Device and process for preparing sulfuric acid from wet-process acid gas

Abstract

The invention provides a device and a process for preparing sulfuric acid from wet-process acid gas, the device comprises an incinerator, a first waste heat boiler, a sulfur dioxide converter, a second waste heat boiler, a condenser and an activated carbon reactor which are sequentially connected through a pipeline, and the sulfur dioxide converter comprises four catalyst bed layers which are sequentially arranged from top to bottom; two air supplement valves and two interlayer heat exchangers are arranged on the sulfur dioxide converter; and a return pipe is communicated between the activated carbon reactor and the condenser. The process provided by the invention can treat various working conditions of feed gases with different concentrations, can adjust the oxygen concentration in the catalyst bed layer according to the change of the feed gas concentration, performs emergency cooling on the catalyst bed layer when an overtemperature phenomenon occurs in the catalyst bed layer, and adopts an activated carbon reactor at the tail end to adsorb and convert sulfur dioxide to obtain dilute sulfuric acid. Dilute sulfuric acid flows back to the condenser to spray sulfur trioxide, sulfuric acid with high concentration is obtained, no waste water is generated in the whole process, and tail gas is discharged after reaching the standard.

Description

Technical Field

[0001] The invention relates to the technical field of sulfuric acid preparation technology, and in particular to a device and process for preparing sulfuric acid by wet acid gas. Background Art

[0002] Since the beginning of the 21st century, my country has built dozens of WSA sulfuric acid production units based on the WSA patented technology of Denmark's Topsoe Company, which has enabled the wet process for preparing sulfuric acid to develop rapidly in my country. These WSA sulfuric acid production units are mainly used as environmental protection devices for treating acid gas from desulfurization units. Generally, the units are small in scale and are used to directly convert sulfuric acid-containing gas in production into acid liquid. They are mostly distributed in industries such as oil refining, non-ferrous metal smelting, fertilizers, viscose fibers, coal coking, and coal chemical industry. They are used to treat low-sulfur gas to obtain commercial-grade concentrated sulfuric acid, and the tail gas meets the emission standards. This process catalytically converts sulfur dioxide into sulfur trioxide in the presence of water vapor, and directly condenses it into sulfuric acid without washing or drying. It has the advantages of simple process, high sulfur recovery rate, high energy efficiency, no wastewater generation, high operational flexibility, low operating cost, and no pollution to the environment.

[0003] In the existing traditional wet process acid gas acid-making device, the one-conversion-one-cooling process takes into account the problem of bed pressure drop. The number of catalyst beds in the SO2 converter is at most three. If you want to improve the total SO2 conversion rate, you can use a two-conversion-two-cooling process, but this will increase the equipment cost. In addition, whether it is a one-conversion-one-cooling mode or a two-conversion-two-cooling mode, at the beginning of the design, it can only adapt to one raw gas component condition, or the raw gas component can only have a slight change, so if there is a large change in the upstream condition, for example, after the upstream coal changes from low-sulfur coal to high-sulfur coal, the concentration of the SO2 converter inlet increases greatly, which will cause the total SO2 conversion rate to fluctuate greatly. Summary of the invention

[0004] The object of the present invention is to provide a device and process for preparing sulfuric acid from wet acidic gas.

[0005] To achieve the above object, the present invention proposes the following technical solutions:

[0006] A device for preparing sulfuric acid from wet acidic gas, comprising an incinerator, a first waste heat boiler, a sulfur dioxide converter, a second waste heat boiler, a condenser and an activated carbon reactor connected in sequence through pipelines;

[0007] The sulfur dioxide converter comprises a first catalyst bed, a second catalyst bed, a third catalyst bed and a fourth catalyst bed arranged in sequence from top to bottom, the inlet and outlet of the second catalyst bed are respectively provided with a first air supply valve and a second air supply valve for supplementing oxygen and emergency cooling, and an interlayer heat exchanger is provided between the second catalyst bed and the third catalyst bed, and between the third catalyst bed and the fourth catalyst bed;

[0008] The condenser is connected to the first air supply valve via a first branch pipe;

[0009] An activated carbon catalytic bed and a first spraying device are provided inside the activated carbon reactor. The first spraying device is used to spray desalted water. A reflux pipe is connected between the activated carbon reactor and the condenser. The reflux pipe is used to reflux the dilute sulfuric acid in the activated carbon reactor to the condenser to spray the sulfur trioxide inside it.

[0010] As a preferred technical solution of the present invention, the condenser includes a third shell, a third heat exchange tube and a second spray device;

[0011] The inner cavity of the third shell is connected to the second waste heat boiler and the activated carbon reactor through pipelines respectively;

[0012] The third heat exchange tube is disposed in the inner cavity of the third shell, and the outlet of the third heat exchange tube is connected to the first air supply valve through the first branch pipe;

[0013] The second spray device is arranged at the top end of the inner cavity of the third shell, and the inlet of the second spray device is connected to the outlet of the reflux pipe.

[0014] As a preferred technical solution of the present invention, the incinerator is provided with an air intake pipe and a fuel replenishing pipe, and a second branch pipe is provided between the air intake pipe and the outlet of the third heat exchange pipe;

[0015] The inlet and outlet of the second catalyst bed are respectively provided with a first transverse porous air tube array and a second transverse porous air tube array;

[0016] The first air supply valve passes the hot air from the third heat exchange tube into the first transverse porous air tube array, and the hot air is mixed with the process gas from the first catalyst bed and then enters the second catalyst bed to supplement oxygen and emergency cooling for the second catalyst bed;

[0017] The second air supply valve passes cold air into the second transverse porous air tube array, and the cold air is mixed with the process gas from the second catalyst bed and then enters the third catalyst bed to supplement oxygen and emergency cooling for the third catalyst bed;

[0018] Air filters are provided at the air inlets of the first air supply valve and the second air supply valve.

