DE2638323C2 - Methods of cleaning surfaces - Google Patents

Description

a) from solid, crystalline or brittle glass-like organic at temperatures above 10 ° C Substances and / or by supercooling to temperatures between +10 and -180 ° C hardened organic solids and / or at temperatures between +10 and - Liquids solidified at 180 ° C and / or at temperatures between +10 and -180 ° C consists of solid gases,

b) is used for cleaning the surfaces at temperatures at which it is crystalline or is brittle glass-like, and

c) after the surfaces have been cleaned, it melts, evaporates or does not have any other detrimental effect or has a disruptive effect.

2. Method of cleaning the surfaces of containers and autoclaves with a particulate matter from 0.05 to 2 mm in diameter containing gas and / or liquid jet of an outflow velocity between 40 and 300 m / sec when the gas and / or liquid carrier medium under pressure between 3 and 800 bar flows out comprises from a nozzle, wherein the solid particles after the nozzle the gas and / or Liquid jet are mixed in, characterized in that the solid for cleaning the Surfaces is used at temperatures at which it is crystalline or brittle glass-like, and from at temperatures above 10 ° C solid, crystalline or brittle vitreous organic substances and / or by subcooling to temperatures between +10 and -180 ° C hardened organic solids lind / or from liquids solidified at temperatures between +10 and -180 ° C and / or at Temperatures between +10 and -180 ° C consists of solid gases with which the container or The autoclave is filled when it is used again or when the container is used again or autoclaves arise or, if necessary, before further use of the container or autoclave by heating escape.

3. The method according to claim 1 and 2 for cleaning surfaces of the polymerization in aqueous Autoclave used for dispersion, characterized in that the solid consists of ground ice of 0.5 to 1.2 mm in diameter and a temperature between -0.5 and -180 ° C.

4. The method according to claim 1 and 2 for cleaning surfaces of the polymerization of Vinyl chloride used in aqueous dispersion, characterized in that the autoclave Solid from ground ice with a diameter of 0.5 to 1.2 mm and / or polyvinyl chloride powder with a sieve fraction of 0.1 to 1.2 mm.

The interior cleaning of autoclaves with agitators, which are used, for example, for the production of polyvinyl chloride be used, reaction vessels and

ίο other containers, such as those in the used in the pharmaceutical industry, by manually scraping off adhering wall coverings, by spraying out with water at pressures between 50 and 800 bar or a combination both cleaning processes are carried out.

Impurities that are deep in the pores and grooves of the base material can only be removed difficult or impossible to remove. These residues form the starting point for new wall systems.

Sandblasting that enables deep cleaning is ruled out in most cases, because Contamination by sand in the subsequent batches from individual grains of sand in the container remain even with thorough post-cleaning, cannot be ruled out. Grains of sand that are in Set down inaccessible areas of the autoclave, for example at the lead-throughs of the stirrer shaft, may only become available after a few batches and thus get into the product.

When the product is further processed, this can lead to injury and thus uselessness highly polished surfaces of the processing machines. The success of this cleaning method stands thus out of proportion to the possible consequential damage.

That is why the sandblasting of autoclaves with agitators is often done with the agitator removed to avoid the dangers indicated above.

The aim of the invention is therefore to find a method for cleaning surfaces in which the Cleaning agent does not have any adverse effects when the container is used further. Simultaneously This cleaning process is intended to achieve a pore-deep purity.

The invention relates to a method for cleaning surfaces with a solid particle from 0.05 to 2 mm in diameter containing gas and / or liquid jet, which has an outflow velocity between 40 and 300 m / sec when flowing out of the under pressures between 3 and 800 bar has standing gas and / or liquid carrier medium from a nozzle, wherein the solid particles after the nozzle are mixed with the gas and / or liquid jet, characterized in that the Solid

a) from solid, crystalline materials at temperatures above 10 ° C or brittle vitreous organic 'substances and / or by subcooling to temperatures between +10 and -180 ° C hardened organic solids and / or from at temperatures liquids solidified between +10 and -180 ° C and / or at temperatures between +10 and -180 ° C consists of solid gases,

b) is used for cleaning the surfaces at temperatures at which it is crystalline or brittle is glassy, and

c) after cleaning the surfaces it melts, evaporates or does not have any other disadvantageous or negative effects. has a disruptive effect

