DESIGN, REALIZATION AND FIRST TESTS OF A PROTOTYPE OF MOWER-CONDITIONER TO HARVEST FIBRE SORGHUM THROUGH HAYMAKINGAssirelli A., Pari L. Consiglio per la Ricerca e la Sperimentazione in Agricoltura Unità di Ricerca per l’Ingegneria Agraria – CRA-ING Via della Pascolare 16, Monterotondo (RM) - ITALIA ABSTRACT: The baling of dried fibre sorghum introduces some specific problems due mostly to stalk development, height and rigidity and to the volume of green biomass to process. To improve storage and to reduce transport cost, the main aspect to consider is the achievement of a satisfactory natural drying of the plant on the ground. Previous tests with mowers and mower-conditioners pointed out operational problems: the mowers, in relation to height and rigidity of the stalks, showed low working capacity, while the mower-conditioners, both with rolls or spokes, were not able to obtain a conditioning level good enough to achieve sufficient natural drying. The structure of the plant, particularly of its stalk, is such that without a continuous cleavage along the whole length, water content decreases slowlier than it would be suitable for harvesting period in Italy. Following these considerations, CRA-ING developed a back mounted harvester prototype, connected to the rear three-point linkage of a reversible drive tractor. Such equipment permits the cutting and conditioning of the whole plant, leaving it spread on the ground, without forming windrows, so to make full use of the solar radiation for drying. When the water contents drops to the optimum value for storing, the product can be collected in windrow and then baled with existing round balers or big balers. The adopted conditioning system is formed by six couples of longitudinal rolls, similar to those used in corn harvesting, because also the fibre sorghum is a row cultivation; each roll is provided with alternate blades and pads to press and cleave all along the stalk while pulling down the plant. Rolls dimensions and rotational speed are such to hit the stalk every 5 cm. Under the rolls, next to the ground, a saw cuts the plants. During the first year tests in Central Italy, the idea was confirmed successful: it was possible, working at 5 km/h speed, corresponding to 1,5 ha/h effective working capacity, to windrow and to bale the cut product after a drying time of only four days. The water content, in this period, decreased from 70% to about 25%. Furthermore, the tests showed that the prototype allows relevant money and time savings in the fibre sorghum chain. Keywords: fibre sorghum, harvesting, energy crops, haymaking, mower-conditioner. 1 INTRODUCTION Fibre sorghum is one of the most interesting species for the production of lignocellulosic biomass. This annual cultivation lets the involved farmer convert part of his company into an energetic cultivation production and draws him closer to the new sector without having to use his own areas and without having to make considerable investments in a plant for 10 – 12 years, which on the contrary it is a must for long-term cultivations. The research projects that have inquired about the potentiality of this species (Prisca and Tisen) have revealed a productivity of 20-25 t/ha d.m. in lands with an average fertility, with peaks up to 35 t/ha d.m. in fertile and well-irrigated lands. It also adapts well to the droughty conditions of south of Italy, thanks to the anatomical structure of the stalk and to the remarkable presence of waxes on the leafs that help the plant overcome drought periods, halting its growth and then resuming after the first rain. For all these reasons along with the common cane, fibre sorghum is the herbaceous energetic cultivation offered in the basins that convey to thermal power stations, in addition to the poplar on the north and eucalyptus on the south of Italy. The only problem that has not yet allowed the spreading, is the lack of efficient harvesting systems. In fact, fibre sorghum has a humidity of 75 – 80% when is harvested, this must be decreased to over 50% in order to help preserve the product for the whole year. According to experiments carried out on previous years, a good storability of bales can already be reached with a humidity of 30%. 148 WORLDBIOENERGY 08 Harvesting fibre sorghum for combustion requires transportation logistic demands from the production areas to the combustion areas, therefore the most drying obtainable on the field is an important aspect, also for the profitability of the cultivation itself. To this day, machines derived from haymaking or from mower conditioners, hay rakes and balers have been used for this purpose. Various Research Institutes [1], [2] have carried out harvesting tests with machines for the haymaking, considering the issues on the harvesting as listed hereafter. All the tested mower conditioners showed difficulty when sending the product to the other conditioning units and were subjected to floodings. Moreover, the conditioning was not always satisfactory as it extended the times required for the field drying process. That is to say that the spongy pith with humidity near 90% must be put to contact with air in order to dry naturally. This can occur only if the conditioning does the complete longitudinal splitting of the plant, which rarely occurs when using the conditioner’s rollers; these are designed to act on the forage, represented by plants with completely different morphological characteristics. The product that is mowed and conditioned must therefore be left on the field to allow for it to dry, which in Central Italy was an average period of five days in August and eight days in September. 