Coal-fired power plant boiler system with enhanced deep de-carbonization capability

Abstract

The utility model discloses a kind of coal-fired power plant boiler systems of promoting deep carbon reduction capacity, by being equipped with hot secondary air warm air heater on secondary air duct, and hot secondary air warm air heater is equipped with extraction steam heating hot secondary air after steam exhaust pipeline;Extraction steam heating hot secondary air after steam exhaust pipeline connects two-stage temperature and pressure reducer, and two-stage temperature and pressure reducer is discharged by the steam exhaust steam turbine two-stage extraction steam pipeline through the steam exhaust steam turbine two-stage extraction steam pipeline adjusting valve of steam turbine two-stage extraction steam pipeline;Main steam output pipeline is connected with one-stage temperature and pressure reducer by being sequentially set extraction steam import shut-off valve, extraction steam import regulating valve extraction steam main pipe in sequence, and one-stage temperature and pressure reducer is equipped with extraction steam pipeline after temperature and pressure reduction;Extraction steam pipeline after temperature and pressure reduction is communicated hot secondary air warm air heater;To solve the problem that boiler stable combustion, feedwater temperature is low, coal mill drying treatment is insufficient when coal-fired power plant boiler exists depth peak shaving, improve the economy of boiler deep regulation condition simultaneously, reduce carbon emission.

Description

Technical Field

[0001] This utility model relates to the field of power system operation and control technology, specifically to a coal-fired power plant boiler system that enhances deep regulation and carbon reduction capabilities. Background Technology

[0002] Under the "dual carbon" goals, my country's energy structure is transitioning towards a clean and low-carbon model. While the installed capacity of new energy sources is surging, their intermittent nature necessitates deep peak-shaving by coal-fired power plants to ensure grid stability. National policies explicitly require coal-fired units to improve their peak-shaving flexibility and promote their transformation into regulating power sources. With limited development of thermal power and severe overcapacity in some regions, continuous low-load operation or deep peak-shaving by thermal power units will become the norm in the coming years.

[0003] Currently, the main factors restricting the deep, rapid, and flexible peak shaving of coal-fired power units include: stable combustion characteristics under ultra-low loads, boiler heating surface safety, turbine adaptability, auxiliary equipment matching, system controllability, and unit operating economy. Furthermore, supercritical units experience frequent dry / wet state transitions under low-load conditions, with strong disturbances such as equipment start-up and shutdown, system switching, and structural changes in controlled objects during these transitions. Improper adjustments can easily lead to significant fluctuations in parameters such as main steam pressure, steam temperature, load, and steam-water separator water level, potentially causing a boiler MFT (Main Fuel Turbine Default). For heating units, deep peak shaving is primarily limited by heating capacity. Currently, improving the flexible operation capability of coal-fired power units mainly involves two aspects: first, optimizing the unit's thermal system (boiler combustion, pulverizing, and steam-water systems) and control; and second, installing energy consumption devices such as batteries, electric boilers, and thermal storage. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a coal-fired power plant boiler system that improves the deep peak shaving capability and reduces carbon emissions by solving the problems of stable combustion and low feedwater temperature in coal-fired power plant boilers during deep peak shaving.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: a coal-fired power plant boiler system for improving the deep regulation and carbon reduction capability, including a boiler body, an air preheater connected to the boiler body through a primary air duct and a secondary air duct, and a primary air fan and a blower provided on the air inlet side of the air preheater.

[0006] The boiler body is equipped with a flue gas outlet, which is connected to an SCR denitrification unit via a flue. The outlet flue of the SCR denitrification unit is connected to an air preheater as its heat source. The outlet flue gas of the air preheater is connected to a dust collector, an induced draft fan, and a chimney in sequence via a tail horizontal flue. The superheater outlet of the boiler body is connected to the high-pressure cylinder of the turbine via a main steam output pipeline. The reheater outlet of the boiler body is connected to the intermediate-pressure cylinder of the turbine via a reheat steam high-temperature section output pipeline. The high-pressure cylinder of the turbine is connected to the reheater inlet of the boiler body via a reheat steam low-temperature section pipeline. The steam outlet of the intermediate-pressure cylinder of the turbine is connected to the low-pressure cylinder of the turbine via a pipeline. The high-pressure cylinder, intermediate-pressure cylinder, and low-pressure cylinder of the turbine are connected to the generator via a single shaft connection.

