A Comparative Performance of Peg-tooth and Rasp-bar Threshing Unit for Rice

Transcription

1 A Comparative Performance of Peg-tooth and Rasp-bar Threshing Unit for Rice * Abdullah SESSİZ, Resat ESGİCİ Dicle University, Faculty of Agriculture, Dept. of Agricultural Machinery 21280, Diyarbakir,TURKEY asessiz@dicle.edu.tr Abstract The aim of this study was designed and developed a prototype threshing machine for rice. To determine the grain losses and power consumption, two threshing units; peg-tooth and rasp-bar, were designed and constructed. The threshing units were driven by 5 kw electrical motor through by belt pulley system. The local rice variety, Karacadağ, was used for this experiment. Five different drum peripheral speeds (6.44 m/s, 8.08 m/s, m/s, m/s and m/s), three different feeding rate (500 kg/h, 750 kg/h and 1000 kg/h) and two moisture levels were used for comparative performance and determine the appropriate working parameters in trials. Depending on these parameters, unthreshed grain, broken grain, damaged grain, skinned grain and energy consumption were investigated. The results indicated that the power requirement increased with increase drum peripheral speed for each two drum and feed rates and moisture contents. The highest of power requirement was measured at 1000 kg/h and m/s as kw. The lowest power requirement was obtained at feeding rate of 500 kg/h, drum peripheral speed of 6.44 m/s in both threshing unit. Also, the results revealed that the grain losses such as broken, damaged and cracked grain were not found during the experiment for each two threshing units. Therefore, the grain losses were not valuated. Key words: Rice threshing; thresher; drum speed; threshing loss, INTRODUCTION Rice (Oryza sativa L.) is one of the most important staple food crop for about half of the world population and at least cultivated in more than 100 countries in the world. Rice is mainly grown in most Asian countries (91%). Turkey is also one of the rice grower countries. Although rice cultivation area of Turkey fluctuates from year to year, it was cultivated over an area of hectares with average rice yield of 6910 kg per hectare and an annual production of tons in In the Southeastern Anatolia According to official statistical data of 2008 year, the average yield of the region was 3940 kg per hectare, which was much less than other rice growing regions of Turkey, it covers an area of hectares (4.66 %) with an annual production of tons (2.66 %). In this region, 95 % of rice cultivation area and production was performed in Sanliurfa, Diyarbakir and Mardin provinces (especially, Karacadag region). Agriculture is one of the most important economic sectors for the South Eastern Anatolia region of Turkey and the economy depends on agriculture. A large proportion of the population is involved in agriculture. However, this number has declined in the last five to ten years because of the rapid expansion in the other sectors (Sessiz at al., 2011). Rice growing is performed in stony areas in this region. Therefore usage of agricultural mechanization equipment is limited. As a consequence, labor has been drawn from the agricultural sector to others, resulting in labor shortages during the peak farming seasons. This causes delay in rice harvesting and threshing and thus increases both quantitative and qualitative losses (Khan and Salim 2005). Undoubtedly, agricultural machinery plays an important role in the current agricultural systems of the region. However, rice harvesting is performed by human. Manual harvesting of rice with sickles in the traditional way is a time-consuming and laborintensive job. In an unfavorable climate with less labor, losses may be unavoidable. After harvesting, the reaped plant left on the field to reduce crop moisture content, and then bundled together and transformed to outside of the field for threshing 259

