Biomass Boiler Testing and Selection of Suitable Biomass Fuel

In line with the trends toward decarbonization and sustainability across various sectors of life, particularly in the processing industries (manufacturing/process industries), the use of biomass boilers has become a realistic option today among boilers that utilize other renewable energy sources. Fossil-fuel-fired boilers—such as solid-fuel boilers (coal), liquid-fuel boilers (industrial diesel), and gas-fired boilers (natural gas)—must be replaced with renewable fuel boilers, namely biomass boilers. Apart from technical factors in the form of operational adjustments from previous fossil-based fuels, the suitability and availability of biomass fuels are important factors. Suitability refers to the technical aspect and availability refers to the economic aspect.

Combustion technology for biomass boilers also continues to develop so that efficiency continues to increase. From the beginning in the form of static grates to dynamic moving grates such as chain grates and reciprocating grates, even fluidized beds. And to get optimal performance, biomass fuel specifications must also match the shape, size, calorific value and dryness. If the specifications do not meet the requirements of the combustion technology in the boiler then of course the performance will not be optimal. For example, chain grates are suitable for using fuel that has a uniform size and low water content such as palm kernel shells, wood chips and wood pellets. Apart from that, biomass fuel with ash content which has a high melting point is highly preferred so that the ash does not melt and clog the chain lattice cavity.

Meanwhile, using a reciprocating grate, this system is very reliable for burning biomass with high moisture content (up to 60%), non-uniform size, and high ash content, such as empty oil palm fruit bunches (EFB), bark, and municipal solid waste (MSW). The combustion system moves back and forth periodically (like a moving staircase that moves back and forth) which functions to mechanically turn and stir the fuel. And for fluidized beds, this system has the highest thermal efficiency (>89%) and is very suitable for biomass with very small size (powder/dust), low calorific value, or fluctuating chemical content such as rice husks, sawdust, and coffee grounds. The biomass particle size must be maintained within certain limits so that it can float and fluidize perfectly with the sand bed media. The ideal particle size for a fluidized bed boiler (FBC) generally ranges from 0.1 mm to 10 mm (maximum 30–50 mm for certain components), depending on the specific type of technology used.

As a country located on the equator with a tropical climate, Indonesia is a biomass paradise in the world; read more here. A wide variety of biomass fuels in large volumes can be sourced in Indonesia. The most readily available biomass fuels in Indonesia today are wood chips, palm kernel shells, and wood pellets. Wood briquettes are also available but in limited quantities. Choosing the right biomass fuel will ensure optimal boiler performance, but of course, the economic factors for each metric ton of high-pressure steam produced are equally important. 

Ideally, biomass fuel is available in large quantities, ensuring affordability and high quality. The price of biomass fuel is influenced by various factors, including availability, location, logistics infrastructure, and transportation costs. Furthermore, if the biomass fuel undergoes processing, such as wood pellets and briquettes, production costs also contribute. Palm kernel shells for industrial boiler use in Indonesia require almost no processing; they are simply collected from palm oil mills or CPO mills, which produce waste in the form of palm kernel shells (PKS).

There is a case study regarding the selection of this biomass fuel involving a multinational company. In a certain country, the company’s boilers operate using wood briquettes—specifically, industrial briquettes produced by a mechanical press. This approach was also planned for the company’s plant in Indonesia. However, because producers of wood briquettes are still very scarce in Indonesia—making it impossible to secure a supply—the company ultimately conducted various experiments and trials with different types of biomass fuels and now operates its boilers using wood pellets. Thus, in addition to technical factors, economic factors are also crucial for ensuring optimal and sustainable biomass boiler operations. The trial phase is a critical step in achieving these conditions. 

Palm Oil Mill: Just Replacing Boiler? Or Are You Also Looking for a Solution to Address the Problem of Empty Fruit Bunches and Generate Additional Profits?

As palm oil plantations in Indonesia continue to expand—currently covering approximately 17 million hectares—the demand for palm oil mills is also increasing. About 10 years ago, there were approximately 1,000 palm oil mills in Indonesia, but according to the latest data from the Ministry of Agriculture of the Republic of Indonesia, the number of active palm oil mills (POM) in the country is now estimated to be between 1,200 and 1,500. These palm oil mills are primarily located on Indonesia’s two largest islands: Sumatra (52.69%) and Kalimantan (42.71%), while the remainder are in Sulawesi, Papua, and several other islands, where their presence is relatively small (each accounting for less than 3%). In terms of ownership, the majority of palm oil mills in Indonesia are owned by large private companies (93%), with the remainder owned by state-owned enterprises (7%). A single large private company may own a dozen or even dozens of these palm oil mills. 

