Process for producing ammonium sulfate crystals

Patent metadata

Field	Value
Publication number	US-2016214868-A1
Application number	US-201314649823-A
Country	US
Kind code	A1
Filing date	Nov 29, 2013
Priority date	Dec 6, 2012
Publication date	Jul 28, 2016
Grant date	—

Abstract

The present invention provides a continuous process for producing ammonium sulfate crystals, wherein said process comprises: i) feeding to a series of crystallization sections, which crystallization sections are heat integrated in series, a solution of ammonium sulfate; ii) crystallizing ammonium sulfate crystals from said solution of ammonium sulfate; iii) purging a fraction of the solution of ammonium sulfate from each of said crystallization sections;and iv) discharging ammonium sulfate crystals from each crystallization section, characterized in that: a fraction of said solution of ammonium sulfate is purged from at least one crystallization section to at least one other crystallization section; and an apparatus suitable for producing ammonium sulfate crystals.

First claim

1 . A continuous process for producing ammonium sulfate crystals, wherein said process comprises:
i) feeding to a series of crystallization sections, which crystallization sections are heat integrated in series, a solution of ammonium sulfate; ii) crystallizing ammonium sulfate crystals from said solution of ammonium sulfate; iii) purging a fraction of the solution of ammonium sulfate from each of said crystallization sections; and iv) discharging ammonium sulfate crystals from each crystallization section, characterized in that: a fraction of said solution of ammonium sulfate is purged from at least one crystallization section to at least one other crystallization section.

2 . A process according to claim 1 , wherein the crystallization sections are heat integrated by means of steam.

3 . A process according to claim 2 , wherein a fraction of said solution of ammonium sulfate is purged from each crystallization section in the series to the next crystallization unit in the series, as defined by descending temperature of steam supply, with the exception that the purge from the final crystallization section in the series is discharged from the series.

4 . A process according to claim 1 , wherein each crystallization section has substantially equal production capacity of ammonium sulfate crystals.

5 . A process according to claim 1 , wherein the series comprises from two to four, crystallization sections.

6 . A process according to claim 1 , wherein each crystallization section comprises an Oslo-type crystallizer.

7 . A process according to claim 1 , wherein the temperature of steam entering the first crystallization section in the series is from 80° C. to 160° C.

8 . A process according to claim 1 , wherein the temperature of steam exiting the last crystallization section in the series is from 40° C. to 60° C.

9 . A process according to claim 1 , wherein the production capacity of ammonium sulfate crystals of each crystallization section is from 30 kta to 150 kta.

10 . A process according to claim 1 , wherein the mean median diameter of the ammonium sulfate crystals discharged is from 1.0 mm to 4.0 mm.

11 . A process according to claim 1 , wherein the solution of ammonium sulfate is produced from a process for producing ε-caprolactam or acrylonitrile.

12 . Apparatus suitable for producing ammonium sulfate crystals, comprising:
i) a series of crystallization sections of substantially equal production capacity of ammonium sulfate crystals, which are configured to be heat integrated with respect to steam; ii) a steam supply system integrating the crystallization sections in series; iii) a feed of ammonium sulfate solution; and iv)a system of removal of ammonium sulfate crystals; characterized in that, at least one crystallization section is connected by a purge line to another crystallization section in the series.

13 . Apparatus according to claim 12 , wherein each crystallization section is connected by a purge line to the next crystallization section in the series, as defined by descending temperature of steam supply, with the exception that the purge from the final crystallization section is discharged from the series.

14 . Apparatus according to claim 12 , wherein each crystallization section comprises an evaporative crystallizer and solid-liquid separation equipment.

15 . Apparatus according to claim 12 , wherein the production capacity of ammonium sulfate crystals of each crystallization section is from 30 kta to 150 kta.

Assignees

• Dsm Ip Assets Bv

Inventors

• Ekkelenkamp Geert
• Debeij Johannes Elisabeth Pierre
• Geertman Robert
• Van Ysacker Peter
• Tinge Johan Thomas

Classifications

• B01D9/0036

  Crystallisation on to a bed of product crystals; Seeding · CPC title

• B01D9/0031 Primary

  by heating (B01D9/0022, B01D9/0027 take precedence) · CPC title

• B01D9/0063

  Control or regulation (control per se G05) · CPC title

• C01C1/248

  Preventing coalescing or controlling form or size of the crystals · CPC title

• B01D9/004

  Fractional crystallisation; Fractionating or rectifying columns · CPC title