A device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia and its application

Abstract

The patent of the present invention relates to a device for producing ammonium sulfate by neutralization and crystallization of caprolactam rearrangement liquid with ammonia and its application, including a DTB neutralization crystallizer, a built-in main condenser is arranged in the body of the DTB neutralization crystallizer, and a tail condenser and a condensation system are arranged outside the body; the main condenser is equipped with a liquid collecting tank, a liquid collecting bucket, a condensate discharge port and a condensate pipeline; the tail condenser is equipped with vacuum facilities and a jet liquid system. The built-in main condenser eliminates the pressure drop of the condensation process on the evaporation vapor side, greatly reduces the amount of evaporation vapor discharged from the top of the neutralization crystallizer, reduces the diameter of the top vapor phase pipe and the difficulty of layout; the tail condenser adopts a jet vacuum condenser with low pressure drop, low temperature difference, fast condensation, and no steam is used for vacuuming; the circulating feed liquid of the neutralization crystallizer or the ammonium sulfate mother liquor in the device is used as the supplementary liquid of the jet liquid, and no wastewater is generated during operation, which is more environmentally friendly; the jet liquid cooler adopts circulating cooling water with large flow and low temperature rise to maintain the stability of the system vacuum.

Description

Technical Field

[0001] The invention relates to the technical field of preparing ammonium sulfate by reacting sulfuric acid with ammonia, in particular to a process device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia and application thereof. Background Art

[0002] At present, most domestic chemical production enterprises and some metallurgical enterprises often use the neutralization crystallization process and select the DTB neutralization crystallizer (draft tube baffle), that is, the draft tube plus baffle evaporation neutralization crystallizer, when treating by-product sulfuric acid or ammonia. It is a double-sleeve draft tube baffle, which is a typical internal circulation crystallizer with high circulation efficiency; the ammonia-containing stream and the sulfuric acid-containing stream are introduced into the DTB neutralization crystallizer together, and the neutralization and crystallization process is realized simultaneously, and the reaction generates ammonium sulfate crystal slurry containing solid ammonium sulfate particles; the neutralization process generates a large amount of heat, which causes a large amount of water in the solution to be vaporized, and the ammonium sulfate solution is concentrated and crystallized; when the ammonium sulfate crystal slurry at the bottom reaches the specified concentration, it is discharged through a pump, and then thickened, centrifuged and dried to finally obtain ammonium sulfate crystal products. Guo Xinxin et al.'s "Resource Treatment of By-product Ammonium Sulfate Crystallization Clear Mother Liquor in MMA Production" [J]. Coal and Chemical Industry, 2019, 42 (3) introduces the application of a continuous ammonium sulfate DTB neutralization crystallizer to treat by-product ammonium sulfate waste liquid in methyl methacrylate production. Chinese patent CN201411372Y discloses a DTB neutralization crystallizer that uses the ammonium sulfate solution produced by the coke oven gas purification project as raw material to produce large-particle ammonium sulfate. The crystallizer optimizes the internal and external circulation channels to increase the internal circulation rate, and uses a bottom stirring method to control the growth of crystals, so that the supersaturation in each part of the crystallizer is low and uniform, and a large-particle ammonium sulfate product is obtained. Chinese patent CN1757599A "A method for producing ammonium sulfate" discloses the use of neutralization crystallization technology to treat Beckmann rearrangement liquid in a caprolactam device, separate caprolactam from the rearrangement liquid and produce ammonium sulfate.

[0003] Wen Jie's "Nuclearization Reaction Crystallization Technology of New Caprolactam Ammonium Sulfate Plant" [J]. Enterprise Technology Development, 2005, 24 (9); Wang Jin's "Comparison of Evaporation Crystallization and Neutralization Crystallization of Ammonium Sulfate in Caprolactam Production" [J]. China Chemical Trade, 2014 (3); both detailed the process technology and parameters of ammonium sulfate neutralization crystallization in caprolactam production. In the production process of caprolactam, most of the supporting ammonium sulfate plants adopt the neutralization crystallization process, which includes DTB neutralization crystallizer, decanter, thickener, centrifuge, dryer and other main equipment; the neutralization reaction of sulfuric acid-containing redistribution liquid and ammonia mostly adopts DTB type neutralization crystallizer with baffle area; the redistribution liquid and gaseous ammonia are respectively introduced into the guide tube through the nozzle on the ring distributor of the crystallizer through ratio adjustment, and an internal circulation channel is formed under the action of the guide tube and the agitator. The ammonium sulfate solution containing crystals is quickly "lifted" to the boiling surface on the upper part of the guide tube, and the water begins to evaporate. The slurry flows from the boiling surface along the outside of the guide tube to the outside of the guide tube. The crystallizer flows downward. In the lower area outside the guide tube, the flow rate is reduced due to the change in the shape of the crystallizer. A part of the suspension returns to the guide tube through the agitator, and the other part flows upward to the baffle area. In this area, due to the density difference, the crystals and amide oil are separated by sedimentation. The amide oil layer containing a small amount of ammonium sulfate solution is sent to the decanter by the amide oil discharge pump for re-stratification. The crystallizer circulation pump extracts part of the slurry containing ammonium sulfate crystals from the middle of the baffle area, first mixes with a part of the condensate on the inlet pipeline of the crystallizer circulation pump, and then mixes with the unsaturated ammonium sulfate mother liquor on the outlet pipeline of the circulation pump, and then returns to the guide tube. When the solid content of ammonium sulfate in the crystallizer reaches the set value, the ammonium sulfate slurry is extracted from the bottom by the crystal slurry discharge pump and sent to the thickener.

[0004] The operating pressure of the DTB neutralization crystallizer is controlled at about 15KPa(A); the evaporated steam discharged from the vapor phase outlet at the top of the neutralization crystallizer enters the surface condenser, is condensed into condensate by circulating cooling water, flows to the condensate tank by gravity and is then pressurized by the condensate pump, a part of the condensate is sent to the ammonia feed pipeline to dissolve and absorb ammonia, a part of the condensate is sent to the crystallizer circulation pump inlet pipeline to dissolve fine crystals, a small part of the condensate is used for flushing various parts, and finally returns to the neutralization crystallizer (101) to balance the evaporated water; the uncondensed steam discharged from the surface condenser is extracted by a steam jet vacuum pump.

[0005] The above-mentioned ammonium sulfate neutralization crystallization device has the following characteristics: 1) The evaporation steam volume of the process device is large, and the evaporation steam temperature is relatively low; 2) The cooling medium required is very large, and only circulating cooling water can be used as the cooling medium; 3) Due to the limitation of the circulating cooling water temperature and the heat transfer temperature difference between the hot and cold sides, in order to ensure the vacuum degree of crystallization evaporation, the vacuum side (evaporation steam) pressure drop must be strictly controlled; 4) The DTB neutralization crystallizer has a large specification, a large surface condenser area, and a thick evaporation steam discharge pipe. Taking an ammonium sulfate unit with an annual output of 150,000 tons built in conjunction with a caprolactam unit as an example, the evaporation steam volume per hour is about 17 tons, the top operating pressure of the DTB neutralization crystallizer is 15-20KPa (A), the neutralization crystallizer operating temperature is 55-65°C, and the circulating cooling water consumption is about 1600m 3 / h; the diameter of the neutralization crystallizer is about 6.9 meters; the diameter of the evaporation steam outlet pipe from the neutralization crystallizer is about 1.2 meters; two heat exchangers with a heat exchange area of ​​480m 2 Shell and tube surface condenser.

[0006] The above-mentioned ammonium sulfate neutralization crystallization device still has the following optimization potential: 1) The diameter of the evaporation vapor phase discharge pipe at the top of the crystallizer is large, the pipeline cost is high, and the piping difficulty is great; 2) The use of an external, partition-type surface condenser has a large pressure drop on the vacuum side; 3) The main body of the surface condenser is made of stainless steel, the equipment specifications are large, the layout occupies a large area, and the comprehensive investment is high; 4) The use of a steam jet vacuum pump has the advantages of simple structure, reliable operation, and long service life, but has low efficiency and large steam consumption. Circulating cooling water is also required to condense its power steam, which increases energy consumption; 5) After the power steam is condensed, it is mixed with the process condensate and then enters the process system, which increases the water volume of the process system and increases the sewage treatment and discharge volume.

[0007] Chinese patent CN103936032B discloses a method for producing a large-particle ammonium sulfate product, which adopts a neutralization crystallization process and equipment, and produces large-particle ammonium sulfate by controlling the mass percentage of sulfuric acid in the DTB neutralization crystallizer. Chinese patent CN211798914U discloses an ammonium sulfate crystallizer, which achieves a more complete neutralization reaction in the guide tube and a more uniform temperature distribution by adjusting the installation position of the rearrangement nozzle, and reduces the organic droplets entrained during the water evaporation process. Chinese patent CN111530119A discloses a series ammonium sulfate crystallization method and device, which adopts two series-connected crystallizers and a two-effect vacuum crystallization process, fully utilizes the heat of dissolution of gas ammonia, the heat of neutralization of sulfuric acid and ammonia, and uses the first-effect evaporation steam as a heat source, reducing the consumption of circulating cooling water and increasing the proportion of large-particle ammonium sulfate. Existing industrial devices and public technologies all use external, shell-and-tube surface condensers, and all use steam jet vacuum pumps, and do not involve the optimization and improvement of condensation methods and vacuum facilities.

