Combined heat and power system and method

Abstract

The present invention discloses a cogeneration system and method, specifically, the startup high-pressure bypass is only used at startup, a peak-shaving high-pressure bypass is added between two high-pressure cylinder steam input pipelines and two high-pressure cylinder steam output pipelines, the medium-pressure cylinder steam output pipeline is connected to the heating connection pipeline, a peak-shaving low-pressure bypass is added between the two medium-pressure cylinder steam input pipelines and the heating connection pipeline, the heating connection pipeline is connected to the heating pipeline, the two medium-pressure cylinder steam input pipelines are connected to the startup low-pressure bypass through the startup low-bypass connection pipeline, and the startup low-pressure bypass is connected to the industrial steam extraction pipeline. The present invention can meet the industrial gas supply demand while reducing the power generation load through deep peak regulation, and can also provide a higher heating heat supply, realizing the deep peak regulation participation effect of the thermal power plant, avoiding the adverse consequences of low-load combustion of the boiler under the existing peak regulation conditions, and solving the problem of tight industrial steam extraction and heat supply under peak regulation conditions.

Description

Technical Field

[0001] The invention relates to the technical field of heat and power cogeneration in thermal power plants, and in particular to a heat and power cogeneration system and method. Background Art

[0002] Cogeneration projects were first used in the industrial sector and later developed into central heating for residents. In recent years, cogeneration projects have been completed and put into operation in various places, continuously improving the heating capacity of cities in my country.

[0003] The temperature in northern my country is relatively low in winter, and as the ambient temperature drops, the heat supply of the cogeneration system needs to increase, and the electrical load also increases. Under the deep peak-shaving conditions of thermal power plants, thermal power units need to reduce the power generation load. At the traditional technical level, reducing the power generation load will affect the heat output and reduce the industrial steam supply.

[0004] Therefore, how to reduce the power generation load during deep peak regulation, meet the requirements of deep peak regulation conditions, meet the industrial gas supply needs, and provide a higher heating supply is a technical problem that needs to be solved urgently. Summary of the invention

[0005] The first purpose of the present invention is to overcome the shortcomings of the prior art and provide a cogeneration system that can meet industrial gas supply needs and provide a higher heating supply while reducing power generation load through deep peak regulation.

[0006] The first object of the present invention is achieved through the following technical scheme: a cogeneration system, comprising a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder, wherein the upper and lower steam inlets of the high-pressure cylinder are connected to upper and lower steam input pipelines of the high-pressure cylinder, the two steam exhaust ports of the high-pressure cylinder are connected to two high-pressure cylinder steam output pipelines, a start-up high-pressure bypass is connected between the two high-pressure cylinder steam input pipelines and the two high-pressure cylinder steam output pipelines, the high-pressure cylinder steam output pipeline is connected to the steam inlet of a boiler reheater, the upper and lower steam inlets of the intermediate-pressure cylinder are connected to upper and lower steam input pipelines of the intermediate-pressure cylinder, the steam outlet of the boiler reheater is connected to the steam input pipeline of the intermediate-pressure cylinder, and the exhaust port of the intermediate-pressure cylinder is connected to the steam outlet of the intermediate-pressure cylinder. The steam port is connected to the medium-pressure cylinder steam output pipeline, the steam inlet of the low-pressure cylinder is connected to the low-pressure cylinder steam input pipeline, the medium-pressure cylinder steam output pipeline is connected to the low-pressure cylinder steam input pipeline, a peak-shaving high-pressure bypass is connected between the two high-pressure cylinder steam input pipelines and the two high-pressure cylinder steam output pipelines, the medium-pressure cylinder steam output pipeline is connected to the heating connecting pipeline, a peak-shaving low-pressure bypass is connected between the two medium-pressure cylinder steam input pipelines and the heating connecting pipeline, the heating connecting pipeline is connected to the heating pipeline, the two medium-pressure cylinder steam input pipelines are connected to a starting low-pressure bypass through a starting low-pressure bypass connecting pipeline, and the starting low-pressure bypass is connected to the industrial steam extraction pipeline.

[0007] The startup high-pressure bypass is provided with a first desuperheater and a startup high-pressure bypass valve.

