CN101786641A - Ammonia recovery process used for production of nitroaniline and ammonia recovery system - Google Patents
Ammonia recovery process used for production of nitroaniline and ammonia recovery system Download PDFInfo
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- CN101786641A CN101786641A CN 201010128902 CN201010128902A CN101786641A CN 101786641 A CN101786641 A CN 101786641A CN 201010128902 CN201010128902 CN 201010128902 CN 201010128902 A CN201010128902 A CN 201010128902A CN 101786641 A CN101786641 A CN 101786641A
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- tail gas
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Abstract
The invention relates to an ammonia recovery process used for production of nitroaniline, wherein the nitroaniline is prepared by the ammonolysis reaction by nitrochlorobenzene and ammonia in an ammonolysis kettle, and the ammonia is from an ammonia allocation tank. In the ammonia recovery process, (1) dilute ammonia water is adopted for absorbing ammonia tail gas after the ammonolysis reaction until the pressure of the ammonolysis kettle is balanced with that of the ammonia allocation tank; (2) the residual ammonia tail gas is led into a multi-stage ammonia recovery system for absorption until the pressure of the ammonolysis kettle is zero, and then the dilute ammonia water after absorption can be used for the step (1). In the invention, the high-pressure section absorption and the low-pressure absorption are combined for the ammonia absorption, therefore, the recovery rate of the ammonia tail gas is greatly improved, and the economic benefit is obvious; in the process, almost no ammonia recovery equipment is added, therefore, the reformation cost is low; by establishing the relationship of the pressure drop of the ammonolysis kettle and the amount of the ammonia tail gas, the problem of measuring the ammonia tail gas at the high-pressure section can be solved, and stronger ammonia water sampling and analyzing operations with pressure can be avoided, so that the recovery process can be smoothly operated.
Description
(1) technical field
The present invention relates to a kind of ammonia reclaiming process and ammonia recovery system that N-methyl-p-nitroaniline is produced that be used for.
(2) background technology
With reference to Fig. 1, N-methyl-p-nitroaniline production is to be that raw material is separated at ammonia and carried out ammonolysis reaction in the still 1 with nitro-chlorobenzene, ammonia, is solvent with water in the reaction.Nitro-chlorobenzene, ammonia and water, react under the 4.5-5.2Mpa condition at 150-172 ℃ with about 1: 9: 9 mixed in molar ratio, and reaction finishes to emit the surplus ammonia of reaction, and surplus ammonia water absorbs the ammonification water cycle and applies mechanically.Unload behind the ammonia feed liquid after filtration, washing, promptly get the p-Nitroaniline finished product.Reaction formula is as follows:
The defective that this technology exists: the excessive multiple of ammonia is big, and reaction finishes to still have a large amount of surplus ammonia.Contain a small amount of N-methyl-p-nitroaniline because water absorbs in the ammoniacal liquor that surplus ammonia obtains, can only be used as the N-methyl-p-nitroaniline raw materials for production.Not superfluous in order to guarantee to reclaim ammoniacal liquor, requiring to reclaim the surplus ammonia solvent for use water yield must equate with N-methyl-p-nitroaniline production technique water consumption.About 1: 1.36 of the weight ratio of surplus ammonia and process water, the full recovery set usefulness of ammonia, ammonia concn need reach more than 40%, and the ammoniacal liquor of this concentration reaches about 3atm at 40 ℃ of following saturation pressures, must adopt band to press and absorb.And adopt conventional pressurization ammonia absorption system, on problems such as concentration analysis and reinforced metering, there is certain degree of difficulty again.
With reference to Fig. 1, in the prior art in the N-methyl-p-nitroaniline production ammonia reclaiming process be:, ammonia carries out release earlier after separating end, the ammonia tail gas that draws off is concentrated through water cooler 6 and is guided to multistage ammonia recovery system 2 and reclaim, and unloads to be pressed onto ammonia to separate still 1 gauge pressure be zero back discharging.In the process that feeds intake, the ammoniacal liquor that the ammoniacal liquor storage tank is reclaimed carries out sampling analysis, table look-up then and determine ammoniacal liquor feeding quantity (purpose is that every batch of technology water yield of maintenance is identical), calculate folding 100% ammonia amount in the ammoniacal liquor, add ammoniacal liquor by definite ammonia vol of tabling look-up in the ammonia jar 3 toward joining, charge into liquefied ammonia again to stipulating total ammonia amount.The shortcoming of this technology is that multistage ammonia recovery system 2 pressure are limited, and ammonia tail gas recycle utilization ratio is not high.Press ammonia recovery system if simply set up a cover band, exist again how to guarantee with the accurate analysis of pressing ammoniacal liquor and the problem of metering.
