US3883329A

US3883329A - High efficiency vapor control system

Info

Publication number: US3883329A
Application number: US435705A
Authority: US
Inventors: Sr John A Dupps
Original assignee: Dupps Co
Current assignee: Dupps Co
Priority date: 1974-01-23
Filing date: 1974-01-23
Publication date: 1975-05-13
Anticipated expiration: 1992-05-13
Also published as: FR2258216B1; FR2258216A1; NL7500743A; DE2502694A1; GB1473995A

Abstract

A vapor control system in which noxious and odoriferous vapors are first condensed and the remaining non-condensable vapors subjected to a scrubbing operation to wash and dilute the residual gases, the scrubbed gases as an incident of their evacuation from the system being subjected to additional treatments selectively utilizing chemical gaseous and incinerating mediums to further purify the effluent so that it is effectively odor free when discharged from the system, the system enabling the user to obtain maximum odor control utilizing the treatment mediums which are most efficient and economical for the operating conditions encountered.

Description

United States Patent 11 1 Dupps, Sr.

1 1 HIGH EFFICIENCY VAPOR CONTROL SYSTEM [75] Inventor: John A. Dupps, Sr., Germantown,

Ohio

[731 Assignee: The Dupps Company, Germantown.

Ohio

[22] Filed: Jan. 23, 1974 [21] Appl. No.: 435,705

[52] US. Cl 55/222; 23/277 C; 23/284; 55/228; 55/233; 55/259; 55/261; 261/98;

[51] Int. Cl .1B0ld 47/06 [58] Field of Search 55/222, 227. 228, 233,

1 1 May 13, 1975 Primary E.\'aminer-Bernard Nozick Attorney, Agent, or Firm-Melville, Strasser, Foster & Hoffman 1 1 ABSTRACT A vapor control system in which noxious and odoriferous vapors are first condensed and the remaining noncondensable vapors subjected to a scrubbing opera tion to wash and di1ute the residual gases, the scrubbed gases as an incident of their evacuation from the system being subjected to additional treatments selectively utilizing chemical gaseous and incinerating mediums to further purify the effluent so that it is effectively odor free when discharged from the system, the system enabling the user to obtain maximum odor control utilizing the treatment mediums which are most efficient and economical for the operating conditions encountered.

7 Claims, 7 Drawing Figures HIGH EFFICIENCY VAPOR CONTROL SYSTEM BACKGROUND OF THE INVENTION This invention relates to pollution control apparatus and has to do more particularly with improvements in the type of vapor control apparatus disclosed in US. Pat. No. 3,572,010, issued Mar. 23, l97l, and entitled Vapor Control Apparatus." In accordance with this patent, contaminated vapors, such as those generated in the rendering of animal, fish and poultry by-products to yield fat and tankage, are processed in a vapor control tower which condenses the generated vapors, washes the remaining noncondensables to remove objectionable odors, and additionally serves to evacuate odor laden air from the building in which the apparatus is located, thereby also effectively controlling odors which are inevitably released within the processing plant itself. While such vapor control apparatus has been highly effective in controlling objectionable vapors, the present day demands for ecological improvements has dictated even more stringent controls than were heretofore deemed satisfactory.

Accordingly, the present invention is directed to improved vapor control apparatus in the form of a system which is highly efficient and, in the case of the effluent from a rendering plant, is capable of removing in excess of 99% of the objectionable odors prior to discharge into the atmosphere.

RESUME OF THE INVENTION In accordance with the invention, the vapors to be treated are first subjected to an initial treatment in which they are condensed, the condensate removed, and the remaining non-condensables passed through a water spray which washes and dilutes the remaining gases. Such initial treatment is of known character, although as will be pointed out hereinafter, whereas the washing or scrubbing operation was heretofore performed utilizing water as the washing medium, the present invention contemplates the admixture of chemicals utilized in a secondary treatment with the wash water to enhance the washing efficiency.

