Uses of Hot Gas Filtration

Why Filter Gases at High Temperature ?

There are a number of reasons why it may be desirable to remove solids from a process gas at an elevated temperature:

• the gas is already hot and subsequent process(es) also require it to be hot, but clean
• the hot gas contains condensable liquids or solids that are required to remain in the vapour phase i.e.
  • product liquids, such as oil from pyrolysis processes, that will be subsequently condensed and captured
  • acid gases, that would condense and corrode the process vessels
  • sticky liquids that would blind the filter medium
• the solids would compromise downstream processes e.g. by fouling a heat exchanger
• the gas will be recycled and solids are unacceptable
• the solids to be collected will change their properties if cooled down
• occasional loss of control, or sparks, require high temperature resistance
• a dry scrubbing sorbent in the gas stream reacts only at high temperature

Applications

Caldo has installed ceramic filters on processes including (links are to other pages on www.caldo.com):

• incineration of various materials
• burnout furnaces in lost wax foundries
• plasma melting of catalyst for precious metal recovery
• demilitarisation of munitions and chemical weapons
• production of nano materials
• gasification of waste wood and other materials
• pyrolysis of waste plastics and other materials
• manufacture of high performance ceramic fibres
• sulphuric acid recovery

Dry Scrubbing

Acid gases are a common gas phase pollutant and these can be very effectively removed by the addition of lime or sodium bicarbonate to the gas upstream of the ceramic filter.