A sulfur recovery device accident acid gas treatment system and treatment method

Abstract

The present invention provides an accident sour gas treatment system and a treatment method for a sulfur recovery unit. The system includes: a progressive caustic scrubbing unit, a tail gas incineration unit, and a post-desulfurization unit for flue gas. The progressive caustic scrubbing unit includes: a multi-stage caustic scrubbing tower, a caustic scrubbing circulation pipeline, a liquid storage tank, an external discharge pipeline, and a caustic solution delivery pipeline. The multi-stage caustic scrubbing tower is respectively connected to the caustic scrubbing circulation pipeline, the caustic solution delivery pipeline, and the external discharge pipeline, and performs progressive multi-stage cyclic caustic scrubbing on the sour gas to remove H2S and generate by-products, which are discharged into the liquid storage tank through the external discharge pipeline. At the same time, the tail gas with a qualified H2S removal rate is sent to the tail gas incineration unit for treatment, and then the flue gas is sent to the post-desulfurization unit for SO2 removal treatment to discharge qualified flue gas.

Description

Technical Field

[0001] The invention relates to acid gas treatment technology, and in particular to a sulfur recovery device accident acid gas treatment system and treatment method. Background Art

[0002] As the terminal environmental protection device of the whole plant, the sulfur recovery unit treats the sulfur-containing wastewater and waste gas generated in the processing of sulfur-containing crude oil or raw coal. While meeting the sulfur balance, it also needs to ensure that the pollutant SO 2 When the sulfur recovery unit is a single series, it must be started and stopped at the same time as the main unit when the interlock fails. When the interlock stops, the H-containing gas released by the system buffer 2 S acid gas still needs to be handled safely to prevent H 2 S leakage, and H 2 The sulfur emission concentration is reduced to 10 mg / m 3 The following ensures intrinsic safety.

[0003] Acid gas flares are emergency treatment facilities for acid gas in the event of an accident at a sulfur recovery unit. Their installation needs to meet the safety distance requirements of the GB50160 fire protection code. However, in practice, some plant areas are often tight on land during construction, and some plants are unable to deploy acid gas flares due to limited general layout. However, GB50160-2018 "Petrochemical Enterprise Design Fire Protection Standard" stipulates in 4.1.10 that "the fire protection distance between an elevated flare that may carry flammable liquids and a Class A and B process unit or facility is 90m", which means that Class A and B units and flammable liquid tanks are not allowed within at least 90m of the elevated flare.

[0004] In addition, even the acid gas flare of the existing technology, as an emergency treatment facility, is not very effective in dealing with the high concentration of H2 2 In the treatment of S acid gas, there are also defects such as incomplete combustion and acid rain in practice.

[0005] Therefore, how to design a solution that can replace the acid gas flare, perform emergency treatment on the acid gas in the event of an accident in the sulfur recovery unit, and ensure that pollutants are discharged safely and meet standards while relatively saving space is a difficult problem facing technical personnel in this field. Summary of the invention

[0006] Therefore, the main purpose of the present invention is to provide a system and method for treating accident acid gas in a sulfur recovery unit to solve the problems mentioned in the background technology.

[0007] In order to achieve the above-mentioned object, according to one aspect of the present invention, a sulfur recovery unit accident acid gas treatment system is provided, which comprises: a progressive alkali washing unit, the progressive alkali washing unit comprises: a multi-stage alkali washing tower, an alkali washing circulation pipeline, a liquid storage tank, an external discharge pipeline, and an alkali liquid delivery pipeline, the multi-stage alkali washing tower is respectively connected to the alkali washing circulation pipeline, the alkali liquid delivery pipeline, and the external discharge pipeline, and the acid gas is subjected to progressive multi-stage circulation alkali washing to remove H 2 S and produces by-products, which are discharged into the liquid storage tank through the external discharge pipeline.

[0008] In a possible preferred embodiment, a cooler is provided at the top of each alkali washing tower to cool the tail gas to below 50°C and pass it to the next alkali washing tower; the alkali liquid delivery pipeline dynamically adjusts the amount and concentration of NaOH alkali liquid entering each alkali washing tower to react with the acid gas to generate NaHS and H 2 O.

[0009] In a possible preferred embodiment, the accident acid gas treatment system of the sulfur recovery unit further includes: a desalted water supply pipeline, the multi-stage alkali washing towers are respectively connected to the desalted water supply pipeline, so that the concentration of NaOH alkali solution in each alkali washing tower is dynamically diluted by the desalted water, and the alkali solution level in the alkali washing tower and the external discharge pipeline form a cascade regulation loop to maintain a preset liquid level height in the alkali washing tower, so that the acid gas reacts in the alkali washing tower to generate NaHS and H 2 O; A cooler is installed at the top of each level of alkali washing tower to cool the tail gas to below 50°C and pass it into the next level of alkali washing tower.

[0010] In a possible preferred embodiment, an alkali liquid spraying facility is provided in the gas phase space in each level of the alkali washing tower to allow the alkali liquid to fully cover the gas phase; the acid gas outlet end in each level of the alkali washing tower is placed below the alkali liquid level, and a plurality of air holes are arranged on the acid gas outlet end to promote gas-liquid contact to form bubbling absorption.

