CN113716530A

CN113716530A - H containing ammonia2Preparation of low-content NO from S acid gasxSulfuric acid incinerator and method

Info

Publication number: CN113716530A
Application number: CN202111097033.9A
Authority: CN
Inventors: 王阳; 高学顺; 胡耀峰; 荆开石; 洪鹏; 张宏科; 吴雪峰; 华卫琦
Original assignee: Wanhua Chemical Group Co Ltd; Wanhua Chemical Fujian Co Ltd
Current assignee: Wanhua Chemical Group Co Ltd; Wanhua Chemical Fujian Co Ltd
Priority date: 2021-09-18
Filing date: 2021-09-18
Publication date: 2021-11-30
Anticipated expiration: 2041-09-18
Also published as: CN113716530B

Abstract

The invention relates to an ammonia-containing H₂Preparation of low-content NO from S acid gas_xIncinerator and process for sulfuric acid comprising H containing ammonia₂S acid gas, air and fuel gas are burnt in a sulfur recovery incinerator to prepare sulfuric acid, and part of tail gas for preparing sulfuric acid is back-mixed to the incinerator for circular combustion, SO that the acid gas is fully combusted in three stages at 830-1000 ℃, and the tail gas is back-mixed in a grading manner, SO that hydrogen sulfide is fully combusted and converted into SO₂，SO₂Further converted into SO₃And sulfuric acid. Sulfuric acid, tail gas NO prepared by the device and method of the invention_xThe content is less than 20mg/Nm³NO in sulfuric acid_x ^‑Less than 10ppm and no NH₄ ⁺The quality of the sulfur is consistent with that of chlorine gas for drying and the sulfur for nitrobenzeneAcid requirement, and the preparation method is safe and environment-friendly.

Description

H containing ammonia2Preparation of low-content NO from S acid gasxSulfuric acid incinerator and method

Technical Field

The invention relates to the technical field of synthesis gas acid gas recovery, in particular to ammonia-containing H₂An incinerator and a method for preparing low-NOx sulfuric acid from S acid gas.

Background

In the fields of petrochemical industry, natural gas chemical industry and coal chemical industry, because the raw materials contain sulfur, H can be generated in the process of processing the raw materials to produce high-added-value products₂S, forming a gas containing H₂Acid gas of S. Due to H₂S is toxic, flammable and explosive, cannot be directly discharged and must be recycled. In particular, in the gasification process using coal as a raw material, nitrogen is converted into ammonia and enters tail gas along with hydrogen sulfide because the coal contains nitrogen elements.

The current treatment means of the acid gas containing hydrogen sulfide mainly comprises incineration of sulfur and incineration of sulfuric acid for resource recovery treatment. Incinerator feeding material for preparing sulfuric acid by taking hydrogen sulfide acid gas as raw material to remove H₂Besides the acid gas and air of S, fuel gas is also needed to be supplemented. For example, CN108675271A discloses₂And (2) fully mixing the acid gas, the fuel gas and the air, and combusting the mixed process gas at 900-1000 ℃ to ensure that the hydrogen sulfide is fully combusted and completely converted into sulfur dioxide, and further converting the sulfur dioxide in the flue gas into sulfuric acid. The method can effectively reduce H₂The cost consumption of the sulfuric acid prepared by the acid gas wet method is reduced, the generation of water in the combustion process is reduced, the concentration of the sulfuric acid can be effectively increased to more than 98.5 wt%, but the influence of the existence of ammonia on the product performance and the application of the prepared sulfuric acid is not disclosed.

The synthesis gas prepared by taking coal as raw material has the ammonia content as high as 300-600mg/Nm because a large amount of ammonia enters hydrogen sulfide acid gas³The part of ammonia enters the incinerator for producing the sulfuric acid and has a large amount of NO_xGeneration of NO in the exhaust gas_xThe content exceeds 100mg/Nm³With NO in sulphuric acid_x ^-More than 50 ppmw.

Sulfuric acid is an important industrial raw material, can be used for manufacturing fertilizers, medicines, explosives, pigments, detergents, storage batteries and the like, and is also widely applied to industries of purifying petroleum, metal smelting, dyes and the like. In addition, sulfuric acid is frequently used as a dehydrating agent because it has a strong water-absorbing property. In the field of chlorine drying, sulfuric acid is mainly used as a drying agent for chlorine drying because chlorine has water absorption and reacts when meeting a conventional alkaline drying agent. For example, sulfuric acid contains ammonia, and the ammonia reacts with chlorine gas to generate NCl₃The risk of explosive compounds. The current sulfuric acid for chlorine drying requires less than 5ppmw ammonia in sulfuric acid.

Sulfuric acid can be used as catalyst and water absorbent in the process of preparing nitrobenzene by nitration of benzene, such as NO in sulfuric acid_x ^-In an amount of more than 20ppmw, NO_x ^-Will react with benzene to form alkane and CO₂The bubble amount in the oil-water separator after the nitration reaction is increased, the content of sulfuric acid in nitrobenzene is increased due to uneven layering of nitrobenzene and sulfuric acid, and meanwhile, the liquid level of the liquid tank is difficult to control, so that the process stability is influenced.

Therefore, when the acid gas containing ammonia hydrogen sulfide is used for preparing sulfuric acid, NO in tail gas needs to be controlled_xAnd simultaneously controlling NH in sulfuric acid₄ ⁺Content and NO_x ^-Content, but how to control the prior art does not give a good solution. When the sulfuric acid is prepared from the ammonia-containing acidic gas at present, if tail gas is not controlled, the tail gas and NO in the sulfuric acid_xThe content will exceed the standard and does not meet the use requirement of the benzene nitration reaction; e.g. control of NO in exhaust gases_xThe main means in the industry at present is to arrange SCR behind an incinerator, but the SCR has the problem of ammonia escape, so that the ammonia content in sulfuric acid is more than 5ppmw, and the sulfuric acid does not meet the use requirement of chlorine drying.

