JPH082859B2 - Urea production method - Google Patents

Urea production method

Info

Publication number
JPH082859B2
JPH082859B2 JP62041054A JP4105487A JPH082859B2 JP H082859 B2 JPH082859 B2 JP H082859B2 JP 62041054 A JP62041054 A JP 62041054A JP 4105487 A JP4105487 A JP 4105487A JP H082859 B2 JPH082859 B2 JP H082859B2
Authority
JP
Japan
Prior art keywords
urea
synthesis
carbon dioxide
ammonia
stage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP62041054A
Other languages
Japanese (ja)
Other versions
JPS63208563A (en
Inventor
英嗣 藤井
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toyo Engineering Corp
Original Assignee
Toyo Engineering Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toyo Engineering Corp filed Critical Toyo Engineering Corp
Priority to JP62041054A priority Critical patent/JPH082859B2/en
Priority to IN135/CAL/88A priority patent/IN169023B/en
Priority to IDP283688A priority patent/ID800B/en
Priority to DE3805403A priority patent/DE3805403A1/en
Priority to BR8800751A priority patent/BR8800751A/en
Priority to PL1988270814A priority patent/PL152735B1/en
Publication of JPS63208563A publication Critical patent/JPS63208563A/en
Publication of JPH082859B2 publication Critical patent/JPH082859B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C273/00—Preparation of urea or its derivatives, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups
    • C07C273/02—Preparation of urea or its derivatives, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups of urea, its salts, complexes or addition compounds
    • C07C273/04—Preparation of urea or its derivatives, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups of urea, its salts, complexes or addition compounds from carbon dioxide and ammonia
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/141—Feedstock

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Description

【発明の詳細な説明】 ［発明が属する技術分野］ この発明は尿素製造プロセス中の合成工程に関する。
詳しくはa.（非ストリッピング式）溶液循環法からb.ス
トリッピング式への転換の際の合成工程の改良に関す
る。Description: TECHNICAL FIELD The present invention relates to synthetic steps in a urea production process.
Specifically, it relates to improvement of the synthetic process in the conversion from a. (Non-stripping type) solution circulation method to b. Stripping type.

［従来技術の問題点］ 尿素製造プロセスは大別して上述の二つがある。以前
は両者には合成条件に大きな違いがあった。即ち、合成
でのNH3/CO2（mol比）が、溶液循環法では約４てあり、
一方、旧来のストリッピング式では３以下であって、こ
のようにmol比を大きくするのは困難とされていた。し
かしその後技術の進歩とエネルギーの高騰により大きい
mol比でもストリッピング式が技術的に、経済的にも可
能になって来た。そこで溶液循環法をストリッピング式
に転換する場合が発生するようになった。この場合の問
題点の一つに両者では合成管の構造とその配置法に大き
な違いがあることである。すなわち、b.の場合合成管は
同一生産量ならばa.の場合より大きくかつ中にバッフル
プレートが装着されている。また、流体の出入口および
合成管の設置法もa.の場合と大いに異なる。このため転
換の際に、溶液循環法で使用していた合成管をb.に転用
するには種々の工夫が要る。合成管はプラント全体の中
では高価なユニットに属するのでプロセスをａからｂに
転換する場合、殊に増産を兼る場合、ａの合成管を利用
しようとする。現にａのプロセスでプラントが稼動して
いる場合には転換の際の停止による損失を最小限に止め
ねばならず、この考慮も必要である。この発明はこれら
を解決し最適な、合成工程の転換法を提供したものであ
る。[Problems of Prior Art] Urea production processes are roughly classified into the above two types. Previously there was a big difference in the synthesis conditions between the two. That is, the NH 3 / CO 2 (mol ratio) in the synthesis is about 4 in the solution circulation method,
On the other hand, the conventional stripping method has a value of 3 or less, and it has been considered difficult to increase the mol ratio in this way. But later on due to technological advances and soaring energy
Even with the mol ratio, stripping has become technically and economically feasible. Therefore, the solution circulation method has been changed to the stripping method. One of the problems in this case is that there is a big difference between the structure of the synthetic tube and the method of arranging them. That is, in the case of b., The synthetic tube is larger than in the case of a. Also, the method of installing the fluid inlet / outlet and the synthetic tube is very different from the case of a. For this reason, when converting, the synthetic tube used in the solution circulation method needs to be converted to b. Since the synthesis pipe belongs to an expensive unit in the whole plant, when the process is converted from a to b, particularly when the production is also increased, the synthesis pipe of a is used. When the plant is actually operating in the process a, the loss due to the shutdown at the time of conversion must be minimized, and this consideration is necessary. The present invention solves these problems and provides an optimum method for converting synthetic steps.