[0008] In the vacuum condensation process, the pressure drop on the vacuum side is a very important factor, which affects the design of the vacuum condenser, the condensation effect, the vacuum degree and the suction capacity. The selection of processes, equipment and pipelines with low pressure drop is conducive to the condensation of evaporating steam and reduces vacuum power consumption.

[0009] Direct contact condensers have the characteristics of large processing capacity, small pressure drop, small required heat transfer temperature difference, large two-phase contact area and high heat transfer efficiency. They are suitable for occasions where the process allows the mixing of two fluids and are often used for gas cooling or water vapor condensation. The main types of direct contact condensers are liquid column condensers, liquid film condensers, packed tower condensers and jet condensers. Among them, types 1 to 3 are countercurrent flows of the condensed vapor phase and the cooling medium in the device, while the jet condenser belongs to parallel flow condensation. The vapor phase is directly mixed with the cooling medium sprayed from the nozzle and condensed. The entrained non-condensable gas flows out from the lower discharge pipe. The pressure drop of the vapor phase condensation process is extremely small, which is more suitable for use in vacuum occasions. Kang Chuanjiang's "Design and Application of Water Jet Condensers" [J]. Chemical Engineering Design, 2001, 11(3) has a detailed introduction to it.

[0010] Liquid jet vacuum pumps have been widely used in the chemical industry. Their principle and structure are basically the same as those of steam jet vacuum pumps. They are composed of three main parts: nozzle, suction chamber and diffuser. They use the mutual conversion and transfer of energy during fluid flow to achieve air extraction. Working fluid with a certain pressure is ejected from a group of nozzles at high speed and ejected toward the throat in a cone shape. Its static pressure energy is converted into kinetic energy, causing a local vacuum at the nozzle outlet. The pumped fluid is drawn from the equipment into the suction chamber, and then mixed with the working fluid and carried away by the high-speed jet. The kinetic energy of the mixed fluid is converted into pressure energy by the diffuser, and the gas-liquid mixture is discharged from the jet pump outlet. The gas-liquid mixture goes to the gas-liquid separator to separate the non-condensable gas. The working fluid is pressurized by the pump and goes to the cooler. The working fluid is cooled to the required temperature and returned to the nozzle of the liquid jet pump. Liquid jet vacuum pumps are suitable for pumping condensable gas, dust, and granular media. They are suitable for occasions where the working fluid and the process system are compatible. It is more advantageous to use water as the working fluid. Compared with steam jet vacuum pumps, liquid jet vacuum pumps have the following advantages: 1) They do not use water vapor as power, so they are relatively efficient and have low energy consumption; 2) They do not require a large condenser and are easy to install; 3) They do not generate additional wastewater; 4) The vacuum degree is easy to adjust; and 5) The noise is very low.

[0011] A complete jet condenser needs to be equipped with a jet liquid tank, a jet liquid pump, a jet liquid cooler, instruments, pipelines, etc.; a complete liquid jet vacuum pump includes a jet liquid tank, a jet liquid pump, a jet liquid cooler, instruments, pipelines, etc.; the equipment for both is the same, but the relevant process parameters are not exactly the same.

[0012] Common jet condensers require a large amount of cooling medium per unit of vapor phase condensation; for liquid jet vacuum pumps, when the amount of gas to be pumped is large and the vacuum degree is high, a large amount of injection liquid is required, especially in situations where the amount of condensed steam is large, the amount of injection liquid required is even greater; based on differences in vacuum degree, evaporation steam volume and cooling medium, the existing technology cannot be simply applied to the existing ammonium sulfate neutralization crystallization device.

[0013] In the process of studying heat exchange and vacuum technology, the inventor found that the jet atomizing condenser used in the sugar industry has good advantages under specific conditions. Ye Zhiwei et al.'s "On New Equipment of Vacuum Condensation System - Jet Atomizing Condenser" [J], Guangxi Light Industry, 2007, 23 (3) detailed the application and technology of the jet atomizing condenser in the sugar industry; Chinese patent CN201040758Y discloses a crystallization tank vacuum condenser belonging to the field of sugar vacuum equipment technology, which consists of a water inlet pipe, a water collection chamber, a shell, a cone pipe, and a tail pipe. The water collection chamber is divided into a condensation section and a suction section. The juice vapor (evaporation vapor) condensation section and the suction section are designed in one condenser. The condensation section uses atomized water to condense the juice vapor, and the suction section uses high-speed jet water to suck the non-condensable gas. Chinese patent CN107699640A discloses a water-cooled high-efficiency vacuum condenser system belonging to the field of vacuum process technology for sugar production, including a juice vapor generating tank, a pipeline, a water filtering device, a vacuum condensing device, a water collecting pool, a circulating water pool, and a water suction pump, which are connected together by pipelines; a combination of multiple atomizing nozzles and jet nozzles is adopted to effectively improve the vacuum degree and save water. The vacuum condensers used in the above two patents have similar structures and belong to direct contact condensers. They are an organic combination of a jet condenser and a hydraulic jet vacuum pump. A spray nozzle and a jet nozzle are designed in the equipment cavity. The spray nozzle sprays a large surface area of ​​atomized water droplets to fully mix and transfer heat with the juice vapor quickly, so that the water vapor quickly condenses into water to form a vacuum; the remaining non-condensable gas is sucked out of the tail pipe by the jet water ejected by the jet nozzle, thereby achieving the purpose of stable high vacuum.

[0014] In the sugar industry, the juice vapor (evaporation vapor) generated during the vacuum sugar boiling and sugar crystallization process is large, the vacuum condenser has a large condensation load, and a large amount of cooling water is required. Natural water such as river water is mostly used as cooling water, which has the characteristics of low inlet water temperature, no limit on outlet water temperature, and discharge after one-time use. This technology has the characteristics of stable vacuum degree and relative energy saving. However, the amount of cooling water and injection water used in this technology is too large, and the one-time water use is not suitable for the production needs of large-scale chemical equipment, and is not in line with the development concept of green environmental protection. Summary of the invention

[0015] The purpose of the technology of the present invention is to address the deficiencies in the prior art. The inventors analyzed the characteristics and requirements of the DTB neutralization crystallization process and equipment for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia, studied technologies such as liquid jet vacuum pumps, jet condensers, and jet atomizing condensers, and creatively proposed a device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia, which has low pressure drop, low energy consumption, is more environmentally friendly, and saves investment, and its application in producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia.

[0016] A device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia, comprising a DTB neutralizing crystallizer; a built-in main condenser is arranged in the body of the DTB neutralizing crystallizer, and a tail condenser, a condensate system and other related equipment are arranged outside the crystallizer body to form a neutralizing crystallization process and device; the main condenser is also equipped with a liquid collecting tank, a liquid collecting bucket, a condensate outlet and a condensate pipeline; the tail condenser is also equipped with vacuum facilities and a liquid injection system; the tail condenser is preferably a jet condenser; the liquid collecting tank collects the condensate generated on the shell side of the main condenser, and discharges it through the condensate outlet on the cylinder of the DTB neutralizing crystallizer, and flows to the condensate system by gravity; the top of the DTB neutralizing crystallizer The vapor phase outlet is connected to the jet condenser, and a small amount of evaporation vapor containing non-condensable gas is condensed in the jet condenser. The non-condensable gas is sucked by the liquid jet vacuum pump to form a vacuum, and the jet liquid containing non-condensable gas and condensate is discharged from the bottom drain port of the jet condenser to the jet liquid tank of the jet liquid system, and then pressurized by the jet liquid pump and cooled by the jet liquid cooler, and circulated to the jet liquid inlet of the nozzle to realize the recycling of the jet liquid, and the discharged jet liquid flows by gravity to the condensate system; spraying facilities are provided above the main condenser and below the liquid collecting tank; the circulating feed liquid of the neutralization crystallizer is used as the feed liquid of the jet liquid, and the balanced jet liquid flows by gravity to the condensate system; the jet liquid cooler is cooled by circulating cooling water.

[0017] The condensate produced by the main condenser is collected in the collecting tank, and flows to the condensate system by gravity through the collecting hopper and the condensate outlet. The destination of the condensate is the same as that of the existing process; the remaining small amount of evaporation vapor and non-condensable gas is discharged from the vapor phase outlet at the top of the DTB and crystallizer to the tail condenser. The uncondensed evaporation vapor and non-condensable gas are first condensed by the spray condenser using the jet liquid as the cooling medium in the tail condenser, and then sucked and vacuumed by the liquid jet pump using the jet liquid as the power medium. The non-condensable gas and condensate are discharged from the bottom outlet of the tail condenser to the jet liquid system, and then pressurized to the jet liquid cooler by the jet liquid pump, cooled to the specified temperature by the circulating cooling water, and sent to the jet liquid inlet of the jet condenser to realize the recycling of the jet liquid. The balanced jet liquid is discharged to the condensate system, and the vacuum is drawn without steam.

