Effect of Dissolution and Dispersion Conditions of VC-713 on the Hydrate Inhibition

Abstract

VC-713 is a kind of hydrate kinetics inhibitor, which is widely used because of its strong hydrate inhibition. In this paper, VC-713 was dissolved and dispersed into its solution to various degrees by stirring the solution at the speeds of 600 r·min−1 and 12000 r·min−1. Then, under the condition of normal pressure and temperature change (gradually decreasing from 278.15 K to 273.65 K), the hydrate inhibitory effect of dissolution and dispersion of VC-713 on THF hydrate formation was studied. The variation in the concentration of VC-713 was monitored during the experiments. In addition, the mesoscopic structure characteristics of aqueous solutions were observed, and experimental phenomena in the reactor were recorded along with real time. Then, the experimental data were comprehensively analyzed, and the underlying mechanism of inhibition was revealed. Results showed that VC-713 inhibits hydrate nucleation and growth by adsorbing and binding. When the addition amounts are the same, better dissolution and dispersion of VC-713 can inhibit the hydrate formation more effectively. This is due to more complex skeleton structures formed by the hydrated VC-713 molecule. When the amount of VC-713 is 0.5 wt.%, the induction time, the formation rate, and the degree of supercooling of hydrate formation were extended, mitigated, and increased by 10.30%, 21.43%, and 17.80%, respectively, and changed to values of 8.75%, 14.29%, and 22.50%, respectively, for 1.0 wt.% VC-713.

Fundamental Investigation of the Effects of Modified Starch, Carboxymethylcellulose Sodium, and Xanthan Gum on Hydrate Formation under Different Driving Forces

“…where ∆n is the gas consumption amount in moles; R is the universal gas constant, 8.31441 J/(mol•K); T is the gas temperature in K; V is the gas volume in m 3 ; P 1 and P 2 are the pressures in the reactor at the start and end times of hydrate formation, respectively, in Pa; and Z 1 and Z 2 are the gas compression factors under the P 1 and P 2 states, respectively [34,35]. The hydrate formation rate was characterized by the average consumption rate of CH 4 gas during the period between the start and end of hydrate formation, which is expressed as follows:…”

“…For mesostructures of MS aqueous solutions, sparsely distributed rod-like skeletons and spherical aggregates cause their hydrated molecule aggregates to have a smaller specific surface area than those of CMC and XG aqueous solutions. Due to the presence of more pores with larger diameters in MS-hydrated molecule aggregates, there was a smaller number of strongly and weakly bound water molecules adsorbed near the hydrophilic MS molecules and a relatively larger amount of free water molecules in the pore space [35]. Furthermore, the hydrophobic CH 4 molecules were possibly dispersed in free water after dissolving in the solution [35], which made a larger contact area between the gas molecules and free water molecules in the pore space and thus created the hydrate form more easily.…”

Experimental Investigation of the Weakening Effect of Corrosion Inhibitors on the Performance of Kinetic Hydrate Inhibitors

“…1,2 Hydrate can nucleate and form under conditions of low temperature and high pressure, 3 allowing its universal existence in the oil and gas transportation pipelines. 4,5 The continuous growth and agglomeration of hydrate particles will reduce the efficiency of transportation and even cause the entire pipeline blockage that severely threatens flow assurance. 6,7 So far, several methods have been proposed to treat the hydrate blockage issues in pipelines, including physical methods and chemical methods, while the latter have been regarded as the best preventive technique for hydrate treatment in pipelines.…”

“…8 Chemical methods mainly refer to the injection of chemical inhibitors, such as thermodynamic hydrate inhibitors (THIs) and low-dosage hydrate inhibitors (LDHIs). 4,9 Among these hydrate inhibitors, THIs are the kind of chemicals (e.g., methanol, mono ethylene glycol, and sodium chloride) that can shift the equilibrium conditions for hydrate formation to a higher equilibrium pressure or a lower equilibrium temperature. 10 However, due to the high required dosage and the environmentally unfriendly characteristics, THIs are actually not the perfect choice for hydrate inhibition.…”

Kinetic Hydrate Inhibition of Natural Gels in Complex Sediment Environments

“…It has been proved that hydrate formation can be effectively inhibited in the presence of hydrate inhibitors in working fluids, especially kinetic hydrate inhibitors characterized by high inhibition and low dosage [ 9 , 10 ]. However, most typical commercial kinetic hydrate inhibitors cannot be extensively applied because of their high toxicity, high costs, and low biodegradability [ 11 , 12 ]. Therefore, green, environment-friendly, and biodegradable natural gels have gradually become a hot spot of research [ 13 ].…”