TS-67
Actual Capability of Shipboard Fuel Oil Pre-treatment Systems
Susumu AKENO*, Kobune GOTO*, Fuyuki HIRATA*, Yoshimitsu ICHIHARA*
Haruo MIYANO**, Yukiko SHIMA**, Hideo WATANUMA* and Minoru TAJIMA*
ABSTRACT
In recent years there is a steadily growing number of abnormalities which caused by the poor quality of marine fuel oils. In particular, abnormal wears of piston rings and cylinder liners are creating serious problems. Therefore, a role of fuel oil pre-treatment systems is becoming increasingly important.
The capability of pre-treatment system is governed by fuel oil properties, system arrangement, individual abilities, operating conditions and operating procedures. With a view of grasping actual capability of pre-treatment system, fuel oils were collected from vessels and the investigation was conducted.
The followings are the results.
Water, FCC fines and TSE are removed by pre-treatment system relatively well. Average removal ratio of FCC fines at purifier was 43.2%. Average flow ratio was 50.1%. It's considered that the flow ratios through purifiers are the main attributing factors of the removal capabilities. And capability of treatment device is given influence by methods of operation.
Key Words: Fuel Oil Pre-treatment Systems, Properties of Fuel Oil, Capability of Pre-treatment System
1. INTRODUCTION
With recent degradation of fuel oil quality, the number of marine diesel engine failures is increasing. In particular, occurrence of abnormal wear of cylinder liners and piston rings is affected by design, the maintenance and operation of engine in addition to combustibility of fuel oil and impurities in fuel oil. Therefore, it is quite difficult to identify specific factors responsible for the abnormalities in cylinder liners and piston rings.
Most reports point out that these abnormalities are caused by hard catalysts (such as FCC fines). In this respect shipboard fuel oil pre-treatment system has important role in processing of degraded fuel oil.
The separation efficiency of pre-treatment system is governed by the properties of fuel oil, the system arrangement, capability of each device as well as maintenance and operating conditions of the system.
Therefore, investigations were made to ascertain whether or not existing shipboard pre-treatment devices are capable of sufficiently responding to fuel oil as stated in the specifications of manufacturers and capable of responding to heavy oils which are expected to be constantly degraded and deteriorated in the future.
Although the studies are still in progress, the summarized results are described here.
2. PRE-TREATMENT SYSTEMS OF SHIPS SELECTED FOR INVESTIGATION
Ten ships have been selected and named "Vessel A" to " Vessel J" respectively. Table 1 shows comparison of pre-treatment systems on these vessels. During the investigation, abnormal wear of the cylinder liner caused by fuel oil was reported on Vessel "C".
3. SAMPLING SPOTS AND FUEL OIL ANALYSIS ITEMS
Figure 1 shows shipboard fuel oil treatment process and sampling spots. Line between the sampling spot N0.1 to No.5 is called fuel supply line; No.6 to No.8 is called fuel circulation line.
However, primary filter, pumps, and heater are omitted on Figure 1. Sampling was carried out at the time when the same fuel oil had been filled on the fuel supply line and the fuel circulation line. The following items in fuel oil were analyzed: density, kinematic viscosity, water, sodium, asphaltene, dry sludge, aluminum silicon and vanadium. Sulfur and micro carbon residue were omitted because these properties can not be reduced through the shipboard processing system.
