Abstract
Liquefied petroleum gas is used as an energy source in many areas of the world. It is among the most important fuels used worldwide. Transport of this type of petroleum products between ports is carried out on a large scale. These cargoes are transported in ship types called LPG tankers. Transported LPG gas formation must be carried in liquid form. Particularly in these liquid formations, the transportation of the LPG vessels is divided into different types and it is carried under the name of Fully Refrigerated, which authors call full cooling. LPG is a highly sensitive, flammable, and explosive property, but it is also necessary to know special precautions regarding its transportation. Load operations are difficult processes for LPG tankers. The most complex of these processes is the change of load called grade change. The chapter guides LPG vessels' workers and students in the education process.
TopIntroduction
Sea transportation logistics is one of the most important building blocks of the logistics sector with the globalization of the economy. In order to better understand and understand this maritime transport area, it is first necessary to examine how sea transport is carried out and what processes are going on. Considering the transportation economy, sea transportation is one of the most used methods with the least amount of transportation. It also provides a safe transportation of cargo. In sea transportation, many types of ships travel in the seas and realize the largest part of transportation. Liquefied petroleum gas and liquefied natural gas, which is the most complex and difficult type of transportation models, should be examined in detail.
According to the data of the Chamber of Shipping 2017 sector report, the transportation of the LPG segment has led to a strong demand increase since 2012, according to Clarkson Research. This increase significantly increased both earnings and orders. In early 2017, the LPG fleet consisted of 30.3 mcbm (22.4 mDWT) and 1,382 vessels. This tonnage represents an increase of 17.2% over the previous year in terms of capacity. This is a function of high returns observed in 2014. Although the weak freight rates observed in 2016 (0.7 million DWT 12 vessels) restrict the order activity, the LPG order book at the beginning of 2017 still includes 115 units with a volume of 3.7 million DWT. The world tanker fleet, together with gas tankers, crude oil tankers, chemical tankers and product tankers, has 12262 units. 1770 of this number is indicated as gas tankers. As stated in the numbers, the gas tank market is small in volume but small in volume.
There are also differences in the variety of gas tankers. 5 different types of liquefied petroleum gas vessels traveling in global sea trade are identified. They have differences, such as full-pressure gas vessels, semi-pressurized gas vessels, ethylene vessels, fully-refrigerated gas vessels, and liquefied natural gas ships. Full-pressure vessels, semi-pressure vessels and ethylene tankers can be specified as small-sized liquefied gas carriers. Fully refrigerated gas tankers and liquefied natural gas carriers come in large size and tonnage. The most prominent feature of the first three types of vessels is that they perform close coastal voyages and carry out partial transportation in low tonnage. Other liquefied petroleum gas and those carrying liquefied natural gas are transported with large load capacities to long distances due to their large size. Another difference is the different operations in the cargo operations. With different types of equipment, transportation of different species is also easily provided. The major reasons for the separation of these ships are the differences in the cargoes carried and the different locations of the voyages.
In this section, the main aim is to give information about the difference in the operations of LPG (Liquid Petroluem Gas) tankers. Ship operators show the high freight rates in LPG tankers as an interesting area. It is very important to know the operational processes in gas tankers. The most important reason for this is the transport of explosive materials, which cause serious loss of life and property in accidents caused by operational errors in gas tankers. Therefore, information is given about careful review of the operational process and what needs to be done at the stage. In addition, the largest and most time-consuming load exchange operations on gas tankers have been mentioned. Having different operations in different gas tankers brings to the fore the need for well-trained personnel.
In this process, the following stages are mentioned; 1-Gas tanker ship types 2-Cargo tanks design Differences 3-Lpg tanks 4-Used load pumps 5-Relification cycle 6-Preparing for loading stage 7-Drying 8- Inert operation 9-Gassing Up operation 10-Cool Down operation 11-Discharge operation 12-Grade Change operation
It is the lack of knowledgeable and experienced staff who can do all the operations mentioned above briefly. In the processes mentioned in this study, information is given to guide the education sector and the personnel working on such ships.
A liquefied gas is liquid at ambient temperature and under atmospheric pressure. Most of the liquefied gases are hydrocarbons and are the basic properties of hydrocarbons. The world's primary energy source is LPG flammability and makes them naturally dangerous. Since these gases are used in large quantities, it is imperative that they be controlled and safety precautions taken.
Key Terms in this Chapter
Relification: The gas state of the cargo is brought into liquid state with the compressor and other auxiliary equipment.
Bulkhead Valve: Due to the large size of the vessel tanks, it is the intermediate section placed on the vessel tank to reduce the free sloshing effect.
Ethanol Injection: It is the addition of ethanol to the circuit to prevent freezing of the cargo circuits.
Puddle Heating: LPG Cargo is the rapid heating of the load with seawater and compressors.
Sloshing: It is called the wave movement of the load in the ship tanks with the effect of free surface. This causes a negative condition to occur. This situaiton will damage to ships tanks.
Gassing Up: It is the raising of the LPG load from the tank base by giving heat to the top of the tank.
Cool Down: It is the reduction of LPG load to the tank base by cooling with compressor.