[0008] The peak-shaving high-pressure bypass is provided with a second desuperheater and a peak-shaving high-pressure bypass valve.

[0009] The peak-shaving low-pressure bypass is provided with a fourth desuperheater and a peak-shaving low-pressure bypass valve.

[0010] The starting low-pressure bypass is provided with a third desuperheater, and the starting low-pressure bypass connecting pipeline is provided with a starting low-pressure bypass valve.

[0011] A low-pressure cylinder steam inlet regulating valve is arranged between the low-pressure cylinder steam input pipeline and the steam inlet of the low-pressure cylinder.

[0012] The heating connection pipeline is provided with a heating connection valve.

[0013] The second purpose of the present invention is to overcome the shortcomings of the prior art and provide a cogeneration system that can meet industrial gas supply needs and provide a higher heating supply while reducing power generation load through deep peak regulation.

[0014] The second object of the present invention is achieved through the following technical solution: A method for cogeneration of heat and power, comprising the following contents:

[0015] a. The startup high-pressure bypass is only used during startup. A new peak-shaving high-pressure bypass is added between the two high-pressure cylinder steam input pipelines and the two high-pressure cylinder steam output pipelines. The medium-pressure cylinder steam output pipeline is connected to the heating connecting pipeline. A new peak-shaving low-pressure bypass is added between the two medium-pressure cylinder steam input pipelines and the heating connecting pipeline. The heating connecting pipeline is connected to the heating pipeline. The two medium-pressure cylinder steam input pipelines are connected to the startup low-pressure bypass through the startup low-bypass connecting pipeline. The startup low-pressure bypass is connected to the industrial steam extraction pipeline.

[0016] b. Open the drain valve from the low-pressure bypass to the industrial exhaust pipeline to drain the condensate from the pipeline, slowly open the valve from the low-pressure bypass to the industrial exhaust pipeline, and use the desuperheater to ensure that the steam temperature from the low-pressure bypass to the industrial exhaust pipeline is less than 300 degrees Celsius, until the industrial exhaust flow rate is greater than 40 tons / hour and the exhaust pressure is greater than 0.7MPa, meeting the industrial production needs of users;

[0017] c. Start the low-pressure bypass until the opening of the industrial exhaust pipeline valve reaches 70%. If the user demand is still not met, or the pressure ratio of the high-pressure cylinder regulating stage pressure P1 to the medium-pressure cylinder second-stage exhaust pressure P2 is less than 5, open the pipeline drain valve of the peak-shaving high-pressure bypass to drain the condensate in the pipeline, slowly open the pipeline valve of the peak-shaving high-pressure bypass, and ensure that the pipeline steam temperature of the peak-shaving high-pressure bypass is between 330-350 degrees Celsius through the desuperheater until the industrial extraction flow rate is greater than 70 tons / hour and the extraction pressure is greater than 0.7MPa, meeting the user's industrial production needs;

[0018] d. Open the drain valve from the peak-shaving low-pressure bypass to the heating pipeline to drain the condensate from the pipeline, slowly open the valve from the peak-shaving low-pressure bypass to the heating pipeline, and ensure that the steam temperature from the peak-shaving low-pressure bypass to the heating pipeline is less than 200 degrees Celsius through the desuperheater. At the same time, monitor the change in the pressure ratio. When the pressure ratio is lower than 5.2, open the pipeline valve of the peak-shaving high-pressure bypass to increase the pressure ratio to above 5.7, and then increase the valve opening from the peak-shaving low-pressure bypass to the heating pipeline. When the pressure ratio is lower than 5.2 again, open the pipeline valve of the peak-shaving high-pressure bypass again. Repeat this operation to maintain the pressure ratio between 5 and 6 to ensure pressure matching at this point of the steam turbine unit, balance the axial thrust of the high- and medium-pressure cylinders of the steam turbine unit, and ensure safe operation of the unit until the heat of the heating pipeline is greater than 400GJ / h to meet the heating needs of users.

