CN204345619U - A kind of burner reducing nitrogen oxide emission - Google Patents

Abstract

A combustion device for reducing the emission of nitrogen oxides, including a boiler. The boiler is provided with a gas tank and a flue gas pipeline with a flue gas circulation fan outside the boiler. There are two gas pipelines in the gas tank, one of which is connected to the boiler The upper part of the combustion device installed on one side of the inner furnace wall communicates with the upper part of the combustion device, while the other one communicates with the flue gas pipeline to form a flue gas mixing pipeline, and then communicates with the lower part of the combustion device through a gas mixing device. The utility model makes the NOx concentration of the boiler flue gas lower than 100mg/Nm ³ through its redesigned gas, combustion-supporting air, coal powder, fuel oil and flue gas mixed gas pipeline, which meets the national standard and reduces environmental pollution. The utility model has the advantages of simple structure, low cost, minor changes to the existing boiler, and greatly reduced labor intensity of operators. The utility model is applicable to the field of reducing flue gas nitrogen oxide emission and reducing environmental pollution of large coal-fired generating units.

Description

A combustion device for reducing nitrogen oxide emissions

technical field

The utility model relates to a combustion device, in particular to a combustion device applied to a large coal-fired generating set for the purpose of reducing flue gas nitrogen oxide emissions and reducing environmental pollution.

Background technique

At present, my country, as a large thermal power generation country, consumes about 1.1 billion tons of coal every year, and emits nearly 6 million tons of nitrogen oxides (hereinafter referred to as NOx). The unit coal consumption is 65 grams higher than that of foreign countries on average. 400 million tons, NOx emissions are nearly 2 million tons, resulting in a huge waste of energy and environmental pollution, so the control of NOx emissions has become a very urgent task for our country to control environmental pollution.

The Ministry of Environmental Protection and the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China jointly issued the "Emission Standards of Air Pollutants for Thermal Power Plants" GB13223-2011 in July 2011. The standard stipulates that from July 1, 2014, the NOx emission concentration of existing coal-fired unit boilers should be less than 100mg/Nm ³ .

In order to achieve the above-mentioned goals, under the existing technology, domestic boilers have adopted a method of controlling NOx emissions, that is, the combined application of low NOx burners and air staged combustion technologies. However, affected by the coal quality, combustion technology, and operation mode of the combustion system, the NOx emission concentration often fluctuates between 300mg/Nm ³ and 500mg/Nm ³ . Therefore, it is difficult to make boiler NOx emissions meet the requirements of national environmental protection standards only by relying on the two combustion technologies of the prior art.

In order to further reduce NOx emissions under the existing technology, there is also a technology to reduce boiler tail flue gas purification, which can greatly reduce NOx emissions. This technology is divided into two different technologies:

1. Selective catalyst reduction (SCR) denitrification technology;

2. Selective catalyst-free reduction (SNCR) denitrification technology.

The first SCR flue gas denitrification technology can further reduce the NOx emission concentration by 80-90% on the basis of combustion suppression measures. However, the SCR denitrification method still has the disadvantages of large project investment, short catalyst working life, large floor area, and high operating costs.

The second SNCR flue gas denitrification technology can reduce the NOx emission concentration by another 20-30% on the basis of combustion suppression measures. However, it directly sprays 10% urea solution into the furnace, which will reduce the thermal efficiency of the boiler, so this method is rarely used.

If only the existing technology is used to make the NOx emission concentration of coal-fired units below 100mg/ ^Nm3 , the low-nitrogen combustion technology in the furnace must be used first to reduce the NOx emission concentration to below 500mg/Nm3, and then the SCR flue gas denitrification technology should be used again. 80-90% drop. However, the implementation of this combined combustion method requires large engineering investment, many parameters to be monitored, and labor-intensive operators, so it is difficult to promote it now.

To sum up, there is an urgent need for a new type of combustion device that can reduce NOx emissions while also requiring lower cost, less investment, and reduced labor intensity for operators.

Utility model content

In order to solve the problem that the NOx emission concentration of the coal-fired units in the prior art is not up to the standard, and the combined combustion method is implemented with large engineering investment, many parameters to be monitored, and high labor intensity of the operators, the utility model redesigns a The new type of combustion device reduces NOx emissions through low-NOx combustion in the furnace, and at the same time, the cost is low, and the changes to the existing boilers are minor. Concrete structure of the present utility model is as follows:

A combustion device for reducing nitrogen oxide emissions, including a boiler, characterized in that:

The boiler is provided with a gas tank and a flue gas pipeline with a flue gas circulation fan on the outside. There are two gas pipelines in the gas tank. The other one communicates with the flue gas pipeline to form a flue gas mixing pipeline, and then communicates with the lower part of the combustion device through a gas mixing device.

