CN209188501U - The system of NOx in a kind of efficient removal pelletizing flue gas - Google Patents

Abstract

A system for efficiently removing NOx from pellet flue gas, the system includes a grate (1), and according to the process direction, the grate (1) is sequentially provided with a blast drying section (UDD) and a draft drying section (DDD), preheating stage one (TPH) and preheating stage two (PH); preheating stage two (PH) is provided with reductant injection device (2); The second pipeline (L2) drawn from the air outlet of the preheating section (TPH) and the third pipeline (L3) drawn from the air outlet of the bottom air box of the preheating section (TPH) are connected to the flue gas treatment via the fourth pipeline (L4) after being combined system. In this utility model, on the basis of setting the SNCR method deNOx device in the second preheating section of the grate machine, a flue gas treatment system is added to process the flue gas discharged from the draft drying section and the preheating section, and the deNOx effect is remarkable, which is truly realized. "Energy Conservation, Emission Reduction, and Ultra-Low _NOx Production".

Description

A system for efficiently removing NOx from pellet flue gas

technical field

The utility model relates to the production of grate machine-rotary kiln pellets with low NOx (nitrogen oxides), in particular to a system for efficiently removing NOx from pellet flue gas, and belongs to the technical field of engineering chain grate machine-rotary kiln pellets .

Background technique

Pellets are the main iron-containing charge for blast furnace ironmaking in my country. In 2015, the output of pellets in my country was 128 million tons. Compared with sinter, due to the low energy consumption and relatively friendly environment of the pellet production process, and the product has the advantages of good strength, high grade, and good metallurgical properties, it can increase production and save coke when applied to blast furnace smelting, and improve ironmaking technology and economy Indicators, reducing the cost of pig iron, and improving economic benefits, so pellets have been vigorously developed in my country in recent years.

my country's pellet production is dominated by the grate-rotary kiln process, and its output accounts for more than 60% of the total pellet production. In recent years, with the increasing complexity of iron ore raw materials and fuels, the increase in the proportion of hematite (leading to an increase in roasting temperature), the large-scale utilization of low-quality fuels, and the application of nitrogen-containing coke oven gas in gas-based rotary kilns have made it difficult to The concentration of NOx emissions in the pellet production process of a small number of enterprises is on the rise; coupled with the increasingly stringent environmental protection requirements in China, NOx emissions have been included in the emission assessment system. From 2015, the NOx (calculated as NO ₂ ) emission limit for pellet production is 300mg /m ³ , making these enterprises need to add denitrification facilities to meet the national emission standards. In June 2017, the Ministry of Environmental Protection of the People's Republic of China issued the revised announcement of the "Steel Sintering and Pelletizing Industry Air Pollutant Emission Standards", lowering the NOx (calculated as NO ₂ ) emission limit from 300mg/Nm ³ to 100mg/Nm ³ , sintering And the standard oxygen content of pellet roasting flue gas is 16%.

Although pelletizing companies have done a lot of work in environmental protection, dust removal and desulfurization have been effectively controlled to meet emission requirements, but the current NOx removal costs are high and the process is complicated. New challenges have been brought about, and some enterprises have had to reduce production in large quantities due to excessive NOx, and even face shutdown. Judging from the current production situation of most pellets, NOx emissions generally exceed the standard by 30-100 mg/m3. If the NOx production can be reduced from the source and the process, so as to meet the emission requirements, the terminal denitrification purification equipment can be omitted, and the chain The production of grate-rotary kiln pellets is of great significance, which is conducive to further improving the vitality and competitiveness of pelletizing enterprises.

The existing methods for removing nitrogen oxides in flue gas mainly include selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR). Among them, temperature plays a leading role in SNCR denitrification technology. It is generally believed that the temperature range of 800°C to 1100°C is more suitable. When the temperature is too high, _NH3 will oxidize to produce NO, which may cause the concentration of NO to increase, resulting in a decrease in the removal rate of NOx; when the temperature is too low, the _NH3 As the reaction rate decreases, the NOx removal rate will also decrease, and the escape amount of NH ₃ will also increase. Usually, the temperature range of the second stage of preheating is 850°C to 1000°C, which meets the conditions of the SNCR denitrification method, but optimization control is required to achieve the best emission reduction effect.

The selectivity of SCR denitrification technology means that under the action of the catalyst and the presence of oxygen, NH ₃ preferentially undergoes reduction and removal reaction with NOx to generate N ₂ and H ₂ O, and does not undergo oxidation reaction with oxygen in the flue gas.

The existing grate machine-rotary kiln pellet production process is shown in Figure 1. The grate machine is divided into a blast drying section, a draft drying section, a preheating section, and a preheating section. The annular cooler is divided into an annular cooling section, an annular The second stage of cooling and the third stage of ring cooling. Among them, the wind from the ring cooling stage directly enters the rotary kiln to roast the pellets, and then heats the preheated balls in the second stage of preheating, blows them into the air drying section to dry the raw pellets, and then discharges them outside through the air drying section ( The air from the second stage of the ring cooling enters the preheating stage to heat the preheating balls and then discharges outward; the wind from the third stage of the ring cooling enters the blast drying section to dry the green balls by blasting, thus realizing chain Closed circulation of grate-rotary kiln-circular cooler air flow system.

The publication number is CN 106268270 A, and the publication date is January 4, 2017. The patent document titled "a grate-rotary kiln denitrification system" discloses a grate-rotary kiln denitrification system. A denitrification device is added to the inner cavity of the second preheating section, and the injection direction of the nozzle is the same as the flow direction of the flue gas. Although this technology can reduce NOx emissions to a certain extent, the reduction range is limited, and the amount of reducing agent sprayed is difficult to control. Too much will cause NH ₃ to escape and pollute the environment. If it is too small, NOx emissions will still fail to meet the emission requirements.

