Process system and method for preparing ammonium sulfate by wet oxidation of desulfurization waste liquid

Abstract

The invention provides a process system for preparing ammonium sulfate by wet oxidation of desulfurization waste liquid. The process system comprises a first-stage pressure pump, a second-stage pressure pump and a third-stage pressure pump, the raw material heater is connected with the primary pressure pump; the primary reaction tower is connected with the raw material heater through a first pipeline; the first pipeline is also connected with an air / oxygen compression device; the second-stage pressure pump is connected with the first-stage reaction tower; the reaction liquid heat exchange device is connected with the secondary pressure pump; the second-stage reaction tower is connected with the reaction liquid heat exchange device through a second pipeline; the second pipeline is also connected with an oxygen / air compression device; and the oxidation liquid cooling device is connected with the secondary reaction tower. The desulfurization waste liquid is changed into a single component from multiple components by adopting a wet oxidation method, secondary salt components and elemental sulfur in the desulfurization waste liquid are gradually oxidized by adopting a two-stage oxidation mode to obtain an ammonium sulfate single component, the ammonium sulfate single component can be directly sent to an ammonium sulfate unit to uniformly produce an ammonium sulfate product, and the whole process system is safer and more stable.

Description

Technical Field

[0001] The invention belongs to the technical field of desulfurization waste liquid treatment, and relates to a process system for preparing ammonium sulfate by wet oxidation of desulfurization waste liquid and a method for preparing ammonium sulfate by wet oxidation of desulfurization waste liquid. Background Art

[0002] During the production process of the chemical production workshop of the coking plant, when the coal gas desulfurization and decyanation system using NH3 as the alkaline source is in operation, secondary salts such as ammonium thiosulfate and ammonium thiocyanate will be generated in the desulfurization liquid, which directly affects the desulfurization and decyanation efficiency. At present, there are many processes at home and abroad to treat mixed salts in desulfurization waste liquid. With the introduction of national policies, enterprises are required to achieve ultra-low emissions during the production process, so the requirements for process facilities are getting higher and higher. The desulfurization liquid treatment process currently developed concentrates the desulfurization salt solution to a saturated state through evaporation and concentration, and separates it according to the different solubility of each component. The mixed salt or single salt separated by this process often needs to be further purified to obtain the target product.

[0003] The current desulfurization waste liquid treatment technology is not ideal. The purity of the secondary salts generated by evaporation concentration or membrane separation technology is not high and often requires further separation and purification.

[0004] Therefore, how to design and develop a more suitable treatment process to solve the above-mentioned problems existing in the existing desulfurization waste liquid treatment process has become one of the urgent issues to be solved by many front-line researchers in the industry. Summary of the invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a process system for preparing ammonium sulfate by wet oxidation of desulfurized waste liquid and a method for preparing ammonium sulfate by wet oxidation of desulfurized waste liquid. The process system provided by the present invention adopts a wet oxidation method to oxidize different secondary salts and elemental sulfur in the desulfurized waste liquid into a single component of ammonium sulfate through two-stage oxidation, which can be directly sent to the ammonium sulfate unit to uniformly produce ammonium sulfate products.

[0006] The present invention provides a process system for preparing ammonium sulfate by wet oxidation of desulfurization waste liquid, comprising:

[0007] First stage booster pump;

[0008] a raw material heater connected to the primary pressure pump;

[0009] a primary reaction tower connected to the raw material heater via a first pipeline;

[0010] The first pipeline is also connected to an air / oxygen compression device;

[0011] A secondary pressure pump connected to the primary reaction tower;

[0012] A reaction liquid heat exchange device connected to the secondary pressure pump;

[0013] a secondary reaction tower connected to the reaction liquid heat exchange device via a second pipeline;

[0014] The second pipeline is also connected to an oxygen / air compression device;

[0015] An oxidizing liquid cooling device connected to the secondary reaction tower.

[0016] Preferably, the inlet of the primary booster pump is connected to an ammonia water source and a desulfurization waste liquid pipeline;

[0017] The outlet of the primary pressure pump is connected to the inlet of the raw material heater;

[0018] The outlet of the raw material heater is connected to the inlet of the primary reaction tower through a first pipeline;

[0019] The outlet of the air / oxygen compression device is connected to the first pipeline;

[0020] The inlet of the primary reaction tower is arranged at the lower part of the primary reaction tower.

[0021] Preferably, the outlet of the primary reaction tower is arranged at the upper part of the primary reaction tower;

[0022] A first-stage reaction tower tail gas outlet is provided at the top of the first-stage reaction tower;

[0023] The tail gas outlet of the primary reaction tower is connected to the inlet of the primary tail gas cooler;

[0024] The process system also includes a primary gas-liquid separator;

[0025] The outlet of the primary tail gas cooler is connected to the inlet of the primary gas-liquid separator.