[0011] In order to achieve the above-mentioned object, according to another aspect of the present invention, a sulfur recovery device accident acid gas treatment system is also provided, which comprises: a progressive alkali washing unit, a tail gas incineration unit, and a flue gas post-desulfurization unit, wherein the progressive alkali washing unit comprises: a multi-stage alkali washing tower, an alkali washing circulation pipeline, a liquid storage tank, an external discharge pipeline, and an alkali liquid delivery pipeline, and the multi-stage alkali washing tower is respectively connected to the alkali washing circulation pipeline, the alkali liquid delivery pipeline, and the external discharge pipeline, and the acid gas is subjected to progressive multi-stage circulation alkali washing to remove H 2 S and produce by-products, which are discharged into the storage tank through the external pipeline, and H 2 The tail gas with the S removal rate reaching the standard is sent to the tail gas incineration unit for treatment, and then the flue gas is sent to the flue gas post-desulfurization unit for SO 2 Removal treatment to discharge qualified flue gas.

[0012] In a possible preferred embodiment, a cooler is provided at the top of each alkali washing tower to cool the tail gas to below 50°C and pass it to the next alkali washing tower; the alkali liquid delivery pipeline dynamically adjusts the amount and concentration of NaOH alkali liquid entering each alkali washing tower to react with the acid gas to generate NaHS and H 2 O.

[0013] In a possible preferred embodiment, the accident acid gas treatment system of the sulfur recovery unit further includes: a desalted water supply pipeline, the multi-stage alkali washing towers are respectively connected to the desalted water supply pipeline, so that the concentration of NaOH alkali solution in each alkali washing tower is dynamically diluted by the desalted water, and the alkali solution level in the alkali washing tower and the external discharge pipeline form a cascade regulation loop to maintain a preset liquid level height in the alkali washing tower, so that the acid gas reacts in the alkali washing tower to generate NaHS and H 2 O; A cooler is installed at the top of each level of alkali washing tower to cool the tail gas to below 50°C and pass it into the next level of alkali washing tower.

[0014] In a possible preferred embodiment, an alkali liquid spraying facility is provided in the gas phase space in each level of the alkali washing tower to allow the alkali liquid to fully cover the gas phase; the acid gas outlet end in each level of the alkali washing tower is placed below the alkali liquid level, and a plurality of air holes are arranged on the acid gas outlet end to promote gas-liquid contact to form bubbling absorption.

[0015] In a possible preferred embodiment, the tail gas incineration unit includes: an ejector, an incinerator, a blower, a fuel pipeline, and a waste heat boiler, wherein the ejector is respectively connected to the final alkali scrubber and the blower, and the blower provides combustion-supporting air as a power gas to the ejector to suck the tail gas output from the final alkali scrubber for mixing, and the tail gas is premixed with the fuel output from the fuel pipeline before entering the incinerator, and then sprayed into the incinerator for low-nitrogen combustion, and the high-temperature flue gas produced is cooled by the by-product steam of the waste heat boiler and then sent to the flue gas post-desulfurization unit.

[0016] In a possible preferred embodiment, the flue gas post-desulfurization unit includes: a multi-stage filler desulfurization subunit, which includes: a multi-stage desulfurization tower, in which a multi-stage desulfurization section, a water washing section and a demisting section are sequentially arranged, wherein the flue gas treated by the tail gas incineration unit enters from the bottom of the multi-stage desulfurization tower, and the desulfurization liquid is used to absorb the SO in the flue gas through the multi-stage desulfurization section. 2 After desulfurization and purification, the flue gas enters the water washing section and the demisting section in turn for dust and droplet treatment until the flue gas meets the standards and is discharged. This desulfurization process can be applied to layout sites with no height restrictions and has relatively low energy consumption.

[0017] In a possible preferred embodiment, the flue gas post-desulfurization unit includes: a supergravity desulfurization subunit, which includes: a desulfurization reactor, a desulfurization liquid buffer tank, a circulating cooler, and a circulating alkali liquid pipeline. The desulfurization reactor is connected to an alkali liquid delivery pipeline and a desalted water supply pipeline, and receives the flue gas discharged from the tail gas incineration unit, wherein the flue gas forms a supergravity field under the centrifugal force generated by the desulfurization reactor, and the alkali liquid is diluted with desalted water and shredded in the desulfurization reactor by the centrifugal force to contact and react with the flue gas to absorb SO in the flue gas. 2 After desulfurization and purification, the alkali liquid is collected in the desulfurization liquid buffer tank through the circulating alkali liquid pipeline, and then cooled in the circulating cooler after being transmitted through the circulating alkali liquid pipeline, and then enters the desulfurization reactor again for circulating alkali washing until the flue gas meets the standards and is discharged. This desulfurization process is suitable for layout sites with limited height and direction, and the energy consumption is relatively high, but the desulfurization efficiency is 0.5% higher than the aforementioned multi-stage filler desulfurization sub-unit example scheme.

[0018] In order to achieve the above object, corresponding to the above system, according to another aspect of the present invention, a method for treating accident acid gas in a sulfur recovery unit is provided, the steps of which include:

[0019] Step S100: The acid gas is fed into a multi-stage alkali washing tower for cyclic alkali washing to produce H 2 The tail gas with S removal rate reaching the standard and NaHS solution as by-product; the tail gas of each alkali washing tower is cooled to below 50°C by a cooler and then transferred to the next alkali washing tower; in the gas phase space of each alkali washing tower, alkali liquid is sprayed to fully cover the gas phase; the acid gas is released below the alkali liquid level to promote gas-liquid contact and form bubbling absorption; the preset liquid level height in the alkali washing tower is maintained, and the alkali concentration in each alkali washing tower is dynamically diluted by desalted water;

[0020] Step S200: H 2 The tail gas with S removal rate reaching the standard is mixed with combustion air and fuel, and input into the incinerator for low-nitrogen combustion. The high-temperature flue gas is cooled down to low-temperature flue gas by the by-product steam of the waste heat boiler;

[0021] Step S300: low temperature flue gas is fed into the flue gas post-desulfurization unit for SO 2 Removal treatment to discharge qualified flue gas.

