Research On Small LNG Cold Energy Recovery System And Design Performance Analysis Of Gasifier

As we all know,China's economic development is getting faster and faster,but at the same time of rapid economic development,environmental problems and energy waste will follow.As a green energy source,natural gas is one of the main forms of energy used in China.Liquefied Natural Gas(LNG)can release a large amount of cold during gasification.If it can be used in actual projects,this part of the cooling capacity can be carried out.Effective use can fully respond to China's national policy of energy conservation and emission reduction,and the construction of LNG gasification station with cold energy utilization has important engineering practical significance.During the gasification process of LNG,the heat transfer performance of the gasifier directly determines the effect of the cold energy recovery system of the gasification station,that is,the efficiency of cold energy recovery and utilization.Therefore,it is of great practical significance to study the heat transfer performance of the gasifier.By reading the relevant literature and combining the theoretical basis of thermodynamics and numerical simulation analysis,the cold energy recovery method of small LNG gasification station is studied,and the way of cold energy utilization is obtained.At the same time,the gasification which plays an important role in the cold energy recovery process is obtained.The structural design and flow field numerical simulation analysis are carried out to obtain the flow field change in gasification and its own heat exchange effect.Firstly,based on the thermodynamics,the enthalpy analysis method is used to analyze the change of the cold enthalpy of the LNG gasification process,the low temperature enthalpy and pressure enthalpy contained in the cold enthalpy,and the environmental temperature which mainly affects the LNG cooling enthalpy.System pressure factors are analyzed to provide a theoretical basis for efficient recovery of LNG cold energy.At the same time,the LNG gasification cooling capacity per unit volume was calculated,and the cooling capacity of about 417 MJ was obtained,which indicates that the cooling capacity of the small LNG gasification station is recycled,and the design significance of the gasifier is also indicated.Secondly,based on an example of a gasification station,the cold energy generated in the station is used for the cold storage and the air conditioning system in the station to realize the cascade utilization of energy.Through the RESEARCH ON the refrigerant,the liquid carbon dioxide was selected as the refrigerant of the primary gasifier in this design,and the ethylene glycol solution with a volume fraction of 50% was used as the refrigerant of the secondary gasifier.Calculate the cooling capacity of the cold storage system of the gasification station according to the relevant formula,and use the EnergyPlus software to carry out the annual dynamic RESEARCH ON the cooling load of the air conditioning system in the station,and obtain the maximum cooling capacity in the whole year.By comparing and analyzing the cooling capacity,it is proved that the cooling capacity in the station can meet the cooling demand of production and life in the station,which also provides a theoretical basis for gasifier design.The gasifier is an important working component in the gasification process of a small LNG gasification station.In order to improve the effective utilization of the cold energy recovery system,the gasifier is structurally designed according to the design principle of the gasifier.By calculating the parameters of the heat exchanger coefficient,wall temperature and flow resistance of the gasifier,the structure of the gasifier is designed to ensure that the wall of the gasifier does not freeze.Finally,the fluid numerical simulation software is applied to simulate the operating conditions of the gasifier,so as to verify the feasibility of the gasifier design from the numerical simulation.Through the modeling and parameter setting,the flow field distribution and temperature field distribution are obtained.It is found that the fluid in the gasifier forms a vortex in the vicinity of the baffle plate,and the flow velocity changes greatly.Therefore,it is necessary to pay attention to increase the baffle in the design process.Thickness to enhance its operational stability.As the inlet flow rate of the shell-side fluid is larger,the eddy current area generated by the fluid in the baffle region is smaller,the flow velocity in the peripheral region of the vortex is large,and the velocity gradient is very obvious.The overall trend of convective heat transfer coefficient increases with the increase of flow velocity,which is beneficial to the heat exchange process,but its value decreases when flowing through the baffle.Therefore,when designing the gasifier,it is necessary to pay attention to the situation near the baffle plate,and set the flow rate reasonably,and select the appropriate heat transfer enhancement measures to improve the heat exchange efficiency of the gasifier.