Sulfur tail gas treatment process with low nitrogen oxide emission and treatment equipment thereof

Abstract

The invention provides a sulfur tail gas treatment process with low nitrogen oxide emission and treatment equipment thereof.The process comprises the following steps that S1, steam, fuel gas and first-stage combustion-supporting air are mixed and combusted in a combustor to form a high-temperature flue gas group, and the amount of the first-stage combustion-supporting air is 80-90% of the amount of air needed for complete combustion of the fuel gas; s2, secondary combustion-supporting air enters the furnace body and is uniformly mixed with combusted high-temperature flue gas clusters, and the amount of the secondary combustion-supporting air is 30%-50% of the amount of air required for complete combustion of the fuel gas; and S3, the third-stage combustion air and the sulfur tail gas enter the furnace body to be subjected to mixed combustion, the third-stage combustion air amount is the air amount needed by sulfur tail gas incineration, and adjustment is conducted according to the standard that the oxygen content of flue gas exhausted by the furnace body is 3%. Generation of nitric oxide is effectively controlled by adopting a steam nitrogen reduction technology and an oxygen-deficient combustion technology, and the emission amount of the nitric oxide can be reduced by about 50%.

Description

Technical Field

[0001] The invention belongs to the field of air pollution treatment, and specifically relates to a sulfur tail gas treatment process with low nitrogen oxide emission and a treatment device thereof. Background Art

[0002] Sulfur recovery is an essential environmental protection device in the petrochemical, natural gas and coal chemical industries. The burner of the sulfur recovery unit incinerator is the key equipment for the sulfur recovery unit to meet environmental standards. The sulfur recovery unit tail gas incineration mainly burns and oxidizes the tail gas containing a small amount of hydrocarbons, hydrogen, trace H2S, S and other toxic and harmful components generated during the production process in the furnace to achieve efficient incineration.

[0003] During the incineration of tail gas, fuel gas is consumed to maintain the incineration temperature of the incinerator. During the combustion of fuel gas, the flame burns in a high-temperature insulated furnace body. Part of the N2 in the air is oxidized in the high-temperature flame to generate nitrogen oxides (NOX). At present, the burners of tail gas incinerators at home and abroad have also begun to adopt low-nitrogen combustion technology. The technology of graded air distribution, fuel gas classification, and oxygen-deficient combustion is generally used to control nitrogen oxides. Tail gas incinerators usually use air classification technology to control nitrogen oxides. The first-level air participates in the combustion of fuel gas, and the second-level air adjusts the oxygen content of the flue gas at the outlet of the incinerator. There is no heat-absorbing medium in the combustion in the fire channel of the incinerator, which is close to adiabatic combustion. The flame temperature is difficult to control, the thermal NOX generation is large, and the nitrogen oxide control effect is poor; the tail gas and secondary air in the furnace are unevenly mixed, and incomplete combustion is very likely to occur, generating a large amount of CO, which not only wastes energy but also pollutes the environment, affecting the long-term safe and stable operation of the sulfur recovery tail gas treatment device. The above combustion technologies for controlling nitrogen oxides are difficult to achieve ideal values. Ultra-low NOX emissions are key technologies urgently needed in the tail gas incineration link. Summary of the invention

[0004] 1. Technical issues to be resolved In view of the above technical problems, the present invention provides a sulfur tail gas treatment process with low nitrogen oxide emissions and its treatment equipment, which adopts steam nitrogen reduction technology and oxygen-deficient combustion technology to effectively control the generation of nitrogen oxides, and the emission of nitrogen oxides can be reduced by about 50%.

[0005] (II) Technical solution The present invention provides a sulfur tail gas treatment process with low nitrogen oxide emission, the steps are as follows: S1: Steam, fuel gas and primary combustion air are mixed and burned in the burner to form a high-temperature flue gas mass. The amount of primary combustion air is 80-90% of the amount of air required for complete combustion of the fuel gas. S2: The secondary combustion air enters the furnace and mixes evenly with the burning high-temperature smoke mass. The amount of secondary combustion air is 30% to 50% of the amount of air required for complete combustion of the fuel gas. S3: The tertiary combustion air and sulfur tail gas enter the furnace body for mixed combustion. The amount of tertiary combustion air is required to meet the air volume required for the incineration of sulfur tail gas, and is adjusted based on the oxygen content of 3% in the flue gas discharged from the furnace body.

