Patent Publication Number: US-7914282-B2

Title: Apparatus for reducing pollution from a flare stack

Description:
FIELD OF THE INVENTION 
     This invention relates to an apparatus for reducing pollution from a flare gas stack and more particularly to a combination of a flare gas stack for waste combustible gases from industrial processes and an apparatus for reducing pollution from such stacks. 
     BACKGROUND FOR THE INVENTION 
     In many areas of the world, environmental concerns have focused on industrial pollution, efforts to reduce such pollution, global warming, acid rain and protection of the ozone layer. It has also been recognized that waste combustible gases from industrial processes including petrochemical processes may contribute to harmful pollution. As a result, there have been numerous attempts to control emissions, namely in the form of flare gases. 
     One approach to control flare gas emissions is disclosed in a U.S. patent of Straitz et al., U.S. Pat. No. 4,139,339. As disclosed therein provisions are made for start-up, steady state or transient purged gas control and for failure of the purged gas supply. It also takes into account variable wind speed at or near the top of the stack, flow or non-flow of purge gas and waste gas in the stack. The patent also teaches provisions for ambient temperature and temperatures of the advancing gaseous medium in the stack, oxygen content of the gases, pilot burner gas supply and ignition with protection against pilot burner operation under undesirable conditions. A control panel is also provided so that an operator can take appropriate action when necessary. 
     A more recent approach to flare apparatus and methods are disclosed in the U.S. Pat. No. 5,846,068 of Schwartz et al. The Schwartz patent discloses an improved flare apparatus for burning flammable gas and air. The apparatus includes an outer tubular member and an inner tubular member positioned within the outer tubular member whereby an annular flammable gas discharge space is provided immediately adjacent to an annular air discharge space. The flammable gas is discharged into the atmosphere in an annular straight out pattern. At least a portion of the air is discharged into the atmosphere for mixing with the flammable gas in a swirling pattern immediately adjacent to the flammable gas which prevents internal burning and premature failure of the flare apparatus. 
     A further approach to burning stack gas is disclosed in a U.S. patent of Rajewski, U.S. Pat. No. 5,865,613. The Rajewski patent discloses a flare stack with a smokeless burn and reduced steam consumption. The flare stack includes a central pipe having a flare tip with a flare tip edge. An outer pipe surrounds the central pipe and forms an annulus between them. A spreader spreads gas from the central pipe into the annulus. Steam and air with oxygen are forced into the base of the annulus and past of the spreader to mingle with the gas and create smokeless burning. Steam and air are supplied by at least one conical conduit leading into the annulus, the conduit having an inlet for the flow of steam into it. A steam manifold having an outlet corresponding to each conduit, and each outlet being directed towards a corresponding inlet in the conduit are provided. In addition, an opening between each outlet and inlet for the flow of air into each conduit is drawn by a ventory effect. 
     Notwithstanding the above, it is presently believed that there is a need and a potential market for an improved apparatus for reducing pollution from a flare gas stack. There should be a demand for such apparatus since it will reduce pollution and reduce additional heat, acid rain and adverse effect on the ozone layer. In addition, the improved apparatus does not require burning of additional gases or added steam or oxygen to the flare gas. Further, it is presently believed that the apparatus in accordance with the present invention will have few moving parts and will be of durable construction. 
     BRIEF SUMMARY OF THE INVENTION 
     In essence, the present invention contemplates an improved apparatus for reducing pollution from a flare stack. The apparatus includes a first plurality of baffles and a support means such as a generally horizontal circular platform having an outer periphery disposed on the top of or near the top of a flare stack. The platform supports a first plurality of baffles at the top of the flare stack with the first plurality of baffles arranged in a generally circular configuration around the top of the flare stack and on an inner portion of the platform. The first plurality of baffles extends upwardly from the platform with a space between adjacent baffles. The space is about equal to the width of an adjacent baffle. This first plurality of baffles directs a portion of the flare gas upwardly above the flare gas stack while allowing a portion of the gas to flow outwardly between the first pluralities of baffles. 
     The apparatus also includes a second plurality of upwardly extending arcuate baffles disposed on the platform around the outer periphery thereof. Each of the baffles defines a pair of adjacent arcuate sections. 
     The apparatus also includes a first plurality of filters disposed on the platform between the first and second plurality of baffles and means for drawing a portion of flare gas into and through the first plurality of filters and directing the portion of flare gas below the platform. The apparatus also includes a second plurality of filters having the shape of a right circular cylinder for absorbing pollutants from the flare gas. 
     The invention will now be described in connection with the accompanying drawings wherein like reference numbers have been used to designate like parts. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an apparatus for reducing pollution from a flare stack in accordance with the present invention; 
         FIG. 2  is an exploded perspective view of the apparatus shown in Figure one; and 
         FIG. 3  is a top or plan view of a platform, blowers and baffles as used in the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
     As illustrated, in  FIGS. 1-3 , an apparatus  20  for reducing pollution from a flare stack includes a supporting means such as a generally circular horizontal platform  22  disposed at the top or near the top of a flare stack  24 . The platform  24  may for example be supported by a pair of brackets  26  (shown in  FIG. 2 ) or other conventional means as will be well understood by person of ordinary skill in the art. 
     The apparatus  20  also includes a first plurality of stainless steel upright baffles  30  disposed on the platform  22  and extending upwardly by a distance of about 20-30% preferable about 25% of the diameter of the platform  22 . The stainless steel baffles  30  are disposed in a circular array around the flare stack  24  for extending the height of the flare stack but providing a diameter of about 50% larger than the flare stack. These first plurality of baffles  30  direct a portion of gas and pollutants upwardly while allowing a portion of gas and pollutants to pass laterally through the openings between the first plurality of baffles. It is also believed that the baffles will cause a certain amount of turbulence which will cause pollutants and flare gases to impact on the first and second plurality of filters  32  and  34  respectfully. 
     The apparatus also includes a second plurality of upwardly extending stainless steel baffles  36  each of which define a pair of adjacent arcuate sections. In the preferred embodiment of the invention, the adjacent sections form a shallow “w”. These baffles  36  are at or near the outer edge of the platform  22  and spaced apart to reflect a portion of the flare gas and pollutants back toward a first and second plurality of upwardly extending filters that have a generally right circular cross section. 
     Means such as a fan, pump or blower  40  are disposed on or below each of the four filters  32  and are constructed and arranged for drawing flare gas and/or pollution into the central hollow areas of the filters  32 . The gas and/or pollutants are then exhausted below the platform  32  to a pipe  42  and into a storage tank  44  or are recycled back into the flare stack  24 . 
     The second plurality of filters  34  are treated with a suitable absorbent such as silica gel for absorbing flare gases. Further, a sensor (not shown) such as an oxygen sensor may be provided to monitor the composition of the gases and/or the combustion product. Other sensors may be used depending on the type of pollutant being monitored. 
     Inside each perforated cylinder there is a catalyst for filter made of ceramic, other filtering material that will filter out the remaining combustion product (smoke, smog, fire powder) and moisture, while the gas flows through. 
     While the invention has been described in connection with its preferred embodiment, it should be recognized that changes and modifications can be made therein without departing from the scope of the appended claims.