Analysis For Optimization And Retrofit Of Low Temperature Heat System And Steam System In The Refinery

Low temperature system and Steam system can provide heat, steam, power and other energies for the Refinery and chemical, they are an important part of energy system in process industry. At the same time, they also consume a lot of energy source, produce large amounts of pollutants. So it’s necessary to optimize low temperature system and steam power system, it not only can achieve the purpose of saving energy and reducing consumption, but also achieve good environmental and social benefits. The main research content of the paper:Through an investigation of the current low temperature heat system to the enterprise, the lack of heat in spring, autumn and winter comes to light. Some available waste heat resources are considered, taking some optimization measures, a total of579.2×104kcal/h heat can be obtained from catalytic reforming, sour water stripper, isomerization dewaxing, TMP and other devices, the1.0MPa steam for heating can be reduced significantly, avoiding the low use of high-energy steam,the purpose of saving energy and reducing consumption is achieved.According to the low temperature waste heat resources, it can be upgraded by heat pump technology. According to the working principle and characteristics of the various types of heat pumps, the first type LiBr solution heat pump is used; The process heat load and economic operation of units are considered, the power for heat pump is19000kW; According to the principles of the heating cycle and working fluid physical properties of the mathematical model, reasonably choosing the design parameters, completing the thermodynamic calculation of the heat pump unit, achieving each state point parameters and cycle working fluid flow. The thermal load of the unit can be calculated, the heat is balanced, and the value of COP is1.72. Heat transfer coefficient and heat transfer area formula are used, the heat transfer area of the heat exchanger is figured out. Through the work, some preparations are completed for the preliminary design of the heat pump.Through an investigation of the current steam power system to the Refinery, some high level steams are used as waste and the phenomena of de-superheating and decompression are serious. The utilization of back pressure steam turbine and other power recovery devices are proposed as optimizations, the purpose to reduce the steam consumption of the summer and winter is achieved, then energy cascade utilization and productive energy are realized.According to the economic and technical feasibility analysis for the above-mentioned energy-saving projects, the total investment is RMB78.6327millions, Annual economic benefits is RMB40millions, the payback period for the project is1.966years. Therefore, the optimum reform schemes which is presented in the paper is feasible in technology, through the implementation of the project can improve the energy efficiency for Refinery, the economic benefit is obvious.