Study And Analysis On The Recovery Technique Of Lng Light Hydrocarbon

Environment and energy have become an increasingly important issue holding back sustainable development on China’s economy. Therefore, China starts to vigorously develop LNG(liquified natural gas) for optimization of its energy structure, improvement of residents’ living environment and increase of national economy income. LNG contains about 10% of C2+ light hydrocarbon which is the raw material including ethane, propane, butane is high-quality material for the production of ethylene for. Meanwhile, a large amount of cryogenic energy will be released during LNG’s gasification. It is estimated that per kilogram of LNG possesses 830KJ-850 KJ of cryogenic exergy. The efficient use of LNG cold energy recycling its own C2+ light hydrocarbon is not only conducive to the energy conservation, but also to the enormous economic benefit. The following aspects will be discussed in this paper.To begin with, this paper introduces principle and classification of recycling technology of LNG light hydrocarbon in details, summarizes the classic domestic and foreign recycling process of LNG light hydrocarbon makes specific account for process flow, process equipment and product properties of LNG light hydrocarbon in Shandong province. The issues existing in the process will be found and settled through comparison and analysis.What’s more, this paper elaborates briefly the characteristics of LNG cold energy and puts forward the evaluation methods applying to the recycling technology of LNG light hydrocarbon, that is adopting cryogenic analysis method evaluating the rate of exergy efficiency of cold energy and technical economic analysis method evaluating economic indicator of the recycling cryogenic exergy of LNG light hydrocarbon. This paper also gives boundary conditions for starting processing installations. Through above two analysis methods, the comprehensive evaluation has been conducted to the recycling process of LNG light hydrocarbon.Then, in view of the complexity of LNG gasification, LNG gas and liquid equilibrium model was established, BWRS state equation was used to establish a LNG physical parameters model and Visual Basic 6.0 was used to develop a LNG physical parameters calculation software. Verification of calculation software of this paper through examples meets the requirements for accuracy, which provides the tools for the development and application of recycling technology of LNG light hydrocarbon to facilitate the analysis for recycling process.Last but not least, in view of domestic and foreign recycling process of LNG light hydrocarbon, specific process research and theoretical analysis have been made. With the method of exergy analysis and economic evaluation, exergy evaluation index, economic evaluation and concentration index of the product can be calculated through the tool compiled by this paper. We have found issues of recycling process of LNG light hydrocarbon through comparison and analysis. With the principles of the cold cascade, this chapter develops a new recycling process of LNG light hydrocarbon, establishes the model of exergy analysis and economic evaluation and analyzes the product index and risk factors of cryogenic exergy utilization and ethane recovery rate. The efficiency of exergy system is 87.49%. Methane molar content in the product is 99.01%. The recycling rate of C2 + light hydrocarbon is 94.65%. Compared with other process, its profit value, product concentration, recycling rate, exergy consumption and risk factors are optimal.