• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    Unreacted ammonium carbamate contained in urea synthesis effluent obtained by reacting ammonia and carbon dioxide at urea synthesis pressures and temperatures is recovered by a method comprising subjecting the urea synthesis effluent to a three-stage decomposition to decompose the unreacted ammonium carbamate in each stage, the first stage and the second stage of which are operated at a gauge pressure of at least 30 kg/cm2 and a gauge pressure of from 10 to 25 kg/cm2, respectively, absorbing the off-gas resulting from the second stage decomposition in an absorbent to form an aqueous solution of ammonium carbamate and unabsorbed gaseous ammonia, condensing the gaseous ammonia to form recovered liquid ammonia, and absorbing substantially all of the off-gas resulting from the first stage decomposition in the aqueous solution of ammonium carbamate to form recovered ammonium carbamate solution while removing the heat of absorption by indirect heat exchange with the recovered liquid ammonia pressurized to the urea synthesis pressure.
    公开号:SU1064863A3
    申请号:SU741998275
    申请日:1974-02-13
    公开日:1983-12-30
    发明作者:Иноуи Сигеру；Кимура Тецуо
    申请人:Мицуи Тоацу Кемикалз,Инкорпорейтед (Фирма)；
    IPC主号:
    专利说明:

    This invention relates to the production of urea from carbon dioxide and ammonia. A known method for producing urea from NHj and -CO2g includes three successive stages of decomposition of unreacted ammonium carbamate at a pressure of 40-120 kg / cm7 10-25 kg / cm and from atmospheric to 5 kg / cm, respectively, with the formation of exhaust gas at each stage, absorbed by the adsorbent to form ammonium carbonate solution and cooling unabsorbed ammonia gas into regenerated liquid ammonia and recycling ammonium carbonate solution and regenerated liquid ammonia to the urea synthesis zone. The disadvantages of this method are that the refrigerator clogs or corrodes when the NHj gas is liquefied with a condenser in case of incomplete removal of carbon dioxide, and the steam temperature is low, recoverable from the adsorption stage (vapor pressure 2 kg / cm; i). The goal is achieved according to the method of producing urea from ammonia and carbon dioxide, which includes three successive stages of decomposition of unreacted ammonium carbamate at a pressure of 40-120 kg / cm, 10-25 g / cm and atmospheric up to 5 kg / cm, respectively, with the formation of exhaust gas at each stage absorbed by the adsorbate with the formation of ammonium carbamate solution and cooling non-absorbing gaseous ammonia into regenerated liquid ammonia with recirculation of ammonium carbamate solution and regenerated liquid ammonia in the urea synthesis zone, the gas waste in the first decomposition stage, is cyclically adsorbed at a pressure of 40120 kg / cm with an adsorbent containing ammonium caromate and having a composition, wt.%: urea 11-12.7, ammonia 35.4-36, carbon dioxide Ode 27,7-32 and the rest is water, with removal of adsorption heat by external heat exchange with a mixture of 1 wt. regenerated liquid ammonia and 1.4-2.4 weight. additional liquid ammonia and the subsequent interaction of the mixture of the ammonium carbamate solution and liquid ammonia with carbon dioxide in an amount compensated carbon dioxide in the carbamate solution of gmmonium with simultaneous removal of the heat of reaction by external heat exchange. The drawing shows an installation for carrying out the method. The method is carried out as follows. Carbon dioxide, line 1, (see drawing) which is maintained at a pressure of urea synthesis (preferably a pressure of 150-300 kg / cm, liquid ammonia, line 2, which is also maintained at a pressure of synthesis of urea and preheated, as well as a regenerated solution of narbammate ak & Yuni, line 3, with a pressure of synthesis of urea, is sent, respectively, to a heat recovery zone 4. The latter is equipped with a cooler 5 to recover the excess heat of reaction in order to produce steam with a gauge pressure of 2-6 kg / cm. a, which is discharged in the heat recovery zone 5, depends on the temperature in the synthesis zone 6. The reaction mixture from the heat recovery zone 4 is then fed to the urea synthesis zone 6 to convert the ammonium carbamate to urea. C at a molar ratio of the total amount of ammonia and the total amount of carbon dioxide supplied to the synthesis zone 6. Pressure of the stream resulting from the synthesis of urea, which consists of urea, water, excess ammonia and unreacted ammonium carbamate No, it is brought up to 40-120 kg / cm through the reducing valve 7. Then, via line 8, it is fed to the high pressure separator 9. The flow after the synthesis of urea in the high-pressure