A principal feature of the present invention is the treatment of the washed gases in the vapor control tower, such gases as an incident of their evacuation from the system being subjected to one or more chemical treatments utilizing liquid and gaseous mediums, together with the removal of condensate, so that the discharged effluent is essentially free from pollutants. In an alternative arrangement, only the odor laden plant air is subjected to the washing and chemical treatments in the vapor control tower, the noncondensables removed from the bottom of the tower housing being scrubbed in a separate scrubber which utilizes the chemical containing washing solution from the tower as the scrubbing medium, the washed gases from the separate scrubber being discharged into an incinerator wherein the residual gases are burned. This arrangement provides the user with alternative procedures which may be selectively utilized depending upon the economics involved, which will vary depending upon the nature and extent of contamination of the vapors being treated and the relative costs of the chemicals and fuel for the incinerator. Under conditions wherein the noxious odors to be removed are not extreme, the chemical treatment of the non-condensables in the tower normally will be the more efficient and economical. However, in other instances, it has been found to be more efficient to chemically treat only the plant air in the tower, which requires far less chemicals than if the non-condensables are also treated, the noncondensables being subjected to an initial washing operation in a separate scrubber, whereupon the residual gases are incinerated. Such alternative arrangement is particularly suited to situations wherein the vapors being treated require massive chemical treatment to remove objectionable odors and/or where an incinerating means, such as a plant boiler, is readily available to incinerate the residual gases as a secondary function, or where the cost of incineration is less than the cost of the chemicals required to treat the noncondcnsables in the tower.

The invention contemplates a tower construction in which the various operating components for treating the vapors are contained within an elongated, vertically disposed, and preferably cylindrical tower, the vapors to be treated entering the system toward the upper part of the tower, traveling downwardly for condensation, with condensate removal at the bottom of the tower, whereupon contaminated plant air is drawn into the tower, with or without the non-condensables, to create an air stream traveling upwardly through the tower for scrubbing and chemical treatment, Such arrangement requires a relatively small amount of valuable floor space in the plant and, in addition, provides for maximum efficiency in the utilization of treatment materials. Thus, the initial treatment basically utilizes water as the treating medium, with the more expensive chemical treating mediums concentrated in the after or secondary treatment portion of the tower wherein the gases being acted upon have already been relieved of a substantial portion of their contaminants. Conse quently, the required chemical materials only need be supplied in a quantity sufficient to remove the residual contaminants. In addition, the residual liquid chemicals from the after treatment flow downwardly through the housing where they are mixed with the wash water and utilized to enhance the effectiveness of the washing operation performed as a part of the initial treatment, irrespective of whether such initial treatment is conducted in the tower or in a separate scrubber. The system is highly efficient, not only in the removal of contaminants from the vapors being treated, but also in the utilization of treatment materials, leading to over-all reductions in operating costs.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a pictorial vertical sectional view of a vapor control tower in accordance with the invention.

FIG. 2 is a vertical sectional view taken along the lines 22 of FIG. 1.

FIG. 3 is a vertical sectional view taken along the line 3-3 of FIG. 1.

FIG. 4 is a vertical sectional view taken along the line 44 of FIG. 1.

FIG. 5 is a vertical sectional view taken along the line 55 of FIG. 1.

FIG. 6 is a vertical sectional view taken along the line line 66 of FIG. 1.

FIG. 7 is a fragmentary elevational view with parts broken away illustrating the use of a separate scrubber and incinerator for non-condensables removed from the tower.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1 of the drawing, the tower apparatus comprises an elongated, vertically disposed, and preferably cylindrical housing 1 having a lower or initial treatment zone A, and an upper or secondary treatment zone B. Vapors to be treated enter the sys tem through the vapor inlet conduit 2 at the upper end of the primary treatment zone, and gases which are treated and purified in the tower are discharged from the top of the tower through exhaust stack 3 the extension of which projects upwardly through the roof of the building in which the vapor control apparatus is located so as to vent the decontaminated gases to the outside atmosphere. it will be understood that a suitable fan, indicated diagrammatically at 4, is located within or operatively connected to the exhaust stack to draw the treated gaseous residue and air upwardly through the housing 1. Air is introduced into the system through inlet ports 5 in the annular base 6 at the bottom of the housing, the lowermost portion of which is divided by a baffle 7 into a reservoir 8 and a condensate discharge compartment 8a.