[0019] e. When the openings of the pipeline valves of the peak-shaving high-pressure bypass and the valves from the peak-shaving low-pressure bypass to the heating pipeline reach more than 90%, but still cannot meet the needs of the heating network users, slowly close the steam inlet regulating valve of the medium-pressure cylinder steam input pipeline, and monitor the pressure ratio at the same time to make the pressure ratio between 5 and 6 until the opening of the steam inlet regulating valve is reduced to 30%. If it still cannot meet the needs of heating users, slowly reduce the low-pressure cylinder steam inlet regulating valve until the opening of the low-pressure cylinder steam inlet regulating valve is reduced to 20%, and ensure that the low-pressure cylinder intake pressure is greater than 0.01 MPa, so that when the electrical load reaches 25% of the rated installed capacity, the heating heat reaches 600GJ / h.

[0020] The beneficial effects of the present invention are as follows: while reducing the power generation load through deep peak regulation, the present invention can meet the industrial gas supply demand and provide a relatively high heating amount, thereby achieving the deep peak regulation participation effect of the thermal power plant, avoiding the adverse consequences brought about by low-load combustion of boilers under existing peak regulation conditions, and solving the problem of tight industrial steam extraction and heat supply under peak regulation conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention.

[0022] In the figure: 1-high-pressure cylinder; 2-medium-pressure cylinder; 3-low-pressure cylinder; 4-high-pressure cylinder steam input pipeline; 5-high-pressure cylinder steam output pipeline; 6-medium-pressure cylinder steam input pipeline; 7-medium-pressure cylinder steam output pipeline; 8-low-pressure cylinder steam input pipeline; 9-low-pressure cylinder steam input valve; 10-heating connecting pipeline; 11-heating connecting valve; 12-start high-pressure bypass; 13-first desuperheater; 14-start high bypass valve; 15-peak-shaving high-pressure bypass; 16-second desuperheater; 17-peak-shaving high bypass valve; 18-start low-pressure bypass; 19-third desuperheater; 20-start low bypass valve; 21-peak-shaving low-pressure bypass; 22-fourth desuperheater; 23-peak-shaving low bypass valve; 24-industrial steam extraction pipeline; 25-heating pipeline; 26-start low bypass connecting pipeline; 27-medium-pressure cylinder steam inlet regulating valve. DETAILED DESCRIPTION

[0023] The present invention is described in detail below with reference to the accompanying drawings.

[0024] like Figure 1 As shown, a heat and power cogeneration system includes a high-pressure cylinder 1, an intermediate-pressure cylinder 2 and a low-pressure cylinder 3, the upper and lower steam inlets of the high-pressure cylinder 1 are connected to upper and lower high-pressure cylinder steam input pipelines 4, the two steam exhaust ports of the high-pressure cylinder 1 are connected to two high-pressure cylinder steam output pipelines 5, a start-up high-pressure bypass 12 is connected between the two high-pressure cylinder steam input pipelines 4 and the two high-pressure cylinder steam output pipelines 5, the high-pressure cylinder steam output pipeline 5 is connected to the steam inlet of the boiler reheater, the upper and lower steam inlets of the intermediate-pressure cylinder 2 are connected to upper and lower intermediate-pressure cylinder steam input pipelines 6, the steam outlet of the boiler reheater is connected to the intermediate-pressure cylinder steam input pipeline 6, and the steam exhaust port of the intermediate-pressure cylinder 2 is connected to the intermediate-pressure cylinder steam output pipeline 7 The steam inlet of the low-pressure cylinder 3 is connected to the low-pressure cylinder steam input pipeline 8, the medium-pressure cylinder steam output pipeline 7 is connected to the low-pressure cylinder steam input pipeline 8, a peak-shaving high-pressure bypass 15 is connected between the two high-pressure cylinder steam input pipelines 4 and the two high-pressure cylinder steam output pipelines 5, the medium-pressure cylinder steam output pipeline 7 is connected to the heating connecting pipeline 10, a peak-shaving low-pressure bypass 21 is connected between the two medium-pressure cylinder steam input pipelines 6 and the heating connecting pipeline 10, the heating connecting pipeline 10 is connected to the heating pipeline 25, the two medium-pressure cylinder steam input pipelines 6 are connected to a starting low-pressure bypass 18 through a starting low-bypass connecting pipeline 26, and the starting low-pressure bypass 18 is connected to an industrial steam extraction pipeline 24.