Patent CN103626136A describes a process for preparing sulfuric acid by using a peroxide combustion technique, but the control requirement of the process for the oxygen content is high, and the existence of peroxide can cause the incineration temperature to be too high, and NO exists_xA problem of mass production.

Patent CN108793090A describes a method for preparing sulfuric acid from hydrogen sulfide in coal gas, and proposes to increase SCR denitration at an outlet of an incinerator, wherein ammonia escapes, and ammonia enters sulfuric acid to cause NH in the sulfuric acid₄ ⁺The content is high.

Patent CN111033124A describes a gas refining system containing tail gas such as hydrogen sulfide and ammonia, and proposes a way of partial reduction combustion in a three-stage incinerator, and a way of combustion at high temperature, so as to realize less NO production_x(ii) a However, the temperature of the front two-stage burning part of the burning furnace is up to 1250-₃And O₂The reaction is intensified to generate thermal NO_xIs not favorable to tail gas NO_xAnd (4) controlling.

Thus, there is still a need for a viable solution to the problem of converting ammonia-containing H₂Preparation of low-content NO from S acid gas_xSulfuric acid, and NO in sulfuric acid_x ^-And NH₄ ⁺Low content and quality meeting the requirements of chlorine drying and sulfuric acid for nitrobenzene.

Disclosure of Invention

Aims to solve the problem that ammonia can be converted into NO in the process of preparing sulfuric acid from ammonia-containing hydrogen sulfide acidic gas_xResulting in exhaust gas NO_xExcess and NO in sulfuric acid_x ^-High content of NH in sulfuric acid, and the treatment of incinerator tail gas by SCR₄ ⁺High problem, provides an incinerator suitable for directly preparing sulfuric acid from ammonia-containing hydrogen sulfide acid gas.

It is still another object of the present invention to provide an incinerator for incinerating H containing ammonia₂Preparation of low-content NO from S acid gas_xMethod for preparing sulfuric acid, NO in tail gas from sulfuric acid preparation_xThe content is less than 20mg/Nm³NO in sulfuric acid_x ^-Less than 10ppmw and no NH₄ ⁺。

In order to achieve the above purpose, the invention adopts the following technical scheme:

h containing ammonia₂Preparation of low-content NO from S acid gas_xAn incinerator for sulfuric acid, the incinerator is a three-stage incinerator, each timeThe two-stage incinerator is provided with a throttling wall, the first-stage incinerator is provided with a first-stage incinerator air inlet at one end far away from the second-stage incinerator, the second-stage incinerator top is provided with a second-stage incinerator air inlet, the third-stage incinerator top is provided with a third-stage incinerator air inlet and one end far away from the second-stage incinerator is provided with a tail gas outlet, and the tail gas outlet is respectively connected with the first-stage incinerator air inlet and the second-stage incinerator air inlet.

In a specific embodiment, the air inlet of the first-stage incinerator is used for premixing raw materials through a nozzle and then feeding the premixed raw materials into the incinerator, and the nozzle is a four-channel nozzle which is concentrically distributed in a circular ring shape from inside to outside.

In a specific embodiment, the throttling wall between the first-stage incinerator and the second-stage incinerator is a circular wall, and an annular gap is formed between the throttling wall and the incinerator cavity; preferably, the annular gap has a size of 50-100mm, preferably 50-70 mm.

In a specific embodiment, the throttle wall between the second-stage incinerator and the third-stage incinerator is a circular wall with apertures in the form of fan blades; preferably, the circumscribed circle diameter of the fan blade shape is 200-.

In another aspect, an ammonia-containing H₂Preparation of low-content NO from S acid gas_xProcess for sulfuric acid comprising reacting H containing ammonia₂S acid gas as raw material, incinerating the same in the incinerator of any one of claims 1 to 4 to make H containing ammonia₂Partial oxidation of ammonia in S-acid gas to N₂、H₂S is fully combusted and completely converted into SO₂，SO₂Further converted into SO₃Followed by a step of preparing sulfuric acid.

In a specific embodiment, the ammonia-containing H₂The ammonia content in the S acid gas is 300-600mg/Nm³(ii) a Preferably, NO is present in the tail gas from the production of sulphuric acid_xThe content is less than 20mg/Nm³NO in sulfuric acid_x ^-Less than 10ppmw and no NH₄ ⁺。

In a specific embodimentIn the first stage incinerator, the feed gas fed through the gas inlet of the first stage incinerator comprises H containing ammonia₂S acid gas, air, fuel gas and part of back-mixed tail gas after sulfuric acid is prepared at an outlet of an incinerator; preferably, the feeding mixing mode of the first-stage incinerator is four-channel nozzle premixing type mixing, and the materials conveyed in the four channels from inside to outside of the four-channel nozzle are fuel gas, air and acid gas respectively, and part of back-mixed tail gas after sulfuric acid is prepared at the outlet of the incinerator.

In a specific embodiment, the mixture of part of the back-mixed tail gas and air after the sulfuric acid is prepared at the outlet of the incinerator enters the second-stage incinerator through the air inlet of the second-stage incinerator; air enters the third-stage incinerator through the air inlet of the third-stage incinerator.

