CN116481039A - Coal-fired power generating unit and operation method thereof - Google Patents

Abstract

The invention relates to a coal-fired power generation unit and an operation method thereof, wherein the coal-fired power generation 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; the coal-fired power generating unit is configured as follows: 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%, 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 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. 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.

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

The installed capacity of renewable energy sources such as solar energy and wind energy is dramatically increased. However, 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 the 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.

To achieve the above object, according to a first aspect of the present disclosure, there is provided a coal-fired power generation unit comprising: the flue gas denitration device is arranged at the downstream of the first low-temperature economizer along the flow direction of the flue gas, is used for denitration of the flue gas, is arranged at the downstream of the first low-temperature economizer along the flow direction, is a main flue communicated between the SCR denitration device and the hearth, is a first low-temperature reheater and a first low-temperature superheater, is arranged in the main flue side by side, is a low-temperature reheat side economizer and a low-temperature overheat side economizer, and is arranged in the main flue side by side, is arranged at the downstream of the first low-temperature reheater along the flow direction, is a low-temperature overheat side economizer arranged at the downstream of the first low-temperature superheater along the flow direction, is a flue gas bypass, is communicated to an inlet of the SCR denitration device in an on-off manner between the first low-temperature superheater and the low-temperature overheat side economizer through the main flue, is arranged in the bypass, is a second low-temperature side economizer and is communicated to a water supply-temperature economizer through the first low-temperature side and the low-temperature economizer through the low-temperature bypass, and the water supply-temperature economizer is communicated to the high-temperature economizer through the first low-temperature side bypass economizer and the low-temperature economizer by the high-pressure side economizer and the water supply-pressure side bypass; wherein, the coal-fired generating unit is configured to: 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.

Optionally, the system further comprises a third feedwater bypass, the third feedwater bypass is communicated into the furnace chamber by an inlet of the low-temperature reheating side economizer in an on-off way, and the coal-fired power generation unit is further configured to: and when the load rate of the coal-fired power generation unit is 30-50%, opening the third water supply bypass.

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, the second low-temperature superheater is arranged between the first low-temperature superheater and the low-temperature reheating side economizer along the flow direction, and the flue gas bypasses the inlet of the SCR denitration device, which is communicated with the first low-temperature superheater and the second low-temperature reheater of the main flue in an on-off manner.

According to a second aspect of the present disclosure, there is provided a method of operating a coal-fired power unit, the coal-fired power unit comprising: the flue gas denitration device is arranged at the downstream of the first low-temperature economizer along the flow direction of the flue gas, is used for denitration of the flue gas, is arranged at the downstream of the first low-temperature economizer along the flow direction, is a main flue communicated between the SCR denitration device and the hearth, is a first low-temperature reheater and a first low-temperature superheater, is arranged in the main flue side by side, is a low-temperature reheat side economizer and a low-temperature overheat side economizer, and is arranged in the main flue side by side, is arranged at the downstream of the first low-temperature reheater along the flow direction, is a low-temperature overheat side economizer arranged at the downstream of the first low-temperature superheater along the flow direction, is a flue gas bypass, is communicated to an inlet of the SCR denitration device in an on-off manner between the first low-temperature superheater and the low-temperature overheat side economizer through the main flue, is arranged in the bypass, is a second low-temperature side economizer and is communicated to a water supply-temperature economizer through the first low-temperature side and the low-temperature economizer through the low-temperature bypass, and the water supply-temperature economizer is communicated to the high-temperature economizer through the first low-temperature side bypass economizer and the low-temperature economizer by the high-pressure side economizer and the water supply-pressure side bypass; 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.

Optionally, the coal-fired power generation unit further comprises a third feedwater bypass, and the third feedwater bypass is communicated into the hearth in an on-off manner through an inlet of the low-temperature reheating 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.

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; 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.

