Isamu Fujita

Spilled Oil Tracking Autonomous Buoy System

Spilled oil damages not only the ocean environment but also the regional economy. In order to minimize such damages we are now developing a spilled oil tracking autonomous buoy system. The buoys used in this system are expected to send their location, and the meteorological and oceanographic data around them, to the land base in real-time while they drift with spilled oil. In the case that the buoy detaches from the spilled oil by external forces, it must be capable of detecting and tracking the spilled oil autonomously. In this paper, we first describe the concept of this system. This is followed by the development of two kinds of oil-detecting sensors installed on the buoy: a contact sensor and a non-contact sensor. The efficiencies of these sensors were verified by carrying out various water tank experiments. The buoy tracks spilled oil with descending and ascending procedures by controlling its buoyancy and movable wings. The developed control algorithm was validated with some water tank experiments using a simple buoy model. Finally, we carried out field experiments, such as data measurements and autonomous tracking experiments, using a new buoy model equipped with oil detecting sensors, GPS and an anemometer. The results of field experiments show the efficiency of this system.

Development of Spilled Oil Tracking Autonomous Buoy System

Spilled oil from stranded ship damages not only the ocean environment but also the regional economics. In order to prevent such damages from expanding, we are developing a system using autonomous buoys. When the oil spill accident happens, several buoys are dropped into the sea. While the buoys drift along with spilled oil, those send some useful data such as its location, the meteorological and oceanographic data around them, in real time. According to the effect of wind driven water currents on the free surface, the buoys tend to drift apart from spilled oil. Therefore, the buoys must have the function of detecting and tracking spilled oil. In this paper, the concept of the buoy system and the mechanism of tracking spilled oil are firstly introduced. Then, the sensors to detect spilled oil are described. Next, the numerical scheme is explained to design the buoy and verify its maneuverability. Some experiments using a buoy model were carried out to verify the maneuverability and tracking ability of this buoy. These results show that the buoy could track the target by using the developed tracking algorithm.

An Onboard Air Conveyer Oil Skimmer

A high power air conveyer oil skimming system and implementation on a real oil recovery vessel are presented. Port and Airport Research Institute (PARI) has succeeded in development of a new type of onboard oil recovery system. Development of the project has been in cooperation with the Shikoku Regional Bureau, Ministry of Land Infrastructure and Transport Japan (MLIT). The system employs a high-power vacuum blower for sucking liquid in gas-liquid multiphase form. Its applicability to an onboard oil recovery system has been experimentally investigated. The experiments have shown that the method can respond to the wide range of viscosity of the spilled oil and works well even in wavy sea condition. These results have been applied to the oil skimming system mounted on ISHIZUCH - an oil recovery vessel owned and operated by MLIT recently refitted by Mitsui Engineering & Shipbuilding Co., LTD

Steam Jet Pump For Oil Recovery And Reformation

ABSTRACT This paper discusses basic performances of the steam jet suction device and its potential application to the spilled oil recovery. The experiments were carried out on suction and ejection performance of the steam-driven jet pump as well as its other benefits such as breaking emulsion or an application to a beach cleaning device. The paper additionally includes some basic topics related to the process of emulsion breaking by surface active agents. The main conclusions of the study are (1) A steam-jet pump is basically suitable to recover and transfer high viscosity spilled oil because it realizes large suction power as well as very rapid heating which resolves the difficulty related to the high viscosity caused by the emulsification, (2) A steam-jet pump is also available for reforming the nature of the spilled oil. Emulsion breaking was observed to a considerable extent even without chemical agent, (3) A steam-jet pump has a potential application to a beach cleaning equipment. The steam-driven je...

Spilled Oil Tracking Autonomous Buoy

We are developing Spilled Oil Tracking Autonomous Buoy System (SOTABS), which is composed of a land base and several spilled oil tracking autonomous buoys (SOTAB), to detect and track spilled oil autonomously, sending real time data around them to the land base. This paper firstly deals with steady sailing performance of SOTAB-II with a sailboat shape for tracking spilled oil on the sea surface by controlling the rudder angle, and the area and direction of the sail, and then sea trials using a model of SOTAB-II with a cylindrical buoy shape to obtain its fundamental characteristics on motion.

