Ammonia fuel low-nitrogen combustion equipment

Abstract

The invention belongs to the related technical field of ammonia combustion, and discloses ammonia fuel low-nitrogen combustion equipment which comprises a combustion and flue gas purification system and a nitrogen oxide recombustion system, and the combustion and flue gas purification system comprises a combustor, a combustion chamber, a first induced draft fan and a nitrogen oxide separation system which are sequentially connected; the combustor is provided with a fuel inlet and an air inlet, and the air inlet is connected to the heater. The combustor is provided with a swirler; the combustion chamber is further provided with an igniter and a combustion chamber smoke outlet, and the combustion chamber smoke outlet is connected to the first induced draft fan. The nitrogen oxide re-combustion system comprises a second induced draft fan and a bypass valve which are connected in sequence; a purified flue gas outlet and a concentrated nitrogen oxide gas outlet are respectively formed in one end, far away from the first induced draft fan, of the nitrogen oxide separation system; the concentrated nitrogen oxide gas outlet is connected with the second induced draft fan; the bypass valve is connected to the inlet of the heater. According to the invention, low-nitrogen combustion of ammonia fuel is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field related to ammonia combustion, and more specifically, relates to an ammonia fuel low-nitrogen combustion device. Background Art

[0002] Ammonia is a renewable carbon-neutral fuel that has received extensive attention in the energy field in recent years because of its artificial synthesis, high energy density, and easy storage and transportation. In the future, ammonia will play an important role in the industrial field as an alternative to fossil fuels. However, ammonia fuel is very likely to produce nitrogen oxides (NOx) during combustion, causing environmental pollution. Therefore, the development of efficient low-nitrogen combustion technology for ammonia fuel is of great significance to promoting the application of ammonia fuel.

[0003] Ammonia burns very slowly, and it is difficult to organize its combustion, especially when pure ammonia is not intervened by specific technologies. It is particularly difficult to achieve stable combustion in the air. In addition, achieving low-nitrogen combustion of ammonia also faces technical challenges. Traditional low-nitrogen combustion methods are mainly aimed at hydrocarbon fuels such as coal and natural gas, covering nitrogen oxide control technology during combustion and nitrogen oxide control technology after combustion. The former mostly reduces the local high-temperature area in the combustion area by reducing the flame temperature and reducing the oxygen content, thereby suppressing the formation of thermal NOx; the latter widely uses selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) methods, through the reaction of reducing agents (usually ammonia or urea) with nitrogen oxides in the flue gas to generate N2 and water, thereby achieving the effect of removing nitrogen oxides. However, when examining the combustion process of ammonia as a fuel, the situation is completely different. The nitrogen oxides produced by ammonia combustion are mainly fuel-type NOx, and their generation mechanism is completely different from that of thermal NOx. The nitrogen oxide control technology in traditional combustion cannot achieve the control of fuel-type NOx; secondly, the NOx concentration released by ammonia combustion is often several times or even dozens of times higher than that of coal or natural gas combustion. This high concentration level far exceeds the treatment threshold of post-treatment technologies such as SCR and SNCR, resulting in these traditional methods being greatly reduced in effectiveness or even completely ineffective in treating nitrogen oxides emitted from ammonia combustion.

[0004] In view of this, in order to meet the needs of stable combustion and low-nitrogen combustion of ammonia, it is urgent to innovate and develop more efficient and suitable low-nitrogen combustion methods to ensure that ammonia fuel can be smoothly and environmentally friendly promoted and applied, thereby promoting the transformation of energy structure and promoting green development. Summary of the invention

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides an ammonia fuel low-nitrogen combustion device, which aims to solve the problem of high NOx concentration released by existing ammonia combustion.

