• 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:
    A process and a device for treating urea solutions coming from synthesis reactors and containing in addition to the formed urea also free ammonia, water and unreacted ammonium carbammate having two steps wherein in the first step, a substantial amount of ammonia is distilled while ammonium carbammate is only partially decomposed, and in the second step, the bulk of carbammate is decomposed and the residual ammonia is distilled.
    公开号:SU1085506A3
    申请号:SU792789506
    申请日:1979-07-23
    公开日:1984-04-07
    发明作者:Пастормерло Примо
    申请人:Стамикарбон Б.В.(Фирма)；
    IPC主号:
    专利说明:

    2. A device for carrying out the method according to Claim 1, comprising a column with upper, lower and central parts, vertically installed tubes with open ends, mounted along the entire height of the central part of the column, a supply pipe for the initial solution, a branch pipe for exhaust gases connected to the upper part a column, a urea drainage pipe connected to the lower part of the column, and heat transfer and discharge pipes to the annular space of the central part of the column, characterized in that the column is provided with a vertically installed
    a partition mounted in the central part of the column over its entire height and dividing it into two sections, the supply pipe of the original paciBopa being connected to the lower section of the first section of the central part of the column.
    3. The device according to claim 2, about tl and so that the partition is made in the form of a hollow cylinder, mounted coaxially column.
    4. A device according to claim 2, wherein the partition is made flat, and both sections are located adjacent to each other.
    The invention relates to an improved iiiFicTBOBaHHOMy method for the processing of urea synthesis products from AmAI and carbon dioxide and to a device for its implementation. A known method of processing products of the synthesis of urea, the so-called stripping technologist, BKJmchagging of unconverted LND and CO /; in two successive stages with intermediate separation of gases by a downward current of the liquid in the second stage. In the known method, all NH required for. the synthesis of urea, is used before being fed into the reactor for the synthesis of urea as a stripping agent and is countercurrently prepared; it is fed into the reactor for the decomposition of a urea melt containing carbamate l. The disadvantages of this method are the following: a very large mass of gas is passed through the decomposition reactor, the size of which approaches a crush; the flooding of the column, the urea melt coming out of the decomposition reactor, contains a large amount of No. 1 and a certain amount of carbameg, and thus requires expensive equipment for further processing. A device for extracting urea from a solution of reaction products of ammonia and carbon dioxide, containing a column with upper, lower and central parts, vertically installed tubes with open pits, mounted along the entire height of the central part of the column, is known. a gas outlet pipe connected to the upper part of the column, a urea outlet pipe connected to the column bottom, and supply and exhaust pipelines, heat carrier to the annular space of the central part of the column 2. A disadvantage of the known device is the limited possibilities for increasing the productivity determined by the conditions for flooding the column. In addition, in this device it is necessary to use large quantities of a passivating agent to prevent corrosion on the heated surfaces of a large area of elements of the stainless steel device. The aim of the invention is to increase the efficiency of the process. The goal is achieved by the fact that according to the method of processing urea synthesis products, including the conversion of unconverted ammonia and carbon dioxide in two successive stages with intermediate separation of gases by a downstream liquid of the ammonium carbamate in the second stage, separation of . The first stage is conducted in a fluid stream, ascending inside heated heat exchange tubes. In a device for carrying out the method, comprising a column with upper, lower and central parts, vertically installed tubes with open ends, mounted along the entire height of the central part of the column, a supply solution supply pipe, a gas outlet connection connected to the top of the column, a solution discharge pipe urea,. connected to the lower part of the column, and the pipes for supplying and discharging the coolant into the annular space of the central part of the column, the column is provided with a vertically installed partition mounted in the central part of the column at its full height and dividing it into two sections, with the source solution supply pipe connected to the bottom section of the first section of the central part of the column. Moreover, the partition is made in the form of a hollow cylinder mounted coaxially with the column. In addition, the partition is made flat, and both sections are located adjacent to each other. Figure 1 shows the flow chart of the proposed method; FIG. 2 shows a device for performing the method / vertical section / in FIG. 3 — section A-A in FIG. 2; figure 4 - section bb in figure 2; Fig. 5 is an embodiment of the device, vertical section; Fig. 6 is a section bb-b in Fig. 5, Fig. 7 is a cut of G-D in Fig. 5. The main distinguishing feature of the proposed method is shown in figure 1. In the synthesis reactor 16, the NH and CO supplied react under pressure and at high temperature to form a UM urea melt (containing urea, ammonium carbamate, free NHa and other by-products). As a rule, excess NH is supplied to