Influence of Micro- and Macrostructure of Atomised Water Jets on Ammonia Absorption Efficiency

Abstract

Ammonia has a very wide range of applications. Its worldwide production exceeds 230 million tonnes per year. Due to its properties, ammonia causes a serious threat to human life and health when released uncontrolled into the environment. Research carried out in the word shows that this substance may be effectively neutralised by absorption in water. The aim of research described in this paper is to determine the influence of key parameters of the micro- and macrostructure of water streams on the course of the ammonia absorption process. During the studies, different types of water nozzles were used, with similar efficiency and supply pressure, but characterised by different parameters of the micro- and macrostructure of the produced stream. The experiments were divided into two stages. In the first one, the macro- and microparameters of the streams were measured, while in the second one, the changes in ammonia concentration were established during delivering spray jet generation by different nozzles. Among the basic parameters of the macrostructure, the spray angle and liquid distribution in the jet (spray intensity) were determined, while for the microstructure, the droplet size distribution and mean droplet diameters were measured. Ammonia concentration was measured by means of a photoionisation detector (PID). In order to evaluate the absorption efficiency of different water spray jets, the apparent absorption rate (kp) and the half-time of concentration reduction (t½) in the kinetic range were established. The study has confirmed that atomised water jets are an effective method for neutralising ammonia released into the environment. The research has a practical aspect and shows that the structure of atomised water streams influence the course of the absorption process. Increasing the spray angle in a conical stream leads to an improvement in the quality of water atomisation and helps increase ammonia absorption. Moreover, it was also observed that for the absorption of spatial ammonia clouds, use should be made of nozzles generating streams with full spray cones and high uniformity of spray and dispersion.