[0025] See also Figure 1, the starting high-pressure bypass 12 is provided with a first desuperheater 13 and a starting high bypass valve 14. The peak-shaving high-pressure bypass 15 is provided with a second desuperheater 16 and a peak-shaving high bypass valve 17. The peak-shaving low-pressure bypass 21 is provided with a fourth desuperheater 22 and a peak-shaving low bypass valve 23. The starting low-pressure bypass 18 is provided with a third desuperheater 19, and the starting low bypass connecting pipeline 26 is provided with a starting low bypass valve 20. A low-pressure cylinder steam inlet regulating valve 9 is provided between the low-pressure cylinder steam input pipeline 8 and the steam inlet of the low-pressure cylinder 3. The heating connecting pipeline 10 is provided with a heating connecting valve 11.

[0026] When entering deep peak load regulation, the peak load regulation high pressure bypass 15 is opened to reduce the turbine air intake, and the peak load regulation low pressure bypass 21 is opened to introduce steam into the heating pipeline 25 for heat supply, so as to transfer the power generation steam load to heat supply. During the peak load regulation process, the low pressure bypass 18 is started to supply industrial steam extraction, so as to achieve the characteristics of load reduction without reducing the heat supply, load reduction without reducing the steam extraction, and stable joint supply of steam extraction and heat supply under low load of the steam turbine.

[0027] See also Figure 1 , a cogeneration method, comprising the following contents:

[0028] a. The startup high-pressure bypass 12 is only used during startup. A new peak-shaving high-pressure bypass 15 is added between the two high-pressure cylinder steam input pipelines 4 and the two high-pressure cylinder steam output pipelines 5. The medium-pressure cylinder steam output pipeline 7 is connected to the heating connecting pipeline 10. A new peak-shaving low-pressure bypass 21 is added between the two medium-pressure cylinder steam input pipelines 6 and the heating connecting pipeline 10. The heating connecting pipeline 10 is connected to the heating pipeline 25. The two medium-pressure cylinder steam input pipelines 6 are connected to the startup low-pressure bypass 18 through the startup low-bypass connecting pipeline 26. The startup low-pressure bypass 18 is connected to the industrial steam extraction pipeline 24;

[0029] b. Open the drain valve from the starting low-pressure bypass 18 to the industrial exhaust pipeline to drain the condensate from the pipeline, slowly open the valve from the starting low-pressure bypass 18 to the industrial exhaust pipeline, and use the desuperheater to ensure that the steam temperature from the starting low-pressure bypass 18 to the industrial exhaust pipeline is less than 300 degrees Celsius, until the industrial exhaust steam flow rate is greater than 40 tons / hour and the exhaust steam pressure is greater than 0.7MPa, meeting the industrial production needs of users;

[0030] c. Start the low-pressure bypass 18 until the opening of the industrial exhaust pipeline valve reaches 70%. If the user demand is still not met, or the pressure ratio of the high-pressure cylinder 1 regulating stage pressure P1 to the medium-pressure cylinder 2 second-stage exhaust pressure P2 is less than 5, open the pipeline drain valve of the peak-shaving high-pressure bypass 15 to drain the condensate in the pipeline, slowly open the pipeline valve of the peak-shaving high-pressure bypass 15, and ensure that the pipeline steam temperature of the peak-shaving high-pressure bypass 15 is between 330 and 350 degrees Celsius through the desuperheater until the industrial extraction flow rate is greater than 70 tons / hour and the extraction pressure is greater than 0.7MPa, meeting the user's industrial production needs;

[0031] d. Open the drain valve from the peak-shaving low-pressure bypass 21 to the heating pipeline 25 to drain the condensate from the pipeline, slowly open the valve from the peak-shaving low-pressure bypass 21 to the heating pipeline 25, and ensure that the steam temperature from the peak-shaving low-pressure bypass 21 to the heating pipeline 25 is less than 200 degrees Celsius through the desuperheater. At the same time, monitor the pressure ratio change. When the pressure ratio is lower than 5.2, open the pipeline valve of the peak-shaving high-pressure bypass 15 to increase the pressure ratio to above 5.7, and then increase the valve opening from the peak-shaving low-pressure bypass 21 to the heating pipeline 25. When the pressure ratio is lower than 5.2 again, open the pipeline valve of the peak-shaving high-pressure bypass 15 again. Repeat this operation to maintain the pressure ratio between 5 and 6 to ensure the pressure matching of the steam turbine unit here, ensure the axial thrust balance of the high and medium pressure cylinder 2 of the steam turbine unit, and ensure the safe operation of the unit until the heat of the heating pipeline 25 is greater than 400GJ / h to meet the user's heating needs;

