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公开(公告)号：US4654442A
公开(公告)日：1987-03-31
申请号：US567047
申请日：1983-12-30
IPC分类号： C07C273/16 , C07C126/08
CPC分类号： C07C273/16
摘要： Biuret is removed from biuret-containing aqueous urea solutions in a multi-cycle process which involves sequential (A) removal of biuret by contact with an anion exchanger and (B) regeneration of the anion exchanger, in which method, in one or more cycles, the anion exchanger regenerant comprises an aqueous solution of a strong base which has been employed to regenerate the anion exchanger in a previous cycle. This procedure allows for recycling, and thus reuse, of the strong base regenerant which results in significant economy. Methods are also provided in which (A) one or both of the aqueous urea solution and regenerant have a relatively low calcium equivalent content, (B) a substantially non-alkaline regenerant is employed either as the only regenerant in one or more cycles or as a partial regenerant before regeneration with the strong base regenerant, (C) the carbonate content of one or more of the aqueous process streams is controlled and/or reduced, and/or (D) the concentration of biuret in the recycled strong base regenerant is periodically reduced. All of these factors contribute to process economy, anion exchanger life, and more efficient, less frequent regeneration.
摘要翻译： 在多循环过程中，从缩二脲水溶液中除去含脲脲水溶液，其涉及通过与阴离子交换剂接触而顺序地（A）除去缩二脲，和（B）阴离子交换剂的再生，其中以一个或多个循环 ，阴离子交换剂再生剂包括强碱的水溶液，其已用于在先前循环中再生阴离子交换剂。 该方法允许再次使用，从而重新使用强碱基再生剂，这导致显着的经济性。 还提供了其中（A）尿素水溶液和再生剂中的一种或两种具有相对低的钙当量含量的方法，（B）基本上非碱性的再生剂被用作一个或多个循环中的唯一再生剂，或作为 用强碱再生剂再生之前的部分再生剂，（C）一种或多种含水工艺流的碳酸盐含量被控制和/或减少，和/或（D）再循环的强碱再生剂中的缩二脲浓度是 定期减少。 所有这些因素都有助于过程经济性，阴离子交换寿命，更有效率，更不频繁的再生。
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公开(公告)号：US4645860A
公开(公告)日：1987-02-24
申请号：US732175
申请日：1985-05-07
IPC分类号： C07C273/18 , C07C275/62 , C07C126/08
CPC分类号： C07C273/189 , C07C275/62 , Y02P20/125
摘要： Methods are provided for recovering biuret from aqueous urea solutions and for producing relatively concentrated biuret-containing extracts which involve contacting a biuret-containing aqueous urea solution with the hydroxide ion form of an anion exchanger to retain at least a portion of the biuret on the exchanger, contacting the resulting biuret-containing ion exchanger with an aqueous extractant under conditions sufficient to form a biuret-containing extract, and contacting the resulting biuret-containing extract with the same or other biuret-containing anion exchanger in the same or subsequent cycles under conditions sufficient to increase the biuret concentration of the extract. The biuret-containing urea feed solution may also contain higher molecular weight urea condensation products, and the biuret can be selectively separated from such condensation products by the disclosed methods. Extracts containing about 1 weight percent biuret or more can be obtained from which biuret can be crystallized at temperatures above 0.degree. C., and purified biuret of as much as 99.9 percent plus purity can be obtained from solutions containing higher molecular weight urea condensation products such as triuret, melamine, ammelide, and/or others. An integrated process also is provided which involves heating urea at a temperature sufficient to form biuret (in the presence or absence of higher molecular weight urea condensation products) and recovering biuret from an aqueous solution of the resulting pyrolyzed urea as described.