separator 9 is maintained at a temperature of 130 ° C and preferably from 140 to 180 ° C by heating with the help of the heater 10, if necessary. In the separator 9, part of the excess ammonia and unreacted ammonium carbamate is separated from the stream leaving the urea synthesis stage (as a gaseous mixture containing ammonia, carbon dioxide and steam C from the exhaust gas 1, the unreacted ammonium carbamate decomposes, / s The pressure of the exhausted stream from the synthesis of urea from the high pressure separator 9 is reduced by means of a reducing valve 11 to 1025 kg / cm, and then the stream is introduced into the stripping column 12 of the average pressure through line 13. In column 12, the stream from the synthesis of ureas They are heated to 140-170 ° C by means of a heater 14 to decompose most of the unreacted ammonium carbamate and separate the waste gas containing ammonia, carbon dioxide and water vapor from this stream. The urea solution from column 12 is all
    it still contains unreacted ammonium carbamate in an amount of less than 10 wt.% Its pressure is additionally reduced by means of a reducing valve is to a gauge pressure of 0-5 kg / cm. The urea solution under reduced pressure is passed through line 16 and subjected to conventional distillation under reduced pressure (not shown) for separation of the remaining ammonium carbamate with its simultaneous decomposition from the urea solution to obtain a urea solution not containing ammonium carbamate and exhaust gas containing ammonia, carbon dioxide and vapor. The urea solution thus obtained is processed by any known method until urea is obtained in the form of crystals or a pelletized product.
    In parallel, the off-gas, which is released in the stripping column 12 of medium pressure, is fed via line 11 to the absorber 18 of medium pressure. Absorber 18 is introduced into absorber 18 (which may be a product of absorption by water, an aqueous solution of ammonia or an aqueous solution of urea waste gas during the distillation of a low pressure / through line 19 to absorb the waste gas. The absorption pressure is practically the same as in the average pressure distillation column. The absorption temperature at the base of the column 18 is maintained equal to RN-IO C. using a cooler 20. Excess gaseous ammonia not absorbed by the absorbent is then fed through line 21 to the ammonia condenser 22, in which ammonia gas is swept away with liquid ammonia, which is introduced into the ammonia condenser 22 through line 23. The mixture is cooled with water to 20-50 ° C by condensation. A part of the liquid ammonia that is formed in the aMMHa4HON {condenser 22 can be circulated to the top medium pressure absorption column 18 to reduce the temperature at the top of the column. The remaining liquid ammonia is reduced to a pressure at which urea is synthesized, using a pump 24 and then passed through a high pressure oxygen absorber column 26. Liquid ammonia is preheated and then fed to the heat recovery zone 4 via line 2.
    The gas escaping from the high pressure separator 9 is sent to the absorption column 26 of high dmcc flow along line 27. In the absorption column 26, the absorption product having a composition, weight, is introduced. %: urea 1112, 7, ammonia 35.4-36, carbon dioxide 27.7-32, the rest is water, which is removed from the absorber 18 of the medium pressure and brought to the pressure of the column 26 (for example, the pressure corresponding to the pressure in the separator 9 is high pressure) by means of a pump 28, as a result of which almost all the waste gas is absorbed by this absorption product. The heat of absorption released at this stage,. remove, passing liquid ammonia from condenser 22 through refrigeration 25, thereby preheating ammonia. Due to this cooling, the temperature of the high pressure absorption column is kept at 120180 ° C, preferably 130-160 ° C, while the temperature of the liquid ammonia rises from 100 to 160 ° C, preferably from 110 to 140 ° C. At the top of the high pressure absorber column 26, inert gases are mixed with a small amount of ammonia and carbon dioxide. The effluent gases are withdrawn through line 29 and introduced into the medium pressure absorption column 18 to recover either ammonia or carbon dioxide. Absorption column 26 is, for example, a vertical type heat exchanger or a combination of a horizontal type heat exchanger and a pilot column. With a vertical type of heat exchanger, no packed column is required. Moreover, the vertical heat exchanger is characterized by high absorption efficiency, which is very advantageous, since with the vertical type a greater temperature difference between the two heat exchange media is possible than with the horizontal type.