［発明とその構成］ この発明はアンモニアと二酸化炭素から尿素合成に適
した圧力、温度の合成工程で得られた該尿素、未反応ア
ンモニア、二酸化炭素を含む尿素合成液を、先ず同圧力
下での二酸化炭素ガスによるストリッピング工程に付し
て該未反応物の一部をガス状にて分離し、次いで残った
尿素合成液を減圧し少なくとも一段の未反応物分離工程
に付して該尿素合成液中の未反応物の実質全部をガス状
に分離し尿素水溶液を得、一方、かくして、ストリッピ
ング工程より後の分離工程から、回収された未反応物の
溶液を該合成工程の圧力に昇圧し凝縮工程に付しストリ
ッピング工程からの未反応物およびストリッピングに用
いた二酸化炭素との混合ガスをこれに凝縮せしめ得られ
る凝縮液および未凝縮ガスを該合成工程に循環せしめる
尿素製造プロセスにおいて、該合成工程の圧力に昇圧さ
れた先の未反応物溶液を該凝縮工程に付すに先だち、少
なくともその一部を新規供給二酸化炭素ガスおよびアン
モニアの各一部と共に、尿素合成条件に保ち尿素を合成
せしめて後、該凝縮工程に付すことを特徴とした尿素製
造方法である。ａ用の合成管とｂ用の合成管の組み合せ
方法は直列、並列、そして直列でもその順序に応じてい
ろいろな配置法が考えられる。それらについて技術的、
経済的および改造時の休業損失などを検討の結果、直列
でａ用の合成管を前に設置するこの発明の方法に至った
のである。この前段の合成（以後前段合成または前段合
成管と称する）のうち、圧力は後段の合成のそれと実質
同じであるが、温度は許容される限り低い方が好まし
い。その理由は、ここに送入される新規供給二酸化炭素
ガスはなるべく少なくしストリッピングに使用した方が
良いからである。ここに送入される未反応物溶液が一部
であるのは同じ理由による。このためここに送入される
新規供給二酸化炭素ガスは全新規供給二酸化炭素ガスの
５〜15％（重量）とされる。このように少ないので前段
合成におけるH2O/CO2（mol比）は通常より大きくなり合
成率低下を来たす。そのために、ここに送入される新規
供給アンモニアは、この合成率低下を補償する程度に多
くすることが好ましいので全新規供給アンモニアの30〜
50％（重量）とする。これらの結果、この前段合成での
NH3/CO2（mol比）＝3.5〜5.0、温度は、新規供給アンモ
ニアの予熱によっても調節され、175〜185℃となる。こ
のような合成条件によって得られた前段の尿素合成液は
尿素25〜35％（重量）を含む。この合成液は次いで後記
カバメート凝縮工程に付しストリッピング工程からの混
合ガスを凝縮せしめる。この後は通常のストリッピング
式プロセスでの合成工程への循環と全く同じである。た
だしこの発明でのｂ用合成管は後段になっている。[Invention and Its Structure] This invention is to prepare a urea synthesis solution containing urea, unreacted ammonia, and carbon dioxide obtained in the synthesis process at a pressure and temperature suitable for urea synthesis from ammonia and carbon dioxide under the same pressure. Part of the unreacted material is separated into a gas by a stripping step using carbon dioxide gas, and the remaining urea synthesis solution is decompressed and subjected to at least one unreacted material separation step Substantially all of the unreacted material in the synthesis solution is separated into a gas to obtain an aqueous urea solution, and thus the solution of the unreacted material recovered from the separation step after the stripping step is used as the pressure of the synthesis step. The unreacted substances from the stripping process and the mixed gas with the carbon dioxide used for the stripping are condensed and condensed in this, and the obtained condensate and uncondensed gas are circulated to the synthesis process. In the urea production process, prior to subjecting the unreacted material solution whose pressure has been increased to the pressure of the synthesis step to the condensation step, at least a part thereof together with a part of newly supplied carbon dioxide gas and ammonia and urea synthesis conditions. The method for producing urea is characterized in that after the urea is kept in the above condition and the urea is synthesized, the condensation step is performed. As a combination method of the synthetic tube for a and the synthetic tube for b, various arrangement methods can be considered in series, in parallel, and even in series depending on the order. Technical about them,
As a result of studying economically and loss of work at the time of remodeling, the method of the present invention in which a synthetic tube for a was installed in series was reached. In the former stage synthesis (hereinafter referred to as the former stage synthesis or former stage synthesis tube), the pressure is substantially the same as that of the latter stage synthesis, but the temperature is preferably as low as possible. The reason is that it is better to reduce the amount of newly supplied carbon dioxide gas fed into here and use it for stripping. The unreacted material solution fed into this is a part for the same reason. For this reason, the newly supplied carbon dioxide gas fed into this is 5 to 15% (weight) of the total newly supplied carbon dioxide gas. Since it is so small, the H 2 O / CO 2 (mol ratio) in the first-stage synthesis becomes larger than usual, resulting in a lower synthesis rate. For this reason, it is preferable that the amount of newly supplied ammonia fed into this is large enough to compensate for this decrease in the synthesis rate.
50% (by weight). As a result of these,
NH 3 / CO 2 (mol ratio) = 3.5-5.0, the temperature is adjusted to 175-185 ° C. by adjusting the preheating of the newly supplied ammonia. The pre-stage urea synthesis solution obtained under such synthesis conditions contains 25 to 35% (by weight) of urea. This synthetic solution is then subjected to a cabamate condensing step described below to condense the mixed gas from the stripping step. After this, it is exactly the same as the circulation to the synthesis step in the usual stripping type process. However, the synthetic tube for b in this invention is in the latter stage.

