CN111603928A - An efficient, clean, flexible and collaborative coal-fired power generation system and operation method - Google Patents

Abstract

The invention discloses a high-efficiency clean flexible cooperative coal-fired power generation system and an operation method thereof, wherein the system adopts an arrangement mode of separating parallel flues and grading economizers, and is provided with a flue gas adjusting baffle and an adjusting valve; the system can accurately adjust the temperature of the flue gas at the SCR inlet, realize the wide-load efficient denitration of the coal-fired generator set and improve the wide-load operation efficiency. In addition, the system can improve the variable load rate of the coal-fired generator set, and improves the system efficiency and the SCR denitration efficiency in the process of improving the variable load rate.

Description

An efficient, clean, flexible and collaborative coal-fired power generation system and operation method

technical field

The invention belongs to the field of coal-fired power generation, and in particular relates to an efficient, clean, flexible, and collaborative coal-fired power generation system and an operation method.

Background technique

Achieving high-efficiency denitrification under all working conditions, increasing the variable load rate, and improving operating efficiency are the technical requirements for coal-fired power generation in the basic national policy of "energy saving and emission reduction". However, the efficiency, cleanliness and flexibility of coal-fired generating units are mutually restricted. Because the SCR denitration catalyst has its working temperature range requirements, and the inlet temperature of the SCR denitration catalyst drops when the conventional coal-fired power unit reduces the load, it is difficult for the coal-fired power unit to achieve high-efficiency denitration at a wide load. At the same time, the operating efficiency of the coal-fired generator set is significantly reduced when it climbs rapidly.

In recent years, my country has made great achievements in new energy development, and the installed capacity of new energy power generation has grown rapidly. However, wind energy and solar energy are unstable, resulting in strong fluctuations in the output power of solar photovoltaic and wind power generation, causing huge power-side load disturbances to the power grid. In order to balance power supply and demand, coal-fired generating units need to operate with frequent and deep load changes. At the same time, in order to improve the operation safety of the power grid, the coal-fired power generating unit needs to have the ability to change the load rapidly.

SCR denitration device is the current mainstream denitration device, but the SCR denitration catalyst has a suitable temperature range for operation. When the inlet flue gas temperature of the SCR denitration device deviates from the operating temperature range of the SCR denitration catalyst, the denitration efficiency will be significantly reduced. It is for this reason that when coal-fired power plants operate at low loads, NOx emissions are greatly increased. Existing technologies such as flue gas bypass and water supply bypass generally have a prominent problem of contradiction between high efficiency and cleanliness. In addition, when the unit operates with a rapid load change, the instantaneous denitration efficiency of the SCR and the efficiency of the coal-fired power station in the prior art are significantly reduced.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned problems in the prior art, the purpose of the present invention is to propose a high-efficiency, clean, flexible, and collaborative coal-fired power generation system and an operation method. Flue gas regulating baffle and regulating valve. The system can precisely adjust the flue gas temperature at the SCR inlet to achieve high-efficiency denitrification in a wide-load coal-fired generator set, and at the same time improve the wide-load operating efficiency. In addition, the system can improve the variable load rate of the coal-fired generator set, and in the process of increasing the variable load rate, the system efficiency and the SCR denitration efficiency can be improved.

In order to achieve the above object, the present invention adopts the following technical solutions:

An efficient, clean, flexible, and coordinated coal-fired power generation system includes an economizer 2, an SCR denitration device 3, and a pre-economizer 4, which are sequentially arranged in the flue flue at the tail of a boiler 1 along the flue gas flow direction. The duct is divided into two parallel separated flues, one side of the separated flue is arranged along the flue gas flow direction in turn with the No. 1 flue gas baffle 51 and the air preheater 53, and the other side is arranged with the No. 52. No. 1 split economizer 54 and No. 2 split economizer 55; the water outlet of economizer 2 is connected to the water inlet of the water wall, the water inlet of economizer 2 is connected to the water outlet of pre-economizer 4, and is also The No. 1 feedwater regulating valve 61 is connected to the water inlet of the pre-economizer 4; the water inlet of the pre-economizer 4 is connected to the water outlet of the No. 1 split economizer 54, and is also connected to the high-pressure heater group through the No. 2 feedwater regulating valve 62 7. The water outlet is connected; the water inlet of the No. 1 split economizer 54 is connected to the water outlet of the No. 2 split economizer 55, and is also connected to the water outlet of the high-pressure heater group 7 through the No. 3 water supply regulating valve 63; the No. 2 split economizer 55 The water inlet is connected with the water outlet of the feed pump 8 through the No. 4 feed water regulating valve 64; the water inlet of the high pressure heater group 7 is connected with the water outlet of the feed pump 8.