    The pressure of the absorption product from the base of the high-pressure absorption column 30 increases to the pressure of the urea synthesis process, and the absorption product under this pressure is fed via line 3 to the heat recovery zone 4.
    Example. The stream after urea synthesis from zone 6 of urea synthesis at 200 ° C and a manometric pressure of 200 kg / cm, containing, kg / h: urea 1153, ammonia 1150, carbon dioxide 340 and water 550, pass through the downstream valve 7 and line 8 and evaporated in a high pressure separator 9, operating under a pressure of 65 kg / cm. In separator 9, waste gas is released from the stream containing, kg / h, ammonia 370, carbon dioxide 55 and water 22. Depleted stream containing, kg / h: urea 1150, ammonia 782, carbon dioxide 285 and water 527, are supplied from the base of the separator 9 through a reducing-to valve 11 and line 13 to the stripping column 12 of medium pressure, which operates under the ma
    non-metric pressure of 17 kg / on. At the same time, most of the unreacted ammonium carbamate is isolated, in the form of a gas containing NH, to CO2. The separation from the current-depleted occurs by distillation. The resulting urea solution with residual ammonium carbamate is passed through a reduction valve 15 and line 16 to a low pressure stripping column (not shown), in which the residual ammonium carbamate is separated from the urea solution by distillation at atmospheric pressure. At the base of the stripping column V, Low Pressure, a portion of the starting carbon dioxide is fed in order to speed up the separation of a small amount of MN remaining in the bottom of the urea.
    The urea solution thus separated is concentrated and crystallized to obtain crystalline urea by separating it from the mother liquor. Exhaust gases released during the low and medium pressure stripping stages are absorbed by the resulting mother liquor, first in a low pressure absorption column (not shown and then in an average pressure absorption column 18 until the absorption product containing, kg / h: urea 114 11 is obtained wt.%, ammonia 370 (36.0 wt.%), carbon dioxide 333 (32 weight.% | and water 216.
    At the same time, unabsorbed ammonia gas is obtained in an amount of 418 kg / h.
    Gaseous ammonia, not absorbed in the absorption column 18 of medium pressure, is fed through line 21 to condenser 22 and mixed with 581 kg / h (weight ratio 1.4; 1 / additional ammonia, which is introduced through line 23. The mixture is cooled to liquefy, while the pressure of the absorption product obtained in the absorption column 18 of the medium pressure is increased to a gauge pressure of 65 kg / cm. The absorption product with this increased pressure is introduced into the 2o absorption column with a high pressure dp of absorption, the total off-gas supplied from separator 9 through line 27.
    In this way, a regenerated ammonium carbamate solution is obtained with 114 kg / h of urea, 740 kg / h of ammonia, 385 kg / h of carbon dioxide and 238 kg / h of water. The heat of absorption is removed by passing through the condenser 2 regenerated liquid ammonia from the high pressure distillation column 9. This regenerated liquid ammonia, K is liquefied in an ammonia condenser 22 and compressed to a gauge pressure of 230 kg / cm.
    pump 24. With the help of heat absorption, liquid liquid is heated to 110 G. The resulting regenerated ammonium carbamate solution is pressurized to 230 kg / cm using a pump 30, fed by
    3 in zone 4, the heat E) is heated, while the heated liquid ammonia is fed through line 2. In addition,
    717 kg / h COg is compressed to a gauge pressure of 230 kg / cm T1 is fed via line 1 to the heat recovery zone 4. The latter is equipped with a refrigerator 5, by means of which steam with a manometric pressure is produced.
    4 kg / cm in amount of O, 2 kg per 1 k of urea to recover part of the ammonium carbamate formation, as a result of which the temperature in the zone
    4 heat recovery is maintained at 178 ° C. The reaction mixture of the heat recovery zone 4 is introduced into the synthesis zone to convert the carbamate ammonia to urea.
