Abstract: A turbulence inducing fan blows cold gaseous nitrogen through ducts disposed to either side of a conveyor carrying product to be frozen through a freezing tunnel. The cold gaseous nitrogen is deflected downwardly onto product on the conveyor by a baffle having, in cross section, the form of a cusp. The cold gaseous nitrogen forms two counter-rotating vortex. The cold gaseous nitrogen travels across the product and then passes into an intake cowl primarily via inlets disposed adjacent both edges of the conveyor. The intake cowl collects the cold gaseous nitrogen which is sucked into the intake of the turbulence inducing fan. This arrangement provides excellent heat transfer to the product being frozen.

Abstract: The present invention is a tunnel freezer which incorporates a "dual flow" design whereby the refrigerant is introduced at each end of the tunnel and withdrawn from the middle of the tunnel. A key to the present invention is that the dual flow design allows one to confine the pressure gradient for leaks between the ends of the tunnel where it will not be a concern since the item entrance and exit ports (which ports provide a ready access for leaks) are located at the ends of the tunnel.

Abstract: The present invention is a combination immersion/impingement tunnel freezer. A solid conveyor belt moves the items to be frozen through an initial immersion section wherein the conveyor belt is immersed in a bath of liquid refrigerant. Subsequently, the conveyor belt moves the items to be frozen through an impingement section wherein the evaporated refrigerant from the immersion section is directed toward the solid conveyor belt at a high velocity and at an angle substantially perpendicular to the longitudinal axis of the tunnel.

Abstract: The present invention is a tunnel freezer which employs two distinct chambers for crust freezing the bottom surfaces of items to be processed without substantially refrigerating the remainder of the items. In this manner, the product is made ready for transfer to downstream operations without worry of sticking to belt surfaces. The present invention has application in setting the bottom surface of food items such as cookies, bakery items, caramel coated candies, taffy and the like.

Abstract: A process is set forth for purifying and liquefying a feed gas mixture with respect to its less strongly adsorbed component of lower volatility which integrates temperature swing adsorption (TSA), pressure swing adsorption (PSA) and cryogenic distillation to optimize overall performance. The TSA portion of the process is used to remove the strongly adsorbed component from the feed; the PSA portion of the process is used to remove the moderately strongly adsorbed component from the feed; and the cryogenic distillation portion of the process is used to remove the less strongly adsorbed component of higher volatility from the feed while also providing for the liquefaction of the product. A key to the present invention is the use of the PSA and distillation waste streams in the regeneration of the TSA and PSA adsorbents. An important application of the present invention is the purification and liquefaction of a natural gas feed stream with respect to its methane/C.sub.2 hydrocarbon component.

Abstract: An integrated adsorption/cryogenic distillation process is set forth for the separation of an air feed. The air feed is passed through a vacuum swing adsorption (VSA) unit to remove impurities comprising water and carbon dioxide which will freeze out at cryogenic temperatures. The VSA sequence includes an adsorbent regeneration step whereby the impurity-saturated adsorbent is purged under vacuum with a purge gas. The resulting impurity-depleted air feed is fed to a cryogenic distillation column for rectification into a gaseous nitrogen overhead and a liquid oxygen bottoms. A waste stream from the distillation column is expanded, warmed against the impurity-depleted air feed to recover its refrigeration and subsequently recycled as the purge gas to the VSA unit. A key to the present invention is that the waste stream is expanded to the required sub-ambient pressure level in the cryogenic portion of the process.

Abstract: A membrane-assisted process to produce ammonia is set forth wherein the recycle stream from the ammonia process containing primarily unreacted hydrogen and nitrogen but also containing inerts and unrecovered ammonia is separated in a first ammonia-selective membrane separator into a permeate stream enriched in ammonia and a non-permeate stream enriched in hydrogen, nitrogen and the inerts which is recycled to the reactor feed. A key to the present invention is that the permeate stream enriched in ammonia is recycled to the reactor effluent.

Abstract: A process is set forth for the cryogenic distillation of an air feed to produce a low to medium purity oxygen product using a single distillation column system. The air feed is partially condensed into a crude liquid oxygen stream and a remaining nitrogen-enriched vapor stream by boiling the liquid phase at the bottom of the distillation column. The pressure of the crude liquid oxygen stream is reduced and the nitrogen-enriched vapor stream is subsequently condensed against it to provide reflux to the top of the distillation column. The low to medium purity oxygen product (oxygen concentration between 65% and 99%) is withdrawn from the bottom of the distillation column as liquid, vapor or a combination of both.

Abstract: A process is set forth for the cryogenic distillation of an air feed to produce an ultra-high purity oxygen product. A first oxygen-containing but heavy contaminants-lean (free) stream is removed from the main distillation column system and subsequently stripped in an auxiliary distillation column. A second oxygen-containing but light contaminants-lean (free) gaseous stream is also removed from the main distillation column system and subsequently fed to the bottom section of the auxiliary distillation column in order to provide heat duty/reboil to the bottom of the auxiliary distillation column. The ultra-high purity oxygen product (ie total contaminant concentration less than 10.0 vppm, preferably less than 1.0 vppm) is withdrawn from an intermediate section of the auxiliary distillation column.

