CN216778830U - Urea catalytic hydrolysis system of filler formula - Google Patents
Urea catalytic hydrolysis system of filler formula Download PDFInfo
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- CN216778830U CN216778830U CN202220376950.4U CN202220376950U CN216778830U CN 216778830 U CN216778830 U CN 216778830U CN 202220376950 U CN202220376950 U CN 202220376950U CN 216778830 U CN216778830 U CN 216778830U
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Abstract
The filler type urea catalytic hydrolysis system and method provided by the utility model have the advantages that the efficient heat exchange is realized, the hydrolysis reaction rate is improved, the inhibition effect of ammonia gas on the hydrolysis reaction is avoided, the hydrolysis effect of a high-concentration urea solution in a reaction kettle is improved, the structure is simple, and the economy is high. A heat exchanger and a filler area for placing a supported catalyst are arranged in the urea catalytic hydrolysis reaction kettle, a heat exchanger outlet, a urea solution inlet, a gas inlet and a circulating liquid outlet are arranged at the bottom of the urea catalytic hydrolysis reaction kettle, and the gas outlet is connected with the gas inlet through a circulating pipeline; the flash tank comprises a drain port, a desalting water port for feeding raw material desalted water, a steam outlet and a liquid water outlet; the urea dissolving tank is connected with a circulating liquid outlet of the urea catalytic hydrolysis reaction kettle, a liquid water outlet of the flash tank and a mixed solution inlet of the urea solution mixing tank respectively, and the urea solution mixing tank is also provided with a mixed solution outlet connected with the urea solution inlet of the urea catalytic hydrolysis reaction kettle.
Description
Technical Field
The utility model relates to the technical field of flue gas denitration of thermal power plants, in particular to a filler type urea catalytic hydrolysis system.
Background
In recent years, due to the attention on safety factors and potential risks, the urea ammonia production technology gradually replaces a liquid ammonia method and is used as a preparation method of reducing agent ammonia in the flue gas denitration technology of a thermal power plant. Wherein, the urea hydrolysis technology is mature and applied to the waste liquid recovery process of urea synthesis in the chemical industry, and the principle of urea hydrolysis is that NH is generated by the reaction of water at high temperature3And CO2CO (NH) at temperatures above 60 deg.C2)2The hydrolysis is started, the hydrolysis speed is accelerated when the temperature reaches 80 ℃, the hydrolysis speed tends to increase more rapidly when the temperature is higher than 145 ℃, and the hydrolysis is more violent in the boiling urea aqueous solution. The degree of urea hydrolysis depends on the reaction temperature, NH in solution3And CO2Content of (1), urineThe content of the elements and the residence time in the reactor.
In a reactor with a fixed volume, the hydrolysis reaction time cannot be ensured to be long enough, and the hydrolysis efficiency is influenced. In particular, the high-temperature urea solution continuously generates NH generated by hydrolysis in the hydrolysis reaction process3And CO2And free NH3Has the inhibiting effect on hydrolysis reaction, so that the high-concentration urea solution in the reactor can not be completely hydrolyzed in time. In addition, the heat required for heating the urea solution and the heat output by the urea hydrolysis reaction solution are not fully utilized for heat exchange, so that the energy consumption is not economical.
SUMMERY OF THE UTILITY MODEL
In order to solve the problems in the prior art, the utility model provides a filler type urea catalytic hydrolysis system, which realizes high-efficiency heat exchange, improves the hydrolysis reaction rate, avoids the inhibiting effect of NH3 on the hydrolysis reaction, improves the hydrolysis effect of a high-concentration urea solution in a reaction kettle, and has the advantages of simple structure and high economical efficiency.
