Dehydration Plant Research Articles

An analytical study of TEG loss in a natural gas purification plant based on high-pressure droplet angular scattering

In the process of purifying natural gas, natural gas dehydration plants use triethylene glycol (TEG) as a solvent for absorption. However, the loss of TEGs in the form of droplets can pollute pipelines and create a technological challenge. Using the geometric optical approximation (GOA) method, a model was developed to predict the scattering of droplets at high pressure. Based on this model, a device was designed and constructed to inspect droplets in external pipelines and distillation column tailgate lines online, which are the outlets of the natural gas dehydration unit (TEG absorber tower) of four columns in stable production. This device analyzes the components of the sampled droplets and performs online inspection to ensure smooth and safe operation. The results of the experiment indicate that the TEG content in the droplet samples exceeded 80%, which helped identify the source of the loss. The amount of treatment directly affected the concentration and distribution features of the entrained droplets, whereas the impact of the gas-phase pressure change was negligible. This study investigated three different forms of filtration separation, which provided industrial data for the separation and recovery process of entrained droplets. This study provides a new testing tool and method to examine plate towers under high pressure and provides a theoretical reference for dewatering procedures in natural gas purification plants.

Design modification and comparative analysis of glycol‐based natural gas dehydration plant

AbstractNatural gas production from reservoirs is often associated with water, which poses numerous challenges, such as methane hydrate formation, sludge, corrosion and flow assurance issues in gas processing plants and sales gas transmission pipelines. To effectively remove water from natural gas, there is a need to design, compare and modify dehydration plants. This study investigated the performance difference between a conventional triethylene glycol (TEG)‐based dehydration system with a cooler at the TEG inlet to the contactor, and a newly proposed TEG‐based dehydration system with a heat exchanger replacing the cooler at the TEG inlet with the contactor. The advanced process simulation software Aspen HYSYS was used to design and compare two dehydration system configurations. The modified design configuration exhibited better performance in terms of energy conservation and water‐removal capability. The material balance of molar flow, mass flow and volume flow of dry gas produced in the absorber/contactor column showed a higher volume of dry gas produced in the modified system configuration, indicating that it is a better design. The modified design configuration also produced dry gas within the recommended temperature range for underground storage and transmission. There was a significant difference in the percentage difference of 64% between the conventional and modified designs in terms of energy consumption, whereas the percentage differences of 0% and 0.6% showed nonsignificant and significant differences between the two plant design configurations. Both plant design configurations showed a significant reduction (from 0.005 to 0.0002 mol%) in the water composition of natural gas after the simulation.

Design and Optimization of Glycol-Based Natural Gas Dehydration Plant

Design and Optimization of Glycol-Based Natural Gas Dehydration Plant

Assessment of chemical enhancement and energy consumption of natural gas dehydration processes

Water vapors are found in high concentrations during natural gas production and processing. Energy consumption is known to be a drawback of the glycol dehydration process. Toxic and greenhouse gas emissions are another drawback from the environmental point of view. This paper served to propose a solution to the two problems together by using an emissions stream from the regenerator distillation tower to serve as a striping gas which solved the environmental problem of emissions and helped to reduce energy consumption. Aspen HYSYS was used to model glycol dehydrating as the most widely used and economically viable technique for drying off natural gas streams. This method uses the solvent tri ethylene glycol (TEG) as the absorbent. The focus of this research is to analyze sensitivity to the modeling outcomes. Furthermore, the results suggest that the process might be enhanced and save energy consumption. The simulation used three different tri-ethylene glycol flows, stripping gas flows, and different reboiler temperatures were used in the simulation. The modeling technique was effective in decreasing the water content in the regeneration column from 75lb/MMSCF to 2.5lb/MMSCF and saving energy consumption during the dehydration of natural gas. However, the results showed that in the fourth case when the amount of triethylene glycol is equal to 665.3 kg/h, and reboiler energy is equal to 247300 kJ/h, therefore the energy consumed per kilogram of the TEG is equal to 371.7 kJ/kg which represents the lowest amount of energy consumed during solvent regeneration. However, the results suggest that using emissions as a stripping gas can increase TEG purity and boost the efficiency of the dehydration plant, which appears to be a better option in the long run. The results suggest that the demonstrated approach may help towards decarbonization and zero emission of the dehydration process.