The vapor inlet conduit 2, through which the vapors and non-condensables are introduced into the system, extends inwardly through the wall of housing 1 with its innermost end opening into a closed upper chamber 9, preferably of annular configuration and a diameter sufficiently smaller than the diameter of the housing 1 so as to provide an essentially annular passageway 10 for the gases and air which are drawn upwardly through the housing for subsequent discharge. An annular bank of condensing tubes 11 extends downwardly from the upper chamber 9, the uppermost ends of the tubes 11 opening into the undersurface of the chamber 9, such openings being indicated at 12. At their lowermost ends, the condensing tubes 11 open into a closed lower chamber 13, which is also of annular configuration and extends inwardly from the wall surfaces of housing 1, the lower chamber terminating inwardly in an annular wall 14 defining an airflow passageway 15 through which air and non-condensables flow upwardly within the housing.

A vertically disposed spray pipe 16 extends upwardly through the center of the housing from the reservoir 8 to the area of upper chamber 9, the spray pipe being closed at its opposite ends and equipped at spaced intervals along its length with radially disposed sets of spray nozzles 17 arranged to direct conical sprays of water outwardly from the spray pipe onto the annular array of condensing tubes 11, the sprayed water also passing beyond the condensing tubes out to the wall surfaces of the housing 1. The water returns to the reservoir by gravity, running down the tubes and the walls of the housing into the reservoir 8 through the passage 15. Thus, the water sprayed from the nozzles 17 will cool the condensing tubes and hence condense the vapors flowing through the tubes, the condensate soforrned being collected in the lower chamber 13 from which the condensate is discharged into discharge chamber 8a through drain conduit 18. The collected condensate, together with overflow from reservoir 8, is discharged from the system through discharge conduit 19 which may be connected to a sewer or other disposal means.

Waterfor the spray pipe 16 is supplied from reservoir 8, pump means 20 being arranged to withdraw water from the reservoir through outlet pipe 21 for introduction into the bottom end of spray pipe 16 through inlet pipe 22. The spray water is in part recirculating in that the returning water which runs down the condensing tubes will return to the reservoir, although preferably a portion of the returning water will spill into the discharge compartment 8a and will be discharged along with the condensate. Such arrangement prevents the build-up of excessive salts and also serves to further cool the condensate prior to its discharge into the sewer. The reservoir will also be provided with a supply of fresh water, through a suitable inlet pipe and floatcontrolled valve mechanism (not shown), which will serve to automatically add makeup water to the reser voir when the apparatus is in use. If desired, the height of the water in the reservoir may be controlled to permit some of the water from the reservoir to cascade into the discharge compartment 8a, or the baffle 7 may be perforated for such purpose, thereby further facili tating the discharge of the condensate.

Along with the condensate, the lower chamber 13 also collects the non-condensable gases which are withdrawn through conduit 23 by blower 24 which directs the non-condensables through conduit 25 for introduction through conduit 26 into the annular base 6 of the housing in the area above the reservoir 8 where the gases are drawn upwardly through annular passage 15 along with plant air drawn into the housing through the inlet ports 5. in the event incineration of the non condensables is desired, the valve 27 will be utilized to divert the gases through conduit 28 to the separate scrubbing and incinerating means which will be described hereinafter.

When the non-condensable gases are returned to the tower through the annular base 6, they are admixed with the plant air drawn into the system through inlet ports 5 and are thus highly diluted. As the air stream so-formed is drawn upwardly through the housing, it will flow outwardly between the annular array of condensing tubes 11 and around the upper chamber 9 through the annular passage 10. During such flow, the air stream is washed by the water being sprayed from the nozzles 17, such spraying action serving to remove particulate matter carried by the air stream; and the air stream in turn acts to remove heat from the system and discharge it into the atmosphere.

The tower apparatus thus far described is of known character and has heretofore been utilized in the con trol of noxious and odoriferous vapors. While such apparatus will remove up to about 60% of the objectionable contaminants encountered in the vapor effluent from a rendering plant which was wholly adequate under heretofore customary emission control standards many communities now require much higher stan dards. It has been found that even the most stringent standards can be met by subjecting the air stream to one or more chemical treatments, which can be conveniently conducted within the housing 1 immediately above the upper chamber 9. However, in the event the cost of the chemical treatment becomes excessive when the entire operation is performed in the tower, the system may include a separate scrubber and incinerator for the non-condensables withdrawn from the chamber 15.

