Storage and Transportation Technology: [Weekly Topic] 11-1-19 Issues with the Unloading of Large Oil Tankers
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This post was last edited by flute6 on 2011-6-2 at 22:33. Hello everyone, I work in oil depot design. Oil depots involve oil unloading at docks, so we need to understand the structure of the cargo holds in oil tankers. First of all, I would like to ask everyone: 1. What is the structure of the oil sump? Is it directly connected to the bottom of the cargo hold, and is there always an oil collection pit at the bottom of the cargo hold? 2. What is the purpose of the oil-water tank, and is it connected to the fuel tanks? 3. Are all the fuel tanks connected to each other? 4. How is the inlet of the oil unloading pump connected to the fuel tank? 5. What type of pumps are the oil unloading pump and the bilge pump? :(There are quite a few questions; I hope everyone can help me out.)
I also want to learn*learn* those topics mentioned by the original poster. I would appreciate your advice
Reply 1# kai*n1200 5. What types of pumps are the oil unloading pump and the bilge pump? Answer: Generally, a positive displacement pump is chosen.
1.1 Fuel oil pumps: Large oil tankers generally use vertical centrifugal pumps, which are powered by steam turbines. These pumps have a simple structure and high flow rates, but they do not possess self-priming capability. The types of cargo pumps for oil tankers and their applicable applications are shown in the table below. Table 1: Types of cargo oil pumps for oil tankers and their applicable applications 1.2 Bilge pumps 1.2.1 Cargo oil bilge piping The types of bilge systems and their applicable applications are shown in the table below. Table-2 Types of Bilge Suction Systems and Their Applications 1.2.2 Bilge Suction Branches For large and medium-sized oil tankers, since automatic bilge suction systems are installed, and to simplify the cargo oil system, a dedicated bilge suction system is generally not provided; instead, the cargo oil intake pipe is used as the main bilge suction pipe. Each fuel tank is equipped with smaller-diameter scavenge branch pipes and inlets connected to the main fuel pipe. During oil unloading, when the oil level in the tank drops to near the main suction port, the main suction valve is closed and the bilge suction valve is opened; simultaneously, a bilge pump is used to remove the oil from the tank. 1.2.3 Independent bilge piping: The bilge main pipe and the fuel oil main pipe are laid in parallel; each fuel oil tank is connected to a bilge branch pipe as well as the bilge main pipe, which in turn is connected to the bilge pump. 1.2.4 Bilge suction inlet The bilge suction inlet shall be located at the main fuel suction inlet, as close as possible to the bottom of the fuel tank. If the fuel tank is equipped with a bilge pumping well, the bilge suction inlet should be located within that well. 1.2.5 For bilge pumps, steam reciprocating pumps or electric screw pumps with good self-priming capabilities should be used, and their pressure should be the same as that of the cargo oil pump discharge pressure. Typically, large oil tankers are equipped with cargo oil tanks, bilge tanks, oil suction wells, and cargo oil pump rooms. Fuel tank: Used for storing oil; it consists of multiple tanks that can hold different types of oil. Slop tank: Deposits and residues attached to the inner walls, bottom, and internal structures of the cargo hold are first cleaned into the bottom of the hold, where they are then sucked up using a bilge pumping system and discharged into the slop tank. The actual volume of the fuel tanks (including the bilge tanks) should be accurately measured by a unit with legal metrology qualifications. Oil suction wells: Each fuel tank is equipped with oil suction wells at its bottom to draw in water and oil. Fuel oil pump compartment: Generally located on the side of the bilge tank, at the bottom layer of the tanker, with the floor of the fuel oil pump compartment being slightly lower than that of the bilge tank and the fuel oil tank.
The content above is information I gathered on my own
The reply on the 4th floor was quite comprehensive and professional. This can answer the original poster’s question.
1. The main bottom pipe branches off to each fuel tank, and these branches are controlled by valves. The oil collection troughs at the bottom of the fuel tanks vary depending on the ship’s design; some ships have 2 such troughs. 2. The bilge tanks are used to store the ship’s own sewage or water used for cleaning the tanks, and they can be connected to the fuel tanks through pipelines. 3. Can all the fuel tanks be connected together via the bottom pipes? 4. Is the inlet of the oil unloading pump connected to the various cargo tanks through the ship’s bottom pipes? 5. The pump selection is determined by the viscosity of the oil being carried by the ship; screw pumps are generally used for heavy oil, while centrifugal pumps are used for light oil.
Reply to 7# Dokubu Kyushu, take a look
I don’t think that’s the case. Pumps are purchased on the deck; each tank is equipped with its own pump. On chemical tankers, pumps with hydraulic systems are mostly used, with these pumps leading directly to the sump at the bottom of the fuel tanks, allowing for direct cleaning of those tanks. All the fuel tanks are connected to each other through upper or lower pipelines
Hehe. Good, the key is to have clear indications of where the pipelines enter and exit; otherwise it’s easy to get misled