One of the main equipments for palm oil mill operations is the boiler. In fact, given the current palm oil mill production process, boilers are mandatory for palm oil mills; more details on the reasons can be found here. Boilers can also be considered the "heart" of a palm oil mill, converting water into high-pressure steam to run the production process and generate electricity for the mill and its employee housing. Like all production equipment, boilers have a lifespan. When a boiler's lifespan is exceeded, it becomes not only uneconomical due to high maintenance and operational costs, but also dangerous.

The average lifespan, which is the technical and economic life of a palm oil mill boiler, is 20 years. Once this lifespan is exceeded, investing in a new boiler becomes more profitable. The majority of palm oil mills in Indonesia use water tube boilers (e.g., Takuma or Vickers). This type of boiler circulates water through hundreds of externally heated pipes fueled by palm oil waste in the form of shells and fibers. Because these pipes interact directly with extreme heat and water scale, these internal components wear out most rapidly. The three main factors affecting the boiler's lifespan are boiler feedwater quality, fuel characteristics, and regular maintenance.

When the time comes to replace the boiler, and considering the mountains of unused empty fruit bunches (EFB), palm oil mills might consider using them as boiler fuel. But given their large size and high moisture content (>60%), how can they do that? This is certainly a reasonable and innovative idea, given the urgency of replacing the boiler and simultaneously facing the problem of biomass waste. Technically, as biomass waste, it can certainly be used, but is it economically feasible to treat or prepare the empty fruit bunches (EfB) until they are ready for use as fuel? This is the challenge.

Proven evidence will dispel any doubts or theoretical narratives. Likewise, a unit that can process empty fruit bunches (EFBs) and also serve as an additional energy source for boiler operations (cogeneration) at the palm oil mill. With this equipment, not only can the problem of empty fruit bunch (EFB) biomass waste be resolved, but the palm kernel shells (PKS), which have been used as boiler fuel along with the fiber, can be 100% sold directly, providing a source of income. Furthermore, the potassium-rich ash content of empty fruit bunches (up to 30%) also has the potential to be used as fertilizer, including for use on the palm oil plantation. For more details, please read here. Visiting and observing the unit in action can also serve as a means of proving the point, thereby increasing the confidence of palm oil mills interested in this solution.

Beyond technical factors, economic considerations will undoubtedly be a crucial consideration in implementing this equipment. By considering several factors, particularly those currently operating in the palm oil industry, a comprehensive and accurate economic analysis can be conducted to reach a decision on use of the equipment. In an era of renewable fuels, efficiency, zero waste, and increased profitability, this equipment, which serves as a supplemental energy source (cogeneration) for the palm oil mill's boiler, is worth considering for palm oil mills currently facing boiler replacement. 

OPT Briquette and EFB Briquette for Medium Capacity Industrial Biomass Boiler Consumption

The growing utility business, specifically the provision of steam and electricity for renewable energy-based industries, particularly biomass, has led to a growing need for biomass fuel. This also applies to industries using their utility units to produce steam and electricity using biomass fuel. In addition to biomass fuel, water quality, the raw material for steam and electricity production (using steam turbines), is also crucial and must be considered. Good water quality will ensure optimum steam and electricity production performance, and the longevity of equipment (boilers, heat exchangers, steam turbines, and cooling towers), and vice versa. Good water quality is like healthy blood for our bodies, enabling all organs to function optimally.

Palm oil industry solid waste is a potential raw material for biomass fuel. This solid waste is empty fruit bunches (EFB) and oil palm trunks (OPT). EFB is produced from palm oil mill operations with a percentage of approximately 22% of fresh fruit bunches (FFB), while oil palm trunk waste is produced from replanting programs of oil palm plantations, which are also very abundant. For more details, read here. Utilizing both of these biomass wastes for the production of biomass fuel, especially biomass briquettes, would be very good. But why are they processed into briquettes?

The advantage of briquettes over pellets, aside from technical advantages, lies in their scale. Briquette production requires a looser particle size and lower moisture content. Energy consumption per ton of briquette production is also lower than that of pellet production. This makes EFB briquette and OPT briquette production more suitable for a palm oil mill serving medium-sized industries. A palm oil mill with a capacity of 45 tons/hour of FFB will produce approximately 10 tons/hour of EFB. With a 20-hour daily operation, approximately 200 tons will be produced per day. With a moisture content of approximately 60%, this means that after drying, approximately 100 tons/day (10% moisture content) will be produced, or 2,500 tons/month.

