US3591928A - Continuous fluidization-type powder drying plant and method of use - Google Patents

Continuous fluidization-type powder drying plant and method of use Download PDF

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Publication number
US3591928A
US3591928A US834325A US3591928DA US3591928A US 3591928 A US3591928 A US 3591928A US 834325 A US834325 A US 834325A US 3591928D A US3591928D A US 3591928DA US 3591928 A US3591928 A US 3591928A
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drying
gas
column
columns
dehumidifying
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US834325A
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English (en)
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Jiyuichi Nara
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
    • B01J8/24—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique
    • B01J8/36—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique with fluidised bed through which there is an essentially horizontal flow of particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B13/00—Conditioning or physical treatment of the material to be shaped
    • B29B13/06—Conditioning or physical treatment of the material to be shaped by drying
    • B29B13/065—Conditioning or physical treatment of the material to be shaped by drying of powder or pellets
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B3/00—Drying solid materials or objects by processes involving the application of heat
    • F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air
    • F26B3/06—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried
    • F26B3/08—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried so as to loosen them, e.g. to form a fluidised bed

Definitions

  • the heat-treating chamber comprising a first section 45 in which a heated air medium is directed at high velocity against the surfaces of the veneer material to evaporate moisture therefrom, and a second section 55 in which ambient air is circulated to cool the veneer and also carry away remaining moisture.
  • a pair of centrifugal fans 46 in the heating section 45 pressurizes air which is also heated to high temperature (typically, above 350 F.) by a gas burner (not shown).
  • the pressurized heated air is then forced into a respective first plenum chamber 47 and thence into an associated hollow air box 48 disposed laterally on either side of the veneer material which is transported through the central core area.
  • the veneer 18 is carried through the center of the chamber by means of a sandwiching conveyor web 35a and 35b supported and driven by a roller mechanism 49.
  • the heated air emerges from the respective air boxes 48 at high velocity, typically 2,500 l0,000 linear feet per minute, through a plurality of jet nozzles 52 spaced in a staggered arrangement to direct the heated air medium perpendicularly to the horizontal surfaces of the moving veneer material 18.
  • the high-velocity, high-temperature jet action produces an efficient and rapid drying of the partially dried veneer material and, because of the disruption of the interface boundary layer which occurs due to the sharp right-angle impingement of the jet streams on the flat surface of the sheet material, the drying action is extremely thorough.
  • the air flow is swept laterally across the surface thereof and exhausted from the central core area and into the respective second plenum passages 51, and thereafter drawn toward the inlet side of the opposing centrifugal fan 46 to complete the circulation path.
  • the moisture carried away from the veneer material in the drying process and collected in the gaseous medium is then exhausted to the atmosphere through the vent stack 53.
  • the veneer material After passage through the heating section 45, the veneer material then passes into the adjacent cooling section 55 of similar design in which unheated ambient air is directed in high velocity jet streams perpendicularly against the respective faces of the veneer sheet so as to draw off remaining moisture.
  • the air is circulated in a fashion similar to that in the heating section by means of a single centrifugal fan 56, and the moisture-laden air is exhausted to the atmosphere by a separate stack 58 provided in the cooling section.
  • the conveyor mechanism 35 which transports the veneer material 18 in a closed loop configuration through the secondary dryer 30 is of generally conventional design utilizing powered and idler rollers driven by suitable mechanisms known to the art.
  • the veneer is preferably constrained in sandwichlike fashion by the conveyor web 35 which, as shown in H0. 4A, overlies the top and bottom of the material during this portion of its travel. ln its arcuate vertical passage from the overhead-mounted drying chamber to the ground level moisture detection and grading stations, and then back again, the veneer material is supported, as shown in FIG.
  • samples of intermixed sapwood and heartwood green veneer having a range of initial moisture content varying from 35 percent to 158 percent (based, as is the conventional industry practice, on the bone dry weight of the veneer) were entered into the infeed of the primary dryer unit.
  • the operating parameters of the primary dryer were set so that only the material having the lowest initial moisture content was fully dried in this unit; thus, the material of originally 35 percent moisture level was reduced to a satisfactory moisture level of 4 percent in its passage through the primary unit, and this material was then removed from the system.
  • the veneer material of initially 158 percent moisture content was reduced to only a partially dry 22 percent moisture level after passage through the primary dryer, and this wet material was thereafter continued on to the secondary dryer where it was finally reduced to a satisfactory 3% percent moisture level in two passes through the secondary dryer unit.
