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.

Effect of mist nozzle supply pressure on the ammonia absorption process

“…The NF 15 nozzle has a slightly higher K-factor value as compared to the TF 6. However, the jet produced by it, over the entire pressure range, is characterized by a high droplet density and low dispersion level (Wąsik et al 2022). The tests carried out on the flow characteristics of all the nozzles suggest that the smallest changes in flow rate occur at high pressures.…”

“…The nozzles were selected due to their purpose and various spraying parameters. They were the subject of studies published by the authors (Wąsik et al 2022, Majder-Łopatka et al 2016, Majder-Łopatka et al 2017, Wąsik et al 2021. The important parameters affecting the efficiency of gas sorption include, among others, the size of the droplets fed through the nozzle, the shape of the water stream and the droplet fall time.…”

“…In ammonia sorption the value of k p and t ½ is influenced by many factors related to the water feed and its parameters. Among these factors, the following are particularly important: the type of spray nozzle and its supply pressure, as they determine the extent to which the space is sprinkled and how long the drops remain in the air (Wąsik et al 2022).…”

“…Research studies conducted by (Węsierski 2015, Majder--Łopatka et al 2016, Buchlin 2017, Hua et al 2018, Shen et al 2017, Wąsik et al 2022 demonstrate that NH 3 is extremely effectively sorbed by water sprays owing to its good solubility in water. At 0°C, 900 g of NH 3 becomes soluble in 1 dm 3 of water.…”

“…Results of scientific research, confirmed in practice in rescue operations, suggest that changing the supply pressure of the spray device has a major impact on the micro-and macro--structural parameters of the sprayed water jet (Majder-Łopatka et al 2017, Wąsik et al 2021, Ochowiak et al 2020). Among these, the average diameter of the droplets produced, the spray spectrum, the water flow rate, the spray angle, and the intensity of the spray are particularly important for the efficiency of the sorption process (Majder-Łopatka et al 2016, Buchlin 2017, Wąsik et al 2022, Warych 1998.…”