CN214319665U

CN214319665U - Claus tail gas treatment system

Info

Publication number: CN214319665U
Application number: CN202023217391.2U
Authority: CN
Inventors: 王昱飞
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-12-28
Filing date: 2020-12-28
Publication date: 2021-10-01
Anticipated expiration: 2030-12-28

Abstract

The utility model discloses a Claus tail gas treatment system, which comprises an incinerator, a quenching unit and a desulfurization unit which are connected in sequence, wherein Claus tail gas is introduced into the input end of the incinerator, the output end of the incinerator is connected with the input end of the quenching unit, the quenching unit is used for cooling incineration flue gas from the incinerator, and the output end of the quenching unit is connected with the desulfurization unit; the desulfurization unit comprises an electrolytic cell and an absorption towerAnd a desorption tower, wherein the electrolytic cell is used for absorbing low-concentration SO₂And reacted to form H₂SO₃The lower end of the absorption tower is communicated with the output end of the quenching unit, the upper end of the absorption tower is provided with a desulfurized flue gas discharge port, an upper liquid inlet is communicated with the output end of the cathode region salt solution, and a lower liquid outlet is communicated with the input end of the cathode region salt solution; the upper part of the desorption tower is provided with high-concentration SO₂And the lower liquid inlet is communicated with the salt solution output end of the anode region, and the upper liquid outlet is communicated with the salt solution input end of the anode region. The method can reduce energy consumption and cost while ensuring the sulfur recovery rate, and has wide application range.

Description

Claus tail gas treatment system

Technical Field

The utility model relates to a contain sulphur tail gas treatment, concretely relates to claus tail gas treatment system.

Background

In the production processes of petrochemical industry, coal chemical industry and the like, sulfur in raw materials is finally converted into acid gas containing hydrogen sulfide in the processing process and must be treated or recycled. Currently, the claus sulphur recovery process is commonly used to convert hydrogen sulphide into sulphur.

The Claus sulfur recovery process comprises a thermal reaction section and a plurality of catalytic reaction sections, namely, the Claus sulfur recovery process contains H₂The acid gas of S is incompletely combusted with air in the combustion furnace to obtain part H₂SO formed by combustion of S₂And has a moiety H₂S and SO₂Reacting at high temperature to form elemental sulfur, limited by thermodynamic conditions, with the remainder of H₂S and SO₂Enters a catalytic reaction section to continue the reaction for generating the elemental sulfur under the action of the catalyst. And sulfur condensers are arranged at the downstream of the thermal reaction section and each catalytic reaction section to condense and separate the elemental sulfur generated by the reaction, and the condensed liquid sulfur enters a liquid flow storage tank to be directly transported outwards with the liquid sulfur or is formed into solid sulfur to be transported outwards.

In the Claus sulfur recovery process, due to the limitation of chemical equilibrium and reversible reaction at the reaction temperature, even under the condition of good equipment and operation conditions, the highest sulfur recovery rate can only reach 95-97 percent by using a catalyst with good activity and a three-stage Claus process, and the emission is further reduced by adopting a sulfur recovery tail gas treatment process. At present, the flue gas SO of the sulfur recovery device, which can meet the requirements in the emission standard of pollutants for petroleum refining industry₂Specific discharge limits (100 mg/m)³) The technology of (1) comprises: reducing SO in flue gas independently researched and developed by Chinese petrifaction₂Emission concentration technique LS-DeGAS; secondly, flue gas alkali washing technology; ③ ammonia method tail gas desulfurization technology; organic amine SO removal₂Tail gas treatment technology; superYoukouse + flue gas alkali washing technology and the like.

LS-DeGAS is developed by research institute of Qilu branch petrochemical corporation in China for reducing SO in sulfur tail gas₂The core of the emission concentration technology is as follows: high-efficiency organic sulfur hydrolysis catalyst, matched high-efficiency desulfurizer, independent regeneration system, absorption tower temperature control and liquid sulfur removalGas and exhaust gas treatment technology, and the like. The technology has the characteristics of source control, resource recovery and the like, does not produce secondary pollution, has higher sulfur recovery rate, but has general fluctuation resistance, needs high-efficiency organic sulfur hydrolysis catalyst, and has high fine operation requirement during start-up and shut-down.

