阅读说明：本技术 一种废硫酸和/或含硫废液裂解再生制备硫酸的装置及方法 (Device and method for preparing sulfuric acid by cracking and regenerating waste sulfuric acid and/or sulfur-containing waste liquid ) 是由 章一夫 程广春 洪哲 于 2019-12-24 设计创作，主要内容包括：本发明提供了一种废硫酸和/或含硫废液裂解再生制备硫酸的装置及方法,该方法包括如下步骤：a.将助燃气体进行预热；b.通过燃料与助燃气体的燃烧反应升高温度,使得废硫酸和/或含硫废液发生裂解,生成含SO<Sub>2</Sub>的第一混合气；c.对所述第一混合气进行热量回收,得到第二混合气；d.将所述第二混合气进行净化处理,得到第三混合气；e.将所述第三混合气进行干燥处理,得到第四混合气；f.采用脱硝工艺脱除所述第四混合气中的氮氧化物,得到第五混合气；g.将所述第五混合气中的SO<Sub>2</Sub>氧化为SO<Sub>3</Sub>；h.采用浓硫酸吸收所述步骤g中生成的SO<Sub>3</Sub>；i.对所述步骤h排出的尾气进行净化处理。本发明一实施方式的装置或方法,具有运行成本低廉﹑稳定性高﹑环保效果好等优点。(The invention provides a device and a method for preparing sulfuric acid by cracking and regenerating waste sulfuric acid and/or sulfur-containing waste liquid, wherein the method comprises the following steps: a. preheating combustion-supporting gas; b. the temperature is raised through the combustion reaction of fuel and combustion-supporting gas, SO that the waste sulfuric acid and/or sulfur-containing waste liquid are cracked to generate SO 2 The first mixed gas of (1); c. carrying out heat recovery on the first mixed gas to obtain a second mixed gas; d. purifying the second mixed gas to obtain a third mixed gas; e. drying the third mixed gas to obtain a fourth mixed gas; f. removing nitrogen oxides in the fourth mixed gas by adopting a denitration process to obtain a fifth mixed gas; g. SO in the fifth mixed gas 2 Oxidation to SO 3 (ii) a h. Adopting concentrated sulfuric acid to absorb the product generated in the step gSO of (A) 3 (ii) a i. And h, purifying the tail gas discharged in the step h. The device or the method provided by the embodiment of the invention has the advantages of low operation cost, high stability, good environment-friendly effect and the like.)

1. A method for preparing sulfuric acid by cracking and regenerating waste sulfuric acid and/or sulfur-containing waste liquid comprises the following steps:

a. preheating combustion-supporting gas;

b. the temperature is raised through the combustion reaction of fuel and combustion-supporting gas, SO that the waste sulfuric acid and/or sulfur-containing waste liquid are cracked to generate SO₂The first mixed gas of (1);

c. carrying out heat recovery on the first mixed gas to obtain a second mixed gas;

d. purifying the second mixed gas to obtain a third mixed gas;

e. drying the third mixed gas to obtain a fourth mixed gas;

f. removing nitrogen oxides in the fourth mixed gas by adopting a denitration process to obtain a fifth mixed gas;

g. SO in the fifth mixed gas₂Oxidation to SO₃；

h. Adopting concentrated sulfuric acid to absorb SO generated in the step g₃；

i. And h, purifying the tail gas discharged in the step h.

2. A process according to claim 1, wherein in step a the combustion-supporting gas is heated to a temperature of 300-500 ℃ and/or,

in the combustion-supporting gas of the step a, the volume content of oxygen is 21-30%, and/or,

in the first mixed gas, the volume content of oxygen is 1.5-3%.

3. A method according to claim 1, wherein a two-stage series waste heat boiler is employed in step c, the two-stage series waste heat boiler comprising a first waste heat boiler and a second waste heat boiler; the temperature of the process gas at the outlet of the first waste heat boiler is 500-600 ℃, and the temperature of the process gas at the outlet of the second waste heat boiler is 300-350 ℃.

4. The method according to claim 1, wherein the purification treatment of the step d comprises temperature reduction and dust removal treatment, cooling dehydration treatment and acid mist removal treatment.

5. A device for preparing sulfuric acid by cracking and regenerating waste sulfuric acid and/or sulfur-containing waste liquid comprises:

the combustion-supporting gas preheating unit is used for preheating combustion-supporting gas;

the cracking unit is used for cracking the waste sulfuric acid and/or the sulfur-containing waste liquid;

the waste heat recovery unit is used for recovering the heat of the first mixed gas discharged by the cracking unit to obtain a second mixed gas;

the purification unit is used for purifying the second mixed gas to obtain a third mixed gas;

the drying unit is used for drying the third mixed gas to obtain a fourth mixed gas;

the nitrogen oxide removal unit is used for removing nitrogen oxides from the fourth mixed gas to obtain a fifth mixed gas;

a catalytic oxidation unit for converting SO in the fifth mixed gas₂Oxidation to SO₃；

An absorption unit for absorbing SO generated in the catalytic oxidation unit₃(ii) a And

and the tail gas treatment unit is used for purifying the tail gas discharged by the absorption unit.

6. The apparatus according to claim 5, wherein the combustion-supporting gas preheating unit comprises a heating furnace and a heater, the heater being connected to the heating furnace and the cracking unit, respectively; and/or the presence of a gas in the gas,

the waste heat recovery unit comprises a first waste heat boiler and a second waste heat boiler which are connected, and the cracking unit is connected with the first waste heat boiler.

