monitored by each pressure monitoring unit 211 at the monitoring position 210, and the gas heat supply variation ΔQ _gas caused by the gas fluctuation is calculated based on the monitored gas pressure fluctuation; the calculated gas runs from the monitoring position 210 to The time t1 required to adjust the bit;

If ΔQ _gas >0, after time t1, reduce the opening of the main flow regulating valve 220 to improve the stability of the main steam parameters of the gas boiler;

If ΔQ _gas <0, after time t1, increase the opening of the main flow regulating valve 220 to improve the stability of the main steam parameters of the gas boiler;

If _ΔQgas =0, keep the opening of the main flow regulating valve 220 unchanged.

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

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

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

Q _gas = qm _gas

Among them, q is the calorific value of the gas, which can be monitored in real time by installing a calorific value meter 212 on the pipeline; m _gas is the gas flow rate, and m _gas can be converted by monitoring the gas pressure.

Correspondingly, a gas calorific value meter 212 is also provided at the monitoring position 210, which can monitor the gas calorific value online. The gas calorific value meter 212 can be arranged on the same section of the main gas pipeline 200 opposite to one of the pressure monitoring units 211, and also It can be arranged between two adjacent pressure monitoring units 211 , or arranged downstream of each pressure monitoring unit 211 .

In actual operation, the fluctuation of the calorific value of the gas is relatively small. Therefore, in this embodiment, the impact of the fluctuation of the gas flow on the operation of the boiler is mainly considered.

There is a certain distance between the monitoring position 210 and the adjustment position, so as to ensure that corresponding processing can be carried out in advance when the gas fluctuates. In one of the embodiments, the distance between the monitoring position 210 and the adjustment position is more than 20m, for example, controlled within the range of 20-100m.

There is a certain distance between the adjustment position and the boiler burner 300, and the distance is also preferably more than 20m, for example, within the range of 20-100mm.

Further, when calculating the time t1 required for the gas to run from the monitoring position 210 to the adjustment position, the position of the gas pressure measuring point at the central position or the central position of the monitoring position 210 is used as the initial operating position of the gas, and the gas flow rate can be at It is calculated based on the gas pressure monitored at the initial operating position and combined with the pipe diameter.

Further, when calculating ΔQ _gas , first obtain the gas pressure fluctuation, specifically, calculate the pressure difference between every two adjacent gas pressure measuring points, and take the average value of each pressure difference as the gas pressure fluctuation. When calculating the pressure difference between every two adjacent gas pressure measuring points, it is preferably the monitoring data of the downstream gas pressure measuring point minus the monitoring data of the upstream gas pressure measuring point. Since gas fluctuation is generally a creep process rather than a sudden change process, the above calculation method can ensure the accuracy and reliability of the monitoring results.

The above-mentioned main flow regulating valve 220 is an automatic valve, and a flow regulating valve such as an electric butterfly valve can be used.

Further preferably, when adjusting the opening degree of the main flow regulating valve 220, the goal of the adjustment is to control the fluctuation range of the middle point temperature of the boiler within 0-10°C, so as to achieve the above-mentioned improvement of the stability of the main steam parameters of the gas boiler Effect.

When the calorific value of the gas fluctuates little, preferably, the opening of the main flow regulating valve 220 increases or decreases by 1% to 10% for every 1KPa decrease or increase of the gas pressure.

Further preferably, the above control method also includes:

When the main flow regulating valve 220 is adjusted to the maximum opening and still fails to reach the control target, the control target is further achieved by adjusting the main feed water flow of the boiler. Among them, after the flow regulating valve is opened to the maximum opening degree, the main feed water flow of the boiler is further adjusted.

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

Q _water = ηQ _gas

Among them, Q water is the heat absorbed by the feed water heat exchange; η is the thermal efficiency of the boiler.

Q _water = m _water (h _out -h _in )

Among them, m _water is the main feed water flow rate of the boiler; h _out is the specific enthalpy value of the feed water after heat exchange, and h _in is the specific enthalpy value of the feed water before heat exchange. For the table look-up operation of h _out and h _in , the current engineering generally refers to the "Water and Steam Thermodynamic Properties Chart Manual"; the parameters of boiler main feed water and main steam are applicable to the "water and superheated steam table" in this manual. Specifically, according to the temperature and pressure parameters of the boiler main feed water, query the "water and superheated steam table" to obtain the specific enthalpy value h _in of the boiler main feed water; according to the temperature and pressure parameters of the boiler main steam, query the "water and superheated steam table ” to obtain the boiler main steam specific enthalpy value h _out .