次にこの発明を図に従って説明する。11は前段合成
管、12は後段合成管、13はストリッパー、14、14′はカ
ーバメート凝縮器である。圧力160〜180kg/cm2G、温度1
85〜195℃の後段合成管12で、平衡値近くまで合成され
た尿素を含む合成液は下降管39を通って同圧のストリッ
パー13の頂部に入り、ライン35により底部に吹き込まれ
る新規供給二酸化炭素ガス（の75〜95％（重量））と加
熱下、向流的に接触して、その合成液に含まれる未反応
アンモニア、二酸化炭素の一部が吹き込まれた二酸化炭
素ガスとともに塔頂より分離される。残留未反応物が20
〜30％（重量）となった温度175〜185℃の合成液は減圧
弁21により14〜20kg/cm2Gに減圧されてカーバメート凝
縮器14′のシェル側に入ってチューブ側で発生する凝縮
熱を受け、さらに残留未反応物の少なくとも一部を気化
する。この後は、気液分離するか、必要に応じさらにス
チームで加熱され合成液中の残留未反応物を減らす。こ
の工程で分離される未反応物ガスは対応する（高圧）吸
収工程にて吸収される。この圧力段階以降の合成液およ
び未反応物の処理は周知の方法に従う。Next, the present invention will be described with reference to the drawings. Reference numeral 11 is a front-stage synthesis tube, 12 is a rear-stage synthesis tube, 13 is a stripper, and 14 and 14 'are carbamate condensers. Pressure 160-180kg / cm 2 G, temperature 1
In the latter stage synthesis tube 12 at 85 to 195 ° C., the synthesis solution containing urea synthesized to near the equilibrium value enters the top of the stripper 13 at the same pressure through the downcomer 39, and is fed to the bottom by the line 35. From the top of the tower together with the carbon dioxide (75-95% (weight)) of the carbon dioxide gas (75-95% (by weight)) of the carbon dioxide gas, which comes into countercurrent contact with the carbon dioxide gas by blowing in a part of the unreacted ammonia and carbon dioxide contained in the synthesis solution. To be separated. 20 unreacted residues
The synthetic solution with a temperature of 175 to 185 ° C that has reached ~ 30% (by weight) is depressurized to 14 to 20 kg / cm 2 G by the decompression valve 21, enters the shell side of the carbamate condenser 14 ′, and is condensed on the tube side. It receives heat and further vaporizes at least part of the residual unreacted material. After this, gas-liquid separation is carried out or, if necessary, it is further heated by steam to reduce residual unreacted substances in the synthesis liquid. The unreacted gas separated in this step is absorbed in the corresponding (high pressure) absorption step. Treatment of the synthesis solution and unreacted materials after this pressure step follows well-known methods.

