Peak Adjustment Technology Of LNG With Gas Hydrates As The Medium

As the Chinese economy keeps growing and requests further efforts to the environmental protection,demand for natural gas still has much room for high growth.And the diversified supply structure of natural gas,abundant storage and peak shaving facilities are able to ensure the balance of its supply and demand.However,the underground gas storage,liquefied natural gas?LNG?and other methods which are widely applied at present cannot fully meet the demand of peak shaving as limited by the geological structure and the high cost.Therefore,new and efficient peak shaving methods need to be further developed as alternatives.Natural gas hydrate?NGH?,a clathrate crystal formed by water and methane with high rate of gas storage and mild storage condition,has drawn extensive attention and study in gas storage industry.Therefore,this paper mainly carried out the preliminary conceptual design of LNG peaking shaving technology with hydrate as the medium.?1?In order to improve the low formation rate of hydrate in the process,an efficient hydrate promoter,Ag&-SO₃^-@PSNS,based on dynamic nano-spheres was synthesized in this Chapter by utilizing the functional groups in the surfactant with good effect on hydrate formation and the high thermal conductivity of metal particles.The experimental results of hydrate at constant volume show that the promoter is able to realize the rapid formation of hydrate in about 100min compared with pure water and SDS of traditional surfactant type,and solve the foaming problem in the decomposition of hydrate in surfactant.Meanwhile,an increase in the concentration of Ag particles on the promoter's surface and the particle size of the nano-spheres can help to improve the hydrate formation rate,thereby the hydrate induction period and the growing period would be completed within 60min under constant pressure.In the end,the comparison experiment of hydrate formation under high pressure?6MPa?and low pressure?5MPa?also shows that the promoter can complete hydrate formation within 130 minutes and achieve a 160-fold high gas storage ratio under low pressure,bringing out the good industrial value?2?Based on the promoting effect of Ag&-SO₃^-@PSNS promoter on hydrate formation,LNG peak shaving technology with hydrate as the medium was developed.With this technology,the cold energy released in the LNG gasification can be used to remove the heat generated in the hydrate formation and cool down the material.At the same time,on the premise of satisfying the gas users,the hydrate formed by extra methane gas and water after gasification should be stored under normal pressure and low temperature until the stored NGH is decomposed to supply the methane gas to users at the peak of gas consumption and also bridge the gap between supply and demand.In addition,the consumption of electric energy and cold energy and the range of peak shaving capacity are analyzed in this Chapter.?3?In view of the high energy consumption caused by the high pressure required for hydrate formation described in the second part,this part designed the low-pressure hydrate formation process on the premise of ensuring the hydrate formation rate.Compared with the process of high-pressure hydrate formation in the second part,the heat transfer process of high-pressure fresh gas sent to the reactor after compression is mainly adjusted in this part.According to the data,the power consumption of the hydrate formation process is decreased by 10%when the reaction pressure is reduced from 6MPa to 5MPa.