CA1198364A - Method and apparatus for cooling a hot particulate- laden process stream - Google Patents
Method and apparatus for cooling a hot particulate- laden process streamInfo
- Publication number
- CA1198364A CA1198364A CA000404611A CA404611A CA1198364A CA 1198364 A CA1198364 A CA 1198364A CA 000404611 A CA000404611 A CA 000404611A CA 404611 A CA404611 A CA 404611A CA 1198364 A CA1198364 A CA 1198364A
- Authority
- CA
- Canada
- Prior art keywords
- gas stream
- particulate
- stream
- hot
- venturi
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D51/00—Auxiliary pretreatment of gases or vapours to be cleaned
- B01D51/10—Conditioning the gas to be cleaned
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D47/00—Separating dispersed particles from gases, air or vapours by liquid as separating agent
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
- C09C1/44—Carbon
- C09C1/48—Carbon black
- C09C1/50—Furnace black ; Preparation thereof
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28C—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA COME INTO DIRECT CONTACT WITHOUT CHEMICAL INTERACTION
- F28C3/00—Other direct-contact heat-exchange apparatus
- F28C3/06—Other direct-contact heat-exchange apparatus the heat-exchange media being a liquid and a gas or vapour
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28C—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA COME INTO DIRECT CONTACT WITHOUT CHEMICAL INTERACTION
- F28C3/00—Other direct-contact heat-exchange apparatus
- F28C3/10—Other direct-contact heat-exchange apparatus one heat-exchange medium at least being a fluent solid, e.g. a particulate material
- F28C3/12—Other direct-contact heat-exchange apparatus one heat-exchange medium at least being a fluent solid, e.g. a particulate material the heat-exchange medium being a particulate material and a gas, vapour, or liquid
Abstract
Abstract of the Disclosure A hot, particulate-laden process gas stream is cooled preparatory to cloth filtration treatment thereof by conducting said stream through a venturi-shaped conduit (20) adapted to cause acceleration of the stream to a Mach number of at least about 0.25. A plurality of streams of liquid water is introduced through means (27) trans-versely into the process stream in the region of the throat (24) of the venturi-shaped conduit (20), the rate of total water so introduced being sufficient to cool the process stream to the desired temperature. The cooled process stream can then be conducted into a cloth filtration device (15) wherein separation of the particulate component from the gaseous component is performed.
Description
Method and Apparatus for Coolin~ a Hot Particulate-Laden Process Stream The present invention relates broadly to cooling of paTticulate-laden process st~eams and is more specifically concerned with an integrated method and means for cooling hot, particulate-laden process streams and separating the particulate burdens therefrom by 5 cloth filtration.
In many industrial processes products or by-products are prodllced in suspended par~iculate form, ~hat is to say, in the form of a solid particulate matteT component entrained in a hot gas stream component. For instance, 1~ furnace carbon blacks are produced by the thermal decom-position and/or paTtial combustion of hydrocarbonaceous feedstocks and are normally initially produced in the form of an aerosol or suspension of the paTticulate carbon - black product in hot by-product flue gases. The carbon 15 black process stream is quenched in the carbon black' forming reactor to terminate the carbon forming reaction, urther cooled and then treated ~y cloth filtration in order to collect the carbon black product. Some other exemplary industrial processes in which a hot, particulate^
2n laden process stream is cooled and then aubj ected to cloth filtration and to which the present in~ention may be employed with good efect are: treatment of coal fired power plant flue gases prior to filtration of the particu-late burden therefrom, cooling of dry process cemen~ cal-25 cining streams, cooling of calcined ore or rock dust con-taining streams and the like.
~"3~
Typically, cloth filtration methods o~ co~erce in~lve flowing a particulate-laden gaseous s~ream through one or more pOTOUS cloth or fab~ic fil~ration elements, said elements having a selected poTosity or transmissibility which is, at once, sufficient to allow the gaseous component of the process stream ~o pass therethrough while being insufficien~ to allow passage of the particulate component. In consequence, the par~iculate component is separated from the gaseous component and is deposited on the upstream or collection side o-f the cloth fil~ration elemen~s. Means are usually provided by which to aid removal of the particulate burden from the filt~ation elements, such as by periodic repressurization or reversal of the ~as flow therethrough, mechanical shaking OT vibration thereof and the like.
The thusly separated particulate burden is generally conducted into a collection hopper and is periodically removed therefrom for packaging and/or for such further processing as may be desired or necessary to provide a finished paTticulate product. In furnace carbon black processes of commerce, the so-called "fluffy" carbon black collected from the cloth filtration device may be sub-jected to such further treatments as: wet pelletizing;
dry pelleti7ing; densing; calcining; surface o~idizing with ai~, ozone or mineral acids; milling, such as by pin milling, hammer millin~ OT fluid en~rgy milling;
~reating with surfactants 9 oils or oil emulsions and ~he like.
~a.~
~,J ~ I.J'~
The cloth materials utilized to produce the filtra-tion elements are usually composed of woven or unwoven textile fibers such as glass, cotton, wool, polyamide, pol~ester9 polytetrafluoroethylene or blends thereof.
Said materials are formed or sewn into the geometric shapes required of the particular cloth filtration device employed. One commonly employed filtration devïce is a so-called "bag filter", the cloth filtra-tion elements of which are of long tubulaT shape.
Other known cloth filtration devices employ cloth filtration elements in the forms of en~elopes, sheets, bolts OT disks. Certain other known cloth filtra-tion de~ices employ cloth filtration elements which are essentially shapeless, the cloth filtration mater-ial merely being employed in the form of a stuffing orfiller for a cartridge element through which the parti-culate-laden process stream is conducted.
Nhatever the particular cloth ~iltration device used, however, it is essential that the particulate-laden process stream conducted thereinto have a temp-erature which is not so high as to bc deletrious to the cloth filtration elements thereof. Likewise, however, it is also important that the temperature of the process stream conducted into the filtration device be sufficiently high as to maintain the atmosphere within the device at above the dewpoint of the gaseous component of the process stream, the~eby to mitigate against condensation of condensibles therefrom. ~ailure to maintain the former temperature criterion leads, of course, to excessively short cloth filtration element life. ~ailu.e to maintain the latter temperature criterion can lead to collection of adulterated and/or wetted particulate product and to ~..{.~
blinding of the cloth filtration elements, In the case of furnace carbon black operations, the collection of wetted carbon black in the cloth filtration device not only adversely affects the efficiency of the collection 5 step, but also can adversely affect the efficiency and quality of downstTeam finishing operations such as pelletizing, densing OT chemical aftertTeating of the collected carbon black and the quality and unifoTmity of the resulting -finished carbon black product.
~ile it is possible to cool a hot, particlllate-laden process stream to ~ithin the a~oresaid temperature criteria by means of indirect heat exchangers, the~e a-rises the pToblem of efficient and economic operations of such heat exchangers. Normally, the goal temperatures for 15 a particulate-laden process s~ream to ~e treated by cloth ~iltration will range from about 149C to about 371C.
Indirect heat exchange is usually an economically ~us~i-fiable method of heat extraction only when the temperature dTop to be achieved is relatiYely great, for instance, on 20 the order of 300C, or more~ and wh~n the hot process stream to be cooled is at a tempera~ure of substantially above about 538C. Thus, for example, to cool a 538C
particulate-laden process stream to about 260C by an indi-rect heat exchange technique geneTally requires 25 substantial and expensive equipment, the process economics of which are not usually justified even assuming complete recoupment of the extracted heat energy. Moreover~
indirect heat exchange equipment is usually adapted for operations under relatively static process conditions and 30 is therefore, usually ill-adapted foT reasona~ly pTeCiSe contrcl in response to changing process conditions, In view of these foregoing deficiencies, therefo-re, it is 3t~
conventional prac~ice in chemical plant operations to first extract and recoup as much heat from the hot pro- ;
cess stream by indirect heat exchange as is economically feasible and, thereafter, to ~urther quench the pTocess 5 stTeam to suitable cloth filtration temperatures by atom-izing liquid wa~er thereto.
This quenching of the process stream ~o suitable cloth filtration temperatures is normally undertaken by pressure or bi-fluid atomization of the liquid wateT
10 into the process strea~ ~t some point relatively far upstream of the inlet of the cooled s~ream into the cloth filtration device. Atomi~ation, as opposed to spraying, is undertaken in ordeT toperform minute droplets which, of course, evaporate more quickly than the relatively 15 largeT droplets producible by ordinary spraying techniques.
