CN1224635A - Urea synthesizing tower with evenly distributed reaction material residance period - Google Patents
Urea synthesizing tower with evenly distributed reaction material residance period Download PDFInfo
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- CN1224635A CN1224635A CN 98121987 CN98121987A CN1224635A CN 1224635 A CN1224635 A CN 1224635A CN 98121987 CN98121987 CN 98121987 CN 98121987 A CN98121987 A CN 98121987A CN 1224635 A CN1224635 A CN 1224635A
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- tower
- distributor
- carbon dioxide
- inlet distributor
- urea
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Abstract
In the bottom of the tower, all the materials including ammonia, CO2, ammonium carbamate, etc. enter into the tower through respective fluid distributor, so that the material liquid is distributed homogeneously in the whole section once entering into the tower, and this can eliminate radically the distribution inhomogeneity of the flow rate, concentration and temperature of the materials. At the main urea discharge port in the upper part of the tower and at the discharge port for small amount of urea in the lower part, fluid distributors are set for homogeneous discharge. All the section homogeneous distribution of liquid flow in the tower can realize the homogeneous distribution of material residence-time and high reaction percent conversion.
Description
The invention belongs to the technical field of urea production, and relates to a urea synthesis tower.
As is well known, urea is a high-quality fertilizer and also an important chemical raw material. The synthesis reaction of urea is carried out in two steps: firstly, ammonia and carbon dioxide react to generate ammonium carbamate, and the reaction formula is as follows:
In order to meet the requirement of sufficient residence time of reaction materials in the urea synthesis tower and reduce back mixing, the existing industrial urea synthesis tower is designed into a larger height-diameter ratio, and a plurality of tower plates are arranged in the urea synthesis tower so as to reduce the back mixing phenomenon of the fluid. Even so, back mixing of the fluids in the column is still quite severe. In order to modify this situation, U.S. patent 5,304,353, apr.19,1994 discloses a urea synthesis column with a sieve plate with a relief structure, with some improvement in the conversion. However, the urea synthesis tower with such a structure still does not fundamentally solve the problem of back mixing of the fluids in the tower, mainly because: 1. the feed liquid inlets at the bottom of the urea synthesis tower are directly fed by straight pipes, and the feed liquid enters the tower body in a jet flow form, and the diameter of the urea synthesis tower is generally large, and the space is also large, so that the flow velocity and the concentration on thecross section of the tower are seriously uneven; the temperature distribution is therefore also very inhomogeneous due to the dependence of the thermal effects of the reaction. The mixing process in such low flow rate situations, by means of conventional sieve or swirl plates, is often ineffective, since it can only be carried out in spaces with a considerable height-to-diameter ratio, with the consequence of a significant reduction in the reaction conversion of the urea synthesis column; 2. urine is directly derived through straight tube or bell mouth pipe in urea converter upper portion urine exit and the little urine exit in lower part, because the diameter of discharging pipe is far less than the tower footpath, must lead to the tower cross-section velocity of flow to distribute seriously unevenly, influences the evenly distributed of whole tower material dwell time to cause the reduction of conversion. Accordingly, a new urea synthesis tower that eliminates back mixing of fluids must be developed to meet the needs of industrial production for production increase and potential.
The invention aims to disclose a urea synthesis tower with a feeding fluid distributor and a discharging fluid distributor, which ensures that reaction materials uniformly flow in the whole urea synthesis tower at the whole cross section, thereby ensuring that the concentration, the temperature and the retention time can be uniformly distributed along the tower cross section, thoroughly eliminating the reverse mixing of the fluids, realizing the uniform distribution of the residence time of the reaction materials, overcoming the defects in the prior art and obtaining the urea conversion rate which is closer to the equilibrium state than the prior art.
The idea of the invention is that:
at the bottom of the urea synthesis tower, all materials including ammonia, carbon dioxide and methylamine respectively enter the synthesis tower through respective fluid distributors, so that the feed liquid enters the synthesis tower to achieve full-section uniform distribution, and the uneven distribution state of bottom flow velocity, concentration and temperature caused by feeding is fundamentally eliminated; the urine discharge port at the upper part of the tower and the small amount of urine discharge port at the lower part are also respectively provided with a fluid distributor to ensure that the urine is discharged evenly. Therefore, the liquid flow of the whole synthesis tower is in a full-section uniform distribution state, the residence time of reaction materials is uniformly distributed, the defect of serious reverse mixing of the fluid in the tower in the prior art is overcome, and the reaction conversion rate is effectively improved.
According to the above concept, the invention discloses a urea synthesis tower with a feeding and discharging full-section distributor. At present, the urea synthesis tower used in industry has a slightly different structure due to different flow paths, and the technical scheme of the invention will be described in detail with reference to the attached drawings.
