CN115418425B - Stable operation control method of multi-unit supercritical gas power generation system - Google Patents
Stable operation control method of multi-unit supercritical gas power generation system Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B5/00—Making pig-iron in the blast furnace
- C21B5/06—Making pig-iron in the blast furnace using top gas in the blast furnace process
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17D—PIPE-LINE SYSTEMS; PIPE-LINES
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17D—PIPE-LINE SYSTEMS; PIPE-LINES
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Abstract
The invention relates to a stable operation control method of a multi-unit supercritical gas power generation system, which is provided with a gas main pipeline and a plurality of gas boilers, wherein each gas boiler is provided with a gas supply pipe, and each gas supply pipe is connected with the gas main pipeline; the method comprises the following steps: setting a part of the gas supply pipes as constant supply pipes and the rest gas supply pipes as variable supply pipes; when the gas flow in the main gas pipeline fluctuates, the gas flow stability of the constant supply pipe is ensured, and the gas flow stability of the outlet of the variable supply pipe is improved by adopting the regulating measure so as to improve the stability of main steam parameters of the corresponding gas boiler. In the invention, the gas flow of the gas supply pipe of part of the gas boilers is always kept stable in the operation process, and the gas fluctuation is resolved by the other gas boilers, so that the system adjusting action is obviously reduced, the system disturbance caused by the gas fluctuation in the operation process is reduced, and the system operation stability is improved.
Description
Technical Field
The invention belongs to the technical field of gas power generation, and particularly relates to a stable operation control method of a multi-unit supercritical gas power generation system.
Background
The low-heat-value gas power generation industry of steel mills is subjected to medium-temperature medium-pressure, high-temperature high-pressure, high-temperature ultrahigh-pressure, subcritical and supercritical five-generation technology alternation. Before subcritical technology, gas boilers are drum boilers; whereas for supercritical technology, the boiler is of the once-through furnace type.
The amount of gas in the steel mill is always in an unstable fluctuation state, and in the operation of the gas boiler, the matching adjustment of fuel and water supply amount is very important, and the safe operation of the boiler is directly influenced. At present, in subcritical and below parameter gas generator sets, boiler fuel and water supply quantity control can be indirectly controlled through intermediate quantity drum water level, but a supercritical once-through furnace does not have a drum, gas fluctuation easily causes fluctuation of main steam parameters of the boiler, and main water supply flow is generally required to be adjusted to match gas flow. For a multi-unit supercritical gas power generation system, the gas flow is generally equally divided, the gas fluctuation of each unit needs to be controlled respectively, so that the operation parameters of all gas boilers need to be adjusted, the system operation disturbance is large, and the stability is poor.
Disclosure of Invention
The invention relates to a stable operation control method of a multi-unit supercritical gas power generation system, which at least can solve part of defects in the prior art.
The invention relates to a stable operation control method of a multi-unit supercritical gas power generation system, which is provided with a gas main pipeline and a plurality of gas boilers, wherein each gas boiler is provided with a gas supply pipe, and each gas supply pipe is connected with the gas main pipeline;
the method comprises the following steps:
setting a part of the gas supply pipes as constant supply pipes and the rest gas supply pipes as variable supply pipes;
when the gas flow in the main gas pipeline fluctuates, the gas flow stability of the constant supply pipe is ensured, and the gas flow stability of the outlet of the variable supply pipe is improved by adopting the regulating measure so as to improve the stability of main steam parameters of the corresponding gas boiler.
As one of the embodiments, a first monitoring position is arranged on the main gas pipeline, and a plurality of first pressure monitoring units are sequentially arranged at the first monitoring position along the gas flowing direction; setting a regulating position on the variable supply pipe, wherein a main flow regulating valve is arranged at the regulating position;
the adjusting measures comprise:
monitoring the gas pressure by each first pressure monitoring unit at the first monitoring position, and calculating the variation delta Q of the gas heat supply quantity in each variable supply pipe caused by the gas fluctuation based on the monitored gas pressure fluctuation and the gas flow required by each constant supply pipe Gas (gas) The method comprises the steps of carrying out a first treatment on the surface of the Calculating time t1 required by the gas to run from the first monitoring position to the adjusting position;
if DeltaQ Gas (gas) Reducing the opening of the main flow regulating valve after time t1 to improve the stability of main steam parameters of the corresponding gas boiler;
if DeltaQ Gas (gas) After the time t1, the opening of the main flow regulating valve is increased to improve the stability of main steam parameters of the corresponding gas boiler;
if DeltaQ Gas (gas) =0, keeping the main flow regulating valve opening unchanged.
As one embodiment, the adjusting means further includes:
when the maximum opening degree of the main flow regulating valve still cannot reach the control target, the main water supply flow of the corresponding gas boiler is further regulated to reach the control target.
As one embodiment, the adjustment amount of the main water supply flow of the boiler is calculated as follows:
wherein eta is the thermal efficiency of the boiler, h out To the specific enthalpy value after heat exchange of the water supply, h in Is the specific enthalpy value before heat exchange of the feed water.
