Thermal Distillation Process Research Articles

Benchmarking produced water treatment strategies for non-toxic effluents: Integrating thermal distillation with granular activated carbon and zeolite post-treatment

The management of produced water (PW) generated during oil and gas operations requires effective treatment and comprehensive chemical and toxicological assessment to reduce the environmental risks associated with reuse or discharge. This study evaluated a treatment train that included a low-temperature thermal distillation pilot system followed by granular activated carbon (GAC) and zeolite post-treatment for processing hypersaline Permian Basin PW. Our study provides a unique and comprehensive assessment of the treatment efficiency considering a targeted chemical scheme together with whole effluent toxicity (WET) tests across four trophic levels regarding aquatic critical receptors of concern (ROC): Raphidocelis subcapitata, Vibrio fischeri, Ceriodaphnia dubia, and Danio rerio. The distillate from the thermal distillation process met various numeric discharge standards for salinity and major ions. However, it did not meet toxicity requirements established by the United States National Pollutant Discharge Elimination System program. Subsequent post-treatment using GAC and zeolite reduced the concentration of potential stressors, including volatile organics, NH3, Cd, Cr, Zn, and Mn in the final effluent to below detection limits. This resulted in a consistent toxicity reduction across all WET tests, with no observable adverse effects for R. subcapitata, C. dubia, and D. rerio (no observed effect concentration >100%), and V. fischeri effects reduced to 19%. This study realizes the feasibility of treating PW to non-toxic levels and meeting reuse and discharge requirements. It underscores the importance of implementing integrated treatment trains to remove the contaminants of concern and provides a systematic decision framework to predict and monitor environmental risks associated with PW reuse.

Thermal crosslinking and cyclodehydration assisted fabrication of chemically robust thin-film composite (TFC) membranes for ultrafast polar solvents filtration

Organic solvent nanofiltration (OSN) offers an energy-efficient alternative to conventional thermal distillation processes for organic solvent separations. However, the fabrication of polymeric OSN membranes with adequate chemical stability in strong polar aprotic solvents remains a remarkable challenge. In this work, chemically robust polyamide thin-film composite (TFC) OSN membranes were fabricated by utilizing an innovative chemical modification of polyimide (PI) nanofiber substrate via one-step crosslinking and thermal cyclodehydration of terephthalic hydrazide (TPDH). The crosslinking and cyclodehydration reaction mechanisms were thoroughly elucidated and the effects of TPDH loading and thermal treatment conditions on solvent resistance and pore structure of the resulting TPDH/PI nanofiber substrates as well as the formation of the polyamide selective layer were systematically studied. The resulting TFC membranes show excellent stability in polar aprotic solvents (i.e., DMF, DMAC, and NMP), and a high DMF permeance of 9.4 L m−2 h−1 bar−1 was achieved with a 99.8% rejection to Rose Bengal at 2.0 bar. The outstanding long-term performance stability revealed the robust structure of the developed TFC OSN membranes. This work demonstrates a facile strategy to address the chemical stability limitations of TFC OSN membranes through a multifaceted yet generalizable approach of chemical crosslinking and thermal cyclodehydration. We believe this strategy can be broadly applied to different substrates, enabling TFC membranes to address a wide variety of unmet OSN needs.

Design and modeling of vertical tube evaporator in a thermal-driven multiple effect distillation system

Abstract The scarcity of freshwater is one of the biggest issues in the world, as a result of which more attention is given to the thermal distillation process for seawater and as well as brackish water distillation which removes almost all types of contaminants. Multiple effect distillation makes the process economical by recycling the latent heat of vaporization. In this paper a vertical tube evaporator is designed for a small scale thermal driven MED system comprising six effects and one condenser and a boiler that can produce 20–25 kg/hr of steam. VTE dimensions are calculated by estimating the outside diameter for different configurations. Heat transfer coefficient was estimated by using the developed correlations of the Bell method, Kandlikar and Kutateladze, compared with previous experiments and then used for calculating the heat transfer area for different distillate flow rates. An appropriate vertical tube evaporator is designed with the developed model to condense 25–30 kg/hr steam for producing 50–75 lt/hr freshwater. The result shows good agreement with previous work and reliability in design. The Developed model can also be used to design the vertical tube evaporator for different sizes (micro scale to large scale) MED plant.