Likewise, when using oil palm trunk (OPT) waste as raw material, it depends on the ratio or percentage of land replanted each year. Replanting itself is an effort to continuously maintain the productivity of the oil palm plantation itself, in addition to the use of superior seeds and intensification. For more details, read here. For example, with a land area of ​​10,000 hectares and each year replanting 5% of the land, or 500 hectares. With an average of 125 trees per hectare of oil palm plantation and each tree having an average dry weight of 0.4 tons, then per hectare obtained 50 tons of dry weight of biomass. With an area of ​​500 hectares, this means 25,000 dry palm trunk biomass (10% moisture content) each year or can be processed into OPT briquettes with a capacity of around 2,000 tons/month.

Biomass boilers, used for producing biomass briquettes (EFB briquettes/OPT briquettes), can utilize various combustion technologies, such as moving grates, stokers, reciprocating grates, and so on. The choice depends on the cost or price of the boiler and its efficiency. In addition to biomass fuel, to align with decarbonization and sustainability programs, water for boiler operation, including boiler feedwater and cooling water for heat exchangers (heat exchangers/condensers), is crucial. This is likened to blood for the human body; healthy blood ensures optimal function. If impure blood circulates throughout the body, for example due to kidney failure, organs will automatically be damaged, and a person will soon die.

To maintain water quality for steam production through a boiler, boiler feedwater/demin water must strictly comply with the boiler's operational specifications. The higher the boiler pressure, the higher the water quality or purer the water required. If the steam is used for electricity production, after the steam drives the turbine, it needs to be condensed in a heat exchanger (condenser) so that it changes phase back to liquid and enters the boiler again. This heat exchanger requires cooling water that is continuously used repeatedly, thus requiring a cooling tower. Not only does the boiler feedwater/demin water need to meet the required technical specifications, but so does the cooling water for this condenser. With water volumes circulating up to thousands of tons per hour and operating 24 hours a day (the same as boiler operations) in the cooling tower, a number of water problems in the cooling tower need to be addressed effectively and efficiently. A number of water problems that occur in cooling towers can be read here.

In addition to electricity production, steam is also used for processes within a specific plant. If the steam is then condensed, then liquid, and returned to the boiler, this requires a cooling tower, just as in electricity production. Efficient and environmentally friendly water treatment technology, which eliminates secondary pollution and is easy to operate and maintain, aligns with the vision of decarbonization and sustainability. This vision of decarbonization and sustainability will be even more optimal or ideal for utility units, namely the use of biomass-based renewable energy and environmentally friendly water treatment technology. 

Processing of Empty Palm Fruit Bunches (EFB) for Ash Production as Potassium Fertilizer and Energy

Palm oil mills produce a large amount of biomass waste, and one of the largest in their daily operations is empty fruit bunches (EFB). Comprising approximately 22% of the fresh fruit bunches (FFB) processed by the mill, the volume becomes enormous and piles up daily if not managed properly. For example, a palm oil mill with a capacity of processing 60 tons of FFB per hour for 20 hours per day produces 264 tons of empty fruit bunch waste per day (approximately 6,600 tons per month and 79,200 tons per year). This enormous amount would resemble a hill if piled up in one place.

Incinerators have recently become popular, particularly in Indonesia, for processing empty fruit bunches due to their speed and practicality. Furthermore, the ash produced by burning them can be used as fertilizer due to their high potassium content. However, these incinerators produce exhaust emissions that pollute the environment, including black smoke and particulate matter. These emissions, which pollute the environment and exceed the threshold permitted by the Ministry of Environment (KLH), have led to the prohibition of incinerators. This ban has led to an increasing number of unmanaged empty fruit bunches. Using empty fruit bunches for mulch is also less effective, and composting, a biological process, takes a long time.

Video link for conventional EFB incinerator here

This problem demands an immediate and effective solution. The quickest practical solution is to upgrade the incinerator to make it environmentally friendly or to reduce emissions below the required threshold. This can be achieved by using adequate emission control devices to meet these environmental requirements. While many emission control devices are available, cost and target output are crucial considerations when selecting them. This approach not only addresses the problem of empty fruit bunches, but the resulting ash can also be used as a potassium fertilizer.

