A method for controlling air volume of gas boiler

Abstract

The present invention provides a gas boiler air volume control method, the gas boiler air volume control method comprising: step S100, calculating an oxygen volume set value according to a boiler load; step S200, comparing the oxygen volume set value with an obtained oxygen volume measurement value through an oxygen volume regulator to obtain an oxygen volume deviation value; step S300, calculating an air volume preset value according to the boiler load; step S400, calculating an air volume set value according to the oxygen volume deviation value and the air volume preset value; step S500, comparing the air volume set value with an obtained air volume measurement value through an air volume regulator to obtain an air volume deviation value; step S600, controlling the air volume of a blower according to the air volume deviation value. The present invention fully considers the influence of oxygen volume changes on the air volume preset value, and uses the oxygen volume deviation value as a correction of the air volume preset value in air volume regulation to obtain the air volume set value, thereby improving the accuracy of air volume control.

Description

Technical Field

[0001] The invention relates to the technical field of gas boilers, and in particular to a method for controlling the air volume of a gas boiler. Background Art

[0002] Gas boilers are widely used in self-contained power plants such as steel mills and coal chemical plants. They use by-products such as blast furnace gas, converter gas, coke oven gas, and lignite tail gas to generate electricity, which can achieve clean and efficient use of energy. Steel mills and coal chemical plants often produce more than a single by-product due to different production processes, while gas boilers have better fuel adaptability and generally have several fuel operating conditions. These require different air supply volumes depending on the different fuel components and changes in fuel flow.

[0003] At present, the air volume control method of a gas boiler usually directly compares the preset air volume 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 method of controlling the air volume of a gas boiler does not fully consider the impact of oxygen content changes on the preset air volume value, resulting in an inaccurate air volume deviation value.

[0004] Therefore, it is necessary to improve the existing gas boiler air volume control method to improve the accuracy of air volume control. Summary of the invention

[0005] The object of the present invention is to provide a method for controlling the air volume of a gas boiler, so as to solve the problem of low accuracy of the existing method for controlling the air volume of a gas boiler.

[0006] In order to solve the above technical problems, the present invention provides a gas boiler air volume control method, including: step S100, calculating the oxygen content set value according to the boiler load; step S200, comparing the oxygen content set value and the obtained oxygen content measurement value through an oxygen content regulator to obtain an oxygen content deviation value; step S300, calculating the air volume preset value according to the boiler load; step S400, calculating the air volume set value according to the oxygen content deviation value and the air volume preset value; step S500, comparing the air volume set value and the obtained air volume measurement value through an air volume regulator to obtain an air volume deviation value; step S600, controlling the air volume of the blower according to the air volume deviation value.

[0007] Optionally, in step S200, the oxygen content measurement value is an average value of valid oxygen content values ​​obtained from multiple measurement points.

[0008] Optionally, in step S200, when the oxygen content set value and the obtained oxygen content measurement value are compared, if the oxygen content measurement value is less than the oxygen content set value, the output air volume deviation value is a positive number; if the oxygen content measurement value is greater than the oxygen content set value, the output air volume deviation value is a negative number.

[0009] Optionally, 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 a negative number, the air volume preset value is less than the air volume setting value; if the air volume deviation value is a positive number, the air volume preset value is greater than the air volume setting value.

[0010] Optionally, in step S500, the air volume setting value and the obtained air volume measurement value are compared by the air volume regulator to obtain an air volume deviation value, which is the air volume measurement value minus the air volume setting value. When the air volume deviation value is a positive number, the air supply volume decreases, and when the air volume deviation value is a negative number, the air supply volume increases.

[0011] Optionally, step S600 also includes calculating the real-time air supply volume, wherein when the air supply volume is greater than a preset value, the supplementary fan is controlled to be turned off, and when the air supply volume is less than the preset value, the supplementary fan is controlled to be turned on, and the power of the air supply fan is adjusted at the same time.

[0012] Optionally, step S800 is further included between step S500 and step S600, in which the air volume deviation values ​​of the boiler master control feedforward are summed to obtain a corrected air volume deviation value.

[0013] Optionally, a fuel fluctuation control method for adjusting the boiler main control feedforward is also included, and the fuel fluctuation control method includes: setting a monitoring position and an adjustment position on the gas main pipeline of the boiler, and sequentially setting a plurality of pressure monitoring units at the monitoring position along the gas 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 by each pressure monitoring unit at the monitoring position, and the change ΔQ of the gas heat supply caused by the gas fluctuation is calculated based on the monitored gas pressure fluctuation 煤气 ; Calculate the time t1 required for gas to run from the monitoring position to the regulating position; if ΔQ 煤气 >0, after time t1, reduce the main flow regulating valve opening to improve the main steam parameter stability of the gas boiler; if ΔQ 煤气 <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 ΔQ 煤气 =0, keeping the opening of the main flow regulating valve unchanged.

[0014] Optionally, it also includes: when the main flow regulating valve is adjusted to the maximum opening and still cannot achieve the control target, further adjusting the boiler main feed water flow to achieve the control target.