In a particular embodiment, the H containing ammonia entering the incinerator₂The total volume ratio of the acid gas, the air and the part of the back-mixed tail gas and the fuel gas after the sulfuric acid is prepared at the outlet of the incinerator is 1: 5-10: 0.1-0.3: 0.1 to 0.3, preferably 1: 6-8: 0.2-0.3: 0.2-0.3.

In a specific embodiment, the volume ratio of the part of the back-mixed tail gas after the sulfuric acid is prepared at the outlet of the incinerator in the three-stage incinerator is 0.6-0.8: 0.2-0.3: 0.1-0.2, preferably 0.6-0.7: 0.2-0.3: 0.1.

in a specific embodiment, the volume ratio of the air in the tertiary incinerator is 0.5-0.8: 0.1-0.3: 0.1-0.2, preferably 0.6-0.8: 0.1-0.2: 0.1-0.2.

In a specific embodiment, the temperature of the three-stage incinerator is 830-900 ℃, 850-950 ℃ and 900-1000 ℃.

Compared with the prior art, the invention has the following two advantages:

1) the incinerator of the invention provides H suitable for high ammonia content₂S the raw material gas mixing burner for preparing sulfuric acid from acid gas realizes partial incineration reaction of acid gas, fuel gas and air in a reducing atmosphere through the burner and air inflow control, and then the acid gas, the fuel gas and the air are subjected to incineration reaction in the reducing atmosphere in a first-stage incinerator together with back-mixed tail gas, and the reaction temperature is maintained at 830-NH in acid gas at 900 deg.C₃Conversion of generated thermal NO_xLow production and NO in back-mixed tail gas_xWith NH in the raw acid gas₃At the temperature, the SNCR reaction to generate N₂Reduction of NH₃Further generation of NO in fuel form_xThereby effectively reducing NO in the final sulfuric acid_x ^-Content and NH₄ ⁺And (4) content.

2) The invention provides a method for preparing H suitable for high ammonia content₂The acid gas of each stage of incinerator, the back-mixed tail gas and air can be axially and radially mixed at molecular level by an incineration method of air graded incineration and tail gas partial back mixing in a three-stage incinerator and a four-channel nozzle and a throttle wall with a unique structure, the mixed combustion effect is enhanced, and unburned NH can be realized₃With NO_xSNCR reaction occurs to reduce thermal NO_xAnd (4) generating. Finally realizing NO in the prepared sulfuric acid tail gas_xThe content is less than 20mg/Nm³NO in sulfuric acid_x ^-Less than 10ppmw and no NH₄ ⁺The method meets the requirements of chlorine drying and sulfuric acid for nitrobenzene, and the whole process flow is safe and environment-friendly.

Drawings

FIG. 1 shows the process of the present invention for producing ammonia-containing H₂Preparation of low-content NO from S acid gas_xThe structure of the sulfuric acid incinerator is shown schematically.

FIG. 2 is a schematic view of the feed nozzle structure of the first stage incinerator.

Fig. 3 is a sectional view of a throttle wall between a first-stage incinerator and a second-stage incinerator.

Fig. 4 is a sectional view of a throttle wall between the second-stage incinerator and the third-stage incinerator.

Wherein, 1 is an incinerator, 2-a first-stage incinerator, 3-a second-stage incinerator, 4-a third-stage incinerator, 5-a first throttling wall, 6-a second throttling wall, 7-a first-stage incinerator air inlet, 8-a four-channel nozzle, 9-a second-stage incinerator air inlet, 10-a third-stage incinerator air inlet, 11-a tail gas air outlet, 12-a sulfuric acid preparation unit, 13-a back-mixing tail gas pipeline and 14-tail gas.

Detailed Description

The following examples will further illustrate the methods provided by the present invention, but the present invention includes but is not limited to the examples listed, and shall include any other known variations within the scope of the claims of the present invention.

As shown in fig. 1, the incinerator 1 of the present invention is a horizontal tube type incinerator, which is a three-stage incinerator having three divided internal spaces, corresponding to a first-stage incinerator 2, a second-stage incinerator 3, and a third-stage incinerator 4, wherein the first-stage incinerator 2 and the second-stage incinerator 3 are separated by a first throttle wall 5, and the second-stage incinerator 3 and the third-stage incinerator 4 are separated by a second throttle wall 6. The three-stage incinerators are, for example, space-reduced stepwise, and the first-stage incinerator is space-maximized, but not limited thereto. Wherein, the first level burns burning furnace 2 and is equipped with first level and burns burning furnace air inlet 7 in the one end of keeping away from second level and burns burning furnace 3, and the top of second level and burns burning furnace air inlet 9 is equipped with the second level, and the top of third level burning furnace 4 is equipped with third level and burns burning furnace air inlet 10 and the one end of keeping away from the second level and burn burning furnace and be equipped with tail gas outlet 11, tail gas outlet 11 respectively with first level burn burning furnace air inlet 7 and second level and burn burning furnace air inlet 9 and link to each other.

In the description of the present invention, it should be noted that the terms "one end", "top", "horizontal", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In addition, the gas inlet 7 of the first-stage incinerator mixes the raw gas in advance through a nozzle and then feeds the raw gas into the incinerator, the nozzle is a four-channel nozzle 8 which is a premixing type mixing nozzle and is distributed in a concentric circular ring shape from inside to outside, the structural schematic diagram is shown in fig. 2, and materials (hereinafter referred to as raw gas) conveyed in the four channels from inside to outside of the four-channel nozzle 8 are fuel gas, air, acid gas and part of back-mixed tail gas after sulfuric acid is prepared at the outlet of the incinerator respectively. Wherein the fuel gas is, for example, but not limited to, natural gas; the acid gas is H containing ammonia₂S acid gases, e.g. H from petrochemical, natural gas and coal industries₂S acid gas, especially H containing ammonia formed by coal gasification process₂And S acid gas. It will be appreciated by those skilled in the art that the primary incinerator inlet 7 comprises four separate inlet lines for fuel gas, air, acid gas and back-mixed tail gas, which are in communication with the four channels of the four-channel nozzle 8. The four-channel nozzle 8 extends into the incinerator partially, the premixed raw material gas is sent into the incinerator for incineration, inevitably, the contact part of the acid gas, the fuel gas and the air at the outlet of the four-channel nozzle 8 can be burnt, and then the combustion is continued along with the back-mixed tail gas.