ストリッピング工程より後の工程から得られた未反応
物の回収液（カーバメート水溶液）−ライン42−はポン
プ３により先の合成圧力まで昇圧されて、その一部（50
〜70％）はライン43を経てガス洗滌器15に供給され、残
り（30〜50％）はライン44を経て前段合成管11に送入さ
れる。同時に新規供給二酸化炭素ガスの一部（５〜15％
（重量））および120〜160℃に予熱された新規供給アン
モニアの一部（30〜50％（重量））も送入される。ここ
で先に述べた合成条件下、尿素が平衡値の90〜96％まで
合成される。こうして得られた前段合成液はライン37を
経てカーバメート凝縮器14′のチューブ側に入りライン
48を経て入って来るストリッパーからの混合ガスと接触
しこの混合ガスの少くとも一部が凝縮する。その際、発
生する凝縮熱は、先述のごとく未反応物の分離に回収利
用される。一方、ガス洗滌器15に挿入された一部の未反
応物回収液は、後段合成管12の頂部から分離されるイナ
−トガスに同伴するアンモニア、二酸化炭素ガスを吸収
してライン46を経てカーバメート凝縮器14のシェル側に
入り、14′に於けると同様に、これにストリッパーから
の混合ガスの少くとも一部が凝縮する。カーバメート凝
縮器14、14′からの気液混合流はライン38を経て後段合
成管12の底部に入る。同時に残りの新規供給アンモニア
−ライン32−も挿入される。後段合成管12は通常のスト
リッピング式プロセスの合成条件に保たれる。The unreacted material recovery liquid (carbamate aqueous solution) -line 42-obtained from the step after the stripping step is boosted to the previous synthetic pressure by the pump 3, and a part of it (50
~ 70%) is supplied to the gas scrubber 15 via the line 43, and the rest (30 to 50%) is sent to the pre-stage synthesis tube 11 via the line 44. At the same time, part of the newly supplied carbon dioxide gas (5 to 15%
(Wt)) and a portion (30-50% (wt)) of fresh feed ammonia preheated to 120-160 ° C. Under the synthetic conditions described here above, urea is synthesized to 90-96% of the equilibrium value. The pre-stage synthetic liquid thus obtained enters the tube side of the carbamate condenser 14 'through line 37 and the line
It contacts the mixed gas coming from the stripper via 48 and condenses at least part of this mixed gas. At that time, the generated heat of condensation is recovered and used for separating unreacted substances as described above. On the other hand, a part of the unreacted material recovery liquid inserted in the gas scrubber 15 absorbs ammonia and carbon dioxide gas entrained in the inert gas separated from the top of the latter-stage synthesis tube 12, and carbamates via the line 46. It enters the shell side of condenser 14 and at least some of the mixed gas from the stripper condenses on it, as at 14 '. The gas-liquid mixed flow from the carbamate condensers 14 and 14 'enters the bottom of the post-synthesis tube 12 via the line 38. At the same time, the remaining fresh feed ammonia-line 32-is also inserted. The post-stage synthesis tube 12 is kept under the synthesis conditions of a normal stripping type process.