7. The apparatus as claimed in claim 6, wherein the waste heat recovery unit includes a preheater, a superheater, and a combustion furnace, the preheater being connected to the first waste heat boiler and the second waste heat boiler, respectively, and the superheater being connected to the first waste heat boiler, the second waste heat boiler, and the combustion furnace, respectively.

8. The apparatus of claim 5, wherein the purification unit comprises a gas scrubber, a packed cooling tower, a first electric demister, and a second electric demister in series.

9. The apparatus of claim 5, wherein the catalytic oxidation unit comprises a converter, a first heater, a second heater, a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a fifth heat exchanger and a sixth heat exchanger, wherein the converter is respectively connected with the first heat exchanger and the second heat exchanger, the fourth heat exchanger is respectively connected with the second heat exchanger and the third heat exchanger, and the sixth heat exchanger is respectively connected with the first heat exchanger and the fifth heat exchanger.

10. The apparatus of claim 9, wherein the converter comprises a stage I catalyst bed, a stage II catalyst bed, a stage III catalyst bed, a stage IV catalyst bed; the first heater is connected with the I section of catalyst bed layer, and the second heater is connected with the IV section of catalyst bed layer.

Technical Field

The invention relates to recovery and treatment of waste sulfuric acid or sulfur-containing waste liquid, in particular to a device and a method for preparing sulfuric acid by cracking and regenerating the waste sulfuric acid and/or the sulfur-containing waste liquid.

Background

In recent years, with the rapid development of national economy in China, the demand of industrial and agricultural production for basic chemicals such as sulfur, sulfuric acid and the like and fossil energy such as coal, petroleum, natural gas and the like is increasing year by year. On one hand, the annual domestic consumption of sulfuric acid is more than 9Mt, and a large part of sulfuric acid is discharged in the form of waste sulfuric acid (mainly in the industries of titanium dioxide, lead storage batteries, aromatic hydrocarbon nitration, chloridization, dyes and the like); on the other hand, sulfur in fossil energy is recovered by a Claus method, and a part of sulfur is desulfurized by a wet oxidation method and finally discharged in the form of desulfurization waste liquid and sulfur paste (mainly in the coking and nitrogen fertilizer industries); in addition, a large amount of sulfur-containing waste liquid containing sulfide, sulfate, thiosulfate and sulfite is discharged from the petrochemical industry and the fine chemical industry. The waste sulfuric acid and the sulfur-containing waste liquid which are not easy to be treated cause great harm to the society and the environment. How to treat the waste sulfuric acid and the sulfur-containing waste liquid safely, thoroughly, economically and effectively is the focus of attention of the industry. Meanwhile, the waste sulfuric acid and the sulfur-containing waste liquid are potential sulfur resources, and have great economic significance and social benefit for resource recycling of the sulfur resources under the current situation of shortage of sulfur resources in China.

At present, the titanium dioxide waste acid, the dye waste acid, the steel pickling waste acid, the alkylation waste acid, the nitration waste acid, the Methyl Methacrylate (MMA) waste acid, the hydrofluoric acid drying waste acid, the chlor-alkali waste acid, the acetylene purification waste acid, the storage battery waste acid, the sulfonation waste acid and the like are mainly used as industrial waste sulfuric acid in China, and the domestic waste sulfuric acid production amount is about 12Mt (by 100% H) in 2016 years₂SO₄Meter), wherein ω (H)₂SO₄) More than or equal to 40 percent of waste acid accounts for 45 percent, omega (H)₂SO₄)<40% of waste acid accounts for about 55%; the industrial sulfur-containing waste liquid in China is mainly prepared by the byproduct of desulfurization waste liquid of wet oxidation desulfurization devices of coking plants and nitrogen fertilizer plantsSulfur paste and waste viscose fiber liquid as main material.

At present, the treatment of industrial waste sulfuric acid in China mainly comprises 6 ways of concentration, cracking regeneration, fertilizer production, chemical oxidation, extraction, neutralization treatment and the like; the treatment of industrial sulfur-containing waste liquid in China mainly comprises the ways of concentration and salt extraction, cracking regeneration and the like. Generally, different treatment processes are adopted according to the flow, concentration, impurity content and components of the waste sulfuric acid and the sulfur-containing waste liquid, and sometimes, several processes are matched for use. Because industrial waste sulfuric acid and sulfur-containing waste liquid contain a large amount of impurities, the technologies of concentration, fertilizer production, chemical oxidation, extraction, neutralization treatment, concentration salt extraction and the like have the problems that the treatment capacity is small, the impurities cannot be treated, the quality of the recovered product is poor, and the method is only suitable for specific applications.

The cracking regeneration technology of the waste sulfuric acid and the sulfur-containing waste liquid is based on the decomposition or combustion of sulfide, sulfate and other organic and inorganic impurities in the waste sulfuric acid and the sulfur-containing waste liquid at high temperature to finally generate SO-containing₂The flue gas is used for producing clean concentrated sulfuric acid (or fuming sulfuric acid) or other sulfuration chemical products by adopting a contact process.

The cracking regeneration technology has the advantages of relatively low energy consumption, high purity of final products, no secondary pollution and the like, and is particularly suitable for treating waste sulfuric acid and sulfur-containing waste liquid with large flow and high sulfur content.

The existing sulfuric acid production technology basically adopts a contact process, namely, SO is prepared from a sulfur-containing raw material₂Process gas, SO₂The gas is oxidized to generate SO under the action of catalyst₃Then adding SO₃Absorbing to generate sulfuric acid. The two-rotation and two-absorption acid making process is generally adopted at home and abroad.