  • Material of moisture content intermediate these two extremes required but a single pass through the secondary dryer to reach the desired moisture level. In this manner all of the material was dried to a satisfactory moisture level within a narrow range centering around 2 4 percent moisture content, with none of the material being underdried and none of it requiring further handling or reprocessing as redry material.
  • Apparatus for continuous heat treating of planar material, of the type comprising a drying chamber having a horizontal core opening extending longitudinally through the center thereof, a conveyor for carrying said material through said chamber core, and a plurality of nozzles arranged in a spaced array throughout said chamber and coupled to a source of pressurized heated air for directing jets of high temperature air at high velocity and substantially perpendicularly to the major surfaces of said material advancing through said chamber core, characterized in that said chamber is supported overhead and above ground level by a skeletal framework so as to form an exposed open area underneath said chamber and that said conveyor is arranged in a vertically disposed closed loop so that said material, after passage through said chamber core, is transported downward, then through said open area directly underneath said chamber, and finally upward to return to the input of said chamber, whereby material will be repetitively cycled through said drying chamber until removed from said conveyor.
  • a moisture detector means for discriminating fully dried from partially dried material is positioned to examine material on said conveyor after its passage through said chamber core, and a grading station is provided underneath said chamber in said open area at which personnel may remove fully dried material from said conveyor as marked by said moisture detector.
  • This invention relates to a continuous fluidization-type powder drying plant having a plurality of drying chambers transversely parallelly connected thereto.
  • This invention has for its object the provision of a plant for drying powder, said plant being of the structure in which, in a plant used for drying polyethylene of high density, polypropylene and other synthetic resins or organic and inorganic chemicals containing singly or in conjugate state hydrocarbon-based, alcohol-based, water and other solvents by a continuous fluidization system in a gas which is in a single or azeotropic state of said organic solvents and in a nitrogen carrier gas, an object of drying is attained by separating heated drying gas into a gas of high humidity and a gas of low humidity and treating the gases through individual circuits and circulating a greater part of said heated gas in the form of the gas treated at relatively high temperatures and which needs no special cooling, and an object of efficient finished drying is attained by cooling and drying a small quantity of circulating gas alone to low temperatures.
  • a cleansing column for finished drying for use in the whole quantity of heated drying gas can be dispensed with, a refrigeration load can be decreased to a very small degree, and a desired quantity of steam is not only decreased but there is little or no need of nitrogen spent, with the result that cost of operation can be reduced
  • Another object of this invention is to provide a continuous fluidization-type powder drying plant having a plurality of drying columns transversely parallelly connected thereto, said plant being of the structure in which a plurality of fluidizationtype powder drying columns are connected and disposed parallelly at the same height, said columns have porous plates respectively on the same horizontal level, the neighboring columns of said columns communicate with each other only through the gaps between the upper sides of said porous plates and the lower ends of the sidewalls partitioning two drying columns, a first drying column is provided on one side of the upper portion thereof with a moist powder feeder, a last drying column is provided on dried powder outlets any of said drying columns is selectively provided therein with heat exchangers, fine powder mixed gas outlet pipes are respectively connected to
  • the drawing is a diagrammatic view showing by way of example a continuous fiuidization-type powder drying plant hav ing a plurality of drying chambers transversely parallelly connected thereto.
  • continuous fluidization powder drying columns I, II, III are disposed and connected in series at the same height, and provided with porous plates 1, I and 1" each placed on the same horizontal level, neighboring columns I, II and II, III communicate with each other only through the gaps between the upper side of the porous plates 1', l" 1" and the lower ends of the sidewalls partitioning both columns,
  • a first continuous fluidization drying column I is provided on one side of the upper portion thereof with a moist powder feeder 2
  • a last fluidization powder-drying column III is provided on the side thereof with a fence 3, said fence 3 being provided on the upper and lower edges with dried powder outlets 4 and 4', respectively.
  • any of the fiuidization powder-drying columns I, II, III are selectively provided therein with heat exchange devices 6, 6" and the columns are respectively provided on the undersides thereof with heated drying gas communication chamber 5, 5", 5"
  • the drying columns are respectively provided on the upper portions with fine powder mixed gas outlet pipes 7', 7", 7" which are connected and led in one pipe to a cyclone collector 8 and the gas discharged from the cyclone 8 is fed to a cleansing and dehumidifying column 9.
