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Pollution Prevention Options for Chemical Manufacturers

compiled by Rick Grote, ChemAlliance Staff

Pollution Prevention Checklist for Chemical Manufacturing Facilities
Prepared by Solid & Hazardous Waste Education Center (SHWEC),
University of Wisconsin-Madison Extension Program
WASTE ORIGIN WASTE TYPE POLLUTION PREVENTION AND RECYCLING METHODS
Material Input, Storage and Handling Shelf-life Expired, Obsolete, or Contaminated Materials

Reacted, Polymerized or Off-spec Chemicals

Dust Emissions

Empty Containers

Tanker Heels

  • Test materials first to determine whether they can be used in current manufacturing processes.
  • Return obsolete materials to suppliers.
  • Segregate waste streams.
  • Store packages to protect from weather.
  • Provide secondary containment (and possibility for recovery) for hazardous materials.
  • Improve quality of feed by working with suppliers or installing purification equipment.
  • Re-examine need for each raw material (e.g., reduce or eliminate by modifying process and improving control).
  • Use off-spec material.
  • Use inhibitors to prevent unwanted side reactions or polymer formation.
  • Reformulate products from powder to pellet.
  • Reuse inert ingredients when flushing solids handling equipment.
  • Switch to reusable containers, tote-bins or bulk shipments.
  • Recover product from tank cars and tank pumps and piping systems to transfer liquids.
  • Use dry disconnects.
Reactors Off-spec Materials

By-products

  • Improve physical mixing in reactor by installing baffles, high rpm motor for agitator, different mixing blade design, multiple impellers, pump recirculation or an in-line static mixer.
  • Distribute feeds better for better yield conversion, both inlet and outlet.
  • Improve ways reactants are introduced into reactor (perfect ideal reactant concentrations before feeds enter reactor).
  • Improve catalyst and continuously upgrade.
  • Provide separate reactor for recycled streams.
  • Improve heating and cooling techniques for reactor.
  • Consider different reactor design (e.g., plug flow instead of stirred-tank back mix).
  • Improve control to maintain optimal conditions in reactor (e.g., stabilize conditions in operation frequently, use advanced computer controls).
  • Ensure that rubber gaskets are not cracked or worn.
Pumps  
  • Recover seal flushes and purchase and recycle to process where possible.
  • Turn off flush when not in use.
  • Use seal-less pumps (can-type or magnetically driven).
Heat Exchangers Off-spec Product (e.g., temperature sensitive)
  • Reduce tube-wall temperature:
  • Use lower pressure steam;
  • De-superheat steam;
  • Install thermocompressor.
  • Use staged heating (waste heat, then low pressure steam, then de-superheated high pressure steam).
  • Use on-line cleaning techniques (recirculating sponge balls and reversing brushes).
  • Use scraped-wall exchanger for viscous streams.
  • Monitor exchanger fouling.
  • Use non-corroding tube.
Distillation Column Impure Product

Polymerized Waste

Vented or Flared Products

  • Increase reflux ratio if column capacity is adequate.
  • Add section to column (e.g., with different diameter, trays, high efficiency packing).
  • Retray or repack column.
  • Change feed tray for better separation.
  • Insulate.
  • Improve feed distribution, especially for packed column.
  • Preheat column feed (e.g., by cross exchange with another stream).
  • Remove overhead products from tray near top of column.
  • Increase size of vapor line.
  • Modify reboiler design (falling film or pumped recirculation reboilers, high-flux tubes).
  • Reduce reboiler temperature (e.g., using lower pressure steam, de-superheated steam, installing thermocompressor, using intermediate transfer fluid).
  • Ensure that tubes are not blocked.
  • Lower column pressure.
  • Improve overhead condensers (retubing, condenser replacement, supplemental vent condenser addition).
  • Forward vapor overhead to next column (use partial condenser and introduce vapor stream to downstream column).
Piping Leaks and Volatile Emission