FIG. 1 is a schematic diagram of a urea synthesis column with a total cross-section distributor for a total circulation process of aqueous solution. Figure 2 is a schematic diagram of a carbon dioxide stripping urea synthesis column with a full cross-section sparger. In the figure:
1-tower body 2-methylamine inlet distributor
3-column plate 4-urine discharge pipe
5- -urine discharge distributor
6-carbon dioxide inlet distributor
7-liquid ammonia inlet distributor
8-small quantity urine discharging distributor
9- -Ammonia and carbon dioxide gas inlet sparger 10- -feed pipe
The urea synthesizing tower shown in figure 1 is a combination body, which is mainly composed of a tower body 1, an ammonium carbamate inlet distributor 2, a tower plate 3, a urine discharging pipe 4, a urine discharging distributor 5, a carbon dioxide inlet distributor 6, a liquid ammonia inlet distributor 7, a feeding pipe 10 and other parts. The aspect ratio is generally 11 to 21. Urine ejection of compact distributor 5 sets up in the upper portion of tower, and for simple to operate, urine discharging pipe 4 can adopt the socket joint structure. The methylamine inlet distributor 2, the carbon dioxide inlet distributor 6 and the liquid ammonia inlet distributor 7 are arranged at the bottom of the tower. The tower plate 3 is arranged in the tower, the existing urea synthesis tower usually has 2-10 blocks, and a flat screen hole type, a concave-convex screen hole type or a rotational flow plate type and the like can be adopted. Urine discharging distributor 5, liquid ammonia inlet distributor 7, carbon dioxide inlet distributor 6 and methylamine inlet distributor 2 are all fixedly connected with the inner wall of the tower by adopting a mechanical method. During production, methylamine, carbon dioxide and liquid ammonia respectively enter the synthesis tower from the bottom of the tower through respective distributors, and urine after reaction flows out of the tower through the discharge pipe 4 by the urine discharge distributor 5.
In order to satisfy the mechanism of the two-step reaction of urea and ensure that the material has enough reaction space after entering the tower, the positions of all the feeding distributors are reasonably arranged. The specific structural parameters are as follows:
the distance H between the liquid ammonia inlet distributor 7 and the tower bottom is (0.15-0.45) D, and D is the inner diameter of the synthesis tower;
the distance H between the liquid ammonia inlet distributor 7 and the carbon dioxide inlet distributor 61D is (0.05-0.45);
the distance H between the carbon dioxide distributor 6 and the ammonium carbamate distributor 22D is (0.10-1.0);
the location of the discharge distributor may be flush with the outlet pipe in existing synthesis columns.
The urea synthesis tower shown in fig. 2 is a combination of a tower body 1, an ammonium carbamate inlet distributor 2, a tower plate 3, a urine discharging distributor 5, a small amount of urine discharging distributor 8 and an ammonia and carbon dioxide gas inlet distributor 9. The aspect ratio is generally 11 to 21.
Urine ejection of compact distributor 5 sets up in the upper portion of tower, and ammonia and carbon dioxide gas import distributor 9 and first ammonium import distributor 2 set up in the bottom of tower, and a small amount of urine ejection of compact distributor 8 sets up in the lower part of tower. The tower plate 3 is arranged in the tower, the existing urea synthesis tower usually has 2-10 blocks, and a flat screen hole type, a concave-convex screen hole type or a rotational flow plate type and the like can be adopted. Urine discharging distributor 5, small urine discharging distributor 8, ammonia and carbon dioxide gas inlet distributor 9, and methylamine inlet distributor 2 are all fixed with the inner wall of the tower by mechanical method. During production, ammonia, carbon dioxide gas and methylamine respectively enter the tower from the bottom of the tower through respective distributors, a small amount of urine at the lower part flows out from the bottom of the tower through the distributor8, and finished urine flows out from the bottom of the tower through the urine discharging distributor 5. The specific structural parameters are as follows:
the distance H between the ammonia and carbon dioxide gas inlet distributor 9 and the bottom of the tower3D is (0.15-0.45);
the distance H between the ammonia and carbon dioxide gas inlet distributor 9 and the methylamine inlet distributor 24D is (0.05-0.40);
the positions of the lower small urine discharging distributor 8 and the finished urine discharging distributor 5 are the same as the discharging holes of the existing equipment.
The distributors can be conventional fluid distributors, such as branched pipe distributors, circular pipe distributors and square groove distributors.
Fig. 3 is a view from a-a in fig. 1. The distributor is a pipe branch-shaped distributor. In the figure:
11-main pipe 12-branch pipe
13- -support
Fig. 4 is a view from B-B in fig. 3. In the figure:
14- -small hole
Feed liquid enters the main pipe 11 through the feed pipe 10 and then enters the synthesis column through the branch pipe 12 through the small hole 14. Said distributor being fixedly connected to the inner wall of the tower by means of a support 13.