  • the discharged gas from the dehumidifying column is separately fed to a plurality of pipes and the heated gas communication chamber 5' of said first drying column I is supplied under pres sure by pump 13, with a gas of relatively high humidity which has been heated by a steam heater 1-0 and the heated gas com munication chamber 5' of the other drying columns II and III are provided with a means for selectively supplying under pressure a gas of low humidity Le. a gas of high degree ol'drying through a gas cooler II and a gas heater [2.
  • the apparatus of the invention comprises a plurality of the drying columns connected and disposed transversely parallelly to each other in the manner described above.
  • the cleansing and dehumidifying column 9 is designed to collect heptane from the spent liquid discharged from the column 9 and to feed the heptane at about 30 C. back thereto through a heptane cooler 9 by mean of the pump 15.
  • the numeral 16 in the drawing designates a dehumidifier.
  • Polyethylene granules to be dried are fed in a hexane con tent of 25 percent WB to a continuous fluidization powderdrying column 1 through a humidifier l6, and are dried on a porous plate 1 in a circulating nitrogen gas containing hexane C H of high humidity (45 C. dew point) to the first order balance moisture content of 1.5 to 20 percent WB in the presence of a heat exchange device 6'.
  • the granules are moved to a porous plate I" on the same horizontal level with the plate 1' and to a fluidization powder-drying column II, into which a nitrogen gas containing hexane C H of low humidity (a dew point of-IO" to 20 C.) is fed under pressure through a heated gas feed passageway different from that through which the heated gas was fed to said drying column I, the granules are dried to a higher degree of drying.
  • the granules thus dried to a higher degree in the drying column II are then moved to the succeeding drying columns llland dried to higher and higher degrees until finally they are dried to a degree of less than 0.1 percent moisture content in the final drying column III in the ease of the plant shown.
  • Drying in the drying column II is reduced to be shortest necessary period of time and the quantity of gas also is smallest in view of a separator being disposed.
  • the drying column I" depends upon its object as a purger and upon the property of material to be dried for its dimensions, a period of staying time allowed to the materials and the quantity of gas used.
  • the heated gas discharged from each partitioned drying columns is fed through each regulating valve or orifices to a cyclone collector 8 for purging and collecting powder, and the gas is introduced into a cleansing and dehumidifying column 9.
  • a colling hexane liquid from the top of the inside of the column are effected purge of dust and dehumidifying to bring about saturation at about 40 C., and a greater part of gas is increased in pressure and elevated by a steam heater to a temperature of 105 C. and circulated to the drying column I.
  • Part of the gas discharged from the cleansing and dehumidifying column 9, after the increase in pressure flows to a circuit different from said gas circulation passageway and is circulated to the drying column II by mean of the pump 14.
  • This circulating gas is dehumidifled by a gas cooler 11 (indirect heat exchange by the medium of brine from refrigerator) to a dew point of -l C into a gas of low humidity and elevated by a steam heater 112 to a temperature of 105 C and circulated to the drying columns ll or lll.
  • the plant of the invention which is constructed as described above is free from such a disadvantage and func tions in the manner described, and therefore makes it easy to dry a material to a final desired moisture content by use of a small quantity of circulating nitrogen gas during a relatively short period of gas staying. That is to say, as a greater part of the circulating gas is circulated as a high dew point, there is no necessity of effecting particular drying.
  • a greater part of the gas can be collected by cooling by use of general inexpensive industrial water, and a small quantity of circulating gas alone needs being cooled to low temperatures, but as percentage of the quantity of such a gas to the whole quantity of gas is very small, both the quantity of steam for heating and the quantity of nitrogen Spent are very small.
  • a continuous fluidization-type powder drying plant for drying high density chemical powders comprising in combination:
  • first and second adjacent vertical drying columns (I, ll) disposed in series at substantially the same height and the same horizontal level separated by a common wall, porous plates (1, ll) towards the bottom of said columns with gaps above said plates providing communication between said columns, the first drying column being substantially larger than the second drying column;
  • first and second branch lines from said outlet line, said first branch line going to said first drying column communication chamber (5), said second branch line going to said second drying column communication chamber (5"), a first pump 14), a gas cooler (11) and heater (H2) in said first branch line, a second pump (13) and steam heater (10) in said second branch line, whereby said first drying column is supplied under pressure with a gas of relatively high humidity and said second drying column with a gas of relatively low humidity.
  • a plant as claimed in claim ll including at least a third drying column after said second drying column, said third drying column including an outlet pipe (7"') with a throttle valve therein.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Combustion & Propulsion (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Microbiology (AREA)
  • General Engineering & Computer Science (AREA)
  • Drying Of Solid Materials (AREA)
US834325A 1968-06-27 1969-06-18 Continuous fluidization-type powder drying plant and method of use Expired - Lifetime US3591928A (en)