The flue gas alkali washing technology is two-stage Claus + SCOT + tail gas incineration + sodium flue gas desulfurization, the operation adaptability is strong, the reliability is high, the fluctuation resistance is strong, and SO can be adjusted by the process during start-up and shut-down₂The emission mass concentration is controlled to be 50mg/m³The following. But the investment and the operation cost are relatively high, the generated salt-containing wastewater is discharged after reaching the standard after being treated, and the treatment cost is increased.

The ammonia process tail gas desulfurization is two-stage Claus + tail gas incineration + ammonia process flue gas desulfurization, acid gas generates Claus tail gas through the two-stage Claus, the Claus tail gas enters a desulfurization tower after being incinerated to be in countercurrent contact with circulating slurry for washing, cooling and absorption, and in the process, the circulating liquid containing an ammonia absorbent absorbs SO in the flue gas₂And reacting to generate ammonium sulfite, carrying out oxidation reaction on the liquid containing the ammonium sulfite and air blown from the bottom of the desulfurization tower to oxidize the ammonium sulfite into ammonium sulfate, and concentrating, crystallizing and drying to obtain the ammonium sulfate. No waste liquid and waste residue are discharged in the treatment process, the SCOT unit can be omitted in the newly-built device, and the investment and operation cost are relatively low. But has the problems of ammonia escape and aerosol formation possibility, poor environment of ammonium sulfate crystallization site, high particle emission in flue gas and the like.

Organic amine SO removal₂Tail gas treatment technology namely Cansolv-SO₂The washing technology is that acid gas enters a tail gas incinerator after passing through a sulfur production unit, flue gas with the temperature of 260 ℃ after waste heat recovery is quenched to about 60 ℃ by washing liquid at the inlet of a cooling tower and then enters SO₂The absorption tower packing section is in reverse contact with the barren solution to remove SO in the tail gas₂And the purified tail gas is discharged into a chimney. The pickling water at the bottom of the cooling tower is discharged after being neutralized by alkali liquor. The technical advantages are that: purifying SO in tail gas₂The mass concentration can be reduced to 50mg/m³Further reducing the need for auxiliary caustic washing. The disadvantages are high grade of selected material, complex operation and high salt contentThe wastewater is discharged after reaching standards after being treated, and a destabilization salt system is required to be arranged to ensure the absorption effect of barren solution.

The super Claus is developed by Holland Hefeng company on the basis of super Claus process, and the technical core is H₂The catalytic reduction to sulfur vapor precedes the selective oxidation of S. In order to meet the requirements of stricter environmental protection standards, sodium method alkaline washing is added after the ultra-excellent Claus direct oxidation technology to form a new combined process, SO that the sulfur removal rate reaches more than 99.9, the installation space is reduced by 40%, and the SO discharged by flue gas is reduced₂The mass concentration is less than 50mg/m³. The combined process has the advantages of simple flow, strong fluctuation capacity of antigen materials, relatively low investment and operation cost, relatively low sulfur recovery rate, and standard discharge of the generated high-salt-content wastewater after treatment.

Disclosure of Invention

The utility model aims at providing a Claus tail gas processing system, it can reduce energy consumption and cost when guaranteeing the sulphur rate of recovery, and application scope is wide.

The Claus tail gas treatment system comprises an incinerator, a quenching unit and a desulfurization unit which are connected in sequence, wherein Claus tail gas is introduced into the input end of the incinerator, the output end of the incinerator is connected with the input end of the quenching unit, the quenching unit is used for cooling incineration flue gas from the incinerator, and the output end of the quenching unit is connected with the desulfurization unit; the desulfurization unit comprises an electrolytic cell, an absorption tower and a desorption tower, the electrolytic cell comprises an electrolytic tank and an ion exchange membrane which divides the electrolytic tank into an anode area and a cathode area, and the anode area comprises an anode electrode and contains HSO₃ ^-A salt solution and an organic solvent in which a compound QH is dissolved, and a cathode region including a cathode electrode containing HSO₃ ^-、SO₃ ^2-A salt solution and an organic solvent in which a compound Q is dissolved, the organic solvent and the salt solution being immiscible with each other, a direct current power supply being applied between the anode electrode and the cathode electrode; the compound Q and the compound QH are compounds capable of generating PCET reaction, Q is in an oxidation state, and QH is in a reduction state; the lower end of the absorption tower is communicated with the output end of the quenching unit, and the upper end of the absorption tower is provided with desulfurized flue gasThe upper liquid inlet is communicated with the output end of the cathode region salt solution, and the lower liquid outlet is communicated with the input end of the cathode region salt solution; the upper part of the desorption tower is provided with high-concentration SO₂And the lower liquid inlet is communicated with the salt solution output end of the anode region, and the upper liquid outlet is communicated with the salt solution input end of the anode region.