Furthermore, by upgrading the incinerator with emission controls (basic type), the equipment can be developed into several types, as follows: the second type is a cogeneration boiler for palm oil mills, allowing 100% palm kernel shell (PKS) to be sold, even for export. The third type is by adding a new boiler and steam turbine for electricity production, which is then sold to PLN (Indonesia State Owned Electricity Company) under a power purchase agreement (PPA). The fourth type is equipped with waste heat recovery equipment, allowing for more general use. This also means the combustion process in the upgraded incinerator can also be upgraded so that the combustion process can run optimally. Several combustion technologies, such as chain grates, step grates, or reciprocating grates, can be considered to achieve maximum performance, including the removal and handling of ash product.

Empty fruit bunches (EFB) processing can vary, although the primary focus is addressing environmental pollution caused by them. However, their large volumes certainly represent a potential raw material for processing units. Therefore, in addition to addressing this waste, the technology used must also provide financial benefits. Of the numerous EFB processing technology options, the cost-to-benefit ratio of a technology application will be a crucial consideration for EFB processing.

In addition to combustion using conventional or this upgraded incinerator, thermal processing routes also include pyrolysis, with slow pyrolysis specifically for biochar production and fast pyrolysis for bio-oil production. Another pyrolysis variant is mild pyrolysis or torrefaction for the production of torrified biomass. Then there's gasification to maximize gas (syngas) production from biomass. Furthermore, empty fruit bunches of palm oil can be used as fuel or an energy source. To facilitate handling, storage, and reduce transportation costs, empty fruit bunches need to undergo biomass densification technology, with the final product being pellets or briquettes. 

Hydraulic Press Type Biomass Briquettes, Efficient for Small Capacity

Wood processing factories and sawmills that produce small amounts of wood biomass waste, such as 5-10 tons per day, can process it into value-added products, namely briquettes. Briquettes and pellets both use biomass densification technology, but pellets are far more popular than briquettes. Wood pellets are typically used for large-scale power plants with annual demand of tens or even hundreds of thousands of tons. Briquettes (wood briquettes) are typically used for smaller capacities, and there are also wood briquettes for special applications, such as charcoal and BBQs. The question is, which type of wood briquette is suitable for this small amount of waste?

Compared to wood pellets, which only use one type of production technology—a roller press—wood briquette production uses three types: piston press, mechanical press, and screw press. For more details, read here. Of the three, hydraulic wood briquette is the most suitable type for processing this "small" amount of waste. This is because it uses the least electricity, can operate automatically, and is stable, even for 24/7 operation. The sawmill and wood processing industry, in addition to achieving clean production units (zero waste), also benefits from contributing to renewable energy.

Technically, briquette production is also easier than pellet production, due to the looser moisture content and particle size. Even for abrasive biomass materials, briquetting, particularly with piston presses and hydraulic presses, can handle these materials more effectively than roller-press pelletizing. The wear and tear on equipment in pelletizing these materials is much greater, while in briquetting, this is much less. This is because the contact area during pressing/compaction in pelletizing is much larger than in briquetting. Therefore, in briquetting, it is easier to replace certain machine components that wear out due to abrasive materials, unlike in pelletizing, which requires replacing dies and even rollers.

As the era of decarbonization accelerates, the use of renewable fuels, particularly biomass, such as wood waste, is also growing. Briquetting, particularly hydraulic press briquettes, simplifies handling and use in furnaces. Biomass boilers that feed fuel manually will easily utilize these hydraulic press briquettes. Small and medium-sized industries using small boilers will be able to utilize these hydraulic press briquettes.

Industrial Wood Briquette Becomes an Alternative Between Wood Chips and Wood Pellets

Biomass fuel is a renewable fuel or renewable energy that is currently positioned as one of the alternative fuel. However, along with awareness of various climate problems, the use of alternative energy from biomass has increased over time. The decarbonization trend as a response to climate problems has penetrated all lines of life including the industrial sector. As a profit-oriented industry, of course, efforts to maximize are a major concern, including in the use of alternative fuels. There are various types of fuels that can be produced from biomass and especially for solid fuels, including wood chips, wood pellets and wood briquettes. The characteristics of these fuels are slightly different from one another, including their production costs. It is necessary to look more carefully and deeply so that you can get the best biomass fuel according to the goals of the industry.

Industrial briquette can be produced in large quantities at a lower cost than briquette produced with hydraulics or extruders. And when compared to wood pellets, industrial wood briquette is also cheaper to produce. But of course the production cost is more expensive than wood chips. Wood chips can be said to be the easiest and cheapest biomass fuel to produce.