As one embodiment, the adjusting means further includes:
the time t2 required by the gas to be transmitted from the first monitoring position to the boiler burner of the corresponding gas boiler and the time t3 required by the water supply to be transmitted from the water supply pump to the boiler water wall are obtained,
if t2 is more than t3, the main water supply flow of the boiler is regulated in a lagging way, and the lagging time is t2-t3; or the exogenous gas is supplemented into the variable supply pipe so as to improve the stability of the main steam parameters of the corresponding gas boiler;
if t2 is less than t3, before the main water supply flow of the boiler is regulated in place, reducing the opening of a branch pipe flow regulating valve on a combustor air inlet pipe at the inlet side of each boiler combustor so as to improve the stability of main steam parameters of the corresponding gas boiler.
As one of the embodiments, a gas storage device and a main flow regulating valve are arranged on the variable supply pipe, and the main flow regulating valve is positioned at the downstream of the gas storage device.
As one embodiment, the adjusting means includes:
when the pressure fluctuation of the gas in the main gas pipeline is within a set fluctuation range, the upstream gas firstly enters the gas storage device for caching, and the gas storage device supplies the gas to the corresponding gas boiler so as to realize primary buffering of the gas fluctuation;
when the fluctuation of the gas pressure in the main gas pipeline exceeds a set fluctuation range and/or the fluctuation of the gas heat value at the outlet side of the gas storage device, the main flow regulating valve is used for regulating the gas flow on the basis of primary buffering of the gas storage device, so that the secondary regulation of the gas fluctuation is realized.
As one embodiment, the adjusting means includes:
a second monitoring position is arranged on the variable supply pipe, the second monitoring position is positioned between the gas storage device and the main flow regulating valve, and a gas heat value monitoring unit and a plurality of second pressure monitoring units which are sequentially arranged along the gas flowing direction are arranged at the second monitoring position;
monitoring the gas pressure by each second pressure monitoring unit at the second monitoring position, and calculating the variation delta Q of the gas heat supply quantity caused by the gas fluctuation based on the monitored gas pressure fluctuation Gas (gas) The method comprises the steps of carrying out a first treatment on the surface of the Calculating the time t4 required for the gas to run from the second monitoring position to the main flow regulating valve;
if DeltaQ Gas (gas) Reducing the opening of the main flow regulating valve after time t4 to improve the stability of main steam parameters of the corresponding gas boiler;
if DeltaQ Gas (gas) After time t4, increasing the opening of the main flow regulating valve to improve the stability of main steam parameters of the corresponding gas boiler;
if DeltaQ Gas (gas) =0, keeping the main flow regulating valve opening unchanged.
As one embodiment, a bypass pipe is provided on the variable supply pipe, both ends of the bypass pipe are connected to the upstream and downstream of the gas storage device, respectively, and a bypass valve is provided on the bypass pipe.
As one embodiment, the adjusting means includes:
monitoring the fluctuation of the gas pressure in the gas main pipeline, and when the fluctuation of the gas pressure in the gas main pipeline does not occur or the fluctuation of the gas pressure of the gas main pipeline is within the allowable fluctuation range, directly running upstream gas through the bypass pipe; when the fluctuation of the gas pressure exceeds the allowable fluctuation range, the upstream gas enters the gas storage device;
and/or a bypass flow regulating valve is arranged on the bypass pipe, a stable flow is set through the bypass pipe, when the pressure of the coal gas in the coal gas main pipeline positively fluctuates, the bypass pipe keeps normal coal gas flow, and redundant coal gas enters the coal gas storage device; when the pressure of the coal gas in the main coal gas pipeline fluctuates negatively, the coal gas circulates through the bypass pipe and the fluctuation is supplemented through the coal gas storage device.
The invention has at least the following beneficial effects: in the invention, the gas flow of the gas supply pipe of part of the gas boilers is always kept stable in the operation process, and the gas fluctuation is resolved by the other gas boilers, so that the system adjusting action is obviously reduced, the system disturbance caused by the gas fluctuation in the operation process is reduced, and the system operation stability is improved.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 and fig. 2 are schematic structural diagrams of two multi-unit supercritical gas power generation systems according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
As shown in fig. 1 and 2, an embodiment of the present invention provides a stable operation control method of a multi-unit supercritical gas power generation system, which has a main gas pipe 1 and a plurality of gas boilers, each configured with a gas supply pipe, and each connected to the main gas pipe 1.
The method comprises the following steps:
setting a part of the gas supply pipes as constant supply pipes 21 and the other gas supply pipes as variable supply pipes 22;
when the gas flow in the main gas pipeline 1 fluctuates, the gas flow stability of the constant supply pipe 21 is ensured, and the gas flow stability of the outlet of the variable supply pipe 22 is improved by adopting the regulating measure so as to improve the stability of the main steam parameters of the corresponding gas boiler.
In the embodiment, the gas supply pipe of part of the gas boilers always keeps stable gas flow in the operation process, and the gas fluctuation is resolved by the other gas boilers, so that the system adjusting action is obviously reduced, the system disturbance caused by the gas fluctuation in the operation process is reduced, and the system operation stability is improved.