Further, the compound capable of generating PCET reaction is anthraquinone compound or fluorescein compound, the organic solvent is natural or synthetic organic solvent capable of phase separation with water, preferably at least one of dichloromethane, trichloromethane, carbon tetrachloride, 1,2 dichloroethane, 1-butyl-3-methylimidazole hexafluorophosphate ionic liquid, sulfonated kerosene, ethyl acetate and cyclohexane.

Further, introducing a Q-rich organic solution generated by reacting QH dissolved in an organic solvent in the anode region into Q through a first circulating pump into the cathode region; and introducing a QH-rich organic solution generated by converting the Q reaction dissolved in the organic solvent in the cathode region into QH into the anode region by using a second circulating pump so as to maintain the continuous and stable electrochemical reaction.

Further, still include super Claus reaction unit, super Claus reaction unit includes super Claus reactor and sulphur condenser, super Claus reactor input lets in Claus tail gas, and the output communicates with sulphur condenser entry, sulphur condenser export communicates with burning furnace input.

The system further comprises a Scott reaction unit, wherein the Scott reaction unit comprises a hydrogenation reactor, a quench tower and an oxidation desulfurization tower which are sequentially connected; the Claus tail gas is introduced into the input end of the hydrogenation reactor and is used for reacting the Claus tail gas with reducing gas, so that the sulfur-containing components in the Claus tail gas are converted into H₂S; the quenching tower is used for cooling the process gas of the hydrogenation reactor; the oxidation desulfurization tower is used for carrying out oxidation desulfurization treatment on the process gas of the quenching tower so as to ensure that H in the process gas of the quenching tower₂S is converted into elemental sulfur; and the outlet of the oxidation desulfurization tower is communicated with the input end of the incinerator.

Compared with the prior art, the utility model following beneficial effect has.

1. The utility model discloses an burn remaining H in burning furnace will claus tail gas₂Conversion of S to SO₂. Then based on SO₂-HSO₃ ^--SO₃ ^2-Equilibration, i.e. HSO when acid is added₃ ^-Can release pure SO₂When alkali is added, HSO₃ ^-Can be converted into SO₃ ^2-Using SO in the salt solution in the cathode region₃ ^2-Absorbing low-concentration SO in incineration flue gas₂Post production of HSO₃ ^-Absorbing SO in the incineration flue gas₂The content is less than 50mg/Nm³Completely meets the latest national standard requirement. Under the action of current, the compound Q in the organic solution in the cathode region obtains electrons from the cathode electrode and contains HSO₃ ^-In the catholyte of⁺To form QH and SO in a reduced state₃ ^2-SO formed₃ ^2-For cyclic absorption of low-concentration SO₂Simultaneous regeneration of HSO₃ ^-The sensible heat and the heat loss of the temperature increase during the solvent regeneration are avoided, and the absorption of low-concentration SO is greatly reduced₂Energy consumption of (2). The compound QH in the organic solution in the anode region releases electrons and H⁺And returning to oxidized Q, releasing H⁺HSO in salt solution with anode region₃ ^-Reaction to form H₂SO₃Obtaining H₂SO₃React in a desorption tower to generate high-concentration SO₂And further realize low concentration SO₂To high concentration SO₂The conversion rate of the desorption reaction is greatly improved, and the problem of low concentration SO at present is effectively solved₂The recovery and separation technology has the technical problems of high energy consumption, low efficiency and poor stability.