The area of the pre-economizer 4 is 0.2 to 0.4 times the area of the economizer 2 .

The area of the No. 1 split economizer 54 is 0.5 to 0.8 times the area of the No. 2 split economizer 55 .

The No. 1 water supply regulating valve 61 , the No. 2 water supply regulating valve 62 , the No. 3 water supply regulating valve 63 and the No. 4 water supply regulating valve 64 are electric automatic regulating valves.

In the described operation method of an efficient, clean, flexible and collaborative coal-fired power generation system, the inlet flue gas temperature of the SCR denitration device 3 is adjusted by adjusting the No. 1 feedwater control valve 61 to meet the working temperature range of the SCR denitration device 3. The specific adjustment method is: The inlet flue gas temperature of SCR denitration device 3, if the measured inlet flue gas temperature of SCR denitration device 3 is higher than the maximum working temperature of SCR denitration device 3, increase the opening degree of No. 1 feedwater regulating valve 61; measure and measure SCR denitration device 3 If the inlet flue gas temperature is lower than the working temperature of the SCR denitration device 3, the opening degree of the No. 1 feedwater regulating valve 61 is reduced;

When the coal-fired power generation system needs to increase the load rapidly, increase the opening of the No. 4 feedwater control valve 64, decrease the opening of the No. 3 feedwater control valve 63, increase the opening of the No. 2 feedwater control valve 62, and decrease the opening of the No. The opening degree of No. 61 water supply control valve;

By adjusting the opening degrees of the No. 1 flue gas baffle 51 and the No. 2 flue gas baffle 52, the flue gas temperature at the flue gas outlet at the tail of the boiler 1 is minimized.

The flue gas flow of the No. 2 flue gas baffle 52 accounts for 20% to 40% of the total flue gas flow.

The working temperature range of the SCR denitration device 3 is 300°C to 400°C.

The system of the invention adopts the arrangement of separating parallel flues and grading economizers, and is equipped with flue gas regulating baffles and regulating valves. The system can precisely adjust the flue gas temperature at the SCR inlet to achieve high-efficiency denitrification in a wide-load coal-fired generator set, and at the same time improve the wide-load operating efficiency. In addition, the system of the present invention can improve the variable load rate of the coal-fired generating set, and in the process of increasing the variable load rate, the system efficiency and the SCR denitration efficiency can be improved.

Compared with the prior art, the present invention has the following advantages:

(1) The present invention can expand the denitration operation range of the SCR system, and can realize high-efficiency denitration under all working conditions;

(2) Compared with the flue gas bypass technology, the present invention can improve the boiler efficiency by 0.3% to 0.8%;

(3) The present invention can realize the variable load operation of the coal-fired generator set above 3% of the rated load/min, and at the same time improve the power generation efficiency and denitration efficiency of the coal-fired generator set during rapid variable load operation.

Description of drawings

FIG. 1 is a schematic diagram of the system structure of the present invention.

FIG. 2 is a comparison diagram of the flue gas temperature at the inlet of the coal-fired generator set using the SCR of the present invention.

