CN86101228A - Make the method for urea with carbonic acid gas and ammonia - Google Patents
Make the method for urea with carbonic acid gas and ammonia Download PDFInfo
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- CN86101228A CN86101228A CN198686101228A CN86101228A CN86101228A CN 86101228 A CN86101228 A CN 86101228A CN 198686101228 A CN198686101228 A CN 198686101228A CN 86101228 A CN86101228 A CN 86101228A CN 86101228 A CN86101228 A CN 86101228A
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- heat
- urea
- carbonic acid
- acid gas
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- 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
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Abstract
With the method for carbonic acid gas and ammonia manufacturing urea, in this method, carbonic acid gas reaches the pressure that generates urea through stage compression, and between compressions at different levels, carbonic acid gas is cooled off.Urea synthesis solution is processed into a kind of aqueous solution of urea or urea solid.At the heat that pressurization inter processes at different levels discharge, at least a portion is taken away by a kind of heat-eliminating medium, and the heat of taking away needing in other operation of heat to can be used for again.At the pressurization inter process, carbonic acid gas can be by the heat-eliminating medium advection cooling that provides or by a plurality of independently cooling loop coolings.
Description
The present invention touches upon and makes the method for urea with carbonic acid gas and ammonia, what compression arbon dioxide is this method divide, to reach the pressure that generates urea, between compressions at different levels, carbonic acid gas is cooled off, and make urea synthesis solution be processed into aqueous solution of urea or urea solid.
In the method for industrial application, need the high-pressure gaseous carbonic acid gas, available radial compressor and/or reciprocation compressor divide a few step compression arbon dioxides, make it reach desired pressure.For example, during with gaseous carbon dioxide and liquid ammonia urea synthesis, synthetic is to carry out under the pressure that is higher than 125 crust, usually, and progressively dividing level Four compressed gaseous carbonic acid gas at least under the pressure boost, to reach desired pressure.Every grade of compression all can produce heat.If want the required energy of limit compression,, then must remove the heat that compression process discharges in order to avoid compressor components damages because of overheated.
In fact now adopted following method usually: make water coolant side cooler by each pressurization operation under each intermediate pressure, remove the heat that discharges with the indirect heat exchange method.Its repeated use is promptly discharged or made to the temperature of water coolant after raising, and for example, can cool off in refrigerating unit.In this method, the heat that the water that is cooled in the heat exchanging process of each pressurization operation absorbs is a depleted.
In making the process of urea, under suitable pressure (as the 125-350 crust) and suitable temperature (as 170-250 ℃), generate ammonium carbamate earlier with liquid ammonia and gaseous carbon dioxide, then, the ammonium carbamate of generation is dewatered and make urea.The reaction product that this method obtains comes down to a kind of solution, and this solution contains urea, water, ammonium carbamate and free ammonia.From solution, remove ammonium carbamate and ammonia.Then remaining urea-containing solution is processed into urea soln or urea solid.
In " Europe chemistry circular " the urea supplementary issue 17-20 page or leaf on January 17th, 1969, introduced a kind of urea manufacture method commonly used.This method is earlier under high pressure and high temperature, in synthetic district, generate urea synthesis solution, then under synthesis pressure, this solution is contacted with the gaseous carbon dioxide convection current to carry out stripping to be handled, transmit heat simultaneously, the result makes carbamate contained in the solution decompose ammonification and carbonic acid gas basically, removes gaseous decomposition product from solution, and takes away a small amount of water vapor and be used for steam stripped carbonic acid gas.Except that adopting carbonic acid gas (described in above-mentioned publication), can also use the mixture of gaseous ammonia, a kind of rare gas element or above-mentioned at least two kinds of gases, for example, be used in the gaseous mixture that discharges because of heating in the treating processes and carry out the stripping processing.In the tube space of the vertical heat exchanger that carries out the stripping processing, the high compressed steam condensation of clinging to by 15-25 can obtain the required heat of stripping.
At first condensing zone, the most of condensation of the gaseous mixture that obtains in the stripping is got off, and by new liquid ammonia with further handle and contain the resulting a kind of aqueous solution of urea soln and absorb, the carbamate aqueous solution that generates in this process and uncooled gaseous mixture are by synthetic district, to generate urea.Heat that discharges in this condensing zone and solution are taken away with the evaporation of water device is housed, and make water become low-pressure steam, and this low-pressure steam can be used for other operation of urea synthesis.
