Method for recovering waste heat of thermal power plant and heating and supplying heat to hot water in a stepping way

Abstract

The invention discloses a method for recovering the waste heat of a thermal power plant and heating and supplying heat to hot water in a stepping way. In the method, low-temperature heat-net return water is firstly mixed with circulating cooling water positioned on an outlet of a cooling condenser or exchanges heat with the circulating cooling water positioned on the outlet of the cooling condenser to be increased in temperature and then sequentially delivered into an each-step vapour absorption type heat pump and a vapor-water heat exchanger in a series connection way to be gradually heated to be increased in temperature to heat supplying temperature and finally discharged through a water supplying pipeline; the circulating cooling water absorbs the waste steam condensation heat of a steam turbine in the cooling condenser, then one path of the circulating cooling water is directly mixed with the low-temperature heat-net return water or heats the low-temperature heat-net return water through the heat changer, the other path of the circulating cooling water is delivered into an each-step absorption type heat pump unit to be used as a low-order heat source of the absorption type heat pump unit, and the redundant heat of the circulating cooling water is discharged to the environment through a cooling tower. The invention uses the steam extraction of the steam turbine as a driving heat source of the absorption type heat pump so that the low-temperature heat-net return water is heated in a stepping way, thereby reducing the effective energy loss; the waste heat of the discharged steam of the steam turbine is sufficiently recovered in a direct heating way and an absorption type heat pump temperature increasing heating way, therefore, the comprehensive energy usage efficiency of the thermal power plant is enhanced.

Description

technical field [0001] The invention belongs to the technical field of central heating, and in particular relates to a method for recovering waste heat from thermal power plants and cascading hot water heating. Background technique [0002] In the current combined heat and power plants, the extraction steam of the extraction condensing steam turbine is generally used to directly heat the return water of the heating network in the heating network heater, and it is generally heated to about 120-130°C before being supplied. For this reason, the steam extraction pressure of the steam turbine is required Above 0.3MPa, the corresponding condensation temperature is above 135°C, while the return water of the heating network is generally only about 60°C. It can also be lower, so there is a heat transfer temperature difference as high as 70°C at the inlet end of the heating network heater, resulting in a large loss of effective energy, which does not conform to the principle of energy...

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Problems solved by technology

[0002] In the current combined heat and power plants, the extraction steam of the extraction condensing steam turbine is generally used to directly heat the return water of the heating network in the heating network heater, and it is generally heated to about 120-130°C before being supplied. For this reason, the steam extraction pressure of the steam turbine is required Above 0.3MPa, the corresponding condensation temperature is above 135°C, while the return water of the heating network is generally only about 60°C. It can also be lower, so there is a heat transfer temperature difference of up to 70°C at the inlet of the heating network heater, resulting in a large loss of effective energy, which does not conform to the principle of energy cascade utilization

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