Staged steam waste gas flare

Abstract

A steam flare is provided that injects steam, unmixed with air into a waste gas stream at locations where the resulting accelerated steam and waste gas mixture upon exposure to the surrounding air induces a mixture of steam, waste gas and air with improved combustion and effectively complete destruction of the waste gas, and where under low-flow conditions, reduced steam and / or assist gas are required to maintain smokeless operation. The steam is injected via multiple tubes each controlled independently so that steam can normally be flowed via a first tube, and then, when operation loads require, flowed via a second tube. The first and second tubes may be concentric and may be in communication with steam supplies that have different pressures of steam.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is a Continuation in Part of U.S. Ser. No. 16 / 117,969, filed on Aug. 30, 2018, which claims priority from Provisional Application No. 62 / 559,318 filed Sep. 15, 2017, the contents of both of which are hereby incorporated by reference in their entirety.BACKGROUND OF THE INVENTION[0002]The present invention relates to an improved flare apparatus and more specifically to an efficient steam-assisted flare apparatus.[0003]Steam assisted flares are used in refinery and petrochemical plants for the combustion of high-volume releases of waste gases during interruptions of normal plant operation. The “smokeless” capacity is an extremely important operating parameter. High quantities of high-pressure steam is used to entrain atmospheric air and force the mixing of the air with the waste gases. The greater the quantity of air mixed per pound of steam injected with the waste gases the higher the achievable smokeless capacity.[0004]Flar...

AI Technical Summary

Benefits of technology

The invention is a steam flare that includes a flare gas conduit and a steam tube. The steam tube has a plurality of flare gas conduits, each containing a plurality of flare gas conduits. The flare gas conduits have a ring at the top, which may have perforations or other surface features to direct the mixture of waste gas and steam. The flare gas conduit may have a flat plate, cone, or other shape to reduce pressure drop. The steam flare also includes a sensor, flow regulating device, and controller to regulate the steam flow and pressure. The invention provides a steam flare that requires less steam and assist gas to maintain smokeless combustion and increase equipment life at low-flow operating conditions.

Problems solved by technology

First, the relatively small 8-inch diameter nozzles severely limit the quantity of the air that can be entrained by the steam.

Secondly, the steam flow and waste gas flow are essentially parallel which reduces the mixing efficiency.

This causes higher concentrations of waste gas in the center of the tip resulting in incomplete combustion that produces smoke.

However, such flare apparatus may require more steam per waste gas than other steam-assisted flare types, especially at larger sizes; additionally, they may create an excessive amount of noise.

The noise from the lower steam can be muffled, while the noise from the upper steam is difficult or impractical to muffle due to its vicinity to the flare flame.

A muffler for the lower steam not only adds to the costs, but also increases the wind load of the flare stack, resulting in increased flare stack costs.

With many steam-assisted flares, the steam and steam / air mixtures are introduced to the waste gas fairly uniformly, whereas the waste gas can exit the flare non-uniformly with higher wind, requiring higher steam and / or assist gas utilities to maintain smokeless combustion.

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