Modernization Charcoal Production with Continuous Pyrolysis

Charcoal production and charcoal marketing have not been treated by strict rules such as wood pellets. This is mainly due to the large number of charcoal producers, with a small average production and traditional production technology. In addition, the market or buyer also does not require large volumes and long-term contracts. The quality factor remains an important standard, especially for the export market. But it could be that more stringent rules will also apply to production and marketing, given the potential damage caused. The low conversion of traditional charcoal kiln, which is an average of 15%, makes the need for wood raw materials extra, so that to produce 1 million tons of raw materials is needed about 6.5 million tons of wood. The approach to using efficient technology is increasingly urgent especially to serve large and continuous needs. Pyrolysis or continuous carbonization is the solution to this, with a conversion rate to charcoal reaching 30% or almost one third. With this efficient technology, only 3 million tons of wood is needed, or only half that means saving about 3 million tons of wood raw material.

Another motivation for using continuous pyrolysis technology is the high efficiency of energy savings that can be obtained. In charcoal production traditionally more than 60% of energy is lost during the production process. This can be illustrated in making charcoal from coconut shells. Conversion from raw materials to charcoal is only 15-25% in the process of traditional carbonization / pyrolysis. For example, we take a conversion of 25% (the best estimate), with a raw material of 10 tons of coconut shell, then 2.5 tons of charcoal are produced. Coconut shell with a heating value of around 4,500 kcal / kg, meaning that 10 tons of raw material is 45,000,000 kcal. While coconut shell charcoal with a heating value of around 8,000 kcal / kg, then 2.5 tons of charcoal will have a heating value of 20,000,000 kcal / kg. Based on these calculations more than 50% of energy is lost or is only wasted, ie 25,000,000 kcal. If the conversion to charcoal is lower or 20%, the energy loss is even greater, namely 29,000,000 kcal or more than 60%. Of course it is very inefficient and a lot of energy waste.

Whereas in the continuous pyrolysis process almost all energy can be utilized. Syngas and biooil are two types of by-products from pyrolysis that can be used as energy sources. Based on this, not only is conversion increasing, resulting in a reduction in raw materials which are also used by side products that can be used as energy sources. At present there are very few people who are thinking of utilizing the energy lost during the carbonization / pyrolysis process, this is because most people only think about how to increase the conversion to the charcoal. The loss of energy during the carbonization process is unknown or not realized by mostly charcoal producers in particular.

The use of 'lost energy' when the carbonization / pyrolysis process becomes another form of energy is certainly very good and adds value to its benefits. Electricity and heat are the two most needed forms of energy, so the conversion of 'lost energy' or pyrolysis / carbonization byproducts to become electric and heat energy is the best use scenario today. A number of regions or regions in the world still have low levels of electricity access. Africa, for example, on average has a low level of access to electricity, which is less than 30%, whereas in this region is the largest charcoal producer in the world which reaches 50% of global global production. By using continuous pyrolysis, this area, in addition to being the largest charcoal producer and even with a higher conversion, will also have access to electricity with the construction of a power plant fueled by the pyrolysis / carbonization by-products.

Charcoal is an energy product from biomass processing, especially wood. Wood charcoal has been known for a long time and is produced in a number of places. The process of producing wood charcoal is generally traditional, takes a long time and the quality is not uniform. According to FAO, global wood charcoal production in 2015 was recorded at more than 50 million tons and about half of it was produced in Africa. That means with the assumption that the conversion rate of 15% requires biomass, especially wood as raw material, as much as 333 million tons every year with 167 million tons coming from Africa. If the conversion rate to charcoal can be increased to 30% or two times, then the need for raw materials will decrease drastically or only half, namely 167 million tons globally and 83.5 million tons from Africa. What a very significant savings effort.

Every year Europe imports 1 million tons of charcoal, as well as Saudi Arabia and Middle Eastern countries import more than 1 million tons of charcoal. Saudi Arabia and the Middle East mainly use charcoal to roast lamb, a favorite food there. The use of charcoal in general is mostly the household sector with retail distribution. In addition charcoal is also used for metallurgy, agriculture (biochar) and activated charcoal (activated carbon) raw materials.

Continuous Pyrolysis for Palm Oil Mills

A number of regions have been over-supplied with electricity so it is not possible to add or build new power plants. Making a new plant will only be in vain because the electricity production cannot be utilized or absorbed by the user. Based on this, electricity production in a number of areas must be limited and diversified into other products needed. These other products are products whose needs are still not met. Another thing that can be done is to increase the efficiency of a production process. When the efficiency of a production process is improved and produces the products needed, of course the business benefits increase. Besides that, when all the waste can be processed, it becomes a production unit that is zero waste and environmentally friendly.

Palm oil mills are very numerous in Indonesia and Malaysia, the number reaches more than 1000 units, while Thailand also begins to follow the planting of oil palm. At present some of the palm oil mill effluents have not been processed such as empty palm bunches, palm shells and fronds. The palm oil mill that has been operating can be increased efficiency and the production of by-products that provide additional income. This can be done by using a continuous pyrolysis unit for both electrical and heat energy sources and the production of various by-products in the form of charcoal, biooil and biomass vinegar. The three by-products can be sold or marketed and become an additional income for the palm oil mill which is quite attractive.

Conventional Energy System in Palm Oil Mill

Improved Palm Oil Mill with Continous Pyrolysis System

Palm oil mills also do not need to be bothered with the problem of waste, especially solid waste if everything can be processed and very profitable. Meanwhile, from the environmental aspect of a palm oil mill that is zero waste and environmentally friendly, it is certainly the dream of all the palm oil mill owners. The community and the surrounding environment which is not disturbed by the palm oil mill that is because of its pollution is also a condition desired by the palm oil entrepreneurs. By using the continuous pyrolysis, the air pollution generated is very minimal or far from the required threshold, so that the environment and the surrounding community can be accepted. If the palm oil mills have used continuous pyrolysis, it will also be economically attractive.

