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Continuous Pyrolyser

Designed by Australian & Chinese experts and manufactured in China, this is a continuous device that heats biomass in the absence of oxygen to reduce it to charcoal and gases. It operates at temperatures from 300 to 900 degrees Celsius. It is designed to be used in the field and can be mounted on a trailer or can be placed in an open sided shed. It has one motor to drive the screw and one fan and a diesel generator set to provide electricity when grid power is not available. Biochar can be continually feed out through a screw or can be stored in a bin. Pyrolysis of biomass to biochar has great potential to both ameliorate the effects of climate change and improve farming efficiency. It does this by converting biomass carbon to black carbon and sequestering it in soil where it has been shown in certain cases to improve crop yield and resilience. Meanwhile, as burning of wheat straw and rice husks in the crop field has been causing more and more air pollution problem, more regulations will be implemented in the near future to restrict the emission. The continuous pyrolyser will be a perfect solution to such problem.

  Operational principle
LPG burner is used to preheat the chamber. Fuel comes in from an external hopper. Primary air comes through holes in flat steel sheets beside the troughs and through 2 jets on the end wall . Damper is closed at the start to minimise the heat loss.
The syngas from pyrolysing biomass in the trough and primary air mix and partially combust above the bed. Radiant flux above the bed causes biomass to dry/torrefy and pyrolyse as the material moves along the trough. The secondary air then enters the reactor at the outlet and mixes with the remaining unburnt syngas.
The paddles stir the charring biomass and sweep it to the bottom of the trough mixing with the drying biomass. The biochar drops over a weir at the end of the trough. The temperature of the burning gas is maintained above 700C to ensure complete combustion.

  Control strategy
There are 2 options for controlling the unit. The first relies on the skill of an operator to ensure that process conditions are maintained (biomass feed rate in, reactor temperature, biochar temperature and biochar feed rate) through adjusting air flow rate and auger speeds. The operator also activates any shut down procedures if required e.g. stopping screw and fan or quenching the reactor or feed bin with water. The unit can have different levels of control that allows the auger rate and the air rate to be adjusted around temperature set points using variable frequency drives.

The continuous pyrolyser has already been used by a number of farming corporations in Australia, and was well received in the market. The business opportunities are blooming.