CS257501B1 - A method of disposing of chlorinated organic compounds - Google Patents

Abstract

A method for the disposal of chlorinated organic compounds, in which organic chlorinated substances or their mixtures with at least one organic substance containing 0.5 to 25% by weight of hydrogen, optionally containing at least one -OH, =C=O, -COOH group in the molecule and/or with organic combustible waste are fed into a fluidized bed furnace, where they are burned at temperatures higher than 700 °C at atmospheric pressure and the resulting hydrogen chloride is removed from the flue gases, preferably by washing with water in adiabatic absorption. The bottom product is technical hydrochloric acid, which can be further used in various chemical processes. The method is applicable primarily in the production of organic semi-finished products and dyes, pesticides, in the production of medicines and in various extraction and degreasing technological processes.

Description

The present invention relates to a process for the disposal of chlorinated organic compounds using highly efficient fluidized bed combustion.

Chlorinated organic compounds are used in many industrial operations, in the chemical industry in the manufacture of semi-finished products, dyes, pharmaceuticals and pesticides. Because of their excellent solubility, they are used in large quantities as solvents, degreasers and as extraction agents. Even with the possibility of regeneration, considerable amounts of these highly toxic substances are eliminated in the above-mentioned processes, for which a suitable method of disposal has not yet been found.

One of the procedures for the disposal of difficult wastes is their incineration. In most cases, perfect combustion of organic substances or mixtures thereof under suitable conditions leads to the formation of harmless carbon dioxide and water. In conventional combustion processes, however, these suitable conditions are not always ensured and combustion, especially chlorinated organic compounds, leads to mixtures which, in addition to conventional combustion products, contain products of their oxidation and condensation radical reactions, sometimes very toxic such as phosgene, chlorinated biphenyls, dioximes and the like

A suitable method for the combustion of organic chlorinated compounds is fluidized bed combustion, the theoretical basis of which is the well-known fact that physical and chemical processes of much increased intensity take place in the boiling liquid. In this process, where the combusted substance is intimately mixed with the fluid-forming substances and the fuel and thus burns as if in a liquid, conditions are created to completely destroy the chlorinated organic substances. When they are combusted in a fluidized bed in the presence of a fuel preferably with a high hydrogen content, hydrogen chloride gas is produced as a product which is no longer contaminated by the destruction products of the chlorinated organic compound molecule.

Therefore, a process for the disposal of chlorine-containing organic compounds with recovery of hydrogen chloride from combustion gases by scrubbing with water under adiabatic absorption conditions has been established and tested. The resulting hydrochloric acid is then a useful product which can be used in a number of technological processes.

Combustion of carbon tetrachloride, dichloromethane, tri- and tetrachloroethane, dichlorobenzene, chlorophenol, DDT, HCH, chlorinated cresols and their mixtures in a fluidized bed at temperatures above 700 ° C and at atmospheric pressure has been experimentally tested. It was found that in all cases where at least 0.5 mol% was present in the flue gas. oxygen, hydrogen chloride is formed. The toxic products of destruction could not be demonstrated.

Accordingly, the present invention provides a process for the destruction of chlorinated organic compounds, characterized in that the organic chlorinated substances or mixtures thereof with at least one organic substance containing 0.5 to 25% by weight of the organic compound. hydrogen, optionally containing at least one -OH, = C = O, -COOH or with organic combustible wastes, are fed to a fluidized bed where they are combusted at temperatures above 700 ° C at atmospheric pressure and the flue gases are scrubbed in adiabatic absorption water. They enter the atmosphere through a fuse filled with activated carbon. The heel product of adiabatic absorption is technical hydrochloric acid, which can be further used in various chemical processes.

The examples below illustrate embodiments of the invention.

Example 1

Propane with air was combusted in a fluidized bed reactor with an internal diameter of 0.08 m. The inert particles were corundum with a particle size of 2 to 2.5 mm. The height of the expanded fluidized bed was 0.6-0.8 mm. The layer temperature was in the range of 730 to 850 ° C.

The reactor was made of stainless steel and was equipped with a ceramic flue gas transducer from which part of the flue gas was removed for analysis. The flue gases from the transducer entered the filled glass

Even a column whose stove was heated. Water was injected into the top of the column, and the resulting hydrochloric acid solution was removed from the digester through a condenser.

The effluents from the column were passed through an activated carbon charge. ’

The reactor was dosed 167 gh ¹ of carbon tetrachloride and 90 litrů.h ^- '· propane. 4.1 Nm.h of air were introduced for combustion. The linear velocity in the reactor under combustion conditions was about 0.8 ms *.

