Natural Gas Dehydration Process Research Articles

Artificial neural network modelling of natural gas dehydration process

A multi-input–multi-output artificial neuron network (MIMO-ANN) model has been developed for process monitoring and improvement on a natural gas glycol dehydration process. The MIMO-ANN model was based on a steady-state process simulation model constructed in commercial software Aspen HYSYS. A set of training data was generated with the converged simulation model for the training of the MIMO-ANN model in Python. The process input of the model includes lean glycol recirculation rate and purity along with wet gas inlet pressure. On the other hand, the process output considered includes dehydrated gas water and aromatics content, dehydrated gas hydrate formation temperature and water dew point, stripping gas flow rate as well as reboiler duty. The overall mean squared error (MSE) of the MIMO-ANN model was calculated as 1.79. The best-fit line that highly overlaps with a 45° diagonal line is constructed with a correlation coefficient (R2) score of more than 0.999 for all studied process output testing datasets. The mean absolute percentage error (MAPE) of the predicted outputs is generally less than 1%, except for dehydrated gas water dew point (16.63%) and stripping gas flow rate (11.55%), due to error predictions attempted on pseudo-zero values. This successfully displays an exceptional predictive performance of the MIMO-ANN model developed in this work which can be further deployed as an online dashboard for real-time monitoring tool.

Selection of Natural Gas Dehydration Process for Offshore Floating Production Storage and Offloading

Based on the oil and gas component data of an offshore gas field in West Africa, the steady‐state models of the triethylene glycol (TEG) dehydration process and the low‐temperature separation dehydration process are established. The adaptability of two kinds of processes to the disturbance of pressure, temperature, and flow of imported natural gas source is studied, and the sensitivity analysis is carried out. In addition, the investment cost and operating cost of the two types of processes are compared. The low temperature separation dehydration process is more adaptable to the disturbance of inlet gas source than the TEG dehydration process. The former is more expensive to build than the latter, but less expensive to run. The low temperature separation dehydration is preferred as the natural gas dehydration process which is more suitable for floating production storage and offloading.

Investigation of natural gas dehydration process using triethylene glycol (TEG) based on statistical approach

Investigation of natural gas dehydration process using triethylene glycol (TEG) based on statistical approach

Multi-objective particle swarm optimization of industrial natural gas dehydration process

Multi-objective particle swarm optimization of industrial natural gas dehydration process

Enhanced Regeneration of Triethylene Glycol Solution by Rotating Packed Bed for Offshore Natural Gas Dehydration Process: Experimental and Modeling Study

To address the problems of confined space for offshore application, rotating packed bed (RPB) was firstly used to enhance the regeneration of TEG solution in natural gas dehydration process. The performance of the regeneration, which was exhibited in terms of the desorption efficiency and mass transfer coefficient, was investigated experimentally. The effects of various operating parameters, including rotation speed, gas-liquid ratio, liquid flow rate, liquid inlet temperature, and inlet concentration of rich TEG were studied to assess the impacts on the regeneration process. It was found that the purity of regenerated TEG solution by RPB was basically above 99.7% under a common gas-liquid ratio of 45 (volume ratio), and even higher than 99.98% under the optimal conditions. A mass transfer model combined two-film theory and penetration theory was established, which could well predict the TEG solution regeneration performance in RPB. According to the established model and ASPEN simulation result, an RPB and a packed column were designed respectively for a specific TEG regeneration task. It was found the volume reduction factor of RPB was about 8, which showed well adaptation of RPB for the offshore natural gas extraction due to the outstanding mass transfer performance in the TEG regeneration process.