[0006] In some embodiments of the present invention, the steam, fuel gas and primary combustion air in S1 are mixed directly or indirectly; The direct mixing method is that steam and fuel gas are evenly mixed and then sprayed out from the fuel gas spray gun to mix with the primary combustion air for combustion; In the indirect mixing method, steam is sprayed from a steam spray gun, fuel gas is sprayed from a fuel gas spray gun, and the steam, fuel gas and swirling air inside the air cyclone are mixed and burned; In the direct mixing method and the indirect mixing method, the ratio of steam to fuel gas is 0.2-0.6:1.

[0007] In some embodiments of the present invention, the steam is input into the burner in a dual-channel manner, the first channel inputs steam in the indirect mixing method or the direct mixing method, and the steam in the second channel is injected into the burner after being injected into the primary combustion air, and the ratio of steam to primary combustion air in the second channel is 0.02~0.04:1.

[0008] The present invention also provides a sulfur tail gas treatment equipment with low nitrogen oxide emissions, including a burner and a furnace body. The burner is arranged at the front end of the furnace body. The burner includes a fuel gas spray gun, a first-level combustion air collecting box, an air cyclone and a combustion fire channel. The fuel gas spray gun is composed of a fuel gas inlet, a fuel gas gun body and a fuel gas nozzle. A radiation protection cone is provided at the front end of the fuel gas nozzle. The fuel gas spray gun is slidably installed in the center of the burner. The first-level combustion air collecting box is sleeved on the outer ring of the fuel gas spray gun. A first-level combustion air inlet is provided on the first-level combustion air collecting box. The air cyclone is arranged inside the first-level combustion air collecting box. The combustion fire channel is arranged at the rear end of the first-level combustion air collecting box.

[0009] In some embodiments of the present invention, the furnace body includes a conical portion and a circular portion, the circular portion is arranged at the rear end of the conical portion, the outer circle of the conical portion is provided with the secondary combustion air collecting box, the secondary combustion air collecting box is provided with a secondary combustion air inlet, the secondary combustion air collecting box is connected to the conical portion through a plurality of secondary combustion air nozzles, the secondary combustion air nozzles are arranged around the conical portion, and the secondary combustion air nozzles form an angle of 30°~60° with the axis of the furnace body.

[0010] In some embodiments of the present invention, a three-stage combustion air collecting box and an exhaust gas collecting box are provided on the outer circle of the circular body, an exhaust port is provided at the rear end of the circular body, and the exhaust gas collecting box is provided at the rear end of the three-stage combustion air collecting box. The three-stage combustion air collecting box and the exhaust gas collecting box are respectively provided with a three-stage combustion air inlet and an exhaust gas inlet, and the three-stage combustion air collecting box and the exhaust gas collecting box are respectively connected to the circular body through a plurality of three-stage combustion air nozzles and exhaust nozzles.

[0011] In some embodiments of the present invention, a steam inlet is provided on the fuel gas spray gun, and the steam is mixed with the fuel gas inside the fuel gas spray gun body and then sprayed out from the fuel gas spray head.

[0012] In some embodiments of the present invention, a steam spray gun is provided inside the burner, and the steam spray gun is coaxially arranged with the fuel gas spray gun at the center of the burner. The steam spray gun consists of a steam inlet, a steam gun body and a steam spray head. The steam spray gun is arranged inside the fuel gas spray gun, and the fuel gas spray gun is wrapped around the outside of the steam spray gun.

[0013] In some embodiments of the present invention, a second steam inlet is provided on the side of the primary combustion air collecting box, and the steam is mixed with the primary combustion air inside the primary combustion air collecting box and then enters the burner.

[0014] In some embodiments of the present invention, an air intake control system is provided outside the burner, and the air intake control system is used to control the amount of gas discharged from the first-stage combustion air collecting box, the second-stage combustion air collecting box, the third-stage combustion air collecting box, and the exhaust gas collecting box into the burner and the furnace body.

