A temperature regulation method and system based on a waste heat boiler and a storage medium

Abstract

This invention relates to the field of industrial boiler technology, providing a temperature regulation method, system, and storage medium based on a waste heat boiler. Based on the different temperature characteristics of the waste heat boiler at different stages of gas turbine load, preset conditions are set to divide the temperature control process into two different stages. When the gas turbine load is low, the high-pressure steam temperature after passing through the superheater is low, so a PID algorithm function can be used for regulation. When the gas turbine load is high, the target temperature after the superheater is used as the feedforward quantity for the superheater water logic. This allows the temperature after the superheater to be directly controlled near the actual required temperature when the gas turbine load changes, overcoming the lag of the regulation system. Not only is the control deviation generated by the calculated feedforward quantity very small, but it can also be corrected by the main PID, thereby achieving proactive temperature control. The maximum temperature deviation of this invention is controlled within ±3℃, meeting the requirement of operating procedures not exceeding 5℃.

Description

Technical Field

[0001] This invention relates to the field of industrial boiler technology, and in particular to a temperature regulation method, system and storage medium based on a waste heat boiler. Background Technology

[0002] The M701F4 gas-fired combined cycle turbine unit uses a single-stage spray desuperheating control scheme for the high-pressure main steam temperature in the waste heat boiler, with the desuperheating water sourced from the high-pressure feedwater. The automatic logic for controlling the desuperheating water uses a cascade PID control method, with only a four-segment piecewise linear function calculated from the gas turbine load as the feedforward. This results in poor regulation quality, leading to overheating of the high-pressure main steam temperature during significant load fluctuations. During unit commissioning, a micro-component of boiler inlet flue gas temperature was added to the feedforward to improve temperature regulation quality. This reduced the overheating phenomenon somewhat, but it still could not be completely eliminated.

[0003] b) Deficiencies of existing technical solutions: 1. The four-segment piecewise linear function calculated from the gas turbine load is not accurate enough, and its contribution to the stability of the regulation system is small, so it cannot achieve the effect of advance regulation.

[0004] 2. Refer to Chinese invention patent application number 01810338086.7, "A Waste Heat Boiler Main Steam Temperature Control Device and Control Method," which discloses "obtaining the real-time exhaust temperature values ​​of the gas turbine exhaust duct and the waste heat boiler inlet...that is, using the flue gas temperature of the gas turbine exhaust duct and the waste heat boiler inlet flue gas duct, the flue gas temperature signal output by the gas turbine combustion state observation device is successively input into the differentiator and the first function generator, and the output value is superimposed on the valve command, which can overcome the interference of gas turbine exhaust temperature and waste heat boiler inlet flue gas temperature fluctuations on the main steam temperature." However, operational experience shows that when the gas turbine load increases, the boiler inlet flue gas temperature does not necessarily increase; sometimes it decreases. Using the minute component of the flue gas temperature as the feedforward adjustment quantity will not be able to accurately predict the superheater temperature, thus leading to erroneous adjustments such as reverse heating or cooling. Summary of the Invention

[0005] This invention provides a temperature regulation method, system, and storage medium based on a waste heat boiler, which solves the technical problems that existing temperature regulation schemes for high-pressure superheaters in waste heat boilers cannot achieve advance regulation, and that existing flue gas temperature as a feedforward regulation quantity cannot reflect the actual temperature change, leading to temperature regulation failure.

[0006] To solve the above technical problems, the present invention provides a temperature regulation method based on a waste heat boiler, comprising the following steps: S1. Obtain the gas turbine load and determine whether the gas turbine load meets the preset conditions. If not, proceed to step S2; if yes, proceed to step S3. S2. Collect the real-time output temperature of the high-pressure main steam, substitute it into the PID algorithm function, calculate the temperature control parameters, and then proceed to step S4. S3. Obtain the real-time flow rate of the high-pressure main steam, calculate the target temperature based on the current gas turbine load and the prediction function formula, and then proceed to step S4. S4. Control the water flow rate above the desuperheating water valve according to the target temperature or the temperature control parameters to adjust the unit temperature.