Performance optimization of an industrial natural gas dehydration process to reduce energy consumption and greenhouse gases (GHGs) emission

AbstractNatural gas dehydration using multi‐layer adsorption beds is one of the most essential processes in gas processing plants, where the water molecule is removed from raw gas by a continuous cyclic temperature swing adsorption operation. In the present research, a commercial adsorption unit for dehydration of natural gas has been studied, and the effects of the volume of adsorbents in the multi‐layer adsorption beds on the overall performance of the process have been investigated using a precise mathematical model. The numerical method of lines (NMOL) has been applied to solve the partial differential equations (PDEs) demonstrating the fixed bed. The real plant data from the industrial unit have been used for validation of the model. The simulated breakthrough time, bed pressure drop, and dried gas temperature are found to be in good agreement with experimental measurements with an error of less than 4%. The modelling results are applied to obtain the optimum adsorbents layers' configuration using response surface methodology (RSM). The objective functions are pressure drop and water breakthrough time, while variables are the length of two molecular sieve layers with different particle sizes, which are loaded in each adsorption column. The results indicated that an 18.45% reduction in the direct and indirect greenhouse gases (GHGs) emission (35 369.59 MT/year) during the regeneration cycle and a significant decrease in energy consumption (623 609 GJ/year) can be achieved by applying the optimal configuration. Moreover, 1 year of longer continuous operation (by avoiding nearly 45 regenerations) is another desirable outcome of the optimization.

Advanced Process Control for Cost-Effective Glycol Loss Minimization in a Natural Gas Dehydration Plant under Upset Conditions

The monoethylene glycol (MEG)-based natural gas (NG) dehydration process often faces significant glycol losses at the stripper column because of vaporization and poor NG liquid recovery because of ...

Ionic Liquid versus Traditional Volatile Organic Solvent in the Natural Gas Dehydration Process: A Comparison from a Life Cycle Perspective

The life cycle environmental sustainability of the natural gas (NG) dehydration process using novel dehydrant [EMIM][Tf2N] ionic liquid (IL) has been evaluated using a “cradle to grave” life cycle ...

Process Simulation and Optimization of Natural Gas Dehydration Process using Aspen Hysys

Natural Gas is More Efficient than Other Forms of Fossil Fuel. Natural gas produces more energy than any of the fossil fuels. Although the primary use of natural gas is as a fuel, it is also a source of hydrocarbons for petrochemical feedstocks and a major source of elemental sulfur, an important industrial chemical. The process simulation and optimization of natural gas dehydration process including mono ethylene glycol (MEG) injection and its regeneration process is studied in this research work. This study also carried out the operation parameters and optimization. The simulation is carried out using Aspen-HYSYS. The effect of replacement MEG by DEG and influence of replacement of Chiller by a turbo expander refrigeration technique on the DPCU operation was studied. The result obtained for optimum parameters like inlet pressure and temperature of the LTS are studied and comparing chiller and expander to maximize NGL are presented. The study recommends to use the expander instead of the chiller. The the economic evaluation of the proposed modification is presented in this study.

Subsea natural gas dehydration with membrane processes: Simulation and process optimization

Subsea processing enables broader exploration of oil and gas reservoir, giving an increased focus on developing alternative processes for subsea oil and gas treatment. This work provides a first evaluation of a new proposed subsea natural gas dehydration process with the use of a membrane contactor with triethylene glycol (TEG) for dehydration of the natural gas in combination with thermopervaporation for regeneration of the TEG. Simulation models are developed in Aspen HYSYS V8.6 and process optimization is performed on three different process designs with respect to staging of the regeneration. By introducing two thermopervaporation units in series the TEG flow rate is reduced by 55%, the membrane volume by 14.6% and the energy demands by 37.8%, compared to a design with one thermopervaporation unit. However, increasing the number of regeneration stages increases the complexity as additional heaters are introduced.