[0026] Preferably, a gas-liquid separation device is provided in the upper part of the reaction tower;

[0027] The outlet of the primary reaction tower is connected to the inlet of the secondary pressure pump;

[0028] The outlet of the secondary pressure pump is connected to the cold source inlet of the reaction liquid heat exchange device;

[0029] The cold source outlet of the reaction liquid heat exchange device is connected to the inlet of the secondary reaction tower through a second pipeline;

[0030] The outlet of the oxygen / air compression device is connected to the second pipeline.

[0031] Preferably, the inlet of the secondary reaction tower is arranged at the lower part of the secondary reaction tower;

[0032] The outlet of the secondary reaction tower is arranged at the upper part of the secondary reaction tower;

[0033] The outlet of the secondary reaction tower is connected to the inlet of the oxidizing liquid cooling device;

[0034] A secondary reaction tower tail gas outlet is provided at the top of the secondary reaction tower;

[0035] The tail gas outlet of the secondary reaction tower is connected to the inlet of the primary tail gas cooler.

[0036] Preferably, the tail gas outlet of the secondary reaction tower is connected to the heat source inlet of the reaction liquid heat exchange device;

[0037] The process system also includes a secondary gas-liquid separator;

[0038] The heat source outlet of the reaction liquid heat exchange device is connected to the inlet of the secondary gas-liquid separator;

[0039] The tail gas outlet of the primary gas-liquid separator and the tail gas outlet of the secondary gas-liquid separator are connected to a desulfurization tail gas treatment system;

[0040] The condensate outlet of the primary gas-liquid separator and the condensate outlet of the secondary gas-liquid separator are connected to the reaction liquid tank of the desulfurization unit.

[0041] The present invention provides a method for preparing ammonium sulfate by wet oxidation of desulfurization waste liquid, comprising the following steps:

[0042] 1) The mixed solution of the desulfurization waste liquid and the pH value regulator after being pressurized and heated is mixed with pressurized air / oxygen, and then enters the primary reaction tower for reaction to obtain a reaction solution;

[0043] 2) The reaction solution obtained in the above step is pressurized and heat-exchanged again, mixed with pressurized oxygen / air, and then enters a secondary reaction tower for oxidation reaction to obtain an ammonium sulfate solution.

[0044] Preferably, the desulfurization waste liquid is obtained from the desulfurization and decyanation process of coke oven gas;

[0045] The desulfurization waste liquid includes, by mass content: 0.1% to 15% of ammonium thiosulfate, 0.01% to 1% of ammonium polysulfide, 0.1% to 12% of ammonium thiocyanate, 0.01% to 2% of ammonium sulfate, 0.01% to 0.7% of free ammonia and other trace amounts;

[0046] The pressurized pressure is 2.0-3.0 MPa;

[0047] The heating temperature is 200-210°C;

[0048] The pH adjuster includes concentrated ammonia water.

[0049] Preferably, the pH value of the mixed solution is 10 to 12;

[0050] The pressure of the pressurized air / oxygen is 2.0-3.0 MPa;

[0051] The flow ratio of the pressurized air / oxygen to the mixed liquid is (150-300) m 3 Pressurized air: 1m 3 Mixed liquid;

[0052] The reaction temperature is 170-190°C;

[0053] The reaction pressure is 1.0-2.0 MPa.

[0054] Preferably, the re-pressurization pressure is 7.0-9.0 MPa;

[0055] The flow ratio of the pressurized oxygen / air to the reaction liquid is (30-60) m 3 Pressurized oxygen: 1m 3 Reaction solution;

[0056] The heat exchange is specifically heat exchange between the reaction liquid and the tail gas of the secondary reaction tower;

[0057] The temperature of the oxidation reaction is 260-270°C;

[0058] The pressure of the oxidation reaction is 6.0-7.0 MPa.

