A method for resource utilization of a transformed condensate

Abstract

The present application relates to a kind of transformation condensate resource utilization method.The method includes the following steps: S1, after mixing with sulfuric acid, the transformation condensate is carried out decarburization treatment, and the crude ammonium sulfate solution is obtained;S2, under the action of catalyst, the crude ammonium sulfate solution is reacted with oxidizing agent, and the refined ammonium sulfate solution is obtained;Oxidizing agent includes one or more of hydrogen peroxide, ozone and persulfate.The method of the present application is suitable for different scale transformation condensate treatment process, and has the following characteristics: waste material recycling, recovery rate is more than 99.0%, product added value is high, and economic benefit is good;Avoid the phase change process of water, and energy consumption is less, energy saving and emission reduction;Process flow is simple, and processing efficiency is high;Avoid secondary pollution;Help coal chemical industry enterprise to realize plant material self circulation, and generate good economic benefit by-product.

Description

Technical Field

[0001] This invention relates to a method for the resource utilization of conversion condensate. Background Technology

[0002] Coal gasification and gas shift are important technological pathways for syngas production and the starting point of the coal chemical industry. After these two processes, the gas exiting the shift furnace contains a large amount of water vapor and various impurities. After multi-stage condensation, a large amount of condensate (referred to as "shift condensate") is generated. Its water quality is characterized by high concentrations of pollutants such as NH3, H2S, and CO2, making it difficult to treat.

[0003] Previously, environmental protection strategies have focused on achieving the complete degradation of pollutants. However, the challenge in treating conversion condensate lies in the high concentration of sulfur (S). 2- The wastewater exhibits strong toxicity to microorganisms, making direct biological treatment impossible; pretreatment is necessary. The traditional pretreatment method is a single-tower stripping process, where steam separates H2S from the water, and a portion of the H2S, along with some NH3 waste gas, is incinerated in a flare; the remaining NH3 dissolves in the condensate at the top of the tower, which then enters the wastewater treatment plant's biological treatment system; the bottom liquid is returned to the gasification unit for reuse. However, this pretreatment method commonly suffers from the following problems during operation:

[0004] ① The consumption of steam and circulating cooling water is large (water has a high latent heat of phase change), resulting in high energy consumption;

[0005] ② The separation effect is limited, and flare incineration and biological treatment methods are still needed to remove pollutants, which is a cumbersome and complicated process;

[0006] ③ It generates secondary pollution. The incineration exhaust gas contains a large amount of sulfur dioxide, which requires further desulfurization processes.

[0007] ④ The concentration and total amount of NH3-N entering the biochemical system are high, and the treatment load is high, requiring an additional large amount of easily degradable carbon source to meet the denitrification requirements;

[0008] ⑤ The stripping tower top is severely corroded and clogged (ammonium bicarbonate crystals precipitate), requiring frequent shutdowns for cleaning, maintenance, and replacement.

[0009] ⑥ The treatment effect was not ideal; more than 300 mg / L of NH3 remained in the wastewater after stripping.

[0010] In recent years, single-tower side-stream pressurized stripping and double-tower stripping technologies have been developed and successfully applied to the treatment of shift converter condensates. These methods are improvements upon traditional single-tower stripping, utilizing the fact that CO2 and H2S are more volatile than NH3 to achieve stepwise separation of different components. Although this method offers good separation efficiency and allows for the recovery of some pollutants, it requires more energy, and the price of the recovered products cannot compensate for the additional operating costs.

[0011] Currently, most shift conversion condensate treatment technologies are optimizations and improvements based on the stripping principle. For example, Chinese patent CN210521820U discloses a high-efficiency and energy-saving shift conversion condensate stripping and ammonia recovery system, which solves the environmental pollution, resource waste, and ammonia salt crystallization problems caused by combustion treatment of acidic gas at the top of the stripping tower. However, this doubles the equipment investment and increases operating costs. Patent CN115259259B discloses a shift conversion condensate treatment system and process, which solves the water balance and ammonia balance problems of boiler desulfurization systems, improves the quality of ammonium sulfate, and turns shift conversion condensate into a valuable resource after purification. However, the three parallel shift conversion condensate systems it provides result in complex equipment and process flows.

[0012] Therefore, there is an urgent need to change the traditional mindset and seek a disposal and resource reuse technology that is efficient and economically beneficial. Summary of the Invention

[0013] This invention addresses the shortcomings of traditional stripping processes, which transfer pollutants to the gas phase, resulting in approximately 30-50% of NH3 and H2S being incinerated. These processes are characterized by high energy consumption, complex procedures, secondary pollution, and low efficiency. This invention provides a method for the resource utilization of shift conversion condensate. This invention is applicable to shift conversion condensate treatment processes of varying scales and features the following characteristics: ① Waste material recovery rate exceeding 99.0%, high product added value, and good economic benefits; ② Simple process flow, high treatment efficiency, and high resource utilization rate; ③ Avoidance of secondary pollution; ④ Guarantee of long-term continuous and stable operation of the membrane system, ensuring high technical reliability; ⑤ Avoidance of water phase change, resulting in low energy consumption and energy saving and emission reduction; ⑥ Assistance to coal chemical enterprises in achieving in-plant material self-circulation and generating by-products with good economic benefits.

[0014] The objective of this invention can be achieved through the following technical solutions:

[0015] The present invention also provides a method for the resource utilization of conversion condensate, which includes the following steps:

[0016] S1. The conversion condensate is mixed with sulfuric acid and then subjected to decarbonization treatment to obtain crude ammonium sulfate solution;

[0017] S2. Under the action of a catalyst, the crude ammonium sulfate solution is reacted with an oxidant to obtain a refined ammonium sulfate solution; the oxidant includes one or more of hydrogen peroxide, ozone, and persulfate.