The lengthy conduit interposed between the point of atom-ization sf the cooling water into the process stream and the filtration device is provided or purposes of ensuring adequate time for the liquid water atomizate to evaporate 20 completely prior to entry of the cooled process stream into the cloth filtration device. It is obvious, of course, that failure to completely evaporate the liquid water in the p~ocess stream can lead to dificulties similar ~o those which have herein~efore been discussed 25 with respect to condensation of the gaseous component of the process stream within the cloth filtration device.
The underlying reason for providing a relatively lengthy Tesidence time after atomizing the liquid coolant WateT into the process stream ,esides in the fact that, 30 as far as is kno~ to applicant, neither bi-fluid nor pressuTe atomization techniques currently available in industrial operations lend themselves to the perfoTmance 3~
,, of droplets of minu~e size over a sufficien~ly broad range of process conditions as to gua~antee uniformly rapid and complete evapDration thereof wi~hin the process stream. In pressure atomizat-ion water is forced through a 5 nozzle having a restricted orifice and the efficiency at which the injzcted water is fractured into drople~s and the average size of the droplets so performed are largely dependent upon the orifice si;ze of the atomizing nozzle and the pressure drop achieved across that orifice.
lO In turn, the flow rate of water through an orifice of - given dimensions is, of course, a function of the pressure drop, the higher the pressure drop the greater being the flow rate. Minor variation in any of the foregoing parameters has a very profound effect upon the uniformity 15 and size of the droplets performed, For most induskrial chemical plant installations the orifice size of a given pressure atomizing nozzle may be considered an invarian~
parameter. However, such is not normally the case with respect to flow rates and pressure drops. In industrial 20 plant operations water line pressure and flow rate and the temperature and flow rate of the process stream to be quenched are normally subject to considerable variation.
~'here the hot process stream temperature and/or flow rate is altered, such as due to changes in reactor conditions 25 in order to alter product properties, it is usually also necessary to alter the Tate of quench water atomized in~o the process stream in order to attain the desired goal temperature preparatory to the cloth filtration treatment thereof. Thus, considerable variations in the 30 water pressure delivered to the atomizing nozzles may occur incidentally or by design and can lead to periods of process operation wherein the pressure atomization nozzles are not and cannot be operated up to their design pressure drops and flow rates, Under such conditions, the droplets produced by pressure ~tomization ~echniques can be much enlarged and droplet uniformity diminished, thereby to require substantially increased residence 5 times within the quenched pTocess s~ream so as to ensure complete evaporation of the water therein. Bi-fluid atomization nozzles employ motive gas to fracture a water stream into minute dropiets within the nozzle and to project said droplets, entrained in the motive gas, into 10 the process gas stream. In order to operate efficiently, such bi-fluid nozzles generally employ relatively large volume flow ra~es of the motive gas, which gas is not normally inherently available at the plant site and which gas, in any event, represents an added gas burden in the 15 process stream which must ultimately be handled by the downstream cloth filtration device.
In order to maximize the residence time of the pressure or bi-fluid atomized quench water in the process stream the customary approach, as mentioned, has been to 20 interpose a large volume conduit or so-called "riser"
between the point of atomizat on of the quench water into the process stream and the cloth filtration device. Vnder thcse conditions wherein the droplet size of the atomized quench water is relatively large, the evaporation rate 25 thereof can be much reduced within the process stream flowing through the riser. In furnace carbon black opera-tions such reduced evaporation Tates can lead to increased opportunities for wetting and agglomeration of the parti-culate component of the process stream within the riser 30 and the collection of a carbon black product having sub-stantial quantities of hard coarse agglomerates therein.
Moreover~ in view of the fact that the process stream can ~ 9~
often be highly corrvsive, the riser conduit is often also required to be constructed of expensive corrosion resistant alloys. Neverthe~ess~ the need for avoiding the presence of liquids within the cloth filtration 5 device has heretofoTe outweighed the considerable eco-nomic penalties imposed by the construction and operations of a large volume corrosion resistant alloy riser pre-ceeding same and the danger of encountering the afore-mentioned phenomenon of particulate component agglome-10 ration within the riser and, unti~ the advent of the presentinvention, industry has gTudgingly accepted these defi ciencies so as to assure complete evaporation of the quench water introduced in~o the process stream over a broad range of process conditions.
In accordance with the present invention, many of the aforemen~ioned difficulties are either completely resolved or are at least substantially ameliorated.
Objects of the Invention I~ is a principal object of the invention to pro vide a novel method for cooling a hot particulate-laden 20 gas stream.
It is another object of the invention to provide a novel apparatus for cooling a hot, particulate-laden gas stream.
It is another object of the present invention to 25 provide an improved integrated method for the separa~ion of the particulate component from a hot, particulate-laden process stream.
I~ is another object of the pTeSent inven~ion ~o provide an improved integrated system for the sepa~a-30 tion of the paTticulate component frcm a hot, particu-late-laden process stream.
~?~33~
It is still another object of the present iovention to provide an improved integrated method and system :For the separation of furnace carbon black from a hot, furnace carbon black-containing process stream.
Other objects and advantages of the present inven-tion will in part be obvious and will in part appear hereinafter.
Summary of the Invention In accordance with the present invention, a hot, particulate-laden gas s~ream is conduc~ed ~hrough a venturi-shaped conduit having a size and geometry adapted to accelerate the process stream to a Mach number of at least 0.25. Within the throat portion o~ the venturi-shaped conduit liquid water is injected substantially ~ransversely into said ~as s~ream through a n~ber of unrestricted orificesO By reason of the eneTgetic flow of the process stream at the points of introduction o:E
the liquid water thereinto, the plural streams of water are rapidly fragmented, disintegrated and sheared into uniform droplets of relatively minute size9 thereby extracting heat from the gas stream by rapid evaporation of the thusly performed water droplets. The thusly cooled gas OT process stream is conducted through a cloth filtra-tion device, whereby the particulate component is separated from the gaseous componen~, Brief Description of the ~rawing Figure 1 hereof is a schematic diagrammatic 10w sheet depicting, in solid lines, a cooling apparatus in accordance with the invention integrated into a typical furnace carbon black process line and, in dashed lines, a rela~ively comparativel~ scaled conventional prior 3~ ar~ cooling apparatus.
Figure 2 hereof is a schematic, diagrammatic longitudinal sectional view of the embodiment of the cooling apparatus of the in~ention shown .in Figure 1.
Pigure 3, hereof is an enlarged schematic, diagram-matic longitudinal sectional YieW of a portion of thesooling apparatus sho~l in Figure 2, Description of Preferred Embodiments Referring now to Figure 1 hereof, a conventional furnace carbon black process line is depicted comprising major elemen~s 1, 9~ 14 and 15~ A hydrocarbonaceous feedstock, c~mbustion fuel and a gaseous oxidant (usually air) are in~roduced into a carbon black reactor 1.
Therein the resulting mixture is ignited and the burning reaction mixture passed into refractory lined reac~ion chamber 5 wherein carbon forming conditions are main~ained.
Conventionally, the temperature within reaction chamber 5 is maintained at between about 1315C and about 1760C, the exact temperature being primarily dependent upon the desired properties of the carbon blac~ product. Control of the temperature within reaction chamber 5 is usually achieved by appropriate proportioning of the oxidant, fuel and feedstock delivered to ~eac*or 1. Termination of the carbon forming reaction is initiated by a so-called 'tprimary quench" wherein water is sprayed through no~zle 6 into the reaction mixture as it progresses through the downstream portion of reaction chamber 5O The rate a~
which the quench water is sprayed into the reaction mix-~ure is appropriately proportioned 50 as to rapidly reduce the temperature of the process stream to about 1204C, or less. Since the thermal energy contained in the reaction mixture at this point in the process is relatively high, tD ~L
rapid e~aporation of the primary quench water is inherently assured and the operations of the quench nozzle 6 are not normally critical.
l'he Tesul~ing process stream, compTising carbon 5 black suspended in process flue gases, is then conducted from reactor 1 to an indirect heat e~changer 9 wherein said process stream is fuT~her cooled, usually to a temperature of between a~out 426C and 648C. Indirect heat exchange~ 9 îs conventioncllly cooled by the com~
10 bustion oxidant employed in the carbon blac~ orming pro-~cess, thereby to preheat same prioT to introduction into reac~oT 1 and thereby to l~ecover subs~antial quanti-ties of what would otherwise be waste heat and to improve the thermal efficiency of the overall process.
