Thermal Design of Supercritical Water Oxidation Reactors

2002 ◽  
Author(s):  
S. N. Rogak ◽  
M. S. Khan ◽  
I. Vera-Pe´rez
Keyword(s):  
Heat Transfer ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Flow Reactor ◽  
Inorganic Compounds ◽  
Pure Water ◽  
Thermal Design ◽  
Water Model ◽  
Supercritical Water Oxidation ◽  
Treated Effluent

Waste destruction using supercritical water oxidation (SCWO) was demonstrated in laboratories in the early 1980’s and in full-size facilities by the early 1990’s. The process offers thorough destruction of toxins in a compact facility without supplementary energy. Early estimates that SCWO could auto-thermally treat wastewaters with as little as 2% weight organic ignored some practical factors, such as corrosion, fouling, heat transfer limitations. In this paper, a thermal model for a SCWO system based on pure water properties and heat transfer correlations is used to estimate heat exchanger size and frictional pressure losses. Information on real mixtures at SCWO conditions is not established to the point needed for rigorous thermal modeling, but the pure-water model can be interpreted using real-fluid properties and experience from operating SCWO systems. It is shown that the waste composition has a direct influence on the SCWO design. Auto-thermal treatment of dilute streams (2% organic) is economic only if inorganic compounds are absent from the waste stream or treated effluent, and the plant is of moderate size. For more corrosive wastes, or those with fouling agents, it becomes very expensive to preheat the feed beyond the critical temperature. Without preheating to supercritical temperatures, some back-mixing of hot products is needed to stabilize reaction, so that plug-flow reactor designs become inappropriate.

An inclined plug-flow reactor design for supercritical water oxidation

2018 ◽  
Vol 343 ◽  
pp. 351-361 ◽  
Author(s):  
Zhong Chen ◽  
Hongzhen Chen ◽  
Xiaoling Liu ◽  
Chunlan He ◽  
Datian Yue ◽  
...  
Keyword(s):  
Supercritical Water ◽  
Water Oxidation ◽  
Flow Reactor ◽  
Plug Flow ◽  
Reactor Design ◽  
Plug Flow Reactor ◽  
Supercritical Water Oxidation

Effect of Buoyancy on Heat Transfer in Supercritical Water Flow in a Horizontal Round Tube

2005 ◽  
Vol 127 (8) ◽  
pp. 897-902 ◽  
Author(s):  
Majid Bazargan ◽  
Daniel Fraser ◽  
Vijay Chatoorgan
Keyword(s):  
Heat Transfer ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Local Heat Transfer ◽  
Heat Fluxes ◽  
Supercritical Water Oxidation ◽  
Transfer Coefficients ◽  
Horizontal Pipe ◽  
Free Region ◽  
Wide Range

Heat transfer to supercritical water and buoyancy∕natural convection effects are becoming increasingly important areas of research due to current trends in nuclear reactor design and supercritical water oxidation facilities. A pilot-scale supercritical water oxidation loop was constructed at the University of British Columbia. For this work, the facility was used to study the relative importance of buoyancy effects on supercritical water flowing in a horizontal pipe. Local heat transfer coefficients at the top and bottom surfaces of the horizontal test section were systematically measured over a wide range of conditions at supercritical pressures between 23 to 27 MPa, uniform heat fluxes were up to 310kW∕m2, and the mass flux ranged from 330 to 1230kg∕m2s. It was found that neglecting buoyancy effects could cause large discrepancies between the predictions of available empirical correlations and the experimental data. The data was used to assess available criteria for the buoyancy-free region during horizontal supercritical fluid flows. The criterion of Petukhov and Polyakov, which, for the range of parameters in this study, was found to be accurate in predicting the onset of buoyancy effects. The experimental investigation is confined to supercritical flows with heat addition only. Hence, no heat loss conditions at supercritical temperatures were investigated.