[0019] As a preferred technical solution of the present invention, the first waste heat boiler comprises a first shell, a first heat exchange tube and a first steam drum, the first heat exchange tube is arranged in the inner cavity of the first shell, the inlet and outlet of the first heat exchange tube are respectively connected to the incinerator and the sulfur dioxide converter, and the first steam drum is connected to the inner cavity of the first shell;

[0020] The second waste heat boiler comprises a second shell, a second heat exchange tube and a second steam drum, the second heat exchange tube is arranged in the inner cavity of the second shell, the inlet and outlet of the second heat exchange tube are respectively connected to the sulfur dioxide converter and the condenser, and the second steam drum is in communication with the inner cavity of the second shell;

[0021] The inlet of the interlayer heat exchanger is connected to the outlet of the first steam drum and / or the second steam drum, so that the water vapor generated by the first steam drum and / or the second steam drum enters the interlayer heat exchanger to exchange heat with the first process gas and the second process gas.

[0022] As a preferred technical solution of the present invention, the first catalyst bed is loaded with a platinum-based catalyst, and the height of the first catalyst bed is 500 to 1000 mm;

[0023] The platinum-based catalyst has an outer dimension of 150*150*600mm or 150*150*300mm and a 60-hole honeycomb catalyst, and the carrier used by the platinum-based catalyst is titanium dioxide;

[0024] The second catalyst bed layer, the third catalyst bed layer and the fourth catalyst bed layer are all loaded with vanadium-based catalysts, and the heights of the second catalyst bed layer, the third catalyst bed layer and the fourth catalyst bed layer are 500-600 mm.

[0025] As a preferred technical solution of the present invention, the activated carbon loading amount of the activated carbon catalytic bed is 80 to 100 m 3 .

[0026] As a preferred technical solution of the present invention, an electrostatic demister is provided at the top of the condenser, and the electrostatic demister is used to remove acid mist.

[0027] The present invention provides a process for preparing sulfuric acid by wet process acidic gas, wherein sulfuric acid is prepared by using the device for preparing sulfuric acid by wet process acidic gas as described above, and the process comprises the following steps:

[0028] (1) Acidic gas containing hydrogen sulfide and air enter the incinerator and burn to generate a first process gas rich in sulfur dioxide;

[0029] (2) the first process gas enters the first waste heat boiler for heat exchange and cooling, and then enters the sulfur dioxide converter;

[0030] (3) The sulfur dioxide in the first process gas is converted into sulfur trioxide in the sulfur dioxide converter to obtain a second process gas rich in sulfur trioxide; the flow rate of hot air entering the second catalyst bed is adjusted through the first air supply valve according to the concentration of sulfur dioxide in the first process gas, and oxygen is supplemented and heat is removed by the hot air. When the third catalyst bed is overheated, cold air is introduced into the third catalyst bed through the second air supply valve to perform emergency cooling;

[0031] (4) After the second process gas enters the second waste heat boiler for heat exchange and cooling, it then enters the condenser for heat exchange with air for condensation, so that sulfur trioxide in the second process gas is condensed and forms sulfuric acid under the spray of dilute sulfuric acid. At the same time, the obtained third process gas enters the activated carbon reactor, and the hot air heated by the condenser enters the second catalyst bed through the first branch pipe and the first air supply valve;

[0032] (5) The sulfur dioxide in the third process gas is converted into sulfur trioxide under catalytic oxidation by the activated carbon catalyst bed, and the generated sulfur trioxide is contacted with desalted water to obtain dilute sulfuric acid, and the sulfur dioxide in the remaining tail gas meets the emission standards;

[0033] (6) The dilute sulfuric acid generated in the activated carbon reactor enters the condenser through a reflux pipe to spray the sulfur trioxide inside the condenser, thereby converting the sulfur trioxide into sulfuric acid without generating wastewater.

[0034] As a preferred technical solution of the present invention, a part of the hot air heated by the condenser is mixed with the acidic gas containing hydrogen sulfide through the second branch pipe and then enters the incinerator;

[0035] The water vapor generated by the first waste heat boiler and / or the second waste heat boiler enters the interlayer heat exchanger.

[0036] As a preferred technical solution of the present invention, when the acid gas containing hydrogen sulfide is burned in the incinerator, fuel is added to the incinerator through a fuel adding pipe, and the fuel is any one or more of natural gas and hydrocarbon compounds.

[0037] The technical solution of the present invention provides a device and process for preparing sulfuric acid from wet acid gas, which has the following beneficial effects compared with the prior art:

[0038] (1) By arranging four catalyst beds and two interlayer heat exchangers between two adjacent catalyst beds in the sulfur dioxide converter, and arranging an air supply valve between two adjacent catalyst beds without an interlayer heat exchanger, and replacing the interlayer heat exchanger with the air supply valve, the effect of one-stage conversion and one-stage condensation of the sulfur dioxide converter can be achieved while saving one interlayer heat exchanger, thereby saving equipment costs;

[0039] (2) The sulfuric acid preparation device and process can handle various working conditions of raw gas with different concentrations. The hot air flow rate introduced by the first air supply valve can be adjusted according to the change of the raw gas concentration, thereby dynamically adjusting the oxygen concentration entering the second catalyst bed layer, so that the oxygen concentration and the sulfur dioxide concentration in the raw gas maintain the most suitable conversion ratio, so that the sulfur dioxide conversion rate is always maintained at a high level;

[0040] (3) In addition, when the third catalyst bed layer overheats during the catalytic oxidation of sulfur dioxide, an appropriate amount of cold air is introduced through the second air supply valve to urgently cool the third catalyst bed layer to prevent the third catalyst bed layer from being deactivated due to overheating, thereby maximizing the sulfur dioxide conversion rate;

[0041] (4) An activated carbon reactor is arranged at the tail end of the device, so that the sulfur dioxide in the non-condensable gas discharged from the condenser is catalytically oxidized to sulfur trioxide, and then sprayed with demineralized water to form dilute sulfuric acid, which is then refluxed to the condenser to spray sulfur trioxide to obtain sulfuric acid with a high concentration. No wastewater is generated during the whole process, and the tail gas from the activated carbon reactor meets the emission standards, that is, the sulfur dioxide concentration is extremely low and meets the emission indicators.