2 APPLIED METHODOLOGY Without conditioning, the outer layer of fibre sorghum stems also enables the loss of just a few humidity Moreover. The power device that feeds the conditioning units is also separate for each row and transfers the plant from the cutting to the conditioner's rollers. with minimum shifting of 0. there is a system that adjusts the cutting height from the ground and is used to reduce risks of ground contracts that can pollute the product. the slope of the ground. Table I: Main characteristics of the developed prototype conditioning devices (n) working width (m) row spacing (m) transportation width (m) length (m) height (m) mass (kg) 6 2.I.) 3A R1. etc).O.27 1. whose main dimensional features are shown on table I.14 2. the company made what was planned along with the CRA-ING’s researchers. The cutting device with width of 2. they are screwed on a blade holder with specific bolts.R.8 m. The operation is ensured by a slider-crank system with mass balance and a main chain drive with interchangeable crowns that can vary the working system to meet with the work demands that are mostly influenced by characteristics of the cultivation (height.A.810 The machine is made up of single conditioner equipments that operate on each row. they can be moved along the frame when required so that to operate on the systems that are put in order between 0. Each conditioning device is made up of a set of counter-rotating rollers placed lengthwise compared to the direction of the drive and fitted with blades and spacer bars (Figure 1) that can be adjusted by the radial direction on the rollers to determine the level of forcefulness on the plant and hence the conditioning level. transmission elements. The construction of the prototype was entrusted to a Company that constructs agricultural machines. bearing. the prototype was tested in various areas with cultivations of different morphological characteristics that had an influence on the operativeness of the machine (height.05 m.I. therefore an intensive conditioning is an important aspect in order to reach a humidity content such that to enable harvesting and storability in acceptable times. The head was designed with the a 3D CAD software (thinkdesign think3) with specifications supported by calculations. (*) Data taken with the machine positioned on the ground and with adjustable supports in central position.percentage points per exposure day on the periods of maximum efficiency of solar radiation (months of JulyAugust). an innovative prototype. a cutting device. Then. shear diameter. etc. CRA-ING (The Council for Agricultural Research and Experimentation – Research Unit for Agriculture Engineering) has therefore designed and made. and according to the quality of the job carried out considered as the conditioning grade of the product.75 m in width. protection. within the Bioenergy MiPAAF Project. Figure 1: Counter-rotating rollers with blades and spacer bars. The entire cutting device is fixed onto a mobile connection system on the frame. was taken to the back of a tractor that was equipped with a reversible guide. development). lodging.G. The prototype is made up of a main frame. This process looked after the planning of single components in the perspective of meeting with current regulations on the safety of moving parts. the performance of the prototype was evaluated by measuring the collection times according to the official methods of the Commission Internationale de l’Organisation Scientifique du Travail en Agriculture (C.T. hence it conditions by compressing and splitting from the base to the apex when the plant is still in vertical position. it cuts the cultivation at the base and then conditions each single stem. The tests were aimed at identifying possible functioning defects so that to identify the respective technical solutions to resolve the problems. according to the recommendation of the Associazione Italiana di Genio Rurale (A.). is made up of an alternated blade cutting system that operates at a speed of 600 rpm with blades that are especially made for difficult conditions (cleaning channels and lea). just after being cut-off at the base. a power equipment and one conditioning equipment.S. WORLD BIOENERGY 08 149 .45 and 0. which adjusts the height and depth and helps adapt the cutting to the various cultivation characteristics. the balancing and the breaking of cutting parts.7 0.45 3. Experiments carried out on the previous years have therefore determine the need to individualize a mechanical system that is different from those adopted on the mower conditioner machines that are currently been used and that can provide the require conditioning of fibre sorghum. Therefore. is made up of a set of toothed chains that operate mechanically from the main drive.58 (*) 1. The motion is provided by the tractor’s PTO and the transmission motion is solely mechanical. 2.1 Description of the technological innovation developed The machine. 