Simulation of Supercritical Water Oxidation with Air at Pilot Plant Scale

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Belén García Jarana ◽  
Jezabel Sánchez Oneto ◽  
Juan Ramón Portela Miguélez ◽  
Enrique Nebot Sanz ◽  
Enrique J. Martínez de la Ossa
Keyword(s):  
Kinetic Parameters ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Pilot Plant ◽  
Reaction Kinetic ◽  
Pure Water ◽  
Kinetic Equations ◽  
Pilot Scale ◽  
Laboratory Scale ◽  
Supercritical Water Oxidation

Supercritical Water Oxidation (SCWO) processes have been studied by numerous researchers. The effectiveness of this approach to treat a wide variety of wastes has been proved and the kinetics involved in some cases have been described. Phenol is commonly present in industrial wastewaters and it is extremely toxic. Hence, phenol is a model pollutant that has been the subject of numerous studies by SCWO on a laboratory scale. In this work, a pilot-scale SCWO system has been used to compare experimental and predicted conversions in the SCWO of phenol, using the reaction kinetic equations obtained at the laboratory scale. In this context, “PROSIM PLUS” software was employed to develop a simulator for the pilot plant facility, with the reaction kinetic parameters adjusted to represent the experimental data. In this study it was necessary to determine the thermal losses between the experimental reactor and its surroundings. These thermal losses were obtained from tests with pure water and oxidant streams in the absence of chemical reaction. An equation that predicted the effect of flow rate and temperature on the thermal losses was used. Experimental oxidation tests were conducted with initial temperature in the range 380 to 425 ºC, at 250 bar and phenol concentrations ranging from 1 to 12 g/l. Good agreement in the simulation was obtained by adjusting the kinetic parameters within their confidence range. This simulator was used to optimize the SCWO of phenol solutions in the pilot plant facility.

Supercritical water oxidation of quinoline in a continuous plug flow reactor—part 2: kinetics

2006 ◽  
Vol 81 (6) ◽  
pp. 919-926 ◽  
Author(s):  
Lisete DS Pinto ◽  
Luisa M Freitas dos Santos ◽  
Regina CD Santos ◽  
Bushra Al-Duri
Keyword(s):  
Supercritical Water ◽  
Water Oxidation ◽  
Flow Reactor ◽  
Plug Flow ◽  
Plug Flow Reactor ◽  
Supercritical Water Oxidation

Phosphate recovery from sewage sludge in combination with supercritical water oxidation

2003 ◽  
Vol 48 (1) ◽  
pp. 185-190 ◽  
Author(s):  
K. Stendahl ◽  
S. Jäfverström
Keyword(s):  
Sewage Sludge ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Organic Contaminants ◽  
Sodium Phosphate ◽  
Pure Water ◽  
Phosphate Solution ◽  
Supercritical Water Oxidation ◽  
Digested Sludge ◽  
Sodium Phosphate Solution

Supercritical Water Oxidation (SCWO) is an innovative and effective destruction method for organics in sewage sludge. The SCWO process leaves a slurry of inorganic ash in a pure water phase free from organic contaminants, which opens possibilities for a simple process to recover components like phosphates from the sewage sludge. In a continuous pilot plant for the SCWO process digested sludge has been treated. The ash has been extracted in lab scale with both caustic and acids in order to recover phosphates. By leaching the ash with caustic, 90% of the phosphorus could be separated as a sodium phosphate solution. By treating the sodium phosphate solution with lime, calcium phosphate was precipitated and caustic recovered and circulated back to the leaching process.

Kinetics of Ethylenediamine Wastewater Oxidation in Supercritical Water

2012 ◽  
Vol 531 ◽  
pp. 516-519 ◽  
Author(s):  
Jia Ming Zhang ◽  
Chun Yuan Ma
Keyword(s):  
Residence Time ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Flow Reactor ◽  
Plug Flow ◽  
Excess Oxygen ◽  
Supercritical Water Oxidation ◽  
Kinetics Equation ◽  
First Order ◽  
Kinetics Of

The decompositon of ethylenediamine (EDA) in supercritical water oxidation (SCWO) were investigated. The experiments were conducted in an isothermal and vertical continuous plug-flow reactor at 375-500°C, 25 MPa, residence time of 2-80 s, and excess oxygen of 150%. It was found that yields of nitrous oxide, nitrogen, and the denitrification rate increased as temperature and residence time increased. The kinetics for denitrification of EDA was described by a rate law involving first order reaction. The results calculated from kinetics equation reconciled the experimental data.

scholarly journals Supercritical water oxidation for the destruction of hazardous waste: better than incineration

