WO2021238320A1

WO2021238320A1 - Configuration-adaptive flexible cleaning coordinated coal-fired power generation system and operation method

Info

Publication number: WO2021238320A1
Application number: PCT/CN2021/078892
Authority: WO
Inventors: 刘明; 严俊杰; 刘继平; 种道彤; 邢秦安
Original assignee: 西安交通大学
Priority date: 2020-05-24
Filing date: 2021-03-03
Publication date: 2021-12-02
Also published as: CN111637440A

Abstract

Disclosed in the present invention are a configuration-adaptive flexible cleaning coordinated coal-fired power generation system and an operation method. A coal economizer of the system is provided with a feed water control valve group which can control a heat exchange process between flue gas and a working medium, and adaptive adjustment of a configuration can be performed according to a load to change the heat exchange flow direction between the flue gas and the working medium, thus adjusting the inlet temperature of an SCR denitration apparatus, and achieving all-condition efficient operation of the SCR denitration apparatus. The system in the present invention has low investment, and a boiler using the system has high efficiency and high operation flexibility.

Description

Configuration self-adaptive flexible clean 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 a configuration self-adaptive, flexible and clean collaborative coal-fired power generation system and an operating method.

Background technique

Building a clean, "clean, low-carbon, safe and efficient" energy system is the development direction of my country's energy structure transformation. For this reason, in recent years, my country's large-scale installed capacity of renewable energy has developed rapidly, and at the same time, the efficiency of conventional fossil energy utilization has gradually improved. However, the time-varying characteristics of wind power and solar power generation are strong, threatening the safety of the power grid. For this reason, it is urgent to improve the operational flexibility of conventional coal-fired generating sets, that is, to increase the variable load range and variable load rate of coal-fired generating sets. Therefore, coal-fired generating units present new features of frequent and deep load changes.

However, when the unit is operating at low load, the denitrification efficiency of the coal-fired unit is significantly reduced. The main reason is that the SCR denitrification catalyst has a suitable operating temperature range, but when the unit is operating at reduced load, the temperature of the SCR inlet flue gas drops, which makes it difficult for the SCR denitrification device to operate in a suitable operating temperature range, resulting in a decrease in denitrification efficiency. The existing increase in SCR inlet flue gas temperature mainly includes flue gas bypass, economizer grading arrangement, water supply bypass, etc. However, the flue gas bypass technology transformation has a large workload, and the boiler efficiency is significantly reduced; the economizer graded layout transformation has a large workload; the feedwater bypass technology has limited flue gas temperature regulation performance, and the safety of the economizer operation is not easy to guarantee.

How to improve the operating performance of coal-fired power stations under all operating conditions, improve the operating flexibility and operating efficiency of coal-fired power stations, and reduce pollutant emissions is an urgent need for coal-fired power generation technology.

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 an adaptive, flexible, clean and cooperative coal-fired power generation system and operation method. The system can adaptively adjust the configuration according to load and change the flue gas , The heat exchange flow direction between the working fluids, so as to adjust the inlet temperature of the SCR denitrification device, and realize the efficient operation of the SCR denitrification device under all working conditions. The system investment of the invention is low, and the system boiler adopting the invention has high efficiency and high operation flexibility.

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

A configuration adaptive, flexible, clean and cooperative coal-fired power generation system, comprising an economizer 2 and an SCR denitrification device 4 arranged in the flue of the boiler 1 in sequence along the flue gas flow direction; the lower port of the economizer 2 passes through two pipes No. 32 and No. 1 feedwater regulating valve 31 are connected to the boiler feedwater inlet, and the No. 2 feedwater regulating valve 32 and No. 1 feedwater regulating valve 31 are connected to the water wall feedwater inlet through the No. 5 feedwater regulating valve 35 through a pipeline; The upper port of economizer 2 is connected to the feedwater inlet of the water wall through the pipeline through the No. 3 feedwater regulating valve 33, and the upper port of the economizer 2 is connected to the boiler feedwater inlet through the pipeline through the No. 4 feedwater regulating valve 34 and the No. 6 feedwater regulating valve 36 Connected; the boiler feedwater inlet is also connected to the water wall feedwater inlet through the No. 7 feedwater regulating valve 37 through the pipeline.

The boiler feedwater inlet is in communication with the outlet of the regenerative heater of the highest pressure of the steam turbine regenerative system.

The No. 1 water supply regulating valve 31 to No. 7 water supply regulating valve 37 are automatic regulating valves.