This places industrial wood briquette in a position between wood chips and wood pellets or hydraulic and extruder type briquettes. As a biomass densification product, industrial wood briquette is also more economical for long-distance transport. In addition, a number of industrial boilers have also been specially designed to be able to use industrial wood briquette fuel, even with automatic feeding. Other factors such as uniformity of shape, size can vary and low water content are other advantages of industrial wood briquette.

Boiler users in industry and even coal power plants can consider using industrial wood briquette. Especially for companies engaged in industrial utilities such as steam providers for processing industries so that the operation and maintenance of the boiler including the use of biomass fuel is the responsibility of the company. With a long-term steam supply contract, for example around 5-10 years, the provision of biomass fuel in the form of industrial wood briquette within that period is also very important. In addition to the availability of sufficient, legal and sustainable raw materials, the reliability aspect of industrial wood briquette production machines cannot be ignored.

 

Utility Business for Palm Oil Mills

When the priority is to obtain the maximum profit, good environmental management and ease, efficiency and stability of production as an option, then utility matters at the palm oil mill may be collaborated with other parties. This specialization becomes important because of the priority choices above. The utility problems in question are electricity and steam. Electricity is produced from a steam turbine and steam is produced from a boiler. High pressure steam enters the steam turbine to drive a generator and produce electricity and low pressure steam output from the steam turbine is used for the fresh fruth bunch (FFB) sterilization process. Water treatment for boiler feed is also part of the utility problem, as well as for boiler operations to produce output in the form of electricity and steam.

Regarding cooperation or business models, palm oil mills can pay for the electricity and steam they receive. But because the fuel or energy to produce electricity and steam comes from palm oil mills, of course the price is cheaper. If currently almost all palm oil mills use their boiler fuel from mesocarp fiber and palm kernel shell (PKS), then with this specialization it is possible for palm fiber (mesocarp fiber) and empty palm fruit bunches (EFB) to be used as fuel or energy sources while palm kernel shells (PKS) can 100% sold and even exported. Palm kernel shells (PKS) as biomass fuel can be sold directly and are in great demand, and are also the main competitor for wood pellets in the global biomass fuel market.

Under these conditions, there are efforts to increase the efficiency of utility production such as steam and electricity as optimally as possible, not only combustion technology with static grates, moving grates, reciprocating grates to fluidized beds, but it is even possible to use pyrolysis. EFB or empty palm fruit bunches, which were previously unprocessed and were an environmental problem, can become a potential energy source so that 100% of the palm kernel shells / PKS from palm oil mills can be commercialized/sold. And even if the utility provider uses pyrolysis, biochar will also be obtained. Biochar provides many benefits related to soil fertility and climate.

Briquette For Textile Industry

As the demand to become an environmentally friendly industry enters this era of decarbonization, a number of industries have begun to switch to using renewable energy in their production processes, and the textile industry is no exception. You can read about the urgency of a biomass boiler here. A number of boilers are used in the textile industry with the type of boiler that uses a static (static grate) and dynamic (moving grate) furnace. From the operational point of view, a dynamic furnace (moving grate) is easier and more efficient because the combustion process can be more complete. In addition to general fuel specifications such as calorific value, moisture content, ash content and so on, the size and shape of the fuel is also an important factor in the efficiency of the combustion. Wood pellets with a diameter of generally 6 mm and 8 mm and palm kernel shells with a size of about 1 cm to 5 cm are sometimes not suitable for this type of boiler. For these conditions briquette can be the solution. Briquette sizes are not only bigger but also more diverse, including the briquetting technology used, for more details on briquetting technology, you can read here.

Biomass waste, both wood processing industry and agricultural waste such as rice husks, can be used as raw material for these briquettes. Briquette shapes such as pucks or cylinders or short octagonals can be a solution for certain types of boilers. Currently, there is still a lot of wood waste that has not been utilized and even polluted waters such as rivers that can be used for the production of these briquettes, more details can be read here. Meanwhile, rice as a staple food source for the Indonesian population also produces a lot of waste in the form of rice husks. Indonesia's rice production in 2008 is estimated to reach 59.9 million tons of milled dry grain with a husk composition of 25%, meaning that the husk potential reaches 15 million tons/year. Although the amount is abundant but generally its utilization is still not optimal, this is because rice husk has a low bulk density and relatively small calorific value due to the high ash content. Indeed, with biomass compaction technology such as briquetting, the biomass waste becomes easy to use, economical for long-distance transportation and overcomes environmental pollution problems.