In order to achieve the purpose, the utility model provides the following technical scheme:
a filler type urea catalytic hydrolysis system comprises a urea catalytic hydrolysis reaction kettle and a flash evaporation circulating device;
the top of the urea catalytic hydrolysis reaction kettle is provided with a gas outlet and a saturated steam inlet, the interior of the urea catalytic hydrolysis reaction kettle is provided with a heat exchanger and a filler area for placing a supported catalyst, the saturated steam inlet is connected with the heat exchanger inlet, the bottom of the urea catalytic hydrolysis reaction kettle is provided with a heat exchanger outlet, a urea solution inlet, a gas inlet and a circulating liquid outlet, and the gas outlet is connected with the gas inlet through a circulating pipeline;
the flash evaporation circulating device comprises a urea solution mixing tank, a urea dissolving tank and a flash evaporation tank;
the flash tank comprises a drain port, a desalting water port for feeding desalted water into the raw material, a steam outlet and a liquid water outlet, the drain port is connected with a heat exchanger outlet of the urea catalytic hydrolysis reaction kettle, and the steam outlet is provided with a steam check valve;
the urea dissolving tank is respectively provided with a first solution inlet connected with a circulating liquid outlet of the urea catalytic hydrolysis reaction kettle, a second solution inlet connected with a liquid water outlet of the flash tank, a third solution inlet used for feeding raw material urea solution, a solution outlet connected with a mixed solution inlet of the urea solution mixing tank and a urea dissolving tank steam inlet used for feeding steam;
the urea solution mixing tank is also provided with a mixed solution outlet connected with a urea solution inlet of the urea catalytic hydrolysis reaction kettle, and a filter is arranged on a connecting pipeline between the urea solution inlet and the mixed solution outlet.
Preferably, the steam outlet of the flash tank is connected with the steam inlet of the urea dissolving tank.
Preferably, the interior of the urea catalytic hydrolysis reaction kettle is divided into a filler area and a heat exchanger area containing a heat exchanger through a partition plate, wherein the filler area comprises a gas distribution device arranged at the bottom, a liquid distribution device arranged at the top and a filler layer arranged between the gas distribution device and the liquid distribution device.
Preferably, a support grid is arranged above the gas distribution device, and the support grid is arranged at an inclined angle.
Preferably, the urea solution mixing tank is further provided with an inlet for introducing the high-temperature urea solution, and the introducing pipeline is provided with a high-temperature urea solution flow valve and a high-temperature urea solution circulating pump.
Preferably, the packing is Raschig rings or pall rings made of stainless steel.
Preferably, the bottom of the urea catalytic hydrolysis reaction kettle is also provided with a drain outlet, and a filter screen is arranged at the outlet of the drain outlet.
Preferably, a flash evaporation desalted water flow valve and a flash evaporation desalted water pump are arranged on a connecting pipeline between the liquid water outlet of the flash tank and the second solution inlet of the urea dissolving tank;
and a urea solution flow valve and a urea solution circulating pump are arranged on a connecting pipeline between a mixed solution inlet of the urea solution mixing tank and a solution outlet of the urea dissolving tank.
Compared with the prior art, the utility model has the following beneficial effects:
the utility model provides a filler type urea catalytic hydrolysis system, which adopts a filler type urea catalytic hydrolysis reaction kettle, wherein a filler area is arranged in the urea catalytic hydrolysis reaction kettle, so that gas molecules of a urea solution and urea hydrolysis products are in gas-liquid two-phase contact on the surface of a liquid film formed on the surface of a filler loaded with a catalyst, and a filler structure with a high specific surface area ensures that the urea solution is uniformly bubbled, the heat and mass transfer is more effective, and the hydrolysis reaction is more complete. Simultaneously through setting up flash distillation circulating device, including the high temperature hydrophobic and the raw materials desalinized water that produce saturated steam after the heat transfer send to the flash tank in utilize latent heat flash evaporation to form high temperature saturated liquid water rapidly, carry to the urea dissolving tank in and send into the urea solution blending tank with raw materials urea solution and mix, behind the filter, the pump is sent into urea catalysis hydrolysis reation kettle, realize the high-efficient heat exchange of low temperature feeding and high temperature hydrolysis product material, reduced the energy consumption when reaching high-efficient heat exchange, the decomposition of urea has been accelerated, the risk that polymer generated in the urea hydrolysis reaction system has been reduced, the energy consumption is reduced, form a closed circulation circuit between whole flash distillation circulating device and the urea catalysis hydrolysis reation kettle simultaneously, can realize the recycle of solution and steam, the cost is saved, waste is reduced. Wherein, the hydrolysis gas phase product in the urea catalytic hydrolysis reaction kettle, and the mixed gas component comprises NH3、CO2、H2O is used as a gas component, the equilibrium partial pressure of a gas-phase component in contact with the urea solution tends to zero at the mixing temperature of low-temperature feeding and high-temperature materials, the equilibrium partial pressure of the gas phase is far less than that of a liquid-phase, and a volatile component is converted from the liquid phase to the gas phase to ensure that free NH in the liquid phase3Timely discharge, avoid the inhibiting effect on hydrolysis reaction and improve the hydrolysis effect of high-concentration urea solution in the reaction kettle.
