• 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:
    Process for preparing urea in which,… in a synthesis zone, at a pressure of 125-350 bar and at the temperature belonging thereto, a urea synthesis solution containing carbamate and free ammonia is formed from carbon dioxide and an excess of ammonia,… in a first decomposition step, at synthesis pressure or lower, a part of the carbamate is decomposed by supply of heat and the gas phase obtained in this process is condensed in a first condensition zone,… in a second decomposition step, at a pressure of 4-40 bar, a further part of the carbamate still present is decomposed by supply of heat and the gas phase formed is separated off,… in a further step, the remaining carbamate is removed in the form of a gas mixture containing ammonia and carbon dioxide, and this gas mixture is processed to form a solution of ammonia and carbon dioxide in water,… and the remaining urea-containing solution is processed to form a concentrated urea solution. …<??>The urea solution to be concentrated is introduced into the tubes of a shell and tube heat exchanger, the gas mixture from the second decomposition step is led into the shell side of heat exchanger at the end opposite the place where the urea solution to be concentrated is fed, the solution of ammonia and carbon dioxide in water is fed to the said shell side at a place located between the inlet for the gas mixture and the inlet for the urea solution to be concentrated, and the condensate is discharged from the shell side at the end where the urea solution is led into the tubes.
    公开号:SU1450735A3
    申请号:SU843814605
    申请日:1984-11-12
    公开日:1989-01-07
    发明作者:Йонкерс Кес
    申请人:Уни Ван Кунстместфабрикен,Бв (Фирма)；
    IPC主号:
    专利说明:

    one
    The invention relates to a process for the preparation of ureas; from ammonia and carbon dioxide.
    The aim of the invention is to reduce the steam consumption at the evaporation stage: not a urea solution.
    The drawing shows a flow diagram of a device implementing the method.
    The diagram shows the synthesis zone 1, the first decomposition stage 2, for example, the desorption zone, the first condensation zone 3 and the scrubber 4. These nodes form part of the high-pressure apparatus for the synthesis of urea, where i maintain pressure, for example, 125-350 bar, valves 5 -7 expansion, heating zone 8, gas-liquid sepa
    3
    rators 9 and 10, storage vessel 11 for the urea solution to be evaporated, first 12 and second 13 evaporation stages, second condensation zone 14 and storage vessel 15 for the carbamate solution obtained in the heat exchange stage of the first evaporation stage, pump 16 for transfer the carbamatesorption and pass through line 28, expansion valve 5 where the pressure drops to 4-40 bar, for example, to about 24 bar, and through heating zone 8, where the reaction mixture is heated by heat exchange to 125-180 ° C, for example, to 165 ° C part of the carbamate that is still present a.
    The liquid solution and the liquid ejector 7. ig are decomposed into gas-liquid separation. Through line 18 and ejector 17, liquid ammonia is passed along with the carbamate solution supplied through line 19 from clamp 4 through line 20 to the first condensation zone 3. Through line- 21, gaseous gas is fed to the mixture from the desorption zone 2. This gas mixture is produced by passing desorption in zone 2 when heat is applied, the urea synthesis solution 2o passing through line 22 from synthesis zone 1 countercurrently to carbon dioxide, which is introduced into this zone through
    torus 9. From this separator, the formed gas phase, the mixture containing mainly ammonia, carbon dioxide and water vapor, is discharged through line 29 and the remaining liquid phase through line 30. Using the expansion valve 8, the pressure of the liquid phase decreases to 1 -10 bar, for example, up to about 7 bar, and the gas-liquid mixture formed in this process is fed to the gas-liquid separator 10. The gas phase released in it, i.e. a mixture containing mainly ammonia, carbon dioxide and water 9. From this separator, the formed gas phase, the mixture containing mainly ammonia, carbon dioxide and water vapor, is discharged through line 29 and the remaining liquid phase through line 30. Using the expansion valve 8, the pressure of the liquid phase is reduced to 1-10 bar, for example, to about 7 bar, and the gas-liquid mixture formed in this process is supplied to the gas-liquid separator 10. The gas phase released in it, i.e. a mixture containing mainly ammonia, carbon dioxide and water line 23.