[0018] The preparation method of the catalyst includes the following steps:

[0019] a. Containing Ca 2+ Mn 2+ and Fe3+ The mixed solution is mixed with urea to form a suspension, and then kept at a certain temperature to allow the suspension to crystallize, yielding a solid mixture; the mixed solution contains Ca 2+ Mn 2+ and Fe 3+ The molar ratio is (1-2):(1-4):1;

[0020] b. React the aqueous solution of the solid mixture with an ammonium metavanadate solution to obtain a precipitate;

[0021] c. Calcine the precipitate.

[0022] The purpose of this invention is to shift from the traditional "pollutant degradation" mindset to the "circular economy" mindset. The method of this invention enables the disposal of coal chemical conversion condensate and the resource utilization of the condensate.

[0023] In this invention, the catalyst prepared by the aforementioned catalyst preparation method belongs to the category of hydrotalcite-like catalysts.

[0024] In some embodiments, in step a, the Ca in the mixed solution 2+ It is added in the form of a soluble calcium salt; said soluble calcium salt includes calcium nitrate.

[0025] In some embodiments, in step a, the Mn in the mixed solution 2+ It is added in the form of a soluble manganese salt; said soluble manganese salt includes manganese nitrate.

[0026] In some embodiments, in step a, Fe in the mixed solution 3+ It is added in the form of a soluble iron salt; said soluble iron salt includes ferric nitrate.

[0027] In some embodiments, in step a, the Ca in the mixed solution 2+ Mn 2+ and Fe 3+ The molar ratio is 2:2.5:1.

[0028] In some embodiments, in step a, the mixing temperature is 60-80°C, for example 75°C.

[0029] In this invention, in step a, the urea mainly functions as an alkaline substance, and the amount of urea added is preferably such that the metal ions in the above mixed solution precipitate as much as possible. The amount added can be determined by those skilled in the art according to their needs.

[0030] In some embodiments, in step a, the concentration of urea is 2 to 5 mol / L, for example 3 mol / L.

[0031] In some embodiments, in step a, the urea and the Ca in the mixed solution 2+ Mn 2+ Fe 3+ The molar ratio is ≥1.5, for example, 2.5.

[0032] In this invention, the heat preservation is to induce crystallization of the suspension in step a.

[0033] In some implementations, in step a, the heat preservation time is greater than or equal to 10 hours.

[0034] In this invention, the heat preservation process is carried out in a reactor where mixing is performed, and the heat preservation temperature is the same as the mixing temperature, so as to separate solids and liquids and remove residual impurity ions from the water.

[0035] In some embodiments, in step a, the temperature of the heat preservation is 60-80°C.

[0036] In some implementations, after the heat preservation is completed in step a, the material is further subjected to centrifugation and drying processes.

[0037] In some embodiments, in step b, the pH of the aqueous solution of the solid mixture is adjusted to 4.5-5.5.

[0038] In this invention, in step b, ammonium metavanadate solution can be added in different proportions depending on the required exchange amount of the solid mixture. Those skilled in the art can determine the amount added according to their needs.

[0039] In some embodiments, in step b, the concentration of the ammonium metavanadate solution is 0.1 mol / L.

[0040] In some embodiments, in step b, the ratio of the number of moles of ammonium metavanadate to the total number of moles of metal ions in the solid mixture is 0.1 to 0.5.

[0041] In some embodiments, the temperature of the reaction in step b is 40-60°C, for example, 60°C.

[0042] In some implementations, the reaction time in step b is 1-4 hours, for example, 4 hours.

[0043] In some embodiments, after the reaction is completed in step b, the precipitate is washed and dried sequentially.

[0044] In some embodiments, in step c, the calcination is carried out in an oxygen-free atmosphere, which means an atmosphere that does not contain oxygen.

[0045] In some embodiments, in step c, the calcination temperature is 300-550°C, preferably 350-500°C.

[0046] In some embodiments, the calcination time in step c is 2-6 hours, for example, 5 hours.

[0047] In some embodiments, in step S1, the decarbonization process includes blowing air into the mixture of the shift condensate and sulfuric acid; wherein the sulfuric acid can be sulfuric acid of any concentration.

[0048] In this process, air is blown into the mixture to remove dissolved carbon dioxide and hydrogen sulfide. This air-blowing method can improve treatment efficiency and reduce the content of carbon dioxide and hydrogen sulfide in the shift condensate.

[0049] In some embodiments, in step S1, the shift condensate comprises NH3, H2S, and CO2; the composition of the shift condensate is mainly composed of NH3, H2S, and CO2, with only trace amounts of F. - CN - The processing method and apparatus are not limited by the composition and content of the condensate.

[0050] In this invention, the purpose of decarbonation is to replace anions, converting carbonate and sulfide ions into sulfate ions, thereby generating carbon dioxide and hydrogen sulfide, which then escape; the escaped hydrogen sulfide can be recovered by a sulfur recovery device.

[0051] In this invention, the purpose of decarbonization is to transfer partially dissolved carbon dioxide and hydrogen sulfide from the liquid phase to the gas phase.

[0052] In this invention, both the decarburization treatment in step S1 and the reaction in step S2 can be carried out under normal pressure.

[0053] In this invention, the decarbonization treatment in step S1 and the reaction in step S2 can both be carried out at room temperature or high temperature; preferably, the reaction temperature is 30-60℃.

[0054] In some embodiments, in step S1, the concentration of ammonia nitrogen in the shift condensate is ≥500 mg / L. 2- The concentration is ≥10mg / L, the alkalinity is ≥2000mg / L, and the COD value is 100-2000mg / L; wherein, the concentration of ammonia nitrogen can be expressed as the concentration of NH3-N, and the alkalinity is calculated as the mass concentration of calcium carbonate.

[0055] In a specific implementation, in step S1, the concentration of ammonia nitrogen in the shift condensate is 500 mg / L-5000 mg / L. 2-The concentration is 10 mg / L-2000 mg / L, the alkalinity is 2000 mg / L-20000 mg / L, and the COD value is 100-2000 mg / L. The alkalinity is calculated based on the mass concentration of calcium carbonate.

