A heat network circulating water system and regulation method for a combined heat and power unit

Abstract

A heat network circulating water system and a regulation method for a cogeneration unit. The heat network circulating water system includes a feed water pump steam turbine and a boiler feed water pump and a heat network circulating water pump arranged coaxially. The boiler feed water pump is connected in the boiler water supply pipeline, and the heat network circulating water pump is connected in the heat network circulating water supply pipeline; the boiler feed water pump and the heat network circulating water pump are jointly driven by the feed water pump steam turbine to simultaneously realize boiler water supply and heat network circulating water supply. The regulation method includes that when the outlet flow rate of the heat network circulating water pump is less than the total flow rate of the heat network circulating water, start the standby heat network circulating water pump, open the outlet valve of the standby heat network circulating water pump, and by adjusting the scoop tube opening of the hydraulic coupling, make the sum of the outlet flow rate of the heat network circulating water pump and the outlet flow rate of the standby heat network circulating water pump meet the requirement of the total flow rate of the heat network circulating water. The invention reduces the equipment investment cost and the infrastructure investment of the heat network primary station.

Description

Technical Field

[0001] The present invention belongs to the field of heat supply energy conservation in thermal power plants, and relates to a heat network circulating water system and an adjustment method for a cogeneration unit. Background Art

[0002] The driving modes of the heat network circulating water pumps in cogeneration power plants include motor drive and steam turbine drive. Among them, the structure of the electric heat network circulating water pump system is simple and convenient for maintenance, but the plant power consumption rate and power supply coal consumption are relatively high. The driving steam source of the steam-driven heat network circulating water pump is mostly led from the main engine extraction steam pipeline. A part of the steam extracted from the main engine heater enters the steam turbine of the heat network circulating water pump, drives the heat network circulating water pump to rotate, and the exhaust steam enters the steam side system of the heat network heater. Compared with the motor drive, the steam-driven heat network circulating water pump can reduce the plant power consumption rate and power supply coal consumption. However, at present, a small steam turbine is separately set at the heat network first station and is not coupled with the main engine feed water pump steam turbine. Designing a separate steam turbine for the heat network circulating water pump not only requires supporting extraction steam pipelines, exhaust steam pipelines, and lubricating oil systems, but also requires regular maintenance of the oil system. The site infrastructure cost, equipment investment cost, and maintenance cost are relatively high. Summary of the Invention

[0003] The purpose of the present invention is to provide a heat network circulating water system and an adjustment method for a cogeneration unit, aiming at the problems of high heat supply plant power consumption rate, site infrastructure cost, equipment investment cost, and maintenance cost in the above-mentioned existing technology, effectively reducing the heat supply plant power consumption rate and the investment cost of the heat supply first station, and at the same time reducing the equipment maintenance amount during the maintenance period.

[0004] To achieve the above purpose, the present invention has the following technical solutions:

[0005] A heat network circulating water system for a cogeneration unit includes a feed water pump steam turbine and a boiler feed water pump and a heat network circulating water pump arranged coaxially. The boiler feed water pump is connected to the boiler water supply pipeline, and the heat network circulating water pump is connected to the heat network circulating water supply pipeline; the boiler feed water pump and the heat network circulating water pump are jointly driven by the feed water pump steam turbine to realize boiler water supply and heat network circulating water supply at the same time.

[0006] As a preferred scheme of the heat network circulating water system of the present invention for a cogeneration unit, the boiler feed water pump is connected to the deaerator. A part of the fourth extraction steam from the medium-pressure cylinder of the steam turbine is sent into the deaerator through the fourth extraction steam pipeline, and another part of the fourth extraction steam is sent into the water pump steam turbine. The exhaust steam of the water pump steam turbine enters the condenser.

[0007] As a preferred scheme of the heat network circulating water system of the present invention for a cogeneration unit, the water pump steam turbine is provided with an inlet steam control valve, and adjusting the opening degree of the inlet steam control valve can adjust the speed of the water pump steam turbine.

[0008] As a preferred embodiment of the heat network circulating water system of the cogeneration unit of the present invention, the heat network circulating water pump and the feed water turbine are connected by an automatic synchronous clutch.

[0009] As a preferred embodiment of the heat network circulating water system of the cogeneration unit of the present invention, a standby heat network circulating water pump is provided in the heat network circulating water supply pipeline. The standby heat network circulating water pump is connected in parallel with the heat network circulating water pump, and the standby heat network circulating water pump is connected to the standby heat network circulating water pump motor through a hydraulic coupling.

[0010] As a preferred embodiment of the heat network circulating water system of the cogeneration unit of the present invention, a heat network circulating water return main valve, a heat network circulating water pump inlet valve, a heat network circulating water pump, a heat network circulating water pump outlet valve, and a heat network circulating water supply main valve are sequentially arranged in the heat network circulating water supply pipeline according to the flow direction.

