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Removal of residual chlorine in the hydrolysate of process equipment - — Centrifugal extraction equipment

by:Deyuan      2020-09-06
The hydrolysis products of dimethyl dichlorosilane ( Hydrolysate) Is one of the important intermediates of organic silicon industry, can be directly used in the preparation of alpha and omega Dihydroxy polydimethylsiloxane ( 107 silicone rubber) Or through pyrolysis ring dimethyl siloxane mixture ( DMC) And further preparation of silicone oil, silicone rubber, silicone resin and other products.
a, the source of residual chlorine in hydrolysate
the current domestic hydrolysate preparation widely used concentrated acid hydrolysis process, namely the level of concentrated acid hydrolysis, loop level of dilute acid hydrolysis, two levels of alkaline cleaning, two levels of water to wash the technology preparation of residual chlorine quality score 10 x 10 - 6~250×10- 6 the hydrolysate. Hydrolysis of free chlorine residual due to incomplete separation in the hydrolysate, and hydrolyzed by incomplete residue containing Si - Cl material, make the residual chlorine mass fraction on the high side.
2, why want to reduce the residual chlorine in the high chlorine hydrolysate quality score?
concentrated acid hydrolysis process will consume large amounts of alkali, produce a large amount of waste water. At the same time, in order to strengthen the water washing or alkaline cleaning effect to let hydrolysate is mixed with water or alkali more fully, but the stirring in the stirred tank too violent causes hydrolysate emulsification and difficult to settlement separation, this makes the hydrolysis products can be limited. In addition, the residual chlorine for up to 10 x 10 - 6~250×10- 6 hydrolysate, in the process of its 107 silicone rubber as raw material preparation not only consumes more KOH catalyst, but also results in the decrease of polymerization rate slows, polymer yield, light transmittance of the product variation, chlorine ion content increases, etc. ; And as raw material in the cracking in the process of preparation of DMC, will increase the consumption of cracking catalyst KOH, causing cracking unit of driving cycle is shorten, pyrolysis products of low boiling point product six methyl siloxane (three D3) The series of problems such as acid value, chlorine ion content increases.
3, in addition to the drawbacks of the traditional method and chloride
in order to reduce the residual chlorine in the hydrolysate, use tower device abroad and water vapor counter-current extraction method, the residual chlorine is quality score dropped to 1 x 10 - 6 the following; Of the hydrolysate by porous adsorption material absorption, also can be mass fraction of residual chlorine in the hydrolysate dropped to 1 x 10 - 6; Using liquid membrane washing tower and extraction and flow process of residual chlorine in the hydrolysate can be control in 5 x 10 - mass fraction 6.
however, the water vapor of the chloride process temperature is 110 ~ 160 ℃, the temperature too high can cause a dramatic rise in the hydrolysate viscosity, difficult to control. Using adsorption materials leads to increased quantity of solid waste and adsorption materials of metal impurity into problems affect the quality in the hydrolysate, and in addition to the cost of chlorine is higher. Using liquid membrane washing tower and although and flow extraction process can effectively reduce the residual chlorine in the hydrolysate, but still require the two levels of alkaline cleaning, process more complex. To solve above problems, therefore, the development of a more simple and efficient hydrolysate of residual chlorine removal process is very meaningful.
4 machine, centrifugal extraction to remove residual chlorine effective
centrifugal extraction machine is a kind of fast and efficient new liquid-liquid extraction separation device, compared with traditional extraction equipment such as stirred tank and the combination of the settling tank device as well as the extraction tower and so on, on the working principle has essential difference. Centrifugal extraction machine is the use of motor driven rotary drum high-speed rotation, the density is different and incompatible two liquids in under the action of shear force produced by the rotation of the impeller to complete mixing and mass transfer, and under the effect of high-speed rotation of the centrifugal drum rapid separation. Hydrolysate and compatibility and the density difference of water completely meet the requirements of centrifugal extraction machine for material.

experimental process: the residual chlorine quality score about 10-1000 x 6 hydrolysate as raw material, using centrifugal extraction machine as strengthening dimethyl dichloride silane hydrolysis of residual chlorine removal effect of the device, study USES centrifugal extraction machine washed by step fast and efficient removal of residual chlorine in the hydrolysate of process.
type centrifugal extraction pause: CWL50 - M, extraction technology co. , LTD. Zhengzhou days; Produced steam condensate: sell
by the experimental results show that: with the increase of water temperature and centrifugal extraction machine impeller diameter increase, gradually reduce the mass fraction of residual chlorine in the hydrolysate. As hydrolysate and the volume of water than the increase of hydrolysate and the increase of feed flow rate, mass fraction of residual chlorine in the hydrolysate was gradually increased. In water temperature 95 ℃, the impeller diameter of 50 mm, hydrolysate with the volume of water than 0. 3:1, the hydrolysate feed flow rate under the condition of 90 ml/min, the centrifugal extraction machine through a washing residual chlorine in the hydrolysate mass fraction can be controlled in 3 x 10 - Less than 6.
the process once the industrialize, could significantly shorten the existing dimethyl dichloride silane hydrolysis process, at the same time ease by extraction and separation of contradictions can hydrolysis products.

the article references: the efficient removal of residual chlorine in the hydrolysate technology research,
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