CN-116481039-B - Coal-fired power generating unit and operation method thereof

CN116481039BCN 116481039 BCN116481039 BCN 116481039BCN-116481039-B

Abstract

The utility model relates to a coal-fired generating unit and an operation method thereof, wherein the coal-fired generating unit comprises a hearth, an SCR denitration device, a first low-temperature economizer, a main flue, a flue gas bypass, a second low-temperature economizer, a main water supply pipeline, a first water supply bypass and a second water supply bypass, wherein the flue gas bypass and the second water supply bypass are arranged in the flue gas bypass, the coal-fired generating unit is configured to be closed when the load rate of the coal-fired generating unit is 75-100%, the first water supply bypass is opened, the first water supply bypass, the flue gas bypass and the second water supply bypass are opened when the load rate of the coal-fired generating unit is 50-75%, and the first water supply bypass and the second water supply bypass are closed when the load rate of the coal-fired generating unit is 30-50%. The coal-fired power generation unit and the operation method thereof can solve the technical problem that the load-changing rate of the coal-fired power generation unit is improved and the safe and efficient operation of the SCR denitration system cannot be achieved.

Inventors

ZHANG JUNLIANG
JIA SHUWANG
GAO WEI
WANG TIANKUN
ZHAO MINGYUAN
WANG BO
GU YONGZHENG

Assignees

国能锦界能源有限责任公司
西安交通大学

Dates

Publication Date: 20260512
Application Date: 20230201

Claims (10)

1. A coal-fired power generation unit comprising: a furnace in which coal is combusted to produce flue gases, The SCR denitration device is arranged at the downstream of the hearth along the flow direction of the flue gas and is used for denitration of the flue gas, A first low-temperature economizer arranged downstream of the SCR denitration device along the flow direction, The main flue is communicated between the SCR denitration device and the hearth, The first low-temperature reheater and the first low-temperature superheater are arranged in the main flue side by side, A low-temperature reheating side economizer and a low-temperature superheating side economizer arranged in parallel in the main flue, the low-temperature reheating side economizer being arranged downstream of the first low-temperature reheater in the flow direction, the low-temperature superheating side economizer being arranged downstream of the first low-temperature superheater in the flow direction, A flue gas bypass, which is communicated with the inlet of the SCR denitration device in an on-off way between the first low-temperature superheater and the low-temperature overheat side economizer of the main flue, a second low-temperature economizer is arranged in the flue gas bypass, A main water supply pipeline, which sequentially passes through the high-pressure heater, the low-temperature reheating side economizer and the low-temperature superheating side economizer from the water supply pump outlet to reach the hearth, A first feedwater bypass, which is connected to the outlet of the high-pressure heater through the first low-temperature economizer by the water pump outlet, and A second feedwater bypass, which is connected to the outlet of the low-temperature overheat side economizer through the inlet of the low-temperature reheat side economizer in an on-off manner; The coal-fired power generation unit is configured to close the flue gas bypass and the second water supply bypass when the load rate of the coal-fired power generation unit is 75-100%, open the first water supply bypass, the flue gas bypass and the second water supply bypass when the load rate of the coal-fired power generation unit is 50-75%, and close the first water supply bypass and open the flue gas bypass and the second water supply bypass when the load rate of the coal-fired power generation unit is 30-50%.
2. The coal-fired power generation unit according to claim 1, further comprising a third feedwater bypass, the third feedwater bypass being on-off communicable into the furnace by an inlet of the low temperature reheat side economizer, The coal-fired power generation unit is further configured to open the third water supply bypass when a load factor of the coal-fired power generation unit is 30% to 50%.
3. The coal-fired power generation unit according to claim 2, wherein the third feedwater bypass is provided with a third regulating valve with an adjustable opening.
4. The coal-fired power generation unit according to claim 1, wherein a flue gas baffle for opening and closing the flue gas bypass is arranged in the flue gas bypass, and the opening degree of the flue gas baffle is adjustable.
5. The coal-fired power generation unit according to claim 4, wherein the maximum amount of flue gas flowing through the flue gas bypass is 20% of the total amount of flue gas generated by the furnace.
6. The coal-fired power generation unit according to claim 1, wherein the first feedwater bypass is provided with a first regulating valve with an adjustable opening, and the second feedwater bypass is provided with a second regulating valve with an adjustable opening.
7. The coal-fired power generation unit according to claim 1, wherein a second low-temperature reheater and a second low-temperature superheater are further provided side by side in the main flue, the second low-temperature reheater being provided between the first low-temperature reheater and the low-temperature reheat side economizer in the flow direction, the second low-temperature superheater being provided between the first low-temperature superheater and the low-temperature superheat side economizer in the flow direction, The flue gas bypass is communicated to an inlet of the SCR denitration device between the first low-temperature superheater and the second low-temperature superheater of the main flue in an on-off mode.
8. A method of operating a coal-fired power generation unit, the coal-fired power generation unit comprising: a furnace in which coal is combusted to produce flue gases, The SCR denitration device is arranged at the downstream of the hearth along the flow direction of the flue gas and is used for denitration of the flue gas, A first low-temperature economizer arranged downstream of the SCR denitration device along the flow direction, The main flue is communicated between the SCR denitration device and the hearth, The first low-temperature reheater and the first low-temperature superheater are arranged in the main flue side by side, A low-temperature reheating side economizer and a low-temperature superheating side economizer arranged in parallel in the main flue, the low-temperature reheating side economizer being arranged downstream of the first low-temperature reheater in the flow direction, the low-temperature superheating side economizer being arranged downstream of the first low-temperature superheater in the flow direction, A flue gas bypass, which is communicated with the inlet of the SCR denitration device in an on-off way between the first low-temperature superheater and the low-temperature overheat side economizer of the main flue, a second low-temperature economizer is arranged in the flue gas bypass, A main water supply pipeline, which sequentially passes through the high-pressure heater, the low-temperature reheating side economizer and the low-temperature superheating side economizer from the water supply pump outlet to reach the hearth, A first feedwater bypass, which is connected to the outlet of the high-pressure heater through the first low-temperature economizer by the water pump outlet, and A second feedwater bypass, which is connected to the outlet of the low-temperature overheat side economizer through the inlet of the low-temperature reheat side economizer in an on-off manner; The operation method of the coal-fired power generation unit comprises the following steps: when the load rate of the coal-fired power generation unit is 75-100%, closing the flue gas bypass and the second water supply bypass, and opening the first water supply bypass; When the load rate of the coal-fired power generation unit is 50-75%, opening the first water supply bypass, the flue gas bypass and the second water supply bypass; and when the load rate of the coal-fired power generation unit is 30-50%, closing the first water supply bypass, and opening the flue gas bypass and the second water supply bypass.
9. The method of operating a coal-fired power unit as claimed in claim 8, further comprising a third feedwater bypass, the third feedwater bypass being on-off communicable into the furnace by an inlet of the low temperature reheat side economizer; the operation method of the coal-fired power generation unit further comprises the following steps: and when the load rate of the coal-fired power generation unit is 30-50%, opening the third water supply bypass.
10. The operation method of the coal-fired power generation unit according to claim 8, wherein a flue gas baffle for opening and closing the flue gas bypass is arranged in the flue gas bypass, and the opening of the flue gas baffle is adjustable; the operation method of the coal-fired power generation unit further comprises the following steps: When the load factor of the coal-fired power generation unit is 30-75%, the smaller the load factor is, the larger the opening degree of the smoke baffle is, and the larger the load factor is, the smaller the opening degree of the smoke baffle is.

