Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B5/00—Drying solid materials or objects by processes not involving the application of heat
  • F26B5/04—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum
  • F26B5/041—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum for drying flowable materials, e.g. suspensions, bulk goods, in a continuous operation, e.g. with locks or other air tight arrangements for charging/discharging
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B17/00—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
  • F26B17/18—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by rotating helical blades or other rotary conveyors which may be heated moving materials in stationary chambers, e.g. troughs
  • F26B17/20—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by rotating helical blades or other rotary conveyors which may be heated moving materials in stationary chambers, e.g. troughs the axis of rotation being horizontal or slightly inclined
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B25/00—Details of general application not covered by group F26B21/00 or F26B23/00
  • F26B25/005—Treatment of dryer exhaust gases
  • F26B25/006—Separating volatiles, e.g. recovering solvents from dryer exhaust gases
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B2200/00—Drying processes and machines for solid materials characterised by the specific requirements of the drying good
  • F26B2200/18—Sludges, e.g. sewage, waste, industrial processes, cooling towers

Definitions

• This invention relates to a method of producing a soil enrichment product from dewatered sludge utilizing a vacuum-auger dryer.
• U.S. Patent No. 5,570,516 shows a condensation process and apparatus for water vapor that is under vacuum. As explained in the specification, this device appears to have been created for an industrial process such as drying plastic granules as explained in column 3 ? lines 40-42.
• U.S. Patent No. 5,570,516 also appears to be directed to a drying system for an industrial process since the dryer is coupled to an industrial mixer as is shown illustrated in Figure 2 and as described in the abstract,
• the water may be removed from both primary and secondary sludges and this by-product is known as dewatered sludge.
• this unpasteurized dewatered sludge is hauled to landfills where it takes up space. This costs municipalities a relatively large amount in transportation costs. Furthermore, it fills in a landfill which could be utilized for other waste products.
• An object of the present invention is to convert unpasteurized dewatexed sludge into a useful and possibly marketable soil enrichment product at lower temperatures than typical sludge dryers.
• Another object of the invention is to reduce the need to ship dewatered sludge to landfills.
• a method of pasteurizing dewatered sludge into valuable soil conditioners is provided, Unpasteurized dewatered sludge is introduced into a first end of an auger/dryer which is maintained under vacuum pressure.
• the vacuum is provided by a manifold connected to a knock-out tank.
• a condenser applies a negative pressure to the knock-out tank.
• Hotter fluid is passed through an a duct and then through a cooling tower where it is then pumped back in the condenser to provide a temperature gradient in the condenser. Condensate from the knock-out tank is pumped with the condensate pump out of the knock-out tank.
• a boiler is utilized to provide pressurized hot water to the auger/dryer to maintain the desired temperature level such as at least a 160 degrees for 20 minutes to provide the necessary time and temperature for pasteurizing the dewatered sludge to ensure that any harmful pathogens are sufficiently reduced as the auger transfers the sludge from one end of the dryer to the other.
• the dryer portion of the process ensures that the drying portion reduces the shipping weight and volume of the dewatered sludge which is believed to be important for disposal purposes. Not only do drier sludges have reduced transportation and disposal costs, the dryer treated sludges can be directly applied by spreading on top of land with topsoil spreaders and other such equipment or incorporated into agricultural soil with minimum documentation and site restrictions.
• Figure 1 is a schematic view of the components utilized to treat dewatered sludge in occurrence with the embodiment of the present invention
• Figure 2 is a side plan view with internal portions shown in phantom of a preferred embodiment the auger/dryer shown in Figure 1 ;
• Figure 3 is a cross-sectional view of the auger ⁇ iryer shown in Figure 2;
• Figure 4 is a detailed, cut-away plan view of the inlet end of the auger/dryer of Figure 2;
• FIG. 5 is a detailed plan view of the outlet end of the auger/dryer of Figure 2. Detailed Description of the Drawings
• Class A biosolid wastewater must first be pasteurized by heating to an elevated temperature, i.e., 160 degrees Fahrenheit and maintained at that temperature for a particular time (i.e., 20 minutes), Class A sludges are considered to be environmentally safe and can be disposed of with minimal documentation and site restrictions. In many instances pasteurized sludge can be a valuable soil conditioner. It is important to remember that pasteurization is not the same as high temperature drying, which can involve burning or oxidizing into ash.
• dewatered sludge 10 is introduced through inlet airlock 12 into a dryer 14.
• the dryer 14 is equipped with an auger 16, illustrated in phantom.
