Madras Agric. J. 91 (1-3) : 140-141 January-March 2004 Research Notes
Intensive evaluation of power operated groundnut decorticator V. THIRUPATHI, R. VISWANATHAN AND K. THANGAVEL Dept. of Agrl. Processing, AEC & RI, Tamil Nadu Agrl. University, Coimbatore-641 003, Tamil Nadu Groundnut decorticators are used for removing kernels from groundnut pods. Groundnut decorticators are classified as manually operated and power operated shellers. Based on the shelling action they can be divided into reciprocating type or rotary type. A hand operated groundnut decorticator of 50-75 kg hr-1 capacity was evaluated and found that shelling efficiency was 95-99 per cent (Mandivikar, 1988). A pedal operated groundnut decorticator was found to have a capacity of 72 kg hr-1 and kernel germination of 94.2 per cent (Dash et al. 1994). A rotary type was tested and reported that a maximum efficiency of 80 per cent at a cylinder speed of 300 rpm and 14mm clearance (Bhagawan Singh et al. 1985). A maximum damage due to mechanical action was 15.5 per cent (Patil et al. 1988). The germination of seed was found to be 95.95 per cent by manual shelling and 94.1 per cent by mechanical shelling (Anandachar et al. 1990). An intensive evaluation was conducted in power operated groundnut decorticator for CO 2 and ALR 2 varieties of groundnut. A reciprocating type groundnut decorticator has been developed in Tamil Nadu Agricultural University, Coimbatore. The machine consists of a hopper, double crank lever mechanism, oscillating unit and a blower assembly, all fitted to a frame. In the oscillating unit a number of cast iron pegs are fitted. The groundnut pods are shelled between the oscillating unit and a perforated concave sieve. A blower blows the husk away and clean kernels are collected at the bottom. The clearance between the oscillating unit and concave is adjustable. The shelling efficiency of the unit depends on the speed of the oscillating unit, clearance between the oscillating unit and the concave sieve and perforation
size of the sieve. In the groundnut decorticator, the oscillating unit has number of cast iron pegs and the groundnut pods are shelled between the oscillating unit and a perforated concave sieve. The speed of oscillation, feed rate and clearance between the pods and the pegs play the major role on the performance of the unit. For different varieties, these parameters vary and hence need to be evaluated and the variables such as clearance, stroke length, and feed rate etc. has to be optimized. CO 2 and ALR 2 were the two varieties selected for conducting experiments. The independent variables used were speed (200, 250, 300, 350, 400 and 450 strokes/min-1) and clearance between concave and oscillating sector (14, 16, 18 and 20 mm). The dependent variables viz. shelling efficiency and percentage of brokens were calculated as Wt. of kernels – Wt. of unshelled kernels Shelling = --------------------------------------- x 100 efficiency % Wt. of kernels Wt. of broken kernels Percentage = ------------------------------------ x 100 of brokens Total weight of kernels The shelling efficiency and percentage of brokens for CO 2 and ALR 2 varieties are presented in Table 1. For CO 2 variety the shelling efficiency varied between 80.2 and 96.7 per cent and the percentage of brokens varied between 5.2 and 17.3 per cent. It is observed that increase in speed for the same clearance increases the shelling efficiency, however the percentage of brokens was increased. Similarly for particular speed of oscillating sector the
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Intensive evaluation of power operated groundnut decorticator
Table 1. Shelling performance of the groundnut decorticator at different speeds and clearances Variety CO 2 No. of strokes min-1
Variety ALR 2
Clearance (mm)
Shelling efficiency (%)
Broken (%)
Shelling efficiency (%)
Broken (%)
200
14 16 18 20
92.8 90.7 85.4 80.2
16.9 13.5 10.4 9.5
94.8 92.5 90.5 85.5
17.3 15.4 12.5 10.5
250
14 16 18 20
93.2 91.5 86.7 82.3
15.0 12.0 11.5 8.0
95.8 93.2 91.5 83.2
10.3 8.5 7.2 6.0
300
14 16 18 20
94.1 92.5 88.6 87.5
19.8 16.5 14.3 12.5
98.1 94.5 92.5 90.8
9.8 8.0 6.5 5.2
350
14 16 18 20
96.7 93.6 90.8 86.4
6.7 6.5 5.0 4.5
94.6 92.4 90.6 88.5
11.1 9.8 7.5 6.2
400
14 16 18 20
93.5 91.8 87.5 84.3
12.6 10.5 8.3 8.0
92.9 90.5 96.5 83.2
12.0 10.5 8.5 6.0
450
14 16 18 20
92.8 89.5 85.4 81.6
20.8 16.5 11.2 9.5
84.8 80.5 75.8 72.0
13.3 12.2 10.5 8.5
increase in clearance decreased the percentage of brokens, however the shelling efficiency was also decreased. The maximum shelling efficiency of 96.7 per cent for CO 2 variety with a brokens of 6.7 per cent is achieved at 350 strokes min-1 and 14 mm clearance. Similarly the maximum shelling efficiency of 98.1 per cent for ALR 2 variety with a brokens of 9.8 per cent was achieved at 300 strokes min-1 and 14 mm clearance. References Anandachar, M., Mathew, M. and Adwani, M.R. (1990). Effect of decortication method on groundnut seed quality. Seed Res. 18: 144-147.
Bhagawan Singh, Varshney, B.P., Nasim Ahamed and Tiwari, J.P. (1985). Development and testing of a groundnut decorticator. J. Agri. Engg. ISAE, 25: 15-20. Dash, A.K., Das, D.K. and Das, S.K. (1994). Development and performance evaluation of a pedal operated groundnut decorticator. AMA, 25: 61-65. Mandivikar, S.S. (1988). A new groundnut decorticator. Indian Fmg. 38: 33. Patil, R.B., Bharud, R.W. and Pokharkar, S.M. (1988). Mechanical shelling and damage in groundnut. Seed Res. 16: 112-113.
(Received: August 2003; Revised: December 2003)
