Concept Commercial System

System Description

Input Processing
1. Receiving
  1. Waste Receipt
    
    Incoming wastes are received at the Scale House. The weighmaster classifies the load, begins the delivery tag, and allows the vehicle to enter the facility.
  2. Tipping
    Cleared vehicles proceed to the tipping area. At this point, loads are discharged into the respective Receiving Hopper for that load class (Food, Green, Paper, etc.). The operator checks the tipped load for contaminants and removes any which are detected before acknowledging receipt of the load. Liquid loads are discharged into the Liquid Waste Receiving Sump. A Sump Pump transfers liquid material to the Liquid Waste Storage Tank.
  3. Exiting
    Empty vehicles exit the facility via the Scale House, where the weighmaster completes the delivery tag and the transaction.
2. Processing
  1. Batching
    The operator verifies the batch parameters and initiates the batching sequence. Respective quantities of materials are transferred by the Receiving Hoppers, which also function as Waste Metering Conveyors, onto the Transfer Conveyor. The Transfer Conveyor discharges to the Input Conveyor, which deposits the material into the Hydrapulper, along with liquid delivered from the Liquid Waste Storage Tank by the Liquid Waste Transfer Pump. The sequencing of the various materials is determined during batch setup. Once complete, the batch is mixed for an additional length of time before being delivered to Bioconversion.
  2. Loading
    The finished batch is loaded into the appropriate BioConverter by the Feedstock Pump after passing through the Trash Removal Device. The "de-trasher" prevents large particles from reaching the Feedstock Pump, diverting them instead to the Trash Conveyor, where the rejects are rinsed and dewatered while being discharged to the Trash Compactor. In the Trash Compactor, rejects undergo further dewatering and are then deposited in a "roll-off" for removal from the facility.
    
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BioConversion

BioConversion of the feedstock is accomplished in an array of BioConverters. The BioConverter is the heart of the BioConversion system. It provides an environment for the cultivation of anaerobic bacteria, which biologically convert (hence the term BioConversion) the organic material added to the system into the output products of the system. A typical BioConverter is a vertical concrete Vessel, which contains a Growth Immobilization Matrix, a Heating Coil for temperature maintenance, and Sparging Tubes for mixing/gas transfer. A fiberglass Gas Holder maintains the produced BioGas at a slight positive pressure, preserving the anaerobic environment. A Differential Pressure Sensor is used to measure liquid level, and a RTD(s) measures the liquid temperature.
1. Heating
  
  Vessel temperature is maintained by heat recovered from the Generator Set(s). A Hot Water Pump circulates a heat transfer fluid through the Exhaust and Cooling Water Heat Exchanges, where it is heated. The fluid then passes through the Vessels' Heat Exchange where it's heat is transferred to the Vessel contents. The RTD(s) measures the temperature of the contents and acts upon the Heat Exchange Control Valve to maintain the temperature setpoint. A Radiator/Fan adjusts the final temperature of the fluid as it returns to the Hot Water Pump.
2. Mixing
  
  Vessel mixing is accomplished by recirculating the BioGas. The Sparging Blower provides an increase in the pressure/flow of raw BioGas to the Sparge Tubes in each Vessel. Automated Valving allows variation of "sparging" sequences to match mixing requirements.
  
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Output Processing
1. Gas
  1. Primary
    BioGas is produced by the bacteria as they convert the feedstock. Raw BioGas is passed through the Scrubber(s) by static pressure built up in the gas header. The Gas Blower boosts the pressure of the scrubbed BioGas and provides fuel flow to the Generator Set and/or Boiler.
  2. Secondary
    A portion of the scrubbed BioGas undergoes further processing in the Membrane Separation System, which separates the components of the gas into two streams. The "product" stream is pipeline-quality compressed natural gas (CNG), which is used as fuel replacement in vehicles equipped for the purpose. The "reject" stream is re-combined with scrubbed BioGas, and consumed in the Generator Set(s) and/or Boiler.
    
    "Product" BioGas is stored using one of two systems, the selection of which is dependent upon the quantity of gas to be stored. Small quantities (< 200 gge/day) are delivered directly into respective vehicles' storage cylinders with a Vehicle Refueling Appliance (VRA), a small compressor developed for the purpose (10-12 hr. fill time). Larger quantities are put into High Pressure Storage Vessels using a Gas Compressor. A Fast-fill Dispenser is then used to fill vehicles' cylinders from HP Storage in a manner similar to traditional fuelling (5-10 min. fill time).
  3. Other
    An enclosed Safety Flare is provided to burn gas which is relieved from the system. Annubars w/ DP sensors provide gas flow measurement. Temperature and Pressure are corrected for by respective Sensors. A Gas Chromatograph provides measurement of the components of any BioGas sample. This information, combined with flow data, allows the calculation of the mass of the BioGas being produced. System performance may then be determined.
    
