Exhaust steam cooling system and exhaust steam cooling method

Abstract

The invention provides an exhaust steam cooling system and an exhaust steam cooling method. During the zero-output heat supply operation of a low-pressure cylinder of a steam turbine, a heat supply butterfly valve arranged on a communicating pipe between a high-pressure cylinder and the low-pressure cylinder is closed, a steam adjusting valve on a cooling steam bypass is opened, a steam inlet valve of an exhaust steam cooler, a condensation water drain valve of the exhaust steam cooler and an evacuation air valve of the exhaust steam cooler are opened, the water inlet valve of the exhaust steam cooler and a water drain valve of the exhaust steam cooler are opened, the water inlet valve of an air condenser, a condensation water drain valve of the air condenser and an air outlet air valve ofthe air condenser are closed, the exhaust steam of a unit enters the exhaust steam cooler for condensation, and the condensed water flows back to a main machine steam discharging device. All steam inlet valves of a steam distribution pipe of the air condenser are closed, the air condenser is isolated, all the exhaust steam of the steam turbine set is introduced into the exhaust steam condenser for condensation, and the condensed water flows back to the main machine steam discharging device, so that the problem of freezing of the air condenser in the zero-output heat supply running process ofthe direct air cooling unit in heat supply season is thoroughly solved.

Description

technical field [0001] The invention belongs to the fields of heat supply, flexibility and safe operation of a thermal power plant, and in particular relates to a exhaust steam cooling system and a exhaust steam cooling method. Background technique [0002] In order to improve the heating capacity of the unit and the deep peak-shaving capability of the heating unit, some units have undergone low-pressure cylinder zero-output heating transformation. The low-pressure cylinder zero-output heating technology transformation cost is low, the operation mode is flexible, and the thermal economy is good. Comprehensive Great advantage. [0003] The zero-output heating technology of the low-pressure cylinder breaks the original theory of the minimum cooling flow limit of the low-pressure cylinder of the steam turbine, cuts off the steam intake of the original low-pressure cylinder during the heating period, and only maintains a small amount of cooling steam by setting the bypass coolin...

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Problems solved by technology

[0004] Direct air-cooled combined heat and power units are widely used in the "Three North" regions of my country. After the direct air-cooled unit low-pressure cylinder has zero output transformation, the steam flow (heat load) entering the air-cooled condenser is theoretically very small, and it is extremely low under low temperature and low heat load conditions. It is easy to freeze the heat exchange tube bundle, which seriously affects the safe and reliable operation of the unit

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