CN218154187U - SCR deNOx systems's gas temperature governing system - Google Patents

Abstract

The utility model discloses a flue gas temperature governing system of SCR deNOx systems, including middle warehouse style powder process system, middle warehouse style powder process system connects and switches on hot primary air pipeline and tertiary air pipeline respectively, and hot primary air pipeline connects and switches on the air heater of primary air mechanism, and tertiary air pipeline connects and switches on the ventilation air spout in the boiler furnace, still includes the natural gas line, and natural gas line one end is connected and switches on the external air supply, and the other end of the natural gas line connects and switches on hot primary air bypass pipeline; the hot primary air bypass pipeline is connected and communicated with the tertiary air pipeline at the position of the outlet of the powder discharge fan; the hot primary air bypass pipeline is connected and communicated with the hot primary air pipeline. The utility model discloses with the hot primary air of some high temperature through the natural gas of hot primary air bypass pipeline with natural gas line internal input in advance, then introduced tertiary air pipeline and tertiary air and mix, send into furnace on the boiler through the ventilation air methane spout at last and burn.

Description

A flue temperature regulation system of an SCR denitrification system

technical field

The utility model relates to a smoke temperature regulating system of an SCR denitrification system, in particular to a smoke temperature regulating system of an SCR denitrification system which adopts tertiary air nozzle supplementary combustion under low load, and belongs to the field of coal-fired boilers.

Background technique

The scale of new energy power generation continues to increase, and coal-fired units are facing the situation of long-term low-load and deep peak regulation. The inlet smoke temperature of the Selective Catalytic Reduction (hereinafter referred to as SCR) system at low load is relatively low, often at the lower limit of the designed smoke temperature of the catalyst.

Coal-fired power plants that use intermediate storage pulverizing systems are generally designed to use lean coal and anthracite coal with poor burnout rates. At present, a large number of such units put into operation have problems such as poor burnout rate, high carbon content in fly ash, low combustion efficiency of boilers, excessive discharge of pollutants such as NO _X and CO, especially the current low-load deep peak-shaving policy , The inlet smoke temperature of the SCR system is low under low load, often at the lower limit of the catalyst design smoke temperature.

Intermediate storage type pulverizing system, the coal is dried and ground inside the coal mill, the coal is dried by the hot air passing into the coal mill and the pulverized coal is sent out, and the pulverized coal passes through the coarse powder with the airflow The separator and fine powder separator arrive at the pulverized coal bin. The fine powder separator separates the pulverized coal from the airflow and stores it in the pulverized coal bin. The airflow containing about 5% pulverized coal after separation is called the tertiary air (depleted air). The tertiary air is pressurized by the powder exhaust fan and enters the upper part of the boiler furnace. The pulverized coal is first stored in the pulverized coal bin, and then sent to the boiler furnace by the hot air from the pulverized coal bin according to the load requirements.

In the current intermediate storage pulverizing system, the air temperature of the tertiary air separated by the fine powder separator is about 90 ℃ lower, and the coal type with high moisture content and low load working conditions are even lower. The low-temperature tertiary air carrying about 5% of the total pulverized coal has a great impact on the combustion efficiency of the boiler, because the tertiary air is at the uppermost part of the furnace, close to the furnace outlet, the temperature of the flue gas in this area is low, the path of the pulverized coal is short, and the combustion is not sufficient, resulting in flying The ash contains a lot of carbon, and the tertiary air with low air temperature increases the ignition heat of pulverized coal and also aggravates the insufficiency of combustion.

Therefore, how to increase the inlet smoke temperature of the SCR system under low load is an urgent problem to be solved.

Contents of the invention

The technical problem to be solved by the utility model is: how to increase the inlet smoke temperature of the SCR system under low load.

In order to solve the above technical problems, the technical solution of this utility model is to provide a flue temperature adjustment system of the SCR denitrification system, including an intermediate storage type pulverizing system, which is respectively connected and connected to the hot primary air duct and The tertiary air pipeline, the hot primary air pipeline is connected and connected to the air preheater of the primary air mechanism, the tertiary air pipeline is connected and connected to the exhaust air nozzle in the boiler furnace, and it is characterized in that it also includes a natural gas pipeline, and the natural gas One end of the pipeline is connected and connected to an external air source, the other end of the natural gas pipeline is connected and connected to the hot primary air bypass pipe; the hot primary air bypass pipe is connected to and connected to the tertiary air pipe at the outlet of the powder exhaust fan; The bypass pipe is connected and connected to the hot primary air pipe.