[0006] To achieve the above-mentioned purpose, according to one aspect of the present invention, an ammonia fuel low-nitrogen combustion device is provided, the combustion device includes a combustion and flue gas purification system and a nitrogen oxide re-combustion system, the combustion and flue gas purification system includes a burner, a combustion chamber, a first induced draft fan and a nitrogen oxide separation system connected in sequence; the burner is respectively provided with a fuel inlet and an air inlet, and the air inlet is connected to a heater; the burner is arranged in the combustion chamber at the end opposite to the end where the fuel inlet is located, and a swirler is correspondingly arranged; an igniter is also arranged on the end of the combustion chamber adjacent to the burner, and a combustion chamber flue gas outlet is arranged on the other end, and the combustion chamber flue gas outlet is connected to the first induced draft fan; the nitrogen oxide re-combustion system includes a second induced draft fan and a bypass valve connected in sequence; the nitrogen oxide separation system is respectively provided with a purified flue gas outlet and a concentrated nitrogen oxide gas outlet at the end away from the first induced draft fan, and the concentrated nitrogen oxide outlet is connected to the second induced draft fan; the bypass valve is connected to the inlet of the heater.

[0007] Furthermore, the nitrogen oxide separation system is one of a low-temperature NOx adsorption-desorption system, a zeolite wheel adsorption-desorption system, and a membrane separation system.

[0008] Furthermore, the low-temperature NOx adsorption-desorption system includes a NOx adsorption system and a NOx desorption system, the NOx adsorption system includes a cold dryer, a third induced draft fan, a flue gas cooling system, and an adsorption tower which are connected in sequence; the cold dryer is connected to the first induced draft fan and the inlet of the flue gas cooling system; an adsorption tower flue gas inlet is provided on one side of the adsorption tower, and two saturated adsorbent outlets are respectively provided on the other side; the purified flue gas outlet is provided at the top of the adsorption tower; the outlet of the flue gas cooling system is connected to the flue gas inlet of the adsorption tower; and adsorbents are respectively provided at positions adjacent to the saturated adsorbent outlets in the adsorption tower.

[0009] Furthermore, the NOx desorption system includes an adsorbent regeneration box, in which a saturated adsorbent is arranged; a regenerated adsorbent outlet is arranged on one side of the adsorbent regeneration box, and the concentrated nitrogen oxide gas outlet is arranged on the other side of the adsorbent regeneration box.

[0010] Furthermore, the zeolite rotor adsorption-desorption system includes a zeolite rotor, a fourth induced draft fan, a regeneration heater and a regeneration fan. The zeolite rotor is connected to the first induced draft fan and the fourth induced draft fan. The zeolite rotor forms an adsorption zone, an adsorbent cooling zone and an adsorbent regeneration zone. One end of the regeneration heater is connected to the adsorbent cooling zone through a pipeline, and the other end is connected to the adsorbent regeneration zone and the regeneration fan in sequence through a pipeline. The regeneration fan is connected to the second induced draft fan.

[0011] Furthermore, the purified flue gas outlet is arranged on a side of the fourth induced draft fan away from the zeolite rotor; the concentrated nitrogen oxide gas outlet is arranged on the regeneration fan, and the regeneration fan is connected to the second induced draft fan through the concentrated nitrogen oxide gas outlet.

[0012] Furthermore, the membrane separation system includes a membrane separator, one end of which is connected to the first induced draft fan, and the purified flue gas outlet is arranged at the other end of the membrane separator; a membrane separator flue gas outlet is arranged in the middle of the membrane separator, and a hollow fiber nanofiltration membrane is also arranged therein.

[0013] Furthermore, the concentrated nitrogen oxide gas outlet is arranged in a region of the membrane separator corresponding to the hollow fiber nanofiltration membrane.

[0014] In general, compared with the prior art, the ammonia fuel low-nitrogen combustion equipment provided by the present invention has the following beneficial effects:

[0015] 1. The present invention adopts a combustion method of preheating air and increasing swirl, which enhances the thermal motion between molecules, making the ammonia fuel and air mixed more evenly, which is beneficial for the reactants to overcome the activation energy, accelerates the reaction rate of ammonia oxidation, greatly increases the combustion rate of ammonia, and enables pure ammonia fuel to stably maintain combustion in the burner, thereby helping to reduce the NOx concentration released by ammonia combustion.

