EA041439B1 - ACID GAS CLEANING - Google Patents

Description

According to this application in accordance with 35 USC. § 119 the priority of application no.

201810804898.6 for the grant of a Chinese patent (filing date 07/20/2018), which is thereby fully incorporated into the documents of this application.

The field of technology to which the invention belongs

The invention relates to the purification of acid gas containing sulfur compounds (such as hydrogen sulfide, sulfur dioxide, COS, CS ₂ , etc.) formed in technological processes carried out in the petrochemical, gas chemical, coal-chemical and other industries, with this purification is carried out by desulfurization (desulfurization) on the basis of ammonia. The invention particularly relates to an acid gas scrubbing process in which the scrubbing of the acid tail gas is carried out by desulfurization using ammonia, the aim being achieved in that the final tail gas satisfies the emission limits of harmful substances as a result of the absorption being carried out in a multi-stage circulation of the absorbent liquids; The invention relates in particular to acid gas treatment, in which the enthalpy value of the acid tail gas is first controlled by means of a control system, and then the acid tail gas is sent to a subsequent desulfurization process using ammonia. The invention furthermore relates to a corresponding acid gas treatment plant which can be used in the petrochemical, gas chemical, coal chemical and similar industries.

State of the art

Acid gas refers to a process gas containing, among other things, sulfur-containing substances such as hydrogen sulfide, sulfur oxides, sulfur of organic origin and the like, which were formed during the implementation of technological processes in the petrochemical, gas chemical, coal-chemical industries, in the oil and gas industries. - and the gas chemical industry associated with the processing of shale oil and gas, and similar industries. The harmful components in acid gas are mainly hydrogen sulfide, sulfur dioxide, COS, CS2, and the like. compounds with a high content of H2S (typically 70-95% in the petrochemical industry, 30%-80% in the gas chemical industry and 20%-50% in the coal chemical industry), and therefore they need to be purified to meet emission standards.

Various methods are known using various technologies for treating sour gas containing acid, such as conventional Claus technology plus absorption regeneration using hydrogenation reduction (Claus off-gas cleaning (SCOT) at low temperature), dry process for producing sulfuric acid, afterburning plus tail gas desulphurisation, wet sulfuric acid process, conventional Claus plus super Claus (euro-Claus), conventional Claus plus combustion plus tail gas desulfurization, conventional Claus plus catalytic oxidation, conventional Claus plus biological desulfurization, etc., with the Claus method plus absorption regeneration using hydrogenation regeneration being the most commonly used technology.

In the Claus sulfur recovery stage, 85-99% of the hydrogen sulfide is converted to sulfur and less than 15% of the sulfide is recovered by hydrogenation, absorbed and regenerated to produce H ₂ S, which is returned to the Claus sulfur recovery unit.

However, after the practical application of the aforementioned purification methods, acid gas still does not meet environmental standards sufficiently, so it cannot be directly emitted into the atmosphere, and additional purification of acid gas is necessary. Other well-known purification methods include tail gas desulfurization by alkaline method, tail gas biodesulfurization, use of the Cansol·v process, and the like. With more and more stringent regulations on sulfur emitted to the environment, mandatory sulfur recovery may reach 99.9% or more, and the concentration of sulfur oxide in the tail gas may be required to be controlled at 100 mg/Nm ³ or even was less than 50 mg/Nm ³ .

However, existing methods usually involve large investments, high operating costs and high concentrations of harmful impurities, or even difficulties in meeting emission standards, especially during start-up and shutdown periods of plants.

CN 200910188118, a Chinese patent, describes a process for desulfurizing a tail gas with a high concentration of sulfur dioxide, in which the desulfurization is carried out using sodium and the by-product sodium sulfite is recovered at the same time, while the tail gas is deoxidized before desulfurization. The concentration of sulfur dioxide in the tail gas before cleaning is in the range of 10000-100000 mg/m ³ , the concentration of oxygen is in the range of 2000-10000 mg/m ³ , the concentration of sulfur dioxide in the tail gas after cleaning is less than 200 mg/m ³ . Compared to the conventional method using sodium sulfite, the deoxidation step in this method requires the conversion of a portion of the sulfur dioxide into low concentration sulfuric acid, which is the product leaving the apparatus, and the recovery of sulfur dioxide in the tail gas is reduced. In addition, the known method is problematic for complete deoxidation, and the purity of the obtained sodium sulfite is low, in addition, this method causes a large investment and operating costs.

The Chinese Patent CN 200580011908.X discloses a biological desulfurization process that is used for biological desulfurization of the tail gas of a Claus process to produce a desulphurized tail gas and a sulfur product. The basic process is that the tail gas is introduced into an absorber where it is contacted with a poor solvent to obtain a desulfurized tail gas and a rich solvent; the rich solvent is introduced into a bioreactor in which the dissolved hydrogen sulfide undergoes bio-oxidation to produce a sulfur-containing product and a poor solvent. The content of hydrogen sulfide in the tail gas may be less than 10 ppm (ppm). This method is associated with large capital investment, cumbersome production process and waste liquid disposal, and it is difficult to maintain continuous and stable biological activity.

In the patent document US 5019361, a flow diagram of the Cansolv process is presented with the following parameters: sulfur dioxide concentration in the range 7x10 ^-4 -5x10 ^-3 , the mass concentration of the liquid containing organic amine is at least 20%, the temperature of the absorbing liquid is in the range 10-50 °C, the amount of sulfur dioxide absorbed per 1000 g of absorbent liquid is more than 100 g, the desorption temperature is in the range of 70-90°C, and 4-10 g of water vapor will be consumed to desorb 1 g of sulfur dioxide. This method is characterized by high capital investment, waste acid removal and high energy consumption.

CN 201210288895, a Chinese patent, describes a tail gas purification method using the Claus method in which a Claus tail gas containing sulfur dioxide, oxygen and water is continuously added to a reactor filled with a porous carbon desulfurizer; at a reaction temperature in the range of 30-150° C., sulfur dioxide and water in the tail gas undergo a catalytic oxidation reaction on the porous carbon surface to form sulfuric acid, and at the same time, a regeneration cleaning agent (detergent) is continuously introduced into the reactor. In this process, the desulfurization rate is up to 93%, and the output of the final residual gas cannot meet the high standards of environmental protection and protection, and it is difficult to use a low concentration sulfuric acid by-product. The tail gas of the multi-stage Claus process does not meet the requirements for vented gas.

Countries around the world emit sulfur dioxide to varying degrees. China's sulfur dioxide emissions are huge and have a significant impact on the environment and society. The total amount of sulfur dioxide emissions in 2014 was 19.74 million tons, and the total amount of sulfur dioxide emissions in 2015 was 18.591 million tons, while China ranks first in the world in these harmful emissions, which causes huge economic losses and seriously affects the environment and human health.

In connection with the above-mentioned shortcomings of known methods and the mass of pollution emitted into the atmosphere in the form of sulfur dioxide, which actually exists in China, various methods for desulphurization of residual gas are being developed. Currently, there are hundreds of desulfurization methods developed, among which the most widely used is the wet desulfurization process, which accounts for approximately 85% of the world's total installed desulfurization process capacity. Conventional tail gas wet desulphurization technologies include a limestone-gypsum method, a two-alkali metal compound method, a sodium carbonate method, an ammonia method, a magnesium oxide method, and the like. Ammonia desulphurization is a wet desulphurization process using ammonia as an absorbent, this method allows the production of ammonium sulfate fertilizers using SO2, and is an environmentally friendly off-gas treatment method, characterized by low energy consumption, high efficiency and recycling of material resources through recycling. Since chemical industry processes produce a large amount of available ammonia water, desulfurization using ammonia may be a desirable way to clean up tail gas in the chemical industry.

The desulfurization process using ammonia mainly includes three technological processes: absorption, oxidation and concentration (crystallization). First, sulfur dioxide is absorbed by ammonium sulfite to obtain a mixed solution of ammonium sulfite and ammonium hydrosulfite, and then neutralized by adding ammonia to obtain ammonium sulfite again:

(NH ₄ )2SO3+H2O+SO2=2NH ₄ HSO3 (NH ₄ )xH(2-x)SO3+(2-x)NH3=(NH ₄ )2SO3

- 2 041439

Oxidized air is introduced into this solution to oxidize ammonium (hydro) sulfite to obtain ammonium (hydro) sulfate:

(NH ₄ )2SO3+1/2O2=(NH ₄ )2SO4

The circulating absorbent liquid containing ammonium sulfate is subjected to concentration, crystallization, separation into liquid and solid phase, and drying to obtain the final product, ammonium sulfate.

Patent document CN 201310130225.4, under which a Chinese patent has been issued, discloses an off-gas treatment plant using ammonia and acid tail gas treatment methods, specifically comprising the following steps:

1) control of the concentration of sulfur dioxide in the tail gas to be introduced into the absorption column, at a level of <30,000 mg/Nm ³ ;

2) supplying process water or ammonium sulphate solution into the off-gas inlet pipe of the absorption column or inside the absorption column for spraying in order to reduce the temperature;

3) there is an oxidizing section in the absorption column, and an oxidant distributor is provided in the oxidizing section for carrying out the process of oxidizing the absorbing liquid of the desulfurization process;

4) an absorption section is placed in the absorption column, and an absorption liquid distributor is provided to carry out spray absorption in the desulfurization process using an absorption liquid containing ammonia in the absorption section; said absorbent liquid containing ammonia is added from the ammonia storage tank;

5) at the top of the absorption section in the absorption column, a wash water layer is formed, which flushes out the absorption liquid present in the residual gas to reduce the loss of the absorption liquid;

6) in the upper part of the wash water layer in the absorption column, a fog-dispersing device (heater) is placed to control the content of fog droplets in the purified tail gas; in the coal chemical industry, the use of integrated desulfurization technology, including Claus sulfur removal plus ammonia desulfurization, can reduce the investment cost of subsequent treatment, simplify the process flow, and this process is mainly applicable to acid gas treatment in the coal chemical industry industry, in which case it is necessary that the concentration of sulfur dioxide in the tail gas to be introduced into the absorption column be controlled at <30,000 mg/Nm ³ , while the requirements for other tail gas parameters, such as enthalpy and impurity content, not installed.

In the patent document CN 201410006886.0, according to which a Chinese patent was issued, a method for effectively purifying acid gas containing sulfide using ammonia desulphurization technology is described, including the following steps:

1) pre-treatment, in which the sulfide present in the acid gas is subjected to pre-treatment such as sulfur recovery, sulfuric acid production and/or combustion, and after that, the sulfur remaining in the acid gas is converted into sulfur oxides to produce an acid tail gas containing oxides of sulfur; source acid gas comes from enterprises of the petrochemical, gas chemical, coal-chemical industries and similar industries;

2) ammonia absorption of sulfur oxide, in which the acid tail gas containing sulfur oxides is sent to the ammonia absorber, where the sulfur oxides are absorbed by the circulating absorption liquid;

3) post-treatment from ammonium sulfate, during which the saturated or almost saturated absorbing liquid, which has completely absorbed sulfur oxides, is subjected to concentration, crystallization, liquid-solid separation, resulting in the product, solid ammonium sulfate.

Sulfur oxides (sulfur dioxide, sulfur trioxide and their hydrates) are removed from the acid tail gas; in addition, by-products are formed: sulfuric acid, sulfur and ammonium sulfate, and the purified gas is removed, in accordance with the established standards for emissions of harmful substances. The composition, density, circulation rate, or other parameters of the absorption liquid are adjusted according to different concentrations of sulfur oxide and the amounts of absorbed sulfur dioxide contained in the acid tail gas. If the concentration of sulfur oxide in the acid gas is less than 30,000 mg/Nm ³ , the acid gas is injected directly into the ammonia absorber without pre-treatment. This prior art method does not specify the enthalpy value and impurity content of the acid tail gas after pretreatment, as well as the treatment measures after the impurities enter the desulfurization system using ammonia.

