Combined heat supply system for recovering waste heat of thermal power plant deeply with zero power of low pressure cylinder

Abstract

The invention discloses a combined heat supply system for recovering waste heat of a thermal power plant deeply with zero power of a low pressure cylinder. A primary heat supply network water return pipe is connected to the inlet of an absorption heat pump evaporator through a pipeline, a driving heat source is extracted steam of a steam turbine and a low position heat source is primary heat supply network return water; the primary heat supply network return water is primarily heated in a high back pressure condenser of a #1 machine; an absorption waste heat recovery unit heats the primary heat supply network return water secondarily; the primary heat supply network return water is heated thirdly in an absorption heat pump absorber and a absorption heat pump condenser; the primary heat supply network return water is heated fourthly in a peak heater; and the outlet of the peak heater is connected to a primary heat supply network water supply pipeline. By utilizing extracted steam afterlow zero transformation of the lower pressure cylinder gradiently, the utilization ratio of energy sources is improved greatly. Under the circumstance of simultaneous operation of a high back pressureunit and a low pressure cylinder zero force unit, no cold source loss is available and flue gas waste heat of a boiler and waste heat of cooling water of an auxiliary machine can be recovered effectively, so that the waste heat in the power plant is recovered to the maximum extent; the external heating capacity is increased, and the advantage of a low heat supply cost of the high back pressure unit is exerted fully.

Description

technical field [0001] The invention relates to the field of cogeneration waste heat recovery, in particular to a combined heat supply system for deep recovery of waste heat from a thermal power plant with zero output of a low-pressure cylinder. Background technique [0002] In 2016, the urban heating area in northern my country reached 14.1 billion square meters, of which the urban centralized heating area exceeded 7 billion square meters. Heating energy consumption exceeds 180 million tons of standard coal (coal accounts for about 90%), which not only consumes a lot of energy, but also brings serious environmental problems. Coal-burning waste gas emissions during the heating season are the cause of winter haze weather disasters in northern my country. One of the main causes. [0003] At present, the return water temperature of the primary heating network circulating water in the northern region is mostly around 50-60°C. The traditional steam turbine generator set adopts h...

AI Technical Summary

Problems solved by technology

New large-scale central heating heat source projects have high investment and long construction period, and are often difficult to carry out due to environmental capacity and other factors; developing small coal-fired heat sources will seriously pollute the atmosphere; developing gas heat sources and electric heat sources has high comprehensive costs and Restricted by the supply of gas and electricity; the development of groundwater source heat pumps and soil source heat pumps is restricted by local hydrogeological conditions, and because the current heat pump heating system has a small temperature difference in transmission, the investment is high and the operating costs are also high

[0011] The outstanding problems and urgent needs in the current central heating system and power production system, the essence of the lack of heat in central heating is the lack of low-grade heat sources and the reasonable matching of high-grade and low-grade heat; the low heat utilization efficiency in the power production process is due to the proportion of low-grade heat High, difficult to be utilized by the power sector itself

[0012] How to integrate and utilize the high back pressure heating transformation of thermal power plants, zero output transformation of low pressure cylinders, deep recovery of flue gas waste heat, and waste heat recovery and utilization of auxiliary machine circulating cooling water to maximize benefits technically requires economical and effective Solve these problems: first, the return water temperature of the primary heating network is not low enough, and the heating company has no willingness and motivation to reduce the return water temperature, so it is necessary to take measures to actively reduce the return water temperature in the thermal power plant; second, the matching of heat load, low pressure The extracted steam after zero-efficiency transformation of cylinders is used for heating. The steam used is of high grade and low energy utilization rate, resulting in high energy and low utilization. The grade after heating by the heat pump is equivalent to the grade of the outlet temperature of the high back pressure condenser, but limited by the heating area of ​​the external network, the potential for increasing the circulating water volume of the heating network is limited

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