[0059] The present invention provides a process system for preparing ammonium sulfate by wet oxidation of desulfurized waste liquid, comprising: a primary booster pump; a raw material heater connected to the primary booster pump; a primary reaction tower connected to the raw material heater through a first pipeline; an air / oxygen compression device is also connected to the first pipeline; a secondary booster pump connected to the primary reaction tower; a reaction liquid heat exchange device connected to the secondary booster pump; a secondary reaction tower connected to the reaction liquid heat exchange device through a second pipeline; an oxygen / air compression device is also connected to the second pipeline; an oxidation liquid cooling device is connected to the secondary reaction tower. Compared with the prior art, the present invention creatively designs a process system for preparing ammonium sulfate by wet oxidation of desulfurized waste liquid with a specific structure and connection relationship, and at the same time, the present invention also provides a corresponding method for preparing ammonium sulfate by wet oxidation of desulfurized waste liquid. The present invention particularly adopts a wet oxidation method to convert the desulfurization waste liquid from multiple components into a single component, and adopts two-stage oxidation to make the entire process safer and more stable. In addition, the oxidation reaction tower of the present invention is made of composite materials, which is resistant to high temperature, high pressure and corrosion, and has a unique internal structure. A mixing facility is arranged at the lower part of the oxidation reaction tower to fully mix the gas and liquid and improve the reaction conversion rate. A cyclone-type gas-liquid separator is arranged in the middle and upper part to separate the reacted gas from the oxidized liquid and reduce the liquid carried by the gas out of the tower. The gas is discharged from the top of the tower, and the liquid is discharged through the upper part of the first layer of the tower plate of the reaction tower through liquid level control; the oxidation reaction of the desulfurization liquid is more complete and the oxidation efficiency is higher.

[0060] The present invention adopts a wet oxidation method to convert the desulfurization waste liquid from multiple components into a single component, and adopts a two-stage oxidation method to gradually oxidize the secondary salt components and elemental sulfur in the desulfurization waste liquid to obtain a single component of ammonium sulfate, which can be directly sent to the ammonium sulfate unit to uniformly produce ammonium sulfate products, and the entire process is safer and more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 The present invention provides a schematic diagram of the process flow of the process system for producing ammonium sulfate through wet oxidation of desulfurization waste liquid. DETAILED DESCRIPTION

[0062] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the patent claims of the present invention.

[0063] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0064] There is no particular limitation on the purity of all raw materials in the present invention. The present invention preferably uses industrial purity or conventional purity required in the field of post-treatment of desulfurization waste liquid.

[0065] All noun expressions and abbreviations in the present invention are conventional noun expressions and abbreviations in the field. Each noun expression and abbreviation is clear and unambiguous in its relevant application field. Those skilled in the art can clearly, accurately and uniquely understand them based on the noun expressions and abbreviations.

[0066] Booster pump: A device used to increase the pressure of a liquid.

[0067] Air compressor: A device used to increase the total pressure of air.

[0068] Reaction tower: A tower used for chemical reactions of raw material mixtures.

[0069] Gas-liquid separator: a device used to separate gas-liquid two-phase mixed flow into gas phase and liquid phase flow.

[0070] The present invention provides a process system and method for preparing ammonium sulfate by wet oxidation of desulfurization waste liquid. The desulfurization waste liquid refers to a process in which ammonia is used as an alkali source in the desulfurization and decyanation process of coke oven gas. Under the action of a catalyst, hydrogen sulfide and hydrogen cyanide in the gas are absorbed by the desulfurization liquid, and part of them are oxidized to generate secondary salts such as ammonium thiosulfate, ammonium polysulfides and ammonium thiocyanate. The content of secondary salts in the desulfurization liquid affects the desulfurization and decyanation effects, so it is necessary to regularly separate the mixed salts in the desulfurization liquid.

[0071] The present invention provides a process system for preparing ammonium sulfate by wet oxidation of desulfurization waste liquid, comprising:

[0072] First stage booster pump;

[0073] a raw material heater connected to the primary pressure pump;

[0074] a primary reaction tower connected to the raw material heater via a first pipeline;

[0075] The first pipeline is also connected to an air / oxygen compression device;

[0076] A secondary pressure pump connected to the primary reaction tower;

[0077] A reaction liquid heat exchange device connected to the secondary pressure pump;

[0078] a secondary reaction tower connected to the reaction liquid heat exchange device via a second pipeline;

[0079] The second pipeline is also connected to an oxygen / air compression device;

[0080] An oxidizing liquid cooling device connected to the secondary reaction tower.

[0081] In the present invention, the inlet of the primary booster pump is preferably connected to an ammonia water source and a desulfurization waste liquid pipeline.

[0082] In the present invention, the outlet of the primary pressure pump is preferably connected to the inlet of the raw material heater.

[0083] In the present invention, the outlet of the raw material heater is preferably connected to the inlet of the primary reaction tower through a first pipeline.

[0084] In the present invention, the outlet of the air / oxygen compression device is preferably connected to the first pipeline. The air / oxygen compression device is specifically an air and / or oxygen compression device.

[0085] In the present invention, the inlet of the primary reaction tower is preferably arranged at the lower part of the primary reaction tower.

[0086] In the present invention, the outlet of the primary reaction tower is preferably arranged at the upper part of the primary reaction tower.

[0087] In the present invention, a first-stage reaction tower tail gas outlet is preferably provided at the top of the first-stage reaction tower.

[0088] In the present invention, the tail gas outlet of the primary reaction tower is preferably connected to the inlet of the primary tail gas cooler.