[0015] (III) Beneficial effects It can be seen from the above technical solution that the present invention has at least one of the following beneficial effects: The steam of the present invention is delivered to the interior of the burner through a dual channel, and the hydrocarbons in the fuel react with the water vapor under high temperature conditions to generate reducing gas, thereby inhibiting the generation of thermal nitrogen oxides. The steam in the second channel is injected into the primary combustion-supporting air, and the oxygen concentration in the mixture of the steam and the first combustion-supporting air is further reduced. The low oxygen partial pressure can further reduce the probability of high-temperature reaction of nitrogen in the air to generate nitrogen oxides.

[0016] The first-level combustion-supporting air of the present invention satisfies the sub-equivalent combustion of the fuel gas combustion. The oxygen in the first-level combustion-supporting air reacts with C and H in the fuel gas under an oxygen-deficient environment to generate reducing gases CO and H2, and inhibits the N2 in the first-level combustion-supporting air from reacting with O2 under high temperature conditions to generate nitrogen oxides; the second-level combustion-supporting air is added in the rear area of ​​the fuel gas combustion, and the second-level combustion-supporting air is used as a supplement to the first-level combustion-supporting air to meet the full combustion of the fuel, ensure the full reaction of the fuel, and avoid the incomplete combustion of the fuel to generate a large amount of CO; the tertiary combustion-supporting air is mixed with the sulfur tail gas in the furnace, and the toxic and harmful components in the sulfur tail gas are oxidized and decomposed under peroxygen conditions. The first-level combustion-supporting air, the second-level combustion-supporting air, the tertiary combustion-supporting air and the sulfur tail gas of the present invention are all controlled by the air intake control system in linkage, so the present invention can be applied to different types of sulfur tail gas treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The figure is a schematic diagram of a sulfur tail gas treatment process with low nitrogen oxide emissions.

[0018] Figure 2 The figure is a schematic diagram of the structure of a sulfur tail gas treatment equipment with low nitrogen oxide emissions.

[0019] Figure 3 Schematic diagram of the components for direct mixing of steam, fuel gas and primary combustion air.

[0020] Figure 4 Schematic diagram of the components for indirect mixing of steam, fuel gas and primary combustion air.

[0021] Figure 5 Schematic diagram of the dual-channel steam input component.

[0022] Figure 6 It is a schematic diagram of the cross section of the cone and the secondary combustion air nozzle.

[0023] [Description of the main components of the present invention] 1. Fuel gas spray gun; 2. Primary combustion air collecting box; 3. Air cyclone; 4. Combustion fire channel; 5. Radiation protection cone; 6. Primary combustion air inlet; 7. Conical body; 8. Round body; 9. Secondary combustion air collecting box; 10. Secondary combustion air inlet; 11. Secondary combustion air nozzle; 12. Third-level combustion air collecting box; 13. Exhaust gas collecting box; 14. Third-level combustion air inlet; 15. Exhaust gas inlet; 16. Third-level combustion air nozzle; 17. Exhaust gas nozzle; 18. Steam inlet; 19. Steam spray gun; 20. Second steam inlet; 1-1. Fuel gas inlet; 1-2. Fuel gas gun body; 1-3. Fuel gas nozzle. DETAILED DESCRIPTION

[0024] The present invention provides a sulfur tail gas treatment process with low nitrogen oxide emission and a treatment device thereof. In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. Specific embodiments Example

[0025] like Figure 1 As shown, the present invention provides a sulfur tail gas treatment process with low nitrogen oxide emission, the steps are as follows: S1: Steam, fuel gas and primary combustion air are mixed and burned in the burner to form a high-temperature flue gas mass. The amount of primary combustion air is 80-90% of the amount of air required for complete combustion of the fuel gas. S2: The secondary combustion air enters the furnace and mixes evenly with the burning high-temperature smoke mass. The amount of secondary combustion air is 30% to 50% of the amount of air required for complete combustion of the fuel gas. S3: The tertiary combustion air and sulfur tail gas enter the furnace body for mixed combustion. The amount of tertiary combustion air is required to meet the air volume required for the incineration of sulfur tail gas, and is adjusted based on the oxygen content of 3% in the flue gas discharged from the furnace body.

