Flow Mini-loop Apparatus Research Articles

Performance Improvement of Various Kinetic Hydrate Inhibitors Using 2-Butoxyethanol for Simple Gas Hydrate Formation in a Flow Mini-Loop Apparatus

The effect of 2-butoxyethanol as an additive on simple gas hydrate formation in the presence of kinetic hydrate inhibitors such as modified starch, polyvinylcaprolactam, and Gaffix VC-713 under various conditions in a flow mini-loop apparatus has been studied. A laboratory flow mini-loop apparatus has been designed and manufactured to measure the induction time of simple gas hydrate formation. Hydrate formers (such as C1, C2, C3, i-C4, and CO2) are contacted with water containing dissolved inhibitor in the presence of 2-butoxyethanol as an additive at desired temperature and pressure. The effect of 2-butoxyethanol on the induction time during gas hydrate formation was investigated in the presence and absence of modified starch, polyvinylcaprolactam, and Gaffix VC-713 as kinetic inhibitors. Results show that the induction time is prolonged in the presence of Gaffix VC-713 compared to polyvinylcaprolactam and modified starch as inhibitors. Moreover, the induction time in the presence of 2-butoxyethanol is greater than in the absence of this additive for simple gas hydrate formation. As a result, the performance of kinetic hydrate inhibitors was enhanced in the presence of 2-butoxyethanol for natural gas components during gas hydrate formation.

Prediction of induction time for methane hydrate formation in the presence or absence of THF in flow loop system by Natarajan model

The induction time is a time interval to detect the initial hydrate formation, which is counted from the moment when the stirrer is turned on until the first detection of hydrate formation. The main objective of the present work is to predict and measure the induction time of methane hydrate formation in the presence or absence of tetrahydrofuran (THF) as promoter in the flow loop system. A laboratory flow mini-loop apparatus was set up to measure the induction time of methane hydrate formation. The induction time is predicted using developed Kashchiev and Firoozabadi model and modified model of Natarajan for a flow loop system. Furthermore, the effects of volumetric flow rate of the fluid on the induction time were investigated. The results of the models were compared with experimental data. They show that the induction time of hydrate formation in the presence of THF is very short at high pressure and high volumetric flow rate of the fluid. It decreases with increasing pressure and liquid volumetric flow rate. It is also shown that the modified Natarajan model is more accurate than the Kashchiev and Firoozabadi ones in prediction of the induction time.

Enhancement of the performance of modified starch as a kinetic hydrate inhibitor in the presence of polyoxides for simple gas hydrate formation in a flow mini-loop apparatus

The main objective of the present work is the enhancement of the performance of modified starch as a kinetic inhibitor in the presence of polyoxides such as ethylene oxide (PEO) and polypropylene oxide (PPO) for simple gas hydrate formation in a flow mini-loop apparatus. Polyoxides such as PEO and PPO are high molecular weight polymers that are not kinetic inhibitors by themselves. For this investigation, a laboratory flow mini-loop apparatus was set up to measure the induction time and rate of gas hydrate formation when a hydrate forming substance (such as C1, C3, CO2 and i-C4) is contacted with water containing dissolved inhibitor in the presence or absence of polyoxides under suitable temperature and pressure conditions. In each experiment, water containing inhibitor blend saturated with pure gas is circulated up to a required pressure. Pressure is maintained at a constant value during experimental runs by means of required gas make-up. The effect of PEO and PPO on induction time and gas consumption during hydrate formation is investigated in the presence or absence of modified starch as a kinetic inhibitor. The results showed that the induction time is prolonged in the presence of PPO compared to the inhibitor alone. The efficiency of PPO is higher than the PEO, because, the induction time for simple gas hydrate formation in presence of PPO is greater than by using the PEO in presence of kinetic hydrate inhibitors.Also, the results show, that the gas consumption in the presence of modified starch is lower that in the absence of this inhibitor for all experiments. Moreover, the inhibition effect is clearly seen as well as the synergism between the inhibitor and PEO or PPO and this effect is higher in the presence of PPO.

Experimental investigation of gas consumption for simple gas hydrate formation in a recirculation flow mini-loop apparatus in the presence of modified starch as a kinetic inhibitor

The main objective of the present work is to investigate experimentally the formation of simple gas hydrate with or without the presence of kinetic inhibitors such as modified starch in a recirculation flow loop. For this purpose, a laboratory recirculation flow mini-loop apparatus was set up to measure the induction time for hydrate formation and gas consumption rate when a hydrate forming substance (such as C1, C3, CO2 and i-C4) is contacted with water in the absence or presence of dissolved inhibitor under suitable temperature and pressure conditions. In each experiment, a water blend saturated with pure gas is circulated up to a required pressure. Pressure is maintained at a constant value during experimental runs by means of the required gas make-up. The effect of pressure on gas consumption during hydrate formation is investigated with or without the presence of polyvinylpyrrolidone (PVP) and modified starch as kinetic inhibitors at various concentrations. Our results show that the modified starch can be applied as an inhibitor in prevention of simple gas hydrate formation.