2. The utility model discloses the utilization has high-efficient "Proton Coupling Electron Transfer (PCET)" reaction property's compound as the electrocatalyst, utilizes the PCET reaction to replace the hydrogen evolution oxygen evolution reaction that takes place on traditional electrode, does not need noble metal Pt as the catalyst when reducing electrolysis voltage by a wide margin, has reduced manufacturing cost by a wide margin. As the organic matter mainly contains C, H, O, N and other rich elements, the raw material has wide source and low price.

3. The utility model discloses select specific compound that has oleophylic hydrophobic property and can take place the PCET reaction as the catalyst of electrolytic reaction, all dissolve compound Q and compound QH in the organic solvent with salt solution mutually insoluble, during electrolytic reaction, compound Q and compound QH dissolve in organic phase almost completely, do not get into the aqueous phase to the easy oxidation problem of catalyst has been solved. Meanwhile, the compound Q and the compound QH are transferred between the cathode area and the anode area through the circulating pump, so that the exchange process of the catalyst is simplified, and the reaction efficiency is improved.

4. The utility model adopts sulfite as SO₂The adsorbent is inexpensive compared to the organic amine solution, and its absorption performance is less affected by other impurities. SO (SO)₂The absorption and desorption processes are carried out at lower temperature, the reaction condition is mild, and the material selection range is wide. And absorb each ton of SO₂The power consumption is about 800-1000 kWh, the energy consumption is basically stable, and the flue gas is not subjected to SO in the incineration flue gas₂The concentration influence.

5. Processing system can burn the low concentration SO in the flue gas₂Direct purification to high concentration SO₂To obtain high-concentration SO₂Can be directly used as the raw material for preparing downstream sulfuric acid, and realizes the trapped SO₂The resource utilization of the sulfur-containing material relieves the pressure of sulfur resource shortage in China. Or the obtained high concentration SO₂And the sulfur returns to the main incinerator of the Claus reaction unit, so that the sulfur recovery rate is improved.

Drawings

Fig. 1 is one of the schematic structural diagrams of the present invention;

fig. 2 is a second schematic structural diagram of the present invention;

fig. 3 is a third schematic structural diagram of the present invention;

FIG. 4 is a fourth schematic structural diagram of the present invention;

FIG. 5 is one of the reaction schemes of the electrolytic cell of the present invention;

FIG. 6 is a second reaction scheme of the electrolytic cell of the present invention.

In the figure, 1-electrolytic cell, 11-cathode zone, 12-anode zone, 13-ion exchange membrane, 14-cathode electrode, 15-anode electrode, 2-absorption column, 21-pump one, 22-pump two, 3-desorption column, 31-pump three, 32-pump four, 4-circulation pump one, 41-buffer tank one, 5-circulation pump two, 52-buffer tank two, 6-claus reaction unit, 61-main incinerator, 62-sulfur condenser, 63-claus reactor, 64-heat exchanger, 65-liquid sulfur tank, 7-scott reaction unit, 71-hydrogenation reactor, 72-quench tower, 73-oxidative desulfurization tower, 74-regeneration tower, 8-super claus reactor, 100-incinerator, 200-quench unit, 300-desulfurization unit.

Detailed Description

The present invention will be described in detail with reference to the accompanying drawings and specific embodiments.

First embodiment, referring to fig. 1, a claus tail gas treatment system is shown, which includes an incinerator 100, a quenching unit 200 and a desulfurization unit 300 connected in sequence, wherein claus tail gas is introduced into an input end of the incinerator 100, an output end of the incinerator is connected with an input end of the quenching unit 200, the quenching unit 200 is used for cooling incineration flue gas from the incinerator 100, and an output end of the quenching unit is connected with the desulfurization unit 300.

The desulfurization unit 300 comprises an electrolytic cell 1, an absorption tower 2 and a desorption tower 3, wherein the electrolytic cell 1 comprises an electrolytic tank and an ion exchange membrane 13 which divides the electrolytic tank into an anode area 12 and a cathode area 11, and the anode area 12 comprises an anode electrode 15 and contains HSO₃ ^-Salt solution and organic solvent dissolved with compound QH, cathode region 11 comprises cathode 14 electrode containing HSO₃ ^-、SO₃ ^2-A salt solution and an organic solvent in which the compound Q is dissolved, the organic solvent being immiscible with the salt solution, and a direct current power supply being applied between the anode electrode 15 and the cathode electrode 14. The compound Q and the compound QH are compounds capable of generating a PCET reaction, wherein Q is in an oxidation state and QH is in a reduction state. The compound QH is used as an anode electrocatalyst, and the compound Q is used as a cathode electrocatalyst.