[0016] 2. The NOx generated during the adsorbent regeneration process is mixed with air and sent into the combustion chamber, so that the chemical equilibrium of reactions such as NH2+NO=N2+H2O, NH2+NO=NNH+OH, NH2+NO2=H2NO+NO in the combustion process moves towards the direction of consuming NOx, achieving the effect that the NOx concentration in the product is lower than the NOx concentration in the reactant. Combined with the adsorption effect of the adsorbent on NOx, the emission concentration of NOx in the flue gas finally discharged into the atmosphere is reduced, thereby achieving low-nitrogen combustion of ammonia fuel.

[0017] 3. The nitrogen oxide separation system shows a high degree of flexibility in design, and can flexibly adopt a variety of efficient and economical solutions based on specific application scenarios and available materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of an ammonia fuel low-nitrogen combustion device provided by the present invention;

[0019] Figure 2 It is a schematic diagram of the structure of an ammonia fuel low nitrogen combustion device equipped with a low temperature NOx adsorption-desorption system;

[0020] Figure 3It is a structural schematic diagram of an ammonia fuel low-nitrogen combustion device equipped with a zeolite wheel adsorption-desorption system;

[0021] Figure 4 It is a structural schematic diagram of an ammonia fuel low nitrogen combustion device equipped with a membrane separation system;

[0022] Figure 5 is a schematic diagram of an experimental device used in an embodiment of the present invention;

[0023] Figure 6 is a graph showing the relationship between the NOx adsorption capacity and the adsorption temperature of the activated carbon adsorbent in an embodiment of the present invention;

[0024] Figure 7 1 is the NOx breakthrough curve of the activated carbon adsorbent at different temperatures in the embodiment of the present invention.

[0025] In all the drawings, the same reference numerals are used to represent the same elements or structures, wherein: 1-burner, 2-cyclone, 3-fuel inlet, 4-air inlet, 5-igniter, 6-combustion chamber, 7-combustion chamber flue gas outlet, 8-first induced draft fan, 9-nitrogen oxide separation system, 10-purified flue gas outlet, 11-concentrated nitrogen oxide gas outlet, 12-second induced draft fan, 13-bypass valve, 14-heater, 15-cold dryer, 16-third induced draft fan, 17-smoke Gas cooling system, 18-adsorption tower, 19-adsorption tower flue gas inlet, 20-saturated adsorbent outlet, 21-adsorbent, 22-adsorbent regeneration box, 23-regenerated adsorbent outlet, 24-saturated adsorbent, 25-zeolite rotor, 26-adsorption zone, 27-adsorbent cooling zone, 28-adsorbent regeneration zone, 29-regeneration heater, 30-fourth induced draft fan, 31-regeneration fan, 32-membrane separator, 33-membrane separator flue gas outlet, 34-hollow fiber nanofiltration membrane. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] The present invention provides an ammonia fuel low-nitrogen combustion device, which utilizes an efficient NOx separation method to remove high-concentration NOx generated by ammonia combustion, so that the NOx concentration in the emitted combustion flue gas meets the relevant emission requirements; and the separated NOx is then mixed into the fuel gas and re-sent into the combustion chamber 6 for combustion, and the introduced NOx is consumed through nitrogen chemical reactions, so that the total amount of NOx generated by combustion is reduced, and the NOx separation-reburning cycle is repeated, ultimately achieving low nitrogen oxide emissions from ammonia combustion.

[0028] See also Figure 1 The combustion equipment provided by the present invention includes a combustion and flue gas purification system and a nitrogen oxide re-combustion system, wherein the combustion and flue gas purification system includes a burner 1, a combustion chamber 6, a first induced draft fan 8 and a nitrogen oxide separation system 9 connected in sequence. The burner 1 is provided with a fuel inlet 3 and an air inlet 4, respectively, the air inlet 4 is connected to a heater 14, and the bypass valve 13 is connected to the inlet of the heater 14. The end of the burner 1 opposite to the end where the fuel inlet 3 is located is arranged in the combustion chamber 6, and a cyclone 2 is correspondingly arranged. An igniter 5 is also arranged on one end of the combustion chamber 6 adjacent to the burner, and a combustion chamber flue gas outlet 7 is arranged on the other end, and the combustion chamber flue gas outlet 7 is connected to the first induced draft fan 8. The nitrogen oxide re-combustion system includes a second induced draft fan 12 and a bypass valve 13 connected in sequence. The end of the nitrogen oxide separation system 9 away from the first induced draft fan 8 is respectively provided with a purified flue gas outlet 10 and a concentrated nitrogen oxide gas outlet, and the concentrated nitrogen oxide outlet is connected to the second induced draft fan 12.