[0056] In some embodiments, in step S1, the molar ratio of the sulfuric acid to the alkalinity of the shift condensate is 0.95-1.10; wherein the molar value of the alkalinity of the shift condensate is the mass concentration of alkalinity divided by the relative molecular weight of calcium carbonate.

[0057] In some embodiments, in step S1, prior to the decarbonization treatment, the pH of the mixture of the shift condensate and sulfuric acid is adjusted to 4.0-5.0.

[0058] In this invention, in step S2, by adding a catalyst, sulfide ions can be oxidized to sulfate ions in their highest oxidation state.

[0059] In this invention, the oxidation process of sulfide ions in hydrogen sulfide is as follows: S 2- →S→S2O3 2- →SO3 2- →SO4 2- In this process, the sulfur concentration in the conversion condensate is relatively low, and its oxidation rate is slow, which is a key factor affecting the processing efficiency of the unit. The catalyst of this application can improve the conversion rate of low-valent sulfides (oxides) to sulfate and the utilization efficiency of the oxidant; and achieve complete decomposition of residual oxidant, avoiding damage to subsequent components.

[0060] In this invention, hydrogen sulfide has two fates: ① it is stripped to the gas phase for sulfur recovery, with a recovery rate of >98%; ② it remains in the water and is oxidized to sulfate ions in the oxidation reaction for utilization, with a recovery rate of >99% based on the residual sulfur ion concentration. Therefore, the total hydrogen sulfide recovery rate in the shift condensate is >98%.

[0061] In some embodiments, in step S2, the persulfate includes one or more of ammonium persulfate, potassium persulfate, and sodium persulfate.

[0062] In some embodiments, in step S2, the molar ratio of the effective oxygen equivalent of the oxidant to the sulfur ions in the crude ammonium sulfate solution is greater than or equal to 4:1, preferably (4-8):1, for example 4.5:1.

[0063] The effective oxygen equivalent of the oxidant is the amount of oxygen that can be transferred out per mol of oxidant.

[0064] In some embodiments, in step S2, the amount of catalyst used accounts for 0.1%-5% of the total mass of the crude ammonium sulfate, preferably 0.3%-5%.

[0065] In some embodiments, in step S2, the reaction is carried out under stirring conditions; preferably, the stirring method includes mechanical stirring and / or gas stirring; the intensity of the mechanical stirring is 4-15 W / m. 3 The intensity of the gas stirring is 1-4 m. 3 / (m 2 ·h).

[0066] In some embodiments, the reaction time in step S2 is 0.3-4.0 h.

[0067] In some embodiments, in step S2, the S of the refined ammonium sulfate solution 2- Concentration ≤ 1.0 mg / L.

[0068] In some embodiments, the method for resource utilization of the conversion condensate further includes: S3, post-processing the refined ammonium sulfate solution to obtain solid ammonium sulfate.

[0069] In a specific implementation, the post-processing method includes filtration, concentration, and evaporation crystallization in sequence.

[0070] In a preferred embodiment, the filtration is carried out in a membrane filtration system to ensure that the resulting solution is free of suspended particles and colloidal substances, otherwise it will cause clogging and damage to the membrane element; in addition, the use of this membrane filtration system can realize the recovery and reuse of the catalyst.

[0071] Preferably, the filter membrane in the membrane filtration system includes a microporous filter membrane and / or an ultrafiltration membrane.

[0072] Preferably, the pore size of the filter membrane in the membrane filtration system is 0.02-10 μm.

[0073] Preferably, the surface flow velocity of the filter membrane in the membrane filtration system is 1-6 m / s.

[0074] The filter membrane in the membrane filtration system is generally made of inorganic materials or organic polymer materials.

[0075] Preferably, the inorganic material includes one or more of aluminum oxide, zirconium dioxide, titanium dioxide, stainless steel, alloys, and silicon carbide; or, the organic polymer material includes one or more of polysulfone, polyethersulfone, polyvinylidene fluoride, polyvinyl chloride, polyethylene, and polypropylene. The alloy may be a nickel alloy.

[0076] In a preferred embodiment, the filtration employs a cross-flow filtration method.

[0077] In a preferred embodiment, the operating pressure of the filter is 0.2-1.0 MPa.

[0078] In a preferred embodiment, the operating temperature of the filter is 1-90°C.

[0079] In a preferred embodiment, the concentration is carried out in a membrane concentration system.

[0080] Preferably, the concentration membrane in the membrane concentration system has a sodium chloride rejection rate of >95%.

[0081] Preferably, the concentrating membrane in the membrane concentration system includes a reverse osmosis membrane.

[0082] The material of the concentration membrane in the membrane concentration system generally includes organic polymer materials.

[0083] Preferably, the material of the concentration membrane includes one or more of polysulfone, polyethersulfone, polyvinylidene fluoride, polyvinyl chloride, polyethylene, polyamide, polypropylene, polyacrylonitrile, cellulose acetate, piperazineamide, propylene-alkyl polyamide, condensed urea, furfuryl alcohol, trihydroxyethyl isocyanate, m-phenylenediamine, and pyromellitic trimethylolpropionate.

[0084] Preferably, the concentrated membrane in the membrane concentration system is of one type: spiral wound, tubular, capillary, or plate.

[0085] In a preferred embodiment, the concentration operation pressure is 0.1-12 MPa.

[0086] In a preferred embodiment, the concentration operation temperature is 1-40°C.

[0087] In a preferred embodiment, after the concentration is completed, the mass percentage of ammonium sulfate in the ammonium sulfate solution is 10-20%.

[0088] In this invention, product water and condensate are obtained by concentration and evaporation crystallization, respectively. The NH3-N concentration in the product water and the condensate is ≤20mg / L. It can be used as process water and circulated to various water points in the plant area, including but not limited to: gasification coal mill unit, gasification ash water makeup water, flushing water, etc.

[0089] In some embodiments, the resource utilization method of the shift condensate employs a processing system comprising a decarbonization device and an oxidation reaction device connected in sequence; the decarbonization device is used to mix the shift condensate with sulfuric acid and perform decarbonization treatment to form a crude ammonium sulfate solution; the oxidation reaction device is used to remove sulfur ions from the crude ammonium sulfate solution to obtain a refined ammonium sulfate solution.