The main gas pipe 1 is preferably used for transporting steel mill gas, such as blast furnace gas, etc. The main steam parameter is preferably pressure not lower than 22.12Mpa and temperature not lower than 540 ℃, and the supercritical gas boiler can be applied to supercritical gas generator sets, ultra supercritical gas generator sets and the like.
In addition, each gas boiler is provided with a plurality of boiler burners 5, each boiler burner 5 is provided with a burner gas inlet pipe 4, and each burner gas inlet pipe 4 is connected with a corresponding gas supply pipe; further, as shown in fig. 1 and 2, a branch flow rate adjusting valve 41 is provided on the burner intake pipe 4, and a pressure monitoring device 42 may be further provided on the burner intake pipe 4. In addition, the shutoff valve 43 is provided in the burner intake pipe 4, and for example, a hydraulic shutoff valve is used, so that the reliability of the system operation can be further improved.
In addition, as shown in fig. 1 and 2, a heat exchanger 26 is preferably further arranged at the tail end of the gas supply pipe, and the heat exchanger 26 is preferably a flue gas-gas indirect heat exchanger 26, so that the waste heat of flue gas discharged by the boiler can be utilized to improve the combustion effect of the gas.
Optionally, as shown in fig. 1 and 2, an electric blind plate valve 24 and a hydraulic quick-cutting valve 25 are further arranged on the gas supply pipe, so that the running reliability of the system can be further improved.
Example two
The present embodiment optimizes the steady operation control method in the first embodiment described above.
As shown in fig. 1, a first monitoring position 11 is provided on the main gas pipe 1, and a plurality of first pressure monitoring units 111 are sequentially provided at the first monitoring position 11 along the gas flowing direction; a regulating position is arranged on the variable supply pipe 22, and a main flow regulating valve 23 is arranged at the regulating position;
the adjusting measures comprise:
the gas pressure is monitored by each first pressure monitoring unit 111 at the first monitoring position 11, and the variation delta Q of the gas heat supply quantity in each variable supply pipe 22 caused by the gas fluctuation is calculated based on the monitored gas pressure fluctuation and the gas flow quantity required by each constant supply pipe 21 Gas (gas) The method comprises the steps of carrying out a first treatment on the surface of the Calculating the time t1 required for the gas to run from the first monitoring position 11 to the regulating position;
if DeltaQ Gas (gas) Reducing the opening of the main flow regulating valve 23 after the time t1 to improve the stability of main steam parameters of the corresponding gas boiler;
if DeltaQ Gas (gas) After the time t1, the opening of the main flow regulating valve 23 is increased to improve the stability of main steam parameters of the corresponding gas boiler;
if DeltaQ Gas (gas) =0, keeping the main flow regulating valve 23 opening unchanged.
The first monitoring position 11 is a section, i.e. a monitoring section with a certain axial length of the pipeline, such as the main gas pipeline 1, which is convenient for the arrangement of monitoring equipment.
The number of the gas pressure measuring points (i.e. the first pressure monitoring units 111) is preferably 3 or more, so as to ensure the accuracy and reliability of pressure monitoring. The distance between two adjacent gas pressure measuring points is preferably in the range of 1-20 m, and more preferably in the range of 5-15 m.
In one embodiment, the gas heat supply is calculated using the following formula:
Q gas (gas) ＝qm Air flow
Wherein q is the calorific value of the gas, and the real-time monitoring can be carried out by arranging a calorific value meter on the pipeline; m is m Air flow Is the gas flow, m Air flow Can be obtained by monitoring the conversion of the gas pressure.
Correspondingly, the first monitoring position 11 is further provided with a gas heat value meter 112, so that the gas heat value can be monitored on line, and the gas heat value meter 112 and one of the first pressure monitoring units 111 can be arranged on the same section of the gas main pipeline 1 oppositely, can be arranged between two adjacent first pressure monitoring units 111, or can be arranged downstream of each first pressure monitoring unit 111. In actual operation, the fluctuation of the gas heat value is small, so in the embodiment, the influence of the fluctuation of the gas flow on the operation of the boiler is mainly considered.
The first monitoring position 11 is at a certain distance from the regulating position, so that corresponding treatment can be performed in advance when the gas fluctuates. In one embodiment, the distance between the first monitoring bit 11 and the adjustment bit is above 20m, for example controlled in the range of 20-100 m.
The adjustment position is at a distance from the corresponding boiler burner 5, which distance is also preferably above 20m, for example in the range of 20-100 mm.
In the present embodiment, when there are a plurality of variable supply pipes 22, each variable supply pipe 22 preferably performs gas flow sharing, that is, the total gas flow of the gas main pipe 1 minus the gas flow required by each constant supply pipe 21, and the remaining gas flow is equally distributed to each variable supply pipe 22.
