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Voc recovery units

MODERN SOLUTIONS: CRYOGENICS

Low temperature and cryogenic condensation is a process that can be used as an effective means for VOC emissions control.

Cryogenic condensation technology is based on lowering the vapor pressure of a component by reducing the temperature of the process stream thus increasing the recovery of the components in the liquid or solid phase.

Nitrogen gas is widely used in the  process industry. It is inert and  typically transported and stored in its liquid state at low temperature and high pressure.
It is a convenient media to use.  The low temperature cooling capability of liquid nitrogen allows for the design of highly efficient condensation systems. 
Why wasting “ cold energy “ to the environment to vaporize liquid nitrogen and not use it profitably?

  • Cryogenic condensation is well suited for VOC emission control because of its ability to respond instantly to changes in VOC flow rate and solvent loading.
  • It can recover virtually any VOC species even under varying conditions.
  • Cryogenic condensation can deal with all organics (even in the presence of water) and can function when the concentration and composition are changing over time. 
  • This flexibility makes it particularly suitable for VOC control in multi-product, multi-purpose plants where batch or continuous processes are employed.

PraxEidos has been developing and manufactures high quality - high performance heat exchangers for direct expansion of liquid nitrogen and new generation Refrigerants.

THE TECHNOLOGY PROVIDED

A responsible approach towards protecting the environment means limiting the emissions of volatile components. One method is the condensation of these components by cooling the exhaust stream with liquid nitrogen. As the vapours are cooled, the volatile components condense and then freeze. These solid particles can be trapped leaving a clean stream of gas to vent to the atmosphere. The understanding of the heat transfer mechanisms has promoted special heat exchanger geometries which are best suited to the properties of boiling nitrogen and condensation of gases within incondensable vapours. The temperatures required to meet acceptable emission standards of the order of tens parts per million (ppm) are typically -100°C and lower. The obvious choice of a cooling medium is liquid mitrogen which can provide cooling down to 180°C. The design of the heat exchangers poses a special challenge which is beyond the remit of typical heat exchanger design packages. Not only are the temperatures outside the normal parameters but the heat transfer relationships have to consider the boiling and gas heating of the nitrogen, and the condensation and freezing of multiple volatile components in an incondensable stream. PRAXEIDOS has developed computer design tools to model these heat transfer mechanisms and generate valid heat exchanger designs. The vertical heat exchanger mounted above the 1500 liters vinyl chloride tank.

THE NEED

PraxEidos has developed the technology to reduce pollution from a number of industrial activities using cryogenic condensation. New laws and new attitudes to environmental protection are driving down the permissible level of emissions of volatile organic compounds (VOC's). The aim is to reduce the damage that VOC's cause to human health and the environment. Many of these substances are carcinogenic and a key cause of photochemical smog. The neatest and cleanest way to remove VOC's from exhaust gas stream is condensation with liquid nitrogen. The technology from PRAXEIDOS removes VOC's to meet emission level lower than 20 mg/Nmc as well as overcoming the limitations of traditional emission-control methods.

THE BENEFIT

The cryogenic recovery system, designed and supplied by PRAXEIDOS, combines the refrigeration power of liquid nitrogen with the inerting properties of gas nitrogen resulting in a skid mounted VOC control system that is simple to install, economical and effective. Running costs are reduced to a minimun by the ability to re-use the nitrogen to purge and and blanket pipe work and tanks. Recovered VOC’s can often be re-used directly – something that is more difficult with carbon bed technology and impossible with incerators and catalytic axidisers.

   MARKET

      INDUSTRIAL APPLICATION

  • Fine Chemicals Industry
  • Chemical Industry
  • Pharmaceutical Industry
  • Oil and Gas Industry
  • Spent Solvent Recovery Industry
  • Gasoline road, ship and rail
  • Filling tankers
  • Coating and Drying Industry

 

 

POLLUTANTS

  • Petrol
  • Diesel Industry
  • Benzene
  • Toluene
  • Phenols
  • Alcohols
  • Ketones, Acetone
  • Hydrocarbons
  • Acrylonitrile
  • Esters
  • Ethyl  acetate

 

 

 

  • Fine Chemicals Industry
  • Chemical Industry
  • Pharmaceutical Industry
  • Oil and Gas Industry
  • Spent Solvent Recovery Industry
  • Gasoline road, ship and rail
  • Filling tankers
  • Coating and Drying Industry