[0026] In step S1, steam and fuel gas are fully mixed and burned, and hydrocarbons and water in the fuel gas react to form a synthesis gas under high temperature conditions. The chemical equation is: CH4+H2O→CO+3H2, △H=+206.1KJ / mol, and the reaction is an endothermic reaction. The carbon monoxide and hydrogen in the combustion products are highly reducing, and more than 95% of the nitrogen oxides are nitrogen monoxide. The chemical equation is: 2CO+2NO→2CO2+N2, △H=+756KJ / mol. The reaction is an endothermic reaction. Hydrogen also reacts with nitrogen oxides under high temperature conditions to produce nitrogen and water. The chemical equation is: 2H2+2NO→2H2O+N2△H=+198KJ / mol. The reaction is an endothermic reaction.

[0027] The addition of water vapor can produce a large amount of hydrogen and carbon dioxide through reaction, and the reducing atmosphere is enhanced, which is conducive to the occurrence of nitric oxide reduction reaction. At the same time, the H and OH free radicals generated by the dissociation of water vapor can inhibit the oxidation of HCN to nitric oxide, and their combined effect reduces the amount of nitric oxide generated. Steam and hydrocarbons generate a reducing atmosphere under high temperature conditions, further reducing the NO produced by combustion to N2, which is the main role of steam in reducing nitrogen and nitrogen oxide emissions. Secondly, steam also has a certain cooling effect on the flame temperature. It has a positive effect on reducing thermal nitrogen oxides.

[0028] In said S1, the steam, fuel gas and primary combustion air are mixed directly or indirectly; The direct mixing method is that steam and fuel gas are evenly mixed and then sprayed out from the fuel gas spray gun to mix with the primary combustion air for combustion; In the indirect mixing method, steam is sprayed from a steam spray gun, fuel gas is sprayed from a fuel gas spray gun, and the steam, fuel gas and swirling air inside the air cyclone are mixed and burned; In the direct mixing method and the indirect mixing method, the ratio of steam to fuel gas is 0.2-0.6:1.

[0029] Steam is input into the burner in a dual-channel manner. The first channel uses the above-mentioned indirect mixing method or direct mixing method to input steam. The steam in the second channel is injected into the primary combustion air and then input into the burner. The oxygen concentration in the mixture of steam and the primary combustion air is further reduced. The low oxygen partial pressure can further reduce the probability of high-temperature reaction of N2 in the air to generate nitrogen oxides. The ratio of steam to primary combustion air in the second channel is 0.02~0.04:1.

[0030] like Figure 2-6 As shown, the present invention also provides a sulfur tail gas treatment equipment with low nitrogen oxide emission, including a burner and a furnace body, wherein the burner is arranged at the front end of the furnace body, the burner includes a fuel gas spray gun 1, a primary combustion air collecting box 2, an air cyclone 3 and a combustion fire channel 4, the fuel gas spray gun 1 is composed of a fuel gas inlet 1-1, a fuel gas gun body 1-2 and a fuel gas nozzle 1-3, a radiation-proof cone 5 is provided at the front end of the fuel gas nozzle 1-3, the fuel gas spray gun 1 is slidably installed in the center of the burner, the primary combustion air collecting box 2 is sleeved on the outer ring of the fuel gas spray gun 1, the primary combustion air collecting box 2 is provided with a primary combustion air inlet 6, the air cyclone 3 is arranged inside the primary combustion air collecting box 2, and the combustion fire channel 4 is arranged at the rear end of the primary combustion air collecting box 2; The furnace body comprises a cone portion 7 and a round portion 8, wherein the round portion 8 is arranged at the rear end of the cone portion 7, and the outer ring of the cone portion 7 is provided with the secondary combustion air collecting box 9, and the secondary combustion air collecting box 9 is provided with a secondary combustion air inlet 10, and the secondary combustion air collecting box 9 is connected to the cone portion 7 through a plurality of secondary combustion air nozzles 11, and the secondary combustion air nozzles 11 are arranged around the cone portion 7, and the secondary combustion air nozzles 11 form an angle β with the axis of the furnace body, and the range of the angle β is 30°~60°; The outer ring of the circular body 8 is provided with a three-stage combustion air collecting box 12 and an exhaust gas collecting box 13, the rear end of the circular body 8 is provided with an exhaust port, the exhaust gas collecting box 13 is arranged at the rear end of the three-stage combustion air collecting box 12, the three-stage combustion air collecting box 12 and the exhaust gas collecting box 13 are respectively provided with a three-stage combustion air inlet 14 and an exhaust gas inlet 15, the three-stage combustion air collecting box 12 and the exhaust gas collecting box 13 are respectively connected to the circular body 8 through a plurality of three-stage combustion air nozzles 16 and an exhaust nozzle 17; The steam, fuel gas and primary combustion air mixing component structures of the present invention are provided with three types, namely: The first type: the fuel gas spray gun 1 is provided with a steam inlet 18, and the steam is mixed with the fuel gas inside the fuel gas gun body 1-2 and then sprayed out from the fuel gas nozzle 1-3; The second type: a steam spray gun 19 is provided inside the burner, and the steam spray gun 19 is coaxially arranged with the fuel gas spray gun 1 at the center of the burner. The steam spray gun 19 consists of a steam inlet, a steam gun body and a steam nozzle. The steam spray gun 19 is arranged inside the fuel gas spray gun 1, and the fuel gas spray gun 1 is wrapped around the outside of the steam spray gun 19.

