Methods of utilizing boiler blowdown for reducing NOX

Abstract

The present invention provides improved methods of reducing NOx emissions in the flue gases produced by a steam boiler fired by a fluid fuel and combustion air burner and including a steam drum provided with make-up water from which produced steam and blowdown steam are withdrawn. In accordance with the invention at least a portion of the blowdown steam is combined with the fluid fuel or combustion air or both.

Description

[0001] 1. Field of the Invention[0002] This invention relates to improved methods of reducing NO.sub.x emissions produced by a steam boiler fired by a fluid fuel and combustion air burner.[0003] 2. Description of the Prior Art[0004] Packaged unit and other steam boilers which are fired by fluid fuel and combustion air burners are commonly used in chemical and other process installations. Such boilers include a steam drum which is provided with feed water and from which produced steam is withdrawn. In order to maintain the appropriate total dissolved solids in the boiler water and avoid scale formation, blowdown steam is withdrawn from the steam drum. The blowdown steam flow depends on the feed water quality and typically amounts to in the range of from about 1.5 to about 5% of the total steam produced by the boiler. The blowdown steam is released to the atmosphere or used to preheat the feed water and then released to the atmosphere.[0005] In order to reduce the NO.sub.x emissions p...

AI Technical Summary

Benefits of technology

This approach effectively reduces NOx emissions while maintaining boiler efficiency and avoiding the need for additional make-up water, improving net thermal efficiency by approximately 20% and allowing for flexible control of emission reduction through trial and error adjustments.

Problems solved by technology

This usage of process steam lowers the efficiency of the boiler or requires additional make-up water which increases the cost of operating the boiler.

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