FAST DRY
(original article published in the August 2000 issue of Farming)
An option to drying grain that may fit many operations at much lower capital cost.
“FAST DRY” is used to speed up Natural Air Drying (NAD) in grain bins using heat, allowing the grain to be dried in 7 days or less instead of weeks or months. Tens of millions of bushels have been dried in FAST DRY bins. Hundreds of burners have been successfully used and some have not, we will cover that later.
The beauty of FAST DRY is that bins can be designed for adding burners and/or other accessories later. By placing bins for a future handling system a continuous flow dryer can also be added later. With over 20 years of experience Wall Grain has added four more key items to make FAST DRY 20% - 30% more efficient and effective.
1. ROOF FANS - Greatly reduce the mess on bin walls by installing roof fans. As we get into mid-September and cooler nights, dripping in bins creates a mess on the walls and slows the amount of moisture removed. Wall Grain designed a roof fan that greatly reduces the dripping in the bin. This helps push moisture out of the space under the roof but more importantly keeps the roof at a constant temperature so moisture does not condense on the roof. Very late, cold conditions can still cause some dripping.
2. MULTIPLE FANS - As farms and bins got bigger Wall Grain went to multiple fans. Two 25HP motors now allow you to dry 25,000-35,000 bushels in each bin (cereals or canola). In 5-7 days each bin is done. Four bins = 100,000-140,000 bushels dried.
3. NEW, SELF-ADJUSTING AGNEW GRAIN SPREADER - With bins ranging in size from 36-54 feet in diameter the peak of the grain is quite high and needs to be level for more consistent drying. This can be done by taking a load or two out of the bin, which is a lot of work! Now you have the option to use a self-adjusting Agnew grain spreader that can handle 13-16” augers. This spreader has self-adjusting springs that allow constant feed on the spreading arms/pans (see picture). Having a more “lumpy” spread rather than a peak means less over-dried grain that needs to be blended.
4. TECHNOLOGY & COACHING TO UNDERSTAND FAST DRY - Knowing how much water needs to be removed will help manage your batches. Wall Grain has a FAST DRY calculator for cereals and canola with seven different fan combinations. Our team of Grain Management Advisors can coach customers on what works and when not to overfill the bin. This also involves matching fans for your operation – 1 phase or 3 phase, size of bin, placement of bins. Moisture and temperature cables also help monitor your bins. Using GrainX Command for fan automation and monitoring makes it much easier to know what is happening in the bin. GrainX Command also comes with coaching and weekly reporting at harvest time. With so many units out there we have trained our sales team to service when needed with parts and advice.
Grain drying is not complicated. Simply warm up the grain to a certain temperature and it is dry. The faster we do it the more effective we can be. We use the acronym H.A.T.T. (Heat, Airflow, Time, Timing). This works for all dryers but we will use this specifically for bin drying in this article.
A. HEAT – Let’s look at the amount of moisture removed by various temperatures, humidity and airflow:
40. – 45C is our target, hotter does not speed up drying of the grain and can cause over-drying.
B. 1) AIRFLOW – Fan and burner selection are critical. The more airflow the more pounds of water are removed. With single phase we are limited to airflows as well as by static pressure. Three phase gives us lots of options and, if we need to, find a different site or go with gen set as it will double your capacity. A wider bin (39’ or 45’) will help reduce the static pressure both on single and three phase.
Let’s look at the amount of air most fans move in CFM. We can then determine the number of bushels we can dry per day.
*fan is operating at limit of designed fan curve, static pressure may be too high
**ideally used in bins 45’ or bigger
B. 2) SIZING – It is important to size the right burner with a fan. The sizing formula is:CFM x Temperature Rise (in F) x 1.05 =BTU required
For example: 10 HP @ 1750 rpm fan = 11,000 CFM 60F – 110F outside temp = 50 Temperature Rise
11,000 x 50 x 1.05 = 577,500 BTU
Therefore a 600,000 – 1,000,000 BTU unit is required, natural gas, liquid propane or other heat.
WARNING – if the burner is not big enough it can double the drying time and result in much more over-dried grain.
The 1.05 multiplier is used because combustion of gas creates water that we simply burn off by adding a few BTU to have “dry air” maximum. The most effectively used burner is a downstream burner which fits between the fan and the transition. We can also use upstream burners for adding to existing, installed fans. Modulating burners are standard on bigger units vs thermostats which make for better burner ignition. Cost of burners vary from approximately $4000 - $6000 for single phase, three phase units are slightly more. Spreaders and/or roof fans are extra.