[0090] In a specific embodiment, the processing system further includes a filtration device, a concentration device, and a crystallization device connected in sequence. The inlet of the filtration device is connected to the outlet of the oxidation reaction device for separating the clear liquid containing ammonium sulfate and the slurry containing the catalyst. The inlet of the concentration device is connected to the clear liquid outlet of the filtration device.

[0091] In a preferred embodiment, the concentration device includes a product water outlet and a concentrated ammonium sulfate outlet, the concentrated ammonium sulfate outlet being connected to the feed inlet of the crystallization device.

[0092] In a preferred embodiment, the crystallization apparatus includes a condensate outlet and an ammonium sulfate solid outlet.

[0093] In a specific embodiment, the slurry outlet of the filtration device is connected to the oxidation reaction device for recycling the catalyst slurry back to the oxidation reaction device.

[0094] In a specific implementation, the slurry outlet of the filtration device is also connected to the feed inlet of the filtration device.

[0095] In a preferred embodiment, the crystallization apparatus includes an evaporator crystallizer; the evaporator crystallizer may be a forced circulation evaporator and / or a mechanical recompression evaporator (MVR).

[0096] In a specific embodiment, the oxidation reaction apparatus further includes a catalyst inlet and an oxidant inlet.

[0097] In a specific embodiment, the decarbonization device further includes a sulfuric acid inlet, a shift condensate inlet, a non-condensable gas outlet, and an air inlet; preferably, the air inlet is located at the bottom or lower part of the decarbonization device.

[0098] In this invention, pollutants are retained in the aqueous phase, thereby significantly reducing the amount of exhaust gas.

[0099] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0100] The reagents and raw materials used in this invention are all commercially available.

[0101] The positive and progressive effects of this invention are as follows:

[0102] (1) High recycling rate: Pollutants are converted into high-value ammonium sulfate for recycling, with an NH3 recovery rate of over 99.0%;

[0103] (2) The process is simple, easy to operate, and has a high resource utilization rate: the process water does not need to be discharged into the sewage station for further treatment, and can be directly recycled to each process water point for production use (including but not limited to gasification coal mill unit, gasification ash water makeup water, flushing water, etc.); in addition, the generated gas can be reused to recover sulfur, avoiding incineration and saving a lot of fuel gas.

[0104] (3) High technical reliability: The residual sulfur ion concentration is extremely low, which effectively avoids membrane fouling caused by sulfides and ensures that the membrane system can operate continuously and stably for a long time.

[0105] (4) Reduced energy consumption: Avoiding the phase change process of water, the energy required for treatment is lower compared with the traditional stripping process.

[0106] (5) This application assists coal chemical enterprises in realizing the self-circulation of materials within the plant and generating by-products with good economic benefits. Attached Figure Description

[0107] Figure 1 This is a schematic diagram of the structure of the transformation condensate treatment system of Embodiment 1 of the present invention.

[0108] Explanation of reference numerals in the attached figures:

[0109] Decarbonization Unit 1

[0110] Sulfuric acid entrance 101

[0111] 102 condensate inlet

[0112] Non-condensable gas outlet 103

[0113] Air inlet 104

[0114] Oxidation Reaction Apparatus 2

[0115] Catalyst inlet 201

[0116] Oxidizing agent inlet 202

[0117] Filter device 3

[0118] 301 Slurry outlet of the filtration unit

[0119] Clarified liquid outlet 302 of the filtration device

[0120] Filter inlet 303

[0121] Concentration Unit 4

[0122] Inlet 401 of the concentration unit

[0123] Product water export 402

[0124] Crystallization device 5

[0125] Condensate outlet 501

[0126] Ammonium sulfate solids outlet 502. Detailed Implementation

[0127] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0128] Example 1

[0129] Figure 1 The conversion condensate treatment system of this embodiment includes a decarbonization device 1, an oxidation reaction device 2, and a filtration device 3 connected in sequence. The decarbonization device 1 is used to mix the conversion condensate with sulfuric acid and remove carbon dioxide and hydrogen sulfide to form a crude ammonium sulfate solution. The oxidation reaction device 2 is used to remove sulfur ions from the crude ammonium sulfate solution and obtain a refined ammonium sulfate solution. The filtration device 3 is used to separate the clear liquid containing ammonium sulfate and the slurry containing catalyst. The slurry outlet 301 of the filtration device is connected to the oxidation reaction device 2 for recycling the catalyst slurry back to the oxidation reaction device 2.

[0130] The slurry outlet 301 of the filter device is also connected to the feed inlet 303 of the filter device;

[0131] The conversion condensate treatment device also includes a concentration device 4 and a crystallization device 5 connected in series. The feed inlet 401 of the concentration device is connected to the clear liquid outlet 302 of the filtration device. The concentration device 4 includes a product water outlet 402. The crystallization device 5 includes a condensate outlet 501 and an ammonium sulfate solid outlet 502.

[0132] The oxidation reaction device 2 also includes a catalyst inlet 201 and an oxidant inlet 202;

[0133] The decarbonization device 1 also includes a sulfuric acid inlet 101, a shift condensate inlet 102, a non-condensable gas outlet 103, and an air inlet 104; the air inlet 104 is located at the bottom or lower part of the decarbonization device 1.

[0134] Example 2

[0135] This embodiment describes a method for preparing a vanadium-intercalated Ca-Mn-Fe ternary hydrotalcite catalyst, which includes the following steps:

[0136] a) Calcium nitrate, manganese nitrate, and ferric nitrate were mixed in a molar ratio of 2:2.5:1 to obtain a mixed metal solution, with the temperature maintained at 75℃ during preparation. 3.0 mol / L urea was added to the mixed metal solution to form a suspension, with the molar ratio of urea to the metal ions in the mixed metal solution being 2.5:1. The suspension was kept at this temperature and allowed to crystallize for 16 hours before centrifugation and drying to obtain a solid mixture.

