EFB Pellets with Low Potassium (K) and Chlorine (Cl) for Power Plants

Palm oil mills that have excess energy, especially electrical energy, will have more freedom to develop their business. The excess electrical energy could have come from the production of electricity from the use of biogas. Liquid waste (pome) from palm oil mills is the raw material for biogas production. A palm oil mill with a production capacity of 30 tons of FFB/hour will be able to generate 1 MW of electricity and so on. One of the products that can be processed from the utilization of palm oil solid waste as well as the development of this business by utilizing excess energy is EFB pellets production. With the high price of palm kernel shells or PKS and wood pellets, the driving force or need for EFB pellets is increasing. Global awareness regarding decarbonization or CO2 removal (CDR) or CO2 reduction is the main driving force.

Apart from that, the production of EFB pellets can also be carried out by a separate company by purchasing the raw materials for EFB from palm oil mills. With conditions in Indonesia where there are still very few palm oil mills that have biogas units so that they have electricity supply and can process EFB into EFB pellets, there is still a lot of EFB that has not been utilized and becomes waste that pollutes the environment. This makes EFB pellet producing companies not have to worry about the supply of EFB raw materials. In fact, because the amount or volume of EFB is very large, the EFB pellet plant will be overwhelmed by the abundance of this raw material.

However, due to the high content of EFB in potassium and chlorine (ash chemistry), the use of EFB pellets is limited or can only be used in certain types of power plants, especially stokers and fluidized beds. In fact, most power plants currently use pulverized combustion technology. This is so that the chemical content of ash in EFB must be made as friendly as possible to boilers, especially those with pulverized combustion technology. This can be done so that the chemical content of the ash in the form of potassium (K) and chlorine (Cl) is only less than 2000 ppm. Potassium (K) with a low melting point causes deposits or scale to form in the heat exchanger pipes in the boiler so that the efficiency of heat exchange decreases while chlorine (Cl) is corrosive which shortens the life of the equipment. The treatment was even successful in reducing K and Cl by up to 80% so that the problem of fouling thickness and corrosivity was also reduced by 80%. With the number of palm oil mills in Indonesia reaching around 1000 units, of course the amount of EFB that can be processed into EFB pellets is also very large.

Higher Power Plant Efficiency Demands Higher Fuel Quality

When we want to refuel our vehicle at a gas station, of course we choose what fuel is most suitable for our vehicle. Our vehicles will be able to run optimally when using the appropriate fuel. Over spec fuel quality or too low (under spec) will only provide less optimal performance. Technically, the vehicle has been designed with a certain pressure ratio on the combustion system, if the quality of the fuel is too high then low compression is difficult to burn perfectly, and vice versa. In the operation of vehicles, even fuel that burns prematurely or after time will produce a performance that is not optimal. High-quality fuels also have higher prices so that they are economically also not profitable, as are low quality fuels, although they are cheaper but performance is also below standard.

The analogy above is also more or less the same for electricity generation. The higher the level of efficiency the higher the quality of the fuel required because the operating conditions are also above the average, for example compression, temperature and so on. If the quality of gasoline is expressed by octane numbers, or on diesel oil the quality is stated by cetan numbers, then in solid fuels such as wood pellets the size of quality is expressed as a caloric value. Other elements that are also considered in fuel are elements that can damage the equipments or machines used. Especially for wood pellets, high potassium and chlorine content can have a bad effect on the power plant. Potassium will be a deposit / fouling on boiler pipes thereby reducing its efficiency, while corrosive chlorine will shorten the life of the power plant.

In 2030, Japan will implement the use of power plants with higher efficiency, which is a minimum of 41%, while most of the efficiency of coal power plants currently ranges from 30-35%. To achieve an efficiency level of more than 41% the technology used is ultra supercritical pulverized coal. Ultra supercritical pulverized coal technology is basically a further development of pulverized coal technology that is most widely used by coal power plants or more than 95% in the entire world today. The difference in ultra supercritical pulverized technology with pulverized is the use of higher pressure and temperature so that its efficiency is also higher. Modification of the power plant can also be done to increase the efficiency. The use of biomass fuels such as wood pellets can be done by cofiring or full firing (100% wood pellets). The characteristics of the fuel used will also affect the boiler technology used.

The ash of wood pellet required for industries such as electricity generation can be up to 6% according to the American pellet fuel institute (PFI). But chemical ash is an important consideration in the use of the power plant. South Korea for example currently requires a maximum chlorine level of 500 ppm (500 mg / kg) or Japan requires a maximum potassium level of 1000 ppm (1000 mg / kg). This makes the production of wood pellets follow these specifications if the specifications are not appropriate. A number of special pretreatments need to be done to achieve these specifications. The potential of wood pellets from energy plantations in Indonesia is very large, as are pellet fuels from agricultural or plantation waste such as palm oil empty fruit bunches which are estimated to reach approximately 38 million tons per year. But once again the specifications of the pellets (wood pellets or agro waste pellets) produced need to be adjusted to the needs of power plants in Japan or South Korea - two countries that are highly energy dependent - of course if the pellet producers are export oriented. What are the next pretreatment questions that need to be done on the production of the pellet? InsyaAllah, we discussed on another occasion.