[0007] The deaerator, feedwater pump, No. 3 high-pressure heater, No. 2 high-pressure heater, and No. 1 high-pressure heater are connected in sequence by pipelines. The deaerator is equipped with an inlet pipe, and the No. 1 high-pressure heater is equipped with a No. 1 high-pressure heater outlet feedwater pipeline.

[0008] The high-pressure cylinder of the steam turbine is connected to the first-stage extraction steam header and the second-stage extraction steam header of the steam turbine, respectively, to the No. 1 high-pressure heater and the No. 2 high-pressure heater; the intermediate-pressure cylinder of the steam turbine is connected to the No. 3 high-pressure heater through the third-stage extraction steam header of the steam turbine.

[0009] The secondary air duct is equipped with a hot secondary air heater, and the hot secondary air heater is equipped with a steam extraction pipe for heating the hot secondary air and then the exhaust steam pipe. The steam extraction pipe for heating the hot secondary air and then the exhaust steam pipe is connected to a secondary desuperheater and pressure reducer. The outlet of the secondary desuperheater and pressure reducer is connected to a exhaust steam return pipe to the second stage of the turbine with a regulating valve.

[0010] The main steam output pipeline is connected to the first-stage desuperheating and pressure reducing device via a steam extraction header pipe that is sequentially equipped with a steam extraction inlet shut-off valve and a steam extraction inlet regulating valve. The first-stage desuperheating and pressure reducing device is equipped with a desuperheating and pressure reducing steam extraction pipeline. The desuperheating and pressure reducing steam extraction pipeline is connected to the secondary air heater.

[0011] As a preferred embodiment, the primary desuperheating and pressure reducing device is equipped with a desuperheating and pressure reducing water supply pipe.

[0012] As a preferred embodiment, the desuperheating water supply pipeline of the desuperheating pressure reducer is equipped with a first-stage desuperheating pressure reducer desuperheating water shut-off valve.

[0013] As a preferred embodiment, a desuperheating water regulating valve is provided on the desuperheating water supply pipeline of the desuperheating pressure reducer, on the side of the desuperheating water shut-off valve of the first-stage desuperheating pressure reducer near the first-stage desuperheating pressure reducer.

[0014] As a preferred embodiment, the secondary desuperheating and pressure reducing device is further equipped with a secondary desuperheating and pressure reducing water supply pipeline with a secondary desuperheating and pressure reducing water shut-off valve.

[0015] As a preferred embodiment, the desuperheating water supply pipeline of the secondary desuperheating pressure reducer is further provided with a secondary desuperheating pressure reducer desuperheating water regulating valve on the side of the secondary desuperheating pressure reducer desuperheating water shut-off valve near the secondary desuperheating pressure reducer.

[0016] As a preferred embodiment, the exhaust steam pipeline after the extracted steam heats the secondary air is also connected to a section of the exhaust steam pipeline for returning exhaust steam to the turbine, which includes a regulating valve for the exhaust steam return to the turbine section.

[0017] As a preferred embodiment, the primary air duct is equipped with a primary air heater, the steam inlet of which is connected to the extraction steam pipe after de-temperature and pressure reduction via a pipeline; the steam outlet of the primary air heater is connected to the exhaust steam pipe after the extraction steam heats the secondary air via the exhaust steam pipe of the primary air heater outlet.

[0018] As a preferred embodiment, a desulfurization tower is provided between the induced draft fan and the chimney.

[0019] As a preferred embodiment, the intermediate pressure cylinder of the steam turbine is connected to the deaerator via the fourth-section extraction steam header of the steam turbine.