In recent years, the technology for preparing sulfuric acid by cracking regeneration is popularized fast in China, and the application field is continuously developed. The method is mainly applied as follows: the C4 alkylation unit is matched with a waste acid cracking regeneration environment-friendly device; a natural gas acetylene waste acid and calcium carbide dry acetylene waste acid cracking and regenerating device; a cracking regeneration device matched with acrylonitrile and MMA waste liquid treatment; coking plant desulfurization waste liquid schizolysis regenerating unit.

Although the technology for preparing sulfuric acid by cracking and regenerating waste sulfuric acid and sulfur-containing waste liquid has been advanced to a certain extent, some technical problems still need to be solved:

1. the waste sulfuric acid and sulfur-containing waste liquid contain more impurities, especially high-content of chlorine, fluorine and metal salt, and contain arsenic, fluorine, chlorine and metal ions (especially Na)⁺﹑K⁺) The problem that waste heat recovery equipment (a waste heat boiler and a high-temperature superheater) is easy to corrode and block, and especially the problem that the high-temperature superheater cannot be cleaned up becomes a bottleneck for limiting long-period stable operation of the device;

2. the concentration of the waste sulfuric acid and the sulfur-containing waste liquid is low, a large amount of water exists, a large amount of fuel gas is consumed for cracking, the process gas amount is greatly increased, the size of equipment is large, and the fuel gas enters SO₂Catalytic oxidation unit SO₂Low concentration and unable to satisfy SO₂Self-heating balance of the catalytic oxidation unit;

3. a large amount of thermal NOx is generated in the cracking process of waste sulfuric acid and sulfur-containing waste liquid, in addition, the waste liquid containing ammonium salt can also generate a large amount of NOx, the NOx is dissolved in the sulfuric acid, the quality of the sulfuric acid can be influenced, the sulfuric acid is reddened, the NOx is dissolved in the sulfuric acid, a passivation film can be damaged, the corrosion of the sulfuric acid to pipelines and equipment is accelerated, meanwhile, the content of the NOx in tail gas can exceed the standard, and the environment-friendly emission requirement cannot be met.

Disclosure of Invention

The invention mainly aims to provide a method for preparing sulfuric acid by cracking and regenerating waste sulfuric acid and/or sulfur-containing waste liquid, which comprises the following steps: a. preheating combustion-supporting gas; b. the temperature is raised through the combustion reaction of fuel and combustion-supporting gas, SO that the waste sulfuric acid and/or sulfur-containing waste liquid are cracked to generate SO₂The first mixed gas of (1); c. carrying out heat recovery on the first mixed gas to obtain a second mixed gas; d. purifying the second mixed gas to obtain a third mixed gas; e. drying the third mixed gas to obtain a fourth mixed gas; f. removing nitrogen oxides in the fourth mixed gas by adopting a denitration process to obtain a fifth mixed gas; g. SO in the fifth mixed gas₂Oxidation to SO₃(ii) a h. Adopting concentrated sulfuric acid to absorb SO generated in the step g₃(ii) a i. For step hAnd (5) purifying the tail gas.

The invention provides a device for preparing sulfuric acid by cracking and regenerating waste sulfuric acid and/or sulfur-containing waste liquid, which comprises a combustion-supporting gas preheating unit, a cracking unit, a waste heat recovery unit, a purification unit, a drying unit, a nitrogen oxide removal unit, a catalytic oxidation unit, an absorption unit and a tail gas treatment unit, wherein the combustion-supporting gas preheating unit is used for preheating the combustion-supporting gas; the combustion-supporting gas preheating unit is used for preheating combustion-supporting gas; the cracking unit is used for cracking the waste sulfuric acid and/or the sulfur-containing waste liquid; the waste heat recovery unit is used for recovering the heat of the first mixed gas discharged by the cracking unit to obtain a second mixed gas; the purification unit is used for purifying the second mixed gas to obtain a third mixed gas; the drying unit is used for drying the third mixed gas to obtain a fourth mixed gas; the nitrogen oxide removal unit is used for removing nitrogen oxides from the fourth mixed gas to obtain a fifth mixed gas; the catalytic oxidation unit is used for converting SO in the fifth mixed gas₂Oxidation to SO₃(ii) a The absorption unit is used for absorbing SO generated in the catalytic oxidation unit₃(ii) a And the tail gas treatment unit is used for purifying the tail gas discharged by the absorption unit.

The device or the method provided by the embodiment of the invention has the advantages of low operation cost, large operation elasticity, high stability, good environment-friendly effect and the like.

Drawings

Fig. 1 to 5 are schematic structural diagrams of a device for preparing sulfuric acid by cracking and regenerating waste sulfuric acid and/or a sulfur-containing waste liquid according to an embodiment of the present invention.

Detailed Description

Exemplary embodiments that embody features and advantages of the invention are described in detail below in the specification. It is to be understood that the invention is capable of other embodiments and that various changes in form and details may be made therein without departing from the scope of the invention and the description and drawings are to be regarded as illustrative in nature and not as restrictive. The terms "first", "second", "third", "fourth", "fifth", "sixth", and the like are used for distinguishing a plurality of processes or products with the same name, and are not limited thereto. The oxygen content referred to in the present invention means the volume content.

