PKS For CFB Powerplant

49 MW Japan Biomass Powerplant
Operates Since 2015 That Use PKS As Fuel

The fluidized bed combustion (FBC) technology is not new since it has been used since 1960 to burn city waste and industrial waste. After proven successful, then made more than 300 units worldwide. The advantages of this technology are higher fuel flexibility, high efficiency due to good mixing, relatively low combustion temperature so as to minimize the problem of ash deposits due to melt and the use of small excess air, also increasing the efficiency and reduce the resulting flue gas. FBC technology is suitable for large capacity that is above 20 MW. In the development of this technology is divided into 2, namely bubbling fluidized bed (BFB) and circulating fluidized bed (CFB). In general the difference is not much, such as fuel size, unit construction and air-fuel ratio. PKS (palm kernel shell) or palm shell is more suitable for CFB powerplant because its size is less than 4 cm. The power plants in Japan in particular, which use PKS or palm shells as fuel because they use this CFB technology.

With relatively low operating temperature ie 650-900 C then the ash problem can be minimized. Certain biomass fuels sometimes have high ash levels and ash chemicals that potentially damage these generating units. In addition, the fuel cleanliness factor is also very important, this is because technically certain impurities such as metal can close the air pores on the perforated plate of FBC unit, whereas air, especially oxygen is absolutely necessary in the combustion process and also the making the fuel bed in fluidized condition. The requirements for clean fuel must be met by the provider or seller of the biomass fuel, therefore the purchasers require an acceptable amount of impurities (contaminants), ranging from less than 1%. Cleaning of PKS is done by sifting (screening) either manual or mechanical machine, for more detail biomass fuel cleanliness problem can be read here.

In addition to PKS, pellet fuel from agricultural wastes or agro-waste pellets such as EFB pellets that have a high ash content and low melting point can also be used and not to worry for the fuel with this technology. Agro-waste production can be encouraged if there is a buyer, namely a biomass power plant with CFB technology. Although agricultural wastes are abundant in Indonesia but generally only burned or in pile only, because they are considered as a problem or pollutant. Why are these wastes not processed into pellets? One is because they have not found a market or buyers, although there is basically there's always a market for every type of pellet fuel. While the PKS that can be produced in Indonesia with the current palm oil plantations of 12 million hectares is estimated to reach 10 million tons / year, can be directly used for the power plant CFB. This is why the PKS is more sought after by current buyers.

The weakness of the CFB power plant is the high concentration of the flue gas so that the dust precipitator and the boiler cleaning system must be able to work efficiently. In addition the bed material is also lost with ash, so periodically need to be added again. Bed material commonly used is silica sand and dolomite. To reduce the cost of bed material usually reused after separated with ash. The technique is that the ash mixture is separated from a large size material with fine particles and silica sand in a water classifier. Next the fine material is returned to the bed. More specifically, CFBs are more efficient and less flue gas than BFBs so that boilers and flue gas cleaning systems can be designed to be smaller.

Biomass fuel gets a 4.3% share in Japan on their 2030 energy projections. This means that biomass accounted for 4.3% of 245 million MW per year with renewable energy or about 6,000 MW of biomass. To reduce CO2 emissions from coal Japan also make regulations on the efficiency of the coal power plants, to a minimum of 41% by 2030 while most of the current coal power plant efficiency is around 30-35%. Currently power plants that have an efficiency of more than 41% are only ultra supercritical pulverized coal. Modification of power plants can also be done to improve the efficiency, but certainly require more costs, so that the condition is increasingly becoming the driving force of biomass power generation especially CFB powerplant and the effect of increasing PKS demands.