[0018] The DTB neutralization crystallizer has the characteristics of large cylinder diameter and high internal space. The inventor arranges a built-in main condenser in the upper space of the DTB neutralization crystallizer body to form an integrated device with the neutralization crystallizer. The condenser extends into the heat exchange component in the neutralization crystallizer without a shell, so that most of the evaporated steam can be condensed on the interlayer without pressure drop, thereby reducing the pressure drop on the evaporated steam (vacuum) side; more than 95% of the evaporated steam generated by the heat of the crystallizer neutralization reaction is condensed into liquid by the main condenser, which greatly reduces the amount of evaporated steam discharged from the vapor phase port at the top of the DTB neutralization crystallizer, thereby reducing the diameter of the vapor phase pipe from the top of the DTB neutralization crystallizer to the tail condenser and the condensation cooling load of the downstream tail condenser.

[0019] The main condenser is one or a combination of a shell-and-tube condenser and a plate-and-shell condenser, and is composed of one or more units. The evaporation vapor generated by the neutralization crystallization can enter the heat exchange components of the main condenser from multiple directions, and is not affected by the gap between the baffles, tube bundles (or shell plates) and the cylinder, and the pressure drop during the condensation process can be ignored; the main component of the evaporation vapor is water, and the heat transfer film coefficient on the water vapor condensation side is usually very large, greater than the heat transfer film coefficient on the tube side; the cooling medium of the main condenser is circulating cooling water, which flows on the tube side (plate path) and forms a staggered flow with the evaporation vapor, taking away the heat released by the evaporation vapor; the condenser is not provided with a shell and baffles, which has little effect on the total heat transfer coefficient of the condenser, and can still maintain a high total heat transfer coefficient of the condenser; when the vacuum degree of water vapor condensation is close to 10KPa (a), the low pressure drop can significantly increase the water vapor condensation temperature, thereby increasing the logarithmic mean temperature difference of heat exchange, which is conducive to condensation.

[0020] The heat exchange components of the main condenser are installed in the vapor phase space at the top of the DTB neutralization crystallizer, and the main condenser heat exchange section in the DTB neutralization crystallizer is not provided with a shell. Based on installation, internal space and effective heat transfer considerations, the shell diameter of a single condenser should not exceed Φ1500, preferably not more than Φ1200. In order to meet the heat exchange requirements, combined with the space that can be arranged at the top of the DTB neutralization crystallizer, the specifications and number of built-in condensers are comprehensively determined according to conventional engineering calculations; the present invention does not require all condensers to be installed at the same height, which is conducive to reducing the pressure drop on the evaporation vapor side, effective heat transfer of the condenser and condenser settings; without increasing the diameter of the crystallizer, the DTB neutralization crystallizer cylinder can be appropriately raised according to engineering knowledge and design regulations to increase the height of the top vapor phase space, so that the operating liquid level above the guide tube of each main condenser to the crystallizer is kept at a certain distance.

[0021] The DTB neutralization crystallizer has a mounting hole on the cylinder wall corresponding to the vapor phase space at its upper part, and a short tube with the same diameter as the main condenser shell is welded to the outside of the cylinder through the mounting hole, and the length of the short tube meets the needs of the condenser; the outlet end of the short tube is provided with a flange, and the flange connects and combines the main condenser, the main condenser pipe box and the short tube, so as to realize the connection and fixation of the DTB neutralization crystallizer cylinder and the condenser pipe box end; the pipe box is provided with a cooling water inlet and outlet, and are respectively connected to the corresponding external cooling water supply and return pipes; the pipe box, the internal partition plate and the cooling water inlet and outlet are designed according to the usual engineering practices.

[0022] The main condenser is fixed, supported or suspended in the DTB neutralization crystallizer by bolts and / or welding with the steel beams, rods and other parts installed in the DTB neutralization crystallizer. The heat exchange components of the main condenser are almost all inside the neutralization crystallizer, and the center of gravity of the main condenser's own load is also inside the neutralization crystallizer. It is necessary to set corresponding support beams, rods and other components in the DTB neutralization crystallizer, which are used to support various loads of the main condenser, fix or limit the displacement of the condenser, and facilitate the installation and maintenance of the main condenser. The location, number and specifications of the support beams are related to the specifications, number and layout of the main condenser, and are designed according to conventional engineering technology.

[0023] The collecting tank is arranged directly below the heat exchange component of the main condenser, and the collecting area of ​​the collecting tank is not less than the projected area of ​​the main condenser from directly above; the collecting tank can be in the form of a groove or a circular arc plate with a baffle; the condensate outlet end of the collecting tank is tightly connected to the inner side of the crystallizer cylinder, and slopes toward the condensate outlet end, with a slope angle ranging from 1° to 10°. The evaporation vapor generated by the neutralization heat of the DTB and the crystallizer rises to the periphery of the main condenser, exchanges heat with the circulating cooling water, releases latent heat and condenses into liquid. The condensate drips to the collecting tank below under the action of gravity. The collecting tank should be arranged below the main condenser, and the collecting area should be able to cover the area where the condensate of the corresponding main condenser above may fall, to ensure that all condensate is collected.

[0024] The condensate outlet end of the liquid collecting tank is tightly connected to the inner side of the crystallizer cylinder, which means that there is no gap or notch between the connecting parts that may cause leakage. In addition to setting the liquid collecting tank as described in the invention, the technical requirements are that the liquid collecting tank maintains a certain downward slope toward the condensate outlet end; the condensate in the liquid collecting tank should not overflow or leak into the DTB and the evaporation surface of the crystallizer; the horizontal slope angle of the liquid collecting tank is related to the condensate amount and the specifications of the liquid collecting tank. These are engineering technical common sense and can be designed through conventional engineering calculations.

[0025] The liquid collecting hopper is arranged on the inner side of the joint between the discharge end of the liquid collecting tank and the barrel of the DBT crystallizer. The liquid collecting hopper, the discharge end of the liquid collecting tank and the barrel of the crystallizer are all tightly connected. The liquid collecting hopper and the end plate of the discharge end of the liquid collecting tank are tightly connected through similar connecting grooves or plates. The function of the liquid collecting hopper is the same as that of the liquid collecting hopper of the distillation tower. The depth and volume of the liquid collecting hopper, and the connection method with the barrel and the nozzle are also the same as the requirements of the liquid collecting hopper of the distillation tower. It is designed according to conventional engineering knowledge to prevent the condensate from overflowing or leaking back into the crystallizer.

[0026] The condensate outlet is a pipe opening on the wall of the joint between the collecting bucket and the crystallizer cylinder. The bottom of the condensate outlet is not higher than the bottom of the collecting bucket to facilitate discharge and drainage. The condensate outlet, collecting bucket, main condenser and collecting tank correspond to each other one by one, ensuring that the condensate collected by the collecting tank flows smoothly from the collecting tank to the collecting bucket, and then is smoothly discharged from the condensate outlet, and finally flows through the external pipeline to the condensate system of the crystallization device; the collecting tank collects the condensate generated on the shell side of the main condenser, and the condensate in the collecting tank flows to the collecting bucket, and then flows through the condensate outlet and the external pipeline to the condensate system; the specifications of the collecting tank, collecting bucket and condensate outlet can be calculated according to conventional engineering knowledge, and the connection method and mechanical strength between the three can be designed according to general machinery.

[0027] The DTB neutralization crystallizer is operated in vacuum. The setting and pipeline design of the condensate system should ensure that the condensate has sufficient potential difference to ensure smooth self-flow, and it should have a liquid sealing function to prevent external gas from entering the DTB neutralization crystallizer. This is a common requirement and practice in engineering design.

[0028] A spray facility is provided above the main condenser and below the liquid collecting tank, and is characterized in that one or more groups of spray nozzles are provided above the main condenser, and one or more groups of spray nozzles are provided below the liquid collecting tank, which should cover the horizontal projection area of ​​each flushed equipment; the spray liquid comes from the condensate system in the neutralization crystallizer device, the main component of the condensate is water, and it almost does not contain ammonium sulfate. The condensate is used as a medium to flush and dissolve to remove ammonium sulfate crystals that may adhere to the components; the number, arrangement and required condensate amount of the spray nozzles can be calculated and arranged according to the method provided in the engineering professional manual.

[0029] The tail condenser is externally arranged in the neutralization crystallizer, and can adopt a direct contact condenser or a partition condenser. The direct contact condenser is preferred. The direct contact condenser has the characteristics of good condensation effect, small heat transfer temperature difference, and small pressure drop during the condensation process. More importantly, the condensate in the process technology of the present invention needs to be returned to the neutralization crystallization device for reuse, so that the liquid in the device (such as condensate, circulating material liquid) is compatible as a cooling medium for direct cooling; the disclosed technology adopts a partition surface condenser, and the cooling water condenses the evaporated steam indirectly on the cold side of the heat exchanger. The partition condenser can be one or a combination of a shell and tube heat exchanger, a spiral plate heat exchanger, and a plate heat exchanger. The current technology is mostly a shell and tube heat exchanger; the direct contact condenser has the following types: liquid column condenser, liquid film condenser, filling tower condenser, and jet condenser. The jet condenser is preferred. The pressure drop during the condensation process is extremely small, the contact area between the fluids is large, and the condensation effect is good.

