CN100488931C

CN100488931C - Composite extraction and rectification method for separating methylal-methanol-water by adding salt

Info

Publication number: CN100488931C
Application number: CNB2006100389585A
Authority: CN
Inventors: 顾正桂
Original assignee: Nanjing Normal University
Current assignee: Nanjing Normal University
Priority date: 2006-03-21
Filing date: 2006-03-21
Publication date: 2009-05-20
Anticipated expiration: 2026-03-21
Also published as: CN1821200A

Abstract

The salt adding composite extraction and rectification process of separating methylal-methanol-water mixed liquid includes the following steps: the first water extraction of the mixed liquid and extracting separation with 10-20 % salt-containing glycol in the proportion among material, water and salt-containing glycol being 1 to 0.3-1 to 0.5-1 at tower top temperature of 42-43 deg.c to obtain methylal of purity over 99.8% in the tower top and the salt-containing mixed extractant as the effluent; the subsequent treatment of the salt-containing mixed extractant in a regeneration tower to obtain methanol of purity over 99.8% in the tower top; treating the rest part in a methanol recovering tower for reuse; and using the salt-containing mixed extractant circularly. The present invention can separate methylal, methanol, formaldehyde and water effectively.

Description

The method of salting, compounding, extracting, rectifying separating methylal-methanol-water

Technical field

The present invention relates to a kind of salting, compounding, extracting, rectifying technology, be specifically related to the isolating composite extractant of composite extraction and rectification and the salting, compounding, extracting, rectifying processing method of the processing method, particularly a kind of methylal of a kind of salting, compounding, extracting, rectifying separating methylal-methanol-water and methylal-methanol system.

Background technology

Methylal is mainly used in anionite-exchange resin, the also solvent of conduct and special fuel, generally adopt acid catalyzed process production at present: synthetic methylal, methyl alcohol, formaldehyde and the water mixed solution of generating of methyl alcohol and formaldehyde, because methylal and methyl alcohol, formaldehyde and water all form azeotropic, adopt the precise distillation method to separate mix products, reflux ratio (R) is controlled at about 30:1, and not only energy consumption is big, and only can obtain the methylal about 85%.Adopt the alkaline hydrogen peroxide oxidation to remove formaldehyde at present, add the sodium Metal 99.5 distillation and can remove methyl alcohol, rectifying obtains the high purity methylal then, this method sepn process complexity, sepn process energy consumption height.

Summary of the invention

The present invention will provide a kind of new adding salt composite extracting solvent and separating technology, compare with traditional technology, and the novel method processing step is fairly simple, and water consumption reduces and reusable edible.The present invention adopts the adding salt composite extracting agent to separate methylal-methyl alcohol-water mixed liquid with the compound extracting tower, stock liquid is behind adding salt composite extracting, can once obtain the methylal more than 99.8%, yield can reach more than 96%, obtain 99.8% above methyl alcohol simultaneously, water consumption less and can recycle, non-wastewater discharge.This technological process is simple, and energy consumption is low.

The method of salting, compounding, extracting, rectifying separating methylal-methanol-water mixed solution provided by the invention is that a composite extraction and rectification separates methylal-methyl alcohol-aqueous systems, and its step is as follows:

Methylal, methyl alcohol, water mixed liquid are earlier through adding the water extraction, and then (wherein through saliferous ethylene glycol, the mass content of salt is 10～20%) extracting and separating, raw material: water: the inlet amount ratio of saliferous ethylene glycol is 1:0.3～1:0.5～1, tower top temperature is controlled at 42～43 ℃, cat head gets the methylal more than 99.8%, and the tower still flows out the saliferous mixed extractant;

Above-mentioned saliferous mixed extractant is handled through regenerator column, and the regenerator column cat head gets 99.8% methyl alcohol, and all the other cut parts are handled through methanol distillation column, recycle;

The saliferous mixed extractant recycles.

" with salt " described in the above scheme is meant to add sodium-acetate or Potassium ethanoate;

Described saliferous mixed extractant is meant: contain above-mentioned salt, ethylene glycol and water;

Described " all the other cuts recycle " is meant: the remainder that the adding raw material separates behind methylal, the methyl alcohol recycles.

Specifically, the adding salt composite extracting step is as follows: solution after methyl alcohol and the formaldehyde reaction rectifying (cut 1) enters the compound extracting tower, the control tower top temperature is at 42～43 ℃, NS2, the charging of NS1 position above raw material respectively of extraction agent S2 water and extraction agent S1 ethylene glycol and sodium-acetate (or Potassium ethanoate), cat head is the methylal more than 99.8%; Compound extracting tower still saliferous mixed solution is handled through regenerator column, regeneration overhead distillate respectively contain methylal cut 6. with cut 7., 6. cut is delivered in the methylal reactor, 7. cut is delivered to the dilute methanol recovery tower and is handled, 8. cut is 99.8% above methyl alcohol, and reason back, regenerator column bottom solvent is delivered to cut and 3. recycled.