Abstract: A process is set forth for directly controlling the quantity and particle size distribution of the solid inventory inside a circulating fluidized bed combustor. A portion of the bed ash is withdrawn from the combustor as bottom ash. The particle size distribution of the stream is adjusted, such as by a hammermill, to a specified distribution. Finally, a portion of the adjusted ash is re-injected into the combustor. The process may be facilitated by size classifying the bottom ash prior to size reduction.

Abstract: A two stage pressure swing adsorption process is set forth for producing high purity oxygen from a feed air stream wherein carbon dioxide, water and preferably nitrogen are removed in the first stage and wherein an oxygen selective adsorbent is used to adsorb oxygen in the second stage. The oxygen product is recovered upon depressurization of the second stage. The high purity of the oxygen product is achieved by rinsing the oxygen selective adsorbent with oxygen prior to the depressurization step. A key to the present invention is that the effluent streams from the second stage feed and rinse steps are used to regenerate the first stage adsorbent(s) in a specific regeneration scheme.

Abstract: A two stage pressure swing adsorption process is set forth for producing the less strongly adsorbed component of a feed gas mixture wherein the first stage utilizes a first adsorbent for bulk removal of the more strongly adsorbed component and wherein the second stage utilizes a second adsorbent for trace removal of the more strongly adsorbed component. A further feature of the present invention is that the desorbed gas from the second stage's depressurization step (consisting primarily of the desired less strongly adsorbed component) is recycled to the first stage in order to improve its performance. In a preferred embodiment of the present invention, high purity nitrogen (less than 1000 ppm oxygen, preferably less than 100 ppm oxygen) is produced from an air feed using a kinetically controlled carbon molecular sieve adsorbent in the first stage and an equilibrium controlled metal complex-based adsorbent in the second stage.

Abstract: The present invention is an ammonia injection scheme for enhanced NO.sub.x reductions wherein the NO.sub.x containing gas to be treated is upstream of a cyclone separator. The enhanced NO.sub.x reductions is accomplished by injecting the ammonia through the inside wall of the cyclone inlet duct.

Abstract: A pressure swing adsorption process is set forth for the recovery of two gas products at high recovery and high purity using the steps of adsorption, depressurization, low pressure purge, evacuation and repressurization. The purge effluent and a portion of the depressurization effluent are used to partially accomplish the repressurization step.

Abstract: Fly ash generated from incineration of municipal solid waste (MSW) when placed in landfills can under mild acid conditions can leach lead and cadmium. A process for stabilizing heavy metals in this fly ash is presented which involves calcining the fly ash in the presence of an oxygen containing gas stream at a temperature greater than about 400.degree. C. and less than about 600.degree. C. for times from about 170 seconds up to about 5 hours fly ash which has been subjected to calcium scrubbing for acid gas removal. Such treated MSW fly ash will give leachates containing heavy metal concentrations less than the EPA regulatory limit.

Abstract: Fly ash generated from incineration of municipal solid waste (MSW) when placed in landfills can under mild acid conditions 1each lead and cadmium. A process for stabilizing lead in this fly ash is presented which involves calcining a mixture of the fly ash and certain calcium-containing compounds in the presence of an oxygen containing gas stream at a temperature greater than about 475.degree. C. and less than about 600.degree. C. for times from about 30 minutes up to about 5 hours. Such treated MSW fly ash will give leachates containing lead concentrations less than the EPA regulatory limit.

Abstract: A process is set forth for producing a krypton/xenon enriched stream directly from the main air distillation column in a cryogenic air separation process. A column bypass is suggested in the bottom few trays of the low pressure column in order to concentrate krypton and xenon in the sump while rejecting the majority of methane in the gaseous oxygen product.

Abstract: A process is set forth for producing a krypton/xenon enriched stream from a cryogenic nitrogen generator. Distillation of the oxygen product stream at the top of the low pressure column is suggested in order to concentrate krypton and xenon while rejecting the majority of methane in the oxygen product stream.

Abstract: A process is set forth for the separation of one or more, more permeable components from one or more, less permeable components in a feed stream. The process suggests two membrane separation stages in series wherein the feed is introduced into the low pressure side of the first stage, the permeate stream from the first stage is compressed and introduced into the high pressure side of the second stage and wherein the non-permeate stream from the second stage is recycled to the high pressure side of the first stage.

Abstract: In a process for preparing poly(vinyl alcohol), an improved method for separating the methanol/acetate azeotropes that result from said process. The azeotropes are separated by selective adsorption of methanol on an adsorbent followed by regeneration of the adsorbent with hot methanol vapor.