The lower end of the absorption tower 2 is communicated with the output end of the quenching unit 200, the upper end of the absorption tower is provided with a desulfurized flue gas discharge port, the upper liquid inlet is communicated with the output end of the cathode area salt solution, and a pump 21 for driving the cathode area salt solution to move towards the upper liquid inlet of the absorption tower 2 is arranged on the communication pipeline. The liquid outlet at the lower part of the absorption tower 2 is communicated with the salt solution input end of the cathode area, and the communicating pipeline is provided with a driving absorption low-concentration SO₂And a second pump 22 for moving the salt solution toward the cathode region 11 of the electrolytic cell 1.

The upper part of the desorption tower 3 is provided with high-concentration SO₂A discharge port, a lower liquid inlet and an anode area 12 salt solution output end are communicated, and a third pump 31 for driving the anode area salt solution after the electrolytic reaction to move towards the desorption tower 3 is arranged on the communicating pipeline. A liquid outlet at the upper part of the desorption tower 3 is communicated with the salt solution input end of the anode area 12, and a pump IV 32 for driving the desorbed salt solution to move towards the anode area 12 of the electrolysis unit 1 is arranged on the communicating pipeline.

Referring to fig. 5, the electrolytic cell 1 is specifically: the ion exchange membrane 13 is an anion exchange membrane, and the anode electrode 15 and the cathode electrode 14 are both carbon fiber cloth. By using

As the cathode electrocatalyst Q, use is made of

As the anode electrocatalyst QH.

Respectively dissolving a compound Q and a compound QH in 1,2 dichloroethane, and adding 0.3 mol/L1-butyl-3-methylimidazole hexafluorosulfate ionic liquid as a supporting electrolyte, wherein the concentration of the compound Q and the concentration of the compound QH in 1,2 dichloroethane are both 0.2 mol/L. Respectively preparing 20 wt% of NaHSO₃Solution and 20% wt Na₂SO₃And (3) solution. Adding SO₂Introducing Na₂SO₃Reaction in solution to generate NaHSO₃So that the solution contains HSO₃ ^-、SO₃ ^2-And adjusting the pH of the solution to 6-7. Then adding NaHSO₃Solution and 1, 2-dichloroethane with compound QH dissolved thereinMixing the solution and introducing into an anode region, and adding Na with the pH of 6-7₂SO₃The solution and the 1, 2-dichloroethane solution dissolved with the compound Q are passed into the cathode region

Specifically, the Claus waste gas is introduced into an incinerator 100 for incineration at 1000 deg.C to convert sulfides in Claus tail gas into SO₂To obtain a solution containing low concentration of SO₂The incineration flue gas of (2). Then the incineration flue gas is treated by a quenching unit 200 and then is introduced into an absorption tower 2, and the concentration of SO is low₂Passing SO in the salt solution of the cathode region in the absorption column 2₃ ^2-Formation of HSO after absorption₃ ^-Flows into the electrolytic cell 1, and a direct current power is applied between the anode electrode 15 and the cathode electrode 14 to start an electrolytic reaction.

Under the action of the current, compound Q obtains two electrons from cathode electrode 14, from NaHSO₃Organic solvent with middle abstraction of proton to generate QH rich in reduction state and Na rich₂SO₃By pumping Na to the first pump 21₂SO₃The solution is introduced into an absorption tower 2 to absorb the low-concentration SO in the incineration flue gas₂Reconverting into NaHSO₃Then the NaHSO at the bottom of the absorption tower 2 is pumped by a second pump 22₃The solution is pumped back into the cathode region 11 of the cell 1 for use as catholyte. For charge balance in the cell, Na₂SO₃Absorption of low concentration SO₂Generated HSO₃ ^-Through the anion exchange membrane to the anode region 12. In order to maintain high absorption efficiency, the pH of the salt solution in the cathode region 11 needs to be maintained between 6 and 7, and the specific reaction is as follows:

Q+HSO₃ ^-+e→QH+SO₃ ^2-，

SO₃ ^2-+SO₂+H2O→2HSO₃ ^-，

and (3) total reaction: q + SO₂+H₂O→QH+HSO₃ ^-。

In the anode region 12, the compound QH releases electrons and H⁺And generating organic solvent rich in oxidation state Q, and releasing H⁺HSO in salt solution with the anode region 12₃ ^-And is penetratedHSO in solution passing through anion exchange membrane to reach anode salt₃ ^-Reaction to form H₂SO₃Will be enriched in H by pump III 31₂SO₃Introducing the salt solution into a desorption tower 3, controlling the working pressure of the desorption tower 3 to be 0.1-101325 Pa, and introducing H into the desorption tower 3₂SO₃Reaction to produce high concentration SO₂And further realize low concentration SO₂To high concentration SO₂Then the desorbed salt solution is returned by the pump iv 32 to the anode region 12 for use as anolyte. The specific reaction is as follows:

QH→Q+H⁺+e，

H⁺+HSO₃ ^-→H₂SO₃，

H₂SO₃→H₂O+SO₂，

and (3) total reaction: QH + HSO₃ ^-→Q+H₂O+SO₂。

After reacting for a period of time, introducing a Q-rich organic solution generated by reacting QH dissolved in an organic solvent in the anode region 12 into Q through a first circulating pump 4 into the cathode region 11; and a QH-rich organic solution generated by converting the Q reaction dissolved in the organic solvent in the cathode region 11 into QH is introduced into the anode region 12 through the second circulating pump 5 to maintain the continuous and stable electrochemical reaction. Meanwhile, in order to ensure the replacement efficiency of the organic solvent, a first buffer tank 41 and a second buffer tank 51 are respectively added on pipelines where the first circulating pump 4 and the second circulating pump 5 are located. It should be noted that the upper and lower positions of the organic solution and the salt solution may change with the difference of the organic solvent, that is, the density of the organic solution is greater than or equal to the density of the salt solution, the organic solution is located below the salt solution, and if the density of the organic solution is less than the density of the salt solution, the organic solution is located above the salt solution.

By adopting the treatment method, SO in the desulfurized flue gas treated by the absorption tower 2₂The concentration is not higher than 50mg/m³SO treated by a desorption tower 3₂The concentration is more than 99 percent, on one hand, the flue gas desulfurization is realized, the emission requirement of the flue gas is met, the desulfurization rate is improved, on the other hand, SO with the concentration of more than 99 percent is generated₂Obtaining high concentration SO₂Can be used for preparing sulfuric acid or reflowing again for Claus reaction, and realizes the purpose of burning SO in flue gas₂The resource utilization is realized. And no wastewater and waste residue are generated in the whole treatment process, so that additional treatment equipment is not required, the treatment cost is reduced, and the method is economic and environment-friendly.

The treatment process mainly consumes fuel gas in the incinerator 100 and electric energy in the desulfurization unit 300, and specific energy consumption values are shown in fig. 1.

TABLE 120 million tons Sulfur recovery, Main energy consumption for Claus Tail gas treatment as described in example I

Name (R)	Example one	Place of use
			Gas combustion	2700～2800m³/h	Incinerator
Electric power	2250kW	Desulfurization unit
			Cost of	About 1125 yuan/h, 900 ten thousand/year

See table 2 for comparison to conventional scott tail gas treatment process.

TABLE 220 million tons Sulfur recovery, Scott tail gas treatment method Main energy consumption

It can be known to compare table 1 and table 2, compares in conventional scott tail gas treatment method, adopts the embodiment of the utility model provides a claus tail gas treatment method energy consumption lower, the annual energy consumption cost of saving 1400 ten thousand yuan, under the prerequisite of guaranteeing desulfurization efficiency and sulphur rate of recovery, reduced treatment cost by a wide margin.