[0022] In a possible preferred embodiment, the flue gas post-desulfurization unit performs SO 2 The removal process includes:

[0023] The low-temperature flue gas and the alkali solution diluted with desalted water are input into the desulfurization reactor to react under the action of centrifugal force to absorb the SO in the flue gas. 2 Carry out desulfurization and purification;

[0024] The alkali solution is transmitted through the circulating alkali solution pipeline and cooled in the circulating cooler, and then enters the desulfurization reactor again for circulating alkali washing until the flue gas meets the standards and is discharged.

[0025] In a possible preferred embodiment, the flue gas post-desulfurization unit performs SO 2 The removal process includes:

[0026] The low-temperature flue gas is input from the bottom of the multi-stage desulfurization tower, and the desulfurization liquid is used to absorb the SO in the flue gas through the multi-stage desulfurization section. 2 After desulfurization and purification, the flue gas enters the water washing section and the demisting section in turn for dust and droplet treatment until it is discharged after meeting the standards.

[0027] Through the sulfur recovery device accident acid gas treatment system and treatment method provided by the present invention, a progressive alkali washing unit is cleverly designed, which can not only cope with high concentration H 2 S and unstable acid gas to achieve H 2 It can efficiently remove S and reduce the floor space of the traditional acid gas flare from 90X90m to 10X6m, thus solving the problem of insufficient floor space for setting up the acid gas flare in the prior art.

[0028] In addition, in the corresponding embodiment, the progressive alkali washing unit can remove 99.5% of H 2 S is removed efficiently. Compared with the conventional desulfurization process, the removal efficiency has achieved a qualitative leap, which is 2 The intrinsically safe discharge of S provides reliable guarantee, and can also produce ~40wt% NaHS solution, achieving the high-risk and highly toxic H 2 During the S treatment, no difficult-to-treat waste liquid or hazardous waste is generated.

[0029] In addition, in the corresponding embodiment, in order to further remove the outlet as low as H 2 The tail gas contains 0.5 mol% S and trace hydrocarbons and a small amount of ammonia. This scheme also provides a low-nitrogen tail gas incineration unit to decompose the pollutants at high temperature to achieve H 2 The incineration rate of S is above 99.99%.

[0030] In addition, in the corresponding embodiment, in order to further remove SO from the flue gas 2 This solution also provides a flue gas post-desulfurization unit to receive the flue gas treated by the tail gas incineration unit and remove the residual SO 2 Remove to below the limit concentration of environmental protection standards, and maximize the safe discharge of pollutants in abnormal conditions such as accidental shutdown of the sulfur recovery unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0032] Figure 1 It is a structural schematic diagram of a progressive alkali washing unit in the accident acid gas treatment system of the sulfone recovery device of the present invention;

[0033] Figure 2 It is a structural schematic diagram of the tail gas incineration unit in the accident acid gas treatment system of the sulfide recovery device of the present invention;

[0034] Figure 3 It is a structural schematic diagram of a multi-stage filler desulfurization subunit in the accident acid gas treatment system of the sulfide recovery device of the present invention;

[0035] Figure 4 It is a structural schematic diagram of the super gravity desulfurization subunit in the accident acid gas treatment system of the sulfide recovery device of the present invention.

[0036] Description of Reference Numerals

[0037] Alkali washing tower 1, alkali washing circulation pipeline 2, liquid storage tank 3, external discharge pipeline 4, alkali solution delivery pipeline 5, desalted water supply pipeline 6, multi-stage desulfurization tower 8, cooler 11, alkali solution spraying facility 12, acid gas outlet 13, fresh alkali solution pump 14, by-product liquid pump 15, ejector 71, incinerator 72, blower 73, fuel pipeline 74, waste heat boiler 75, primary desulfurization section 81, secondary desulfurization section 82, water washing section 83, demisting section 84, desulfurization reactor 91, desulfurization liquid buffer tank 92, circulating cooler 93, circulating alkali solution pipeline 94, circulating alkali solution pump 95. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solution of the present invention, the specific technical solution of the present invention will be clearly and completely described in conjunction with the embodiments below to help those skilled in the art further understand the present invention. Obviously, the embodiments described in this case are only embodiments of a part of the present invention, not all of the embodiments. It should be pointed out that for those of ordinary skill in the art, the embodiments in this application and the features in the embodiments can be combined with each other without departing from the concept of the present invention and without conflicting with each other. Based on the embodiments in the present invention, all other embodiments obtained without creative work by those of ordinary skill in the art should belong to the disclosure and protection scope of the present invention.

[0039] In addition, the terms "first", "second", "S100", "S200", etc. in the specification, claims and drawings of the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the features used in this way can be interchanged where appropriate, so that the embodiments of the present invention described here can be implemented in an order other than those described here. At the same time, the stages recorded in each step are not mandatory to be implemented in the same step. It should be understood that the implementation order of the contents in each step stage can be adjusted and interchanged without violating the inventive concept, so that the step embodiments of the present invention described here can be implemented in an order other than those described here. In addition, the terms "including" and "having" and any of their variations in the present invention are intended to cover non-exclusive inclusions. Unless otherwise clearly specified and limited, the terms "set", "layout", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in this case can be understood according to specific circumstances and in combination with the prior art.