[0042] The process proposed by the present invention adjusts the oxygen concentration of the catalyst bed according to the raw gas concentration working conditions, urgently cools the over-temperature catalyst bed, and uses an activated carbon reactor to treat a small amount of sulfur dioxide discharged after condensation in the condenser to convert it into sulfuric acid. Multiple measures ensure that under various working conditions, the total conversion rate of sulfur dioxide is greater than or equal to 99.2%.

[0043] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, may be considered to be part of the inventive subject matter of the present disclosure, provided such concepts are not mutually inconsistent.

[0044] The foregoing and other aspects, embodiments and features of the present invention can be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will be apparent from the following description or learned from the practice of the specific embodiments according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The accompanying drawings are not drawn to scale according to actual reference objects. In the accompanying drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For the sake of clarity, not every component is labeled in each figure. Now, embodiments of various aspects of the present invention will be described by way of example and with reference to the accompanying drawings, in which:

[0046] Figure 1 It is a process flow chart of the present invention;

[0047] Figure 2 It is a structural schematic diagram of the sulfur dioxide converter of the present invention.

[0048] 1-First catalyst bed 2-Second catalyst bed 3-Third catalyst bed 4-Fourth catalyst bed 5-First air supply valve 6-Second air supply valve 7-Interlayer heat exchanger DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs.

[0050] The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular form of "a", "an" or "the" and other similar words do not indicate a quantitative limitation, but indicate the existence of at least one. "Include" or "comprise" and other similar words mean that the elements or objects appearing before "include" or "comprise" include the features, wholes, steps, operations, elements and / or components listed after "include" or "comprise", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0051] like Figure 1As shown, an embodiment of the present application provides a device for preparing sulfuric acid from wet acid gas, comprising an incinerator, a first waste heat boiler, a sulfur dioxide converter, a second waste heat boiler, a condenser and an activated carbon reactor connected in sequence through pipelines.

[0052] The incinerator is used for burning the acid gas containing hydrogen sulfide to generate the first process gas rich in sulfur dioxide.

[0053] The incinerator is provided with an air intake pipe and a fuel replenishing pipe. The air intake pipe is used to introduce acidic gas and air containing hydrogen sulfide into the incinerator. The air intake pipe is provided with a second branch pipe connected to the condenser. The second branch pipe is used to mix the hot air heated by the condenser with the acidic gas containing hydrogen sulfide to replenish air and oxygen; the fuel replenishing pipe is used to introduce fuel into the incinerator so that hydrogen sulfide can be fully burned to generate sulfur dioxide; the furnace of the incinerator is connected to the first waste heat boiler through a pipeline.

[0054] The first waste heat boiler is a high-temperature waste heat boiler, which is used to exchange heat with the first process gas from the incinerator to reduce the temperature of the first process gas and heat the water in the first waste heat boiler to form steam.

[0055] The first waste heat boiler includes a first shell, a first heat exchange tube and a first steam drum. The first heat exchange tube is arranged in the inner cavity of the first shell. The inlet of the first heat exchange tube is connected to the furnace of the incinerator through a pipeline. Therefore, the first process gas from the incinerator directly enters the first heat exchange tube to exchange heat with the water in the inner cavity of the first shell. The outlet of the first heat exchange tube is connected to the inlet at the top of the sulfur dioxide converter through a pipeline; the inlet of the first steam drum is connected to the inner cavity of the first shell, and the outlet of the first steam drum is connected to the interlayer heat exchanger. The water in the inner cavity of the first shell is heated by the high-temperature first process gas to become water vapor and enter the first bubble, and then enters the interlayer heat exchanger through the pipeline for heat exchange.

[0056] The sulfur dioxide converter is used to convert sulfur dioxide in the first process gas into sulfur trioxide. It is the main conversion device for sulfur dioxide. Therefore, it is crucial to control and adjust the process conditions of the sulfur dioxide converter to maintain a suitable reaction environment for the sulfur dioxide catalytic oxidation process to improve the conversion rate of sulfur dioxide.

[0057] The sulfur dioxide converter is a vertical multi-stage catalytic bed converter, including a first catalyst bed 1, a second catalyst bed 2, a third catalyst bed 3 and a fourth catalyst bed 4 arranged in sequence from top to bottom, and the inlet and outlet of the second catalyst bed 2 are respectively provided with a first air supply valve 5 and a second air supply valve 6 for supplementing oxygen and emergency cooling.

[0058] An interlayer heat exchanger is provided between the second catalyst bed and the third catalyst bed, and between the third catalyst bed and the fourth catalyst bed; the inlet and outlet of the second catalyst bed are provided with a first transverse porous air tube array and a second transverse porous air tube array, respectively.

[0059] Air filters are provided at the air inlets of the first air supply valve and the second air supply valve.

[0060] The first catalyst bed 1 is filled with a platinum-based catalyst, and the height of the first catalyst bed 1 is 500 to 1000 mm;

[0061] The platinum-based catalyst has an outer dimension of 150*150*600mm or 150*150*300mm and is a 60-hole honeycomb catalyst. The carrier used by the platinum-based catalyst is titanium dioxide.

