Lng Ship Cargo Tank Insulation And Heat Transfer Calculations

As is now well known, liquefied natural gas is more and more widely used at present as a kind of high calorific value and clean energy source, In recent years, people begin to attach importance to the exploitation and using of the natural gas, because of the impact of petroleum crisis and increasingly serious environment issue caused by coal and petroleum. Some developed countries have regarded the natural gas as a sort of importantly strategic substance. With the rapid development of national economy in China, the demand of natural gas is increasing steadily. We must import a great deal of liquefied natural gas for lack of existing output in domestic market. The liquefied natural gas carrier plays very important role in world natural market because it possesses the merit of very high economy and agility property in the process of reserving and transportation in liquid state. The technique of design, build and operation of the liquefied natural gas carrier are very mature abroad. However, this aspect in our country is blank. So, we must pay more attention to develop the technique of liquefied natural gas carrier. Its key technique mostly focus on the structure of cargo tank and heat insulation property at present.Developing the large ships with high-tech and high-added-value has become the focus and hot-spot of the world ship market competition. The Ministry of Communication of the People's Republic of China has ranked the projecfdesigning and making engineering of ships with high technique and performance" as one of the twelve large engineering projects with high technique, and ranked the LNG carrier as one of the new type. As the LNG project of Guangdong is put into practice, Hudong China shipyard begins to build LNG carrier with the help of GTT Company in France. It is very clear that our country will have LNG carrier and own LNG fleet in forthcoming 3-5 years. This will end the history of having no LNG carriers in China, the development foreground is very prospective.It is very pressing and significant for the safe transportation of the LNG carrier that how to improve technical level of LNG carrier seamen and enhance train for them in the face of forthcoming massive marine transportation. However, relevant applied software and simulation system are not tapped at present in China. Basedon the consideration, the paper is dealing with partial basic study on the heat insulation technique and heat-transfer calculation.Firstly, the paper introduces the property of the LNG and the application, technical character and study emphases of the LNG carrier. Some detailed description and contrast are made about two kinds of typical LNG carrier's cargo tanks in the following aspects: structure, material, jointing character and heat insulation property and so on. Besides, A brief introduction is made about two kinds of new type heat insulation techniques. Secondly, some detailed qualitative analysis is provided on the heat-transfer of cargo tank. I use basic theory of heat-transfer to give a detailed heat-transfer calculation of MOSS type cargo tank and obtain calculation values of some parameters such as heat load, boil-off rate, thickness of heat insulation lay and so on. Thirdly, I give a theoretic study on the temperature and heat flow density distributing of the support-skirt about MOSS type cargo tank under the condition of full-load and put forward corresponding measure to reduce heat quantity from outside according to the calculation result. Fourthly, I make use of calculation method and combine the analysis of last chapter to set up mathematic models about temperature and pressure changes in the process of precooling according to detailed gas condition in cargo tank after unloading while analyzing precooling process and find the relation between temperature, pressure in cargo tank and time in the process of empty load voyage, I analyze the calculation result and set forth leading factors causing error. Finally, I bring forward LNG carrier precooling scheme according to calculation results.This paper prov...