[0137] b. After grinding the above solid mixture, dissolve it in water to obtain a suspension. Adjust the pH to 5.0±0.5, maintain the temperature at 60℃, add ammonium metavanadate solution with a molar ratio of 0.4 to the solid mixture, and react for 4 hours. After washing and drying, a precipitate is obtained.

[0138] c. The precipitate was placed in an oxygen-free atmosphere and calcined at 460℃ for 5 hours to obtain a vanadium-intercalated Ca-Mn-Fe ternary hydrotalcite catalyst.

[0139] Examples 3.1-3.6

[0140] This embodiment examines the treatment effect under different effective oxygen equivalents and sulfur ion molar ratios when hydrogen peroxide is used as the oxidant.

[0141] The shift condensate used in these examples was taken from a coal chemical enterprise in Inner Mongolia, with a COD of 711 mg / L, NH3-N of 1736 mg / L, and S... 2- =324mg / L, alkalinity =6378mg / L.

[0142] The resource utilization method for the shift condensate in Example 3.1 uses the processing system of Example 1 and includes the following steps:

[0143] S1. The shift condensate is mixed with sulfuric acid until the pH value is 4.5, and then sent to decarbonization tower 1 for decarbonization treatment to obtain crude ammonium sulfate solution; wherein, the molar ratio of alkalinity of shift condensate to sulfuric acid is 1.05; carbon dioxide and hydrogen sulfide are blown off from the water by blowing air to obtain crude ammonium sulfate dilute solution.

[0144] S2. Under the action of the vanadium-intercalated Ca-Mn-Fe ternary hydrotalcite catalyst prepared in Example 2, the amount of vanadium-intercalated Ca-Mn-Fe ternary hydrotalcite catalyst accounts for 2.0% of the total mass of the shift condensate. The crude ammonium sulfate solution in step S1 is thoroughly stirred and reacted with hydrogen peroxide in oxidation reaction device 2. The effective oxygen equivalent of hydrogen peroxide to the molar ratio of sulfur ions is 3.8, and the mechanical stirring intensity is 15 W / m. 3 The reaction time is 0.5 h, which is used to remove sulfur ions and simultaneously purify and refine wastewater to obtain a refined ammonium sulfate solution.

[0145] In Examples 3.2, 3.3, 3.4, 3.5, and 3.6, the molar ratio of effective oxygen equivalent of hydrogen peroxide to sulfur ions was 4.1, 4.5, 5.2, 6.0, and 8.0, respectively. All other conditions were the same as in Example 3.1.

[0146] Examples 4.1-4.6

[0147] This embodiment examines the treatment effect of using ozone as an oxidant under different effective oxygen equivalents and sulfur ion molar ratios.

[0148] The resource utilization method of the conversion condensate in Example 4.1 is the same as that in Example 3.1. In step S2, ozone is used as the oxidant, and the molar ratio of effective oxygen equivalent of ozone to sulfur ions is 3.8. All other conditions are the same as in Example 3.1.

[0149] In Examples 4.2, 4.3, 4.4, 4.5, and 4.6, the molar ratio of effective oxygen equivalent of ozone to sulfur ions was 4.1, 4.5, 5.2, 6.0, and 8.0, respectively. All other conditions were the same as in Example 4.1.

[0150] Examples 5.1-5.6

[0151] This embodiment examines the treatment effect of using ammonium persulfate as an oxidant under different effective oxygen equivalents and sulfur ion molar ratios.

[0152] The resource utilization method of the conversion condensate in Example 5.1 is the same as that in Example 3.1. In step S2, ammonium persulfate is used as the oxidant, and the molar ratio of effective oxygen equivalent of ammonium persulfate to sulfur ions is 3.8. All other conditions are the same as in Example 3.1.

[0153] In Examples 5.2, 5.3, 5.4, 5.5, and 5.6, the molar ratio of effective oxygen equivalent to sulfur ions of ammonium persulfate was 4.1, 4.5, 5.2, 6.0, and 8.0, respectively. All other conditions were the same as in Example 5.1.

[0154] Example 1

[0155] This example demonstrates the treatment effects of Examples 3.1-3.6, 4.1-4.6, and 5.1-5.6. The concentrations of sulfur ions and COD in the effluent after the oxidation reaction were measured. The sulfur ion concentration was measured using the current national standard iodometric method (HJ / T60-2000), and the COD concentration was measured using the current national standard potassium dichromate method (HJ 828-2017). The results are shown in Table 1.

[0156] Table 1 shows the effect of the type and amount of oxidant on the treatment effect in Examples 3-5. In Table 1, S... 2-Both COD and COD are measured in mg / L.

[0157] Table 1

[0158]

[0159] As shown in Table 1, under the action of a catalyst, Examples 3-5 used hydrogen peroxide, ozone, and ammonium persulfate as oxidants, respectively, to reduce the effluent S 2- The concentration is reduced to 3.01 mg / L or below, and the COD is reduced to 179 mg / L or below; preferably, when the molar ratio of the effective oxygen equivalent of the oxidant to sulfur ions is ≥4.0, hydrogen peroxide, ozone, and persulfate can all ensure the effluent sulfur content. 2- The concentration was ≤1.0mg / L; meanwhile, the COD of the above batches of effluent was measured to be 13-87mg / L, showing good wastewater purification effect.

[0160] Examples 6.1-6.6

[0161] This embodiment investigates the effect of the dosage of vanadium-intercalated Ca-Mn-Fe ternary hydrotalcite catalyst on the removal efficiency of sulfur ions. The same shift condensate as in Example 3.3 was used as the water sample in this embodiment.

[0162] In step S2, the amount of catalyst used accounts for 0.1% of the total mass of the conversion condensate, and the other operating steps and processes are the same as in Example 3.3.

[0163] In Examples 6.2, 6.3, 6.4, 6.5, and 6.6, the amount of catalyst used accounts for 0.1%, 0.3%, 0.5%, 1.0%, 3.0%, and 5.0% of the total mass of the conversion condensate, respectively. All other conditions are the same as in Example 6.1.