In the existing technology, due to the lack of systematic research and reliable low NOx generation and control technology in the grate-rotary kiln pellet production process, the NOx emission in the production process of the pellet plant is not up to standard and has become the norm and one of the biggest challenges facing enterprises . For this reason, enterprises can only reduce the generation of NOx by reducing the production of pellets, reducing the amount of gas or pulverized coal injection, reducing the strength requirements of pellets, reducing the temperature of the rotary kiln, and using lower NOx raw materials and fuels. These methods not only affect the production of pellets in terms of output and quality, but also have high requirements on the quality of raw materials and fuels, resulting in increased costs, and cannot fundamentally solve the problem of low NOx production of pellets. In addition, adding a denitrification device after the main exhaust fan, such as the use of selective catalytic reduction technology (SCR) and selective non-catalytic reduction technology (SNCR), although it can meet the requirements of low NOx emissions, due to its high investment cost , High equipment requirements, high energy consumption, high denitrification cost and secondary pollution have not been popularized and applied in pelletizing enterprises. At present, the NOx control method of pelletizing plants at home and abroad is mainly realized through process control.

In order to meet the NOx emission requirements of the grate machine-rotary kiln pellet production process and respond to the country's call for energy conservation and emission reduction, it is necessary to design a more advanced air flow system starting from the process itself, and at the same time use the characteristics of the system itself to achieve low NOx pellets group production.

Utility model content

Aiming at the defects and deficiencies in the above-mentioned prior art, the utility model proposes a system for efficiently removing NOx from pellet flue gas by optimizing the process flow of the grate machine-rotary kiln system. The system is equipped with an SNCR deNOx device in the second preheating section of the grate to reduce the NOx content in the pellet flue gas. The gas is treated to further reduce the NOx content in the flue gas, so as to realize the ultra-low emission of NOx from the pellet flue gas, so as to solve the above-mentioned technical problems, and has the characteristics of "energy saving, emission reduction and ultra-low _NOx production".

According to the first embodiment of the utility model, a system for efficiently removing NOx in pellet flue gas is provided:

A system for efficiently removing NOx from pellet flue gas, the system includes a grate, and according to the process direction, the grate is sequentially provided with a blast drying section, an exhaust drying section, a preheating stage and a preheating stage two . The second preheating section is equipped with a reducing agent injection device. Wherein, the second pipe drawn from the air outlet of the bottom air box of the extraction and drying section and the third pipe drawn from the air outlet of the bottom air box of the preheating section are combined and connected to the flue gas treatment system through the fourth pipe.

The process direction refers to the direction of the materials in the grate machine, that is, the direction from one end of the material input to the end of the material output.

In the utility model, the system also includes a rotary kiln and an annular cooler. The annular cooler is sequentially provided with the first annular cooling section, the second annular cooling section and the third annular cooling section. The tail end of the rotary kiln is connected to the second stage of preheating of the grate and the other end is connected to the first stage of ring cooling of the ring cooler.

Wherein, the air outlet of the ring cooling section is connected to the front air inlet of the rotary kiln through the fifth pipeline. The air outlet of the ring cooling second stage is connected to the air inlet of the preheating first stage via the sixth pipe. The air outlet of the third ring cooling section is connected to the air inlet of the bottom air box of the blast drying section via the seventh pipeline and the first blower is provided on the seventh pipeline. The first pipeline drawn from the air outlet of the bottom air box of the preheating second section is connected to the air inlet on the top of the draft drying section and a first exhaust fan is arranged on the first pipeline. The eighth pipeline drawn from the air outlet on the top of the blast drying section is connected to the chimney and a second suction fan is provided on the eighth pipeline. The air outlet of the second blower is connected to the air inlet of the ring cooling section through the ninth pipeline. The air outlet of the third blower is connected to the air inlet of the second stage of the ring cooling through the tenth pipeline. The air outlet of the fourth blower is connected to the air inlet of the third ring cooling section via the eleventh pipeline.

The front end (or kiln head) of the rotary kiln is generally equipped with a blower to supply combustion-supporting air to the central burner of the rotary kiln.

In the utility model, the flue gas treatment system is an activated carbon adsorption system. The second pipe drawn from the air outlet of the bottom air box of the extraction and drying section and the third pipe drawn from the air outlet of the bottom air box of the preheating section are combined and connected to the flue gas inlet of the activated carbon adsorption system through the fourth pipe. Preferably, a third exhaust fan is provided on the fourth pipeline.

Preferably, the flue gas outlet of the activated carbon adsorption system is connected to the chimney via a flue gas discharge pipe.

In the present utility model, the reductant injection device includes a reductant storage tank, a pressure delivery pump, a mixing chamber connected in sequence, a gas distribution chamber in the second stage of preheating, and a reductant delivery pipe communicated with the gas distribution chamber , There is a nozzle on the reducing agent delivery pipe. Wherein, the outlet of the reductant storage tank is connected to the inlet of the mixing chamber through a delivery pipeline, the delivery pipeline is provided with a pressure delivery pump, and the mixing chamber is connected to the gas distribution chamber in the second preheating section through the pipeline.

Preferably, a compressed air pipeline is also connected to the gas distribution chamber. Preferably, a gas flow regulating valve is provided on the compressed air pipeline.

Generally, the reducing agent is mainly composed of ammonia agent (such as ammonia water, urea, etc.) and trace additives (such as NaCl, vanadium-containing solution, mesoporous/microporous nanomaterials, etc.).

Preferably, the reductant injection device further includes a liquid flow regulating valve arranged between the pressure delivery pump and the mixing chamber.

Preferably, the first pipeline is also provided with a first dust collector. Preferably, the first dust collector is a multi-tube dust collector.

Preferably, the first dust collector is located upstream of the first suction fan.

Preferably, a second dust collector is also provided on the fourth pipeline. Preferably, the second deduster is located upstream of the third suction fan.

According to the second embodiment of the present utility model, a system for efficiently removing NOx in pellet flue gas is provided:

A system for efficiently removing NOx from pellet flue gas, the system includes a grate, and according to the process direction, the grate is sequentially provided with a blast drying section, an exhaust drying section, a preheating stage and a preheating stage two . The second preheating section is equipped with a reducing agent injection device. Wherein, the second pipe drawn from the air outlet of the bottom air box of the extraction and drying section and the third pipe drawn from the air outlet of the bottom air box of the preheating section are combined and connected to the flue gas treatment system through the fourth pipe.