the reactor 16 in relation to the stoichiometric amount , the MIN solution, which flows into the lower part of the reactor 16, contains significant amounts of free NH and ammonium carbamate, decomposing as a result of thermal decomposition into HH and CO, which can then be recycled to the synthesis reactor 16. Typically, this reactor operates at high temperatures (e.g. 160-250 s) and at a pressure of, for example, 100-300 bar and at high ratios, e.g. in the range of 2.5: 10. The treatment of urea melts consists in thermal decomposition, carried out in the form of the following stages under critical conditions. At stages I, a significant amount of NH is distilled off from the urea solution and, at the same time, only a small amount of carbamate is subjected to decomposition. To do this, fresh CO can be supplied simultaneously with the urea melt. Stage I is fixed by a diagram block, in which the CM is fed from the reactor and which is distilled into a pair, which are regenerated and recycled to the reactor in the traditional way. The urea urea solution treated in this way is fed to the second treatment stage K, where the main mass of carbamate is decomposed (and the residual amount of NH4 is distilled off), preferably by stripping the uM countercurrently to COj. The gases formed as a result of the decomposition of the carbamate in stage II are regenerated and recycled to the reactor by traditional methods, the same happens with the residual distilled NH, and the UM urea solution, practically containing free NIi and carbamate, is fed through the line. The MIN solution obtained by the proposed method is practically not needed in additional processing in order to regenerate NH, j and CO. The steps of the process can be carried out at the same pressure, for example, at the pressure of the synthesis, but the process can also be carried out at different pressures that may differ from the pressure of the synthesis. -The proposed method can be carried out in very simple, efficient and cheap processing devices (Figures 2 and 3). A device for carrying out the method of the invention comprises a column 1 with upper a, central and lower b parts. Across the entire height of the central part of the column 1 vertically mounted tubes 2 are mounted with open ends. For the mounting of the tubes 2, upper 3 and lower 4 tube sheets are provided. In the upper part a of column 1 there is a gas collector 6, and in the lower b there is a liquid collector 5. The device is equipped with a supply solution supply pipe 7, a gas outlet pipe 8 connected to the upper part a of column 1, and urea removal pipe 9, connected to the lower part of the column 1. Corresponding pipes 10 and 11 are provided for supplying the coolant outlet to the shell side of the central part of the column. The column is equipped with a vertically installed partition 12 mounted in the central part of the column the height and dividing it into two sections - the first with and the second d. The feed pipe 7 of the original solution is connected to the lower section of the first section with in the central part of the column 1. The partition 12 can be made in the form of a hollow cylinder (Fig.2-4) mounted coaxially column1. The partition can also be made flat (Figs. 5-7), with both sections arranged side by side. The upper edge of the partition 12, located in the upper part a of the column 1, is a liquid overflow partition 13 in which slots can be made. In the lower part of column 1, there is an annular feeding space 14 located under the lower tube sheet 4. To supply gas-forming CO in the lower part of column 1, a nozzle 15 is provided with nozzles.
    . The device works as follows.
    A urea melt containing ammonium carbamate, free ammonia and water, and obtained in synthesis reactor 16, is fed through pipe 7 through nozzles into the annular feeding space 14.
    The melt inside the tubes 2 rises through the first zone of the upper part of the column and is heated by steam entering the annular space through the nozzle 10.
    The temperature of the heat carrier (steam) and the residence time of the melt are chosen so that, inside the tubes 2 of the first section, only a small part of the ammonium carbamate decomposes and most of the free ammonia is distilled off. Further, the urea melt moves inside the tubes 2 in the first section with a coil with vapors formed during the distillation of ammonia and the decomposition of ammonium carbamate. Here, the temperature of the tubes is 2-102,020 ° C, and the residence time of the urea melt is less than 50 seconds, preferably 3-12 seconds.
    At the top of the column, at the exit of the tubes 2 of the first section, the vapor (fiE, CO and H20) is separated from the urea melt. The vapors are collected in the steam manifold 6, the urea melt through the overflow partition 13 enters the second section d of the column and flows as a thin film along the inner surfaces of the tubes 2 into the lower part b of the column 1 countercurrently with a stream of fresh COg gas supplied from an external source ( not shown) through a nozzle 15 with nozzles or with vapors obtained in the second section d, when fresh CO is not supplied.
    As the urea melt moves inside the tubes 2 of the second section d in the form of a thin film and coolant (steam) is supplied to the annulus, good contact is maintained between the urea melt and the countercurrent moving fresh COg or -gas separated from the urea melt during downward movement and carbamate gogo ammonia and ammonia are completed mainly in the second section d.
    The process of processing high-purity urea melt is collected at the bottom of column 1 in a liquid manifold 5. This melt requires little or no additional processing.