Whereas in Indonesia, almost all of the briquettes produced are screw extrude types which are actually not very suitable for the boiler solution. This is because this type of briquette is not only long in shape and also requires a large amount of energy or electrical power for the production process. Cutting it into small pieces will be an additional job in itself. While the mechanical press type to get small pieces to form pucks is easy to do and also requires less electrical power. As a comparison, screw extrude briquettes to produce 1 tonne of briquettes require about 100 kW of electricity, while on a mechanical press to produce 1 ton of briquettes, electricity is needed only 50 kW or half. In addition, when using abrasive raw materials such as rice husk which has a high silica content for a screw extrude type briquette machine, it will only have a short life, while the mechanical press has a much longer service life.

The Urgency of Biochar Application on Palm Oil Plantations in Indonesia

The large number of acidic soils in Indonesia that are used for palm oil plantations makes the productivity of palm oil fruit or the resulting FFB (fresh fruit bunch) not optimal. The acid soil covers the largest dryland area in Indonesia. It occupies approximately 55% of the total land area (191.09 million ha) in Indonesia. About 107.36 million ha of all Indonesian acid soils is classified as dryland acid soils and the rest (14.93 million ha) as peat soil. Acid soils in Indonesia are distributed amongst the big islands, such as Kalimantan (39.42%), Sumatera (28.81%), Papua (18.03%), Java (7.77%), and Sulawesi (6.95%). Acidic soils with low pH make nutrient absorption low in plants and so do soil microbial activity, which plays a large role in soil fertility. This condition should not be ignored because besides making the cultivation of palm oil plantations not optimal, there will also be a lot of fertilizer used. This makes the operational costs of  palm oil plantation operation high. Biochar is a biomass pyrolysis product that is effective and efficient in overcoming these problems. With the abundant amount of biomass waste produced by palm oil mills or CPO mills as biochar raw materials, efforts to improve the quality of plantation soil should be easy to do and have even become the operational standard for these plantations. But the fact is not.

 

Why hasn't biochar been used to improve soil quality and thus increase the production of palm oil fruit or FFB? The lack of information and education about the benefits and uses of biochar are the main factor. This of course makes the application of biochar in palm oil plantations not yet done even though palm oil mills have abundant biomass waste such as empty palm fruit bunches (EFB) and fiber which are generally not used and cause environmental problems. The priority for processing EFB compared to other products such as EFB pellets or compost also needs separate considerations. The best choice, of course, is based on a comprehensive study according to the characteristics of the business or business will be built. Consider not only short-term economic benefits, but also environmental and long-term benefits is an important thing.

Quantitatively, an increase in the production of palm oil fruit or FFB, an increase of at least 20% with the application of biochar is something that is normal. And a 20% increase in fruit production will also result in a big profit. Productivity of a number of other agricultural commodities can be increased by 30%, 40% or even more than 100%. The low productivity of palm oil fruit in Indonesia can be increased by the application of biochar, which is particularly effective in improving the soil quality in the palm oil plantations. Moreover, about 80% of the components of the cost of producing crude palm oil (CPO) come from the plantations, and 20% in the processing sector (palm oil mills). The operational costs of palm oil mill plantations, especially fertilizers, can also be reduced by the use of biochar. The priority of liquid biofuel development will also get better if the volume of biofuel raw materials such as CPO increases. This shows the strategic role of biochar. Apart from that from the aspect of climate change, biochar will also absorb CO2 concentrations in the atmosphere or reduce the concentration of greenhouse gases, as a solution to today's world problems. 

 

Meanwhile, from the side of the palm oil mill, another advantage obtained from biochar production is the use of excess energy from the pyrolysis process or the production of biochar as an energy source for the boiler. Boiler feed water (BFW) will also be preheated twice when it is used for cooling in the pyrolysis condenser and then the economizer on the boiler. In this way, the energy needed by the boiler decreases. When the boiler energy source uses the energy source from pyrolysis, this means that the palm kernel shell (PKS) can be taken and used for other things and can even be sold directly for local and export markets. The main obstacle to business development in the palm oil industry is the availability of energy source namely electricity. If the energy source is available, the development of palm oil-based businesses is very open and varied, such as the production of CPO derivatives, palm kernel shell processing, PKO production, PKO derivative production, biomass power plants and so on.