The process direction refers to the direction of the materials in the grate machine, that is, the direction from one end of the material input to the end of the material output.

In the utility model, the system also includes a rotary kiln and an annular cooler. The annular cooler is sequentially provided with the first annular cooling section, the second annular cooling section and the third annular cooling section. The tail end of the rotary kiln is connected to the second stage of preheating of the grate and the other end is connected to the first stage of ring cooling of the ring cooler.

Wherein, the air outlet of the ring cooling section is connected to the front air inlet of the rotary kiln through the fifth pipeline. The air outlet of the ring cooling second stage is connected to the air inlet of the preheating first stage via the sixth pipe. The air outlet of the third ring cooling section is connected to the air inlet of the bottom air box of the blast drying section via the seventh pipeline and the first blower is provided on the seventh pipeline. The first pipeline drawn from the air outlet of the bottom air box of the preheating second section is connected to the air inlet on the top of the draft drying section and a first exhaust fan is arranged on the first pipeline. The eighth pipeline drawn from the air outlet on the top of the blast drying section is connected to the chimney and a second suction fan is provided on the eighth pipeline. The air outlet of the second blower is connected to the air inlet of the ring cooling section through the ninth pipeline. The air outlet of the third blower is connected to the air inlet of the second stage of the ring cooling through the tenth pipeline. The air outlet of the fourth blower is connected to the air inlet of the third ring cooling section via the eleventh pipeline.

The front end (or kiln head) of the rotary kiln is generally equipped with a blower to supply combustion-supporting air to the central burner of the rotary kiln.

In the utility model, the flue gas treatment system is a desulfurization tower and an SCR system. The second pipeline drawn from the air outlet of the bottom wind box of the extraction and drying section and the third pipeline drawn from the air outlet of the bottom wind box of the preheating section are combined and connected to the flue gas inlet of the desulfurization tower through the fourth pipeline. The flue gas outlet of the desulfurization tower is connected to the flue gas inlet of the SCR system through the twelfth pipeline. Preferably, a third exhaust fan is provided on the fourth pipeline or the twelfth pipeline.

Preferably, the flue gas outlet of the SCR system is connected to the chimney via a flue gas discharge pipe.

In the present utility model, the reductant injection device includes a reductant storage tank, a pressure delivery pump, a mixing chamber connected in sequence, a gas distribution chamber in the second stage of preheating, and a reductant delivery pipe communicated with the gas distribution chamber , There is a nozzle on the reducing agent delivery pipe. Wherein, the outlet of the reductant storage tank is connected to the inlet of the mixing chamber through a delivery pipeline, the delivery pipeline is provided with a pressure delivery pump, and the mixing chamber is connected to the gas distribution chamber in the second preheating section through the pipeline.

Preferably, a compressed air pipeline is also connected to the gas distribution chamber. Preferably, a gas flow regulating valve is provided on the compressed air pipeline.

Preferably, the reductant injection device further includes a liquid flow regulating valve arranged between the pressure delivery pump and the mixing chamber.

Generally, the reducing agent is mainly composed of ammonia agent (such as ammonia water, urea, etc.) and trace additives (such as NaCl, vanadium-containing solution, mesoporous/microporous nanomaterials, etc.).

Preferably, the first pipeline is also provided with a first dust collector. Preferably, the first dust collector is a multi-tube dust collector.

Preferably, the first dust collector is located upstream of the first suction fan.

Preferably, a second dust collector is also provided on the fourth pipeline. Preferably, the second deduster is located upstream of the third suction fan.

In the utility model, the reducing agent injection device is a device for removing NOx by SNCR method, which is installed in the second stage of preheating of the chain grate. The temperature range of the second stage of preheating is generally 850°C to 1000°C, which is in line with the temperature conditions of the SNCR deNOx method. When there is a transition section between the second preheating section of the grate and the rotary kiln, the temperature range of the transition section is generally 950 ° C ~ 1100 ° C, and a reducing agent injection device can also be installed in the transition section to treat the smoke through the SNCR method. gas for deNOx treatment.

Generally, the content of NOx in the pellet flue gas from the tail of the rotary kiln is 400-700mg/m ³ (eg 500mg/m ³ ). In the first embodiment of the present utility model, when the flue gas flows through the second preheating section of the grate machine, the flue gas and the reducing gas sprayed in reverse from the reducing agent injection device arranged in the second preheating section Mixed, the NOx in the flue gas reacts quickly with the reducing gas at high temperature to generate N ₂ , and the NOx content in the flue gas is reduced to below 300mg/m ³ . After preheating the second-stage reaction, the flue gas enters the second dust collector together with the flue gas from the preheating stage after passing through the exhausting and drying section. After the flue gas is dedusted, it enters the activated carbon adsorption system and is discharged to the chimney. After activated carbon adsorption treatment, the emission concentrations of NOx and SOx in the flue gas are controlled at ultra-low levels, meeting the requirements of ultra-low emissions. In this way, the NOx emission of the whole pellet system can meet the requirement of ultra-low emission.

In the second embodiment of the present utility model, when the flue gas flows through the second preheating section of the grate machine, the flue gas and the reducing gas sprayed in reverse from the reducing agent injection device installed in the second preheating section Mixed, the NOx in the flue gas reacts rapidly with the reducing gas in a selective non-catalytic reduction reaction at high temperature to generate N ₂ , and the NOx content in the flue gas is reduced to below 300mg/m ³ . The flue gas after preheating the second-stage reaction passes through the exhausting and drying section and enters the second dust collector together with the flue gas from the preheating stage. After dust removal, the flue gas enters the desulfurization tower, and the desulfurized flue gas enters the SCR system. Selective catalytic reduction reaction is carried out in the system, the content of NOx in the flue gas is further reduced to below 30mg/ ^m3 , and the oxygen concentration in the flue gas is controlled at 16-20% (preferably 17-19%, such as 18%), according to The benchmark oxygen concentration is converted to 16%, meeting the requirements of ultra-low emissions. In this way, the NOx emission of the whole pellet system can meet the requirement of ultra-low emission.