以上の事から次の効果が生ずる。 From the above, the following effects are produced.

［発明の効果］ 1.改造に際しａ用の合成管がそのまま使える。[Effects of the Invention] 1. When remodeling, the synthetic tube for a can be used as it is.

2.新規にｂ用の合成工程を設備するよりは簡単な設備で
済む。2. It is simpler than a new synthesis process for b.

3.b用の新設合成管は、全くの新規の場合よりも小さく
出来る。例えば20％位。The new synthetic tube for 3.b can be smaller than the completely new case. For example, about 20%.

4.前段合成管で尿素と水が生成しているので、カーバメ
ート凝縮器での凝縮温度が従来よりも高温に保てる。4. Since urea and water are generated in the former stage synthesis tube, the condensation temperature in the carbamate condenser can be kept higher than before.

［実施例］ ａ式プロセスによる日産100トンの尿素があって、これ
を増産をも兼ねて日産1500トンのｂ式プロセスのプラン
トに改造した。従来250kg/cm2G200℃で使用されていた
ａ用の合成管はその位置、そのままで使用された。ただ
し、合成管出口の配管は、改造により新設されるカーバ
メート凝縮器の一つに接続された。昇圧された新規供給
アンモニアはａ用合成管は勿論、ｂ用の合成管にも送入
出来るように、また昇圧された新規供給二酸化炭素ガス
も同様に、新設されるストリッパーにも送入出来るよう
に配管がなされた。一方、従来の高圧吸収器からの（カ
ーバメート）回収液は合成圧に昇圧後、その一部を新設
されるガス洗滌器にも送入出来るように配管がなされ
た。なお、新設の合成管、カーバメート凝縮器およびス
トリッパーの配置の相互関係は通常と同様である。従来
の（図示されていないが、）高圧吸収器からの、NH320.
0、CO220.8およびH2O12.0t/hrよりなる103℃の回収液が
回収液ポンプ３により190kg/cm2Gに昇圧され、そのうち
65.5％（重量）がガス洗滌器へ、残りの34.5％（重量）
が前段合成管11の底部に送入された。一方、圧縮機２に
より昇圧された140℃の新規供給二酸化炭素ガス45.8t/h
rの一部10％（重量）がこの前段合成管に、残りの90％
（重量）はストリッパー13の底部に送入された。またポ
ンプ１により昇圧された液体の新規供給アンモニア35.4
t/hrは第１予熱器でスチームコンデイセイトにより70℃
に予熱され、このうちの65％（重量）が後段合成管12に
送入され、残りの35％（重量）はさらにスチームで予熱
され前段合成管の底部に送入された。その結果、この合
成管ではNH3/CO2＝4.25mol比）、温度177℃となり、出
口では尿素10.5、NH313.5、CO24.1およびH2O7.5t/hrよ
りなる合成液が得られ、次いでカーバメート凝縮器14′
のチューブ側に入った。ここで、ストリッパーからの混
合ガスの一部がこの合成液に凝縮して温度が186℃に達
した。この際の発生熱は後述のように回収利用された。
一方、ガス洗滌器15に送入された回収液は、後段合成管
12の頂部にて分離されたイナートガスに同伴するアンモ
ニア、二酸化炭素ガスを吸収してカーバメート凝縮器14
のチューブ側に入りストリッパーからの混合ガスの他の
一部がこれに凝縮して同様の温度に達し、その際の発生
熱は低圧のスチームとして回収された。かくして、カー
バメート凝縮器14、14′で生成した気液混合流は後段合
成管12の底部に入り先述の送入アンモニアと共にここに
滞留する間にさらに尿素が合成された。温度は190℃に
達し頂部でイナートガスを分離した後は尿素67.4、NH37
4.3、CO223.3およびH2O38.4t/hrなる組成の合成液が得
られた。この合成液は下降管39よりストリッパー13の頂
部に入り高圧スチームによる加熱と、底部に送入された
先述の二酸化炭素ガスのストリッピング作用により、NH
359.3、CO27.8およびH2O5.5t/hrが送入二酸化炭素ガス
との混合ガスとして分離された。この結果、ストリッパ
ー底部からは176℃の尿素64.2、NH316.8、CO217.8およ
びH2O31.9t/hrからなる合成液が得られこれは直ちに17k
g/cm2Gに減圧されてカーバメート凝縮器14′のシェル側
に入りチューブ側で発生する熱により、残留アンモニア
および二酸化炭素の一部が気化した。かくして生成した
気液混合流はこの後、従来の処理に付されて尿素は製品
となり、未反応アンモニアおよび二酸化炭素は先述の如
き回収液として回収された。[Examples] There was 100 tons of urea per day produced by the a-type process, and this was converted into a plant of the b-type process of 1500 tons per day to increase production. The synthetic tube for a, which was conventionally used at 250 kg / cm 2 G at 200 ° C, was used as it was at that position. However, the piping at the outlet of the synthesis tube was connected to one of the carbamate condensers that will be newly installed by modification. The pressurized new supply ammonia can be sent not only to the synthesis pipe for a but also to the synthesis pipe for b, and the boosted new supply carbon dioxide gas can be sent to the newly installed stripper as well. The pipe was made to. On the other hand, piping was made so that the (carbamate) recovery liquid from the conventional high-pressure absorber could be fed to the newly installed gas scrubber after raising the synthetic pressure. The mutual relationship of the arrangement of the new synthetic tube, the carbamate condenser and the stripper is the same as usual. NH 3 20 from a conventional (not shown) high pressure absorber.