[0030] The jet condenser has a nozzle installed in the upper space of the condenser body cavity, a shell is provided with a vapor phase inlet and a jet liquid inlet, and a drain port is arranged vertically at the bottom of the condenser; the nozzle includes a conventional nozzle and an atomizing nozzle, preferably an atomizing nozzle; a small amount of evaporation vapor and non-condensable gas that are not condensed in the DTB neutralizer are discharged from the top vapor phase outlet to the vapor phase inlet of the tail condenser, and directly contact with the atomized jet liquid distributed from the jet liquid cavity to the atomizing nozzle and atomized after passing through the atomizing nozzle, so as to achieve low pressure drop, rapid condensation and cooling, and the condensate and the jet liquid fall into the liquid collecting pipe at the bottom of the jet condenser due to gravity.

[0031] The vacuum facility is used to suck the non-condensable gas condensed in the tail condenser to form the required vacuum degree. The vacuum facility can select one or a combination of a liquid jet vacuum pump, a liquid ring vacuum pump and a Roots vacuum pump, preferably a liquid jet vacuum pump. The technology of the present invention is optimized and improved, and uses the existing process liquid in the device as the liquid medium of the injection liquid of the jet vacuum pump, which is not only beneficial to stabilizing the system vacuum degree, but also beneficial to reducing wastewater discharge, and does not require a steam jet vacuum pump to save energy.

[0032] The jet condenser and the liquid jet vacuum pump may be set up independently of each other, or the liquid jet vacuum pump may be embedded in the jet condenser cylinder, which is called a jet vacuum condenser. In the independent setting, the non-condensable gas discharged from the jet condenser is discharged to the liquid jet vacuum pump through an external pipeline. The jet vacuum condenser is preferred, and the gas after jet condensation is immediately sucked by the liquid jet, which has the characteristics of compact equipment and small pressure drop during condensation and vacuuming.

[0033] The jet vacuum condenser is characterized in that an atomizing nozzle for condensation and cooling and a jet nozzle for vacuuming are arranged from top to bottom in the upper part of the jet tail condenser cylinder, a diffusion tube and a liquid collecting pipe are arranged in sequence at the lower part of the cylinder, and a drain port is arranged at the bottom; the atomizing nozzle and the jet nozzle are both provided with respective jet liquid inlets and jet liquid cavities in the condenser shell, and are connected to the jet liquid cooler outlet end of the jet liquid system through a pipeline; the jet nozzle is vertically installed, and the jet liquid is sprayed vertically downward at a high speed through the jet nozzle, and the non-condensable gas after atomization, condensation and cooling is sucked to form a vacuum, and the jet liquid containing non-condensable gas and condensable liquid is discharged from the drain port at the bottom to the jet liquid tank of the jet liquid system through the diffusion tube and the liquid collecting pipe of the jet vacuum tail condenser. For given process conditions such as condensation load, vacuum degree, cooling medium conditions, etc., the jet vacuum condenser is designed according to the formulas and data described in the existing public technical information. The design includes determining the specifications of the jet vacuum condenser, the dimensions of the various parts of the jet vacuum condenser, and the specifications, quantity and distribution of the spray nozzles and jet nozzles to ensure that the designed results can achieve both the condensation effect and meet the system vacuum degree requirements.

[0034] The injection liquid system comprises an injection liquid tank, an injection liquid pump and an injection liquid cooler, etc.; the injection liquid tank is provided with an injection liquid return port, an injection liquid outlet, an overflow port, a liquid replenishing port, and an exhaust port is provided on the top; the injection liquid and the condensate carry a small amount of non-condensable gas, and flow into the injection liquid tank from the bottom discharge port of the injection vacuum tail condenser under the action of gravity, and gas-liquid separation is performed in the injection liquid tank, wherein the non-condensable gas is discharged from the exhaust port of the injection liquid tank through the high-point discharge pipe, and the injection liquid flows from the injection liquid outlet of the injection liquid tank to the injection liquid pump inlet; the injection liquid is pressurized by the injection liquid pump, and after being cooled to a specified temperature by circulating cooling water in the injection liquid cooler, it is circulated to the corresponding inlet of the atomizing nozzle and the injection nozzle of the injection vacuum tail condenser, so as to realize the recycling of the injection liquid; the condensate generated in the condensation process and the added circulating slurry both increase the injection liquid of the system, and the excess injection liquid is discharged to the condensate system through the overflow port of the injection liquid tank and the corresponding pipeline, so as to realize the working liquid balance of the injection liquid system.

[0035] The spray liquid system, the condensing atomizing nozzle and the vacuum spray nozzle share a set of spray liquid system.

[0036] Application of the above-mentioned device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia in the process of producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia:

[0037] Ammonia gas and redistribution liquid enter the DTB neutralization crystallizer through their respective nozzles. The operating pressure of the neutralization crystallizer is 10-25KPa(a) and the operating temperature is about 40-60°C. 90-95% of the evaporation vapor generated by the heat of neutralization crystallization is condensed on the shell side of the main condenser. The condensate is collected by the liquid collecting tank below the main condenser, flows into the liquid collecting hopper and the condensate outlet to discharge the crystallizer, and then flows to the condensate system by gravity. The destination of the condensate is the same as that of the disclosed technical process.

[0038] DTB neutralizes the evaporation vapor and non-condensable gas in the crystallizer that are not condensed by the main condenser, and discharges them from the vapor phase outlet at the top to the vapor phase inlet of the tail condenser. In the tail condenser (jet vacuum condenser), they are directly in contact with the atomized spray liquid and are condensed. The non-condensable gas and other components are sucked by the liquid spray to form a vacuum. All fluids then pass through the diffusion pipe and liquid collecting pipe of the jet vacuum tail condenser, and are finally discharged from the drain port at the bottom to the jet liquid tank of the jet liquid system. The jet liquid is separated into gas and liquid in the jet liquid tank, and the non-condensable gas is discharged from the exhaust port of the jet liquid tank through the high point. The discharge pipe discharges, and the injection liquid flows from the injection liquid outlet of the injection liquid tank to the injection liquid pump inlet; the injection liquid is pressurized by the injection liquid pump, and after being cooled to a specified temperature by circulating cooling water in the injection liquid cooler, it circulates to the atomizing nozzle and the corresponding inlet of the injection nozzle of the injection vacuum tail condenser to realize the recycling of the injection liquid; a pipeline is connected from the outlet pipe of the crystallizer circulation pump to the liquid replenishing port of the injection liquid tank to replenish the circulating liquid to the injection liquid system; the injection liquid after the injection liquid system is balanced is discharged to the condensate system through the overflow port of the injection liquid tank and the corresponding pipeline, and then returns to the crystallizer.

[0039] The injection liquid is a mixture of one or two of the circulating feed liquid of the DTB neutralization crystallizer and the ammonium sulfate mother liquor and the condensate of the tail condenser, and does not contain ammonium sulfate crystals; the condensate is produced by the condensation of evaporation steam during the operation of the jet vacuum condenser; the circulating feed liquid refers to the slurry containing ammonium sulfate drawn from the middle of the crystallizer baffle area by the crystallizer circulating pump, and is a pipe branched from the outlet pipe of the crystallizer circulating pump to the injection liquid tank replenishing pipe; the ammonium sulfate mother liquor is ammonium sulfate mother liquor produced by the centrifugal process of the ammonium sulfate device, which is pumped to the inlet pipe of the crystallizer circulating pump through the mother liquor pump and finally enters the neutralization crystallizer. When used as the injection liquid, it is a pipe branched from the outlet pipe of the mother liquor pump to the injection liquid tank replenishing pipe to add the circulating feed liquid to the injection liquid tank; the maximum amount of the circulating feed liquid added is to ensure that the injection liquid is in an unsaturated state and does not contain crystals, and the amount of the circulating feed liquid added is controlled not to exceed the amount of condensate generated by the tail condenser; the minimum amount of the circulating feed liquid added should ensure that the pH value of the injection liquid entering the tail condenser is less than 7.

[0040] The spray liquid cooler is characterized in that a partition cooler is used, which is one or a combination of a shell and tube heat exchanger, a spiral plate heat exchanger, and a plate heat exchanger, preferably a plate heat exchanger. The plate heat exchanger can provide a smaller heat transfer temperature difference, and is particularly suitable for liquid-liquid heat exchange occasions to obtain a higher heat exchange efficiency and a lower spray liquid outlet temperature.