A Parametric Study of Different Recycling Configurations for the Natural Gas Dehydration Process Via Absorption Using Triethylene Glycol

In this work, the effect of triethylene glycol (TEG) flowrate on the water content in dry product gas, the TEG loss rate, and the BTEX (i.e. benzene, toluene, ethylbenzene, and xylene) emission of a conventional natural gas dehydration process via absorption using TEG were evaluated. Given the conflicting nature of decreasing water content against increasing BTEX emission and TEG loss rate with increasing TEG flowrate, an optimum TEG flowrate was determined that gives the minimum water content in dry product gas with minimum TEG loss rate and BTEX emission. The possibility of improving the dehydration process performance was additionally investigated through recycling the flash vapour or the regenerator overhead or both the flash vapour and the regenerator overhead into the absorber. The aforementioned recycling configurations aim towards sustainable design for a natural gas dehydration process that provides a lower BTEX emission and TEG loss rate (i.e. plant’s wastage). These recycling configurations were also evaluated based on economic analysis. Our simulation results however revealed that the TEG loss rate is only reduced by 0.4% in all three different configurations. The reduction in water content, on the other hand, is always traded-off by the increase in the total BTEX emission and vice versa, by marginal amount, relative to the base case scenario. Therefore, applying such configuration does not contribute towards sustainable design and significant process performance improvement despite requiring substantial additional capital and operational costs.

Simulation and Optimization of the Utilization of Triethylene Glycol in a Natural Gas Dehydration Process

Abstract The dehydration unit of a plant that processes natural gas uses triethylene glycol (TEG) as an absorbent to remove water from the gas to prevent blockages in pipes due to the formation of hydrates. Although TEG is recyclable, it is usually lost in the system due to vaporization and carryover, which results in economic issues. Therefore, it is necessary to optimize the dehydration process to achieve the allowable water concentration in the gas, to minimize the use of energy, and to minimize the loss of TEG. Experimental set was designed using Design Expert software by utilising data from Farashband gas processing plant, Iran and subsequently, fed to ASPEN HYSYS to construct and simulate the dehydration process. The chosen affecting parameters to the process were the (1) lean glycol circulation rate, (2) the temperature of the reboiler, and (3) the number of trays in the contactor column. Whereas, the response parameters included the (1) amount of glycol that was lost, (2) the reboiler duty, (3) the concentration of water in the dry gas, and the (4) temperature at which the hydrate formed. Then, these data were optimized using the response surface methodology (RSM). The results indicated that the optimum conditions within the experimental range conducted in this study of process parameters chosen, of the lean glycol circulation rate, the temperature of the reboiler, and the number of trays in the glycol contactor column for the gas dehydration process for the plant were 3944 kg/hr, 180 °C, and three trays, respectively.

Natural Gas Dehydration with Ionic Liquids

The technology of natural gas dehydration with ionic liquids (ILs) as a promising method was proposed and systematically investigated in this work. The IL [EMIM][Tf2N] was screened out as an appropriate absorbent from 252 IL candidates for the natural gas dehydration process by means of the COSMO-RS model. The σ-profiles and σ-potentials of the CH4-H2O-IL system were analyzed at the molecular level to explain the possibility of CH4 dehydration using [EMIM][Tf2N] as absorbent. The experiment data of CH4 solubility in pure IL and in the mixture of IL + H2O were measured and compared with the predicted results by the UNIFAC–Lei model. Moreover, the CH4 dehydration experiment was carried out, and the gas product with a low water content (down to 350 ppm in mole fraction) can be obtained. Finally, the conceptual dehydration process was simulated and optimized using the rigorous equilibrium (EQ) stage model, into which the UNIFAC–Lei model parameters were input. It was found that the CH4 dehydration process wit...

Assessment of new and improved solvent for pre-elimination of BTEX emissions in glycol dehydration processes

Emission of benzene, toluene, ethylbenzene, and xylene (BTEX) from natural gas dehydration units was highlighted as an acute environmental impact. Furthermore, recent stringent environmental regulations addressed a pressing need of knowledge to eliminate hydrocarbon's emissions from glycol dehydrators. The primary objective of this study is to combine the minimization of BTEX emissions with an efficient dew point control. However, the approach in this research emphasis on the cause of the BTEX emissions rather than the post treatment process. Chemically modified monoethylene glycol (mMEG) is proposed as a new solvent to replace triethylene glycol (TEG) in the dehydration process. The results of this study showed a significant improvement in the dehydration performance together with the elimination of (BTEX) emissions. The results demonstrated that mMEG could produce gas water content of 0.16ppm (7.6×10−3lb/mmscf) and near zero level of BTEX. This investigation suggests that using mMEG can solve the environmental issue of BTEX in the natural gas dehydration process.

