Katsuji Yamaguchi

Calculating Benzene Concentration Emitted During Tanker Loading

Benzene emissions occur during marine vessel loading operations. These emissions are regulated in several countries. Accordingly, we developed a one-dimensional benzene diffusion model advancing in the vertical direction within cargo tanks. Unlike other models, the model presented in this paper is based on a 1/10 scale modeling of eddy diffusion at the liquid surface during initial loading operations and advection under the tank roof during final loading operations. The model input parameters include loading rate, flow rate, cargo tank size, and temperature dependent saturated concentrations. The validity of the model is demonstrated by comparisons with onboard measurements. Other models exist. However, they are based on empirical estimates rather than rational modeling.

Workplace Concentration of Benzene Vapor during Marine Transfer Operations and Its Risk

International Maritime Organization (IMO) recognized that chronic exposure to very low concentration of benzene vapor in air of the order of a few parts per million may cause cancer.It is necessary to protect the health of sailors exposed to benzene vapor to the same level as that of shorebased workers performing compatible tasks.Measurements of onboard environment benzene vapor concentration for tankers carrying benzene during loading, transit, unloading and tank cleaning operations of routine tanker operation were made during all seasons of the year for typical size of 500 tons and 1000 tons cargoes.The vapor samples were collected from 11 tankers in 3 points on the ship to the canister and were subsequently analized by gas chromatography. The benzene vapor concentrations were varied with operations and onboard points.The risk of health of sailors exposed to benzene vapor is assessed using time and area averaged concentration. Effectiveness of wearing respiratory equipment for reducing health risk of sailors due to benzene exposure during marine vessel transfer operations is suggested.

Minimization of Cargo Residue in Piping for Chemical Tankers

An analysis is presented which describes and predicts the process of drainage of noxious liquid substances from piping arrangement consisted of horizontal and vertical pipe line in chemical tanker during the operation of air blowing. The process is modeled in three stages according to the location of the head of flowing single air slug in pipe line, that is, stage 1: the head of slug locates in horizontal pipe, stage 2: the head locates in vertical pipe, stage 3: the head locates outside the outlet of pipe line.Analytical expression is derived by taking into account the important factors in each stage.The results predicted by the analysis in stage 1 and stage 2 are compared with experimental data obtained for various operational conditions using water and air as working fluid. Good agreement with experimantal data of pressure and the quantity of residue in horizontal pipe are shown.

Minimization of Cargo Residue in Piping for Chemical Tankers (Part1 Experiments)

To prevent the marine pollution from discharge of the harmful liquid cargo into the sea, reduction of the quantity of cargo remained in the tank after the unloading is required. The effectiveness of the method of gas blowing which is commonly applied to the present chemical tanker for minimizing the quantity of residue in the piping arrangement for the carriage of noxious liquid substances is examined. Characteristics of fluid flow and the quantity of residues during the processes of gas blowing in horizontal pipe using water and air as the working medium have been measured under various operational conditions and piping arrangements. The effects of experimental variables on them are investigated. It is suggested that gas blowing is an effective stripping method and discusses recommend-ed measures to reduce the quantity of the residue in the piping system.The method for calculating the residues in the range of high quantity in horizontal pipe have been developed. The results predicted are consistent with the experimental data.