[0020] The beneficial effects of this utility model are as follows: The system disclosed in this utility model, which enhances the carbon reduction capability of deep-load operation in coal-fired power plant boilers, divides steam from the main steam header into two paths after desuperheating and pressure reduction by a primary desuperheater / pressure reducer. One path enters the primary air heater to heat the primary air, improving the drying output of the coal mill; the other path enters the secondary air heater to heat the secondary air, improving the stability of pulverized coal combustion in the furnace. The exhaust steam from the heater is then divided into two parts: one part enters the secondary extraction steam header after desuperheating and pressure reduction by a secondary desuperheater / pressure reducer to heat the feedwater, significantly increasing the feedwater temperature; the other part enters the primary extraction steam header to further heat the feedwater. This system can significantly increase the primary air temperature, secondary air temperature, and feedwater temperature of coal-fired power plant boilers under deep load conditions, ultimately solving the problems of stable boiler combustion, low feedwater temperature, dry-wet transition, and insufficient drying output of the coal mill during deep-load operation in coal-fired power plant boilers. It can also reduce the coal consumption for power generation during deep-load operation to a certain extent, improving economic efficiency and reducing carbon emissions.

[0021] Because the primary desuperheater is equipped with a desuperheater desuperheating water supply pipe, the desuperheating water is introduced to mix with the steam extracted from the steam header and then used to heat the primary and secondary air. This satisfies the heating requirements of the primary and secondary air entering the boiler body without wasting steam, thereby improving thermal efficiency.

[0022] Since the exhaust steam pipeline after the extraction steam heats the secondary air is also connected to the exhaust steam pipeline with a regulating valve for the exhaust steam returning to the turbine, the exhaust steam returns to the high-pressure heater to heat the feedwater, thereby increasing the feedwater temperature and further improving the system's thermal energy utilization rate.

[0023] Because the primary air duct is equipped with a primary air heater, the inlet of the primary air heater is connected to the extraction steam pipe after de-cooling and de-pressure through a pipe; the outlet of the primary air heater is connected to the exhaust steam pipe after the extraction steam heats the secondary air through the exhaust steam pipe of the primary air heater outlet, so as to heat the air sent into the boiler body from the primary air duct and improve the combustion efficiency.

[0024] Because a desulfurization tower is installed between the induced draft fan and the chimney, the emitted flue gas is guaranteed to meet environmental protection standards.

[0025] Since the intermediate pressure cylinder of the steam turbine is connected to the deaerator through the fourth extraction steam header of the steam turbine, the thermal energy utilization rate of this system is further improved. Attached Figure Description

[0026] Figure 1 This is a system composition block diagram of the present invention. Detailed Implementation

[0027] The specific implementation scheme of this utility model will now be described in detail with reference to the accompanying drawings.

[0028] like Figure 1 As shown, a coal-fired power plant boiler system with improved deep-heating carbon reduction capability includes a boiler body (1), an air preheater (7) with a primary air fan (8) and a blower (9) on the air inlet side, and the air preheater (7) is connected to the boiler body (1) through a primary air duct (a) and a secondary air duct (b).

[0029] The boiler body (1) is provided with a flue gas outlet, which is connected to the SCR denitrification device (3) through a flue. The outlet flue of the SCR denitrification device (3) is connected to the air preheater (7) as the heat source of the air preheater. The outlet flue gas of the air preheater (7) is connected to the dust collector (10), induced draft fan (11), desulfurization tower (12) and chimney (13) in sequence through the tail horizontal flue (d). The superheater outlet of the boiler body (1) is connected to the high pressure of the steam turbine through the main steam output pipe (e). The cylinder (14) is connected; the reheater outlet of the boiler body (1) is connected to the intermediate pressure cylinder (15) of the steam turbine through the high temperature section output pipe (g) of the reheat steam; the high pressure cylinder (14) of the steam turbine is connected to the reheater inlet of the boiler body (1) through the low temperature section pipe (f) of the reheat steam; the intermediate pressure cylinder (15) of the steam turbine is connected to the low pressure cylinder (16) of the steam turbine through a pipe; the high pressure cylinder (14), intermediate pressure cylinder (15) and low pressure cylinder (16) of the steam turbine are connected to the generator (17) after being connected by a single shaft;

[0030] The deaerator (22), feed water pump (21), No. 3 high-pressure heater (20), No. 2 high-pressure heater (19), and No. 1 high-pressure heater (18) are connected in sequence by pipes. The deaerator (22) is equipped with an inlet pipe (supplied by a lower-level low-pressure heater), and the No. 1 high-pressure heater (18) is equipped with a No. 1 high-pressure heater outlet feed water pipe (L).