2 operations. Rice threshing is done either by cereals thresher or by stationary combine harvesters in Southeastern region of Turkey. In this systems, labor intensiveness, low grain quality and widespread use of simple farm tools which results in low productivity and high losses occurred of during threshing. So, the threshing unit plays a key role in determining the tooth open threshing drum was constructed using 48 pegs arranged in four rows on surface of the threshing drum. The pegs were 50 mm in height and were cut from a 19 mm by 19 mm mild steel square. They fixed on a drum with the help of weld in a helical arrangement. The distance between each tooth was 60 mm. The diameter and length of threshing drum were 280 and 920 mm, respectively. A rasp bar, open threshing drum had four equidistant stationary bars built on the speed of the drum in a parallel orientation (Sudajan et al., 2002). The concave was made of steel plate and welded four rows mild steel rods with spacing of 240 mm. The concave clearance between the threshing drum and concave was fixed at 22 mm. The length of concave of threshing unit was 0.96 m. Threshing drum is powered by 5 kw electrical motor. The power from the motor was transmitted to threshing drum by pulleys and V-shaped belts (Fig.1). The five drum speeds of 410, 515, 665, 760 and performance of a thresher (Sudajan, 2002).Threshing performance and grain losses are affected by design factors, operating parameters and crop condition. Considering this factor, In this study, in order to find a solution to the problem and to increase rice production and reduce of threshing losses, two different threshing units ( peg-tooth and rasp-bar type) were designed and manufactured and their performances were compared. MATERIALS and METHODS This study was carried out at the Department of Agricultural Machinery, University of Dicle, Diyarbakir province, Turkey. For rice trails, two threshing drums, a peg tooth type with an open threshing drum and a rasp bar type with an open threshing drum, were 915 rpm, equivalent to peripheral velocities of 6.44 ms-1, 8.08 ms-1, ms-1, ms-1 and ms-1, respectively, were examined. The drum speed was measured with digital tachometer (Lutron DT-2236). Three feed rates, 500, 750 and 1000 kg h-1, were used for testing. During the experiment, at each test run, materials was weighted by electronic balance and loaded onto the tray and fed into the threshing unit at constant rate by hand. designed and constructed (Fig.1). The threshing unit consisted mainly of a commercially available main frame, tray, threshing drum, concave and power drive unit. The rice threshing units operates on the principle of tangential flow movement of the material. The peg Fig. 1. A view of threshing units 260

3 A local rice variety common cultivated in southeastern part of Turkey, namely Karacadag, was used for the tests. The rice stalk was harvested by sickle about 15 cm above the ground or the stalk length is about cm ease of bundling and threshing. After harvesting, the bundles were placed in the stack and covered with tarpaulin for weather protection. During the experiment seed and stalk moisture contents were measured. The moisture content of the grains and stalks were determined by standard oven drying method at 105 C for 24 hours (ASAE S352.2FEB03, 2003). The average ratio of seed to straw was 1.50 on wet basis (w.b.). The average moisture contents of seeds and stalk were found to be (65.87) % (w.b.) and (38.42)% (w.b.). The torque transducer was used to measure the torque in this experiment. The power requirement was calculated by using the torque and drum speed data (Sudajan et al., 2002; Sessiz et al., 2004; Vejasit and Salokhe, 2004). After threshing tests, the samples collected from plastic bags were cleaned by a ventilator for determine of grain losses (Gummert et al., 1992; Sudajan et al., 2002). The samples of cleaned grains, in order to determine the percentage of grain losses (broken, skinned and cracked), at each test runs, three samples of 50 g were randomly selected for visual determination of the grain damage (Sessiz and Ulger, 2004; Chimchana et al., 2008; Alizadeh and Bagheri, 2009; Alizadeh and Khodabakhshipour, 2010; Peksen et al., 2013). The percentage of the total grain losses were calculated using skin grain, broken grain, unthreshed panicles (Gummert et al., 1992; Sessiz, and Ulger, 2004). All experiments were conducted at the same time to avoid changes in the moisture content of the material used in the experiments. The performance of the developed threshing unit was analyzed against different threshing drums, threshing speeds, moisture contents and feed rates by using a randomized complete block design (RCBD) of 2 x 2x 3 x 5 (two drum type, two moisture content, three feed rate and five levels of drum speed ) factorial experiment with three replications in each treatment. All statistical tests were done using JAMP software and mean values were compared by Tukey test and comparison between treatment means by the least significant difference (LSD) at the 5% (Sudajan et al., 2002; Vejasit and Salokhe, 2004; Alizadeh