The recovery liquid of 103 ° C consisting of 0, CO 2 20.8 and H 2 O 12.0 t / hr was pressurized to 190 kg / cm 2 G by the recovery liquid pump 3,
65.5% (by weight) goes to the gas scrubber, the remaining 34.5% (by weight)
Was sent to the bottom of the former synthesis tube 11. On the other hand, the newly supplied carbon dioxide gas at 140 ° C that was boosted by the compressor 2 45.8t / h
Part of 10% (weight) of r is in this former stage synthetic tube, and the remaining 90%
(Weight) was sent to the bottom of the stripper 13. In addition, a new supply of liquid ammonia, which is boosted by pump 1,
t / hr is the 1st preheater and 70 ℃ by steam condiate
65% (by weight) of this was sent to the latter-stage synthesis tube 12, and the remaining 35% (by weight) was further preheated by steam and sent to the bottom of the former-stage synthesis tube. As a result, a NH 3 / CO 2 = 4.25 mol ratio) and a temperature of 177 ° C were obtained in this synthetic tube, and a synthetic solution consisting of urea 10.5, NH 3 13.5, CO 2 4.1 and H 2 O 7.5 t / hr was obtained at the outlet. , Then carbamate condenser 14 '
Entered the tube side of. Here, a part of the mixed gas from the stripper was condensed in this synthetic liquid, and the temperature reached 186 ° C. The heat generated at this time was recovered and used as described later.
On the other hand, the recovered liquid sent to the gas scrubber 15 is the latter stage synthesis tube.
Carbamate condenser by absorbing ammonia and carbon dioxide gas accompanying the inert gas separated at the top of 12
The other part of the mixed gas from the stripper, which entered the tube side, condensed to this and reached the same temperature, and the heat generated at that time was recovered as low-pressure steam. Thus, the gas-liquid mixed stream produced in the carbamate condensers 14 and 14 'enters the bottom of the latter-stage synthesis tube 12 and further urea is synthesized while staying there together with the above-mentioned fed ammonia. After the temperature reached 190 ° C and the inert gas was separated at the top, urea 67.4, NH 3 7
A synthetic solution having a composition of 4.3, CO 2 23.3 and H 2 O 38.4 t / hr was obtained. This synthetic liquid enters the top of the stripper 13 from the downcomer 39, is heated by high-pressure steam, and is stripped by the above-mentioned carbon dioxide gas sent to the bottom to generate NH.
3 59.3, CO 2 7.8 and H 2 O 5.5 t / hr were separated as a mixed gas with the input carbon dioxide gas. As a result, a synthetic solution consisting of urea 64.2, NH 3 16.8, CO 2 17.8 and H 2 O 31.9 t / hr at 176 ° C. was obtained from the bottom of the stripper, which was immediately heated to 17 k
Part of the residual ammonia and carbon dioxide was vaporized by the heat generated by entering the shell side of the carbamate condenser 14 'and being generated on the tube side after being reduced to g / cm 2 G. The gas-liquid mixed flow thus produced was then subjected to conventional treatment to convert urea into a product and unreacted ammonia and carbon dioxide as a recovery liquid as described above.