Impact study of thermal distillation process on absorption refrigerators

Impact study of thermal distillation process on absorption refrigerators

Energy saving in distillation by combining vortex contact device and thermal effects

• Energy efficiency assessment of the thermal distillation in the column apparatuses is presented. • Heat extra removed from the upper tray of the column leads to a decrease in heat flows by 9–12%. • Vortex contact devices provide an increase in the mole fraction of the light-volatile component in the liquid by 5.61%. Thermal effects are proposed to improve the efficiency of heat and mass transfer phenomena in distillation columns. The new design of the vortex contact device is developed. The paper investigates a combined use of the vortex devices that act as the contact stages of the distillation column and heat removal from the upper contact stage. Theoretical results on the distribution of vapor and liquid flows on each tray of the vortex device are obtained. The mass flow rate of the liquid phase as a result of the partial condensation of vapors is determined based on the amount of heat removed and the location of the tray with additional heat removal. A reduction in the mass flow rate of reflux during thermal distillation is experimentally established. The dependence of the average Murphree tray efficiency of the vortex contact stage is obtained depending on the reflux ratio at thermal distillation, which is confirmed experimentally. Experimental study shows an increase in the average efficiency of the stage by 10.6% compared to the adiabatic column without heat removal. A distillate mass fraction of 0.884 in the liquid phase is achieved at the outlet of the column when using 10 vortex contact stages and the working reflux ratio of 1.83. The comparative analysis of the use of the developed vortex contact devices in the thermal distillation process is performed in terms of the separation quality of the ethanol–water mixture, energy costs for the supply, and removal of heat.

Setting up of a cost-effective continuous desalination plant based on coupling solar and geothermal energy

The aim of the work was to describe and test a solar desalination system for salt and brackish water desalination considering a real application, in order to provide detailed technical features of a future plant based on the calculated data by the modelling approach. The main innovative aspect of the studied solar desalination system consists in reproducing, in a restricted environment, the water cycle that commonly occurs in nature. The process is a thermal distillation process based on a first humidification phase and a second phase of air dehumidification, exploiting, at steady-state conditions, only solar thermal energy, and it is capable to work 24 h day−1. It is built with materials that are commonly used in the building sector, reducing construction costs. The findings have led to a system easily integrable in real scale scenarios to recover fresh water from a solution of salt or brackish water, for both potable uses and process uses. Thanks to these technological solutions, a low specific energy consumption (5.5 kWh m−3 of water) is obtained, envisaging lower running cost.

Evaluation and minimisation of energy consumption in a medium-scale reverse osmosis brackish water desalination plant

The Reverse Osmosis (RO) process has been expansively used in water treatment as a result of its low energy consumption compared to thermal distillation processes, leading to reduced overall water production cost. Evaluation and minimisation of energy consumption (expressed in kWh/m3 of fresh water production) in a medium-scale spiral wound brackish water RO (BWRO) desalination plant of the Arab Potash Company (APC) are the main aims of this research. The model developed earlier by the authors has been integrated to simulate the process and achieve the main aims. Energy consumption calculations of low salinity BWRO desalination plant, with and without an energy recovery device, have been carried out using the gPROMS software suite. In other words, this research evaluated the impact of adding an energy recovery device on the RO process energy consumption of the APC, which is introduced for the first time. Also, the effects of several operating conditions of BWRO process include the feed flow rate, pressure and temperature on the performance indicators, which include the energy consumption and total plant recovery at different energy recovery device efficiencies, were studied. The simulation results showed that the total energy consumption could be reduced at low values of feed flow rates and pressures and high values of temperatures. More importantly, there is an opportunity to reduce the total energy consumption between 47% and 53.8% compared to the one calculated for the original design without an energy recovery device.

Highly effective organic draw solutions for renewable power generation by closed-loop pressure retarded osmosis

An appropriate draw solution selection is a key to successful implementation of closed-loop pressure retarded osmosis (PRO) process for sustainable energy generation. In this study, the organic compounds potassium citrate, calcium acetate, potassium oxalate, potassium acetate, ammonium acetate, ammonium carbamate, ammonium formate, potassium formate, sodium glycolate, sodium propionate and calcium propionate were identified for the first time as highly effective draw solutions (except for NaP) using an easy desk-top screening method. This method identified these organic compounds by considering physical state at ambient condition, water solubility and osmotic pressure. The draw solutions were comprehensively evaluated for water flux, power density, and reverse salt flux through a laboratory-based investigation of the PRO process. The peak power densities achieved for the identified draw solutions were 5.32–6.73 W/m2 at 2.8 MPa osmotic pressure. These peak power densities increased from 109% to 118% (11.1–14.64 W/m2) when increasing the osmotic pressure of the draw solutions by 50% (4.2 MPa). A significant increase in the peak power density was obtained due to the very low reverse salt flux for the organic draw solutions (0.029–0.0699 mol m−2 h−1 and 0.0325–0.0854 mol m−2 h−1 at osmotic pressures of 2.8 MPa and 4.2 MPa, respectively). The identified organic draw solutions were also analyzed as distillable and thermolytic through gravimetric method, for the identification of potential downstream recovery methods to recycle the draw solutions in the closed-loop PRO process. Membrane distillation could be used as a downstream separator technique for the distillable organic draw solutions; however, only the ammonium carbamate among the thermolytic compounds could be separated downstream by using a low-temperature thermal distillation process.