[0007] This basic scheme is based on the different temperature characteristics of the waste heat boiler at different stages of gas turbine load. It sets preset conditions and divides the temperature control process into two different stages. When the gas turbine load is low, the high-pressure steam temperature after passing through the superheater is low, so a PID algorithm function can be used for adjustment. When the gas turbine load is high, the steam flow rate of the high-pressure main steam is introduced for temperature control analysis. Combined with the current gas turbine load, the target temperature after passing the desuperheater is calculated using the prediction function formula, and then the output temperature of the high-pressure main steam is adjusted. Using the target temperature after passing the desuperheater as the feedforward quantity for the desuperheater logic allows the temperature after passing the desuperheater to be directly controlled near the actual required temperature when the gas turbine load changes. This overcomes the lag of the regulation system. Not only is the control deviation generated by the calculated feedforward quantity very small, but it can also be corrected by the main PID, thus achieving proactive temperature control. When the gas turbine load fluctuates significantly and rapidly, the maximum temperature deviation is controlled within ±3℃, meeting the requirement of no more than 5℃ in the operating procedures.

[0008] In a further embodiment, step S3 includes the following steps: S31. Real-time flow rate of high-pressure main steam entering the superheater is collected using a throttling orifice plate. S32. Obtain the current gas turbine load and calculate the standard steam flow rate based on the gas turbine load; S33. Calculate the dynamic prediction component based on the prediction function formula and the real-time flow rate and standard steam flow rate; S34. Based on the predicted function formula, the dynamic predicted component is superimposed on the second temperature threshold to obtain the target temperature; the second temperature threshold is the temperature threshold corresponding to the temperature higher than the steam temperature after cooling.

[0009] In a further embodiment, in step S3, the formula for the prediction function is as follows: ; in, t1 is the target temperature, and t2 is the second temperature threshold. For adjustment coefficients, For real-time traffic, This is the standard steam flow rate.

[0010] This solution is based on the actual working environment of the waste heat boiler. Considering that when the gas turbine load is too high, the flow rate of the high-pressure main steam is closely related to the steam temperature at the outlet of the high-pressure desuperheater, the steam flow rate of the high-pressure main steam is introduced into the steam temperature control analysis. By calculating the target temperature of the steam after the high-pressure desuperheater, the output temperature of the high-pressure main steam is indirectly adjusted. This solution has high accuracy and can achieve precise temperature control of the waste heat boiler, thereby reducing the record of high-temperature damage to the equipment and ensuring the safe operation of the unit.

[0011] In a further implementation, the method further includes step S0, calculating the adjustment coefficient based on the first temperature threshold, the second temperature threshold, and the real-time flow rate, using the following formula: ; Where t1 is the first temperature threshold corresponding to the high-pressure main steam output temperature, and t2 is the second temperature threshold.

[0012] This solution calculates the formula for the adjustment coefficient based on the relationship between the superheater and the system heat change under different gas turbine loads and load variations. By obtaining the adjustment coefficient that is closely related to the current state, the temperature change of the high-pressure main steam can be tracked in real time, thereby achieving precise tracking and adjustment.

[0013] In a further implementation, in step S1: the preset conditions include the gas turbine load being above 150MW and operating stably.

[0014] This solution involves statistical analysis of waste heat boiler parameters under different gas turbine loads, establishing 150MW as the node for switching the unit's temperature regulation mode. This allows for matching the corresponding temperature control process according to the actual working environment, achieving precise and efficient temperature control.

[0015] In a further embodiment, step S2 includes the following steps: S21. Collect the real-time output temperature of the high-pressure main steam from the output end of the superheater, and obtain the first temperature threshold corresponding to the output temperature. S22. Calculate the difference between the real-time output temperature and the first temperature threshold to obtain the temperature error; S23. Substitute the temperature error into the PID algorithm function, calculate the temperature control parameters, and then proceed to step S4.

[0016] In a further implementation, the PID algorithm function is as follows: ; Among them, K P K I K DThese are the proportional term coefficient, integral term coefficient, and derivative term coefficient, respectively; e(t) is the temperature error in the system; Δu(t) is the temperature control parameter output to the PID controller.

[0017] This scheme uses PID control for feedforward control of high-pressure main steam, which continuously brings the temperature closer to the set temperature (first temperature threshold) and has a fast response speed, thus improving the intelligence and control accuracy of the equipment.