Further, the generated hydrolysis gas-phase product is discharged from a gas outlet at the top, and then a part of the product is used as product gas to be sent to a boiler denitration system, a part of the gas is sent back to the urea catalytic hydrolysis reaction kettle from a gas inlet at the bottom, and enters a filler layer from bottom to top through a gas distributor to conduct heat transfer between gas phase and liquid phase, so that the solution is dissolved in the solutionThe gas phase of the sex gas and volatile substances is transferred, the gas molecules are separated in time, and free NH is avoided3The hydrolysis reaction is inhibited, so that the high-concentration urea solution in the reactor can not be hydrolyzed completely in time, and the hydrolysis efficiency is improved.
Drawings
FIG. 1 is a schematic diagram of the structure of a packed urea catalytic hydrolysis system according to the present invention.
In the figure, 1-saturated steam inlet, 2-heat exchanger outlet, 3-heating tube bundle, 4-urea solution inlet, 5-urea catalytic hydrolysis reaction kettle, 6-clapboard, 7-overflow weir, 8-liquid distributor, 9-packing layer, 10-gas distributor, 11-gas inlet, 12-circulating liquid outlet, 13-sewage outlet, 14-liquid level meter, 15-safety valve, 16-demister, 17-gas outlet, 18-mixed gas regulating valve, 19-product gas regulating valve, 20-gas regulating valve, 21-plug, 22-urea solution delivery pump, 23-saturated steam regulating valve, 24-sewage system, 25-high temperature urea solution flow valve, 26-high temperature urea solution circulating pump, 27-urea solution mixing tank, 28-urea dissolving tank, 29-desalted water, 30-flash tank, 31-flash tank liquid level meter, 32-blowdown ball valve, 33-flash desalted water flow valve, 34-flash desalted water pump, 35-urea solution flow valve, 36-urea solution circulating pump, 37-filter, 38-circulating liquid pump, 39-steam check valve, 40-steam outlet, 41-raw material urea solution, 42-raw material desalted water, 43-hydrophobic stop valve and 44-urea dissolving tank steam inlet.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
The utility model relates to a filler type urea catalytic hydrolysis system, which comprises a urea catalytic hydrolysis reaction kettle 5 and a flash evaporation circulating device;
the top of the urea catalytic hydrolysis reaction kettle 5 is provided with a gas outlet 17 and a saturated steam inlet 1, the interior of the urea catalytic hydrolysis reaction kettle is provided with a heat exchanger and a filler area for placing a supported catalyst, the saturated steam inlet 1 is connected with the heat exchanger inlet, the bottom of the urea catalytic hydrolysis reaction kettle 5 is provided with a heat exchanger outlet 2, a urea solution inlet 4, a gas inlet 11 and a circulating liquid outlet 12, and the gas outlet 17 is connected with the gas inlet 11 through a circulating pipeline;
the flash evaporation circulating device comprises a urea solution mixing tank 27, a urea dissolving tank 28 and a flash evaporation tank 30;
the flash tank 30 comprises a drain port, a desalted water port for feeding desalted water into the raw material, a steam outlet and a liquid water outlet, the drain port is connected with the heat exchanger outlet 2 of the urea catalytic hydrolysis reaction kettle 5, and the steam outlet is provided with a steam check valve 39;
the urea dissolving tank 28 is provided with a first solution inlet connected with the circulating liquid outlet 12 of the urea catalytic hydrolysis reaction kettle 5, a second solution inlet connected with the liquid water outlet of the flash tank 30, a third solution inlet for feeding raw material urea solution, a solution outlet connected with the mixed solution inlet of the urea solution mixing tank 27 and a urea dissolving tank steam inlet 44 for feeding steam;
the urea solution mixing tank 27 is also provided with a mixed solution outlet connected with the urea solution inlet 4 of the urea catalytic hydrolysis reaction kettle 5, and a filter 37 is arranged on a connecting pipeline between the urea solution inlet 4 and the mixed solution outlet.
