Diffuser plate for boiler burner feed assembly

Abstract

A diffuser or orifice plate is positioned across the bore of a feed pipe supplying a mixture of pressurized air and recycled flue gas to the combustion chamber of a gas burner associated with a boiler. The diffuser plate comprises inner and outer, radially spaced apart, annular baffles. The baffles define a central opening and an outer series of openings forming an annular array. Part of the gas mixture is accelerated as it passes through the restrictive outer openings and forms an annular stream. Part of the gas mixture passes through the central opening in the form of a lance-like stream. Fuel gas is injected into the annular stream immediately downstream of the diffuser plate. The resulting air / flue gas / fuel gas mixture mixes and adopts an elongated form in the combustion chamber. The burner feed assembly described contributes to maintaining the Ox content in the burner flue gas at a low level such as less than 15 ppm.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a burner feed assembly incorporating a diffuser plate. The burner feed assembly is used in connection with the burner of a boiler, such as a boiler used in an oilfield operation for generating steam. The diffuser plate assists in mixing air, recycled flue gas and fuel gas being fed to the burner combustion chamber. BACKGROUND OF THE INVENTION [0002] Boilers are commonly used in oilfield operations. These boilers are usually provided to generate steam. [0003] The burners in these boilers produce flue gases, which are commonly emitted into the atmosphere. The flue gases comprise NOx compounds. The production of these NOx compounds is environmentally undesirable. They can react to form ground-level ozone and nitrates, which can trigger respiratory problems in humans. They also contribute to the formation of acid rain. And nitrous oxide contributes to the formation of ‘greenhouse’ gases in the atmosphere. [0004] Governments ...

AI Technical Summary

Benefits of technology

[0021] It is believed that the upstream surfaces of the annular baffles deflect part of the air / flue gas mixture flow moving through the feed pipe and cause it to move through the arcuate openings, which constrict and accelerate it, thereby inducing a venturi effect which assists in entraining the fuel gas being injected inwardly, immediately downstream of the plate. In addition, it is believed that the lance-like flow through the central opening has the effect of causing the flame produced in the burner chamber to elongate, which contributes to reducing flame temperature.

Problems solved by technology

The production of these NOx compounds is environmentally undesirable.

They can react to form ground-level ozone and nitrates, which can trigger respiratory problems in humans.

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