Biomass Boiler and Its Urgency

A problem that is visible and can be felt, especially if it has a short-term impact, is certainly easy to map and find a solution to. But if the opposite namely is not visible, it is difficult to feel and the impact or effect is long-term, of course it is more difficult to map, let alone find a solution. The use of fossil fuels, especially coal in a number of industrial boilers, is an example. The effects of exhaust emissions in the form of COx, NOx and SOx may be difficult to detect at first but create environmental damage in the long term. Likewise heavy metals like mercury which also have long-term effects. Meanwhile, fly ash pollution and boiler furnace ash (bottom ash) are clearly affected more easily. In a larger case or global scale, namely climate change and global warming due to greenhouse gases, especially CO2 (carbon dicside), a global consensus is also needed to solve these problems. That is what makes the Earth Conference on Climate Change (UNFCC) always held every year, which has so far been recorded 27 times, lastly in 2019 in Madrid, Spain, while what was supposed to be held in 2020 was postponed in 2021 due to the COVID-19 pandemic. Fossil fuels including coal are carbon positive fuels so that their use will increase the concentration of CO2 in the atmosphere, while biomass fuels such as wood chips, wood pellets, wood briquette and palm kernel shells (PKS) are carbon neutral fuels. It is said to be carbon neutral because of the use of this fuel because it does not increase the concentration of CO2 in the atmosphere.

 

Boilers are essential equipment for the operation of a number of industries. The main function of the boiler is to produce steam which is used in the industrial production process. But when the boiler is not operated and maintained properly, the boiler can be dangerous. The continuity of production operations also greatly depends on this equipment, so that disruption of boiler operations will have a significant effect on this production. The boiler also consists of a number of subsystems that work in harmony, such as boiler burners and controls, water treatment for boiler feed water preparation, fuel handling and feeding and so on. Sometimes a number of subsystems are supplied from a number of different vendors, so synchronization between these subsystems is very important. This makes boiler operations safe, efficient, reliable and minimizes boiler downtime. And of all the subsystems in the boiler, the burner system is the most sophisticated subsystem in the boiler unit. The burner system has a number of operational modes that require extensive training and / or experience for boiler operators to be well understood.

Currently, a number of industries have started to switch from fossil fuels to biomass fuels. In industries that previously used solid fuels, technical changes or furnace modifications can be minor, while in industries that previously used gas or liquid fuels, the usual thing to do is replace the boiler unit (including the furnace). Of course, the replacement of the boiler unit is also followed by its supporting systems such as fuel storage, provisioning and so on. Petroleum fuels, coal and natural gas are consistent fuels with standard quality and their contaminants or impurities have been known and studied for decades. Whereas with biomass there are a number of options and each source is also unique and also the level of contaminants.

In certain cases, industries that will switch to using biomass, namely palm kernel shells (PKS), that previously using natural gas, so the industry needs to study and analyze the implications of using the PKS. And because the use of PKS for industrial fuel is relatively new, the industry can use old data about their furncae operations with natural gas and compare it to furnace that use solid fuels like coal - which is commonly used by the industry today. Although PKS is also a solid fuel, there are a number of characteristics that distinguish it from coal. In addition, gas combustion can be said to be the most ideal combustion process, which is in terms of stoichiometry or the perfection of combustion compared to combustion of liquid or solid fuels. Large particle size such as coal will also have an effect on combustion and also make a fuel more difficult to burn. So that from this comparison, the industry can get an overview of the burning of the PKS and the scheme below to describe the case.

With adequate analysis, planning and system design, the use of new fuels, especially biomass, such as wood chips, wood pellets, wood briquettes and PKS can be implemented properly. Energy prices and environmental regulations are driving forces for the use of this new fuel. Fixed bed combustion type furnaces are most commonly used in a number of industries. These furnace variants include grate furnace types namely traveling grate, fixed grate system, incline moving grate & horizontally moving grate, vibrating grate, cigar burner and underfeed rotating grate, while other types are underfeed stokers. Meanwhile, the fluidized bed and pulverized combustion types are generally used by power plants. The technical considerations for selecting biomass-based solid fuels include heating value, moisture content, ash content, density, particle size, emissions, availability of these fuels, and suitability for the furnace. In the end, the most optimal combustion rate that is safe and meets environmental standards is the purpose of using the biomass fuel.