[0040] At present, the existing sulfur recovery units generally adopt single series or double series. Single series means single set of sulfur. Single set of sulfur generally has 20~30 SIS interlocking points. For example, if the fan fails, the furnace temperature of the combustion furnace is high, the liquid level of the waste heat boiler is low, etc., when any interlocking point is triggered, the entire sulfur recovery unit needs to be stopped immediately. At this time, the upstream unit also needs to be stopped synchronously, which makes it impossible to process the H2 in the whole plant. 2 S is acidic gas, while H 2 S is a highly toxic and flammable Class A high-risk medium, and the environmental protection standard allows the emission concentration to be 10mg / m 3 the following.

[0041] The hydrogenation and coking units in the plant contain H 2 After the wastewater and waste gas are treated and absorbed by the acidic water stripping and solvent regeneration device, the H 2 The S concentration is at least above 50 mol%. 2 S needs to be properly and thoroughly handled in real time to ensure H 2 S emissions are inherently safe. Therefore, the industry's common practice is to hand over these acid gases to the acid gas flare for treatment. It can be seen that the acid gas flare is the last guarantee of intrinsic safety and its function is indispensable.

[0042] Therefore, if there is no acid gas flare in the plant area, when the sulfur recovery unit fails, the acid gas produced by the acid water stripping and solvent regeneration unit will be cut off by the interlock valve and will no longer go to the sulfur recovery unit. The switch valve on the acid gas bypass pipeline is in the open state, and it is transported to the emergency treatment facility through the bypass pipeline. Under this condition, the acid gas will have the typical characteristics of high concentration and unstable flow. The concentration of the mixed acid gas from the acid water stripping + solvent regeneration can be as high as 90 mol%, and it needs to be continuously discharged for 2 to 5 hours, and the flow tends to gradually decrease. Therefore, even if it is an acid gas flare, in the face of emergency discharge of high-concentration H 2 In the treatment of S acid gas, there are also defects such as incomplete combustion and acid rain in practice.

[0043] Therefore, even in the existing technology, there are few real cases for emergency treatment of high-concentration H2S gas. Therefore, in order to replace the role of the acid gas flare and reduce the floor space at the same time, it is necessary to make innovative improvements in the design of the process route and the actual operation adjustment to achieve safe and standard treatment of sulfides.

[0044] For this reason, Figure 1 As shown, the present invention provides a sulfur recovery device accident acid gas treatment system, which includes: a progressive alkali washing unit, the progressive alkali washing unit includes: a multi-stage alkali washing tower 1, an alkali washing circulation pipeline 2, a liquid storage tank 3, an external discharge pipeline 4, and an alkali liquid delivery pipeline 5. The multi-stage alkali washing tower 1 is respectively connected to the alkali washing circulation pipeline 2, the alkali liquid delivery pipeline 5, and the external discharge pipeline 4, and performs progressive multi-stage circulation alkali washing on the acid gas to remove H 2 S and produces by-products, which are discharged into the liquid storage tank 3 through the external discharge pipeline 4.

[0045] Specifically, the design of the progressive alkali washing unit needs to take into account the treatment of sulfur recovery accident acid gas and sulfur recovery combined unit safety valve release gas, and the H 2 The S concentration is treated to below 5000ppm, and in this example, the target corresponds to the H 2 The concentration of S is as high as 90 mol%. Therefore, according to the total release of acid gas, a 4-stage alkali washing tower 1 is set up in this example to form a progressive multi-stage circulating alkali washing system together with the alkali washing circulation pipeline 2, the alkali liquid delivery pipeline 5, and the external discharge pipeline 4, with the intention of gradually digesting large quantities of high-concentration acid gas through multiple cycles of alkali washing.

[0046] However, there are also some difficulties in this process, that is, in the process of alkaline washing to remove ultra-high concentration H 2 In the process of S, how to improve the absorption efficiency of NaOH alkali solution and prevent byproducts from clogging the pipeline is the key to ensure ultra-high concentration H 2 The key to S removal efficiency.

[0047] For this example, the first point is:

[0048] By quantitatively supplying low-concentration NaOH solution and other control loops, NaHS with high solubility is generated without generating low-solubility Na 2 S.

[0049] That is, hydrogen sulfide reacts with sodium hydroxide:

[0050] A small amount of sodium hydroxide: NaOH+H 2 S=NaHS+H 2 O

[0051] Excess sodium hydroxide: 2NaOH+H 2 S=Na 2 S+2H 2 O

[0052] This reaction is a dynamic equilibrium, on the one hand, NaOH is continuously consumed, and on the other hand, H 2 O, so NaOH is constantly diluted. The absorption liquid is refined to remove by-products such as sodium carbonate and sodium bicarbonate, and then concentrated to finally obtain a 30wt% to 40wt% NaHS liquid product.

[0053] In an optional example, the alkali solution delivery pipeline 5 can dynamically adjust the amount and concentration of NaOH alkali solution entering each level of the alkali washing tower 1 to react with the acid gas to generate NaHS and H 2 O.