A combustion device for reducing nitrogen oxide emissions according to the utility model is characterized in that the combustion device includes a frame, an overburning air nozzle, a gas reburning nozzle, an air nozzle, a thick-thin separation type coal powder nozzle, a fuel oil Air nozzles, fuel oil nozzles and low calorific value gas nozzles, wherein the frame is fixed vertically on one side of the inner furnace wall of the boiler, and the uppermost frame body of the frame is provided with an overfired air nozzle. The upper frame body below the burn-out air nozzle is provided with a gas reburning nozzle. The frame body is provided with an air nozzle and a thick-lean separation type coal powder nozzle group, and a fuel air nozzle is provided on the lower frame body of the frame. One end of the fuel air nozzle is inside the boiler, and the other end is connected with the fuel nozzle The external fuel oil circuit is connected, and the low calorific value gas nozzle is arranged at the bottom of the frame, and the low calorific value gas nozzle communicates with the pipeline of the gas mixing device outside the boiler.

The key point of the design here is that the gas reburning nozzle is supplied with fuel through the gas tank and the gas pipeline, the gas supplied by another gas pipeline and the low-temperature flue gas (temperature At 300°C ~ 400°C (generally at the outlet of the economizer), after being mixed by the gas mixing device, the low calorific value gas is supplied to the boiler furnace through the low calorific value gas nozzle.

A combustion device for reducing nitrogen oxide emissions according to the utility model is characterized in that an air nozzle and a thick-thin separation type pulverized coal nozzle group are arranged on the middle frame body at the lower part of the gas reburning nozzle. Specifically, 5 to 7 groups of air nozzles and thick-thin separation type coal powder nozzles are respectively arranged on the frame body of the middle section at equal intervals from top to bottom.

A combustion device for reducing nitrogen oxide emissions according to the utility model is characterized in that the burn-off air nozzles, air nozzles and fuel air nozzles are connected to the air box, and are provided by a groove outside the boiler. The air is supplied by the large air box, which provides combustion air to the boiler.

A combustion device for reducing nitrogen oxide emissions according to the utility model is characterized in that the gas reburning nozzles, thick-lean separation type coal powder nozzles, fuel oil nozzles and low calorific value gas nozzles all pass through the wind box and are connected with their respective fuel The system is connected to provide various combustibles to the boiler.

A combustion device for reducing nitrogen oxide emissions according to the utility model is characterized in that the gas reburning nozzle is placed 2 to 4 m above the uppermost thick-thin separation type coal powder nozzle on the frame body of the middle section The position of the overburning air nozzle is placed 6-8m above the dense-lean separation type pulverized coal nozzle.

A combustion device for reducing the emission of nitrogen oxides according to the utility model is characterized in that the exhaust air nozzle, the gas reburning nozzle, the air nozzle, the fuel air nozzle and the fuel nozzle can all swing up and down by 30°, and the adjustment Spray direction.

The overall design concept of the utility model is that the frame of the combustion device is fixed vertically on one side of the inner furnace wall of the boiler, and the over-burning air nozzle, the gas reburning nozzle, the air nozzle and the concentration separation are arranged sequentially from top to bottom. Coal powder nozzle group, fuel air nozzle and its connected fuel nozzle and low calorific value gas nozzle, each nozzle is respectively connected with different gas, combustion air, coal powder, fuel oil and flue gas mixed gas pipelines, so that the inside of the boiler is formed. Low NOx pulverized coal combustion, air staged combustion, gas reburning and flue gas recirculation, and finally through the low NOx combustion in the furnace, the NOx concentration of the boiler flue gas is lower than 100mg/Nm ³ .

Use a kind of combustion device that reduces nitrogen oxide discharge of the present utility model to obtain following beneficial effect:

1. A combustion device for reducing the emission of nitrogen oxides of the present utility model, through its redesigned gas, combustion-supporting air, pulverized coal, fuel oil and flue gas mixed gas pipeline, the NOx concentration of the boiler flue gas is lower than 100mg /Nm ³ , in line with national standards, reducing environmental pollution.

2. The utility model has the advantages of simple structure, low cost, and minor changes to the existing boiler, greatly reducing the labor intensity of the operators.