[0011] As a preferred embodiment of the heat network circulating water system of the cogeneration unit of the present invention, both ends of the standby heat network circulating water pump are respectively connected to one end of the standby heat network circulating water pump inlet valve and the standby heat network circulating water pump outlet valve. The other end of the standby heat network circulating water pump inlet valve is connected between the heat network circulating water return main valve and the heat network circulating water pump inlet valve, and the other end of the standby heat network circulating water pump outlet valve is connected between the heat network circulating water pump outlet valve and the heat network circulating water supply main valve.

[0012] As a preferred embodiment of the heat network circulating water system of the cogeneration unit of the present invention, the heat network circulating water return main valve, the heat network circulating water pump inlet valve, the standby heat network circulating water pump inlet valve, the heat network circulating water pump outlet valve, the standby heat network circulating water pump outlet valve, and the heat network circulating water supply main valve are all electric valves.

[0013] As a preferred embodiment of the heat network circulating water system of the cogeneration unit of the present invention, the heat network circulating water pump inlet valve and the standby heat network circulating water pump inlet valve are electric globe valves and are always open during the operation of the system; the heat network circulating water pump outlet valve and the standby heat network circulating water pump outlet valve are electric regulating valves, and the opening degrees are adjusted according to the output changes of the heat network circulating water pump and the standby heat network circulating water pump during the operation of the system.

[0014] The present invention also provides a regulation method for the heat network circulating water system of the cogeneration unit, including:

[0015] - When the outlet flow rate of the heat network circulating water pump is less than the total flow rate of the heat network circulating water, start the standby heat network circulating water pump, open the standby heat network circulating water pump outlet valve, and adjust the scoop tube opening degree of the hydraulic coupling so that the sum of the outlet flow rate of the heat network circulating water pump and the outlet flow rate of the standby heat network circulating water pump meets the requirement of the total flow rate of the heat network circulating water;

[0016] - When the outlet flow rate of the heat network circulating water pump is greater than the total flow rate of the heat network circulating water, stop the standby heat network circulating water pump, close the outlet valve of the standby heat network circulating water pump, and adjust the opening degree of the outlet valve of the heat network circulating water pump to meet the requirements of the total flow rate of the heat network circulating water.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] By arranging the heat network circulating water pump and the boiler feed water pump coaxially and jointly driving them by the feed water turbine, the equipment investment cost is reduced, and the capital construction investment of the heat network primary station is reduced. The present invention does not require an additional heat network circulating water pump turbine, reducing the equipment maintenance amount during maintenance. The system of the present invention is simple and reliable, compact in structure, and low in operation and maintenance costs.

[0019] Furthermore, a standby heat network circulating water pump is provided in the heat network circulating water supply pipeline. The standby heat network circulating water pump is connected in parallel with the heat network circulating water pump, which can maintain the stability of the heat network circulating water flow rate and pressure while reducing the equipment cost.

[0020] Compared with the prior art, the regulation method of the heat network circulating water system of the present invention's cogeneration unit can ensure the stability of the heat network circulating water flow rate and pressure by adjusting the opening degree of the hydraulic coupling scoop tube and the opening degree of the electric control valve at the pump outlet, and the operation is convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Structural schematic diagram of the heat network circulating water system of the present invention's cogeneration unit;

[0022] In the drawings: 1 - Intermediate pressure cylinder of the steam turbine; 2 - Four - extraction steam pipeline; 3 - Feed water turbine; 4 - Boiler feed water pump; 5 - Heat network circulating water pump; 6 - Standby heat network circulating water pump; 7 - Hydraulic coupling; 8 - Motor of the standby heat network circulating water pump; 9 - Total return valve of the heat network circulating water; 10 - Inlet valve of the heat network circulating water pump; 11 - Inlet valve of the standby heat network circulating water pump; 12 - Outlet valve of the heat network circulating water pump; 13 - Outlet valve of the standby heat network circulating water pump; 14 - Total supply valve of the heat network circulating water; 15 - Low - pressure cylinder of the steam turbine; 16 - Automatic synchronous clutch; 17 - Deaerator. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The following further describes the present invention in detail with reference to the drawings and embodiments.