(3) summary of the invention
Technical problem to be solved by this invention is to provide a kind of can increase substantially ammonia tail gas recycle rate, convenient to the metering of ammonia tail gas, has avoided the strong aqua band to press the ammonia reclaiming process and the ammonia recovery system that N-methyl-p-nitroaniline is produced that be used for of sampling and analysing operation.
A kind of ammonia reclaiming process that is used for N-methyl-p-nitroaniline production, described N-methyl-p-nitroaniline is separated at ammonia by nitro-chlorobenzene and ammonia and is carried out ammonolysis reaction in the still and make, described ammonia comes autogamy ammonia jar, described ammonia reclaiming process comprises the steps: the ammonia tail gas after (1) employing weak ammonia absorbs ammonolysis reaction, separates still and only joins ammonia pressure tank balance up to ammonia; (2) residual ammonia tail gas is introduced multistage ammonia recovery system again and absorbed, separating still still pressure until ammonia is zero ending, and obtains weak ammonia after the absorption, and weak ammonia is used for step (1).
N-methyl-p-nitroaniline produces being used for, and p-Nitrophenyl chloride ammonia is separated end, carry out the nature release (in the so-called natural release stress-relief process to ammonia separate still neither heat also do not cool off).In the stress-relief process, need to absorb heat because the dissolved ammonia vaporization is overflowed, along with the carrying out of release, pressure and temperature progressively descend.The contriver tests discovery, and in the stress-relief process, ammonia is separated the reduction value of ammonia concentration in the feed liquid and reduction value that ammonia is separated still pressure (or temperature) has quantitative relationship.Because to separate the charging technology water yield be fixed to every batch of ammonia, therefore, separates feed liquid for the ammonia of different batches, on behalf of ammonia, identical ammonia concentration just separate to have identical ammonia amount in the feed liquid.Can draw thus, in the natural stress-relief process, separating the reduction value that ammonia amount that still draws off and ammonia separates still pressure (or temperature) from ammonia has quantitative relationship.
Based on above-mentioned conclusion, the ammonia reclaiming process that the present invention proposes is separated the still stress-relief process with ammonia and is divided into high pressure section, two sections recovery of low-pressure stage.The same prior art of low-pressure stage ammonia solvent recovery technology from vent gas is concentrated and is introduced multistage ammonia recovery system absorption; Press the ammonia recovery system to join the ammonia jar as band, absorb single pot of high pressure section ammonia tail gas.Entering the high pressure section ammonia tail gas amount of joining the ammonia jar separates still pressure decline numerical value according to ammonia and determines.
Mainly there is the measurement problem of high pressure section ammonia tail gas in the ammonia reclaiming process of this patent.Because joining ammonia jar recovery high pressure section ammonia tail gas is solvent with the weak ammonia that multistage ammonia recovery system reclaims, after absorbing high pressure section ammonia tail gas again, resulting strong aqua concentration has reached more than 40%, the vapour pressure of ammoniacal liquor is greater than normal atmosphere, in case enter the normal pressure sampling unit, ammonia is overflowed easily, causes error.In order accurately to measure high pressure section ammonia tail gas amount, begin when tentative without weak ammonia, use clear water instead as solvent, directly absorb high pressure section ammonia tail gas, resulting ammonia concn is about 20%, and the vapour pressure of ammoniacal liquor is lower than normal atmosphere, easily sampling analysis, calculate the high pressure section ammonia tail gas amount of recovery, long run test is several batches according to this.Separate total ammonia amount and P in the still by estimation ammonia again
150The relation of (still is pressed when being warmed up to 150 ℃) draws different P
150Press terminal point P with different putting
tHigh pressure section ammonia tail gas folding ammonia amount.Separating still with the 3000L ammonia of producing p-Nitroaniline is example, high pressure section ammonia tail gas folding ammonia amount and P
150, P
tConcern as shown in table 1ly, so just solved the measurement problem of high pressure section ammonia tail gas.
