CN104759205B - A kind of high temperature air channel Benitration reactor and the method with its denitration - Google Patents

Abstract

The invention relates to a high-temperature air duct denitrification reactor and a denitrification method using the same. The high-temperature air duct denitrification reactor is a serpentine metal tubular air duct loaded with barbed wire inside, and its inlet is communicated with a NOx separation device for flue gas. The outlet communicates with the furnace. NOx and carbon monoxide gas flow into the serpentine metal tubular air duct and react under the catalysis of the wire mesh at 600-800°C to reduce NOx to generate harmless nitrogen and carbon dioxide. The incompletely reacted carbon monoxide is sprayed into the furnace from the outlet of the air duct. Participate in hearth combustion. The high-temperature air duct denitrification reactor of the present invention has simple structure, convenient installation, and low cost. It can be used in conjunction with a flue gas NOx separation device to achieve efficient removal of NOx in the flue gas in the furnace. The carbon monoxide gas used as the carrier gas can Combustion is carbon dioxide, avoiding secondary pollution, iron wire is non-toxic as a catalyst. At the same time, part of the heat can be recovered.

Description

A high-temperature air duct denitrification reactor and its denitrification method

technical field

The invention relates to a high-temperature air duct denitrification reactor and a denitrification method using the same. When used in conjunction with a NOx separation and enrichment device for flue gas, it can not only realize near-zero emission of nitrogen oxides, but also avoid secondary pollution caused by reducing agent discharge. , which belongs to the technical innovation field of coal-fired flue gas pollutant emission reduction.

Background technique

Nitrogen oxides (NOx) are one of the main air pollutants, which can form acid rain or acid mist combined with hydrocarbons to form photochemical smog and destroy the ozone layer. Currently, more than 60% of nitrogen oxides come from flue gas from coal combustion.

The "Emission Standard of Air Pollutants for Thermal Power Plants" (GB13223-2011) implemented on January 1, 2012 stipulates that the NO emission of all newly built thermal power units should reach 100mg/cm ³ . Starting from January 1, 2014, the NOx emissions of all thermal power units put into operation in key areas are required to reach 100mg/cm ³ , while units in non-key areas put into operation before 2003 are required to reach 200mg/cm ³ . The increasingly serious environmental pollution and strict emission standards require us to strive to achieve near-zero emissions of nitrogen oxides.

At present, catalytic reduction NOx technology (SCR) has become the most widely used, most mature and most effective flue gas denitrification technology in the world. This technology uses ammonia as a reducing agent, sprays it into the flue and mixes it fully with the flue gas, and then flows through the reactor loaded with SCR catalyst. Under the action of the catalyst, NOx in the flue gas is reduced to harmless nitrogen by the reducing agent ammonia. . NH ₃ -SCR technology has high denitrification efficiency, is mature and reliable, and has strong adaptability. It is especially suitable for coal-fired units in areas with variable coal quality, frequent unit load changes and sensitive air quality requirements. However, there are also certain problems in ammonia denitrification: using ammonia as a reducing agent will cause corrosion to the pipeline, improper control will cause ammonia to escape and cause secondary pollution, and the ammonium salt particles produced will block downstream equipment, and the cost of ammonia production is high. . Moreover, precious metals, metal oxides, etc. are mostly used as SCR catalysts, which are costly and complicated to manufacture.

When the iron wire is at a temperature of 600°C to 800°C, carbon monoxide can react with NOx to generate nitrogen and carbon dioxide. Iron wire is used as a catalyst, and CO is used as a denitrification reducing agent. CO can be produced by coal gasification or coal pyrolysis, which is convenient and low-cost for coal-fired power plants. Compared with precious metals and metal oxides, iron wire is easy to obtain and has high economic efficiency. . However, when iron wire is used as a catalyst, it is easily oxidized by oxygen and loses its catalytic effect, so this method is not feasible in conventional flue gas.

Contents of the invention

The purpose of the present invention is to provide a high-temperature air duct denitrification reactor and its denitrification method. The reactor is used in conjunction with a flue gas NOx separation and enrichment device to achieve near-zero NOx emissions. CO is selected as the reducing agent and iron wire is used as the catalyst. , low cost and avoid secondary pollution.

The technical scheme adopted in the present invention is:

A high-temperature air duct denitrification reactor, which is arranged in the boiler flue communicated with the furnace, the high-temperature air duct denitrification reactor is a serpentine metal tubular air duct loaded with barbed wire inside, and its inlet is connected to the NOx separation device of flue gas Connected, the outlet communicates with the furnace.

The barbed wire is arranged in multiple layers. The interval between each layer of barbed wire in the pipeline is 20-60mm, the diameter of the wire is 0.2-1.5mm, and the mesh interval is 1.5-8mm.

Micro-fins can be added to the pipes of the serpentine metal tubular air duct to enhance the heat exchange of the gas in the air duct.

The pipe length of the serpentine metal tubular air duct is determined by the flow rate and residence time of the gas in the air duct. Under a certain flow rate, the residence time is set to 5-10 seconds.

Using the above-mentioned high-temperature air duct denitrification reactor for denitrification, NOx and carbon monoxide gas flow into the serpentine metal tubular air duct, and react under the catalysis of the wire mesh at 600-800°C to reduce NOx and generate harmless nitrogen and carbon dioxide. Incompletely reacted carbon monoxide is sprayed into the furnace from the outlet of the air duct, and participates in the combustion of the furnace to generate harmless carbon dioxide.