[0062] The second catalyst bed 2, the third catalyst bed 3 and the fourth catalyst bed 4 are all loaded with vanadium-based catalysts, and the heights of the second catalyst bed 2, the third catalyst bed 3 and the fourth catalyst bed 4 are 500-600 mm.

[0063] The first air supply valve passes the hot air coming out of the third heat exchange tube into the first transverse porous air tube array, and the hot air is mixed with the process gas coming out of the first catalyst bed layer and then enters the second catalyst bed layer, which is used to supplement oxygen and emergency cooling for the second catalyst bed layer. Specifically, the air inlet of the first air supply valve 5 is connected to the third heat exchange tube through the first branch pipe, and the air outlet of the first air supply valve 5 is connected to the first transverse porous air tube array. The hot air is evenly distributed through the first transverse porous air tube array, and is easier to mix evenly with the process gas coming out of the first catalyst bed layer. The first air supply valve 5 adjusts the flow rate of hot air entering the second catalyst bed layer according to the sulfur dioxide concentration in the raw gas, so that the oxygen concentration and the sulfur dioxide concentration in the raw gas maintain the most suitable conversion ratio, so that the conversion rate of sulfur dioxide is always maintained at a high level.

[0064] The second air supply valve passes cold air into the second transverse porous air tube, and the cold air is mixed with the process gas coming out of the second catalyst bed and then enters the third catalyst bed, which is used to supplement oxygen and emergency cooling for the third catalyst bed. Specifically, the air outlet of the second air supply valve 6 is connected to the second transverse porous air tube, and the cold air is evenly distributed through the second transverse porous air tube, and is easier to mix evenly with the process gas coming out of the second catalyst bed, so that when the third catalyst bed is overheated during the catalytic oxidation of sulfur dioxide, an appropriate amount of cold air is passed through the second air supply valve to urgently cool the third catalyst bed, thereby avoiding the deactivation of the third catalyst bed due to overheating and maximizing the sulfur dioxide conversion rate.

[0065] Air filters are provided at the air inlets of the first air supply valve 5 and the second air supply valve 6. The filtered hot air is delivered to the first transverse porous air tube array, while the filtered cold air is delivered to the second transverse porous air tube array.

[0066] like Figure 2 As shown, the two interlayer heat exchangers 7 of the embodiment of the present application are respectively arranged between the second catalyst bed 2 and the third catalyst bed 3, and between the third catalyst bed 3 and the fourth catalyst bed 4; the inlet of the interlayer heat exchanger 7 is connected to the outlet of the first steam drum or the second steam drum, or the inlet of the interlayer heat exchanger is connected to the first steam drum and the second steam drum through two pipes, so that the water vapor generated by the first steam drum or the second steam drum, or the water vapor generated by both the first steam drum and the second steam drum, enters the interlayer heat exchanger for transferring heat to the reaction process gas in the sulfur dioxide converter.

[0067] The second waste heat boiler is a medium temperature waste heat boiler, which is used to exchange heat with the second process gas from the sulfur dioxide converter, reduce the temperature of the second process gas, and heat the water in the second waste heat boiler to form water vapor. The second process gas contains a large amount of sulfur trioxide gas and a small amount of sulfur dioxide gas.

[0068] The second waste heat boiler includes a second shell, a second heat exchange tube and a second steam drum. The second heat exchange tube is arranged in the inner cavity of the second shell, and the inlet of the second heat exchange tube is connected to the outlet of the sulfur dioxide converter through a pipeline, so that the second process gas from the sulfur dioxide converter directly enters the second heat exchange tube and exchanges heat with the water in the inner cavity of the second shell. The outlet of the second heat exchange tube is connected to the inner cavity of the third shell of the condenser through a pipeline; the inlet of the second steam drum is connected to the inner cavity of the second shell, and the outlet of the second steam drum is connected to the interlayer heat exchanger. The water in the inner cavity of the second shell is heated by the second process gas to become water vapor and enter the second steam drum, and then enters the interlayer heat exchanger through the pipeline for heat exchange.

[0069] The condenser is used to condense the second process gas, so as to cool the sulfur trioxide in the second process gas and form a sulfuric acid solution with a high concentration under the spraying of dilute sulfuric acid.

[0070] The condenser includes a third shell, a third heat exchange tube, a second spray device and an electrostatic demister. The inlet of the inner cavity of the third shell is connected to the outlet of the second heat exchange tube through a pipeline, and the outlet of the inner cavity of the third shell is connected to the inlet of the activated carbon reactor through a pipeline; the third heat exchange tube is arranged in the inner cavity of the third shell, the inlet of the third heat exchange tube is passed through cold air, the outlet of the third heat exchange tube is connected to the first air supply valve through the first branch pipe, and is connected to the air intake pipe through the second branch pipe; the second spray device is arranged at the upper part of the inner cavity of the third shell, the inlet of the second spray device is connected to the activated carbon reactor through a reflux pipe, and the dilute sulfuric acid from the activated carbon reactor is sprayed downward, so that sulfur trioxide in the second process gas contacts with water in the dilute sulfuric acid to form sulfuric acid; the electrostatic demister is arranged at the top of the inner cavity of the third shell and is located above the second spray device, and the electrostatic demister is used to remove acid mist.

[0071] During operation, the second process gas enters the inner cavity of the third shell, exchanges heat with the cold air in the third heat exchange tube and is condensed. The dilute sulfuric acid sprayed by the second spray device contacts the sulfur trioxide in the second process gas to generate a sulfuric acid solution with a higher concentration, and the third process gas is obtained at the same time. The sulfuric acid solution is discharged and stored through the liquid outlet of the third shell, while the third process gas (containing a small amount of sulfur dioxide) enters the activated carbon reactor after passing through the electric demisting at the top of the inner cavity of the third shell. At the same time, the air in the third heat exchange tube is heated to form hot air, and enters the first air supply valve (sulfur dioxide converter) and the air inlet pipe (incinerator) through the first branch pipe and the second branch pipe respectively, which is used to supplement the oxygen concentration in the sulfur dioxide converter and to supply air and oxygen to the incinerator.