[0041] The jet liquid cooler is characterized in that its cooling medium is circulating cooling water; the circulating cooling water is a part or all of the circulating cooling water used by the main condenser, which is first used as the cooling medium of the jet liquid cooler, and then reaches the cooling water inlet of the main condenser after heat exchange in the jet liquid cooler, and the inlet and outlet temperature difference of the cooling water passing through the jet liquid cooler is controlled to be no more than 1°C; the cooling medium adopts a large flow rate and a low temperature rise, so that the jet liquid cooler can obtain the maximum logarithmic mean temperature difference without using low-temperature cooling water, so as to reduce the outlet temperature of the jet liquid, which is the inlet temperature of the tail condenser.

[0042] In the method for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia, the temperature of the spray liquid at the inlet of the tail condenser does not exceed 45° C., preferably 35-40° C. This temperature is reached after the spray liquid is cooled by the above-mentioned spray liquid cooler.

[0043] In the method for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia, the temperature of the circulating spray liquid discharged from the bottom of the tail condenser does not exceed 55°C, preferably 40-50°C; the temperature of the discharged circulating spray liquid should not exceed the maximum temperature allowed by vacuum extraction, and the theoretical value of the maximum temperature is the saturation temperature of the spray liquid under the corresponding vacuum degree.

[0044] The inlet temperature of the injection liquid to the tail condenser and the temperature of the injection liquid discharged from the tail condenser are related to the vacuum degree, condensation load, vacuum load, injection liquid volume, external cooling medium, etc. required by the process; for given process conditions, including the amount of vapor phase entering the injection vacuum condenser, the amount of non-condensable gas, and the vacuum degree of the neutralizer, the injection liquid inlet temperature and discharge temperature are set first, and the condensation injection liquid volume and vacuum injection liquid volume are calculated according to public technical data, and the minimum working pressure to the nozzle inlet is deduced from this, and an optimal value is found between the injection liquid inlet and outlet temperature difference, flow rate and pressure. Adjustment facilities are set at the condensation injection liquid inlet pipe and the vacuum injection inlet pipe to ensure that the injection liquid to the two nozzles in the vacuum tail condenser meets the requirements. The above work belongs to conventional engineering calculations, and industry engineers can design according to the design manual or data. The design includes the nozzle-injected vacuum tail condenser, as well as related equipment, process flow, instrumentation and pipelines.

[0045] The beneficial effects of the technology of the present invention are:

[0046] 1. The built-in main condenser is adopted, and the shell of the condenser heat exchange section extending into the neutralization crystallizer is cancelled. The evaporation steam of the crystallizer can directly enter the condenser tube bundle (or plate) in multiple directions and be condensed by the circulating cooling water, and no longer passes through the pipeline, inlet and outlet pipes, and baffles, eliminating the pressure drop of the condensation process on the evaporation steam side, reducing the vacuum load, which is conducive to heat transfer and full condensation of the evaporation steam.

[0047] 2. After most of the evaporative steam is condensed in the main condenser, the amount of evaporative steam discharged from the top of the neutralization crystallizer is greatly reduced, and the diameter of the vapor phase pipe of the DTB neutralization crystallizer is greatly reduced, which reduces the design difficulty and investment of the pipeline.

[0048] 3. The tail condenser adopts a jet condenser. After being sprayed, the cooling medium has a larger surface area and direct contact with the evaporating steam in a mist form to achieve efficient heat transfer, low heat transfer temperature difference, low pressure drop and rapid condensation effect.

[0049] 4. The jet vacuum condenser that combines spray condensation and liquid jet vacuuming simplifies the condensation and vacuum facilities and equipment, eliminates the flow resistance of non-condensable gas between the two devices, and further reduces the system pressure drop, the vacuum degree required by the vacuum pump and the energy consumption.

[0050] 5. Liquid jet vacuuming is adopted instead of steam as the power medium, which reduces energy consumption.

[0051] 6. The circulating liquid of the neutralized crystallizer is used as the injection liquid. No external water replenishment or drainage is required during operation, which is more environmentally friendly. At the same time, since the circulating liquid of the crystallizer is ammonium sulfate solution, the vacuum degree of the vacuum system can be further improved.

[0052] 7. The jet liquid cooler adopts large flow and low temperature rise circulating cooling water, and the operating vacuum is more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 Schematic diagram of the DTB neutralization crystallizer system of the present invention.

[0054] Attached Figure 1 The neutralization crystallization system 100 mainly includes: a DTB neutralization crystallizer 101, a neutralization crystallizer cylinder 102, a guide cylinder 103, a separation cylinder 104, a baffle area 105, a flushing facility 106, a demisting facility 107, an agitator 108, a crystallizer circulation pump 110, a slurry discharge pump 111, an amide oil discharge pump 112, an evaporation steam pipe 115, an ammonium sulfate mother liquor pipe 116, a circulating liquid pipe 117, a main condenser 151, a liquid collecting tank 152, a liquid collecting bucket 153, a condensate outlet 154, and a condensate pipe 155.

[0055] Figure 2 One of the process flow charts of the DTB neutralization crystallizer device of the present invention.

[0056] Attached Figure 2 The process flow is composed of a neutralization crystallization system 100, a jet vacuum tail condensation system 200, a condensation system 300, and a jet liquid system 400, wherein:

[0057] The neutralization crystallization system 100 mainly includes: a DTB neutralization crystallizer 101, a neutralization crystallizer cylinder 102, a guide cylinder 103, a dividing cylinder 104, a baffle area 105, a flushing facility 106, a defogging facility 107, an agitator 108, a crystallizer circulation pump 110, a slurry discharge pump 111, an amide oil discharge pump 112, an evaporation steam pipe 115, an ammonium sulfate mother liquor pipe 116, a circulating liquid pipe 117, an ammonium sulfate mother liquor branch pipe 118, a circulating liquid branch pipe 119, a main condenser 151, a liquid collecting tank 152, a liquid collecting bucket 153, a condensate outlet 154, and a condensate pipe 155.

[0058] The jet vacuum tail condensation system 200 mainly includes: a jet vacuum tail condenser 210, a jet vacuum tail condenser cylinder 211, an atomizing nozzle 212, an injection nozzle 213, a diffusion pipe 214, a liquid collecting pipe 215, a vapor phase inlet 216, an atomizing injection liquid chamber 217, a vacuum injection liquid chamber 218, an atomizing injection liquid pipe 220, a vacuum injection liquid pipe 221, and a liquid discharge pipe 222.

[0059] The condensate system 300 mainly includes: a condensate tank 301 , a condensate pump 302 , and a condensate return pipe 303 .

[0060] The injection liquid system 400 mainly includes: an injection liquid tank 401, an injection liquid pump 402, an injection liquid cooler 403, an overflow pipe 404, a non-condensable gas discharge pipe 405, an injection liquid pipe 406, a liquid replenishing pipe 407, a cooling water supply pipe 408, a cooling water bypass 409, and a cooling water pipe 410.

[0061] Figure 3 The second process flow chart of the DTB neutralization crystallizer device of the present invention.

[0062] Attached Figure 3 The process flow is composed of a neutralization crystallization system 100, a jet tail condensation system 200A, a condensate system 300, a jet liquid system 400, and a liquid ring vacuum system 500, wherein:

[0063] The crystallization system 100 mainly includes: a DTB neutralization crystallizer 101, a neutralization crystallizer cylinder 102, a guide cylinder 103, a separation cylinder 104, a baffle 105, a flushing facility 106, a defogging facility 107, an agitator 108, a crystallizer circulation pump 110, a slurry discharge pump 111, an amide oil discharge pump 112, an evaporation steam pipe 115, an ammonium sulfate mother liquor pipe 116, a circulating liquid pipe 117, an ammonium sulfate mother liquor branch pipe 118, a circulating liquid branch pipe 119, a built-in main condenser 151, a liquid collecting tank 152, a liquid collecting bucket 153, a condensate outlet 154, and a condensate pipe 155.

[0064] The spray tail condensation system 200A mainly includes: a spray tail condenser 210A, a spray tail condenser cylinder 211A, an atomizing nozzle 212, an atomizing spray liquid chamber 217, a vacuum air pipe 219, an atomizing spray liquid pipe 220, and a drain pipe 222.

[0065] The condensate system 300 mainly includes: a condensate tank 301 , a condensate pump 302 , and a condensate return pipe 303 .

[0066] The injection liquid system 400 mainly includes: an injection liquid tank 401, an injection liquid pump 402, an injection liquid cooler 403, an overflow pipe 404, an injection liquid pipe 406, a liquid replenishing pipe 407, a cooling water pipe 408, a cooling water bypass 409, a cooling water pipe 410,

[0067] The liquid ring vacuum system 500 mainly includes: a liquid ring vacuum pump 501 , a gas-liquid separation tank 502 , a working fluid cooler 503 , a working fluid replenishing pipe 504 , a non-condensable gas discharge pipe 505 , and a working fluid discharge pipe 506 .

[0068] Figure 4 It is a schematic diagram of the process flow of the DTB neutralization crystallizer device in the prior art.

