NCB heat supply system based on two units and adjustment method

Abstract

The invention relates to a NCB heat supply system based on two units and an adjustment method. According to the NCB heat supply system based on the two units and the adjustment method, the utilizationefficiency of energy of the system can be improved through gradient utilization of the energy. The heat supply system comprises a first cogeneration unit, a second cogeneration unit and a cooling steam system; the cooling steam system is provided with a pressure reducing device and a temperature reducing device; the first cogeneration unit is provided with the cooling steam system; a steam inletof a cooling steam pipe is connected to a regenerative extraction opening of a low-pressure cylinder of the second cogeneration unit; and a steam outlet of the cooling steam pipe is connected to a steam inlet of a low-pressure cylinder and the regenerative extraction opening of the low-pressure cylinder of the second cogeneration unit. The NCB heat supply system based on the two units and the adjustment method have the advantages that indirect heat exchange is used for reducing the temperature of cooling steam, and therefore the quality of the cooling steam can be guaranteed; and regenerativeextraction steam of the other steam turbine low-pressure cylinder after applying work serves as a steam source for the cooling steam, and therefore irreversible loss caused by temperature reduction and pressure reduction of the cooling steam can be reduced, the reliability of the cooling steam source can be guaranteed, and the safety of the operation without steam inlet of the steam turbine low-pressure cylinders can be improved.

Description

technical field [0001] The invention belongs to the technical field of cogeneration of heat and power, and in particular relates to a two-unit-based condensing-pumping back heating system and an adjustment method, and is especially suitable for a thermal power plant with two units. Background technique [0002] At present, my country's policies are gradually emphasizing the promotion of new energy sources and reducing the proportion of thermal power units. For thermal power plants, the exhaust steam of the steam turbine is usually discharged directly through air cooling or water cooling, which causes a huge loss at the cold end. For example, the energy utilization rate of a 300MW subcritical pure condensing unit is about 38%, of which the loss at the cold end accounts for about 45%. After using steam extraction for heating, the energy utilization rate of the unit increases to 60%, but there is still 20% of condensing low-temperature waste heat This part of the heat is diffi...

AI Technical Summary

Problems solved by technology

For thermal power plants, the exhaust steam of the steam turbine is usually discharged directly through air cooling or water cooling, which causes a huge loss at the cold end

For example, the energy utilization rate of a 300MW subcritical pure condensing unit is about 38%, of which the loss at the cold end accounts for about 45%. After using steam extraction for heating, the energy utilization rate of the unit increases to 60%, but there is still 20% of condensing low-temperature waste heat is discharged, this part of the heat is difficult to use directly due to its low grade

At the same time, as the power grid accommodates new energy power, the requirements for thermal power flexibility of coal-fired power units continue to increase. Coal-fired power units need to achieve ultra-low load operation in order to meet the peak-shaving demand of the power grid, which brings coal-fired thermal power units. great challenge

[0003] At present, the Chinese patent application number 201711165679.X discloses "a cooling system and working method for cutting off the heat supply of the low-pressure cylinder", which realizes the effective cooling of the low-pressure cylinder when the low-pressure cylinder does not enter steam, and directly uses the medium-pressure Cylinder exhaust steam is used as cooling steam. Because the temperature and pressure parameters are too high, it is necessary to reduce the temperature and pressure first, which causes irreversible losses to a certain extent. steam quality

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