Improved method for processing magnesium chloride solutions and method for manufacturing carboxylic acids

Patent metadata

Field	Value
Publication number	US-2019194029-A1
Application number	US-201716068989-A
Country	US
Kind code	A1
Filing date	Jan 19, 2017
Priority date	Jan 19, 2016
Publication date	Jun 27, 2019
Grant date	—

Abstract

Magnesium chloride solutions including providing aqueous magnesium chloride solution with magnesium chloride concentration of 10-30 wt. % to concentration step where water is evaporated, resulting in concentrated magnesium chloride solution with magnesium chloride concentration of 30-50 wt. %, wherein concentration step is carried out in one or more stages, wherein at least one of the stages is conducted at elevated pressure, withdrawing concentrated magnesium chloride solution from concentration step, and providing it to thermohydrolysis reactor of at least 300° C., withdrawing MgO from thermohydrolysis reactor in solid form, and withdrawing a HCl containing gas stream of at least 300° C. from thermohydrolysis reactor, providing the HCl-containing gas stream of at least 300° C. to cooling step, where HCl-containing gas stream is contacted with cooling liquid, withdrawing HCl-containing gas stream below 150° C. from cooling step, circulating cooling liquid through heat exchanger where energy is transferred to heating liquid which circulates from heat exchanger to concentration step.

First claim

1 . Method for processing magnesium chloride solutions comprising the steps of
providing an aqueous magnesium chloride solution with a magnesium chloride concentration of 10-30 wt. % to a concentration step where water is evaporated, resulting in a concentrated magnesium chloride solution with a magnesium chloride concentration of 30-50 wt. %, wherein the concentration step is carried out in one or more stages, wherein at least one of the stages is conducted at elevated pressure, withdrawing the concentrated magnesium chloride solution from the concentration step, and providing it to a thermohydrolysis reactor, the reactor being at a temperature of at least 300° C., withdrawing MgO from the thermohydrolysis reactor in solid form, and withdrawing a HCl containing gas stream having a temperature of at least 300° C. from the thermohydrolysis reactor, providing the HCl-containing gas stream having a temperature of at least 300° C. to a cooling step, where the HCl-containing gas stream is contacted with a cooling liquid, withdrawing a HCl-containing gas stream with a temperature below 150° C. from the cooling step, circulating the cooling liquid through a heat exchanger where energy from the cooling liquid is transferred to a heating liquid which circulates from the heat exchanger to the concentration step.

2 . Method according to claim 1 , wherein the concentration step is carried out in one or more stages, wherein at least one of the stages is conducted at a pressure of at least 1.1 bara and/or at most 10 bara.

3 . Method according to claim 1 wherein the concentration step is carried out in multiple stages.

4 . Method according to claim 3 wherein steam is withdrawn from a first concentration stage and provided as heating liquid to a further concentration stage.

5 . Method according to claim 3 wherein the multiple stage concentration is carried out in a multiple-effect evaporator.

6 . Method according to claim 1 wherein vapor-compression evaporation is used in the concentration step or in one or more stages thereof.

7 . Method according to claim 1 wherein the magnesium chloride solution provided to the thermal decomposition step has a concentration of 30-48 wt. % and a temperature of 100-170° C.

8 . Method according to claim 1 , wherein the temperature of the cooling liquid as it is derived from the cooling step and before it enters the heat exchanger is in the range of 90-150° C.

9 . Method according to claim 1 wherein the temperature of the cooling liquid as it leaves the heat exchanger is at least 2° C. in some embodiments at least 10° C. below the temperature of the cooling liquid as it enters the heat exchanger.

10 . Method according to claim 1 wherein the temperature of the heating liquid as it enters the heat exchanger is in the range of 70-95° C.

11 . Method according to claim 1 wherein the temperature of the heating liquid as it exits the heat exchanger is at least 2° C. in some embodiments at least 10° C. above the temperature of the heating liquid as it enters the heat exchanger.

12 . Method according to claim 1 wherein the heating liquid is circulated through a flash vessel which supplies steam to the concentrator.

13 . Method for manufacture of carboxylic acid comprising the steps of
subjecting a carbon source to a fermentation step to form a carboxylic acid, which fermentation step comprises the steps of fermenting a carbon source by means of a micro-organism in a fermentation broth to form carboxylic acid and neutralizing at least part of the carboxylic acid by adding a magnesium base selected from magnesium oxide and magnesium hydroxide, thereby obtaining a magnesium carboxylate, subjecting the magnesium carboxylate to an acidification step wherein the magnesium carboxylate is contacted with HCl in an aqueous environment to form an aqueous mixture comprising carboxylic acid and magnesium chloride, subjecting the aqueous mixture comprising carboxylic acid and magnesium chloride to a separation step, to form an effluent comprising carboxylic acid and an aqueous magnesium chloride solution providing an aqueous magnesium chloride solution with a magnesium chloride concentration of 10-30 wt. % to a concentration step where water is evaporated, resulting in a concentrated magnesium chloride solution with a magnesium chloride concentration of 30-50 wt. %, wherein the concentration step is carried out in one or more stages, wherein at least one of the stages is conducted at elevated pressure, withdrawing the concentrated magnesium chloride solution from the concentration step, and providing it to a thermohydrolysis reactor, the reactor being at a temperature of at least 300° C., withdrawing MgO from the thermohydrolysis reactor in solid form, and withdrawing a HCl containing gas stream having a temperature of at least 300° C. from the thermohydrolysis reactor, providing the HCl-containing gas stream having a temperature of at least 300° C. to a cooling step, where the HCl-containing gas stream is contacted with a cooling liquid, withdrawing a HCl-containing gas stream with a temperature below 150° C. from the cooling step, circulating the cooling liquid through a heat exchanger where energy from the cooling liquid is transferred to a heating liquid which circulates from the heat exchanger to the concentration step.

14 . Method according to claim 13 comprising the further steps of
recycling the magnesium oxide withdrawn from the thermohydrolysis reactor at least in part to the fermentation step, and/or
recycling the HCl-containing gas stream derived from the preconcentrator at least in part to the acidification step, wherein both recycling steps are carried out.

Assignees

• Purac Biochem Bv

Inventors

• De Vries Johannes Jeichienus
• Frediansyah Raymon

Classifications

• C01B7/035

  Preparation of hydrogen chloride from chlorides · CPC title

• C12P7/40

  containing a carboxyl group {including Peroxycarboxylic acids} · CPC title

• C01F5/10 Primary

  by thermal decomposition of magnesium chloride with water vapour · CPC title

• C12P7/44

  Polycarboxylic acids · CPC title

• B01D1/28

  with vapour compression · CPC title