[0069] Attached Figure 4 The process flow is composed of a neutralization crystallization system 100, a vacuum condensation system 200B, and a condensation system 300, wherein:

[0070] The neutralization crystallization system 100 mainly includes: a DTB neutralization crystallizer 101, a neutralization crystallizer cylinder 102, a guide cylinder 103, a separation cylinder 104, a baffle area 105, a flushing facility 106, a defogging facility 107, an agitator 108, a crystallizer circulation pump 110, a slurry discharge pump 111, an amide oil discharge pump 112, an evaporation steam pipe 115, an ammonium sulfate mother liquor pipe 116, and a circulating liquid pipe 117.

[0071] The vacuum condensation system 200B mainly includes: a condenser 201, a first-stage steam jet pump 202, a first-stage jet condenser 203, a second-stage steam jet pump 204, a second-stage jet condenser 205, a condensate discharge pipe 206, a condensate discharge pipe 207, an uncondensed steam pipe 208, and a non-condensable gas discharge pipe 209.

[0072] The meanings of the English codes in the above figure are: SML-medium pressure steam, pressure 0.9Mpa, superheat not less than 5℃; CWS-circulating cooling water (upstream water), upstream water temperature 33℃; CWR-circulating cooling water (return water), return water temperature 40℃; RWS-low temperature cooling water (upstream water), upstream water temperature 7℃; RWR-low temperature cooling water (return water), return water temperature 12℃.

[0073] The device described in the above figure refers to the device of the present invention and its closely related process steps, such as decantation, thickening, centrifugation and drying steps, to produce solid ammonium sulfate.

[0074] The "outside the device" mentioned in the above figure refers to materials, logistics and equipment that are not included in the above device. DETAILED DESCRIPTION

[0075] The present invention is further described in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited thereto:

[0076] Embodiment 1:

[0077] Caprolactam rearrangement liquid and ammonia neutralization crystallization unit, with an ammonium sulfate production capacity of 150,000 tons / year.

[0078] A built-in main condenser (151) is disposed in the DTB neutralization crystallizer (101) body, and a jet vacuum tail condensation system (200), a condensation liquid system (300), etc. are disposed outside the neutralization crystallizer (101) body; the jet vacuum tail condensation system (200) adopts a jet vacuum tail condenser (210) and a matching jet liquid system (400). The process flow is as shown in the attached figure. Figure 2 .

[0079] Ammonia gas and rearrangement liquid from outside the device are added in an amount adjusted by ratio, and ammonia gas is dissolved and absorbed into ammonia water by the condensate from the condensate return pipe (303). The ammonia water and rearrangement liquid enter the DTB neutralization crystallizer (101) through their respective nozzles; an internal circulation is formed under the action of the guide tube (103) and the agitator (108), and the ammonium sulfate solution containing crystal particles is quickly raised to the boiling surface on the upper part of the guide tube, and the water begins to evaporate. The crystal slurry flows downward from the boiling surface along the outer side of the guide tube. In the lower area outside the guide tube, the flow rate is reduced due to the change in the shape of the crystallizer. A part of the suspension returns to the guide tube through the action of the agitator, and the other part flows upward to the deflection area (105). In the baffle area (105), due to the density difference, the crystals and the amide oil are separated by sedimentation, and the amide oil layer containing a small amount of ammonium sulfate solution is sent to the decanter in the device by the amide oil discharge pump (112) for re-stratification; a part of the slurry containing ammonium sulfate crystals is extracted from the middle of the baffle area (105) by the crystallizer circulation pump (110), and the ammonium sulfate-containing process water from the outside of the device, the unsaturated ammonium sulfate mother liquor sent by the mother liquor circulation pump of the subsequent process, and the rest of the return condensate are connected to the inlet pipeline of the crystallizer circulation pump (110), mixed with the circulating ammonium sulfate slurry in the pipe, and then returned to the guide tube (103). When the ammonium sulfate solid content at the bottom of the neutralization crystallizer (101) reaches the set value, the ammonium sulfate slurry is extracted from the bottom by the crystal slurry discharge pump (111) and sent to the thickener in the device for thickening and separation.

[0080] The operating pressure at the top of the neutralization crystallizer is 15 KPa(a) and the operating temperature is about 60°C. 95% of the evaporation steam generated by the heat of neutralization crystallization is condensed on the shell side of the main condenser (151), and the condensate is collected by the sump (152) below the main condenser (151), flows into the condensate hopper (153) and is discharged from the neutralization crystallizer (101) through the condensate outlet (154), and flows to the condensate system (300) through the condensate pipe (155). The destination of the condensate is the same as that of the disclosed process technology.

[0081] The evaporation vapor and non-condensable gas in the DTB neutralization crystallizer (101) that have not been condensed by the main condenser (151) are discharged from the vapor phase outlet at the top of the neutralization crystallizer (101) and the evaporation vapor pipe (115) to the vapor phase inlet (216) of the jet vacuum tail condenser (210) and enter the jet vacuum tail condenser (210) to directly contact with the spray liquid sprayed by the atomizing nozzle (212) and be condensed. The non-condensable gas and other components are sucked by the spray liquid of the spray nozzle (213) to form a vacuum. All fluids then pass through the diffusion pipe (214) and the liquid collecting pipe (215) of the jet vacuum tail condenser (210) and are finally discharged from the discharge port and the discharge pipe (222) at the bottom thereof to the spray liquid tank (401) of the spray liquid system (400); the spray liquid is separated into gas and liquid in the spray liquid tank (401), and the non-condensable gas is discharged from the exhaust port of the spray liquid tank (401) through the high pressure outlet. The non-condensable gas is discharged from the discharge pipe (405) and the spray liquid flows from the spray liquid outlet of the spray liquid tank to the inlet of the spray liquid pump (402); the spray liquid is pressurized by the spray liquid pump (402) and is cooled to a specified temperature by circulating cooling water in the spray liquid cooler (403), and then circulated to the corresponding inlet pipes of the atomizing spray liquid chamber (217) and the vacuum spray liquid chamber (218) of the spray vacuum tail condenser, so as to realize the recycling of the spray liquid; the circulating liquid branch pipe (119) is connected from the circulating liquid pipe (117) of the crystallizer circulating pump (110) to the liquid replenishing pipe (407) of the spray liquid tank (401), and the circulating liquid is replenished to the spray liquid system (400); the spray liquid after the spray liquid system is balanced is discharged to the condensate tank (301) of the condensate system (300) through the overflow pipe (404) of the spray liquid tank (401), and finally returns to the neutralization crystallizer (101).

[0082] The main condenser (151) is of shell-and-tube type. The heat exchange section extending into the neutralization crystallizer (101) is without a shell. There are three heat exchangers in total, with specifications of Φ1100X4500, Φ1100X6000, and Φ1100X4500. The total heat exchange area of ​​the three heat exchangers is 1250m 2 , installed horizontally in the upper vapor space of the neutralization crystallizer (101); the cooling medium is circulating cooling water, the water inlet temperature is about 34°C, the water outlet temperature is 40°C, and the water volume is 1465m 3 / h.

[0083] The jet vacuum tail condenser (210) adopts a jet vacuum condenser, which is a jet condensation and vacuum equipment in one, one set, specification Φ900X2000, jet liquid inlet temperature 39 ° C, jet liquid inlet temperature 43 ° C, tail condenser top vacuum degree 14KPa (a). The atomizing nozzle (212) for condensation and the vacuum jet nozzle (213) in the tail condenser share a set of jet liquid system (400), the main equipment includes: jet liquid tank (401), jet liquid pump (402), and jet liquid cooler (403).

[0084] Main parameters of the jet pump (402): head 35m, flow 150m 3 / h, motor power 22kw.

[0085] Jet liquid cooler (403), 1 unit, plate heat exchanger, heat exchange area 72m 2 The circulating cooling water entering the cooler is 494m 3 / h, accounting for about one third of the cooling water upper pipe (408) of the main condenser (151), is first heated to 33.8°C by heat exchange in the injection liquid cooler, and then mixed with the remaining cooling water through the cooling water bypass (409) in the cooling water pipe (410) to the cooling water inlet of the main condenser (151); the injection liquid at the outlet of the injection liquid cooler (403) is cooled to 39°C.

[0086] The amount of circulating liquid added by the crystallizer circulation pump (110) to the injection liquid tank (401) is 750 kg / h.

[0087] The utility consumption of this technical solution: electricity 19kw; circulating cooling water 1465m 3 / h; no steam and low-temperature cooling water are required.

[0088] Embodiment 2:

[0089] Caprolactam rearrangement liquid and ammonia neutralization crystallization unit, with an ammonium sulfate production capacity of 150,000 tons / year.

[0090] A built-in main condenser (151) is arranged in the body of the DTB neutralization crystallizer (101), and a jet tail condensation system (200A), a condensation liquid system (300), etc. are arranged outside the body of the neutralization crystallizer (101); the jet tail condensation system (200A) adopts a jet tail condenser (210A) and a matching jet liquid system (400); the vacuum facility is independently set up and adopts a liquid ring vacuum system (500). The process flow is as shown in the attached figure. Figure 3 .