An embodiment of the invention provides a device and a method for preparing sulfuric acid by cracking and regenerating waste sulfuric acid and/or sulfur-containing waste liquid, wherein the device and the method comprise the following steps:

a. preheating combustion-supporting gas;

b. the temperature is raised through the combustion reaction of fuel and combustion-supporting gas, SO that the waste sulfuric acid and/or sulfur-containing waste liquid is cracked to generate high-temperature SO-containing waste liquid₂Process gas (first mixed gas);

c. for the high-temperature SO-containing generated in the step b₂The process gas is subjected to heat recovery, and the recovered heat is used for producing superheated steam;

d. recovering heat in step c to obtain SO₂The process gas (second mixed gas) is subjected to heat insulation temperature reduction and dust removal, cooling dehydration, acid mist removal and other purification treatment in sequence;

e. d, purifying the SO-containing product obtained in the step d₂Drying the process gas (third mixed gas);

f. removing dried SO-containing by adopting denitration process₂Nitrogen oxides (NOx) in the process gas (fourth mixed gas);

g. f, carrying out denitration treatment on the obtained SO-containing material₂SO in the Process gas (fifth gas mixture)₂Oxidation to SO₃；

h. Absorbing SO from step g with concentrated sulfuric acid₃To generate sulfuric acid;

i. for step h to absorb SO₃Further treating the tail gas discharged from the tail gas to remove residual SO in the tail gas₂Acid mist and the like, and the clean tail gas obtained is sent into a chimney for emission.

In one embodiment, the combustion-supporting gas is air or oxygen-enriched air, wherein the combustion-supporting gas is air

Oxygen-enriched air is used as combustion-supporting gas to reduce the introduction of inert gas into SO₂Process gas, increasing SO in process gas₂The concentration of (c).

Method of one embodiment of the inventionThe method can reduce the supplement of fuel gas in the cracking process by preheating the combustion-supporting gas, thereby reducing the introduction of inert gas into the process gas and improving the SO in the process gas₂The concentration of (c).

In one embodiment, the combustion gas is preheated to 300 ℃ to 500 ℃, e.g., 320 ℃, 350 ℃, 380 ℃, 400 ℃, 420 ℃, 450 ℃, 480 ℃.

In one embodiment, the combustion-supporting gas is heated by an external heat source, so that the problem that the running stability of the device cannot be ensured by using an internal heat source can be avoided.

In one embodiment, the fuel for heating the combustion-supporting gas is one or more of gas, liquid or solid fuel.

In step b of one embodiment, the fuel used is one or more of a gas, a liquid or a solid fuel, and the gas fuel may be, for example, natural gas.

In one embodiment, the fuel comprises conventional heat value providing fuel and a sulfur-containing material, the sulfur-containing material may be one or more of liquid sulfur, a hydrogen sulfide-containing gas, and sulfuric acid, and the presence of the sulfur-containing material in the fuel may be used to maintain SO in the process gas₂The concentration of (c).

In one embodiment, the cracked SO obtained in step b₂In process gas

1.5% to 3%, e.g. 1.8%, 2%, 2.2%, 2.5%, 2.8%, enables complete cracking of spent sulfuric acid and/or sulfur-containing spent liquor while minimizing the generation of NOx in the process gas.

In one embodiment, the waste sulfuric acid and/or sulfur-containing waste liquid is atomized and then cracked, and the atomization medium can be compressed air or low-pressure steam; the mass ratio of the using amount of the atomizing medium to the waste sulfuric acid and/or the sulfur-containing waste liquid is 0.15-0.3, such as 0.16, 0.18, 0.2, 0.22, 0.25 and 0.28.

In one embodiment, the temperature of the cracking of the spent sulfuric acid and/or sulfur-containing waste liquid is 1000 ℃ to 1250 ℃, such as 1050 ℃, 1100 ℃, 1150 ℃, 1200 ℃.

In one embodiment, the heat recovery of step c employs two stages of series connected waste heat boilers, including a first waste heat boiler and a second waste heat boiler.

In one embodiment, the waste heat boiler adopts a fire tube boiler, the inner diameter of a heat exchange tube of the waste heat boiler is more than or equal to 60mm, large cavities can be arranged at the front and the rear of the waste heat boiler for collecting ash, and a quick-opening ash cleaning hole is arranged at the tail of a rear smoke box of the waste heat boiler for online ash cleaning, so that the blockage of a furnace tube is reduced.

In one embodiment, the working pressure of the waste heat boiler can be 4.0-6.0 MPa, so as to ensure that the wall temperature of the heat exchange tube is always above the dew point, and thus the problem of dew point corrosion of the waste heat boiler is effectively solved.

In one embodiment, the first waste heat boiler outlet process gas temperature is 500 ℃ to 600 ℃, e.g., 520 ℃, 550 ℃, 580 ℃; the temperature of the process gas at the outlet of the second waste heat boiler is 300 ℃ to 350 ℃, such as 310 ℃, 320 ℃ and 340 ℃.

In step c of one embodiment, the steam is superheated using an external heat source.

In step d of one embodiment, a gas scrubber is used to perform adiabatic temperature reduction dust removal to enhance the scrubbing process and remove most of the moisture and dust.

In step d of an embodiment, a packed cooling tower is used for cooling and dehydrating, and the circulating liquid of the packed tower is cooled by using cryogenic water and/or circulating cooling water.

In step d of one embodiment, a two-stage electro-defogging process is used to remove the acid mist.

In one embodiment, the SO is contained after the treatment of step d₂The temperature of the process gas is controlled at 32 ℃ to 38 ℃, for example, at 33 ℃, 35 ℃ and 36 ℃.

In one embodiment, concentrated sulfuric acid is used to treat the SO-containing product after the purification treatment in step d₂And drying the process gas.