Further, when calculating the time t1 required for the gas to run from the first monitoring position 11 to the adjusting position, the gas running time in the gas main pipe 1 and the gas running time in the variable supply pipe 22 can be calculated respectively by taking the position of the gas pressure measuring point in the central position or the central position of the first monitoring position 11 as the initial running position of the gas, and can be calculated according to the gas flow rate/gas pressure in the gas main pipe 1 and the gas flow rate/gas pressure in the variable supply pipe 22, the combined pipe diameter and the like.
Further, when Δq is calculated Gas (gas) In the time-course of which the first and second contact surfaces,firstly, the fluctuation amount of the gas pressure in the gas main pipeline 1 is obtained, and then the fluctuation amount is divided by the number of variable supply pipes 22; specifically, the pressure difference between every two adjacent gas pressure measuring points is calculated, and the average value of the pressure differences is taken as the fluctuation amount of the gas pressure. In calculating the pressure difference between every two adjacent gas pressure measurement points, it is preferable that the monitoring data of the downstream gas pressure measurement point minus the monitoring data of the upstream gas pressure measurement point. Because the gas fluctuation is generally a creep process, but not a mutation process, the calculation mode can ensure the accuracy and the reliability of the monitoring result.
The main flow rate adjusting valve 23 may be an automatic valve, and may be a flow rate adjusting valve such as an electric butterfly valve.
Further preferably, when the opening degree of the main flow rate regulating valve 23 is regulated, the regulation is aimed at: the fluctuation range of the temperature of the middle point of the boiler is controlled within 0-10 ℃, and the effect of improving the stability of the main steam parameters of the gas boiler can be achieved.
In the case where the fluctuation of the gas heating value is not large, preferably, the opening degree of the main flow rate regulating valve 23 is increased or decreased by 1% to 10% for every 1KPa of decrease or increase of the gas pressure.
Further, the adjusting means further includes:
when the main flow regulating valve 23 is regulated to the maximum opening degree and still does not reach the control target, the main water supply flow of the corresponding gas boiler is further regulated to reach the control target. Wherein, after the main flow regulating valve 23 is opened to the maximum opening, the main water flow of the boiler is further regulated.
When the boiler is in operation, in order to ensure the stability of the main steam parameters, the following relations should be satisfied between fuel and water:
Q water and its preparation method ＝ηQ Gas (gas)
Wherein Q is Water and its preparation method Heat absorbed for feedwater heat exchange; η is the thermal efficiency of the boiler.
Q Water and its preparation method ＝m Water and its preparation method (h out -h in )
Wherein m is Water and its preparation method The main water supply flow of the boiler; h is a out To the specific enthalpy value after heat exchange of the water supply, h in Is the specific enthalpy value before heat exchange of the feed water. For h out H in Reference is generally made to the handbook of the thermal Properties of Water and Water vapor in engineering at present; the parameters of the main boiler 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 main water supply of the boiler, inquiring the water and superheated steam table can obtain the specific enthalpy value h of the main water supply of the boiler in The method comprises the steps of carrying out a first treatment on the surface of the According to the temperature and pressure parameters of the main steam of the boiler, the specific enthalpy value h of the main steam of the boiler can be obtained by inquiring a water and superheated steam table out 。
Therefore, the calculation formula of the main feedwater flow of the boiler is:
although the boiler heat efficiency eta is different under different loads, the fluctuation of the coal gas is a continuous process, and the boiler heat efficiency eta is not suddenly changed, so that the boiler heat efficiency eta at two adjacent monitoring moments can be approximately considered to be unchanged. However, it is preferable that the boiler heat efficiency η is recalculated after each adjustment of the opening degree of the main flow rate adjusting valve 23, and a specific calculation method is a conventional technique in the art and will not be described here.
Accordingly, the adjustment amount of the main feedwater flow of the boiler is calculated according to the following formula:
wherein eta is the thermal efficiency of the boiler, h out To the specific enthalpy value after heat exchange of the water supply, h in Is the specific enthalpy value before heat exchange of the feed water.
According to the calculation result, the frequency converter frequency of the water feed pump can be adjusted to achieve the purpose of adjusting the main water feed flow of the boiler. The adjustment quantity of the main water supply flow of the boiler is equal to delta m Water and its preparation method Obviously is an ideal regulation target, but the regulation quantity of the main water supply flow of the boiler is close to the delta m in consideration of the actual working condition Water and its preparation method Is considered reasonableThe specific difference should meet the requirement of ensuring the fluctuation range of the temperature of the middle point of the boiler to be 0-10 ℃.
Further, the adjusting means further includes:
the time t2 required for the gas to be transferred from the first monitoring position 11 to the boiler burner 5 of the corresponding gas boiler and the time t3 required for the feed water to be transferred from the feed water pump to the boiler water wall are obtained,
if t2 is more than t3, the main water supply flow of the boiler is regulated in a lagging way, and the lagging time is t2-t3; or the external source gas is supplemented into the variable supply pipe 22 to improve the stability of the main steam parameters of the corresponding gas boiler; wherein, the external gas supplementing point can be positioned at the upstream or downstream of the adjusting position, the time of the external gas reaching the boiler burner 5 is preferably the same as t3, the external gas is supplemented when the gas fluctuation signal is monitored, and the ventilation time of the external gas is t2-t3. Wherein, a gas storage bypass 3 can be connected to the variable supply pipe 22, the gas storage bypass 3 is connected to an external source 31, and a bypass regulating valve 32 and a quick-cut valve 33 are arranged on the gas storage bypass 3, and the flow rate of the external source gas is controlled by the bypass regulating valve 32.