In the first-stage incinerator, the fuel gas and air are incinerated in the acid gas channel to provide fuel temperature, and the mixed gas of the fuel gas and the air further reacts with the acid gas to further ensure H₂S combustion effect, after the three components are subjected to partial incineration reaction in a reducing atmosphere, the three components and the back-mixed tail gas sprayed out from the fourth channel are subjected to incineration reaction in the reducing atmosphere in the first-stage incinerator together, the reaction temperature is maintained at 830-900 ℃, and NH in the acid gas at the temperature₃Conversion of generated thermal NO_xLow production and NO in back-mixed tail gas_xIn raw acid gasNH of (2)₃At the temperature, the SNCR reaction to generate N₂Reduction of NH₃Further generation of NO in fuel form_x。

As shown in fig. 3, the first throttling wall 5 between the first-stage incinerator 2 and the second-stage incinerator 3 is a circular wall, and the circular throttling wall is connected to the incinerators to divide the internal space of the incinerators into the first incinerator 2 and the second-stage incinerator 3. The material of the throttling wall is not limited at all, such as corundum bricks, and the thickness of the throttling wall is not limited at all, such as 500 mm. Wherein, be equipped with the annular gap between throttling wall and the burning furnace cavity casing to the feed gas can get into the second grade through the annular gap and burn after the burning of first grade burning furnace. Preferably, the annular gap has a size of 50-100mm, for example including but not limited to 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, preferably 50-70 mm. The annular gap design between the throttling wall and the incinerator cavity realizes good mixing of acid gas at the outlet of the first-stage incinerator in the axial direction of the second-stage incinerator, and can form a rotational flow field in the first-stage incinerator and the second-stage incinerator, so that the mixing effect of the acid gas and air is enhanced, and the incineration reaction is enhanced.

The acid gas of the first-stage incinerator enters the second-stage incinerator through a throttling wall gap, the back-mixed tail gas and air mixture are sprayed into the incinerator from the top of the second-stage incinerator through a nozzle, radial mixing of the acid gas at the outlet of the second-stage incinerator, the back-mixed tail gas and the air is achieved, molecular-level mixing of the acid gas, the air and the back-mixed tail gas of the second-stage incinerator is achieved through axial mixing and radial mixing, and mixed combustion effect is enhanced. Wherein the temperature of the second-stage incinerator is controlled to be 850-950 ℃, and NH is realized at the temperature₃With NO_xIn the selective non-catalytic reduction reaction, to reduce NO in the exhaust gas_xContent (c); simultaneously, in a second-stage incinerator, H is realized₂And further burning of S.

As shown in FIG. 4, the second throttling wall 6 between the second-stage incinerator 3 and the third-stage incinerator 4 is in the form of a circular wall with apertures in the form of fan blades, forming a swirling flow field to enable the second-stage incinerator to pass through the fan blade-shaped throttling wallThe air which enters the third-stage incinerator through the pores and is sprayed into the incinerator from the top of the third-stage incinerator through the nozzle realizes good mixing at the molecular level, and ensures NH₃Complete conversion of (2). Wherein, the diameter of the circumscribed circle of the fan blade shape is 200-500mm, such as but not limited to 200mm, 250mm, 300mm, 350mm, 400mm, 450mm, 500mm, preferably 300-400 mm. The temperature of the third-stage incinerator is controlled at 900-1000 ℃ to further ensure H₂S acid gas and NH₃And (4) completely combusting.

As shown in figure 1, the method is suitable for preparing low NO by using hydrogen sulfide acidic gas with high ammonia content_x ^-Method for content of sulfuric acid, with H containing ammonia₂S acid gas as raw material is fed into a three-stage incinerator shown in figure 1 for incineration to realize H containing ammonia₂Partial oxidation of ammonia in S-acid gas to N₂、H₂S is totally burnt to SO₂The incinerated process gas is further converted into SO from a tail gas outlet 11 through a sulfuric acid preparation unit 12₃And sulfuric acid, the tail gas part of the tail gas prepared from the sulfuric acid at the tail gas outlet 11 of the incinerator is sent to the gas inlet 7 of the first-stage incinerator to be used as back-mixed tail gas to enter the first-stage incinerator 2 for incineration; part of the tail gas is sent to the air inlet 9 of the second-stage incinerator to be used as back-mixed tail gas to enter the second-stage incinerator 3 to be incinerated; part is sent to the next process via tail gas line 14. Wherein the sulfuric acid preparation unit 12 is a common acid preparation process, and the prior art can be referred to, such as a Monmo acid preparation process, and SO is absorbed from an incinerator₂The process gas is converted into SO by catalytic oxidation₃And the converted gas is further condensed in a condensing tower and concentrated by sulfuric acid, the high-concentration sulfuric acid at the bottom of the condensing tower enters a sulfuric acid product tank, and the gas at the top of the condensing tower is subjected to electrostatic demisting to obtain tail gas. The incinerator equipment comprises three levels of incinerator chambers, and a throttling wall is arranged between every two levels of incinerators. Wherein the first-stage incinerator is a mixed gas incinerator of acid gas, air, back-mixed tail gas and fuel gas; the second-stage incinerator is an incinerator of raw gas, air and back-mixed tail gas from the first-stage incinerator; the third stage is an incinerator in which air is mixed with the raw gas from the second stage incinerator.