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

Although the thermal efficiency η of the boiler is different under different loads, since the fluctuation of gas is generally a continuous process, the thermal efficiency η of the boiler will not change suddenly, so it can be approximately considered that the thermal efficiency η of the boiler at two adjacent monitoring times remains unchanged. However, preferably, after each adjustment of the opening of the main flow regulating valve 22012, the thermal efficiency η of the boiler is recalculated. The specific calculation method is a conventional technique in the art, and will not be repeated here.

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

Among them, η is the thermal efficiency of the boiler, h _out is the specific enthalpy of the feed water after heat exchange, and h _in is the specific enthalpy of the feed water before heat exchange.

According to the above calculation results, the inverter frequency of the feed water pump can be adjusted to achieve the purpose of adjusting the main feed water flow of the boiler. The adjustment amount of boiler main feed water flow equal to Δm _water is obviously an ideal adjustment target, but considering the actual working conditions, it is considered reasonable that the adjustment amount of boiler main feed water flow is close to this Δm _water , and the specific difference should meet the guarantee of the middle point of the boiler The fluctuation range of temperature is required in the range of 0-10°C.

Further, the method also includes:

Obtain 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 feedwater to be transmitted from the feedwater pump to the boiler water wall,

If t2>t3, the main feed water flow of the boiler is adjusted laggingly, and the lag time is t2-t3. Or add external source gas to the gas main pipeline 200 to improve the stability of the main steam parameters of the gas boiler, wherein the external source gas supply point is located downstream of the monitoring position 210, and can be located upstream or downstream of the adjustment position. The time when the gas reaches the boiler burner 300 is preferably the same as t3, and at the same time when the gas fluctuation signal is detected, the external source gas is replenished, and the ventilation time of the external source gas is t2-t3. Wherein, a gas storage bypass 400 can be connected to the main gas pipeline 200, the gas storage bypass 400 is connected to an external gas source 410, and a bypass regulating valve 420 and a quick cut valve 430 are set on the gas storage bypass 400, The flow rate of external source gas is controlled by the bypass regulating valve 420 .

If t2<t3, before the boiler main feedwater flow is adjusted in place, reduce the opening of the branch flow regulating valve 510 on the gas branch pipe 500 at the inlet side of the boiler burner 300 to improve the stability of the main steam parameters of the gas boiler. Further, when the time t3 is reached, the opening of the branch pipe flow regulating valve 510 is reset to the position before the gas fluctuation, so as to further improve the stability of the subsequent boiler operation.

Based on the above scheme, the time for the gas fluctuation to reach the boiler burner 300 and the time for the feed water to reach the water wall of the boiler are fully considered to ensure the reliability of the adjustment operation, further improve the operation stability of the gas boiler, and ensure the main steam under various working conditions. Parameters can be controlled within target ranges.

The above-mentioned main gas pipeline 200 transports preferably steel plant gas, such as blast furnace gas. The above-mentioned main steam parameters are preferably pressure not lower than 22.12Mpa and temperature not lower than 540°C. The above-mentioned supercritical gas boiler can be applied to supercritical gas generator sets, ultra-supercritical gas generator sets, etc.

Although the fuel fluctuation control method can reduce the fluctuation of the gas to reduce the regulation of the air volume, the fluctuation of the gas cannot be avoided. Therefore, it is necessary to provide the gas boiler air volume control method in the second embodiment to control the air volume of the blower and the supplementary fan. To regulate.

Embodiment four,

The embodiment of the present invention provides a fuel fluctuation control system, which includes a gas main pipeline 200 and a plurality of gas branch pipelines 500 connected to each boiler burner 300 in a one-to-one correspondence. The gas main pipeline 200 is provided with a monitoring position 210 and And the adjustment position, at the monitoring position 210 is provided with a gas calorific value instrument 212 and a plurality of pressure monitoring units 211 distributed sequentially along the gas flow direction, the adjustment position is located downstream of the monitoring position 210 and is provided with a main flow rate Regulate valve 220 .