If t2 is less than t3, the opening of the branch pipe flow regulating valve 41 on the burner air inlet pipe 4 at the inlet side of each boiler burner 5 is reduced before the main water supply flow of the boiler is regulated in place, so that the stability of the main steam parameters of the corresponding gas boiler is improved. Further, after the time t3 is reached, the opening of the branch pipe flow regulating valve 41 is reset to the position before the gas fluctuation, so that the running stability of the subsequent boiler is further improved.
Based on the scheme, the time for the gas fluctuation to reach the boiler burner 5 and the time for the feed water to reach the boiler water-cooled wall are fully considered, the reliability of the adjustment operation is ensured, the running stability of the gas boiler can be further improved, and the main steam parameters under various working conditions can be controlled within a target range.
According to the control method provided by the embodiment, in the running process of the boiler, the opening degree of the main flow regulating valve 23 on the variable supply pipe 22 can be regulated in advance according to the gas fluctuation condition in the main gas pipeline 1 monitored at the monitoring position, so that the stability of the released heat of gas combustion in unit time is maintained, the stability of the main steam parameters of the gas boiler is further improved, and the operation is convenient and the reliability is high.
Example III
The present embodiment optimizes the steady operation control method in the first embodiment described above.
As shown in fig. 2, a gas storage device 6 and a main flow rate regulating valve 23 are provided on the variable supply pipe 22, and the main flow rate regulating valve 23 is located downstream of the gas storage device 6.
In one embodiment, the gas storage device 6 is a gas tank, which is a mature gas storage device, and the specific structure is not described herein.
Preferably, the adjusting means comprises:
when the pressure fluctuation of the gas in the main gas pipeline 1 is within a set fluctuation range, the upstream gas firstly enters the gas storage device 6 for caching, and the gas storage device 6 supplies the gas to the corresponding gas boiler so as to realize primary buffering of the gas fluctuation;
under the general working condition, after the gas storage device 6 is additionally arranged, the gas can be supplied to the boiler burner 5 relatively stably, but when the fluctuation of the upstream gas pressure is large, the gas pressure at the outlet side of the gas storage device 6 still can be fluctuated, and when the gas storage device 6 continuously enters and discharges gas, the internal gas heat value also can be fluctuated, so that the gas heat value at the outlet side of the gas storage device 6 still can be fluctuated. Therefore, when the upstream gas pressure fluctuation exceeds the set fluctuation range and/or the gas heat value at the outlet side of the gas storage device 6 fluctuates, the gas flow is regulated through the main flow regulating valve 23 on the basis of the primary buffer of the gas storage device 6, so that the secondary regulation of the gas fluctuation is realized.
In the embodiment, the gas storage device 6 can be used as a primary buffer, so that adverse impact of gas fluctuation on the boiler can be remarkably relieved, and the operation stability of the supercritical gas boiler and the generator set can be improved; the gas storage device 6 is matched with the main flow regulating valve 23, so that the secondary regulation of gas fluctuation can be realized, and the operation stability of the supercritical gas boiler and the generator set is higher.
Preferably, as shown in fig. 2, a second monitoring position 7 is provided on the variable supply pipe 22, the second monitoring position 7 is located between the gas storage device 6 and the main flow regulating valve 23, and a gas heating value monitoring unit 72 and a plurality of second pressure monitoring units 71 sequentially provided along the gas flowing direction are provided at the second monitoring position 7; the gas heat value monitoring unit 72 may be a heat value meter, and the second pressure monitoring unit 71 may be a pressure transmitter or the like.
The gas pressure is monitored by each second pressure monitoring unit 71 at the second monitoring position 7, and the variation delta Q of the gas heat supply quantity caused by the gas fluctuation is calculated based on the monitored gas pressure fluctuation Gas (gas) The method comprises the steps of carrying out a first treatment on the surface of the Calculating the time t4 required for the gas to run from the second monitoring position 7 to the main flow regulating valve 23;
if DeltaQ Gas (gas) Reducing the opening of the main flow regulating valve 23 after the time t4 to improve the stability of main steam parameters of the corresponding gas boiler;
if DeltaQ Gas (gas) After the time t4, the opening of the main flow regulating valve 23 is increased to improve the stability of main steam parameters of the corresponding gas boiler;
if DeltaQ Gas (gas) =0, keeping the main flow regulating valve 23 opening unchanged.
The second monitoring position 7 is a section, i.e. a section with a certain axial length of the pipe, for example a monitoring section on the variable feed pipe 22, which facilitates the arrangement of the monitoring device.