Wherein the H containing ammonia is fed to the incinerator₂The volume ratio of the acid gas, air and part of back-mixed tail gas and fuel gas after the sulfuric acid is prepared at the outlet of the incinerator is 1: 5-10: 0.1-0.3: 0.1 to 0.3, preferably 1: 6-8: 0.2-0.3: 0.2 to 0.3; the volume ratio comprises the volume ratio of the total amount of all the gas entering the first-stage incinerator, the second-stage incinerator and the third-stage incinerator, namely the volume of the air comprises the volume of all the air entering the first-stage incinerator, the second-stage incinerator and the third-stage incinerator, and the like. The volume ratio of the back-mixed tail gas in the first-stage, second-stage and third-stage incinerators is 0.6-0.8: 0.2-0.3: 0.1-0.2, preferably 0.6-0.7: 0.2-0.3: 0.1. wherein, the back-mixed tail gas in the third-stage incinerator mainly comes from the incompletely combusted partial tail gas of the first-stage incinerator and the second-stage incinerator. The effect of back-mixing the tail gas is mainly to utilize NO in the back-mixing tail gas_xWith NH in the raw acid gas₃SNCR reaction to N at high temperature₂Further decrease NH₃Further generation of NO in fuel form_xFurther reduce NO emission_xThe amount of (c). The volume ratio of air in the third-stage incinerator is 0.5-0.8: 0.1-0.3: 0.1-0.2, preferably 0.6-0.8: 0.1-0.2: 0.1-0.2; by controlling the content in the first-stage incinerator to be lower than the theoretical amount required by the complete combustion of the acid gas, such as 50% -80% of the theoretical amount, the combustion reaction in the first-stage incinerator under the reducing atmosphere is caused, and the effective reduction of NO in the final sulfuric acid is finally realized by matching with the staged combustion and the control of the gas amount and the components at each stage_x ^-Content and NH₄ ⁺The purpose of content. In the present invention, the residence time of the raw material gas in the incinerator in each of the first, second, and third stages of incinerators is not particularly limited, but is preferably 180s, 120s, and 100s, respectively, for example, but not limited thereto.

By the process of the invention, H containing ammonia₂The ammonia content in the S acid gas exceeds 500mg/Nm³In the sulfuric acid prepared by incineration and preparation of the incinerator and incineration process of the invention, NO is contained in the tail gas after the sulfuric acid is prepared_xThe content is less than 20mg/Nm³NO in sulfuric acid_x ^-Less than 10ppm and no NH₄ ⁺The quality of the product meets the requirements of chlorine gas drying and sulfuric acid for nitrobenzeneThe preparation method is safe and environment-friendly.

The present invention will be further described with reference to the following examples, but the present invention is not limited to the following examples.

Containing H in a device of Wanhua chemistry₂S acid gas as raw material, ammonia content of 300-600mg/Nm³，H₂S content 30% (v), the remainder being CO₂The natural gas is used as fuel gas and is mixed with air in a sulfur recovery incinerator for combustion, and the process gas after combustion is converted and condensed to prepare sulfuric acid.

Example 1

The use of ammonia-containing H as shown in FIG. 1₂S acid gas is used for preparing sulfuric acid, the acid gas, air, fuel gas and back-mixed tail gas are mixed and combusted in a sulfur recovery incinerator, and the combusted process gas is converted and condensed to prepare sulfuric acid. In this embodiment, the total volume ratio of the acid gas, air, back-mixed tail gas and fuel gas mixture is 1: 8: 0.2: 0.3, the proportion of the back-mixed tail gas in the three-stage incinerator is 0.7: 0.2: 0.1, the ratio of air in the three-stage incinerator is 0.8: 0.1: 0.1, the temperature of the three-stage incinerator is 850 ℃, 900 ℃ and 960 ℃, the distance between the first throttling wall and the wall surface of the incinerator is 70mm, the second throttling wall is in a fan shape, and the diameter of the circumscribed circle of the second throttling wall is 400 mm. NO in tail gas_xContent 9mg/Nm³Meets the requirement of environmental protection; NO in sulfuric acid_x ^-The content is 3ppmw, meets the requirement for nitrothiophenic acid, and does not contain NH₄ ⁺And meets the requirement of chlorine gas drying.

Example 2

The use of ammonia-containing H as shown in FIG. 1₂S acid gas is used for preparing sulfuric acid, the acid gas, air, fuel gas and back-mixed tail gas are mixed and combusted in a sulfur recovery incinerator, and the combusted process gas is converted and condensed to prepare sulfuric acid. In this embodiment, the total volume ratio of the acid gas, air, back-mixed tail gas and fuel gas mixture is 1: 5: 0.3: 0.1, the proportion of the back-mixed tail gas in the three-stage incinerator is 0.6: 0.3: 0.1, the ratio of air in the three-stage incinerator is 0.6: 0.2: 0.2, the temperature of the third-stage incinerator is 830 ℃, 850 ℃ and 900 ℃. First throttling wall and burnerThe wall space of the burning furnace is 50mm, the second throttling wall is in a fan shape, and the diameter of an external circle of the second throttling wall is 200 mm. NO in tail gas_xContent 15mg/Nm³Meets the requirement of environmental protection; NO in sulfuric acid_x ^-The content is 7ppmw, meets the requirement for nitrothiophenic acid, and does not contain NH₄ ⁺And meets the requirement of chlorine gas drying.