Description

Coal-fired power generating unit and operation method thereof Technical Field The disclosure relates to the technical field of thermal power generation, in particular to a coal-fired power generation unit and an operation method thereof. Background Wind energy and solar energy are easily affected by the environment, have strong time variability, and bring a certain threat to the safe operation of a power grid. And coal-fired power generation is used as a main power supply source in China at present, and more peak regulation and frequency modulation tasks are needed to be born. In the related art, the load-changing rate of the coal-fired power generation unit is improved, and meanwhile, the safe and efficient operation of the SCR denitration system of the coal-fired power generation unit is considered, so that the power generation efficiency of the coal-fired power generation unit is improved, and the problem to be solved is urgently needed. Disclosure of Invention The invention aims to provide a coal-fired power generation unit and an operation method thereof, which are used for solving the technical problem that the load-changing rate of the coal-fired power generation unit is improved and the safe and efficient operation of an SCR denitration system cannot be achieved. In order to achieve the above object, according to a first aspect of the present disclosure, there is provided a coal-fired power generation unit including a furnace in which coal is burned to generate flue gas, an SCR denitration device disposed downstream of the furnace in a flow direction of the flue gas for denitration of the flue gas, a first low-temperature economizer disposed downstream of the SCR denitration device in the flow direction, a main flue communicated between the SCR denitration device and the furnace, a first low-temperature reheater and a first low-temperature superheater disposed in the main flue side by side, a low-temperature reheat side economizer and a low-temperature overheat side economizer disposed in the main flue side by side, the low-temperature reheat side economizer being disposed downstream of the first low-temperature reheater in the flow direction, a bypass being disposed downstream of the first low-temperature superheater in the flow direction, the flue gas bypass being communicated between the first low-temperature superheater and the low-temperature superheater of the main flue to the second low-temperature economizer via the first low-temperature economizer, the first low-temperature reheater and the low-temperature economizer being communicated to the second low-temperature economizer by way through a water pump, the water-supply-side economizer being communicated to the first low-temperature economizer, the water-temperature economizer being disposed in the main flue, the low-temperature economizer being communicated to the water-supply-side by way, and the water-gas-saving device being connected to a water-supply-side-by the water-pump, the water-heater, the bypass being disposed at the water-low-temperature economizer; wherein the coal-fired power generation unit is configured such that when the load factor of the coal-fired power generation unit is 75% to 100%, the flue gas bypass and the second water supply bypass are closed, the first water supply bypass is opened, when the load rate of the coal-fired power generation unit is 50-75%, the first water supply bypass, the flue gas bypass and the second water supply bypass are opened, and when the load rate of the coal-fired power generation unit is 30-50%, the first water supply bypass is closed, and the flue gas bypass and the second water supply bypass are opened. Optionally, the system further comprises a third water supply bypass, wherein the third water supply bypass is communicated to the hearth by the inlet of the low-temperature reheating side economizer in an on-off mode, and the coal-fired power generation unit is further configured to open the third water supply bypass when the load rate of the coal-fired power generation unit is 30-50%. Optionally, a third adjusting valve with adjustable opening is arranged on the third water supply bypass. Optionally, a flue gas baffle for opening and closing the flue gas bypass is arranged in the flue gas bypass, and the opening of the flue gas baffle is adjustable. Optionally, the maximum flue gas amount flowing through the flue gas bypass is 20% of the total flue gas amount generated by the furnace. Optionally, the first water supply bypass is provided with a first adjusting valve with adjustable opening, and the second water supply bypass is provided with a second adjusting valve with adjustable opening. Optionally, a second low-temperature reheater and a second low-temperature superheater are arranged in the main flue side by side, the second low-temperature reheater is arranged between the first low-temperature reheater and the low-temperature reheating side economizer along the flow direction,