Because the feeding distributor and the discharging distributor are arranged in the urea synthesizing tower, and the positions of the distributors are reasonably arranged, the serious uneven state of the fluid distribution in the prior art is fundamentallyeliminated, the fluid of the whole urea synthesizing tower is ensured to uniformly flow in the whole cross section, so that the concentration, the temperature and the retention time can be uniformly distributed along the cross section of the tower, therefore, the urea synthesizing reaction can be carried out in the state of orderly flowing of the fluid, the conversion rate is obviously improved, and the urea synthesizing tower is an efficient urea synthesizing tower.
The invention is suitable for the urea synthesizing tower with the aqueous solution full circulation method and the urea synthesizing tower with the carbon dioxide gas stripping method, and is also suitable for urea synthesizing towers with other various processes.
Claims (4)
1. A urea converter with uniformly distributed residence time of reaction materials is characterized in that: the bottom of the urea synthesizing tower is provided with a feeding fluid distributor which is fixedly connected with the inner wall of the tower by a mechanical method.
2. A urea synthesis column according to claim 1, characterized in that: the upper part of the tower is provided with a urine discharging distributor (5), the lower part of the tower is provided with a small amount of urine discharging distributors (8), and the distributors (5) and (8) are fixedly connected with the inner wall of the tower by adopting a mechanical method.
3. A urea synthesis column according to claims 1-2, characterized in that: the bottom of the urea synthesis tower is provided with a methylamine inlet distributor (2), a carbon dioxide inlet distributor (6) and a liquid ammonia inlet distributor (7); the urine discharging distributor (5) is arranged at the upper part of the tower;
the urine discharge distributor (5), the liquid ammonia inlet distributor (7), the carbon dioxide inlet distributor (6) and the ammonium carbamate inlet distributor (2) are fixedly connected with the inner wall of the tower by adopting a mechanical method;
the distance (H) between the liquid ammonia inlet distributor (7) and the tower bottom is (0.15-0.45) (D);
liquid ammonia inletThe distance (H) between the distributor (7) and the carbon dioxide inlet distributor (6)1) Is (0.05-0.45) (D);
the distance (H) between the carbon dioxide inlet distributor (6) and the methylamine inlet distributor (2)2) Is (0.10-1.0) (D);
the location of the discharge distributor may be flush with the outlet pipe in an existing urea synthesis column.
4. A urea synthesis column according to claims 1-2, characterized in that: the bottom of the urea synthesis tower is provided with a methylamine inlet distributor (2), a small amount of urine discharging distributor (8) and an ammonia and carbon dioxide gas inlet distributor (9); the urine discharging distributor (5) is arranged at the upper part of the tower;
the urine discharging distributor (5), the ammonia and carbon dioxide gas inlet distributor (9), the small urine discharging distributor (8) and the ammonium carbamate inlet distributor (2) are fixedly connected with the inner wall of the tower by adopting a mechanical method;
the distance (H) between the ammonia and carbon dioxide gas inlet distributor (9) and the bottom of the tower3) Is (0.15-0.45) (D);
the distance (H) between the ammonia and carbon dioxide gas inlet distributor (9) and the methylamine inlet distributor (2)4) Is (0.05-0.40) (D);
the positions of the small urine discharging distributor (8) and the urine discharging distributor (5) are the same as the existing equipment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN98121987A CN1085106C (en) | 1998-11-12 | 1998-11-12 | Urea synthesizing tower with evenly distributed reaction material residance period |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN98121987A CN1085106C (en) | 1998-11-12 | 1998-11-12 | Urea synthesizing tower with evenly distributed reaction material residance period |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1224635A true CN1224635A (en) | 1999-08-04 |
| CN1085106C CN1085106C (en) | 2002-05-22 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN98121987A Expired - Fee Related CN1085106C (en) | 1998-11-12 | 1998-11-12 | Urea synthesizing tower with evenly distributed reaction material residance period |
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| CN (1) | CN1085106C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016157154A1 (en) * | 2015-04-03 | 2016-10-06 | Saipem S.P.A. | Urea synthesis reactor and process |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3709568B2 (en) * | 1994-02-07 | 2005-10-26 | チッソ株式会社 | Residual monomer removal treatment method and residual monomer removal treatment tower used therefor |
| CN1075889C (en) * | 1998-01-23 | 2001-12-05 | 浙江大学 | On-line detector for safety condition of urea synthetic tower |
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1998
- 1998-11-12 CN CN98121987A patent/CN1085106C/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016157154A1 (en) * | 2015-04-03 | 2016-10-06 | Saipem S.P.A. | Urea synthesis reactor and process |
| CN107660159A (en) * | 2015-04-03 | 2018-02-02 | 塞彭公司 | Reactor for synthesis of urea and method |
| US10486130B2 (en) | 2015-04-03 | 2019-11-26 | Saipem S.P.A. | Urea synthesis reactor and process |
| CN107660159B (en) * | 2015-04-03 | 2021-02-05 | 塞彭公司 | Urea synthesis reactor, use method thereof and urea synthesis method |
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| Publication number | Publication date |
|---|---|
| CN1085106C (en) | 2002-05-22 |
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