[0072] The activated carbon reactor is used to catalytically oxidize sulfur dioxide in the third process gas delivered from the condenser into sulfur trioxide, and form dilute sulfuric acid under the spraying of desalted water.

[0073] The activated carbon reactor is equipped with an activated carbon catalyst bed and a first spray device. The activated carbon loading capacity of the activated carbon catalyst bed is 80-100m 3 , used for catalytically oxidizing sulfur dioxide into sulfur trioxide; the first spraying device is used for spraying desalted water to convert the generated sulfur trioxide into sulfuric acid; a reflux pipe is connected between the activated carbon reactor and the condenser, and the reflux pipe is used to reflux the dilute sulfuric acid in the activated carbon reactor to the second spraying device, and the dilute sulfuric acid sprayed by the second spraying device contacts with the sulfur trioxide in the condenser to generate sulfuric acid.

[0074] Through the setting of the activated carbon reactor, a small amount of sulfur dioxide in the third process gas is catalytically oxidized, and the formed dilute sulfuric acid is refluxed to the condenser to react with sulfur trioxide to form sulfuric acid. No wastewater is generated, which further increases the conversion rate of sulfur dioxide. Moreover, the remaining tail gas from the activated carbon reactor meets the emission standards, that is, the sulfur dioxide content is extremely low and meets the emission indicators.

[0075] The present application also provides a process for preparing sulfuric acid by wet acid gas, wherein sulfuric acid is prepared by using the device for preparing sulfuric acid by wet acid gas as described above, and the process comprises the following steps:

[0076] (1) Acidic gas containing hydrogen sulfide and air enter the incinerator and burn to generate a first process gas rich in sulfur dioxide; in addition, when the acidic gas containing hydrogen sulfide burns in the incinerator, fuel can be added to the incinerator through a fuel replenishing pipe, and the fuel is any one or more of natural gas and hydrocarbon compounds, so that hydrogen sulfide is fully burned to generate sulfur dioxide;

[0077] (2) The first process gas enters the first waste heat boiler for heat exchange and cooling, and then enters the sulfur dioxide converter. The water in the first waste heat boiler is heated to form steam, which enters the first steam drum and then enters the interlayer heat exchanger through a pipeline to transfer heat to the catalyst bed.

[0078] (3) The sulfur dioxide in the first process gas is converted into sulfur trioxide in the sulfur dioxide converter to obtain a second process gas rich in sulfur trioxide; the flow rate of hot air entering the second catalyst bed is adjusted through the first air supply valve according to the concentration of sulfur dioxide in the first process gas to adjust the oxygen concentration and heat transfer of the second catalyst bed; when the third catalyst bed is overheated, cold air is introduced into the third catalyst bed through the second air supply valve for emergency cooling to prevent the catalyst bed from losing activity due to overheating;

[0079] (4) The second process gas enters the second waste heat boiler for heat exchange and cooling. The water in the second waste heat boiler is heated to form water vapor. The water vapor enters the interlayer heat exchanger through the pipeline to transfer heat to the catalyst bed. The second process gas then enters the condenser for heat exchange with air to be condensed, so that the sulfur trioxide in the second process gas is condensed and forms sulfuric acid under the spray of dilute sulfuric acid. At the same time, the obtained third process gas enters the activated carbon reactor. A part of the hot air heated by the condenser passes through the first branch pipe and the first air supply valve to enter the sulfur dioxide converter, and another part of the hot air passes through the second branch pipe to enter the air inlet pipe and mix with the acidic gas containing hydrogen sulfide for air supply and oxygen supply.

[0080] (5) The sulfur dioxide in the third process gas is converted into sulfur trioxide under catalytic oxidation by the activated carbon catalyst bed, and the generated sulfur trioxide is contacted with desalted water to obtain dilute sulfuric acid, and the sulfur dioxide in the remaining tail gas meets the emission standards;

[0081] (6) The dilute sulfuric acid generated in the activated carbon reactor enters the condenser through a reflux pipe to spray the sulfur trioxide inside the condenser, thereby converting the sulfur trioxide into sulfuric acid without generating wastewater.

[0082] Example 1

[0083] The acidic gas containing hydrogen sulfide and fuel gas generated by the combustion of the upstream medium-sulfur coal are introduced into the incinerator for combustion at a temperature of 1000°C. Then the first process gas is heat exchanged by the high-temperature waste heat boiler and then removed from nitrogen oxides before entering the adjustable SO2 converter. The inlet temperature is 410°C and the inlet gas flow rate is 20503Nm 3 / h, the inlet SO2 concentration is 4.1%. The outlet temperature of the first catalyst bed is 500℃, the inlet temperature of the second catalyst bed is adjusted to 420℃ through the first air supply valve at the inlet, the outlet temperature of the second catalyst bed is 425℃, the inlet temperature of the third catalyst bed is adjusted to 390℃ through the second air supply valve at the outlet of the second catalyst bed, and the outlet temperature of the third catalyst bed is 392℃. The inlet temperature of the fourth catalyst bed is 390℃, and the outlet temperature of the fourth catalyst bed is 391℃. The total conversion rate of SO2 is 99.2%. After the second process gas at the outlet of the SO2 converter is heat-exchanged by the medium-temperature waste heat boiler, it enters the bottom of the condenser and exchanges heat with the cold air from the top of the condenser to condense into acid. The inlet temperature of the second process gas is 290℃ and the outlet temperature is 90℃. The third process gas at the outlet of the condenser is transported to the activated carbon reactor through a pipeline, where trace SO2 is catalytically oxidized to SO3 and then sprayed with desalted water to form dilute sulfuric acid, which returns to the top of the condenser for spraying. The final SO2 content of the third process gas is 5mg / m 3 Then it is discharged through the chimney.