[0015] Optionally, the adjustment amount of the boiler main feed water flow is calculated according to the following formula:

[0016]

[0017] Where η is the thermal efficiency of the boiler, h outis the specific enthalpy of feed water after heat exchange, h in is the specific enthalpy of feed water before heat exchange.

[0018] The present invention provides a method for controlling the air volume of a gas boiler, which has the following beneficial effects:

[0019] Firstly, a supplementary air duct is provided with one end connected to the atmosphere and the other end connected to the front air duct of the air preheater, and a supplementary fan is arranged on the supplementary air duct, and one end of the front air duct of the air preheater is connected to the atmosphere, and the other end is connected to the air inlet of the air preheater. Therefore, when the air volume required by the boiler becomes larger, 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 the air volume can be supplemented into the air preheater through the air inlet of the air preheater, so as to supplement the air volume into the furnace through the rear air duct of the air preheater which is connected to the air outlet of the air preheater at one end and connected to the furnace at the other end. Therefore, the working condition that the gas boiler needs a larger air supply volume is adapted, and it is more economical than replacing the blower and the motor to adapt to the working condition with a larger air supply volume.

[0020] Secondly, by fully considering the influence of oxygen content change on the preset air volume value, the oxygen content deviation value is used as a correction to the preset air volume value in air volume regulation to obtain the air volume set value, thereby improving the accuracy of air volume control.

[0021] Thirdly, by fully considering the influence of the boiler main control feedforward on the air volume deviation value, the air volume deviation value of the boiler main control feedforward is summed to obtain the corrected air volume deviation value, thereby improving the accuracy of air volume control.

[0022] Secondly, the present invention sets a monitoring point upstream of the boiler burner. When gas fluctuations occur during the operation of the boiler, the opening of the flow control valve can be adjusted in advance according to the fluctuations in the heat supply value corresponding to the gas fluctuations monitored at the monitoring point, thereby maintaining the stability of the heat released by gas combustion per unit time, thereby improving the stability of the main steam parameters of the gas boiler. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the structure of the air supply and smoke temperature adjustment system for a gas boiler in an embodiment of the present invention;

[0024] Figure 2 is a control flow chart of a method for controlling the air volume of a gas boiler in an embodiment of the present invention;

[0025] Figure 3 A schematic diagram of a gas pipeline of a fuel fluctuation control system provided in an embodiment of the present invention.

[0026] 101-air duct before air preheater; 102-air preheater; 103-air duct after air preheater; 104-smoke duct before heat exchanger; 105-supplementary air duct; 106-supplementary fan; 107-supply fan; 108-supplementary air branch pipe; 109-flue gas and coal gas heat exchanger; 110-smoke duct after heat exchanger; 111-coal gas pipe before heat exchanger; 112-coal gas pipe after heat exchanger; 113-desulfurization tower; 114-supplement fan inlet silencer; 115-supplement fan inlet regulating damper; 116-supplement fan outlet damper door; 117-supplementary fan inlet silencer; 118-supplementary fan inlet regulating damper; 119-supplementary fan outlet damper door; 120-supplementary air duct isolation door; 121-supplementary branch pipe isolation door;

[0027] 200-gas main pipeline; 210-monitoring point; 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 pipeline; 510-branch flow regulating valve; 520-pressure monitoring device; 530-cut-off valve; 230-electric blind plate valve; 240-hydraulic quick-cut valve. DETAILED DESCRIPTION

[0028] The following is a further detailed description of the gas boiler air supply and smoke temperature control system proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0029] Embodiment 1

[0030] refer to Figure 1 , Figure 1 1 is a structural schematic diagram of a gas boiler air supply and smoke temperature regulation system in an embodiment of the present invention. This embodiment provides a gas boiler air supply and smoke temperature regulation system, comprising: an air preheater front air duct 101 connected to the atmosphere at one end, an air preheater 102 whose air inlet is connected to the other end of the air preheater front air duct 101, an air preheater rear air duct 103 connected to the air outlet of the air preheater 102 at one end and to the furnace at the other end, a heat exchanger front flue 104 connected to the smoke outlet of the air preheater 102 at one end, a supplementary air duct 105 connected to the atmosphere at one end and to the air preheater front air duct 101 at the other end, a supplementary fan 106 arranged on the supplementary air duct 105, and a blower 107 arranged on the air preheater front air duct 101.

[0031] A supplementary air duct 105 is provided, one end of which is connected to the atmosphere and the other end of which is connected to the front air duct 101 of the air preheater. A supplementary fan 106 is provided on the supplementary air duct 105. One end of the front air duct 101 of the air preheater is connected to the atmosphere and the other end is connected to the air inlet of the air preheater 102. Therefore, when the air volume required by the boiler increases, the air volume can be supplemented into the front air duct 101 of the air preheater through the supplementary fan 106 and the supplementary air duct 105, and then the air volume can be supplemented into the air preheater 102 through the air inlet of the air preheater 102, so that the air volume can be supplemented into the furnace through the rear air duct 103 of the air preheater, one end of which is connected to the air outlet of the air preheater 102 and the other end of which is connected to the furnace. Therefore, the working condition that the gas boiler needs a larger air supply volume is adapted, and it is more economical than replacing the air blower 107 and the motor to adapt to the working condition with a larger air supply volume.