Flue gas samples were taken from the flue gas transducer for analysis. Upon absorption in a NaOH solution in water, no free chlorine was detected in the gaseous mixture. The oxygen content was 8.4% by volume. The foot product in the absorption column was a 33.5% hydrochloric acid solution. The chlorine yield was not less than 98% by weight. No unreacted carbon tetrachloride or other organic matter was detected in the activated carbon adsorption cartridge.

Example 2

2 kg was injected into the fluidized bed reactor under the same conditions as in Example 1.

1-I 3-1 h of dichloromethane and 120 l h of propane. 4.5 Nm.h of air was supplied for combustion. Under these conditions and a combustion temperature of 750 to 850 ° C, the linear velocity of the air in the reactor was about 1 m.s.

An analysis of the flue gas taken from the transducer revealed that the oxygen content was 0.9 mol%. The presence of free chlorine has not been analytically proven. The heel product of adiabatic absorption was 31% by weight of hydrochloric acid. The chlorine yield was 96% by weight. Neither unburned dichloromethane or other organic substances were detected in the activated carbon adsorption cartridge.

Example 3

Dichlorobenzene vapor from the evaporator was fed to the fluidized bed reactor described in Example 1. The temperature of the fluidized bed was 800-890 ° C. Prior to start-up, the fluidized bed was heated to 800 ° C with propane flue gas. Dosing of dichlorobenzene into the evaporator was then started and the vapors introduced into the fluidized bed while gradually reducing the propane feed. The temperature was maintained in this range by injecting dichlorobenzene of 600-620 g.h and air required for 3 -1 combustion at 4.8 Nm.h

The flue gas was taken from the reactor between the reactor and the absorber - the oxygen content was 2.5 mol%. Absorption in aqueous NaOH solution did not show the presence of free chlorine. Hydrochloric acid having a concentration of 32% by weight was obtained in an adiabatic absorber. The yield of chlorine based on the input amount was 95% by weight. Adsorption of flue gases to activated carbon did not detect the presence of dichlorobenzene or its possible chemical transformation products.

Example 4

In the same reactor as in the previous examples, an ethanolic solution of dichlorvinyltrichloromethylmethane was combusted at a temperature of 800 to 850 ° C. The feed mixture contained

4.4 wt. 10% by weight of chlorine. of this substance in ethanol. This solution was injected into the fluidized bed at 305 g / ^l . Combustion air was dosed 4.1 Nm ³ .h ^_1. After heating the fluidized bed to 800 ° C and starting the reaction, propane was no longer added to the reactor. The oxygen content of the flue gas was 3.3 mol%. Free chlorine was not detected in the flue gas.

Upon boiling of the hydrogen chloride from the flue gas in water, a solution containing 31 wt. hydrogen chloride. The total chlorine yield at steady state operation was 93%. No unburned organic matter was detected in the activated carbon adsorption cartridge.

Example 5

Into a fluidized bed reactor filled with a layer of corundum particles, after heating to temperature

750 ° C dosed liquid waste mixture of propanol, tetrachlorethylene and chlorinated cresols.

_ 3—1

The total chlorine content of the mixture was 2.8 wt. Into a reactor were fed 4.4 Nm .h air and 215 gh ³ waste mixture. The combustion temperature ranged from 800 to 880 ° C depending on the height of the fluidized bed and the amount of feed mixture. The oxygen content of the flue gas was 4.6% by volume. Free chlorine was not analytically proved in the flue gas.

In adiabatic absorption, hydrogen chloride was separated from the flue gases. The column bottom product contained 33 wt. hydrogen chloride. The chlorine yield based on feed was 92%. No organic substances were detected in the activated carbon adsorption cartridge.

As can be seen from the examples, the process according to the invention can be used in particular in the production of organic semi-finished products and dyes, pesticides, in the manufacture of medicaments and in various extraction and degreasing processes.

Claims (2)

1. A process for the disposal of chlorinated organic compounds by incineration thereof, characterized in that the organic chlorinated compounds or mixtures thereof with at least one organic compound containing a compound of the formula (I). 0.5 to 25 wt. hydrogen, optionally containing at least one -OH, = C = O, -COOH and / or organic combustible waste, are fed to a fluidized bed where they are combusted at temperatures above 700 ° C under atmospheric pressure in a reducing atmosphere and Hydrogen chloride is removed from the flue gas. 2. Method according to claim 1, characterized in that the hydrogen chloride is removed from the flue gas by scrubbing with water, preferably by an adiabatic absorption system.