この発明の実施により後段合成管は、全くの新設の場
合より20％小さく出来、また凝縮温度が従来より高く出
来るためカーバメート凝縮器の伝熱面積も24％小さく出
来た。By carrying out the present invention, the latter-stage synthesis tube can be made 20% smaller than in the case of a completely new construction, and the heat transfer area of the carbamate condenser can be made 24% smaller because the condensation temperature can be made higher than before.

【図面の簡単な説明】[Brief description of drawings]

図は、本発明を適用した際の、合成、ストリッピングお
よびカーバメート凝縮工程の関係を示す概略フローシー
トである。 次に主要機器を列挙する。 1:アンモニアポンプ、2:圧縮機、3:回収液ポンプ、11:
前段合成管、12:後段合成管、13:ストリッパー、14、1
4′：カーバメート凝縮器、15:ガス洗滌器、16、17:ア
ンモニア予熱器The figure is a schematic flow sheet showing the relationship between the synthesis, stripping and carbamate condensation steps when the present invention is applied. The main equipment is listed below. 1: Ammonia pump, 2: Compressor, 3: Recovery liquid pump, 11:
1st-stage synthesis tube, 12: 2nd-stage synthesis tube, 13: Stripper, 14, 1
4 ': Carbamate condenser, 15: Gas scrubber, 16, 17: Ammonia preheater

