Scientific report: "The separation of the particles through the trough parts dam dam dam and several empty grain saving function" docx

Grain separation by the concave and remaining grain of a multiple cylinders threshing system Sự tách hạt qua máng đập của bộ phận đập nhiều trống đập và hàm lưu hạt Le Minh Lu and Nguy

Grain separation by the concave and remaining grain of

a multiple cylinders threshing system

Sự tách hạt qua máng đập của bộ phận đập nhiều trống đập và hàm lưu hạt

Le Minh Lu and Nguyen Xuan Thiet

Faculty of Engineering, Hanoi University of Agriculture

TÓM TẮT

Đập và tách hạt là quá trình quan trọng trong việc thu hoạch lúa (lúa nước; lúa mì) và tốn nhiều năng lượng Đã có nhiều nghiên cứu về bộ phận đập nhiều trống đập để cải tiến máy gặt đập liên hợp được giới thiệu trong nhiều năm gần đây Nghiên cứu bộ phận đập hai trống đập kiểu tiếp tuyến với hướng cấp liệu tiếp tuyến đã được thực hiện năm 2007 với mục đích: tăng khả năng tách hạt của bộ phân đập, giảm chi phí năng lượng đập, giảm tác động làm vỡ hạt và rơm vụn Kết quả nghiên cứu cho thấy năng lượng đập đã giảm đi khi cấp liệu tiếp tuyến, vật liệu đập (rơm, hạt ) bị giập nát, gẫy vụn ít hơn do đó tăng khả năng phân tách hạt qua máng đập Sự sắp xếp hai trống đập liên tiếp thuận theo hướng chuyển động của dòng nguyên liệu cũng làm tăng chiều dài của máng đập do đó làm giảm đáng kể lượng hạt còn lưu lại theo rơm ra khỏi máng đập Bài báo này cung cấp một số kết quả nghiên cứu chính về sự tách hạt khỏi máng đập, lượng hạt lưu lại theo rơm sau bộ phận đập và phân tích ảnh hưởng của một số thông số chính như góc cấp liệu và chiều dài máng đập Mô hình toán học

về quá trình tách hạt khỏi bộ phân đập cũng được giới thiệu

Từ khóa: Bộ phận đập nhiều trống đập, máy gặt đập liên hợp, sự tách hạt qua máng đập

SUMMARY

Threshing and separation is one of the most important processes during harvesting of rice and wheat, and consumes a large of engine power A number of studies for improving combine harvester with a multi-drum threshing system have recently been introduced

Study on two-cylinder tangential threshing system with tangentially fed was done in 2007 with purposes: to improve separation capacity, reduce fuel consumption and reduce the amount of broken grain and straw damage The research results showed that energy will be reduced with tangentially fed The threshing material have broken little thereby increasing the separation ability of the threshing unit The arrangement of both cylinders, one behind the other in the direction of the material-flow, are also increase the length of the concave so reduce the remaining grain

This paper presents some main research results of grain separation by the concave, remaining grain and analyze the influence of the main parameters feeding angle and concave length The mathematical model of grain separation in threshing units are presented

Key words: Combine, grain separation, multi-drum threshing system, threshing unit

1 INTRODUCTION

Climbing The task of threshing system is the

removing the grains, i.e extracting the grains from

the infructescence, like ears, panicle or caps, by

striking and rubbing as well as separating the grains

from the straw For further grain separating the

cleaning unit is arranged next to the threshing unit,

which design depends partially on the structure of

the threshing system (Arnold, 1964; Huynh, 1982;

Wacker, 1995) It is necessary to improve the

threshing system to perform efficiently and also for the machine is valid: increasing total throughput; improving of the grain separation; lowering of the grain losses

In this paper, the results of lab tests on two-cylinder tangential threshing system for the grain separation and the remaining grain with different feeding angle, concave clearance and specific throughput are given

A general and plain mathematical description of this process would allow a theoretical prediction of