In the utility model, the flue gas mainly reacts as follows in the second stage of preheating of the grate machine:

4NO+4NH ₃ +O ₂ →4N ₂ +6H ₂ O

6NO+4NH ₃ →5N ₂ +6H ₂ O

2NO ₂ +4NH ₃ +O ₂ →3N ₂ +6H ₂ O

6NO ₂ +8NH ₃ →7N ₂ +12H ₂ O;

The flue gas mainly undergoes the following reactions in the activated carbon adsorption system:

4NO+O ₂ +4NH ₃ →4N ₂ +6H ₂ O

2SO ₂ +O ₂ +2H ₂ O→2H ₂ SO ₄

NH ₃ +H ₂ SO ₄ →NH ₄ HSO ₄ ;

The flue gas mainly undergoes the following reactions in the SCR system:

NO+NO ₂ +2NH ₃ →2N ₂ +3H ₂ O

4NO+4NH ₃ +O ₂ →4N ₂ +6H ₂ O

4NH ₃ +2NO+2O ₂ →3N ₂ +6H ₂ O;

Through the above reaction, the NO _x (including NO, NO ₂ ) in the flue gas can be converted into N ₂ , effectively reducing the emission of NO _x in the flue gas. In addition, the unreacted reducing agent in the second stage of preheating can also enter the subsequent activated carbon adsorption system or SCR system through the pipeline together with the flue gas to continue to participate in the reaction, while ensuring a high removal rate of NO _x , as much as possible Reduced escape of NH ₃ .

The reductant injection device in the utility model includes a reductant storage tank, a pressure delivery pump, a mixing chamber, a gas distribution chamber, a reductant delivery pipe, and a nozzle. The reductant stored in the reductant storage tank is pumped by the pressure delivery pump. It is sent to the mixing chamber to be mixed with the diluent input therein, and then directly sent to the gas distribution chamber located in the second preheating section, and then the reducing agent mixture enters each reducing agent delivery pipe and passes through the The nozzles are injected into the second preheating stage, and the reducing agent reacts with nitrogen oxides (NO _x ) contained in the hot exhaust gas flowing through the second preheating stage to produce nitrogen.

In this application, the diluent may be a liquid or gaseous diluent, such as water or air or nitrogen.

Typically, compressed air is introduced into the gas distribution chamber via compressed air lines.

The reductant injection device in the utility model also includes a liquid flow regulating valve arranged between the pressure delivery pump and the mixing chamber. The setting of the liquid flow regulating valve is conducive to real-time adjustment of the liquid flow of the reducing agent according to production needs. A gas flow regulating valve is also provided on the compressed air pipeline, and the setting of the gas flow regulating valve is conducive to real-time regulation of the gas flow of the compressed air passing into the gas distribution chamber according to production needs.

In the present application, the "upstream" or "downstream" is a concept relative to the direction of flue gas in the pipeline.

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

1. This utility model combines the SNCR method denitrification technology, and adds an SNCR method deNOx device in the second stage of preheating of the grate machine. On the one hand, it can process the NOx in the recycled flue gas, and at the same time, it can process the NOx produced in the production process. , indeed effectively reduce the emission concentration of NOx in the flue gas;

2. On the basis of setting the SNCR method deNOx device in the second preheating section of the grate machine, the utility model adds a flue gas treatment system to process the flue gas discharged from the draft drying section and the preheating section. The flue gas treatment system can be Activated carbon adsorption system, which can also be a combination of desulfurization tower and SCR system, further reduces the emission concentration of NOx in flue gas;

3. The utility model starts from the technological process and the decomposition mechanism of _NOx to reduce the discharge of _NOx in the grate machine-rotary kiln pellet production process. The process is simple, the cost of _NOx removal is low, and the effect of NOx removal is remarkable. The technical problem of excessive NO _x emissions in enterprises has truly realized "energy saving, emission reduction and ultra-low NO _x production".

Description of drawings

Fig. 1 is prior art grate machine-rotary kiln pellet production process sketch;

Fig. 2 is a structural schematic diagram of a system for efficiently removing NOx in pellet flue gas of the present invention;

Fig. 3 is the structure schematic diagram of another system of efficient removal of NOx in pellet flue gas of the present utility model;

Fig. 4 is a structural schematic diagram of the reducing agent injection device of the present invention.

Reference signs: 1: chain grate; UDD: blast drying section; DDD: draft drying section; TPH: preheating section 1; PH: preheating section 2; Kiln: rotary kiln; C: ring cooler; C1: ring Cooling stage one; C2: Ring cooling second stage; C3: Ring cooling third stage; 2: Reductant injection device; 201: Reductant storage tank; 202: Pressure delivery pump; 203: Mixing chamber; 204: Gas distribution chamber; 205 : reducing agent delivery pipe; 206: nozzle; 207: gas flow regulating valve; 208: liquid flow regulating valve; 3: first exhaust fan; 4: first blower; 5: chimney; 6: second exhaust fan; 7: Second blower; 8: Third blower; 9: Fourth blower; 10: Activated carbon adsorption system; 11: Third exhaust fan; 12: Desulfurization tower; 13: SCR system; 14: First dust collector; 15: Second dust collector;

L1: first pipeline; L2: second pipeline; L3: third pipeline; L4: fourth pipeline; L5: fifth pipeline; L6: sixth pipeline; L7: seventh pipeline; L8: eighth pipeline; L9: Ninth pipeline; L10: Tenth pipeline; L11: Eleventh pipeline; L12: Twelfth pipeline; L13: Compressed air pipeline; L14: Smoke discharge pipeline.

Detailed ways

According to the first embodiment of the utility model, a system for efficiently removing NOx in pellet flue gas is provided:

A system for efficiently removing NOx from pellet flue gas. The system includes a grate 1. According to the process trend, the grate 1 is sequentially provided with a blast drying section UDD, a draft drying section DDD, and a preheating section TPH And preheat the second stage PH. A reductant injection device 2 is provided on the preheating second stage PH. Among them, the second pipeline L2 drawn from the air outlet of the bottom wind box of the extraction and drying section DDD and the third pipeline L3 drawn from the air outlet of the bottom wind box of the preheating section TPH are connected to the flue gas through the fourth pipeline L4 after being combined. Air treatment system.