Low-Energy Fruit Dehydration Method

This article describes a low-energy fruit dehydration method. To evaluate the effectiveness of this method, an experimental fruit dehydration plant of the tunnel type was developed, on the basis of which the studies were carried out. Convection and microwaves have been used to treat the fruits during the dehydration process. The results obtained on the basis of the proposed method were compared with those obtained when using the classical dehydration method. Thus, studies have shown that dehydration of fruits by the new method allows of reducing electric energy consumption by 4.69 times.

Study The Effect of The Main Variables on The Objectives of The Natural Gas Dehydration Plant by ASPEN-HYSYS v8.8

In the NGD process, TEG dehydration is commonly employed to prevent corrosion and blockage of equipment, valves, and piping systems. TEG is frequently lost in the system during this procedure owing to vaporization and carryover. Therefore, it is necessary to study the affection of variables of the dehydration process the process was simulated with ASPEN-HYSYSV8.8 and the thermodynamic model was glycol-package; the process was validated by comparing the Plant results with the simulation results and demonstrating good acceptance. ASPEN-HYSYS conducted a sensitivity study to investigate the impact of variables on the main objectives. , as this study showed that not all of these variables have a strong effect, some of them have a weak effect, for example (wet gas pressure and same case of solvent pressure) and the rest of the variables have a strong effect on this process, so it must be taken into consideration by the station operators where this The changes were targeted because they are subject to change within the plant, and the highest value and the smallest value were taken according to the factory's parameters. As these variables are taken into account and the requisite improvements are made, the natural gas drying process will improve, and the dry gas requirements needed will improve, resulting in increased benefit.

Simulation and optimization of sweetening and dehydration processes in the pretreatment unit of a mini-scale natural gas liquefaction plant

This study focuses on the simulation of sweetening and dehydration processes for natural gas feed to achieve the liquefied natural gas specifications. The analysis and optimization of these two units have been carried out to reduce energy consumption. The sweetening and dehydration units lower the amount of carbon dioxide and water in treated gas to less than 50 ppmv and 0.1 ppmv, respectively. In the sweetening unit, due to the high energy consumption (45.63 kW) in the reboiler of the amine regeneration column, sensitivity analysis is used to investigate the variables causing high energy consumption. The optimum values for the main influencing variables were obtained by the response surface method. The optimization results in reboiler duty reduction by 30% compared to the base case simulation. In the dehydration unit, due to the high energy consumption of the furnace (100.7 kW) inlet stream temperature and regeneration temperature are analyzed as the influencing variables. By optimizing the unit, the energy consumption per mole production is reduced by 20% compared to the base case simulation. Through exergy analysis 836.13 kJ/kg CO2 exergy loss is estimated for sweetening plant and 5724.73 kJ/kg H2O exergy destruction for dehydration plant. The regenerator and absorber have a significant share of exergy losses in the sweetening plant and the furnace is the major contributor to exergy destruction in the dehydration plant.

Investigating the properties and performance of 3A molecular sieves as an adsorbent to prevent coke formation in olefin dehydration process

Abstract To study the affinity of 3A aluminosilicate adsorbents to prevent oligomerization of olefin molecules and forming green oil, physical and chemical properties of 3A molecular sieves are measured by using characterization techniques such as temperature-programmed desorption (TPD), nitrogen (N2) and water adsorptions, X-ray diffraction (XRD), X-ray fluorescence (XRF), crushing strength, and carbon dioxide (CO2) adsorption. Moreover, coke formation affinities of the understudy adsorbents are evaluated in a bench-scale system using 1-butene and 1,3-butadiene at temperatures of 220 and 260 °C, and outcomes are validated against the actual data gathered from an industrial scale olefin dehydration plant. Results confirm that the type of binder and the amount of ion exchange affect the performance of a 3A molecular sieve nominated for dehydrating olefinic streams. The binder with the least amount of acidity is preferred, and at least 35% of Na ions of the 4A zeolite should be exchanged with K ions to make it applicable for synthesizing an appropriate 3A molecular sieve. Furthermore, to control the oligomerization and inhibit green oil formation, the CO2 adsorption and acidity of Trisiv shape molecular sieves with the sizes of 1/4 inch should be less than 0.5 wt % and 1.7 mmol NH3/g, respectively. For extrudate shape with the sizes of 1/16 inch CO2 adsorption and acidity should be less than 0.2 wt % and 2.2 mmol NH3/g, respectively.

