Chemical Engineering & Technology, Vol.32, No.5, 805-819, 2009
Experimental and Theoretical Investigation of Double Gas Hydrate Formation in the Presence or Absence of Kinetic Inhibitors in a Flow Mini-Loop Apparatus
Double gas hydrate formation in the presence or absence of kinetic inhibitors in a flow mini-loop apparatus was investigated. For the prediction of the gas consumption rate during hydrate formation in this system, the rate equation based on the Kashchiev and Firoozabadi model for simple gas hydrate formation in a batch system was developed for double gas hydrate formation in a flow mini-loop apparatus. To complete the theoretical evaluation of gas hydrate formation through the mini-loop apparatus in the presence or absence of kinetic hydrate inhibitors (KHI), a laboratory flow mini-loop apparatus was set up to measure the induction time for hydrate formation and the uptake rate when a gaseous mixture (Such as 75 % C1/25 % C3, 25 % C1/75 % C3, 75 % C1/25 % i-C4, and 25% C1/75% i-C4) is contacted with water containing or not containing dissolved inhibitor under suitable temperature and pressure conditions. In each experiment, a water blend saturated with gas mixture was circulated up to the required pressure. The pressure was maintained at a constant value during the experimental runs by means of a required gas mixture make-up. The effect of pressure on gas consumption during hydrate formation was investigated in the presence or absence of polyvinylpyrrolidone (PVP) and L-tyrosine as kinetic inhibitors at various concentrations. A good agreement was found between the predicted and experimental data in the presence or absence of KHI. The total average absolute deviation percents between the experimental and predicted values of gas consumption were found to be 16.4 and 17.5 % for the double gas hydrate formation in the presence or absence of the kinetic inhibitors, respectively.