1 The morphological and production characteristics of the tested cultivations The fibre sorghum cultivations that were tested were in good phytosanitary condition and did not have any infesting grasses. the operating lifetime coincides with the consumption time from the time required to turn in headland (TAV) and from the ripening time due to flooding of the power equipment (TAC) as the site did not have supply times (TAS).2 Working times Table III lists the times taken during the course of the harvesting tests on the site.m.) 4 1. Figure 2: Working prototype during the Apiro test 3. while the diameters at 20 cm from the ground were between 20 and 39 mm. Further information is shown on table II. the stem is split and crushed.3 6. while it is been split with the blades every 70 mm and crushed with the bars in intermediate position.10 Apiro (MC) 3 1. As there was no dead times. alternatively with an approximately distance of 35 mm between each treated area. the more uneven configuration of the allotment of Apiro (MC) and the inter-row of seeding less suitable for the use of the machine with reduction on the working speed to ensure enough power of the mower conditioner shall be emphasized. with a speed of 800 rpm in order to shift the plant to the ground. Marani. The measurements concerning the height and diameter of the stalks. independently from company's characteristics. Table II: Morphologic and productive characteristics Bertinoro (FC) total area (ha) test area (ha) disposition mowing date. plant cutting./h.6 100.1 and 5. Province of Ravenna at the Experimental Agricultural Company M.65 and 4. which were representative of the allotment. The testing surfaces were always less than the total as various operative courses were often tested. in Pievequinta (FC) and Bertinoro (FC). in Apiro (MC) (Figure 2) and at last back in Emilia Romagna. then in Marche. resulting in significant increase of ground losses due to uncut product.0 64.19 km/h). respectively for the testing fields of Bertinoro (FC) and Apiro (MC). drying process in an oven and the weighing.55 11. On this first layout. different among the two allotments is worth considering.) obtained product (t/ha d. the prototype did not enable a good cutting height control.72 m/s (6. The first experiments were carried out in Emilia Romagna.34 150 WORLDBIOENERGY 08 . on the testing grounds of Apiro. the hourly operative production was respectively 13. setup times on the site or standby times during the measurements. it was decided to increase the cutting height to values.6 6. As the harvested production was 11. As the testing objective was to measure the performance of the site. hay baling date cut height (mm) stalk diameter at 20 cm (mm) height (mm) row spacing (mm) nominal production (t/ha d. such that to eliminate this type of unexpected occurrence.7 24.3 100. including the harvest of fresh produce by cutting the cultivation directly using self-propelled forage harvesters.00 5. The average height and the diameter of the plant stems were between 2.2 and 3. Operating at an effective speed of 1.72 Apiro (MC) 69. expressed on average.1 hill 24/09/07 05/10/07 280 26 270 180 8. the disposition and the presence of stones made it necessary to raise the cutting height even 3. more. as it is directly responsible for the increase of non-harvest productions.5 ha/h on the experiment in the Forli region.The rollers are counter-rotating. Overall.4 17.7 m. The cutting height.m. so after several ground contacts mostly due to a pitching phenomena of the tractor. divided by testing area. The operative efficiency was a little higher than 74% in the plain of Forli and it came down to 70% on the hills of the Marches. Theoretical productions were obtained by harvesting directly on the field.m.87 t d.92 t/ha d.. Table III: Working times and operative capacities Bertinoro (FC) effective time (%) turning accessory time (%) maintenance accessory time (%) accessory time (%) operative time (%) operative capacity (%) effective speed (m/s) 74.5 1.1 1. were measured directly on the field during the harvesting.92 3 RESULTS Mowing and conditioning tests were carried out in three distributional areas that were potentially involved with the cultivation positioned in two regions.m. the machine reached an effective working capacity higher than 1.0 73.0 30. on the testing areas of known surfaces.8 flat 11/09/07 17/09/07 180 32 310 450 13.0 23. only the consumption times were taken. 17 13. Table IV: Working devices operative parameters tractor PTO (rpm) mower (cut/min) feeding chains gear (rpm) feeding chain speed (m/s) conditioning rollers (rpm) stalk conditioning speed (m/s) conditioning blades spacing (mm) conditioning bars spacing (mm) 540 1268 310 1. has in any case.65 0. Checking the cutting height constitutes a very important aspect as it is directly linked with the quantitative and quality aspects of the job carried out.62 867 46. especially with reference to the testing field of Apiro (MC). hence increasing the values obtained over three times on the two testing allotments. and when they are calculated together with the different driving power of the tractor used.6 15. confirmed the expectations about the validity WORLD BIOENERGY 08 151 . Table V: Fuel consumption analysis Bertinoro (FC) tractor engine power (kW) harvested area (ha) fuel consumption (l) fuel consumption