The number of the gas pressure measuring points (i.e. the second pressure monitoring units 71) 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 in the range of 1-20 m, and more preferably in the range of 5-15 m. The gas heating value monitoring unit 72 may be disposed on the same section of the pipe opposite to one of the second pressure monitoring units 71, may be disposed between two adjacent second pressure monitoring units 71, or may be disposed downstream of each of the second pressure monitoring units 71.
In one embodiment, the gas heat supply is calculated using the following formula:
Q gas (gas) ＝qm Air flow
Wherein q is the heat value of the gas, and the real-time monitoring can be performed through the gas heat value monitoring unit 72; m is m Air flow The gas flow can be obtained by monitoring the conversion of the gas pressure.
In actual operation, the fluctuation of the gas heat value is small, so in the embodiment, the influence of the fluctuation of the gas flow on the operation of the boiler is mainly considered.
The second monitoring position 7 is preferably spaced from the main flow control valve 23 to ensure that appropriate treatment can be carried out in advance in the event of gas fluctuations. In one embodiment, the distance is above 20m, e.g., controlled in the range of 20-100 m.
The main flow rate regulating valve 23 is spaced from the boiler burner 5 by a distance of preferably 20m or more, for example, 20 to 100 mm.
The main flow rate adjusting valve 23 is obviously an automatic valve, and may be an electric butterfly valve or the like.
In one embodiment, as shown in fig. 2, a third monitoring position 12 is further provided on the main gas pipe 1, and a plurality of third pressure monitoring units are sequentially provided at the third monitoring position 12 along the gas flowing direction. The third monitoring position 12 is used for monitoring the pressure of the upstream gas, so that whether the pressure of the upstream gas fluctuates or not can be timely mastered, and subsequent adjustment is facilitated.
Further, when calculating the time t3 required for the gas to run from the second monitoring position 7 to the main flow regulating valve 23, the gas flow rate can be calculated based on the gas pressure monitored by the initial running position by taking the position of the gas pressure measuring point of the second monitoring position 7 at the center position or taking the center position of the second monitoring position 7 as the initial running position of the gas, and combining the pipe diameter and the like.
Further, when Δq is calculated Gas (gas) When the gas pressure fluctuation is obtained, specifically, each phase is calculatedThe pressure difference between the adjacent two second pressure monitoring units 71 is taken as the average value of the pressure differences as the fluctuation amount of the gas pressure. In calculating the pressure difference between every adjacent two of the second pressure monitoring units 71, it is preferable that the monitoring data of the downstream pressure monitoring unit is subtracted from the monitoring data of the upstream pressure monitoring unit. Because the gas fluctuation is generally a creep process, but not a mutation process, the calculation mode can ensure the accuracy and the reliability of the monitoring result.
Further preferably, when the opening degree of the main flow rate regulating valve 23 is regulated, the regulation is aimed at: the fluctuation range of the temperature of the middle point of the boiler is controlled within 0-10 ℃, and the effect of improving the stability of the main steam parameters of the gas boiler can be achieved. In the case where the fluctuation of the gas heating value is not large, preferably, the opening degree of the main flow rate regulating valve 23 is increased or decreased by 1% to 10% for every 1KPa of decrease or increase of the gas pressure.
Further preferably, the above adjustment means further includes:
when the main flow regulating valve 23 is regulated to the maximum opening degree and still does not reach the control target, the control target is further achieved by regulating the main water supply flow of the boiler. The main water supply flow measure of the boiler can be referred to the related content in the second embodiment, and will not be described herein.
Further, the adjusting means further includes:
the time t5 required for the coal gas to be transmitted from the second monitoring position 7 to the boiler burner 5 and the time t6 required for the feed water to be transmitted from the feed water pump to the boiler water wall are obtained,
if t5 is more than t6, the main water supply flow of the boiler is regulated in a lagging way, and the lagging time is t5-t6;
if t5 is less than t6, the opening of the branch pipe flow regulating valve 41 on the burner air inlet pipe 4 at the inlet side of each boiler burner 5 is reduced before the main water supply flow of the boiler is regulated in place, so that the stability of the main steam parameters of the corresponding gas boiler is improved. Further, after the time t6 is reached, the opening of the branch pipe flow regulating valve 41 is reset to the position before the gas fluctuation, so that the running stability of the subsequent boiler is further improved.
Based on the scheme, the time for the gas fluctuation to reach the boiler burner 5 and the time for the feed water to reach the boiler water-cooled wall are fully considered, the reliability of the adjustment operation is ensured, the running stability of the gas boiler can be further improved, and the main steam parameters under various working conditions can be controlled within a target range.
Optionally, a plurality of sets of gas storage devices 6 can be arranged, and each gas storage device 6 is connected in parallel, so that each gas storage device 6 can receive upstream gas and supply gas to the downstream, and the operation stability and reliability of the supercritical gas boiler and the generator set can be further improved. For example, two sets of gas storage devices 6 are arranged, and when one set of gas storage devices 6 supplies gas downstream, the other set of gas storage devices 6 receives upstream gas; based on the scheme, on one hand, unnecessary fluctuation caused when the gas storage device 6 simultaneously feeds and discharges gas can be avoided, on the other hand, after the gas storage device 6 singly receives the upstream gas, the downstream gas is fed for a period of time, the gas homogenizing effect can be achieved, and the uniformity of the gas heat value in the gas storage device 6 is improved.