Example 3

The use of ammonia-containing H as shown in FIG. 1₂S acid gas is used for preparing sulfuric acid, the acid gas, air, fuel gas and back-mixed tail gas are mixed and combusted in a sulfur recovery incinerator, and the combusted process gas is converted and condensed to prepare sulfuric acid. In this embodiment, the total volume ratio of the acid gas, air, back-mixed tail gas and fuel gas mixture is 1: 10: 0.1: 0.3, the proportion of the back-mixed tail gas in the three-stage incinerator is 0.7: 0.2: 0.1, the ratio of air in the three-stage incinerator is 0.6: 0.2: 0.2, the temperature of the third-stage incinerator is 900 ℃, 950 ℃ and 1000 ℃ respectively. The distance between the first throttling wall and the wall surface of the incinerator is 100mm, the second throttling wall is in a fan shape, and the diameter of an external circle of the second throttling wall is 500 mm. NO in tail gas_xContent 19mg/Nm³Meets the requirement of environmental protection; NO in sulfuric acid_x ^-The content is 9ppmw, meets the requirement for nitrothiophenic acid, and does not contain NH₄ ⁺And meets the requirement of chlorine gas drying.

Example 4

The use of ammonia-containing H as shown in FIG. 1₂S acid gas is used for preparing sulfuric acid, the acid gas, air, fuel gas and back-mixed tail gas are mixed and combusted in a sulfur recovery incinerator, and the combusted process gas is converted and condensed to prepare sulfuric acid. In this embodiment, the total volume ratio of the acid gas, air, back-mixed tail gas and fuel gas mixture is 1: 7: 0.2: 0.2, the proportion of the back-mixed tail gas in the three-stage incinerator is 0.7: 0.2: 0.1, the ratio of air in the three-stage incinerator is 0.7: 0.15: 0.15, the temperature of the third-stage incinerator is 870 ℃, 920 ℃ and 980 ℃ respectively. The distance between the first throttling wall and the wall surface of the incinerator is 90mm, the second throttling wall is in a fan shape, and the diameter of an external circle of the second throttling wall is 300 mm. NO in tail gas_xContent 12mg/Nm³Meets the requirement of environmental protection; NO in sulfuric acid_x ^-The content is 5ppmw, meets the requirement for nitrothiophenic acid, and does not contain NH₄ ⁺And meets the requirement of chlorine gas drying.

Comparative example 1

The hydrogen sulfide incinerator is a primary incinerator, NO back-mixed tail gas is arranged, acid gas containing hydrogen sulfide, air and fuel gas are sprayed into the incinerator through three nozzles, and NO in the tail gas for preparing sulfuric acid after incineration_xThe content is more than 100mg/Nm³Less than 50mg/Nm which does not meet the environmental protection requirement³(ii) a NO in sulfuric acid_x ^-Has a content of 60ppmw, and does not meet the requirement for nitrothiophenic acid (NO)_x ^-＜20ppmw)。

Comparative example 2

The hydrogen sulfide incinerator is a primary incinerator, NO back-mixed tail gas is arranged, acid gas containing hydrogen sulfide, air and fuel gas are sprayed into the incinerator through three nozzles, SCR denitration is additionally arranged behind the incinerator, and NO in tail gas for preparing sulfuric acid after incineration_xThe content is 30-50mg/Nm³Meets the requirement of environmental protection; NO in sulfuric acid_x ^-The content of which is 15ppmw, meets the requirements for nitrothiophenic acid, but NH₄ ⁺The content reaches 15ppmw, and the requirement for drying chlorine gas is not met (NH is not contained)₄ ⁺)。

Comparative example 3

The use of ammonia-containing H as shown in FIG. 1₂S acid gas is used for preparing sulfuric acid, the acid gas, air, fuel gas and back-mixed tail gas are mixed and combusted in a sulfur recovery incinerator, and the combusted process gas is converted and condensed to prepare sulfuric acid. The total volume ratio of the acid gas, the air, the back-mixed tail gas and the fuel gas mixture in the comparative example is not in the patent range and is 1: 8: 0.05: 0.05, and the other parameters are in accordance with example 1. NO in tail gas_xContent 57mg/Nm³Does not meet the environmental protection requirement; NO in sulfuric acid_x ^-Has a content of 27ppmw, does not meet the requirement for nitrothiophenic acid, and does not contain NH₄ ⁺And meets the requirement of chlorine gas drying.

Comparative example 4

The use of ammonia-containing H as shown in FIG. 1₂S acid gas to sulfuric acid incinerator, acid gas, air, fuel gas and back mixingAnd (4) carrying out mixed combustion on the tail gas in a sulfur recovery incinerator, and converting and condensing the combusted process gas to prepare sulfuric acid. The temperature of the third-stage incinerator in this comparative example was out of the range of the patent, and was 950 ℃, 1050 ℃, 1300 ℃ respectively, and other parameters were in accordance with example 3. NO in tail gas_xThe content is 60mg/Nm³Does not meet the environmental protection requirement; NO in sulfuric acid_x ^-Has a content of 28ppmw, does not meet the requirement for nitrothiophenic acid, and does not contain NH₄ ⁺And meets the requirement of chlorine gas drying.