[0089] In the present invention, the process system preferably further comprises a primary gas-liquid separator.

[0090] In the present invention, the outlet of the primary tail gas cooler is preferably connected to the inlet of the primary gas-liquid separator.

[0091] In the present invention, a gas-liquid separation device is preferably provided at the upper part of the primary reaction tower, and more preferably a cyclone type gas-liquid separator, which can be provided above the first layer of trays so that the separated liquid phase enters the outlet of the primary reaction tower.

[0092] In the present invention, the outlet of the primary reaction tower is preferably connected to the inlet of the secondary pressure pump.

[0093] In the present invention, the outlet of the secondary pressure pump is preferably connected to the cold source inlet of the reaction liquid heat exchange device.

[0094] In the present invention, the cold source outlet of the reaction liquid heat exchange device is preferably connected to the inlet of the secondary reaction tower through a second pipeline.

[0095] In the present invention, the outlet of the oxygen / air compression device is preferably connected to the second pipeline. The oxygen / air compression device is specifically an oxygen and / or air compression device.

[0096] In the present invention, the inlet of the secondary reaction tower is preferably arranged at the lower part of the secondary reaction tower.

[0097] In the present invention, the outlet of the secondary reaction tower is preferably arranged at the upper part of the secondary reaction tower.

[0098] In the present invention, a gas-liquid separation device is preferably provided at the upper part of the secondary reaction tower, and more preferably a cyclone type gas-liquid separator, which can be provided above the first tray so that the separated liquid phase enters the outlet of the secondary reaction tower.

[0099] In the present invention, the outlet of the secondary reaction tower is preferably connected to the inlet of the oxidizing liquid cooling device.

[0100] In the present invention, a secondary reaction tower tail gas outlet is preferably provided at the top of the secondary reaction tower.

[0101] In the present invention, the tail gas outlet of the secondary reaction tower is preferably connected to the inlet of the primary tail gas cooler.

[0102] In the present invention, the tail gas outlet of the secondary reaction tower is preferably connected to the heat source inlet of the reaction liquid heat exchange device.

[0103] In the present invention, the process system preferably further comprises a secondary gas-liquid separator.

[0104] In the present invention, the heat source outlet of the reaction liquid heat exchange device is preferably connected to the inlet of the secondary gas-liquid separator.

[0105] In the present invention, the tail gas outlet of the primary gas-liquid separator is preferably connected to a desulfurization tail gas treatment system together with the tail gas outlet of the secondary gas-liquid separator.

[0106] In the present invention, the condensate outlet of the primary gas-liquid separator is preferably connected to the condensate outlet of the secondary gas-liquid separator to the reaction liquid tank of the desulfurization unit.

[0107] The present invention provides a method for preparing ammonium sulfate by wet oxidation of desulfurization waste liquid, comprising the following steps:

[0108] 1) The mixed solution of the desulfurization waste liquid and the pH value regulator after being pressurized and heated is mixed with pressurized air / oxygen, and then enters the primary reaction tower for reaction to obtain a reaction solution;

[0109] 2) The reaction solution obtained in the above step is pressurized and heat-exchanged again, mixed with pressurized oxygen / air, and then enters a secondary reaction tower for oxidation reaction to obtain an ammonium sulfate solution.

[0110] The present invention firstly mixes the pressurized and heated mixed solution of desulfurization waste liquid and pH value regulator with pressurized air / oxygen, and then enters a primary reaction tower for reaction to obtain a reaction solution.

[0111] In the present invention, the desulfurization waste liquid is preferably obtained in the process of desulfurization and decyanation of coke oven gas.

[0112] In the present invention, the desulfurization waste liquid preferably includes, by mass content: 0.1% to 15% of ammonium thiosulfate, 0.01% to 1% of ammonium polysulfides, 0.1% to 12% of ammonium thiocyanate, 0.01% to 2% of ammonium sulfate, 0.01% to 0.7% of free ammonia and other trace amounts. Among them, ammonium thiosulfate can be 0.5% to 13%, or 1% to 10%, or 3% to 8%. Ammonium polysulfides can be 0.05% to 0.8%, or 0.1% to 0.6%, or 0.2% to 0.5%. Ammonium thiocyanate can be 0.5% to 10%, or 1% to 8%, or 3% to 6%. Free ammonia can be 0.05% to 0.6%, or 0.1% to 0.5%, or 0.2% to 0.4%.

[0113] In the present invention, the pressurized pressure is preferably 2.0 to 3.0 MPa, more preferably 2.2 to 2.8 MPa, and even more preferably 2.4 to 2.6 MPa.

[0114] In the present invention, the heating temperature is preferably 200-210°C, more preferably 202-208°C, and more preferably 204-206°C.

[0115] In the present invention, the pH adjuster preferably includes concentrated aqueous ammonia.