The utility model provides a filler type urea catalytic hydrolysis system, which adopts a filler type urea catalytic hydrolysis reaction kettle 5, wherein a filler area is arranged in the urea catalytic hydrolysis reaction kettle 5, so that gas molecules of a urea solution and urea hydrolysate are in gas-liquid two-phase contact on the surface of a liquid film formed on the surface of a filler loaded with a catalyst, and a filler structure with high specific surface area ensures that the urea solution bubbles uniformly, the heat and mass transfer is more effective, and the hydrolysis reaction is more complete. Meanwhile, by arranging the flash evaporation circulating device, high-temperature hydrophobic water and raw material desalted water generated after saturated steam is subjected to heat exchange are sent to the flash tank 30, and high-temperature saturated liquid water is rapidly formed by latent heat flash evaporationAnd then, the urea solution is conveyed into the urea dissolving tank 28 and is mixed with the raw material urea solution in the urea solution mixing tank 27, the urea solution is pumped into the urea catalytic hydrolysis reaction kettle 5 after passing through the filter 37, the high-efficiency heat exchange of low-temperature feeding and high-temperature hydrolysis product materials is realized, the energy consumption is reduced while the high-efficiency heat exchange is realized, the decomposition of urea is accelerated, the risk of polymer generation in a urea hydrolysis reaction system is reduced, the energy consumption is reduced, meanwhile, a closed circulation loop is formed between the whole flash evaporation circulation device and the urea catalytic hydrolysis reaction kettle 5, the repeated cyclic utilization of the solution and steam can be realized, the cost is saved, and the waste is reduced. Wherein, the urea is catalyzed and hydrolyzed in the reaction kettle 5 to hydrolyze the gaseous products, and the mixed gas comprises NH3、CO2、H2O is used as a gas component, the equilibrium partial pressure of a gas-phase component contacted with the urea solution tends to zero at the temperature of mixing low-temperature feeding and high-temperature materials, the equilibrium partial pressure of the gas phase is far less than that of a liquid phase, and a volatile component is converted from the liquid phase to the gas phase, so that free NH in the liquid phase3Timely discharge, avoid the inhibiting action to the hydrolysis reaction, improve the hydrolysis effect of the high concentration urea solution in the reaction kettle.
Further, a steam outlet of the flash tank 30 is connected with a steam inlet of the urea dissolving tank 28, so that saturated steam obtained in the flash tank 30 can be recycled as a circulating medium of a heat exchange pipe to provide heat for the urea hydrolysis reaction.
Further, the urea catalytic hydrolysis reaction kettle 5 divides the interior of the urea catalytic hydrolysis reaction kettle 5 into a heat exchange area and a filling area through a partition plate 6 arranged at the bottom, and the top end of the partition plate 6 is provided with an overflow weir crest; a heat exchanger is arranged in the heat exchange area, and a urea solution inlet 4 is arranged at the bottom of the heat exchange area; the gas distributor, the supporting grid and the liquid distributor are sequentially arranged from the bottom to the top end of the partition plate 6 in the packing area, the side walls of the supporting grid, the liquid distributor, the partition plate 6 and the urea catalytic hydrolysis reaction kettle 5 jointly surround to form a packing layer 9 for placing packing with a high specific surface area structure, and a gas inlet 11 and a circulating liquid outlet 12 are arranged at the bottom of the packing area.
The support grid of the packing area is arranged above the gas distributor and plays a role of a packing support plate, the packing is placed on the support grid in a stacking mode, the liquid distributor is long and plays a role of a packing press plate, and the packing is prevented from entering the other side of the partition plate 6 along with the fluid.
