Peak-load-regulating heat supply system of thermoelectric unit

Abstract

The invention discloses a peak-load-regulating heat supply system of a thermoelectric unit. The peak-load-regulating heat supply system comprises a turbine high-pressure cylinder, a boiler, a cold reheated steam pipeline, a steam turbine middle-pressure cylinder and a reheated steam pipeline, wherein a coal economizer is arranged on the boiler; the coal economizer is connected with an SCR denitrification system; a steam outlet of the boiler is further connected with a reheated steam heat-supply branch; and a bypass water-feeding pipeline is arranged between an inlet header of the coal economizer and an outlet header of the coal economizer. The peak-load-regulating heat supply system disclosed by the invention solves the problems that industrial steam consumption parameter requirements cannot be met under a low-load working condition and steam inlet amount of a steam turbine low-pressure cylinder is small by utilizing a high-parameter heat supply steam source, reduces heat release amount of smoke gas in the coal economizer, guarantees that SCR equipment does not exit operation, guarantees that the thermoelectric unit can operate under relatively low load, and improves peak-regulating capacity of the thermoelectric unit.

Description

technical field [0001] The invention relates to a heat supply system for peak regulation of thermoelectric units, which belongs to the field of peak regulation of thermoelectric units. Background technique [0002] With the rapid development of social economy, the peak-to-valley difference of power load in my country's power system has been increasing, and the duration has also become longer, and the difficulty of peak regulation in the power grid has increased; in recent years, wind power, hydropower, nuclear power and various new energy sources The proportion of power generation continues to increase. These new energy sources are basically unable to participate in grid peak regulation and the power generation is very random, which intensifies the pressure on grid peak regulation. Relying solely on pure condensing thermal power units is already difficult to meet the needs of power grid peak regulation, so it is necessary to find new peak regulation power sources. The instal...

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Problems solved by technology

[0003] The test shows that there are three problems in the peak regulation of thermal power units: 1. As the electrical load decreases, the steam extraction parameters decrease, which cannot meet the demand for industrial steam; thermal power units generally use the exhaust steam of the medium-pressure cylinder as the heating steam source, with 600MW Take the thermal power unit as an example. When the electrical load of the unit is reduced to 50%, the exhaust pressure of the medium-pressure cylinder drops below 0.5MPa, which cannot meet the requirements of industrial steam extraction parameters.

2. When the heat supply remains unchanged, due to the decrease of the steam extraction parameters, the increase of the heat extraction steam volume, the decrease of the steam intake of the low-pressure cylinder of the steam turbine will cause the steam turbine to produce a blowing phenomenon, and the heat generated cannot be taken away in time, endangering the safety of the equipment ;3. After the electrical load is reduced, the flue gas temperature at the SCR inlet decreases. When the flue gas temperature at the inlet of the denitrification device does not reach the lower limit of the operating temperature of the denitrification system, the denitrification system will stop operating, resulting in excessive nitrogen oxide emissions

At present, the SCR equipment of thermal power units is mostly installed at the outlet of the economizer. When the electric load decreases, the amount of fuel decreases, and the temperature of the flue gas at the outlet of the economizer decreases, resulting in a decrease in the SCR denitrification efficiency. In severe cases, the denitration system will be out of operation, and the nitrogen Oxygen emissions exceed the standard

These problems lead to the thermoelectric unit can only operate in the higher load segment, and the peak shaving ability is weak

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