80

the effect of the parameters variations involved,

comparing it with experimental results and obtaining

some ideas about the desired configuration of the

cylinder-concave set (Beck, 1999; Gieroba, 1992;

Kutzbach, 2000) Through analyzing the results of

lab tests with the help of the software Origin, two

mathematical functions have been found

2 MATERIALS AND METHODS

The basic setup of the test stand is shown in

Fig 1 The lab test was done with winter wheat

2006 The crop material is prepared on a storage

belt 1 and tangentially fed to the rasp bar cylinder

3 and 4 by means of a feeding mechanism1 and 2

The grain and material other than grain (MOG) separated underneath the concave during the test are collected in classes 1… 5 (mk1…mk5) The remaining material that is discharged from the second cylinder is post - processed using classical straw walkers to separate grain mk6 that

is still contained within the MOG (class 6) The feeding angle () is varied in three steps from 50° through 60° to 70° Fig 2 shows the test stand in the lab

The concave clearance at the primary cylinder (DT1) is defined with the dimensions S1, S2, S3 and

S4 The concave clearance can be modified by changing the length of the connections L1 through

L5 of the concave support (Fig 3)

Fig 1 Test stand Fig 2 Test stand in the lab

Fig 3 Layout of primary cylinder and concave

3 RESULTS AND DISCUSSION

For the evaluation of the concave length the

integral of grain separation (SKi) and remaining

grain (RKi) as defined in Eq (1) and Fig 4 was

derived out of the measured grain masses gathered

at the different classes

100 1

1













i

i

j kj j

Kj

Ki

m

m l

A

RKi = (1 - SKi)*100%; *100

j k

kj kj

l m

m A



The tests have shown that very few grains

are separated at the first class (Fig 5) This is typical

behavior of a tangential threshing unit, since kernels have to be removed from ears first At the end of the second class approx 50% of the grain is separated Less than 5.5% grain is kept in the straw after leaving the second cylinder at a specific MOG throughput of 9 kg/(s.m) as seen in Fig 5

Through analysis of experiment with help of statistical software Origin, the function of integral

of grain separation and remaining grain can be fitted by the following equations:

SK1 = (1- a*bl)*100%

RK1 = a*bl*100% (2)

or by SK2 = (1 – A1e-l/t1)*100%

RK2 = A1e-l/t1*100% (3)

a, b, A1, t1 are coefficients, which depend on the structural parameters of threshing unit (thresh gap, specific total throughput, feeding angle) (Tab 1)

Fig 4 Definition of the grain masses in the classes 1 to 3

Fig 5 Integral of grain separation of lab tests

82

Table 1 Coefficients of functions (S K1 , R K1 , S K2 , R K2 ) and the R-squared value

Fig 6 Coefficient a as a function of the total throughput with different concave clearance a)  = 50°; b)  = 60°;

c)  = 70°; d) Average value of the coefficient a as a function of total throughput

170

175

180

185

190

195

200

205

210

specific grain and MOG throughput q

[kg/(s.m)]

20-14-10-8 20-16-12-8 22-18-14-10 sE/sA: DT1(mm)

a)

175 180 185 190 195 200 205 210

Specific grain and MOG throughput

q [kg/(s.m)]

20-14-10-8 20-16-12-8 22-18-14-10

sE/sA: DT1(mm)

b)

180

185

190

195

200

205

210

Specific grain and MOG throughput q

[kg/(s.m)]

Co

effi

cie

nt

a

[%

20-14-10-8 20-16-12-8 22-18-14-10

sE/sA:

DT1(mm )

a = -5,11*(s.m/kg)*q + 228,26 [%]

180 185 190 195 200 205 210

Specific grain and MOG throughput q [kg/(s.m)]

Co effi cie

nt

a [%]

Fig.7 Average value of the coefficient as a function of total throughput: a)-A 1 , b)-t 1

