The article presents a method of controlling the size of droplets generated by a system that sprays a high-viscosity liquid containing particles of a solid body, i.e., a catalyst. The work is a continuation of previous research concerning the spraying of liquids with a catalyst, which improves the efficiency of the process. As a result of the conducted CFD calculations, it was found that to bring the catalyst to the system, a droplet with a diameter of at least 30 µm should be generated. The tests were carried out on a laboratory scale on a model isopropanol-water system. A polymer containing Raney nickel particles was added to the suspension. The analysis of the obtained data confirmed the possibility of generating droplets with the desired diameters in order for the liquid carrying the catalyst to not evaporate before it is delivered to the combustion chamber. The designed and constructed test system allows the diameters of the generated droplets to be controlled by changing the settings of the spraying nozzle. Moreover, it enables the parameters of the process, and the spraying itself, to be controlled. In further work, tests on a real 0.5 MW facility are planned. Due to the use of a catalyst, a greater degree of fuel burnout can be obtained, and the dynamics of the combustion process can be improved. Additionally, the parameters of the emitted exhaust gases and ash composition can also be enhanced.

This article presents the concept of a method of improving the dynamics of combustion in boilers operating in power plants, cogeneration plants, and heating plants by introducing a catalyst that is fed with a carrier in the form of droplets. Thanks to the proposed method, a greater degree of fuel burnout can be obtained, which, in turn, results in lower energy consumption in the case of producing the same amount of power. The parameters of the emitted exhaust gases and ash are also improved. The method described in the article involves the adding of a catalyst to the dust pipe of the boiler, which improves the combustion parameters. The catalyst was implemented using a sprayer/nebulizer. In order to obtain the correct flow parameters, the sprayer was modeled using CFD calculations. The calculations include trajectories, velocities and concentrations with regards to various flow parameters. Particular attention should be paid to the model of the evaporation of moving droplets. The results of these calculations enable the parameters that guarantee that the catalyst reaches the dust channel outlet in the desired form to be assessed. The analysis is an introduction to experimental research that is carried out on a medium and large scale.

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The review presents the D2-law of droplet evaporation, which is used to describe the spraying process involving the evaporation of droplets. This law, the subject of numerous publications, can be successfully applied to describe the droplet evaporation process under various conditions, including the calculations of the process of feeding the boiler with a liquid that contains catalyst particles. To date, not a lot of work has been devoted to this issue. The paper is a continuation of previous research concerning the spraying of liquids with a catalyst, which improves the efficiency of the process. The conducted analysis showed that the experimental data from previously published work are very compatible with the data obtained from the D2-law of droplet evaporation. At the standard speed of about 20 m/s of an aerosol flowing through a dust duct, droplets in the stream should be observed up to a distance of 1 m from the outlet of the apparatus supplying the system. Under such flow conditions, a droplet’s lifetime must be above 0.05 s. The dependence between a droplet’s lifetime and its diameter and temperature was determined. The obtained results confirmed that the effective droplet diameter is above 30 µm. Such droplets must be generated and then fed to the boiler for the catalyst to work properly. This law is an engineering approach to the problem, which uses relatively simple model equations in order to determine the evaporation time of a droplet.

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