Combustion installations for biofuels; gas scrubbers being parts of gas installations; cooling and drying installations for gases; gas cleaners and purifiers, namely, gas scrubbers and gas purification machines; gas collection installations, namely, gas separators, gas filtration units, and gas purification installations; gas drying devices, namely, biogas dehumidification units, gas dehydration apparatus, and heat exchangers not being parts of machines; apparatus for purification of combusti...