The method is particularly suitable for cleaning the surfaces of containers and autoclaves with a gas and / or liquid jet containing solid particles from 0.05 to 2 mm in diameter with an outflow speed between 40 and 300 m / sec when the outflow is under pressures between 3 and 800 bar standing gas and / or liquid carrier medium from a nozzle, wherein the solid particles are added to the gas and / or liquid jet after the nozzle, which is characterized in that the solid, crystalline or ^{solid at temperatures above 10 0 C with solids.} glass-like organic material and / or by sub-cooling to temperatures between +10 and - 180 ⁰ C cured organic solids and / or from at temperatures between +10 and - 180 ⁰ C solidified liquid and / or at temperatures between +10 and -180 ⁰ C consist of solid gases with which the container or autoclave is filled with further use or with further use tion of the container or autoclave or, if necessary, escape by heating before further use of the container or autoclave.

Another preferred embodiment of the process consists in the cleaning of autoclaves used for polymerization in aqueous dispersion, which is characterized in that the solid consists of ground ice with a diameter of 0.5 to 1.2 mm and a temperature between -0.5 and - 18O ⁰ C exists.

Another preferred embodiment of the method according to claim 1 and 2 for the purification of Surfaces of autoclaves used for the polymerization of vinyl chloride in aqueous dispersion in that the solid consists of ground ice with a diameter of 0.5 to 1.2 mm and / or polyvinyl chloride powder with a sieve fraction of 0.1 to 1.2 mm.

The surprising of the method according to the invention is that with the invention solid particles used an advantageous cleaning effect is achieved if they are by a gas and / or liquid medium of high outflow speed accelerated to the to be cleaned Affect surfaces. When using the method according to the invention for the purification of Containers or autoclaves, it is particularly advantageous that they are used as blasting media Solid particles do not have an adverse effect on further use of the container or autoclave exercise.

The inventive method is by no means limited to the cleaning of containers and Restricted interior surfaces of the autoclave In principle, the method according to the invention is suitable wherever the hitherto customary sandblasting or water sandblasting because of the dangers involved due to sand residue was inapplicable, albeit the problem of cleaning containers and Inner surfaces of the autoclave, as they are often required in the chemical sector, by the inventive Method is particularly advantageous to solve

At temperatures above 1O ⁰ C solid crystalline or glassy organic substances are, for example, all organic substances with melting point above 10 ⁰ C, forming a solid crystalline or glassy phase and having no elastic properties. In particular, it is to be understood as meaning polymeric substances whose glass transition temperature is above 10 ° C. (Table I lists polymers with a glass transition temperature above 10 ° C.) Substances which, due to their molecular character, are waxy or have a lubricating effect are excluded.

Than by subcooling to temperatures between

ίο +10 and -18O ⁰ C curable organic solids are to be described in particular organic polymeric materials, by sub-cooling in the temperature range between +10 and - can be converted to 180 ⁰ C in brittle glassy or crystalline modification and whose glass transition temperatures fall below this range . Such polymers are, for example, the polymers listed in Table II:

Tabl

Polymer

of the monomer

Glass transition temperature ⁰ C

Styrene

Methyl methacrylate

Acrylonitrile

Vinyl chloride
Ethyl methacrylate

Vinyl acetate

+ 103 +100.7 + 91.0 + 77 + 62 + 28

Tab II

Polymer

of the monomer

Glass transition temperature, ⁰ C

Methyl acrylate

Vinylidene chloride

Propylene

Ethyl acrylate

Chloroprene

Isoprene

Butadiene

Ethylene

+ 3

- 18th

- 20th

- 23

- 50

- 77

- 86 -122

The solid particles are advantageously used in their most brittle or hardest modification Bring application that can be achieved by supercooling, with in individual cases between the advantage the associated cleaning effect and that required to achieve the hardest modification Cooling costs must be considered. In general, when using polymerisation powders or - aim for a temperature range below the transformation temperature in the brittle, The glass-like state also depends on the choice of the carrier medium, gas or liquid to vote. It is natural when using very low temperature particulate matter attached as a carrier medium a gas or air jet, because of the lower heat capacity compared to Liquids such as water and the temperature caused by adiabatic cooling

ture reductions of the gas jet during expansion are to be exploiteda However, this heat transfer from the Carrier medium on subcooled abrasives due to the extremely short contact times of subordinate Meaning.

