Wash column apparatus with static grid element for use in a suspension crystallization process

Patent metadata

Field	Value
Publication number	US-11045744-B2
Application number	US-201716332261-A
Country	US
Kind code	B2
Filing date	Sep 6, 2017
Priority date	Sep 12, 2016
Publication date	Jun 29, 2021
Grant date	Jun 29, 2021

Abstract

A wash column apparatus for the use in a suspension crystallization process for separating crystals from a crystal suspension mixture includes a cylindrical vessel including a piston with a piston head including a filter and a piston rod, movable in the cylindrical vessel, an inlet for supplying a crystal suspension mixture into the cylindrical vessel, an outlet for discharging mother liquor from the cylindrical vessel, an outlet for discharging crystals or crystal melt from the cylindrical vessel, a circulation conduit for circulating melt arranged outside the vessel, in communication with the wash chamber, a static grid element arranged in the wash chamber for restricting movement of the crystal bed and for directing the wash liquid entering into the cylindrical vessel from the circulation conduit so as to homogeneously distribute it over the entire cross-section of the wash column.

First claim

The invention claimed is:

1. A wash column apparatus for use in a suspension crystallization process configured to separate crystals from a crystal suspension mixture composed of crystals and mother liquor, the wash column apparatus comprising:
a cylindrical vessel, the cylindrical vessel comprising:
a piston with a piston head and a piston rod, the piston being arranged reciprocatingly movable in the cylindrical vessel, the piston bounding above the piston head a wash chamber inside the cylindrical vessel, and the piston head comprising at least one filter,
an inlet configured to supply a crystal suspension mixture composed of crystals and mother liquor into the cylindrical vessel,
a first outlet configured to discharge mother liquor from the cylindrical vessel,
a second outlet configured to discharge crystals or crystal melt from the cylindrical vessel,
a circulation conduit configured to circulate melt arranged outside the cylindrical vessel, the circulation conduit being in communication with the wash chamber, and
a static grid element arranged in the wash chamber configured to restrict movement of a crystal bed that has been compacted in the wash chamber by the piston and configured to direct a wash liquid entering into the cylindrical vessel from the circulation conduit so as to homogeneously distribute the wash liquid over an entire cross-section of the wash column,
the static grid element comprising at least one element, which is at least substantially vertically extending, and at least two vertically extending cavities, which are at least substantially vertically extending, the at least two cavities, which are at least substantially vertically extending, being open at upper and lower ends thereof, but otherwise at least partially closed, substantially vertically extending meaning that a longitudinal axis of the at least one element and of the at least two cavities extends at an angle of 0 to 60° to a vertical direction,
wherein a second inlet leads from the cylindrical vessel into the circulation conduit for discharging a part of the crystals or crystal melt thereof into the circulation conduit and a third outlet leads from the circulation conduit into the cylindrical vessel for partially reintroducing the circulated melt as reintroduced wash liquid into the cylindrical vessel so as to flow through the static grid element to the crystal bed,
wherein the second inlet and the third outlet are arranged at a downstream side of the static grid element, the downstream side being a side of the static grid element that is opposite to a side of the static grid element at which the piston performs a compression stroke,
wherein a heating element is provided in the circulation conduit to control a temperature of the circulated melt, and
wherein dimensions and cross-sectional areas of the cavities are adjusted so as to allow the formation and maintenance of the crystal bed and to homogeneously distribute the reintroduced wash liquid over the entire cross-section of the wash column.

2. The wash column apparatus in accordance with claim 1 ,
wherein the at least two cavities, which are at least substantially vertically extending, have a rectangular cross-section, a hexagonal cross-section, a circular cross-section or an annular cross-section.

3. The wash column apparatus in accordance with claim 1 ,
wherein the static grid element comprises at least three vertically extending cavities being open at upper and lower ends thereof, but otherwise closed.

4. The wash column apparatus in accordance with claim 1 ,
wherein the static grid element comprises at least two vertically arranged parallel plates with at least one cavity formed between each of adjacent plates, wherein the at least one cavity is open at its upper and lower ends, but otherwise closed.

5. The wash column apparatus in accordance with claim 4 ,
wherein the static grid element comprises 2 to 20 plates arranged vertically and in parallel.

6. The wash column apparatus in accordance with claim 4 ,
wherein cuboidal cavities are formed between each of the adjacent plates of the static grid element, the cuboidal cavities being open at upper and lower ends thereof, but otherwise closed.

7. The wash column apparatus in accordance with claim 6 ,
wherein the static grid element includes an open cross-sectional area, which is the ratio of the sum of cross-sectional areas of the cuboidal cavities of the static grid element divided by a total cross-sectional area of the static grid element, and is 10 to 90%.

8. A method for separating crystals from a crystal suspension mixture composed of crystals and mother liquor comprising the step of supplying a crystal suspension mixture composed of crystals and mother liquor to the inlet of a wash column apparatus in accordance with claim 1 .

9. A method for thickening a crystal suspension mixture composed of crystals and mother liquor, comprising:
supplying a crystal suspension mixture composed of crystals and mother liquor to the inlet of a wash column apparatus in accordance with claim 1 .

10. The wash column apparatus in accordance with claim 2 , wherein the static grid element comprises at least three vertically extending cavities, which are open at upper and lower ends thereof, but otherwise closed.

11. The wash column apparatus in accordance with claim 5 , wherein cuboidal cavities are formed between each of the adjacent plates of the static grid element, wherein the cuboidal cavities are open at upper and lower ends thereof, but otherwise closed.

12. The wash column apparatus in accordance with claim 4 , wherein the static grid element comprises 4 to 7 plates, which are arranged vertically and in parallel.

Assignees

• Sulzer Management Ag

Inventors

• Jansen Halbe
• Jansen Johannes

Classifications

• B01D9/0045 Primary

  Washing of crystals, e.g. in wash columns · CPC title

• B01D9/0059

  General arrangements of crystallisation plant, e.g. flow sheets · CPC title

• B01D9/005

  Selection of auxiliary, e.g. for control of crystallisation nuclei, of crystal growth, of adherence to walls; Arrangements for introduction thereof · CPC title

• B01D9/0013

  by indirect heat exchange · CPC title