[0091] Ammonia gas and rearrangement liquid from outside the device are added in an amount adjusted by a ratio, and ammonia gas is dissolved and absorbed into ammonia water by the condensate sent from the condensate return pipe (303). The ammonia water and rearrangement liquid enter the DTB neutralization crystallizer (101) through their respective nozzles; an internal circulation is formed under the action of the guide tube (103) and the agitator (108), and the ammonium sulfate solution containing crystal particles is quickly raised to the boiling surface on the upper part of the guide tube, and the water begins to evaporate. The crystal slurry flows downward from the boiling surface along the outer side of the guide tube. In the lower area outside the guide tube, the flow rate is reduced due to the change in the shape of the crystallizer. A part of the suspension returns to the guide tube through the action of the agitator, and the other part flows upward to the deflection area (105). In the baffle area (105), due to the density difference, the crystals and the amide oil are separated by sedimentation, and the amide oil layer containing a small amount of ammonium sulfate solution is sent to the decanter in the device by the amide oil discharge pump (112) for re-stratification; a part of the slurry containing ammonium sulfate crystals is extracted from the middle of the baffle area (105) by the crystallizer circulation pump (110), and the ammonium sulfate-containing process water from the outside of the device, the unsaturated ammonium sulfate mother liquor sent from the mother liquor circulation pump of the subsequent process, and the rest of the return condensate are connected to the inlet pipeline of the crystallizer circulation pump (110), mixed with the circulating ammonium sulfate slurry in the pipe, and then returned to the guide tube (103). When the ammonium sulfate solid content at the bottom of the neutralization crystallizer (101) reaches the set value, the ammonium sulfate slurry is extracted from the bottom by the crystal slurry discharge pump (111) and sent to the thickener in the device for thickening and separation.

[0092] The operating pressure at the top of the neutralization crystallizer is 15 KPa(a) and the operating temperature is about 60°C. 95% of the evaporation steam generated by the heat of neutralization crystallization is condensed on the shell side of the main condenser (151), and the condensate is collected by the sump (152) below the main condenser (151), flows into the condensate hopper (153) and is discharged from the neutralization crystallizer (101) through the condensate outlet (154), and flows to the condensate system (300) through the condensate pipe (155). The destination of the condensate is the same as that of the disclosed process technology.

[0093] The evaporated vapor and non-condensable gas in the DTB neutralization crystallizer (101) that are not condensed by the main condenser (151) are discharged from the vapor phase outlet at the top of the neutralization crystallizer (101) and the evaporated vapor pipe (115) to the vapor phase inlet (216) of the jet tail condenser (210A) and enter the tail condenser (jet tail condenser 210A) to counter-flow and directly contact with the spray liquid sprayed by the atomizing nozzle (212) to be condensed. The condensate and the spray liquid fall into the discharge pipe (222) at the bottom of the jet tail condenser (210A) under the action of gravity and are discharged into the spray liquid tank (401) of the spray liquid system (400); the non-condensable gas and other non-condensable components are discharged from the gas outlet at the top of the jet tail condenser (210A), and are sucked through the vacuum air pipe (219) to the inlet of the liquid ring vacuum pump (501) to form a vacuum. The gas is discharged from the gas-liquid separation tank (502) and discharged at a high point through the non-condensable gas discharge pipe (505). The spray liquid flows from the spray liquid tank (401) to the inlet of the spray liquid pump (402), is pressurized by the spray liquid pump (402), and is cooled to a specified temperature by circulating cooling water in the spray liquid cooler (403). Then, the spray liquid is circulated to the inlet of the atomizing spray liquid chamber (217) of the spray tail condenser (210A), thereby realizing the recycling of the spray liquid; a circulating liquid branch pipe (119) is connected from the circulating liquid pipe (117) of the crystallizer circulating pump (110) to the liquid replenishing pipe (407) of the spray liquid tank (401), and the circulating liquid is replenished to the spray liquid in the spray liquid system (400). The working liquid of the liquid ring vacuum system (500) is added to the working liquid replenishing pipe (504) of the gas-liquid separation tank (502) by the jet liquid pump (402) through the pipeline; the jet liquid after the jet liquid system is balanced is discharged to the condensate tank (301) of the condensate system (300) through the overflow pipe (404) of the jet liquid tank (401); the working liquid after the liquid ring vacuum system (500) is balanced is discharged to the condensate tank (301) of the condensate system (300) through the working liquid discharge pipe (506); and finally returns to the neutralization crystallizer (101).

[0094] The main condenser (151) is of shell-and-tube type. The heat exchange section extending into the neutralization crystallizer (101) is without a shell. There are three heat exchangers in total, with specifications of Φ1100X4500, Φ1100X6000, and Φ1100X4500. The total heat exchange area of ​​the three heat exchangers is 1250m 2 , installed horizontally in the upper vapor space of the neutralization crystallizer (101); the cooling medium is circulating cooling water, the water inlet temperature is about 34°C, the water outlet temperature is 40°C, and the water volume is 1465m 3 / h.

[0095] The tail condenser adopts a jet condenser, and the tail condenser and the vacuum facility are set separately. There is one jet condenser with a specification of Φ1000X1600, and it is equipped with a jet liquid system; the main equipment of the jet liquid system (400) includes: a jet liquid tank (401), a jet liquid pump (402), and a jet liquid cooler (403); the jet liquid inlet temperature is 39℃, the jet liquid inlet temperature is 43℃, and the vacuum degree at the top of the tail condenser is 13.5KPa (a).

[0096] Main parameters of the jet pump (402): head 32m, flow 100m 3 / h, motor power 18.5kw.

[0097] Jet liquid cooler (403), jet liquid cooler, 1 unit, plate heat exchanger, heat exchange area 72m 2 ; The circulating cooling water entering the cooler is 450m 3 / h, which is less than one third of the circulating cooling water (408) of the main condenser (151), is first heated to 34°C by heat exchange in the injection liquid cooler, and then merged with the remaining circulating cooling water through the cooling water bypass (409) in the cooling water pipe (410), and then to the cooling water inlet of the main condenser (151); the injection liquid is cooled to 39°C.

[0098] Liquid ring vacuum system (500), one set, including liquid ring vacuum pump (501), gas-liquid separation tank (502), working liquid cooler (503), etc.; operating parameters: air extraction volume 17m 3 / min, vacuum degree at the inlet of liquid ring vacuum pump (501) is 13.0KPa (a), motor power is 30kw, low-temperature cooling water consumption is about 20m 3 / h.

[0099] The amount of circulating liquid added by the crystallizer circulation pump (110) to the injection liquid tank (401) is 700 kg / h; the average amount of working liquid added by the injection liquid pump (402) to the gas-liquid separation tank (502) of the liquid ring vacuum system (500) is 50 kg / h.

[0100] The utility consumption of this technical solution: 44kw of additional electricity; 1465m3 of circulating cooling water 3 / h; Add 20m3 of low-temperature cooling water 3 / h; no steam is required.

[0101] Comparative Example 1:

[0102] According to the production scale of Example 1 and Example 2, the neutralization reaction crystallization technology of the caprolactam ammonium sulfate device described in Wang Jin. Comparison of ammonium sulfate evaporation crystallization and neutralization crystallization in caprolactam production [J]. "China Chemical Trade" Issue 3, 2014, adopts a DTB type neutralization crystallizer (101), an external condenser (201), and a vacuum steam jet pump technology. The process flow is as shown in the attached Figure 4 .

[0103] The operating pressure of the neutralization crystallizer is 15KPa(a) and the operating temperature is about 60°C. The evaporation steam generated by the heat of neutralization crystallization is discharged from the vapor phase outlet at the top of the neutralization crystallizer, enters the shell-and-tube condenser (201) through the evaporation steam pipe (115), is condensed into condensate by the circulating cooling water, and flows to the condensate tank (301) through the condensate discharge pipe (206); the uncondensed gas discharged from the condenser (201) is extracted by a steam jet vacuum pump; the steam jet vacuum pump is a two-stage jet, consisting of a first-stage steam jet pump (202), a first-stage jet condenser (203), a second-stage steam jet pump (204) and a second-stage jet condenser (205). The discharged uncondensed gas passes through the uncondensed steam pipe (208) to the first-stage steam jet pump (202) to be extracted and pressurized, and then to the first-stage jet condenser (203) for condensation. The gas that has not been condensed is extracted and pressurized again to the second-stage steam jet pump (204). Subsequently, the steam is further condensed in the secondary jet condenser (205), and a small amount of non-condensable gas that is not condensed by the secondary jet condenser (205) is discharged at a safe high point through the non-condensable gas discharge pipe (209); the steam condensate from the primary jet condenser (203) and the secondary jet condenser (205) flows by gravity to the condensate tank (301) through the condensate discharge pipe (206); all the condensate in the condensate tank (301) is pressurized by the condensate pump (302) and circulated back to the neutralization crystallization system (100) through the condensate return pipe (303) to balance the evaporated water; a part of the condensate is sent to the ammonia feed pipe to dissolve and absorb ammonia; a part of the condensate is sent to the inlet pipe of the crystallizer circulation pump (110) to dissolve the fine crystals in the circulating slurry; a small part of the condensate is used for flushing various parts and finally returns to the neutralization crystallizer (101).