Through the technical scheme, in the process of converting the load rate of the coal-fired power generation unit into 75-100% high load rate, the temperature of the flue gas generated in the hearth is rapidly increased, and when the flue gas reaches the flue gas inlet of the SCR denitration device after flowing through the first low-temperature reheater, the first low-temperature superheater, the low-temperature reheating side economizer and the low-temperature superheating side economizer in the main flue, the temperature of the flue gas inlet of the SCR denitration device can be kept in a temperature interval of efficient operation, meanwhile, the temperature of the first low-temperature economizer at the downstream of the SCR denitration device is also rapidly increased, at the moment, a first water supply bypass is opened to heat the water by using the waste heat of the first low-temperature economizer, that is, the waste heat of the high-pressure heater and the coal-fired power generation unit can be simultaneously heated by water supply to rapidly increase the water supply temperature entering the hearth, so that the load rate of the coal-fired power generation unit can be rapidly changed into 75-100%; when the load rate of the coal-fired power generation unit is converted to 50-75% medium load rate, a flue gas bypass can be opened, so that a part of high-temperature flue gas which is not cooled by the low-temperature reheating side economizer and the low-temperature superheating side economizer directly passes through the flue gas bypass and reaches a flue gas inlet of the SCR denitration device, the flue gas inlet temperature of the SCR denitration device is kept in a temperature interval of efficient operation, the load rate of the coal-fired power generation unit is prevented from being reduced to influence the efficient operation of the SCR denitration device, the standard coal consumption rate of the coal-fired power generation unit is reduced, and meanwhile, a second water supply bypass is opened to adjust the flue gas temperature in the flue gas bypass through the second low-temperature economizer, so that the variable load rate of the coal-fired power generation unit can be improved, the peak regulation process of the coal-fired power generation unit can be assisted, and meanwhile, the first water supply bypass is opened to heat by using the residual heat of the first low-temperature economizer as water supply for heating; when the load rate of the coal-fired power generation unit is changed to 30-50% of low load rate, the flue gas bypass can be opened, so that part of high-temperature flue gas which is not cooled by the low-temperature reheating side economizer and the low-temperature superheating side economizer directly passes through the flue gas bypass and reaches the flue gas inlet of the SCR denitration device, the flue gas inlet temperature of the SCR denitration device is kept in a temperature interval of efficient operation, the load rate of the coal-fired power generation unit is prevented from being reduced to influence the efficient operation of the SCR denitration device, the standard coal consumption rate of the coal-fired power generation unit is reduced, and meanwhile, the second water supply bypass is opened, so that the variable load rate of the coal-fired power generation unit can be improved, the peak regulation process of the coal-fired power generation unit can be assisted, and meanwhile, the first water supply bypass is also closed. The operation method of the coal-fired power generation unit provided by the disclosure has the same technical effects as the coal-fired power generation unit in the technical scheme, and in order to avoid unnecessary repetition, a description is omitted here.

Additional features and advantages of the present disclosure will be set forth in the detailed description which follows.

Drawings

The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification, illustrate the disclosure and together with the description serve to explain, but do not limit the disclosure. In the drawings:

FIG. 1 is a schematic diagram of a coal-fired power unit in accordance with an embodiment of the present disclosure;

FIG. 2 is a flow chart of a method of operating a coal-fired power unit in accordance with an embodiment of the present disclosure.

Description of the reference numerals

The device comprises a 1-hearth, a 2-SCR denitration device, a 31-first low-temperature economizer, a 32-second low-temperature economizer, a 40-main flue, a 41-flue gas bypass, a 411-flue gas baffle, a 51-first low-temperature reheater, a 52-first low-temperature superheater, a 53-second low-temperature reheater, a 54-second low-temperature superheater, a 61-low-temperature reheating side economizer, a 62-low-temperature overheating side economizer, a 70-main water supply pipeline, a 71-first water supply bypass, a 711-first regulating valve, a 72-second water supply bypass, a 721-second regulating valve, a 73-third water supply bypass, a 731-third regulating valve, a 74-water supply pump outlet, an 8-high-pressure heater and a 9-air preheater.

Detailed Description

Specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the disclosure, are not intended to limit the disclosure.