and Khodabakhshipour, 2010). RESULTS and DISCUSSION Effect of moisture content, type of threshing drum, drum speed and feed rate on Threshing losses The threshing losses are not affected directly by different operating parameters such as feed rate, type of threshing drum, threshing drum peripheral speed and seed moisture content. Unbroken and cracked grains were not found in the samples collected from outlet of the threshing units for all selected independent parameters. However, small amount skinned grain losses was observed at m/s drum speed. This value was found to be less than %. Therefore, the grain losses were not evaluated for all independent parameters. This may be due to that local rice variety of karacadağ strength against impact force. In addition to selected parameters and adjustment may be suitable for rice threshing. Because, the threshing unit losses were not only caused by the difference in threshing feature, but also by threshing unit adjustments and operation conditions (Chuan-udom and Chinsuwan; 2012). Besides operation and adjustments, the feature or design of the threshing unit was also an important factor leading to losses from the threshing unit. A similar results was observed by Alizadeh and Khodabakhshipour ( 2010) for threshing paddy and also this findings are in agreement with Sessiz et al. (2011) for rice threshing. Effect of operating parameters on energy requirements Statistical analysis of the data showed that the moisture content, drum speed and feed rate significantly affected the power requirement and specific energy consumption at the 1% level of significance. The effect of drum speed was the most significant on power requirement, followed by feed rate and moisture content. Also, interaction of the drum type, feed rate, drum peripheral speed and moisture content had not on power requirement and SPC. According our findings, both open type of threshing unit can be used for rice threshing. The effect of drum type on energy requirement and SPC are shown in Table 1. The results indicated 261

4 that there is no significant differences between pegtooth and rasp-bar type drum in to terms of energy requirement. However, both power requirement and SPC values was found higher at peg-tooth than raspbar drum type (Table 1). Similar results were observed by Peksen et al. (2013). Peksen et al. (2013) studied the effects of threshing drum on power requirement and specific power consumption. The results showed that there were no significant differences drum type among drums and energy consumption for different chickpea variety. Table 1. The effect of drum type on energy requirement and SPC Power Type of Drum requirement requirement (kw) (kwh/t) Rasp-bar Peg-tooth Mean LSD n.s n.s The effect of moisture content on energy requirement and SPC are shown in Table 2. As is seen in Table, power requirement and SPC decreased with increases moisture content. This decrease may be due to the straw at lower moisture content can be easily threshing and required energy value lower than the higher moisture content of straw has lower strength against impact. Table 2.The effect of moisture content on energy requirement and SPC Moisture Content Power requirement requirement (% w.b) (kw) (kwh/t) a* a b b Mean LSD values * Means followed by the same letter in each column are not significantly different by Tukey multiple range test at the 5% level The relationship between energy consumption and the feed rate are shown in Table 3. The results indicated that the power consumption rapidly increased with an increase in feed rate. The power requirement increase with increase feed rate, while specific power consumption decrease with feed rate increase. In another word the power requirement was linearly with increase feed rate and inversely proportional to the feed rate. Increasing energy required by increasing feed rate is attributed to the excessive plants in the threshing chamber which represent more loads on the drum, resulting in more consumption energy (Afify et al., 2009). Increasing feed rate from 500 to 1000 kg/h the energy increased from kw to kw while, SPC decrease from 1.705kWh/ton to kwh/ton. The increase in feed rate required greater compression of the material as it passed between the threshing drum and concave causing an increase in power requirement (Sudajan et al., 2002). Table 3.The effect of feed rate on energy requirement and SPC Power requirement Feed rate (kg/h) (requirement (kw) kwh/t) b* a b b a c Mean LSD values * Means followed