Comparative example 5

The use of ammonia-containing H as shown in FIG. 1₂The S acid gas is used for preparing sulfuric acid, but no back-mixed tail gas exists, and air directly enters the first-stage incinerator from a nozzle. The acid gas, air and fuel gas are mixed and combusted in a sulfur recovery incinerator, and the combusted process gas is converted and condensed to prepare sulfuric acid. In the comparative example, the total volume ratio of the acid gas, the air and the fuel gas mixture is 1: 7: 0.15, furnace temperature and throttle wall parameters were the same as in example 4. NO in tail gas_xContent 81mg/Nm³Does not meet the environmental protection requirement; NO in sulfuric acid_x ^-The content of 36ppmw does not meet the requirement for nitrothiophenic acid, and does not contain NH₄ ⁺And meets the requirement of chlorine gas drying.

Comparative example 6

The use of ammonia-containing H as shown in FIG. 1₂S acid gas is used for preparing sulfuric acid, the acid gas, air, fuel gas and back-mixed tail gas are mixed and combusted in a sulfur recovery incinerator, and the combusted process gas is converted and condensed to prepare sulfuric acid. In this embodiment, the total volume ratio of the acid gas, air, back-mixed tail gas and fuel gas mixture is 1: 5: 0.3: 0.1, the first-stage furnace is not provided with back-mixing tail gas, and the proportion of the back-mixing tail gas in the third-stage incinerator is 0: 0.7: 0.3, the ratio of air in the three-stage incinerator is 0.6: 0.2: 0.2, the furnace temperature and the parameters of the throttle wall are the same as those of example 2. NO in tail gas_xContent 73mg/Nm³Does not meet the environmental protection requirement; NO in sulfuric acid_x ^-The content is 35ppmw, the requirement for nitrothiophenic acid is not met, and NH is not contained₄ ⁺And meets the requirement of chlorine gas drying.

Comparative example 7

The use of ammonia-containing H as shown in FIG. 1₂S acid gas is used for preparing sulfuric acid, the acid gas, air, fuel gas and back-mixed tail gas are mixed and combusted in a sulfur recovery incinerator, and the combusted process gas is converted and condensed to prepare sulfuric acid. In this embodiment, the total volume ratio of the acid gas, air, back-mixed tail gas and fuel gas mixture is 1: 5: 0.3: 0.1, but the second-stage furnace is not provided with back-mixed tail gas, and the proportion of the back-mixed tail gas in the third-stage incinerator is 0.7: 0: 0.3, the ratio of air in the three-stage incinerator is 0.6: 0.2: 0.2, the furnace temperature and the parameters of the throttle wall are the same as those of example 2. NO in tail gas_xContent 66mg/Nm³Does not meet the environmental protection requirement; NO in sulfuric acid_x ^-Has a content of 34ppmw, does not meet the requirement for nitrothiophenic acid, and does not contain NH₄ ⁺And meets the requirement of chlorine gas drying.

Comparative example 8

The use of ammonia-containing H as shown in FIG. 1₂S acid gas is used for preparing sulfuric acid, the acid gas, air, fuel gas and back-mixed tail gas are mixed and combusted in a sulfur recovery incinerator, and the combusted process gas is converted and condensed to prepare sulfuric acid. In this embodiment, the total volume ratio of the acid gas, air, back-mixed tail gas and fuel gas mixture is 1: 5: 0.3: 0.1, but the third-stage furnace is not provided with back-mixing tail gas, and the proportion of the back-mixing tail gas in the third-stage incinerator is 0.7: 0.3: 0, the proportion of air in the three-stage incinerator is 0.6: 0.2: 0.2, the furnace temperature and the parameters of the throttle wall are the same as those of example 2. NO in tail gas_xContent 62mg/Nm³Does not meet the environmental protection requirement; NO in sulfuric acid_x ^-The content is 30ppmw, does not meet the requirement for nitrothiophenic acid, and does not contain NH₄ ⁺And meets the requirement of chlorine gas drying.

Comparative example 9

The use of ammonia-containing H as shown in FIG. 1₂S acid gas is used for preparing sulfuric acid, the acid gas, air, fuel gas and back-mixed tail gas are mixed and combusted in a sulfur recovery incinerator, and the combusted process gas is converted and condensed to prepare sulfuric acid. In this example, acid gas, air, back-mixed tail gas and fuel gas are mixedThe total volume ratio of the combined gas is 1: 10: 0.1: 0.3, the proportion of the back-mixed tail gas in the three-stage incinerator is 0.7: 0.2: 0.1, but the first-stage furnace is not provided with feeding air, the first-stage furnace can not burn and only plays a role in mixing, the temperature is 20 ℃, and the mixed gas is burned in the two stages of furnaces at the back; the proportion of air in the three-stage incinerator is 0: 0.8: 0.2, the second and third furnace temperatures and the parameters of the throttle wall are the same as those in example 3. NO in tail gas_xContent 103mg/Nm³Does not meet the environmental protection requirement; NO in sulfuric acid_x ^-The content of 47ppmw does not meet the requirement for nitrothiophenic acid, and does not contain NH₄ ⁺And meets the requirement of chlorine gas drying.

Comparative example 10

The use of ammonia-containing H as shown in FIG. 1₂S acid gas is used for preparing sulfuric acid, the acid gas, air, fuel gas and back-mixed tail gas are mixed and combusted in a sulfur recovery incinerator, and the combusted process gas is converted and condensed to prepare sulfuric acid. In this embodiment, the total volume ratio of the acid gas, air, back-mixed tail gas and fuel gas mixture is 1: 10: 0.1: 0.3, the proportion of the back-mixed tail gas in the three-stage incinerator is 0.7: 0.2: 0.1, but the second stage furnace was not provided with feed air, the ratio of air in the third stage incinerator was 0.8: 0: 0.2, furnace temperature and throttle wall parameters were the same as in example 3. NO in tail gas_xContent 65mg/Nm³Does not meet the environmental protection requirement; NO in sulfuric acid_x ^-Has a content of 34ppmw, does not meet the requirement for nitrothiophenic acid, and does not contain NH₄ ⁺And meets the requirement of chlorine gas drying.