[0031] The third type: the first steam channel is any one of the above two structures, and the second channel is a second steam inlet 20 arranged on the side of the first-level combustion air collecting box 2. The steam is mixed with the first-level combustion air inside the first-level combustion air collecting box 2 and then enters the burner.

[0032] An air intake control system is provided outside the burner, and the air intake control system is used to control the amount of gas discharged from the first-stage combustion air collecting box 2, the second-stage combustion air collecting box 9, the third-stage combustion air collecting box 12, and the exhaust gas collecting box 13 into the burner and the furnace body.

[0033] So far, the present embodiment has been described in detail with reference to the accompanying drawings. Based on the above description, those skilled in the art should have a clear understanding of the present invention.

[0034] It should be noted that the implementation methods not shown or described in the drawings or the text of the specification are all forms known to ordinary technicians in the relevant technical field and are not described in detail. In addition, the above definitions of each element and method are not limited to the various specific structures, shapes or methods mentioned in the embodiments.

[0035] It should also be noted that this document may provide demonstrations of parameters containing specific values, but these parameters do not need to be exactly equal to the corresponding values, but can be approximated to the corresponding values ​​within an acceptable error tolerance or design constraint. The directional terms mentioned in the embodiments, such as "up", "down", "front", "back", "left", "right", etc., are only reference directions of the accompanying drawings and are not intended to limit the scope of protection of the present invention. In addition, unless the steps are specifically described or must occur in sequence, the order of the above steps is not limited to those listed above, and can be changed or rearranged according to the desired design. And the above embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, the technical features in different embodiments can be freely combined to form more embodiments.

[0036] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A sulfur tail gas treatment process with low nitrogen oxide emission, characterized in that: Here are the steps: S1: Steam, fuel gas and primary combustion air are mixed and burned in the burner to form a high-temperature flue gas mass. The amount of primary combustion air is 80-90% of the amount of air required for complete combustion of the fuel gas. S2: The secondary combustion air enters the furnace and mixes evenly with the burning high-temperature smoke mass. The amount of secondary combustion air is 30% to 50% of the amount of air required for complete combustion of the fuel gas. S3: The tertiary combustion air and sulfur tail gas enter the furnace body for mixed combustion. The amount of tertiary combustion air is required to meet the air volume required for the incineration of sulfur tail gas, and is adjusted based on the oxygen content of 3% in the flue gas discharged from the furnace body.