In patent documents CN 201611185413.7, CN 201611185413.7 and CN 201810062243.6 also

- 3 041439 an attempt has been made to improve the purification of the acid tail gas by desulfurization using ammonia, but the described measures for improving the purification are still not perfect.

In addition, these publications did not note the control of the enthalpy value of the acid tail gas.

In view of the foregoing, it is desirable to determine more suitable acid tail gas parameters and further improve the efficiency of the desulfurization process. This will reduce the capital investment and operating cost of the ammonia desulfurization device, ensure a long period of stable operation of the device, and can achieve synergistic control of acid gas pretreatment and tail gas desulfurization with ammonia, improve ammonia recovery, and ensure production control. aerosol and improve the quality of the product.

Brief description of the figures

The objects and advantages of the invention will become apparent from the following detailed description of the invention, set forth in conjunction with the accompanying drawings, wherein like reference numerals refer to like elements throughout the drawings.

Fig. 1 is a schematic diagram of the installation according to example 1 in accordance with the essence of the present invention.

Fig. 2 is a block diagram of the installation according to example 2 in accordance with the essence of the invention.

Fig. 3 is a block diagram of a plant control system in accordance with the invention.

Item Reference List

- sour gas

- sulfur recovery system

- sulfur/sulfuric acid

- tail gas with recovered sulfur

- combustion system

- sour tail gas

- regulation system

- adjusted residual gas

- ammonia

- desulfurization system using ammonia

- ammonium sulfate

- clean residual gas

- sulfuric acid production system

- cooling device

- drying device (desiccant)

- device for removal of sulfur

- dust/impurity removal device

Detailed description of the invention

Definitions

The term ammonia recovery means that a fraction or fraction of the ammonia added to the gas cleaning process is subsequently captured and recovered from the process.

The term dust means material in the form of particles so small that they are carried away by gaseous streams during transportation, processing or contact. Said material includes, but is not limited to, aerosols, including solid aerosol particles and liquid aerosol particles, soot, coal dust, unburned coal, fines, sand, gravel, salts, and any combination of said material.

The term oxidation rate means the percentage, on a mole percentage basis, of a given material that has been converted to the identified more oxidized compounds of that material. For example, in a mixture containing compounds derived from ammonia and sulfur oxide, if X mol.% in the mixture corresponds to the content of ammonium sulfate, Y mol.% - the content of ammonium sulfite and Z mol.% - some other ammonia, sulfur and / or compounds containing oxygen having a greater oxidation potential than ammonium sulfate, since ammonium sulfate is the most oxidized compound identified, the oxidation state will be X mol%.

The term sulfur oxides or SO _X refers to chemical compounds containing sulfur and oxygen. The term includes compounds such as sulfur monoxide (SO), sulfur dioxide (SO ₂ ), sulfur trioxide (SO3), sulfur oxides with a higher oxidation state (SO3 and SO ₄ and their polymeric condensates), sulfur oxide sulfide (sulfur oxide (I )) (S2O), disulfo dioxide (dimeric sulfur monoxide) (S ₂ O ₂ ) and lower oxidation state sulfur oxides (S ₇ O ₂ , S ₆ O ₂ , and SnO _x , where n and x are any possible stoichiometric numerical values).

In the event that the above definitions or characteristics given elsewhere in this application do not correspond to the semantic content of the concept (explicitly or unconditionally), which

- 4 041439 is commonly used, listed in a dictionary or established in the source included in this description by reference, it must be taken into account that the description and terms used in the claims should be interpreted in accordance with the definition given in this application, or the description of this application, and not in accordance with the generally accepted definition given in the dictionary, or a definition that has been incorporated by reference. In the event that a term used in a formula can only be understood by a dictionary, the Kirk-Othmer encyclopedia definition is used. Encyclopedia of Chemical Technology, 5 ^th Edition, 2005, (John Wiley & Sons, Inc.) unless cited in that source.

The disclosure provides an acid gas treatment plant and methods designed to address some or all of the following prior art problems in using ammonia-based desulfurization for acid tail gas treatment: failure to achieve long term plant stability, poor product quality, difficulty in control leakage (loss) of ammonia and aerosol production. The proposed apparatus and method may also be directed to solving other problems not mentioned.

The acid gas treatment plant and methods may include the use of an ammonia-based desulfurization process to treat the acid tail gas, and may provide emissions-compliant final tail gas to the atmosphere by using multi-stage absorption with circulating absorption liquid and efficient acid tail gas treatment at low cost. In the present invention, the multi-stage absorption with circulating absorbent in an ammonia-based desulfurization process may include one or more cycles of a refrigeration cycle, an SO ₂ absorption cycle, and a water wash cycle.

It is preferable to control the enthalpy values of the acid tail gases obtained as noted above, first by means of a control system and then by feeding the acid tail gases into a subsequent ammonia-based desulfurization process.

The enthalpy value of the acid tail gas has an effect on the stable normalized (standardized) operation of the desulfurization device: if the enthalpy value is high and the absorption temperature is also high, ammonia leakage (loss) may be significant, and as a result, absorption efficiency cannot be guaranteed; at the same time, if the enthalpy value is low and the absorption temperature is low, the oxidation state of the circulating absorption liquid may be low, and therefore the post-treatment system may not work stably; moreover, since the tail gas with sulfur recovered may not be completely combusted in the combustion system, hydrogen sulfide has the property of being converted to sulfur in low temperature combustion, while hydrogen sulfide, elemental sulfur and organic matter, in turn, can affect the oxidation of sulfite ammonium and crystallization of ammonium sulfate, which leads to poor product quality. If it is desired to burn substantially all of the hydrogen sulfite, organics, and elemental sulfur present in the acid gas or sulfur recovered tail gas with the combustion system, it is necessary to increase the combustion process temperature to 1300°C or higher, and increase the air ratio to 1 ,8, and may need to increase the residence time to 7 s. However, this may increase the capital investment and operating cost of the combustion system, and increase the consumption of combustible gas; in addition, the combustion gases may have a high concentration of nitrogen oxides, and as a result, the investment in denitrification may be significant with high operating costs, and the content of nitrogen oxide in the final purified gas, of course, may not meet the established standards.

The enthalpy value of the acid tail gas should be properly controlled so that it is in the range of 60-850 kJ/kg dry gas before entering the desulfurization process using ammonia, e.g. 80-680 kJ/kg dry gas or 100-450 kJ/kg dry gas.

The control system may include a temperature control unit and/or a humidity control unit, or both of the aforementioned temperature control and humidity control units. The enthalpy value of the acid tail gas can be controlled by measuring the temperature and humidity of the acid tail gas that will enter the ammonia-based desulfurization process and adjusting the temperature and humidity of the tail gas accordingly by means of a control system.

An example of a formula for determining the enthalpy value of the residual gas:

H=(1.01 +1-88b)xt+2490b, where t is the temperature in °С, b is the concentration of water vapor in dry gas, measured in kg/kg of dry gas.

Those skilled in the art will appreciate that, depending on the various temperatures and humidity levels of the acid tail gas to be treated using the control system, the temperature control unit may respectively comprise a heating or cooling device, such as a heater or cooler or other temperature control means, in while the humidity control unit may respectively contain a moisturizing or

- 5 041439 a drying device, such as a device that can distribute nitrogen gas or carbon dioxide or add water vapor. Suitable devices for temperature control and humidity control are themselves well known to those skilled in the art.

The control system may further comprise one or more of a sulfur removal unit, a dust removal unit, and an impurity removal unit. In this case, the total dust content (particulate fraction) in the acid tail gas can be controlled by means of a control system, and the total dust content in the acid tail gas after regulation can be <200 mg/Nm ³ , for example < 50 mg/Nm ³ .

With the control system, the content of impurities in the acid tail gas can be controlled, and the content of organic impurities in the acid tail gas after regulation can be <30 ppm, for example, <10 ppm, and/or the content of elemental sulfur and hydrogen sulfide can be <30 ppm, for example <10 ppm.

The circulating absorbent liquid in a desulfurization process using ammonia may be subjected to treatment, after which the suspended matter content of the circulating absorbent liquid may be < 200 mg/l and/or the hydrocarbon (oil) content may be < 100 mg/l .

There are no particular restrictions on the source of acid tail gas that can be used in the proposed plant and methods, provided that they are commonly used in the petrochemical, petrochemical, coal chemical and similar industries. In this case, the acid tail gas may include, for example, tail gas obtained after processing acid gas produced in the petrochemical, gas chemical, coal chemical industries with a process such as sulfur recovery plus combustion, sulfuric acid production and combustion; or the acid tail gas may include, for example, be an off gas from a cracking catalyst regeneration process.

Sulfur recovery may include a sulfur recovery process such as a Claus sulfur recovery process by one to three process steps, a super-Claus sulfur recovery process, a Euro-Claus sulfur recovery process, a catalytic sulfur recovery process liquid phase, or biological sulfur recovery process; and the sulfuric acid production process can be carried out by a wet catalysis sulfuric acid production process (wet sulfuric acid process) or a dry catalysis sulfuric acid production process.

The molar ratio of H ₂ S/SO ₂ in the tail gas after sulfur recovery can be adjusted in the range of 1.2-3, for example 1.5-2.5.

In the process of sulfur recovery with subsequent combustion and in the combustion process, the combustion temperature can be 600°C-1300°C, for example 650°C-950°C, while the duration of the combustion process can be 1-6 s, for example 1.5-4 c, the oxygen content of the acid tail gas may be 2-5%, eg 3-4%, and the sulfur oxide content of the acid tail gas may be 2000-150000 mg/Nm ³ , eg 5000-55000 mg/Nm ³ .

The method may include the following process steps:

1) the acid gas is purified by sulfur removal plus combustion, or by the production of sulfuric acid, or by combustion, or directly in the catalytic cracking catalyst regeneration process to produce an acid tail gas;

2) acid tail gas is sent to a control system to control the enthalpy value of the tail gas so that it is in the range of 60-850 kJ/kg dry gas, for example, 80-680 kJ/kg dry gas or 100-450 kJ/kg;

3) The sour tail gas that meets the enthalpy requirement is sent to the ammonia-based desulfurization purification process, so that the pure tail gas meets the emission standards after passing through the multi-stage absorption with circulating absorption liquid.

The acid tail gas obtained in step 2) can be further treated in the control system so that the total dust concentration is <200 mg/Nm ³ and/or the organic content is <30 ppm and/or the elemental sulfur content is <30 ppm before feed into the ammonia-based desulfurization process.

The unit may include an acid gas scrubber including an acid gas pre-treatment system and an ammonia desulfurization system.

The acid gas pretreatment system may comprise one or more of a sulfur recovery system with a combustion system, a sulfuric acid production system, a combustion system, and a catalytic cracking catalyst regeneration system. The ammonia desulfurization system may be a conventional ammonia desulfurization apparatus, and its structure may be known from the prior art, for example, from CN 201710379460.3, CN 201810057884.2, which are incorporated herein by reference in their entirety. (The indicated applications are submitted by the applicant).

The sulfur recovery system may include one or more of a Claus sulfur recovery system with one to three process steps, a super-Claus sulfur recovery system, a Euro-Claus sulfur recovery system, a liquid phase catalytic oxidation, or a system using biological sulfur recovery.

