CN217979280U

CN217979280U - Ultralow nitrogen emission gas hot-blast furnace

Info

Publication number: CN217979280U
Application number: CN202221119073.9U
Authority: CN
Inventors: 林永兵
Original assignee: Huangshi Xinrui Environmental Protection Technology Co ltd
Current assignee: Huangshi Xinrui Environmental Protection Technology Co ltd
Priority date: 2022-05-10
Filing date: 2022-05-10
Publication date: 2022-12-06
Anticipated expiration: 2032-05-10

Abstract

The utility model discloses an ultralow nitrogen discharges gas hot-blast furnace, including furnace body and combustor, the furnace body includes inside lining and the shell that the interval set up, be formed with the first shell side that is used for circulating tail gas flow in the cavity between inside lining and the shell, the combustor sets up on being located the furnace body of first shell side one side, and set up the gas outlet that is used for circulating tail gas outflow on being located the furnace body shell of first shell side, the gas outlet has the air mixer through the pipe connection, another air inlet of air mixer lets in combustion air and air mixer's gas outlet through the air inlet intercommunication of combustion air blower with the combustor, circulating tail gas gets into and sprays in the furnace body with the mist entering combustor that forms the surplus coefficient of low air after the combustion air mixes in the air mixer, the inside high temperature strong reduction zone who forms rich combustion in of the inside lining of furnace body, make quick type nitrogen oxide and the thermal type nitrogen oxide that produces in the combustion process, and the fuel nitrogen that nitrogenous gas produced is reduced into nitrogen gas.

Description

Ultralow nitrogen emission gas hot-blast furnace

Technical Field

The utility model belongs to the technical field of the industrial kiln, a kiln that all kinds of gas combustion, production high temperature flue gas or hot-blast is related to, its predominant use provides the heat source for all kinds of drying equipment and each trade fume emission pretreatment system of chemical industry/metallurgy/building materials trade. The utility model particularly relates to an ultralow nitrogen discharges gas hot-blast furnace.

Background

NOx is a main pollutant causing urban pollution, and the national emission requirement on boiler nitrogen oxide is strictly controlled according to the existing emission standard of boiler atmospheric pollutants BG 13271-2014. At present, china has many provinces or regions which have more strict local emission standards than national standards, for example, beijing requires that the emission of nitrogen oxide of a newly-built boiler is not more than 30mg/m < 3 >, and in the southern California region of the United states, even a boiler with power less than 6MW is subjected to the emission of nitrogen oxide of less than 18mg/m < 3 >. Therefore, the development of ultra-low nitrogen combustion technology is not only a requirement of environmental protection, but also an urgent need of the times.

The existing gas hot blast stove generally realizes low-nitrogen combustion by an air classification/fuel classification/flue gas recirculation/rotational flow impact premixing method or a method combining the above technologies. The technical means mainly solve the problems that thermal nitrogen oxide (N2 in air is oxidized and generated at high temperature) generated by a Zeller David mechanism in the combustion process is inhibited from generating thermal nitrogen by controlling the temperature of combustion flame, for example, the publication No. CN110513887A discloses a gas hot blast stove with ultralow nitrogen emission. There is also a new diffusion combustion technology: 20% -50% of natural gas is directly introduced into the flame center, and the natural gas absorbs a large amount of heat in the process of cracking into carbon black, so that the temperature of combustion flame is reduced, and low nitrogen emission is realized. However, the above prior art means cannot solve the problem of fast nitrogen oxides (generated by the reaction of N2 in air and hydrocarbon ion groups in fuel) generated during combustion and the problem of fuel nitrogen (generated by the oxidation of nitrogen compounds in fuel after thermal decomposition) generated by nitrogen-containing fuel gas, so that the development of ultra-low nitrogen combustion technology is limited, and the ultra-low nitrogen emission with strict standards cannot be realized. For nitrogen-containing gas, the emission standard can not be reached even during combustion, and ammonia is sprayed in the furnace or denitration treatment is carried out on the discharged flue gas.

SUMMERY OF THE UTILITY MODEL

Therefore, an object of the utility model is to provide an ultralow nitrogen discharges gas hot-blast furnace to solve current gas hot-blast furnace and only can solve heating power type nitrogen oxide and can't solve the technical problem of quick type nitrogen oxide and fuel type nitrogen oxide, realize the ultralow nitrogen and discharge.