    The first condensation zone may, on the 25th pair, pass through line 31 to
    For example, Oyt is designed as a ver-second condensation zone 14 and a conical tubular heat exchanger is denoted there to form a carb 735
    sorption and pass through line 28, expansion valve 5 where the pressure drops to 4-40 bar, for example, to about 24 bar, and through heating zone 8, where the reaction mixture is heated by heat exchange to 125-180 C, for example, to 165 ° C, and part of the carbamate that is still present.
    torus 9. From this separator, the formed gas phase, the mixture containing mainly ammonia, carbon dioxide and water vapor, is discharged through line 29 and the remaining liquid phase through line 30. Using the expansion valve 8, the pressure of the liquid phase decreases to 1 -10 bar, for example, up to about 7 bar, and the gas-liquid mixture formed in this process is fed to the gas-liquid separator 10. The gas phase released in it, i.e. mixture containing mainly ammonia, carbon dioxide and water
    The heat released in this zone when ammonium carbamate is produced is removed with the help of water that feeds the boiler, which in this process is converted into low pressure steam of 4-5 atm. The desorption zone can also be designed as a vertical tubular heat exchanger. Heat required for desorption is supplied in the form of high pressure steam, for example, 15-30 atm. The carbamate solution formed in the first condensation zone 3 and the uncondensed gas are fed to the synthesis zone 1 via line 24. In this zone, sufficient heat is generated with further condensation of ammonia and carbon dioxide to the urethane carbonate to meet the heat demand for endothermic conversion of carbamate to urea. Through line 25, a gas mixture not condensed in the synthesis zone and containing inert gases removed in the process with fresh ammonia and carbon dioxide, and possibly passivating air or oxygen, is introduced into the scrubber 4 where the ammonia and carbon dioxide present in the gas are washed with carbamate with a solution fed through line 26 / Inert gases out through line 27.
    The desorption solution for the synthesis of urea is withdrawn from zone 2 de
    B
    0
    about
    five
    0
    a mat solution using an aqueous solution, e.g. a condensate from the process, fed through line 32. The heat released by condensation is removed by means of cooling water. The liquid phase obtained in the gas-liquid separator 10 flows through line 33 and the expansion valve 8, where the pressure in the solution is released to atmospheric pressure or lower, for example, to approximately 0.6 bar, into the reservoir
    11dl storage. From the latter, the resulting solution containing, for example, 70 May,% urea, which still contains ammonia and carbon dioxide, is fed through a line to the first stage.
    12 pairing. Then, the urea solution, which is already concentrated to, for example, more than 90% by weight of urea, is passed through line 35 to the second stage 13 of evaporation. The heating zone in these evaporation stages for the process of the present invention is designed as a vertical shell-and-tube heat exchanger. It is also possible to use a horizontal shell-tube heat exchanger, but this requires a more complex device design. Water vapor obtained in two stages of evaporation containing small amounts of liquid urea, ammonia and carbon dioxide.
    after condensation, they are sent via line 36 and 37 respectively to an unrepresented process condensate treatment plant, similar to the gas phase discharged through line 38 from the storage tank 11.
    The heat required by the evaporation in the second stage 13 is evaporated by condensing low pressure steam. The heat required in the first stage 12 of evaporation is supplied during the condensation of the gas mixture discharged through line 29 from the gas-liquid separator 9. This gas mixture is passed into the shell side of the shell-and-tube heat exchanger in the first stage 12 of evaporation, to which the carbamate solution is fed from the second zone 14 condensation at the same time through line 33. Thus, the dew point of the gas mixture to be condensed rises. The carbamate solution also functions as a condensing agent and solvent for the gas mixture that is condensed.
    Preference is given to passing the gas-liquid mixture through the heating zone in a countercurrent to the urea solution, which must be evaporated. The carbamate solution formed in the annular space of the condenser is passed through line 36 to storage vessel 15, pressurized with a pump 16 and passed through line 26 to the top of scrubber 4 to remove ammonia and carbon dioxide from the inert gas mixture gases that escape from line 24 from zone 1 of the synthesis.
    One stripped off of the urea solution is withdrawn through line 37.