[0029] The nitrogen oxide separation system can be a low-temperature NOx adsorption-desorption system, a zeolite wheel adsorption-desorption system, or a membrane separation system. The combustion equipment configured with different nitrogen oxide separation systems can be as follows: Figure 2 , Figure 3 and Figure 4 shown.

[0030] The low-temperature NOx adsorption-desorption system includes a NOx adsorption system and a NOx desorption system, wherein the NOx adsorption system includes a cold dryer 15, a third induced draft fan 16, a flue gas cooling system 17, and an adsorption tower 18 connected in sequence. The cold dryer 15 is connected to the first induced draft fan and the inlet of the flue gas cooling system 17. An adsorption tower flue gas inlet 19 is provided on one side of the adsorption tower 18, and two saturated adsorbent outlets 20 are provided on the other side. The purified flue gas outlet 10 is provided at the top of the adsorption tower. The outlet of the flue gas cooling system is connected to the adsorption tower flue gas inlet 19. Adsorbents 21 are provided at positions adjacent to the saturated adsorbent outlets 20 in the adsorption tower. The NOx desorption system includes an adsorbent regeneration box 22. A saturated adsorbent 24 is provided in the adsorbent regeneration box 22. A regenerated adsorbent outlet 23 is provided on one side of the adsorbent regeneration box, and the concentrated nitrogen oxide gas outlet is provided on the other side of the adsorbent regeneration box.

[0031] The zeolite rotor adsorption-desorption system includes a zeolite rotor 25, a fourth induced draft fan 30, a regeneration heater 29 and a regeneration fan 31. The zeolite rotor 25 is connected to the first induced draft fan and the fourth induced draft fan 30. The zeolite rotor is formed with an adsorption zone 26, an adsorbent cooling zone 27 and an adsorbent regeneration zone 28. One end of the regeneration heater 29 is connected to the adsorbent cooling zone 27 through a pipeline, and the other end is connected to the adsorbent regeneration zone 28 and the regeneration fan 31 in sequence through a pipeline. The regeneration fan 31 is connected to the second induced draft fan. The purified flue gas outlet is arranged on the side of the fourth induced draft fan 30 away from the zeolite rotor. The concentrated nitrogen oxide gas outlet 11 is arranged on the regeneration fan 31, and the regeneration fan is connected to the second induced draft fan through the concentrated nitrogen oxide gas outlet.

[0032] The membrane separation system includes a membrane separator 32, one end of which is connected to the first induced draft fan, and the purified flue gas outlet is arranged at the other end of the membrane separator. A membrane separator flue gas outlet 33 is arranged in the middle of the membrane separator, and a hollow fiber nanofiltration membrane 34 is also arranged therein. The concentrated nitrogen oxide gas outlet is arranged in the area of ​​the membrane separator corresponding to the hollow fiber nanofiltration membrane 34.

[0033] Cold start-up phase of low-nitrogen combustion equipment: At this time, the bypass valve is closed, pure ammonia gas fuel is introduced into the burner from the fuel inlet 3, and the air is heated to 527℃~877℃ by the heater and then introduced from the air inlet 4, and forms swirling hot air through the swirler 2, and is fully mixed with the pure ammonia gas fuel at the burner head, and then ignited by the igniter 5 to carry out the combustion reaction; wherein, the volume ratio of the pure ammonia gas fuel to the air is 1:a, wherein a=3.88~4.76. The flue gas generated by the combustion is rich in nitrogen oxides and is discharged through the flue gas outlet 7 of the combustion chamber, and then the flue gas is pushed into the nitrogen oxide separation system through the first induced draft fan, and after the nitrogen oxides in the flue gas are separated and removed, the nitrogen oxide concentration in the purified flue gas is reduced to below the emission limit, and finally the purified flue gas is discharged into the atmosphere through the purified flue gas outlet. Then it enters the NOx reburning stage: at this time, the bypass valve is opened, and the NOx separation system discharges the separated concentrated NOx gas from the concentrated NOx gas outlet, and the second induced draft fan pushes the concentrated NOx gas into the air inlet pipe through the pipeline to mix it with the air. The mixed concentrated NOx gas and air are heated to 527℃~877℃ by the heater and then passed into the burner from the air inlet, and swirling hot air is formed through the swirler. Pure ammonia gas fuel is passed into the burner from the fuel inlet 3, and is fully mixed with the mixed gas of air and concentrated NOx gas at the burner head, and then ignited by the igniter to cause a combustion reaction; wherein, the volume ratio of pure ammonia gas fuel, air and concentrated NOx gas is 1:a:c, wherein a=3.88~4.76, c=0.002×(1+a)~0.006×(1+a). So far, the subsequent steps are the same as the cold start stage. The NOx produced by combustion continuously undergoes a separation-reburning cycle, thereby achieving low NOx emissions.