[0032] refer to Figure 1 The gas boiler air supply and smoke temperature adjustment system further includes a supplementary air branch pipe 108, one end of which is connected to the supplementary air duct and the other end of which is connected to the air preheater rear air duct 103. By setting the supplementary air branch pipe 108, on the one hand, the air preheater front air duct 101 and the air preheater rear air duct 103 can be connected, so that part of the air volume sent into the air preheater front air duct 101 by the air blower 107 can enter the furnace from the air preheater rear air duct 103, and the air volume supplemented by the supplementary air blower can directly enter the air preheater rear air duct 103 from the supplementary air branch pipe 108, and then enter the furnace, so that different air volumes can be provided for different working conditions, and the temperature of the smoke passing through the air preheater 102 can be adjusted to prevent the temperature of the smoke entering the heat exchanger front smoke duct 104 from being too high or too low.

[0033] refer to Figure 1 The gas boiler air supply and smoke temperature regulation system also includes a flue gas heat exchanger 109, and a heat exchanger rear flue 110, one end of which is connected to the smoke outlet of the flue gas heat exchanger 109 and the other end is connected to the chimney. The other end of the heat exchanger front flue 104 is connected to the smoke inlet of the flue gas heat exchanger 109.

[0034] refer to Figure 1 The gas boiler air supply and smoke temperature regulation system also includes a heat exchanger front gas pipe 111, one end of which is connected to the gas inlet of the flue gas heat exchanger 109 and the other end is connected to the gas pipeline network, and a heat exchanger rear gas pipe 112, one end of which is connected to the gas outlet of the flue gas heat exchanger 109 and the other end is connected to the burner of the boiler.

[0035] refer to Figure 1 The gas boiler air supply and smoke temperature adjustment system also includes a desulfurization tower 113, and the desulfurization tower 113 is arranged on the flue 110 after the heat exchanger.

[0036] refer to Figure 1 The number of the air preheater front air duct 101 and the air preheater rear air duct 103 is two, and the number of the supplementary air duct 105 and the supplementary air branch pipe 108 is one.

[0037] refer to Figure 1 The gas boiler air supply and smoke temperature adjustment system also includes a blower inlet silencer 114, which is arranged on the front air duct 101 of the air preheater and is located between the atmosphere and the blower 107.

[0038] refer to Figure 1 The gas boiler air supply and smoke temperature regulation system also includes a blower inlet regulating damper 115, which is arranged on the air duct 101 before the air preheater and is located between the blower inlet muffler 114 and the blower 107, and is used to adjust the air volume entering the blower 107.

[0039] refer to Figure 1 The gas boiler air supply and smoke temperature regulation system also includes a blower outlet damper door 116, which is arranged on the air duct 101 before the air preheater and is located between the blower 107 and the air preheater, and is used to control the circulation and closing of the air duct 101 before the air preheater.

[0040] refer to Figure 1 The gas boiler air supply and smoke temperature regulation system also includes a supplementary fan inlet silencer 117, which is arranged on the supplementary air duct 105 and located between the atmosphere and the supplementary fan 106.

[0041] refer to Figure 1 The gas boiler air supply and smoke temperature regulation system also includes a supplementary fan inlet regulating damper 118, which is arranged on the supplementary air duct 105 and located between the muffler and the supplementary fan 106, and is used to adjust the air volume entering the supplementary fan 106.

[0042] refer to Figure 1 The gas boiler air supply and smoke temperature regulation system also includes a supplementary fan outlet damper door 119, which is arranged on the supplementary air duct 105 and located between the air preheater 102 and the supplementary fan 106, and is used to control the circulation and closure of the supplementary air duct 105.

[0043] refer to Figure 1The gas boiler air supply and smoke temperature regulation system also includes a supplementary air duct isolation door 120 arranged on the supplementary air duct 105 and located between the supplementary air branch pipe 108 and the air preheater 102.

[0044] refer to Figure 1 The gas boiler air supply and smoke temperature regulation system also includes an air supply branch pipe 108 isolation door 121 arranged on the air supply branch pipe 108.

[0045] The gas boiler air supply and smoke temperature regulation system also includes an air volume controller, which is used to control the opening and closing of the air supply fan 107, the air supply fan outlet damper door 116, the supplementary fan 106 and the supplementary fan outlet damper door 119 according to the fuel operating conditions of the boiler, and control 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 boiler exhaust temperature.

[0046] When the air supply required for boiler fuel combustion 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 the 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 into the boiler furnace. At this time, if the exhaust temperature of the boiler is low, open the supplementary air duct isolation door 120 and the supplementary air branch pipe 108 isolation door 121, and some cold air enters the air preheater front air duct 101 from one end of the air preheater front air duct 101, and then enters the supplementary air duct 105 from the air preheater front air duct 101, and then enters the supplementary air duct 108, and then enters the air preheater rear air duct 103 from the supplementary air branch pipe 108 and flows out to the boiler furnace, and some cold air enters the air preheater 102 from the air preheater front air duct 101 and then enters the air preheater rear air duct 103, and then flows out to the boiler furnace. In this way, it can be avoided that the temperature of the flue gas in the heat exchanger front flue 104 and the heat exchanger rear flue 110 is too low, which causes the sulfur dioxide produced by combustion to easily corrode the heat exchanger rear flue 110 at low temperature and affect the desulfurization effect of the desulfurization tower 113.