[0116] In the present invention, the pH value of the mixed solution is preferably 10-12, more preferably 10.4-11.6, and more preferably 10.8-11.2.

[0117] In the present invention, the pressure of the pressurized air / oxygen gas is preferably 2.0 to 3.0 MPa, more preferably 2.2 to 2.8 MPa, and even more preferably 2.4 to 2.6 MPa.

[0118] In the present invention, the flow ratio of the pressurized air / oxygen to the mixed liquid is preferably (150-300) m 3 Pressurized air: 1m 3 Mixed liquid, more preferably (180 ~ 270) m 3 Compressed air: 1m 3 Mixed liquid, more preferably (210 ~ 240) m 3 Pressurized air: 1m 3 Mixed liquid. Specifically,

[0119] In this step, if pressurized oxygen is used, its flow rate ratio is preferably (30-60) m 3 Pressurized oxygen: 1m 3 Mixed liquid.

[0120] In the present invention, the reaction temperature is preferably 170-190°C, more preferably 174-186°C, and more preferably 178-182°C.

[0121] In the present invention, the reaction pressure is preferably 1.0 to 2.0 MPa, more preferably 1.2 to 1.8 MPa, and more preferably 1.4 to 1.6 MPa.

[0122] In the present invention, the reaction liquid obtained in the above steps is finally pressurized and heat-exchanged again, mixed with pressurized oxygen / air in a pipeline, and then enters a secondary reaction tower for oxidation reaction to obtain an ammonium sulfate solution.

[0123] In the present invention, the re-pressurization pressure is preferably 7.0 to 9.0 MPa, more preferably 7.4 to 8.6 MPa, and even more preferably 7.8 to 8.2 MPa.

[0124] In the present invention, the flow ratio of the pressurized oxygen / air to the reaction liquid is preferably (30-60) m 3 Pressurized oxygen: 1m 3 The reaction liquid is more preferably (35 to 55) m 3 Pressurized oxygen: 1m 3 The reaction liquid is more preferably (40 to 50) m 3 Pressurized oxygen: 1m 3 Specifically, in this step, if pressurized air is used, its flow rate ratio is preferably (150-300) m 3 Pressurized air: 1m 3 Reaction liquid.

[0125] In the present invention, the heat exchange is preferably carried out between the reaction liquid and the tail gas of the secondary reaction tower.

[0126] In the present invention, the temperature of the oxidation reaction is preferably 260-270°C, more preferably 262-268°C, and more preferably 264-266°C.

[0127] In the present invention, the pressure of the oxidation reaction is preferably 6.0 to 7.0 MPa, more preferably 6.2 to 6.8 MPa, and more preferably 6.4 to 6.6 MPa.

[0128] The present invention is a complete and detailed overall technical solution, which better ensures the stability and continuity of the operation of the process system for preparing ammonium sulfate by wet oxidation of desulfurized waste liquid, and further improves the reaction effect of preparing ammonium sulfate by wet oxidation of desulfurized waste liquid. The above-mentioned process system for preparing ammonium sulfate by wet oxidation of desulfurized waste liquid and a method for preparing ammonium sulfate by wet oxidation of desulfurized waste liquid may specifically include the following contents:

[0129] The present invention provides a process system for preparing ammonium sulfate by wet oxidation of desulfurization waste liquid, comprising raw material mixing, a primary pressure pump, a secondary pressure pump, a primary oxidation tower, a secondary oxidation tower, an air compressor unit, an oxygen compressor unit, a raw material heater, a reaction liquid heat exchanger, an oxidation liquid cooler, a tail gas cooler, a primary gas-liquid separator, a secondary separator, and the like.

[0130] The specific process includes: the desulfurization waste liquid is filtered and purified before entering the device, concentrated ammonia water is added to adjust the pH value of the raw material, and then it is sent to the raw material heater for heating by a first-level pressure pump, and after heating, it is mixed with the pressurized air from the air compressor and enters the first-level reaction tower for reaction, the temperature is controlled at 170-190°C, and the pressure is controlled at 1.0-2.0MPa. The reaction liquid coming out of the first-level reaction tower is pressurized by a second-level pressure pump and enters the raw material liquid heat exchanger for heat exchange with the tail gas from the top of the second-level reaction tower, and is mixed with oxygen pressurized by an oxygen compressor and enters the second-level oxidation reaction tower for reaction, the temperature is controlled at 260-270°C, and the pressure is controlled at 6.0-7.0MPa. The oxidized liquid coming out of the second-level oxidation reaction tower is cooled to obtain a single-component ammonium sulfate solution, which is sent to the ammonium sulfate unit as a raw material to produce ammonium sulfate.