[0032] e. When the openings of the pipeline valves of the peak-shaving high-pressure bypass 15 and the valves from the peak-shaving low-pressure bypass 21 to the heating pipeline 25 reach more than 90%, but still cannot meet the needs of the heating network users, slowly close the intermediate-pressure cylinder steam inlet regulating valve 27 of the intermediate-pressure cylinder steam input pipeline 6, and monitor the pressure ratio at the same time to keep the pressure ratio between 5 and 6 until the opening of the intermediate-pressure cylinder steam inlet regulating valve 27 is reduced to 30%. If it still cannot meet the needs of heating users, slowly reduce the low-pressure cylinder steam inlet regulating valve 9 until the opening of the low-pressure cylinder steam inlet regulating valve 9 is reduced to 20%, and ensure that the intake pressure of the low-pressure cylinder 3 is greater than 0.01 MPa, so that when the electrical load reaches 25% of the rated installed capacity, the heating heat reaches 600 GJ / h.

[0033] During the peak period of heating supply, the regulating valve in the combined unit is used to supply high-load heat. During the adjustment process, the ratio of the high-pressure cylinder 1 regulating stage pressure P1 to the medium-pressure cylinder 2 second-stage extraction pressure P2 is introduced as an adjustment reference to ensure the axial thrust balance of the high and medium pressure cylinders 2 of the steam turbine unit and to ensure the safe operation of the unit. This concept is proposed for the first time in the industry.

[0034] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A cogeneration system, comprising a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder, wherein the upper and lower steam inlets of the high-pressure cylinder are connected to the upper and lower steam input pipelines of the high-pressure cylinders, the two steam exhaust ports of the high-pressure cylinder are connected to the two steam output pipelines of the high-pressure cylinders, a startup high-pressure bypass is connected between the two high-pressure cylinder steam input pipelines and the two high-pressure cylinder steam output pipelines, the high-pressure cylinder steam output pipeline is connected to the steam inlet of a boiler reheater, the upper and lower steam inlets of the medium-pressure cylinder are connected to the upper and lower steam input pipelines of the medium-pressure cylinders, the steam outlet of the boiler reheater is connected to the medium-pressure cylinder steam input pipeline, the steam exhaust port of the medium-pressure cylinder is connected to the medium-pressure cylinder steam output pipeline, the steam inlet of the low-pressure cylinder is connected to the low-pressure cylinder steam input pipeline, and the medium-pressure cylinder steam output pipeline is connected to the low-pressure cylinder steam input pipeline, characterized in that: A peak-shaving high-pressure bypass is connected between the two high-pressure cylinder steam input pipelines and the two high-pressure cylinder steam output pipelines, the medium-pressure cylinder steam output pipeline is connected to the heating connecting pipeline, a peak-shaving low-pressure bypass is connected between the two medium-pressure cylinder steam input pipelines and the heating connecting pipeline, the heating connecting pipeline is connected to the heating pipeline, the two medium-pressure cylinder steam input pipelines are connected to a starting low-pressure bypass through a starting low-bypass connecting pipeline, and the starting low-pressure bypass is connected to the industrial steam extraction pipeline; the starting high-pressure bypass is provided with a first desuperheater and a starting high bypass valve, the peak-shaving high-pressure bypass is provided with a second desuperheater and a peak-shaving high bypass valve, and the peak-shaving low-pressure bypass is provided with a fourth desuperheater and a peak-shaving low bypass valve; when entering deep peak-shaving, the peak-shaving high-pressure bypass is opened to reduce the turbine intake, and after the peak-shaving low-pressure bypass is opened, the steam is introduced into the heating pipeline for heat supply, and the power generation steam load is transferred to heating.

2. The cogeneration system according to claim 1, characterized in that: The starting low-pressure bypass is provided with a third desuperheater, and the starting low-pressure bypass connecting pipeline is provided with a starting low-pressure bypass valve.