摘要翻译： 提供了用于从尿素水溶液中回收缩二脲并用于生产相对浓缩的缩二脲的提取物的方法，其涉及使含缩二脲的尿素水溶液与阴离子交换剂的氢氧根离子形式接触，以将至少一部分缩二脲保留在交换器上 在足以形成含缩二脲的提取物的条件下使得到的含缩二脲离子交换剂与含水萃取剂接触，并在相同或随后的循环中将所得缩二脲萃取物与相同或其它缩二脲包含的阴离子交换剂在条件 足以增加提取物的缩二脲浓度。 含缩脲脲的尿素进料溶液还可以含有较高分子量的尿素缩合产物，并且通过所公开的方法可以将缩二脲与这种缩合产物选择性分离。 可以获得含有约1重量％缩二脲或更多的提取物，其中缩合物可以在高于0℃的温度下结晶，并且可以从含有较高分子量的脲缩合产物的溶液获得高达99.9％的纯度的纯化的缩二脲， 作为triuret，三聚氰胺，ammelide和/或其他。 还提供了一种综合方法，其包括在足以形成缩二脲（在存在或不存在较高分子量的脲缩合产物）的温度下加热尿素，并如所述从所得热解脲的水溶液中回收缩二脲。
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公开(公告)号：US4087513A
公开(公告)日：1978-05-02
申请号：US823883
申请日：1977-08-12
申请人： Lorenz P. Schell
发明人： Lorenz P. Schell
IPC分类号： C02F1/58 , C01B32/50 , C01C1/08 , C07C67/00 , C07C239/00 , C07C273/04 , C07C273/10 , C07C126/08
摘要： A process for hydrolyzing urea in waste water streams which comprises introducing a waste water stream containing urea into a carbon dioxide recovery system such as used in connection with the production of ammonia, and therein hydrolyzing substantially all of the urea in the waste water stream.
摘要翻译： 一种用于水解废水流中的尿素的方法，其包括将含有尿素的废水流引入二氧化碳回收系统中，例如与氨的生产相结合，并且在其中水解废水中的所有尿素。
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公开(公告)号：US4701555A
公开(公告)日：1987-10-20
申请号：US753692
申请日：1985-07-10
IPC分类号： C07C273/16 , C07C127/24 , C07C126/08
CPC分类号： C07C273/16
摘要： The biuret content of biuret-containing urea is reduced by contacting a solution or melt of biuret-containing urea with a polar adsorbent under conditions sufficient to remove at least a portion of biuret from the urea. The resulting biuret-containing adsorbent can be regenerated for further use by contact with a polar desorbent under conditions sufficient to desorb at least a portion of the biuret contained on the adsorbent. Optionally, biuret can be recovered by recovering the biuret-containing desorbent, and biuret concentration in the desorbent can be increased by recycling the biuret-containing desorbent into contact with biuret-containing adsorbents, and biuret can be recovered from the desorbent by low temperature crystallization.
摘要翻译： 通过在足以从尿素除去至少一部分缩二脲的条件下使含缩二脲的脲与极性吸附剂的溶液或熔体接触来降低缩二脲含脲的缩二脲含量。 所得到的含缩二脲合金的吸附剂可以在足以解吸吸附剂上所含的至少一部分缩二脲的条件下与极性解吸剂接触来再生再进一步使用。 任选地，可以通过回收含缩二脲的解吸剂来回收缩二脲，并且可以通过将含缩二脲的解吸剂再循环到与含缩二脲的吸附剂接触来提高解吸剂中的缩二脲浓度，并且可以通过低温结晶从解吸剂中回收缩二脲 。
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公开(公告)号：US4461913A
公开(公告)日：1984-07-24
申请号：US376809
申请日：1982-05-10
申请人： Harry T. Lewis , Ewell F. Dillard
发明人： Harry T. Lewis , Ewell F. Dillard
IPC分类号： C07F15/04 , C07C126/08 , C07C127/01
CPC分类号： C07F15/04
摘要： A two-stage continuous crystallization process for production of urea phosphate by reaction of impure wet-process orthophosphoric acid (about 54 percent P.sub.2 O.sub.5) and urea with simultaneous addition of a selected acidifying agent (sulfuric acid, hydrochloric acid, or phosphoric acid) to clarified mother liquor used as recycle in the process. Addition of the acidifying agent decreases pH in the crystallization process whereby the solubility of a contaminating water-insoluble iron phosphate-urea salt [FeH.sub.3 (PO.sub.4).sub.2.2CO(NH.sub.2).sub.2 ] is increased, purity of the crystalline urea phosphate product is improved significantly, and the useful storage life of the recycle mother liquor is prolonged.