2015 ◽  
Vol 373 (2057) ◽  
pp. 20150013 ◽  
Author(s):  
Bushra Al-Duri ◽  
Faihan Alsoqyani ◽  
Iain Kings
Keyword(s):  
Supercritical Water ◽  
Water Oxidation ◽  
Isopropyl Alcohol ◽  
Flow Reactor ◽  
Plug Flow ◽  
Reaction Medium ◽  
Supercritical Water Oxidation ◽  
Split Ratio ◽  
N Removal ◽  
Better Than

Supercritical water oxidation (SCWO) is an advanced process mainly employed for the treatment of hazardous stable wastes, otherwise treatable by incineration. It is based on the unique properties of water above its critical point ( T c =675 K, P c =22.2 MPa), making it a superior reaction medium for the destruction of all organics in the presence of oxygen. This work presents preliminary laboratory scale studies on SCWO of nitrogen (N)-containing hazardous hydrocarbons, with a view to enhancing the process performance, using available reagents and non-complex reactor design. This article investigates the destruction of dimethylformamide (DMF), carried out in a continuous (plug flow) reactor system. SCWO of DMF was enhanced by (i) a split-oxidant system, where stoichiometric oxidant was divided between two inlet ports at various ratios and (ii) the addition of isopropyl alcohol (IPA) as a co-fuel, premixed with the feedstock. Testing a range of temperatures, initial DMF concentrations, oxidant ratios, IPA ratios and oxidant split ratios, selected results were presented in terms of % total organic carbon and % N removal. Reaction kinetics were studied and showed a dramatic decrease in the activation energy upon adding IPA. Split-oxidant-feeding enhancement depended on the split ratio and secondary feed position.

Treatability of Phenol by Supercritical Water Oxidation

2011 ◽  
Vol 422 ◽  
pp. 462-465
Author(s):  
Hui Li ◽  
En Zhao
Keyword(s):  
Supercritical Water ◽  
Water Oxidation ◽  
Continuous Flow ◽  
Flow Reactor ◽  
Reaction Times ◽  
Supercritical Water Oxidation ◽  
Continuous Flow Reactor ◽  
Organic Destruction ◽  
Water Conditions ◽  
Phenol Wastewater

This study focused on the treatment of phenol wastewater by supercritical water oxidation(SCWO). Tests were conducted by using a continuous-flow reactor system. Based on COD, organic destruction efficiencies of phenol wastewater were obtained at supercritical water conditions. Temperatures and pressures, respectively, ranged from 400-500°C,and 25-40Mpa. The reaction times varied from 30 to 190 seconds, and hydrogen peroxide was used as oxidant. Under SCWO conditions, destruction efficiencies greater than 99% were achieved.

scholarly journals Supercritical Water Oxidation of 3-Methylpyridine with Propylene Glycol

2021 ◽  
Vol 33 (7) ◽  
pp. 1573-1578
Author(s):  
Falah Kareem Hadi Al-Kaabi ◽  
Bushra Al-Duri ◽  
Iain Kings
Keyword(s):  
Propylene Glycol ◽  
Removal Efficiency ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Isopropyl Alcohol ◽  
Flow Reactor ◽  
Hydroxyl Groups ◽  
Supercritical Water Oxidation ◽  
Toc Removal ◽  
Positive Effect

The destruction of 3-methylpyridine by supercritical water oxidation (SCWO) using propylene glycol (PG) and isopropyl alcohol (IPA) as co-fuels in a plug flow reactor was carried out. Hydrogen peroxide was the oxygen source. All the experiments were carried out at 25 MPa and a range of temperatures from 425-525 ºC. The residence times range from 6 s to 14 s. Results were presented in terms of total organic carbon (TOC) as a function of time with various process parameters. The findings support the positive effect that propylene glycol has on the destruction of 3-methylpyridine, where TOC removal is ≥ 97.5% at 525 ºC and 14 s. The maximum TOC removal efficiency is 93% at 425 ºC, 14 s, and the [propylene glycol]/[3-methylpyridine]o ratio of 3. The removal efficiency of nitrogen in the presence of propylene glycol reaches 89% at 525 ºC and 10 s. The oxidant ratio also has a positive effect on the removal of TOC in the three systems. Addition of propylene glycol causes a significant development in the ratio at 425 ºC, more so than when isopropyl alcohol was added. This is due to two hydroxyl groups in propylene glycol oxidation that enhance the reaction by generating various free radicals.

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