[0034] Take the laboratory-scale low-nitrogen combustion equipment as an example, Figure 1As shown, in the cold start stage: close the bypass valve, set the heating temperature of the heater to 627℃, determine the gas mixing ratio with ammonia and air volume ratio of 1:3.97, that is, the excess air coefficient is 1.11, and then pass the gas into the burner, and ignite it successfully through the igniter. The gas burns stably in the combustion chamber, and the flue gas generated by the combustion enters the subsequent pipeline through the flue gas outlet of the combustion chamber. At this time, a sampling point is set in the pipeline between the flue gas outlet of the combustion chamber and the first induced draft fan, and the NOx concentration in the flue gas is measured by a flue gas analyzer. The NOx concentration values ​​are read three times, and the average NOx concentration obtained is 4768.7ppm. The flue gas then enters the cold dryer for cooling, and the temperature drops to 1-10°C. At this time, the temperature is below the dew point, and the moisture in the flue gas is condensed and removed. The dry flue gas enters the flue gas cooling system for further cooling. A temperature measuring point is set in the pipeline after the flue gas cooling system. The flue gas temperature is read three times and the average value is -15.3°C. The flue gas then enters the adsorption tower, and the NOx in the flue gas is adsorbed and removed by two layers of adsorbent. The purified flue gas is discharged into the atmosphere through the purified flue gas outlet. At this time, a sampling point is set at the flue gas outlet, and the NOx concentration in the flue gas is measured by a flue gas analyzer. The NOx concentration values ​​are read three times, and the average NOx concentration obtained is 17.7ppm. After conversion (in terms of NO, more than 95% of the NOx component in the ammonia combustion product is NO) is 23.7mg / m 3Taking the Beijing-Tianjin-Hebei region and surrounding areas in China as an example, this value is lower than the relevant emission limit. Then enter the nitrogen oxide reburning stage: open the bypass valve, set the heating temperature of the heater to 627℃, and the adsorbent regeneration box starts the regeneration process. The concentrated nitrogen oxide flue gas generated is discharged through the concentrated nitrogen oxide gas outlet and is ready to be mixed with air. The gas mixing ratio is determined by the volume ratio of ammonia, air, and regenerated NOx gas of 1:3.97:0.03, that is, the excess air coefficient is 1.11, and the NOx concentration in the mixed gas is about 6000ppm. Then the gas is passed into the burner and successfully ignited by the igniter. The gas burns stably in the combustion chamber, and the flue gas generated by the combustion enters the subsequent pipeline through the flue gas outlet of the combustion chamber. At this time, a sampling point is set in the pipeline between the flue gas outlet of the combustion chamber and the first induced draft fan, and the NOx concentration in the flue gas is measured by a flue gas analyzer. The NOx concentration value is read 3 times, and the average NOx concentration obtained is 5422.3ppm, that is, the NOx concentration in the combustion product is lower than the NOx concentration added in the reactant. The regenerated NOx gas can be consumed through the combustion-adsorption-desorption-combustion cycle, thereby realizing the low-nitrogen combustion of ammonia. The flue gas then enters the cold dryer for cooling, and the temperature drops to 1-10°C. At this time, the temperature is below the dew point, and the moisture in the flue gas is condensed and removed. The dry flue gas enters the flue gas cooling system for further cooling. A temperature measuring point is set in the pipeline after the flue gas cooling system. The flue gas temperature is read three times and the average value is -14.7°C. The flue gas then enters the adsorption tower, and the NOx in the flue gas is adsorbed and removed by two layers of adsorbent. The purified flue gas is discharged into the atmosphere through the purified flue gas outlet. At this time, a sampling point is set at the flue gas outlet, and the NOx concentration in the flue gas is measured by a flue gas analyzer. The NOx concentration values ​​are read three times, and the average NOx concentration obtained is 19.3ppm, which is converted to 25.9mg / m 3 , still meets 50mg / m 3 emission limits.