摘要翻译： 通过不纯的湿法正磷酸（约54％P 2 O 5）和尿素的反应生产尿素磷酸盐的两阶段连续结晶方法，同时加入选定的酸化剂（硫酸，盐酸或磷酸）澄清 在这个过程中用作回收的母液。 酸化剂的添加降低了结晶过程中的pH值，由此污染的水不溶性磷酸铁 - 尿素盐[FeH 3（PO 4）2.2 CO（NH 2）2]的溶解度增加，结晶尿素磷酸盐产品的纯度显着提高 ，延长了循环母液的有效保存期。
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公开(公告)号：US4301299A
公开(公告)日：1981-11-17
申请号：US203595
申请日：1980-11-03
申请人： Shigeru Inoue , Hiroshi Ono
发明人： Shigeru Inoue , Hiroshi Ono
IPC分类号： C07C67/00 , C07C239/00 , C07C273/04 , C07C126/02 , C07C126/08
CPC分类号： C07C273/04
摘要： A process for synthesizing urea in which a urea synthesis effluent obtained by reacting carbon dioxide and ammonia at urea synthesis pressures and temperatures is subjected to stripping treatment with carbon dioxide under pressures substantially equal to urea synthesis pressures to separate the unreacted carbon dioxide and ammonia contained in the urea synthesis effluent as a gaseous mixture, and a sufficient amount of said gaseous mixture to maintain the urea synthesis temperatures at a predetermined level is recycled to the urea synthesis in the gaseous state, the balance being subjected to condensation to be recycled in the liquid state to the urea synthesis.
摘要翻译： 一种合成尿素的方法，其中通过使二氧化碳和氨在尿素合成压力和温度下反应而获得的尿素合成流出物在基本上等于尿素合成压力的压力下用二氧化碳进行汽提处理，以将未反应的二氧化碳和氨 作为气态混合物的尿素合成流出物和足够量的所述气态混合物以将尿素合成温度保持在预定水平，在气态下再循环到尿素合成中，余量经过冷凝再循环到液体中 状态到尿素合成。
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公开(公告)号：US4650901A
公开(公告)日：1987-03-17
申请号：US567099
申请日：1983-12-30
IPC分类号： C07C273/16 , C07C126/08
CPC分类号： C07C273/16
摘要： Methods are provided for removing biuret from biuret-containing aqueous urea solutions by contacting the biuret-containing urea solutions with the hydroxide ion form of an anion exchanger under anion exchange conditions in which methods one or more aqueous process streams are either formed from materials which are substantially or completely free of alkaline earth metal and/or carbonate impurities or which process streams are treated either before or during their use in the anion exchange process to reduce their content of contaminant alkaline earth metal and/or carbonate compounds. The anion exchanger can be washed and regenerated with one or more aqueous media including water, aqueous solutions of strong base, acidic chloride solutions, and/or other aqueous solutions, and either batch or continuous (fixed bed) contacting can be employed. The use of one or more aqueous process streams in such methods which have been prepared from aqueous media of relatively low alkaline earth metal and/or carbonate content or which are treated either before or during their use in the methods of this invention, markedly reduces the degree and rate of anion exchanger deactivation and the severity of regeneration required to restore anion exchanger activity and thereby markedly increases anion exchanger efficiency and useful life.