Evaluation of various types equations of state on prediction of rate of hydrate formation for binary gas mixtures in the presence or absence of kinetic hydrate inhibitors in a flow mini-loop apparatus

This paper compares the effects of using various types of equations of state (PR,11Peng Rabinson. PSRK,22Soave Ridlich Kowng. ER,33Esmaeilzadeh–Roshanfeker. NB44Nasrifar–Boland. and VPT55Valderrama-Patel–Teja.) for gas consumption during gas hydrate formation based on the Kashchiev and Firoozabadi model for binary gaseous mixtures such as 70% C1/30%C3, 30% C1/70% C3, 70% C1/30% i-C4, 30% C1/70% i-C4 with experimental data points obtained in a flow mini-loop apparatus in presence or absence of kinetic hydrate inhibitors at various pressures and specified temperature. A laboratory flow mini-loop apparatus is designed and built up to measure the gas consumption rate during gas hydrate formation.For the prediction of the gas consumption rate for double gas hydrate formation in a flow mini-loop apparatus, the rate equation based on the Kashchiev and Firoozabadi model for simple gas hydrate formation in batch system was developed. The total average absolute deviation was found to be 17.6%, 18.1%, 18.8%, 19.1% and 19.6% for the PR, NB, ER, PSRK and VPT equations of state for calculating gas consumption for binary gaseous mixtures during gas hydrate formation in the presence and absence of kinetic hydrate inhibitors, respectively. Comparison results between the calculated and experimental data points of gas consumption were obtained in flow loop indicate that the PR and NB equations of state have lower errors than the PSRK, ER and VPT equations of state for this model.

Prediction of induction time for natural gas components during gas hydrate formation in the presence of kinetic hydrate inhibitors in a flow mini-loop apparatus

The objective of this work is the prediction of induction time (ti) for simple gas hydrate formation in the presence or absence of kinetic hydrate inhibitors at various conditions based on the Kashchiev and Firoozabadi model in a flow mini-loop apparatus. For this purpose, the ti model is developed for simple gas hydrate formation in batch system for natural gas components during hydrate formation in a flow mini-loop apparatus. A laboratory flow mini-loop apparatus is designed and built up to measure the ti for simple gas hydrate formation when a hydrate former (such as C1, C3, CO2 and i-C4) is contacted with water in the absence or presence of dissolved inhibitor, such as poly vinylpyrrolidone, PVCap and L-tyrosine. In each experiment, a water blend saturated with pure gas is circulated up to a required pressure. Pressure is maintained at a constant value during experimental runs by means of the required gas make-up. The average absolute deviation (AAD) of the predicted ti values from the corresponding experimental data are found to be about 11% and 9.4% for gas hydrate formation ti in the presence or absence of kinetic hydrate inhibitors, respectively. © 2012 Canadian Society for Chemical Engineering

Experimental Investigation of Natural Gas Components During Gas Hydrate Formation in Presence or Absence of the L-Tyrosine as a Kinetic Inhibitor in a Flow Mini-loop Apparatus

Hydrates are crystalline compounds similar to ice, with guest molecules like methane and ethane trapped inside cavities or cages formed by the hydrogen bounded framework of water molecules. These solid compounds give rise to problems in the natural gas oil industry because they can plug pipelines and process equipments. Low dosage hydrate inhibitors are a recently developed hydrate control technology, which can be more cost-effective than traditional practices such as methanol and glycols. The main objective of the present work is to experimentally investigate simple gas hydrate formation with or without the presence of kinetic inhibitors in a flow mini-loop apparatus. For this purpose, a laboratory flow mini-loop apparatus was set up to measure the induction time and gas consumption rate during gas hydrate formation when a hydrate forming substance such as methane, ethane, propane, carbon dioxide and iso- butane is contacted with water in the absence or presence of dissolved inhibitor at various concentration under suitable temperature and pressure conditions. In each experiment, a water blend saturated with pure gas is circulated up to a required pressure. Pressure is maintained at a constant value during experimental runs by means of the required gas make-up. The effect of pressure on gas consumption during hydrate formation is investigated with or without the presence of PVP (polyvinylpyrrolidone) and L-tyrosine as kinetic inhibitors at various concentrations. The experimental results show that increasing the pressure of the system, causes to increase the experimental gas consumption and decrease the induction time. Also, the extent of gas hydrate formation at a given time is clearly less in the presence of the inhibitors. Moreover, when comparing the gas consumption during the hydrate formation for simple gas hydrate formation in presence of PVP and L-tyrosine inhibitors, it is seen that the gas consumption in presence of L-tyrosine is lower than that of PVP for all experiments.