Then, make stripped urea synthesis solution be expanded to low pressure, for example, the 2-6 crust, and, be present in remaining ammonia and the carbonic acid gas that exists with the carbamate form in the stripped urea synthesis solution so that from solution, remove in part with the low-pressure steam heating.Condensation in second condensing zone that the gaseous mixture that obtains in these operations (also containing water vapour) is under low pressure operated, and be absorbed in the aqueous solution, the carbamate dilute solution that generates in this process makes it feed synthetic district with the high pressure area of pumped back urea synthesis at last.Remaining contains urea soln step-down and be condensed into urea soln or urea melt once more, and this urea melt can further be processed into solid urea.For this reason, usually with the evaporation of two steps, make the aqueous solution of urea dehydration, transmit heat simultaneously, the urea melt that obtains can be processed into particulate state, or makes the urea soln crystallization.When generating so-called intermediate condensation thing, the steam mixture (except that containing water vapor, the urea microparticles that also contains ammonia, carbonic acid gas and carry secretly) that obtains in evaporation or the crystallisation process is condensed.Part intermediate condensation thing can be used as the absorption agent of gaseous mixture in second condensing zone.Remaining intermediate condensation thing is handled with high compressed steam, so that wherein contained urea decomposition ammonification and carbonic acid gas, and transmits heat by desorb, reclaims these degradation productions and original ammonia and carbonic acid gas.In granulating device, urea melt becomes granular, owing to the carbamide dust of carrying secretly in the air of removing with washings by the granulating device discharge, thereby has generated waste liquid stream.For further handling these waste liquid stream, need heat again.
The object of the invention is to provide a kind of method that reclaims heat economically, and this heat discharges when gaseous carbon dioxide reaches urea synthesis pressure through stage compression.Carbonic acid gas makes its indirect cooling with a kind of cooling medium flowing after one or more levels compression, the heat that is absorbed by heat-eliminating medium needing in the procedure of processing of heat can be used for, thereby can reach purpose of the present invention.
Therefore, the present invention is that what compression arbon dioxide is this method divide to reach the pressure that generates urea, between compressions at different levels about the method with carbonic acid gas and ammonia manufacturing urea, make the carbonic acid gas cooling, and make urea synthesis solution be processed into aqueous solution of urea or urea solid.This method feature is taken away by the heat that discharges in: at least a portion pressurization operation medium that is cooled, and this part heat of taking away can be used for the urea manufacturing processed, and other needs in the operation of heat.
Can easily heat-eliminating medium be sent in the side cooler of compressor of a plurality of split flow, when the heat-eliminating medium stream temperature of middle water cooler raises, can respectively its discharge or synthetic one liquid stream be discharged.Also available independently cooling loop cools off the carbonic acid gas between each step compression.In the case, be used for the heat-eliminating medium stream of cooling loop, for example can flow acquisition, and the heat-eliminating medium stream that temperature has raise can sub-thread liquid stream or synthetic one liquid stream discharge from common main heat-eliminating medium.But, also may be following situation, promptly having a cooling loop at least is the loop line, one end and carbonic acid gas to be cooled carry out heat exchange, the other end and heated technical process logistics or the exchange of a kind of energy transformation medium heat.
A kind of specially suitable heat-eliminating medium is a liquid ammonia, because ammonia is a kind of raw material of urea synthesis, part heat required in the manufacturing processed preferably obtains by preheating ammonia.If make heat-eliminating medium with liquid ammonia, ammonia is introduced under urea synthesis pressure, requirement if so then adds higher pressure earlier, carries out heat exchange with compressed gaseous carbon dioxide again.Because the result of heat exchange, ammonia will all evaporate or the part evaporation, and this depends on the adding temperature and the state of liquid ammonia in the carbon dioxide compressor.Then, all or part of condensing zone of sending into of ammonia stream that preferably will heat, the gaseous ammonia and the gaseous carbon dioxide that condense in this district can not generate urea.In heat exchanging process, because liquid ammonia has absorbed heat, thereby all or part of gas phase that becomes can discharge a large amount of heat in this district, for example, can generate a large amount of low-pressure steams or generate the higher low-pressure steam of a kind of pressure.
The heat that discharges in each pressurization operation also can reclaim with oiler feed (making heat-eliminating medium), and in this process, water becomes low-pressure steam.
This cooling loop uses water as heat-eliminating medium (can add or not add the reagent that falls vapour pressure in the water), or make heat-eliminating medium with the liquid that contains a kind of higher-boiling compound at least, also can reclaim the heat of release easily, this when adopting closed cooling loop especially like this.In this loop line, also can make heat-eliminating medium with fluorine-containing and/or chloride paraffinic material.