摘要翻译： 提供了用于通过在阴离子交换条件下使含缩脲脲的脲溶液与阴离子交换剂的氢氧根离子形式接触的方式来从含缩二脲水溶液中除去缩二脲，其中方法一种或多种含水工艺流由 基本上或完全不含碱土金属和/或碳酸盐杂质，或者在阴离子交换过程中使用之前或期间处理流，以降低其污染物碱土金属和/或碳酸盐化合物的含量。 阴离子交换剂可以用一种或多种含水介质洗涤和再生，包括水，强碱水溶液，酸性氯化物溶液和/或其它水溶液，并可以使用间歇或连续（固定床）接触。 在这样的方法中使用一种或多种水性工艺流，其由在相对低的碱土金属和/或碳酸盐含量的水性介质制备或者在本发明的方法使用之前或期间被处理的方法显着地减少了 阴离子交换剂失活的程度和速率以及恢复阴离子交换活性所需的再生的严重性，从而显着增加阴离子交换器的效率和使用寿命。
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公开(公告)号：US4616094A
公开(公告)日：1986-10-07
申请号：US568500
申请日：1984-01-05
IPC分类号： C07C273/10 , C07C67/00 , C07C239/00 , C07C273/12 , C07C273/16 , C07D251/62 , C07C126/08
CPC分类号： C07D251/62 , C07C273/12 , C07C273/16
摘要： A process for isolating liquid urea and its thermal decomposition products from the off-gas of melamine synthesis, which gas has been freed from melamine by fractional condensation and then been washed with molten urea, wherein the off-gas, containing 2-10 kg of melt per kg of pure gas, is passed at 8-30 m/sec tangentially into the upper part of an axially symmetrical separation zone. As a result of the rotation imparted to the gas/liquid mixture, the two phases are separated from one another, and both pass downward through the separation zone. The gas and liquid are separately taken off at the bottom end of the separation zone. The residence time of the gas mixture in the separation zone is not less than 0.5 second.
摘要翻译： 从三聚氰胺合成废气中分离液态尿素及其热分解产物的方法，该气体已经通过分级冷凝从三聚氰胺中脱除，然后用熔融的尿素洗涤，其中含有2-10kg 每千克纯净气体的熔体以8-30米/秒的切向通入轴向对称分离区的上部。 作为赋予气/液混合物的旋转的结果，两相彼此分离，两者都向下通过分离区。 气体和液体在分离区的底端分开脱落。 气体混合物在分离区中的停留时间不小于0.5秒。
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9.发明授权Method of selectively removing biuret from urea and compositions for use therein 失效选择性地从尿素中除去缩二脲的方法和用于其中的组合物
公开(公告)号：US4345099A
公开(公告)日：1982-08-17
申请号：US291428
申请日：1981-08-10
IPC分类号： C07C273/16 , C07C275/62 , C07C127/01 , C07C126/08
CPC分类号： C07C273/16 , C07C275/62
摘要： Biuret is selectively removed from urea by treating the urea in an aqueous solution at a pH above about 12.5 and a temperature between about 0.degree. C. and 100.degree. C. for a period of time sufficient to decompose at least a portion of the biuret. Solid urea compositions containing biuret and a strong base capable of selectively decomposing at least a portion of the biuret when the mixture is dissolved in water are also disclosed.
摘要翻译： 通过在高于约12.5的pH和约0℃至100℃的温度的水溶液中处理尿素来将尿素选择性地从尿素中除去一段足以分解至少一部分缩二脲的时间。 还公开了含有缩二脲和固体尿素组合物，当混合物溶于水中时，能够选择性分解缩二脲的至少一部分的强碱。
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公开(公告)号：US4168299A
公开(公告)日：1979-09-18
申请号：US888440
申请日：1978-03-20
申请人： Lorenz P. Schell
发明人： Lorenz P. Schell
IPC分类号： C01C1/08 , C01C1/10 , C02F1/02 , C07C126/08
CPC分类号： C02F1/025 , C01C1/086 , C01C1/10 , Y10S210/908
摘要： A method for hydrolyzing urea in aqueous solutions such as waste-water streams which comprises heating the aqueous solution containing urea in the presence of a catalytic amount of vanadium pentoxide for sufficient time and at sufficient temperatures to effect hydrolysis of substantially all of the urea to ammonia and carbon dioxide.
摘要翻译： 一种在诸如废水流的水溶液中水解尿素的方法，包括在催化量的五氧化二钒存在下加热含有尿素的水溶液足够的时间和足够的温度以实质上将所有尿素水解成氨 和二氧化碳。
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