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. 

Increasing Energy Efficiency in Palm Oil Mill Operations Using Pyrolysis

Energy utilization in the form of steam production which is then used for electricity production through steam turbines and generators, as well as the use of steam for steamming (sterilizing) fresh fruit bunches (FFB) are the main things in palm oil mill operations. This is because the need for electrical energy to power various mechanical equipment in the mill comes entirely from this electricity production. Electricity and steam for industrial processing are grouped under the utilities that support that industry. Meanwhile, in the sterilization process or the boiling of FFB, steam besides stopping the development of FFA (free fatty acid) and facilitating the threshing will also facilitate the CPO extraction process and processing the kernel (palm kernel). To produce steam and electricity, of course, energy is needed, namely heat. Steam is produced by the boiler in the form of superheated steam to drive steam turbines and generators to produce electricity and then steam from electricity production or low pressure steam is used for steamming (sterilization) of FFB.

The water after being treated so that it becomes BFW (boiler feed water) is then used for the production of steam and electricity. Heat energy to produce steam can be reduced in such a way with the use of a pyrolysis process (which means that it is not ordinary combustion), so that the heat requirement for the boiler furnace is getting smaller. The pyrolysis condenser will produce hot water so that it becomes preheating for the boiler. In pyrolysis a condenser is used to separate bioil and syngas (uncondensable gas). Preheating from the condensation process of the pyrolysis unit will then go to stage 2 preheating in the economizer of the boiler unit. Thus the temperature of the water entering the upper drum on the boiler is high enough, and the heat requirement to become superheated steam will be reduced. The palm oil mill uses a water tube type boiler as is commonly used in large industries and not a fire tube which is in the form of a shell and tube type heat exchanger with the tube submerged in water so that it does not overheat. In a water tube type boiler, it consists of an upper and lower drum (mud drum) which is connected to a pipe. The lower drum and water tube are fully filled with water, while the upper drum is only partially filled. With this arrangement, steam will pass through the mechanical separator on the upper drum, flow to the superheater and exit the boiler. Efficiency is the key word in production, including the use of energy in the production process of CPO or palm oil mills. The rule of thumb is an increase of 10 C in BFW is equivalent to increasing 1% boiler efficiency.

Typical of water tube boiler

Excess energy from the pyrolysis process should be used for fuel or energy sources in the boiler furnace. The use of excess energy from pyrolysis will also produce environmentally friendly flue gas emissions because the combustion of liquid and gaseous fuels will be cleaner than solid fuels. In this way, the palm kernel shell, which has been used for boiler fuel, can no longer be used. All these palm kernel shells or PKS can be sold directly and even exported to Japan and Korea. Of course, be a separate source of additional income. Palm kernel shells or PKS are competitors for wood pellets in the global market because they have many similar properties, but because palm kernel shells come from waste or palm oil mill sideproducts, the price can be cheaper, more information can be read here. The use of slow pyrolysis for biochar production is the best option compared to similar technologies such as fast pyrolysis and gasification, more details can be read here. Palm oil mills or companies will get a lot of benefits from biochar production, for more details can be read here.