In one embodiment, for drying SO-containing materials₂The mass concentration of the sulfuric acid in the process gas is 93-95%, and the temperature is 45-60 ℃, such as 48 ℃, 50 ℃, 52 ℃, 55 ℃ and 58 ℃.

In one embodiment, the denitration process in step f is an SCR denitration process, and the SCR denitration operation temperature can be controlled at 390-430 ℃, for example, 400 ℃, 410 ℃, 420 ℃.

In step g of one embodiment, the SO-containing from step f is reacted over a catalyst₂SO in process gas₂Oxidation to SO₃。

In step g of one embodiment, the SO-containing material to be oxidized₂Of process gases

0.9 to 1.15, for example, 0.95, 1.0, 1.05, 1.1.

In step g of one embodiment, SO₂The temperature of the catalytic oxidation is 380 to 620 ℃, for example, 400 ℃, 420 ℃, 450 ℃, 480 ℃, 500 ℃, 520 ℃, 550 ℃, 580 ℃, 600 ℃.

In step h of one embodiment, for absorbing SO₃The mass concentration of the sulfuric acid is 98-98.5%, and the temperature is 60-70 ℃, such as 62 ℃, 65 ℃, 66 ℃ and 68 ℃.

In one embodiment, in steps g and h, SO₂Catalytic oxidation and SO₃The absorption adopts a two-conversion two-absorption process, and the conversion adopts a 3+1 two-conversion process.

In one embodiment, the tail gas treatment in step i is performed by a hydrogen peroxide desulfurization process or a sodium desulfurization process.

Referring to fig. 1 to 5, an embodiment of the present invention provides an apparatus for preparing sulfuric acid by cracking and regenerating waste sulfuric acid and/or sulfur-containing waste liquid, which is used for implementing the above method, and includes a combustion-supporting gas preheating unit, a cracking unit, a waste heat recovery unit, an acid cleaning and purifying unit, a drying unit, a nitrogen oxide removing unit, a catalytic oxidation unit, an absorption unit, and a tail gas treatment unit, which are connected in sequence.

In an embodiment, the output end of the combustion-supporting gas preheating unit is connected with the cracking unit, the output end of the cracking unit is connected with the waste heat recovery unit, the output end of the waste heat recovery unit is connected with the pickling purification unit, the output end of the pickling purification unit is connected with the drying unit, the output end of the drying unit is connected with the nitrogen oxide removal unit, the output end of the nitrogen oxide removal unit is connected with the catalytic oxidation unit, the output end of the catalytic oxidation unit is connected with the absorption unit, and the output end of the absorption unit is connected with the tail gas treatment unit.

In one embodiment, the combustion-supporting gas preheating unit is used for heating the combustion-supporting gas to a certain temperature, for example, 300 to 500 ℃, so as to be used for the cracking reaction of the cracking unit.

In one embodiment, the combustion-supporting gas preheating unit comprises a heating furnace 7 and a heater 8, the heating furnace 7 is connected with the heater 8, and the gas in the heating furnace 7 can reach a predetermined temperature, for example 400 ℃, by heating the gas to a high temperature and exchanging heat with the combustion-supporting gas in the heater 8.

In one embodiment, the heating furnace 7, which is an external heat source, is used for heating the combustion-supporting gas, so that instability caused by using an internal heat source is avoided, and the device can run more stably.

In one embodiment, the combustion-supporting gas preheating unit comprises a first air filter 1 and a first fan 2, and the first fan 2 is connected to the first air filter 1 and the heating furnace 7 respectively. After being treated by the first air filter 1, air serving as combustion-supporting gas can enter the heating furnace 7 under the action of the first fan 2, fuel gas enters the heating furnace 7 through the other inlet, the fuel gas is combusted in the heating furnace 7 to release heat, and the temperature of flue gas in a system is increased.

In one embodiment, the combustion-supporting gas preheating unit comprises a second air filter 3 and a second fan 4, and the second fan 4 is connected with the inlets of the second air filter 3 and the heater 8 respectively. After being processed by the second air filter 3, the air can be mixed with oxygen from outside the battery compartment to form oxygen-enriched air, the oxygen content of the oxygen-enriched air can be 30%, for example, the oxygen-enriched air can enter the heater 8 under the action of the second fan 4, and can exchange heat with high-temperature flue gas at the outlet of the heating furnace 7, and after the temperature is raised to about 400 ℃, the oxygen-enriched air is sent to the cracking unit.

In one embodiment, the cracking unit is used for spent sulfuric acid and/or pyrolysis of sulfur-containing waste liquid to obtain high-temperature SO-containing liquid₂And (4) process gas.

In one embodiment, the cracking unit is connected to the combustion-supporting gas preheating unit and the waste heat recovery unit, respectively.

In one embodiment, the cracking unit includes a cracking furnace 9, and the cracking furnace 9 is connected to a heater 8.

In one embodiment, the cracking furnace 9 may be a vertical furnace, a horizontal furnace, or a combination of a vertical furnace and a horizontal furnace.

In one embodiment, the furnace 9 includes a top inlet, a sidewall inlet adjacent the top, and a bottom outlet.

In one embodiment, the cracking furnace 9 may be connected to the heater 8 through a sidewall inlet, so that the combustion-supporting gas preheated to a certain temperature in the heater 8 enters the cracking furnace 9; fuel gas (e.g., natural gas) may enter the furnace 9 through a sidewall inlet; the spent sulfuric acid and/or sulfur-containing waste liquid may enter at the top inlet of the cracking furnace 9.

