Functionality analysis for rack system concept

In this example, the analysis begins with round bales in ambient storage in SSLs and ends

with a stream of size-reduced material entering the bioenergy plant for 24/7 operation.

3.4.2. List of baseline constraints

The constraints for this example are:

1. The rack design, and the design of the trailer to haul the rack, must conform to the standards for highway transport.

2. The rack used for this example holds sixteen 5*4 round bales. This round bale has a diameter of 1.52-m (5 ft) and a length of 1.22-m (4 ft). With two racks on a truck, a truckload is 32 this kind of round bales.

3. The bales will be pre-loaded into the racks while the trailer is parked at the SSL. When a truck arrives, a trailer with two empty racks is dropped, and the trailer with two full racks is towed away. The goal for the load time (trailer exchange) is 10 min, or less.

4. Hauling of the trailer and racks will be done 24 hours/day. Truck drivers will work five, 8-hour shifts per week and operations will be continuous for a 6-day work week. The rack loading crew at an SSL will be organized such that each worker will work a 40-h week. SSL operations will load bales into racks six 10-h workdays per week.

5. At the Receiving Facility, the racks are lifted from the trailer and placed on a conveyor to be conveyed into the plant for immediate use, or stacked two high in at-plant storage. The goal at the Receiving Facility is for the forklift to lift two full racks from the trailer and replace them with empty racks within of 10 min, or less.

6. The plant will operate with a maximum of 3 days of at-plant storage.

7. The example assumes that the plant processes one bale per minute. Assuming a bale weighs 900 lbs (0.408 Mg) in average (15% M. C.). The dry mass (DM) per bale is,

0. 408 Mg / bale x (1 — 0.15) = 0.3468 Mg DM / bale

Assuming one bale is processed per minute, the processing rate is,

0.33468 Mg DM / bale x 1 bale / min x 60 min / h = 20.8 Mg DM / h

For comparison, 20.8 Mg DM/h is 500 Mg DM/d. This size is in the 100 to 1000 Mg/d range recommended for Regional Biomass Processing Depots by Eranki et al. [54].

The processing time for racks is:

Подпись: = 3.75 rack/h the plant for a 24/7 operation is, 630 rack / wk = 315 truck loads / wk 60 bale/h 16 bale/rack

Thus, the number of truckloads consumed by 3.75 rack / h x 24 h / d x 7 d/ wk =