Charcoal produced also has many benefits. Technically, charcoal is a stable fuel so it is easy to store and does not decay or is eaten by termites. Charcoal can be used for energy sources directly easily, or converted to other fuels, for example converted into liquid or gas fuel. The condition of fossil fuels, especially petroleum which is increasingly depleted, demands the diversification of energy, such as Indonesia which is predicted to run out of oil in 10 years or in 2028. Likewise, biooil can be used immediately, or upgraded to better fuels, such as vehicle fuel. While biomass vinegar can be used for fertilizer, biopesticides and upgraded to biophenol and wood adhesive.

Palm Kernel Shell Continuous Pyrolysis For Multipurpose Production

Production of palm kernel shells (PKS) which is palm oil mill waste in Indonesia approximately 9 million tons. Current utilization of 20% (1.8 million tons) for export, 15% (1.35 million tons) for internal use, 10% (0.9 million tons) for domestic (local) use, and the remaining 55% (4.95 million tons) yet used or become waste. Meanwhile, Indonesia's CPO production currently reaches 35.2 million tons, or 20% of FFB (Fresh Fruit Bunch), so the number of FFB (Fresh Fruit Bunch) produced in Indonesia currently ranges from 176 million tons. With an average productivity of 20 tons / hectare of FFB, so the FFB is generated from 8.8 million hectares. While the total area of ​​oil palm plantations in Indonesia is currently estimated to have almost 12 million hectares including unfruitful and unproductive age or need to be replanting. Another influential factor is the low level of productivity of oil palm plantations. Palm kernel shells are only about 6% of the FFB produced, and after is used for the internal CPO production process in the mill  with mesocarp, only about 4.5% of the palm kernel shell is the waste of the palm factory. From there it can also be calculated that every hectare of oil palm plantation will produce 1.2 tons or three quarters namely 0.9 tons of waste. With the current expansion of oil palm plantations up to 12 million hectares, the potential of palm kernel shells that become waste in the palm oil plant around 10.8 million tons or the amount of 10.8 million tons that can be used for export, fuel and production of various other products or external use.

Currently, there are a number of parties who have utilized the palm kernel shells for electricity production and boilers of some industries that are estimated to be less than 10% of the total produced palm shells. Some converting technologies into heat and electricity are used for processing such palm kernel shells. Combustion and gasification are technologies commonly used to convert or extract palm kernel shells into heat and electricity. Combustion technology in the furnace then combined ORC (Organic Rankine Cycle) and Stirling engine to convert it into electricity. While the gas from gasification is then used as fuel in gas engine to generate electricity. Are there any other options for processing the palm kernel shell so that it has bigger added value or more profitable?

Palm kernel shells are not suitable for biogas production because the lignoselulose material or rich lignin content material making it difficult to biologically decompose. The choice is pyrolysis or thermal decomposition with absence of oxygen. Pyrolysis is a technology that can to produce charcoal, biooil, pyro acid and syngas. This is what makes it possible for multipurpose production. Palm kernel shells such as rice husks, sawdust and the like are bulk materials also so will be suitable for continuous pyrolysis. How come? The answer is because there are several options for using the continuous pyrolysis:

1. Production of electricity and charcoal 

2. Production of electricity and activated charcoal

3. Production of electricity and charcoal briquettes

4. Production of charcoal and bio-chemicals

5. Production of charcoal and biofuel

6. Production of Charcoal and heat

At the production of electricity and charcoal, the process of excess syngas is used for electricity production, and charcoal is also produced as a solid product of pyrolysis. The charcoal can also be made briquette so it will be efficient during transportation and its use. As for the production of electricity and activated carbon, then excess syngas is used for the process of activation of the charcoal produced, with a more detailed explanation can be read here. In addition to charcoal, bio-chemicals such as acetic acid, methanol and phenol can also be produced by processing further byproducts namely pyro acid and syngas. Biofuels namely, biooil and syngas can also be additional products besides charcoal. Syngas can also be packed in a tube for ease of distribution and usage. Meanwhile, if syngas and biooil are burned it will generate heat, so if the business of charcoal production in combination with agriculture such as the use of green house or also farms that require a warm certain temperature the continuous pyrolysis unit becomes also very effective to be used. 

Charcoal production from palm kernel shells can also be a solution to the high export tax of palm kernel shells. By processing it into finished product then the tax should be decreased even eliminated because there has been industrialization which also absorb labor and encourage economic growth. In private power producers or IPP (Independent Power Producer), the additional product namely of charcoal will provide an increase business revenue, so that their business becomes more attractive business. In addition to charcoal production, if you want the production of high quality solid fuel (solid biomass fuel) namely by upgrading or processing it with torrefaction, can be done also with pyrolysis technology.

The Importance Of Standard Biochar

Biochar and charcoal are similar materials with different purposes. Charcoal, a fuel and metal reductant,is considered to be the oldest man-made material. The advantage of charcoal is that it burns with less smoke, which is advantageous when cooking indoors. In addition, charcoal burns hotter than wood, which allows it to be used for metal forming, such as in blacksmithing.

Adsorption is a pivotal property that distinguishes biochar from other carbon-rich natural products. Adsorption also distinguishes superior biochars from less effective “agricultural charcoals”. Since biochar is so new, there are no analytical methods developed specifically to measure adsorption in biochar, nor any experience base to relate adsorption to biochar impact when added to growing system. Thus,  urgently needed the standard biochars. Following paper will give analytical options for biochar adsorption and surface area, please go 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.