[0054] In another optional example, in the accident acid gas treatment system of the sulfone recovery device, a desalted water supply pipeline 6 may be further provided, and the multi-stage alkali washing towers 1 are respectively connected to the desalted water supply pipeline 6, so that the concentration of NaOH alkali solution in each stage of the alkali washing tower 1 is dynamically diluted by the desalted water, and the alkali solution level in the alkali washing tower 1 and the external discharge pipeline 4 form a cascade regulation loop to maintain a preset liquid level height in the alkali washing tower 1, so that the acid gas reacts in the alkali washing tower 1 to generate NaHS and H 2 O.

[0055] Secondly, since acid-base neutralization releases heat, there is a strong exothermic reaction in the alkali washing tower 1. Therefore, in order to ensure a high desulfurization efficiency, the heat needs to be removed in time.

[0056] For this reason Figure 1 As shown, a cooler 11 is provided on the top of each alkali washing tower 1. The tail gas of each alkali washing tower 1, after exiting from the top of the alkali washing tower 1, directly enters the cooler 11 (such as a water cooler) to cool the gas to 50°C or below (such as 40-50°C), and then enters the next alkali washing tower 1. In this way, the lower the temperature of the acid-base neutralization reaction, the more favorable it is, and the lower the reaction temperature, the higher the desulfurization efficiency.

[0057] Based on the above configuration, high-concentration acid gas is used for progressive alkali washing, and the concentration and amount of alkali solution in the alkali washing tower 1 are dynamically adjusted (with H 2 The molar ratio of S in the reaction is close to 1:1) to generate NaHS solution as much as possible instead of Na2S solution, which can avoid crystallization blockage in the alkali washing tower 1.

[0058] Third, in order to enhance the absorption efficiency of NaOH alkali solution in the alkali washing tower 1, in an optional example, an alkali solution spraying facility 12 may be provided in the gas phase space in each level of the alkali washing tower 1 to increase the absorption efficiency of the alkali solution and H 2 S gas phase contact area, so that the alkali solution can fully cover the gas phase and improve the reaction efficiency.

[0059] At the same time, the acid gas outlet 13 in each level of the alkali washing tower 1 is placed below the alkali liquid level, and a plurality of air holes are arranged on the acid gas outlet 13 to promote full contact between the gas and liquid phases and enhance the bubbling absorption of H 2 The effect of S is to improve the reaction efficiency within a limited residence time.

[0060] In this process, the acid gas is progressively alkali washed, and the desalting water supply pipeline 6 can dilute the alkali concentration while ensuring a certain liquid level. The liquid level and the external discharge pipeline 4 of the external NaHS solution form a cascade regulation loop to ensure normal operation through timely discharge. This setting can improve H 2 S removal rate, and no crystallization blockage will occur, thus ensuring that ultra-high concentration H 2 S's requirements.

[0061] For example, if Figure 1 As shown, the alkali washing towers I to IV are operated in sequence, wherein the alkali washing towers I to IV are the first cycle, when the NaHS concentration is enriched and the value is close to 40wt% through analysis and testing, the external discharge pump starts automatically; then it passes through the bypass valve to the second cycle, i.e. IV→III→II→I, and circulates in sequence, any one of the alkali washing towers I to IV 1 can be used as the first alkali washing tower 1 of the series alkali washing, wherein the fresh alkali liquid pump 14 of the alkali liquid delivery pipeline 5 and the byproduct liquid pump 15 of sodium hydrosulfide are set to start automatically, and fresh alkali liquid can be added to the alkali washing tower 1 in time, and part of the sodium hydrosulfide byproduct is discharged synchronously; the outlet of the alkali washing tower 1 is designed with a circulating pump, part of the desulfurization liquid is circulated, part is discharged, and new alkali liquid is added in time, and the fresh alkali liquid pump 14 and the circulating pump are set to start automatically under accident conditions to ensure the alkali concentration in the alkali washing tower 1, enhance the absorption effect, and ensure safety.

[0062] This sequential control cycle operation can handle ultra-high concentration H 2 S acid gas, and can run continuously until the accident condition ends without crystallization and blockage, while ensuring the concentration of alkali liquid in the tower, and finally making H 2The S removal efficiency is above 99.5%. In other optional examples, the number of the multi-stage alkali washing tower 1 can be increased or decreased according to the specific situation to meet the required H 2 S removal efficiency.

[0063] Compared with the traditional acid gas flare, this solution can not only handle high concentration H 2 S and unstable acid gas to achieve H 2 It can efficiently remove S and reduce the floor space of the traditional acid gas flare from 90X90m to 10X6m, thus solving the problem of insufficient floor space for setting up the acid gas flare in the prior art.

[0064] In addition, the progressive alkali washing unit can remove 99.5% of H 2 S is removed efficiently. Compared with the conventional desulfurization process, the removal efficiency has achieved a qualitative leap, which is 2 The intrinsically safe discharge of S provides reliable guarantee, and can also produce ~40wt% NaHS solution, achieving the high-risk and highly toxic H 2 During the S treatment, no difficult-to-treat waste liquid or hazardous waste is generated.

[0065] Furthermore, for the sake of exhaust environmental protection, 99.5% of H2S is removed from the acid gas, except for ppm level H 2 In addition to S, there may also be trace hydrocarbons and a small amount of ammonia. Therefore, in order to completely and thoroughly decompose all pollutants at high temperature, H 2 The incineration rate of S is above 99.99%.