Conversion of Industrial Furnaces and Boilers with Biomass Fuels

 

The use of biomass fuels especially palm kernel shells (PKS) has been increasing lately. This was mainly due to the high price of natural gas and non-subsidized industrial LPG. Viewed from the environmental aspect it is a progress because there is a reduction in fossil fuels (carbon positive) which causes climate change and global warming. Industries that initially used furnaces and gas-fired boilers needed to replace them into biomass, especially palm kernel shells which are solid fuels. The availability of palm kernel shells is  also very abundant inline with CPO products or palm oil plantations in Indonesia. Biomass such as wood chips, wood pellets and so on can basically be used as fuel for the furnace, but economic considerations and continuity of supplies are the main considerations. The quality of the palm kernel shell is also almost equal to the wood pellet and in the international market indeed the palm kernel shell is the main competitor of wood pellet. And when compared to other agricultural waste biomass such as rice husks, palm kernel shells  are also far superior both in terms of calories and bulk density, so palm kernel shells are increasingly becoming a favorite fuel.
 

At present the palm kernel shell has also become an export commodity especially for the Japanese and Korean markets. The two countries are the biggest consumers of the palm kernel shells, especially in Asia but with the main motivation due to the implementation of environmental programs in the country. Large incentives are given by the states to companies, especially power plants, when using biomass fuels, especially palm kernel shells because they are a renewable energy group. This is very encouraging the use of palm kernel shells in the two countries. While the main suppliers of palm kernel shells are from Indonesia and Malaysia as the world's largest CPO producer as well as the owner of the largest palm oil plantation in the world today. This condition will certainly create competition especially when the demand for palm kernel shells is equally large. When these conditions occur, special strategies are needed to react to them, thus providing a large added value for Indonesia and Malaysia, or the pks sources. 

 Palm kernel shells are biomass fuels that have almost no processing and can be used directly, while for wood pellets an industry is needed for processing. Based on the fact above, palm kernel shells should be prioritized for the domestic market and wood pellets for the export market. When the production of wood pellets currently still relies on sawdust and wood wastes which are limited in quantity, then in addition to the the environmental aspects of sustainability recognition are also difficult to be obtained. When wood pellet production is made from energy plantations by growing energy crops such as calliandra and gliricidae, although the availability of raw materials can be guaranteed and capable of large capacities and environmental aspects of sustainability can be obtained, but in general producers are still not interested because the process route is long and need mastering the aspects of energy plantation cultivation. EFB pellet production can be a solution for  this. EFB or palm oil empty fruit bunches like palm kernel shells are an abundant amount of solid palm oil mill waste and are currently largely untapped, for more details, please read here.

If the use of biomass fuels, especially palm kernel shells in Indonesia is getting bigger, it means that it is comparable to efforts to reduce greenhouse gases or CO2 derived from fossil fuels. An achievement in the environmental field that can be proud of course. At present, there are not a few palm oil mills which have not yet sold their palm kernel shells, especially those in remote areas. The effort to take the palm kernel shells at the palm oil mills is also a challenge, but with users in the country it is also easier. If the palm kernel shells for the export market, especially Japan, require a large minimum quantity of an average of 10,000 tons per shipment and the quality of a tight palm kernel shell (especially aspects of cleanliness anddryness), the domestic market in addition to the volume of each shipment is smaller, the quality requirements are also not so tight. The transportation of palm kernel shells to Japan with such quantities requires large bulk vessels, while for the domestic market it is sufficient by barges.

 

Conversion from natural gas to solid fuels especially palm kernel shell biomass does require different equipment and operational aspects. Biomass fuels, especially palm kernel shells, require a larger space for storage, the combustion process is not as easy as gas fuel, and solid ash is also produced. The industrial users of palm kernel shell fuel usually have to replace their furnaces or boilers with furnaces or industrial boilers with biomass fuel, especially palm kernel shells. Basically there are 3 groups of combustion technologies that can be used namely grate, fluidized bed and pulverized combustion. The aspect of mixing air with fuel is an important aspect in the combustion process. Solid fuels have low mixing qualities with air compared to liquid fuels moreover in the gas fuel. In liquid fuels and especially gas, fuels can be atomized so that they are close to the molecular size of air, whereas solid fuels cannot. Grate combustion has the lowest air-fuel mixing rate, fluidized bed has a better homogenisation air-fuel mixture and pulverized combustion has the best homogenisation air-fuel mixture level that can be obtained from combustion of solid fuels. The choice of combustion technology is mainly based on the heat capacity needed and economic aspects including the price of the equipment, operational and maintenance costs.