Fig 8 Remaining grain as a function of specific Fig 9 Remaining grain as a function of throughput at different feeding angles at concave throughput at different feeding

clearance sE/sA_DT1_20-14-10-8; DT2_12/8

With the change of the adjusted parameters

and the change of the throughput the coefficient b

hardly changes The coefficient a becomes smaller

with constant feeding angles (50°, 60° and 70°)

with more largely becoming concave clearance,

Fig 6 For the computation suggests computing an

average value from all tests for the individual

throughput The following diagram, Fig 6d) results

for a

The coefficients A1, t1 of the equations hangs

on the test series of (, sE/sA, q) With bigger

throughput the coefficient A1 decreases, while the

coefficient t1 rises In fig 7a) and fig 7b) are

represented the average values of the coefficients

A1 and t1 from all tests for the individual throughput

Fig 8 and Fig 9 show remaining grain that was not separated through the concaves as a function of the specific total throughput at different feeding angles The remaining grain increases as expected with larger concave clearance and at higher throughput

It becomes clear that feeding angle and concave clearance mutually affect each other Different feeding angles have low influence at the smallest concave clearance (Fig 8) However, the

A 1 = -4,9906q + 237,63

190

192

194

196

198

200

202

204

206

208

210

Cpecific grain and MOG throughput q [kg/(s.m)]

Co

effi

cie

nt

A

1

253,18

340

350

360

370

380

390

400

410

Specific grain and MOG throughput q [kg/(s.m)]

Co effi cie

nt t1

84

largest concave clearance causes recognizable

differences in grain separation for the individual

feeding angles (Fig 9) The feeding angle  = 70°

delivers the highest efficiency, which results in the

conclusion that the feeding angle 70° causing

nearly tangential feeding is very advantageous

There is still more than 94% of the grain separated

at the concaves with large concave clearance and a

specific grain and MOG throughput of 9 kg/(s•m)

4 CONCLUSION

The new threshing system consists of two

tangential rasp-bar cylinders, where the 1st rasp-bar

cylinder is tangentially fed from a chain conveyer

Both cylinders are arranged one behind the other in

the direction of the material-flow For this

arrangement the following advantages are proven in

lab tests:

With this threshing system the material is only

tangentially accelerated The crop experiences

smaller forces of the rasp bars compared to

conventional threshing systems Broken grain and

straw damage decreases

The first cylinder accelerates the material flow

for the second cylinder, which causes higher grain

separation in the second cylinder

The dwelling time of the material in the

threshing system and the total separation surface of

concaves increases compared to a conventional

system resulting in an improvement of grain

separation

The integral of grain separation and the

remaining grain function depend at most of the

structural parameters of the rasp-bar cylinders,

concave length, feeding angles, concave clearance

and specific total throughput The integral of grain separation and the remaining grain function can be described with simple functions (2, 3) These functions approach the test results very well Based on the tests we can conclude that such a threshing system contributes to the further increases

in output, however, the concept of presents combines would have to be changed It is an alternative to the hybrid system, since the specific power demand and the straw damage can be reduced

REFERENCES Arnold, R.E and J.R Lake (1964) Experiments with rasp bar threshing drums - Comparison of open and closed concaves - J.Agric.Engng.Res

9 (3): pp 250-251

Beck, F.(1999) Simulation der Trennprozesse im Mähdrescher, Fortschritt- Berichte VDI- Reihe

14, Nr 92, Dissertation Stuttgart Gieroba, J and

K Dreszer (1992) Grain Separation in a Multidrum set for threshing and Separating - Riv.di Ing.Agr XXII (1): pp 45-53

Huynh, V.M.; T Powell, and J.N Siddall (1982) Threshing and Separating Process - A Mathematical Model -Trans of the ASAE 25 (1): pp 65-73

Kutzbach, H.D.(2000) Ansätze zur Simulation der Dresch- und Trennprozesse im Mähdrescher, Tangung Landtechnik 2000, S 17-22

Wacker, P (1995) Untersuchungen zum Dresch- und Trennvorgang von Getreide in einem Axialdreschwerk, Forschungsbericht Argrartechnik der Max- Eyth – Gesellschaft (MEG) Nr 117, Dissertation