[0164] Comparative Example 1

[0165] This comparative example used the same treatment method as in Example 6.1; however, no hydrotalcite catalyst was added in step S2. Otherwise, all other conditions were the same as in Example 6.1.

[0166] Example 2

[0167] This effective example demonstrates the sulfur ion treatment effect of Examples 6.1-6.6 and Comparative Example 1; the sulfur ion concentration in the effluent after the oxidation reaction was detected; the sulfur ion detection method was the current national standard iodometric method (HJ / T60-2000), and the results are shown in Table 2.

[0168] Table 2 shows the effect of catalyst dosage on the sulfur ion treatment effect in Examples 6.1-6.6 and Comparative Example 1.

[0169] Table 2

[0170]

[0171]

[0172] As shown in Table 2, when no catalyst is added, the S in the reactor effluent of Comparative Example 1 2- The concentration remains above 10 mg / L; under the action of the catalyst, the sulfur concentration in the effluent is reduced. 2- The concentration can be reduced to 2.69 mg / L or below; preferably, when the catalyst dosage is ≥0.3%, the S in the effluent... 2- The concentration can be stably maintained at ≤1.0mg / L, demonstrating excellent sulfur ion removal effect.

[0173] Example 7

[0174] In this embodiment, the conversion condensate was taken from a coal chemical enterprise in Inner Mongolia, and approximately 20m³ of it was collected in the inlet tank. 3 The condensate concentration was changed, COD = 611 mg / L, and the water sample NH3-N = 4800 mg / L. 2- =236mg / L, alkalinity =18700mg / L;

[0175] This embodiment uses the processing system of Embodiment 1 and includes the following steps:

[0176] S1. In this embodiment, the shift condensate is pumped to the decarbonization tower 1, sulfuric acid is added (the molar ratio of sulfuric acid to the alkalinity of the shift condensate is 1.10) to control the pH to 4.0, and air is blown in to remove the generated carbon dioxide and hydrogen sulfide to obtain a crude ammonium sulfate dilute solution.

[0177] S2. The crude ammonium sulfate dilute solution is transported to oxidation reactor 2 and filtered by filter device 3 in the membrane filtration system to retain the vanadium intercalated Ca-Mn-Fe ternary hydrotalcite slurry prepared in Example 2 (catalyst dosage approximately 2.6%, % being the mass ratio of catalyst to total mass of shift condensate). Hydrogen peroxide is quantitatively added to the reactor (molar ratio of effective oxygen equivalent to sulfur ions = 4.5:1), and gas stirring is employed (stirring intensity 3.2 m). 3 / (m 2 After a reaction of 2.0 h, the effluent S 2- The concentration was 0.28 mg / L and the COD value was 34 mg / L. It was pumped into the membrane filtration system.

[0178] S3. Under operating pressure of 0.6 MPa, temperature of approximately 32℃, and surface flow velocity of 3.2 m / s, cross-flow filtration was performed using a stainless steel membrane (0.5 μm pore size). The catalyst slurry retained by the membrane was recycled to oxidation reactor 2. After 10 cycles of testing, the catalytic effect did not decrease, and the effluent S...2- The concentration is stable at ≤0.6 mg / L, and the COD value is ≤90 mg / L; the clear liquid permeating through the membrane enters the membrane concentration system. The concentration membrane is made of polyamide and operates at a pressure of 0.1-12 MPa and a temperature of approximately 25°C.

[0179] Based on NH3-N concentration, ammonium sulfate recovery rate = (N content in concentrate * flow rate of concentrate) / (N content in shift condensate * flow rate of shift condensate)

[0180] When the ammonium sulfate solution is concentrated to a mass concentration of about 18%, the concentration of NH3-N in the raw water, membrane permeate, and concentrate is detected and calculated, and the ammonium sulfate recovery rate reaches about 99.1%. The process water passing through the concentrated membrane is transported to the gasification section for recycling.

[0181] Based on sulfide ions, the sulfur recovery rate of the sulfur entering the plant's sulfur recovery unit after step S1 stripping is >98%; the oxidation reaction in step S2 achieves a recovery rate of over 99% for the remaining sulfur. Therefore, the overall sulfur recovery rate is also 98%.

[0182] Example 8

[0183] In this embodiment, the conversion condensate was taken from a coal chemical enterprise in Shaanxi Province, and approximately 10m³ of it was collected in the inlet tank. 3 The condensate was changed, with COD = 1864 mg / L, NH3-N = 3059 mg / L, and S... 2- =1760mg / L, alkalinity =12493mg / L.

[0184] This embodiment uses the processing system of Embodiment 1 and includes the following steps:

[0185] S1. In this embodiment, the shift condensate is pumped to the decarbonization tower 1, sulfuric acid is added (the molar ratio of sulfuric acid to the alkalinity of the shift condensate is 0.95) to control the pH to 5.0, and air is blown in to strip off the generated carbon dioxide and hydrogen sulfide, and a crude ammonium sulfate dilute solution is obtained.

[0186] S2. The crude ammonium sulfate dilute solution is transported to oxidation reactor 2 and filtered by filter device 3 in the membrane filtration system to retain the vanadium intercalated Ca-Mn-Fe ternary hydrotalcite slurry prepared in Example 2 (catalyst dosage is approximately 4.7%, where % is the mass ratio of catalyst to total mass of conversion condensate). Hydrogen peroxide (molar ratio of effective oxygen equivalent to sulfur ions = 5.0:1) is quantitatively added to oxidation reactor 2 under mechanical stirring (stirring intensity is 10 W / m). 3 After a reaction of 4.0 h, the effluent S 2- The concentration was 0.74 mg / L and the COD value was 72 mg / L. It was pumped into the membrane filtration system.