The described operation method of a configuration adaptive, flexible and clean cooperative coal-fired power generation system changes the flue gas and the flue gas in the economizer 2 by adjusting the regulating valve group of the No. 1 feedwater regulating valve 31 to the No. 7 feedwater regulating valve 37. The downstream and counter-current relationship of the feed water can adjust the inlet flue gas temperature of the SCR denitrification device 4 to meet the requirements of the working temperature range of the SCR denitrification device 4. The specific adjustment method is to measure the inlet flue gas temperature of the SCR denitrification device 4:

1) If the flue gas temperature at the inlet of the SCR denitrification device 4 is higher than its maximum operating temperature, first close the No. 7 feedwater regulating valve 37. If the inlet flue gas temperature of the SCR denitrification device 4 is still higher than its maximum working temperature, turn off the No. 4 feedwater regulator Valve 34, No. 5 feed water regulating valve 35 and No. 6 feed water regulating valve 36, open No. 1 feed water regulating valve 31, No. 2 feed water regulating valve 32 and No. 3 feed water regulating valve 33, so that boiler feed water enters from the lower port of economizer 2 The economizer 2 then flows out from the upper port of the economizer 2 into the water wall. At this time, the flue gas in the economizer 2 and the feed water are in a countercurrent relationship;

2) If the flue gas temperature at the inlet of the SCR denitrification device 4 is lower than its maximum operating temperature, gradually open the No. 4 feed water regulating valve 34, the No. 5 feed water regulating valve 35 and the No. 6 feed water regulating valve 36, and gradually close the No. 1 feed water regulating valve 31 and No. 3 feed water regulating valve 33, make the boiler feed water enter the economizer 2 from the upper port of the economizer 2 and then flow out from the lower port of the economizer 2 into the water wall. At this time, the flue gas and feed water in the economizer 2 are Downstream relationship; if the flue gas temperature at the inlet of the SCR denitrification device 4 is still lower than its minimum working temperature, gradually open the No. 7 feedwater regulating valve 37, so that the feedwater directly enters the water wall through the bypass.

The working temperature range of the SCR denitrification device 4 is 300°C to 400°C.

When adjusting the regulating valve group of the No. 1 feedwater regulating valve 31 to the No. 7 feedwater regulating valve 37, pay attention to the linkage of the switch of the feedwater regulating valve, so as to maintain the stability of the water pressure.

The system can realize self-adjustment and self-adaptation of the configuration when the unit is running at different loads. This operating method can maintain the temperature operating range of the denitrification device while ensuring the safety of the economizer operation. The invention can be used when the coal-fired unit that frequently changes the load operation improves the operation flexibility and improves the denitrification efficiency.

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

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

(2) The present invention has low transformation cost and can significantly reduce the transformation cost of SCR denitrification in all working conditions;

(3) The present invention can reduce the temperature of the working fluid at the outlet of the economizer during the adjustment process and ensure the safe operation of the economizer.

Description of the drawings

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

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

Figure 3 is a comparison diagram of the working fluid temperature at the outlet of the coal-fired generator set using the economizer of the present invention.

Detailed ways

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

As shown in Figure 1, an adaptive, flexible, clean and cooperative coal-fired power generation system of the present invention includes an economizer 2 and an SCR denitrification device 4 arranged in the flue of a boiler 1 in sequence along the flue gas flow direction; the economizer 2 The lower port is connected to the boiler feedwater inlet through the No. 2 feedwater regulating valve 32 and the No. 1 feedwater regulating valve 31 through the pipeline, and the No. 2 feedwater regulating valve 32 and the No. 1 feedwater regulating valve 31 are passed through the No. 5 feedwater regulating valve through the pipeline. 35 is connected to the water wall feedwater inlet; the upper port of the economizer 2 is connected to the water wall feedwater inlet through the pipeline through the No. 3 feedwater regulating valve 33, and the upper port of the economizer 2 is connected through the pipeline through the No. 4 feedwater regulating valve 34 and No. 6 The feedwater regulating valve 36 is connected to the boiler feedwater inlet; the boiler feedwater inlet is also connected to the water wall feedwater inlet via the No. 7 feedwater regulating valve 37 through a pipeline.

As a preferred embodiment of the present invention, the boiler feedwater inlet is connected to the outlet of the regenerative heater with the highest pressure of the steam turbine regenerative system, so that the boiler feedwater inlet temperature can be maintained within a suitable temperature range.

As a preferred embodiment of the present invention, the No. 1 feedwater regulating valve 31 to No. 7 feedwater regulating valve 37 are automatic regulating valves, which can improve the regulating performance of the system.

According to the operating method of the self-adaptive, flexible, clean and cooperative coal-fired power generation system of the present invention, the control valve group of the No. 1 feedwater regulating valve 31 to the No. 7 feedwater regulating valve 37 is adjusted to change the smoke in the economizer 2 The downstream and countercurrent relationship between the gas and the feed water, so as to adjust the inlet flue gas temperature of the SCR denitrification device 4 to meet the requirements of the working temperature range of the SCR denitrification device 4. The specific adjustment method is to measure the inlet flue gas temperature of the SCR denitrification device 4:

As a preferred embodiment of the present invention, when adjusting the regulating valve group of the No. 1 feedwater regulating valve 31 to the No. 7 feedwater regulating valve 37, attention should be paid to the linkage of the switch of the feedwater regulating valve, so as to maintain the stability of the water pressure.