    PRI mme R 2. The reaction mixture dp of urea synthesis, obtained under conditions of approximately 1, containing, kg / h: urea 1153, ammonia 1150, carbon dioxide 340, iodine 550, is subjected to instantaneous evaporation, pushing it through the reducing valve 7 and pipeline 8 to high pressure separator 9 operating at a pressure of 120 kg / cm | whereby the waste gas containing kg / h, ammonia 424, carbon dioxide 127 and water 32 is separated, and the solution for the synthesis of urea containing kg / h: urea 1150, ammonia 728, carbon dioxide 215 and water 517 is taken from the bottom parts of high pressure separator 9. After this, the solution is subjected to the treatments analogous to Example 1, in order to be separated in order to regenerate ammonia and carbon dioxide and to obtain urea in the form of crystals.
    Thus, using an absorber 18 operating under conditions of moderate pressure, an absorption liquid with a temperature of 10 ° C is obtained, containing kg / h: urea 114 (12.7 wt.%), Ammonia J2O (35, 6 wt.% 1 g dioxide carbon 258 (28.7% w / w 7. and water 206, while from condenser 22 to receive liquid ammonia in the amount of 995 kg / h, which is a mixture of regenerated ammonia and added ammonia in the amount of 581 kg / h (weight ratio 1.4: 1). Absorbing liquid from absorber 18 of average pressure after increasing pressure to 120 kg / cm in t in the high pressure absorption column 26, in which all the exhaust gases are absorbed from the high-pressure separator through line 27. As a result, a regenerated liquid is obtained, containing kg / h: urea 114, ammonia 744, carbon dioxide 385 and water 238. The heat of absorption at this stage is removed by passing, at a rate of 995 kg / h, liquid ammonia coming from an ammonia condenser, the pressure of which is brought to the pressure of the synthesis process, through the condenser 25 of the high pressure absorption column. Due to this, liquid ammonia enters in the amount of 995 kg / h and is heated to 140 ° C. The resulting regenerated liquid is brought to the synthesis pressure by pump 28 and fed to the heat recovery zone 4, which also serves preheated liquid ammonia and 717 kg / carbon dioxide, the pressure of which is also brought to the pressure of synthesis. Consequently, for 1 kg of urea it produces, with O, 36 kg / h of saturated water vapor with a pressure of .5 kg / cm, with which the temperature in the pipeline for the synthesis of urea (outlet) is maintained at 200 ° C. and measure 3. Urea solution, synthesized under the conditions of example 1, containing kg / h: urea 1153, f ammonia 1150, carbon dioxide 343. and water 550, are introduced into the high pressure separator 9 at a standard pressure of 40 kg / cm reducing valve 7 and line B. In the separator, the escaping gas containing, kg / h: 586 eiMmiak, carbon dioxide 80 and water 32.1, is separated from the solution and the temperature of the solution is lowered to. From the bottom of the high pressure separator 9, the reaction solution containing, kg / h: urea 1150, ammonia 568, carbon dioxide 252, and water 516.9 is discharged. The solution is subjected to treatment with analogous example 1 g where ammonia and water are separated and regenerated, and urea is obtained as crystals. Thus, the regenerated solution having a temperature containing, kg / g: urea 114, 111.9 wt.%, ammonia 338 (33.4 weight. carbon dioxide 295 (30.0 wt.%), water 205.9 is obtained in the absorption column 18 at an average pressure, and 815 kg / h of liquid ammonia containing regenerated ammonia mixed with 581 kg / h of a new portion of ammonia (weight ratio 2, 5: 1), get in the capacitor 22 ammonia. The pressure of the solution in the high-pressure absorption column 26, where the solution absorbs all the exhaust gas supplied via line 27 from the high-pressure separator, is maintained so as to obtain a regenerated solution having a temperature of 115 s and containing kg / h: urea 114, ammonia 924, dioxide carbon 385 and water 288. Heat absorption; the release is absorbed by passing 815 kg / h of liquid ammonia from the ammonia condenser and the pressure is brought to standard by passing 1247 kg / h of liquid ammonia from the liquid ammonia storage tank (not shown) through the cooler 25 into the absorption column 26 of the high pressure where liquid ammonia is preheated to | and the indicated 1247 kg / h of ammonia is used for subsequent heat exchange. The resulting regenerated solution is introduced into the heat recovery zone 4 along with 815 kg / h of pre-heated liquid ammonia. As a result, the temperature at the outlet nozzle is maintained equal to 200 ° C by generating saturated steam having a pressure of 5 kg / cm in an amount of O, 12. kg / h per 1 kg of urea. The advantage of the proposed method is the efficient use of heat-adsorption, as well as the fact that this process can be carried out in a relatively simple system, which has a high-pressure separator and a high-pressure absorption column.