The utility model is provided with a filler area in a urea catalytic hydrolysis reaction kettle 5, gas is introduced through a gas inlet 11 arranged at the bottom of the filler area, urea solution flows in from a urea solution inlet 4, and flows into the filler area filled with the filler along an overflow weir crest at the top end of a clapboard 6 after being provided with certain heat through a heat exchanger, the urea solution flows from top to bottom along the surface structure of the filler to form a liquid film which is dispersed in the introduced gas flowing continuously, the urea solution and the hydrolysate gas are converged in the packing layer 9, the gas-liquid two-phase contact surface is on the liquid film surface of the packing, and the packing structure with high specific surface area enables the gas-liquid two phases to be fully contacted, so that the area between two-phase fluid is increased, the heat transfer between the gas phase and the liquid phase of the urea hydrolysis is enhanced, the separation of the gas phase and the hydrolysis rate of the liquid phase are promoted, the catalytic effect of the urea hydrolysis is effectively improved, and the purpose of improving the hydrolysis reaction rate is achieved.
Preferably, the bottom of the urea catalytic hydrolysis reaction kettle 5 is also provided with a drain outlet 13, a filter screen is arranged at the outlet of the drain outlet 13, the support grid is arranged at an inclined angle, and the filler can slide out of the drain outlet 13 along the support grid with a certain inclined angle when the filler is taken out after the reaction is finished conveniently.
In this embodiment, the urea catalytic hydrolysis reaction kettle is a horizontal reaction kettle, and the heat exchanger is a tubular heat exchanger.
Preferably, the filler is a three-dimensional filler with different shapes and structures, Raschig rings with the same diameter and height or improved pall rings can be adopted, and the filler can roll with fluid better, wherein the common specification is 25-75mm in diameter and 2.5-9.5mm in wall thickness, the size of the sewage discharge diameter at the bottom of the urea catalytic hydrolysis reaction kettle 5 is considered, and the filler with a small specification is selected as much as possible to facilitate discharge.
Preferably, the filler is made of stainless steel.
Specifically, the filler is made of 316L stainless steel.
In this embodiment, a flash evaporation and desalination water flow valve and a flash evaporation and desalination water pump are arranged on a connection pipeline between the liquid water outlet of the flash tank 30 and the second solution inlet of the urea dissolving tank 28;
and a urea solution flow valve and a urea solution circulating pump are arranged on a connecting pipeline between a mixed solution inlet of the urea solution mixing tank 27 and a solution outlet of the urea dissolving tank 28.
The system of the present invention, when embodied, includes,
a urea solution is introduced into a urea solution inlet 4, the urea solution generates urea catalytic hydrolysis reaction on the surface of the filler loaded with the catalyst, and saturated steam is introduced into the heat exchange tube to provide heat for the urea hydrolysis reaction;
the generated hydrolysis gas-phase product is discharged through a gas outlet 17 at the top, and then a part of the product is taken as product gas to be sent to a boiler denitration system, a part of gas is conveyed back to the urea catalytic hydrolysis reaction kettle 5 through a gas inlet 11 at the bottom, and enters a packing layer 9 from bottom to top through a gas distributor to conduct heat transfer between gas phase and liquid phase, so that the dissolved gas and volatile substances in the solution are transferred to the gas phase, the gas molecules are separated in time, and free NH is avoided3The hydrolysis reaction is inhibited, so that the high-concentration urea solution in the reactor can not be completely hydrolyzed in time, and the hydrolysis efficiency is improved;
saturated steam enters from a drain port of the flash tank 30 in a high-temperature hydrophobic manner after heat exchange, and is flashed with introduced raw material desalted water in the flash tank 30 by latent heat to form saturated steam and saturated water, the saturated water is conveyed into the urea dissolving tank 28, is conveyed into the urea solution mixing tank 27 together with introduced circulating liquid and raw material urea solution, is mixed, is filtered by a filter, and is conveyed into the urea catalytic hydrolysis reaction kettle 5 from the urea solution inlet 4 to perform urea catalytic hydrolysis reaction continuously.
