Steam condensing and backpressure switchable steam turbine power generation system and using method thereof

Abstract

The invention discloses a steam condensing and backpressure switchable steam turbine power generation system and a using method thereof. The system comprises a generator, a medium-high pressure cylinder and a low-pressure cylinder, wherein the generator is coaxially connected to the medium-high pressure cylinder, and a rotating shaft of the medium-high pressure cylinder is connected with a rotating shaft of the low-pressure cylinder through a clutch; a steam exhaust port of the medium-high pressure cylinder is provided with a first branch and a second branch, the first branch communicates witha steam inlet of the low-pressure cylinder, and the second branch can be communicated with a heating network heater; when the clutch is closed, the first branch is communicated, the second branch isdisconnected, and the system is in a non-heating season pure condensing power generation mode; when the clutch is closed, the first branch and the second branch are both communicated, and the system is in a heating season condensing heat supply mode; and when the clutch and the first branch are both disconnected, the second branch is communicated, and the system is in a heating season pure backpressure heat supply mode. The system and the using method thereof are simple and reliable, efficient utilization of energy for heat supply and power generation in winter is guaranteed, flexible adjustment of a unit is realized, and meanwhile, normal operation of the unit in the non-heating season is guaranteed.

Description

technical field [0001] The invention relates to the technical field of thermoelectricity, in particular to a steam turbine power generation system with switchable steam condensation and back pressure and a use method thereof. Background technique [0002] In the cogeneration steam turbine generator set, the back pressure machine is widely used because it eliminates the cold source loss of the condenser, has high thermal cycle efficiency, reduces coal consumption for power generation and heat supply, and saves energy. However, the back pressure machine also has the following disadvantages: poor adaptability to load changes, and the power generation of the unit is subject to changes in thermal load. When the heat load is low, the efficiency of the steam turbine decreases, thereby reducing the economic benefits; and the back-pressure unit cannot operate normally due to the lack of heat users in the non-heating season, causing the unit to be idle in the non-heating season. [0...

AI Technical Summary

Problems solved by technology

However, the back pressure machine also has the following disadvantages: poor adaptability to load changes, and the power generation of the unit is subject to changes in thermal loads

The system has the following problems: when switching between the two operating modes, the low-pressure cylinder rotor needs to replace the connecting shaft, which requires a large workload and high installation requirements; in addition, when the back press is in the heating operation mode, an exhaust fan needs to be installed to cool the low-pressure cylinder. increase energy consumption

[0004] In the prior art, there is also a condensing and pumping back heating system with multiple low-pressure cylinders. The system is relatively complicated and mainly operates in two modes: one is the condensing mode: a part of the steam is supplied from the steam extraction pipe at the exhaust port of the medium-pressure cylinder Heating network heater, at the same time, another part of the exhaust steam of the medium pressure cylinder enters the low pressure cylinder through the medium pressure connecting pipe to do work and then enters the condenser for condensation and recovery; the other is the back pressure heating mode: most of the exhaust steam of the medium pressure cylinder The steam is supplied to the heating network heater through the pipeline, the valve on the medium-pressure connecting pipe is closed, the low-pressure cylinder no longer works, and only a small amount of low-pressure steam is passed into the low-pressure cylinder for cooling.

The system has the following problems: the system is relatively complex, and the low-pressure cylinder is cooled during back pressure heating, and a pressure matcher, a steam cooler, a steam heater and multiple valves need to be installed to adapt to the variable operating conditions of the system

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