CS259131B1 - A method of reducing emissions from wastewater, especially ammonia - Google Patents

Abstract

The essence of the method of reducing emissions from wastewater by desorption into an air stream is that this air is further blown into a layer of glowing fuel as a gasification medium.

Description

The invention relates to a method for reducing the emissions of waste water, especially ammonia, occurring. releasing dissolved gases, toxic and odorous substances into the atmosphere.

In many plants, especially in the treatment of solid fuels by gasification or degassing, waste water is produced which contains numerous dissolved gases such as ammonia, sulfane, carbon dioxide, poured hydrogen, odorous and poisonous substances, etc., often in concentrations below the economic usability limit. . During the handling of these water, these harmful substances are always released from them, which are the source of the characteristic unpleasant odor around these plants. Ammonia is known to have a toxic effect on aquatic organisms already at relatively low concentrations and that its presence in surface waters has a negative effect on the oxygen content of them. For example, in the case of brown-coal gasification, 0.3 to 1 kg of waste water containing 3 to 5 grams of ammonia per liter is produced per kg of treated fuel.

These disadvantages are overcome by the method of reducing wastewater emissions by desorption into the air stream according to the invention, which is characterized in that the air is further blown into the glowing fuel layer as a gasification medium.

The advantage of the solution according to the invention is based on the fact that the pressure of said harmful substances and ammonia above the solution is relatively high

-high, therefore these substances are quite easily transferred to the atmosphere. Waste ammonia water from coal gasification contains, for example, 4.5 g of ammonia per liter, whose vapor pressure at a temperature of approximately 40 ° C of cooling water is about 1.4 kPa * The same ammonia vapor pressure has air of 19.28 g · M ~ ^ at the same temperature. Thus, it is possible to transfer relatively large amounts of ammonia and other substances by simple desorption into the air used for technological purposes and thus reduce their content in water and thus release of pollutants into the environment. in further waste water handling. A further advantage is that the ammonia content is beneficial not only ecologically but also operationally, for example, at reduced costs in the dewatering of wastewater, where the presence of larger amounts of ammonia increases the losses of the extractant by saponification. Advantageously, known methods and apparatus by which the air is forced to flow countercurrently can be used to transfer the solutes from the waste water to the air by desorption. A further advantage of the process according to the invention is the constant dependence of the production of waste water and thus of said pollutants on the consumption of gasification air, thus eliminating the need for water accumulation. The content of substances in the water then does not quantitatively exceed the possibilities of their transfer to air.

Λ

The process according to the invention is described in more detail by way of example of its application in brown coal gasification.

-1

The plant, which produces 40,000 rams of low-pressure generator gas by gasifying brown coal with air and steam, consumes 20,000 rpm of air for blowing under the generator grates. When cooling gas, 15 m · of waste water is dispensed per hour with a content of about 4 g NHx per liter, ie about 60 kg of ammonia per hour. In a counterflow tower, this water is ventilated through air for gasification, releasing 2.6 g of 1 Hm · m of air from the water, among other substances, ie.

W. 1 kg · h. Thus, 86.7% of the ammonia is disposed of in this way with 0.53 g of NH3 remaining, ie 13.3% of the original amount.

The process according to the invention can be used in all plants in which waste water containing air-desorbable substances of gaseous or liquid form is present, and at the same time it is possible to use air enriched with these desorbed substances for gasification, in particular for coal processing plants and other.

Claims (1)

Method for reducing emissions from waste water, in particular ammonia, by desorption into the air stream, characterized in that the air is blown further into the glowing fuel layer as a gasification medium.