In accordance with the invention, provision is made in the tower for chemically treating the partially puri fied air stream. While chemical treatments have heretofore been utilized in vapor control systems, the use of a chemical after treatment in conjunction with an initial treatment of the character described, provides a number of advantages. Since a substantial portion of the objectionable materials are removed during the initial treatment, substantial economics can be effected in many instances in the quantity of the treating materials required for the after treatment; and the treating materials can be selected in accordance with the specific nature of the impurities remaining in the air stream. In addition, by conducting the chemical treatment in the upper portion of the tower, the chemicals, after performing their initial treatment function, may be reused, in part at least, to enhance the scrubbing of the air stream which takes place during the initial treatment. whether such initial treatment takes place in whole or in part within the tower. Such reuse of the chemicals effects further savings in two ways; first, a saving is effected by the mere fact that the materials are being reused, and second, by reuse in conjunction with the ini tial treatment, the chemical additives enhance the effectiveness of the scrubbing operation and hence the air stream contains less impurities at the time it is subjected to the secondary treatment, with the result that less chemicals are required to complete the purification of the effluent gases.

Referring again to FIG. 1, the after treatment area of the system comprises a perforated support or base 29 overlying the upper chamber 9 and occupying the entire inside dimensions of the housing 1. As seen in FIG. 2, the base 29 comprises an annular frame having spaced apart supporting ribs, such as the ribs 30, supported on a medial transverse member 31. The support is surfaced with a perforated material 32, which may conveniently comprise one or more sections of expanded metal having a relatively large open flow area. Preferably the base 29, which may have a diameter on the order of 10 feet, will be formed in sections which can be readily removed and reinstalled, thereby facilitating cleaning and maintenance.

The base 29 serves as a support for a bank of packing rings 33, seen in FIGS. 1 and 3, which provide a massive reactive surface area for exposing the air stream to the chemicals. The packing rings are of known construction and generally comprise cylindrical members having spaced apart openings in their cylindrical wall surfaces and interconnecting internal webs arranged in spider-like fashion. Such rings, which are usually formed from plastic or ceramic materials, are designed to provide maximum surface area while minimizing resistance to airflow through and around the rings. Thus, when the rings are wetted with a liquid substance, they effectively provide maximum exposure of the liquid to the air stream. In accordance with the invention, a bank of packing rings will be built-up on support 29. While illustrated in sideby-side and stacked relation, the rings are often in random positions, as dumped on the base 29 and leveled. In an exemplary embodiment wherein the housing has a diameter of 10 feet, the bank of packing rings will be from 3 to 4 feet deep.

Spray means 34 overlie the bank of packing rings, the spray means having a plurality of spaced apart spray heads 35 arranged to direct conical sprays of the chemicals downwardly on the bank of packing rings. An exemplary arrangement of such spray heads is illustrated in FIG. 4, the primary objective being to insure full coverage of the packing rings with the chemicals. The air stream, as it travels upwardly through the after treatment section of the housing, is exposed both to the chemical carrying surfaces of the packing rings and also to the conical sprays themselves, thereby assuring optimum exposure of the air stream to the chemical treatment.

Essentially, the selection of the chemical treatment will depend upon the composition of the air stream and the odors to be removed. Where vapors from a rendering plant are being processed, solutions of caustic soda, sodium hypochlorite, and potassium permanganate may be employed, as well as other chemical compounds having the desired purification and deodorizing properties.

A moisture filter or demister 36 overlies the spray means 34 and serves the dual function of containment of the sprayed chemicals and removal of moisture from the air stream. As seen in FIG. 5, the demister comprises a suitable frame 37 which supports a batting 38 of metal excelsior, preferably about 6 inches in thickness, through which the air stream flows prior to discharge. Moisture in the air stream condenses on the metal strands and drains downwardly, ultimately returning to the reservoir 8.