In one embodiment, the fuel added to the cracking furnace 9 may be one or more of a gas, a liquid, or a solid fuel.

In one embodiment, the spent sulfuric acid and/or sulfur-containing waste liquid is fed into an atomizing spray gun, sufficiently contacted with compressed air and atomized, and then fed into a cracking furnace 9, wherein the fuel gas and oxygen-enriched air from a combustion-supporting gas preheating unit with a temperature of about 400 ℃ are sufficiently combusted in the cracking furnace 9 to generate a high temperature, SO that the spent sulfuric acid and/or sulfur-containing waste liquid is cracked at a high temperature of, for example, 1100 ℃, and sulfur in the spent sulfuric acid and/or sulfur-containing waste liquid is cracked to generate SO₂To obtain SO-containing₂And (4) process gas.

In one embodiment, the SO-containing product of the cleavage₂The residence time of the process gas in the cracking furnace 9 can be controlled within 6 s-15 s, such as 7s, 8s, 10s, 12 s.

In one embodiment, the oxygen content of the process gas at the bottom outlet of the cracking furnace 9 is controlled

1.5-3%, such as 1.8% and 2%、2.2％、2.5％、2.8％。

In one embodiment, the oxygen content of the process gas at the bottom outlet of the cracking furnace 9 is controlled

The oxygen content is about 2 percent, and the combustion-supporting gas amount and the fresh oxygen amount can be adjusted according to the oxygen content at the bottom outlet of the cracking furnace 9; the fuel gas quantity and the combustion-supporting gas temperature can be adjusted according to the process gas temperature at the outlet at the bottom end of the cracking furnace 9.

In one embodiment, the cracking furnace 9 is connected to the waste heat recovery unit through a bottom outlet.

In one embodiment, the waste heat recovery unit is used for recovering high-temperature SO-containing gas₂Heat of the process gas.

In an embodiment, the waste heat recovery unit comprises a first waste heat boiler 13 and a second waste heat boiler 14 connected. The outlet at the bottom end of the cracking furnace 9 can be connected with a first waste heat boiler 13, and SO-containing gas discharged from the cracking furnace 9₂The process gas is subjected to heat exchange treatment by the first waste heat boiler 13, then the temperature is reduced to about 500 ℃, is subjected to heat exchange treatment by the second waste heat boiler 14, then is cooled to about 320 ℃, and is discharged out of the waste heat recovery unit.

In one embodiment, the waste heat recovery unit includes a third air filter 5, a third fan 6, a combustion furnace 10, a high temperature superheater 11, and a boiler feed water preheater 12.

In an embodiment, the waste heat boiler comprises a material cavity and a heat exchange cavity arranged outside the material cavity, the material cavity is used for circulating the process gas, and the heat exchange cavity is used for accommodating a heat exchange medium. SO-containing gas discharged from the bottom outlet of the cracking furnace 9₂The process gas is discharged out of the waste heat recovery unit after passing through the material cavity of the first waste heat boiler 13 and the material cavity of the second waste heat boiler 14 in sequence.

In one embodiment, two-stage series waste heat boilers, namely the first waste heat boiler 13 and the second waste heat boiler 14, are adopted for heat recovery, and the two-stage series waste heat boilers can avoid the situation that the length of a heat exchange pipe of a single waste heat boiler reaches 9m, and increase the difficulty of online ash removal.

In one embodiment, the waste heat boiler is a fire tube boiler, and the heat exchange tubes of the fire tube boiler are phi 76 multiplied by 3.5, and the length of the heat exchange tubes is 4.5 m. Set up firetube exhaust-heat boiler and can avoid setting up high temperature over heater 11 here and influence the long period steady operation of device, particularly, high temperature over heater 11 is water tube boiler structure, and the over heater shell side is walked to the burner gas, and a large amount of ashes can adhere in the burner gas in the superheater tube gap, can't realize online deashing, need device parking processing if the deashing needs.

In one embodiment, the first waste heat boiler 13 and the second waste heat boiler 14 are connected to the high temperature superheater 11 and the boiler feed water preheater 12 through respective heat exchange chambers. Boiler feed water (heat exchange medium) from outside the battery compartment is preheated by a boiler feed water preheater 12 and then respectively enters the heat exchange cavities of a first waste heat boiler 13 and a second waste heat boiler 14, and then leaves the heat exchange cavity to enter a high temperature superheater 11 for superheating after exchanging heat with high temperature process gas in the material cavity, so as to obtain superheated steam.

In one embodiment, the third air filter 5, the third fan 6, the combustion furnace 10, and the high temperature superheater 11 are connected in sequence; after passing through the third air filter 5, the air enters the combustion furnace 10 under the action of the third fan 6, the fuel gas enters the combustion furnace 10 through the other inlet, and the fuel gas is combusted in the combustion furnace 10 to provide heat for the high-temperature superheater 11.

In one embodiment, the acid cleaning unit is used to clean SO-containing gas₂And cooling the process gas, removing dust, removing acid mist and the like.

In one embodiment, the acid cleaning purification unit comprises a gas scrubber 15, a packed cooling tower 16, a first electric demister 17, and a second electric demister 18 connected together.