In the utility model, the system also includes a rotary kiln Kiln and an annular cooler C. The annular cooler C is sequentially provided with the first stage of annular cooling C1, the second stage of annular cooling C2 and the third stage of annular cooling C3. The tail end of the rotary kiln Kiln is connected to the preheating second stage PH of the grate 1 and the other end is connected to the annular cooling first stage C1 of the annular cooler C.

Wherein, the air outlet of the ring cooling section C1 is connected to the front air inlet of the rotary kiln Kiln via the fifth pipeline L5. The air outlet of the second ring cooling section C2 is connected to the air inlet of the preheating section TPH via the sixth pipeline L6. The air outlet of the third ring cooling section C3 is connected to the air inlet of the bottom air box of the blast drying section UDD via the seventh pipeline L7 and the first blower 4 is provided on the seventh pipeline L7. The first pipeline L1 drawn from the air outlet of the bottom air box of the preheating stage 2 PH is connected to the air inlet at the top of the draft drying section DDD and the first exhaust fan 3 is provided on the first pipeline L1. The eighth pipeline L8 drawn from the air outlet at the top of the blast drying section UDD is connected to the chimney 5 and the second suction fan 6 is provided on the eighth pipeline L8. The air outlet of the second blower 7 is connected to the air inlet of the ring cooling section C1 via the ninth pipeline L9. The air outlet of the third blower 8 is connected to the air inlet of the second ring cooling section C2 via the tenth pipeline L10. The air outlet of the fourth blower 9 is connected to the air inlet of the third ring cooling section C3 via the eleventh pipeline L11.

In the present utility model, the flue gas treatment system is an activated carbon adsorption system 10 . The second pipeline L2 drawn from the air outlet of the bottom wind box of the suction drying section DDD and the third pipeline L3 drawn from the air outlet of the bottom wind box of the preheating section TPH are connected to the activated carbon adsorption system via the fourth pipeline L4 after being combined 10's flue gas inlet. Preferably, a third exhaust fan 11 is provided on the fourth pipeline L4.

Preferably, the flue gas outlet of the activated carbon adsorption system 10 is connected to the chimney 5 via the flue gas discharge pipe L14.

In the present utility model, the reductant injection device 2 includes a reductant storage tank 201, a pressure delivery pump 202, a mixing chamber 203, a gas distribution chamber 204 in the preheating second stage PH, and a gas distribution chamber connected in sequence. 204 communicates with a reducing agent delivery pipe 205 , and a nozzle 206 is provided on the reducing agent delivery pipe 205 . Wherein, the outlet of the reducing agent storage tank 201 is connected to the inlet of the mixing chamber 203 through a delivery pipeline, and the delivery pipeline is provided with a pressure delivery pump 202, and the mixing chamber 203 is connected to the gas distribution chamber 204 located in the second stage of preheating PH via a pipeline.

Preferably, a compressed air pipeline L13 is also connected to the gas distribution chamber 204 . Preferably, a gas flow regulating valve 207 is provided on the compressed air pipeline L13.

Preferably, the reductant injection device 2 further includes a liquid flow regulating valve 208 disposed between the pressure delivery pump 202 and the mixing chamber 203 .

Preferably, a first dust collector 14 is also provided on the first pipeline L1. Preferably, the first dust collector 14 is a multi-tube dust collector.

Preferably, the first dust collector 14 is located upstream of the first exhaust fan 3 .

Preferably, a second dust collector 15 is also provided on the fourth pipeline L4. Preferably, the second dust remover 15 is located upstream of the third suction fan 11 .

According to the second embodiment of the present utility model, a system for efficiently removing NOx in pellet flue gas is provided:

A system for efficiently removing NOx from pellet flue gas. The system includes a grate 1. According to the process trend, the grate 1 is sequentially provided with a blast drying section UDD, a draft drying section DDD, and a preheating section TPH And preheat the second stage PH. A reductant injection device 2 is provided on the preheating second stage PH. Among them, the second pipeline L2 drawn from the air outlet of the bottom wind box of the extraction and drying section DDD and the third pipeline L3 drawn from the air outlet of the bottom wind box of the preheating section TPH are connected to the flue gas through the fourth pipeline L4 after being combined. Air treatment system.

In the utility model, the system also includes a rotary kiln Kiln and an annular cooler C. The annular cooler C is sequentially provided with the first stage of annular cooling C1, the second stage of annular cooling C2 and the third stage of annular cooling C3. The tail end of the rotary kiln Kiln is connected to the preheating second stage PH of the grate 1 and the other end is connected to the annular cooling first stage C1 of the annular cooler C.

Wherein, the air outlet of the ring cooling section C1 is connected to the front air inlet of the rotary kiln Kiln via the fifth pipeline L5. The air outlet of the second ring cooling section C2 is connected to the air inlet of the preheating section TPH via the sixth pipeline L6. The air outlet of the third ring cooling section C3 is connected to the air inlet of the bottom air box of the blast drying section UDD via the seventh pipeline L7 and the first blower 4 is provided on the seventh pipeline L7. The first pipeline L1 drawn from the air outlet of the bottom air box of the preheating stage 2 PH is connected to the air inlet at the top of the draft drying section DDD and the first exhaust fan 3 is provided on the first pipeline L1. The eighth pipeline L8 drawn from the air outlet at the top of the blast drying section UDD is connected to the chimney 5 and the second suction fan 6 is provided on the eighth pipeline L8. The air outlet of the second blower 7 is connected to the air inlet of the ring cooling section C1 via the ninth pipeline L9. The air outlet of the third blower 8 is connected to the air inlet of the second ring cooling section C2 via the tenth pipeline L10. The air outlet of the fourth blower 9 is connected to the air inlet of the third ring cooling section C3 via the eleventh pipeline L11.

