Study On The Preparation Of Natural Gas Hydrate In Spiral Tube Reactor

The storage and transportation technology by Natural gas hydrate(NGH),which realizes natural gas storage and transportation in solid state,is proved to be very promising.Theoretically,1 m3 natural gas hydrate can accommodate 150?180 Nm3 natural gas and can be stored for a long time under pressure(1?2 MPa)and temperature(-10?-5?).Since its discovery,natural gas hydrate has attracted much attention from scholars,and a lot of research and theoretical calculations have been carried out.More research has focused on the formation mechanism and laboratory preparation of natural gas hydrate,and less research has been conducted on large-scale preparation,storage and transportation of natural gas hydrate.In this paper,a spiral tubular reactor is designed to study the preparation of natural gas(CH4)hydrate.The experimental raw materials are landfill gas and coal-bed gas.This article explores the process conditions of natural gas hydrate formation and obtains the natural gas hydrate formation rules.Aiming at the preparation of landfill gas hydrate,explores the effects of temperature,pressure,residence time,and intake air flow rate on hydrate formation.In the initial temperature range of 3.0?6.5?,the lower the temperature is,the shorter the induction period of hydrate formation,and the higher the gas reserves of the generated hydrate would be.In the pressure range of 5.0?8.0 MPa,the higher the pressure is,the shorter the induction period of hydrate formation is.High pressure increases the driving force of hydrate formation,promotes the formation of hydrate nuclei and increases the gas reserves of hydrate.Residence time has a greater impact on the gas reserves of the hydrate.The gas reserves of the hydrate generated by the residence time of 50 and 70 minutes are relatively high and the particle size is relatively complete.The longer the residence time is,the lower the gas reserve of hydrate and the worse the particle morphology would be.In the gas flow range of 40?60 m3·h-1,the influence of gas flow on the induction period of hydrate formation is not obvious,and the induction time is 6 minutes,when the intake flow is 40 m3·h-1,The highest gas storage capacity of landfill gas hydrate is 45.2 V·V-1.Aiming at the preparation of coalbed methane hydrate,explores the influence of intake mode,pressure,residence time and additive concentration on the formation of hydrate.Pressure ranges from 3.0?8.5 MPa,with the increase of pressure,the gas storage capacity of the hydrate increases.Under the condition of 8.5 MPa,the gas storage capacity reaches 121.5 V·V-1,and the hydrate particles are relatively complete.The residence time ranges from 30?90 minutes,When the residence time is 90 minutes,generates dry hydrate,and hydrate particles are thicker,the fluidity is poor,and the gas reserves reach 131.1 V·V-1.The concentration of SDS ranges from 0?500 ppm,the optimum concentration of promoting SDS is 300 ppm.The gas reserve of generated hydrate reaches 107.2 V·V-1.SDS significantly decreases the induction time and improves the gas storage capacity of hydrate,while pure water system does not generate hydrate.Intermittent gas intake is more conducive to the formation of CBM hydrate than continuous gas intake,which has decrease induction time,higher average reaction rate and higher gas storage capacity.