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】アンモニアと二酸化炭素から尿素を合成す
る方法において、 反応条件が互いに異なる前段の尿素合成工程と後段の尿
素合成工程からなる尿素合成工程と、 後段の尿素合成工程で得られた尿素合成液Ｂを該合成圧
力下で未反応物をアンモニアと二酸化炭素に加熱・分解
し二酸化炭素の吹き込みにより分離するストリッピング
工程と、 ストリッピング工程で残った尿素合成液を減圧にし、未
反応物の実質全部をガス状に分離・回収し、回収液と尿
素水溶液を得る少なくとも一段の未反応物分離工程と、 ストリッピング工程で分離された未反応物を未反応物分
離工程で得られた回収液の一部及び前段尿素合成工程で
得られた尿素合成液Ａとで凝縮し凝縮液を得る凝縮工程
からなり、 後段の尿素合成工程ではアンモニアと凝縮液とを原料と
して尿素合成反応を行い、前段の尿素合成工程ではアン
モニアと二酸化炭素と未反応物分離工程からの回収液の
一部を原料として尿素合成反応を行わせることを特徴と
する尿素合成方法。1. A method for synthesizing urea from ammonia and carbon dioxide, wherein a urea synthesizing step comprising a pre-stage urea synthesizing step and a post-stage urea synthesizing step having different reaction conditions, and a urea obtained in the post-stage urea synthesizing step A stripping step of heating and decomposing the unreacted product of the synthesis solution B into ammonia and carbon dioxide under the synthesis pressure and separating by blowing carbon dioxide, and reducing the pressure of the urea synthesis solution remaining in the stripping step, Of at least one unreacted material separation step to obtain and collect the recovered liquid and urea aqueous solution by separating and recovering substantially all of the above in a gaseous state, and the unreacted material separated in the stripping step and recovered in the unreacted material separation step It consists of a condensation process in which a part of the liquid and the urea synthesis liquid A obtained in the preceding urea synthesis process are condensed to obtain a condensed liquid. In the latter urea synthesis process, ammonia and the condensed liquid are combined. Urea synthesis reaction carried out, urea synthesis method characterized by the pre-stage of the urea synthesis process to perform a urea synthesis reaction a part of the recovering solution from ammonia and carbon dioxide and unreacted reactants separation step as a raw material as a fee.
JP62041054A 1987-02-24 1987-02-24 Urea production method Expired - Lifetime JPH082859B2 (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
JP62041054A JPH082859B2 (en) 1987-02-24 1987-02-24 Urea production method
IN135/CAL/88A IN169023B (en) 1987-02-24 1988-02-15
IDP283688A ID800B (en) 1987-02-24 1988-02-16 UREA PRODUCTION PROCESS
DE3805403A DE3805403A1 (en) 1987-02-24 1988-02-21 Process for the preparation of urea
BR8800751A BR8800751A (en) 1987-02-24 1988-02-23 IMPROVEMENT IN UREA PRODUCTION PROCESS
PL1988270814A PL152735B1 (en) 1987-02-24 1988-02-23 Method for manufacturing urea

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP62041054A JPH082859B2 (en) 1987-02-24 1987-02-24 Urea production method

Publications (2)

Publication Number Publication Date
JPS63208563A JPS63208563A (en) 1988-08-30
JPH082859B2 true JPH082859B2 (en) 1996-01-17

Family

ID=12597692

Family Applications (1)

Application Number Title Priority Date Filing Date
JP62041054A Expired - Lifetime JPH082859B2 (en) 1987-02-24 1987-02-24 Urea production method

Country Status (6)

Country Link
JP (1) JPH082859B2 (en)
BR (1) BR8800751A (en)
DE (1) DE3805403A1 (en)
ID (1) ID800B (en)
IN (1) IN169023B (en)
PL (1) PL152735B1 (en)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6041654A (en) * 1983-07-14 1985-03-05 モンテデイソン・エツセ・ピ・ア Manufacture of urea with low vapor consumption quantity

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL174548C (en) * 1977-05-05 1988-05-16 Montedison Spa PROCESS FOR PREPARING UREA BY REACTION OF AMMONIA AND CARBON DIOXIDE.
DE3100388A1 (en) * 1981-01-09 1982-09-02 Mitsui Toatsu Chemicals, Inc. Process for urea synthesis
NL8104040A (en) * 1981-09-01 1983-04-05 Unie Van Kunstmestfab Bv METHOD FOR THE PREPARATION OF UREA.
IT1211125B (en) * 1981-10-16 1989-09-29 Ortu Francesco NITROGEN COMPOUNDS. PROCESS FOR THE PREPARATION OF

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6041654A (en) * 1983-07-14 1985-03-05 モンテデイソン・エツセ・ピ・ア Manufacture of urea with low vapor consumption quantity

Also Published As

Publication number Publication date
JPS63208563A (en) 1988-08-30
DE3805403C2 (en) 1990-05-17
ID800B (en) 1996-07-10
IN169023B (en) 1991-08-17
DE3805403A1 (en) 1988-09-01
PL152735B1 (en) 1991-01-31
PL270814A1 (en) 1988-12-08
BR8800751A (en) 1988-10-04

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