2. A sulfur tail gas treatment process with low nitrogen oxide emission according to claim 1, characterized in that: In said S1, the steam, fuel gas and primary combustion air are mixed directly or indirectly; The direct mixing method is that steam and fuel gas are evenly mixed and then sprayed out from the fuel gas spray gun to mix with the primary combustion air for combustion; In the indirect mixing method, steam is sprayed from a steam spray gun, fuel gas is sprayed from a fuel gas spray gun, and the steam, fuel gas and swirling air inside the air cyclone are mixed and burned; In the direct mixing method and the indirect mixing method, the ratio of steam to fuel gas is 0.2-0.6:

1.

3. A sulfur tail gas treatment process with low nitrogen oxide emission according to claim 2, characterized in that: The steam is input into the burner in a dual-channel manner, the first channel inputs steam in the indirect mixing manner or the direct mixing manner, and the steam in the second channel is injected into the primary combustion air and then input into the burner, and the ratio of steam to primary combustion air in the second channel is 0.02~0.04:

1.

4. A sulfur tail gas treatment equipment with low nitrogen oxide emission, characterized in that: It includes a burner and a furnace body. The burner is arranged at the front end of the furnace body. The burner includes a fuel gas spray gun, a first-level combustion air collecting box, an air cyclone and a combustion fire channel. The fuel gas spray gun is composed of a fuel gas inlet, a fuel gas gun body and a fuel gas nozzle. A radiation protection cone is provided at the front end of the fuel gas nozzle. The fuel gas spray gun is slidably installed in the center of the burner. The first-level combustion air collecting box is sleeved on the outer ring of the fuel gas spray gun. A first-level combustion air inlet is provided on the first-level combustion air collecting box. The air cyclone is arranged inside the first-level combustion air collecting box. The combustion fire channel is arranged at the rear end of the first-level combustion air collecting box.

5. The sulfur tail gas treatment equipment with low nitrogen oxide emission according to claim 4 is characterized in that: The furnace body includes a conical portion and a circular portion, the circular portion is arranged at the rear end of the conical portion, the outer circle of the conical portion is provided with the secondary combustion air collecting box, the secondary combustion air collecting box is provided with a secondary combustion air inlet, the secondary combustion air collecting box is connected to the conical portion through a plurality of secondary combustion air nozzles, the secondary combustion air nozzles are arranged around the conical portion, and the secondary combustion air nozzles form an angle of 30°~60° with the axis of the furnace body.

6. The sulfur tail gas treatment equipment with low nitrogen oxide emission according to claim 5, characterized in that: The outer circle of the circular body is provided with a three-stage combustion air collecting box and an exhaust gas collecting box, the rear end of the circular body is provided with an exhaust port, the exhaust gas collecting box is arranged at the rear end of the three-stage combustion air collecting box, the three-stage combustion air collecting box and the exhaust gas collecting box are respectively provided with a three-stage combustion air inlet and an exhaust gas inlet, the three-stage combustion air collecting box and the exhaust gas collecting box are respectively connected to the circular body through a plurality of three-stage combustion air nozzles and exhaust nozzles.

7. The sulfur tail gas treatment equipment with low nitrogen oxide emission according to claim 6 is characterized in that: The fuel gas spray gun is provided with a steam inlet, and the steam is mixed with the fuel gas inside the fuel gas spray gun body and then sprayed out from the fuel gas spray head.

8. The sulfur tail gas treatment equipment with low nitrogen oxide emission according to claim 6, characterized in that: A steam spray gun is provided inside the burner. The steam spray gun is coaxially arranged with the fuel gas spray gun at the center of the burner. The steam spray gun consists of a steam inlet, a steam gun body and a steam spray head. The steam spray gun is arranged inside the fuel gas spray gun, and the fuel gas spray gun is wrapped around the outside of the steam spray gun.

9. A sulfur tail gas treatment equipment with low nitrogen oxide emission according to claim 7 or 8, characterized in that: A second steam inlet is arranged on the side of the primary combustion air collecting box, and the steam is mixed with the primary combustion air inside the primary combustion air collecting box and then enters the burner.

10. The sulfur tail gas treatment equipment with low nitrogen oxide emission according to claim 9, characterized in that: An air intake control system is provided outside the burner, and the air intake control system is used to control the amount of gas discharged from the first-stage combustion air collecting box, the second-stage combustion air collecting box, the third-stage combustion air collecting box, and the tail gas collecting box into the burner and the furnace body.

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