CS266688B1 - A method for processing fine tar sludge from a coal gasification process - Google Patents

Abstract

The solution lies in the method of processing "fine tar sludges from the coal gasification process by their simple distillation with the addition of coal, the addition of coal is necessary to ensure a loose distillation residue. The resulting distilled distillate is separated into an organic and aqueous phase based on different specific gravity.

Description

The present invention relates to a process for treating fine tar sludge from a coal gasification process comprising a solid phase and a liquid phase with an aqueous and an organic component.

During the gasification of coal, condensation is formed by cooling the raw gas, which is divided according to density into light tar, phenolic water and heavy and fine tar sludge, which are separated during the subsequent purification of the phenolic water.

Fine tar sludge can be defined as a heterogeneous mixture of organic matter, a certain amount of mechanical impurities and water. It differs from heavy tar sludges mainly by the grain size of mechanical impurities and the content of the organic phase of the mixture (grain size below 1 mm).

Fine tar sludges are not currently used. They settle to the bottom of the tanks, from where they are continuously or once transported to the sludge and waste landfill.

The construction of these landfills for tar sludges is very demanding and expensive, their maintenance is complicated, the work is harmful to health workers and operators. After filling the landfill, the construction of other landfills must be ensured. It is also necessary to take into account the negative impact on the environment in the vicinity of tar sludge landfills, manifested by a permanent haze of harmful fumes of foul-smelling substances.

The solution to the issue of appropriate disposal of fine tar sludge remained in the Czechoslovak Socialist Republic and in other countries at the stage of operational experiments, which dealt with the possibilities of direct incineration of fine tar sludge or their return to technological equipment. None of these methods have been fully proven in practice and are not known to be in continuous operation.

The essence of the solution according to the invention lies in the simple distillation of fine tar sludges at a temperature of 1E0 to 36 ° C after the addition of coal grain size from coal dust up to 40 mm, in an amount of 5 to 40% by weight. The addition of coal, which has a considerable sorption capacity, ensures the binding of the polymeric and higher molecular components of the distillation residue to its considerable surface, and thus ensures the flowability of the distillation residue without unnecessarily increasing the distillation temperature. The small grain size of the fine tar sludges would cause the formation of a free-flowing, solid distillation residue when distilling them without the addition of coal.

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After subsequent cooling and condensation, the vapor phase of the distillation is divided into an aqueous and an organic component on the basis of different specific gravities.

The products obtained according to the above process can be used energetically by burning them (bulk distillation residue). The organic components of the distillate can be used as raw materials in the chemical industry / the possibility of processing as light tars in pressurized gas plants /. The aqueous component of the distillate can be processed in the technological process of degassing wastewater, which is an essential part of any coal gasification operation. Equipment for the treatment of fine tar sludge must meet the following conditions: Distillation of the vessel is simple, without internal filling. Inside the vessel is a stirrer, which also serves as a wall scraper. The built-in vapor outlet from the distillation vessel prevents the escape of mechanical impurities.

The distilled vapor phase condenses in the condenser, is discharged to the condensate tank, where it is divided according to specific weights. The device must be able to clean with steam.

In one embodiment possible on pressurized gas plants, the coal is added via a separate line from the tank to the top of the distillation vessel. The distillation residue will remain in the distillation vessel unless its temperature drops to about 60 ° C (in the above embodiment it is a batch process). Cooling is accelerated by blowing the vessel with the distillation residue with technical nitrogen. The exhaust is introduced into the flue gas heating pipe. The distillation residue is then discharged from the bottom of the vessel into a container which takes it away. By means of the metering device, the distillation residue will be added to the redlers, through which the coal with a grain size of 0 to 10 mm is conveyed in an amount of 150 to 200 t / hour. from the dryer to the heating plant. The distillation residue is dosed (a single amount of 4 t) at a time interval of 1 to 2 hours. It is advisable to use pre-dried coal and vacuum distillation.

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Table 1 ·> * «!» · ** «··

Common composition of fine tar sludges from the brown coal gasification process (grain size below 1 mm). The composition of fine tar sludges changes in part according to the technological conditions of gasification and the quality of the coal charge.

Mechanical impurities / under 1 mm / 39.4 wt.

Asphaltenes10,2

Acid polymerizing oils4,1

Phenols8,3

Alkaline organic matter0.7

Neutral content of organic substances18.5

Water18.8

Example

Fine tar sludges from the brown coal gasification process (grain size below 1 mm) were distilled at a temperature of up to 250 ° C at atmospheric pressure with the addition of 10% by weight of pre-dried brown coal (grain size 1 to 10 mm).

Table 2

Qualitative parameters of pre-dried brown coal.

. Water content Ash content. Calorific value

30.77 wt.

13.04 wt.

15.66 MJ / kg

Condensation of distilling vapors gave a distillate with separated organic and aqueous phases.

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An overview of ο tar sludge distillation products under the above conditions. These are fine tar sludges.

Distillate up to 250 ° C 38.2 wt.

Distillation residue 61.7% by weight

Distillation losses 0.1 wt.

Table 4

Composition of distillate up to 25 ° C of fine tar sludges (based on the original charge for distillation).

Phenols Alkaline share organic matter 6.9 wt. 0.5 wt. Neutral share Water organic matter 13.4% by weight 17.5% by weight

Table 5

Composition of the neutral content of organic substances.

Alkanes Uncondensed cycloalkanes 10.5 wt. 8.2 wt. Condensed cycloalkanes . 13.7 Alkylbenzenes 12.1 Indans, tetralins _; 13.4 Alkylnaphthalenes 25.7 Acenaphthenes 13.6 Benzothiophenes 2.8

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Composition and mechanical properties of the distillation residue / distillation of fine tar sludges up to 25 ° C /.

Ashes 19.8 b wt. Flammable component mechan. particles 55.1 Asphaltenes 12.9 Monovalent phenols 0.5 Acid polymerizing oils 5.2 Other organic substances 6.5

Heat of combustion 'Bulk angle Flash point

29.9 MJ / kg

36 ° above 260 ° C

Claims (1)

OBJECT OF THE INVENTION Process for the treatment of fine tar sludge from a coal gasification process to produce a free-flowing non-integral combustible product, characterized in that the fine tar sludge is mixed with coal having a moisture content of 5 to 40% by weight and a grain size of up to 40 mm in a ratio of 1: 0.05 to 0.4, volatiles are distilled off from the mixture at 180 DEG to 360 DEG C. with constant stirring, which, after condensation, separates into organic and aqueous phases.