Description of drawings

Fig. 1 is the concrete structure schematic diagram of a kind of combustion device that reduces nitrogen oxide discharge of the present utility model;

Fig. 2 is a schematic diagram of the specific installation and implementation of a combustion device for reducing the emission of nitrogen oxides of the present invention.

In the figure: 1-boiler, 2-gas tank, 2a-gas pipeline, 3-flue gas circulation fan, 3a-flue gas pipeline, 4-gas mixing device, A-combustion device, A1-frame, A2- Burn-out air nozzle, A3-gas reburning nozzle, A4-air nozzle, A5-thickness separation type coal powder nozzle, A6-fuel air nozzle, A7-fuel nozzle, A8-low calorific value gas nozzle.

Detailed ways

A combustion device for reducing the emission of nitrogen oxides of the present utility model will be further described below in conjunction with the accompanying drawings and embodiments.

Example

As shown in Figures 1 and 2, a combustion device for reducing the emission of nitrogen oxides includes a boiler 1, which is provided with a gas tank 2 and a flue gas pipeline 3a with a flue gas circulation fan 3 outside the boiler. There are two gas pipelines 2a in the gas tank, one is connected to the upper part of the combustion device A installed on one side of the inner furnace wall of the boiler, and the other is connected to the flue gas pipeline to form a flue gas mixing pipeline, and then passes through a The gas mixing device 4 communicates with the lower part of the combustion device.

Combustion device A includes frame A1, burn-out air nozzle A2, gas reburning nozzle A3, air nozzle A4, thick-thin separation type coal powder nozzle A5, fuel air nozzle A6, fuel oil nozzle A7 and low calorific value gas nozzle A8, among which, the frame It is fixed vertically on one side of the inner furnace wall of the boiler. The overburning air nozzle is installed on the uppermost frame body of the frame, and the upper frame body below the overburning air nozzle is installed There is a gas reburning nozzle, and the gas reburning nozzle is connected with the gas pipeline directly connected to the boiler inside the gas pipeline 2a of the gas tank 2, and an air nozzle and a thick-thin separation briquette are arranged on the middle frame body of the lower part of the gas reburning nozzle The powder nozzle group is provided with a fuel air nozzle on the frame body of the lower part of the frame. One end of the fuel air nozzle is inside the boiler, and the other end is connected to the external fuel oil circuit through the fuel nozzle, while the low calorific value gas nozzle is set At the bottom of the frame, the low calorific value gas nozzle communicates with the gas mixing device 4 outside the boiler.

The gas reburning nozzle A3 supplies fuel through the gas tank 2 and the gas pipeline 2a, the gas supplied by another gas pipeline and the low-temperature flue gas supplied by the flue gas pipeline 3a with the flue gas circulation fan 3 at the tail of the boiler (the temperature is between 300°C to 400°C (generally at the outlet of the economizer) is mixed by the gas mixing device 4, and then the low calorific value gas is supplied to the boiler furnace through the low calorific value gas nozzle A8.

The air nozzle A4 and the thick-thin separation type pulverized coal nozzle A5 group are arranged on the middle frame body of the lower part of the gas reburning nozzle. 5 to 7 groups of air nozzles and thick-thin separation type coal powder nozzles.

The burn-off air nozzle A2, the air nozzle A4 and the fuel air nozzle A6 are connected to the air box and supplied with air by a trough-shaped large air box arranged outside the boiler to provide combustion-supporting air into the boiler.

The gas reburning nozzle A3, thick-lean separation type pulverized coal nozzle A5, fuel oil nozzle A7 and low calorific value gas nozzle A8 all pass through the wind box and connect with their respective fuel systems to provide various combustibles to the boiler.

The gas reburning nozzle A3 is placed 2 to 4 m above the uppermost dense-lean separation type coal powder nozzle A5 on the middle frame body, and the overburning air nozzle A2 is placed 6 meters above the dense-lean separation type coal powder nozzle ~8m position.

The overburning air nozzle A2, the gas reburning nozzle A3, the air nozzle A4, the fuel air nozzle A6 and the fuel nozzle A7 can all swing up and down by 30° to adjust the injection direction.

The overall design concept of the utility model is that the frame of the combustion device is fixed vertically on one side of the inner furnace wall of the boiler, and the overburning air nozzle, the gas reburning nozzle, the air nozzle and the concentration separation are arranged sequentially from top to bottom. Coal powder nozzle group, fuel air nozzle and its connected fuel nozzle and low calorific value gas nozzle, each nozzle is respectively connected with different gas, combustion air, coal powder, fuel oil and flue gas mixed gas pipelines, so that the inside of the boiler is formed. Low NOx pulverized coal combustion, air staged combustion, gas reburning and flue gas recirculation, and finally through the low NOx combustion in the furnace, the NOx concentration of boiler flue gas is lower than 100mg/Nm ³ .