SeparatioTI of the carbon black from the process stream is conventionally undertaken in a cloth filtra-tion device 15, such as a bag filter~ wheTeby the pTO-cess stream is conducted thTough porous cloth filtTation elements adapted to retain the carbon black burden on 20 the upstream side thereof while allowing the process gases to pass therethrough. The carbon black product separated and collected in cloth filtrat;on device 15 is ~hen packaged or othérwise treated as previously discussed herein.
In order to preserve the cloth filtration elements of the cloth filtration device 15, it is first necessary ~o further cool the still Telatively hot process stream exiting indirect heat exchanger 9~ usually to be~ween about 149~C and about 371C, the exact ~oal ~empera~ure 30 being dictated largely by the dual considerations of the J~
dewpoint. of the gaseous component of the process stream and the thermal stahility of the particular cloth fil-tration elements employed in cloth filtration device 15 The P~ior Art Conventlonally~ this additional cooling or "second-ary quenching" of the furnace carbon black process stream preparatory to cloth filtration thereof is accomplished by conducting the paTtially ccoled pro-cess stream from indirect heat exchanger 9 ~hrough a vertical, lengthy and large ~olume conduit or riser 14 while atomiz;n~ water into the upstream end portion thereof. For purposes of comparison, said riser 14 may, for example, typically have a length of about 30.48m, a diameter of about 1.524m and will usually be constructed of an expensive corrosion-resistant alloy~
Stationed at the upstream end portion of riser 14 are one or more pressure or bi-fluid atomization nozzles 16 through which quench water is atomized into the process stream at a rate sufficient to cool the process stream to the selected goal temperature. The extensive portion of the riser 14 existing downstream from nozzles 16 is provided largely or purposes of ensuring sufficient residence time of the quenched process stream therein as to complete the evaporation of the quench water atomizate prior to entry of the process stream into cloth filtration device 15. For whatever reason, should the atomized water droplets be of a relatively large size say onthe ~rder of about300 X10 6m or more, the evaporation rate thereof in the process stream will be relatively low, theTeby creating significant opportunity for sub-stantial contact of the suspended particulate componen~
3~
carbon black ~ith liquid water during conveyance ofthe process stream through the riser 14, As mentioned previously, should such wetting of the carbon black particles occur, the wctted particles can then collide with one another to fo~n coarse agglomerates. Also, the wetted caTbon black p'articles can contact the walls of the riser 14 7 causing accretion and caking of carbon black thereon.
The Present Invent'ion In accordance with the present invention, referring now to the solid line portion of Figure 1 and to Figures
In many industrial processes products or by-products are prodllced in suspended par~iculate form, ~hat is to say, in the form of a solid particulate matteT component entrained in a hot gas stream component. For instance, 1~ furnace carbon blacks are produced by the thermal decom-position and/or paTtial combustion of hydrocarbonaceous feedstocks and are normally initially produced in the form of an aerosol or suspension of the paTticulate carbon - black product in hot by-product flue gases. The carbon 15 black process stream is quenched in the carbon black' forming reactor to terminate the carbon forming reaction, urther cooled and then treated ~y cloth filtration in order to collect the carbon black product. Some other exemplary industrial processes in which a hot, particulate^
2n laden process stream is cooled and then aubj ected to cloth filtration and to which the present in~ention may be employed with good efect are: treatment of coal fired power plant flue gases prior to filtration of the particu-late burden therefrom, cooling of dry process cemen~ cal-25 cining streams, cooling of calcined ore or rock dust con-taining streams and the like.
~"3~
Typically, cloth filtration methods o~ co~erce in~lve flowing a particulate-laden gaseous s~ream through one or more pOTOUS cloth or fab~ic fil~ration elements, said elements having a selected poTosity or transmissibility which is, at once, sufficient to allow the gaseous component of the process stream ~o pass therethrough while being insufficien~ to allow passage of the particulate component. In consequence, the par~iculate component is separated from the gaseous component and is deposited on the upstream or collection side o-f the cloth fil~ration elemen~s. Means are usually provided by which to aid removal of the particulate burden from the filt~ation elements, such as by periodic repressurization or reversal of the ~as flow therethrough, mechanical shaking OT vibration thereof and the like.
The thusly separated particulate burden is generally conducted into a collection hopper and is periodically removed therefrom for packaging and/or for such further processing as may be desired or necessary to provide a finished paTticulate product. In furnace carbon black processes of commerce, the so-called "fluffy" carbon black collected from the cloth filtration device may be sub-jected to such further treatments as: wet pelletizing;
dry pelleti7ing; densing; calcining; surface o~idizing with ai~, ozone or mineral acids; milling, such as by pin milling, hammer millin~ OT fluid en~rgy milling;
~reating with surfactants 9 oils or oil emulsions and ~he like.
~a.~
~,J ~ I.J'~
The cloth materials utilized to produce the filtra-tion elements are usually composed of woven or unwoven textile fibers such as glass, cotton, wool, polyamide, pol~ester9 polytetrafluoroethylene or blends thereof.
Said materials are formed or sewn into the geometric shapes required of the particular cloth filtration device employed. One commonly employed filtration devïce is a so-called "bag filter", the cloth filtra-tion elements of which are of long tubulaT shape.
Other known cloth filtration devices employ cloth filtration elements in the forms of en~elopes, sheets, bolts OT disks. Certain other known cloth filtra-tion de~ices employ cloth filtration elements which are essentially shapeless, the cloth filtration mater-ial merely being employed in the form of a stuffing orfiller for a cartridge element through which the parti-culate-laden process stream is conducted.
Nhatever the particular cloth ~iltration device used, however, it is essential that the particulate-laden process stream conducted thereinto have a temp-erature which is not so high as to bc deletrious to the cloth filtration elements thereof. Likewise, however, it is also important that the temperature of the process stream conducted into the filtration device be sufficiently high as to maintain the atmosphere within the device at above the dewpoint of the gaseous component of the process stream, the~eby to mitigate against condensation of condensibles therefrom. ~ailure to maintain the former temperature criterion leads, of course, to excessively short cloth filtration element life. ~ailu.e to maintain the latter temperature criterion can lead to collection of adulterated and/or wetted particulate product and to ~..{.~
blinding of the cloth filtration elements, In the case of furnace carbon black operations, the collection of wetted carbon black in the cloth filtration device not only adversely affects the efficiency of the collection 5 step, but also can adversely affect the efficiency and quality of downstTeam finishing operations such as pelletizing, densing OT chemical aftertTeating of the collected carbon black and the quality and unifoTmity of the resulting -finished carbon black product.
~ile it is possible to cool a hot, particlllate-laden process stream to ~ithin the a~oresaid temperature criteria by means of indirect heat exchangers, the~e a-rises the pToblem of efficient and economic operations of such heat exchangers. Normally, the goal temperatures for 15 a particulate-laden process s~ream to ~e treated by cloth ~iltration will range from about 149C to about 371C.
Indirect heat exchange is usually an economically ~us~i-fiable method of heat extraction only when the temperature dTop to be achieved is relatiYely great, for instance, on 20 the order of 300C, or more~ and wh~n the hot process stream to be cooled is at a tempera~ure of substantially above about 538C. Thus, for example, to cool a 538C
particulate-laden process stream to about 260C by an indi-rect heat exchange technique geneTally requires 25 substantial and expensive equipment, the process economics of which are not usually justified even assuming complete recoupment of the extracted heat energy. Moreover~
indirect heat exchange equipment is usually adapted for operations under relatively static process conditions and 30 is therefore, usually ill-adapted foT reasona~ly pTeCiSe contrcl in response to changing process conditions, In view of these foregoing deficiencies, therefo-re, it is 3t~
conventional prac~ice in chemical plant operations to first extract and recoup as much heat from the hot pro- ;
cess stream by indirect heat exchange as is economically feasible and, thereafter, to ~urther quench the pTocess 5 stTeam to suitable cloth filtration temperatures by atom-izing liquid wa~er thereto.