by the same letter in each column are not significantly different by Tukey multiple range test at the 5% level The effect of drum peripheral speed on power requirement and SPC are shown in fig 2. It was observed that the power requirement and SPC linear increased with an increase in drum peripheral speed. These increases were observed at all feeding rates of material, drum type and moisture contents. The highest power requirement and SPC were obtained at peripheral drum speed of ms -1 as kw and kwh/t, respectively. The lowest value of power requirement and SPC were obtained at peripheral drum speed of 6.44 ms -1 as kw and kwh/t respectively. The power consumption and SPC at ms -1 was about 5.6 times greater than at 6.44 ms -1 drum peripheral speed (Fig. 2). This increase in the percentage of energy required by increasing drum speed is attributed to the high stripping and impacting forces applied during threshing operation, that tend to consume power and increase energy required. The power requirement of 262

5 drum increased with drum speed because of the increased feed rate which accounted for the extra energy required for threshing the material (Sessiz, 1998; Sudajan et al., 2002) (a) (b) Fig 2. Effect of drum peripheral speed on power requirement (a), and specific power consumption(b), CONCLUSIONS The lowest specific energy requirement of kwh/ton was obtained at feed rate of 500 kg/h, drum speed of 6.44 m/s and seed moisture content of %. While, the maximum energy requirement of kwh/ton was seen at feed rate of 1000 kg/h, drum speed of m/s and grain moisture content of %. Also, at low feeding rate and low drum speed, the movement of the stalk in during experiment was found not continuous, with the stalk often moving at low peripheral speed and high level of moisture content. It was observed that the blockage was occurred in the machine with low speed. Therefore, it is not applicable to work with low speed. ACKNOWLEDGMENTS The authors would like to thank DUBAP (Project No:10-ZF-167 ) for providing found for conducted this research. REFERENCES Afify M. K. M. M. A. El-Sharabasy., M. M. A. Ali Development of A Local Threshing Machine Suits For Threshing Black Seed (Nigella Sativa). Misr J. Ag. Eng., 24(4): Alizadeh, M.R and I. Bagheri Field Performance Evaluation of Different Rice Threshing Methods. International Journal of Natural and Engineering Sciences. 3 (3): Alizadeh, M.R and M. Khodabakhshipour Effect of Threshıng Drum Speed and Crop Moısture Content On The Paddy Graın Damage In Axıal-Flow Thresher Cercetări Agronomice in Moldova,Vol. XLIII, No. 4 (144) Anonyomous org ASAE S352.2FEB03 Chimchana, D., V. M. Salokhe and P. Soni Development of an Unequal Speed Co-axial Split-Rotor Thresher for Rice. Agricultural Engineering International: the CIGR Ejournal. Manuscript PM Vol. X. October, Chuan-Udom,S., W. Chinsuwan Effects Of Threshing Unit Feature On Threshing Unit Losses For Thai Axial Flow Rice Combine Harvesters.Agricultural Mechanization in Asia, Africa, And Latin America 2012 Vol.43 No.4 Gummert, M., H.D. Kutzbach., W. Mühlbauer, P.Wacker. and G.R. Quik Performance Evaluation of an IRRI Axial Flow Paddy Thresher. Agricultural Mechanization in Asia, Africa and Latin America. Vol.23(3): Khan, a.s., and M. Salim Rice harvesting and threshing. PAK J FOOD SCI 2005, 15(1-2): Pekşen, P., T.Koyuncu, C.Artık, A. Sessiz and Y. Pınar Seed Viability and Yield of Chickpea (Cicer arietinum) Cultivars Threshed by Different Types of Beaters and Concaves. International Journal of Agriculture & Biology. Sessiz, A. and P. Ulger Determination of Threshing Losses with Rasp-bar Type an Axial Flow Threshing Unit. Indian Journal of Agricultural Engineering. 40(4), 1 8, New Delhi, India. Sessiz, A., T. Koyuncu and Y. Pınar Effects of different concave, drum speed and feeding rate on soybean threshing. Bulgarian Journal of Agricultural Science. Vol (10), , Bulgarian. Sessiz,A., R. Esgci, E. Güzel, M.T.Özcan Performance Evaluation of Axial-Flow and Tangential Flow Threshing Units For Rice. 11 th International Congress on Mechanization and Energy in Agriculture , September, Tekirdağ, Turkey. Sudajan, S., V.M. Salokhe and K. Triratanasirichai Effect of type of drum, drum speed and feeding rate on sunflower threshing. Biosystem engineering. 83(4), Vejasit, A., and V. Salokhe Studies on Machine-Crop Parameters of an Axial Flow Thresher for Threshing Soybean. Agriculture Engineering International: The GIGR Journal of Scientific Research and Development. Manuscript PM