An onboard vacuum suction spilled oil recovery system

A vacuum suction oil skimming system has been studied. The system employs a high power vacuum blower for sucking high viscosity oil. Its applicability to an onboard oil recovery system has been experimentally investigated using small-size models as well as a large-size model. The suction performance has been measured and is given in terms of liquid suction rates, oil and water fraction, friction loss and liquid holdup in the riser pipe in various simulated conditions including wave and current. An emulsified heavy oil whose viscosity is as high as 300,000 mPa.s was used. The results shows that the vacuum suction is a suitable method for recovering the spilled oil on the sea surface since the system has better performance on a wavy surface than a calm water. This work also includes the system overview and a basic design strategy for a real-size onboard oil recovery system which will be installed on a new oil recovery vessel.

In situ estimates of horizontal turbulent diffusivity at the sea surface for oil transport simulation

Despite many previous in situ estimates of horizontal diffusivity below the sea surface, horizontal diffusivity at the sea surface, which is a parameter required in the prediction of oil diffusion, has not been formulated. This study conducted in situ estimations to quantify horizontal diffusivity at the sea surface. To measure the horizontal diffusivity at and below the sea surface, clusters of thin sponge rubbers (simulating spilled oil), together with drifting buoys, were deployed on successive occasions in Sagami Bay, Japan. The experimental results revealed that horizontal diffusivity was larger at the sea surface than below. Based on the results, a procedure for estimating horizontal diffusivity at the sea surface was introduced to predict the diffusion of spilled oil, which was verified using numerical simulations. The simulation results showed good agreement with observations, suggesting the procedure is appropriate for the estimation of horizontal diffusivity at the sea surface.

A New Weir Skimmer Test for an Oil Recovery Vessel Dr.Kaiyo

An advanced weir skimmer for spilled oil recovery has been developed by Kinki Regional Bureau, Ministry of Land Infrastructure and Transport Japan. The new skimmer has an oil/water separation mechanism embedded in it and succeeds in a high concentration oil recovery from the sea surface. It has been installed in a new oil recovery vessel Dr. Kaiyo in March 2007. Prior to its installation, the skimmers oil recovery performance was closely evaluated by port and airport research institute (PARI) in a real scale oil spill test tank. The tank test has confirmed that the oil skimmer has excellent oil recovery performance, especially a high oil water ratio more than 80% even in severe sea condition. This paper gives mechanical description of the skimmer and detailed results of the full scale tank tests conducted by PARI as well as an overview of the vessel Dr.Kaiyo.

A New Oil Recovery System using Steam-driven Ejector

An application of steam-driven ejector to oil skimming system has been experimentally examined. Formation of W/O emulsion gives the spilled oil very high viscosity occasionally up to 1,000,000 mPas as well as volume inflation. The change of theological behavior makes an on-site oil recovery very difficult. The steam-driven ejector has potential advantages which are hardly seen in other conventional oil skimming devices to overcome these difficulties. Rapid heating accompanied by condensation of the steam can enhance the flow of the high viscosity spilled oil inside the suction pipe. Super sonic steam flow in the ejector may provide very strong mixing energy required for an emulsion breaking reaction when some chemical agents are employed. A small-size model of the steam-driven suction skimmer was designed and its basic suction recovery performance was experimentally tested. The tests included various aspects such as an oil recovery rate, an oil/water ratio, a steam consumption rate as well as sensitivity to wave. It is concluded that the steam-driven ejector system may be a good option for oil recovery or response.

Development of a handy oil-skimmer

Recently marine pollution by high-viscosity oil leaked from wrecked ships has been becoming a remarkable problem in the world. Japan government is renewing old oil recovery vessels with new concept. The oil recovery vessels are available on the open sea, but unworkable in a narrow space. We have developed a handy oil recovery system which is portable and used for supplementing the weak point of the oil recovery vessel. The system consists of a water jet oil-skimmer and a gravity oil/water separator. The oil skimmer has a high-pressure water jet pump inside the suction mouth and a long shaft which is used as a conduit of the recovered fluid as well as a spring-hanging device which enables an operator to easily manipulate it from the deck of the ship. After 3-year research and experiments, we have completed the system successfully. The system will be soon installed on our oil recovery vessels