This quenching of the process stream ~o suitable cloth filtration temperatures is normally undertaken by pressure or bi-fluid atomization of the liquid wateT
10 into the process strea~ ~t some point relatively far upstream of the inlet of the cooled s~ream into the cloth filtration device. Atomi~ation, as opposed to spraying, is undertaken in ordeT toperform minute droplets which, of course, evaporate more quickly than the relatively 15 largeT droplets producible by ordinary spraying techniques.
The lengthy conduit interposed between the point of atom-ization sf the cooling water into the process stream and the filtration device is provided or purposes of ensuring adequate time for the liquid water atomizate to evaporate 20 completely prior to entry of the cooled process stream into the cloth filtration device. It is obvious, of course, that failure to completely evaporate the liquid water in the p~ocess stream can lead to dificulties similar ~o those which have herein~efore been discussed 25 with respect to condensation of the gaseous component of the process stream within the cloth filtration device.
The underlying reason for providing a relatively lengthy Tesidence time after atomizing the liquid coolant WateT into the process stream ,esides in the fact that, 30 as far as is kno~ to applicant, neither bi-fluid nor pressuTe atomization techniques currently available in industrial operations lend themselves to the perfoTmance 3~
,, of droplets of minu~e size over a sufficien~ly broad range of process conditions as to gua~antee uniformly rapid and complete evapDration thereof wi~hin the process stream. In pressure atomizat-ion water is forced through a 5 nozzle having a restricted orifice and the efficiency at which the injzcted water is fractured into drople~s and the average size of the droplets so performed are largely dependent upon the orifice si;ze of the atomizing nozzle and the pressure drop achieved across that orifice.
lO In turn, the flow rate of water through an orifice of - given dimensions is, of course, a function of the pressure drop, the higher the pressure drop the greater being the flow rate. Minor variation in any of the foregoing parameters has a very profound effect upon the uniformity 15 and size of the droplets performed, For most induskrial chemical plant installations the orifice size of a given pressure atomizing nozzle may be considered an invarian~
parameter. However, such is not normally the case with respect to flow rates and pressure drops. In industrial 20 plant operations water line pressure and flow rate and the temperature and flow rate of the process stream to be quenched are normally subject to considerable variation.
~'here the hot process stream temperature and/or flow rate is altered, such as due to changes in reactor conditions 25 in order to alter product properties, it is usually also necessary to alter the Tate of quench water atomized in~o the process stream in order to attain the desired goal temperature preparatory to the cloth filtration treatment thereof. Thus, considerable variations in the 30 water pressure delivered to the atomizing nozzles may occur incidentally or by design and can lead to periods of process operation wherein the pressure atomization nozzles are not and cannot be operated up to their design pressure drops and flow rates, Under such conditions, the droplets produced by pressure ~tomization ~echniques can be much enlarged and droplet uniformity diminished, thereby to require substantially increased residence 5 times within the quenched pTocess s~ream so as to ensure complete evaporation of the water therein. Bi-fluid atomization nozzles employ motive gas to fracture a water stream into minute dropiets within the nozzle and to project said droplets, entrained in the motive gas, into 10 the process gas stream. In order to operate efficiently, such bi-fluid nozzles generally employ relatively large volume flow ra~es of the motive gas, which gas is not normally inherently available at the plant site and which gas, in any event, represents an added gas burden in the 15 process stream which must ultimately be handled by the downstream cloth filtration device.
In order to maximize the residence time of the pressure or bi-fluid atomized quench water in the process stream the customary approach, as mentioned, has been to 20 interpose a large volume conduit or so-called "riser"
between the point of atomizat on of the quench water into the process stream and the cloth filtration device. Vnder thcse conditions wherein the droplet size of the atomized quench water is relatively large, the evaporation rate 25 thereof can be much reduced within the process stream flowing through the riser. In furnace carbon black opera-tions such reduced evaporation Tates can lead to increased opportunities for wetting and agglomeration of the parti-culate component of the process stream within the riser 30 and the collection of a carbon black product having sub-stantial quantities of hard coarse agglomerates therein.
Moreover~ in view of the fact that the process stream can ~ 9~
often be highly corrvsive, the riser conduit is often also required to be constructed of expensive corrosion resistant alloys. Neverthe~ess~ the need for avoiding the presence of liquids within the cloth filtration 5 device has heretofoTe outweighed the considerable eco-nomic penalties imposed by the construction and operations of a large volume corrosion resistant alloy riser pre-ceeding same and the danger of encountering the afore-mentioned phenomenon of particulate component agglome-10 ration within the riser and, unti~ the advent of the presentinvention, industry has gTudgingly accepted these defi ciencies so as to assure complete evaporation of the quench water introduced in~o the process stream over a broad range of process conditions.
In accordance with the present invention, many of the aforemen~ioned difficulties are either completely resolved or are at least substantially ameliorated.
Objects of the Invention I~ is a principal object of the invention to pro vide a novel method for cooling a hot particulate-laden 20 gas stream.
It is another object of the invention to provide a novel apparatus for cooling a hot, particulate-laden gas stream.
It is another object of the present invention to 25 provide an improved integrated method for the separa~ion of the particulate component from a hot, particulate-laden process stream.
I~ is another object of the pTeSent inven~ion ~o provide an improved integrated system for the sepa~a-30 tion of the paTticulate component frcm a hot, particu-late-laden process stream.
~?~33~
It is still another object of the present iovention to provide an improved integrated method and system :For the separation of furnace carbon black from a hot, furnace carbon black-containing process stream.
Other objects and advantages of the present inven-tion will in part be obvious and will in part appear hereinafter.
Summary of the Invention In accordance with the present invention, a hot, particulate-laden gas s~ream is conduc~ed ~hrough a venturi-shaped conduit having a size and geometry adapted to accelerate the process stream to a Mach number of at least 0.25. Within the throat portion o~ the venturi-shaped conduit liquid water is injected substantially ~ransversely into said ~as s~ream through a n~ber of unrestricted orificesO By reason of the eneTgetic flow of the process stream at the points of introduction o:E
the liquid water thereinto, the plural streams of water are rapidly fragmented, disintegrated and sheared into uniform droplets of relatively minute size9 thereby extracting heat from the gas stream by rapid evaporation of the thusly performed water droplets. The thusly cooled gas OT process stream is conducted through a cloth filtra-tion device, whereby the particulate component is separated from the gaseous componen~, Brief Description of the ~rawing Figure 1 hereof is a schematic diagrammatic 10w sheet depicting, in solid lines, a cooling apparatus in accordance with the invention integrated into a typical furnace carbon black process line and, in dashed lines, a rela~ively comparativel~ scaled conventional prior 3~ ar~ cooling apparatus.
Figure 2 hereof is a schematic, diagrammatic longitudinal sectional view of the embodiment of the cooling apparatus of the in~ention shown .in Figure 1.
Pigure 3, hereof is an enlarged schematic, diagram-matic longitudinal sectional YieW of a portion of thesooling apparatus sho~l in Figure 2, Description of Preferred Embodiments Referring now to Figure 1 hereof, a conventional furnace carbon black process line is depicted comprising major elemen~s 1, 9~ 14 and 15~ A hydrocarbonaceous feedstock, c~mbustion fuel and a gaseous oxidant (usually air) are in~roduced into a carbon black reactor 1.
Therein the resulting mixture is ignited and the burning reaction mixture passed into refractory lined reac~ion chamber 5 wherein carbon forming conditions are main~ained.
Conventionally, the temperature within reaction chamber 5 is maintained at between about 1315C and about 1760C, the exact temperature being primarily dependent upon the desired properties of the carbon blac~ product. Control of the temperature within reaction chamber 5 is usually achieved by appropriate proportioning of the oxidant, fuel and feedstock delivered to ~eac*or 1. Termination of the carbon forming reaction is initiated by a so-called 'tprimary quench" wherein water is sprayed through no~zle 6 into the reaction mixture as it progresses through the downstream portion of reaction chamber 5O The rate a~
which the quench water is sprayed into the reaction mix-~ure is appropriately proportioned 50 as to rapidly reduce the temperature of the process stream to about 1204C, or less. Since the thermal energy contained in the reaction mixture at this point in the process is relatively high, tD ~L
rapid e~aporation of the primary quench water is inherently assured and the operations of the quench nozzle 6 are not normally critical.
l'he Tesul~ing process stream, compTising carbon 5 black suspended in process flue gases, is then conducted from reactor 1 to an indirect heat e~changer 9 wherein said process stream is fuT~her cooled, usually to a temperature of between a~out 426C and 648C. Indirect heat exchange~ 9 îs conventioncllly cooled by the com~
10 bustion oxidant employed in the carbon blac~ orming pro-~cess, thereby to preheat same prioT to introduction into reac~oT 1 and thereby to l~ecover subs~antial quanti-ties of what would otherwise be waste heat and to improve the thermal efficiency of the overall process.