[0047] When the air supply volume required for boiler fuel combustion is large, the supplementary fan 106, the supplementary fan outlet damper door 119, and the supplementary air duct isolation door 120 are opened, and the isolation door 121 of the supplementary air branch pipe 108 is closed, and the cold air enters the air preheater 102 from the front air duct 101 of the air preheater and the supplementary air duct 105, and then enters the rear air duct 103 of the air preheater, and then flows out to the boiler furnace. At this time, if the boiler exhaust temperature is low, the supplementary air duct isolation door 120 is closed, and the isolation door 121 of the supplementary air branch pipe 108 is opened, a part of the 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 and then enters the furnace, and a part of the cold air enters the air preheater 102 from the front air duct 101 of the air preheater, and then enters the rear air duct 103 of the air preheater from the air preheater 102, and then flows out to the boiler furnace.

[0048] 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 and coal gas heat exchanger 109, then into the heat exchanger rear flue 110, and finally into the chimney.

[0049] The coal gas may flow from the coal gas network into the coal gas pipe 111 before the heat exchanger, then flow into the flue gas heat exchanger 109, then flow into the coal gas pipe 112 after the heat exchanger, and then flow into the boiler furnace.

[0050] The cold air and the flue gas may be heat exchanged in the air preheater 102 to cool the flue gas for the first time, and the coal gas and the flue gas may be heat exchanged in the flue gas-to-coal gas heat exchanger 109 to cool the flue gas for the second time.

[0051] When the boiler is operated at low load (near 60% of the maximum continuous evaporation of the boiler), the air supply required for the combustion of the boiler fuel is not large and the temperature of the flue gas discharged from the boiler is relatively low. The supplementary fan 106 and the supplementary fan outlet damper 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 air preheater front air duct 101 from one end of the air preheater front air duct 101, and part of it enters the air preheater 102 from the other end of the air preheater front air duct 101, and then flows into the air preheater rear air duct 103, and then flows into the boiler furnace; 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 air preheater rear air duct 103 in sequence. Since part of the cold air does not pass through the air preheater 102, the amount of cold air for heat exchange with the flue gas in 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 about 140°, meeting the reaction temperature required for baking soda dry desulfurization in the desulfurization tower 113, and avoiding the temperature of the flue gas after passing through the gas heat exchanger to be above the dew point temperature, causing low-temperature corrosion and affecting the service life of the flue gas gas heat exchanger 109.

[0052] When the boiler is running under high load (near 100% of the maximum continuous evaporation of the boiler), if the air supply required for the combustion of the boiler fuel is not large and the exhaust temperature of the boiler is high, the supplementary fan 106, the supplementary fan outlet damper door 119, 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 can be closed. The cold air enters the air preheater front air duct 101 from one end of the air preheater front air duct 101, and all enters the air preheater 102 from the other end of the air preheater front air duct 101, flows through the air preheater 102, and then flows into the air preheater rear air duct 103, and then flows into the boiler furnace. Since 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 large extent, thereby improving the boiler efficiency. When the air supply volume required for boiler fuel combustion is large and the boiler exhaust temperature is high, the supplementary fan 106, the supplementary fan outlet damper door 119, and the supplementary air duct isolation door 120 on the supplementary air duct 105 can be opened, and the supplementary air branch pipe 108 isolation door 121 on the supplementary air branch pipe 108 is closed, and the 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 enters the air preheater 102 from the other end of the air preheater front air duct 101, flows through the air preheater 102, and then flows into the air preheater rear air duct 103, and then flows into the boiler furnace. Since 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 large extent, thereby improving the boiler efficiency.

[0053] When the boiler is operating in a low temperature environment, such as in a northern winter environment, the temperature of the coal gas entering the flue gas heat exchanger 109 from the front gas pipe of the flue gas heat exchanger 109 is relatively low, resulting in a relatively low temperature of the flue gas entering the flue 110 after passing through the flue gas heat exchanger 109. At this time, if the air supply required for boiler fuel combustion is not large, close the supplementary fan 106 and the supplementary fan outlet baffle door 119, and open 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. The cold air enters the air preheater front air duct 101 from one end of the air preheater front air duct 101, and part of it enters the air preheater 102 from the other end of the air preheater front air duct 101, and then flows into the air preheater rear air duct 103, and then flows into the boiler furnace; 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 air preheater rear air duct 103. 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 coal gas heat exchanger can be maintained at a higher temperature.

[0054] Embodiment 2

[0055] refer to Figure 2 , Figure 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:

[0056] Step S100, calculating the oxygen setting value according to the boiler load;

[0057] Step S200, comparing the oxygen setting value and the obtained oxygen measurement value through the oxygen regulator to obtain the oxygen deviation value;

[0058] Step S300, calculating a preset air volume value according to the boiler load;

[0059] Step S400, calculating the air volume setting value according to the oxygen content deviation value and the air volume preset value;

[0060] Step S500, comparing the air volume setting value and the obtained air volume measurement value through the air volume regulator to obtain the air volume deviation value;

[0061] Step S600, controlling the air volume of the blower according to the air volume deviation value.