In the present disclosure, unless otherwise indicated, terms of orientation such as "upstream" and "downstream" are used to generally refer to upstream and downstream in the direction of flow of the flue gas, i.e., the flue gas flows from upstream to downstream in the direction of flow. The terms "first," "second," and the like, as used in this disclosure, are used for distinguishing one element from another and not necessarily for order or importance. Furthermore, when the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements unless otherwise indicated.

According to a first aspect of the disclosed embodiments, a coal-fired power unit is provided, which, referring to fig. 1, comprises a furnace 1, a denitrification device 2, a first low-temperature economizer 31, a main flue 40, a flue gas bypass 41, a second low-temperature economizer 32, a first low-temperature reheater 51 and a first low-temperature superheater 52, a low-temperature reheat side economizer 61 and a low-temperature superheat side economizer 62, a main feed water line 70, a first feed water bypass 71, and a second feed water bypass 72. Wherein coal is combusted in the furnace 1 to produce flue gas; the SCR denitration device 2 can be arranged at the downstream of the furnace 1 along the flow direction of the flue gas, so as to be used for denitration of the flue gas, and the temperature at the flue gas inlet of the SCR denitration device 2 is usually kept between 320 ℃ and 400 ℃ to ensure that the SCR denitration device 2 can safely and efficiently operate; the first low-temperature economizer 31 may be arranged downstream of the SCR denitration device 2 in the flow direction; the main flue 40 can be communicated between the SCR denitration device 2 and the hearth 1; the first low-temperature reheater 51 and the first low-temperature superheater 52 may be disposed side by side in the main flue 40; the low-temperature reheat side economizer 61 and the low-temperature superheat side economizer 62 may be disposed side by side in the main flue 40, and the low-temperature reheat side economizer 61 may be disposed downstream of the first low-temperature reheater 51 in the flow direction, and the low-temperature superheat side economizer 62 may be disposed downstream of the first low-temperature superheater 52 in the flow direction; the flue gas bypass 41 can be connected to the inlet of the SCR denitration device 2 by the first low-temperature superheater 52 and the low-temperature overheat side economizer 62 of the main flue 40 in an on-off manner, that is, the flue gas inlet of the flue gas bypass 41 is arranged on the main flue 40 and is positioned between the first low-temperature superheater 52 and the low-temperature overheat side economizer 62, so that part of the high-temperature flue gas flowing through the first low-temperature reheater 51 and the first low-temperature superheater 52 can directly reach the flue gas inlet of the SCR denitration device 2 through the flue gas bypass 41; the second low-temperature economizer 32 is arranged in the flue gas bypass 41; the main water feed line 70 may pass through the high-pressure heater 8, the low-temperature reheat side economizer 61, and the low-temperature superheat side economizer 62 in this order from the water feed pump outlet 74 to the furnace 1; the first water feed bypass 71 may be connected by the water feed pump outlet 74 via the first low-temperature economizer 31 to the outlet of the high-pressure heater 8 on-off, i.e. the first low-temperature economizer 31 may be connected in parallel with the high-pressure heater 8 via the first water feed bypass 71 along the path of the water feed flow; the second feedwater bypass 72 may be on-off communicated from the inlet of the low-temperature reheat side economizer 61 to the outlet of the low-temperature superheat side economizer 62 via the second low-temperature economizer 32, i.e., the second low-temperature economizer 32 may be connected in parallel with the low-temperature reheat side economizer 61 and the low-temperature superheat side economizer 62 through the second feedwater bypass 72 along the path of the feedwater flow; wherein the coal-fired power generation unit may be configured to: when the load rate of the coal-fired power generation unit is 75-100%, the flue gas bypass 41 and the second water supply bypass 72 are closed, and the first water supply bypass 71 is opened; when the load rate of the coal-fired power generation unit is 50% to 75%, the first water supply bypass 71, the flue gas bypass 41 and the second water supply bypass 72 are opened; when the load factor of the coal-fired power generation unit is 30% to 50%, the first feedwater bypass 71 is closed, and the flue gas bypass 41 and the second feedwater bypass 72 are opened.