    Figures 2-4 show an embodiment of the device in which
    The first and second sections are concentric, and Figures 5-7 show an embodiment in which the partition is flat and both sections are arranged adjacent to each other.
    Comparative example. A separating or stripping device used in traditional technology using carbon dioxide as a desorption agent is loaded with a melt of urea composition, kg: NL 45.33; CO2 29.33; urea 60 (1 kmol); 36. Total 170.66 kg. The conditions of operation of the synthesis reactor: molar ratio, is equal to: - 2.8, the yield of urea is 60%.
    In each of the two tubes, 1 kmol of treated urea is used, each tube having an inner diameter of 25 mm and a length of 6 m. To increase the yield in the synthesis reactor, which produces urea alloy $, supplied to the stripper, this reactor must be operated a molar ratio greater than 2.8 and equal to, for example, 4. However, in the case where the ratio, 4, the amount of gases released from the melt and passing through the device, increases and requires the use of tubes, which have a diameter greater than 25 mm (for example, D, 30 mm, and a shorter length (for example, L 4.3 m), which is necessary to avoid flooding the tubes and lower the total surface of the decomposing device in proportion to the increased output from 60 to 70%, i.e. at a ratio of 60/70. At a plant with a capacity of 1000 tons of urea per day, such a distillation requires an apparatus containing 1388 tubes.
    Example 1. In the case when using a two-stage method, it is possible to work with a decomposing device of the type in which the first decomposition zone is supplied with a melt of composition, kg: NH 63.13, CO 18.85, urea 60 (1 kmol ), 33.42. Only 175.40 kg. The conditions of operation of the synthesis reactor: the molar ratio is 4, the yield of urea is 70%, the pressure is 160 bar, the temperature is 190 ° C.
    With a flow of urea in each of the tubes equal to 1000 kg (tube diameter is, for example, 20 mm and length is 6 m), the number of tubes of the device for the separation of urea from the solution in the first tube with a plant with a capacity of 1000 Mt / day (694, 4 KMOL urea / h) is equal to 122.
    The first zone is heated by steam 5 at 200 ° C. The residence time of the urea solution in this zone is 3 seconds. The composition of the urea melt, which after the first treatment zone enters through the overflow partition 13 of the second zone of the decomposing device, kg: NH.J 39; COg 15.5; urea 60 (1 kmol); LO 29.3, Total 143.8 kg. When 22 kg of fresh stripped CO are supplied to the excretion device, the nozzle 15 (about 1/2 kmol of CO for each kmol of urea) is upwardly countercurrent relative to the downward flow of urea melt into the tubes of the second zone (heated to 200 ° C) is collected in the bottom bottom part of the urea melt, of the following composition, kg (wt.%): NH L (5); CO 1.6 (2); urea 60 (75), 14.4 (18) The urea melt then leaves pipe 9. The residence time of the melt in the second zone is 15 s. From the upper head of the device for release through the pipe 8, a stream of gas of the following composition comes out, kg: 59.13; CO 17.25 + 22, HgO 19. With a stream passing through each tube of the second zone equal to 100 kg, the tube has an internal diameter of 20 mm and a length of 6 mm, the number of tubes is 999. The total number of tubes for the first and second zones is 1121 In the apparatus used in the comparative example, for a known method (1388 tubes with a diameter of 25 mm), the weight reduction of the separation device is 27,000 kg, which gives a great monetary savings. This savings is calculated without taking into account the difference in output (70% in Example 1 according to the invention and 60% according to conventional technology avnitelnomu example). Given the increased yield, additional savings are obtained from reducing the amount of carbamate that needs to be decomposed. The results obtained above are also valid in the case when a boiling agent is not used (C02 0). The composition of the urea melt discharged from the nozzle 9, in the absence of fresh CO, kg (wt.%): NH 8 (9.4); CO 2,6 (3), urea 60 (70,1); Н20 15 (17,5), Example 2. Using the proposed method and device for its implementation (working at an editor pressure of 160 bar and a temperature of 20 ° C, isobaric loop), the composition of the urea melt at the outlet of the device is obtained for the second zone d ( heating to 200s), shown in the table. The residence times in the first and second zones are 5 and 15 s, respectively. Thus, according to example 1, the composition of the urea melt processed by the proposed method is the following: NHj 9.4%; urea 70.1% (in the absence of a countercurrent COg); MB 5%, urea 75% (with a small countercurrent of CO2). While by a known method, using ammonia as a stripping agent, the molten urea composition is discharged from the decomposition apparatus,%: NH.J 47.79, urea 39.41. Comparing the above compositions, it is clear that decomposition proceeds almost completely in the solution treated according to the invention in the carbamate decomposition reactor (and the residual amount of ammonia is negligible), whereas in the solution treated by a known method, the ammonia content is significant, and the urea content is relatively low and therefore, subsequent processing is required on expensive equipment to remove residual ammonia from the solution and return it to the synthesis reactor.