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2. Effluent
  1. Solids Separation
    1. Primary
      Non-converted and non-convertible solids remain in the liquid after BioConversion. The Effluent Pump delivers the effluent to the Vibrating Screen, which removes this material. The portion of the effluent which is smaller than the Screen mesh size passes through the Screen and is held in the Effluent Storage Tank for further processing by the Ultrafilter. The coarse solids "shake" off of the Screen, pass through the Roller Press, and fall into the Dryer.
    2. Secondary
      Screened effluent from the Effluent Storage Tank is transferred by the Effluent Transfer Pump to the Ultrafilter Batch Tank. The Ultrafilter Pump circulates this liquid through the Ultrafilter Module, Heat Exchange, and back to the Batch Tank. The effect of pressure and flow across the Ultrafilter membranes causes the portion of the effluent which is "smaller" than the molecular weight cut-off (MWCO) of the membrane (liquid and dissolved solids) to pass through the membrane. This "filtrate" (plant tonic) drains into the Filtrate Storage Tank. What does not pass becomes gradually concentrated in the Batch Tank. This "retentate" (plant/soil activator) is periodically discharged to the Retentate Storage Tank. Filtrate and Retentate Transfer Pumps are provided to move the filtrate and/or retentate to delivery, packaging, etc.
  2. Solids Drying
    The discharge of the Roller Press is directed to the Dryer, which provides pasteurization and moisture adjustment for non-converted and non-convertible solids, which are removed from the system by the Vibrating Screen. The Dryer is an indirect-heat, contact type equipped with a Vapor Recovery System for emission control. Steam produced in a Boiler is used as the heat transfer medium. Upon completion of a drying cycle, the resulting BioSoil is removed from the Dryer by the Output Conveyor, which discharges into the Bagging System Surge Hopper.
  3. Solids Packaging
    BioSoil produced in the Dryer is discharged into the Bagging System Surge Hopper. A Bag Filler attached to this Hopper places a pre-determined quantity/weight of product into each bag, seals it, and delivers it onto the Bag Conveyor. The Bag Conveyor carries the bags to the Palletizer, where the bags are stacked on pallets. These pallets are wrapped by a Pallet Wrapper prior to being warehoused or shipped by the operator.
  4. Liquid Packaging
    Portions of the liquid products produced by the Ultrafilter are packaged. Retentate or filtrate is transferred from the respective Storage Tank to the Bottle Filler by Transfer Pump. The Bottle Unscrambler, Bottle Filler, Bottle Capper, and Bottle Labeller perform their respective functions as each bottle progresses down the line. A Filled Bottle Packager places filled bottles into boxes, which are then put on a pallet by a Palletizer. The stacked pallet is wrapped by a Pallet Wrapper prior to being warehoused or shipped by the operator.
    
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Auxiliary Systems
1. Electricity Generation
  
  BioGas produced by the system is consumed in a Generator Set(s). Heat Exchanges are installed on the Exhaust and Cooling Water to provide heat recovery. This heat is supplied to the BioConverters by the Hot Water Pump.
2. Steam Generation
  
  BioGas produced by the system is also consumed in a Boiler, which provides steam to the Dryer. It also provides steam to the CIP system. The Boiler is a pre-packaged unit with feedwater treatment and pump, condensate, and chemical systems.
3. Clean In Place
  
  A Clean In Place (CIP) System is provided to allow cleaning of concealed surfaces. Location of these surfaces is primarily confined to the Input Processing Area (enclosed conveyor belts and enclosures, etc.).
4. Wastewater
  
  Sumps/Pumps are strategically located around the facility to collect wastewater produced during processing. Sources of wastewater include water from washdown of exposed surfaces, condensed Dryer vapors, and condensate from the CIP System. All wastewater is pumped to the Liquid Waste Storage Tank for re-use in processing.
5. Control Air
  
  An Air Compressor w/Air Dryer provides dry instrument air for actuation of valves throughout the system.
  
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Conceptual System

System Description

Electricity Generation

Steam Generation

Clean In Place

Wastewater

Control Air