Safety And Effectiveness Evaluation Of Tank Washing For Typical Bulk Liquid Chemical

With the rapid development of shipping market,chemical ship transportation has become an important way to transport liquid chemicals in bulk.There are a wide variety of liquid chemicals in bulk with complex physical properties and high hazards,and the safety and cleaning effect of chemical cabin washing has drawn much attention.At present,the research on the mechanism of tank washing is not clear,and quantitative research is lacking.Therefore,the concentration of gaseous chemicals is tested and chemical physical parameters(viscosity,density,contact Angle,surface tension)and working parameters(working pressure)are explored.Temperature is of great significance to the safety and effect evaluation of tank washing.In this paper,experiments and numerical simulation are carried out based on the washing safety experiment platform,the washing effect experiment platform and FLUENT software.The main research contents are as follows:(1)The concentration of gaseous chemicals is detected through the safety experiment platform of tank washing.ANSYS-ICEM was used to establish the same model as the experiment,and then ANSYS-FLUENT was used to simulate the safety process of tank washing,and finally the change of chemical concentration in different positions was obtained.The results showed that the volatilization rate of different kinds of chemicals was stable in time domain,that is,under the given volatilization point source,the volatilization rate tended to be stable in time domain with little change.In terms of spatial characteristics,the volume ratio of chemical gas phase components differs greatly in different spatial locations.The closer the distance to volatile point source is,the larger the average volume ratio is.The volume ratio of chemical gas phase components at specific points in space has obvious fluctuations in time domain characteristics.(2)Based on the safety experiment of tank washing,taking high-risk non-inert degassing operation as the research object,the ventilation and degassing operation process of 8000 DWT chemical ship cabin after tank washing was simulated by numerical simulation method,and various factors affecting the actual cargo hold ventilation and degassing effect were systematically studied.The results show that the air inlet rate,vent arrangement and number of vents have great influence on the degassing effect of the cargo hold,and the larger the cargo hold capacity,the higher the influence degree of these factors.This study provides a comprehensive and effective judgment method for the actual safety state in the degassing operation of chemical tanker cargo hold,and also provides a valuable theoretical basis for the actual degassing operation of chemical tanker and the design of ship cargo hold.(3)Chemical clearance rate was calculated through the experimental platform of tank washing effect,ANSYS-ICEM was selected to establish the same model as the experiment,and then ANSYS-FLUENT was used to simulate the experimental process of tank washing.Finally,the functional relationship between working parameters and chemical clearance rate over time was obtained through calculation.Functional relationship between physical property parameters and chemical clearance rate changing over time,working parameters,functional relationship between physical property parameters and chemical clearance rate changing over time.Then,under the condition that the physical experiment and numerical simulation are well checked,the intelligent numerical experiment is carried out.Weight analysis is carried out on the sample set of intelligent numerical experiment through the importance model,and the influence of physical property parameters and working parameters on the cleaning effect is analyzed.The results show that the influence of working pressure,temperature,surface tension and contact Angle on tank washing effect is positively correlated,while the influence of viscosity and density on tank washing effect is negatively correlated.The comprehensive impact degree of physical parameters is about 25%.The comprehensive impact of work parameters is about 75%.