[0187] S3. Under operating pressures of 0.2-1.0 MPa, temperatures of approximately 25°C, and surface flow rates of 2.4 m / s, cross-flow filtration was performed using a polyvinylidene fluoride membrane (0.05 μm pore size). The catalyst slurry retained by the membrane was recycled back to the reactor. After 10 cycles of testing, the catalytic efficiency showed no decline, and the effluent S... 2- The concentration is stable at ≤1.0 mg / L, and the COD value is ≤100 mg / L; the supernatant permeating through the membrane enters the membrane concentration system. The concentration membrane operates at a pressure of 0.1-12 MPa and a temperature of approximately 25°C.

[0188] When the ammonium sulfate solution is concentrated to a mass concentration of about 17%, the concentration of NH3-N in the raw water, membrane permeate, and concentrate is detected and calculated, and the ammonium sulfate recovery rate reaches about 99.4%. The process water passing through the concentrated membrane is transported to the gasification section for recycling.

[0189] Example 3

[0190] The embodiments in this application do not use steam, and the total power consumption of the entire process is only 5-6 kWh / ton of water. With an electricity price of 0.6 yuan / kWh, the energy cost of treating one ton of shift condensate is only 3-4 yuan.

[0191] Comparative Example 2

[0192] This comparative example shows the operational results of Example 7 under different operating parameters.

[0193] Specifically, in step S2, no vanadium-intercalated Ca-Mn-Fe ternary hydrotalcite catalyst was added during the oxidation reaction; the molar ratio of effective oxygen equivalent to sulfur ions was 6.0, and the reaction time was extended to 3.0 h; all other operating conditions were the same as in Example 7.

[0194] Water Outflow S 2- The concentration was still 7.16 mg / L, with a strong H2S odor. This not only fails to ensure operational safety but also easily causes sulfide fouling in the downstream concentration membrane.

[0195] Comparative Example 3

[0196] This comparative example shows the operational results of Example 6.4 under different operating parameters.

[0197] Specifically, in step S2, the catalyst used in the oxidation reaction is a Ca-Mn composite catalyst formed by impregnation and calcination of calcium-based bentonite and potassium permanganate (not a vanadium-intercalated Ca-Mn-Fe ternary hydrotalcite catalyst); other operating conditions are the same as in Example 6.4.

[0198] When the catalyst dosage is increased from 1.0% to 5.0%, the effluent S 2- The concentration decreased from 9.45 mg / L to 2.08 mg / L, and the residual S2- The concentration remains high, and it is prone to sulfide fouling when it enters the membrane concentration system.

[0199] Comparative Example 4

[0200] This comparative example shows the operational results of Example 6.6 under different operating parameters.

[0201] Specifically, in step S2, the catalyst used in the oxidation reaction is a common Mg-Al hydrotalcite catalyst (not a vanadium-intercalated Ca-Mn-Fe ternary hydrotalcite catalyst).

[0202] When the catalyst dosage is 5.0%, the effluent S 2- At a concentration of 10.85 mg / L, it did not exhibit significant catalytic activity.

[0203] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for the resource utilization of shift condensate, characterized in that, It includes the following steps: S1. The conversion condensate is mixed with sulfuric acid and then subjected to decarbonization treatment to obtain crude ammonium sulfate solution; S2. Under the action of a catalyst, the crude ammonium sulfate solution is reacted with an oxidant to obtain a refined ammonium sulfate solution; the oxidant includes one or more of hydrogen peroxide, ozone, and persulfate; the molar ratio of the effective oxygen equivalent of the oxidant to the sulfur ions in the crude ammonium sulfate solution is greater than or equal to 4:1; the amount of the catalyst is 0.3%-5% of the total mass of the crude ammonium sulfate solution; The preparation method of the catalyst includes the following steps: a. Containing Ca 2+ Mn 2+ and Fe 3+ The mixed solution is mixed with urea to form a suspension, and then kept at a certain temperature to allow the suspension to crystallize, yielding a solid mixture; the mixed solution contains Ca 2+ Mn 2+ and Fe 3+ The molar ratio is (1~2):(1~4):1; b. React the aqueous solution of the solid mixture with an ammonium metavanadate solution to obtain a precipitate; c. Calcine the precipitate.

2. The method for resource utilization of shift-converted condensate as described in claim 1, characterized in that, In step a, the mixed solution satisfies one or more of the following conditions: ① The Ca in the mixed solution 2+ It is added in the form of a soluble calcium salt; said soluble calcium salt includes calcium nitrate; ②Mn in the mixed solution 2+ It is added in the form of a soluble manganese salt; said soluble manganese salt includes manganese nitrate; ③Fe in the mixed solution 3+ It is added in the form of a soluble iron salt; said soluble iron salt includes ferric nitrate; And / or, in step a, the mixing temperature is 60-80°C; And / or, in step a, the concentration of urea is 2~5 mol / L; And / or, in step a, the urea reacts with the Ca in the mixed solution. 2+ Mn 2+ Fe 3+ The molar ratio is ≥1.5; And / or, in step a, the heat preservation time is greater than or equal to 10 h; And / or, in step a, after the heat preservation is completed, the material is further subjected to centrifugation and drying processes in sequence.

3. The method for resource utilization of shift-converted condensate as described in claim 2, characterized in that, Ca in the mixed solution 2+ Mn 2+ and Fe 3+ The molar ratio is 2:2.5:1; And / or, the Ca in the mixed solution 2+ Added in the form of calcium nitrate; And / or, the Mn in the mixed solution 2+ Added in the form of manganese nitrate; And / or, Fe in the mixed solution 3+ Added in the form of ferric nitrate; And / or, in step a, the mixing temperature is 75°C; And / or, in step a, the concentration of urea is 3 mol / L; And / or, in step a, the urea reacts with the Ca in the mixed solution. 2+ Mn 2+ Fe 3+ The molar ratio is 2.

5.

4. The method for resource utilization of shift-converted condensate as described in claim 1, characterized in that, In step b, the reaction satisfies one or more of the following conditions: ① Prior to the reaction, the pH of the aqueous solution of the solid mixture is adjusted to 4.5-5.5; ②The reaction temperature is 40-60℃; ③ The reaction time is 1-4 hours; ④ After the reaction is completed, the precipitate is washed and dried in sequence.