[0131] See also Figure 1 , Figure 1 The present invention provides a schematic diagram of the process flow of the process system for preparing ammonium sulfate by wet oxidation of desulfurized waste liquid. In particular, 1-a primary pressure pump; 2-a raw material heater; 3-an air compressor unit; 4-a primary reaction tower; 5-a secondary pressure pump; 6-a reaction liquid heat exchanger; 7-an oxygen compressor unit; 8-a secondary reaction tower; 9-an oxidation liquid cooler; 10-a primary gas-liquid separator; 11-a primary tail gas cooler; 12-a secondary gas-liquid separator.

[0132] Further specific steps:

[0133] Step 1: The desulfurization waste liquid from the desulfurization unit is filtered and purified, and then mixed evenly with concentrated ammonia water, and the pH value of the raw material is adjusted to be alkaline;

[0134] Step 2: Enter the first-stage pressure pump (Part No. 1), and then be pressurized by the first-stage pressure pump (Part No. 1) and sent to the material heater (Part No. 2) for heating;

[0135] Step 3: After the raw material liquid is heated, it is mixed with the compressed air from the air compressor unit (Part No. 3) and enters the primary reaction tower (Part No. 4). The raw material liquid undergoes oxidation reaction with oxygen in the primary reaction tower (Part No. 4). The temperature is controlled at 170-190°C and the pressure is controlled at 1.0-2.0MPa.

[0136] Step 4: The reaction liquid comes out of the primary reaction tower (Part No. 4) and is further pressurized by the secondary pressure pump (Part No. 5) and sent to the reaction liquid heat exchanger (Part No. 6) to exchange heat with the tail gas from the secondary reaction tower (Part No. 8), and the temperature of the reaction liquid increases;

[0137] Step 5: The tail gas from the top of the primary reaction tower (Part No. 4) is cooled by the primary tail gas cooler (Part No. 11) and then enters the primary gas-liquid separator (Part No. 10). The tail gas from the gas-liquid separator (Part No. 10) is sent to the desulfurization tail gas treatment system, and the condensate is sent to the desulfurization unit reaction liquid tank;

[0138] Step 6: The heated reaction liquid is mixed with the pressurized oxygen from the oxygen compressor unit (Part No. 7), and then enters the secondary reaction tower (Part No. 8), where the reaction liquid and oxygen undergo an oxidation reaction, with the temperature controlled at 260-270°C and the pressure controlled at 6.0-7.0MPa;

[0139] Step 7: The oxidizing liquid coming out of the secondary reaction tower (item 8) is cooled by an oxidizing liquid cooler (item 9) to obtain a single-component ammonium sulfate solution.

[0140] Step 8: The tail gas coming out of the top of the secondary reaction tower (Part No. 8) is cooled by the reaction liquid heat exchanger (Part No. 6) and then enters the secondary gas-liquid separator (Part No. 12). The tail gas coming out of the secondary gas-liquid separator (Part No. 12) is sent to the desulfurization tail gas treatment system together with the tail gas separated by the primary gas-liquid separator, and the condensate is sent to the desulfurization unit reaction liquid tank.

[0141] The above content of the present invention provides a process system for wet oxidation of desulfurized waste liquid to prepare ammonium sulfate and a method for wet oxidation of desulfurized waste liquid to prepare ammonium sulfate. The present invention designs a process system for wet oxidation of desulfurized waste liquid to prepare ammonium sulfate with a specific structure and connection relationship. At the same time, the present invention also provides a corresponding method for wet oxidation of desulfurized waste liquid to prepare ammonium sulfate. The present invention particularly adopts a wet oxidation method to convert desulfurized waste liquid from multiple components into a single component, and adopts a two-stage oxidation to make the entire process safer and more stable. In addition, the oxidation reaction tower of the present invention is made of composite materials, which is resistant to high temperature, high pressure, and corrosion. The interior adopts a unique structure, and a mixing facility is arranged at the lower part of the oxidation reaction tower to fully mix the gas and liquid to improve the reaction conversion rate. A cyclone-type gas-liquid separator is arranged in the middle and upper part to separate the reacted gas from the oxidized liquid, reduce the liquid carried by the gas out of the tower, and the gas is discharged from the top of the tower. The liquid is discharged through the upper part of the first layer of the tower plate of the reaction tower through liquid level control; the oxidation reaction of the desulfurized liquid is more complete and the oxidation efficiency is higher.

[0142] The present invention adopts a wet oxidation method to convert the desulfurization waste liquid from multiple components into a single component, and adopts a two-stage oxidation method to gradually oxidize the secondary salt components and elemental sulfur in the desulfurization waste liquid to obtain a single component of ammonium sulfate, which can be directly sent to the ammonium sulfate unit to uniformly produce ammonium sulfate products, and the entire process is safer and more stable.