per hour (l/h) fuel consumption per hectar (l/ha) fuel consumption per tonne (l/t) John Deere 7700 125 1. thus helping obtaining interesting results.67 1. the night humidity and the poor effectiveness of daytime solar radiaThe various working conditions. The initial adjustments of the prototype summarized on table IV. have revealed the need for further experiments in order to enable a better integration between the cutting system and the conditioning system.00 3.95 Apiro (MC) Fendt Favorit 924 169 1.61 3.87 3. but also due to various tractors.99 19.86 1. The experiment carried out in the Province of Ravenna in the month of October 2007. turning over the windrow with a rotary swather on the third day or after six days without turning over (Bertinoro FC). Moreover. the prototype for the mowing conditioning of fibre sorghum by CRA-ING.4 Fuel consumption With regard to the fuel consumption. we need to specify that we were not always able of use the same machine on the tests carried out. On the first surveys taken in the middle of September 2007 in Pievequinta (FC). the latter has quickly revealed the need to adjust the aggressive level on the stems based on the cultivation growth and on the consistency of the stems. 4 .0 12. due to immediate and extended rain phenomena from the night after the mowing.80 19.operative speed (m/s) effective work capacity (ha/h) operative work capacity (ha/h) operative hourly productivity (t/h) 1. risking the elevation of the content in ashes. characterized by the disposition and configuration of the allotment and the condition of the cultivation. which is an important factor for the following combustion. resulting in unavoidable losses of produce that could be harvested. even if no favourable meteorological conditions were verified for the following drying process. hence making the harvest more difficult with the baling machine and without getting ground pollution.3 Work quality analysis The first experiments carried out in the summer of 2007 have confirmed the validity of the conditioning principle that was made. in order to prevent the aggressive levels in any condition to be such that it would cut the stems. under favourable weather conditions. the probability of ground pollution actually increases. thus resulting conditioned more or less aggressive every 35 mm along the whole stem (Figure 3). the operator’s optical monitoring in many cases was not enough to prevent ground contacts of the cutting device or heights that were too elevated. tion did no longer enabled for the significant reduction of the water content. they caused a significant difference (for the energetic factors) on fuel consumption by the quantity of produce harvested.95 10.74 4.00 2. The treated plants show repeated splittings every 70 cm caused by the blades and had intermediate compressions at the same distance caused by the conditioning bars.08 1. therefore the data obtained and summary on table V cannot be exclusively attributed to the different power absorption due to the cultivation. the cultivation was harvested only four days after mowing. have set out very different working times. once they were cut down on the following surveys.26 1.46 0.50 0.10 21.CONCLUSIONS On the first experimentation year (2007).31 Figure 3: conditioned stalk If from one side turning over the windrow helps accelerate the drying process even further. shown a further harvesting trial in late autumn conditions revealing how the greater drying level occurred only with erect plants before mowing. 5 ha/h. the cutting device confirmed a high efficiency and accuracy on the various work conditions tested. On the contrary. It was found that there was a need for further development. Energy crops harvesting: Fibre sorghum. providing good results on the reachable conditioning level as well as on the obtainable work capacity. The first experiments revealed some specificity on the cultivation that suggest for further experimentations in order to improve the functionality and integration between the cutting device and that of the conditioning. Figure 4: CRA-ING model scheme BIBLIOGRAPHY [1] Assirelli A. Important relations among the cultivation growth and the humidity content at harvest and the behaviour and effectiveness of the proposed conditioning system were found on the experiments carried out. Based on the obtained results of the experimentation of 2007. L’importanza della raccolta per le colture da biomassa. the CRA-ING of Monterotondo (RM) has designed a model with a greater operative capacity in order to meet with the demands of constructors and operators of the sector. even with stems that had basal diameters of near 40 mm. Cynara Cardunculus. Vannucci D. the model is presented in a schematic form on Figure 4. Mischantus. Firenze 5 . especially with regard to the control of the cutting height and the aggressive level of the conditioning unit. Arundo donax. – Zucchelli M.– Bentini M. with peaks higher than 1..of the conditioning principle. The work capacities found have always exceeded one hectare. 117-123 [2] Pari L.9 October 1992 152 WORLDBIOENERGY 08 . "7th European Conference on Biomass for Energy and Environmental. L’Informatore Agrario (2006) 41. Agriculture and Industry". kenaf.
Report "Design, Realization and First Tests of a Prototype of Mower-conditioner to Harvest"