The system of the present invention can switch the system configuration when the unit is operating in different intervals, so as to maintain the temperature of the flue gas at the inlet of the SCR in the active operation interval of the SCR denitration catalyst. As shown in Figure 2, using the system and operation method of the present invention, when the load factor of the coal-fired power generation system is below 0.5, the temperature of the flue gas at the inlet of the SCR is maintained above 300°C. Compared with the conventional flue gas bypass and the low-temperature economizer grading arrangement, the invention has lower transformation cost. As shown in Figure 3, compared with the conventional feedwater bypass system, the present invention has a lower working fluid temperature at the outlet of the economizer, which can ensure the safe operation of the economizer. The case unit can reduce the load factor of the coal-fired generator set when the load factor is 0.3. The working fluid temperature at the outlet of the economizer is 12°C.

Claims

An adaptive, flexible, clean and cooperative coal-fired power generation system, which is characterized in that it includes an economizer (2) and an SCR denitrification device (4) arranged in the flue of the boiler (1) along the flue gas flow direction; The lower port of the coal machine (2) is connected to the boiler feedwater inlet through the No. 2 feedwater regulating valve (32) and the No. 1 feedwater regulating valve (31) through the pipeline, the No. 2 feedwater regulating valve (32) and the No. 1 feedwater regulating valve (31) The upper port of the economizer (2) is connected to the water wall feedwater inlet via the No. 3 feedwater regulating valve (33) through the pipeline through the No. 5 feedwater regulating valve (35), which saves The upper port of the coal machine (2) is connected to the boiler feedwater inlet through the pipeline through the No. 4 feedwater regulating valve (34) and the No. 6 feedwater regulating valve (36); the boiler feedwater inlet is also connected through the pipeline through the No. 7 feedwater regulating valve (37) Connected to the water supply inlet of the water wall.
The self-adaptive, flexible, clean and cooperative coal-fired power generation system of claim 1, wherein the boiler feedwater inlet is connected to the outlet of the regenerative heater with the highest pressure of the steam turbine regenerative system.
The self-adaptive, flexible, clean and cooperative coal-fired power generation system according to claim 1, characterized in that: the No. 1 water supply regulating valve (31) to the No. 7 water supply regulating valve (37) are automatic regulating valves.
The operation method of an adaptive, flexible, clean and cooperative coal-fired power generation system according to claim 1, characterized in that: adjusting valves of No. 1 water supply regulating valve (31) to No. 7 water supply regulating valve (37) Group, so as to change the downstream and countercurrent relationship between flue gas and feed water in the economizer (2), thereby adjusting the inlet flue gas temperature of the SCR denitrification device (4) to meet the requirements of the working temperature range of the SCR denitrification device (4), and the specific adjustment method To measure the inlet flue gas temperature of SCR denitrification device (4):

1) If the flue gas temperature at the inlet of the SCR denitrification device (4) is higher than its maximum operating temperature, first close the No. 7 feedwater regulating valve (37). If the flue gas temperature at the inlet of the SCR denitrification device (4) is still higher than its maximum operating temperature , Close No. 4 water supply regulating valve (34), No. 5 water supply regulating valve (35) and No. 6 water supply regulating valve (36), open No. 1 water supply regulating valve (31), No. 2 water supply regulating valve (32) and No. 3 The feed water regulating valve (33) makes the boiler feed water enter the economizer (2) from the lower port of the economizer (2) and then flow out from the upper port of the economizer (2) into the water wall. At this time, the economizer (2) enters the economizer (2). The flue gas and water supply are in a countercurrent relationship;

2) If the flue gas temperature at the inlet of the SCR denitrification device (4) is lower than its maximum operating temperature, gradually open the No. 4 feedwater regulating valve (34), the No. 5 feedwater regulating valve (35) and the No. 6 feedwater regulating valve (36), And gradually close the No. 1 feedwater regulating valve (31) and No. 3 feedwater regulating valve (33), so that the boiler feedwater enters the economizer (2) from the upper port of the economizer (2) and then from the lower port of the economizer (2) Flow out into the water wall, at this time the flue gas in the economizer (2) and the feed water are in a downstream relationship; if the inlet flue gas temperature of the SCR denitrification device (4) is still lower than its minimum working temperature, gradually turn on the No. 7 feed water Adjust the valve (37) so that the feedwater directly enters the water wall through the bypass.
The operation method of an adaptive, flexible, clean and cooperative coal-fired power generation system according to claim 4, wherein the operating temperature range of the SCR denitrification device (4) is 300°C to 400°C.
The operation method of an adaptive, flexible, clean and cooperative coal-fired power generation system according to claim 4, characterized in that: adjusting the control valve group of the No. 1 water supply regulating valve (31) to the No. 7 water supply regulating valve (37) At the time, pay attention to the linkage of the water supply control valve switch to maintain the stability of the water pressure.