To as 1,2 ethylene glycol, propylene glycol, for example be added in the water as the di-alcohols that falls vapour pressure reagent, the result is in heat exchanging process, and the pressure of heat-eliminating medium can be lower than the pressure of compressed carbonic acid gas.Because the vapour pressure of heat-eliminating medium reduces,, can prevent that all carbonic acid gas and heat-eliminating medium from mixing no matter (even taking place under the situation of seepage) under which kind of situation.
Suitable higher-boiling compound (this compound can be used for taking away the heat that compression process discharges) can be an epoxy Tetrafluoroethane polymkeric substance etc.Its boiling point of these compounds is up to 490 ℃, and known its trade name is " freonll-11 E ".In addition, in heat exchange, can be as the fluorine-containing and chloride paraffinic hydrocarbons of suitable lower boiling of refrigerant, for example, CCl
3F, CCl
2F
2, CClF
3, CHClF
2, C
2Cl
3F
3, C
2Cl
2F
4, C
2ClF
5If the whole heat of absorption pressure compression process release of round-robin heat-eliminating medium in the loop line, for example the temperature of carbonic acid gas is than higher, and then available water coolant makes the temperature of carbonic acid gas further drop to next stage to compress desired inlet air temperature.
The heat that absorbs can all or part ofly be used for following several respects:
A, generation mechanical energy,
B, generation electric energy,
C, heating and/or evaporation liquid ammonia,
D, heating and/or decomposition carbamate,
E, the evaporation urea soln and/or,
F, further handle the waste liquid stream that intermediate condensation thing and/or urea synthesis obtain.
Certainly, when the heat that the recovery compression is discharged, may adopt two independently cooling loops at least, thereby may adopt two kinds of different refrigerants at least.
Now, will further specify the present invention, yet they are not to come with restriction the present invention by drawings and Examples.
Schematic view illustrating among Fig. 1, compression arbon dioxide in four-stage compressor, the heat that compression process discharges is taken away by ammonia.
1, four pressurization operations of 2,3 and 4 expression four-stage compressors.In pressurization operation 1, carbonic acid gas (also containing a small amount of oxygen containing gas usually) so that used structured material keeps passive state in the urea synthesis equipment, being depressed into pressure is about 5 crust.2,3 and 4 the pressurization operations in, the pressure of carbonic acid gas be increased to respectively about 20,80 and be higher than 120 the crust, for example, about 160 the crust.5,6 and 7 all represent the cooling zone, and compressed gaseous carbon dioxide cools off in these cooling zones in each pressurization operation.Liquid ammonia leads to pump 11 from storage 9 through 10, and with pump 11 pressure of liquid ammonia is added to and is at least 125 crust, for example, about 160 crust.The liquid stream 12 that is extruded by pump 11 is divided into three strands of independent liquid streams 13,14 and 15.Per share liquid stream all leads to a cooling zone that belongs to a pressurization operation respectively, and liquid stream 13 leads to cooling zone 5, and liquid stream 14 leads to cooling zone 6, and liquid stream 15 leads to cooling zone 7.Require if so, can directly deliver to the high pressure condensing zone (not drawing in this district) of urea manufacturing equipment with liquid ammonia by another strand liquid stream 16.After each pressurization operation compression, the cooling degree of carbonic acid gas depends on time per unit the flow through amount of heat-eliminating medium of cooling zone and compressed carbonic acid gas and the temperature head between the refrigerant in each cooling zone.By amount and/or its temperature of controlled chilling agent, the cooling degree that can regulate carbonic acid gas, the cooling degree of carbonic acid gas depend on needed inlet air temperature in the next pressurization operation.Because evaporation or local evaporation fully take place in heat exchange, ammonia.After heat exchange, the liquid stream 13,14 and 15 that separates is merged into liquid stream 17, and then, this liquid stream 17 leads to unillustrated high pressure condensing zone.The gaseous mixture that obtains in the stripping process of urea synthesis is distinguished condensation at this, and the heat of release is used to generate low pressure (as the 3-5 crust) steam, and this low-pressure steam can be used for other operation then.Increase owing to heat exchange makes the thermal content of ammonia, compare with method commonly used so far, this method can generate a large amount of low-pressure steams.
In the urea manufacturing equipment start-up course, return storage 9 for making ammonia by water cooler 19, be provided with pipeline 18.
