Investigation of maize cobs crushing: Preparation for use as a fuel

Abstract

Maize crop residues have great significance, particularly in developing countries, where the harvest of maize ears and their natural drying is widely applied. After drying and grain threshing, maize cobs are available for energetic use on farmers' yards. Shortcomings for their energetic utilization by combustion, in comparison with wood, are higher contents of potassium, chlorine, and nitrogen, and lower ash softening point. Tests in small wood chip boilers showed that the size of maize cobs should be reduced in order to facilitate better combustion and feeding with commonly used screw conveyors. Desirable length of particles should be 1-1.5 of their diameter. Within the framework of the Eureka project, a low-cost maize cobs crusher was developed and tested. It consists of a drum with six rows of knives, stationary comb-like knives, and a screen situated below the drum. The test resulted with working parameters that enable appropriate size reduction. Analyses of crushed material showed that over 80% of particles were in the range of 3.15-45 mm, less than 1% smaller than 1 mm, and less than 1% larger than 63 mm. This granulation is comparable with size class P45 for wood chips in accordance with standard DIN CEN/TS 14961. Further investigations should focus on improving the combustion facilities, in order to avoid formation of ash slag, and keeping exhaust gas characteristics within values defined by legislation.

Production and Characterization of Hybrid Briquettes from Corncobs and Oil Palm Trunk Bark under a Low Pressure Densification Technique

“…However, some have observed that corncob briquettes have a tendency to absorb water due to high particle porosity [16], and also displayed inadequate durability for handling and transporting after densification using low compaction pressure at room temperature [22,23]. Additionally, corncobs have a low bulk density of 104 kg/m 3 [24], low lignin content (5.6%), low water-soluble carbohydrates (1.1%) and low protein (2.5%) that are largely responsible for forming solid bridge bonds during briquetting and thus, requiring a high compacting pressure and/or an external binder [23].…”

Profitability of corn cob utilization as a fuel in small residential heating appliances

“…Moisture content of corn cobs, after drying and threshing of grains, reaches a value of about 12%, i.e. about 2% lower than that of grain [17]. The ash content rates, in average, 1.4% [15], which is lower than for other agricultural biomass, e.g.…”

“…The dry mass distribution in corn stover rates 50.9% stalk, 21.0% leaf, 15.2% cob and 12.9% husk [19]. Martinov et al [17] stated that the average corn cobs yield, relative to grain, rates 18%, for the same moisture content. Djatkov et al [20,21] concluded that corn cob pellets have better mechanical properties than corn stover pellets.…”

Održivost Korišćenja Oklaska Kukuruza Kao Goriva U Malim Generatorima Toplote

“…Gornja toplotna moć oklaska je od 18,3 MJ kg -1 do 18,8 MJ kg -1 , а sadržaj pepela je niži od ostale poljoprivredne biomase i iznosi 1,36% [8]. Sadržaj vlage oklaska kukuruza, nakon sušenja i krunjenja, dostigne vrednost od 10 do 12% oko 2% niži nego kod zrna [9]. Nasipna gustina oklaska ima vrednost oko 164 kg m -3 [10].…”

“…Ocenjivanje je sprovedeno na osnovu dostupnosti i prihvaćenosti navedene tri forme oklaska. Korišćeni su stavovi i principi prethodnih istraživanja o korišćenju oklaska kukuruza [2,3,9].…”