SO-containing exhaust from the second waste heat boiler 14₂The process gas (which may be at a temperature of about 320 ℃) may be passed sequentially through a gas scrubber 15 and a packed cooling tower 16 for SO-containing streams₂Cooling and dedusting the process gas, wherein the gas temperature can be reduced to below 38 ℃; cooled SO-containing₂The process gas is treated by a first electric demister 17 and a second electric demister 18 to remove acid mist, and the content of the acid mist in the outlet gas can be less than 5mg/Nm³。

In one embodiment, the acid cleaning purification unitThe discharged SO-containing gas including the fourth air filter 21, the fourth air filter 21 and the second electric demister 18₂The process gas lines are connected SO as to contain SO₂After exiting the second electric demister 18, the process gas is mixed with air filtered by a fourth air filter 21 and enters a subsequent drying unit.

In one embodiment, the pickling purification unit comprises an elevated tank 19, a desorption tower 20, a safety seal 22, a gas scrubber circulation pump 23, a dilute acid delivery pump 24, a stirrer 25, a dilute acid tank 26, a first circulation pump 27, and a plate heat exchanger 28.

In one embodiment, the desorption tower is used for removing SO dissolved in dilute acid₂。

In one embodiment, the dilute acid tank 26 is used as an intermediate tank for storing dilute acid produced by the pickling purification unit, and the dilute acid in the dilute acid tank 26 is sent to an acid water neutralization and clarification unit outside the device for uniform acid water treatment under the action of the dilute acid delivery pump 24.

In one embodiment, the packed cooling tower 16 is connected to a process water line to obtain cooling water.

In one embodiment, the packed cooling tower 16 is connected to the first circulation pump 27 and the plate heat exchanger 28, respectively, so that a cooling water circulation line is formed therebetween. Cooling water and SO-containing cooling water in packed cooling tower 16₂After the process gas exchanges heat, the temperature rises, the heated cooling water is discharged out of the filler cooling tower 16 and enters a cooling water circulation pipeline, the cooling water enters the plate heat exchanger 28 under the action of the first circulating pump 27 to exchange heat and reduce the temperature, and the cooled cooling water enters the filler cooling tower 16 again along the cooling water circulation pipeline.

In one embodiment, the drying unit includes a drying tower 40 and a blower 30, with SO-containing gas discharged from the acid cleaning unit₂The mixed gas of the process gas and the air can be dried in a drying tower 40 by concentrated sulfuric acid, and the dried mixed gas contains SO₂The water content of the mixed gas of the process gas and the air is 0.1g/Nm³Thereafter, under the action of a blower 30, enters the nitrogen oxide removal unit.

In one embodiment, the drying unit includes a first cooler 44, a first circulation tank 49, and a first circulation pump 55.

In one embodiment, the nitrogen oxide removal unit includes a denitrification reactor 37.

In one embodiment, a blower 30, a fifth heat exchanger 35, a sixth heat exchanger 36 and a first heat exchanger 31 are arranged between the drying tower 40 and the denitration reactor 37, and are connected in sequence.

In one embodiment, the SO is contained₂And air (SO)₂Concentration is about 7.6%), enters the air blower 30 for boosting pressure after being defoamed by the wire mesh demister of the drying tower 40, is sent into the SCR denitration reactor 37 for removing NOx after being subjected to heat exchange and temperature rise to 420 ℃ by the fifth heat exchanger 35, the sixth heat exchanger 36 and the first heat exchanger 31, and then enters the catalytic oxidation unit from the outlet of the denitration reactor 37.

In one embodiment, the catalytic oxidation unit includes a converter 29, SO₂A catalytic oxidation reaction takes place in the converter 29 to generate sulfur trioxide.

In one embodiment, a first heater 38 is disposed between the denitration reactor 37 and the converter 29, and the SO-containing gas involved in the reaction₂The furnace gas with air can be heated by the first heater 38 and enter the converter 29 for reaction after being heated.

In one embodiment, oxygen and SO are fed to the converter 29₂Volume ratio of

Is about 1.

In one embodiment, multiple catalyst beds are provided within the converter 29, such as a first catalyst bed, a second catalyst bed, a third catalyst bed, and a fourth catalyst bed.

In one embodiment, the catalytic oxidation unit comprises a second heat exchanger 32, a fourth heat exchanger 34 and a third heat exchanger 33 which are connected in sequence, and the second heat exchanger 32 is connected with the converter 29.

In one embodiment, a second heater 39 is provided between the second heat exchanger 32 and the converter 29.

In one embodiment, the first heater 38 and the second heater 39 can be electric heaters.

In one embodiment, the first heater 38 is connected to the I-section catalyst bed of the converter 29 and the second heater 39 is connected to the IV-section catalyst bed of the converter 29.

In an embodiment, the first section catalyst bed, the second section catalyst bed and the third section catalyst bed are respectively connected with the first heat exchanger 31, the second heat exchanger 32, the fourth heat exchanger 34 and the third heat exchanger 33, so that the first conversion can respectively pass through the reaction of the first section catalyst bed, the second section catalyst bed and the third section catalyst bed and the heat exchange of the first heat exchanger 31, the second heat exchanger 32, the fourth heat exchanger 34 and the third heat exchanger 33, and the conversion rate can reach about 97.5%.

In an embodiment, the structures of the six heat exchangers, such as the first heat exchanger 31 to the sixth heat exchanger 36, may be the same, and each of the six heat exchangers includes a first inlet, a second inlet, a first outlet, and a second outlet.