Through the above technical scheme, in the process of converting the load factor of the coal-fired power generation unit provided by the disclosure into 75% to 100% of high load factor, the temperature of the flue gas generated in the furnace 1 is rapidly increased, and when the flue gas flows through the first low-temperature reheater 51 and the first low-temperature superheater 52, the low-temperature reheating side economizer 61 and the low-temperature overheating side economizer 62 in the main flue 40 and reaches the flue gas inlet of the SCR denitration device 2, the temperature of the flue gas inlet of the SCR denitration device 2 can be kept within a temperature interval in which the coal-fired power generation unit is efficiently operated, and meanwhile, the temperature of the first low-temperature economizer 31 downstream of the SCR denitration device 2 is also rapidly increased, at this time, the first water supply bypass 71 is opened to heat the water supply by using the waste heat of the first low-temperature economizer 31, that is, the waste heat of the high-pressure heater 8 and the coal-fired power generation unit can be simultaneously heated for water supply to rapidly increase the water supply temperature entering the furnace 1, so that the load factor of the coal-fired power generation unit can be rapidly changed into 75% to 100%; when the load rate of the coal-fired power generation unit is converted to the medium load rate of 50-75%, the flue gas bypass 41 can be opened, so that a part of high-temperature flue gas which is not cooled by the low-temperature reheating side economizer 61 and the low-temperature superheating side economizer 62 directly passes through the flue gas bypass 41 and reaches the flue gas inlet of the SCR denitration device 2, the flue gas inlet temperature of the SCR denitration device 2 is kept in a temperature interval in which the high-efficiency operation is performed, the influence of the reduction of the load rate of the coal-fired power generation unit on the high-efficiency operation of the SCR denitration device 2 is avoided, the standard coal consumption rate of the coal-fired power generation unit is reduced, and meanwhile, the second water supply bypass 72 is opened to adjust the flue gas temperature in the flue gas bypass 41 through the second low-temperature economizer 32, so that the variable load rate of the coal-fired power generation unit can be improved, the peak shaving process of the coal-fired power generation unit can be assisted, and meanwhile, the first water supply bypass 71 is opened to heat the waste heat of the first low-temperature economizer 31 for supplying water; when the load rate of the coal-fired power generation unit is changed to 30% to 50% of the low load rate, the flue gas bypass 41 can be opened, so that a part of high-temperature flue gas which is not cooled by the low-temperature reheating side economizer 61 and the low-temperature superheating side economizer 62 directly passes through the flue gas bypass 41 and reaches the flue gas inlet of the SCR denitration device 2, the flue gas inlet temperature of the SCR denitration device 2 is kept in a temperature interval of efficient operation, the load rate of the coal-fired power generation unit is prevented from being reduced to influence the efficient operation of the SCR denitration device 2, the standard coal consumption rate of the coal-fired power generation unit is reduced, and meanwhile, the second water supply bypass 72 is opened to adjust the flue gas temperature in the flue gas bypass 41 through the second low-temperature economizer 32, so that the load rate of the coal-fired power generation unit can be increased, the peak shaving process of the coal-fired power generation unit can be assisted, and the first water supply bypass 71 is also closed.

In addition, referring to fig. 1, the coal-fired power generation unit may further include a third feedwater bypass 73, and the third feedwater bypass 73 may be connected to the furnace 1 by the inlet of the low-temperature reheat side economizer 61 in an on-off manner, that is, in parallel with the second feedwater bypass 72 along the path of the feedwater flow. The coal-fired power unit may be further configured to: when the load factor of the coal-fired power generation unit is 30% to 50%, the third water supply bypass 73 is opened. The third feedwater bypass 73 can directly communicate the feedwater, which is not heated by the low-temperature reheat side economizer 61 and the low-temperature superheat side economizer 62 but has a reduced temperature, into the furnace 1, so that the temperature in the furnace 1 is rapidly reduced, thereby rapidly shifting the load factor of the coal-fired power generation unit to a low load factor of 30% to 50%. In addition, when the coal-fired power generation unit is rapidly changed from the high load rate of 75% to 100% to the medium load rate of 50% to 75%, the third water supply bypass 73 may be opened, so that the third water supply bypass 73, the first water supply bypass 71, the flue gas bypass 41 and the second water supply bypass 72 cooperate to assist in increasing the variable load rate of the coal-fired power generation unit.