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    权利要求:
    Claims (4)
    [1]
    1. A method of processing urea synthesis products, including the separation of unconverted ammonia and carbon dioxide in two successive stages with intermediate gas separation by a downward flow of liquid - ammonium carbamate in the second stage, characterized in that, in order to increase the efficiency of the process, the allocation in the first the stages are carried out in a fluid flow rising inside the heated heat transfer tubes.
    NH 3 with g of FIG. one
    one f 'FROM g '' 16oneonefour
    10.85506
    [2]
    2. The device for implementing the method according to claim 1, containing a column with upper, lower and central parts, vertically mounted tubes with open ends mounted along the entire height of the central part of the column, a supply pipe for the initial solution, a gas discharge pipe connected to the upper part of the column , a urea outlet pipe connected to the bottom of the column, and pipes for supplying and discharging the coolant into the annulus of the central part of the column, characterized in that the column is equipped with a vertically mounted ne egorodkoy mounted in the central portion of the column throughout its height and dividing it into two sections, the starting solution feed pipe connected to the lower portion of the first section of the central portion to the Lonna.
    [3]
    3. The device according to claim 2, wherein the partition is made in the form of a | mounted hollow cylinder-axial column ..
    [4]
    4, The device according to claim 2, characterized in that the partition is made flat, and both sections are located next to each other.
    类似技术:
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    SU1085506A3|1984-04-07|Process and apparatus for processing products of urea synthesis
    US4410503A|1983-10-18|Process for the removal of urea, ammonia, and carbon dioxide from dilute aqueous solutions
    CA1053701A|1979-05-01|Integrated urea-ammonia process
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    EP0136764A2|1985-04-10|Process for the preparation of urea
    同族专利:
    公开号 | 公开日
    US4269997A|1981-05-26|
    FR2434145A1|1980-03-21|
    CA1127663A|1982-07-13|
    US4308234A|1981-12-29|
    MX151584A|1984-12-21|
    GB2028311A|1980-03-05|
    ATA507479A|1984-02-15|
    JPS60339B2|1985-01-07|
    GB2109257A|1983-06-02|
    GB2109257B|1983-09-28|
    IN151776B|1983-07-30|
    FR2434145B1|1984-11-30|
    NL7905726A|1980-01-28|
    DE2929998A1|1980-02-07|
    IT7826010D0|1978-07-24|
    IT1174366B|1987-07-01|
    AT375916B|1984-09-25|
    JPS5522674A|1980-02-18|
    ES482756A1|1980-04-16|
    GB2028311B|1983-02-09|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    RU2729068C2|2016-03-17|2020-08-04|Касале Са|Combined device for high pressure urea synthesis|US2345424A|1942-04-28|1944-03-28|Alfred G Pfeifer|Combination gauge|
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    BG35038A3|1977-05-05|1984-01-16|Montedison Spa,It|Method and installation for synthesis of urea|
    US4230669A|1978-07-17|1980-10-28|Pullman Incorporated|Radial ammonia converter|JPS5746954A|1980-09-05|1982-03-17|Mitsui Toatsu Chem Inc|Synthesis of urea|
    NL8102391A|1981-05-15|1982-12-01|Unie Van Kunstmestfab Bv|METHOD FOR EXTRACTING VALUABLE COMPONENTS FROM THE WASTE STREAMS OBTAINED IN THE URE PREPARATION.|
    IT1211125B|1981-10-16|1989-09-29|Ortu Francesco|NITROGEN COMPOUNDS. PROCESS FOR THE PREPARATION OF|
    DE3364579D1|1982-06-03|1986-08-28|Montedison Spa|Method for avoiding the corrosion of strippers in urea manufacturing plants|
    US4597946A|1985-04-30|1986-07-01|Uop Inc.|Vertical tube reactor with serial downward flow through a plurality of sets of particulate containing tubes|
    US4788108A|1987-06-15|1988-11-29|Ppg Industries, Inc.|Ultraviolet light curable compositions based on iminated unsaturated polyesters for application to porous substrates|
    CH679485A5|1989-12-29|1992-02-28|Ammonia Casale Sa|
    EP0891968B1|1997-06-26|2003-06-04|Urea Casale S.A.|Process for reducing the residual free ammonia emissions from an urea production plant|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    IT26010/78A|IT1174366B|1978-07-24|1978-07-24|CARBAMATE DECOMPOSITOR FOR INDUSTRIAL PRODUCTION OF UREA|
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