In addition, the utility model can install several sets in the furnace wall of the boiler according to the needs, so as to further reduce the emission of NOx.

A combustion device for reducing nitrogen oxide emissions of the utility model, through its redesigned gas, combustion air, coal powder, fuel oil and flue gas mixed gas pipeline, the NOx concentration of the boiler flue gas is lower than 100mg/Nm ^3. It conforms to national standards and reduces environmental pollution. The utility model has simple structure and low cost, and the existing boilers are slightly modified, and the labor intensity of operators is greatly reduced. The utility model is applicable to the field of reducing flue gas nitrogen oxide emission and reducing environmental pollution of large coal-fired generating units.

Claims (7)

1. A combustion device for reducing emissions of nitrogen oxides, comprising a boiler (1), characterized in that: The boiler (1) is provided with a gas tank (2) and a flue gas pipeline (3a) with a flue gas circulation fan (3) outside it, and there are two gas pipelines (2a) of the gas tank, One is communicated with the upper part of the combustion device (A) installed on one side of the inner furnace wall of the boiler, while the other is communicated with the flue gas pipeline to form a flue gas mixing pipeline, and then passes through a gas mixing device (4) and the combustion device The lower part is connected. 2. A kind of combustion device for reducing nitrogen oxide emissions as claimed in claim 1, characterized in that, said combustion device (A) comprises a frame (A1), an exhaust air nozzle (A2), a gas reburning Nozzles (A3), air nozzles (A4), dense-thin separation type pulverized coal nozzles (A5), fuel air nozzles (A6), fuel oil nozzles (A7) and low calorific value gas nozzles (A8), where the frame is vertical It is fixed on one side of the furnace wall inside the boiler, and the burn-out air nozzle is installed on the frame body at the uppermost part of the rack, and the gas reburning nozzle is installed on the upper frame body below the burn-out air nozzle. , the gas reburning nozzle communicates with the gas pipeline (2a) of the gas tank (2) directly connected to the gas pipeline inside the boiler, and an air nozzle and a thick-thin separation briquette The powder nozzle group is provided with a fuel air nozzle on the frame body of the lower part of the frame. One end of the fuel air nozzle is inside the boiler, and the other end is connected to the external fuel oil circuit through the fuel nozzle, while the low calorific value gas nozzle is set At the lowest part of the frame, the low calorific value gas nozzle communicates with the pipeline of the gas mixing device (4) outside the boiler. 3. A kind of combustion device that reduces nitrogen oxide emissions as claimed in claim 2, is characterized in that, described in the middle frame frame body of gas reburning nozzle bottom, is provided with air nozzle (A4) and thick-thin separation The powdered coal nozzle (A5) group is specifically provided with 5 to 7 groups of air nozzles and thick-thin separation type coal powder nozzles at equal intervals from top to bottom on the middle frame body. 4. A kind of combustion device that reduces nitrogen oxide emissions as claimed in claim 2, is characterized in that, described burn-off air nozzle (A2), air nozzle (A4) and fuel air nozzle (A6), these The nozzle is connected with the air box, and the air is supplied by a trough-shaped large air box arranged outside the boiler to provide combustion-supporting air into the boiler. 5. A combustion device for reducing emissions of nitrogen oxides as claimed in claim 2, characterized in that, the gas reburning nozzle (A3), the thick-thin separation type coal powder nozzle (A5), the fuel nozzle (A7) and low calorific value gas nozzles (A8) are connected to their respective fuel systems through the air box to provide various combustibles to the boiler. 6. A kind of combustion device for reducing nitrogen oxide emissions as claimed in claim 2, characterized in that, said gas reburning nozzle (A3) is placed on the uppermost part of the thick-lean separation briquette on the frame body of the middle section 2-4m above the powder nozzle (A5), and the overburning air nozzle (A2) is placed 6-8m above the dense-lean separation type coal powder nozzle. 7. A combustion device for reducing emissions of nitrogen oxides as claimed in claim 2, characterized in that, said overburning air nozzle (A2), gas reburning nozzle (A3), air nozzle (A4), fuel oil Both the air nozzle (A6) and the fuel nozzle (A7) can swing up and down by 30° to adjust the injection direction.