Multiphase Flow And Formation Characteristics Of Cyclopentane Hydrate In Biaxial Reactor

With the development of social economy and the increasing demand for electricity,hydrate cold storage technology has become a very promising cold storage method because of its good cold storage performance,which is of great significance for regulating the balance between supply and demand,energy conservation and environmental protection.And it also has huge application value and market.Cyclopentane hydrate can be prepared at low temperature and atmospheric pressure without auxiliary gas,so it is a new type of ideal cold storage agent.However,it is difficult to carry out large-scale continuous production,so it cannot achieve industrial application.Researchers have conducted a large number of small-scale experimental studies on improving the rate of hydrate formation,but less research has been done on the promotion of hydrate production by large-scale reaction equipment.Based on this,the paper analyzes the difficulties in the industrial preparation of hydrate.Combined with the hydrate strengthening technology,the biaxial structure is innovatively applied to the industrial production of hydrate to solve the problem of low hydrate formation rate,adherent growth,and removal of hydrate heat.Based on Fluent,the multiphase flow and heat transfer in the biaxial reactor are simulated to understand its promoting effect on hydrate growth.At the same time,a pilot test-bed is set up to prepare cyclopentane hydrate,the optimal reaction conditions are sought,and compared with the simulation results,the improvement measures are put forward.The main research contents are as follows:（1）VOF model is used to simulate the mixing of two-phase flow in a biaxial reactor at different speeds and concentrations,and the distribution of internal flow field,velocity field,pressure field,and turbulent kinetic energy is analyzed.The mass transfer characteristics between immiscible liquids and the promoting effect of this structure on hydrate nucleation are investigated.The results show that with the increase of rotational speed,the turbulent kinetic energy increases,the dispersion of cyclopentane and water is more uniform,and it is easier to meet the nucleation requirements,but the total power consumption also increases,and the stirring power is directly proportional to the square of the rotation speed.When the volume ratio concentration of cyclopentane to water is 1:5 and1:7,the turbulent kinetic energy of the flow field increases,and the distribution effect of cyclopentane in the reaction chamber is good.（2）The Euler model is used to numerically analyze the mixing and flow characteristics of the three-phase flow in the biaxial reactor with different particle sizes and different rotational speeds,and the effects of flow collision and agglomeration on the flow field are considered.The results show that with the increase of particle size,the number of small-scale vortices in the flow field increases,which improves the liquid-liquid and solid-liquid mass transfer characteristics.With the increase of stirring speed,the turbulent kinetic energy and turbulent dissipation rate in the flow field both increase,and the hydrate particles are more uniformly distributed in the liquid phase.（3）The heat transfer characteristics of the biaxial reactor at different reaction temperatures and rotational speeds are simulated,and it is found that the heat transfer effect of the biaxial reactor is improved with the increase of rotational speed and the decrease of reaction temperature.With the rotational speed increases,the disturbance of the system increases,which promotes the heat exchange of the fluid in the reaction chamber.The fitting formula for the relationship between the Nu number and the Re number is:Nu=2.8Re^0.3 ~4.The fluid temperature near the heat exchange surface decreases first,and the lower the reaction temperature,the faster the heat transfer.So it is necessary to comprehensively consider the overall heat transfer effect and hydrate adherent growth to determine the reaction temperature.（4）Build a pilot-scale experimental bench and prepare cyclopentane hydrate,observe the morphological characteristics of the hydrate,and obtain the temperature change curve,total hydrate mass and calculated hydrate number during the hydrate preparation process,and compare the experimental results with the simulation.Considering the influence of various factors,the two conditions of 276.65 K,220 rpm,CP:H₂O=1:5 and 276.65 K,220 rpm,CP:H₂O=1:7 are the most suitable for industrial production of cyclopentane hydrate in a biaxial reactor.The biaxial reactor can effectively reduce the energy consumption of the reaction,and the reaction rate is fast,so it is very suitable as a hydrate preparation device in an industrial cold storage system.