Exhaust gas treatment method and apparatus
AssigneeHeat Exchanger Industries, Inc.
InventorDonald F. Warner
Life of this patent
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Abstract
Exhaust gas treatment method and apparatus extract heat from an exhaust gas by operating in a water-condensing mode which allows more heat to be recovered, removes particulate matter and condensed acid from the exhaust gas, and washes heat exchange surfaces to keep them clean and wet to improve heat transfer. Systems for heating water, air, and both water and air are disclosed. Methods of constructing and assembling improved heat exchangers are disclosed.
Claims33
The method of recovering heat energy contained in a hot exhaust gas containing water vapor and sulfur trioxide combinable in part to form sulfuric acid, and of simultaneously removing substantial amounts of said sulfur trioxide from the exhaust gas, which comprises the steps of:
- passing said exhaust gas in heat exchange flow relationship generally perpendicularly to and between generally horizontally extending tubes of a tube nest having a plurality of tube groups;
- and simultaneously passing a fluid to be heated through successive tubes of said nest in counterflow relationship to said exhaust gas flow, the flow rate of said exhaust gas being established in relation to the input temperature and flow rate of said fluid and the heat exchange surface area of said nest so that the temperature of said fluid within a first group of said tubes remains substantially below the water vapor dewpoint of said exhaust gas, thereby transferring a substantial portion of the latent heat energy in said hot exhaust gas to said fluid and causing continuous substantial condensation of water from said exhaust gas and a continuous fall of water droplets from tubes of said first group through said exhaust gas to the tubes of a lower tube group, whereby said water droplets entrap and dilute sulfuric acid as they fall from said tubes of said first group through said exhaust gas, and said water droplets wash sulfuric acid from said tubes of said lower group, the exterior surfaces of said tubes of said tube nest being covered with coverings which both shield said tubes from sulfuric acid and promote dropwise condensation.
The method of recovering heat energy from a hot exhaust gas which initially contains water vapor condensable at a water vapor dewpoint and a corrosive constituent condensable at a temperature above said water vapor dewpoint, and of recovering latent heat while preventing corrosion from condensation of said corrosive constituent, comprising the steps of:
- passing said exhaust gas in a flow generally perpendicularly to and between tubes of a tube nest having upper and lower groups of tubes;
- and simultaneously passing a fluid to be heated through successive tubes of said tube nest in counterflow relationship to said gas flow, the amount of said exhaust gas being passed through said tube nest being established in relation to the heat exchange surface area of said tube nest and the input temperature and flow rate of said fluid, and the initial temperature of said fluid being sufficiently below said water vapor dewpoint so that substantial condensation of water vapor continuously occurs, the exterior surfaces of said tube nest being covered with coverings which both shield said tubes from condensed corrosive constituent and provide dropwise condensation of water droplets, so that said droplets may drop from tubes of said upper group through said exhaust gas to tubes of said lower group to wash condensed corrosive constituent from tubes of said lower group, and to dilute the condensed corrosive constituent.
Dependencies are inferred from the claim text.