In addition, when the load rate of the coal-fired power generation unit is rapidly reduced, the water supply amount of the water supply pump outlet 74 can be reduced to reduce the water supply amount entering the hearth 1, so that the steam amount generated in the hearth 1 is reduced to assist in improving the load rate of the coal-fired power generation unit changing to a low load rate.

In order to control the on-off of the third water feed bypass 73 and to adjust the water feed flow rate of the third water feed bypass 73, referring to fig. 1, a third adjustment valve 731 having an adjustable opening degree may be provided on the third water feed bypass 73.

In order to control the on-off of the smoke bypass 41 and adjust the flow of the smoke in the smoke bypass 41, referring to fig. 1, a smoke baffle 411 for opening and closing the smoke bypass 41 may be disposed in the smoke bypass 41, and the opening of the smoke baffle 411 may be adjusted to adjust the flow of the smoke in the smoke bypass 41. When the load factor of the coal-fired power generation unit is 30% to 75%, the flue gas baffle 411 is opened, when the load factor of the coal-fired power generation unit is more prone to 75%, the flue gas temperature reaching the flue gas inlet of the SCR denitration device 2 through the main flue 40 is higher, so that the opening degree of the flue gas baffle 411 is smaller to avoid the excessively high temperature of the flue gas inlet of the SCR denitration device 2, when the load factor of the coal-fired power generation unit is more prone to 30%, the flue gas temperature reaching the flue gas inlet of the SCR denitration device 2 through the main flue 40 is lower, so that the opening degree of the flue gas baffle 411 is larger to ensure that more high-temperature flue gas which is not cooled by the low-temperature reheat side economizer 61 and the low-temperature superheat side economizer 62 reaches the flue gas inlet of the SCR denitration device 2 through the flue gas bypass 41, the temperature of the flue gas inlet of the SCR denitration device 2 is prevented from being lower than 320 ℃, and safe and efficient operation of the SCR denitration device 2 is ensured.

In a specific embodiment of the present disclosure, the maximum flue gas amount flowing through the flue gas bypass 41 may be 20% of the total flue gas amount generated by the furnace 1, i.e. when the flue gas damper 411 is opened to the maximum opening, at most 20% of the flue gas generated by the furnace 1 can reach the flue gas inlet of the SCR denitration device 2 through the flue gas bypass 41.

Referring to fig. 1, in order to control the on-off of the first feedwater bypass 71 and to adjust the feedwater flow in the first feedwater bypass 71, a first opening-adjustable regulating valve 711 may be provided in the first feedwater bypass 71, and in order to control the on-off of the second feedwater bypass 72 and to adjust the feedwater flow in the second feedwater bypass 72, a second opening-adjustable regulating valve 721 may be provided in the second feedwater bypass 72.

Referring to fig. 1, a second low temperature reheater 53 and a second low temperature superheater 54 may be further disposed in the main flue 40 side by side, the second low temperature reheater 53 may be disposed between the first low temperature reheater 51 and the low temperature reheating side economizer 61 in the flow direction, and the second low temperature superheater 54 may be disposed between the first low temperature superheater 52 and the low temperature superheating side economizer 62 in the flow direction, and at this time, the flue gas bypass 41 may be connected to the inlet of the SCR denitration device 2 on an on-off basis between the first low temperature superheater 52 and the second low temperature reheater 53 of the main flue 40.

According to a second aspect of the present disclosure, there is provided a method for operating a coal-fired power generation unit, as shown in fig. 1 and 2, the coal-fired power generation unit may be the coal-fired power generation unit in the above technical solution, and the method for operating the coal-fired power generation unit includes the following steps:

s1: when the load rate of the coal-fired power generation unit is 75-100%, the flue gas bypass 41 and the second water supply bypass 72 are closed, and the first water supply bypass 71 is opened;

s2: when the load rate of the coal-fired power generation unit is 50% to 75%, the first water supply bypass 71, the flue gas bypass 41 and the second water supply bypass 72 are opened;

s3: when the load factor of the coal-fired power generation unit is 30% to 50%, the first feedwater bypass 71 is closed, and the flue gas bypass 41 and the second feedwater bypass 72 are opened.