The after treatment section may also include a gas diffuser, indicated at 39. preferably located in the re duced diameter exhaust stack 3just beyond the demister 36. The diffuser illustrated is of the type having a fluted rotary impeller contained within a diffusion chamber having an annular discharge orifice, indicated at 40, the unit being mounted within the exhaust stack 3 by means of supporting arms 41, as possibly best seen in FIG. 6. One or more supply conduits, such as the

conduits

42 and 43 are arranged to supply one or more desired gases to the diffuser which discharges the gaseous medium into the air stream as it flows upwardly through the exhaust stack and around the diffuser.

The gas treatment is optionai but may be utilized as a further means for purifying and deodorizing the air stream. Thus, the air stream may be selectively treated with ozone, chlorine, or other purifying and deodorizing gases in controlled amounts, or with mixtures of gases. The gas diffuser may take other forms, inclusive of the use of an array of discharge nozzles arranged to admix the discharged gases with the outgoing air stream.

While the tower apparatus just described is highly ef ficient and is designed to minimize the consumption of chemicals in the after treatment section, the cost of the chemicals can nonetheless be quite substantial, or in short supply a condition which is not uncommon in the current market. Accordingly, the present invention provides certain alternatives which may be utilized to effect still further economies under certain operating conditions. Thus, as seen in FIG. 7, the conduit 28 may be utilized to divert the non-condensables to a scrubber 44 wherein they are subjected to the action of a spray head 45, the non-condensable gases being drawn upwardly through the scrubber by means of the blower unit 46. In accordance with the invention. the spray head 45 is supplied with washing liquid from the vapor control tower. Thus, washing liquid may be piped directly from the spray pipe 16 in the tower by means of conduit 47. Of course, if desired, the spray head 45 may be supplied from an independent source, but preferably it will utilize the washing solution in the tower, thereby taking advantage of the chemicals which are introduced into the system during the after treatment.

Since a primary function of the scrubber 44 is to reduce chemical consumption in the tower, particularly where massive amounts of chemicals would be required to deodorize noncondensable gases having a high odor level, it should be readily evident that with the diversion of the non-condensables to the scrubber 44, and hence with only plant air flowing upwardly through the tower for chemical treatment, the quantity of chemicals required will be materially reduced. However, even under such conditions, effective amounts of the chemicals remain in the washing solution which returns to the reservoir to enhance the spraying action which takes place in the scrubber, although in this instance the effluent gases will be incinerated rather than discharged directly into the atmosphere.

Provision is made, however, for metering additional chemicals to the spray head 45 in the scrubber if such expedient is deemed necessary. The chemicals will be supplied to the spray means 34 in the tower through conduit 48, being pumped from the chemical tank 49 through conduit 50 by means of pump 51. Suitable metering controls 52 are provided to control the flow of the chemicals to the tower spray means 34. Chemicals from the tank 49 may also be supplied to the spray head 45 in the separate scrubber through branch conduit 53 and metering and mixing valve 54 interposed in the conduit 47 which supplies washing solution under pressure from the spray pipe 16 in the tower. While the primary function of the scrubber 44 is to remove solids from the non-condensable gases prior to incineration, the chemical treatment in the scrubber may be utilized as a means to combat odors which are not effectively eliminated by incineration.

Washing solution and particulate matter from the scrubber may be discharged into the sewer system through drain 55, with the gases drawn upwardly through the scrubber by the blower unit 46 discharged through duct 56 which delivers the scrubbed gases to an incinerator 57 for other burner unit wherein they are incinerated. While a separate incinerator may be utilized, it is sometimes possible for the user to take advantage of an existing burner, such as a plant furnace or boiler, to incinerate the gases, thereby effecting still further economies in the operation of the system.

As should now be evident, vapor control apparatus in accordance with the invention provides an integrated system capable of achieving substantially complete removal of contaminants. The system provides the user with the ability to vary the treatment in accordance with the nature of the noxious or odoriferous gases encountered, and at the same time the system is highly efficient, with the effluent from the after treatment utilized to enhance the effectiveness of the initial scrubbing operation whether such operation be performed in the tower or in the separate scrubber. The user also has the ability to vary the treatment in accordance with the availability and cost of necessary chemicals, as well as the availability and relative cost of operation of the incinerating means.