The utility model discloses a realize that the technical scheme that above-mentioned technical purpose adopted as follows:

the utility model provides an ultralow nitrogen discharges gas hot-blast furnace, includes furnace body and combustor, the furnace body includes inside lining and the shell that the interval set up, be formed with the first shell side that is used for circulating tail gas flow in the cavity between inside lining and the shell, the combustor sets up on being located the furnace body of first shell side, and be located set up the gas outlet that is used for circulating tail gas to flow out on the furnace body shell of first shell side one side, the gas outlet has the air-mixing ware through the pipe connection, another air inlet of air-mixing ware lets in combustion-supporting air and the gas outlet of air-mixing ware pass through combustion-supporting air blower with the air inlet intercommunication of combustor, circulation tail gas gets into form the mixed gas of low excess air coefficient after mixing with combustion-supporting air in the air-mixing ware and gets into the combustor and sprays in the furnace body the inside high temperature strong reduction zone that forms rich combustion of the inside fuel that forms of inside quick type nitrogen oxide and the thermal type nitrogen oxide that produces of combustion process and the fuel nitrogen that contains is reduced into nitrogen gas.

Furthermore, a circulating tail gas inlet is formed in the furnace body shell on one side of the first shell pass and communicated with a tail gas discharge port of a hot blast stove or a smoke discharge port of drying equipment through a pipeline, and the circulating tail gas is inert gas containing carbon dioxide, water vapor, nitrogen and a small amount of oxygen.

Furthermore, still be formed with the second shell side in the cavity between the inside lining of furnace body and the shell, the second shell side is separated through the baffle that sets up in the cavity with first shell side, is located be equipped with ashes air inlet on the furnace body shell of second shell side one side, this ashes air inlet has ashes air blower through the pipe connection, is located be equipped with quick air distributor on the furnace body inside lining of second shell side, and the ashes air enters into the second shell side through ashes air inlet and heats up the back and is entered into the furnace body by quick air distributor in the inside formation ashes district of furnace body inside lining, be used for with the gas that the strong reducing zone of high temperature did not burn out the ashes is in ashes district ashes of burning.

Furthermore, the quick air distributor comprises an air distributor box body and an air outlet plate, wherein a plurality of cyclone blades are arranged in the air distributor box body, the rotating direction of the cyclone blades is opposite to the direction of air flow which is sprayed to the high-temperature strong reduction area, and a plurality of spraying air holes are formed in the air outlet plate.

Furthermore, the combustor is an FGR low-nitrogen gas combustor which is arranged at the side of the furnace body in a tangential manner, so that flame formed by gas, combustion air and circulating tail gas is ejected from the FGR low-nitrogen gas combustor and then enters the furnace body tangentially, and a rotational flow is formed in the high-temperature strong reduction region, so that the turbulence degree of the gas is enhanced, the retention time of the gas in the region is prolonged, and the reduction of nitrogen oxide is facilitated.

Furthermore, one side of the furnace body, which is positioned on the first shell pass, is provided with an explosion venting valve.

Furthermore, a combustion-supporting air blower is arranged on a pipeline for communicating the air mixer with the combustor.

Furthermore, a valve and a flowmeter are arranged at an air outlet for the circulating tail gas to flow out, an air inlet for the air mixer to introduce combustion air and an air inlet for the burnout air.

Furthermore, the furnace body is of a cylindrical double-shell structure, and the lining of the furnace body is made of refractory materials.

