FAQ

Can I buy a BiGchar machine?

Yes, however it is important to note that profitable operation of a carbonistion system requires much more than just the core technology.

Generally the revenue streams are waste processing fees, sales of carbonised biomass and/or sale of heat.

A potential user of BiGchar CCT needs to obtain any necessary environmental and council permits for the proposed operating site.

Do BiGchar units make activated carbon?

Sometimes yes but generally no. An activation step is usually required and the feedstock needs to be suitable. Pyrocal can offer a supplementary steam activation process to produce activated carbon from suitable feedstock (such as bamboo or nut shells). Please contact us to discuss.

What are the char yields?

This is influenced by the feedstock and the operating conditions but roughly speaking is in the range of 20-30 percent of the dry weight of feed.

The key factor is productivity. The BiGchar CCTprocess will produce typically 2 to 5 times more char per unit of labour and machine cost than indirectly heated continuous retorts and as much as 10 times more than most batch retort systems. When you combine both of these considerations in a life cycle analysis, the BiGchar CCT has lower inputs per unit of charcoal activity of anything else we know.

Are the off-gases from the carbonisation process utilised?

BiGchar CCT units use some of the off-gases to run the process and the rest are burnt off cleanly to generate a clean hot flue gas. In the case of fixed site applications we recommend that the byproduct heat is used, either directly or to make electricity.

The off-gas from a BiGchar system cannot be cleaned up and used to run gas engines. Around the worlds hundreds of broken down engines lay unused as proof that pyrolysis and gasification gas is difficult to render safe for reliable operation of engines and turbines. If someone tells you they have a technology to do this please ask to see evidence of their system running a gas engine reliably for more than ten thousand hours. 

Pyrocal recommends high temperature organic rankine cycle technology as the most reliable way to convert heat energy to electricity.

Emissions?

We have confirmed through emissions testing that the native emissions from the BIGchar CCTprocess are inherently low. In most cases additional emissions controls are not required.

The regulatory requirements vary greatly by location and application, as does the emissions performance with feedstock, so the exact requirements are determined on a case by case basis.

Do you have data available for the outgoing products such as share of char, oil and gas and the compositions of the product?

The mass and energy balance is sensitive to feedstock and operating conditions however as a general rule the 100 units of feedstock becomes:

20-30% char

70 - 80% off-gas, which is immediately combusted to yield clean heat, hence our system does not make an oil product.

Similarly, for the energy balance 100 units of energy becomes:

30-40% retained as combustible matter in the char

55-67% heat energy (primarily available from the oxidiser flue at 650-900 deg C)

3 to 10% losses (eg. during char quenching and to the ambient air around the equipment). 

What is the amount time and work needed to sustain the process?

The process is continuous and generally a single operator can operate up to 3 machines. In terms of safety a second person should be always be available on the site to assist or relieve the operator for breaks. The most cost effective operation is achieved when the plant is co-located with other commerical activities so that labour and mobile plant can be shared. 

What kind of restrictions do you have in regard to feed type such as water content and impurities also how is the flexibility regarding the fuel?

BiGchar systems have maximum throughput at around 10% moisture in the feed, however they may operate a moisture contents up to 35% on a wet mass basis. We design installations to operate with feedstock in the range of 15-20% moisture.

The other dilutant is ash (inorganics). The upper limit is approximately 50% as fed to the machine, however ash must be considered in combination with moisture. We do this by specifiying a minimum lower heating value (LHV) or net calorific value (NCV) of 13 MJ/kg (5600 Btu/lb) for feed to the hearth. This provides the hearth and thermal oxidiser with enough energy to do their job. Lower heating value materials can be processed, however these require either pre-drying or pre-heating of the air supply to the oxidiser and/or hearth.

Contaminants such as CCA (copper chrome arsenic) treated timber, PCBs, Dioxins and high levels of heavy metals must be avoided unless the system is specifically customised to handle these. Most simple organic chemicals (eg. hydrocarbons and most plastics) will be destroyed in the thermal oxidation stage.

Halogens (eg. chlorine, bromine) in the feedstock can be handled with appropriate operating procedures, depending on their concentration and source.

Our rotary hearth is much more tolerant of stones, rocks and metal contamination than auger or screw type processes. However prevention is better than cure when it comes to rocks and metal !

How the levels of toxins and heavy metals in the char are, is the biochar ready to use for example soil improvement or is further processing needed?

Organic toxins are generally removed from the char into the off-gas where they are typically destroyed. Most heavy metals are retained and therfore concentrated in the char. The exceptions are volatile heavy metals like mercury and arsenic, which head to the off-gas.

If the quantity of any heavy metal in the feed is sufficient that the resulting concentration in the char or off-gas exceeds regulatory limits then measures must be taken to address this. Prevention is always better than cure, so it is better to avoid feedstocks containing excess levels of heavy metals. Otherwise expensive adsorption/absorption processes may be required to address the issue.

 

 

 

 

 

 

 

Is BIG CHAR for me? Image

Is BIG CHAR for me?

CCT Technology lands
in Vietnam

In November 2014, one of our Big Char 2200 models was installed at a new EcoFarm corn and rice processing facility near Ho Chi Min City, Vietnam. Josiah Hunt, technical
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