[0066] like Figure 2 As shown, in an optional example, the sulfur recovery unit accident acid gas treatment system of the present invention further includes: a tail gas incineration unit for treating the H output by the progressive alkali washing unit 2 The tail gas with S removal rate reaching the standard, wherein the tail gas incineration unit comprises: an injector 71, an incinerator 72, a blower 73, and a fuel pipeline 74, wherein the injector 71 is connected to the final alkali washing tower 1 and the blower 73 respectively, and the blower 73 provides combustion-supporting air as a power gas to the injector 71, so as to suck the tail gas outputted from the final alkali washing tower 1 for mixing, and when entering the incinerator 72, the tail gas is premixed with the fuel outputted from the fuel pipeline 74, and then injected into the incinerator 72 for low-nitrogen combustion.

[0067] Specifically, tail gas incineration is the complete combustion of combustibles. As long as there is sufficient reaction temperature, residence time, and high-intensity mixing, that is, the 3T principle, pollutants can be completely decomposed into CO 2 , H 2 O, SO 2The difficulty of tail gas incineration lies in how to achieve ultra-low NOx emissions and contribute to the reduction of the overall NOx environmental emission indicators of the factory.

[0068] Traditional low-nitrogen combustion technology, such as the Claus tail gas diversion form of sulfur tail gas burner, introduces the first-stage tail gas into the fuel combustion zone of the burner to reduce the oxygen partial pressure of the combustion air and reduce the temperature of the flame zone. It can effectively control the generation of thermodynamic NOx in the fuel combustion of the burner. That is, this type of solution is to adjust the temperature of the burner flame zone by adjusting the amount of primary tail gas entering the burner, and control the amount of thermodynamic NOx generated.

[0069] However, the adverse effect of this type of low-nitrogen technology is that it causes the pressure drop of sulfur-producing tail gas to increase by 3~5KPaG (burner throat and pipeline valve pressure drop), which increases the power consumption of the device and is not conducive to load increase.

[0070] For this reason, in this example, for thermal NOx, the kinetic energy of the diverted exhaust gas is provided by the blower 73 of the exhaust furnace with a pressure head of 30KPaG, that is, an air injector 71 is added to use combustion air to guide a small stream of exhaust gas into the fire channel of the incinerator 72 to cool it down and dilute the oxygen concentration.

[0071] For example, the power gas of the injector 71 is the combustion air at the outlet of the blower 73, and the suction medium is the tail gas output by the progressive alkali washing unit. The mixer outlet of the injector 71 is a mixed gas of two streams. A regulating valve and a flow meter can be set on the branch tail gas pipeline to form a ratio control regulation loop between the branch tail gas (diverted into the incinerator 72) and the primary air volume. The ratio of diverted tail gas: primary combustion air is set to 1:5. Then the mixed gas enters the throat of the incinerator 72 to be premixed with the fuel, and then sprayed into the high-temperature area of ​​the fire channel. At this time, the oxygen concentration has been diluted, thereby achieving the purpose of nitrogen reduction and stably controlling NOx at 50mg / Nm 3 Ultra-low emission levels below.

[0072] Furthermore, in order to remove SO from the flue gas produced by the tail gas incineration unit 2 To make the emission meet the standard, in an optional example, the sulfur recovery device accident acid gas treatment system of the present invention also includes: a flue gas post-desulfurization unit, wherein the tail gas incineration unit also includes: a waste heat boiler 75, wherein the flue gas generated after the low-nitrogen combustion in the incinerator 72 is cooled by the by-product steam of the waste heat boiler 75, and then sent to the flue gas post-desulfurization unit for SO 2 Removal treatment.

[0073] Specifically, in this example, Figure 3The flue gas post-desulfurization unit includes: a multi-stage packing desulfurization subunit, which includes: a multi-stage desulfurization tower 8, in which a multi-stage desulfurization section, a water washing section 83 and a demisting section 84 are sequentially arranged, wherein the multi-stage desulfurization section is divided into a primary desulfurization section 81 and a secondary desulfurization section 82, wherein the primary desulfurization section 81, the secondary desulfurization section 82, and the water washing section 83 are all equipped with an absorption liquid distributor and a packing layer. In view of the fact that the relevant distributor and packing layer can adopt the existing technology, they are not described here. The flue gas treated by the tail gas incineration unit enters from the lower part of the multi-stage desulfurization tower 8, and the desulfurization liquid is used to absorb the SO in the flue gas through the multi-stage desulfurization section. 2 After desulfurization and purification, the flue gas enters the water washing section 83 and the demisting section 84 in sequence for dust and droplet treatment until the flue gas meets the standards and is discharged.

[0074] On the other hand, in the alternative example, Figure 4 As shown, the flue gas post-desulfurization unit includes: a supergravity desulfurization subunit, which includes: a desulfurization reactor 91, a desulfurization liquid buffer tank 92, a circulating cooler 93, and a circulating alkali liquid pipeline 94. The desulfurization reactor 91 is connected to the alkali liquid delivery pipeline 5 and the desalted water supply pipeline 6, and receives the flue gas discharged from the tail gas incineration unit, wherein the flue gas forms a supergravity field under the centrifugal force generated by the desulfurization reactor 91, and the alkali liquid is diluted with desalted water and torn into nanometer to micrometer-sized droplets, liquid filaments and liquid films in the desulfurization reactor 91 by the centrifugal force, thereby providing a huge and rapidly updated flue gas-alkali liquid contact area, so that SO in the flue gas is 2 The alkali liquid is absorbed and reacted quickly and efficiently to desulfurize and purify the flue gas. After the alkali liquid is collected in the desulfurization liquid buffer tank 92 through the circulating alkali liquid pipeline 94, it is then transmitted through the circulating alkali liquid pipeline 94 and the circulating alkali liquid pump 95 to the circulating cooler 93 for cooling, and then enters the desulfurization reactor 91 again for circulating alkali washing until the flue gas meets the standards and is discharged.