Preferably, the hot primary air bypass pipeline is provided with a damper; the damper is located between the connection between the natural gas pipeline and the hot primary air bypass pipeline and the connection between the hot primary air bypass pipeline and the hot primary air pipeline.

Preferably, the natural gas pipeline is provided with a regulating valve.

Preferably, both the regulating damper and the regulating valve are connected with the control system.

Preferably, the openings of the regulating damper and the regulating valve are linearly adjusted through the control system according to the variation range of the flue gas temperature at the inlet of the SCR system.

Preferably, the primary air mechanism further includes a fan, a cold primary air pipeline and an air preheater, and the outlet of the fan is connected through the air preheater and connected to the hot primary air pipeline.

Preferably, the outer walls of the tertiary air duct, the hot primary air bypass duct, and the hot primary air duct are all coated with thermal insulation material layers.

Compared with the prior art, the utility model has the following beneficial effects:

The utility model adds a hot primary air bypass pipe to the original primary air mechanism, and a part of the high-temperature hot primary air is premixed with the natural gas input in the natural gas pipeline through the hot primary air bypass pipe, and then introduced into the tertiary air pipe and the tertiary air pipe. The air is mixed, and finally sent to the upper furnace of the boiler through the exhaust air nozzle for combustion.

The utility model introduces a part of high-temperature hot primary air and natural gas into the tertiary air pipeline, improves the ratio of the tertiary air, optimizes the air distribution in the furnace, not only helps to promote the mixing of coal dust and smoke, but also makes the combustion of the furnace more intense, thereby reducing flyovers. The carbon content in the ash improves the combustion efficiency of the boiler, and the increase in the proportion of the tertiary air promotes the air depth classification in the furnace, which is beneficial to reduce the emission of NO _X.

The utility model can realize the purpose of adjusting the inlet smoke temperature of the SCR system, ensures that the SCR denitrification device can be put into operation under high load or low load, and achieves high efficiency and low pollution.

The utility model does not need to separately add natural gas burners and corresponding pipelines to the water-cooled walls around the furnace, and can be directly installed on the existing primary air mechanism, hot primary air bypass pipeline and tertiary air pipeline, with simple structure and low installation cost. Has good practical value.

Description of drawings

Fig. 1 is a schematic diagram of a flue temperature regulating system of an SCR denitrification system;

Figure 2 is a block diagram of the control system controlling the opening of the damper and the regulating valve.

detailed description

In order to make the utility model more comprehensible, preferred embodiments are described in detail below with accompanying drawings.

The utility model provides a smoke temperature regulating system of an SCR denitrification system, as shown in Figure 1, which includes an intermediate storage type pulverizing system 1, a primary air mechanism 2, a powder exhaust fan 10, a tertiary air duct 3, a hot primary air Bypass pipeline 4, natural gas pipeline 5. The intermediate storage type pulverizing system 1 is respectively connected and connected to the hot primary air pipeline 24 and the tertiary air pipeline 3, the hot primary air pipeline 24 is connected to and connected to the air preheater 23 of the primary air mechanism 2, and one end of the natural gas pipeline 5 is connected and connected to Through the external air source, the other end is connected and connected to the hot primary air bypass pipe 4. The hot primary air bypass pipe 4 is connected and connected to the tertiary air pipe 3 after the powder discharge fan 10 (that is, the outlet end of the powder discharge fan 10, or the side of the powder discharge fan 10 away from the intermediate storage type pulverizing system 1), and the three times The air duct 3 is connected and connected to the exhaust air nozzle 9 in the boiler furnace 8 . The hot primary air bypass pipe 4 is connected and connected to the hot primary air pipe 24 .

The natural gas pipeline 5 is provided with a regulating valve 7; the hot primary air bypass pipe 4 is provided with a regulating damper 6, and the regulating damper 6 is located at the connection between the natural gas pipeline 5 and the hot primary air bypass pipe 4 and the hot primary air bypass pipe 4 Between the connection with the hot primary air duct 24.

The damper 6 and the damper 7 are controlled by the control system; the opening of the damper 6 and the damper 7 can be adjusted linearly according to the range of flue gas temperature change at the inlet of the SCR system, as shown in Figure 2. That is, after the data of flue gas temperature is transmitted to the control system, the control system issues instructions to adjust the opening degrees of the damper 6 and the control valve 7 .