[0018] The present invention also provides a temperature regulation system based on a waste heat boiler, which is applied to the above-mentioned temperature regulation method based on a waste heat boiler, including a waste heat boiler and a first superheater and a second superheater installed in the waste heat boiler, as well as a superheater desuperheater connecting the first superheater and the second superheater. When it is determined that the gas turbine load meets the preset conditions, the real-time flow rate of high-pressure main steam is obtained from the output end of the second superheater. Based on the current gas turbine load and the estimated function formula, the target temperature of the desuperheating water entering the second superheater is calculated, and then the high-pressure desuperheater is controlled to regulate the unit temperature. When it is determined that the gas turbine load does not meet the preset conditions, the real-time output temperature of the high-pressure main steam is collected from the output end of the second superheater, substituted into the PID algorithm function, and the temperature control parameters are calculated to control the high-pressure desuperheater to adjust the unit temperature.

[0019] The present invention also provides a storage medium storing a computer program, which is loaded by the temperature regulation system of the aforementioned waste heat boiler high-pressure superheater to implement the aforementioned temperature regulation method of the waste heat boiler high-pressure superheater. The storage medium may be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating a temperature regulation method based on a waste heat boiler provided in an embodiment of the present invention. Figure 2 This is a system framework diagram of a temperature regulation system based on a waste heat boiler provided in an embodiment of the present invention. Detailed Implementation

[0021] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the present invention. The accompanying drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0022] This invention provides a temperature regulation method based on a waste heat boiler, such as... Figure 1 As shown, in this embodiment, steps S0 to S4 are included: S0. Calculate the adjustment coefficient based on the first temperature threshold, the second temperature threshold, and the real-time flow rate. The calculation formula is as follows: When the gas turbine load is stable at W MW, the heat exchange formula of the superheater system is as follows: Q(W) = *(t1-t2)*C------(1) Q(W) is the heat released by the flue gas in the high-pressure superheater, C is the specific heat capacity of the superheated steam, and W is the gas turbine load; When the gas turbine load changes from other values ​​to W MW, due to the boiler's lag characteristics, the heat exchange formula for the superheater system is as follows: Q(W)≈ *(t1-t2+δt))*C------(2) δt is the deviation between the temperature prediction function and the actual temperature after passing the desuperheater (i.e., the dynamic prediction component). From equations (1) and (2), it can be deduced that: δt≈(t1-t2) - ) / ; That is, it can be deduced that: ; Where t1 is the first temperature threshold corresponding to the high-pressure main steam output temperature, and t2 is the second temperature threshold.

[0023] Specifically, with Taking 568℃ as an example, during normal operation, the gas turbine load varies between 166MW and 277MW. When the gas turbine load increases from 166MW to 277MW, due to the lag in boiler parameters, the actual steam flow rate remains around 216t / h corresponding to 166MW, and k can be calculated to be approximately 0.33. When the gas turbine load decreases from 277MW to 166MW, the actual steam flow rate remains around 286t / h corresponding to 277MW, and k can be calculated to be approximately 0.48. Therefore, the range of k value variation can be deduced to be 0.33-0.48. During commissioning, the k value can be determined based on the effect of high-pressure main steam temperature regulation; this embodiment does not impose such a limitation.

[0024] This embodiment calculates the formula for the adjustment coefficient based on the relationship between the superheater and the system heat change under different gas turbine loads and load variations. By obtaining the adjustment coefficient that is closely related to the current state, the temperature change of the high-pressure main steam can be tracked in real time, thereby achieving precise tracking and adjustment.

[0025] S1. Obtain the gas turbine load and determine whether the gas turbine load meets the preset conditions. If not, proceed to step S2; if yes, proceed to step S3. In this embodiment, the preset conditions include that the gas turbine load is above 150MW (the specific value can be customized according to different gas turbines) and is operating stably.

[0026] This embodiment statistically analyzes the parameters of the waste heat boiler under different gas turbine loads and establishes 150MW as the node for switching the unit temperature regulation mode. This allows for matching the corresponding temperature control process according to the actual working environment, thereby achieving precise and efficient temperature control.

[0027] S2. Collect the real-time output temperature of the high-pressure main steam, substitute it into the PID algorithm function, calculate the temperature control parameters, and then proceed to step S4, including steps S21~S23: S21. Collect the real-time output temperature of the high-pressure main steam from the output end of the superheater, and obtain the first temperature threshold corresponding to the output temperature. S22. Calculate the difference between the real-time output temperature and the first temperature threshold to obtain the temperature error; S23. Substitute the temperature error into the PID algorithm function, calculate the temperature control parameters, and then proceed to step S4.

