Flameless thermal oxidation apparatus and methods

Abstract

A thermal oxidizer is provided in which off-gases in a process stream are thermally oxidized within substantially the entire interior volume of an oxidation chamber. The thermal oxidation is conducted without the presence of a flame or with only a minor portion of one or more fuels being combusted in a flame.

Description

RELATED APPLICATIONS[0001]This application is a continuation-in-part of U.S. patent application Ser. No. 11 / 945,775 filed on Nov. 27, 2007. The disclosure of the aforementioned application is incorporated by reference herein in its entirety.BACKGROUND OF THE INVENTION[0002]This invention relates generally to thermal oxidizers used to oxidize organic compounds in process streams and, more particularly, to apparatus and methods of operating such thermal oxidizers using flameless thermal oxidation to decompose the organic compounds.[0003]Thermal oxidizers are commonly used to oxidize one or more gases or vapors in a process stream by subjecting them to high temperatures before the process stream is released to the atmosphere. The gases in the process stream arc commonly referred to as off-gases and typically consist of volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), and / or hazardous air pollutants (HAPs). The process stream containing the off-gases is freque...

AI Technical Summary

Benefits of technology

[0010]In one embodiment, one or more fuel components in the fluid stream are combusted in a visible flame to cause the initial heating of the refractory lining to the preselected temperature. The overall concentration of the fuel components in the fluid stream can be within the flammability range during this startup mode. Alternatively, the overall concentration of the fuel components is outside of the flammability range, but a flammable mixture results by not completely mixing the fuel components with the combustion air which is present in the fluid stream so that a diffusion or partially premixed flame results. During the transition to the flameless thermal oxidation mode, the flame in the fluid stream is extinguished, such as by increasing the mixing of the fuel and combustion air to move the localized concentrations of the fuel components outside of the flammability range to prevent combustion of the mixture in a visible flame within the burner. Other methods for changing the localized concentrations of the fuel components outside of the flammability range can be used.

Problems solved by technology

The use of a flame to cause thermal decomposition of compounds in thermal oxidizers, however, often results in the production of objectionable levels of air pollutants such as NOx and CO.

The bed matrix, however, occupies a substantial portion of the internal volume of the process reactor, thereby reducing the open volume available for the flow of the process stream.

In addition, the bed matrix creates a substantial pressure drop that adds to the operating costs of the process because the process stream must be subjected to an increased pressure before it enters the process reactor.

This pressure drop tends to increase over time as particulate matter from the process stream accumulates in the bed matrix or the bed material degrades due to thermal shock.

Eventually, the increase in pressure drop across the bed matrix may require replacement of the bed material.

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