High-low pressure cylinder cutting thermoelectric decoupling mode and system based on exhaust steam built-in group injection

Abstract

The invention provides a high-low pressure cylinder cutting thermoelectric decoupling mode and system based on exhaust steam built-in group injection, and belongs to the technical field of combined heat and power generation and centralized heating. A combined heat and power generation system is provided with an injection decoupling device for high-low pressure cylinder cutting, wherein a high-pressure driving steam inlet of an external high-pressure cylinder cutting injector is connected with a new steam pipe; a low-pressure inlet is connected with a high-pressure cylinder exhaust steam cold re-heating pipe; a medium-pressure exhaust steam port is connected with a boiler reheater inlet; a hot re-heating pipe is provided with a steam extraction port; a built-in low-pressure group injectionpipe bundle is arranged in an exhaust steam communicating pipe between a low-pressure cylinder and a condenser; a high-pressure driving steam inlet of the built-in low-pressure group injection pipe bundle communicates with a hot re-heating steam extraction port or a medium-pressure exhaust steam port; a low-pressure inlet is opened in the exhaust steam communicating pipe; medium-pressure exhaust steam is arranged in a front area of an exhaust steam inlet of the condenser; and a cooling water inlet and a cooling water outlet of the condenser communicate with a heat supply network return water inlet pipe and a heat supply network return water outlet pipe correspondingly and achieve heat supply network return water heating. According to the high-low pressure cylinder cutting thermoelectric decoupling mode and system based on exhaust steam built-in group injection, the near-full load heat supply and power generation adjusting capacity of a steam turbine can be achieved, the cold end loss is eliminated, and the thermal power operation flexibility is improved.

Description

technical field [0001] The invention relates to a high-low pressure cylinder cutting thermoelectric decoupling method and system based on exhaust steam built-in group jet ejection, and belongs to the technical field of cogeneration of heat and power and waste heat recovery and heat supply. Background technique [0002] Due to the inherent characteristics of thermoelectric coupling, traditional cogeneration systems in thermal power plants usually adopt the operation mode of setting heat by heat or electricity. In view of the fact that the current power supply is much higher than the power demand, and the heat supply demand, especially in northern regions The demand for central heating and the demand for industrial steam supply in industrial parks have been growing significantly for a long period of time. Therefore, the National Energy Administration has issued a number of policy measures to promote thermal power decoupling, deep peak shaving, and flexible transformation. The ...

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Problems solved by technology

[0003] The existing thermoelectric decoupling schemes and their main problems are summarized as follows: heat storage schemes and electric boiler schemes occupy a large area and have a large investment scale, and cannot be fully and deeply decoupled; low-pressure cylinder zero output transformation, including optical axis schemes, and direct regulation The scheme of reducing or closing the steam intake of the low-pressure cylinder and introducing a small amount of cooling steam to cool the final stage and the exhaust port has little effect on increasing the heat supply; the scheme of high and low bypass joint steam distribution lies in the low power generation load rate At this time, the inlet steam pressure of the reheater is greatly reduced due to the substantial reduction of the steam intake of the turbine, so that the volume flow rate is greatly increased, and the flow capacity and heat transfer capacity of the reheater are greatly reduced. It is difficult to effectively reduce the smoke temperature of the reheater, resulting in The reheater and the subsequent heating surface are overheated and damaged; cylinder drilling and steam extraction, low-vacuum circulating water heating, etc. cannot effectively reduce the power generation load rate; Drilling holes in the cold section of the reheater (cold re) to extract steam, or drilling holes in the hot section of the outlet of the reheater (hot re) can greatly reduce the load rate of power generation, but it will inevitably exist when the amount of steam extraction is large. A series of safety issues such as reheater overheating and steam turbine axial thrust exceeding the limit

[0004] Using ejector steam pressure matching technology and ejector heat pump exhaust heat recovery technology, a complete thermoelectric decoupling scheme can be realized, including: ejector steam distribution thermoelectric decoupling method based on axial thrust balance and reheat balance ( Application No. 2019110733266), a heat supply method and system based on complete thermoelectric decoupling of ejector heat pump exhaust steam recovery (application No. 2019110728319, a thermoelectric decoupling system based on multi-stage ejector steam distribution and heat pump exhaust steam recovery (patent No. 2019219003781), a deep thermoelectric decoupling system based on axial thrust balance (patent no. , not only to ensure the minimum cooling condition of the low-pressure cylinder, but also to realize the recovery of waste heat from exhausted steam of the low-pressure cylinder and to eliminate the loss of the cold end. The ejector heat pump technology is adopted, but in view of the fact that the exhaust gas of the low-pressure cylinder is often large and its specific volume And the volume flow rate is very large. For the wet cooling unit, it is necessary to use large-diameter pipes to lead the exhaust steam to the place where the low-pressure ejector and heating heater are installed. Because the installation and maintenance space of the steam turbine room is usually compact, it is difficult to have space for piping. Therefore, it is more suitable for air-cooled units rather than wet-cooled units, and the entire ejector heat pump system including ejector and heating heat exchanger occupies a relatively large area and investment

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