The installation may include a control system containing a temperature control device and/or a humidity control device, or both of these temperature and humidity control devices. The control system may include one or more of a sulfur recovery device, a dust recovery device, and an impurity recovery device.

The acid gas pretreatment system, the control system and the desulfurization system using ammonia can be connected in series. The acid gas pretreatment system may comprise a sulfur recovery system plus a combustion system. The control system may include one or more of a temperature control device, a humidity control device, and an impurity recovery device that can be connected to each other in series in any order, or one or more of an impurity recovery device, a temperature control device, a humidity control device, and impurity extraction devices that can be connected to each other in series in any order.

The plant may comprise an absorbent liquid cleaning system, which may include one or more of a concentration device, a liquid/solid separation device, and a drying device.

The absorbent liquid purification system may comprise one or more of a solution purification device and an evaporative crystallization device. The solution cleaning device may comprise one or more of a hydrocarbon recovery device and a particulate matter recovery device. The suspended matter recovery device may be configured to provide a circulating absorbent liquid with a suspended matter content of <200 mg/L, 20-100 mg/L, or 30-50 mg/L.

The hydrocarbon recovery device may be configured to provide a circulating absorbent liquid with a hydrocarbon content of <100 mg/l, such as 10-80 mg/l or 20-30 mg/l. The hydrocarbon recovery device may comprise one or more of an air flotation device, an absorption device, or a fine filter device, or combinations of these devices.

The hydrocarbon recovery device may be connected to a combustion system.

The acid gas vented from the petrochemical industry can be subjected to a sulfur recovery plus combustion process (pre-treatment) to produce an acid tail gas, and thereafter, the enthalpy value of the acid tail gas, before it is fed to the ammonia-based desulfurization process, can be controlled with with the help of a regulatory system. In this case, the multi-stage circulating absorption may include a single-stage refrigeration cycle, a two-stage SO ₂ absorption cycle, and a single-stage water washing cycle.

The control system may include one or more of a temperature control unit, a humidity control unit, and a sulfur recovery unit that are connected in series. The acid tail gas enthalpy value can be adjusted first to 560-720 kJ/kg dry gas with a cooling device and then low temperature low enthalpy gas containing nitrogen can be added with a drying device to further control the acid tail gas enthalpy value to 440 -530 kJ/kg of dry gas. Thereafter, the content of elemental sulfur and hydrogen sulfide in the acid gas can be adjusted and controlled at 4-7.5 ppm using a sulfur recovery absorption device.

The content of hydrogen sulfide in the acid gas may be, for example, approximately 90%, the rest being nitrogen, carbon dioxide, and the sulfur recovery system for acid gas treatment may include a 3-stage Claus sulfur recovery process using air. The molar ratio of H2S/SO2 in the tail gas after sulfur recovery can be controlled at 1.7-2.8, while the combustion temperature in the combustion system can be in the range of 850°C950°C, the duration of the combustion process is 2-4 s, the content oxygen in the tail gas may be approximately 3%, and the content of sulfur oxide in the combusted tail gas may be in the range of 12000-15000 mg/Nm ³ .

For an exemplary tail gas flow rate of 46,000 Nm ³ /h, the sulfur recovery rate can be 96%, the annual operation time can be 8400 h, and after cleaning, 477,000 tons of sulfur per year and 80,500 tons of ammonium sulfate per year can be obtained.

If the control system is not used to control the content of organic matter in the acid tail gas, the circulating absorption liquid of the desulfurization process,

- 7 041439 using ammonia, can be treated by hydrocarbon recovery to reduce the hydrocarbon content of the circulating absorption liquid to <50 mg/l.

An exemplary acid gas treatment plant may comprise one or more of an acid gas pretreatment system (sulfur recovery plus combustion system), a control system, and an ammonia-based desulfurization system.

The sulfur recovery system may include a device for conducting a thermal reaction (thermal stage) and a subsequent 3-stage catalytic reaction according to the Claus method, while the device for sulfur recovery by Claus catalytic reduction can be a device for sulfur recovery, which is not loaded with a hydrolysis catalyst .

The control system may include one or more of a temperature control device, a humidity control device, and a sulfur recovery device that are connected in series.

The sulfur recovery system, the combustion system, the control system and the ammonia desulphurization system used for acid gas purification can be connected in series. The temperature control device may be a two-stage flue gas heat recovery device, wherein the by-product of the first flue gas heat recovery stage may be saturated steam, and the second flue gas heat recovery stage may use heated boiler feed water; the humidity control device may comprise a nitrogen gas distribution device.

The plant may include an absorbent liquid cleaning system, which plant may include one or more of a concentration device, a solid-liquid separation device, and a drying device.

The absorbent liquid cleaning system may include a solution cleaning device. The solution cleaning device may be a hydrocarbon recovery device which may be configured to use a circulating absorbent liquid with a hydrocarbon content of <50 mg/L. The hydrocarbon recovery device may include an air flotation device plus a fine filter.

The hydrocarbon recovery device may be connected to the combustion system, and the spent hydrocarbons in the combustion system may be completely converted into water, carbon dioxide and sulfur dioxide by the combustion process.

With regard to the apparatus and methods of the present invention, a number of published patent documents relating to ammonia-based desulfurization can be mentioned, in particular patent documents CN 200510040801.1, CN 03158258.3, CN 201010275966.8, CN 200510040800.7, CN 03158257.5 and the like, and the like can also be mentioned. applications under examination: CN 201710379460.3, CN 201710379458.6, CN 201710154157.3, CN 201710800599.0, CN 201710865004.X and CN 201810329999.2.

Compared to the prior art acid gas purification process by determining the acid tail gas control parameters, using pre-treatment plus control plus ammonia-based desulfurization for acid gas purification, in particular, control of the acid tail gas enthalpy value, the proposed plant and methods can provide lower investment and operating costs in the ammonia desulfurization system, stable long-term operation, synergistic control of pretreatment and acid tail gas desulphurization, can increase ammonia recovery, control aerosol production and improve product quality.

The present invention provides an apparatus and methods for purifying acid gas. The plant may comprise, and the methods may include, the use of an acid gas pretreatment system and an ammonia-based desulfurization system that is in fluid communication with said acid gas pretreatment system.

The pretreatment system may include one or more of a sulfur recovery plus combustion system, a sulfuric acid production system, and a catalytic cracking process catalyst regeneration system. The sulfur recovery system may include a Claus sulfur recovery system. The Claus sulfur recovery system may be a single-stage Claus sulfur recovery system. The Claus sulfur recovery system may be a two-stage Claus sulfur recovery system. The Claus sulfur recovery system may be a three-stage Claus sulfur recovery system.

The sulfur recovery system may be a system for recovering sulfur by liquid phase catalytic oxidation. The sulfur recovery system may be a biological sulfur recovery system.

The sulfur recovery system may include, in fluid communication with the Claus sulfur recovery system, a super Claus sulfur recovery system.

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The sulfur recovery system may include, in fluid communication with the Claus sulfur recovery system, the Euro-Claus sulfur recovery system.

The sulfur recovery system may include, in fluid communication with the Claus sulfur recovery system, a biological sulfur recovery system.

The sulfur recovery system may include, in fluid communication with the Claus sulfur recovery system, a sulfur recovery system by liquid phase catalytic oxidation.

The plant may include a control system that is upstream of the ammonia desulfurization system and is in fluid communication with it. The control system may include a temperature controller that provides in the specified control system the ability to control the temperature of the gas. The control system may include a humidity controller that enables said control system to control the humidity.

The plant may include a sulfur recovery device that is in fluid communication with an ammonia desulfurization system. The plant may include a pulverized fraction recovery device that is in fluid communication with an ammonia desulfurization system.

The plant may include an impurity recovery device that is in fluid communication with an ammonia desulfurization system.

The plant may include a sulfur recovery device that is in fluid communication with the ammonia desulfurization system and a dust recovery device that is in fluid communication with the ammonia desulfurization system.

The plant may include a sulfur recovery device that is in fluid communication with the ammonia desulfurization system and an impurity recovery device that is in fluid communication with the ammonia desulfurization system.

The plant may include a dust recovery device that is in fluid communication with the desulfurization system using ammonia and an impurity recovery device that is in fluid communication with the desulfurization system using ammonia.

The acid gas pretreatment system, the control system and the desulfurization system using ammonia can be connected in series along the direction of flow of the gas to be treated.

The acid gas pretreatment system may comprise a sulfur recovery system plus a combustion system.

The plant may include a control system that is in fluid communication with the ammonia desulfurization system and is upstream of the desulfurization system. The control system may include a temperature controller that enables the control system to control the temperature of the gas. The control system may include a humidity controller that enables the control system to control the humidity of the gas.

The plant may include a sulfur recovery device that is in fluid communication with an ammonia desulfurization system.

The acid gas pre-treatment system, the control system, and the ammonia desulfurization system may be connected in series in the downstream direction.

The acid gas pretreatment system may comprise a sulfur recovery system plus a combustion system. In a control system, a temperature controller, a humidity controller, and a sulfur recovery device may be connected in series in a downstream direction. In the control system, the temperature controller, the humidity controller and the sulfur recovery device are connected in series in the downstream direction.

The ammonia desulfurization system may be configured to circulate an absorbent liquid containing ammonia; and may comprise an absorbent liquid purification system, which may include one or more of a concentration device capable of receiving an absorbent liquid, a liquid-solid separation device configured to capture solids suspended in the liquid; and a drying device for drying the trapped solids.

The absorbent fluid purification system may include a solution purification device that is in fluid communication with a liquid-solid separation device located downstream during operation of the system. The absorbent liquid purification system may include an evaporative crystallization device that can be in fluid communication with one or both of the concentration device and the liquid-solid separation device; and can be placed downstream relative to the device for concentration and upstream relative to the device for

- 9 041439 separation of liquid and solid phase.

The absorbent liquid purification system may include an evaporative crystallization device that can be in fluid communication with one or both of the concentration device and the liquid-solid separation device; and can be placed downstream of the concentration device and upstream of the liquid-solid separation device during operation.

The solution cleaning device may comprise a hydrocarbon recovery device that is in fluid communication with the liquid/solid separation device.

The device for cleaning the solution may include a device for removing suspended matter, which is in fluid communication with the device for separating liquid and solid phase.

The device for cleaning the solution may include a device for removing suspended matter, which is in fluid communication with the device for separating liquid and solid phase.

In the suspended matter recovery device, an absorbent liquid can be circulated in which the suspended matter content is not more than 200 mg/L. The content of suspended matter can be in the range from 20 to 100 mg/l. The content of suspended matter can be in the range from 30 to 50 mg/l.

The hydrocarbon recovery device may include an air flotation device that is in fluid communication with the liquid-solid separation device.

The hydrocarbon recovery device may comprise an adsorption device that is in fluid communication with the liquid/solid separation device.

The hydrocarbon recovery device may include a precision filter that is in fluid communication with the liquid/solid separation device.

The hydrocarbon recovery device may comprise an adsorption device that is in fluid communication with the liquid/solid separation device.

The hydrocarbon recovery device may include a precision filter that is in fluid communication with the liquid/solid separation device.

The hydrocarbon recovery device may further comprise a precision filter that is in fluid communication with the liquid/solid separation device.

The hydrocarbon recovery apparatus may be configured to provide a circulating absorption liquid having a hydrocarbon content of at most 100 mg/L. The content of hydrocarbons can be in the range from 10 to 80 mg/l. The hydrocarbon content may be in the range of 20 to 30 mg/L. The hydrocarbon recovery device may be in fluid communication with the combustion system and during operation it is upstream of said combustion system. The processes may include receiving the acid gas and generating from the acid gas one or both of ammonium sulfate and a final tail gas that meets environmental regulations for air pollutant emissions. Said environmental regulations may be those set forth in the document entitled Emission Standard of Pollutants for Petroleum Refining Industry, published in China, GB31570-2015, which is incorporated herein by reference in its entirety.