Intensification of the performance of kinetic inhibitors in the presence of polyethylene oxide and polypropylene oxide for simple gas hydrate formation in a flow mini-loop apparatus

The main objective of the present work is enhancement of the performance of gas hydrate kinetic inhibitors in the presence of polyethylene oxide (PEO) and polypropylene oxide (PPO) for simple gas hydrate formation in a flow mini-loop apparatus. PEO and PPO are high molecular weight polymers that are not kinetic inhibitors by their self. For this investigation, a laboratory flow mini-loop apparatus was set up to measure the induction time and rate of gas hydrate formation when a hydrate-forming substance (such as C1, C3, CO 2 and i-C4) is contacted with water containing dissolved inhibitor in presence or absence of PEO or PPO under suitable temperature and pressure conditions. In each experiment, water containing inhibitors blend saturated with pure gas is circulated up to a required pressure. Pressure is maintained at a constant value during experimental runs by means of required gas make-up. The effect of PEO and PPO on induction time and gas consumption during hydrate formation is investigated in the presence or absence of PVP (polyvinylpyrrolidone) and l-tyrosine as kinetic inhibitors. Results were shown that the induction time is prolonged in the presence of PEO or PPO compared to the inhibitor only. Inclusion of PPO into a kinetic hydrate inhibitor solution shows a higher enhancement in its inhibiting performance compare to PEO. Thus, the induction time for simple gas hydrate formation in presence of kinetic hydrate inhibitor with PPO is higher, compare to kinetic hydrate inhibitor with PEO.

Effect of various types of equations of state for prediction of simple gas hydrate formation with or without the presence of kinetic inhibitors in a flow mini-loop apparatus

This paper compares the effects of using various types of equations of state (PR, 1 1 Peng–Robinson. SRK, 2 2 Soave–Redlich–Kwong. ER, 3 3 Esmaeilzadeh–Roshanfekr. PT 4 4 Patel–Teja. and VPT 5 5 Valderrama–Patel–Teja. ) on the calculated driving force and rate of gas consumption based on the Kashchiev and Firoozabadi model for simple gas hydrate formation for methane, carbon dioxide, propane and iso-butane with experimental data points obtained in a flow mini-loop apparatus with or without the presence of kinetic inhibitors at various pressures and specified temperatures. For this purpose, a laboratory flow mini-loop apparatus was set up to measure gas consumption rate when a hydrate forming substance (such as C 1, C 3, CO 2 and i-C 4) is contacted with water in the presence or absence of dissolved inhibitor under suitable temperature and pressure conditions. In each experiment, a water blend saturated with pure gas is circulated up to a required pressure. Pressure is maintained at a constant value during experimental runs by means of the required gas make-up. The total average absolute deviation was found to be 15.4%, 16.3%, 15.8%, 17.8% and 17.4% for the PR, ER, SRK, PT and VPT equations of state for calculating gas consumption in simple gas hydrate formation with or without the presence of kinetic hydrate inhibitors, respectively. Comparison results between the calculated and experimental data points of gas consumption were obtained in flow loop indicate that the PR and ER equations of state have lower errors than the SRK, VPT and PT equations of state for this model.

Experimental and theoretical investigation of simple gas hydrate formation with or without presence of kinetic inhibitors in a flow mini-loop apparatus

Gas hydrates are ice-like crystalline compounds, which form through a combination of water and suitably sized guest molecules under low temperature and elevated pressure conditions. These solid compounds give rise to problems in the natural gas oil industry because they can plug pipelines and process equipment. Low dosage hydrate inhibitors are a recently developed hydrate control technology, which can be more cost-effective than traditional practices such as methanol and glycols. The kinetics of hydrate growth has been modeled by numerous authors who have measured the gas consumption rate during hydrate formation in batch agitator reactors. The main objective of the present work is to investigate experimentally of simple gas hydrate formation with or without the presence of kinetic inhibitors in a flow mini-loop apparatus. To predict 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 this objective. To complete the theoretical evaluation of gas hydrate formation through the pipeline with or without the presence of kinetic hydrate inhibitors (KHIs), a laboratory flow mini-loop apparatus was set up to measure the induction time for hydrate formation and the uptake rate when a hydrate forming substance (such as C1, C3, CO 2 and i-C4) is contacted with water in the absence or presence of dissolved inhibitor under suitable temperature and pressure conditions. In each experiment, a water blend saturated with pure gas is circulated up to a required pressure. Pressure is maintained at a constant value during experimental runs by means of the required gas make-up. The effect of pressure on gas consumption during hydrate formation is investigated with or without the presence of polyvinylpyrrolidone (PVP) and l-tyrosine as kinetic inhibitors at various concentrations. A good agreement is found between the predicted and experimental data with or without the presence of KHIs. The total average absolute deviation percent between the experimental and predicted gas consumption is found to be 15.8% and 14.9% for simple gas hydrate formation with or without presence of kinetic inhibitors, respectively.