In one embodiment, the capacity of the gas storage device 6 is 1-10 ten thousand Nm 3 。
Example IV
The present embodiment optimizes the steady operation control method in the first embodiment described above.
As shown in fig. 2, a gas storage device 6 and a main flow rate regulating valve 23 are provided on the variable supply pipe 22, and the main flow rate regulating valve 23 is located downstream of the gas storage device 6.
Further, a bypass pipe 61 is provided to the variable supply pipe 22, both ends of the bypass pipe 61 are connected to the upstream and downstream of the gas storage device 6, respectively, and a bypass valve 612 is provided to the bypass pipe 61. The bypass valve 612 may be a shut-off valve.
In one embodiment, the gas storage device 6 is a gas tank, which is a mature gas storage device, and the specific structure is not described herein.
Preferably, the adjusting means comprises:
monitoring the fluctuation of the gas pressure in the gas main pipeline 1, and when the fluctuation of the gas pressure in the gas main pipeline 1 does not occur or the fluctuation of the gas pressure of the gas main pipeline 1 is within the allowable fluctuation range, the upstream gas runs through the bypass pipe 61; when the fluctuation of the gas pressure exceeds the allowable fluctuation range, the upstream gas enters the gas storage device 6;
and/or, a bypass flow regulating valve 611 is arranged on the bypass pipe 61, a stable flow is set through the bypass pipe 61, when the pressure of the coal gas in the coal gas main pipe 1 positively fluctuates, the bypass pipe 61 keeps normal coal gas flow, and redundant coal gas enters the coal gas storage device 6; when negative fluctuation of the pressure of the coal gas occurs in the main coal gas pipeline 1, the coal gas is circulated through the bypass pipe 61 and the fluctuation is supplemented through the coal gas storage device 6.
For the allowable fluctuation range, in one embodiment, the fluctuation amount Δm of the gas flow is based on the normal gas flow Air flow Within the range of 0-6%, the upstream gas pressure fluctuation can be considered to be within the allowable fluctuation range.
The set fluctuation range can be determined according to specific working conditions, system design parameters and the like. In the above-described arrangement with the bypass pipe 61, optionally on the basis of the normal gas flow, the gas flow fluctuates by an amount Δm Air flow Within the range of 6 to 40%, the upstream gas pressure fluctuation can be considered to be within the set fluctuation range.
When the upstream gas is directly connected through the bypass pipe 61, the inlet and the outlet of the gas storage device 6 are preferably closed; the bypass pipe 61 is preferably closed when the upstream gas enters the gas storage device 6.
The scheme can effectively reduce flow impact caused by gas fluctuation on the gas storage device 6, the adjustment operation is quicker and more effective, the smoothness and the safety of system operation can be ensured, and the gas circulation efficiency can be improved.
In addition, when the gas storage device 6 fails or overhauls, the upstream gas can be directly communicated through the bypass pipe 61, so that the smoothness and safety of the system operation can be ensured; in addition, in this working condition, when the upstream gas fluctuates, the operation stability of the supercritical gas boiler can be ensured by adjusting the main flow adjusting valve 23 and by adjusting the main water supply flow of the boiler, etc., and the adjustment mode of the main flow adjusting valve 23 in the third embodiment is suitable for this working condition, so that the description thereof will not be repeated.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.
Claims (7)
1. The stable operation control method of the multi-unit supercritical gas power generation system is characterized in that the multi-unit supercritical gas power generation system is provided with a gas main pipeline and a plurality of gas boilers, each gas boiler is provided with a gas supply pipe, and each gas supply pipe is connected with the gas main pipeline;
the method comprises the following steps:
setting a part of the gas supply pipes as constant supply pipes and the rest gas supply pipes as variable supply pipes;
when the gas flow in the main gas pipeline fluctuates, the gas flow of the constant supply pipe is ensured to be stable, and the gas flow stability of the outlet of the variable supply pipe is improved by adopting adjusting measures so as to improve the stability of main steam parameters of the corresponding gas boiler;
a first monitoring position is arranged on the main gas pipeline, and a plurality of first pressure monitoring units are sequentially arranged at the first monitoring position along the gas flowing direction; setting a regulating position on the variable supply pipe, wherein a main flow regulating valve is arranged at the regulating position;
the adjusting measures comprise:
monitoring the gas pressure by each first pressure monitoring unit at the first monitoring position, and calculating the variation delta Q of the gas heat supply quantity in each variable supply pipe caused by the gas fluctuation based on the monitored gas pressure fluctuation and the gas flow required by each constant supply pipe Gas (gas) The method comprises the steps of carrying out a first treatment on the surface of the Calculating time t1 required by the gas to run from the first monitoring position to the adjusting position;
if DeltaQ Gas (gas) Reducing the opening of the main flow regulating valve after time t1 to improve the stability of main steam parameters of the corresponding gas boiler;
if DeltaQ Gas (gas) After the time t1, the opening of the main flow regulating valve is increased to improve the stability of main steam parameters of the corresponding gas boiler;
if DeltaQ Gas (gas) =0, keeping the main flow regulating valve opening unchanged;
the adjusting means further comprises:
when the maximum opening degree of the main flow regulating valve still cannot reach the control target, the main water supply flow of the corresponding gas boiler is further regulated to reach the control target;
the adjustment quantity of the main water supply flow of the boiler is calculated according to the following formula:
the method comprises the steps of carrying out a first treatment on the surface of the Wherein eta is the thermal efficiency of the boiler, h out To the specific enthalpy value after heat exchange of the water supply, h in Is the specific enthalpy value before heat exchange of the feed water.