[0084] Example 2

[0085] The acid gas and fuel gas containing acid gas generated by the combustion of the upstream low-sulfur coal are introduced into the incinerator for combustion at a combustion temperature of 1000°C. Subsequently, the first process gas is heat exchanged by the high-temperature waste heat boiler and then removed from nitrogen oxides before entering the adjustable SO2 converter, with an inlet temperature of 410°C, an inlet gas flow of 8167Nm3 / h, and an inlet SO2 concentration of 2.01%. The outlet temperature of the first catalyst bed is 463°C, the inlet temperature of the second catalyst bed is adjusted to 410°C through the first air supply valve at the inlet, and the outlet temperature of the second catalyst bed is 415°C. The inlet temperature of the third catalyst bed is adjusted to 390°C through the second air supply valve at the outlet of the second catalyst bed, and the outlet temperature of the third catalyst bed is 392°C. The inlet temperature of the fourth catalyst bed is 390°C, and the outlet temperature of the fourth catalyst bed is 391°C. The total SO2 conversion rate is 99.4%. The second process gas at the outlet of the SO2 converter is heat exchanged in the medium-temperature waste heat boiler, and then enters the bottom of the condenser to exchange heat with the cold air from the top of the condenser to condense into acid. The inlet temperature of the second process gas is 288°C and the outlet temperature is 85°C. The third process gas at the outlet of the condenser is transported to the activated carbon reactor through a pipeline. The trace SO2 is catalytically oxidized to SO3, and then sprayed with desalted water to form dilute sulfuric acid, which returns to the top of the condenser for spraying. The final SO2 content of the third process gas is 3mg / m3 Then it is discharged through the chimney.

[0086] Example 3

[0087] The acid gas and fuel gas generated by the combustion of the upstream medium-sulfur coal are introduced into the incinerator for combustion at a temperature of 1000°C. Then the first process gas is heat exchanged by the high-temperature waste heat boiler and then removed from nitrogen oxides before entering the adjustable SO2 converter. The inlet temperature is 410°C and the inlet gas flow rate is 20590Nm 3 / h, the inlet SO2 concentration is 3.72%. The outlet temperature of the first catalyst bed is 499℃, the second catalyst bed is adjusted to 420℃ through the first air supply valve at the inlet, the outlet temperature of the second catalyst bed is 425℃, the third catalyst bed is adjusted to 390℃ through the second air supply valve at the outlet of the second catalyst bed, and the outlet temperature of the third catalyst bed is 392℃. The inlet temperature of the fourth catalyst bed is 390℃, and the outlet temperature of the fourth catalyst bed is 391℃. The total conversion rate of SO2 is 99.2%. After the second process gas at the outlet of the SO2 converter is heat-exchanged by the medium-temperature waste heat boiler, it enters the bottom of the condenser and exchanges heat with the cold air from the top of the condenser to condense into acid. The inlet temperature of the second process gas is 290℃ and the outlet temperature is 90℃. The third process gas at the outlet of the condenser is transported to the activated carbon reactor through a pipeline. The trace SO2 is catalytically oxidized to SO3, and then sprayed with desalted water to form dilute sulfuric acid, which returns to the top of the condenser for spraying. The final SO2 content of the third process gas is 5mg / m 3 Then it is discharged through the chimney.

[0088] Example 4

[0089] The acid gas and fuel gas generated by the combustion of upstream high-sulfur coal are introduced into the incinerator for combustion at a temperature of 1100°C. Then the first process gas is heat exchanged by a high-temperature waste heat boiler and then removed from nitrogen oxides before entering the adjustable SO2 converter. The inlet temperature is 430°C and the inlet gas flow rate is 20802Nm 3 / h, the inlet SO2 concentration is 5.1%. The outlet temperature of the first catalyst bed is 541℃, the second catalyst bed is adjusted to 430℃ through the first air supply valve at the inlet, the outlet temperature of the second catalyst bed is 455℃, the third catalyst bed is adjusted to 400℃ through the second air supply valve at the outlet of the second catalyst bed, the outlet temperature of the third catalyst bed is 410℃, the inlet temperature of the fourth catalyst bed is 400℃, and the outlet temperature of the fourth catalyst bed is 405℃. The total conversion rate of SO2 is 99.5%. The second process gas at the outlet of the SO2 converter is heat exchanged by the medium-temperature waste heat boiler, and then enters the bottom of the condenser and exchanges heat with the cold air from the top of the condenser to condense into acid. The inlet temperature of the second process gas is 295℃ and the outlet temperature is 90℃. The third process gas at the outlet of the condenser is transported to the activated carbon reactor through a pipeline. The trace SO2 is catalytically oxidized to SO3, and then sprayed with desalted water to form dilute sulfuric acid, which returns to the top of the condenser for spraying. The final SO2 content of the third process gas is 8mg / m 3 Then it is discharged through the chimney.

