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Impact of oxygen enrichment in a bagasse/bio-mass boiler

IP.com Disclosure Number: IPCOM000028165D
Publication Date: 2004-Apr-29
Document File: 4 page(s) / 45K

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The IP.com Prior Art Database

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Impact of oxygen enrichment in

a bagasse/bio-mass boiler

Summary:

Bagasse is a by-product of sugar manufactured from sugar cane.   Bagasse is a low-BTU fuel, containing around and in excess of 50% water.  Bagasse is ordinarily burned in boilers for steam/power production.  Bagasse is generally stored outside,  and therefore its properties are dependent on many parameters including weather.  Oxygen enrichment can significantly assist the combustion process, by increasing the fuel-heat conversion, the boiler efficiency, reduce the excess air, etc.  This ID shows ways to utilize the beneficial impact of oxygen in such a boiler, or more generally in a bio-mass boiler.

                    The use of bagasse for steam generation is common for sugar producers.  Bagasse is a fuel, and its use serves as recycling as well.  The drawback is its relatively low carbon content, together with a large water content – around and above 50%, greatly varying in time as the bagasse is generally stored outside.  Finally, the long period of storage (a few months) in the elements makes the bagasse properties vary significantly in time.

During normal operation, the CO emissions together with the unburnt carbon could amount to losses up to 10% from the already modest fuel heating value (HHV around 3650 Btu/lb).  In order to maintain and improve the burner operation, a large excess air is used, usually in excess of 50%.  This further diminishes the boiler efficiency due to thermal losses and increased fan power.  At the same time, the heat input is limited due to the high flue gas volume. 

This ID suggests improvements in the boiler operation through the use of oxygen enrichment.  Thus, oxygen will have the following impact on the operation:

v     Will create ignition sources in the mass of bagasse, which will therefore burn quicker and more complete.  By starting the combustion process faster, the bagasse will have an increased amount of time to heat, allowing the water to quicker vaporize and leave the fuel bed, and thus permit it to burn more efficiently.  It is considered that the carbon oxides, and the carbon monoxide will be converted into carbon dioxide in a significantly larger proportion.

v     Will allow to use significantly less excess air, reduced to around 15-25% from 50-70% currently.  This has certain advantages, such as reduced fan power, increased overall efficiency, increased temperature of the preheated air, thus further aiding the combustion process and efficency.

v     Will allow to increase the boiler productivity, as the heat inp...