Abstract
Hydrate-based gas separation is a potential technology for CO2 recovery and storage, and its products can be used for fire prevention and control in mines. Promoters are often employed to accelerate or moderate hydrate formation. In this study, experiments were performed to examine the effects of different concentrations of the thermodynamic promoter tetrahydrofuran (THF) and kinetic promoter sodium dodecyl sulphate (SDS) on CO2 hydrate formation under stirring. The results showed that THF significantly shortens the induction time of CO2 hydrates; however, because THF occupies a large cavity in the hydrate structure, it also reduces the gas absorption and hydrate formation rate. SDS has no obvious effect on the induction time of hydrates, but it can increase the gas storage density and hydrate formation rate. Using THF and SDS together consumed more CO2 than using THF alone or pure water. The peak gas consumption rate was 2.3 times that of the THF system. The hydrate formation efficiency was improved by including both THF and SDS, which maximized both the hydrate formation rate and total gas uptake.
Highlights
The development of the global economy and rapid growth of fossil fuel consumption has sharply increased the CO2 content in the atmosphere, which has aggravated the greenhouse effect and seriously affected Earth’s environment (Kasman and Duman, 2015)
To explore the relationship between the promoter and CO2 hydrate formation under stirring and determine the formation mechanism of CO2 hydrates, this study examined the effects of THF and THF/sodium dodecyl sulphate (SDS) on the formation kinetics of CO2 hydrates
In the pure water system, the pressure and temperature in the reactor dropped with the temperature of the water bath; this period was defined as the induction time Tind
Summary
The development of the global economy and rapid growth of fossil fuel consumption has sharply increased the CO2 content in the atmosphere, which has aggravated the greenhouse effect and seriously affected Earth’s environment (Kasman and Duman, 2015). CO2 hydrates have shown potential as a fire-extinguishing material (Hatakeyama and Aida 2008) owing to their CO2 gas storage capacity and cold storage capacity. Due to the existence of CH4 in coal mine, once a fire occurs, it is easy to cause gas explosion. CO2 hydrate releases a large amount of CO2 gas in the process of extinguishing the fire, which can play the role of flame retardant and explosion suppression, CO2 hydrates have broad application prospects (Huang et al, 2014) to be used for fire control in mines. CO2 hydrate technology has many advantages, such as gas storage capacity and a hydrate formation pressure and temperature that are relatively easy to achieve, the formation rate and gas storage capacity need to be improved
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