In the present utility model, the flue gas treatment system is a desulfurization tower 12 and an SCR system 13 . The second pipeline L2 drawn from the air outlet of the bottom wind box of the extraction and drying section DDD and the third pipeline L3 drawn from the air outlet of the bottom wind box of the preheating section TPH are connected to the desulfurization tower 12 via the fourth pipeline L4 after being combined smoke inlet. The flue gas outlet of the desulfurization tower 12 is connected to the flue gas inlet of the SCR system 13 via a twelfth pipeline L12. Preferably, a third exhaust fan 11 is provided on the fourth pipeline L4 or the twelfth pipeline L12.

Preferably, the flue gas outlet of the SCR system 13 is connected to the chimney 5 via the flue gas discharge pipe L14.

In the present utility model, the reductant injection device 2 includes a reductant storage tank 201, a pressure delivery pump 202, a mixing chamber 203, a gas distribution chamber 204 in the preheating second stage PH, and a gas distribution chamber connected in sequence. 204 communicates with a reducing agent delivery pipe 205 , and a nozzle 206 is provided on the reducing agent delivery pipe 205 . Wherein, the outlet of the reducing agent storage tank 201 is connected to the inlet of the mixing chamber 203 through a delivery pipeline, and the delivery pipeline is provided with a pressure delivery pump 202, and the mixing chamber 203 is connected to the gas distribution chamber 204 located in the second stage of preheating PH via a pipeline.

Preferably, a compressed air pipeline L13 is also connected to the gas distribution chamber 204 . Preferably, a gas flow regulating valve 207 is provided on the compressed air pipeline L13.

Preferably, the reductant injection device 2 further includes a liquid flow regulating valve 208 disposed between the pressure delivery pump 202 and the mixing chamber 203 .

Preferably, a first dust collector 14 is also provided on the first pipeline L1. Preferably, the first dust collector 14 is a multi-tube dust collector.

Preferably, the first dust collector 14 is located upstream of the first exhaust fan 3 .

Preferably, a second dust collector 15 is also provided on the fourth pipeline L4. Preferably, the second dust remover 15 is located upstream of the third suction fan 11 .

Example 1

As shown in Figure 2, a system for efficiently removing NOx from pellet flue gas, the system includes a grate machine 1, and according to the process trend, the grate machine 1 is successively provided with a blast drying section UDD and a draft drying section DDD, preheating one-stage TPH and preheating two-stage PH. A reductant injection device 2 is provided on the preheating second stage PH. Among them, the second pipeline L2 drawn from the air outlet of the bottom wind box of the extraction and drying section DDD and the third pipeline L3 drawn from the air outlet of the bottom wind box of the preheating section TPH are connected to the flue gas through the fourth pipeline L4 after being combined. Air treatment system.

The system also includes rotary kiln Kiln and ring cooler C. The annular cooler C is sequentially provided with the first stage of annular cooling C1, the second stage of annular cooling C2 and the third stage of annular cooling C3. The tail end of the rotary kiln Kiln is connected to the preheating second stage PH of the grate 1 and the other end is connected to the annular cooling first stage C1 of the annular cooler C. Wherein, the air outlet of the ring cooling section C1 is connected to the front air inlet of the rotary kiln Kiln via the fifth pipeline L5. The air outlet of the second ring cooling section C2 is connected to the air inlet of the preheating section TPH via the sixth pipeline L6. The air outlet of the third ring cooling section C3 is connected to the air inlet of the bottom air box of the blast drying section UDD via the seventh pipeline L7 and the first blower 4 is provided on the seventh pipeline L7. The first pipeline L1 drawn from the air outlet of the bottom air box of the preheating stage 2 PH is connected to the air inlet at the top of the draft drying section DDD and a first exhaust fan 3 is provided on the first pipeline L1. The eighth pipeline L8 drawn from the air outlet at the top of the blast drying section UDD is connected to the chimney 5 and the second suction fan 6 is provided on the eighth pipeline L8. The air outlet of the second blower 7 is connected to the air inlet of the ring cooling section C1 via the ninth pipeline L9. The air outlet of the third blower 8 is connected to the air inlet of the second ring cooling section C2 via the tenth pipeline L10. The air outlet of the fourth blower 9 is connected to the air inlet of the third ring cooling section C3 via the eleventh pipeline L11.

The flue gas treatment system is an activated carbon adsorption system 10 . The second pipeline L2 drawn from the air outlet of the bottom wind box of the suction drying section DDD and the third pipeline L3 drawn from the air outlet of the bottom wind box of the preheating section TPH are both connected to the activated carbon adsorption system via the fourth pipeline L4 after being combined 10's flue gas inlet. A third exhaust fan 11 is provided on the fourth pipeline L4. The flue gas outlet of the activated carbon adsorption system 10 is connected to the chimney 5 via the flue gas discharge pipe L14.

As shown in Figure 4, the reductant injection device 2 includes a reductant storage tank 201, a pressure delivery pump 202, a mixing chamber 203, a gas distribution chamber 204 in the preheating second stage PH, and a gas distribution chamber connected in sequence. 204 communicates with a reducing agent delivery pipe 205 , and a nozzle 206 is provided on the reducing agent delivery pipe 205 . Wherein, the outlet of the reducing agent storage tank 201 is connected to the inlet of the mixing chamber 203 through a delivery pipeline, and the delivery pipeline is provided with a pressure delivery pump 202, and the mixing chamber 203 is connected to the gas distribution chamber 204 located in the second stage of preheating PH via a pipeline. A compressed air pipeline L13 is also connected to the gas distribution chamber 204 . A gas flow regulating valve 207 is provided on the compressed air pipeline L13. The reductant injection device 2 further includes a liquid flow regulating valve 208 disposed between the pressure delivery pump 202 and the mixing chamber 203 .

A first dust collector 14 is also provided on the first pipeline L1. The first dust collector 14 is located upstream of the first suction fan 3 . The first dust collector 14 is a multi-tube dust collector.

Example 2

Embodiment 1 is repeated, except that a second dust collector 15 is also provided on the fourth pipeline L4. The second dust collector 15 is located upstream of the third suction fan 11 .