Irreversibility analysis of the absorption heat transformer coupled to a single effect evaporation process

An absorption heat transformer integrated to a desalination system based on a thermal distillation process is simulated from the point of view of the first and second laws of the thermodynamics. Three possible configurations were proposed in the literature in order to transfer the sensitive and latent heats from the desalination process to the absorption heat transformer to improve the coefficient of performance. The performance of the systems was analyzed as a function of the evaporator, generator, condenser temperatures and the main heat exchanger effectiveness, as well as the salinity of seawater. From the exergy analysis, it was clear that the highest irreversibility was obtained in the generator and absorber for all the configurations evaluated in this work. It was found that the lowest values of total irreversibility were estimated for the configuration 1 where sensitive heat was transferred from the distillation process to the strong-working solution, which goes to the absorber.

Predicting the influence of operating conditions on DCMD flux and thermal efficiency for incompressible and compressible membrane systems

Membrane distillation (MD) is a hybrid of thermal distillation and membrane separation. As a thermal distillation process, MD is an energy intensive technique. Therefore, it is important to select optimum operation parameters to maximise both the flux and energy efficiency, even though low grade or waste heat maybe employed in the process. In this paper, a model originally developed for Direct Contact Membrane Distillation (DCMD) using a compressible membrane is employed to predict the thermal efficiency and flux for both compressible and incompressible membrane systems. The predicted thermal efficiency was also compared with experimental results, and the errors were mostly within the range of experimental variation (±5%). As a result of membrane compressibility, the thermal conductivity and vapour permeability of the membrane were altered, causing a change in flux and energy efficiency. If a compressible membrane is used, it was found from the predicted results, that increasing stream velocity will reduce the thermal efficiency and even reduce flux once the increased pressure associated with the higher flows is in the range to compress the membrane. Increasing temperature either on feed side or on permeate side will increase thermal efficiency. In scaling up the process using a compressible membrane, it is necessary to reduce the pressure drop across the module in the DCMD process to maximise energy efficiency and flux. Since the operating temperature is normally not adjustable when low grade waste heat is employed, optimising the flowrates and pressure drops are the key factors for optimising flux and thermal efficiency.

Advanced MED process for most economical sea water desalination

The low temperature horizontal tube multi-effect desalination (MED) process is thermodynamically the most efficient of all thermal distillation processes. A comprehensive multi-disciplinary development and design approach resulted in prevention of corrosion and scale formation on the plant’s heat transfer surfaces. It also allows the successful and most economical use of aluminum alloys for heat transfer tubes, as well as carbon steel epoxy coated shells for the evaporator body. The ability to use economically low grade heat, such as waste heat, exhaust steam from power station turbines as the primary heat source for MED, yields very low specific energy costs for sea water desalination. Recent developments of very economical low temperature deep pool nuclear heat reactors, when acting as the primary energy source for large MED plants, yield very low specific desalination energy costs. The combination of economical specific MED plant costs with low energy cost, together with the inherent durability of low temperature MED avoiding the necessity of comprehensive sea water pretreatment (such as with RO plants) make the MED process one of the best candidates for safe and durable large capacity economical desalination options. This paper describes the design principles and various energy considerations that result in this uniquely economical MED process and plant. It also provides an overview of various cases of waste heat utilization, and cogeneration MED plants operating for many years.

Evaluation of solar powered desalination processes

Besides the conventional thermal distillation process, other desalination processes have been possible by the application of the active utilization of solar energy. These processes include eletrodialysis, reverse osmosis, freezing, … etc. Undoubtely, solar desalination is considered the best alternative to provide fresh water in remote aird areas. The selection of the appropriate solar desalination process is a unique problem ever done by processes comparison. In this paper, the evaluation of the possible solar desalination processes will be carried. The Arabian Gulf region will be used as a reference for the evaluation study. Comparison with the fossil fuel powered desalination plants will also be presented to justify the recommendation of the selected solar desalination process.