[0035] like Figure 5 The experimental device is set up as shown to test the adsorption effect of activated carbon adsorbent on NOx at different temperatures. The concentrations of each component of the simulated gas are: O2: 7%; N2: 92.5%; NO: 0.5%, and the total flow rate of the simulated mixed gas is 1L / min. 10g of 20-30 mesh activated carbon particles are filled in the adsorption tube, and the NOx concentration at the outlet of the adsorption tube at different temperatures is recorded by a flue gas analyzer to measure the penetration time of the adsorbent and the adsorption capacity of activated carbon for NOx (the time point when the NO outlet concentration reaches 5% of the inlet concentration is defined as the breakthrough point, and the adsorption capacity is calculated based on the breakthrough point).

[0036] from Figure 6 and Figure 7It can be seen that as the temperature decreases, the adsorption capacity of activated carbon adsorbent for NOx increases significantly, the adsorbent penetration time is also prolonged, and the best adsorption effect is achieved at -25°C, which proves the feasibility of removing high-concentration NOx by adsorption method at low temperature.

[0037] like Figure 3 As shown, the emission reduction effect of the ammonia fuel low nitrogen combustion device equipped with a zeolite wheel adsorption-desorption system on NOx in the ammonia combustion process was tested. Cold start phase: turn off the regeneration fan, set the heating temperature of the heater to 840℃, determine the gas mixing ratio with an ammonia gas and air volume ratio of 1:3.97, that is, the excess air coefficient is 1.11, then pass the gas into the burner, successfully ignite it through the igniter, the gas burns stably in the combustion chamber, and the flue gas generated by the combustion enters the subsequent pipeline through the flue gas outlet of the combustion chamber. At this time, a sampling point is set in the pipeline between the flue gas outlet of the combustion chamber and the first induced draft fan, and the NOx concentration in the flue gas is measured by a flue gas analyzer. The NOx concentration value is read 3 times, and the average NOx concentration obtained is 6543.2ppm. Then the flue gas enters the adsorption area 26 in the zeolite wheel, where NOx is adsorbed and captured. The purified flue gas is discharged into the atmosphere through the purified flue gas outlet. At this time, a sampling point is set at the flue gas outlet, and the NOx concentration in the flue gas is measured by a flue gas analyzer. The NOx concentration values ​​are read three times, and the average NOx concentration obtained is 24.5ppm. After conversion (in terms of NO, more than 95% of the NOx components in the ammonia combustion products are NO), it is 32.8mg / m 3 Taking Beijing-Tianjin-Hebei and surrounding areas in China as an example, the value is less than 50mg / m 3emission limits. Then enter the nitrogen oxide reburning stage: turn on the regeneration fan, set the heating temperature of the heater to 700℃, start the regeneration process in the adsorbent regeneration zone, and the concentrated nitrogen oxide flue gas generated is discharged through the concentrated nitrogen oxide gas outlet, ready to be mixed with air, and the gas mixing ratio is determined by the volume ratio of ammonia, air, and regenerated NOx gas of 1:3.97:0.03, that is, the excess air coefficient is 1.11, and the NOx concentration in the mixed gas is about 6000ppm. Then the gas is passed into the burner and successfully ignited by the igniter. The gas burns stably in the combustion chamber, and the flue gas generated by the combustion enters the subsequent pipeline through the flue gas outlet of the combustion chamber. At this time, a sampling point is set in the pipeline between the flue gas outlet of the combustion chamber and the first induced draft fan, and the NOx concentration in the flue gas is measured by a flue gas analyzer. The NOx concentration value is read 3 times, and the average NOx concentration obtained is 7048.6ppm, that is, the NOx concentration in the combustion product is lower than the NOx concentration added in the reactant. The regenerated NOx gas can be consumed through the combustion-adsorption-desorption-combustion cycle, thereby realizing the low-nitrogen combustion of ammonia. Then the flue gas enters the adsorption area of ​​the zeolite wheel, where NOx is adsorbed and captured. The purified flue gas is discharged into the atmosphere through the purified flue gas outlet. At this time, a sampling point is set at the flue gas outlet, and the NOx concentration in the flue gas is measured with a flue gas analyzer. The NOx concentration values ​​are read three times, and the average NOx concentration obtained is 28.7ppm, which is converted to 38.5mg / m 3 , still meets 50mg / m 3 emission limits.