[0075] The residual SO in the flue gas output by the tail gas incineration unit is then 2 , remove to below the limit concentration of environmental protection standards, maximize the accidental shutdown of sulfur recovery units, etc., and ensure that pollutants are safely discharged in compliance with standards under abnormal operating conditions.

[0076] On the other hand, corresponding to the above example, the present invention also provides a method for treating accident acid gas in a sulfur recovery unit, the steps of which include:

[0077] Step S100: The acid gas is fed into a multi-stage alkali washing tower 1 for cyclic alkali washing to produce H 2The tail gas with S removal rate reaching the standard is produced, and NaHS solution is produced as a by-product; wherein the tail gas of each alkali washing tower 1 is cooled to below 50°C by a cooler 11, and then is transmitted to the next alkali washing tower 1; in the gas phase space of each alkali washing tower 1, alkali liquid is sprayed to fully cover the gas phase; the acid gas is released below the alkali liquid level to promote gas-liquid contact and form bubbling absorption; the preset liquid level height in the alkali washing tower 1 is maintained, and the alkali liquid concentration in each alkali washing tower 1 is dynamically diluted by desalted water;

[0078] Step S200: H 2 The tail gas with the sulfur removal rate reaching the standard is mixed with combustion-supporting air and fuel, and input into the incinerator 72 for low-nitrogen combustion. The high-temperature flue gas is cooled to low-temperature flue gas by the by-product steam of the waste heat boiler 75;

[0079] Step S300: low temperature flue gas is fed into the flue gas post-desulfurization unit for SO 2 Removal treatment to discharge qualified flue gas.

[0080] In an optional embodiment, the flue gas post-desulfurization unit performs SO 2 The removal process includes:

[0081] The low-temperature flue gas and the alkali solution diluted with desalted water are input into the desulfurization reactor 91 to contact and react under the action of centrifugal force to generate a desulfurization liquid;

[0082] The desulfurization liquid is transferred through the circulating alkali liquid pipeline 94 and passed through the circulating cooler 93 for cooling, and then enters the desulfurization reactor 91 again for circulating alkali washing until the flue gas meets the standards and is discharged.

[0083] In another optional embodiment, the flue gas post-desulfurization unit performs SO 2 The removal process includes:

[0084] The low-temperature flue gas is input from the bottom of the multi-stage desulfurization tower 8, and the desulfurization liquid is used to absorb the SO in the flue gas through the multi-stage desulfurization section. 2 After desulfurization and purification, the flue gas enters the water washing section 83 and the demisting section 84 in sequence for dust and droplet treatment until the flue gas meets the standards and is discharged.

[0085] In summary, the sulfur recovery unit accident acid gas treatment system and treatment method provided by the present invention cleverly designs a progressive alkali washing unit, which can not only cope with high-concentration H 2 S and unstable acid gas to achieve H 2 It can efficiently remove S and reduce the floor space of the traditional acid gas flare from 90X90m to 10X6m, thus solving the problem of insufficient floor space for setting up the acid gas flare in the prior art.

[0086] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is only limited by the claims and their full scope and equivalents. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0087] Those skilled in the art can understand that, in addition to implementing the system, device, unit and its various modules provided by the present invention in a purely computer-readable program code, it is entirely possible to implement the same program in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers and embedded microcontrollers by logically programming the method steps. Therefore, the system, device and its various modules provided by the present invention can be considered as a hardware component, and the modules included therein for implementing various programs can also be regarded as structures within the hardware component; the modules for implementing various functions can also be regarded as both software programs for implementing the method and structures within the hardware component.

[0088] In addition, all or part of the steps in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including a number of instructions to enable a single-chip microcomputer, a chip or a processor to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, RandomAccess Memory), disk or optical disk and other media that can store program codes.

[0089] In addition, various implementation modes of the embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed by the embodiments of the present invention.

Claims

1. A sulfur recovery unit accident acid gas treatment system, comprising: A progressive alkali washing unit, a tail gas incineration unit, and a flue gas post-desulfurization unit, wherein the progressive alkali washing unit comprises: a multi-stage alkali washing tower, an alkali washing circulation pipeline, a liquid storage tank, an external discharge pipeline, and an alkali liquid delivery pipeline. The multi-stage alkali washing tower is respectively connected to the alkali washing circulation pipeline, the alkali liquid delivery pipeline, and the external discharge pipeline, and the acid gas is subjected to a progressive multi-stage circulation alkali washing to remove H2S and produce by-products, which are then collected into the liquid storage tank through the external discharge pipeline. At the same time, the tail gas with a H2S removal rate that meets the standard is sent to the tail gas incineration unit for treatment. The flue gas is sent to the flue gas post-desulfurization unit for SO2 removal treatment to discharge qualified flue gas; a cooler is provided at the top of each alkali washing tower to cool the tail gas to below 50°C and pass it into the next alkali washing tower; the acid gas is controlled to react in the alkali washing tower to generate NaHS and H2O by any of the following methods: a desalted water supply pipeline is set to connect to the multi-stage alkali washing tower respectively, so as to dynamically dilute the NaOH alkali solution concentration in each alkali washing tower with the desalted water, and the alkali solution level in the alkali washing tower and the external discharge pipeline constitute a cascade regulation loop, maintain the preset liquid level height in the alkali washing tower / or dynamically adjust the amount and concentration of NaOH alkali liquid entering each level of the alkali washing tower by the alkali liquid delivery pipeline; wherein the gas phase space in each level of the alkali washing tower is provided with an alkali liquid spraying facility so that the alkali liquid fully covers the gas phase; the acid gas outlet end in each level of the alkali washing tower is placed below the alkali liquid level, and a plurality of air holes are arranged on the acid gas outlet end to promote gas-liquid contact to form bubbling absorption; wherein the tail gas incineration unit includes: an ejector, an incinerator, a blower, a fuel The ejector is connected to the final alkali scrubber and the blower respectively. The blower provides the ejector with combustion-supporting air as the power gas, and the tail gas output from the final alkali scrubber is sucked and mixed. When entering the incinerator, the tail gas is premixed with the fuel output from the fuel pipeline and then sprayed into the incinerator for low-nitrogen combustion. The high-temperature flue gas produced is cooled by the by-product steam of the waste heat boiler and then sent to the flue gas post-desulfurization unit; the flue gas post-desulfurization unit includes: any one of a multi-stage filler desulfurization subunit or a super gravity desulfurization subunit.

