Brazhnik I. Improvement of Processes in Inert Gas System on Tankers During the Oil Shipment

To solve the scientific and technical problem related to the improvement of the inert gas supply system on tankers, the analysis of the main ways to increase the efficiency of production in ship generators of inert gases of their total volumes was performed and a new method of forced ventilation of tanker cargo spaces was developed. The object of the study is the process of accelerated inertization of the cargo space of the tanker through the use of inert gases forced supply. The subject of the study is a technological system of extraction and supply of inert gases into cargo space of tanker. The main volume of the dissertation describes the reproduction of the complete process of inertization of cargo spaces on tankers. At the first stage the process of dispersion of heavy fuel, which goes to the generation of inert gases, is selected and considered. The influence of the degree of flow twist on the quality of cavitation treatment of heavy fuel using the cavitation process is considered. In the end, the dependences reflecting the influence of the channel geometry and the initial flow kinematics on the general indicators of the cavitation cavity inside the working chamber of the cylindrical channel are obtained. It is established that increasing the flow rate of fuel at the entrance to the working chamber leads to an increase in the transverse dimensions of the cavity zone. The degree of flow overlap in the channel reaches 96%. It is proposed to use values ​​from 17 to 26 m / s as the speed range. For the range of cavitation numbers Ω = 0.02–0.5, the calculated values ​​of the length of the cavitation zone should correspond to the range from 5.434 to 0.896 of its width. The main part of the dissertation also considers the process of forced supply of inert gases directly into the working volume of the cargo space. The change of the general indicators of inertization of the tanker is theoretically investigated on the basis of the developed mathematical model. It is established that due to the introduction of forced ventilation: the final value of the height of temperature stabilization inside the cargo space of the tanker is limited to values ​​from 67% to 58%; forced supply of inert gases increases the quality of the process because for any size of the cargo space of the tanker under all identical conditions, the estimated time of the inertization process is reduced by 62%; the distribution of oxygen along the height of the cargo space is not homogeneous because it varies from 0.43 to 1.14% and depends on the height of the inert gases filling the working space of the cargo space of the tanker. The main part of the dissertation presents the results of experimental research. Based on them, with a standard error of less than 2.8%, it was found that due to the cavitation treatment of the fuel flow, its total consumption at identical volumes of inert gas generation decreases to 23.1%. Also, it was found that the reduction of the inertization time of the tanker due to the transition from standard to forced ventilation can exceed 50%. To improve the process of tanker inertization, a method of location of measuring sights and nozzles for supply of inert gases into the working space of the cargo space has been developed and described. The method is made taking into account the features and main characteristics of the inertization process, which were obtained during the research. The practical value of the obtained results is determined in the work. Based on the obtained dependences in time of the rate of change of oxygen concentration and temperature of two-phase mixture of air with inert gases, it is possible to implement practical recommendations in: operation of shipping companies and shipbuilding and repair enterprises during construction or modernization of tankers; in the educational process to improve the skills of ship mechanics. All the results of the performed scientific researches, as well as the developed methods and programs of calculations are introduced into the educational process of NU "OMA". The developed system of forced ventilation of inert gases is implemented on the ship type tanker. Level of fuel consumption compared to the standard operation of the system was reduced by 2.96%. The use of forced ventilation cut inertization time by 34%, and the reduction of oxygen concentration was 7.8%. Implementation is confirmed by relevant acts. Key words: tanker cargo space, inert gases, forced ventilation, cavitation pressure in fuel, oxygen concentration, multiphase flow temperature, measuring sights, technology and nozzle for inert gas supply.