[0090] Example 5

[0091] The acid gas and fuel gas generated by the combustion of the upstream medium-sulfur coal are introduced into the incinerator for combustion at a temperature of 1000°C. Then the first process gas is heat exchanged by the high-temperature waste heat boiler and then removed from nitrogen oxides before entering the adjustable SO2 converter. The inlet temperature is 390°C and the inlet gas flow rate is 9258Nm 3 / h, the inlet SO2 concentration is 4.1%. The outlet temperature of the first catalyst bed is 530℃, the inlet temperature of the second catalyst bed is adjusted to 390℃ through the first air supply valve at the inlet, and the outlet temperature of the second catalyst bed is 405℃. The inlet temperature of the third catalyst bed is adjusted to 400℃ through the second air supply valve at the outlet of the second catalyst bed, the outlet temperature of the third catalyst bed is 410℃, the inlet temperature of the fourth catalyst bed is 400℃, and the outlet temperature of the fourth catalyst bed is 405℃. The total conversion rate of SO2 is 99.2%. After the second process gas at the outlet of the SO2 converter is heat-exchanged by the medium-temperature waste heat boiler, it enters the bottom of the condenser and exchanges heat with the cold air from the top of the condenser to condense into acid. The inlet temperature of the second process gas is 296℃ and the outlet temperature is 89℃. The third process gas at the outlet of the condenser is transported to the activated carbon reactor through a pipeline. The trace SO2 is catalytically oxidized to SO3, and then sprayed with desalted water to form dilute sulfuric acid, which returns to the top of the condenser for spraying. The final SO2 content of the third process gas is 10mg / m 3 Then it is discharged through the chimney.

[0092] Example 6

[0093] The acid gas and fuel gas generated by the combustion of upstream high-sulfur coal are introduced into the incinerator for combustion at a temperature of 1100°C. Then the first process gas is heat exchanged by a high-temperature waste heat boiler and then removed from nitrogen oxides before entering the adjustable SO2 converter. The inlet temperature is 410°C and the inlet gas flow rate is 15828Nm 3 / h, the inlet SO2 concentration is 5.05%. The outlet temperature of the first catalyst bed is 519℃, the second catalyst bed is adjusted to 410℃ through the first air supply valve at the inlet, the outlet temperature of the second catalyst bed is 422℃, the third catalyst bed is adjusted to 400℃ through the second air supply valve at the outlet of the second catalyst bed, the outlet temperature of the third catalyst bed is 409℃, the inlet temperature of the fourth catalyst bed is 390℃, and the outlet temperature of the fourth catalyst bed is 400℃. The total conversion rate of SO2 is 99.7%. The second process gas at the outlet of the SO2 converter is heat exchanged by the medium-temperature waste heat boiler, and then enters the bottom of the condenser and exchanges heat with the cold air from the top of the condenser to condense into acid. The inlet temperature of the second process gas is 289℃ and the outlet temperature is 88℃. The third process gas at the outlet of the condenser is transported to the activated carbon reactor through a pipeline. The trace SO2 is catalytically oxidized to SO3, and then sprayed with desalted water to form dilute sulfuric acid and returned to the top of the condenser for spraying. The final SO2 content of the third process gas is 5mg / m 3 Then it is discharged through the chimney.

[0094] Example 7

[0095] The acid gas and fuel gas generated by the combustion of upstream low-sulfur coal are introduced into the incinerator for combustion at a temperature of 1000°C. Then the first process gas is heat exchanged by a high-temperature waste heat boiler and then removed from nitrogen oxides before entering the adjustable SO2 converter. The inlet temperature is 390°C and the inlet gas flow rate is 8050Nm 3 / h, the inlet SO2 concentration is 1.98%. The outlet temperature of the first catalyst bed is 440℃, the inlet temperature of the second catalyst bed is adjusted to 390℃ through the first air supply valve at the inlet, the outlet temperature of the second catalyst bed is 395℃, the inlet temperature of the third catalyst bed is adjusted to 390℃ through the second air supply valve at the outlet of the second catalyst bed, the outlet temperature of the third catalyst bed is 393℃, the inlet temperature of the fourth catalyst bed is 390℃, and the outlet temperature of the fourth catalyst bed is 392℃. The total conversion rate of SO2 is 99.5%. The second process gas at the outlet of the SO2 converter is heat exchanged by the medium-temperature waste heat boiler, and then enters the bottom of the condenser and exchanges heat with the cold air from the top of the condenser to condense into acid. The inlet temperature of the second process gas is 290℃ and the outlet temperature is 90℃. The third process gas at the outlet of the condenser is transported to the activated carbon reactor through a pipeline. The trace SO2 is catalytically oxidized to SO3, and then sprayed with desalted water to form dilute sulfuric acid, which returns to the top of the condenser for spraying. The final SO2 content of the third process gas is 2mg / m 3 Then it is discharged through the chimney.

[0096] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A device for preparing sulfuric acid from wet acidic gas, characterized in that: It includes an incinerator, a first waste heat boiler, a sulfur dioxide converter, a second waste heat boiler, a condenser and an activated carbon reactor which are sequentially connected through pipelines; The sulfur dioxide converter comprises a first catalyst bed, a second catalyst bed, a third catalyst bed and a fourth catalyst bed arranged in sequence from top to bottom, the inlet and outlet of the second catalyst bed are respectively provided with a first air supply valve and a second air supply valve for supplementing oxygen and emergency cooling, and an interlayer heat exchanger is provided between the second catalyst bed and the third catalyst bed, and between the third catalyst bed and the fourth catalyst bed; The condenser is connected to the first air supply valve via a first branch pipe; An activated carbon catalytic bed and a first spraying device are provided inside the activated carbon reactor. The first spraying device is used to spray desalted water. A reflux pipe is connected between the activated carbon reactor and the condenser. The reflux pipe is used to reflux the dilute sulfuric acid in the activated carbon reactor to the condenser to spray the sulfur trioxide inside it.