    If the heat that is released during condensation of the gas mixture supplied through line 29 is not enough to meet the total heat demand in the first evaporation stage, the shortage can be compensated for by low pressure steam condensation. B. In this case, the heating zone cover must be divided into two compartments.
    Example 1. When using the described process, urea is obtained in the proposed plant having a productivity of 1500 tons per day. The pressure in the high pressure section of the installation is 157.3 atm, in the second stage
    decomposition and in the annular space of the heater in the first stage of evaporation the pressure is 23.5 atm.
    25, 560 kg of NH, which contains 107 kg and which is preheated to, and 38681 kg of carbamate solution containing 16521 kg of COj, 13392 kg of NH, and 8228 kg of HjO are introduced into the high-pressure section of the installation. The temperature in the reaction zone is 183 C and the molar ratio N / C is 2.95. In the desorption zone, 1,79594 kg of urea synthesis solution are introduced and 48.133 kg of a gas mixture containing 46,079 kg of CO and otherwise inert gases, mainly air, are desorbed. 120,382 kg of urea, 29 kg of biuret, 15556 kg O CO are removed from the desorption zone. J, 13193 kg NHj, 27775 kg H ,, 0 and 27 kg of inert components. At the second stage of decomposition, the pressure of the desorbed solution for the synthesis of urea is reduced to 23.5 atm and the temperature of the mixture is adjusted to 165 ° C using heat exchange. Thus, 724,183 kg of gas mixture containing 14,681 kg COj, 7062 kg are obtained in a gas-liquid separator NH ,, 2413 kg and 27 kg inert. Its dew temperature is 148.5 C. Additionally, there are 96199 kg of the liquid phase containing 63539 kg of urea, 291 kg of biuret. , 876 kg COj, 6131 kg NH and 25362 kg. The pressure of the liquid phase is reduced to 6.9 atm and the resulting mixture is passed into a gas-liquid separator 9. Here 4392 kg of a gas mixture containing 552 kg COj, 2612 kg NHj, and 1228 kg are separated. The pressure of the remaining solution is further reduced to 0.65 atm, which gives 84663 kg of urea solution at a temperature consisting of 63477 kg of urea, 324 kg of biuret, g 24 kg COj, 593 kg NH, and 20245 kg NHg.
    The gas mixture obtained in the gas-liquid separator 9 is condensed in the second condensation zone using a carbamate solution formed during the condensate production process, with the carbamate solution containing 2059 kg of CO, 2875 kg of W, and 4623 kg. In the second condensation zone, 15750 kg of solution is obtained at a temperature that consists of 2611 kg of CO, 7289 kg of NH and 5850 kg. This solution is fed under the pressure of 23.5 atm together with the gas mixture from the gas-liquid separator to the upper part
    the intertubular space of the heating section of the first stage of the evaporation of a urea solution by countercurrent, which must be evaporated. The gas mixture is then condensed, and 38631 kg of carbamate solution is formed at a temperature of 124 ° C. The solution of urine. Wines are passed through the tubes of the heating section and are concentrated in this process and the expansion of the JQ stack leaves the heater at a temperature of 130 ° C. The composition of this solution is as follows, kg; urea 67874, biuret 425; NH, 216; 3379. On top of the first stage of evaporation, 17798 kg of 15 steam mixture is withdrawn, which consists of 16774 kg H, 0, 275 kg CO, 581 kg NHj, 23 kg of inert substances and 146 kg of urea. If heating the first stage. evaporation is carried out with low-pressure steam 20, it takes 18390 kg of steam with a pressure of 4 atm to obtain the same result.