Compared with the prior art, the utility model provides a pair of ultralow nitrogen discharges gas hot-blast furnace has following several beneficial effect:

1. the utility model discloses a hot-blast furnace is through letting in circulation tail gas in the air mixer, adopt circulation tail gas to replace the partial combustion air that the hot-blast furnace burning needs, and make circulation tail gas and combustion air mix the mixed air that forms lower excess air coefficient through control combustion-supporting air quantity, this mixed air passes through the combustor and sprays to the stove in, form the high temperature strong reduction zone of rich burning in the stove, in this region, the fast type nitrogen oxide and the thermal type nitrogen oxide that produce in the combustion process, and the fuel nitrogen that nitrogenous gas (the nitrogen content of all kinds of nitrogenous gas is in 2% ~ 3%) produced is reduced into nitrogen gas, the problem that can't handle fast type nitrogen oxide and fuel type nitrogen oxide among the prior art has been solved, the emission of nitrogen oxide has been greatly reduced, make the nitrogen oxide emission volume of hot-blast furnace accord with the standard that is no more than 30mg/m3, even lower;

2. meanwhile, when the circulating tail gas is introduced into the second shell pass, the hot blast stove can absorb the heat of the stove body to evaporate condensed water in the second shell pass, so that the combustion temperature is reduced, and the generation of thermal nitrogen can be inhibited; and a certain amount of circulating tail gas is introduced, so that the oxygen content of a high-temperature strong reduction zone in the furnace is reduced, and a strong reduction atmosphere is established;

3. the hot blast stove can absorb the heat of the stove body when the circulating tail gas is introduced into the second shell pass, the heat is just used for evaporating condensed water in the circulating tail gas, the problem of condensed water in the tail gas circulating process is solved, and especially the effect on the tail gas containing a large amount of steam and condensed water after drying is more obvious;

4. the utility model discloses a hot-blast furnace, because circulation tail gas itself also has certain heat, consequently, to the whole waste heat that has utilized circulation tail gas of hot-blast furnace, have energy saving and emission reduction's advantage.

Drawings

Fig. 1 is a schematic view of the whole structure of the ultra-low nitrogen emission gas hot-blast stove of the present invention.

Shown in the figure:

1-furnace body, 11-lining, 12-outer shell, 13-first shell pass, 14-gas outlet, 15-circulating tail gas inlet, 16-second shell pass, 17-burnout air inlet, 2-burner, 3-air mixer, 4-clapboard, 5-burnout air blower, 6-rapid air distributor, 7-explosion venting valve and 8-combustion-supporting blower.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the invention.

The utility model discloses can only solve heating power type nitrogen oxide and can't solve the technical problem of quick type nitrogen oxide and fuel type nitrogen oxide to current gas hot-blast furnace, an ultralow nitrogen discharges gas hot-blast furnace is proposed, this gas hot-blast furnace carries out the low nitrogen burning design as a whole from the combustor to the burning overall process of each district section in the stove, through the degree of depth to the air hierarchical, establish high temperature strong reduction zone (main burning zone) in the stove and carry out the nitrogen reduction to quick type nitrogen oxide and fuel type nitrogen oxide, and establish the burn-out district and carry out the burn-out to the fuel that main burning zone unburnt was accomplished.

Please refer to fig. 1, the utility model relates to an ultralow nitrogen emission gas hot-blast furnace includes furnace body 1 and combustor 2, furnace body 1 is the cylinder double shell structure, furnace body 1 includes inside lining 11 and the shell 12 that the interval set up, and inside lining 11 is made by refractory material, be formed with the first shell side 13 that is used for circulating the tail gas to flow in the cavity between inside lining 11 and the shell 12, combustor 2 sets up on the furnace body 1 that is located first shell side 13 one side, and set up the gas outlet 14 that is used for circulating the tail gas to flow on the shell 12 of furnace body 1 that is located first shell side 13 one side, gas outlet 14 has a wind mixer 3 through the pipe connection, another air inlet of wind mixer 3 lets in combustion-supporting air and the gas outlet of wind mixer 3 through the pipeline with the air inlet of combustor 2 intercommunication, so set up, circulation tail gas in the first shell side 13 gets into wind mixer 3 through heating power gas outlet 14, replaces the mixed gas that forms lower air and gets into combustor 2 and sprays in the combustion-supporting air mixture of combustion-supporting coefficient after partly combustion-supporting air that the hot-blast furnace burns needs to form in the nitrogen oxide reduction type of nitrogen in furnace body 1, the nitrogen oxide reduction type that the nitrogen that the inside produced of furnace body and nitrogen reduction type is reduced the nitrogen.