2. The device for preparing sulfuric acid from wet acidic gas according to claim 1, characterized in that: The condenser comprises a third shell, a third heat exchange tube and a second spray device; The inner cavity of the third shell is connected to the second waste heat boiler and the activated carbon reactor through pipelines respectively; The third heat exchange tube is disposed in the inner cavity of the third shell, and the outlet of the third heat exchange tube is connected to the first air supply valve through the first branch pipe; The second spray device is arranged at the top end of the inner cavity of the third shell, and the inlet of the second spray device is connected to the outlet of the reflux pipe.

3. The device for preparing sulfuric acid from wet acidic gas according to claim 2, characterized in that: The incinerator is provided with an air intake pipe and a fuel replenishing pipe, and a second branch pipe is provided between the air intake pipe and the outlet of the third heat exchange pipe; The inlet and outlet of the second catalyst bed are respectively provided with a first transverse porous air tube array and a second transverse porous air tube array; The first air supply valve passes the hot air from the third heat exchange tube into the first transverse porous air tube array, and the hot air is mixed with the process gas from the first catalyst bed and then enters the second catalyst bed to supplement oxygen and emergency cooling for the second catalyst bed; The second air supply valve passes cold air into the second transverse porous air tube array, and the cold air is mixed with the process gas from the second catalyst bed and then enters the third catalyst bed to supplement oxygen and emergency cooling for the third catalyst bed; Air filters are provided at the air inlets of the first air supply valve and the second air supply valve.

4. The device for preparing sulfuric acid from wet acidic gas according to claim 3, characterized in that: The first waste heat boiler comprises a first shell, a first heat exchange tube and a first steam drum, wherein the first heat exchange tube is arranged in the inner cavity of the first shell, the inlet and outlet of the first heat exchange tube are respectively connected to the incinerator and the sulfur dioxide converter, and the first steam drum is connected to the inner cavity of the first shell; The second waste heat boiler comprises a second shell, a second heat exchange tube and a second steam drum, the second heat exchange tube is arranged in the inner cavity of the second shell, the inlet and outlet of the second heat exchange tube are respectively connected to the sulfur dioxide converter and the condenser, and the second steam drum is in communication with the inner cavity of the second shell; The inlet of the interlayer heat exchanger is connected to the outlet of the first steam drum and / or the second steam drum, so that the water vapor generated by the first steam drum and / or the second steam drum enters the interlayer heat exchanger to exchange heat with the first process gas and the second process gas.

5. The device for preparing sulfuric acid from wet acidic gas according to claim 1, characterized in that: The first catalyst bed is filled with a platinum-based catalyst, and the height of the first catalyst bed is 500 to 1000 mm; The platinum-based catalyst has an outer dimension of 150*150*600mm or 150*150*300mm and a 60-hole honeycomb catalyst, and the carrier used by the platinum-based catalyst is titanium dioxide; The second catalyst bed layer, the third catalyst bed layer and the fourth catalyst bed layer are all loaded with vanadium-based catalysts, and the heights of the second catalyst bed layer, the third catalyst bed layer and the fourth catalyst bed layer are 500-600 mm.

6. The device for preparing sulfuric acid from wet acidic gas according to claim 1, characterized in that: The activated carbon loading amount of the activated carbon catalyst bed is 80-100 m 3 .

7. The device for preparing sulfuric acid from wet acidic gas according to claim 1, characterized in that: An electrostatic demister is provided at the top of the condenser, and the electrostatic demister is used to remove acid mist.

8. A process for preparing sulfuric acid from wet acidic gas, characterized in that: The device for preparing sulfuric acid from wet acidic gas as claimed in claim 3 is used to prepare sulfuric acid, and the process comprises the following steps: (1) Acidic gas containing hydrogen sulfide and air enter the incinerator and burn to generate a first process gas rich in sulfur dioxide; (2) the first process gas enters the first waste heat boiler for heat exchange and cooling, and then enters the sulfur dioxide converter; (3) The sulfur dioxide in the first process gas is converted into sulfur trioxide in the sulfur dioxide converter to obtain a second process gas rich in sulfur trioxide; the flow rate of hot air entering the second catalyst bed is adjusted through the first air supply valve according to the concentration of sulfur dioxide in the first process gas, and oxygen is supplemented and heat is removed by the hot air. When the third catalyst bed is overheated, cold air is introduced into the third catalyst bed through the second air supply valve to perform emergency cooling; (4) After the second process gas enters the second waste heat boiler for heat exchange and cooling, it then enters the condenser for heat exchange with air for condensation, so that sulfur trioxide in the second process gas is condensed and forms sulfuric acid under the spray of dilute sulfuric acid. At the same time, the obtained third process gas enters the activated carbon reactor, and the hot air heated by the condenser enters the second catalyst bed through the first branch pipe and the first air supply valve; (5) The sulfur dioxide in the third process gas is converted into sulfur trioxide under catalytic oxidation by the activated carbon catalyst bed, and the generated sulfur trioxide is contacted with desalted water to obtain dilute sulfuric acid, and the sulfur dioxide in the remaining tail gas meets the emission standards; (6) The dilute sulfuric acid generated in the activated carbon reactor enters the condenser through a reflux pipe to spray the sulfur trioxide inside the condenser, thereby converting the sulfur trioxide into sulfuric acid without generating wastewater.

9. The process for preparing sulfuric acid from wet acidic gas according to claim 8, characterized in that: A portion of the hot air heated by the condenser is mixed with the acidic gas containing hydrogen sulfide through the second branch pipe and then enters the incinerator; The water vapor generated by the first waste heat boiler and / or the second waste heat boiler enters the interlayer heat exchanger.

10. The process for preparing sulfuric acid from wet acidic gas according to claim 8, characterized in that: When the acid gas containing hydrogen sulfide is burned in the incinerator, fuel is added to the incinerator through a fuel adding pipe. The fuel is any one or more of natural gas and hydrocarbon compounds.

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