Review of Supercritical Hydrothermal Combustion

Haitao Xu,Mengmeng Ren,Chengchao Cui,Jie Zhang,Jianqiao Yang,Shuzhong Wang,Yanhui Li,Y Guo

doi:10.1051/e3sconf/20198301002

Haitao Xu, Mengmeng Ren + Show 6 more

Open Access

https://doi.org/10.1051/e3sconf/20198301002

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Abstract

Two major points in supercritical hydrothermal combustion were reviewed:(1) The structure of semi-batch reactors or continuous reactors used in different institutes and colleges. These investigations can be used to guide the design of reactors for later scholars and lay the foundation for the industrialization of supercritical hydrothermal combustion. (2) The research status of characterization of hydrothermal flame processes by various scholars. These investigations can be used to guide the process parameters of industrialization of supercritical hydrothermal combustion. The continuous reactor designed in each organization is very sophisticated, which can avoid the two major problems of reaction in the supercritical state: salt precipitation and corrosion. The ignition temperature, extinction temperature, and other characteristics of supercritical hydrothermal combustion studied by scholars are summarized and the laws are basically similar. The removal rate of different organic matters was also summarized under supercritical hydrothermal combustion, and the removal rate of more than 99% was basically achieved.

Highlights

Supercritical water(SCW) refers to water in the environment where both temperature and pressure are above its critical point(T>374°C, P>22.1MPa)
The continuous reactor designed in each organization is very sophisticated, which can avoid the two major problems of reaction in the supercritical state: salt precipitation and corrosion
The removal rate of different organic matters was summarized under supercritical hydrothermal combustion, and the removal rate of more than 99% was basically achieved

Summary

Introduction

Supercritical water(SCW) refers to water in the environment where both temperature and pressure are above its critical point(T>374°C, P>22.1MPa). Zhang[5] believes that supercritical hydrothermal combustion occurs when the temperature of fluid in the reactor rises sharply (at least 100 °C /min). Augustine[6] believes that the hydrothermal flame which operates in a regime of thermal runaway has the features of extremely fast reaction rates(with residence times being only 10–100ms) and high temperatures(usually more than 1000 °C). The temperature in the local high temperature zone possessed by supercritical hydrothermal combustion is higher than that of the flameless supercritical water, so the ability to destroy refractory organic matter is stronger. Scholars' research on supercritical hydrothermal combustion focuses on flame characteristics: ignition temperature, extinction temperature, flame temperature, flame height (diameter), the total organic carbon (TOC) removal rate of organic matter or waste and the design of the reactor

Reactor designed by different organization

Semi-batch reactor

Characterization of hydrothermal flame processes

Destruction efficiency

Findings

Conclusion and outlook