The emission standards may be the standards set in the document entitled Emission Standard of Pollutants for Petroleum Refining Industry, published in China, GB31570-2015, which is incorporated herein by reference in its entirety.

Illustrative Examples of Pollution Emission Standards

Emission standards for atmospheric pollutants in the oil refining industry. Tab. The tables 1, 2 below show the emission standards for reclaimed off-gases from process heating furnaces, off-gases from the catalyst regeneration process of fluid catalytic cracking (FCC) units, particulate matter present in tail gas from acid gas recovery plants, nickel and its compounds, sulfur dioxide and sulfuric acid mist.

From the Oil Refinery Emission Standards.

- 10 041439

Table 1. Specific emission limits for air pollutants (unit: mg/m ³ )

Number pollution Acid gas recovery devices Location of the Pollutant Emission Monitoring Device 1 particulate matter — Outlet pipeline of workshop or production equipment 2 nickel and its compounds — 3 sulfur dioxide 400 4 nitrogen oxides 5 sulfuric acid mist 30(4) 6 hydrogen chloride — 7 pairs of pitch — 8 benzo[a]pyrene — 9 benzene — 10 toluene — AND xylene — 12 non-methane hydrocarbons —

From the Oil Refinery Emission Standards.

Table 2. Specific emission limits for air pollutants (unit: mg/m ³ )

Number pollution Process heating furnace Off-gases (1) of the catalyst regeneration process of a fluidized-bed cracker Acid gas recovery devices Location of device for monitoring pollution emissions 1 particulate matter missing thirty — Outlet pipeline of workshop or production equipment 2 nickel and its compounds — 0.3 — 3 sulfur dioxide 50 50 100 4 nitrogen oxides 100 100 — 5 sulfuric acid mist — — 5(3) 6 hydrogen chloride — — — 7 pairs of pitch — — — 8 benzo[a]pyrene — — — 9 benzene — — — 10 toluene — — — eleven xylene — — — 12 non-methane hydrocarbons — — —

Remarks (1) The maximum concentration of contaminants in the regenerated off-gases passing through the catalytic cracking off-gases recovery unit shall not exceed 2 times the limit value in the table below, and the time duration shall not exceed 1 hour each time.

Emission standards for air pollutants in the petrochemical industry. Tab. 3 and 4 below show the emission requirements for particulate matter and sulfur dioxide present in the tail gas of a process carried out in a process heating furnace.

From the Oil Refinery Emission Standards.

T able 3. Emission limits for air pollutants (part) (unit: mg/m ³ )

Number pollution Process heating furnace Location of device for monitoring pollution emissions 1 particulate matter 20 Outlet pipeline of workshop or production equipment 2 sulfur dioxide 100 3 nitrogen oxides 150 180(3)

From the Petrochemical Air Pollutant Emission Standards.

- 11 041439

Table 4. Specific emission limits for air pollution (part) (unit: mg/m ³ )

Number pollution Process heating furnace Location of device for monitoring pollution emissions 1 particulate matter 20 Outlet pipeline of workshop or production equipment 2 sulfur dioxide 50 3 nitrogen oxides 100

The recovery process may include one or both of recovering the sulfur from the acid gas to produce tail gas with the recovered sulfur, and then flaring the gas after the sulfur is recovered.

Recovery may include obtaining sulfuric acid from acid gas.

Recovery may include incineration.

The method may include transporting the acid gas through a pipeline after a chemical reaction has taken place in a petrochemical plant. The method may include transporting acid gas through a pipeline after a chemical reaction in the processing of natural gas. The method may include pipeline transportation of acid gas after chemical reaction with coal.

The recovery process may include the generation of off-gas during the regeneration of the catalyst used in catalytic cracking. The acid tail gas may be an off gas from the regeneration process.

The recovery process may include adjusting the enthalpy value of the acid tail gas.

The recovery may include passing a controlled tail gas through one or more of a cooling stage, an absorption stage and a water washing stage, all of these stages being located in a desulfurization reactor with circulating ammonia.

The control may include changing the temperature of the acid tail gas.

The adjustment may include changing the moisture content of the acid tail gas.

The control may include changing the temperature of the acid tail gas.

The regulation may include the recovery of sulfur from the sour tail gas.

The control may include the removal of dust from the sour tail gas.

The control may include the removal of impurities from the sour tail gas.

The adjustment may include adjusting the enthalpy value of the acid tail gas to a value of 60-850 kJ/kg dry gas. The regulation may include adjusting the enthalpy value to a value of 80-680 kJ/kg of dry gas. The regulation may include adjusting the enthalpy value to a value of 100-450 kJ/kg of dry gas.

The recovery may involve passing the acid gas through a single stage Claus sulfur recovery system. The recovery may involve passing the acid gas through a two-stage Claus sulfur recovery system. The recovery may involve passing the acid gas through a Claus sulfur recovery system containing three stages.

The recovery may involve passing the acid gas through a sulfur recovery system using a liquid phase catalytic oxidation technique. The recovery process may include passing acid gas through a biological sulfur recovery system. Recovery may involve passing acid gas through a super-Claus sulfur recovery system. The recovery may involve passing the acid gas through a Euro-Claus sulfur recovery system. The recovery may further include passing the acid gas through the biological sulfur recovery system. The recovery may involve passing the acid gas through a sulfur recovery system by catalytic liquid phase oxidation.

The production of sulfuric acid may include the production of sulfuric acid by wet catalysis. The production of sulfuric acid may include the production of sulfuric acid by dry catalysis.

The recovery process may include producing a sulfur-recovered gas having an H2S/SO2 molar ratio in the range of 1.2 to 3. Said molar ratio may be in the range of 1.5 to 2.5.

Combustion can be carried out at a temperature in the range from 600 to 1300°C. As a result of combustion, sour tail gas can be produced.

When burning acid gas with extracted sulfur, the duration of the combustion process can be 1-6 s.

The acid tail gas may have an oxygen concentration in the range of 2-5%.

The acid tail gas may have a sulfur oxide concentration in the range of 2,000 to 150,000 mg/Nm ³ . The combustion process can be carried out at a temperature in the range from 650 to 950°C.

When burning acid gas with extracted sulfur, the duration of the combustion process can be 1.5-4 s.

The oxygen concentration in the acid tail gas may be in the range of 3-4%.

- 12 041439

The acid tail gas may have a sulfur oxide concentration in the range of 5000 to 55000 mg/Nm ³ .

The method may include the production of an acid tail gas with a sulfur oxide concentration in the range from 2000 to 150000 mg/Nm ³ .

Combustion can be carried out at a temperature in the range from 600 to 1300°C. As a result of combustion, sour tail gas can be produced.

The method may include the combustion of tail gas with recovered sulfur at a combustion process duration of 1-6 seconds.

The acid tail gas may have an oxygen concentration in the range of 2-5%.

Combustion can be carried out at a temperature in the range from 650 to 950°C.

When burning residual gas with extracted sulfur, the duration of the combustion process can be 1.5-4 s.

The acid tail gas may have an oxygen concentration in the range of 3-4%.

The acid tail gas may have a sulfur oxide concentration in the range of 5000 to 55000 mg/Nm ³ .

The method may include obtaining an acid tail gas with an oxygen concentration in the range of 2-5%.

The acid tail gas may have a sulfur oxide concentration in the range of 2,000 to 150,000 mg/Nm ³ .

The combustion can be carried out at a temperature in the range from 600°C to 1300°C. As a result of combustion, sour tail gas can be produced.

When burning tail gas with recovered sulfur, the duration of the combustion process can be 1-6 s.

Combustion can be carried out at a temperature in the range from 650 to 950°C.

When burning residual gas with extracted sulfur, the duration of the combustion process can be 1.5-4 s.

The acid tail gas may have an oxygen concentration in the range of 3-4%.

The acid tail gas may have a sulfur oxide concentration in the range of 5000 to 55000 mg/Nm ³ .

When burning tail gas with recovered sulfur, the duration of the combustion process can be 1-6 s.

The method may include obtaining an acid tail gas with an oxygen concentration in the range of 2-5%.

The method may include obtaining an acid tail gas having a sulfur oxide concentration in the range from 2000 to 150000 mg/Nm ³ .

The combustion can be carried out at a temperature in the range from 600°C to 1300°C. As a result of combustion, sour tail gas can be produced.

Combustion can be carried out at a temperature in the range from 650 to 950°C.

When burning residual gas with extracted sulfur, the duration of the combustion process can be 1.5-4 s.

The acid tail gas may have an oxygen concentration in the range of 3-4%.

The concentration of sulfur oxide in the acid tail gas can be in the range from 5000 to 55000 mg/Nm ³ .

Recovery may include reducing the suspended solids content of the circulating absorbent liquid of the desulfurization process using ammonia to a level of no more than 200 mg/L.

The recovery may include reducing the hydrocarbon content of the circulating absorbent liquid of the desulfurization process using ammonia to a level of not more than 100 mg/l.

The recovery may include reducing the hydrocarbon content of the circulating absorbent liquid of the desulfurization process using ammonia to a level of not more than 100 mg/L.

The control process can provide tail gas with an organic content of no more than 30 ppm.

The control process can provide a regulated tail gas having an elemental sulfur and hydrogen sulfide content of not more than 30 ppm.

The control process can provide a regulated tail gas having an organic content of not more than 10 ppm.

The control process can provide a regulated tail gas having an elemental sulfur and hydrogen sulfide content of not more than 10 ppm.

The acid gas can be treated by sulfur recovery plus combustion or sulfuric acid production or combustion, or directly in the process of regenerating the catalyst used in the catalytic cracking process to produce an acid tail gas.

The sour residual gas can be sent to a control system to control the enthalpy value of the residual gas so that it is in the range of 60-850 kJ/kg dry gas, for example, in the range of 80-680 kJ/kg dry gas or 100-450 kJ/kg of dry gas.

An acid tail gas that satisfies the selected enthalpy criterion can be sent to an ammonia-based desulphurization process for purification, ensuring that the final tail gas meets emission limits from multi-stage circulating absorption.

Some embodiments may not include features shown and/or described in conjunction with an exemplary setup. Some embodiments may include features that are not shown and/or described in conjunction with the exemplary setup. Features characterizing the exemplary plant and methods may be combined. For example, one illustrative embodiment may include features disclosed in relation to another illustrative embodiment.

The steps of the exemplary methods may be performed in a different order than the order shown and/or set forth herein. In some embodiments, steps shown and/or disclosed with respect to illustrative methods may be omitted. Some embodiments may include steps that are not shown or described in relation to the exemplary methods. The steps of the exemplary method may be combined. For example, one exemplary method may include the steps disclosed in relation to another exemplary method.

Embodiments may include all or some of the features of the exemplary apparatus and/or some or all of the steps of the exemplary methods.

The setup and methods described herein are illustrative. The installation and methods in accordance with the invention will now be disclosed in the examples and figures that are part of these examples. The figures depict the characteristic features of the installation and the steps of the methods in accordance with the principles of the present invention. It should be understood that other embodiments may be used and structural, functional and manufacturing modifications may be made without departing from the scope and spirit of the present invention.

