Control method for steam thermal system with dual-machine backheating steam extraction

Abstract

The invention provides a control method for a steam thermal system with dual-machine backheating steam extraction. When the pressure of a deaerator is lower than the steam extraction pressure at a heat supply steam extraction port of a deaerator on a main steam turbine, a first steam extraction control valve is opened; when the pressure of the deaerator is higher than the steam extraction pressure at the heat supply steam extraction port of the deaerator on the main steam turbine, the first steam extraction control valve is closed and a steam exhaust control valve is opened. According to the control method, the deaerator is connected with a small steam turbine exhaust pipe and a heat supply steam extraction port of the deaerator on a large steam turbine respectively; through controlling the switches of corresponding control valves, on one hand, synchronisms of the pressure of the deaerator and the steam extraction pressure at the heat supply steam extraction port of the deaerator on the large steam turbine under different running conditions are ensured, and on the other hand, the balance of backheating steam extraction flow is achieved on the premise that the output balance between the small steam turbine and the system auxiliary equipment is ensured. Therefore, by adopting the control method, the balance of the backheating steam extraction flow is ensured, and the small steam turbine is enabled to work safely and stably for a long time.

Description

technical field [0001] The invention relates to the field of steam turbines, in particular to a control method for a steam extraction heat recovery thermal system using a small steam turbine. Background technique [0002] Electricity is the most basic, cleanest, and most convenient energy source for human society. Due to the current situation of the earth's primary energy sources, the pattern of coal-fired power generation in the electric power industry will not change for a long period of time. Coal-fired power generation produces clean energy and electricity, but also produces a lot of pollution and CO 2 Emissions, CO calculated based on my country's coal-fired power generation in 2011 2 Emissions have exceeded 3 billion tons. In order to protect the environment and save resources, how to improve the efficiency of steam turbines has become an issue that the industry pays more and more attention to. [0003] In order to improve the efficiency of steam turbines, currently...

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Problems solved by technology

However, the steam of this small steam turbine directly enters the recuperation system from its exhaust end, and the scheme is single. The flow rate of the small steam turbine is limited by the demand of the deaerator. Cycle efficiency and the function of reducing the temperature of the high-pressure heater system. When the small steam turbine is configured according to the power of the driving equipment, when the load changes, the thermal system has no corresponding back pressure control function, the heat balance flow is unbalanced, and the safety of the small steam turbine is unstable. It is possible It will adversely affect the stability and reliability of power plant operation

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