Example 3

As shown in FIG. 3 , Example 2 is repeated, except that the flue gas treatment system is a desulfurization tower 12 and an SCR system 13 . The second pipeline L2 drawn from the air outlet of the bottom wind box of the extraction and drying section DDD and the third pipeline L3 drawn from the air outlet of the bottom wind box of the preheating section TPH are connected to the desulfurization tower 12 via the fourth pipeline L4 after being combined smoke inlet. The flue gas outlet of the desulfurization tower 12 is connected to the flue gas inlet of the SCR system 13 via a twelfth pipeline L12. A third exhaust fan 11 is provided on the fourth pipeline L4. The flue gas outlet of the SCR system 13 is connected to the chimney 5 via the flue gas discharge pipe L14.

Use the system of Example 2 to treat the pellet flue gas, wherein the content of NOx in the flue gas from the tail of the rotary kiln Kiln is 500 mg/m ³ (that is, in the opposite direction to the direction of the flue gas) injecting reducing gas, the reducing gas is mixed with the hot flue gas flowing through the preheating second stage PH, to realize the selective non-catalytic reduction of NOx in the flue gas, and the NOx in the flue gas The content is reduced to below 300mg/m ³ . The flue gas after the preheating stage 2 PH reaction passes through the exhausting and drying stage DDD and enters the second dust collector 15 together with the flue gas from the preheating stage TPH. After activated carbon adsorption treatment, the emission concentrations of NOx and SOx in the flue gas are controlled at ultra-low levels, meeting the requirements of ultra-low emissions.

Use the system of Example 3 to treat pellet flue gas, wherein the content of NOx in the flue gas from the tail of the rotary kiln Kiln is 500 mg/m ³ (that is, in the opposite direction to the direction of the flue gas) injecting reducing gas, the reducing gas is mixed with the hot flue gas flowing through the preheating second stage PH, to realize the selective non-catalytic reduction of NOx in the flue gas, and the NOx in the flue gas The content is reduced to below 300mg/m ³ . The flue gas after the preheating stage 2 PH reaction passes through the exhausting and drying stage DDD and enters the second dust collector 15 together with the flue gas of the preheating stage TPH, and the flue gas enters the desulfurization tower 12 after dedusting, and the desulfurized flue gas enters the SCR system 13. The flue gas undergoes selective catalytic reduction reaction in the SCR system 13, the NOx content in the flue gas is further reduced to below 30mg/ ^m3 , and the oxygen concentration in the flue gas is controlled at about 18%, according to the standard oxygen concentration of 16%. Converted, in line with the requirements of ultra-low emissions.

It can be seen that, compared with the existing denitrification technology and equipment, the system of embodiment 2 or embodiment 3 has simple process, remarkable denitrification effect, avoids the pollution of flue gas to the environment, and truly realizes "energy saving, emission reduction and Ultra-Low NOx Production".

Claims (32)

1. the system of NOx in a kind of efficient removal pelletizing flue gas, the system include drying grate (1), moved towards according to technique, the chain Comb machine (1) is successively arranged two sections blasting drying period (UDD), down-draft drying zone (DDD), preheated one-section (TPH) and preheating (PH)；In advance Two sections of heat (PH) is equipped with reducing agent jetting device (2)；Wherein, draw from the air outlet of the bottom bellows of down-draft drying zone (DDD) Both third pipelines (L3) that the air outlet of second pipe (L2) out and the bottom bellows from preheated one-section (TPH) is drawn are closing And smoke processing system is connected to via the 4th pipeline (L4) later.

2. system according to claim 1, it is characterised in that: the system further includes rotary kiln (Kiln) and ring cold machine (C)； Ring cold machine (C) is successively arranged cold two sections of tri- sections of (C2) He Huanleng (C3) of ring cold one section (C1), ring；The tail end of rotary kiln (Kiln) connects Two sections of preheating (PH) rings that ring cold machine (C) is connected with the other end for connecing drying grate (1) are cold one section (C1)；

Wherein, the air outlet of ring cold one section (C1) is connected to the front end air inlet of rotary kiln (Kiln) via the 5th pipeline (L5)； The air outlet of ring cold two sections (C2) is connected to the air inlet of preheated one-section (TPH) via the 6th pipeline (L6)；Ring is cold three sections (C3) Air outlet via the 7th pipeline (L7) be connected to blasting drying period (UDD) bottom bellows air inlet and in the 7th pipeline (L7) the first air blower (4) are equipped with；The first pipe (L1) drawn from the air outlet of the bottom bellows of preheating two sections (PH) is even It is connected to the air inlet at the top of down-draft drying zone (DDD) and is equipped with the first exhaust fan (3) on first pipe (L1)；From air blast The 8th pipeline (L8) that the air outlet at the top of dryer section (UDD) is drawn is connected to chimney (5) and on the 8th pipeline (L8) Equipped with the second exhaust fan (6)；The air outlet of second air blower (7) via the 9th pipeline (L9) be connected to ring cold one section (C1) into Air port；The air outlet of third air blower (8) is connected to the air inlet of ring cold two sections (C2) via the tenth pipeline (L10)；4th drum The air outlet of blower (9) is connected to the air inlet of ring cold three sections (C3) via the 11st pipeline (L11).

3. system according to claim 1 or 2, it is characterised in that: the smoke processing system is activated carbon adsorption system (10)；The second pipe (L2) drawn from the air outlet of the bottom bellows of down-draft drying zone (DDD) and from preheated one-section (TPH) Both third pipelines (L3) that the air outlet of bottom bellows is drawn are connected to active carbon via the 4th pipeline (L4) after consolidation The smoke inlet of adsorption system (10).

4. system according to claim 1 or 2, it is characterised in that: the 4th pipeline (L4) is equipped with third exhaust fan (11).

5. system according to claim 3, it is characterised in that: the 4th pipeline (L4) is equipped with third exhaust fan (11).

6. system according to claim 3, it is characterised in that: the exhanst gas outlet of activated carbon adsorption system (10) is via flue gas Discharge tube (L14) is connected to chimney (5).

7. system according to claim 4, it is characterised in that: the exhanst gas outlet of activated carbon adsorption system (10) is via flue gas Discharge tube (L14) is connected to chimney (5).