When at temperatures between +10 and -180 ⁰ C solidified liquids are understood to mean those having a crystalline or glassy brittle modification in this temperature range. Such liquids are, for example, solutions of emulsifiers and / or protective colloids, and / or inorganic salts and / or organic salts, monomers suitable for polymerizations and / or organic solvents, in particular water.

Often it is also appropriate fixed gases in the temperature range between +10 and -180 ⁰ C a fixed modification have to use as an abrasive, in particular solid carbon dioxide.

In some cases it can be advantageous to use mixtures of the solids mentioned, for example to prevent the blasting agent from sticking together prevent. When combining several solids, in certain cases a synergistic Reinforcement of the cleaning effect cannot be ruled out.

When using the mentioned solids or substances converted into crystalline or brittle glass-like solids by subcooling to temperatures between +10 and -180 ⁰ C, there is no need to fear that these particles will interfere with the later use of the container or autoclave, if such Substances are selected with which the container or autoclave is filled anyway or which are produced in these containers or autoclaves.

In the case of the cleaning treatment of machines according to the invention, there is no need to damage the bearings etc. to be feared because the solid particles used do not show the abrasive effect known from sand.

The blasting agent reaches the grain size between 0.05 and 2 mm, preferably 0.1 to 1.2 mm Use. It may be necessary to convert the solid particles into suitable, for example To grind heat-insulated mills, for example, solid carbon dioxide is added. The abrasive will have the required grain size and temperature then in a thermally insulated admixture which otherwise corresponds to the admixer used in the known sandblasting process

The gas and / or liquid jet, which preferably flows out of air and / or water at pressures between 3 and 800 bar from a nozzle and thereby reaches speeds between 40 and 300 m / sec, accelerates the mixed solid particles so that they hit the with high energy surfaces to be cleaned. The loading of the gas and / or liquid jet with solid particles is in the range from 0.5 to 15 kg / Nm ² gas or 20 to 200 kg / m ² liquid. The gas, preferably air, consumption is between 50 and 800 Nm ³ / h , the liquid speed, preferably water consumption, at 50 to 500 l / min.

Containing the abrasive that flows off with the cleaning water during or after cleaning The mixture can be recovered from the liquid phase by filtration. Residual grains that have not melted or evaporated. On top of the subsequent container or autoclave approaches, no disadvantageous Effect.

Example! 1

One inside coated with polyvinylchloride crusts Vessel was filled with high pressure water of 400 bar and

cleaned with a water jet at a throughput of 200 l / min.The cleaning time was approx.

4 min / m ² . The nozzle distance to the wall was in

Average at 300 to 500 mm. The wall could admittedly from the crusts

be cleaned, so that a relatively clean impression was created, but the pores and grooves were always still filled with PVC. The same thing happened in places a thin PVC film on approx. 20% of the cleaned area remained.

These PVC residues that have not been removed form starting points for new ones in the subsequent production

Incrustations, so that the container after 8 approaches

had to be cleaned again.

Example 2

The same container as in Example 1 was charged with high-pressure water under the same conditions cleaned as in Example 1. However, the high-pressure water (400 bar) a sub-cooled to -30 ⁰ C PVC with a grain size of 0.8 to 1.2 mm in a handelsübli Chen injector mixed in at the nozzle outlet. The amount of PVC added to the high-pressure ^{water was approx. 90 kg / m 3 of} spray water. The cleaning time was also about 4 min / m ^{2 of the} container wall; the nozzle spacing was approx. 300 to 500 mm.

The container wall cleaned in this way was bare metal. No deposits could be found in the pores. A polishing effect did not occur. Subsequently they could be cleaned in this way th container 52 approaches up to one again required cleaning.

Example 3

A rusted and with paint residues so pump was blasted with compressed air at 4 bar overpressure and a throughput of approx. 100 Nm ³ / h. The compressed air was ice grains with a grain size of approx 2 kg / Nm ^{3 were} added. The temperature of the ice was around -15 ° C. The rust spots and paint residues could be completely removed in this way. A slight polishing effect could even be seen on the mechanically machined areas. The storage of the pump cleaned in this way remained completely undamaged.

Claims (1)

Patent claims: 1. Method of cleaning surfaces with a particulate matter. from 0.05 to 2 mm in diameter containing gas and / or liquid jet, which has an outflow speed between 40 and 300 m / sec when the gas under pressure between 3 and 800 bar flows out and / or liquid carrier medium from a nozzle, wherein the solid particles after the nozzle are mixed with the gas and / or liquid jet, characterized in that the Solid