5. The method for resource utilization of shift-converted condensate as described in claim 1, characterized in that, In step c, the calcination satisfies one or more of the following conditions: ①The calcination is carried out in an oxygen-free atmosphere; ② The calcination temperature is 300-550℃; ③ The calcination time is 2-6 h.

6. The method for resource utilization of shift-conversion condensate as described in claim 5, characterized in that, The calcination temperature is 350-500℃; And / or, the calcination time is 5 h.

7. The method for resource utilization of shift-converted condensate as described in claim 1, characterized in that, In step S1, the decarbonization process includes blowing air into the mixture of the shift condensate and sulfuric acid; And / or, the conversion condensate includes NH3, H2S and CO2; And / or, in the transformed condensate, the concentration of ammonia nitrogen is ≥500 mg / L, S 2- Concentration ≥10 mg / L, alkalinity ≥2000 mg / L, COD value 100-2000 mg / L; And / or, the molar ratio of the sulfuric acid to the alkalinity of the conversion condensate is 0.95-1.10; And / or, prior to the decarbonization treatment, the pH of the mixture of the shift condensate and sulfuric acid is adjusted to 4.0-5.

0.

8. The method for resource utilization of shift-converted condensate as described in claim 1, characterized in that, In step S2, the persulfate includes one or more of ammonium persulfate, potassium persulfate, and sodium persulfate; And / or, the molar ratio of the effective oxygen equivalent of the oxidant to the sulfur ions in the crude ammonium sulfate solution is (4-8):1; And / or, the reaction is carried out under stirring conditions; And / or, the reaction time is 0.3-4.0 h; And / or, the S of the refined ammonium sulfate solution 2- Concentration ≤ 1.0 mg / L.

9. The method for resource utilization of shift-converted condensate as described in claim 8, characterized in that, The stirring method includes mechanical stirring and / or gas stirring; the intensity of the mechanical stirring is 4-15 W / m. 3 The intensity of the gas stirring is 1-4 m. 3 / (m 2 ·h).

10. The method for resource utilization of shift-conversion condensate as described in claim 1, characterized in that, The method for resource utilization of the shift condensate also includes: S3. The refined ammonium sulfate solution described in step S2 is post-processed to obtain solid ammonium sulfate.

11. The method for resource utilization of shift-conversion condensate as described in claim 10, characterized in that, In step S3, the post-processing method sequentially includes filtration, concentration, and evaporation crystallization; the filtration is performed in a membrane filtration system. And / or, the filtering adopts a cross-flow filtering method; And / or, the operating pressure of the filter is 0.2-1.0 MPa; And / or, the operating temperature of the filter is 1-90°C; And / or, the concentration is carried out in a membrane concentration system; And / or, the concentration is carried out at an operating pressure of 0.1-12 MPa; And / or, the concentration operation temperature is 1-40°C; And / or, after the concentration is completed, the mass percentage of ammonium sulfate in the ammonium sulfate solution is 10-20%.

12. The method for resource utilization of shift-conversion condensate as described in claim 11, characterized in that, In step S3, the filter membrane in the membrane filtration system satisfies one or more of the following conditions: ①The filter membrane includes a microporous filter membrane and / or an ultrafiltration membrane; ② The pore size of the filter membrane is 0.02-10 μm; ③ The flow velocity at the surface of the filter membrane is 1-6 m / s; ④ The material of the filter membrane includes one or more of aluminum oxide, zirconium dioxide, titanium dioxide, stainless steel, alloy and silicon carbide; or, the material of the filter membrane includes one or more of polysulfone, polyethersulfone, polyvinylidene fluoride, polyvinyl chloride, polyethylene and polypropylene. And / or, the concentrating membrane in the membrane concentration system satisfies one or more of the following conditions: ① The concentration membrane has a sodium chloride rejection rate of >95%; ②The concentration membrane includes a reverse osmosis membrane; ③ The material of the concentration membrane includes one or more of the following: polysulfone, polyethersulfone, polyvinylidene fluoride, polyvinyl chloride, polyethylene, polyamide, polypropylene, polyacrylonitrile, cellulose acetate, piperazineamide, propylene-alkyl polyamide, condensed urea, furfuryl alcohol, trihydroxyethyl isocyanate, m-phenylenediamine, and pyromellitic trimethylolpropionate. ④ The concentrated membrane can be one of the following types: spiral wound, tubular, capillary, or plate.

13. The method for resource utilization of shift-conversion condensate as described in any one of claims 1-12, characterized in that, The processing system used in the resource utilization method of the shift condensate includes a decarbonization unit and an oxidation reaction unit connected in sequence. The decarbonization device is used to mix the shift condensate with sulfuric acid and perform decarbonization treatment to form a crude ammonium sulfate solution; The oxidation reaction device is used to remove sulfur ions from the crude ammonium sulfate solution and obtain a refined ammonium sulfate solution.

14. The method for resource utilization of shift-conversion condensate as described in claim 13, characterized in that, The processing system further includes a filtration device, a concentration device, and a crystallization device connected in sequence. The inlet of the filtration device is connected to the outlet of the oxidation reaction device for separating a clear liquid containing ammonium sulfate and a slurry containing catalyst. The inlet of the concentration device is connected to the clear liquid outlet of the filtration device. The concentration device includes a product water outlet and a concentrated ammonium sulfate outlet, and the concentrated ammonium sulfate outlet is connected to the inlet of the crystallization device. The crystallization device includes a condensate outlet and a solid ammonium sulfate outlet. And / or, the slurry outlet of the filtration device is connected to the oxidation reaction device for recycling the catalyst slurry back into the oxidation reaction device; And / or, the slurry outlet of the filter device is also connected to the feed inlet of the filter device; And / or, the oxidation reaction apparatus further includes a catalyst inlet and an oxidant inlet; And / or, the decarbonization device further includes a sulfuric acid inlet, a shift condensate inlet, a non-condensable gas outlet, and an air inlet; the air inlet is located at the bottom or lower part of the decarbonization device.

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