Referring to FIG. 2, the high concentration SO obtained in the desorber 3₂And (2) returning to a Claus reaction unit 6, wherein the Claus reaction unit 6 comprises a main incinerator 51, three sulfur condensers 62, two Claus reactors 63, three heat exchangers 64 and a liquid sulfur pool 65, and the liquid sulfur pool 65 is connected with all the sulfur condensers 62 in the Claus reaction unit 6 and is used for collecting liquid sulfur obtained in the sulfur condensers 62. Mixing acid gas and air, introducing the mixture into a main incinerator 61, connecting a first sulfur condenser 62 to the outlet of the main incinerator 61, connecting a first heat exchanger 64 to one side of the first sulfur condenser 62, and reheating the process gas passing through the first sulfur condenser 62 to a specified temperature. The outlet of the first heat exchanger 64 is connected with a first-stage Claus reactor 63, the outlet of the first-stage Claus reactor 63 is connected with a second sulfur condenser 62, the outlet of the second sulfur condenser 62 is connected with a second heat exchanger 64, the outlet of the second heat exchanger 64 is connected with a second-stage Claus reactor 63, the outlet of the second-stage Claus reactor 63 is connected with a third sulfur condenser 62, the outlet of the third sulfur condenser 62 is connected with a third heat exchanger 64, and Claus tail gas passing through the third heat exchanger 64 is mixed with air and gas generated by a liquid sulfur pool and then is introduced into the incinerator 100 for subsequent purification treatment.

In the second embodiment, in order to recover polysulfide and further improve the sulfur recovery rate, referring to fig. 3, a super claus reaction unit is additionally arranged between the incinerator 100 and the claus reaction unit 6, the super claus reaction unit comprises a super claus reactor 8 and a sulfur condenser 62, the input end of the super claus reactor 8 is introduced with claus tail gas generated by the claus reaction unit 6, the output end is communicated with the inlet of the sulfur condenser 62, the outlet of the sulfur condenser 62 is communicated with the input end of the incinerator 100, and the rest structure is the same as that of the first embodiment. The super claus reactor 8 is packed with a selective oxidation catalyst to further convert the sulfur compounds in the claus tail gas to elemental sulfur, and the captured liquid sulfur is directly transferred to the liquid sulfur pool 65 through the sulfur condenser 62, so the sulfur condenser 62 of the super claus reaction unit has the same structure as the sulfur condenser 62 of the claus reaction unit.

The treatment process mainly consumes fuel gas in the incinerator 100, electric power in the desulfurization unit 300, and steam in the super claus reaction unit, and specific energy consumption values are shown in fig. 3.

TABLE 320 million tons Sulfur recovery, Main energy consumption for Claus Tail gas treatment as described in example II

It can be known to contrast table 3 and table 2, compares in conventional scott tail gas treatment method, adopts the embodiment of the utility model provides a claus tail gas treatment method energy consumption lower, annual energy consumption cost 1870 ten thousand yuan, under the prerequisite of guaranteeing desulfurization efficiency and sulphur rate of recovery, reduced treatment cost by a wide margin.

In the third embodiment, in order to recover polysulfide and further improve the sulfur recovery rate, referring to fig. 4, a scott reaction unit 7 is additionally provided between the incinerator 100 and the claus reaction unit 6, and the scott reaction unit 7 includes a hydrogenation reactor 71, a quench tower 72 and an oxidative desulfurization tower 73 which are connected in sequence; the Claus tail gas generated by the Claus reaction unit 6 is introduced into the input end of the hydrogenation reactor 71 and is used for reacting the Claus tail gas with reducing gas, so that the sulfur-containing components in the Claus tail gas are converted into H₂S; the quenching tower 72 is used for cooling the process gas of the hydrogenation reactor 71; the oxidative desulfurization tower 73 is used for oxidative desulfurization treatment of the process gas of the quenching tower 72, so that H in the process gas of the quenching tower 72 is obtained₂S is converted into elemental sulfur; the outlet of the oxidation desulfurization tower 72 is connected with an incinerator 100The input ends are communicated. The bottom of the oxidation desulfurization tower 73 is provided with an absorbent outlet communicated with an absorbent inlet at the upper end of the side wall of the regeneration tower 74, the bottom of the regeneration tower 74 is provided with an absorbent outlet communicated with an absorbent inlet at the upper part of the side wall of the oxidation desulfurization tower 73, so that the absorbent regenerated in the regeneration tower 74 enters the oxidation desulfurization tower 73 again, and the top of the regeneration tower 74 is also provided with a regeneration gas outlet communicated with the Claus reaction unit 6, so that the gas generated in the regeneration tower 74 is conveyed into the Claus reaction unit 6. The rest of the structure is the same as the first embodiment.