Evaluation of the Diethylene Glycol Regeneration rate in Gas Fields Based on Indirect Measurements

Gas dehydration in the field is a mandatory procedure before long-distance transportation. In Russia, gas is dried by absorption using diethylene glycol (DEG). Upon absorbing moisture from the raw gas, DEG is regenerated and recycled to dehydration, the quality of which largely depends on the regeneration rate. This indicator is not measured directly at the dehydration plant, and regeneration is controlled discretely based on the periodic laboratory analysis results. The paper describes a virtual analyzer determining the DEG concentration in a real-time mode based on the temperature and DEG consumption measurement results. The regression mathematical model underlying the virtual analyzer has been built based on experimental data obtained at the Yamburg gas condensate field. As part of the gas treatment plant APCS, a virtual analyzer improves the treatment efficiency and reduces the DEG consumption.

Evaluation of the Novel Dehydration Concept for Wild Multi Floral Honey in Vietnam

Dehydration of honey is an essential step during honey production in tropical countries to prevent rapid deterioration in quality because of the fermentation. In this study, honey dehydration at atmospheric pressure and temperatures of 36°C, 42°C, and 52°C in a pilot dehydration plant based on JEVA concept was carried out to reduce the moisture content of honey to below 17%. Honey dehydration at a temperature range of 36°C - 42°C achieved a high dehydration rate and low energy simultaneously due to integrating a heat pump into the processing loop. The temperature range of 36°C - 42°C was found out to be the most favourable processing temperature for honey dehydration since at these operational conditions, minimal colour degradation of honey, a low decline in diastase number and high retention of TPC and TFC (87.0% - 88.2% and 74.8% - 80.6%) were achieved. Moreover, honey samples dehydrated at 36°C and 42°C preserved antibacterial activity for strains of MRSE, Salmonella Typhimurium, Proteus Vulgaris, and Pseudomonas aeruginosa compared to raw honey. Under similar operational conditions, the proposed dehydration plant has been found to be better than that of other honey dehydrators reported in the literature in terms of dehydration rate, energy consumption, and lighter impacts on physiochemical characteristics.

Rate and equilibrium based modeling with the sequential quadratic programming optimization method for glycol dehydration of produced natural gas

Determining the optimum temperature and pressure for the dehydration of natural gas in a glycol absorption unit and the recovery of the glycol from the glycol water mixture in a desorption unit is of great importance. Although, the equilibrium base model for the absorption column design had been in use, the rate based model for the absorption unit offers a promising technique and had been proven to be more accurate in determining the parameters for the design. In this study, dehydration of a natural gas plant was modelled with optimization of its parameters. The effects on cost were adequately studied. Sensitivity analysis resulting from the simulation showed that a lower temperature for effective absorption of the water from the gas stream by triethylene glycol (TEGlycol) solvent is expected, while a higher temperature and higher reboiler duty is required for the regeneration of the solvent from the Rich TEGlycol stream in a distillation column. The sequential quadratic programming (SQP) direct optimization method was employed to optimize the major parameters of the natural gas dehydration plant. The optimum temperature of 267 °F and Reboiler duty of 169,789 Btu/h gave a 0.99 TEGlycol recovery purity. A minimized capital cost of 3.73 million US Dollars and operating cost of approximately 1 million US dollars was also observed.

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 ...

