Ground Cover Supplement : GC Supplement - Grain Storage 2005
11 is at odds with the objective of cooling grain to preserve grain quality (see page 18). APPrOxiMATE sysTEM COsTs in a 70 to 100-tonne silo, it typically costs about $750 (diy plus gsT) to install ducting and a fan to deliver 2L/s/t for aeration cooling. Two to three fans and ducts may be needed for reliable storage of higher-moisture grain. retro-fitting aeration to older leaky storages that are not suited to using phos- phine is an ideal option. it is low-cost and reduces insect management problems in older storages. While it is possible to retro-fit high flow-rate aeration-drying fans and ducts to existing silos, consider- able design issues are involved and should only be undertaken with the input of an aeration-storage designer. The cost for new purpose-built high flow-rate aeration-drying silos varies. one nsW-based manufacturer indicated that sealable drying silos up to 200-tonne capacity fitted with high flow-rate fans cost 25 per cent to 35 per cent more than standard, sealed, upright storage. To fit a supplemental heater to raise air temperature four to 10ºC costs around $1000 for a gas-powered unit that can potentially service two 200-tonne silos. however with supplemental heating fit- ted, some silo designs may have to be run at half capacity (ie 100 tonnes each) to maximise air-flow rates and minimise the extra condensation that can occur. A diesel unit would cost closer to $1500. running costs of a gas-powered supple- mentary heater (if needed) are estimated at around $2 per tonne. diesel heaters are likely to be closer to $3/t for fuel. An automatic aeration-cooling control- ler with a four-storage control panel costs around $2600 plus gsT (not installed). Labour, plus the cost of additional hard- ware, cabinet, overloads, contractors and time delays, must also be budgeted. Aeration-drying controllers are also avail- able, but vary in their function and cost. A new type of controller capable of con- trolling both drying and cooling has just been commercialised. it is based on the Adaptive discount Control (AdC) method developed by Csiro (see page 17). Typical electricity costs to run cooling fans of 2L/s/t using a time-proportioning cooling controller set to run one-seventh of the time are around $0.05/tonne/month. The electricity costs to dry grain vary widely – but commercial feedback shows that many drying jobs use between $2 and $5 per tonne. it may also be necessary to upgrade the supply transformer and install soft starts or time delays to keeps amps within allow- able limits. grDC research Code DaQ00028 For more information: peter Botta (Vic), 03 5761 1647; peter Fulwood (sa), 08 8568 6422; Chris newman (Wa), 08 9366 2309; John Cameron (nsW), 02 9482 4930 philip Burrill (Qld) 07 4660 3620 Ground covEr GrAin storAGE grain in storage is a valuable commodity. Tasks and key aeration system features task type of system key system features cool dry grain for extended storage Aeration cooling flow-rates of ~1-2l/s/t. Good ventilation. Easy and inexpensive to retro-fit to old elevated upright storage. low cost to install on new sealable storages. store moist grain (ie 13-~15% for cereals) for weeks/several months Aeration cooling flow-rates of ~2-6l/s/t. flow-rates at the higher end of the range and suitable ducts are needed if grain moistures are near the high end of the moisture range. Good ventilation is needed. shallow bed depths may be needed if moistures are near the higher end of the range. Easy and inexpensive to retro-fit to old elevated upright storage. low cost to install on new sealable storages. dry wet grain (ie 13-20% for cereals) Purpose-built high flow-rate aeration drying system flow rates of ~10-30+l/s/t. shallow bed depth with even flow fields of air in the whole grain stack are needed. Air of low relative humidity or supplemental heating is needed to dry grain. heating raises the temperature of inlet air by 4-10ºc and greatly improves the drying potential of air. Good ventilation is needed. more complex to retro-fit than for cooling. wet grain is always at risk and good management is essential. dry wet grain in coastal or humid regions (not tropics) Purpose-built high flow-rate aeration drying system with a supplemental heater As above, but flow-rate should not be less than 20l/s/t and system should be fitted with a supplemental heater to raise air temperature. this increases the ability to gently dry grain when the relative humidity of ambient air is too high for natural air-drying. more complex to retro-fit than for cooling. seek advice to ensure that the system is in balance with the expected air quality in your region.
GC Supplement - Precision Agriculture 2005
GC Supplement - Soil Biology 2005