Comparative example 11

The use of ammonia-containing H as shown in FIG. 1₂S acid gas is used for preparing sulfuric acid, the acid gas, air, fuel gas and back-mixed tail gas are mixed and combusted in a sulfur recovery incinerator, and the combusted process gas is converted and condensed to prepare sulfuric acid. In this embodiment, the total volume ratio of the acid gas, air, back-mixed tail gas and fuel gas mixture is 1: 10: 0.1: 0.3, the proportion of the back-mixed tail gas in the three-stage incinerator is 0.7: 0.2: 0.1, but the third furnace is not provided with feed air, and the proportion of air in the third furnace is 0.8: 0.2: 0, furnace temperature and throttle wall and the likeConsistent with example 3. NO in tail gas_xContent 62mg/Nm³Does not meet the environmental protection requirement; NO in sulfuric acid_x ^-The content of 29ppmw does not meet the requirement for nitrothiophenic acid, and does not contain NH₄ ⁺And meets the requirement of chlorine gas drying.

While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. It will be appreciated by those skilled in the art that modifications or adaptations to the invention may be made in light of the teachings of the present specification. Such modifications or adaptations are intended to be within the scope of the present invention as defined in the claims.

Claims

1. H containing ammonia₂Preparation of low-content NO from S acid gas_xThe sulfuric acid incinerator is characterized in that the incinerator is a three-level incinerator, a throttling wall is arranged between every two levels of incinerators, a first-level incinerator air inlet is formed in one end, away from a second-level incinerator, of the first-level incinerator, a second-level incinerator air inlet is formed in the top end of the second-level incinerator, a third-level incinerator air inlet is formed in the top end of the third-level incinerator, a tail gas outlet is formed in one end, away from the second-level incinerator, of the third-level incinerator, and the tail gas outlet is connected with the first-level incinerator air inlet and the second-level incinerator air inlet respectively.

2. The incinerator according to claim 1, wherein the first stage incinerator air inlet pre-mixes the raw materials into the incinerator through a nozzle, and the nozzle is a four-channel nozzle arranged concentrically and circularly from inside to outside.

3. The incinerator according to claim 1, wherein the throttle wall between the first and second incinerators is a circular wall, and an annular gap is provided between the throttle wall and the incinerator cavity; preferably, the annular gap has a size of 50-100mm, preferably 50-70 mm.

4. The incinerator according to claim 1, wherein the throttle wall between the second and third stage incinerators is a circular wall with apertures in the form of fan blades; preferably, the circumscribed circle diameter of the fan blade shape is 200-.

5. H containing ammonia₂Preparation of low-content NO from S acid gas_xThe method of sulfuric acid is characterized by comprising adding H containing ammonia₂S acid gas as raw material, incinerating the same in the incinerator of any one of claims 1 to 4 to make H containing ammonia₂Partial oxidation of ammonia in S-acid gas to N₂、H₂S is fully combusted and converted into SO₂，SO₂Further converted into SO₃Followed by a step of preparing sulfuric acid.

6. The method of claim 5, wherein the H containing ammonia₂The ammonia content in the S acid gas is 300-600mg/Nm³(ii) a Preferably, NO is present in the tail gas from the production of sulphuric acid_xThe content is less than 20mg/Nm³NO in sulfuric acid_x ^-Less than 10ppmw and no NH₄ ⁺。

7. A method according to claim 5 or claim 6, wherein the feed gas fed through the inlet of the first stage incinerator comprises H containing ammonia₂S acid gas, air, fuel gas and part of back-mixed tail gas after sulfuric acid is prepared at an outlet of an incinerator; preferably, the feeding mixing mode of the first-stage incinerator is four-channel nozzle premixing type mixing, and the materials conveyed in the four channels from inside to outside of the four-channel nozzle are fuel gas, air and acid gas respectively, and part of back-mixed tail gas after sulfuric acid is prepared at the outlet of the incinerator.

8. A method according to claim 5 or 6, characterized in that the mixture of part of the back-mixed tail gas and air after the sulfuric acid is prepared at the outlet of the incinerator enters the second-stage incinerator through the air inlet of the second-stage incinerator; air enters the third-stage incinerator through the air inlet of the third-stage incinerator.

9. A method according to claim 7, characterized in that the H containing ammonia entering the incinerator₂The total volume ratio of the acid gas, the air and the part of the back-mixed tail gas and the fuel gas after the sulfuric acid is prepared at the outlet of the incinerator is 1: 5-10: 0.1-0.3: 0.1 to 0.3, preferably 1: 6-8: 0.2-0.3: 0.2-0.3.

10. A method according to any one of claims 7 to 9, wherein the volume ratio of the part of the back-mixed tail gas after the sulfuric acid is prepared at the outlet of the incinerator in the three-stage incinerator is 0.6-0.8: 0.2-0.3: 0.1-0.2, preferably 0.6-0.7: 0.2-0.3: 0.1; preferably, the volume ratio of the air in the three-stage incinerator is 0.5-0.8: 0.1-0.3: 0.1-0.2, preferably 0.6-0.8: 0.1-0.2: 0.1-0.2; more preferably, the temperature of the three-stage incinerator is 830-900 deg.C, 850-950 deg.C and 900-1000 deg.C respectively.