Charcoal Production for Activated Carbon Raw Material

Charcoal characteristics are influenced by the raw materials used and the conditions of the production process. The use of charcoal for certain applications or industries also requires certain specifications or characteristics. For example, charcoal used for fuel can have different specification requirements from charcoal specifications for agriculture (biochar), or charcoal used as raw material for activated carbon. A number of parameters that are acceptable in certain applications may not be acceptable in other applications.

Charcoal products used as raw materials for activated carbon production are also the same. Parameters in the form of high fixed carbon (~80%), high hardness, low ash content (~3%) and low volatile matter (<10%) are prerequisites for the specifications or quality of charcoal as a raw material for activated carbon. As a comparison, charcoal for agriculture (soil amendment) or commonly called biochar has a wide range of quality or specifications, namely lower fixed carbon (FC), higher ash content and higher volatile matter, especially in agro type biochar according to WBC (World Biochar Certificate), while premium type biochar according to WBC has a higher or highest quality and can be used for various purposes. While the material type biochar according to WBC has the lowest quality with use mainly in certain industries such as cement, asphalt, plastic, electronics, and composite materials or cannot be used for agriculture, soil applications and consumer products.

Raw materials for charcoal production for activated carbon production because it requires stricter parameters, especially high fixed carbon, low ash content and high hardness so that raw materials suitable for this purpose are more limited or not all biomass can be used for charcoal production for activated carbon raw materials. This is what makes coconut shells the best and most popular raw material for charcoal production as activated carbon raw materials today. And palm kernel shell raw materials (especially from dura variety) are expected to be the next candidate. The availability of abundant palm kernel shells (PKS) is a special attraction. But indeed with this palm kernel shell (PKS) charcoal raw material, there is still the smell of palm oil, so it is a challenge for activated carbon producers.

Continuous Activated Carbon Production is More Efficient With Integration JF BioCarbon Continuous Carbonization and Rotating Kiln Activation Unit

Charcoal production as raw material of activated carbon with continuous slow pyrolysis (carbonization) technology very efficient in terms of the energy efficiency, product quality of charcoal is produced, the production process in an easy and environment friendly and many type of outputs is the produced by slow pyrolysis process beside the charcoal namely syngas, biooil  and biomass vinegar, which are all valued economically. Accurate process control as well as production capacity of medium-large scale highly profitable to process a large number of raw materials or that will make activated carbon plant in medium-large scale with high quality.

The size of activated carbon usually on granul or powder which is also very suitable with application of the technology. Charcoal production with JF BioCarbon technology for raw materials of activated carbon will be in the form of granul with capacity is around 20 tons to 70 tons per day which is processed by steam activating so that it would be activated carbon. With raw materials of charcoal is produced then activated carbon plant with capacity 6 - 25 tonnes per day can be made. Charcoal from coconut shell and palmkernel shell are the most common  used in the activated carbon production because its hardness. Iodine number is other parameter the quality of activated carbon besides its hardness. With steam activation, the iodine number that can be reached around 1000 while when combined with chemical activation then the iodine number that can be reached above 2500.

  By setting up the operational process condition such as temperature and residence time then charcoal with high fixed carbon can get and after the process conditions has been obtained for charcoal product with that specification that is desired then the hot charcoal can immediately feed into the  rotating kiln activation unit  without cooling beforehand, so that will save energy consumption significantly especially in the steam activation process. Syngas from pyrolysis will be used in the activation process to produce steam and keep the temperature of activation. Excess syngas after being used in process activation, then can be used to generate electricity or other energy source.

Go Green With Sustainable Energy For All

UN Secretary-General BanKi-moon has called on governments, the private sector and society to commit to his Sustainable Energy for All Initiative at the World Future Energy Summit (WFES) in Abu Dhabi, UAE.

In his keynote at WFES, Ban Ki-moon said he has designated sustainable development as his top priority for his next five-year term, and he has set out three objectives to be achieved by 2030:

1. Universal access to modern energy services;
2. Double the rate of improvement of energy efficiency; and
3. Double the share of renewable energy in the global energy mix.

Work on an Action Agenda has already started.Energy transforms lives, businesses and economies. And it transforms our planet — its climate, natural resources and ecosystems. There can be no development without energy.

Biomass is the fourth largest energy source in the world. In contrast to water, wind and solar thermal, biomass is the only energy source that does not depend on the weather in order to ensure stable energy production. Most of the biomass has been used optimally in developed countries, but otherwise there are still many untapped in developing countries. Yet millions of tons of biomass produced annually as a result of agricultural and agro-industrial residue.

Pyrolysis is a technology to process biomass into high-grade fuel. Application of pyrolysis products that biochar can also improve soil fertility. Problem is the lack of electricity supply is a common problem especially in developing countries. According to Ban Ki-moon one in five residents of this planet do not have access to electricity services. Syngas produced from continuous pyrolysis can be used to power plants in remote areas that are rich in potential biomass. 