Glycol Loss Minimization for a Natural Gas Dehydration Plant under Upset Conditions

Low-temperature separation with a monoethylene glycol (MEG) injection process is a common dehydration technique for natural gas processing. However, the MEG-based dehydration system frequently suffers significant glycol loss during plant upset conditions, causing double penalties of economic loss and air emissions. Thus, it is very important to minimize MEG loss in the dehydration process. In this paper, an efficient and effective methodology to reduce MEG loss under upset conditions of a natural gas dehydration plant has been developed. First, a plant-wide steady-state simulation model is developed and validated at normal operating conditions. Next, the root cause analysis for MEG loss is performed by introducing various process upsets to the simulation model, which indicates that most MEG loss is due to the fluctuating temperature of the stripper column overhead. After that, a plant-wide dynamic simulation model is developed to help generate a new control strategy to regulate the stripper column operati...

Neural computing approach for estimation of natural gas dew point temperature in glycol dehydration plant

ABSTRACTHydrate formation and water accumulation during transmission process can be prevented by effective dehydration of gas streams. This study investigates the application of multi-layer perceptron artificial neural network to estimate natural gas dew point temperature using contactor temperature and TEG purity as independent variables. A dataset comprised of 173 data points is extracted from the literature. The proposed model is considered a great help for engineers to have precise dew point temperature predictive tool in wide ranges of concerning variables. Results obtained from the proposed model show R-squared and mean square error of 1.000 and 0.156, respectively. Accordingly, the remarkable agreement between predicted and experimental values is observed.

Process simulation of dehydration unit for the comparative analysis of natural gas processing and carbon capture application

Dehydration is a common step employed before the transmission of natural gas and/or carbon dioxide in order to avoid hydrate formation. This study is focused on the simulation of dehydration process for the natural gas and CO2 stream using triethylene glycol (TEG) solvent as the dehydrating agent. This study relates the experiences from the natural gas processing to the application of carbon capture and storage technology for CO2 dehydration. Two design configurations namely, conventional and stripping gas design are investigated using Aspen HYSYS to compare the performance improvement. The developed simulation model is first validated against the plant data and then the comparative analysis has been performed to understand the analogy between the natural gas and CO2 dehydration. Finally, a sensitivity has been performed using the stripping gas configuration to test the possible variables that can affect the process performance in terms of dehydrated stream purity, reboiler energy requirement and solvent losses. The results showed that Aspen HYSYS can reasonably predict the dehydration plant performance. The findings of this study also revealed that the CO2 dehydration process requires more energy compared to the same level of natural gas dehydration.

A study to reduce atmospheric emissions of an existing natural gas dehydration plant using multiple thermodynamic models

Using Aspen Plus, operating parameters of an existing triethylene glycol natural gas dehydration plant including the solvent circulation rate, stripping gas flow rate, regenerator reboiler duty, solvent temperature, absorber (contactor) pressure, flash unit pressure and regenerator pressure were optimized to reduce BTEX, VOCs and CO2 emissions. The plant consists of an absorber, a flash tank, a stripper and a regenerator. Two thermodynamic models including PRMHV2 and PSRK were utilized for this plant. The sensitivity analysis study was conducted using two methods, namely Method A and Method B. Method A considered the effect of an individual parameter on the emissions, while other parameters were set at their base case values. Method B studied the impact of a given parameter, while other parameters were at their optimum values. Using the two methods, BTEX emission reduced more than 40%, while VOCs and CO2 emissions were decreased more than 60%. However, the moisture content of the dehydrated gas was higher when Method A was applied (249.9 × 10−6 kg H2O/m3) compared to Method B (65.7 × 10−6 kg H2O/m3). Method B was found to be a more precise approach to achieve the optimum plant operation.