    G T
    权利要求:
    Claims (1)
    [1]
    METHOD FOR PRODUCING UREA from carbon dioxide and ammonia, including three successive stages of decomposition of unreacted ammonium carbamate at a pressure of 40-
    120 kg / cm ^ 10-25 kg / cm 2 and the 'from atmospheric pressure to 5 kg / cm ^, respectively, to form the exhaust gas at each stage, the adsorbent absorbed' to form an ammonium carbamate solution and the cooling unabsorbed ammonia gas in regenerating liquid ammonia with Rowan by recirculating a solution of ammonium carbamate and regenerated liquid ammonia into the urea synthesis zone, which is related to the fact that, in order to increase the efficiency of the process, the gas leaving the first stage of RAE + deposition is adsorbed at a pressure of 40-120 kg / cm 2 adsorbent contains aschim ammonium carbamate and having a composition, wt.%: 11-12,7 urea, ammonia. 35.4-36, carbon dioxide 27.732, the rest is water, with the removal of heat of adsorption by external heat exchange with a mixture of 1 part by weight regenerated liquid ammonia and 1.4-2.4 parts by weight additional liquid ammonia and the subsequent interaction of the mixture of the resulting solution of ammonium carbamate and liquid ammonia with carbon dioxide in an amount that compensates for carbon dioxide in the ammonium carbamate solution with simultaneous removal of the reaction heat by external heat exchange.
    CX
    GO
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    US4365089A|1982-12-21|Synthesis of urea
    同族专利:
    公开号 | 公开日
    JPS5535378B2|1980-09-12|
    NL162636C|1980-06-16|
    FR2217320A1|1974-09-06|
    DE2407019B2|1976-08-19|
    JPS49102620A|1974-09-27|
    US3944605A|1976-03-16|
    ATA114874A|1977-10-15|
    PH11037A|1977-10-25|
    BR7401038D0|1974-09-10|
    ES422910A1|1976-05-01|
    NL162636B|1980-01-15|
    IT1007405B|1976-10-30|
    AT343670B|1978-06-12|
    EG11283A|1977-01-31|
    AR197541A1|1974-04-15|
    DE2407019A1|1974-09-12|
    IN140031B|1976-09-04|
    FR2217320B1|1978-01-06|
    CA1012981A|1977-06-28|
    NL7402055A|1974-08-16|
    AU6495274A|1975-07-31|
    GB1404115A|1975-08-28|
    引用文献:
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    US3573173A|1968-07-24|1971-03-30|Mitsui Toatsu Chemicals|Process for recovering excess ammonia in urea synthesis by direct contact condensation with liquid ammonia|JPS555977B2|1974-05-14|1980-02-12|
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    JPS585190B2|1975-09-22|1983-01-29|Mitsui Toatsu Chemicals|
    JPS5545071B2|1975-12-05|1980-11-15|
    IT1068268B|1976-09-09|1985-03-21|Snam Progetti|PROCEDURE FOR THE PRODUCTION OF UREA AND PURIFICATION OF WATERS|
    JPS5715832B2|1978-11-30|1982-04-01|
    JPS6215070B2|1981-10-16|1987-04-06|Mitsui Toatsu Chemicals|
    JPH0223700B2|1982-06-14|1990-05-25|Suzuki Motor Co|
    US5316554A|1992-06-03|1994-05-31|Hansen Charles N|Method for processing crystalline ammonium carbamate|
    US9863725B1|2012-02-29|2018-01-09|The United States Of America As Represented By The Secretary Of The Air Force|Systems and methods for thermal management through use of ammonium carbamate|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    JP1751873A|JPS5535378B2|1973-02-14|1973-02-14|
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