Illustrative examples

Example 1

Acid gas 1 was used, coming from an acid gas source, a petrochemical industry. The sour gas 1 was passed through the sulfur recovery system 2 to produce a tail gas 6 with sulfur recovered, then the resulting gas was passed through the combustion system 5 to produce an acid tail gas 6 (pretreatment system). The enthalpy value of the acid tail gas was controlled by the control system 7, and then the enthalpy-adjusted tail gas 8 was sent to the ammonia-based desulfurization system 10, into which ammonia 9 was introduced. ammonia, included one stage of the cooling cycle, two stages of the SO ₂ absorption cycle and two stages of washing with water.

The control system 7 used in this example, shown in FIG. 3 included an impurity recovery device 17, a cooling device 14, a drying device 15, and a sulfur recovery device 16, which are connected in series. The content of organic matter in the acid tail gas was reduced to 4.5 ppm or less using the impurity recovery device 17, and the enthalpy value of the acid tail gas 6 was further adjusted to 600-810 kJ/kg dry gas through the cooling device 14, and then a low temperature gas containing carbon dioxide with a low water vapor content was added through the dryer 15 to further adjust the enthalpy value of the acid tail gas 6 to 410-505 kJ/kg dry gas. Then, the content of elemental sulfur and hydrogen sulfide (hydrogen sulfide) in the adjusted tail gas 8 was adjusted to 3 ppm or less by adsorbing sulfur and hydrogen sulfide in the tail gas through the sulfur recovery adsorption device 16 .

In this example, the content of hydrogen sulfide in acid gas 1 was 75%, the rest was nitrogen, carbon dioxide, hydrogen and carbon monoxide; the sulfur recovery system 2 was adapted to carry out a two-stage Claus sulfur recovery process using air. The molar ratio of H2S/SO2 in the residual gas 4 with recovered sulfur was controlled at the level of 1.4-2.2, the combustion temperature in the combustion system 5 was in the range from 750°C to 810°C, the gas residence time in the combustion system was 2- 2.8 s, the oxygen concentration in the acid tail gas was 2.8%, and the sulfur oxide concentration was 22400 mg/Nm ³

The consumption of acid gas 1 was 8100 Nm ³ /h, the annual operation time of the plant was 8400 h, the recovery rate was 93.6%, while 68200 tons of sulfur 3 were obtained per year and 19000 tons of ammonium sulfate 11 per year, the recovery rate of ammonia amounted to 99.1%.

Accordingly, the installation for carrying out the above purification method in this example includes an acid gas pre-treatment system (which includes a sulfur recovery system plus a combustion system), a control system, and an ammonia-using desulfurization system, which are connected in series.

- 14 041439

The sulfur recovery system includes blowers, a thermal reaction device, and a Claus two-stage catalytic reaction device.

In addition, the control system included an impurity removal device, a cooling device, a drying device, and a desulfurization device connected to each other in series. The impurity recovery device was a device for carrying out catalytic oxidation, an absorption device using activated carbon was used as a desulfurization device, one-stage waste heat recovery was used in a cooling device, and a by-product was obtained in the form of saturated water vapor with pressure of 0.3-0.5 MPa, and the drying device was connected to a source of carbon dioxide gas.

The installation included a system for cleaning the absorbing liquid, which contained a tank for concentration in the liquid circulation process, a device for separating the liquid and solid phase, and a drying device. The ammonia-based desulfurization system used a saturation crystallization process implemented in a column.

The flow rate of the adjusted residual gas was 68450 Nm ³ /h (standard conditions, calculation based on wet gas, actual oxygen content), the SO2 concentration was 16100 mg/Nm ³ , the diameter of said column was 3.2 m, the height was 42 m, the concentration of sulfur dioxide in the residual gas obtained was 32.4 mg/Nm ³ , the concentration of free ammonia was 1.3 mg/Nm ³ , the total content of the pulverized fraction was 9.5 mg/Nm ³

With respect to the ammonia-based desulfurization plant and processes discussed in this example, reference may be made to the relevant patent documents CN 201710379460.3, CN 201710865004.X and CN 201810329999.2.

Example 2

Was used acid gas 1, obtained at the enterprise of the gas chemical industry. The sour gas 1 was passed through the sulfuric acid production system 13 to produce sulfuric acid 3 and an acidic tail gas 6, and then the enthalpy value of the acid tail gas was adjusted using the control system 7. After that, the adjusted tail gas was sent to the ammonia desulfurization system 10 into which ammonia was introduced 9. The multi-stage absorption in the circulating absorption liquid mode of the desulfurization system using ammonia 10 included one stage of a cooling cycle, one stage of an SO ₂ absorption cycle, and one stage of washing with water.

In this example, a device for additional introduction of water vapor was included in the control system 7, and the enthalpy value of the acid tail gas 6 was adjusted to a level of 320-410 kJ/kg of dry gas by adding water vapor.

In the acid gas 1 used in this example, the hydrogen sulfide content was 45%, the CO ₂ content was 30%, and the balance was nitrogen, hydrogen, carbon monoxide and methane. The sulfuric acid production system 13 used a wet catalysis sulfuric acid production process. The content of sulfur oxide in the acid tail gas was 5350 mg/Nm ³ .

The consumption of acid gas 1 was 7200 Nm ³ /h, the recovery rate of sulfuric acid was 98%, the annual operation time was 8400 hours, while 119000 tons of sulfuric acid 3 per year and 3200 tons of ammonium sulfate 11 per year were obtained, the recovery rate of ammonia amounted to 99.4%.

Accordingly, the apparatus for carrying out the above purification method in this example included a wet catalysis sulfuric acid production system, a control system, and an ammonia-based desulfurization system connected in series.

The wet catalysis sulfuric acid production system included a combustion device, a conversion device and a condensation device.

The control system included a device for adding water vapor.

The installation included a system for cleaning the absorbing liquid, a device for separating liquid and solid phases, and a drying device. The ammonia-based desulfurization system used a saturation crystallization process implemented in a column.

The flow rate of the adjusted residual gas was 38450 Nm ³ /h (standard conditions, wet basis, actual oxygen content), the concentration of SO ₂ was 4830 mg/Nm ³ , the diameter of said column was 2.6 m, the height was 33 m, the concentration of sulfur dioxide in the obtained residual gas was 16.8 mg/Nm ³ , the concentration of free ammonia 0.6 mg/Nm ³ , the total dust content of 4.5 mg/Nm ³ .

With regard to the desulfurization plant using ammonia and the methods used in this example, reference may be made to the relevant patent documents CN 201710379460.3, CN 201710865004.X and CN 201810329999.2.

Example 3

Was used acid tail gas obtained from the regeneration of the catalyst in the process of catalytic cracking carried out at the petrochemical industry. The enthalpy value of the acid tail gas was controlled by a control system, and then the acid tail gas was sent to an ammonia-based desulfurization system. The multi-stage absorption with circulating absorbent liquid in the desulfurization system included a two-stage wash cycle, a one-stage SO2 absorption cycle, and a one-stage water wash cycle.

The control system included a cooling device, a pulverized fraction extraction device, and an impurity removal device. The impurity recovery device was able to reduce the organic matter content to 6.2 ppm or less. The enthalpy value of the acid tail gas was further adjusted to 370-408 kJ/kg dry gas using a cooling device. After that, using a dust extractor, the content of the dust fraction was reduced to 20-30 mg/Nm ³ .

The flow rate of the acid tail gas 1 was 210,000 Nm ³ /h, the sulfur oxide content was 2350 mg/Nm ³ , and the total dust content was 100-230 mg/Nm ³ . The annual running time was 8400 hours, and the purification of the desulphurization system using ammonia produced 4100 tons of ammonium sulfate per year, the recovery rate of ammonia was 99.3%.

Accordingly, the installation for carrying out the process discussed above included a catalyst regeneration system used in the catalytic cracking process, a control system and a desulfurization system using ammonia connected in series.

The control system included a cooling device, a dust extraction device, and an impurity extraction device.

The installation includes a system for cleaning the absorbing liquid, which contained an evaporative crystallizer, a device for separating liquid and solid phases, and a device for drying.

The solution purification device is included in the absorbent liquid purification system. Said solution purification device comprised a hydrocarbon recovery device and a suspended solids recovery device, which provided a circulating absorbent liquid with a hydrocarbon content of <80 mg/l and a suspended solids content of <120 mg/l. An air flotation device plus a fine filter was included in the hydrocarbon recovery apparatus, and a filter press such as plate and frame filter press was used as the suspended solids recovery apparatus.

The hydrocarbon recovery device is connected to the combustion system, and the spent hydrocarbons were completely burned in the combustion system into water, carbon dioxide, and sulfur dioxide.

The absorption column had a diameter of 6 m, a height of 32 m, the concentration of sulfur dioxide in the resulting tail gas was 23.3 mg/Nm ³ , the concentration of free ammonia was 0.75 mg/Nm ³ , and the total content of the pulverized fraction was 14.5 mg/Nm ³ .

With regard to the desulfurization plant using ammonia and the methods used in this example, reference may be made to patent documents CN 201710379460.3 and CN 201810057884.2.

Comparative example 1.

Example 1 was repeated, except that the acid tail gas was not controlled by the control system 7 . The sour tail gas from heat recovery was fed directly to the ammonia-based desulfurization system. The parameters of the tail gas entering the desulfurization system using ammonia and the technical results are compared in the table below.

Number Compared parameter Unit Example 1 Comparative Example 1 1 Enthalpy value of residual gas kJ/kg 410-505 910-1000 2 Content of organic substances in tail gas ppt 4.5 37 3 The content of sulfur and sulfide in PPm 3 42 residual gas 4 Absorption temperature °C 50-57 70-85 5 Sulfur dioxide content in final tail gas mg/Nm ³ 32.4 123 6 Content of free ammonia in the final residual gas mg/Nm ³ 1.3 26.8 7 Total dust content in final tail gas mg/Nm ³ 9.5 47.9 The degree of extraction of ammonia in 8 desulfurization system, using ammonia o/ /o 99.1 94.3

It can be seen from the table that the sulfur dioxide concentration, the free ammonia content and the total dust content in Comparative Example 1 were all higher than in Example 1, and the ammonia recovery rate was only 94.3%, i.e. 4.7% lower than in example 1, which indicates a large amount of secondary pollution.

- 16 041439

Comparative example 2.

Example 2 was repeated, except that the acid tail gas was not controlled by the control system 7, but the acid tail gas was fed directly to the desulfurization system using ammonia. The parameters of the tail gas entering the desulfurization system using ammonia and the technical results are compared in the table below.

Number Compared parameter Unit Example 2 Comparative Example 2 1 Enthalpy value of residual gas kJ/kg 320-410 30-52 2 Absorption temperature °C 47-50 30-35 3 Sulfur dioxide content in final tail gas mg/Nm ³ 16.8 37 4 Content of free ammonia in the final residual gas mg/Nm3 0.6 4.8 5 Total dust content in final tail gas mg/Nm ³ 4.5 18.3 6 The degree of ammonia recovery in the desulfurization system, using ammonia % 99.4 97.2

It can be seen from the table that the sulfur dioxide concentration, the free ammonia content and the total particulate content in Comparative Example 2 were all higher than in Example 2, and the ammonia recovery was only 97.2%, i.e. 2.2% lower than in example 2, which indicates a large amount of secondary pollution.

Comparative example 3.