Further, cleaning the filler after the reaction is finished; the method comprises the steps of arranging a drain 13 at the bottom of a urea catalytic hydrolysis reaction kettle 5, taking out filler from the drain 13, soaking the filler in dilute hydrochloric acid at a certain temperature until the solution is transparent and the filler is free of impurities, washing the filler with distilled water for multiple times, and carrying out catalyst loading treatment on the filler after the washing is finished, such as a method of loading a liquid catalyst by using an immersion method or a method of spraying a catalyst coating on the surface, but not limited to. The filler can be taken out by-products in the hydrolysis of high-temperature and high-concentration urea to be cleaned and removed by irregular cleaning, and the problems of deposition and blockage of insoluble solid substances in the high-pressure hydrolysis process of the high-concentration urea and the like are solved to a certain extent
Further, the length of the liquid distributor is greater than the length of the gas distributor.
In this embodiment, one side of the heat exchange area of the urea catalytic hydrolysis reaction kettle 5 is provided with a protruding section with an inclined angle, and the inclined protruding section can increase a gas-phase product ascending path and increase the efficiency of gas-liquid separation.
Further, the circulating liquid outlet 12 is connected with the urea dissolving tank 28 through a pipeline, and part of the urea solution can be used as a return material and sent to the urea solution inlet 4 to be mixed for recycling, so that the cost is reduced, and the economical efficiency is improved.
Specifically, as shown in fig. 1, the utility model provides a packed urea catalytic hydrolysis system, a urea catalytic hydrolysis reaction kettle 5 is of a horizontal structure, a protruding section with a demister 16 is arranged at the top, a liquid level meter 14 is arranged at one end of the urea catalytic hydrolysis reaction kettle 5, a tubular heat exchanger is adopted as a heat exchanger, one end of a heating tube bundle 3 is fixed at one end of the urea catalytic hydrolysis reaction kettle 5 through a plug 21 and extends into the urea catalytic hydrolysis reaction kettle 5, the liquid level of urea solution in the kettle is kept higher than that of the heating tube bundle 3, a medium in a coil is circulating water vapor, saturated steam is introduced into the heating tube bundle 3 of the heat exchanger through a saturated steam inlet in a reaction process, heat of hydrolysis reaction is provided for the urea solution in the urea catalytic hydrolysis reaction kettle 5, and then high-temperature hydrophobic water formed by the saturated steam is sent out through a heat exchanger outlet 2.
A partition plate 6 is arranged in the urea catalytic hydrolysis reaction kettle 5, and a safety valve 15 is arranged at the top of the urea catalytic hydrolysis reaction kettle 5; the urea solution is sent into the urea catalytic hydrolysis reaction kettle 5 of the liquid level meter 14 through the urea solution delivery pump 22, the liquid level height is formed on one side of the clapboard, when the liquid level reaches the overflow weir crest 7, the urea solution enters the other side of the clapboard, and the urea solution enters the filler layer 9 from top to bottom through the liquid distributor 8; the hydrolysis gas phase product is delivered from an exhaust port 17 through a demister 16 at the top of the reaction kettle, a part of the hydrolysis gas phase product is delivered to a boiler denitration system through a product gas regulating valve 19 as a product gas through a mixed gas regulating valve 18, a part of the hydrolysis gas phase product is delivered to the urea catalytic hydrolysis reaction kettle 5 through a gas inlet 11 as a gas through a gas regulating valve 20, the hydrolysis gas phase product enters a packing layer 9 from bottom to top through a gas distributor 10, is dissolved with urea to generate gas-liquid two-phase heat and mass transfer, gas molecules are separated in time, the hydrolysis gas phase product is delivered out through the exhaust port 17 at the top of the urea catalytic hydrolysis reaction kettle 5, and a liquid phase is delivered to a urea solution mixing tank 27 through a circulating pump through a circulating liquid port 12, is mixed with fresh raw material liquid, is filtered and is delivered to the urea catalytic hydrolysis reaction kettle 5 again. The urea catalytic hydrolysis reaction kettle 5 is provided with a bottom sewage outlet 13, can discharge sewage in real time according to working conditions and send the sewage to a sewage system 24 for treatment, the filter screen intercepts the filler and discharges the sewage, when the catalyst needs to be cleaned and regenerated, the filter screen is drawn off, the filler is discharged from the drain along the slope and sent to the links of filler cleaning, catalyst regeneration and catalyst coating, a certain volume of filler is blown in by an air blowing mode, or the mixture of the water and the filler is conveyed to the filler layer 9, the mixture of the water and the filler is kept still for a period of time after reaching the liquid level of the liquid distributor 8, the filler is settled and stacked on the filler layer 9, a filter screen device is added at the sewage outlet 13 to discharge the input clear water, the urea catalytic hydrolysis reaction kettle 5 is normally operated, the normal condition of sewage discharge is not needed, feeding the urea solution in the sewage outlet 13 into a urea solution mixing tank 27 through a high-temperature urea solution flow valve 25 and a high-temperature urea solution circulating pump 26; the circulating liquid outlet 12 at the bottom of the urea catalytic hydrolysis reaction kettle 5 is sent into the urea dissolving tank 28, the desalted water 29 from the flash tank 30 passes through the flash desalted water flow valve 33 and the flash desalted water pump 34 and is sent into the urea dissolving tank 28, the urea solution fully dissolved with the raw material urea solution 41 passes through the urea solution flow valve 35 and the urea solution circulating pump 36 and is sent into the urea solution mixing tank 27, the fully mixed urea solution is further filtered through the filter 37 and is sent into the urea catalytic hydrolysis reaction kettle 5 from the urea solution inlet 4 through the circulating liquid pump 38 for hydrolysis reaction.