In the above technical solution, the air outlet 14 from which the circulating tail gas flows out and the air inlet through which the combustion air is introduced into the air mixer 3 are both provided with a valve and a flowmeter for controlling and adjusting the amounts of the circulating tail gas and the combustion air, respectively, so as to reduce the air excess coefficient of the mixed air to a proper value, which is beneficial to forming a rich-burning high-temperature strong reduction region in the liner 11, thereby being beneficial to reducing the nitrogen oxide.

Meanwhile, the generation of nitrogen oxide in the combustion process is not rapid any more, NO is reduced, and the formation of nitrogen oxide is prevented, and the main chemical reactions are as follows: n + NO → N2+ O,

NH+NO→N2+OH NH+NO→N2O+H，

N2O+H→N2+OH N2O(+M) →N2+O(+M)。

in addition, according to the technical scheme, the circulating tail gas is introduced into the first shell pass 13, so that the heat of the furnace body 1 can be absorbed and used for evaporating condensed water in the circulating tail gas, the combustion temperature of the combustor is reduced by the circulating tail gas, the generation amount of thermal nitrogen oxide is inhibited, the problem of condensed water in the circulating tail gas of the whole hot blast furnace system is solved, and meanwhile, the waste heat of the tail gas is utilized, so that the energy-saving and emission-reducing advantages are achieved.

In specific implementation, a circulating tail gas inlet 15 is formed in an outer shell 12 of the furnace body 1 on one side of the first shell pass 13, the circulating tail gas inlet 15 is communicated with a tail gas discharge port of the hot blast stove or a flue gas discharge port of the drying equipment through a pipeline, namely the source of the circulating tail gas is tail gas discharged by a hot blast stove system or flue gas of the drying equipment in the system, the circulating tail gas is inert gas containing carbon dioxide, water vapor, nitrogen and a small amount of oxygen, and the inert gas is used for replacing part of combustion-supporting air required by combustion of the hot blast stove, so that the deep classification of the combustion-supporting air entering the combustor 2 is achieved, a strong reducing atmosphere is formed in the furnace body 1, the reduction of nitrogen oxide is realized, and the purpose of reducing the emission of the nitrogen oxide is realized.

Specifically, unburnt fuel gas exists in the high-temperature strong reduction zone, and in order to burn the unburnt fuel gas in the high-temperature strong reduction zone, a burning zone is arranged in the furnace body 1, and the space between the burning zone and the high-temperature strong reduction zone is invisibly arranged in the furnace body 1. Furthermore, a second shell side 16 is formed in a cavity between the inner liner 11 and the outer shell 12 of the furnace body 1, the second shell side 16 and the first shell side 13 are separated by a partition plate 4 arranged in the cavity, an ember air inlet 17 is arranged on the outer shell 12 of the furnace body 1 on one side of the second shell side 16, the ember air inlet 17 is connected with an ember air blower 5 through a pipeline, a rapid air distributor 6 is arranged on the inner liner 11 of the furnace body 1 on one side of the second shell side 16, ember air enters the second shell side 16 through the ember air inlet 17, is heated and then enters the furnace body 1 through the rapid air distributor 6, an ember area is formed inside the inner liner 11 of the furnace body 1, gas which is not ember in a high-temperature strong reduction area enters the ember area along with flue gas generated by ember, and is ember through ember air distributed by the rapid air distributor 6, the ember gas which is not ember, the conversion rate of nitrogen oxide changes along with the change of the ember air ratio, and when the ratio of the air reaches a low value of 35%, the nitrogen oxide conversion rate.

Concretely, in order to cooperate the function of the strong reduction district of high temperature, the utility model discloses a quick cloth wind ware 6 includes cloth wind ware box and goes out the aerofoil, be equipped with a plurality of whirl blade in the cloth wind ware box, the whirl blade revolve to need with spray extremely the air current opposite direction of the strong reduction district of high temperature, it has seted up a plurality of injection wind eyes on the aerofoil, so, form the air current of opposite direction at the strong reduction district of high temperature with the mixed air that sprays from the blowout wind eye spun ashes wind, is favorable to the formation of the strong reduction district of high temperature (main combustion district) and ashes district.