Modifications may be made in the invention without departing from its spirit and purpose. Various such modifications have already been set forth and others will undoubtedly occur to the skilled worker in the art upon reading this specification. Consequently, it is not intended that the scope of the invention be limited other than in the manner set forth in the claims which follow.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. A vapor control system comprising an elongated, vertically disposed tubular housing having air inlet means at its bottom and air discharge means at its top, including blower means connected to said housing for creating an air stream flowing upwardly through said housing; a lower treatment zone comprising upper and lower spaced apart annular chambers mounted in said housing, an annular passage between said housing and said upper chamber, said lower chamber terminating inwardly in an annular wall defining a centrally disposed air flow passage, the said air stream flowing upwardly through the said passages, an annular array of condensing tubes interconnecting said upper and lower chambers and surrounding the air flow passage in the lower chamber, means for introducing odor containing vapors into said upper chamber, means for withdrawing condensate from said lower chamber, means for withdrawing non-condensables from said lower chamber, conduit means connected to the means for withdrawing noncondensables from said lower chamber and to the housing for introducing the non-condensables into the air stream beneath said lower chamber, and first spray means in said housing positioned to spray liquid onto said annular array of condensing tubes through the air stream; an upper treatment zone in said housing overlying said upper chamber comprising means for subjecting the air stream to a liquid chemical treatment, and means overlying the said liquid chemical treatment means for thereafter removing moisture from the air stream prior to its discharge from the system through said air discharge means; a reservoir underlying said lower annular chamber for collecting both residual liquid chemicals from the chemical treatment means and liquid discharged by said first spray means for recirculation, and conduit means, including pump means, connected to said reservoir and to said first spray means for pumping admixed liquid and chemicals from said reservoir to said first spray means; and a separate scrubber adjacent said housing, spray means in said scrubber, conduit means operatively connecting the spray means in said scrubber to the reservoir in said housing, metering means for introducing additional chemicals into the conduit supplying the spray means in said scrubber, said metering means being connected to said last named conduit and to a separate source of liquid chemicals, means connected to the means for withdrawing non-condensables from the lower chamber for diverting the non-condensables to said scrubber for passage therethrough, and means for withdrawing the noncondensables for said scrubber for delivery to an incinerating means.

2. The vapor control system claimed in claim 1 wherein the means for removing moisture from said air stream comprises a batting of metal excelsior overlying said spray means.

3. The vapor control system claimed in claim I including gas diffusing means overlying the means for removing moisture from said air stream, whereby the air stream may be treated with a gaseous medium immediately prior to its discharge from the system.

4. The vapor control system claimed in claim 3 wherein said gas diffusing means includes means for selectively introducing different gaseous mediums into the air stream and for alternately blending different gases for discharge into the air stream.

5. The vapor control system claimed in claim 1 wherein said liquid chemical treatment means includes packing means presenting a large surface area exposed to the air stream. and second spray means for spraying the packing means with liquid chemicals.