Quantitative structure–activity relationships (QSARs) for estimation of activity coefficient at infinite dilution of water in ionic liquids for natural gas dehydration

Recently, ionic liquids (ILs) have been considered as alternative solvents to glycol in dehydration of natural gas. However, due to the unlimited structural variations and possible combinations of cations and anions of the ILs, selection of potential ILs for this separation process has been a difficult task. Activity coefficient at infinite dilution is one of the most important thermodynamic properties for preliminary selection of suitable liquid desiccants for water absorption and designing of the natural gas dehydration process. In this paper, COSMO-RS based quantitative structure–property/activity relationship (QSPR/QSAR) models were developed for prediction of activity coefficient of water at infinite dilution in ILs over various temperatures. COSMO-RS based descriptors were generated for 53 ILs (318 data points) at various temperatures. Multiple linear regressions were applied to develop the models. The accuracies of the models were verified by different statistical tests. The model provides a better understanding of the effect of the structural variations of ILs on their affinity for water.

Experimental investigations on the phase behavior of the aromatic mixtures regarding the performance enhancement of natural gas dehydration processes in petroleum industry

ABSTRACTThe phase behavior of ternary systems in three-phase separator including benzene-heptane-water and toluene-heptane-water are investigated at 298.15 K and 308.15 K. It is shown that the water solubility in hydrocarbon phase and the benzene and toluene solubilities in aqueous phase decrease considerably with increasing n-heptane concentration. Moreover, the discarded water phase from three-phase separator to the environment in azeotropic regeneration process is less contaminated by aromatic compounds (BTEX) in comparison with the one in the traditional dehydration process. It is shown that the n-heptane can be used as a stripping medium in the azeotropic regeneration process to achieve less than 1% water in the TEG solvent employed for natural gas dehydration process of gas refining plants.

Mitigation of BTEX emission from gas dehydration unit by application of Drizo process: A case study in Farashband gas processing plant; Iran

As greenhouse gas emissions have became a concern to the entire natural gas industry, it is always balanced with the obligation of reasonable investment levels and production costs. According to environmental regulations, emission of aromatic compounds and other hazardous materials from this process is a challengeable issue. In the natural gas dehydration process, glycol solvents use to remove water from the natural gas stream in order to meet the pipeline quality standards. Farashband gas processing plant consists of six dehydration units operate using stripping gas injection. In this study, to mitigate the BTEX compounds emission rate in the Farashband gas processing plant, two alternatives based on the Drizo process for solvent regeneration are proposed. In the first technique, application of a single Drizo process in each dehydration unit is investigated and in the second, use of a complex Drizo process instead of three separated single Drizo processes is suggested. These alternatives aim to minimize environmental disadvantages and improve the most important operating parameters such as dry gas water dew point temperature, glycol loss and glycol purity. Simulation results indicate that TEG as dehydrating agent has a better performance with respect to DEG. Single Drizo process shows the most significant change of water dew point followed by complex Drizo process and conventional stripping gas dehydration process. Also in the case of Drizo process, the water content of natural gas reduces with increasing the reboiler operating temperature from 180 °C to 200 °C. Although the BTEX emission rate in three single Drizo processes is lower than a complex Drizo process, economic evaluations represented that the additional total capital investment decreased from 2.406 million$ to 1.365 million$ using the complex Drizo process instead of three single Drizo processes. Also investigation of different solvents showed that though n-Heptane has the best performance among different solvents, use of the recycled BTEX compounds as a solvent, not only reduces the BTEX emission rate, it decreases the additional costs. Also data analysis represents that by considering this fact that the BTEX emission rate enhances with increasing glycol circulation rate, the optimum TEG circulation rate for both single and complex Drizo processes is approximately 4 (gal TEG/lb water).