Specifically, the combustor 2 is an FGR (flue gas or exhaust gas recirculation) low-nitrogen gas combustor, and the FGR low-nitrogen gas combustor is tangentially arranged at the side of the furnace body 1, so that flame formed by fuel gas, combustion air and circulating tail gas is ejected from the FGR low-nitrogen gas combustor and then tangentially enters the furnace body 1, namely tangentially enters a high-temperature strong reduction region, the flue gas forms strong rotational flow in the region, the turbulence degree of the flue gas is enhanced, the retention time of the flue gas in the region is prolonged, and the reduction of nitrogen oxide is facilitated.

In addition, one side of the furnace body 1, which is positioned on the first shell pass 13, is provided with an explosion venting valve 7; a combustion-supporting blower 8 is arranged on a pipeline for communicating the air mixer 3 with the combustor 2; and a valve and a flowmeter are arranged at the position of the burnout air inlet 17 and are used for controlling the amount of the burnout air entering the burnout area.

The utility model provides a pair of ultralow nitrogen discharges gas hot-blast furnace's theory of operation does:

circulating tail gas (waste gas) enters a first shell pass 13 of the furnace body 1 through a circulating tail gas inlet 15, is heated in the first shell pass 13 to raise the temperature, is evaporated with condensed water and then exits the first shell pass 13 through an air outlet 14 to enter the air mixer 3 to be mixed with combustion-supporting air, and because the circulating tail gas is inert gas, mixed air with low air excess coefficient is formed after being mixed with the combustion-supporting air, and the mixed air is sent into the combustor 2 through the combustion-supporting blower 8; the FGR low-nitrogen gas burner rearranges and cuts the fed mixed gas and fuel gas, tangentially enters a high-temperature strong reduction zone (main combustion zone) in the furnace body 1 to carry out combustion and reduction reaction of nitrogen oxide, the temperature of the main combustion zone is 1000-1200 ℃, the burning equivalence ratio is more than 1.2, low-nitrogen smoke combusted in the main combustion zone and part of unburnt fuel gas enter an ember zone, ember air is fed into a second shell side 16 through an ember air blower 5 to be heated and heated, then the ember air is distributed by a rapid air distributor 6 to enter the ember zone in the furnace body 1, and the ember air reacts with the unburnt fuel gas in the main combustion zone in the ember zone to completely ember the fuel gas. Meanwhile, according to the requirement of the outlet temperature of the hot blast stove (different outlet temperatures under different application scenes), the proper outlet temperature is achieved by adjusting the air volume of the burnout air, and the emission of ultralow nitrogen oxide is realized under the condition of ensuring various performances of the hot blast stove. For example: a gas hot blast stove (XRQS-C-12 type) matched with the slag grinding system, the heat supply energy of which is 1.2 × 107kcal/h, natural gas for combustion and coke oven gas, and a dual-fuel low-nitrogen burner. The furnace adopts the circulation of the dried tail gas, the amount of the circulating tail gas accounts for 20 percent of the amount of the combustion-supporting air, a proper low excess air coefficient value is adopted in a high-temperature strong reduction area, the temperature of a main combustion area is 1000 ℃, the pressure in a furnace body 1 is-100 Pa, the temperature of an after-combustion area is 800 ℃, and when the air rate of the after-combustion area is 30 percent, the emission concentration of the nitrogen oxide at the outlet of a hot blast furnace is actually measured to be 22mg/m < 3 >, so that the emission standard (30 mg/m < 3 >) which has the highest requirement on the nitrogen oxide in China at present is reached.

To sum up, the utility model provides an ultra-low nitrogen discharge gas hot blast stove, replace part combustion air with the circulation tail gas and join in marriage the stove through the combustor in, through establishing high temperature strong reduction zone (main combustion area) and burn-out area in the stove to the degree of depth of air grading, join in marriage the combustor through circulation tail gas and reduce combustion temperature, restrained the formation volume of heating power type nitrogen oxide; meanwhile, under the high-temperature strong reducing atmosphere of the main combustion zone, the rapid nitrogen oxide and fuel nitrogen generated in the combustion process are reduced into nitrogen, and the formation of the nitrogen oxide is prevented. The fuel gas which is not burnt out in the main burning zone enters the burning-out zone together with the flue gas generated by burnt-out. In the burning zone, the burning air is distributed by the rapid air distributor to burn out the uncombusted fuel gas. The utility model provides a problem that the fuel nitrogen that nitrogenous gas produced and the quick nitrogen that produces discharged in the combustion process, also reduced the formation volume of heating power nitrogen simultaneously, realized nitrogen oxide's ultralow emission. The nitrogen oxide generated in the combustion process of natural gas and various nitrogen-containing fuel gases (nitrogen content is 2-3%) is not more than 30mg/m < 3 >, even lower.

