Power at Work: How to plan an effective grain drying system
Monday, March 31, 2008
Asking yourself the right questions before you start and taking all the key factors into account will save you costly regrets five years down the road
by RALPH WINFIELD
Whenever you propose to start or build a grain drying system, you will have to answer many questions. If you do not think these questions are valid now, I guarantee that you will think they were valid when you are five years down the road.
Location is very important. Once you place the first bin, you are committed to that location. Please make sure that you make the best possible choices. Here are a few questions to ask yourself:
1. Is there room for expansion? The system will grow.
2. Is there access for off-road maneuvering of large trucks?
3. Can the system be accessed year-round by truck?
4. Is electrical service and natural gas available? Extending three-phase power or a gas line will cost big dollars.
5. Do you really want to tie the system to existing storage facilities - for example, an old concrete silo? Be careful with this one. Upgrading a silo for grain storage may cost you a lot.
6. Are there neighbouring residences, which may generate noise complaints?
7. Does your layout plan include provision for a leg elevator? If not, change it. You will put in a leg elevator eventually.
8. Do you have adequate drainage for a receiving pit? If not, putting the leg elevator base at grade level has disadvantages and associated costs.
Let's consider some of these points in more detail. Your system will grow in size from the one or two bins you are thinking about now. The opportunities will increase to hold more identity preserved (IP) crops. These must be held in separate, usually relatively small bins - 5,000 to 10,000 bu units. This size provides maximum flexibility for opportunities to grow and store IP soybeans, or even seed beans and other niche market crops.
When you commit to even one bin, you will require grain-handling equipment, probably initially a portable auger or belt conveyer. It will be a significant capital purchase. If used for a number of bins and crops, the fixed cost per bushel of handled product will be decreased significantly. Yes, this is the first incentive to increase the size of "the system."
Do make sure you have a location predetermined for these additional bins.
Even if you start small with just one or two bins, you should (must) have wide culverts to permit entry of large trucks. Yes, even grain trains! In most instances, the purchaser will be picking up your stored crop. They will want to get large trucks off the roadway at any time of year they choose when picking up your IP or seed products.
If you do not have adequate, year-round truck access, you will not be able to obtain specialty or niche market contracts. These are the premium price contracts which will help pay for the drying/storage system.
Available services. Some major decisions have to be made before the first bin foundation is poured. If you are planning on drying a large amount of corn, there is an economic advantage in having natural gas available at the site. How far away is the supply and what will be the cost of bringing it to the proposed site?
Another major decision has to do with three-phase electrical power. If you have a four-wire electrical distribution line passing your proposed site, you have a relatively easy choice. If not, extending or converting a single-phase (two-wire) distribution line to the four-wire (three-phase) line will require a capital contribution, unless you are on a planned upgrade route. But, either way, line upgrades or extensions take time, often months or years.
Do not be misled. Three-phase power is not cheaper than single-phase power. This misconception is still held by many people. However, if you are likely to want to run motors larger than 12 horsepower, then three-phase power is the way to go. The motors will be cheaper and so will the longer-term maintenance costs.
If you have selected a 550-volt service, in order to get single-phase power for use at the grain drying unit or other buildings at the site you will have to buy a dry transformer. If this is confusing, please talk to a reputable commercial electrician in your area. He or she will provide the benefits and shortcomings of 208-volt, or possibly 220-volt, three-phase versus the industrial 550-volt three-phase service voltage.
Why a 550-volt service? Sometimes, 208-volt motors are difficult to acquire.
Using existing storage. Those older concrete silos next to the unused dairy or beef complex are often the reason for some people to decide to dry and store grain on the farm. My response is short and clear. Don't do it! If it sounds like I'm screaming, you are hearing me.
Firstly, will that predetermined location be where the drying system should be? Secondly, will you require a relatively high leg elevator in stage one of development? Thirdly, what is the real cost per bushel of storage? In most cases, you will have to hoop the upper half of the silo so that it can be used for grain versus silage.
Then you will need a fully perforated aeration floor and outloading auger. There is also a high probability that you will require a new roof and parging of the bottom third of the silo. Do consider the total retrofit costs against the cost of new steel storage(s). In almost all cases, the small incremental cost will allow you to move the new system to a more desirable location.
Locating new drier/storage facilities. First, look for high ground with good drainage, good road access and no blocking of the view from the kitchen or family room windows. But, just as importantly, do consider the cost of running services to the site.
Along with siting comes the question of bin unloading height. Do spend money to buy gravel to raise all bin foundations high enough so that pits or trenches do not have to be dug for the auger boot! You will only have to break ice or bucket water once from a sump hole before you will say you wish you had raised your bin foundations.
I guarantee that one.
Be careful with air plenum obstructions.
Every storage or drier bin must permit the establishment of a uniform static air pressure under the perforated floor.
It's vital to locate the aeration fan as close as possible (or practical) to 180 degrees from the unloading auger. This will minimize air swirl and static pressure loss in some plenum areas.
Almost as important, insist on a well-designed transition piece between the fan and the bin. The transition should be long enough to flare gradually. Many transitions are short, so the fan sits close to the bin.
It looks great but is a serious fault when aeration/cooling fans exceed two horsepower.
Here is what happens. If the blown air enters the plenum space under the perforated floor at a high speed, it will cause a high velocity pressure and a low static pressure in that bin region - directly in front of the fan.
An analogy: the next time you fly, ask yourself what keeps the plane in the air. It is the airfoil shape of the wings. The air passing over the upper high curve is speeded up, thus reducing the static pressure above the wings. Thus, the now higher air pressure under the wings causes sufficient lift to hold a fully loaded plane in the air.
Now do you know why spoiled corn (grain) often occurs directly in front of the aeration fan?
If the sales representative encourages you to pay extra for higher aeration floor supports which will also reduce the storage capacity of the bin, please pay attention to the rep's comments about air flow.
Also, please make sure that the unloading augers are oriented so that they can be removed if necessary, but more importantly so that they deliver to a common pathway, allowing grain to be taken to the boot of a leg elevator - eventually.
Last but not least. Most system providers will draw a system layout for you in advance. Make sure you have one and, more importantly, make sure you understand "why" things are laid out and oriented the way they are shown.
When you locate the first bin and pour the concrete base, you have now located your entire drier/storage facility. Drive some stakes well in advance of construction. Stakes are much easier and cheaper to move than concrete. BF
Agricultural engineer Ralph Winfield farms at Belmont in Elgin County.