Simulation and feasibility analysis of structured packing replacement in absorption column of natural gas dehydration process: A case study for Farashband gas processing plant, Iran

Application of structured packing in separation processes like natural gas dehydration has been increased since last few years. Replacement of the existing trayed column with that of structured packing can enhance the capacity and performance of the natural gas dehydration process. In this work, the natural gas dehydration plant of Farashband gas processing plant has been simulated. The profile of concentration, temperature and pressure in absorption column was obtained. A computer program, prepared with Visual Basic, has been proposed to calculate the height equivalent to a theoretical plate (HETP) of structured packing. The effect of some important parameters of inlet Tri-ethylene glycol (TEG) and natural gas on the performance of absorption column have been analyzed. Results show that revamp of trays with structured packing, can reduce outlet natural gas dew point and improve the positive effect of other parameters on the performance of dehydration unit. Moreover, the most significant factors affecting the HETP were investigated which were less than 15% effective. Finally, the cost of the modification project for the absorption column in the Farashband gas processing plant was calculated. The cost is evaluated 202,909 $ in this case and replacing was found economically justifiable.

Estimation of triethylene glycol (TEG) purity in natural gas dehydration units using fuzzy neural network

Natural gas usually contains a large amount of water and is fully saturated during production operations. In natural gas dehydration units' water vapor is removed from natural gas streams to meet sales specifications or other downstream gas processing requirements. Many methods and principles have been developed in the natural gas dehydration process for gaining high level of triethylene glycol (TEG) purity. Among them, reducing the pressure in the reboiler at a constant temperature results in higher glycol purity. The main objective of this communication is the development of an intelligent model based on the well-proven standard feed-forward back-propagation neural network for accurate prediction of TEG purity based on operating conditions of reboiler. Capability of the presented neural-based model in estimating the TEG purity is evaluated by employing several statistical parameters. It was found that the proposed smart technique reproduces the reported data in the literature with average absolute deviation percent being around 0.30%.

Natural Gas Dehydration Process Simulation and Optimization: A Case Study of Khurmala Field in Iraqi Kurdistan Region

Natural gas is the most popular fossil fuel in the current era and future as well. Natural gas is existed in underground reservoirs so it may contain many of non-hydrocarbon components for instance, hydrogen sulfide, nitrogen and water vapor. These impurities are undesirable compounds and cause several technical problems for example, corrosion and environment pollution. Therefore, these impurities should be reduce or removed from natural gas stream. Khurmala dome is located in southwest Erbil-Kurdistan region. The Kurdistan region government has paid great attention for this dome to provide the fuel for Kurdistan region. However, the Khurmala associated natural gas is currently flaring at the field. Moreover, nowadays there is a plan to recover and trade this gas and to use it either as feedstock to power station or to sell it in global market. However, the laboratory analysis has showed that the Khurmala sour gas has huge quantities of H2S about (5.3%) and CO2 about (4.4%). Indeed, Khurmala gas sweetening process has been removed in previous study by using Aspen HYSYS. However, Khurmala sweet gas still contents some quintets of water about 23 ppm in sweet gas stream. This amount of water should be removed or reduced. Indeed, water content in natural gas cause several technical problems such as hydrates and corrosion. Therefore, this study aims to simulate the prospective Khurmala gas dehydration process by using Aspen HYSYS V. 7.3 program. Moreover, the simulation process succeed in reducing the water content to less than 0.1 ppm. In addition, the simulation work is also achieved process optimization by using several desiccant types for example, TEG and DEG and it also study the relationship between absorbents type and its circulation rate with HCs losses from glycol regenerator tower. Keywords—Aspen Hysys, Process simulation, gas dehydration, process optimization.