Wherein, the pressure monitoring unit 211 may adopt pressure measuring equipment such as a pressure transmitter.

There is a certain distance between the monitoring position 210 and the adjustment position, so as to ensure that corresponding processing can be carried out in advance when the gas fluctuates. In one of the embodiments, the distance between the monitoring position 210 and the adjustment position is more than 20m, for example, controlled within the range of 20-100m.

There is a certain distance between the adjustment position and the boiler burner 300, and the distance is also preferably more than 20m, for example, within the range of 20-100m.

Wherein, the monitoring position 210 is an interval, that is, has a certain axial length of the pipeline, for example, a monitoring section of the main gas pipeline 2001, which facilitates the arrangement of monitoring equipment.

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

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

The above-mentioned main flow regulating valve 220 is an automatic valve, and a flow regulating valve such as an electric butterfly valve can be used.

Further, the above system also includes a main controller and a comparator, the main controller is used for:

Obtain the monitoring data of the gas calorific value meter 212 and the monitoring data of each of the pressure monitoring units 211;

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

And according to the comparison result, the change amount ΔQ _gas of the gas heat supply caused by the gas fluctuation is calculated, and the opening degree of the main flow regulating valve 220 is controlled according to a predetermined strategy.

Further, the predetermined strategy may refer to the relevant content in the third embodiment above, for example, the predetermined strategy includes:

If ΔQ _gas >0, after time t1, reduce the opening of the main flow regulating valve 220 to improve the stability of the main steam parameters of the gas boiler;

If ΔQ _gas <0, after time t1, increase the opening of the main flow regulating valve 220 to improve the stability of the main steam parameters of the gas boiler;

If _ΔQgas =0, keep the opening of the main flow regulating valve 220 unchanged.

Further, the above-mentioned main controller is also used to adjust the frequency converter frequency of the main feedwater pump, so as to match the amount of supplied gas with the flow rate of the main feedwater. For relevant content, reference may be made to the third embodiment above, and details are not repeated here.

Further, as shown in Figure 3, Figure 3 is a schematic diagram of the gas pipeline of the fuel fluctuation control system provided by the embodiment of the present invention, the gas branch pipeline 500 is provided with a branch flow regulating valve 510, and further can be installed on the gas branch pipeline 500 A pressure monitoring device 520 is provided, and the branch pipe flow regulating valve 510 and the pressure monitoring device 520 are both electrically connected to the main controller. In addition, a shut-off valve 530 is provided on the gas branch pipeline 500, for example, a hydraulic shut-off valve 530 is used, which can further improve the reliability of system operation.

Further, as shown in Figure 3, the main gas pipeline 200 is connected with a gas storage bypass 400, and the gas storage bypass 400 is connected with an external gas source 410, and the gas storage bypass 400 is provided with a bypass adjustment valve 420 and shutoff valve 530. The external source gas source 410 can be an external source gas storage tank, etc. The external source gas can be the same type of gas supplied by the main gas pipeline 200, for example, both are blast furnace gas, and the external source gas can be pre-discharged at the initial stage of operation. The source gas storage tank is full. The bypass point of the gas storage bypass 400 is preferably located downstream of the monitoring position 210, and may be located upstream or downstream of the regulating position.

The above main controller is also used to:

Obtain 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 feedwater pump to the water wall of the boiler; and send t2 and t3 to the comparator for comparison and obtain the comparison result of the comparator; And execute the set policy according to the comparison result. For the above setting strategy, please refer to the relevant content in the third embodiment.

In addition, as shown in Figure 3, preferably, a heat exchanger is also provided at the tail end of the main gas pipeline 200, the heat exchanger is preferably a flue gas gas heat exchanger 109, which can use the waste heat of the flue gas discharged from the boiler to improve the gas burning effect.

Optionally, as shown in Fig. 3, an electric blind valve 230 and a hydraulic quick-cut valve 240 are also provided on the main gas pipeline 200, which can further improve the reliability of system operation.