Example 3 was repeated, except that the acid tail gas was not controlled by the control system 7, but the acid tail gas coming from the catalytic cracking catalyst regeneration system and subjected to heat recovery and denitrification was sent directly to desulfurization system using ammonia. The parameters of the tail gas entering the desulfurization system using ammonia and the technical results are compared in the table below._________________________________

Number Compared parameter Unit Example 3 Comparative Example 3 1 Enthalpy value of residual gas kJ/kg 370-408 930-1150 2 Content of organic substances in tail gas ppt <6.2 18.9 3 Total dust content in tail gas mg/Nm ³ 20-30 150-300 4 Absorption temperature °C 47.5- 49.8 80-90 5 Sulfur dioxide content in final tail gas mg/Nm ³ 23.3 169 6 Content of free ammonia in the final residual gas mg/Nm ³ 0.75 33.7 7 Total dust content in final tail gas mg/Nm ³ 14.5 102 8 The degree of ammonia recovery in the desulfurization system, using ammonia % 99.3 91.3

It can be seen from the table that the sulfur dioxide concentration, the free ammonia content and the total particulate content in Comparative Example 3 were all higher than in Example 3, and the ammonia recovery was only 91.3%, i.e. 8% lower than in example 3, which indicates a large amount of secondary pollution.

Some illustrative embodiments are described below:

(A) An acid gas purification method in which an ammonia-based desulfurization process is used to purify an acid tail gas, whereby the result is that the final tail gas satisfies the emission limits after performing multi-stage absorption using a circulating absorption liquid.

(B) The method according to (A), wherein the acid tail gas is a tail gas obtained after purification of the acid gas from the petrochemical, gas chemical, and coal chemical industries by a process such as sulfur recovery plus combustion, sulfuric acid production, and combustion.

(C) The process according to (A), wherein the acid tail gas is an off gas obtained from the regeneration of a catalyst used in a catalytic cracking process.

(D) A process according to any of (B) to (C), wherein the enthalpy value of the acid tail gas is first controlled by a control system, and then the acid tail gas is sent to a subsequent ammonia-based desulfurization process.

- 17 041439 (E) The method according to (A), wherein the multi-stage absorption process with circulation of the absorbing liquid includes a cooling cycle, an absorption cycle, and a water washing cycle.

(F) The method according to (D), wherein the control system comprises a temperature control unit and/or a humidity control unit, or both, a temperature control unit and a humidity control unit.

(G) The method according to (F), wherein the control system further comprises one or more of a temperature control unit, a humidity control unit, and an impurity extraction unit.

(H) The method according to (D), wherein the enthalpy value of the residual gas after regulation is in the range of 60 to 850 kJ/kg dry gas, for example, 80 to 680 kJ/kg dry gas or 100 to 450 kJ/kg dry gas gas.

(I) The method according to (B), wherein the sulfur recovery is carried out in a sulfur recovery process such as 1-3-stage Claus sulfur recovery process, super-Claus sulfur recovery process, Euro-Claus sulfur recovery process , a sulfur recovery process by catalytic liquid phase oxidation or a biological sulfur recovery process; the sulfuric acid production process is carried out by a wet catalysis sulfuric acid production process or a dry catalysis sulfuric acid production process.

(J) The method according to (I), in which the molar ratio of H2S/SO2 in the tail gas after sulfur recovery is controlled at 1.2-3, for example 1.5-2.5.

(K) The method according to (B), wherein in the sulfur recovery plus combustion process and in the combustion process, the combustion temperature is in the range of 600 to 1300°C, for example in the range of 650 to 950°C, the duration of the combustion process is 1- 6 s, for example 1.5-4 s, the oxygen concentration in the acid tail gas is 2-5%, for example 3-4% and the content of sulfur oxide in the acid tail gas is in the range from 2000 to 150000 mg/Nm ³ , for example from 5000 to 55000 mg/Nm ³ .

(L) The method according to (A), in which the circulating absorption liquid of the ammonia-based desulfurization process is subjected to a purification process, as a result of which the content of suspended solids in the circulating absorption liquid is <200 mg/l and/or the hydrocarbon content is <100 mg/ l.

(M) The process according to (G), wherein the content of organic matter in the tail gas after regulation is <30 ppm, such as <10 ppm and/or the content of elemental sulfur and hydrogen sulfide is <30 ppm, such as <10 ppm.

(N) A method according to any of (A)-(M), which includes the following specific process steps:

1) the acid gas is purified by sulfur recovery plus combustion or by sulfuric acid production or by combustion or directly in the catalytic cracking catalyst regeneration process to produce an acid tail gas;

2) acid tail gas is sent to a control system to control the enthalpy value of the tail gas so that this value is in the range from 60 to 850 kJ / kg dry gas, for example from 80 to 680 kJ / kg dry gas or from 100 to 450 kJ / kg of dry gas;

3) acid tail gas, which meets the requirements for the enthalpy value, is sent to the desulfurization process using ammonia, as a result of which, due to multi-stage absorption with circulation of the absorbing liquid, the final tail gas meets the emission standards for harmful substances into the atmosphere.

(O) An acid gas treatment plant that includes an acid gas pre-treatment system and an ammonia-based desulfurization system.

(P) The plant according to (O), wherein the pretreatment system comprises a sulfur recovery system plus a combustion system, a sulfuric acid production system, a combustion system, and a catalytic cracking catalyst regeneration system.

(Q) The plant according to (P), in which the sulfur recovery system includes a Claus sulfur recovery system using 1 to 3 stages of sulfur recovery, a super-Claus sulfur recovery system, a Euro-Claus sulfur recovery system, a sulfur recovery by catalytic liquid phase oxidation and biological sulfur recovery system.

(R) Installation according to (O), which includes a control system containing a temperature control device and/or a humidity control device, or both of these devices, i.e. a temperature control device and a humidity control device.

(S) The plant according to (Q), wherein the control system further comprises one or more of a sulfur recovery device, a dust recovery device, and an impurity recovery device.

(T) The plant according to (S), in which the acid gas pre-treatment system, the control system and the ammonia-based desulfurization system are connected in series, the acid gas pre-treatment system includes a sulfur recovery system plus a combustion system, and the control system includes a temperature control device , a humidity control device and a sulfur recovery device, which are connected in series.

- 18 041439 (U) Installation according to (O), which further includes an absorbent liquid purification system, comprising a concentration device, a device for separating liquid and solid phases, and a device for drying.

(V) The apparatus according to (U), wherein the absorbing liquid purification system further comprises one or more of a solution purification apparatus and an evaporative crystallization apparatus.

(W) The plant according to (V), wherein the solution treatment device may comprise one or more of a hydrocarbon recovery device and a solids recovery device.

(X) Installation according to (W), in which the suspended solids recovery device circulates an absorbent liquid with a suspended solids content of <200 mg/L, such as 20-100 mg/L or 30-50 mg/L.

(Y) A plant according to (W) in which the hydrocarbon recovery device is an air skimmer, an absorber, or a precision filter, or a combination of these devices.

(Z) Installation according to (Y), in which the hydrocarbon recovery device circulates an absorption liquid with a hydrocarbon content of <100 mg/l, such as 10-80 mg/l or 20-30 mg/l.

(AA) An apparatus according to any one of (V) to (Z), wherein the hydrocarbon recovery device is connected to a combustion system.

1. An acid gas treatment plant comprising an acid gas pretreatment system and an ammonia-based desulfurization system in fluid communication with said acid gas pretreatment system.

2. Plant according to embodiment 1, wherein the pretreatment system includes a sulfur recovery system plus a combustion system.

3. Plant according to embodiment 1, in which the system for the production of sulfuric acid is included in the pre-treatment system.

4. The plant according to embodiment 1, wherein the pretreatment system includes a catalyst regeneration system used in the catalytic cracking process.

5. A plant according to embodiment 2 wherein the sulfur recovery system includes a Claus sulfur recovery system comprising one sulfur recovery stage.

6. A plant according to embodiment 2 wherein the sulfur recovery system includes a Claus sulfur recovery system comprising two recovery stages.

7. A plant according to embodiment 2 wherein the sulfur recovery system includes a Claus sulfur recovery system comprising three recovery stages.

8. A plant according to embodiment 2 wherein the sulfur recovery system includes a liquid phase catalytic oxidation sulfur recovery system.

9. A plant according to embodiment 2 wherein the sulfur recovery system includes a biological sulfur recovery system.

10. The plant according to any one of embodiments 5-7, wherein the sulfur recovery system further comprises a super-Claus sulfur recovery system that is in fluid communication with the Claus sulfur recovery system.

11. A plant according to any one of embodiments 5-7, wherein the sulfur recovery system further comprises a Euro-Claus sulfur recovery system that is in fluid communication with the Claus sulfur recovery system.

12. A plant according to any one of embodiments 5-7, wherein the sulfur recovery system further comprises a biological sulfur recovery system that is in fluid communication with the Claus sulfur recovery system.

13. The plant according to any one of embodiments 5-7, wherein the sulfur recovery system further comprises a catalytic liquid phase sulfur recovery system that is in fluid communication with the Claus sulfur recovery system.

14. A plant according to embodiment 1, further comprising a control system that is in fluid communication with an ammonia-using desulfurization system and is located upstream of the desulfurization system.

15. An apparatus according to embodiment 14 wherein the control system comprises a temperature controller for controlling the gas temperature control system.

16. An apparatus according to embodiment 15, wherein the control system comprises a humidity controller for controlling the gas humidity control system.

17. An apparatus according to embodiment 14 wherein the control system comprises a humidity controller for controlling the gas humidity control system.

18. A plant as in any one of embodiments 14-17, further comprising a sulfur recovery device that is in fluid communication with an ammonia desulfurization system.

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19. The apparatus of any one of embodiments 14-17, further comprising a pulverized fraction recovery device that is in fluid communication with an ammonia desulfurization system.

20. The apparatus of any one of embodiments 14-17, further comprising an impurity recovery device that is in fluid communication with an ammonia desulfurization system.

21. The plant of any one of embodiments 14-17, further comprising a sulfur recovery device that is in fluid communication with the ammonia-using desulfurization system and a particulate fraction recovery device that is in fluid communication with the ammonia-using desulfurization system.

22. The plant of any one of embodiments 14-17, further comprising a sulfur recovery device that is in fluid communication with the ammonia-using desulfurization system and an impurity recovery device that is in fluid communication with the ammonia-using desulfurization system.

23. The apparatus of any one of embodiments 14-17, further comprising a pulverized fraction recovery device that is in fluid communication with the desulfurization system using ammonia, and an impurity recovery device that is in fluid communication with the desulfurization system using ammonia.

24. A plant according to any one of embodiments 18-23, wherein the acid gas pre-treatment system, the control system, and the ammonia-based desulfurization system are connected in series in the downstream direction of the gas flow.

25. The plant of embodiment 24 wherein the acid gas pretreatment system includes a sulfur recovery system plus a combustion system.

26. The apparatus of embodiment 1, further comprising a control system that is in fluid communication with an ammonia desulphurization system and located upstream.

27. An apparatus according to embodiment 26, wherein the control system comprises a temperature controller for controlling the gas temperature in the control system.

28. An apparatus according to embodiment 27, in which the control system comprises a humidity controller for controlling gas humidity in the control system.

29. The plant of embodiment 28, further comprising a sulfur recovery device that is in fluid communication with an ammonia desulfurization system.

30. The plant according to embodiment 29, wherein the acid gas pre-treatment system, the control system, and the ammonia-using desulfurization system are connected in series in a downstream direction.

31. The plant of embodiment 30 wherein the acid gas pre-treatment system includes a sulfur recovery system plus a combustion system.

32. The plant according to embodiment 31, wherein in the control system, a temperature controller, a humidity controller, and a sulfur recovery device are connected in series in a downstream direction.

33. The plant according to embodiment 30, wherein in the control system, a temperature controller, a humidity controller, and a sulfur recovery device are connected in series in a downstream direction.