[0028] In this embodiment, the PID algorithm function is as follows: ; Among them, K P K I K D These are the proportional term coefficient, integral term coefficient, and derivative term coefficient, respectively; e(t) is the temperature error in the system; Δu(t) is the temperature control parameter output to the PID controller.

[0029] This embodiment uses PID for feedforward control of high-pressure main steam, which continuously brings the temperature closer to the set temperature (first temperature threshold) and has a fast response speed, thus improving the intelligence and control accuracy of the equipment.

[0030] S3. Obtain the real-time flow rate of the high-pressure main steam, calculate the target temperature based on the current gas turbine load and the predicted function formula, and then proceed to step S4, including steps S31~S32: S31. Real-time flow rate of high-pressure main steam entering the superheater is collected using a throttling orifice plate. S32. Obtain the current gas turbine load and calculate the standard steam flow rate based on the gas turbine load; S33. Calculate the dynamic prediction component based on the prediction function formula and real-time flow rate and standard steam flow rate; S34. Based on the prediction function formula, the dynamic prediction component is superimposed on the second temperature threshold to obtain the target temperature; the second temperature threshold is the temperature threshold corresponding to the steam temperature after overheating and de-cooling; the target temperature is adjusted to the steam temperature after overheating and de-cooling.

[0031] In this embodiment, the formula for the predicted function in step S3 is as follows: ; in, t1 is the target temperature, and t2 is the second temperature threshold. For adjustment coefficients, For real-time traffic, This is the standard steam flow rate.

[0032] This embodiment is based on the actual working environment of the waste heat boiler. Considering that when the gas turbine load is too high, the flow rate of the high-pressure main steam is closely related to the steam temperature at the outlet of the high-pressure desuperheater, the steam flow rate of the high-pressure main steam is introduced into the steam temperature control analysis. By calculating the target temperature of the steam after the high-pressure desuperheater, the output temperature of the high-pressure main steam is indirectly adjusted. The accuracy is high, and the temperature of the waste heat boiler can be precisely controlled, thereby reducing the record of high-temperature damage to the equipment and ensuring the safe operation of the unit.

[0033] S4. Control the water flow rate above the desuperheating water valve according to the target temperature or temperature control parameters to regulate the unit temperature.

[0034] This basic scheme is based on the different temperature characteristics of the waste heat boiler at different stages of gas turbine load. It sets preset conditions and divides the temperature control process into two different stages. When the gas turbine load is low, the high-pressure steam temperature after passing through the superheater is low, so a PID algorithm function can be used for adjustment. When the gas turbine load is high (due to the large amount of heat stored in the boiler, the steam flow rate exhibits a significant lag when the gas turbine load changes), the high-pressure main steam flow rate is introduced for temperature control analysis. Combined with the current gas turbine load, the target temperature after passing through the desuperheater is calculated using the prediction function formula, and then the output temperature of the high-pressure main steam is adjusted. Using the target temperature after passing through the desuperheater as the feedforward quantity for the desuperheater water logic allows the temperature after passing through the desuperheater to be directly controlled near the actual required temperature when the gas turbine load changes. This overcomes the lag of the regulation system. Not only is the control deviation generated by the calculated feedforward quantity very small, but it can also be corrected by the main PID, thus achieving proactive temperature control. This invention controls the maximum temperature deviation within ±3℃ when the gas turbine load fluctuates significantly and rapidly, meeting the requirement of no more than 5℃ in the operating procedures.

[0035] Example 2 This invention also provides a temperature control system based on a waste heat boiler, applied to implement the temperature control method based on a waste heat boiler provided in Embodiment 1 above. See [link to related documentation]. Figure 2 It includes a waste heat boiler and a first superheater and a second superheater installed in the waste heat boiler, as well as a high-pressure desuperheater connecting the first superheater and the second superheater. When the gas turbine load is determined to meet the preset conditions, the real-time flow rate of high-pressure main steam is obtained from the output end of the second superheater. Based on the current gas turbine load and the estimated function formula, the target temperature of the desuperheating water entering the second superheater is calculated, and then the high-pressure desuperheater is controlled to regulate the unit temperature. When it is determined that the gas turbine load does not meet the preset conditions, the real-time output temperature of the high-pressure main steam is collected from the output end of the second superheater, substituted into the PID algorithm function, and the temperature control parameters are calculated. Then, the superheater is controlled to adjust the unit temperature.