2. The steady operation control method of a multi-unit supercritical gas power generation system according to claim 1, wherein the adjustment means further comprises:
the time t2 required by the gas to be transmitted from the first monitoring position to the boiler burner of the corresponding gas boiler and the time t3 required by the water supply to be transmitted from the water supply pump to the boiler water wall are obtained,
if t2 is more than t3, the main water supply flow of the boiler is regulated in a lagging way, and the lagging time is t2-t3; or the exogenous gas is supplemented into the variable supply pipe so as to improve the stability of the main steam parameters of the corresponding gas boiler;
if t2 is less than t3, before the main water supply flow of the boiler is regulated in place, reducing the opening of a branch pipe flow regulating valve on a combustor air inlet pipe at the inlet side of each boiler combustor so as to improve the stability of main steam parameters of the corresponding gas boiler.
3. The method for controlling the stable operation of a multi-unit supercritical gas power generation system according to claim 1, wherein a gas storage device and a main flow regulating valve are provided on the variable supply pipe, the main flow regulating valve being located downstream of the gas storage device.
4. A steady operation control method of a multi-unit supercritical gas power generation system according to claim 3, wherein the adjustment means comprises:
when the pressure fluctuation of the gas in the main gas pipeline is within a set fluctuation range, the upstream gas firstly enters the gas storage device for caching, and the gas storage device supplies the gas to the corresponding gas boiler so as to realize primary buffering of the gas fluctuation;
when the fluctuation of the gas pressure in the main gas pipeline exceeds a set fluctuation range and/or the fluctuation of the gas heat value at the outlet side of the gas storage device, the main flow regulating valve is used for regulating the gas flow on the basis of primary buffering of the gas storage device, so that the secondary regulation of the gas fluctuation is realized.
5. The steady operation control method of a multi-unit supercritical gas power generation system according to claim 4, wherein the adjustment means comprises:
a second monitoring position is arranged on the variable supply pipe, the second monitoring position is positioned between the gas storage device and the main flow regulating valve, and a gas heat value monitoring unit and a plurality of second pressure monitoring units which are sequentially arranged along the gas flowing direction are arranged at the second monitoring position;
monitoring the gas pressure by each second pressure monitoring unit at the second monitoring position, and calculating the variation delta Q of the gas heat supply quantity caused by the gas fluctuation based on the monitored gas pressure fluctuation Gas (gas) The method comprises the steps of carrying out a first treatment on the surface of the Calculating the time t4 required for the gas to run from the second monitoring position to the main flow regulating valve;
if DeltaQ Gas (gas) Reducing the opening of the main flow regulating valve after time t4 to improve the stability of the main steam parameters of the corresponding gas boiler more than 0Qualitative;
if DeltaQ Gas (gas) After time t4, increasing the opening of the main flow regulating valve to improve the stability of main steam parameters of the corresponding gas boiler;
if DeltaQ Gas (gas) =0, keeping the main flow regulating valve opening unchanged.
6. The method for controlling the steady operation of a multi-unit supercritical gas power generation system as claimed in claim 3, wherein a bypass pipe is provided on the variable supply pipe, both ends of the bypass pipe are respectively connected upstream and downstream of the gas storage device, and a bypass valve is provided on the bypass pipe.
7. The steady operation control method of a multi-unit supercritical gas power generation system according to claim 6, wherein the adjustment means comprises:
monitoring the fluctuation of the gas pressure in the gas main pipeline, and when the fluctuation of the gas pressure in the gas main pipeline does not occur or the fluctuation of the gas pressure of the gas main pipeline is within the allowable fluctuation range, directly running upstream gas through the bypass pipe; when the fluctuation of the gas pressure exceeds the allowable fluctuation range, the upstream gas enters the gas storage device;
and/or a bypass flow regulating valve is arranged on the bypass pipe, a stable flow is set through the bypass pipe, when the pressure of the coal gas in the coal gas main pipeline positively fluctuates, the bypass pipe keeps normal coal gas flow, and redundant coal gas enters the coal gas storage device; when the pressure of the coal gas in the main coal gas pipeline fluctuates negatively, the coal gas circulates through the bypass pipe and the fluctuation is supplemented through the coal gas storage device.
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