[0031] The high-pressure cylinder (14) of the steam turbine is connected to the No. 1 high-pressure heater (18) and the No. 2 high-pressure heater (19) respectively via the first stage extraction steam header (h) and the second stage extraction steam header (i) of the steam turbine; the intermediate-pressure cylinder (15) of the steam turbine is connected to the No. 3 high-pressure heater (20) via the third stage extraction steam header (j) of the steam turbine; the intermediate-pressure cylinder (15) of the steam turbine is also connected to the deaerator (22) via the fourth stage extraction steam header (k) of the steam turbine.

[0032] A hot secondary air heater (5) is installed on the secondary air duct (b), and a steam extraction pipe (p) is installed on the hot secondary air heater (5) to heat the hot secondary air; the steam extraction pipe (p) is connected to a secondary desuperheater (4), and the outlet of the secondary desuperheater (4) is connected to a steam extraction pipe (r) with a regulating valve (27) for steam returning to the turbine stage 2 to discharge the exhaust steam;

[0033] The main steam output pipeline (e) is connected to the first-stage desuperheater and pressure reducer (2) via the extraction steam inlet shut-off valve (23) and the extraction steam inlet regulating valve (24) installed in sequence. When the unit is under high load, the system is not activated and the extraction steam inlet shut-off valve (23) is closed. The extraction steam inlet shut-off valve (23) acts as an isolation valve to prevent steam from entering. When the load is adjusted to a high level, the system is activated and the extraction steam inlet shut-off valve (23) is opened. The amount of steam extracted is adjusted by the extraction steam inlet regulating valve (24). The extraction steam inlet regulating valve (24) acts as a regulator to adjust the amount of steam entering the unit.

[0034] The primary desuperheater (2) is equipped with a steam extraction pipe (o) after desuperheating and pressure reduction; the steam extraction pipe (o) after desuperheating and pressure reduction is connected to the secondary hot air heater (5). The extracted high-temperature and high-pressure main steam is desuperheated and pressure reduced by the primary desuperheater (2) and then connected to the secondary hot air heater (5).

[0035] The first-stage desuperheating and pressure reducing device (2) is equipped with a desuperheating and pressure reducing water supply pipe (n). The desuperheating and pressure reducing water supply pipe (n) is equipped with a first-stage desuperheating and pressure reducing water shut-off valve (26) and a first-stage desuperheating and pressure reducing water regulating valve (25) in sequence along the medium input direction. The desuperheating water of the first-stage desuperheating and pressure reducing device (2) can be supplied from the outlet of the water pump (21) or the outlet of the No. 1 high-pressure heater (18) according to the actual situation. That is, the desuperheating and pressure reducing water pipe (n) can be connected from different positions of the water supply pipe (L) according to the actual situation.

[0036] When the system is put into operation, the shut-off valve is opened, and the flow rate of the desuperheating water is adjusted by the desuperheating water regulating valve (25) of the first-stage desuperheating and pressure reducing device to control the temperature of the newly extracted steam after desuperheating and pressure reducing, that is, the temperature of the inlet steam of the hot secondary air heater (5), to ensure the effect of the hot secondary air heater (5) in heating the hot secondary air, and to ensure that the temperature of the hot secondary air under deep load is close to the rated load, thereby enhancing the boiler's stable combustion capability under deep peak load.