Optimal PI and PID Temperature Controls for a Dehydration Process

In this work, the drying air temperature for an experimental platform of sliced tomatoes dehydration is optimally regulated by using the very well-known integral control approach which could be equivalent to the PI control when the output system is the whole state. In a first stage, the chosen controller is a PI because the plant step response does not present oscillations with low damping. However, obtained experimental results, applying this controller, present some oscillations in the closed-loop transient response. So, in a second stage, a discrete PID controller is applied and its gains are computed by using a numerical optimization algorithm based on the hill climbing method, which considers a quadratic performance index; the proposed procedure assumes an input delayed discrete model of the plant; therefore, the stability is verified by the closed-loop poles location. The reason to apply an optimal control strategy is motivated by the energy saving and the preserving of a desired closed-loop performance of the process. In order to contrast the advantages to use an optimal controller, the obtained experimental results are compared with a PID controller tuned with the improved Ziegler–Nichols rules, which is optimized only considering a criterion depending on the error (the energy consumption it is not involved). Moreover, the performance given by optimal PI control is also compared with an optimal state feedback control. The synthesized controllers (computed gains) are programmed in an industrial programmable logic controller Siemens S7-1200, and they are applied to a sliced tomato dehydration plant. According to the obtained results, when the optimally tuned PID controller is applied, it produces energy saving rates, more uniform drying conditions for the product and a better closed-loop plant performance (shorter settling time and nonovershoot, which are desired features in this type of process), with respect to other tested controllers. The presented experimental results by using the PI and PID optimized controllers allow to verify the feasibility of our proposal.

Analysis of Methods for Improving the Efficiency of Coalescence Process in Electric Oil Desalination and Dehydration Plants

The methods for increasing the efficiency of the coalescence process in electric desalination and dehydration of oil are analyzed. It is shown that one of the main reasons for the decrease in the efficiency of operation of the electric dehydrators is failure to take account of several phenomena that accompany the formation of chains of water droplets between the electrodes when water-oil emulsions break up. In this case, the dispersion phenomenon in the region directly adjoining the electrodes makes the most contribution to formation of a large quantity of fine water droplets and to deterioration of the electric dehydrator performance. To increase the electric dehydrator efficiency, it is proposed that the size of the electrode and its potential be so chosen that no dispersion occurs near the electrode or the electrode surface is protected with a coating that transmits electric charge in a quantity sufficient to sustain the coalescence process, but insufficient for the dispersion process.

Prediction of the phase behavior of BTEX and alkane hydrocarbons in the presence of Tri-Ethylene Glycol (TEG) solvent

ABSTRACTA computational framework according to the CPA Equation of state by considering hydrogen bonding association and solvation effects has been proposed for accurate prediction of phase behavior of complex mixtures of triethylene glycol (TEG), BTEX aromatic hydrocarbons (benzene, toluene, ethylbenzene, and o-xlylene) and alkanes (methane, ethane, propane). The overall average absolute deviation between the predicted and measured phase compositions, regarding 150 data points is about 2.40% suggesting the accuracy of the presented approach. The presented model can be used for accurate design of BTEX containing natural gas dehydration plants in petroleum industry.

Dehydration of Ethanol/Water Mixture Using Pervaporation and Vapor Permeation Technique

The demand of bio–ethanol to substitute petroleum–based fuel is continuously increasing, and economic aspect has become an important factor in the design of ethanol dehydration plants. Since it forms an azeotrope at 89.4 mole%, 78°C and atmospheric pressure, further dehydration process is difficult and expensive. In this work, a composite membrane using modified poly vinyl alcohol (PVA) as the active separating layer, and poly–acrylonitrite (PAN) as a supportive layer was employed. Two membrane processes, pervaporation (PV) and vapor permeation (VP) system, were investigated for their dehydration performances in order to produce motor fuel grade ethanol (MFGE). The effects of feed temperature, feed pressure, feed composition, module temperature, and permeate pressure were compared for both systems, and also discussed in detail. Total flux, ethanol flux, and water flux as well as separation factor were also calculated. In general for both systems, the water fluxes decreased dramatically as the feed side ethanol concentrations increased. However, the pervaporation system was affected the most, and this is because of the low diffusivity of water in ethanol. For the separation of azeotrope, water fluxes between 0.06–1.17 kg/m2/hr with separation factor of about 100 were observed in VP whilst the value of 0.10–0.22 kg/m2/hr were obtained with PV. In conclusion, VP has advantages over PV system in terms of separation performances and simplicities of the process.