• Detailed views of the dryer 14 are better seen in Figures 2-5 which show details of how heat is applied from a boiler 18 as well as how a vacuum is maintained by a vacuum manifold 20.
• the auger 16 is used to move product from a firsi end 22 to a second end 24 of the dryer 14 so that the dewatered sludge 10 in the dryer 14 is heated and then maintained at a desired temperature for a predetermined time.
• the time the sludge 10 is in the dryer may be dependent at least partially on the feed rate of the auger 16 through the dryer 14, At the second end of the dryer 14, dried sludge 26 is transported out of the outlet airlock 28 as shown.
• Temperature gauges 3032 are useful in verifying the heat transfer within the dryer 14.
• a boiler 18 is particularly useful, As pressurized hot water passes through the dryer 14, heat is transferred to the sludge 10 maintaining pasteurization temperatures and evaporating moisture from the sludge 10. The pressurized hot water is then pumped by hot water pump 34 into the boiler 18 where it is reheated and sent back into the dryer 14. Pressure and flow meters 36,38 are useful to monitor the parameters. Additionally, an expansion tank 40 is useful in maintaining desired amount of water to the boiler 18, [Q0021]
• the vacuum manifold 20 is preferably equipped with a pressure meter 42 to measure the vacuum as well as the vacuum release valve 44 which can prevent pressure within the dryer 14 to fall below the pasteurization temperature vaporization pressure.
• a condenser 48 may utilize an eductor 50 to draw a vacuum in the knockout tank 46, A vacuum pump may be used in lieu of the eductor to provide the required operating vacuum.
• Clean water is pumped to the condenser 48 with a cooling water pump 52 so that vapor in the knockout tank 46 is condensed.
• the water is then pumped on through the eductor 50 which draws a vacuum through the condenser 48.
• Water is then sent on to the cooling tower 54 where it is cooled so that it can be pumped witih the cooling water pump 52 back into the condenser 48.
• a pressure regulator 56 is useful in maintaining the desired level of vacuum in the knockout tank 46. Liquid accumulates in the knockout tank 46 and high and low levels 58,60 are useful to activate condensate pump 62 to remove condensate from the knockout tank 46. A check valve 64 is also useful to ensure that no backflow occurs into the knockout tank 46. Temperature flow and pressure gauges 66,68,70,72,74 in the vacuum drawing portion of the system are useful to maintain a desired level of vacuum in the vacuum manifold 20 so that the proper level of vacuum is drawn to remove moisture from the dewatered sludge 10 as it passes through the outer dryer 14.
• Figures 2-5 show details of the auger dryer 14, Figure 2 shows the auger 16 with a plurality of pipes 100 which connect to the manifold 20 shown in Figure 1 , Details of individual pipes 100 are shown best in Figure 3 which pass through an outer shell 102 and into an inner shell 104 at thiead-o-let 103 having helix 106 or auger 16 disposed therein which is driven by the driver 108 shown in Figure 2.
• An outer pipe 101 receives the pipe 100 from the manifold therein.
• An oversized flange attached to pipe 100 is connected to a flange on pipe 101 thereby sealing the heating water gap 114 between the inner shell 104 and the outer shell 116, [00025]
• the pipes 100 communicate the vacuum from the manifold 20 into the inner shell 104 to draw out moisture from the inner shell 104 which has sludge 10 therein during the drying process.
• Pressurized hot water is provided into inlet 110 shown in Figures 2 and 5 and spent pressurized hot water is removed from outlet 112 shown in Figure 2, Pressurized hot water enters the gap 114 intermediate the inner shell 104 and the wall of the outer tube 102.
• the outer tube 102 has a layer of insulation 118 covered by an outer shell 102.
• the insulation 118 assists in reducing the heat load to perform pasteurization and the drying functions.
• a helix structure 115 is located in a gap 114 which is believed to assist heat transfer from the pressurized hot water to the dewatered sludge in (he inner shell 104,
• the driver 108 shown in Figure 4 preferably consists of a gezi-motor assembly 120 coupled to a driver shaft 122 which drives a shafttess screw conveyer 106 shown in Figure 3 which is a helix driver or auger connected to the flange 126. Accordingly, the dewatered sludge is driven by the conveyer 106 or auger about its circumference while the interior 128 of the inner shell remains unobscured so that dewatered sludge 10 may pass from the top to the bottom while being rotated about the energy by the driver 108,
• the shaftless nature of the auger is believed to differ from prior art structure.
• Figure 4 also shows a mounting flange 140 for use in connecting the outer shell 102 to the inner shell 104.
• the drive shaft 122 is shown proceeding through a cap plate 144 having a seal retainer 146 which maintains a seal 148.
• Seal adjustment 150 is also provided, Opposite the cap plate 144 from The seal retainer 146 is a flange bearing 160.
• a body flange 152 is shown illustrated connected to the cap plate 144.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Molecular Biology (AREA)
• Treatment Of Sludge (AREA)
• Drying Of Solid Materials (AREA)

Applications Claiming Priority (2)

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• 2005
  • 2005-08-11 EP EP05813277.0A patent/EP1776554A4/de not_active Withdrawn
  • 2005-08-11 WO PCT/US2005/028266 patent/WO2006033718A1/en not_active Ceased

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