Medium assisted liquid fuel nozzle technology for a low-NOx burner
Virolainen, Janika (2023)
2023
Ympäristö- ja energiatekniikan DI-ohjelma - Programme in Environmental and Energy Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
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Hyväksymispäivämäärä
2023-03-28
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202303203000
https://urn.fi/URN:NBN:fi:tuni-202303203000
Tiivistelmä
Atomization is a process where liquid fuel is dispersed into droplets for enhanced combustion. Industrial processes utilize large number of atomizers which vary in design, size and working principle. In addition to these, the atomization quality is dependent on the fuel type and environ mental conditions. The impact of different parameters must be known in order to choose the best atomizer for a given application. Droplet size and distribution, emission performance, operating range and flame shape can be affected with a suitable atomizer selection. Due to pressure for stricter measures in emission regulation, demand for higher combustion efficiency, and increasing number of applications, more specified nozzle adjustment is required.
The aim of this thesis was to study different geometrical parameters and compare the perfor mance of two different types of internal-mixing twin-fluid atomizers, namely Y-jet and T-jet. Y-jet atomizers are commonly used in industrial processes and extensively studied in literature, but the available data of the newer T-jet atomizer design are scarcer. The studied parameters were the size and number of orifices and the design of the liquid inlet. Their impact on emission formation, atomizer working regime, droplet size and distribution was investigated experimentally to create design principles for atomizers in power plant and process low-NOx burners. Experimental tests consisted of water spray tests in a lab scale test rig and combustion tests in a recovery boiler and two circulating fluidized bed boilers.
The results are based on a total of 20 atomizers; 8 Y-jet and 12 T-jet atomizers. The results show that with the selected geometrical parameters, Y-jets produce a stable spray in a wider pressure regime than T-jets. T-jets with a large liquid inlet area compared to the atomizing air inlet area have a pressure region where the flow does not settle, and noise generation is increased. However, T-jets contributed to a lower emission formation, they produced a finer spray with a smaller average droplet diameter and consumed less atomizing air.
The aim of this thesis was to study different geometrical parameters and compare the perfor mance of two different types of internal-mixing twin-fluid atomizers, namely Y-jet and T-jet. Y-jet atomizers are commonly used in industrial processes and extensively studied in literature, but the available data of the newer T-jet atomizer design are scarcer. The studied parameters were the size and number of orifices and the design of the liquid inlet. Their impact on emission formation, atomizer working regime, droplet size and distribution was investigated experimentally to create design principles for atomizers in power plant and process low-NOx burners. Experimental tests consisted of water spray tests in a lab scale test rig and combustion tests in a recovery boiler and two circulating fluidized bed boilers.
The results are based on a total of 20 atomizers; 8 Y-jet and 12 T-jet atomizers. The results show that with the selected geometrical parameters, Y-jets produce a stable spray in a wider pressure regime than T-jets. T-jets with a large liquid inlet area compared to the atomizing air inlet area have a pressure region where the flow does not settle, and noise generation is increased. However, T-jets contributed to a lower emission formation, they produced a finer spray with a smaller average droplet diameter and consumed less atomizing air.