[0143] In order to further illustrate the present invention, a process system for preparing ammonium sulfate by wet oxidation of desulfurized waste liquid and a method for preparing ammonium sulfate by wet oxidation of desulfurized waste liquid provided by the present invention are described in detail below in combination with embodiments. However, it should be understood that these embodiments are implemented on the premise of the technical scheme of the present invention, and detailed implementation methods and specific operating processes are given only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention, and the protection scope of the present invention is not limited to the following embodiments.

[0144] Example 1

[0145] Process system for wet oxidation of desulfurization wastewater to produce ammonium sulfate Figure 1 shown.

[0146] The desulfurization waste liquid from the desulfurization unit of the coking plant was taken, and the clear liquid was taken through a filtration separation system. After testing, the main components included: 8.1% ammonium thiosulfate, 11.5% ammonium thiocyanate, 1.4% ammonium sulfate, 0.67% free ammonia and others (including ammonium bisulfite, ammonium sulfide was not detected).

[0147] Step 1: Add 20% concentrated ammonia water and desalted water to the desulfurization waste liquid from the filtration separation system and adjust the pH value to 12.

[0148] Step 2: The desulfurized waste liquid is transported to the feed heater (Part 2) through the primary booster pump (Part 1) and heated to about 200°C. It is then mixed with the compressed air from the air compressor unit (Part 3) and enters the primary reaction tower (Part 4). The temperature of the top of the primary reaction tower (Part 4) is controlled at ~180°C and the pressure is controlled at ~1.5MPa.

[0149] Step 3: The reaction liquid comes out of the primary reaction tower (Part No. 4) and is further pressurized by the secondary pressure pump (Part No. 5) and sent to the reaction liquid heat exchanger (Part No. 6) to exchange heat with the tail gas from the secondary reaction tower (Part No. 8). The temperature is controlled at about 250°C, mixed with the pressurized oxygen from the oxygen compressor unit (Part No. 7), and then enters the secondary reaction tower (Part No. 8). The temperature at the top of the secondary reaction tower is controlled at ~260°C and the pressure is controlled at ~6.0MPa.

[0150] Step 4: The tail gas coming out of the top of the primary reaction tower (Part No. 4) is cooled to ~60°C by the primary tail gas cooler (Part No. 11), and then enters the primary gas-liquid separator (Part No. 10). The tail gas coming out of the gas-liquid separator (Part No. 10) is sent to the desulfurization tail gas treatment system, and the condensate is sent to the desulfurization unit reaction liquid tank; the tail gas coming out of the top of the secondary reaction tower (Part No. 8) is cooled to ~60°C by the reaction liquid heat exchanger (Part No. 6), and then enters the secondary gas-liquid separator (Part No. 12). The tail gas coming out of the secondary gas-liquid separator (Part No. 12) is sent to the desulfurization tail gas treatment system together with the tail gas separated by the primary gas-liquid separator, and the condensate is sent to the desulfurization unit reaction liquid tank.

[0151] Step 5: The oxidizing liquid coming out of the secondary reaction tower (item 8) is cooled by an oxidizing liquid cooler (item 9) to obtain an oxidizing liquid.

[0152] Step 6: The reaction liquid after the oxidation reaction in the primary reaction tower is tested, and its composition is: ammonium thiosulfate (trace amount), 5.9% ammonium thiocyanate, 8.5% ammonium sulfate, 2% free ammonia and others and a small amount of solid particles (mainly elemental sulfur).

[0153] The oxidized liquid after the oxidation reaction in the secondary reaction tower was tested, and the composition of the oxidized liquid was: ammonium thiosulfate (not detected), ammonium thiocyanate (trace amount), 29.3% ammonium sulfate, free ammonia and others (trace amounts).

[0154] The results of this embodiment show that after the primary reaction with compressed air, the ammonium thiosulfate in the desulfurization waste liquid is almost completely oxidized into ammonium sulfate and less sulfur particles. After the secondary reaction with oxygen, the sulfur element in the desulfurization liquid is basically completely converted into ammonium sulfate.

[0155] The above is a detailed introduction to a process system for wet oxidation of desulfurized waste liquid to produce ammonium sulfate and a method for wet oxidation of desulfurized waste liquid to produce ammonium sulfate provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enables any technician in the field to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements that are not different from the text of the claims, or if they include equivalent structural elements that are not substantially different from the text of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A process system for preparing ammonium sulfate by wet oxidation of desulfurization waste liquid, characterized in that: include: First stage booster pump; a raw material heater connected to the primary pressure pump; a primary reaction tower connected to the raw material heater via a first pipeline; The first pipeline is also connected to an air / oxygen compression device; A secondary pressure pump connected to the primary reaction tower; A reaction liquid heat exchange device connected to the secondary pressure pump; a secondary reaction tower connected to the reaction liquid heat exchange device via a second pipeline; The second pipeline is also connected to an oxygen / air compression device; An oxidizing liquid cooling device connected to the secondary reaction tower.