[0104] The vacuum degree at the top of the neutralization crystallizer (101) is 15 KPa (a), the vacuum degree at the outlet of the condenser (201) is 12.5 KPa (a), and the vacuum degree at the inlet of the first-stage steam jet pump (202) is 12.0 KPa (a)

[0105] Comparative Example 1: Utility consumption of the technical solution: No additional electricity consumption, recorded as 0; Circulating cooling water 1600m 3 / h; low-temperature cooling water consumption is not consumed and is recorded as 0; steam consumption is 1200kg / h.

[0106] Utility prices: Steam, 150 yuan / t; electricity, 0.65 yuan / kw; circulating cooling water, 0.22 yuan / m 3 ; Low temperature cooling water, 0.5 yuan / m 3 .

[0107] The ammonium sulfate crystallization device with an ammonium sulfate production capacity of 150,000 tons / year, the utility consumption and calculated costs of Example 1, Example 2, and Comparative Example 1 are compared and shown in Table 1.

[0108] Table 1 Comparison between the present invention and the prior art

[0109]

[0110] The above only compares the utility consumption differences between the embodiment and the comparative example. For example, if the production device is operated for 8,000 hours per year, a set of 150,000 tons / year ammonium sulfate crystallization device using the technology of the present invention can save the utility consumption of:

[0111] (538-334.65) x 8000 = 1626800 (yuan / year)

[0112] The above descriptions are only some embodiments of the present invention and are not intended to limit the present invention. That is to say, the present invention is not limited to the described embodiments. Those skilled in the art may make some modifications or changes without departing from the spirit of the present invention, that is, within the scope of disclosure. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia, comprising a DTB neutralizing crystallizer, characterized in that: The DTB neutralization crystallizer body is provided with a built-in main condenser, and the body is provided with a tail condenser and a condensation system; the main condenser is equipped with a liquid collecting tank, a liquid collecting bucket, a condensation outlet and a condensation pipeline; the tail condenser is equipped with vacuum facilities and a jet liquid system; the tail condenser adopts a jet vacuum condenser, in which a liquid jet vacuum pump is embedded in the jet condenser cylinder, and an atomizing nozzle for condensation cooling and a jet nozzle for vacuuming are arranged from top to bottom in the upper part of the jet tail condenser cylinder, and a diffusion pipe and a liquid collecting pipe are arranged in sequence at the lower part of the cylinder, and a liquid discharge port is arranged at the bottom; the atomizing nozzle and the jet nozzle are provided with respective jet liquid inlets and jet liquid cavities in the condenser shell, and are connected to the outlet end of the jet liquid cooler of the jet liquid system through a pipeline; the jet nozzle is installed vertically, and the jet liquid is ejected vertically downward at a high speed through the jet nozzle, and the non-condensable gas after atomization, condensation and cooling is sucked to form a vacuum, and the jet liquid containing condensate and non-condensable gas is discharged from the bottom discharge port to the jet liquid tank of the jet liquid system through the diffusion pipe and the liquid collecting pipe of the jet vacuum tail condenser.

2. The device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia according to claim 1, characterized in that The main condenser is a type of a shell-and-tube condenser or a plate-and-shell condenser or a combination thereof, and is composed of one or more condensers.

3. The device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia according to claim 1, characterized in that The main heat exchange components or assemblies of the main condenser are installed in the vapor phase space on the upper part of the DTB neutralizer and crystallizer, and the heat exchange section of the condenser in the neutralizer and crystallizer is not provided with a shell.

4. The device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia according to claim 1, characterized in that A mounting hole is provided on the cylinder wall corresponding to the vapor phase space in the DTB and the upper part of the crystallizer. A short tube with the same diameter as the main condenser shell is welded to the outside of the cylinder through the mounting hole. The outlet end of the short tube is provided with a flange. The flange connects and combines the main condenser, the main condenser pipe box and the short tube. The pipe box is provided with a cooling water inlet and outlet, which are respectively connected to the external cooling water pipeline.

5. The device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia according to claim 1, characterized in that The collecting tank is arranged directly below the main condenser heat exchange component, and the collecting area of ​​the collecting tank is not less than the projection area of ​​the main condenser from directly above; the collecting tank is in the form of a groove or a circular arc plate with a baffle; the condensate outlet end of the collecting tank is tightly connected to the inner side of the crystallizer cylinder, and slopes toward the condensate outlet end, with a slope angle ranging from 1° to 10°.

6. The device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia according to claim 1, characterized in that The liquid collecting hopper is arranged on the inner side of the joint between the discharge end of the liquid collecting tank and the cylinder of the DBT crystallizer. The liquid collecting hopper, the discharge end of the liquid collecting tank and the cylinder of the crystallizer are all tightly connected.

7. The device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia according to claim 1, characterized in that The condensate discharge outlet is a pipe outlet opened on the wall of the junction of the liquid collecting bucket and the crystallizer cylinder, and the bottom of the condensate discharge outlet is not higher than the bottom of the liquid collecting bucket; the condensate discharge outlet, the liquid collecting bucket, the main condenser, and the liquid collecting tank are one-to-one corresponding; the liquid collecting tank collects the condensate produced by the main condenser, and the condensate in the liquid collecting tank flows to the liquid collecting bucket, and then flows to the condensate system through the condensate discharge outlet and the external pipeline.

8. The device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia according to claim 1, characterized in that One or more spray facilities are arranged above the main condenser, one or more spray nozzles are arranged below the liquid collecting tank, and the spray nozzles are connected to the condensation system.

9. The device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia according to claim 1, characterized in that A nozzle is installed in the upper space of the jet vacuum condenser body cavity, the shell is provided with a vapor phase inlet and a jet liquid inlet, the lower part of the condenser is a liquid collecting pipe, and the bottom of the condenser is provided with a liquid discharge port; the nozzle is a conventional nozzle or an atomizing nozzle.

10. The device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia according to claim 1, characterized in that The vacuum facility is one or a combination of a liquid jet vacuum pump, a liquid ring vacuum pump and a Roots vacuum pump.

11. The device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia according to claim 1, characterized in that The spray liquid system mainly includes a spray liquid tank, a spray liquid pump and a spray liquid cooler; the spray liquid tank is provided with a spray liquid return port, a spray liquid outlet, an overflow port, a liquid replenishing port, and an exhaust port on the top; The tail condenser discharge port is connected to the injection liquid tank, the injection liquid outlet is connected to the injection liquid pump inlet, the injection liquid pump outlet is connected to the injection liquid cooler inlet, and the injection liquid cooler outlet is connected to the atomizing nozzle and the injection nozzle corresponding to the injection cavity in the injection vacuum tail condenser; the atomizing nozzle and the injection nozzle share a set of injection liquid system.

12. The device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia according to claim 1, characterized in that The spray liquid cooler adopts a partition wall cooler, which is one or a combination of a shell and tube heat exchanger, a spiral plate heat exchanger, and a plate heat exchanger.

13. Use of the device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia as claimed in any one of claims 1 to 12 in producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia.

14. Use of the device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia according to claim 13 in producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia, characterized in that The cooling medium of the spray liquid cooler is circulating cooling water, which first passes through the spray liquid cooler for heat exchange and then reaches the cooling water inlet of the main condenser. All or part of the circulating cooling water of the main condenser is first used as the cooling medium of the spray liquid cooler.

15. Use of the device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia according to claim 13 in producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia, characterized in that The temperature of the injection liquid at the inlet of the tail condenser does not exceed 45°C.

16. Use of the device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia according to claim 13 in producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia, characterized in that The temperature of the circulating injection liquid discharged from the bottom of the tail condenser does not exceed 55°C.

17. Use of the device for producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia according to claim 13 in producing ammonium sulfate by neutralizing and crystallizing caprolactam rearrangement liquid with ammonia, characterized in that The injection liquid is formed by neutralizing one or both of the circulating feed liquid and ammonium sulfate mother liquor of the crystallizer with DTB, and mixing with the condensate of the tail condenser, and has a pH value of less than 7 and does not contain ammonium sulfate crystals; the condensate is produced by condensing the evaporated steam in the tail condenser; the circulating feed liquid refers to the slurry containing ammonium sulfate drawn from the middle of the crystallizer baffle area by the crystallizer circulating pump, and a pipeline is connected from the outlet pipeline of the crystallizer circulating pump to the injection liquid tank replenishment pipe to add circulating feed liquid to the injection liquid tank; the ammonium sulfate mother liquor is the ammonium sulfate mother liquor produced by the centrifugal process in the ammonium sulfate device, and is pumped to the inlet pipeline of the crystallizer circulating pump through the mother liquor pump, and is connected from the outlet pipeline of the mother liquor pump to the injection liquid tank replenishment pipe; the amount of circulating feed liquid added does not exceed the amount of condensate produced by the tail condenser.

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