Steam Boiler: Fuel of Boiler

Rice husk can be used as fuel for steam boiler. Rice husk is the shielding covers for the rice grain that is taken off and declined in the operation of dehusking of rice grinding. Huge quantities of rice husk are produced in the rice grinds for the duration of the farming period. Rice husk varieties among 20% until 25% of excess weight of dried out rice.

The following below are characteristics of rice husk as boiler fuel:

Rice husk needs much area for storeroom. Rice husk is natural, consequently, to try multi fuel firing in order to maintain off-period.
Along with rice husk's calorific value of 3500 kcal/kg, it is desirable fuel with the exception of seasonal availability.
Rice husk has standard size commonly less than 3 mm, so it does not need specific preparation of fuel.
Rice husk is quite waterless, just comprising moisture between 7% until 9% and uncompressible intended for baling reasons.
It possesses 15% until 20% ash in addition to ash is very abrasive, because it has silica to level of 90%.

Stoker firing can be beneficial and uncomplicated firing process for rice husk. Its small fan electrical power, easy to operates and smooth 1: 4 turndown generate it preferably appropriate for rice husk.

Bubbling fluidized bed combustion can be an option, because rice husk provides beneficial 15% until 20% ash to produce bed substance and it is adequately weighty to remain in bed, in contrast to light substance like bagasse. The bigger fan electrical power is countered by improved efficiency of combustion between 2% until 4%. The designs must state along with abrasion concerns. Based on an erosion point of view, overbed bubbling fluidized bed combustion seems much better compared to underbed.

READ MORE - Rice Husk as Boiler Fuel

Bagasse ash is by-product of sugarcane milling process in sugar factories. Sugarcane is plant that its juice can be processed into sugar. This plant can only grow in tropical regions. Bagasse as byproduct of sugar production has variety of benefits, including: fodder, raw material of fertilizer, raw material of ethyl alcohol, fabric particle board, and raw material of pulp and for fuel of boiler in sugar factory / plant.

In the utilization of bagasse as fuel of boiler in sugar plant process, bagasse is burned to heat water in boiler to produce steam that will be used to drive power plants. From the combustion process will be generated bagasse ash that has gray-black color. If a sugar plant operates 3 boilers need about 51 tons of bagasse per hour, so one day it takes about 1224 tons of bagasse which is used as fuel for these boilers. Assuming bagasse ash has proportion of about 2% of the bagasse, so in one day would be generated about 24.48 tons of bagasse ash in this plant.

Production process that takes place at a sugar plant can be shown simply by the scheme below:

Figure 1: Scheme of Sugarcane Production

From the scheme above, we see that the boilers in that sugar plant are used to drive purifier and evaporator to produce sugar crystals.

From the results of wet chemical analysis it appears that bagasse ash has relatively high silica content, so has prospect to serve as substitute ingredient in mixture of cement concrete. This material is expected to react with calcium hydroxide pozzolanic reaction products of cement hydration to produce calcium silicate hydrate compounds that contribute in increasing the compressive strength of concrete. For comparison, following below are some data of compound composition that has other pozzolanic ingredients.

Table 1: Chemical Composition of Bagasse Ash