More particularly: solution behind the esterification reaction rectification (cut 1.: methylal 88%, water 2%, methyl alcohol 10%) enter the adding salt composite extracting tower, the control tower top temperature is at 42～42 ℃, cat head is the methylal more than 99.8%, extraction agent S2 water and extraction agent S1 ethylene glycol and 10～20% sodium-acetates (or Potassium ethanoate) NS2, the charging of NS1 position above raw material.Compound extracting tower still mixed solution is handled through regenerator column, regeneration overhead distillates cut 6. (99.8% methyl alcohol) and cut 7. respectively, 6. cut is delivered in the methylal synthesis reaction vessel, reason back, regenerator column bottom solvent is delivered to cut and is 3. recycled, 7. cut delivers to methanol distillation column, 8. treated cut is delivered in the methylal reactor, and 4. 9. cut deliver to cut.The composition of composite extractant is: extraction agent S2 is a water; Extraction agent S1 is ethylene glycol, sodium-acetate (or Potassium ethanoate); Raw material is F, F:S2:S1=1:0.3～1:0.5～1.

The processing condition of sepn process: each tower still temperature control, reflux ratio, feed entrance point and stage number are shown in Table 1 in the sepn process.

Table 1 sepn process processing condition

The invention provides a kind of rectifying and separate methylal, methyl alcohol, formaldehyde and water with the composite extraction and rectification combining method, therefore this method of not appearing in the newspapers as yet both at home and abroad develops effective separating technology, not only helps product purity and improves, and more helps cutting down the consumption of energy.

Description of drawings

Fig. 1 separates the process flow sheet of methylal-methyl alcohol-aqueous systems for adding salt composite extracting;

Fig. 2 is the adding salt composite extracting experimental installation.

Embodiment

Embodiment 1, and the compound extracting experimental installation is with reference to Fig. 1, Fig. 2, and wherein 1 is feed sump, and 2 is pump, 3 is glass rotameter, and 4 is tower still sampler, and 5 is electric mantle, and 6 is the tower still, 7 is tower still thermometer, and 8 is solvent 2 storage tanks, and 9 is pump, and 10 is solvent 1 storage tank, 11 is pump, and 12 is glass rotameter, and 13 is glass rotameter, and 14 is glass fibre cotton and chuck, 15 is filler, and 16 is the cat head sampler, and 17 is refluxing opening, 18 is the tower top temperature meter, and 19 is electromagnetic wand, and 20 is condenser.Adopting methyl alcohol and formaldehyde synthetic methylal-methyl alcohol-water mixed liquid is raw material, analyzes through the SP-6800 chromatographic instrument, and composition is shown in Table 2, and forms in the table to be mass content.Stock liquid is through adding salt composite extracting tower extracting and separating, and tower top temperature is 42～43 ℃, can get the methylal more than 99.8%, and the methylal yield reaches more than 96%, must contain the methanol aqueous solution (disregarding extraction agent S1) about 7～8% at the bottom of the tower.Experiment is carried out under normal pressure, and the tower internal diameter is 22mm, and the Stainless Steel Helices of interior dress φ 3*3 θ type is through measuring this height equivalent to one theoretical plate HETP=27mm with standards system.The tower still heats with electric mantle, overhead product discharging and raw material, solvent, charging are all measured with glass rotameter, trim the top of column is regulated with electromagnetic wand, the tower still is extracted out with vacuum pump, form at the bottom of the tower and be shown in Table 2, the tower bottom flow fluid is returned to solvent regeneration tower, the regenerator column operational condition is as shown in table 1, solvent recycles after dealcoholysis, dehydration, and after regenerator column was handled, composition was shown in Table 2 at the bottom of cat head, the tower, cat head is delivered to methanol distillation column and is handled, can get 99.8% above methyl alcohol, as methylal synthetic raw material, other cut all can be recycled.

Table 2 adding salt composite extracting separating resulting

Claims

1, a kind of method of salting, compounding, extracting, rectifying separating methylal-methanol-water mixed solution, step is as follows:

Methylal, methyl alcohol, water mixed liquid extract through adding water earlier, and then through saliferous ethylene glycol extracting and separating, raw material: water: the inlet amount ratio of saliferous ethylene glycol is 1: 0.3～1: 0.5～1, and in the described saliferous ethylene glycol, the mass content of salt is 10～20%;

The saliferous mixed extractant recycles;

Described salt is sodium-acetate or Potassium ethanoate;

Concrete steps are: 1. solution-cut enters the adding salt composite extracting tower after the building-up reactions rectifying, and the control tower top temperature is at 42～43 ℃; Extraction agent S2 is a water, and reaching extraction agent S1 is ethylene glycol+salt, NS2, the charging of NS1 position above raw material respectively, and cat head is the methylal more than 99.8%; Compound extracting tower still mixed solution is handled through regenerator column, regeneration overhead distillate respectively cut 6. with cut 7.; 7. cut is delivered to methanol distillation column and is handled, and 6. cut is 99.8% above methanol solution; 8. cut is delivered in the methylal reactor, and reason back, regenerator column bottom solvent is delivered to cut and 3. recycled.

2, according to the method for the described salting, compounding, extracting, rectifying separating methylal-methanol-water of claim 1 mixed solution, it is characterized in that, processing parameter is as follows: temperature is 76～85 ℃ at the bottom of the compound extracting Tata, reflux ratio 3～4,64～101 ℃ of regenerator column tower top temperatures, 172 ℃ of column bottom temperatures, reflux ratio 1～3.