SeparatioTI of the carbon black from the process stream is conventionally undertaken in a cloth filtra-tion device 15, such as a bag filter~ wheTeby the pTO-cess stream is conducted thTough porous cloth filtTation elements adapted to retain the carbon black burden on 20 the upstream side thereof while allowing the process gases to pass therethrough. The carbon black product separated and collected in cloth filtrat;on device 15 is ~hen packaged or othérwise treated as previously discussed herein.
In order to preserve the cloth filtration elements of the cloth filtration device 15, it is first necessary ~o further cool the still Telatively hot process stream exiting indirect heat exchanger 9~ usually to be~ween about 149~C and about 371C, the exact ~oal ~empera~ure 30 being dictated largely by the dual considerations of the J~
dewpoint. of the gaseous component of the process stream and the thermal stahility of the particular cloth fil-tration elements employed in cloth filtration device 15 The P~ior Art Conventlonally~ this additional cooling or "second-ary quenching" of the furnace carbon black process stream preparatory to cloth filtration thereof is accomplished by conducting the paTtially ccoled pro-cess stream from indirect heat exchanger 9 ~hrough a vertical, lengthy and large ~olume conduit or riser 14 while atomiz;n~ water into the upstream end portion thereof. For purposes of comparison, said riser 14 may, for example, typically have a length of about 30.48m, a diameter of about 1.524m and will usually be constructed of an expensive corrosion-resistant alloy~
Stationed at the upstream end portion of riser 14 are one or more pressure or bi-fluid atomization nozzles 16 through which quench water is atomized into the process stream at a rate sufficient to cool the process stream to the selected goal temperature. The extensive portion of the riser 14 existing downstream from nozzles 16 is provided largely or purposes of ensuring sufficient residence time of the quenched process stream therein as to complete the evaporation of the quench water atomizate prior to entry of the process stream into cloth filtration device 15. For whatever reason, should the atomized water droplets be of a relatively large size say onthe ~rder of about300 X10 6m or more, the evaporation rate thereof in the process stream will be relatively low, theTeby creating significant opportunity for sub-stantial contact of the suspended particulate componen~
3~
carbon black ~ith liquid water during conveyance ofthe process stream through the riser 14, As mentioned previously, should such wetting of the carbon black particles occur, the wctted particles can then collide with one another to fo~n coarse agglomerates. Also, the wetted caTbon black p'articles can contact the walls of the riser 14 7 causing accretion and caking of carbon black thereon.
The Present Invent'ion In accordance with the present invention, referring now to the solid line portion of Figure 1 and to Figures
2 and 3~ generally, and in all of which figures like reference numerals refer to like structures, the rela-tively hot, particulate-laden process stream exiting indirect heat exchanger 9 is conducted through a venturi-shaped conduit 20 having a geometry and shape adaptedto accelerate said stream to a Mach number of at lea~t about 0.25 within the throat portion 24 thereof. By "Mach number" is meant the dimensionless numerical quotient of the actual velocity of the process stream divided by the local velocity of sound within said stream. Thus~ the Mach number of the process stream is both temperature and composition dependent and can be Teadily determined for any given set of circumstances by taXing the temperature and composition of the parti-cular process stream involved into full consideration.Desirably, the size and geometry of the venturi-shaped conduit 20 will be selected such as to accelerate the process stream to a Mach numbeT of at least 0.4 within throat portion 24.
3~
The venturi-shaped conduit 20 comprises a rela-tively rapidly convergent upstream portion 22, a throat portion 24 and a relatively gen~,ly divergent downstream portion 26. In the particular embodiment of the inven-tion shown in the drawing there is centrally locatedalong the longitudinal eenterline of throat portion 24 a supply pipe 25 which ~erminates in an end-cap 27.
Supply pipe 25 is braced in its central position by means of a strut 28 extending from the wall of conver-gent portion 22 of the venturi-shaped condui~ 20. End-cap 27 comprises a plurality of unrestricted orifices 29 which are radially oriented relative ts the longitu-dinal centerline of the ven~uri-shaped conduit 2,0 and through which orifices 29 liquid quench wa~er is intro-duced substantially transversely into the process streamflowin~ throllgh throat portion 24. Control of the quench water flow rate through orifices 29 may be provided by the combination of water supply valve 50 and oontToller 51.
Controller -51 receives process st~eam temperature data from outlet thermocouple To, integrates said data with respect to a preselected goal OT set point temperature and responds by adjusting water supply valve 50 as neces-sary to obtain the set point tempera~ure of the quenched process stream. Since the present invention depends primarily on the kinetic energy of the accelerated process strea~ to fracture the quench water into minute droplets and to disperse said droplets within said stream, the diameter(s) of unrestricted orifices 29 and $he pressuTe (or flow rate) at which the quench water is supplied therethrough are subject to conside~able vaTia-tion and are normally non-critical as regaTds the .f~ t'P~
.performance of minutc, uniform and rapidly evaporable droplets within the process stream. This beneficial feature of the pTeSent inventi.on is a marked departure from the criticalities normally attendant opera~ions of pressuTe or bi-fluid atomi~ation nozzles of the prior art. Desirably, the number and diameter(s) of orifices 29 will be selected such that 9 under ~he contemplated range of quench water rates involved in the particulaT
process under consideration, sufficient pressure will be developed at each of said orifices 29 as to project the resulting quench water stream therefrom into the process stream to at least a small distance from the surface of end-cap 27 prioT to substantial disin~egra-tion and breakup of said quench water stream.
The included angle of divergence of the divergent portion 26 of the venturi-shaped conduit 2G is generally non-critical. However, it is preferred that said an~le of divergence reside within the Tange of between about 6 and about 14 and, even more preferably, in the range of between about 7 and about 10. By adherence to these preferred limits said diveTgent por~ion 26 will generally act as a diffuser, thereby to minimize the pressure drop geneTated across conduit 20 for a given acceleration of the process stream and ~o extend the length over which said process stream maintains high velocity. In another preferred embodiment of the invention at least the divergent portion 26 of ven~u~i-shaped conduit 20 is thermally insulated~ such as by means of lagging 30. Said insulation 30 serves to reduce the thermal deposition driving forces of the hot process stream9 which fOTCe5 might otherwise tend to cause at least some deposition of the particulate component thereof on the surfaces immediately downstream of ~hroat portion 74.
3~
In another preferred embodiment of the invention the u~stream end of conver~ent por~ion 22 of the.ven-tuTl-shapecl conduit 20 is fed by a sho~t length o~
conduit 18 containing flow-Tectifying means l9 ~h$rein.
The provision of such flow rectifying means immediately prior to the ~enturi-shaped condui-t 20 minimizes turbu-lences and eddy currents within the process StTeam as it approaches said conduit 207 thereby ~o ensure effi-cient aoceleration therein.
In view of the extremely rapid disintegration and evapOTation of the quench water introduced into the process stream in accordance with the invention, both the venturi-shaped conduit 20 and ~he conduit 31, which defines the commwlication between the downstream end of said conduit 20 and the inlet of c:loth filtTation devicc 15, can be substantially more compact, on an equal process scale basis, than the riser type secondary quench;ng systems of the prior art. This represents a substantial advantage accruing to the practice of the present invention since, as previously indicated, the secondary quench TiseT systems of the prior art usually involve apparatuses of relat;vely very large lengths and volumes Util.izing the process and apparatus of the present invention, for example, a furnace carbon black process stream of the same type contemplated in the sizing of ~he rise~ 14 previously discussed herein in the paragraph entitled~ "The Prior Art", can be effectively cooled to goal tempeTatuTe in a venturi-conduit 20 of the present invention having inlet and 3D outlet diameters of about 0.~128m, a throat diameter of about 0.4064m and an overall length of between about 3.6576m to about 4.572m. The length or volume of con-dui~ 31, moTeoveT~ is dictated substantially only by the need for fluid-~ight communication of the cooled pro-cess stream into the cloth filtration device lS. Moreover, the apparatus ~f the in~ention need not be oriented verti-cally as in the Tisers o:E the prior art, but rather may be subjected to whate~er orientation thereo may present it-self as appropriate based on consideTations of available space and efficient plant layout.