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JP43044759A JPS506058B1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1968-06-27 1968-06-27

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US (1) US3591928A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
JP (1) JPS506058B1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
BE (1) BE735324A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4300291A (en) * 1979-03-13 1981-11-17 Salem Corporation Methods and apparatus for heating particulate material
GB2205154A (en) * 1987-05-21 1988-11-30 Tioxide Group Plc Drying polymer particles
WO1994028993A1 (de) * 1993-06-16 1994-12-22 Henkel Komanditgesellschaft Auf Aktien Modifiziertes trocknungsverfahren unter mitverwendung von heissdampf im trocknungsmedium und seine anwendung
WO2010138257A1 (en) * 2009-05-29 2010-12-02 Exxonmobil Chemical Patents Inc. Method and apparatus for elastomer finishing
CN112856933A (zh) * 2019-11-28 2021-05-28 天华化工机械及自动化研究设计院有限公司 一种卧式多室流化床、高密度聚乙烯的干燥系统和方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT514275B1 (de) * 2013-05-07 2015-05-15 Andritz Tech & Asset Man Gmbh Verfahren zur Erzeugung von Salzen mit reduziertem Kristallwassergehalt

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2529366A (en) * 1945-03-02 1950-11-07 Wolf G Bauer Fluidizing process and mechanism
US3236607A (en) * 1963-06-11 1966-02-22 Exxon Research Engineering Co Apparatus for iron ore reduction

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2529366A (en) * 1945-03-02 1950-11-07 Wolf G Bauer Fluidizing process and mechanism
US3236607A (en) * 1963-06-11 1966-02-22 Exxon Research Engineering Co Apparatus for iron ore reduction

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4300291A (en) * 1979-03-13 1981-11-17 Salem Corporation Methods and apparatus for heating particulate material
GB2205154A (en) * 1987-05-21 1988-11-30 Tioxide Group Plc Drying polymer particles
AU602762B2 (en) * 1987-05-21 1990-10-25 Tioxide Group Plc Drying process
US4974338A (en) * 1987-05-21 1990-12-04 Tioxide Group, Plc Drying process
GB2205154B (en) * 1987-05-21 1991-03-13 Tioxide Group Plc Drying process
WO1994028993A1 (de) * 1993-06-16 1994-12-22 Henkel Komanditgesellschaft Auf Aktien Modifiziertes trocknungsverfahren unter mitverwendung von heissdampf im trocknungsmedium und seine anwendung
WO2010138257A1 (en) * 2009-05-29 2010-12-02 Exxonmobil Chemical Patents Inc. Method and apparatus for elastomer finishing
US20100305301A1 (en) * 2009-05-29 2010-12-02 Yeh Richard C Method And Apparatus For Elastomer Finishing
US7858735B2 (en) 2009-05-29 2010-12-28 Exxonmobil Chemical Patents Inc. Method and apparatus for elastomer finishing
CN112856933A (zh) * 2019-11-28 2021-05-28 天华化工机械及自动化研究设计院有限公司 一种卧式多室流化床、高密度聚乙烯的干燥系统和方法

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JPS506058B1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1975-03-10
BE735324A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1969-12-01

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