By-Products

Emissions

Degraded Product

  • Establish a leak detection and repair system for all valves, pumps and seals.
  • Monitor major vents (storage tanks, tankers) and flare system and recover vented products (install condenser or vent compressor).
  • Avoid sending hot materials to storage.
  • Change metallurgy or use lining.
  • Avoid overheated lines, vessel tracing and jacketing.
  • Eliminate "dead" zones
  • Segregate wastes and recover.
Furnaces Energy
  • Replace coil, investigate alternative designs.
  • Replace furnace with intermediate exchanger, use high temperature transfer fluid.
  • Use existing steam superheat.
Processing, etc. Off-spec Product

Contaminated Product

Spills

Dust Emissions

Evaporative Loss

Samples from Quality Control Testing

  • Produce only the amount requested or needed.
  • Substitute less toxic or non-toxic raw materials.
  • Improve on-line control (e.g., with computer control system).
  • Optimize daily operation.
  • Automate start-ups, shutdowns and product changeover.
  • Program plant to handle unexpected upsets and trips.
  • Relocate process equipment and change piping configuration to avoid contamination from other sources.
  • Find a market for waste product.
  • Install reusable insulation.
  • Redesign or modify processes and technologies to recover product and unconverted raw materials.
  • Reformulate products (e.g. prepare chemicals in pellet form instead of powder to reduce dust emissions).
  • Segregate and reuse dust emissions in the production process.
  • Shift from batch manufacturing to continuous manufacturing.
  • Regenerate catalysts.
  • Review sampling frequency and procedure to reduce number and quantity.
  • Recycle samples.
  • Consider diversion into neutralization tanks if disks rupture on the reactor.
Laboratory Wastes Sample Waste

Mercury

  • Reduce sample size.
  • Review sampling procedures.
  • Return unused sample to process (or client).
  • Perform in-line monitoring.
  • Use electronic or non-mercury thermometers.
Cooling Towers High Chemical Use

High Water Usage

  • Continuously monitor water quality and adjust chemical concentration.
  • Use less toxic biocides instead of chlorine.
  • Use blowdown water for non-critical cleaning applications or as fire pond water.
  • Use plastic lumber to replace wooden slats.
Equipment Cleaning and Changeover Waste Product

Spent Cleaners

Rinse Water

Spent Filters

  • Maximize equipment dedication.
  • Improve scheduling of production of chemicals that use the same production line.
  • Recover more product (e.g., through scraping down tanks, pigging or blowing lines).
  • Reuse inert ingredients when flushing solids handling equipment.
  • Avoid unnecessary equipment cleaning; explore feasibility of eliminating cleaning step between batches.
  • Consider in line mixers instead of bulk tanks for mixing.
  • Consider alternative cleaning methods (mechanical cleaning such as plastic media or dry ice blasting).
  • Consider less hazardous cleaners (e.g., ultrasonic cleaning with more biodegradable cleaner).
  • Standardize cleaning products used.
  • Use less cleaner (by using high pressure sprays, pressurized air, steam and heated cleaning bath, etc.)
  • Reclaim and reuse cleaner if feasible.
  • Use multiple stage rinsing.
  • Reuse rinse water.
  • Clean process equipment with process fluids if possible.
  • Use clearable reusable filter media

Sources:

• Chemical Manufacturing: Pollution Prevention Opportunities Checklist, Industrial Waste Section, County Sanitation Districts of L.A. County, Whittier, CA, 12/90.

• "Use These Ideas to Cut Wastes," Hydrocarbon Processing, Ken Nelson, Dow Chemical USA, March 1990.

• Fact Sheet: Pollution Prevention: Strategies for Chemical Production, Center for Hazardous Materials Research, Pittsburgh, PA.

• "A Pollution Prevention Guide for Small Chemical Manufacturing Operations" Delaware Department of Natural Resources and Environmental Control: http:/wwwdnrec.state.de.us/tdelchem.htm

• Connecticut Department of Environmental Protection Industry Specific Fact Sheets: Chemical Processing (6/93)

 

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