Additionally, the present invention exhibits sub~
stantially less sensi~ivity ~o p~ocess s~ream inlet temperature variation than does the prior ar~ riser technique employing pressure atomizing of the quench water. Utilizing the la~ter pTior ar~ method a decrease in the inlet tempeTature of the process stream fed to riser 14 of about 38C, for example, reduces the rate of water required to be p~essure atomized into the process stream to attain goal temperature by about 20~.
If the water pressure is reduced 50 as to adjust the rate of water flow downwardly by 20%,however, the average droplet size of apressure-atomized spray is maTkedly inc~eased as is the residence time required to evapoTate such larger droplets and the Yolume of downstream enclos-ing conduit ~equired to pTovide such increased resid~nce time. U ilizing the process and apparatus of the present invention, howeveT, a similar reduction of inlet temp-era~uTe of the process stream and a similar reductionof ~he quench wate~ rate Tesults in only a relatively minor increase in d~oplet size and in only a relatively minor increase in the residence time ~equired to achieYe complete evapo~ation of the droplets. Thu~, unlike prioT art riser systems, little or no additiona~ length or vol~me of downstream conduit need ordinarily be built into the apparatus of the present invention simply to provide an adequate residence time buffer for complete quench water evapoTation in response to temperature and flow changes in the p~ocess and quench water s~reams.
Also, while the shearing and disintegration of the quench water introduced into the p~ocess stream in consequence of the practice o~ the present invention may be termed a type cf bi-~luid atomization, the motive gas for ~he 3~
atomization of the quench water is not an external diluent, the process stream and motive gas being one and the same entity. Thus, the present process and system avoids further dilu~ion of the process s~ream and the need for augmentation of the gas handling capacity of the cloth filtration device 15.
While for purposes of illustration the present invention has been described hereinbefore in detail only with respect to a furnace carbon black process line and only in terms of ultimate sepaTation of the particulate component by cloth filtration, i~ is obvious that the present invention can be beneficially applied to many other chemical process lines wherein it is Tequired to cool a hot gaseous process stream containing particulate solids suspended therein.
Also, while the present invention has been described hereinbefore with respect to certain preferred embodi-ments thereof, it it to be noted that the Eoregoing descTiption is intended to be illustrative in natu~e and not as being limiting of the invention. For instance, while the specific apparatus shown and described com-prises a centrally located end-cap 27 within the throat portion 24 of venturi-shaped conduit 207 which end-cap 27 serves as the final element for the introdu~tion Z5 of the quench wate~ into the process stream, it is obvious that other functional equivalents of this arrange-ment can be achieved. For instance 9 the means to in~ro-duce the quench water can also take the form of a plurali~y of radial quench water orifices penetrating through the enclosing wall and positioned about t}le peTiphery~of throat portion 24 of venturi-shaped conduit 20. Said orifices may then be enclosed by a common manifold equip-ped with a water supply line thereto.
3~
Obviously, many other suitable alternative and equi~alent constTuctionS of the apparatus and method of the invention will suggest themselves to those of sXill in the art and it should be understood that all S such chan~es, alterations, modifications and the like are intended to fall within ~he essential spirit and scope of the invention as defined in ~he appended claims.
The venturi-shaped conduit 20 comprises a rela-tively rapidly convergent upstream portion 22, a throat portion 24 and a relatively gen~,ly divergent downstream portion 26. In the particular embodiment of the inven-tion shown in the drawing there is centrally locatedalong the longitudinal eenterline of throat portion 24 a supply pipe 25 which ~erminates in an end-cap 27.
Supply pipe 25 is braced in its central position by means of a strut 28 extending from the wall of conver-gent portion 22 of the venturi-shaped condui~ 20. End-cap 27 comprises a plurality of unrestricted orifices 29 which are radially oriented relative ts the longitu-dinal centerline of the ven~uri-shaped conduit 2,0 and through which orifices 29 liquid quench wa~er is intro-duced substantially transversely into the process streamflowin~ throllgh throat portion 24. Control of the quench water flow rate through orifices 29 may be provided by the combination of water supply valve 50 and oontToller 51.
Controller -51 receives process st~eam temperature data from outlet thermocouple To, integrates said data with respect to a preselected goal OT set point temperature and responds by adjusting water supply valve 50 as neces-sary to obtain the set point tempera~ure of the quenched process stream. Since the present invention depends primarily on the kinetic energy of the accelerated process strea~ to fracture the quench water into minute droplets and to disperse said droplets within said stream, the diameter(s) of unrestricted orifices 29 and $he pressuTe (or flow rate) at which the quench water is supplied therethrough are subject to conside~able vaTia-tion and are normally non-critical as regaTds the .f~ t'P~
.performance of minutc, uniform and rapidly evaporable droplets within the process stream. This beneficial feature of the pTeSent inventi.on is a marked departure from the criticalities normally attendant opera~ions of pressuTe or bi-fluid atomi~ation nozzles of the prior art. Desirably, the number and diameter(s) of orifices 29 will be selected such that 9 under ~he contemplated range of quench water rates involved in the particulaT
process under consideration, sufficient pressure will be developed at each of said orifices 29 as to project the resulting quench water stream therefrom into the process stream to at least a small distance from the surface of end-cap 27 prioT to substantial disin~egra-tion and breakup of said quench water stream.
The included angle of divergence of the divergent portion 26 of the venturi-shaped conduit 2G is generally non-critical. However, it is preferred that said an~le of divergence reside within the Tange of between about 6 and about 14 and, even more preferably, in the range of between about 7 and about 10. By adherence to these preferred limits said diveTgent por~ion 26 will generally act as a diffuser, thereby to minimize the pressure drop geneTated across conduit 20 for a given acceleration of the process stream and ~o extend the length over which said process stream maintains high velocity. In another preferred embodiment of the invention at least the divergent portion 26 of ven~u~i-shaped conduit 20 is thermally insulated~ such as by means of lagging 30. Said insulation 30 serves to reduce the thermal deposition driving forces of the hot process stream9 which fOTCe5 might otherwise tend to cause at least some deposition of the particulate component thereof on the surfaces immediately downstream of ~hroat portion 74.
3~
In another preferred embodiment of the invention the u~stream end of conver~ent por~ion 22 of the.ven-tuTl-shapecl conduit 20 is fed by a sho~t length o~
conduit 18 containing flow-Tectifying means l9 ~h$rein.
The provision of such flow rectifying means immediately prior to the ~enturi-shaped condui-t 20 minimizes turbu-lences and eddy currents within the process StTeam as it approaches said conduit 207 thereby ~o ensure effi-cient aoceleration therein.
In view of the extremely rapid disintegration and evapOTation of the quench water introduced into the process stream in accordance with the invention, both the venturi-shaped conduit 20 and ~he conduit 31, which defines the commwlication between the downstream end of said conduit 20 and the inlet of c:loth filtTation devicc 15, can be substantially more compact, on an equal process scale basis, than the riser type secondary quench;ng systems of the prior art. This represents a substantial advantage accruing to the practice of the present invention since, as previously indicated, the secondary quench TiseT systems of the prior art usually involve apparatuses of relat;vely very large lengths and volumes Util.izing the process and apparatus of the present invention, for example, a furnace carbon black process stream of the same type contemplated in the sizing of ~he rise~ 14 previously discussed herein in the paragraph entitled~ "The Prior Art", can be effectively cooled to goal tempeTatuTe in a venturi-conduit 20 of the present invention having inlet and 3D outlet diameters of about 0.~128m, a throat diameter of about 0.4064m and an overall length of between about 3.6576m to about 4.572m. The length or volume of con-dui~ 31, moTeoveT~ is dictated substantially only by the need for fluid-~ight communication of the cooled pro-cess stream into the cloth filtration device lS. Moreover, the apparatus ~f the in~ention need not be oriented verti-cally as in the Tisers o:E the prior art, but rather may be subjected to whate~er orientation thereo may present it-self as appropriate based on consideTations of available space and efficient plant layout.