    Example 2. Urea is produced in the proposed plant with a capacity of 1000 tons per day. Quantities are given in kg / hour. In the second stage of decomposition, where the pressure is 18 atm, a gas mixture containing 9440 kg CO ,,, 5680 kg NH, and 1810 kg 30 is obtained. The temperature of this gas mixture is 153 C, the dew point is 139 ° C. This gas. the mixture is condensed with the help of a solution of carbamate obtained at the third stage of decomposition, having a temperature of 45 ° C and containing 1470 CO., 4440 kg of Wn and 4470 kg of c. shell side of the shell-and-tube heat exchanger, which forms the heating section in the first stage of evaporation. The gas-Q mixture is introduced into the upper part of the annular space by a countercurrent to a solution containing urea, which must be evaporated and which contains 41667 kg of urea, 132 kg CO, 1343 kg NH, and 14639 kg. The solution containing urea, which passes through the tubes of the heating section, is concentrated using the heat generated there to 95% by weight of the urea solution and removed from the heating section with a temperature of 130 ° C. If heating of the first stage of evaporation is carried out with low pressure steam, then to obtain the same. the result requires 13100 kg of steam with 4 atm.,
    Example 3. Urea is produced in a plant with a capacity of 1000 tons / day. Pressure in the synthesis zone
    50

    0 Q
    0
    125 atm, temperature, and molar ratio H / CO 2.95. In the stripping zone of urea synthesis, the solution is stripped at a pressure of 125 bar with carbon dioxide. Quantities are indicated in kg / h. In the second decomposition zone, in which the pressure is maintained at 5 atm, a gas mixture containing 7.450 kg of CO, 4.720 kg of NH, and 3.540 kg is obtained. The temperature of this mixture is 129 ° C, its dew point is 115 ° C. This gas mixture is condensed with a carbamate solution with a temperature of 50 ° C, containing kg CO, 1.180 kg NH, and 2.550 kg from the shell side of the shell-and-tube heat exchanger, which forms the heating section of the first evaporation stage, moreover, this solution is fed into the housing at a point located between the inlet for the gas mixture and the inlet for feeding the urea solution to be concentrated. The gas mixture is fed to the upper part of the casing in countercurrent with a solution containing urea and intended for evaporation, which contains 41.667 kg of urea, 195 kg of CO, 1.80, kg of NH, and 15.050 kg. The urea-containing solution, which is passed through the pipes of the heating section, is concentrated due to the heat generated. An additional amount of 4120 kg of steam with a pressure of 4 atm is necessary to obtain a 95 wt.% Solution of urea with a temperature. If the heating of the first step is completely carried out with low pressure steam, then to achieve the same result, 13500 kg of steam with a pressure of 4 atm is necessary.
    Example 4. Urea receive proposed in the installation with a capacity of 1000 tons / day. The pressure in the synthesis zone is 220 atm, the temperature is 200 ° С, and the molar ratio is 4.0. The urea synthesis solution is stripped with COxj in the stripping zone, the pressure in which is maintained at 220 atm. Quantities are indicated in kg / h. In the second stage of decomposition, in which the pressure is maintained at 40 atm, a gas mixture containing 7.840 kg COj, 2.830 kg NH, and 630 kg is obtained. The temperature of this gas mixture is 165 ° C, its dew point is 153 s. This gas mixture is condensed with Pomjie carbamate solution with a temperature of 50 C, containing 9U
    At the same time, 5.875 kg of CO, 9.980 kg of NH and 8.870 kg of N20 in the casing are vertical to the shell-and-tube heat exchanger, which forms the heating section of the first stage, which has been designed. The solution is fed in an optimal area located between the inlet for the gas mixture and the inlet dp of the urea solution to be concentrated. The gas mixture is fed to the upper part of the casing side in countercurrent with a solution containing urea and subject to discharge, which contains 41.667 kg of urea, 165 kg CO, 1.268 kg NH, and 14.440 kg. The solution containing urea, which is passed through the pipes of the heating section, is concentrated due to the heat released in this case to 95% by weight of the urea solution, and it leaves the heating section at a temperature of 130 C. Thanks to the temperature difference between the internal

    With the casing and the inside of the Pro-25 93.7 C pipes containing 18.427 kg of CO, there is a good heat transfer and size. shell-and-tube heat exchanger may be less. If the first stage of evaporation is heated only with low pressure steam, 30 to achieve the same result will require 550 kg of steam with a pressure of 4 atm.
    PRI me R 5. Get urea
    16102 kg NHj, 12.529 kg and 21 urea, from the upper compartment of heating. In addition, another 45 kg of gases of a mixture containing 6.3 kg of CO, 9, III, 0.8 kg, the rest is HHep gas is discharged from this compartment.
