Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture
Reexamination Certificate
1999-10-22
2002-02-05
Griffin, Steven P. (Department: 1754)
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
C423S235000, C423S243010, C422S170000
Reexamination Certificate
active
06344177
ABSTRACT:
DESCRIPTION
This invention relates to a pollution abatement process and pollution abatement device which makes use of misting technology, together with cooling and condensation coils to effect targeted pollutants' removal. It accomplishes these objectives with little wastewater generation and the use of reactants for specific pollutants. The invention eliminates the need for an exhaust stack, creating a huge savings for any facility from reduced stack maintenance costs, elimination of stack replacement costs and the elimination of boiler operations for stack warming.
BACKGROUND OF THE INVENTION
General
According to the Principle of Environmental Control (cited by Marks' Standard Handbook of Mechanical Engineers, Ninth edition), nature has provided two almost inexhaustible sumps for maintaining a steady-state environment on earth. The first of these is the 3 K background temperature of absolute space, which nature uses for heat rejection to close its heat balances. The second is the oceans, which serve to close the material balances of its cyclic processes by accepting the combined runoff of the continents. The greatest engineering progress comes when people control their environmental activities so as to take maximum advantage at minimum cost of these sumps and of nature's cyclic process. This is the basic principle upon which the science of environmental control is founded.
Environmental control seeks to subdue and to utilize nature's ecological cycles in order to serve people's needs, thereby conserving natural energy and mineral resources, and to replenish desirable local flora and fauna populations by agriculture and cultivation to provide adequate food, clothing and shelter. Environmental control seeks to extend depletable fuel supplies with clean, abundant forms of reusable energy. Replenishable substitutes for other depletable resources are sought, as well as recycling means for scarce and irretrievable substances. Environmental control seeks to conserve land, air and water quality by diversion into adequately controlled air dispersion and drainage canals of concentrated runoffs. The public standard of living is highest when all these things are done voluntarily by a responsible, cost-conscious citizenry.
Products of Combustion
The combustion byproducts of hydrocarbon fuels primarily consist of nitrogen (N
2
), carbon dioxide (CO
2
), water (H
2
O), carbon monoxide (CO), unburned hydrocarbons (UHC), oxides of sulfur (SO
x
), particulate (soot) and oxides of nitrogen (NO
x
).
The last five items, CO, UHC, SO
x
, particulate and NO
x
are unwanted and undesirable. These pollutants are referred to as criteria pollutants and many regulatory agencies around the world have established guidelines for their control.
CO is a gas that is an intermediate product of combustion of hydrocarbon fuels.
UHC often results from poor fuel atomization or quenching of the combustion process by the combustion cooling air film or by high levels of water or steam injection.
Oxides of sulfur are formed when sulfur is present in the fuel during combustion. SO
x
forms over a wide range of combustion temperatures and cannot be controlled in the combustion process itself. Hence, SO
x
formation either must be prevented from occurring by limiting sulfur in the fuel or else the SO
x
that is created must be removed from the exhaust stream by wet scrubbing or sorbent injection.
Particulate matter (i.e. soot or smoke) results from the combustion of liquid fuels/air ratios in the combustion primary zone.
NO
x
, by virtually unanimous agreement, is considered a primary contributor to visible pollution and deteriorating air quality. The reduction of NO
x
has become the major focus of air quality regulations throughout the world in efforts to improve air quality around the world.
PRIOR ART TECHNOLOGIES
The present invention was created based on well known and proven technologies as described below.
Economizers
Economizers remove heat from the moderately low-temperature combustion gases after the gases leave the steam generating and superheating/reheating sections of the boiler unit. Economizers are, in effect, feed water heaters which receive water from the boiler feed pumps and deliver it at higher temperature to the steam generator. Economizers are used instead of additional steam-generating surface, since the feed-water and, consequently, the heat-receiving surface, are at temperatures below the saturated-steam temperatures. Thus, the gases can be cooled to lower temperature levels for greater heat recovery and economy.
Economizers are forced-flow, once through conversion heat transfer devices, usually consisting of steel tubes, to which feed-water is supplied at a pressure above that in the steam generating section and at a rate corresponding to the steam output of the boiler unit, they are classed as horizontal or vertical-tube type, according to geometrical arrangement; as longitudinal or cross flow, depending upon the direction of gas-flow with respect to the tubes;- as parallel or counter flow, with respect to the relative direction of gas and water flow; as steaming or non-steaming, depending on the thermal performance; as return-bend or continuous-tube, depending upon the details of design; and as base-tube or extended-surface, according to the type of heat- absorbing surface. Staggered or in-line tube arrangements may be used. The arrangement of tubes affects the gas flow through the tube bank, the draft loss, the heat transfer characteristics, and the ease of cleaning.
The size of an economizer is governed by economic considerations involving the cost of fuel, the comparative cost and thermal performance of alternate steam-generating or air heater surface, the feed-water temperature, and the desired exit gas temperature. In many cases, it is more economical to use both an economizer and an air heater.
Present day practice in individual independent economizers is to install economizers having a surface from 50 to 70% of the boiler heating surface. The main factor affecting heat transfer rates is the gas velocity over the economizer. With the ordinary economizers with gas velocities corresponding to approximately 1500 lb. of gas per square foot (71.700 N/m
2
) of gas passage area per hour through the economizers a transfer rate from 2.5 to 3.0 B.T.U. (2.65 kJ to 3.18 kJ) per hour per square foot (0.09 m
2
) of surface per ° F. (0.56° C.) difference in temperature may be expected. If this velocity is increased to 3000 lb. (143,400 N/m
2
) per hour the rate will be from 3.5 to 4.5 B.T.U. (3.71 kJ to 4.77 kJ). Gas velocities through steel economizers are not high and transfer rates are low. With the latest designs of steel tube economizers where the counter flow principle is used, gas velocities are higher and heat transfer rates with this type of economizer will vary from 4 B.T.U. to 8 B.T.U. (4.24 to 8.48 kJ) at 300% of rating.
With the amounts of economizer surface ordinarily installed, the increase in boiler efficiency may be taken as 1% for each 10% of the boiler surface in the economizer at different ratings, and 1.4% for each 10% of surface at 300% of boiler rating.
The installation of economizers necessitates the use of an induced draft fan to overcome the increased draft resistance and also because of the reduction in gas temperatures. The draft loss due to an economizer is usually from 40 to 60% of the loss through to boiler to which it is attached. There are two types of flue gas economizers on which we based our theories: wet scrubber technology and flue gas to hydronic technology.
(i) Wet Scrubber Technology
Wet scrubbers or what is called static spray scrubbers are usually of the tower type, the gas passing upward counter-currently to the descending liquid. Sets of sprays are placed in the top zone, with various materials used in layer to channel and mix the gas and water. Hurdles, cylindrical tiles, and random packed ceramic tiles or metal spirals are common packing materials. With a gas flow-rate of about 350 ft
3
/min per ft
2
(9.9 m
3
/min per 0.1 m
2
)
Enviro-Energy Products, Inc.
Griffin Steven P.
Squire Sanders & Dempsey L.L.P.
Strickland Jonas N.
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