Fig. 2 is a kind of synoptic diagram of embodiment, and this method is taken away the heat that compression produces with pressurized water.Adopt among the figure with the corresponding reference number of Fig. 1 and represent identical equipment and liquid stream.Represent cooling loop with 20,23 and 26; Represent pump with 21,24 and 27; 22,25 and 28 expression heat exchangers.In pressurization operation 1,2 and 3, the heat that compression discharges is carried out round-robin water with pump 21,24 and 27 in loop 20,23 and 26 and is taken away, the heat that is absorbed by water in cooling zone 5,6 and 7 shifts feeding attitude ammonia in heat exchanger 22,25 and 28, liquid ammonia is to flow out from storage 9, in the parallel-flow mode through 13,14 and 15, by heat exchanger 22,25 and 28 separately.In this operation, all or part of evaporation of ammonia.In the high pressure condensing zone of urea synthesis, generate low-pressure steam then with the heat that is transferred to ammonia.
Example 1
When process industry level urea, by method shown in Figure 1, compressed gaseous carbonic acid gas in a level Four radial compressor.One ton of urea of every production adds 774.8 kilograms gaseous mixture in compressor, this gaseous mixture contains 744.9 kilograms of CO
2, 31.86 kilograms of N
2With 7.52 kilograms of O
2The heat that discharges in three grades of initial pressurization operations is to take away by the required liquid ammonia of a part of urea synthesis, and gaseous carbon dioxide is cooled to 75 ℃.
Be divided into the liquid ammonia of three strands of parallel liquid streams, its temperature is 40 ℃, and pressure is 156.9 crust.Each side cooler of the junior three level pressurization operation of the parallel other flow path of ammoniacal liquor flow point of each bar.From the effusive ammonia of each side cooler, its temperature is 160 ℃.Following table 1 has been listed in the operation of respectively pressurizeing, the pressure and temperature of gaseous carbon dioxide, the amount of ammonia and heat to be taken away.
The table I
Feed the high pressure carbamate condensing zone of urea synthesis from the effusive ammonia of middle water cooler, and add in the stripping gas of condensation.
Because heat contained in the ammonia is higher, so in this district, urea per ton can additionally generate the low-pressure steam that 171 kilograms of pressure are 4.5 crust.
Example 2
Press example 1 described method, compression contains the carbonated gaseous mixture with example 1 same composition.Take away the heat of release with liquid ammonia required in the part urea synthesis, the temperature of this liquid ammonia is 70 ℃, and pressure is 156.9 crust.The parallel liquid stream of each bar (totally three) adverse current of each side cooler of the junior three level pressurization of flow path operation is fed in the gaseous carbon dioxide to be cooled.Gaseous carbon dioxide is chilled to 90 ℃, and ammonia is heated to 170 ℃.
The table II is listed the pressure and temperature of gaseous carbon dioxide in the pressurization operations at different levels, the amount of ammonia and heat to be taken away.
The table II
Be admitted to the stripping gas condensation in the high pressure condensing zone of urea synthesis of this gas from the effusive ammonia of each side cooler.
Because a large amount of heat of extra release is produced urea per ton and can additionally be obtained the low-pressure steams that 161 kilograms of pressure are 4.5 crust.
Example 3
The carbonated gaseous mixture of compression in a four-stage compressor, the composition of this gaseous mixture is identical with example 1, takes away the heat that compression produces by method shown in Figure 2 simultaneously.In junior three level pressurization operation, water is taken away the heat of release.For this reason, one ton of urea of every production will feed 212 kilograms water in pressure is cooling loop 20 under 6.2 crust, be in the cooling loops 23 and 26 of 15.5 crust at pressure, should feed 245 kilograms and 276 kg water respectively.Because the water in the cooling zone 5,6 and 7 has absorbed heat, the result is in loop 20, and the temperature of water can rise to 160 ℃ from 80 ℃, and in loop 23 and 26, the temperature of water can rise to 200 ℃ from 80 ℃.By the transferable liquid ammonia of giving of heat that water absorbs, this liquid ammonia is that 156.9 crust and temperature are under 70 ℃ at pressure, in the advection mode, by heat exchanger 22,25 and 28.For this reason, one ton of urea of every production, the ammonia of flow through fluid pipe 13,14 and 15 is respectively 118,131 and 148 kilograms.These ammonia are added up and are equivalent to make about 70% of the required ammonia total amount of urea.The all evaporations of ammonia heat absorption back.13, after 14 and 15 3 strands of liquid streams were merged into one liquid stream 17, the temperature of gaseous ammonia was 167 ℃.Ammonia in the high pressure condensing zone, the gaseous mixture condensation that can in stripping process, obtain, urea per ton can additionally reclaim 161 kilograms of pressure be 4.5 the crust low-pressure steams.