SO in the desulfurized flue gas treated by the absorption tower 2 of the desulfurization unit 300₂The concentration is not higher than 50mg/m³SO treated by a desorption tower 3₂The concentration is more than 99%.

The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, as any modifications, equivalents, improvements and the like made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.

Claims

1. A Claus tail gas treatment system which is characterized in that: the system comprises an incinerator (100), a quenching unit (200) and a desulfurization unit (300) which are connected in sequence, wherein the input end of the incinerator (100) is introduced with Claus tail gas, the output end of the incinerator (100) is connected with the input end of the quenching unit (200), the quenching unit (200) is used for cooling incineration flue gas from the incinerator (100), and the output end of the quenching unit is connected with the desulfurization unit (300);

the desulfurization unit (300) comprises an electrolytic cell (1), an absorption tower (2) and a desorption tower (3), wherein the electrolytic cell (1) comprises an electrolytic tank and an ion exchange membrane (13) which divides the electrolytic tank into an anode area (12) and a cathode area (11), and the anode area (12) comprises an anode electrode (15) and contains HSO₃ ^-A salt solution and an organic solvent in which a compound QH is dissolved, and a cathode region (11) including a cathode electrode (14) containing HSO₃ ^-、SO₃ ^2-A salt solution and an organic solvent in which a compound Q is dissolved, the organic solvent being immiscible with the salt solution, a direct current being applied between the anode electrode (15) and the cathode electrode (14)A power source; the compound Q and the compound QH are compounds capable of generating PCET reaction, Q is in an oxidation state, and QH is in a reduction state;

the lower end of the absorption tower (2) is communicated with the output end of the quenching unit (200), the upper end of the absorption tower is provided with a desulfurized flue gas discharge port, the upper liquid inlet is communicated with the salt solution output end of the cathode area (11), and the lower liquid outlet is communicated with the salt solution input end of the cathode area (11), SO that low-concentration SO in the incineration flue gas is absorbed₂The salt solution is conveyed to the electrolytic cell (1);

the upper part of the desorption tower (3) is provided with high-concentration SO₂And the lower liquid inlet of the discharge port is communicated with the salt solution output end of the anode region (12), and the upper liquid outlet of the discharge port is communicated with the salt solution input end of the anode region (12).

2. The claus tail gas treatment system of claim 1, characterized in that: introducing a Q-rich organic solution generated by reacting QH dissolved in an organic solvent in an anode region (12) into Q through a first circulating pump (4) into a cathode region (11); and a QH-rich organic solution generated by converting the Q reaction dissolved in the organic solvent in the cathode region (11) into QH is introduced into the anode region (12) through a second circulating pump (5) so as to maintain the continuous and stable progress of the electrochemical reaction.

3. The claus tail gas treatment system according to claim 1 or 2, characterized in that: the device also comprises a Scott reaction unit (7), wherein the Scott reaction unit (7) comprises a hydrogenation reactor (71), a quench tower (72) and an oxidation desulfurization tower (73) which are connected in sequence; the Claus tail gas is introduced into the input end of the hydrogenation reactor (71) and is used for reacting the Claus tail gas with reducing gas, so that the sulfur-containing components in the Claus tail gas are converted into H₂S; the quenching tower (72) is used for cooling the process gas of the hydrogenation reactor (71); the oxidation desulfurization tower (73) is used for carrying out oxidation desulfurization treatment on the process gas of the quenching tower (72) so as to ensure that H in the process gas of the quenching tower (72)₂S is converted into elemental sulfur; the outlet of the oxidation desulfurization tower (73) is communicated with the input end of the incinerator (100).

4. The claus tail gas treatment system according to claim 1 or 2, characterized in that: the system is characterized by further comprising a super Claus reaction unit, wherein the super Claus reaction unit comprises a super Claus reactor (8) and a sulfur condenser (62), Claus tail gas is introduced into the input end of the super Claus reactor (8), the output end of the super Claus reactor is communicated with the inlet of the sulfur condenser (62), and the outlet of the sulfur condenser (62) is communicated with the input end of the incinerator (100).