SU1326352A1 - Method of cleaning equipment from thermostructural polyamide - Google Patents

Abstract

The invention relates to the chemical industry and allows to intensify the process by reducing the time for cleaning and disposal of waste. Production waste, f-caprolactam is loaded into the equipment, dehydrated, then it is maintained at a temperature of 200-260 ° C until the polymer is completely dissolved. After that, the mixture is drained from the equipment, and the acid residues are neutralized with a 2-4% solution of sodium carbonate, followed by washing with hot water. At the same time, the ratio of contaminated products and industrial solution is 1: 2-3.5. Waste from the production of caprolactam is a mixture of dicarboxylic acids. 1 tab. (L

Description

Ibregenie relates to a method of cleaning equipment from thermostructured polyamide and can be used in the chemical industry for cleaning continuous polymerization apparatus, fiery sets, injection molding blocks.

The purpose of the invention is to intensify the process by reducing the time for cleaning and disposal of waste.

Example 1. Dp of cleaning the contaminated g of the apparatus and parts of the water-: waste is loaded into the apparatus, held, when heated, first to SO-IO C to remove

water evaporation, o

and then at 200260 s for 18-48 hours until polymer is completely dissolved. Thereafter

the mixture is drained from the apparatus, and the remains of 20 tatok melt on the walls of the apparatus

neutralized with 5.0 m of 2.0% konakisl is washed off by neutralization with a 2-4% solution of NajCO at 80-90 ° C, followed by washing of the neutralized water with hot water.

A polyamide device for caprolactam of the type ANP-5.5, equipped with a heating jacket and having a working volume of 5.5 m, is emptied before cleaning by draining off residues of polycaproamide. After unloading, there are soils on the walls of the apparatus — a thermo-structured solid product in the amount of 0.8 tons. Then it is cooled to 70-100 0 and poured in two steps: 21.1% aqueous acid layer (cyclohexane oxidation waste) in the amount of 8, 0 m at 70-80 ° C, providing the ratio thermostructured polymer - the dry residue of the aqueous layer as 1: 2.

The composition of the aqueous layer in the calculation of the cloth residue, wt.%:

Adipinova

acid49,8

Glutarova

acid12,6

Amberna

acid.6,4

Schavelev. acid7,5

Ants

acetic acid and others

acids19.0

Cyclo gek with an ol ol

and cyclohexanone 4.7

First, 4.5 m of an aqueous solution of acids is poured into the apparatus, then it is evaporated at 100-110 ° C. As rhenium is used, water is fed

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the concentration of sodium carbonate, which are fed with a temperature of 70-80 ° C in the apparatus, pre-cooled 25 to .70-80 with the heating off during the day. Then the temperature in the apparatus is raised to 95-100 ° C and maintained at this temperature for 8 hours.

30 Completeness of neutralization is controlled by the absence of laxable COg bubbles. The neutralizer is drained and the apparatus is rinsed with distilled water. After processing, the internal surface of the apparatus becomes visually clean.

Example 2. The apparatus for continuous polymerization of capillary type ANP-5.5 with a jacket for heating 4Q with heat carrier before cleaning is emptied by draining from residues of polycaproamide and cooled to 80 C. After unloading, there are contaminants on the walls of the apparatus - a burnt thermal 4g solid structure in the amount of 0.6 tons. Then, a 45.3% water-acidic layer of oxidation products of cyclohexane in the amount of 4.8 m with a temperature of 80 ° C is slowly poured into the apparatus with a ratio of thermally structured polymer - the dry residue of water The layer is 1: 3.5.

The composition of the aqueous layer in the calculation of the dry residue, wt.%:

Adipinova

acid88,3

Glutarova

acid4,6

50

55

the remaining 2.5 m solution of acids at | the above temperature conditions, to prevent the evaporation of evaporation residue. The removal of water vapor and gas is carried out through the pipeline through a cooler and an absorber. The end of the evaporation of water is characterized by increasing the temperature of the mixture in

machine. The monitoring of the process is carried out according to the temperature of the melt. After complete dehydration of the acids, the temperature of the dinyl is raised to 260 ° C, ensuring that the temperature of the melt is maintained, and held for 48 hours until the polymer is completely dissolved.

