Review of Supercritical Water Oxidation in Hydrothermal Flames

Abstract

Supercritical water oxidation in hydrothermal flames is a promising method for the total destruction of refractory compounds because it can overcome corrosion and salt deposition problems. In case of wastewater with a low reaction heat, the use of auxiliary fuels, to increase the reaction heat for the auto thermal operation is necessary. Methanol and isopropyl-alcohol were usually used as fuels. This paper compares the two fuels in hydrothermal flames and reviews the experimental results of salts, acetic acid, dioxins, ammonia, sludge and phenols of naphthalene and toluene. The results show that the destruction process obtains high TOC removals, and phenols are easy to cause soot formation problems. If soot deposition problems can be solved, supercritical water oxidation in hydrothermal flames will have a bright prospect for commercial applications.

Supercritical Water Oxidation for Environmentally Friendly Treatment of Organic Wastes

“…The center pipe is set on a fixed platform by screw thread, which is easy to be replaced when plugged or eroded severely. Generally, the traditional transpiring wall reactor is a tubular reactor with a hydrothermal burner [69,73,74]. However, no hydrothermal burner is set in TWM reactor in order to decrease design temperature of reactor and operation cost of sewage sludge SCWO treatment.…”

Ignition of hydrothermal flames

“…12 Among all organics investigated, methanol and isopropanol have received most attention. 14 The choice of the fuel for hydrothermal ame depends on its solubility with water at room temperature, ammability, optimal auto-ignition conditions, high heating value, low cost, and safety to handle. The organic component should be soluble in water to avoid two-phase pumping of uids into the reactor.…”

“…Hydrothermal ame oxidation has the potential to degrade a broad range of wastes from different application sectors including extended duration and/or extraterrestrial space missions; waste disposal from nuclear energy plants; municipal wastes (e.g., sewage sludge); and biomedical wastes (particularly from the pharmaceutical industries). 14,15 Various parameters inuence the ignition of hydrothermal ames, which further impacts the SCWO process. The commercialization of SCWO technology can be attained for broad-ranging applications only when the effect of process parameters on ignition and continuous production of hydrothermal ames is well understood.…”

“…In addition, this emerging area of research has only two comprehensive reviews so far. Recent reviews by Augustine and Tester 12 and Qian et al 14 have outlined some applications and experimental investigations on hydrothermal ames. There is very little literature available on the impact of various ame parameters (e.g., reactant ow rates, reactant concentration, process temperatures, etc.)…”

Supercritical Water Oxidation Using Hydrothermal Flames at Microscale as a Potential Solution for Organic Waste Treatment in Space Applications – a Practical Demonstration and Numerical Study

“…While some organic matter may be able to generate sufficient heat to autoignite, such as quinoline [7], in situations wherein organic water or wastewater may have a low heating value, a small amount of auxiliary fuel (usually methanol or isopropanol) is added to achieve auto thermal operation. In situations wherein organic water or wastewater may have a low heating value, a small amount of auxiliary fuel (usually methanol or isopropanol) is added to achieve auto thermal operation [8,9]. It is to be mentioned that the organic matter and oxygen present in the homogeneous medium (water) are always reacting and thus, heat is being consistently generated.…”