[0024] See Figure 1, the heat network circulating water system of the cogeneration unit of the present invention includes a feed water turbine 3 and a boiler feed water pump 4 and a heat network circulating water pump 5 arranged coaxially. The boiler feed water pump 4 is connected to the boiler water supply pipeline, and the heat network circulating water pump 5 is connected to the heat network circulating water supply pipeline; a standby heat network circulating water pump 6 is arranged in the heat network circulating water supply pipeline. The standby heat network circulating water pump 6 is connected in parallel with the heat network circulating water pump 5, and the standby heat network circulating water pump 6 is connected to a standby heat network circulating water pump motor 8 through a hydraulic coupling 7. In the heat network circulating water supply pipeline, a total return valve 9 of the heat network circulating water, an inlet valve 10 of the heat network circulating water pump, the heat network circulating water pump 5, an outlet valve 12 of the heat network circulating water pump, and a total feed valve 14 of the heat network circulating water are arranged in sequence according to the flow direction. Both ends of the standby heat network circulating water pump 6 are respectively connected to one end of a standby heat network circulating water pump inlet valve 11 and a standby heat network circulating water pump outlet valve 13. The other end of the standby heat network circulating water pump inlet valve 11 is connected between the total return valve 9 of the heat network circulating water and the inlet valve 10 of the heat network circulating water pump, and the other end of the standby heat network circulating water pump outlet valve 13 is connected between the outlet valve 12 of the heat network circulating water pump and the total feed valve 14 of the heat network circulating water. The boiler feed water pump 4 and the heat network circulating water pump 5 are jointly driven by the feed water turbine 3 to simultaneously realize boiler water supply and heat network circulating water supply. When the unit load changes, the feed water turbine 3 will change its speed to ensure the boiler water supply requirements, and the outlet flow rate of the heat network circulating water pump 5 will change accordingly. Therefore, a standby heat network circulating water pump 6 connected in parallel with the heat network circulating water pump 5 is provided.

[0025] The heat network circulating water pump 5 is connected to the feed water turbine 3 through an automatic synchronous clutch 16.

[0026] The feed water turbine 3 is provided with an inlet steam control valve. By controlling the opening of the inlet steam control valve, the speed of the feed water turbine 3 can be adjusted. The boiler feed water pump 4 is connected to the deaerator 17. A part of the extraction steam from the middle pressure cylinder 1 of the steam turbine is sent into the deaerator 17 through the four - extraction steam pipeline 2, and another part of the extraction steam is sent into the feed water turbine 3. The exhaust steam of the feed water turbine 3 enters the condenser.

[0027] The inlet steam pressure of the feed water turbine 3 is determined by the parameters of the extraction steam of the steam turbine. The speed of the feed water turbine 3 is controlled with the goal of meeting the boiler water supply pressure and flow rate. The control method is to adjust the opening of the inlet steam control valve of the feed water turbine 3.

[0028] As the unit load changes, the outlet circulating water flow rate of the heat network circulating water pump 5 will change accordingly. In order to ensure the stability of the heat network circulating water supply flow rate and pressure in the system of the present invention, the standby heat network circulating water pump 6 is provided with a hydraulic coupling 7 to change along with the speed of the feed water turbine 3, and then the output of the hydraulic coupling 7 is changed in real time.

[0029] The present invention controls the opening and closing of pipelines in the system through multiple control valves. Among them, the total return valve 9 of the heat network circulating water, the inlet valve 10 of the heat network circulating water pump, the inlet valve 11 of the standby heat network circulating water pump, the outlet valve 12 of the heat network circulating water pump, the outlet valve 13 of the standby heat network circulating water pump, and the total feed valve 14 of the heat network circulating water all adopt electric valves. Further, the inlet valve 10 of the heat network circulating water pump and the inlet valve 11 of the standby heat network circulating water pump are electric globe valves and are always open during the operation of the system; the outlet valve 12 of the heat network circulating water pump and the outlet valve 13 of the standby heat network circulating water pump are electric regulating valves, and the opening degrees are adjusted according to the output changes of the heat network circulating water pump 5 and the standby heat network circulating water pump 6 during the operation of the system.

[0030] The present invention also provides a regulation method for the heat network circulating water system of the above-mentioned cogeneration unit, including the following steps:

[0031] - When the outlet flow rate of the heat network circulating water pump 5 is less than the total flow rate of the heat network circulating water, start the standby heat network circulating water pump 6, open the outlet valve 13 of the standby heat network circulating water pump, and by adjusting the scoop tube opening degree of the hydraulic coupler 7, make the sum of the outlet flow rates of the heat network circulating water pump 5 and the standby heat network circulating water pump 6 meet the requirements of the total flow rate of the heat network circulating water;

[0032] - When the outlet flow rate of the heat network circulating water pump 5 is greater than the total flow rate of the heat network circulating water, stop the standby heat network circulating water pump 6, close the outlet valve 13 of the standby heat network circulating water pump, and by adjusting the opening degree of the outlet valve 12 of the heat network circulating water pump, meet the requirements of the total flow rate of the heat network circulating water.

[0033] The present invention arranges the heat network circulating water pump 5 and the boiler feed water pump 4 coaxially and is jointly driven by the water pump steam turbine 3, thereby reducing the equipment investment cost of the heat network circulating water pump steam turbine and the steam pipeline, reducing the operation and maintenance cost and overhaul and maintenance cost of the heat network circulating water pump steam turbine, and also reducing the area of the heat network first station and the infrastructure investment cost.