[0062] In step S100 and step S300, the boiler load is the amount of steam generated per unit time. For example, the boiler steam is used to drive the steam turbine, and the steam turbine is used to do external work. When the boiler is doing work, the more work it does per unit time, the greater the boiler load, and vice versa.

[0063] In step S200, the oxygen content measurement value is the average value of the valid oxygen content values ​​obtained at multiple measurement points. For example, if there are five measurement points and the oxygen content value measured at one measurement point is obviously wrong, the oxygen content value measured at the measurement point is deleted, and the oxygen content values ​​measured at the remaining four measurement points are averaged to obtain the oxygen content measurement value.

[0064] In step S200, when the oxygen content setting value is compared with the obtained oxygen content measurement value, if the oxygen content measurement value is less than the oxygen content setting value, the output air volume deviation value is a positive number, and if the oxygen content measurement value is greater than the oxygen content setting value, the output air volume deviation value is a negative number.

[0065] Between step S100 and step S200, step S700 is also included to manually correct the oxygen volume setting value. By manually correcting the oxygen volume setting value, the accuracy of the air volume control of the blower can be further improved.

[0066] 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 a negative number, the air volume preset value is less than the air volume setting value. If the air volume deviation value is a positive number, the air volume preset value is greater than the air volume setting value.

[0067] In step S500, the air volume setting value and the obtained air volume measurement value are compared by the air volume regulator to obtain the air volume deviation value, which is the air volume measurement value minus the air volume setting value. When the air volume deviation value is a positive number, the air supply volume decreases, and when the air volume deviation value is a negative number, the air supply volume increases.

[0068] 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.

[0069] Step S600 also includes calculating the real-time air supply volume, wherein when the air supply volume is greater than a preset value, the supplementary fan is controlled to be turned off, and when the air supply volume is less than the preset value, the supplementary fan is controlled to be turned on, and the power of the air supply fan is adjusted at the same time.

[0070] Also included between step S500 and step S600 is step S800, in which the boiler main control feedforward is used to sum the air volume deviation value to obtain the corrected air volume deviation value. The boiler main control feedforward is a feedforward air volume value calculated based on the gas fluctuation. When the current feed air volume value increases, the amount of fuel increases, the larger the air volume deviation value is, the larger the required air supply volume is; when the current feed air volume value decreases, the amount of fuel decreases, the smaller the air volume deviation value is, the smaller the required air supply volume is. In other words, the gas fluctuation affects the size of the air volume deviation value in real time. Therefore, if the air supply volume is to be accurately controlled in real time, the control of the gas fluctuation is also critical.

[0071] Embodiment 3

[0072] In this embodiment, the smaller the gas fluctuation is, the more beneficial it is to the air volume control. Based on this, this embodiment provides a fuel fluctuation control method, which is:

[0073] A monitoring position 210 and a regulating position are set on the 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 flow direction. The regulating position is located downstream of the monitoring position 210 and is provided with a main flow regulating valve 220.

[0074] The gas pressure is monitored by each pressure monitoring unit 211 at the monitoring position 210, and the change ΔQ of the gas heat supply caused by the gas fluctuation is calculated based on the monitored gas pressure fluctuation. 煤气 ; Calculate the time t1 required for the gas to run from the monitoring position 210 to the regulating position;

[0075] If ΔQ 煤气 >0, after time t1, the opening of the main flow regulating valve 220 is reduced to improve the stability of the main steam parameters of the gas boiler;

[0076] If ΔQ 煤气 <0, after time t1, the opening of the main flow regulating valve 220 is increased to improve the stability of the main steam parameters of the gas boiler;

[0077] If ΔQ 煤气 =0, keeping the opening of the main flow regulating valve 220 unchanged.

[0078] The monitoring position 210 is a section, that is, has a certain pipeline axial length, such as a monitoring section of the gas main pipeline 200, which is convenient for the arrangement of monitoring equipment.

[0079] The number of gas pressure measuring points (i.e., pressure monitoring units 211) is preferably 3 or more to ensure the accuracy and reliability of pressure monitoring. The distance between two adjacent gas pressure measuring points is preferably within the range of 1 to 20 m, and more preferably within the range of 5 to 15 m.

[0080] In one embodiment, the gas heat supply is calculated using the following formula:

[0081] Q 煤气 =qm 气

[0082] Wherein, 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 气 is the gas flow rate, m 气 It can be obtained by monitoring the gas pressure.

[0083] Correspondingly, a gas calorific value meter 212 is also provided at the monitoring position 210, which can monitor the calorific value of the gas online. The gas calorific value meter 212 can be arranged on the same cross-section of the gas main pipeline 200 relative to one of the pressure monitoring units 211, or can be arranged between two adjacent pressure monitoring units 211, or can be arranged downstream of each pressure monitoring unit 211.

[0084] In actual operation, the fluctuation of the calorific value of coal gas is relatively small. Therefore, in this embodiment, the impact of the fluctuation of coal gas flow on the operation of the boiler is mainly considered.