Table 1 p-Nitroaniline is produced high pressure section ammonia tail gas folding ammonia amount and P
150, P
tRelation table
A kind of ammonia recovery system that is used for N-methyl-p-nitroaniline production, described N-methyl-p-nitroaniline production adopts ammonia to separate still, described ammonia recovery system adopts multistage ammonia recovery system, ammonia is separated still successively by water cooler, first valve and the multistage ammonia recovery system of pipe connection, multistage ammonia recovery system is separated still through joining ammonia jar connection ammonia again, and described water cooler is also joined the ammonia jar by second valve and pipe connection.
The present invention absorbs ammonia and adopts high pressure section absorption and low-pressure stage absorption to combine, and ammonia tail gas recycle rate increases substantially, and adopts these technology front and back relatively, and the liquefied ammonia unit consumption descends about 0.35 ton/ton, remarkable in economical benefits; And this technology increases the ammonia recovery system hardly, utilizes original production unit---join the ammonia jar and carry out ammonia tail gas band and press and absorb, improvement cost is low; Separate the relation of still pressure drop and ammonia tail gas amount by setting up ammonia, solved high pressure section ammonia tail gas measurement problem, avoided the strong aqua band to press the sampling and analysing operation, make this recovery technology be able to trouble-free operation.
(4) description of drawings
Fig. 1 is the structural representation that is used for the ammonia recovery system of N-methyl-p-nitroaniline production in the prior art.
Fig. 2 is the structural representation that this patent is used for the ammonia recovery system of N-methyl-p-nitroaniline production.
(5) embodiment
Below by embodiment and accompanying drawing the present invention is preferably specified, but protection scope of the present invention is not limited to this.
A kind of ammonia reclaiming process that is used for N-methyl-p-nitroaniline production, described N-methyl-p-nitroaniline is separated at ammonia by nitro-chlorobenzene and ammonia and is carried out ammonolysis reaction in the still and make, described ammonia comes autogamy ammonia jar, described ammonia reclaiming process comprises the steps: the ammonia tail gas after (1) employing weak ammonia absorbs ammonolysis reaction, separates still and only joins ammonia pressure tank balance up to ammonia; (2) residual ammonia tail gas is introduced multistage ammonia recovery system again and absorbed, separating still still pressure until ammonia is zero ending, and obtains weak ammonia after the absorption, and weak ammonia is used for step (1).
With reference to Fig. 2, a kind of ammonia recovery system that is used for N-methyl-p-nitroaniline production, described N-methyl-p-nitroaniline production adopts ammonia to separate still 1, described ammonia recovery system adopts multistage ammonia recovery system 2, ammonia is separated still 1 successively by water cooler 6, first valve 4 and the multistage ammonia recovery system 2 of pipe connection, multistage ammonia recovery system is separated still 1 through joining ammonia jar 3 connection ammonia again, and described water cooler 6 is also joined ammonia jar 3 by second valve 5 and pipe connection.
Promptly know with reference to Fig. 1, Fig. 2, the difference of this patent and prior art ammonia recovery system be water cooler comes out among Fig. 2 ammonia offgas duct many a branch road directly enter and join the ammonia jar.Do not increase other new installation, by Adjustment System management with put the press operation step, significantly improved ammonia tail gas recycle rate.
Before every batch of ammonolysis reaction finishes, will prepare for the ammonia work of joining that next batch ammonia is separated.Ammonia concn in the ammoniacal liquor storage tank in the sampling analysis low pressure ammonia recovery system is tabled look-up and is determined single batch of weak ammonia feeding quantity (purpose is to guarantee that every batch of technology water yield is identical), adds the specified amount weak ammonia in the ammonia jar toward joining.