2. The process system according to claim 1, characterized in that: The inlet of the primary booster pump is connected to an ammonia water source and a desulfurization waste liquid pipeline; The outlet of the primary pressure pump is connected to the inlet of the raw material heater; The outlet of the raw material heater is connected to the inlet of the primary reaction tower through a first pipeline; The outlet of the air / oxygen compression device is connected to the first pipeline; The inlet of the primary reaction tower is arranged at the lower part of the primary reaction tower.

3. The process system according to claim 1, characterized in that: The outlet of the primary reaction tower is arranged at the upper part of the primary reaction tower; A first-stage reaction tower tail gas outlet is provided at the top of the first-stage reaction tower; The tail gas outlet of the primary reaction tower is connected to the inlet of the primary tail gas cooler; The process system also includes a primary gas-liquid separator; The outlet of the primary tail gas cooler is connected to the inlet of the primary gas-liquid separator.

4. The process system according to claim 1, characterized in that: A gas-liquid separation device is provided at the upper part of the reaction tower; The outlet of the primary reaction tower is connected to the inlet of the secondary pressure pump; The outlet of the secondary pressure pump is connected to the cold source inlet of the reaction liquid heat exchange device; The cold source outlet of the reaction liquid heat exchange device is connected to the inlet of the secondary reaction tower through a second pipeline; The outlet of the oxygen / air compression device is connected to the second pipeline.

5. The process system according to claim 1, characterized in that: The inlet of the secondary reaction tower is arranged at the lower part of the secondary reaction tower; The outlet of the secondary reaction tower is arranged at the upper part of the secondary reaction tower; The outlet of the secondary reaction tower is connected to the inlet of the oxidizing liquid cooling device; A secondary reaction tower tail gas outlet is provided at the top of the secondary reaction tower; The tail gas outlet of the secondary reaction tower is connected to the inlet of the primary tail gas cooler.

6. The process system according to claim 5, characterized in that: The tail gas outlet of the secondary reaction tower is connected to the heat source inlet of the reaction liquid heat exchange device; The process system also includes a secondary gas-liquid separator; The heat source outlet of the reaction liquid heat exchange device is connected to the inlet of the secondary gas-liquid separator; The tail gas outlet of the primary gas-liquid separator and the tail gas outlet of the secondary gas-liquid separator are connected to a desulfurization tail gas treatment system; The condensate outlet of the primary gas-liquid separator and the condensate outlet of the secondary gas-liquid separator are connected to the reaction liquid tank of the desulfurization unit.

7. A method for preparing ammonium sulfate by wet oxidation of desulfurization waste liquid, characterized in that: The following steps are involved: 1) The mixed solution of the desulfurization waste liquid and the pH value regulator after being pressurized and heated is mixed with pressurized air / oxygen, and then enters the primary reaction tower for reaction to obtain a reaction solution; 2) The reaction solution obtained in the above step is pressurized and heat-exchanged again, mixed with pressurized oxygen / air, and then enters a secondary reaction tower for oxidation reaction to obtain an ammonium sulfate solution.

8. The method according to claim 7, characterized in that The desulfurization waste liquid is obtained in the process of desulfurization and decyanation of coke oven gas; The desulfurization waste liquid includes, by mass content: 0.1% to 15% of ammonium thiosulfate, 0.01% to 1% of ammonium polysulfide, 0.1% to 12% of ammonium thiocyanate, 0.01% to 2% of ammonium sulfate, 0.01% to 0.7% of free ammonia and other trace amounts; The pressurized pressure is 2.0-3.0 MPa; The heating temperature is 200-210°C; The pH adjuster includes concentrated ammonia water.

9. The method according to claim 7, characterized in that: The pH value of the mixed solution is 10 to 12; The pressure of the pressurized air / oxygen is 2.0-3.0 MPa; The flow ratio of the pressurized air / oxygen to the mixed liquid is (150-300) m 3 Pressurized air: 1m 3 Mixed liquid; The reaction temperature is 170-190°C; The reaction pressure is 1.0-2.0 MPa.

10. The method according to claim 7, characterized in that The re-pressurization pressure is 7.0-9.0 MPa; The flow ratio of the pressurized oxygen / air to the reaction liquid is (30-60) m 3 Pressurized oxygen: 1m 3 Reaction solution; The heat exchange is specifically heat exchange between the reaction liquid and the tail gas of the secondary reaction tower; The temperature of the oxidation reaction is 260-270°C; The pressure of the oxidation reaction is 6.0-7.0 MPa.

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