[0037] The secondary desuperheater (4) is also equipped with a secondary desuperheater desuperheater water supply pipe (s) with a secondary desuperheater desuperheater water shut-off valve (29); the secondary desuperheater desuperheater water supply pipe (s) is also equipped with a secondary desuperheater desuperheater water regulating valve (28) on the side of the secondary desuperheater desuperheater water shut-off valve (29) near the secondary desuperheater (4). The desuperheater water of the secondary desuperheater (4) is taken from the condensate at the outlet of the deaerator (22). When the system is put into operation, the secondary desuperheater desuperheater water shut-off valve (29) is opened, and the flow rate of the desuperheater water is adjusted by the secondary desuperheater desuperheater water regulating valve (28) to control the temperature and pressure of the exhaust steam heating turbine second-stage extraction steam header (i). The exhaust steam pipeline (p) after the extracted steam heats the hot secondary air is also connected to the exhaust steam pipeline (t) with an exhaust steam return turbine first-stage extraction steam pipeline regulating valve (30).

[0038] The primary air duct (a) is equipped with a primary air heater (6). The steam inlet of the primary air heater (6) is connected to the extraction steam pipe (o) after de-temperature and pressure reduction through a pipe. The steam outlet of the primary air heater (6) is connected to the exhaust steam pipe (p) after the extraction steam heats the secondary air through the exhaust steam pipe (q) of the primary air heater outlet.

[0039] After de-cooling and depressurization, the extracted steam enters the hot primary air heater (6) to heat the hot primary air, thereby increasing the temperature of the hot primary air and ensuring the drying output of the coal mill under deep-load conditions. This reduces the unburned carbon content in fly ash and slag under deep-load conditions, effectively reducing energy consumption and pollutant emissions.

[0040] The exhaust steam from the outlets of the secondary hot air heater (5) and the primary hot air heater (6) is combined into one path and then transported in two paths: one path passes through the secondary desuperheater and pressure reducer (4) for desuperheating and pressure reduction before entering the second-stage extraction steam header (i) to heat the feedwater, significantly increasing the feedwater temperature; the other path enters the first-stage extraction steam header (h) to heat the feedwater, further increasing the feedwater temperature.

[0041] The above embodiments are merely illustrative of the principles and effects of this utility model, as well as some of its applications, and are not intended to limit this utility model. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of this utility model, and these modifications and improvements all fall within the protection scope of this utility model.

Claims

1. A coal-fired power plant boiler system for improving deep-fired carbon reduction capability, comprising a boiler body (1), an air preheater (7) connected to the boiler body (1) through a primary air duct (a) and a secondary air duct (b), and a primary air fan (8) and a blower (9) provided on the air inlet side of the air preheater (7); The boiler body (1) is provided with a flue gas outlet, which is connected to the SCR denitrification device (3) through a flue. The outlet flue of the SCR denitrification device (3) is connected to the air preheater (7) as the heat source of the air preheater (7). The outlet flue gas of the air preheater (7) is connected to the dust collector (10), the induced draft fan (11), and the chimney (13) in sequence through the tail horizontal flue (d). The superheater outlet of the boiler body (1) is connected to the high-pressure cylinder (14) of the steam turbine through the main steam output pipe (e). The reheater outlet of the boiler body (1) is connected to the intermediate-pressure cylinder (15) of the turbine through the high-temperature section reheat steam output pipe (g); the high-pressure cylinder (14) of the turbine is connected to the reheater inlet of the boiler body (1) through the low-temperature section reheat steam pipe (f); the steam outlet of the intermediate-pressure cylinder (15) of the turbine is connected to the low-pressure cylinder (16) of the turbine through a pipe; the high-pressure cylinder (14), intermediate-pressure cylinder (15) and low-pressure cylinder (16) of the turbine are connected to the generator (17) after being connected by a single shaft; The deaerator (22), water pump (21), No. 3 high-pressure heater (20), No. 2 high-pressure heater (19), and No. 1 high-pressure heater (18) are connected in sequence by pipes. The deaerator (22) is equipped with an inlet pipe, and the No. 1 high-pressure heater (18) is equipped with a No. 1 high-pressure heater outlet water supply pipe (L). Its features are: The high-pressure cylinder (14) of the steam turbine is connected to the first-stage extraction steam header (h) and the second-stage extraction steam header (i) of the steam turbine to the first high-pressure heater (18) and the second high-pressure heater (19) respectively; the intermediate-pressure cylinder (15) of the steam turbine is connected to the third high-pressure heater (20) through the third-stage extraction steam header (j) of the steam turbine. A hot secondary air heater (5) is installed on the secondary air duct (b), and a steam extraction pipe (p) is installed on the hot secondary air heater (5) to heat the hot secondary air; the steam extraction pipe (p) to heat the hot secondary air is connected to a secondary desuperheater (4), and the outlet of the secondary desuperheater (4) is connected to a steam extraction pipe (r) to the second stage of the turbine with a regulating valve (27) for the steam extraction pipe to return the steam to the turbine. The main steam output pipeline (e) is connected to the first-stage desuperheating and pressure reducing device (2) via the extraction steam inlet shut-off valve (23) and extraction steam inlet regulating valve (24) set in sequence. The first-stage desuperheating and pressure reducing device (2) is equipped with an extraction steam pipeline (o) after desuperheating and pressure reducing; the extraction steam pipeline (o) after desuperheating and pressure reducing is connected to the secondary hot air heater (5).