The primary air mechanism 2 also includes a fan 22 , a cold primary air pipeline 21 and an air preheater 23 , and the outlet of the fan 22 is connected to the hot primary air pipeline 24 through the air preheater 23 .

The outer wall of the tertiary air duct 3 , the hot primary air bypass duct 4 , and the hot primary air duct 24 is covered with a thermal insulation material layer.

The working principle of the utility model is as follows:

The cold primary air at the outlet of the fan 22 is heated by the air preheater 23 to generate hot primary air. Part of the hot primary air at the outlet of the air preheater 23 enters the intermediate storage type pulverizing system 1 through the hot primary air pipeline 24 for pulverization, and the other part of the hot primary air passes through the hot primary air bypass connected to the hot primary air pipeline 24 The pipeline 4 is pre-mixed with the natural gas in the natural gas pipeline 5 connected to the natural gas pipeline 5 after being adjusted by the damper 6, and then enters the tertiary air pipeline 3 and mixes with the tertiary air (depleted air) in the tertiary air pipeline 3 and passes through Exhaust air nozzle 7 enters boiler furnace 8 to participate in combustion. The amount of natural gas and bypass hot primary air volume is controlled by the system according to the inlet smoke temperature of the SCR system.

In this embodiment, by mixing hot primary air and natural gas into the tertiary air, on the one hand, the ratio of the tertiary air is increased, the air distribution in the furnace is optimized, the mixing of pulverized coal and smoke is promoted, the combustion of the furnace is stronger, and the carbon content of fly ash is reduced. The amount and the combustion efficiency of the boiler are improved, and the increase in the proportion of the tertiary air promotes the air depth classification in the furnace, which is conducive to reducing the emission of NO _X , and finally achieves the purpose of improving the operating economy and environmental protection of the unit. On the other hand, through the supplementary combustion of natural gas in the upper part of the furnace, the purpose of adjusting the inlet smoke temperature of the SCR system can be achieved, ensuring that the SCR denitrification device can be put into operation under high load or low load, achieving high efficiency and low pollution.

Claims (7)

1. A smoke temperature regulating system of an SCR denitrification system, comprising an intermediate storage type pulverizing system (1), the intermediate storage type pulverizing system (1) is respectively connected and connected to a hot primary air duct (24) and a tertiary air duct ( 3), the hot primary air pipe (24) is connected and connected to the air preheater (23) of the primary air mechanism (2), the tertiary air pipe (3) is connected and connected to the exhaust air nozzle in the boiler furnace (8) (9), characterized in that it also includes a natural gas pipeline (5), one end of the natural gas pipeline (5) is connected to and connected to an external gas source, and the other end of the natural gas pipeline (5) is connected to and connected to a hot primary air bypass pipeline (4); The hot primary air bypass pipe (4) is connected and connected to the tertiary air pipe (3) at the outlet of the powder discharge fan (10); the hot primary air bypass pipe (4) is connected to and connected to the heat once Air duct (24). 2. The flue temperature regulating system of a kind of SCR denitrification system as claimed in claim 1, is characterized in that, described hot primary air bypass pipe (4) is provided with regulating damper (6); Regulating damper (6) It is located between the connection between the natural gas pipeline (5) and the hot primary air bypass pipeline (4) and the connection between the hot primary air bypass pipeline (4) and the hot primary air pipeline (24). 3. The flue temperature regulating system of an SCR denitrification system according to claim 2, characterized in that, the natural gas pipeline (5) is provided with a regulating valve (7). 4. The flue temperature regulating system of an SCR denitrification system according to claim 3, characterized in that, both the regulating damper (6) and the regulating valve (7) are connected to the control system. 5. The flue temperature regulating system of a kind of SCR denitrification system as claimed in claim 4, is characterized in that, the opening degree of described damper (6) and regulating valve (7) is according to SCR system entrance flue gas temperature respectively. The range of change is linearly adjusted by the control system. 6. The flue temperature regulating system of a kind of SCR denitrification system as claimed in claim 1, is characterized in that, described primary air mechanism (2) also comprises blower fan (22), cold primary air duct (21) and air preheating Heater (23), the outlet of blower fan (22) is connected by air preheater (23) and connects hot primary air pipeline (24). 7. The flue temperature regulating system of a kind of SCR denitrification system as claimed in claim 1, is characterized in that, described tertiary air duct (3), hot primary air bypass duct (4), hot primary air duct (24 ) are covered with a layer of thermal insulation material on the outer wall.

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