In one embodiment, the first heat exchanger 31 is connected to the I-section catalyst bed of the converter 29 through a first inlet, connected to the sixth heat exchanger 36 through a second inlet, connected to the denitration reactor 37 through a first outlet, and connected to the II-section catalyst bed of the converter 29 through a second outlet; the sixth heat exchanger 36 is connected with the outlet of the fifth heat exchanger 35 through a first inlet, is connected with the IV-stage catalyst bed layer of the converter 29 through a second inlet, is connected with the inlet of the fifth heat exchanger 35 through a first outlet, and is connected with the second inlet of the first heat exchanger 31 through a second outlet; the fifth heat exchanger 35 is connected to the blower 30 through a first inlet, to a first outlet of the sixth heat exchanger 36 through a second inlet, to a first inlet of the sixth heat exchanger 36 through a first outlet, and to the second absorption tower 43 through a second outlet.

In one embodiment, the second heat exchanger 32 is connected to the second stage catalyst bed of the converter 29 through a first inlet, connected to the outlet of the fourth heat exchanger 34 through a second inlet, connected to the second heater 39 through a first outlet, and connected to the third stage catalyst bed of the converter 29 through a second outlet; the fourth heat exchanger 34 is connected with the outlet of the third heat exchanger 33 through a first inlet, is connected with the III-section catalyst bed layer of the converter 29 through a second inlet, is connected with the inlet of the third heat exchanger 33 through a first outlet, and is connected with the second inlet of the second heat exchanger 32 through a second outlet; the third heat exchanger 33 is connected to the first outlet of the fourth heat exchanger 34 through the first inlet, connected to the first absorption tower 42 through the second inlet, connected to the first inlet of the fourth heat exchanger 34 through the first outlet, and connected to the nicotinic acid tower 41 and the first absorption tower 42 through the second outlet, respectively.

In one embodiment, the absorption unit is configured to absorb sulfur trioxide produced in the converter 29.

In one embodiment, the absorption unit includes a nicotinic acid tower 41, a first absorption tower 42, and a second absorption tower 43.

In one embodiment, the temperature of the process gas after the heat exchange in the catalytic oxidation unit reaction can be reduced to about 181 ℃, and then part of the process gas is sent to the nicotinic acid tower 41, and the rest part of the process gas is merged with the process gas at the outlet of the nicotinic acid tower 41 and then enters the first absorption tower 42, SO in the first absorption tower 42 is absorbed by the first absorption tower 42₃And the process gas is further demisted by a fiber demister at the top of the tower and then returns to the catalytic oxidation unit for secondary conversion.

In an embodiment, the process gas at the outlet of the first absorption tower 42 is heated by the third heat exchanger 33, the fourth heat exchanger 34 and the second heat exchanger 32, and then enters the IV-stage catalyst bed of the converter 29 for the second conversion, and the total conversion rate can reach more than 99.9%. The secondary reformed gas can be cooled to about 174 ℃ after heat exchange by the sixth heat exchanger 36 and the fifth heat exchanger 35, enters the second absorption tower 43, and SO in the secondary reformed gas is absorbed by the second absorption tower 43₃And the process gas is further demisted by a fiber demister at the top of the tower and then enters a tail gas treatment unit.

In one embodiment, the absorption unit comprises a nicotinic acid tower acid cooler 45, a first absorption tower acid cooler 46, a second absorption tower acid cooler 47, a finished product acid cooler 48, a nicotinic acid tower acid circulating tank 50, a first absorption tower acid circulating tank 51, a second absorption tower acid circulating tank 52, an acid mixing tank 53, an acid underground tank 54, a nicotinic acid tower acid circulating pump 56, a first absorption tower acid circulating pump 57, a second absorption tower acid circulating pump 58, an acid mixing tank pump 59, and an acid underground tank pump 60.

In one embodiment, the tail gas treatment unit is used for purifying the gas discharged from the absorption unit to avoid pollution caused by emission into the air.

In one embodiment, the tail gas treatment unit includes a desulfurization tower 61 and an electric demister 62. The tail gas at the outlet of the second absorption tower 43 enters a desulfurizing tower 61 and contacts with sprayed dilute sulfuric acid containing hydrogen peroxide to further remove SO₂And then the tail gas enters an electric demister 62 to remove entrained liquid drops, and then enters a chimney 63 to be discharged at high altitude up to the standard.

In one embodiment, the tail gas treatment unit comprises a chimney 63, a desulfurization tower circulating pump 64, a metering pump 65 and an intermediate tank 66, wherein the intermediate tank 66 is used for storing the tail gas treatment unit absorption medium.

The device or the method provided by the embodiment of the invention has the remarkable advantages of low operation cost, high operation elasticity, high stability, good environment-friendly effect and the like.

The device or the method provided by the embodiment of the invention has strong adaptability to the fluctuation of the flow, the composition, the concentration and the like of the waste sulfuric acid and the sulfur-containing waste liquid.

The device or the method provided by the embodiment of the invention can solve the problems that the waste heat recovery equipment is easy to corrode and block.

The device or the method of one embodiment of the invention can improve SO₂The concentration, the total gas amount of the process gas is greatly reduced, the size of equipment is reduced, and SO requirement is met₂The catalytic oxidation unit is self-heating balanced, thereby reducing the engineering investment and the operation cost.

The device or the method provided by the embodiment of the invention can solve the problems that NOx in the tail gas exceeds the standard and the acid quality is low.

The device or the method provided by the embodiment of the invention can effectively improve the driving rate of the device and ensure the long-period stable operation of the device.

Hereinafter, the apparatus and method for preparing sulfuric acid by cracking and regenerating waste sulfuric acid and/or sulfur-containing waste liquid according to an embodiment of the present invention will be further described with reference to specific examples. The raw materials used were all commercially available unless otherwise specified.