Claims (11)
1, makes the method for urea with carbonic acid gas and ammonia, this method divides the stage compression carbonic acid gas to reach the pressure that generates urea, between compressions at different levels, make the carbonic acid gas cooling and make urea synthesis solution be processed into a kind of aqueous solution of urea or urea solid, this method feature is: at the heat of pressurization inter process release, at least a portion is taken away by a kind of heat-eliminating medium, and the heat of taking away needing in other operation of heat to can be used for again.
2, by the method for claim 1, it is characterized by: at the pressurization inter process, with the heat-eliminating medium cooled carbon dioxide of multiply split flow.
3, by the method for claim 1, it is characterized by: at the pressurization inter process, with a plurality of independently cooling loop cooled carbon dioxides.
4, by the method for claim 3, it is characterized by: the heat-eliminating medium stream of each cooling loop is to be obtained by a total sprue.
5, press the method for claim 3, it is characterized by: at least one independently cooling loop be the loop line, this loop at one end with carbonic acid gas heat exchange to be cooled, the other end and a kind of technological process logistics or a kind of energy transfer medium to be heated carry out heat exchange.
6, by the method for claim 3, it is characterized by: the used heat-eliminating medium at least one loop line is a water, can contain in the water a kind ofly to fall the reagent of vapour pressure or contain a kind of liquid, and this liquid is made up of a kind of higher-boiling compound at least.
7, by the method for claim 3, it is characterized by: at least one closed loop is made heat-eliminating medium with fluorine-containing and/or chloride paraffinic hydrocarbons.
8, by the method for claim 1, it is characterized by: in pressurization inter process heat to be taken away, at least a portion can be used for heating a kind of compressed ammoniacal liquor stream.
9, by the method for claim 8, it is characterized by: the ammonia stream that heated to small part is admitted to the gaseous ammonia of condensation and the zone that carbonic acid gas can not be transformed into urea.
10, make the method for urea with carbonic acid gas and ammonia, wherein to reach the pressure that generates urea, carbonic acid gas can be cooled off at the pressurization inter process by the method for narrating and illustrating in accompanying drawing and the example this method with the stage compression carbonic acid gas.
11, make urea soln and solid urea by the described methods of any one or several of aforesaid right requirement.
Errata
CPCH866061
After the preceding revisal of the capable revisal of file name page or leaf
Specification sheets 7 10 744.9 734.9
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL8500591A NL8500591A (en) | 1985-03-04 | 1985-03-04 | PROCESS FOR THE PREPARATION OF UREA FROM CARBON DIOXIDE AND AMMONIA. |
| NL8500591 | 1985-03-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN86101228A true CN86101228A (en) | 1986-10-22 |
Family
ID=19845610
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN198686101228A Pending CN86101228A (en) | 1985-03-04 | 1986-03-02 | Make the method for urea with carbonic acid gas and ammonia |
Country Status (6)
| Country | Link |
|---|---|
| CN (1) | CN86101228A (en) |
| DE (1) | DE3606898A1 (en) |
| FR (1) | FR2578251B1 (en) |
| HU (1) | HUT44487A (en) |
| NL (1) | NL8500591A (en) |
| TR (1) | TR22829A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101679224B (en) * | 2007-05-22 | 2013-11-06 | 塞彭公司 | Enhanced process for the synthesis of urea |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1908355A1 (en) * | 1968-03-19 | 1969-10-09 | Mitsui Toatsu Chemicals | Process for the production of urea |
-
1985
- 1985-03-04 NL NL8500591A patent/NL8500591A/en not_active Application Discontinuation
-
1986
- 1986-03-02 CN CN198686101228A patent/CN86101228A/en active Pending
- 1986-03-03 DE DE19863606898 patent/DE3606898A1/en not_active Withdrawn
- 1986-03-03 TR TR12486A patent/TR22829A/en unknown
- 1986-03-03 HU HU87686A patent/HUT44487A/en unknown
- 1986-03-04 FR FR8603005A patent/FR2578251B1/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101679224B (en) * | 2007-05-22 | 2013-11-06 | 塞彭公司 | Enhanced process for the synthesis of urea |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2578251A1 (en) | 1986-09-05 |
| DE3606898A1 (en) | 1986-10-09 |
| NL8500591A (en) | 1986-10-01 |
| TR22829A (en) | 1988-08-17 |
| FR2578251B1 (en) | 1987-11-27 |
| HUT44487A (en) | 1988-03-28 |
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