Continuous crystallization method under control of multistage membrane

Patent metadata

Field	Value
Publication number	US-10675557-B2
Application number	US-201716314773-A
Country	US
Kind code	B2
Filing date	Nov 3, 2017
Priority date	Nov 3, 2017
Publication date	Jun 9, 2020
Grant date	Jun 9, 2020

Abstract

The present invention provides a continuous crystallization method under control of the multistage membrane modules, and belongs to the technical field of crystallization engineering. A crystallization solution is added to a crystallizer, and a stirring apparatus and a temperature control apparatus are started. After the system running stability, the loop of crystallization is started. Meanwhile, the coolant or antisolvent feed liquid loop is also started. The crystallization solution can respectively conduct crystal nucleation, growth and ripening in the multistage membrane modules, and then the crystallization solution is transported into a filter device and a drying apparatus to obtain the final crystal products. The desired crystal products can be obtained by the systematical control of the nucleation and crystal growth through the flow and the temperature of the crystallization solution, coolant or antisolvent feed liquid, and the contact time between two liquid phases.

First claim

We claim:

1. A continuous crystallization method under control of multistage membrane, wherein a continuous crystallization apparatus is composed by two loops;
a first loop: a first stirring apparatus is installed in a crystallizer with a jacket; the jacket is connected with a first temperature control apparatus through a pipeline; an outlet of the crystallizer is connected with a lower port of a first membrane module in a membrane module combination successively through a first peristaltic pump, a first rotameter, a first valve, a first thermometer and a first pressure gauge; one path of an upper port of a last membrane module in the membrane module combination is connected with an inlet of the crystallizer through a seventh valve; another path of the upper port of the last membrane module in the membrane module combination is connected with a filter device through a third valve; an upper port of the filter device is connected with an inlet of the crystallizer, and a lower port of the filter device is connected with a left port of a drying apparatus; a right port of the drying apparatus produces the final crystal product; a lower port of the drying apparatus is a dry gas inlet, and an upper port of the drying apparatus is a drying apparatus outlet, wherein the connection of the membrane modules is controlled by the valves;
a second loop: a second stirring apparatus is installed in a coolant or antisolvent feed liquid tank with a jacket; the jacket is connected with a second temperature control apparatus through a pipeline; the coolant or antisolvent feed liquid tank is placed on a precision electronic balance; the precision electronic balance is connected with a control system; an outlet of the coolant or antisolvent feed liquid tank is connected with an inlet of the coolant or antisolvent feed liquid tank successively through a second valve, a second rotameter, a second thermometer, a second pressure gauge, a second peristaltic pump, a rotameter combination, a temperature regulator combination, a meter combination and a membrane module combination, wherein a lower port of each membrane module is connected with a temperature regulator through the pressure gauge and the thermometer; a lower port of each temperature regulator is connected with a rotameter and then is connected in parallel and connected in series in the loops;
steps are as follows:
(1) preparing the nearly saturated crystallization solution, and transporting into a raw material kettle; opening the first stirring apparatus and the first temperature control apparatus to uniformly mix the crystallization solution; simultaneously opening the second stirring apparatus, the second temperature control apparatus, the precision electronic balance and the control system to uniformly heat the antisolvent and keep a stable balance reading;
(2) opening the control valves in the first peristaltic pump, the first valve and the membrane module combination; adjusting the first peristaltic pump to enable the crystallization solution to stably flow in the first loop;
(3) opening the second valve; starting the second peristaltic pump to enable liquid in the coolant or antisolvent feed liquid tank to circularly and stably flow in the second loop; controlling the temperature of the coolant in the membrane modules tube pass by adjusting the power of the temperature regulators of all stages to cool the stages of the membrane modules, wherein the temperature of the nucleation region is higher than that of the growth region by 2-20° C. and the temperature of the growth region is higher than that of the ripening region by 1-10° C.; controlling the flow velocity of antisolvent in the membrane modules shell pass by adjusting the rotameters of all stages to reduce the pressure of all stages in the membrane module combination so as to adjust the permeation rate of the shell pass antisolvent, wherein the pressure of the nucleation region is higher than that of the growth region by 2-20 kPa and the pressure of the growth region is higher than that of the curing region by 1-10 kPa; the residence time of the crystallization solution in the nucleation region, the growth region and the ripening region; respectively conducting crystal nucleation process, crystal growth process and crystal ripening process;
(4) until the circularly flowing crystal product in the first loop meets requirements, closing the seventh valve, opening the third valve, the filter device and the drying apparatuses and introducing dry gas to obtain the final crystal product at the outlet of the dry apparatus.

2. The continuous crystallization method according to claim 1 , wherein the membrane used in the membrane module is the hollow fiber membrane or the flat membrane.

3. The continuous crystallization method according to claim 1 , wherein the hollow fiber membrane or/and the flat membrane are organic membranes, inorganic membranes or composite membranes.

Assignees

• Univ Dalian Tech

Inventors

• Jiang Xiaobin
• Li Guannan
• He Gaohong
• Tuo Linghan
• Lu Dapeng
• Xiao Wu
• Li Xiangcun
• Wu Xuemei

Classifications

• B01D9/0013

  by indirect heat exchange · CPC title

• B01D9/0063

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

• B01D9/0054 Primary

  Use of anti-solvent · CPC title

• B01D9/0059 Primary

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

• B01D2009/0086

  Processes or apparatus therefor · CPC title