[0085] There is a certain distance between the monitoring position 210 and the regulating position to ensure that corresponding processing can be carried out in advance when the gas fluctuates. In one embodiment, the distance between the monitoring position 210 and the regulating position is more than 20m, for example, controlled within the range of 20 to 100m.

[0086] There is a certain distance between the adjustment position and the boiler burner 300, and the distance is preferably greater than 20m, for example, in the range of 20 to 100mm.

[0087] Furthermore, when calculating the time t1 required for the gas to run from the monitoring position 210 to the regulating position, the location of the gas pressure measuring point at the center position or the center position of the monitoring position 210 is used as the starting operation position of the gas, and the gas flow rate can be calculated based on the gas pressure monitored at the starting operation position and combined with the pipe diameter, etc.

[0088] Furthermore, when calculating ΔQ 煤气When calculating the pressure difference between two adjacent gas pressure measuring points, the gas pressure fluctuation amount is first obtained. Specifically, the pressure difference between each adjacent gas pressure measuring point is calculated, and the average value of each pressure difference is taken as the gas pressure fluctuation amount. When calculating the pressure difference between each adjacent gas pressure measuring point, it is preferred that the monitoring data of the downstream gas pressure measuring point is subtracted from the monitoring data of the upstream gas pressure measuring point. Since gas fluctuation is generally a creeping process rather than a sudden change process, the above calculation method can ensure the accuracy and reliability of the monitoring results.

[0089] The main flow regulating valve 220 is an automatic valve, and a flow regulating valve such as an electric butterfly valve can be used.

[0090] Further preferably, when adjusting the opening of the main flow regulating valve 220, the adjustment goal is to control the fluctuation range of the boiler midpoint temperature within 0-10°C, which can achieve the above-mentioned effect of improving the stability of the main steam parameters of the gas boiler.

[0091] In the case where the gas calorific value does not fluctuate much, preferably, for every 1 KPa drop or rise in the gas pressure, the opening of the main flow regulating valve 220 correspondingly increases or decreases by 1% to 10%.

[0092] Further preferably, the above control method further includes:

[0093] When the main flow regulating valve 220 is adjusted to the maximum opening and still cannot reach the control target, the main feed water flow of the boiler is further adjusted to reach the control target. Among them, the main feed water flow of the boiler is further adjusted after the flow regulating valve is opened to the maximum opening.

[0094] When the boiler is running, in order to ensure the stability of the main steam parameters, the fuel and feed water should meet the following relationship:

[0095] Q 水 =ηQ 煤气

[0096] Among them, Qwater is the heat absorbed by the feed water heat exchange; η is the boiler thermal efficiency.

[0097] Q 水 =m 水 (h out -h in )

[0098] Among them, m 水 is the main feed water flow rate of the boiler; h out is the specific enthalpy of feed water after heat exchange, h in is the specific enthalpy of feed water before heat exchange. out and h inThe table operation is generally referred to in the current engineering "Handbook of Thermodynamic Properties of Water and Steam"; the parameters of the boiler main feed water and main steam are applicable to the "Water and Superheated Steam Table" in the manual. Specifically, according to the temperature and pressure parameters of the boiler main feed water, the "Water and Superheated Steam Table" can be queried to obtain the specific enthalpy value h of the boiler main feed water. in According to the temperature and pressure parameters of the boiler main steam, query the "water and superheated steam table" to obtain the specific enthalpy value h of the boiler main steam out .

[0099] Therefore, the calculation formula for the boiler main feed water flow is:

[0100]

[0101] Although the boiler thermal efficiency η is different under different loads, since the fluctuation of coal gas is generally a continuous process, the boiler thermal efficiency η will not change suddenly, so it can be approximately considered that the boiler thermal efficiency η at two adjacent monitoring moments remains unchanged. However, preferably, after each adjustment of the opening of the main flow control valve 22012, the boiler thermal efficiency η is recalculated, and the specific calculation method is a conventional technology in the field and is not described here.

[0102] Accordingly, the adjustment amount of the boiler main feed water flow is calculated according to the following formula:

[0103]

[0104] Where η is the thermal efficiency of the boiler, h out is the specific enthalpy of feed water after heat exchange, h in is the specific enthalpy of feed water before heat exchange.

[0105] According to the above calculation results, the frequency converter 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 the main feed water flow of the boiler is equal to Δm 水 This is obviously an ideal regulation target, but considering the actual operating conditions, the regulation amount of the boiler main feed water flow is close to this Δm 水 It is considered reasonable, and the specific difference should meet the requirement of ensuring that the fluctuation range of the boiler mid-point temperature is between 0 and 10°C.

[0106] Furthermore, the method further comprises:

[0107] 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 feed water pump to the boiler water wall,

[0108] If t2>t3, the main feed water flow of the boiler is adjusted with a lag time of t2-t3. Alternatively, external gas is added to the main gas pipeline 200 to improve the stability of the main steam parameters of the gas boiler, wherein the external gas addition point is located downstream of the monitoring position 210, and can be located upstream or downstream of the adjustment position. The time when the external gas reaches the boiler burner 300 is preferably the same as t3. When the gas fluctuation signal is monitored, the external gas is added, and the ventilation time of the external gas is t2-t3. Among them, a gas storage bypass 400 can be connected to the main gas pipeline 200, and the gas storage bypass 400 is connected to the external gas source 410, and a bypass regulating valve 420 and a quick-cut valve 430 are set on the gas storage bypass 400, and the flow rate of the external gas is controlled by the bypass regulating valve 420.

