A low-pressure cylinder-cutting-cylinder heating unit with low-addition heat recovery system

Abstract

The present invention is in the technical field of thermal power generation, and specifically discloses a low-pressure cylinder-cutting-cylinder heat supply unit with a low-charge and heat-regeneration system, comprising a medium-pressure cylinder, a low-pressure cylinder connected to the medium-pressure cylinder through a communication pipe, and a low-pressure cylinder connected to the medium-pressure cylinder. system, a drainage system connected with the low-addition system, and a deaerator connected with the medium-pressure cylinder; the input end of the deaerator is connected with the low-addition system. The invention not only increases the inlet water temperature entering the deaerator, operates according to the capacity of the original deaerator to ensure the deaerator capacity; it also reduces the steam extraction volume of the deaerator stage (high energy level) correspondingly, and uses more medium pressure cylinders The extraction steam volume of exhaust steam (low energy level) improves the economy of unit operation.

Description

technical field [0001] The invention relates to the technical field of thermal power generation, and more particularly, to a low-addition heat recovery system for a low-pressure cylinder-cutting-cylinder heating unit. Background technique [0002] In the conventional thermal power unit, after the low-pressure cylinder cuts the cylinder for heat supply, the low-pressure cylinder is cut off, and the extraction and recuperation part of the low-pressure cylinder is also cut off accordingly. pressure. [0003] During operation, due to the low back pressure operation of the low-pressure cylinder, and the supplementary water for heating extraction steam is supplemented into the condenser, due to the very small exhaust steam volume of the steam turbine, the newly supplemented chemical water cannot be sufficiently reheated, and the condenser The condensed water has the characteristics of low water temperature, large subcooling degree and high oxygen content; during the operation of ...

AI Technical Summary

Problems solved by technology

[0003] During operation, due to the low back pressure operation of the low-pressure cylinder, at the same time, the make-up water for heating and extracting steam is added to the condenser. Since the exhaust steam of the steam turbine is very small, the newly added chemical water cannot be sufficiently reheated, and the condenser The condensed water has the characteristics of low water temperature, high degree of subcooling, and high oxygen content; during the operation of the recuperation system, due to the cylinder cutting condition, there is no regenerative heat from the partial extraction of the low-pressure cylinder, and the condensed water enters the medium-pressure The temperature of the extraction heater in the cylinder exhaust section is low, and the heat load of the heater is large, resulting in a large extraction volume of the low-pressure heater at this stage and a high flow rate of the pipeline. At the same time, due to the large heat load required, the area of ​​the original heater is seriously insufficient , resulting in a large difference at the outlet of the heater; not only affects the heat exchange effect of the next-stage hybrid heater (deaerator), the outlet temperature of the deaerator is low, but also due to the large supercooling degree of the condensed water in the deaerator, the deaerator Oxygen removal is not complete, and the oxygen content of the condensed water is high; the high oxygen content of the condensed water will deteriorate the heat transfer of the subsequent surface heat exchanger and reduce the thermal economy of the unit; at the same time, it will also cause corrosion of thermal equipment and its pipelines, The dissolved carbon dioxide will also intensify the corrosion of oxygen

Images