Claims

1. A VAPOR CONTROL SYSTEM COMPRISING AN ELONGATED, VERTICALLY DISPOSED TUBULAR HOUSING HAVING AIR INLET MEANS AT ITS BOTTOM AND AIR DISCHARGE MEANS AT ITS TOP, INCLUDING BLOWER MEANS CONNECTED TO SAID HOUSING FOR CREATING AN AIR STREAM FLOWING UPWARDLY THROUGH SAID HOUSING; A LOWER TREATMENT ZONE COMPRISING UPPER AND LOWER SPACED APART ANNULAR CHAMBERS MOUNTED IN SAID HOUSING, AN ANNULAR PASSAGE BETWEEN SAID HOUSING AND SAID UPPER CHAMBER, SAID LOWER CHAMBER TERMINATING INWARDLY IN AN ANNULAR WALL DEFINING A CENTRALLY DISPOSED AIR FLOW PASSAGE, THE SAID AIR STREAM FLOWING UPWARDLY THROUGH THE SAID PASSAGES, AN ANNULAR ARRAY OF CONDENSING TUBES INTERCONNECTING SAID UPPER AND LOWER CHAMBERS AND SURROUNDING THE AIR FLOW PASSAGE IN THE LOWER CHAMBER, MEANS FOR INTRODUCING ODOR CONTAINING VAPORS INTO SAID UPPER CHAMBER, MEANS FOR WITHDRAWING CONDENSATE FROM SAID LOWER CHAMBER, MEANS FOR WITHDRAWING NON-CONDENSATE FROM SAID LOWER CHAMBER, CONDUI! MEANS CONNECTED TO THE MEANS FOR WITHDRAWING NONCONDENSABLES FROM SAID LOWER CHAMBER AND TO THE HOUSING FOR INTRODUCING THE NON-CONDENSABLES INTO THE AIR STREAM BENEATH SAID LOWER CHAMBER, AND FIRST SPRAY MEANS IN SAID HOUSING POSITIONED TO SPRAY LIQUID ONTO SAID ANNULAR ARRAY OF CONDENSING TUBES THROUGH THE AIR STREAM; AN UPPER TREATMENT ZONE IN SAID HOUSING OVERLYING SAID UPPER CHAMBER COMPRISING MEANS FOR SUBJECTING THE AIR STREAM TO A LIQUID CHEMICAL TREATMENT, AND MEANS OVERLYING THE SAID LIQUID CHEMICAL TREATMENT MEANS FOR THEREAFTER REMOVING MOISTURE FROM THE AIR STREAM PRIOR TO ITS DISCHARGE FROM THE SYSTEM THROUGH SAID AIR DISCHARGE MEANS; A RESERVOIR UNDERLYING SAID LOWER ANNULAR CHAMBER FOR COLLECTING BOTH RESIDUAL LIQUID CHEMICALS FROM THE CHEMICAL TREATMENT MEANS AND LIQUID DISCHARGED BY SAID FIRST SPRAY MEANS FOR RECIRCYALTION, AND CONDUIT MEANS, INCLUDING PUMP MEANS, CONNECTED TO SAID RESERVOIR AND TO SAID FIRST SPRAY MEANS FOR PUMPING ADMIXED LIQUID AND CHEMICALS FROM SAID RESERVOIR TO SAID FIRST SPRAY MEANS; AND A SEPARATE SCRUBBER ADJACENT SAID HOUSING, SPRAY MEANS IN SAID SCRUBBER, CONDUIT MEANS OPERATIVELY CONNECTING THE SPRAY MEANS IN SAID SCRUBBER TO THE RESERVOIR IN SAID HOUSING, METERING MEANS FOR INTRODUCING ADDITIONAL CHEMICALS INTO THE CONDUIT SUPPLYING THE SPRAY MEANS IN SAID SCRUBBER, SAID METERING MEANS BEING CONNECTED TO SAID LAST NAMED CONDUIT AND TO A SEPARATE SOURCE OF LIQUID CHEMICALS, MEANS CONNECTED TO THE MEANS FOR WITHDRAWING NON-CONDENSABLES FROM THE LOWER CHAMBER FOR DIVERTING THE NON-CONDENSABLES TO SAID SCRUBBER FOR PASSAGE THERETHROUGH, AND MEANS FOR WITHDRAWING THE NON-CONDENSABLES FOR SAID SCRUBBER FOR DELIVERY TO AN INCINERATING MEANS.

3. The vapor control system claimed in claim 1 including gas diffusing means overlying the means for removing moisture from said air stream, whereby the air stream may be treated with a gaseous medium immediately prior to its discharge from the system.

5. The vapor control system claimed in claim 1 wherein said liquid chemical treatment means includes packing means presenting a large surface area exposed to the air stream, and second spray means for spraying the packing means with liquid chemicals.

6. The vapor control system claimed in claim 5 wherein said packing means comprises a bank of packing rings seated on a perforated support plate.

7. The vapor control system claimed in claim 6 wherein said second spray means comprises a plurality of spray heads overlying said bank of packing rings and positioned to spray liquid chemicals downwardly onto said packing rings and the upwardly flowing air stream.