[0038] like Figure 4 The experimental device is set up as shown to test the effect of the ammonia fuel low nitrogen combustion device equipped with a membrane separation system on the reduction of NOx emissions during ammonia combustion. Cold start stage: close the bypass valve, set the heating temperature of the heater to 760℃, and determine the gas mixing ratio with an ammonia gas and air volume ratio of 1:3.97, that is, the excess air coefficient is 1.11, then pass the gas into the burner, and successfully ignite it through the igniter. The gas burns stably in the combustion chamber, and the flue gas generated by the combustion enters the subsequent pipeline through the flue gas outlet of the combustion chamber. At this time, a sampling point is set in the pipeline between the flue gas outlet of the combustion chamber and the first induced draft fan, and the NOx concentration in the flue gas is measured by a flue gas analyzer. The NOx concentration value is read 3 times, and the average NOx concentration obtained is 5438.5ppm. Then the flue gas enters the flue gas inlet of the membrane separator, and NOx is separated by the hollow fiber nanofiltration membrane. The purified flue gas is discharged into the atmosphere through the purified flue gas outlet. At this time, a sampling point is set at the flue gas outlet, and the NOx concentration in the flue gas is measured by a flue gas analyzer. The NOx concentration value is read three times, and the average NOx concentration obtained is 20.4ppm. After conversion (in terms of NO, more than 95% of the NOx component in the ammonia combustion product is NO), it is 27.3mg / m 3Taking Beijing-Tianjin-Hebei and surrounding areas in China as an example, the value is less than 50mg / m 3 The emission limit is reached. Then the nitrogen oxide reburning stage is entered: the outlet of concentrated nitrogen oxide gas is opened, and the nitrogen oxide gas is discharged and mixed with air. The gas mixing ratio is determined by the volume ratio of ammonia, air, and regenerated NOx gas of 1:3.97:0.03, that is, the excess air coefficient is 1.11, and the NOx concentration in the mixed gas is about 6000ppm. Then the gas is passed into the burner and successfully ignited by the igniter. The gas burns stably in the combustion chamber, and the flue gas generated by the combustion enters the subsequent pipeline through the flue gas outlet of the combustion chamber. At this time, a sampling point is set in the pipeline between the flue gas outlet of the combustion chamber and the first induced draft fan, and the NOx concentration in the flue gas is measured by a flue gas analyzer. The NOx concentration values ​​are read three times, and the average NOx concentration obtained is 6083.4ppm, that is, the NOx concentration in the combustion product is lower than the NOx concentration added in the reactant. The regenerated NOx gas can be consumed through the combustion-separation-reburning cycle, thereby realizing the low-nitrogen combustion of ammonia. Then the flue gas enters the flue gas inlet of the membrane separator, and NOx is separated by the hollow fiber nanofiltration membrane. The purified flue gas is discharged into the atmosphere through the purified flue gas outlet. At this time, a sampling point is set at the flue gas outlet, and the NOx concentration in the flue gas is measured by a flue gas analyzer. The NOx concentration values ​​are read three times, and the average NOx concentration obtained is 23.8ppm, which is converted to 31.9mg / m 3 , still meets 50mg / m 3 emission limits.