FIG. 3 is a graph showing the change trend of the output power of the case coal-fired generator set using the present invention.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

As shown in FIG. 1, an efficient, clean, flexible and collaborative coal-fired power generation system of the present invention includes an economizer 2, an SCR denitration device 3 and a pre-economizer 4 that are sequentially arranged in the flue of the boiler 1 along the flue gas flow direction. The rear flue of the pre-economizer 4 is divided into two parallel separated flues. One side of the separated flue is arranged along the flue gas flow direction, and the No. 1 flue gas baffle 51 and the air preheater 53 are arranged in sequence, and the other side is along the flue gas flow direction. The No. 2 flue gas baffle 52, the No. 1 split economizer 54 and the No. 2 split economizer 55 are arranged in sequence; the water outlet of the economizer 2 is connected to the water inlet of the water wall, and the water inlet of the economizer 2 is connected to the pre-coal economizer The water outlet of the first economizer 4 is connected to the water outlet of the first economizer 4, and is also connected to the water inlet of the pre-economizer 4 through the No. 1 water supply regulating valve 61; the water inlet of the pre-economizer 4 is connected to the water outlet of the No. The regulating valve 62 is connected to the water outlet of the high pressure heater group 7; the water inlet of the No. 1 split economizer 54 is connected to the water outlet of the second split economizer 55, and is also connected to the water outlet of the high pressure heater group 7 through the No. 3 water supply regulating valve 63 The water inlet of No. 2 split economizer 55 is connected to the water outlet of the feed pump 8 through the No. 4 feed water regulating valve 64; the water inlet of the high pressure heater group 7 is connected to the water outlet of the feed pump 8.

As a preferred embodiment of the present invention, the area of the pre-economizer 4 is 0.2 to 0.4 times the area of the economizer 2, so that the inlet flue gas temperature of the SCR denitration device 3 can be maintained at an appropriate level within the entire working condition. working temperature area.

As a preferred embodiment of the present invention, the area of the No. 1 split-flow economizer 54 is 0.5 to 0.8 times the area of the No. 2 split-flow economizer 55, which can improve the matching relationship between the flue gas heat release and the working fluid system, and improve the System energy utilization efficiency, and reduce system investment.

As a preferred embodiment of the present invention, the No. 1 water supply regulating valve 61, No. 2 water supply regulating valve 62, No. 3 water supply regulating valve 63 and No. 4 water supply regulating valve 64 are electric automatic regulating valves, which can enhance the regulation performance of the system .

In the operation method of an efficient, clean, flexible and collaborative coal-fired power generation system according to the present invention, the inlet flue gas temperature of the SCR denitration device 3 is adjusted by adjusting the No. 1 feedwater control valve 61 to meet the working temperature range of the SCR denitration device 3. The specific adjustment method is as follows: , measure the inlet flue gas temperature of SCR denitration device 3, if the measured inlet flue gas temperature of SCR denitration device 3 is higher than the maximum working temperature of SCR denitration device 3, increase the opening degree of No. 1 feedwater regulating valve 61; measure and measure SCR denitration If the inlet flue gas temperature of the device 3 is lower than the working temperature of the SCR denitration device 3, the opening degree of the No. 1 feedwater regulating valve 61 is reduced;

When the coal-fired power generation system needs to increase the load rapidly, increase the opening of the No. 4 feedwater control valve 64, decrease the opening of the No. 3 feedwater control valve 63, increase the opening of the No. 2 feedwater control valve 62, and decrease the opening of the No. The opening degree of No. 61 water supply control valve;

By adjusting the opening degrees of the No. 1 flue gas baffle 51 and the No. 2 flue gas baffle 52, the flue gas temperature at the flue gas outlet at the tail of the boiler 1 is minimized.

The working temperature range of the SCR denitration device 3 is 300°C to 400°C.

As a preferred embodiment of the present invention, the flue gas flow of the No. 2 flue gas baffle 52 accounts for 20% to 40% of the total flue gas flow, so that the boiler can have the highest operating efficiency.

The system of the present invention can switch the system configuration when the unit operates in different intervals, so as to maintain the SCR inlet flue gas temperature in the most suitable operating interval for the activity of the SCR denitration catalyst. As shown in Figure 2, a coal-fired generator set adopts the system and operation method of the present invention. After calculation, in the entire load rate range of 0.3 to 1.0, the SCR inlet flue gas temperature can be controlled above 320 °C. At the same time, the present invention can improve the efficiency of the coal-fired generating set, maintain the boiler efficiency above 92% under various load rates, and improve the boiler efficiency by 0.3% to 0.8% compared with the flue gas bypass technology.

