The research activities carried out on the lignocellulosic biomasses, in particular those dedicated to

SRF harvesting mechanization, have underscored some operative limits of the maize chopper Class Jaguar 890 mainly due to the chipping device. Data analysis in the tests previously conducted (2, 3)

as well as the research activities on storage of poplar chips, have highlighted two negative aspects:

1) the reduced size of the harvested product, with negative repercussions upon preservation;

2) further improvement of the machine productivity during harvesting.

In order to overcome the limitations described above, Panacea has designed and charged the construction to the company “Biomasse Europe” of a new chipping device to be mounted on Class Jaguar 890 in place of that commercial one. Following to this, some experimental tests harvesting were carried out during R4S2 (Root 4 years and Stalk 2 years) poplar plantation.

The developing of a new prototype needs some experimental phases comprising:

1) experimental tests to evaluate the efficiency of the mechanical modifications;

2) a long testing period necessary to better evaluate the machine’s functional aspects as well as to determine which components can be stressed by an excessive wear and tear;

3) final evaluations of machine performance, including quality of the work and harvesting costs.

The preliminary experiments were conducted in April 2008, in the province of Pordenone; the experiments focused on the “Pegaso” poplar variety at second felling (Fig. 1). Due to the necessity of testing the prototype before growing season, together with the heavy rain at the end of winter 2008, we were forced to select a skeleton plot that although appeared not to be in good condition, allowed the experimental to go on. The unit worked even after rainy periods cutting and chipping of 20 rows, which averaged 241.40 m in length, on a net area of 1,41 ha. Results from the preliminary experiments already indicated good prototype performance, confirming the success of both the prototype and the technical aspects developed. In the subsequent phase, conducted through the collaboration with “Veneta Mais”, the machine harvested about 100 ha of poplar plantation, extending over several provinces in northern Italy (winter 2008-2009). A portion of the chipped product was used in the preparation of one of the six piles, built, through the collaboration of Enervision Company, in Dosolo (Mantova) for the evaluation of different SRF storage methods in relation to energy content preservation, within the scope of the “Bio-energy” project begun in 2006.

For the final evaluations of the machine performance, including quality of the work and harvesting costs, some experiments were conducted in February 2009, in the province of Padova. These experiments were conducted on a planting at second felling (R4S2) with different poplar varieties.

The poplar SRF harvesting chain comprises a maize chopper Class Jaguar 890 of 372 kW equipped with Panacea’s rotor and a GBE-1 header (Fig. 2) for SRF harvesting and four farm tractors towing four carts with tipping body.

Similar to previous experiments conducted on

planting at the second felling, the header was provided with beater structure that separates the rows aimed at separating the epigeal biomass, directing part of the fall of them towards the right inter-rows and the rest to the left inter-rows.

The innovative Panacea’s rotor was designed to increase the dimensions of the harvested chips and to improve harvester performances. Analysis of the wood chips harvested with a traditional rotor showed that the small size of chips resulted from chip-crushing at the knife holder impact rather than only at the knives. The new rotor, with ten fix knives (Figure 4), was made up of a steel drum (diameter= 403 mm, length=670 mm and a holder with the capacity for 10 knives (five for part, equally distributed on the drum mantle) in order to allow the correct positioning of the knife holder for the subsequent welding stage. The knife holder was fixed with an inclination angle of 5° with respect to the straight lines of the rotor; the drum weight was 145 kg. Each knife holder (length=320 mm) was equipe with five slots in order to better fix and adjust the knife position. The knife has a maximum length of 380 mm, with a cutting angle of 32.5° and a series of five threaded holes, allowing the knives to be fixed on the knife holder at the slots’ height. We also modified the insertion angle to fit the knife holder on the cylinder/roll.

The planting comprised different poplar varieties. March 2005 marked the fourth year of growing, with only one harvest two years before. The rectangular-shaped and level field, took up a gross area of 1.60 ha. The carried out surveys emphasized an effective distance between the rows and on the row of 3 m and 0.53 m, respectively, for an investment of 6295 plants/ha.

The aim of the work was to evaluate the performance of the machine equipped with the innovative CRA-ING rotor. To this purpose, the standard harvesting times were worked out. The times mentioned above were categorized as a effective time (80.66%) and accessory time (19.34%). Rest times and maintenance times were not reported. The accessory times allotted time for turns (14,92%), due, in part, to the waiting time prior to trailer-towing tractor’s completion of the turn, and for dead times (4,42%) due to alternation among tractors loaded with chip and those without any loaded. The machine worked at a speed of 1.46 m/s (5,25 km/h) and so doing attained an operative capacity of 1.51 ha/h.

The harvested product was 76 t/ha, and the operative productivity was 120,29 t/h.

The comparative size tests analyzed 40 surveyed chip samples (20 samples from the commercial rotor and 20 from CRA-ING rotor), each of them of the weight of 10 kg, on first (R2S2) or second-cut (R4S4) plantings. According to the tets results, the chip size distribution, derived from CRA-ING rotor, into granulometric classes vary, if we compare the two rotor production (see table below).

In the 12,5 – 25 mm class, one of the classes (including large chip size), was found to increase the first- and the second-cut values by +13, 82% and +12, 14%, respectively. In contrast, in the three 6.3 – 12 mm, 3,15 – 6,3 mm and < 3,5 m classes, we observed reduced values of -17,72%, -4,55 % and -5,20% for R2S2 and -4,10%, -2,87 % and -4,14 % for R4F2 (see table below).

Results from the previous year’s storage experiments (5), for which these data resulted very important, indicated that a pile was composed of a low percentage (<12,5 mm) of thin chips and by a greater percentage (12.5 – 25 mm) of granulometric fragments. This pattern guarantees good pile air circulation, improving moisture content and the control on fermentative phenomena.

We did not observe remarkable differences in the values of volume mass unit values from the chip derived from the two rotors chip at the same felling: 297 and 302 kg/m3 for CRA-ING rotor and Class rotor on R2S2 respectively; 274 and 281 kg/m3 for Panacea rotor and Class rotor on R2S2 respectively.

In the harvesting proof, the maize chopper, equipped with Panacea rotor, increased both working capacity and the hourly operative production, corresponding to the reduction of harvesting costs.

The chipping device works at a speed of 1100 rpm. The new rotor, with 10 knives instead of 12 knives, makes about 1100 fewer cuts each minute, guaranteeing less consumption, less power input (15%) and greater speed for the advancing machine in the harvest phase, as well as a better chip size.

The planting which the Class Jaguar 890 worked on presented a similar productivity, 79 t/ha for current rotor and 76 t/ha for Panacea rotor. The comparison of the two tests results show a 33% increase of the effective speed of the machine during the harvest phase. In all, the machine equipped with Panacea rotor shows a 22% increase of the working capacity and the hourly operative production, with a reduction of the harvesting costs of 19%.

From the comparison of the experimental proof, we estimate the increase in Panacea rotor working capacity to be 22% and the favorable impact on harvesting costs (-19%). The greater operative capacity is given by a high advancing speed of the machine equipped with an experimental rotor, during harvesting.

With regard to the size of the wood chips , the 12,5 – 25 mm class (one of the classes including large chip size) exhibited significant increases. In contrast, the < 12,5 mm class exhibited reduced values.

At the moment specified activities aimed at the evaluation of the separating of the woody year increments into different species and into the same specie or variety in relation to the chipping system, is under developed in order to suggest further modifications on the rotor prototype, particular attention is on the knives inclination degree.