[0039] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An ammonia fuel low nitrogen combustion device, characterized in that: The combustion equipment includes a combustion and flue gas purification system and a nitrogen oxide re-combustion system, wherein the combustion and flue gas purification system includes a burner, a combustion chamber, a first induced draft fan and a nitrogen oxide separation system connected in sequence; the burner is respectively provided with a fuel inlet and an air inlet, and the air inlet is connected to a heater; the end of the burner opposite to the end where the fuel inlet is located is arranged in the combustion chamber, and a swirler is correspondingly arranged; an igniter is also arranged on one end of the combustion chamber adjacent to the burner, and a combustion chamber flue gas outlet is arranged on the other end, and the combustion chamber flue gas outlet is connected to the first induced draft fan; the nitrogen oxide re-combustion system includes a second induced draft fan and a bypass valve connected in sequence; the nitrogen oxide separation system is respectively provided with a purified flue gas outlet and a concentrated nitrogen oxide gas outlet at one end away from the first induced draft fan, and the concentrated nitrogen oxide outlet is connected to the second induced draft fan; the bypass valve is connected to the inlet of the heater.

2. The ammonia fuel low nitrogen combustion equipment according to claim 1, characterized in that: The nitrogen oxide separation system is one of a low-temperature NOx adsorption-desorption system, a zeolite wheel adsorption-desorption system, and a membrane separation system.

3. The ammonia fuel low nitrogen combustion equipment according to claim 2, characterized in that: The low-temperature NOx adsorption-desorption system includes a NOx adsorption system and a NOx desorption system, wherein the NOx adsorption system includes a cold dryer, a third induced draft fan, a flue gas cooling system, and an adsorption tower which are connected in sequence; the cold dryer is connected to the first induced draft fan and the inlet of the flue gas cooling system; an adsorption tower flue gas inlet is provided on one side of the adsorption tower, and two saturated adsorbent outlets are respectively provided on the other side; the purified flue gas outlet is provided on the top of the adsorption tower; the outlet of the flue gas cooling system is connected to the flue gas inlet of the adsorption tower; and adsorbents are respectively provided at positions adjacent to the saturated adsorbent outlets in the adsorption tower.

4. The ammonia fuel low nitrogen combustion equipment according to claim 3, characterized in that: The NOx desorption system comprises an adsorbent regeneration box, in which a saturated adsorbent is arranged; a regenerated adsorbent outlet is arranged on one side of the adsorbent regeneration box, and the concentrated nitrogen oxide gas outlet is arranged on the other side of the adsorbent regeneration box.

5. The ammonia fuel low nitrogen combustion equipment according to claim 2, characterized in that: The zeolite rotor adsorption-desorption system includes a zeolite rotor, a fourth induced draft fan, a regeneration heater and a regeneration fan. The zeolite rotor is connected to the first induced draft fan and the fourth induced draft fan. The zeolite rotor is formed with an adsorption zone, an adsorbent cooling zone and an adsorbent regeneration zone. One end of the regeneration heater is connected to the adsorbent cooling zone through a pipeline, and the other end is connected to the adsorbent regeneration zone and the regeneration fan in sequence through a pipeline. The regeneration fan is connected to the second induced draft fan.

6. The ammonia fuel low nitrogen combustion equipment according to claim 5, characterized in that: The purified flue gas outlet is arranged on a side of the fourth induced draft fan away from the zeolite rotor; the concentrated nitrogen oxide gas outlet is arranged on the regeneration fan, and the regeneration fan is connected to the second induced draft fan through the concentrated nitrogen oxide gas outlet.

7. The ammonia fuel low nitrogen combustion equipment according to claim 2, characterized in that: The membrane separation system includes a membrane separator, one end of which is connected to the first induced draft fan, and the purified flue gas outlet is arranged at the other end of the membrane separator; a membrane separator flue gas outlet is arranged in the middle of the membrane separator, and a hollow fiber nanofiltration membrane is also arranged therein.

8. The ammonia fuel low nitrogen combustion equipment according to claim 7, characterized in that: The concentrated nitrogen oxide gas outlet is arranged in a region of the membrane separator corresponding to the hollow fiber nanofiltration membrane.

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