The above description is intended to illustrate the embodiments of the present invention, and not to limit the scope of the invention. Any other corresponding changes and modifications made according to the technical idea of the present invention should be included in the scope of the claims of the present invention.

Claims

1. The utility model provides an ultralow nitrogen discharges gas hot-blast furnace, includes furnace body and combustor, its characterized in that, the furnace body includes inside lining and the shell that the interval set up, be formed with the first shell side that is used for circulating tail gas flow in the cavity between inside lining and the shell, the combustor sets up and is located on the furnace body of first shell side one side, and be located offer the gas outlet that is used for circulating the tail gas outflow on the furnace body shell of first shell side one side, the gas outlet has the air mixer through the pipe connection, another air inlet of air mixer let in combustion air with the gas outlet of air mixer pass through combustion air blower with the air inlet intercommunication of combustor, circulation tail gas gets into form the mist of low air excess coefficient and get into the combustor and spray in the furnace body after mixing with combustion air in the air mixer, the inside high temperature strong reduction zone that forms rich combustion for quick type nitrogen oxide and the thermal type nitrogen oxide that produce in the combustion process and the fuel nitrogen that contains that the nitrogen gas produced are reduced into nitrogen.

2. The ultra-low nitrogen emission gas hot blast stove according to claim 1, wherein a circulating tail gas inlet is provided on the stove body housing on one side of the first shell side, and the circulating tail gas inlet is communicated with a tail gas discharge port of the hot blast stove or a flue gas discharge port of the drying device through a pipeline.

3. The ultra-low nitrogen emission gas hot blast stove according to claim 1, wherein a second shell pass is further formed in the cavity between the inner liner and the outer shell of the stove body, the second shell pass is separated from the first shell pass by a partition plate provided in the cavity, an ember air inlet is provided on the outer shell of the stove body on the side of the second shell pass, the ember air inlet is connected with an ember air blower through a pipeline, a fast air distributor is provided on the inner liner of the stove body on the side of the second shell pass, ember air enters the second shell pass through the ember air inlet, is heated and then enters the stove body through the fast air distributor, and an ember zone is formed inside the inner liner of the stove body for embering out the gas which is not embered in the high temperature strong reduction zone in the ember zone.

4. The ultra-low nitrogen emission gas hot blast stove according to claim 3, wherein the rapid air distributor comprises an air distributor box body and an air outlet plate, a plurality of swirl vanes are arranged in the air distributor box body, and a plurality of injection air holes are arranged on the air outlet plate.

5. The ultra-low nitrogen emission gas hot blast stove according to claim 4, wherein the swirl vanes are rotated in a direction opposite to the flow direction of the mixed gas injected into the high temperature strong reduction zone.

6. The ultra-low nitrogen emissions gas hot blast stove according to claim 1, wherein said burner is a FGR low nitrogen gas burner.

7. The ultra-low nitrogen emission gas hot blast stove according to claim 6, wherein the FGR low nitrogen gas burner is tangentially arranged at the side of the stove body, so that flame formed by gas, combustion air and circulating tail gas is ejected from the FGR low nitrogen gas burner and then tangentially enters the stove body, and forms rotational flow in the high temperature strong reduction zone.

8. The ultra-low nitrogen emission gas hot blast stove according to claim 1, wherein an explosion venting valve is provided on a side of the stove body on the first shell side.

9. The ultra-low nitrogen emission gas hot blast stove according to claim 3, wherein a valve and a flow meter are provided at the outlet of the circulating tail gas, the inlet of the air mixer for introducing combustion air and the inlet of the burnout air.

10. The ultra-low nitrogen emission gas hot blast stove according to claim 1, wherein the stove body has a cylindrical double shell structure, and an inner lining of the stove body is made of a refractory material.