Saturated steam 1 from the temperature and pressure reduction station is sent to a heating tube bundle 3 of a urea catalytic hydrolysis reaction kettle 5 through a saturated steam regulating valve 23, and a urea solution undergoes hydrolysis reaction under the heating condition in the urea catalytic hydrolysis reaction kettle 5; high-temperature hydrophobic water after heat exchange enters the upper part of a flash tank 30 with a flash tank liquid level meter 31 from a high-temperature hydrophobic outlet 2 through a hydrophobic stop valve 43, a raw material desalted water 42 inlet is arranged at the lower part of the flash tank 30, saturated vapor and saturated water are quickly formed by latent heat flash evaporation, the vapor is sent out from a vapor outlet 40 through a vapor check valve 39 at the top of the flash tank 30, liquid water after flash evaporation is sent into a urea dissolving tank 28 with a urea dissolving tank vapor inlet 44 at the top as desalted water 29, and sewage is discharged from the bottom of the flash tank 30 through a blowdown ball valve 32.
The urea solution generates urea catalytic hydrolysis reaction on the surface of the filler impregnated with the liquid catalyst and the solid catalyst coating under the conditions of the operation temperature of about 150 ℃ and the operation pressure of 0.6MPa, and generates ammonia gas mixture through gas-liquid mass transfer enhanced by the surface of the filler.
Various cycles are realized in the present invention, including,
circulating the circulating liquid, pumping out the urea solution after heat and mass transfer with the gas phase through the packing layer as the circulating liquid, mixing and filtering the urea solution with fresh raw material liquid in a urea dissolving tank 28, and feeding the urea solution into a urea catalytic hydrolysis system again;
circulating sewage, discharging sewage in real time from a sewage outlet at the bottom of the reaction kettle according to working conditions, sending the sewage to a sewage system for treatment, sending the urea solution at the sewage outlet to a urea solution mixing tank 27 under the normal condition that the sewage does not need to be discharged, and sending the urea solution into a urea catalytic hydrolysis system after filtering;
circulating liquid, desalted water after flash evaporation and raw material urea solution are fully dissolved in a urea dissolving tank 28, and then are sent into a urea solution mixing tank 27 through a urea solution flow valve, a urea solution circulating pump and part of sewage, and are fully mixed, and then are sent into a hydrolysis reaction kettle through a filter for hydrolysis reaction.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the utility model, the scope of which is defined in the appended claims and their equivalents.