34. The plant according to embodiment 1, wherein the desulfurization system using ammonia circulates an absorbent liquid containing ammonia, and includes an absorbent liquid purification system, which includes a concentration device for receiving the absorbent liquid, a device for separating liquid and solid phase , capable of trapping solids suspended in the liquid, and a drying device that allows the separated solids to be dried.

35. The apparatus of embodiment 34, wherein the absorbent liquid purification system further comprises a solution purification device that is in fluid communication with said liquid-solid separation device and is in operation located downstream of the liquid-solid separation device. phases.

36. The plant according to embodiment 35, wherein the absorbent liquid purification system further comprises an evaporative crystallization device that is in fluid communication with said concentration device and the liquid-solid separation device and is located downstream of the device during operation. concentration and upstream relative to the device for separating liquid and solid phase.

37. The apparatus of embodiment 34, wherein the absorbent liquid purification system further comprises an evaporative crystallization device that is in fluid communication with said concentration device and the liquid-solid separation device and is located downstream of the device during operation. for con-

- 20 041439 and upstream of the device for separating liquid and solid phase.

38. An apparatus according to any of embodiments 35 and 36 wherein the solution scrubber comprises a hydrocarbon recovery apparatus in fluid communication with the liquid/solid separation apparatus.

39. An apparatus according to embodiment 38, wherein the solution purification device comprises a suspended matter recovery device that is in fluid communication with the liquid/solid separation device.

40. An apparatus according to any one of embodiments 35 and 36, wherein the solution purification device comprises a suspended matter recovery device that is in fluid communication with the liquid/solid separation device.

41. An apparatus according to any one of embodiments 39 and 40, wherein the suspended matter recovery device circulates an absorbent liquid having a suspended matter content of not more than 200 mg/L.

42. Installation according to embodiment 41, in which the content of suspended matter is in the range from 20 to 100 mg/l.

43. Installation according to embodiment 42, in which the content of suspended matter is in the range from 30 to 50 mg/l.

44. The apparatus of embodiment 38 wherein the hydrocarbon recovery apparatus includes an air flotation apparatus in fluid communication with the liquid/solid separation apparatus.

45. The apparatus of embodiment 44 wherein the hydrocarbon recovery device further comprises an absorption device that is in fluid communication with the liquid/solid separation device.

46. The apparatus of embodiment 45 wherein the hydrocarbon recovery device further comprises a precision filter that is in fluid communication with the liquid/solid separation device.

47. The apparatus of embodiment 38 wherein the hydrocarbon recovery device further comprises an absorption device that is in fluid communication with the liquid/solid separation device.

48. The apparatus of embodiment 38 wherein the hydrocarbon recovery device further comprises a precision filter that is in fluid communication with the liquid/solid separation device.

49. The apparatus of embodiment 47, wherein the hydrocarbon recovery device further comprises a precision filter that is in fluid communication with the liquid/solid separation device.

50. The apparatus of embodiment 44 wherein the hydrocarbon recovery device further comprises a precision filter that is in fluid communication with the liquid/solid separation device.

51. An apparatus according to any one of embodiments 44-50, wherein the hydrocarbon recovery device circulates an absorption liquid having a hydrocarbon content of not more than 100 mg/L.

52. The installation according to embodiment 51, in which the hydrocarbon content is in the range from 10 to 80 mg/l.

53. The installation according to embodiment 52, in which the hydrocarbon content is in the range from 20 to 30 mg/l.

54. An apparatus according to any one of embodiments 44-53, wherein the hydrocarbon recovery apparatus is in fluid communication with the combustion system and is located upstream of the combustion system during operation.

55. A process for treating acid gas, which includes receiving acid gas, recovering ammonium sulfate from acid gas and the final residual gas that meets the standards for pollutant emissions into the atmosphere.

56. The method according to embodiment 55, wherein said emission standards for atmospheric pollutants are defined in a document entitled Emission Standard of Pollutants for Petroleum Refining Industry published in China, GB 31570-2015.

57. The method according to embodiment 55, wherein said emission standards for air pollutants are defined in a document entitled Emission Standard of Pollutants for Petroleum Chemistry Industry published in China, GB 31571-2015.

58. The method of embodiment 55, wherein the recovery process comprises recovering sulfur from acid gas to produce a tail gas with recovered sulfur, and thereafter combusting said gas with recovered sulfur.

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59. The method of embodiment 55, wherein the recovery process includes the production of sulfuric acid from acid gas.

60. The method of embodiment 55 wherein the recovery process includes incineration.

61. The method of any one of embodiments 55-60, further comprising transporting the acid gas through a pipeline after the chemical reaction is carried out in the petrochemical plant.

62. The method of any one of embodiments 55-60, further comprising transporting the acid gas through a pipeline after the chemical reaction is carried out in a gas chemical plant.

63. The method of any one of embodiments 55-60, further comprising transporting the acid gas through a pipeline after the chemical reaction is carried out in a coal chemical plant.

64. The method according to embodiment 55, in which the recovery process includes the formation of off-gas of the process of regeneration of the catalyst used in carrying out catalytic cracking; wherein the acid gas includes off-gas from the regeneration process.

65. The method of any one of embodiments 55-64, wherein the recovery process comprises adjusting the enthalpy value of the acid tail gas.

66. The method according to embodiment 55, wherein the recovery process includes passing the adjusted tail gas through: a cooling stage, an absorption stage and a water washing stage, all stages being in a desulfurization reactor using circulating ammonia.

67. The method of embodiment 65 wherein the control process includes changing the temperature of the acid tail gas.

68. The method of embodiment 65 wherein the control process includes changing the moisture content of the acid tail gas.

69. The method of embodiment 68, wherein the control process further comprises changing the temperature of the acid tail gas.

70. The method according to any one of embodiments 67-69, wherein the control process further comprises recovering sulfur from the acid tail gas.

71. The method according to any one of embodiments 67-69, wherein the control process further comprises recovering the pulverized fraction from the acid tail gas.

72. The method according to any one of embodiments 67-69, wherein the control process further comprises removing impurities from the acid tail gas.

73. The method of embodiment 70 wherein the control process further comprises removing impurities from the acid tail gas.

74. The method of embodiment 71 wherein the control process further comprises removing impurities from the acid tail gas.

75. The method of embodiment 65, wherein the control process adjusts the residual gas enthalpy to 60-850 kJ/kg dry gas.

76. The method of embodiment 65, wherein the control process adjusts said value to 80-680 kJ/kg dry gas.

77. The method of embodiment 65, wherein the control process adjusts said value to 100-450 kJ/kg dry gas.

78. The method of embodiment 55, wherein the recovery process includes passing acid gas through a single stage Claus sulfur recovery system.

79. The method of embodiment 55, wherein the recovery process includes passing acid gas through a two-stage Claus sulfur recovery system.

80. The method of embodiment 55 wherein the recovery process comprises passing acid gas through a Claus sulfur recovery system comprising three stages.

81. The method of embodiment 55 wherein the recovery process comprises passing acid gas through a sulfur recovery system by liquid phase catalytic oxidation.

82. The method of embodiment 55 wherein the recovery process includes passing acid gas through a biological sulfur recovery system.

83. The method of any one of embodiments 78-80, wherein the recovery process further comprises passing acid gas through a super-Claus sulfur recovery system.

84. The method of any one of embodiments 78-80, wherein the recovery process further comprises passing acid gas through a Euro-Claus sulfur recovery system.

85. The method of any one of embodiments 78-80, wherein the recovery process further comprises passing acid gas through a biological sulfur recovery system.

86. The method of any of embodiments 78-80, wherein the recovery process further comprises passing acid gas through a liquid phase catalytic oxidation sulfur recovery system.

87. The method according to embodiment 59, wherein the production of sulfuric acid comprises the production of sulfuric acid by wet catalysis.

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88. The method according to embodiment 59, wherein the production of sulfuric acid comprises the production of sulfuric acid by dry catalysis.

89. The method of any one of embodiments 78-88, wherein the recovery process includes producing a gas with recovered sulfur and an H2S/SO2 molar ratio in the range of 1.2 to 3.

90. The method according to embodiment 89 wherein said molar ratio is in the range of 1.5 to 2.5.

91. The method according to embodiment 56, wherein the combustion is carried out at a temperature in the range from 600 to 1300° C. and an acid tail gas is obtained.

92. The method according to embodiment 91, in which the process of burning the tail gas with the recovered sulfur is continued for 1 to 6 seconds.

93. The method of any one of embodiments 91-92, wherein the oxygen content of the acid tail gas is in the range of 2 to 5%.

94. The method of any one of embodiments 91-93, wherein the content of sulfur oxide in the acid tail gas is in the range of 2,000 to 150,000 mg/Nm ³ .

95. The method of any one of embodiments 91-94 wherein the combustion process is carried out at a temperature in the range of 650°C to 950°C.

96. The method according to any one of embodiments 91-95, wherein the process of burning the residual gas with recovered sulfur is continued for 1.5 to 4 seconds.

97. The method of any one of embodiments 91-96, wherein the oxygen content of the acid tail gas is in the range of 3 to 4%.

98. The method according to any one of embodiments 91-97, wherein the content of sulfur oxide in the acid tail gas is in the range of 5000 to 55000 mg/Nm ³ .

99. The method according to any one of embodiments 91-97, wherein the content of sulfur oxide in the acid tail gas is in the range of 2,000 to 150,000 mg/Nm ³ .

100. The method according to embodiment 99, in which combustion is carried out at a temperature in the range from 600 to 1300°C and an acid tail gas is obtained.

101. The method according to any one of embodiments 99-100, further comprising a process of burning the residual gas with recovered sulfur, wherein the duration of the combustion process is from 1 to 6 seconds.

102. The process of any one of embodiments 99-101, wherein the oxygen content of the acid tail gas is in the range of 2 to 5%.

103. The method of any one of embodiments 99-102, wherein the combustion process is carried out at a temperature in the range of 650 to 950°C.

104. The method according to any one of embodiments 99-103, wherein the process time for burning the residual gas with recovered sulfur is 1.5 to 4 seconds.

105. The process of any one of embodiments 99-104, wherein the oxygen content of the acid tail gas is in the range of 3 to 4%.

106. The process of any one of embodiments 99-105, wherein the content of sulfur oxide in the acid tail gas is in the range of 5,000 to 55,000 mg/Nm ³ .

107. The method of embodiment 56, further comprising producing an acid tail gas with an oxygen content in the range of 2 to 5%.

108. The method according to embodiment 107, wherein the content of sulfur oxide in the acid tail gas is in the range from 2000 to 150000 mg/Nm ³ .

109. The method according to any one of embodiments 107-108, wherein combustion is carried out at a temperature in the range of 600 to 1300° C. and an acid tail gas is obtained.

110. The method according to any one of embodiments 107-109, wherein the process of burning the tail gas with recovered sulfur is from 1 to 6 seconds.

111. The method of any one of embodiments 107-110, wherein the combustion process is carried out at a temperature in the range of 650 to 950°C.

112. The method according to any one of embodiments 107-111, wherein the process time for burning the residual gas with recovered sulfur is from 1.5 to 4 seconds.

113. The method of any one of embodiments 107-112, wherein the oxygen content of the acid tail gas is in the range of 3 to 4%.

114. The method of any one of embodiments 107-113, wherein the content of sulfur oxide in the acid tail gas is in the range of 5000 to 55000 mg/Nm ³ .

115. The method according to embodiment 56, in which the duration of the process of burning the residual gas with recovered sulfur is from 1 to 6 seconds.

116. The method of embodiment 115, further comprising producing an acid tail gas with an oxygen content in the range of 2 to 5%.