3. The cogeneration system according to claim 2, characterized in that: A low-pressure cylinder steam inlet regulating valve is arranged between the low-pressure cylinder steam input pipeline and the steam inlet of the low-pressure cylinder.

4. The cogeneration system according to claim 3, characterized in that: The heating connection pipeline is provided with a heating connection valve.

5. A method for cogeneration of heat and power, characterized in that It includes the following: a. The startup high-pressure bypass is only used during startup. A new peak-shaving high-pressure bypass is added between the two high-pressure cylinder steam input pipelines and the two high-pressure cylinder steam output pipelines. The medium-pressure cylinder steam output pipeline is connected to the heating connecting pipeline. A new peak-shaving low-pressure bypass is added between the two medium-pressure cylinder steam input pipelines and the heating connecting pipeline. The heating connecting pipeline is connected to the heating pipeline. The two medium-pressure cylinder steam input pipelines are connected to the startup low-pressure bypass through the startup low-bypass connecting pipeline. The startup low-pressure bypass is connected to the industrial steam extraction pipeline. b. Open the drain valve from the low-pressure bypass to the industrial exhaust pipeline to drain the condensate from the pipeline, slowly open the valve from the low-pressure bypass to the industrial exhaust pipeline, and use the desuperheater to ensure that the steam temperature from the low-pressure bypass to the industrial exhaust pipeline is less than 300 degrees Celsius, until the industrial exhaust flow rate is greater than 40 tons / hour and the exhaust pressure is greater than 0.7MPa, meeting the industrial production needs of users; c. Start the low-pressure bypass until the opening of the industrial exhaust pipeline valve reaches 70%. If the user demand is still not met, or the pressure ratio of the high-pressure cylinder regulating stage pressure P1 to the medium-pressure cylinder second-stage exhaust pressure P2 is less than 5, open the pipeline drain valve of the peak-shaving high-pressure bypass to drain the condensate in the pipeline, slowly open the pipeline valve of the peak-shaving high-pressure bypass, and ensure that the pipeline steam temperature of the peak-shaving high-pressure bypass is between 330-350 degrees Celsius through the desuperheater until the industrial extraction flow rate is greater than 70 tons / hour and the extraction pressure is greater than 0.7MPa, meeting the user's industrial production needs; d. Open the drain valve from the peak-shaving low-pressure bypass to the heating pipeline to drain the condensate from the pipeline, slowly open the valve from the peak-shaving low-pressure bypass to the heating pipeline, and ensure that the steam temperature from the peak-shaving low-pressure bypass to the heating pipeline is less than 200 degrees Celsius through the desuperheater. At the same time, monitor the change in the pressure ratio. When the pressure ratio is lower than 5.2, open the pipeline valve of the peak-shaving high-pressure bypass to increase the pressure ratio to above 5.7, and then increase the valve opening from the peak-shaving low-pressure bypass to the heating pipeline. When the pressure ratio is lower than 5.2 again, open the pipeline valve of the peak-shaving high-pressure bypass again. Repeat this operation to maintain the pressure ratio between 5 and 6 to ensure pressure matching at this point of the steam turbine unit, balance the axial thrust of the high- and medium-pressure cylinders of the steam turbine unit, and ensure safe operation of the unit until the heat of the heating pipeline is greater than 400GJ / h to meet the heating needs of users. e. When the openings of the pipeline valves of the peak-shaving high-pressure bypass and the valves from the peak-shaving low-pressure bypass to the heating pipeline reach more than 90%, but still cannot meet the needs of the heating network users, slowly close the steam inlet regulating valve of the medium-pressure cylinder steam input pipeline, and monitor the pressure ratio at the same time to make the pressure ratio between 5 and 6 until the opening of the steam inlet regulating valve is reduced to 30%. If it still cannot meet the needs of heating users, slowly reduce the low-pressure cylinder steam inlet regulating valve until the opening of the low-pressure cylinder steam inlet regulating valve is reduced to 20%, and ensure that the low-pressure cylinder intake pressure is greater than 0.01MPa, so that when the electrical load reaches 25% of the rated installed capacity, the heating heat reaches 600GJ / h.

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