[0034] The specific embodiments described above do not limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the technical solution of the present invention shall be included in the protection scope of the present invention.

Claims

1. A heat network circulating water system for a combined heat and power unit, characterized in that: It includes a boiler feed pump steam turbine (3), a boiler feed pump (4) and a heat network circulating water pump (5) arranged coaxially. The boiler feed pump (4) is connected to the boiler water supply pipeline, and the heat network circulating water pump (5) is connected to the heat network circulating water supply pipeline; the boiler feed pump (4) and the heat network circulating water pump (5) are jointly driven by the boiler feed pump steam turbine (3) to simultaneously realize boiler water supply and heat network circulating water supply; the heat network circulating water pump (5) is connected to the boiler feed pump steam turbine (3) through an automatic synchronous clutch (16); a standby heat network circulating water pump (6) is arranged in the heat network circulating water supply pipeline. The standby heat network circulating water pump (6) is connected in parallel with the heat network circulating water pump (5). The standby heat network circulating water pump (6) is connected to a standby heat network circulating water pump motor (8) through a hydraulic coupling (7). By adjusting the scoop tube opening of the hydraulic coupling (7), the sum of the outlet flow of the heat network circulating water pump (5) and the outlet flow of the standby heat network circulating water pump (6) meets the requirement of the total heat network circulating water flow.

2. The heat network circulating water system for a combined heat and power unit according to claim 1, characterized in that: The boiler feed pump (4) is connected to the deaerator (17). A part of the fourth extraction steam from the intermediate pressure cylinder (1) of the steam turbine is sent into the deaerator (17) through the fourth extraction steam pipeline (2), and another part of the fourth extraction steam is sent into the boiler feed pump steam turbine (3). The exhaust steam of the boiler feed pump steam turbine (3) enters the condenser.

3. The heat network circulating water system for a combined heat and power unit according to claim 2, characterized in that: The boiler feed pump steam turbine (3) is provided with an inlet steam control valve. By controlling the opening of the inlet steam control valve, the speed of the boiler feed pump steam turbine (3) can be adjusted.

4. The heat network circulating water system for a combined heat and power unit according to claim 1, characterized in that: In the heat network circulating water supply pipeline, a heat network circulating water return main valve (9), a heat network circulating water pump inlet valve (10), a heat network circulating water pump (5), a heat network circulating water pump outlet valve (12) and a heat network circulating water supply main valve (14) are arranged in sequence according to the flow direction.

5. The heat network circulating water system for a combined heat and power unit according to claim 4, characterized in that: Both ends of the standby heat network circulating water pump (6) are respectively connected to one end of a standby heat network circulating water pump inlet valve (11) and a standby heat network circulating water pump outlet valve (13). The other end of the standby heat network circulating water pump inlet valve (11) is connected between the heat network circulating water return main valve (9) and the heat network circulating water pump inlet valve (10). The other end of the standby heat network circulating water pump outlet valve (13) is connected between the heat network circulating water pump outlet valve (12) and the heat network circulating water supply main valve (14).

6. The heat network circulating water system for a combined heat and power unit according to claim 5, characterized in that: The heat network circulating water return main valve (9), the heat network circulating water pump inlet valve (10), the standby heat network circulating water pump inlet valve (11), the heat network circulating water pump outlet valve (12), the standby heat network circulating water pump outlet valve (13) and the heat network circulating water supply main valve (14) are all electric valves.

7. The heat network circulating water system for a combined heat and power unit according to claim 6, characterized in that: The heat network circulating water pump inlet valve (10) and the standby heat network circulating water pump inlet valve (11) are electric globe valves and are always open during system operation; the heat network circulating water pump outlet valve (12) and the standby heat network circulating water pump outlet valve (13) are electric regulating valves and their openings are adjusted according to the output changes of the heat network circulating water pump (5) and the standby heat network circulating water pump (6) during system operation.

8. A regulating method for the heat network circulating water system for a combined heat and power unit according to claim 5, characterized in that: - When the outlet flow rate of the heat network circulating pump (5) is less than the total flow rate of the heat network circulating water, start the standby heat network circulating pump (6), open the outlet valve (13) of the standby heat network circulating pump, and by adjusting the scoop tube opening of the hydraulic coupling (7), make the sum of the outlet flow rate of the heat network circulating pump (5) and the outlet flow rate of the standby heat network circulating pump (6) meet the requirement of the total flow rate of the heat network circulating water; - When the outlet flow rate of the heat network circulating pump (5) is greater than the total flow rate of the heat network circulating water, stop the standby heat network circulating pump (6), close the outlet valve (13) of the standby heat network circulating pump, and by adjusting the opening of the outlet valve (12) of the heat network circulating pump, meet the requirement of the total flow rate of the heat network circulating water.

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