Effect of Heating Rate in Pyrolysis Process

The rate of heating of the biomass particle has an important influence on yield and composition of the product. Rapid heating to a moderate temperature (400-600 oC) yields higher volatiles and hence more liquid, while slower heating to that temperature produces more char. The operating parameters of a pyrolyzer are adjusted to meet the requirement of the final product of interest. Tentative design norms for heating in a pyrolyzer include the following :

-To maximize char production, use a slow heating rate (<0.01-2.0 oC/s), a low final temperature, and a long gas residence time.
-To maximize liquid yield, use a high heating rate, a moderate final temperature (450-600 oC), and a short gas resiedence time.
-To maximize gas production, use a slow heating rate, a high final temperature (700-900 oC), and a long gas residence time.

Production of charcoal through carbonization uses the first norm, more detail about our pyrolyzer please click here or if you want more considerations about charcoal production please click here.

Selection of Pyrolysis Technology to Produce Charcoal from Biomass

Pyrolysis is a thermochemical decomposition of biomass into a range of useful  products, either in the total absence of oxidizing agents or with a limited supply that does not permit gasification to an appreciable extent. It is one of several  reaction steps or zones observed in a gasifier if we use gasification application. During pyrolysis, large complex hydrocarbon molecules of biomass break down into relatively smaller and simpler molecules of gas, liquid, and char.

Pyrolysis has similarity to and some overlap with processes like cracking, devolatilization, carbonization, dry distillation, destructive distillation, and thermolysis, but it has no similarity with the gasification process, which involves chemical reactions with an external agent known as gasification medium. Pyrol-ysis of biomass is typically carried out in a relatively low temperature range of 300 to 650 °C compared to 800 to 1000 °C for gasification. Other review the difference between pyrolysis and gasification, please click here.

The product of pyrolysis depends on the design of the pyrolyzer, the physical and chemical characteristics of the biomass, and important operating parameters such as

-  Heating rate

-  Final temperature (pyrolysis temperature)

-  Residence time in the reaction zone

Besides these, the tar and the yields of other products depend on (1) pressure,  (2) ambient gas composition, and (3) presence of mineral catalysts (Shafizadeh, 1984).

By changing the final temperature and the heating rate, it is possible to change the relative yields of the solid, liquid, and gaseous products of pyrolysis.  Rapid heating yields higher volatiles and more reactive char than produced by  a slower heating process; slower heating rate and longer residence time result in secondary char produced from a reaction between the primary char and the volatiles.

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Type of Pyrolysis

Based on heating rate, pyrolysis may be broadly classified as slow and fast. It is considered slow if the time, theating, required to heat the fuel to the pyrolysis temperature is much longer than the characteristic pyrolysis reaction time,  tr, and vice versa. That is:

-Slow pyrolysis: theating is bigger than tr

-Fast pyrolysis: theating is smaller tr

These criteria may be expressed in terms of heating rate as well, assuming a simple linear heating rate (Tpyr/theating, K/s). The characteristic reaction time, tr, for a single reaction is taken as the reciprocal of the rate constant,  k, evaluated at the pyrolysis temperature (Probstein and Hicks, 2006, p. 63).

There are a few other variants depending on the medium in and pressure at which the pyrolysis is carried out. Given specific operating conditions, each process has its characteristic products and applications. In the following list, the first two types are based on the heating rate while the third is based on the environment or medium in which the pyrolysis is carried out: (1) slow pyrolysis, (2) fast pyrolysis, and (3) hydropyrolysis.

Slow and fast pyrolysis are carried out generally in the absence of a medium.  Two other types are conducted in a specific medium: (1) hydrous pyrolysis (in H2O) and (2) hydropyrolysis (in H2). These types are used mainly for the production of chemicals.

In slow pyrolysis, the residence time of vapor in the pyrolysis zone (vapor residence time) is on the order of minutes or longer. This process is used primarily for char production and is broken down into two types: (1) carbonization and (2) conventional.

In fast pyrolysis, the vapor residence time is on the order of seconds or milliseconds. This type of pyrolysis, used primarily for the production of bio-oil and gas, is of two main types: (1) flash and (2) ultra-rapid. Carbonization produces mainly charcoal; fast pyrolysis processes target production of liquid or  gas.

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Production of charcoal through Pyrolysis

Carbon is a preferred product of biomass pyrolysis at a moderate temperature.  Thermodynamic equilibrium calculation shows that the char yield of most biomass may not exceed 35%. See table below gives the theoretical equilibrium yield of biomass at different temperatures. Assuming that cellulose represents biomass, the stoichiometric equation for production of charcoal (Antal, 2003) may be written as :

 

Charcoal production from biomass requires slow heating for a long duration but at a relatively low temperature of around 400 °C. An extreme example of a pyrolysis or carbonization is in the coke oven in an iron and steel plant, which pyrolyzes (carbonizes) coking coal to produce hard coke used for iron extraction. This is an indirectly pyrolyzer that operates at a temperature exceeding 1000 °C and for a long period of time to maximize gas and solid coke production.

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The best biochar  for improving soil quality (agricultural application) can be produced with slow pyrolysis process, more review on this, please click here.  The best charcoal for activated carbon production also can be produced with this process, more explanation please click here. We can also produce high fixed carbon charcoal with this technology, read more click here. In simple words we will produce charcoal as you wish.