After the ammonolysis reaction end, promptly begin release, leading portion high pressure section ammonia tail gas directly feeds after cooling off joins the ammonia jar, until ammonia is separated still and joined ammonia pressure tank balance, ammonia tail gas can not enter only joins the ammonia jar, and record ammonia this moment is separated the temperature and the pressure of still.P when separating the still intensification according to ammonia
150Separate the still that still high pressure section ammonia tail gas puts when finishing with ammonia and press P
tTable look-up and 1 determine high pressure section ammonia tail gas amount.Ammonia is separated low-pressure stage ammonia tail gas that still draws off to be guided to multistage ammonia recovery system and absorbs.
Join that the ammonia amount is weak ammonia folding ammonia amount and high pressure section ammonia tail gas folding ammonia amount in the ammonia jar this moment, charge into liquefied ammonia total ammonia amount in joining the ammonia jar in the ammonia jar and only reach the total ammonia amount of regulation toward joining.
After ammonia is separated still low-pressure stage ammonia tail gas and is unsnatched, discharging.Separate toward this ammonia again and add nitro-chlorobenzene in the still, will join the high strength ammonia hydraulic pressure for preparing in the ammonia jar and go into ammonia and separate still, enter down batch operation.
Claims (2)
1. one kind is used for the ammonia reclaiming process that N-methyl-p-nitroaniline is produced, and described N-methyl-p-nitroaniline is separated at ammonia by nitro-chlorobenzene and ammonia and carried out ammonolysis reaction in the still and make, and described ammonia comes autogamy ammonia jar, it is characterized in that described ammonia reclaiming process comprises the steps:
(1) the ammonia tail gas behind the employing weak ammonia absorption ammonolysis reaction is separated still and is only joined ammonia pressure tank balance up to ammonia;
(2) residual ammonia tail gas is introduced multistage ammonia recovery system again and absorbed, separating still still pressure until ammonia is zero ending, and obtains weak ammonia after the absorption, and weak ammonia is used for step (1).
2. one kind is used for the ammonia recovery system that N-methyl-p-nitroaniline is produced, described N-methyl-p-nitroaniline production adopts ammonia to separate still, described ammonia recovery system adopts multistage ammonia recovery system, ammonia is separated still successively by water cooler, first valve and the multistage ammonia recovery system of pipe connection, multistage ammonia recovery system is separated still through joining ammonia jar connection ammonia again, and it is characterized in that: described water cooler is also joined the ammonia jar by second valve and pipe connection.
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| CN 201010128902 CN101786641A (en) | 2010-03-19 | 2010-03-19 | Ammonia recovery process used for production of nitroaniline and ammonia recovery system |
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| CN 201010128902 CN101786641A (en) | 2010-03-19 | 2010-03-19 | Ammonia recovery process used for production of nitroaniline and ammonia recovery system |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3354615A (en) * | 1964-08-07 | 1967-11-28 | Snam Spa | Process for the separation of ammonia produced in medium and low pressure synthesizing plants |
| CN101289401A (en) * | 2008-03-24 | 2008-10-22 | 浙江巍华化工有限公司 | Process for preparing 2,6- dichlor-4-trifluoromethyl aniline |
-
2010
- 2010-03-19 CN CN 201010128902 patent/CN101786641A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3354615A (en) * | 1964-08-07 | 1967-11-28 | Snam Spa | Process for the separation of ammonia produced in medium and low pressure synthesizing plants |
| CN101289401A (en) * | 2008-03-24 | 2008-10-22 | 浙江巍华化工有限公司 | Process for preparing 2,6- dichlor-4-trifluoromethyl aniline |
Non-Patent Citations (4)
| Title |
|---|
| 《中国氯碱》 20040331 梁诚 邻苯二胺生产技术进展与市场分析 17-20 1-2 , 第3期 2 * |
| 《化工生产与技术》 20010625 严招春等 对硝基苯胺生产工艺的改进 42-43 1-2 第8卷, 第3期 2 * |
| 《化工设计通讯》 19940930 李永昌 间歇反应氨尾气回收工艺及运行 62-64 1-2 第20卷, 第3期 2 * |
| 《环境污染与防治》 20000430 谢雨生 对硝基苯胺生产过程中的污染防治对策 24-25 1-2 第22卷, 第2期 2 * |
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Open date: 20100728 |