In addition, the present invention can increase the ramp rate of the unit. As shown in FIG. 3 , a coal-fired generating unit adopts the system and operation method of the present invention, and after calculation, the variable load rate can be increased to more than 3% rated load/min. Adjusting the relevant valve opening can ensure the denitration efficiency of the SCR device.

Claims (7)

1. An efficient, clean, flexible and collaborative coal-fired power generation system, characterized in that it comprises an economizer (2), an SCR denitration device (3) and a pre-economizer that are sequentially arranged in the flue of the boiler (1) tail along the flue gas flow direction. The coal collector (4), the rear flue of the front economizer (4) is divided into two parallel separated flues, and one side of the separated flue is sequentially arranged along the flue gas flow direction with the No. 1 flue gas baffle (51) and air preheating On the other side, the No. 2 flue gas baffle (52), the No. 1 split economizer (54) and the No. 2 split economizer (55) are arranged in sequence along the flue gas flow direction; The water outlet of the economizer (2) is connected to the water inlet of the water cooling wall, the water inlet of the economizer (2) is connected to the water outlet of the pre-economizer (4), and is also connected to the pre-economizer through the No. 1 water supply regulating valve (61). The water inlet of the coal collector (4) is connected to the water inlet; the water inlet of the pre-economizer (4) is connected to the water outlet of the No. 1 split-flow economizer (54), and is also connected to the high-pressure heater group (7) through the No. 2 water supply regulating valve (62). ) water outlet is connected; the water inlet of the No. 1 split economizer (54) is connected to the water outlet of the No. 2 split economizer (55), and is also connected to the water outlet of the high-pressure heater group (7) through the No. 3 water supply regulating valve (63). The water inlet of the No. 2 split economizer (55) is connected with the water outlet of the feed pump (8) through the No. 4 feed water regulating valve (64); the water inlet of the high pressure heater group (7) is connected with the water outlet of the feed pump (8) . 2. An efficient, clean, flexible, and collaborative coal-fired power generation system according to claim 1, characterized in that: the area of the pre-economizer (4) is 0.2 to 0.4 times the area of the economizer (2). 3. An efficient, clean, flexible and collaborative coal-fired power generation system according to claim 1, characterized in that: the area of the No. 1 split economizer (54) is 0.5 of the area of the No. 2 split economizer (55). to 0.8 times. 4. An efficient, clean, flexible, and collaborative coal-fired power generation system according to claim 1, characterized in that: the No. 1 water supply regulating valve (61), the No. 2 water supply regulating valve (62), and the No. 3 water supply regulating valve ( 63) and No. 4 water supply regulating valve (64) are electric automatic regulating valves. 5. The operation method of an efficient, clean, flexible, and coordinated coal-fired power generation system according to any one of claims 1 to 4, wherein the inlet of the SCR denitration device (3) is adjusted by adjusting the No. 1 feedwater control valve (61). The flue gas temperature meets the working temperature range of the SCR denitration device (3). The specific adjustment method is to measure the inlet flue gas temperature of the SCR denitration device (3). If the measured inlet flue gas temperature of the SCR denitration device (3) is higher than that of the SCR denitration device ( 3), increase the opening of the No. 1 feedwater regulating valve (61); measure the inlet flue gas temperature of the SCR denitration device (3), if it is lower than the working temperature of the SCR denitration device (3), Then reduce the opening of No. 1 water supply regulating valve (61); When the coal-fired power generation system needs to increase the load rapidly, increase the opening of the No. 4 feedwater control valve (64), decrease the opening of the No. 3 feedwater control valve (63), and increase the opening of the No. 2 feedwater control valve (62). opening, reduce the opening of the No. 1 water supply control valve (61); By adjusting the opening degrees of the No. 1 flue gas baffle (51) and the No. 2 flue gas baffle (52), the temperature of the flue gas at the tail flue gas outlet of the boiler (1) is minimized. 6 . The operation method according to claim 5 , wherein the flue gas flow of the No. 2 flue gas baffle ( 52 ) accounts for 20% to 40% of the total flue gas flow. 7 . 7. The operation method according to claim 5, characterized in that: the operating temperature range of the SCR denitration device (3) is 300°C to 400°C.

Images