[0109] If t2<t3, before the boiler main feed water flow is adjusted to the right position, the opening of the branch pipe flow regulating valve 510 on the gas branch pipe 500 at the inlet side of the boiler burner 300 is reduced to improve the stability of the main steam parameters of the gas boiler. Furthermore, when time t3 is reached, the opening of the branch pipe flow regulating valve 510 is reset to the position before the gas fluctuation to further improve the stability of the subsequent boiler operation.

[0110] Based on the above scheme, the time for gas fluctuations to reach the boiler burner 300 and the time for feed water to reach the boiler water-cooled wall are fully considered to ensure the reliability of the adjustment operation, which can further improve the operating stability of the gas boiler and ensure that the main steam parameters under various operating conditions can be controlled within the target range.

[0111] The gas transported by the main gas pipeline 200 is preferably steel plant gas, such as blast furnace gas, etc. The main steam parameters are preferably a pressure of not less than 22.12Mpa and a temperature of not less than 540°C. The supercritical gas boiler can be applied to supercritical gas generator sets, ultra-supercritical gas generator sets, etc.

[0112] Although the fluctuation of coal gas can be reduced by the fuel fluctuation control method to reduce the regulation of air volume, the fluctuation of coal gas is still unavoidable. Therefore, it is necessary to provide a gas boiler air volume control method in Example 2 to regulate the air volume of the blower and the supplementary blower.

[0113] Embodiment 4:

[0114] An embodiment of the present invention provides a fuel fluctuation control system, including a gas main pipeline 200 and a plurality of gas branch pipelines 500 connected one-to-one to each boiler burner 300, wherein a monitoring position 210 and an adjustment position are provided on the gas main pipeline 200, wherein a gas calorific value meter 212 and a plurality of pressure monitoring units 211 distributed in sequence along the gas flow direction are provided at the monitoring position 210, and the adjustment position is located downstream of the monitoring position 210 and is provided with a main flow regulating valve 220.

[0115] The pressure monitoring unit 211 may be a pressure measuring device such as a pressure transmitter.

[0116] There is a certain distance between the monitoring position 210 and the regulating position to ensure that corresponding processing can be carried out in advance when the gas fluctuates. In one embodiment, the distance between the monitoring position 210 and the regulating position is more than 20m, for example, controlled within the range of 20 to 100m.

[0117] There is a certain distance between the adjustment position and the boiler burner 300, and the distance is preferably greater than 20 m, for example, in the range of 20 to 100 m.

[0118] The monitoring position 210 is a section, that is, it has a certain axial length of the pipeline, for example, a monitoring section of the main gas pipeline 2001, which is convenient for the arrangement of the monitoring equipment.

[0119] The number of gas pressure measuring points (i.e., pressure monitoring units 211) is preferably 3 or more to ensure the accuracy and reliability of pressure monitoring. The distance between two adjacent gas pressure measuring points is preferably within the range of 1 to 20 m, and more preferably within the range of 5 to 15 m.

[0120] The gas calorific value meter 212 may be arranged on the same cross section of the gas main pipeline 200 opposite to one of the pressure monitoring units 211 , or may be arranged between two adjacent pressure monitoring units 211 , or may be arranged downstream of each pressure monitoring unit 211 .

[0121] The main flow regulating valve 220 is an automatic valve, and a flow regulating valve such as an electric butterfly valve can be used.

[0122] Furthermore, the system further comprises a main controller and a comparator, wherein the main controller is used for:

[0123] Acquire the monitoring data of the gas calorific value meter 212 and the monitoring data of each of the pressure monitoring units 211;

[0124] and sending the monitoring data of each pressure monitoring unit 211 to a comparator for comparison, and obtaining a comparison result of the comparator;

[0125] And the change ΔQ of the gas heat supply caused by the gas fluctuation is calculated according to the comparison result. 煤气 , and controls the opening of the main flow control valve 220 according to a predetermined strategy.

[0126] Further, the predetermined strategy may refer to the relevant content in the above-mentioned embodiment 3, for example, the predetermined strategy includes:

[0127] If ΔQ煤气 >0, after time t1, the opening of the main flow regulating valve 220 is reduced to improve the stability of the main steam parameters of the gas boiler;

[0128] If ΔQ 煤气 <0, after time t1, the opening of the main flow regulating valve 220 is increased to improve the stability of the main steam parameters of the gas boiler;

[0129] If ΔQ 煤气 =0, keeping the opening of the main flow regulating valve 220 unchanged.

[0130] Furthermore, the main controller is also used to adjust the frequency of the inverter of the main water supply pump so that the gas volume supplied matches the main water supply flow rate. For related content, please refer to the above embodiment 3, which will not be repeated here.