2. The coal-fired power plant boiler system for improving deep-fired carbon reduction capability as described in claim 1, characterized in that: The first-stage desuperheating and pressure reducing device (2) is equipped with a desuperheating and pressure reducing water supply pipe (n).

3. A coal-fired power plant boiler system for improving deep-fired carbon reduction capability as described in claim 2, characterized in that: The desuperheating water supply pipeline (n) of the desuperheating pressure reducer is equipped with a first-stage desuperheating water shut-off valve (26).

4. A coal-fired power plant boiler system for improving deep-fired carbon reduction capability as described in claim 3, characterized in that: On the desuperheating water supply pipeline (n) of the desuperheating pressure reducer, a desuperheating water regulating valve (25) of the first-stage desuperheating pressure reducer is provided on the side of the first-stage desuperheating pressure reducer desuperheating water shut-off valve (26) near the first-stage desuperheating pressure reducer (2).

5. A coal-fired power plant boiler system for improving deep-fired carbon reduction capability as described in claim 1, characterized in that: The secondary desuperheating pressure reducer (4) is also equipped with a secondary desuperheating pressure reducer desuperheating water supply pipe (s) with a secondary desuperheating pressure reducer desuperheating water shut-off valve (29).

6. A coal-fired power plant boiler system for improving deep-fired carbon reduction capability as described in claim 5, characterized in that: On the secondary desuperheating pressure reducer desuperheating water supply pipeline (s), a secondary desuperheating pressure reducer desuperheating water regulating valve (28) is also provided on the side of the secondary desuperheating pressure reducer desuperheating water shut-off valve (29) near the secondary desuperheating pressure reducer (4).

7. A coal-fired power plant boiler system for improving deep-fired carbon reduction capability as described in claim 1, characterized in that: After the steam is extracted to heat the secondary air, the exhaust steam pipeline (p) is also connected to the exhaust steam return turbine first-stage extraction steam pipeline (t) with the exhaust steam return turbine first-stage extraction steam pipeline regulating valve (30).

8. A coal-fired power plant boiler system for improving deep-fired carbon reduction capability as described in claim 1, characterized in that: The primary air duct (a) is equipped with a primary air heater (6). The steam inlet of the primary air heater (6) is connected to the extraction steam pipe (o) after de-temperature and pressure reduction through a pipe. The steam outlet of the primary air heater (6) is connected to the exhaust steam pipe (p) after the extraction steam heats the secondary air through the exhaust steam pipe (q) of the primary air heater outlet.

9. A coal-fired power plant boiler system for improving deep-fired carbon reduction capability as described in claim 1, characterized in that: A desulfurization tower (12) is provided between the induced draft fan (11) and the chimney (13).

10. A coal-fired power plant boiler system for improving deep-fired carbon reduction capability as described in claim 1, characterized in that: The intermediate pressure cylinder (15) of the steam turbine is connected to the deaerator (22) through the fourth extraction steam header (k) of the steam turbine.

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