117. The method of any one of embodiments 115-116, further comprising producing an acid tail gas with a sulfur oxide content in the range of 2,000 to 150,000 mg/Nm ³ .

118. The method according to any of embodiments 115-117, in which combustion is carried out at a dark

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Claims (35)

temperature in the range from 600 to 1300°C and get an acid tail gas. 119. The method according to any one of embodiments 115-118, wherein the combustion is carried out at a temperature in the range from 650 to 950°C. 120. The method according to any one of embodiments 115-119, wherein the process time for burning the residual gas with recovered sulfur is in the range of 1.5 to 4 seconds. 121. The method of any one of embodiments 115-120, wherein the oxygen content of the acid tail gas is in the range of 3 to 4%. 122. The method of any one of embodiments 115-121, wherein the content of sulfur oxide in the acid tail gas is in the range of 5,000 to 55,000 mg/Nm ³ . 123. The method according to embodiment 55, wherein the recovery process comprises reducing the suspended matter content to a value of not more than 200 mg/l as a result of desulfurization based on ammonia using a circulating absorbent liquid. 124. The method of embodiment 123, wherein the recovery process further comprises reducing the hydrocarbon content to a value of not more than 100 mg/L by ammonia-based desulfurization using a circulating absorption liquid. 125. The method according to embodiment 55, wherein the recovery process includes reducing hydrocarbon content to a value of not more than 100 mg/l as a result of ammonia-based desulfurization using a circulating absorption liquid. 126. The method according to embodiment 67, in which the regulated tail gas with an organic matter concentration of not more than 30 ppm is obtained in the control process. 127. The method according to embodiment 67, in which the regulated tail gas containing elemental sulfur and hydrogen sulfide with a concentration of not more than 30 ppm is obtained during the regulation. 128. The method according to any one of embodiments 126-127, wherein the adjustment process produces a regulated tail gas with an organic matter concentration of not more than 10 ppm. 129. The method according to any of embodiments 126-128, wherein the control process produces a regulated tail gas containing elemental sulfur and hydrogen sulfide at a concentration of not more than 10 ppm. 130. The method according to embodiment 68, in which the regulation process produces a regulated tail gas containing elemental sulfur and hydrogen sulfide with a concentration of not more than 30 ppm. 131. The method according to embodiment 68, wherein the adjustment process produces a regulated tail gas in which the concentration of organic matter is not more than 30 ppm. 132. The method according to any of embodiments 130 and 131, wherein the adjustment process produces a regulated tail gas in which the concentration of organic matter is not more than 10 ppm. 133. The method according to any of embodiments 130-132, wherein the control process produces a regulated tail gas containing elemental sulfur and hydrogen sulfide at a concentration of not more than 10 ppm. 134. The method of any of embodiments 55-133, wherein the specific steps of the method include the following: a) the acid gas is treated by sulfur recovery plus combustion or sulfuric acid production or combustion, or directly by a catalytic cracking catalyst regeneration process to produce an acid tail gas; b) acid tail gas is sent to a control system to control the enthalpy value of the tail gas so that it is in the range from 60 to 850 kJ/kg dry gas, for example from 80 to 680 kJ/kg dry gas or from 100 to 450 kJ/kg dry gas; c) Sour tail gas, whose enthalpy value meets the specified requirements, is sent to ammonia-based desulfurization for purification, so that the final tail gas from the multi-stage absorption using circulating absorption liquid meets the emission standards. Thus, a facility and methods for purifying acid gas are provided. Those skilled in the art will appreciate that the present invention may be practiced with examples other than those described above, provided for purposes of illustration and not limitation of the invention. The present invention is limited only by the following claims. CLAIM 1. An acid gas treatment plant comprising an acid gas pre-treatment system, a control system, and an ammonia-using desulfurization system, wherein the acid gas pre-treatment system, the control system, and the ammonia-using desulfurization system are connected in series in a downward direction. in the direction of the flow; wherein the pretreatment system includes a sulfur recovery system and a combustion system, a sulfuric acid production system and/or a catalyst regeneration system used in the catalytic cracking process; said desulfurization system using ammonia is configured to circulate an absorbing liquid containing ammonia and obtain a final tail gas; Said control system comprises a temperature controller configured to control the temperature of the acid tail gas discharged from the pretreatment system in the control system and/or a humidity controller configured to control the gas humidity in the control system, and said control system is configured to control the enthalpy value of the acid tail gas, so that the enthalpy value is maintained in the range from 60 to 850 kJ/kg dry gas, while the enthalpy H value is calculated by the formula H \u003d (1.01 + 1.88b) x1 + 2490b, where t is the temperature in ° C, b is the concentration of water vapor in dry gas, measured in kg / kg of dry gas. 2. The plant of claim 1, wherein the sulfur recovery system includes a Claus sulfur recovery system comprising one stage, two stages, or three stages, a liquid phase catalytic oxidation sulfur recovery system, or a biological sulfur recovery system. 3. The plant according to claim 1 or 2, wherein the sulfur recovery system further comprises a super-Claus sulfur recovery system, a Euro-Claus sulfur recovery system, a biological sulfur recovery system, or a liquid phase catalytic sulfur recovery system, which are in flow communication with the Claus sulfur recovery system. 4. Plant according to any one of claims 1 to 3, wherein the control system is in flow communication with the desulfurization system using ammonia and is located upstream of the desulfurization system. 5. Plant according to any one of claims 1 to 4, further comprising a sulfur recovery device, a dust recovery device and/or an impurity recovery device that are in fluid communication with the desulfurization system using ammonia. 6. Plant according to any one of claims 4, 5, wherein the control system, temperature controller, humidity controller and desulphurizer are connected in series in a downstream direction. 7. The plant according to any one of claims 1 to 6, wherein the desulfurization system using ammonia comprises an absorbent liquid purification system, which includes a concentration device to receive the absorbent liquid, a device for separating liquid and solid phase, configured to capture solids suspended in the liquid; and a drying device for drying the trapped and separated solids. 8. The plant according to claim 7, wherein the absorbent liquid purification system further comprises a solution purification device that is in fluid communication with the liquid-solid separator and is located downstream of the liquid-solid separator during operation of the apparatus. phases. 9. The plant according to claim 7 or 8, wherein the absorbent liquid purification system further comprises an evaporative crystallization device that is in fluid communication with the concentration device and the liquid-solid separation device and is located downstream of the device during operation. for concentration and upstream of the liquid/solid separator. 10. A plant according to claim 8 or 9, wherein the solution purification device comprises a liquid/solid separation device, a hydrocarbon recovery device and/or a solids recovery device in flow communication. 11. The installation according to claim 10, wherein the suspended solids recovery device circulates an absorbent liquid containing suspended solids whose concentration does not exceed 200 mg/l, preferably in the range of 20 to 100 mg/l, and more preferably in the range of 30 to 50 mg/l. 12. A plant according to claim 10 or 11, wherein the hydrocarbon recovery device comprises a liquid/solid separation device, an air flotation device, an absorption device and/or a fine filter in flow communication. 13. Plant according to any one of claims 10 to 12, wherein the hydrocarbon recovery device provides a circulating absorption liquid in which the hydrocarbon content is not more than 100 mg/l, preferably in the range of 10 to 80 mg/l, and more preferably in the range from 20 to 30 mg/l. - 25 041439 14. Plant according to any one of claims 10 to 13, wherein the hydrocarbon recovery device is connected to a combustion system. 15. An apparatus as claimed in claim 14, wherein the hydrocarbon recovery apparatus is in fluid communication with the combustion system and, under operating conditions, is located upstream of the combustion system. 16. A method for purifying acid gas using the plant according to claim 1, including supplying acid gas, extracting ammonium sulfate from acid gas and obtaining a final residual gas that meets the emission standards for harmful substances that are established by the Emission Standard of Pollutants for Petroleum Refining Industry document, published in China, GB 31570-2015. 17. The method of claim 16, wherein the step of recovering comprises recovering sulfur from the acid gas to produce a tail gas with recovered sulfur, and then flaring the gas from which the sulfur has been recovered. 18. The method according to claim 16 or 17, wherein the step of recovery comprises the production of sulfuric acid from the acid gas and/or combustion. 19. The method according to any one of claims 16 to 18, further comprising transporting acid gas through a pipeline after a chemical reaction in a petrochemical plant, a chemical reaction in a gas processing plant, and/or a chemical reaction in a coal industry. 20. A process according to any one of claims 16 to 19, wherein the recovery step comprises generating a regeneration off gas of a catalyst used in a catalytic cracking process and the acid tail gas is an off gas of a catalyst regeneration process. 21. The method according to any one of claims 16 to 20, wherein the recovery step comprises adjusting the enthalpy value of the acid tail gas. 22. The method according to any one of claims 16-21, wherein the recovery step comprises passing the adjusted tail gas through a cooling stage, an absorption stage and a water washing stage, all stages being placed in a desulfurization reactor using circulating ammonia. 23. The method according to claim 21 or 22, wherein the control step comprises changing the temperature of the acid tail gas and/or the humidity of the acid tail gas and/or further comprising removing sulfur, dust and/or impurities from the acid tail gas. 24. The method according to any one of claims 21 to 23, wherein the step of adjusting comprises adjusting the enthalpy value of the tail gas to a value in the range of 80 to 680 kJ/kg dry gas and preferably 100 to 450 kJ/kg dry gas. 25. A process according to any one of claims 21 to 24, wherein the control step produces a controlled tail gas with an organic matter content of at most 30 ppm, preferably at most 10 ppm. 26. The method according to any one of claims 21 to 25, wherein the control step produces a regulated tail gas containing elemental sulfur and hydrogen sulfide with a content of not more than 30 ppm, preferably not more than 10 ppm. 27. The process according to any one of claims 21 to 26, wherein the recovery step comprises passing the acid gas through a Claus sulfur recovery system comprising one stage, two stages, or three stages, through a catalytic liquid phase sulfur recovery system, through a biological sulfur recovery system, via a Super Claus sulfur recovery system, and/or via a Euro Claus sulfur recovery system. 28. A process according to any one of claims 16 to 27, wherein the production of sulfuric acid comprises the production of sulfuric acid by wet catalysis and/or the production of sulfuric acid by dry catalysis. 29. The method according to any one of claims 17 to 28, wherein the recovery step comprises producing a sulfur-recovered gas in which the H2S/SO2 molar ratio is in the range of 1.2 to 3, preferably in the range of 1.5 to 2, 5. 30. The method according to any one of claims 17 to 29, wherein the combustion step is carried out at a temperature in the range from 600 to 1300°C, preferably in the range from 650 to 950°C, and an acid tail gas is obtained. 31. The method according to any one of claims 17 to 30, wherein in the stage of combustion of the tail gas with recovered sulfur, the combustion time is in the range of 1 to 6 seconds, preferably 1.5 to 4 seconds. 32. The method according to any one of claims 20 to 31, wherein the oxygen concentration in the acid tail gas is in the range of 2 to 5%, preferably in the range of 3 to 4%. 33. Process according to any one of claims 20 to 32, wherein the content of sulfur oxide in the acid tail gas is in the range from 2000 to 150000 mg/Nm ³ , preferably in the range from 5000 to 55000 mg/Nm ³ . 34. The method according to any one of claims 16 to 33, wherein the step of recovering comprises reducing the suspended matter content in the circulating absorption liquid of the ammonia-based desulfurization process, preferably to a value of not more than 200 mg/L. 35. The method according to any one of claims 16 to 34, wherein the step of recovering further comprises reducing the hydrocarbon content of the circulating absorbent liquid of the desulfurization process by -