8. system according to claim 5, it is characterised in that: the exhanst gas outlet of activated carbon adsorption system (10) is via flue gas Discharge tube (L14) is connected to chimney (5).

9. system according to claim 1 or 2, it is characterised in that: the smoke processing system is desulfurizing tower (12) and SCR System (13)；The second pipe (L2) drawn from the air outlet of the bottom bellows of down-draft drying zone (DDD) and from preheated one-section (TPH) both third pipelines (L3) that the air outlet of bottom bellows is drawn are connected to via the 4th pipeline (L4) after consolidation The smoke inlet of desulfurizing tower (12)；The exhanst gas outlet of desulfurizing tower (12) is connected to SCR system (13) via the 12nd pipeline (L12) Smoke inlet.

10. system according to claim 9, it is characterised in that: the 4th pipeline (L4) or the 12nd pipeline (L12) are equipped with Third exhaust fan (11).

11. system according to claim 9, it is characterised in that: the exhanst gas outlet of SCR system (13) is via smoke discharge pipe Road (L14) is connected to chimney (5).

12. system according to claim 10, it is characterised in that: the exhanst gas outlet of SCR system (13) is via flue gas emission Pipeline (L14) is connected to chimney (5).

13. according to claim 1,2, system described in any one of 5-8,10-12, it is characterised in that: the reducing agent sprays into Device (2) includes sequentially connected reducing agent holding vessel (201), pressure feed pump (202), mixing chamber (203) and is in preheating Gas distributing chamber (204) in two sections (PH) and the reducing agent delivery pipe (205) being connected to gas distributing chamber (204), reducing agent Delivery pipe (205) is equipped with nozzle (206)；Wherein, the outlet of reducing agent holding vessel (201) is connected to mixing by conveyance conduit The import of room (203), conveyance conduit are equipped with pressure feed pump (202), and mixing chamber (203) is connected to via pipeline is located at preheating Gas distributing chamber (204) in two sections (PH).

14. system according to claim 3, it is characterised in that: the reducing agent jetting device (2) includes sequentially connected Reducing agent holding vessel (201), pressure feed pump (202), mixing chamber (203) and the gas distributing chamber in two sections of preheating (PH) (204) and with gas distributing chamber (204) the reducing agent delivery pipe (205) being connected to, reducing agent delivery pipe (205) are equipped with nozzle (206)；Wherein, the outlet of reducing agent holding vessel (201) is connected to the import of mixing chamber (203), delivery pipe by conveyance conduit Road is equipped with pressure feed pump (202), and mixing chamber (203) is connected to the gas being located in two sections of preheating (PH) via pipeline and distributes Room (204).

15. system according to claim 4, it is characterised in that: the reducing agent jetting device (2) includes sequentially connected Reducing agent holding vessel (201), pressure feed pump (202), mixing chamber (203) and the gas distributing chamber in two sections of preheating (PH) (204) and with gas distributing chamber (204) the reducing agent delivery pipe (205) being connected to, reducing agent delivery pipe (205) are equipped with nozzle (206)；Wherein, the outlet of reducing agent holding vessel (201) is connected to the import of mixing chamber (203), delivery pipe by conveyance conduit Road is equipped with pressure feed pump (202), and mixing chamber (203) is connected to the gas being located in two sections of preheating (PH) via pipeline and distributes Room (204).

16. system according to claim 9, it is characterised in that: the reducing agent jetting device (2) includes sequentially connected Reducing agent holding vessel (201), pressure feed pump (202), mixing chamber (203) and the gas distributing chamber in two sections of preheating (PH) (204) and with gas distributing chamber (204) the reducing agent delivery pipe (205) being connected to, reducing agent delivery pipe (205) are equipped with nozzle (206)；Wherein, the outlet of reducing agent holding vessel (201) is connected to the import of mixing chamber (203), delivery pipe by conveyance conduit Road is equipped with pressure feed pump (202), and mixing chamber (203) is connected to the gas being located in two sections of preheating (PH) via pipeline and distributes Room (204).

17. system according to claim 13, it is characterised in that: gas distributing chamber is also connected with compressed air on (204) Pipeline (L13).

18. system described in any one of 4-16 according to claim 1, it is characterised in that: gas distributing chamber is also connected on (204) There is compressed air pipe (L13).

19. system according to claim 17, it is characterised in that: compressed air pipe (L13) is equipped with gas flow tune It saves valve (207).

20. system according to claim 18, it is characterised in that: compressed air pipe (L13) is equipped with gas flow tune It saves valve (207).

21. system according to claim 13, it is characterised in that: the reducing agent jetting device (2) further includes that setting exists Liquid flow regulating valve (208) between pressure feed pump (202) and mixing chamber (203).

22. system according to claim 17, it is characterised in that: the reducing agent jetting device (2) further includes that setting exists Liquid flow regulating valve (208) between pressure feed pump (202) and mixing chamber (203).

23. the system according to any one of claim 2,5-8,10-12,14-17,19-22, it is characterised in that: first The first deduster (14) are additionally provided on pipeline (L1).

24. system according to claim 3, it is characterised in that: be additionally provided with the first deduster (14) in first pipe (L1).

25. system according to claim 4, it is characterised in that: be additionally provided with the first deduster (14) in first pipe (L1).

26. system according to claim 23, it is characterised in that: the first deduster (14) is multi-tube dust cleaner.

27. the system according to claim 24 or 25, it is characterised in that: the first deduster (14) is multi-tube dust cleaner.

28. system according to claim 23, it is characterised in that: the first deduster (14) is located at the first exhaust fan (3) Upstream.

29. the system according to any one of claim 24-26, it is characterised in that: the first deduster (14) is located at first The upstream of exhaust fan (3).

30. system according to claim 3, it is characterised in that: be additionally provided with the second deduster (15) on the 4th pipeline (L4).

31. system according to claim 9, it is characterised in that: be additionally provided with the second deduster (15) on the 4th pipeline (L4).

32. the system according to claim 30 or 31, it is characterised in that: the second deduster (15) is located at third exhaust fan (11) upstream.