Liquefied petroleum gas (LPG) can be at room temperature by pressure or frozen under atmospheric pressure and liquefaction. According to the method of liquefied LPG ship is divided into pressure type, half frozen pressure type and frozen type 3 kinds. Pressure type LPG ship is several pressure tank is installed in the boat, the maintenance of liquefied petroleum gas at high pressure liquid. This simple form structure, 30 s have been, since capacity under 6000 m 3 boat is still widely used.
Photo of our LPG Vessel:
LPG (Liquefied petroleum gas, LPG) ship (LPG ship) main transport propane and butane as the main components of petroleum hydrocarbons or both mixture, including propylene and butylene, there are some chemical products, ethylene is also included in the scope of its transportation in recent years. According to the different liquefaction conditions carrying all kinds of gas and divided into total pressure type (loading capacity is small), cold half pressure type (larger loading capacity) and whole cooled (load). Liquefied petroleum gas ships because of its special purpose and produce the special requirements of the various aspects, its technical difficulty is big, on behalf of the shipbuilding technology in today's world, with tonnage ship price of conventional carrier 2 ~ 3 times, is a kind of high technology, high value-added ships.
Liquefied petroleum gas (LPG) can be at room temperature by pressure or frozen under atmospheric pressure and liquefaction. According to the method of liquefied LPG ship is divided into pressure type, half frozen pressure type and frozen type 3 kinds. Pressure type LPG ship is several pressure tank is installed in the boat, the maintenance of liquefied petroleum gas at high pressure liquid. This simple form structure, 30 s have been, since capacity under 6000 m 3 boat is still widely used. After frozen liquefied petroleum gas pressurized liquefied than after small volume of 2% ~ 6%, so the early '60 s had half frozen pressure vessel, then develop a frozen type ship (of temperature in the cargo tank is about - 50 ℃, the pressure of 0.28 bar).Liquid tank with the ship to the double hull structure, low temperature resistant alloy steel and lined with insulation, most capacity in more than 10000 cubic meters. The ship is equipped with gas liquefaction plant, evaporation can be out of liquefied petroleum gas (LPG) into cargo tank of liquefied.
LPG ship under the mode of transportation of goods into the whole pressure type, cold half pressure type (cold) and cooled all three kinds of ship type.
(1) the full pressure type
Also known as room temperature pressure type, is to put the goods at room temperature under the condition of pressure exceeds evaporation pressure stress, make the goods into a liquid state. A few gas such as ethane, ethylene and methane above the critical temperature and pressure liquefied. Total pressure vessel cabins do not need to set the heat insulation and cooling equipment. Usually the highest design temperature 45 ℃, the highest design pressure between 1.75 2.0 MPa. Jiangnan shipyard to build China's first 3000 m3lpg ship, its design working pressure is 1.75 MPa, usually all pressure type LPG ship are below 5000 m3 tank capacity.
(2) half cold pressure type transport
Also called low temperature pressure type, the first type of the ship was built in 1959, volume of 2100 m3.In Europe, the early 60 s mature because of low temperature technology research, built a large number of. At present, a lot of fleet to Germany to see. This type of ship early cooling temperature is about 5 ℃, pressure is 0.8 MPa, carrying liquefied gas nearly all over pressure type LPG ship, has little to build. Recently, there are two types of this kind of boat, more cooling temperature was minus 48 ℃, the minority carrier of ethylene to - 104 ℃, pressure is 0.5 to 0.8 MPa, jiangnan shipyard built 4200 m3 and 16500 m3lpg ship respectively belong to the two kinds of ship type. Usually the ship tank capacity most no more than 25000 m3, newly developed 30000 m3lpg ship is the most of the ship.
(3) full cooled
Also known as low temperature atmospheric pressure type, liquid gas storage in the liquid chamber pressure, boiling state under normal pressure. Tank design pressure is 0.025 MPa commonly, a single tank volume is seldom restricted, to build large ships, the capacity is 50000-100000 m3 mostly.
(1) the independent model of tank type as a whole
(2) the internal storage tank insulation type
(3) the independent type of tank. The tank can be divided into three type A, B, C, they are not form part of the hull, A seft sustained.
Type A separate tank: this type of tank is composed of flat structure, more tank maximum allowable design pressure is not greater than 0.07 MPa, in A large cold ship using this type is more, all working temperature not less than 55 ℃.
Type B independent module: to accurately the structure stress analysis and model test, including the finite element and shell theory, some cases can be appropriately used frame analysis method. Buckling, fatigue life and plastic deformation are considered. Tank type prisms and rotary spherical, pressure is less than 0.07 MPa. This pattern is more LNG Marine.
Type C pod: C tank has a single pot, three ears and 3 leaf type, according to the rule of pressure vessel design. Design pressure often take 1.8 MPa, less than 2 MPa. Built in our country at present the whole pressure and cold half pressure type LPG ship all belong to this category. Do not need to set the ship shielding, technical state of maturity.