    The output of 67.833 kg of urea concentrate solution at a rate of
    according to the proposed method, one-35 round of 122.5 C from the bottom of the beam
    The first stage 12 evaporation is designed and operates as a vertical shell-and-tube heat exchanger. The heating surface around the tubes is divided into ten compartments with 40 baffles, provided with holes to provide. good contact between liquid and gas phases. The real-: upward flow of the liquid phase and the gas phase through the compartments. 45
    The following data relates to a plant with a capacity of 1500 tons / day. Quantities are indicated in kg / h.
    35.414 kg of NHj and 45.863 kg of C0.j are supplied to the part of the installation that is working under high pressure. The pressure in this part of the high pressure, which is the synthesis zone, the first stage of decomposition, the zone of co-condensation, is 140 atm. The pressure in the second stage of decomposition and on the heating grounds of the first stage of decomposition is 17.7 atm. The pressure in the third stage of decomposition is 3.9 atm. Gas
    pipes. This solution contains 63,144 to urea, 264 kg of biuret. Oh, 02.kg COj, 4.7 kg NHj and 4420 kg of water.
    Thus, the proposed method allows to reduce the cost of steam by condensing NHj- and - containing the gas mixture under pressure of 5.18 and 40 atm. Corresponding to the heat exchange with a solution of urea (about 75% by weight of urea), which must be concentrated to 95% by weight urea solution at 13CfC This can be seen, for example, from a comparison and a well-known (heat transfer with the same flow direction) and the proposed methods (heat exchange in countercurrent, setting the dew point and adding an aqueous solution in the optimum part of the heat exchanger).
    At a pressure of 5 atm: 7940 kg / h of steam at a pressure of 4 atm; according to the proposed method - 4120 kg / h of steam under pressure5
    ten
    the mixture in the second stage of decomposition, containing 14.139 kg of CO, 8.711 kg of NH and 3.301 kg, is fed to the lower compartment of the heating zone surrounding the bundle of pipes. The temperature of this gas mixture is 158.6 C, its dew point is 143.4 ° C. When this mixture is heat exchanged with 86.623 kg of urea solution flowing down the tubes in the form of a film, which is fed at a temperature and which contains 63.525 kg of urea, 210 kg of biuret, 28 kg of CO, 377 kg of NHj, the rest is water, this gas mixture is cooled and condenses. Condensation and absorption of the gas mixture is continued with 20.944 kg of carbamate solution obtained from the third decomposition stage, containing 4.294 kg of CO, 7400 kg of NH, 9.229 kg and 21 kg of urea, which is fed to the third compartment of the heating surface at 47 s. 47,079 kg of carbamate solution is unloaded at a temperature of
    93.7 C, containing 18.427 kg CO,
    g
    16102 kg NHj, 12.529 kg and 21 kg of urea, from the upper compartment of the heating surface. In addition, another 45 kg of a gas mixture containing 6.3 kg CO, 9.1 kg W, 0.8 kg, the rest is HHepfT gas is unloaded from this compartment.
    Conclusion t 67,833 kg of a concentrated solution of urea at temperatrub. This solution contains 63.144 kg of urea, 264 kg of biuret. Oh, 02.kg COj, 4.7 kg NHj and 4420 kg of water.
    Thus, the proposed method allows to reduce the cost of steam during condensation of NHj-, and - containing gas mixture under pressure of 5.18 and 40 atm. During heat exchange with urea solution (about 75 wt.% Urea), which needs to be concentrated to 95 wt.% urea solution at 13CfC. This can be seen, for example, from a comparison of the known (heat exchange with the same flow direction) and the proposed methods (heat exchange in countercurrent, setting the dew point and adding an aqueous solution in the optimal part of the heat exchanger).
    At a pressure of 5 atm: 7940 kg / h of steam under a pressure of 4 atm; according to the proposed method - 4120 kg / h of steam under pressure should be O kg / h of steam; according to the przd-Q, and the gas mixture formed by the claimed method is O kg / h of steam.