The melt of waste acids from the apparatus is drained at 160-165 C. 0s5

concentration of sodium carbonate, which are fed with a temperature of 70-80 ° C in the apparatus, pre-cooled 5 to .70-80 with the heating off during the day. Then the temperature in the apparatus is raised to 95-100 ° C and maintained at this temperature for 8 hours.

0 Completeness of neutralization is controlled by the absence of impermeable bubbles of COg. The neutralizer is drained and the apparatus rinsed with distilled water. After processing, the internal surface of the apparatus becomes visually clean.

Example 2. A device for the continuous polymerization of caprolactam of the type ANP-5.5 with a jacket for heating Q with a heat carrier before cleaning is emptied by draining from polycaproamide residues and cooled to 80 ° C. After unloading, there are burns on the walls of the apparatus g is a structured solid product in the amount of 0.6 tons. Then, a 45.3% water-acid layer of oxidation products of cyclohexane in the amount of 4.8 m with a temperature of 80 ° C is slowly poured into the apparatus, providing a ratio of thermo-structured polymer to the dry residue This is 1: 3.5.

The composition of the aqueous layer in the calculation of the dry residue, wt.%:

Adipinova

acid88,3

Glutarova

acid4,6

0

five

Amber acid, 4

Shaveleva

acid1,7

Ants

acetic acid and others

acid2.5

Cyclohexanone

and cyclohexanol 2.5

After the apparatus is filled with an aqueous solution of acids, the temperature of the solution is raised to 100-110 s for 4 hours, followed by a uniform boiling of the reaction mixture until the water is completely evaporated, held for 12 hours, and then the temperature is raised to 285 ° C in the apparatus (temperature 260 ° C) and maintained at this temperature for 18 hours until complete dissolution of the polymer. The apparatus is then emptied with a discharge at 200 ° C. Controlling the cleaning process with a mixture of dicarboxylic acids and subsequent rinsing the apparatus with a solution of sodium carbonate and water is carried out as in Example 1 with the difference that sodium carbonate solution is used in an amount of 5.0%. m and hold it in the apparatus for 4 hours.

Example 3. Parts contaminated with polycaproamide, in an amount of 500 kg, are loaded into a container with an 8 m plug-in jacketed jacket for heating with an organic heat transfer medium, 30.0% solution of dicarboxylic acids in the form of an aqueous layer of cyclohexane oxidation products in quantity 5 is poured there , 0 m, providing the ratio thermostructured polymer - dry residue as 1: 3.

 The composition of the aqueous layer in the calculation of the dry residue, wt.%:

Adipinova

acid62,3

Glutarova

acid 10,0

Amberna

acid6,3

Shaveleva

acid5,4

Ants

acetic acid and others.

acids 10,9

Cyclohexanone

and cyclohexanol 5.1

The apparatus is then cleaned in Example 2. After processing, the surface of the parts becomes visually clean.

The table shows the comparative indicators of the proposed and known methods.

:

As follows from the table, the proposed technical solution makes it possible to use for cleaning devices and parts contaminated with polycaproamide, low-toxic, affordable, cheap production waste of caprolactam containing dicarboxylic acids, which reduces the cost, increases the quality of washing devices,

operating at normal pressure, without degrading the environment.

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Claims (1)

Invention Formula The method of cleaning equipment from thermostructured polyamide by treating the internal surface of equipment with a carboxylic acid-based washing solution when heated to 200-260 with water washing, characterized in that, in order to intensify the process by reducing the time for cleaning and recycling waste, water cleaned surface. This is additionally subjected to neutralization with a 2.0-4.0% solution of sodium carbonate, and as a washing solution, use is made of the production of a-caprolactam of the following composition, m.ch .: Adipine acid49.8-88.3 Glutarova acid 12,6-4,6 Amberna acid6.4-0.4 Shaveleva acid7.5-1.7 Formic acid vinegar etc. acid19.0-2.5 Impurities4.7-2.5, when the ratio of contaminated products to the washing solution is 2-3.5. For machines operating at normal pressure Completeness cleaning Almost full The melt of dicarboxylic acids (adipic, glutaric, succinic, oxalic and other impurities), obtained from 20-40% aqueous waste Low toxicity Solvent consumption per 1 meter of equipment, kg 1200 Redshstor M. Dylsh Compiled by M. Voevodina Tehred A. Kravchuk Order 3223/8 Circulation 540 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 For pressure and normal pressure machines Incomplete Melt dehydrated caprolactam Low toxicity Toxic 60 1000 Proofreader M. Pojo