Additionally, the present invention exhibits sub~
stantially less sensi~ivity ~o p~ocess s~ream inlet temperature variation than does the prior ar~ riser technique employing pressure atomizing of the quench water. Utilizing the la~ter pTior ar~ method a decrease in the inlet tempeTature of the process stream fed to riser 14 of about 38C, for example, reduces the rate of water required to be p~essure atomized into the process stream to attain goal temperature by about 20~.
If the water pressure is reduced 50 as to adjust the rate of water flow downwardly by 20%,however, the average droplet size of apressure-atomized spray is maTkedly inc~eased as is the residence time required to evapoTate such larger droplets and the Yolume of downstream enclos-ing conduit ~equired to pTovide such increased resid~nce time. U ilizing the process and apparatus of the present invention, howeveT, a similar reduction of inlet temp-era~uTe of the process stream and a similar reductionof ~he quench wate~ rate Tesults in only a relatively minor increase in d~oplet size and in only a relatively minor increase in the residence time ~equired to achieYe complete evapo~ation of the droplets. Thu~, unlike prioT art riser systems, little or no additiona~ length or vol~me of downstream conduit need ordinarily be built into the apparatus of the present invention simply to provide an adequate residence time buffer for complete quench water evapoTation in response to temperature and flow changes in the p~ocess and quench water s~reams.
Also, while the shearing and disintegration of the quench water introduced into the p~ocess stream in consequence of the practice o~ the present invention may be termed a type cf bi-~luid atomization, the motive gas for ~he 3~
atomization of the quench water is not an external diluent, the process stream and motive gas being one and the same entity. Thus, the present process and system avoids further dilu~ion of the process s~ream and the need for augmentation of the gas handling capacity of the cloth filtration device 15.
While for purposes of illustration the present invention has been described hereinbefore in detail only with respect to a furnace carbon black process line and only in terms of ultimate sepaTation of the particulate component by cloth filtration, i~ is obvious that the present invention can be beneficially applied to many other chemical process lines wherein it is Tequired to cool a hot gaseous process stream containing particulate solids suspended therein.
Also, while the present invention has been described hereinbefore with respect to certain preferred embodi-ments thereof, it it to be noted that the Eoregoing descTiption is intended to be illustrative in natu~e and not as being limiting of the invention. For instance, while the specific apparatus shown and described com-prises a centrally located end-cap 27 within the throat portion 24 of venturi-shaped conduit 207 which end-cap 27 serves as the final element for the introdu~tion Z5 of the quench wate~ into the process stream, it is obvious that other functional equivalents of this arrange-ment can be achieved. For instance 9 the means to in~ro-duce the quench water can also take the form of a plurali~y of radial quench water orifices penetrating through the enclosing wall and positioned about t}le peTiphery~of throat portion 24 of venturi-shaped conduit 20. Said orifices may then be enclosed by a common manifold equip-ped with a water supply line thereto.
3~
Obviously, many other suitable alternative and equi~alent constTuctionS of the apparatus and method of the invention will suggest themselves to those of sXill in the art and it should be understood that all S such chan~es, alterations, modifications and the like are intended to fall within ~he essential spirit and scope of the invention as defined in ~he appended claims.
Claims (34)
1. A method for cooling a hot, particulate-laden gas stream in preparation, for collection of the particulate component therefrom which comprises atomizing liquid water into said stream in such quantity as to extract heat from said stream by evaporation of the liquid water so atomized thereinto and cool said stream to a temperature above the dewpoint thereof, characterized in that said hot, parti-culate-laden gas stream is conducted through a relatively compact venturi-shaped conduit comprising an upstream con-vergent portion, a downstream divergent portion and a throat portion therebetween, accelerating said gas stream to a Mach number of at least about 0.25 in said throat portion and, in said throat portion, introducing sub-stantially transversely into said gas stream said cooling water to be atomized as a plurality of streams thereof.
2. The method of claim 1, wherein, in said throat portion, said hot, particulate-laden gas stream is accelerated to a Mach number of at least about 0.4.
3. The method of claim 1, wherein said liquid water is introduced substantially transversely and out-wardly into said gas stream from a centrally located element within said throat portion, said element having a plurality of radially oriented unrestricted orifices.
4. The method of claim 3, wherein the rate of water introduced from said element is sufficient to pro-ject each of the resulting streams of liquid water into said gas stream to at least a small distance from the surface of said element prior to substantial disintegration and breakup thereof.
5. The method of claim 1, wherein said downstream divergent portion has an included angle within the range of about 6 and about 14°.
6. The method of claim 1, wherein at least the downstream divergent portion of said venturi-shaped conduit is thermally insulated.
7. The method of claim 1, wherein substantially immediately preceeding introduction of the hot, parti-culate-laden gas stream into the convergent upstream portion of the venturi-shaped conduit, the flow of said gas stream is rectified to reduce eddy currents and turbulences therein.
8. The method of claim 1, 2 or 3, wherein said hot, particulate-laden gas stream is a furnace carbon black process stream.
9. The method of claim 4, 5 or 6, wherein said hot, particulate-laden gas stream is a furnace carbon black process stream.
10. The method of claim 7, wherein said hot, particulate-laden gas stream is a furnace carbon black process stream.
11. An integrated method for the separation of a particulate component from a hot, particulate-laden gas stream which comprises cooling said hot, parti-culate-laden gas by atomizing liquid water into said stream, thereby to extract heat from said stream by evaporation of the liquid water so atomized thereinto, and then conducting the thusly cooled particulate-laden stream through a cloth filtration device, the quantity of water so atomized being sufficient to cool the stream to a temperature sufficiently low as to prevent damage to the cloth filtration elements of said device but being sufficiently high as to maintain the atmosphere within said device at above the dew-point of the gaseous component of said particulate-laden gas stream, characterized in that said hot, particulate-laden gas stream is cooled by conducting same through a relatively compact, venturi-shaped conduit comprising an upstream convergent portion, a downstream divergent portion and a throat portion therebetween, accelerating said stream to a Mach number of at least about 0.25 in said throat portion and, in said throat portion, introducing sub-stantially transversely into said gas stream a plurality of streams of said water to be atomized, the rate of liquid water so introduced being proportioned to cool said stream to within the aforedescribed limits.
12. The integrated method of claim 11, wherein, in said throat portion, said hot, particulate-laden gas stream is accelerated to a Mach number of at least about 0.4. -22-
13. The integrated method of claim 11, wherein said cloth filtration device is a bag filter.
14. The integrated method of claim 11, wherein said liquid water is introduced substantially trans-versely and outwardly into said gas stream through a centrally located element within said throat portion said element within said throat portion, said element having a plurality of radially oriented unrestricted orifices.
15. The integrated method of claim 14, wherein the rate of water introduced from said element is sufficient to project each of the resulting streams of liquid water into said gas stream to at least a small distance from the surface of said element prior to substantial disintegration and breakup thereof.
16. The integrated method of claim 11, wherein the temperature of the cooled gas stream is continuously monitored and wherein the rate of water introduced into the hot, particulate-laden gas stream is adjusted in response thereto.
17. The integrated method of claim 11, wherein said downstream divergent portion has an included angle within the range of between about 6 and about 14°.
18. The integrated method of claim 11, wherein at least the downstream divergent portion of said verturi-shaped conduit is thermally insulated.
19. The integrated method of claim 11, wherein, substantially immediately preceeding introduction of the hot, particulate-laden gas stream into the upstream convergent portion of the venturi-shaped conduit, the flow of said gas stream is rectified to reduce eddy currents and turbulences therein.
20. The integrated method of claim 11, 12 or 13, wherein said hot, particulate-laden gas stream is a furnace carbon black process stream.
21. The integrated method of claim 14, 15 or 16, wherein said hot, particulate-laden gas stream is a furnace carbon black process stream.
22. The integrated method of claim 17, 18 or 19, wherein said hot, particulate-laden gas stream is a furnace carbon black process stream.
