Process for melamine purification
US-2021332017-A1 · Oct 28, 2021 · US
Process for preparing melamine
US9598379B2 · US · B2
| Field | Value |
|---|---|
| Publication number | US-9598379-B2 |
| Application number | US-73804908-A |
| Country | US |
| Kind code | B2 |
| Filing date | Oct 14, 2008 |
| Priority date | Oct 15, 2007 |
| Publication date | Mar 21, 2017 |
| Grant date | Mar 21, 2017 |
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Abstract
Official abstract text for this publication.
Process for preparing melamine by converting urea in the presence of a solid catalyst in one reactor or in a plurality of reactors connected in series in the temperature range from 370° C. to 430° C., cooling and filtering the gas formed in the urea conversion, removing the melamine by desublimation and recycling a portion of the gas present after the melamine removal (“cycle gas”) into the reactor or the reactors, which comprises performing all of the above stages at a pressure in the range from 4 bar abs. to 10 bar abs.
First claim
Opening claim text (preview).
The invention claimed is: 1. A process for preparing melamine by converting urea in the presence of a solid catalyst in one reactor or in a plurality of reactors connected in series in the temperature range from 370° C. to 430° C., cooling the gas formed in the urea conversion in a gas cooler to a temperature from 320° C. to 380° C. and filtering the gas formed in the urea conversion in a hot gas filter, removing the melamine by desublimation and recycling a portion of the gas present after the melamine removal (“cycle gas”) into the reactor or the reactors, which comprises performing all of the above stages at a pressure in the range from 4 bar abs. to 10 bar abs and wherein, after the melamine removal, 5 to 50% of the cycle gas is branched off and fed into the reactor as “fluidizing gas” without passing through a urea scrubber and at least some of the remainder of cycle gas is fed to the urea scrubber. 2. The process according to claim 1 , wherein the catalytic urea conversion and melamine synthesis take place only in one reactor in a fluidized bed. 3. The process according to claim 1 , wherein the return gas is branched off upstream of the cooling gas blower in flow direction. 4. The process according to claim 1 , wherein the desublimation is carried out at a temperature in the range from 150° C. to 250° C. 5. The process according to claim 2 , wherein the desublimation is carried out at a temperature in the range from 150° C. to 250° C. 6. The process according to claim 3 , wherein the desublimation is carried out at a temperature in the range from 150° C. to 250° C. 7. The process according to claim 2 , wherein the return gas is branched off upstream of the cooling gas blower in flow direction. 8. The process according to claim 7 , wherein the desublimation is carried out at a temperature in the range from 150° C. to 250° C. 9. The process according to claim 1 , wherein 10 to 20% of the cycle gas is branched off and fed into the reactor as “fluidizing gas” without passing through the urea scrubber.
Assignees
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Classifications
Purification of melamine · CPC title
- C07D251/60Primary
from urea or from carbon dioxide and ammonia · CPC title
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- What does patent US9598379B2 cover?
- Process for preparing melamine by converting urea in the presence of a solid catalyst in one reactor or in a plurality of reactors connected in series in the temperature range from 370° C. to 430° C., cooling and filtering the gas formed in the urea conversion, removing the melamine by desublimation and recycling a portion of the gas present after the melamine removal (“cycle gas”) into the rea…
- Who is the assignee on this patent?
- Kern Andreas, Pröbstle Hans-Ulrich, John Tilo, and 3 more
- What technology area does this patent fall under?
- Primary CPC classification C07D251/60. Mapped technology areas include Chemistry & Metallurgy.
- When was this patent published?
- Publication date Tue Mar 21 2017 00:00:00 GMT+0000 (Coordinated Universal Time) (B2). Legal status and post-grant events are not shown on this page.
- What related patents are in patentsdb?
- We list 8 related publications on this page (citations in our corpus or others sharing the same primary CPC).