2. The sulfur recovery unit accident acid gas treatment system according to claim 1, wherein the multi-stage filler desulfurization subunit comprises: A multi-stage desulfurization tower is provided with a multi-stage desulfurization section, a water washing section and a demisting section in sequence. The flue gas treated by the tail gas incineration unit enters from the lower part of the multi-stage desulfurization tower, and after the multi-stage desulfurization section uses desulfurization liquid to absorb SO2 in the flue gas for desulfurization and purification, it enters the water washing section and the demisting section in sequence for dust and droplet treatment until the flue gas meets the standards and is discharged.

3. The sulfur recovery unit accident acid gas treatment system according to claim 1, wherein the super gravity desulfurization subunit comprises: Desulfurization reactor, desulfurization liquid buffer tank, circulating cooler, circulating alkali liquid pipeline, the desulfurization reactor is connected to the alkali liquid delivery pipeline and the desalted water supply pipeline, and receives the flue gas discharged from the tail gas incineration unit, wherein the flue gas forms an overweight position under the centrifugal force generated by the desulfurization reactor, the alkali liquid is diluted with desalted water, and is torn into pieces by the centrifugal force in the desulfurization reactor to react with the flue gas, absorb SO2 in the flue gas for desulfurization and purification, the alkali liquid is gathered to the desulfurization liquid buffer tank through the circulating alkali liquid pipeline, and then cooled by the circulating cooler after being transmitted through the circulating alkali liquid pipeline, and then enters the desulfurization reactor again for circulating alkali washing until the flue gas meets the standards and is discharged.

4. A method for treating an accident acid gas in an accident acid gas treatment system of a sulfur recovery unit according to any one of claims 1 to 3, comprising the steps of: Step S100: The acid gas is input into a multi-stage alkali washing tower for step-by-step alkali washing to produce tail gas with a qualified H2S removal rate and a by-product NaHS solution; wherein the tail gas of each alkali washing tower is cooled to below 50°C by a cooler and then transmitted to the next alkali washing tower; in the gas phase space of each alkali washing tower, alkali solution is sprayed to fully cover the gas phase; the acid gas is released below the alkali solution surface to promote gas-liquid contact and form bubbling absorption; the preset liquid level in the alkali washing tower is maintained, and the alkali solution concentration in each alkali washing tower is dynamically diluted by desalted water; and the acid gas is controlled to react in the alkali washing tower to generate NaHS and H2O by any of the following methods: controlling the desalted water to dynamically dilute the NaOH alkali solution concentration in each alkali washing tower, and maintaining the preset liquid level in the alkali washing tower / or controlling the alkali solution delivery pipeline to dynamically adjust the amount and concentration of NaOH alkali solution entering each alkali washing tower; Step S200: The tail gas with the H2S removal rate meeting the standard is mixed with combustion-supporting air and fuel, and input into the incinerator for low-nitrogen combustion. The high-temperature flue gas is cooled to low-temperature flue gas through the by-product steam of the waste heat boiler; Step S300: The low-temperature flue gas is input into the flue gas post-desulfurization unit for SO2 removal treatment to discharge qualified flue gas.

5. The method for treating accidental acid gas of a sulfur recovery unit according to claim 4, wherein the step of performing SO2 removal treatment in the flue gas post-desulfurization unit comprises: The low-temperature flue gas and the alkali solution diluted with desalted water are input into the desulfurization reactor to react under the action of centrifugal force to absorb SO2 in the flue gas for desulfurization and purification; The alkali solution is transmitted through the circulating alkali solution pipeline and cooled in the circulating cooler, and then enters the desulfurization reactor again for circulating alkali washing until the flue gas meets the standards and is discharged.

6. The method for treating accidental acid gas of a sulfur recovery unit according to claim 5, wherein the step of performing SO2 removal treatment in the flue gas post-desulfurization unit comprises: The low-temperature flue gas is input from the bottom of the multi-stage desulfurization tower, and the desulfurization liquid is used to absorb the SO2 in the flue gas through the multi-stage desulfurization section. After desulfurization and purification, the flue gas enters the water washing section and the demisting section in turn for dust and droplet treatment until it is discharged after meeting the standards.

Images