Claims (8)
1. A filling type urea catalytic hydrolysis system is characterized by comprising a urea catalytic hydrolysis reaction kettle (5) and a flash evaporation circulating device;
the top of the urea catalytic hydrolysis reaction kettle (5) is provided with a gas outlet (17) and a saturated steam inlet (1), the inside of the urea catalytic hydrolysis reaction kettle is provided with a heat exchanger and a filler area for placing a loaded catalyst, the saturated steam inlet (1) is connected with the inlet of the heat exchanger, the bottom of the urea catalytic hydrolysis reaction kettle (5) is provided with a heat exchanger outlet (2), a urea solution inlet (4), a gas inlet (11) and a circulating liquid outlet (12), and the gas outlet (17) is connected with the gas inlet (11) through a circulating pipeline;
the flash evaporation circulating device comprises a urea solution mixing tank (27), a urea dissolving tank (28) and a flash evaporation tank (30);
the flash tank (30) comprises a drain port, a desalted water port for feeding desalted water into the raw material, a steam outlet (40) and a liquid water outlet, the drain port is connected with the heat exchanger outlet (2) of the urea catalytic hydrolysis reaction kettle (5), and a steam check valve (39) is arranged at the steam outlet (40);
a first solution inlet connected with a circulating liquid outlet (12) of the urea catalytic hydrolysis reaction kettle (5), a second solution inlet connected with a liquid water outlet of the flash tank (30), a third solution inlet used for feeding raw material urea solution, a solution outlet connected with a mixed solution inlet of the urea solution mixing tank (27) and a urea dissolving tank steam inlet (44) used for feeding steam are respectively arranged on the urea dissolving tank (28);
a mixed solution outlet connected with a urea solution inlet (4) of the urea catalytic hydrolysis reaction kettle (5) is also arranged on the urea solution mixing tank (27), and a filter (37) is arranged on a connecting pipeline of the urea solution inlet (4) and the mixed solution outlet.
2. A packed urea catalytic hydrolysis system according to claim 1, characterized in that the steam outlet (40) of the flash tank (30) is connected to the urea dissolving tank steam inlet (44).
3. A packed urea catalytic hydrolysis system according to claim 1, wherein the inside of the urea catalytic hydrolysis reaction kettle (5) is divided into a packing area and a heat exchanger area containing a heat exchanger by a partition plate (6), and the packing area comprises a gas distribution device arranged at the bottom, a liquid distribution device arranged at the top and a packing layer (9) between the gas distribution device and the liquid distribution device.
4. The system of claim 3, wherein a support grid is disposed above the gas distribution device, and the support grid is disposed at an inclined angle.
5. The system for catalytic hydrolysis of urea with filler according to claim 1, wherein the urea solution mixing tank (27) is further provided with an inlet for introducing the high-temperature urea solution, and the introduction pipeline is provided with a high-temperature urea solution flow valve (25) and a high-temperature urea solution circulating pump (26).
6. The system of claim 1, wherein the packing is made of Raschig rings or pall rings made of stainless steel.
7. The filling type urea catalytic hydrolysis system as claimed in claim 1, wherein a drain outlet (13) is further provided at the bottom of the urea catalytic hydrolysis reaction kettle (5), and a filter screen is provided at an outlet of the drain outlet (13).
8. The system for catalytic hydrolysis of urea in packed form according to claim 1, characterized in that the connection line between the outlet of liquid water of the flash tank (30) and the inlet of the second solution of the urea dissolving tank (28) is provided with a flash desalted water flow valve (33) and a flash desalted water pump (34);
and a urea solution flow valve (35) and a urea solution circulating pump (36) are arranged on a connecting pipeline between a mixed solution inlet of the urea solution mixing tank (27) and a solution outlet of the urea dissolving tank (28).
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114505044A (en) * | 2022-02-23 | 2022-05-17 | 西安热工研究院有限公司 | Filling type urea catalytic hydrolysis system and method |
| CN116002716A (en) * | 2022-12-28 | 2023-04-25 | 华能沁北发电有限责任公司 | Zero-waste emission system and method for thermal power plant urea hydrothermal ammonia production |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114505044A (en) * | 2022-02-23 | 2022-05-17 | 西安热工研究院有限公司 | Filling type urea catalytic hydrolysis system and method |
| CN114505044B (en) * | 2022-02-23 | 2023-10-20 | 西安热工研究院有限公司 | Filling urea catalytic hydrolysis system and method |
| CN116002716A (en) * | 2022-12-28 | 2023-04-25 | 华能沁北发电有限责任公司 | Zero-waste emission system and method for thermal power plant urea hydrothermal ammonia production |
| CN116002716B (en) * | 2022-12-28 | 2024-05-28 | 华能沁北发电有限责任公司 | Zero-waste emission system and method for thermal power plant urea hydrothermal ammonia production |
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