    Due to the greater temperature difference in the proposed method between the inner part of the casing and the inner
    divided with the subsequent treatment of the urea solution by depressurizing to obtain a gas phase and condensing it with a carbamate solution, and also to obtain a 75% solution that is evaporated to 95%, so that, in order to reduce the flow rate the vapor in the evaporation stage, the urea solution to be evaporated are introduced inside the tube-tube heat exchanger tubes, the gas mixture from the second decomposition stage is fed into the urea solution in the heat exchanger casing, and the ammonia and carbon dioxide solution obtained after days of the decomposition stage, at 45-50 °, are fed to the middle part of the heat exchanger casing, and
    part of the pipe is 60 ° С compared to 15 54 ° С in the known method. In this case, in the proposed method, a reduction of 10% of the heat exchange surface can be realized.
    20
    权利要求:
    Claims (1)
    [1]
    Invention Formula
    The method of obtaining urea by synthesis from an excess of ammonia and carbon dioxide at a pressure of 125-220 atm 25 and a temperature of 180-200 s to obtain a solution of the synthesis of urea containing carbamate and free ammonia fed to the first stage of decomposition
    divided with the subsequent treatment of the urea solution by depressurizing to obtain a gas phase and condensing it with a carbamate solution, and also to obtain a 75% solution that is evaporated to 95%, so that, in order to reduce the flow rate the vapor in the evaporation stage, the urea solution to be evaporated are introduced inside the tube-tube heat exchanger tubes, the gas mixture from the second decomposition stage is fed into the urea solution in the heat exchanger casing, and the ammonia and carbon dioxide solution obtained after days of the decomposition stage, at 45-50 °, are fed to the middle part of the heat exchanger casing, and
    its quantity provides a point of pressure for the synthesis with the supply of heat of the gas mixture 115-153 C, and the condensate and condensation of the gas phase in the first condensation zone by feeding the urea solution to the second stage times27.
    Sat is discharged from the annular space at the end where the urea solution is introduced into the tubes.
    with the resulting gas mixture
    divided with the subsequent treatment of the urea solution by depressurizing to obtain a gas phase and condensing it with a carbamate solution, and also to obtain a 75% solution that is evaporated to 95%, so that, in order to reduce the flow rate the vapor in the evaporation stage, the urea solution to be evaporated are introduced inside the tube-tube heat exchanger tubes, the gas mixture from the second decomposition stage is fed into the urea solution in the heat exchanger casing, and the ammonia and carbon dioxide solution obtained after days of the decomposition stage, at 45-50 °, are fed to the middle part of the heat exchanger casing, and
    sy gas mixture 115-153 C, and
    Sat is discharged from the annular space at the end where the urea solution is introduced into the tubes.
    f3
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    同族专利:
    公开号 | 公开日
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    DD233124A5|1986-02-19|
    NO161315B|1989-04-24|
    CS249529B2|1987-03-12|
    IN162987B|1988-07-30|
    EP0145054B1|1988-03-23|
    IL73489A|1988-03-31|
    EG16095A|1988-01-31|
    EP0145054A2|1985-06-19|
    DE3470038D1|1988-04-28|
    ES537569A0|1985-10-16|
    AU3531484A|1985-05-23|
    US4801747A|1989-01-31|
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    BG45699A3|1989-07-14|
    HUT35636A|1985-07-29|
    NZ210148A|1987-07-31|
    MA20262A1|1985-07-01|
    PH20867A|1987-05-25|
    NO844516L|1985-05-14|
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    RO91348B|1987-05-01|
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    ZA848715B|1985-06-26|
    AT33132T|1988-04-15|
    PT79483A|1984-12-01|
    PL141369B1|1987-07-31|
    GR80927B|1985-02-11|
    AU569555B2|1988-02-04|
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    FI844426A0|1984-11-12|
    OA07860A|1986-11-20|
    ES8601114A1|1985-10-16|
    HU199405B|1990-02-28|
    NL8303888A|1985-06-03|
    JPS60166656A|1985-08-29|
    RO91348A|1987-04-30|
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    EP0145054A3|1985-07-03|
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    EP2153880A1|2008-07-31|2010-02-17|Urea Casale S.A.|Process and plant for the production of a urea solution for use in SCR process for reduction of Nox|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    NL8303888A|NL8303888A|1983-11-13|1983-11-13|METHOD FOR THE PREPARATION OF UREA.|
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