[0036] It also includes a steam flow acquisition device, preferably a throttling orifice plate for acquisition.

[0037] Example 3 This invention also provides a storage medium storing a computer program. The computer program is loaded by the temperature control system of the waste heat boiler high-pressure superheater provided in Embodiment 2 above, to implement the temperature control method of the waste heat boiler high-pressure superheater provided in Embodiment 1 above. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0038] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A temperature regulation method based on a waste heat boiler, characterized in that, Including the following steps: S1. Obtain the gas turbine load and determine whether the gas turbine load meets the preset conditions. If not, proceed to step S2; if yes, proceed to step S3. S2. Collect the real-time output temperature of the high-pressure main steam, substitute it into the PID algorithm function, calculate the temperature control parameters, and then proceed to step S4. S3. Obtain the real-time flow rate of the high-pressure main steam, calculate the target temperature based on the current gas turbine load and the prediction function formula, and then proceed to step S4. S4. Control the water flow rate of the desuperheating water valve according to the target temperature or the temperature control parameters to adjust the unit temperature. Step S3 includes the following steps: S31. Real-time flow rate of high-pressure main steam entering the superheater is collected using a throttling orifice plate. S32. Obtain the current gas turbine load and calculate the standard steam flow rate based on the gas turbine load; S33. Calculate the dynamic prediction component based on the prediction function formula and the real-time flow rate and standard steam flow rate; S34. Based on the predicted function formula, the dynamic predicted component is superimposed on the second temperature threshold to obtain the target temperature; the second temperature threshold is the temperature threshold corresponding to the temperature higher than the steam temperature after cooling. In step S3, the formula for the prediction function is as follows: ； in, t1 is the target temperature, and t2 is the second temperature threshold. For adjustment coefficients, For real-time traffic, This is the standard steam flow rate.

2. The temperature regulation method based on a waste heat boiler as described in claim 1, characterized in that, It also includes step S0, calculating the adjustment coefficient based on the first temperature threshold, the second temperature threshold, and the real-time flow rate, using the following formula: ； Where t1 is the first temperature threshold corresponding to the high-pressure main steam output temperature, and t2 is the second temperature threshold.

3. The temperature regulation method based on a waste heat boiler as described in claim 1, characterized in that, In step S1: the preset conditions include the gas turbine load being above 150MW and operating stably.

4. The temperature regulation method based on a waste heat boiler as described in claim 1, characterized in that, Step S2 includes the following steps: S21. Collect the real-time output temperature of the high-pressure main steam from the output end of the superheater, and obtain the first temperature threshold corresponding to the output temperature. S22. Calculate the difference between the real-time output temperature and the first temperature threshold to obtain the temperature error; S23. Substitute the temperature error into the PID algorithm function, calculate the temperature control parameters, and then proceed to step S4.

5. The temperature regulation method based on a waste heat boiler as described in claim 4, characterized in that, The PID algorithm function is as follows: ； Among them, K P K I K D These are the proportional term coefficient, integral term coefficient, and derivative term coefficient, respectively; e(t) is the temperature error in the system; Δu(t) is the temperature control parameter output to the PID controller.

6. A temperature control system based on a waste heat boiler, applied to a temperature control method based on a waste heat boiler as described in any one of claims 1-5, characterized in that: It includes a waste heat boiler and a first superheater and a second superheater installed in the waste heat boiler, as well as a high-temperature desuperheater connecting the first superheater and the second superheater. When it is determined that the gas turbine load meets the preset conditions, the real-time flow rate of high-pressure main steam is obtained from the output end of the second superheater. Based on the current gas turbine load and the estimated function formula, the target temperature of the desuperheating water entering the second superheater is calculated, and then the high-pressure desuperheater is controlled to regulate the unit temperature. When it is determined that the gas turbine load does not meet the preset conditions, the real-time output temperature of the high-pressure main steam is collected from the output end of the second superheater, substituted into the PID algorithm function, and the temperature control parameters are calculated to control the high-pressure desuperheater to adjust the unit temperature.

7. A storage medium having a computer program stored thereon, characterized in that: The computer program is loaded by the temperature regulation system based on a waste heat boiler as described in claim 6, to implement the temperature regulation method based on a waste heat boiler as described in any one of claims 1-5.

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