The above description is only a description of the preferred embodiments of the present invention, and does not limit the scope of the present invention. Any changes and modifications made by those of ordinary skill in the field of the present invention based on the above disclosures shall fall within the protection scope of the claims.

Claims (10)

1. A gas boiler air volume control method, characterized in that, comprising: Step S100, calculating the oxygen setting value according to the boiler load; Step S200, comparing the set value of the oxygen amount with the measured value of the oxygen amount obtained by the oxygen amount regulator to obtain an oxygen amount deviation value; Step S300, calculating the preset value of the air volume according to the boiler load; Step S400, calculating the air volume set value according to the oxygen amount deviation value and the air volume preset value; Step S500, comparing the air volume setting value with the obtained air volume measurement value through the air volume regulator to obtain the air volume deviation value; Step S600, controlling the air supply volume of the air blower according to the air volume deviation value. 2 . The gas boiler air volume control method according to claim 1 , characterized in that, in step S200 , the oxygen measurement value is an average value of effective oxygen values obtained from multiple measurement points. 3 . 3. The gas boiler air volume control method according to claim 1, characterized in that, in step S200, when comparing the oxygen set value with the obtained oxygen measured value, if the oxygen measured value is less than the oxygen set value value, the output air volume deviation value is positive, if the oxygen measurement value is greater than the oxygen set value, the output air volume deviation value is negative. 4. The gas boiler air volume control method according to claim 1, characterized in that, in step S400, the air volume set value is obtained by summing the air volume deviation value and the air volume preset value, and if the air volume deviation value is negative, the air volume The preset value is smaller than the air volume set value, and if the air volume deviation value is a positive number, the air volume preset value is greater than the air volume set value. 5. The gas boiler air volume control method according to claim 1, characterized in that, in step S500, the air volume set value is compared with the air volume measured value obtained by the air volume regulator to obtain the air volume deviation value, which is to compare the air volume The measured value minus the air volume setting value, when the air volume deviation value is positive, the air supply volume will decrease, and when the air volume deviation value is negative, the air supply volume will increase. 6. The gas boiler air volume control method according to claim 1, characterized in that step S600 also includes calculating the real-time air supply volume, wherein, when the air supply volume is greater than the preset value, the supplementary fan is controlled to be turned off, and when the air supply volume When the amount is less than the preset value, the supplementary fan is controlled to be turned on, and the power of the blower is adjusted at the same time. 7. The gas boiler air volume control method according to claim 1, characterized in that, between step S500 and step S600, step S800 is further included, summing the air volume deviation values of the boiler main control feedforward to obtain the corrected Air volume deviation value. 8. The gas boiler air volume control method as claimed in claim 7, further comprising a fuel fluctuation control method for adjusting boiler main control feedforward, said fuel fluctuation control method comprising: A monitoring position and an adjustment position are set on the gas main pipeline of the boiler, and a plurality of pressure monitoring units are sequentially arranged along the gas flow direction at the monitoring position, and the adjustment position is located downstream of the monitoring position and is provided with a main flow regulating valve; The gas pressure is monitored by each pressure monitoring unit at the monitoring position, and the change amount ΔQ gas of the gas heat supply caused by the gas fluctuation is calculated based on the monitored gas pressure fluctuation; the gas is calculated from the monitoring position to the adjustment position The required time t1; If ΔQ _gas >0, after time t1, reduce the opening of the main flow regulating valve to improve the stability of the main steam parameters of the gas boiler; If ΔQ _gas <0, after time t1, increase the opening of the main flow regulating valve to improve the stability of the main steam parameters of the gas boiler; If _ΔQgas =0, keep the opening of the main flow regulating valve unchanged. 9. The gas boiler air volume control method as claimed in claim 8, characterized in that: Also includes: When the main flow regulating valve is adjusted to the maximum opening and still fails to reach the control target, further adjust the boiler main feed water flow to achieve the control target. 10. The air volume control method of a gas boiler as claimed in claim 9, wherein the adjustment amount of the main feed water flow of the boiler is calculated according to the following formula:

Among them, η is the thermal efficiency of the boiler, h _out is the specific enthalpy of the feed water after heat exchange, and h _in is the specific enthalpy of the feed water before heat exchange.

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