Through the technical scheme, the operation method of the coal-fired power generation unit has the same technical effects as the coal-fired power generation unit in the technical scheme, and in order to avoid unnecessary repetition, redundant description is omitted.

Referring to fig. 1, the coal-fired power generation unit may further include a third feedwater bypass 73, and the third feedwater bypass 73 may be connected to the furnace 1 by the inlet of the low-temperature reheat side economizer 61 in an on-off manner, that is, in parallel with the second feedwater bypass 72 along the path of the feedwater flow. Accordingly, the operation method of the coal-fired power generation unit may further include the steps of:

s31: when the load factor of the coal-fired power generation unit is 30% to 50%, the third water supply bypass 73 is opened.

Through step S31, the third feedwater bypass 73 can directly feed the feedwater, which is not heated by the low-temperature reheat side economizer 61 and the low-temperature superheat side economizer 62 but has a reduced temperature, into the furnace 1, so that the temperature in the furnace 1 is rapidly reduced, thereby rapidly shifting the load factor of the coal-fired power generation unit to a low load factor of 30% to 50%.

In addition, the operation method of the coal-fired power generation unit can further comprise the following steps:

s21: when the load factor of the coal-fired power generation unit is 50% to 75%, the third water supply bypass 73 is opened.

The third feedwater bypass 73, the first feedwater bypass 71, and the flue gas bypass 41 and the second feedwater bypass 72 are caused to cooperate to assist in increasing the variable load rate of the coal-fired power generation unit, via step S21.

In order to control the on-off of the smoke bypass 41 and adjust the flow of the smoke in the smoke bypass 41, referring to fig. 1, a smoke baffle 411 for opening and closing the smoke bypass 41 may be disposed in the smoke bypass 41, and the opening of the smoke baffle 411 may be adjusted to adjust the flow of the smoke in the smoke bypass 41. The operation method of the coal-fired power generation unit can further comprise the following steps:

s4: when the load factor of the coal-fired power generation unit is 30% to 75%, the smaller the load factor is, the larger the opening degree of the smoke baffle 411 is, and the larger the load factor is, the smaller the opening degree of the smoke baffle 411 is.

Through step S4, when the load factor of the coal-fired power generation unit tends to 75%, the flue gas temperature reaching the flue gas inlet of the SCR denitration device 2 through the main flue 40 is higher, so that the opening of the flue gas baffle 411 is smaller to avoid the excessively high temperature of the flue gas inlet of the SCR denitration device 2, when the load factor of the coal-fired power generation unit tends to 30%, the flue gas temperature reaching the flue gas inlet of the SCR denitration device 2 through the main flue 40 is lower, so that the opening of the flue gas baffle 411 is larger, so that more high-temperature flue gas which is not cooled by the low-temperature reheat side economizer 61 and the low-temperature superheat side economizer 62 reaches the flue gas inlet of the SCR denitration device 2 through the flue gas bypass 41, the temperature of the flue gas inlet of the SCR denitration device 2 is prevented from being lower than 320 ℃, and the safe and efficient operation of the SCR denitration device 2 is ensured.

The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, but the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solutions of the present disclosure within the scope of the technical concept of the present disclosure, and all the simple modifications belong to the protection scope of the present disclosure.

In addition, the specific features described in the foregoing embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, the present disclosure does not further describe various possible combinations.

Moreover, any combination between the various embodiments of the present disclosure is possible as long as it does not depart from the spirit of the present disclosure, which should also be construed as the disclosure of the present disclosure.

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 water supply bypass, which is connected to the outlet of the high-pressure heater through the first low-temperature economizer by the water supply pump outlet in an on-off way, 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;

wherein, the coal-fired generating unit is configured to: 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.

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 unit is further configured to: and when the load rate of the coal-fired power generation unit is 30-50%, opening the third water supply bypass.

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 reheater 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 water supply bypass, which is connected to the outlet of the high-pressure heater through the first low-temperature economizer by the water supply pump outlet in an on-off way, 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.