23. An integrated system for the separation of a particulate component from a hot, particulate-laden gas stream comprising a conduit adapted to receive a hot, particulate-laden gas stream therethrough and means to atomize liquid water into said gas stream flowing through said conduit, thereby to cool same by evaporation of the atomized liquid water therein, and a cloth filtration device to receive the thusly cooled particulate-laden gas stream from said conduit and to separate the particulate component from the gaseous component thereof, characterized in that said conduit comprises a relatively compact venturi-shaped conduit having an upstream convergent portion, a downstream divergent portion and a throat portion therebetween, said venturi-shaped conduit being of a size and shape adapted to accelerate a hot, particulate-laden gas stream to a Mach number of at least about 0.25 within the throat portion thereof and means to introduce a plurality of streams of liquid water substantially transversely into said gas stream in said throat portion at a rate proportioned to cool said gas stream sufficiently to prevent damage to the cloth filtration elements of said cloth filtration device but to maintain the temperature of the atmosphere within said cloth filtration device at above the dew-point of the gaseous component of the cooled gas stream.
24. The integrated system of claim 23, wherein said cloth filtration device is a bag filter.
25. The integrated system of claim 23, further including flow rectifying means located substantially immediately upstream from said upstream convergent portion of said venturi-shaped conduit, said flow rectifying means being adapted to reduce eddy currents and turbulences in the hot, particulate-laden gas stream.
26. The integrated system of claim 23, wherein said downstream divergent portion of said verturi-shaped conduit has an included angle within the range of about 6 and about 14°.
27. The integrated system of claim 23, wherein said means to introduce a plurality of streams of liquid water comprises an element located centrally within said throat portion of said venturi-shaped conduit said element comprising a plurality of radially oriented unrestricted orifices, and a water supply pipe in communication with said element, said supply pipe extending through a sidewall of said venturi-shaped conduit.
28. The integrated system of claim 23, including temperature sensing means (To) located between the downstream end of said venturi-shaped conduit and the inlet to said cloth filtration device valve means to control the rate of liquid water introduced into the gas stream in said throat portion and controller means communicating with said temperature sensing means (To) and being operative to control said valve means in response to the sensed temperature of said temperature sensing means (To).
29. The integrated system of claim 23, wherein the size and shape of said-venturi-shaped conduit is adapted to accelerate the hot, particulate-laden gas stream to a Mach number of at least about 0.4 within the throat portion thereof.
30. The integrated system of claim 23, wherein at least the downstream divergent portion of said venturi-shaped conduit is thermally insulated.
31. The integrated system of claim 24, wherein said downstream divergent portion of said venturi-shaped conduit has an included angle within the range of between about 6 and about 14°.
32. The integrated system of claim 23, 24 or 25, further comprising an indirect heat exchanger communicating with and being located upstream from said venturi-shaped conduit and a furnace carbon black reactor communicating with and being located upstream from said indirect heat exchanger.
33. The integrated system of claim 26, 27 or 28, further comprising an indirect heat exchanger communicating with and being located upstream from said venturi-shaped conduit and a furnace carbon black reactor communicating with and being located upstream from said indirect heat exchanger.
34. The integrated system of claim 29, 30 or 31, further comprising an indirect heat exchanger communicating with and being located upstream from said venturi-shaped conduit and a furnace carbon black reactor communicating with and being located upstream from said indirect heat exchanger.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US27521981A | 1981-06-19 | 1981-06-19 | |
| US275,219 | 1981-06-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1198364A true CA1198364A (en) | 1985-12-24 |
Family
ID=23051357
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000404611A Expired CA1198364A (en) | 1981-06-19 | 1982-06-07 | Method and apparatus for cooling a hot particulate- laden process stream |
Country Status (26)
| Country | Link |
|---|---|
| JP (1) | JPS5813661A (en) |
| KR (1) | KR880001994B1 (en) |
| AR (1) | AR228776A1 (en) |
| AU (1) | AU556481B2 (en) |
| BE (1) | BE893496A (en) |
| BR (1) | BR8203555A (en) |
| CA (1) | CA1198364A (en) |
| CS (1) | CS276402B6 (en) |
| DD (2) | DD239343A5 (en) |
| DE (1) | DE3221340A1 (en) |
| DK (1) | DK274382A (en) |
| ES (2) | ES513258A0 (en) |
| FR (1) | FR2508155B1 (en) |
| GB (1) | GB2100850B (en) |
| IE (1) | IE53299B1 (en) |
| IN (1) | IN157954B (en) |
| IT (1) | IT1152419B (en) |
| LU (1) | LU84208A1 (en) |
| NL (1) | NL8202333A (en) |
| NZ (1) | NZ200776A (en) |
| PH (1) | PH24916A (en) |
| PL (1) | PL236994A1 (en) |
| PT (1) | PT75012B (en) |
| SE (1) | SE457058B (en) |
| YU (1) | YU132982A (en) |
| ZA (1) | ZA823412B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ZA845571B (en) * | 1983-07-20 | 1985-03-27 | Uhde Gmbh | Process for the treatment of dust-laden waste gas |
| US4691865A (en) * | 1986-01-23 | 1987-09-08 | Interlock Corporation | Device for chilling stream of gas-suspended particles |
| FR2719499B1 (en) * | 1994-05-04 | 1996-07-26 | Tech Ind Fonderie Centre | Method and installation for treating combustion fumes. |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB717884A (en) * | 1952-07-15 | 1954-11-03 | Tor Fjalar Holmberg | An improved method of treating gases by the wet process |
| US3155325A (en) * | 1960-10-14 | 1964-11-03 | Phillips Petroleum Co | Process and apparatus for treating carbon black effluent |
| DE1421337B2 (en) * | 1962-10-26 | 1970-03-26 | Klöckner-Humboldt-Deutz AG, 5OOO Köln-Deutz | Device for humidifying hot, dusty gases, in particular exhaust gases from rotary cement kilns |
| DE1768585A1 (en) * | 1967-06-03 | 1972-03-02 | Japanese Geon Co Ltd | Process for quenching thermally cracked gas and apparatus for carrying out this process |
-
1982
- 1982-05-14 PH PH27305A patent/PH24916A/en unknown
- 1982-05-17 ZA ZA823412A patent/ZA823412B/en unknown
- 1982-05-28 NZ NZ200776A patent/NZ200776A/en unknown
- 1982-05-31 AR AR289551A patent/AR228776A1/en active
- 1982-06-04 PT PT75012A patent/PT75012B/en not_active IP Right Cessation
- 1982-06-05 DE DE19823221340 patent/DE3221340A1/en not_active Withdrawn
- 1982-06-07 CA CA000404611A patent/CA1198364A/en not_active Expired
- 1982-06-09 NL NL8202333A patent/NL8202333A/en not_active Application Discontinuation
- 1982-06-10 GB GB08216825A patent/GB2100850B/en not_active Expired
- 1982-06-11 BE BE0/208335A patent/BE893496A/en unknown
- 1982-06-14 CS CS824397A patent/CS276402B6/en unknown
- 1982-06-17 FR FR8210610A patent/FR2508155B1/en not_active Expired
- 1982-06-17 SE SE8203768A patent/SE457058B/en not_active IP Right Cessation
- 1982-06-17 LU LU84208A patent/LU84208A1/en unknown
- 1982-06-17 DD DD82264924A patent/DD239343A5/en not_active IP Right Cessation
- 1982-06-17 DD DD82240833A patent/DD212575A5/en not_active IP Right Cessation
- 1982-06-17 BR BR8203555A patent/BR8203555A/en not_active IP Right Cessation
- 1982-06-18 YU YU01329/82A patent/YU132982A/en unknown
- 1982-06-18 DK DK274382A patent/DK274382A/en not_active Application Discontinuation
- 1982-06-18 PL PL23699482A patent/PL236994A1/xx unknown
- 1982-06-18 KR KR8202734A patent/KR880001994B1/en active
- 1982-06-18 ES ES513258A patent/ES513258A0/en active Granted
- 1982-06-18 IE IE1452/82A patent/IE53299B1/en unknown
- 1982-06-18 AU AU84988/82A patent/AU556481B2/en not_active Ceased
- 1982-06-18 IT IT21932/82A patent/IT1152419B/en active
- 1982-06-18 JP JP57105250A patent/JPS5813661A/en active Granted
- 1982-06-19 IN IN714/CAL/82A patent/IN157954B/en unknown
-
1983
- 1983-07-27 ES ES524480A patent/ES8501243A1/en not_active Expired
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