[0131] Furthermore, if Figure 3 , Figure 3 The schematic diagram of the gas pipeline of the fuel fluctuation control system provided by the embodiment of the present invention is shown in the figure. The gas branch pipeline 500 is provided with a branch flow regulating valve 510. A pressure monitoring device 520 can be further provided on the gas branch pipeline 500. The branch 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 also provided on the gas branch pipeline 500. For example, a hydraulic shut-off valve 530 is used to further improve the reliability of the system operation.

[0132] Furthermore, if Figure 3 The gas main pipeline 200 is connected to a gas storage bypass 400, and the gas storage bypass 400 is connected to an external gas source 410. The gas storage bypass 400 is provided with a bypass regulating valve 420 and a shut-off valve 530. The external gas source 410 can be an external gas storage tank, etc. The external gas can be the same type of gas as the gas supplied by the gas main pipeline 200, for example, both are blast furnace gas, and the external gas storage tank can be filled in advance at the initial stage of operation. The bypass point of the gas storage bypass 400 is preferably located downstream of the monitoring position 210, and can be located upstream or downstream of the regulating position.

[0133] The above main controller is also used to:

[0134] 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 feed water pump to the boiler water wall; send t2 and t3 to the comparator for comparison and obtain the comparison result of the comparator; and execute the setting strategy according to the comparison result. The above setting strategy can refer to the relevant content in Example 3.

[0135] In addition, if Figure 3Preferably, a heat exchanger is also provided at the tail end of the main gas pipeline 200. The heat exchanger is preferably a flue gas heat exchanger 109, which can utilize the waste heat of the flue gas discharged by the boiler to improve the combustion effect of the gas.

[0136] Alternatively, if Figure 3 An electric blind plate valve 230 and a hydraulic quick-cut valve 240 are also provided on the gas main pipeline 200, which can further improve the reliability of system operation.

[0137] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A method for controlling the air volume of a gas boiler, characterized in that: include: Step S100, calculating the oxygen setting value according to the boiler load; Step S200, comparing the oxygen setting value and the obtained oxygen measurement value through the oxygen regulator to obtain the oxygen deviation value; Step S300, calculating a preset air volume value according to the boiler load; Step S400, calculating the air volume setting value according to the oxygen content deviation value and the air volume preset value; Step S500, comparing the air volume setting value and the obtained air volume measurement value through the air volume regulator to obtain the air volume deviation value; Step S600, controlling the air volume of the blower according to the air volume deviation value; Also included between step S500 and step S600 is step S800, which sums the air volume deviation values ​​of the boiler master control feedforward to obtain a corrected air volume deviation value; The invention also includes a fuel fluctuation control method for adjusting the boiler main control feedforward, the fuel fluctuation control method comprising: A monitoring position and a regulating position are arranged on the main gas pipeline of the boiler, a plurality of pressure monitoring units are arranged in sequence at the monitoring position along the gas flow direction, and the regulating 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 ΔQ gas of the gas heat supply caused by the gas fluctuation is calculated based on the monitored gas pressure fluctuation; Calculate the time t1 required for the gas to run from the monitoring position to the regulating position; If ΔQ 煤气 >0, after time t1, the main flow regulating valve opening is reduced to improve the stability of the main steam parameters of the gas boiler; If ΔQ 煤气 <0, after time t1, the main flow regulating valve opening is increased to improve the stability of the main steam parameters of the gas boiler; If ΔQ 煤气 =0, keeping the opening of the main flow regulating valve unchanged.

2. The gas boiler air volume control method according to claim 1, characterized in that: In step S200 , the oxygen content measurement value is an average value of valid oxygen content values ​​obtained at a plurality of measurement points.

3. The gas boiler air volume control method according to claim 1, characterized in that: In step S200, when the oxygen content setting value is compared with the obtained oxygen content measurement value, if the oxygen content measurement value is less than the oxygen content setting value, the output air volume deviation value is a positive number, and if the oxygen content measurement value is greater than the oxygen content setting value, the output air volume deviation value is a negative number.

4. The gas boiler air volume control method according to claim 1, characterized in that: 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 a negative number, the air volume preset value is less than the air volume setting value. If the air volume deviation value is a positive number, the air volume preset value is greater than the air volume setting value.

5. The gas boiler air volume control method according to claim 1, characterized in that: In step S500, the air volume setting value and the obtained air volume measurement value are compared by the air volume regulator to obtain the air volume deviation value, which is the air volume measurement value minus the air volume setting value. When the air volume deviation value is a positive number, the air supply volume decreases, and when the air volume deviation value is a negative number, the air supply volume increases.

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 a preset value, the supplementary fan is controlled to be turned off, and when the air supply volume is less than the preset value, the supplementary fan is controlled to be turned on, and the power of the air supply fan is adjusted at the same time.

7. The gas boiler air volume control method according to claim 1, characterized in that: Also includes: When the main flow regulating valve is adjusted to the maximum opening and still cannot reach the control target, the main feed water flow of the boiler is further adjusted to reach the control target.

8. The gas boiler air volume control method according to claim 7, characterized in that: The adjustment amount of the boiler main feed water flow is calculated according to the following formula: Where η is the thermal efficiency of the boiler, h out is the specific enthalpy of feed water after heat exchange, h in is the specific enthalpy of feed water before heat exchange.

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