In the NOx and carbon monoxide gases, the volume fraction of CO is 1.5-3 times that of NOx. It is obtained by separating the combustible gas through the flue gas NOx separation device. The combustible gas is NOx carrier gas, and the main component is carbon monoxide. It can be produced by coal-fired power stations through coal gasification or coal pyrolysis technology.

The flue gas NOx separation device can use a rotary denitration reactor (application number 2014101535846) or an air pre-denitration integrated reactor (application number 2014102467723) or other NOx adsorption and separation devices. The principle of this type of device is to use NOx adsorbent to adsorb NOx in the flue gas, and then use carbon monoxide gas to desorb the NOx on the surface of the adsorbent, so as to realize the separation and enrichment of NOx from the flue gas.

The present invention combines the flue gas NOx separation device to realize the mixing of NOx and carbon monoxide and the separation of oxygen in the flue gas. The reaction of NOx and carbon monoxide realizes the efficient and low-cost removal of NOx.

The high-temperature air duct denitrification reactor of the present invention has simple structure, convenient installation, and low cost, and can be used in conjunction with the NOx separation and enrichment device to achieve efficient removal of NOx in the flue gas in the furnace, and the carbon monoxide gas used as the carrier gas can be burned on the spot Carbon dioxide is used to avoid secondary pollution, and iron wire is non-toxic as a catalyst. At the same time, part of the heat can be recovered.

Description of drawings

Fig. 1 is a schematic structural diagram of a high-temperature air duct denitrification reactor of the present invention; wherein, a is a structural diagram of the reactor; b is a schematic cross-sectional view of the reactor air duct.

Figure 2 is a schematic diagram of the layout of the high-temperature air duct denitration reactor.

Among them, 1 is CO gas; 2 is CO+NOx gas; 3 is incompletely reacted CO gas; 4 is NOx separation device for flue gas; 5 is high-temperature air duct denitrification reactor; 6 is furnace.

detailed description

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

A high-temperature air duct denitrification reactor, which is arranged in the boiler flue communicated with the furnace 6, the high-temperature air duct denitrification reactor is a serpentine metal tubular air duct loaded with barbed wire inside, and its inlet is separated from the NOx of the flue gas The device 4 communicates, and the outlet communicates with the furnace 6 .

The snake-shaped metal tubular air duct is loaded with multi-layer barbed wire, and micro-fins are also added to enhance heat exchange. The regional temperature is around 600°C to 800°C, which can ensure the reaction between the reducing agent and NO _X under the catalysis of the iron wire. The inlet of the high-temperature air duct denitrification reactor 5 is CO+NOx gas 2, and its source is the NOx separation device 4 of the downstream flue gas. The NOx separation device of the flue gas can use a rotary denitrification reactor (application number 2014101535846) or other NOx adsorption separation device. The inlet of the flue gas NOx separation device 4 is CO gas 1, and the volume fraction of CO as a carrier gas is 1.5-3 times that of NOx. It can be prepared by coal-fired power plants through coal gasification or coal pyrolysis technology, and the cost is low. The incompletely reacted CO gas 3 in the high-temperature air duct denitrification reactor 5 is injected into the furnace 6 for combustion to avoid secondary pollution.

The high-temperature air duct denitrification reactor is used in conjunction with the NOx separation device, and CO is used as the reducing agent. The iron wire is used as a catalyst to realize the efficient removal of NOx in the flue gas in the furnace, with low cost and no secondary pollution, which is of great significance.

Claims (6)

1. the method for carrying out denitration using high temperature air channel Benitration reactor, is characterized in that, NO_xFlow into CO (carbon monoxide converter) gas snakelike Tubular metal air channel, reacts under the catalytic action of 600-800 DEG C of wire gauze, by NO_xReduction, generate harmless nitrogen and Carbon dioxide, the carbon monoxide not reacted completely spray into burner hearth by ducting outlet, participate in hearth combustion, generate harmless titanium dioxide Carbon；The NO_xThe processing mode flowed into before snakelike tubular metal air channel with CO (carbon monoxide converter) gas is to adopt NO_xAdsorbent adsorbs NO in flue gas_x, then the NO for being desorbed adsorbent surface with CO (carbon monoxide converter) gas_x；

Described high temperature air channel Benitration reactor is arranged in the boiler flue communicated with burner hearth, and described high temperature air channel denitration is anti- Answer the NO of the snakelike tubular metal air channel that device is interior loading wire gauze, its entrance and flue gas_xSegregation apparatuss are communicated, and are exported and burner hearth Communicate.

2. the method that high temperature air channel according to claim 1 Benitration reactor carries out denitration, is characterized in that, described NO_xWith The volume fraction of CO (carbon monoxide converter) gas, wherein CO is NO_x1.5-3 times.

3. the method that high temperature air channel according to claim 1 Benitration reactor carries out denitration, is characterized in that, described iron wire Net is arranged for multilamellar.

4. the method that high temperature air channel according to claim 3 Benitration reactor carries out denitration, is characterized in that, wire gauze is in pipe Per interlayer every 20-60mm, iron wire diameter 0.2-1.5mm, mesh spaces 1.5-8mm in road.

5. the method that high temperature air channel according to claim 1 Benitration reactor carries out denitration, is characterized in that, described is snakelike Micro- fin is added to process in the pipeline in tubular metal air channel.

6. the method that high temperature air channel according to claim 1 Benitration reactor carries out denitration, is characterized in that, described is snakelike The pipe range in tubular metal air channel by gas in air channel flow and the time of staying determine that the time of staying is set as the 5-10 seconds.