C. TIME – How long will it take to dry my bin? Our ideal target for FAST DRY is 6-7 days removing approximately ½ point per day. This is full-on heat for 24 hours a day no matter what the weather. A popular design is a 36’ bin with 10HP, single phase 1,750 rpm fan in which 18% wheat will take 5-6 days to dry 15,000–18,000 bushes. In colder conditions we add an extra day to allow for the warming up of the grain. A popular design with three phase is a 48’ bin with 25HP, 1,750 rpm which dries 26,000 bushels in 5-6 days or 20,000 – 25,000 bushes of canola in 4 days.
Instead of using the previous tables, Wall Grain has developed a calculator for wheat and canola with the 7 most common fan combinations. Visit our website www.wallgrain.com to find the Grain Management Advisor in your area or call Dave Wall at 204-269-7616 or toll free 844-744-WALL (9255). Dave has 40 years of experience with FAST DRY, stir systems and other forms of in-bin grain drying.
Here is a chart that shows the length of drying time required using different fans (the blue colors indicate single phase). With three phase you can double your capacity. If three phase is not available Wall Grain would advise getting a gen set, finding a different location or using a variable frequency drive (VFD converter). The grain requires one day to warm and a half day or less to cool before moving it out.
WARNING: When drying Canola use smaller batches and move or mix after 4-5 days. Talking to others is critical to drying canola. With cereals you can remove of ½ - ⅔ points per day. If the grain is very wet you can increase drying points removed by putting less grain in the FAST DRY. By using our charts and FAST DRY calculator you can do 20% cereal in 6-7 days by reducing bushels to match what your fan and burners can dry.
D. TIMING & DESIGN – To make FAST DRY more effective combining sooner (August or early September) is much easier to dry than in late September or October when grain temperatures are colder and nighttime temperatures even lower. Using roof fans in September reduces the dripping. Self-adjusting spreaders can again reduce the amount of over-dried grain on the sides and the middle that is still wet. GrainX Command gives you monitoring of temperature and moisture cables so you know what is happening in your bins.
Early harvest pays back big for Harv Aberhart who has six of the 48’ bins with 25HP fans. Quite often he will over dry in some bins so he can blend with other bins to reduce moving grain.
Harv, who farms at Langenburg, SK, has excellent germination tests for his malt barley. He also has dried lots of canola in his 6 FAST DRY bins, some of which have 2 roof fans each. He started a new bin site in 2015 that has three phase, natural gas and is close to hard-top highway. This has allowed him to keep expanding the farm and adding more bins to the site. Harv has been a long time GrainX Management Solutions customer which helps him get great malt barley results every year!
Nykolaishen Farms in Kamsack, SK started with three FAST DRY bins in 2003. A few years ago Nolan Nykolaishen added roof fans to his seven 48’ FAST DRY bins (50,000 bushels) with 25HP, 1750 rpm and he loves the result. There is no longer moisture dripping from the roof so the grain does not stick to the bin walls. Last year Nolan doubled his fans (3,500 rpm) and burners on a row of 48 bins (67,000 bushels). He was able to put in 1,000-1,200 tonnes of 18% wheat and after 5-6 days he had the bottom at 12%. He took the peak off by taking some loads out and put them in other bins. This year he is adding the self-adjusting spreaders that handle his 16” auger with no problem. Nolan is also a GrainX Management Solutions customer, utilizing the coaching to help him get close to his moisture targets.
Designing big bins with two 25HP, 3,500 rpm fans and burners allows for bigger batches of wheat and can even do 25,000-30,000 bushels.
Adding many of these options makes it much easier to do your blending on the farm or with your terminal. At times it is easier to over dry a batch so you can blend with other bins at other locations.
As mentioned at the beginning of this article, hundreds of burners have been successfully used and some have not. Let’s review the have nots:
• Full-floor bins dry grain 6-7 times faster then hopper bin. Most hopper bins only have 40 square feet of screen for drying whereas a 36’ bin has 1,000 square feet. Drying in a hopper bin could turn your grain in to “popcorn” giving you extremely over-dried grain.
• Limited success in hopper bins even with a good air system such as a Rocket. In a hopper the hot air tends to channel (taking the path of least resistance) making for extremely over-dried grain in one area but still totally wet in most areas.
• Not enough bin space to move grain around or have the ability to blend.
• Many have asked about adding stir augers. This will help mix or blend the grain but it does not speed up the drying process that much. The higher maintenance and cost make it more economical to add burners to more bins. Stir augers are limited to approximately 20’ and bins have eave heights of 33’ or higher. The longer stir augers break too much.
• Burners are not sized properly to handle the amount of moisture to be removed.
• When a wet year comes (like 2019) there is not enough drying capacity and bins get overfilled.
• Corn in FAST DRY is too slow, the amount of bushels and 25% corn has so much water to be removed we do not advise it. There comes a time when FAST DRY will not fit your farm. It is then that Wall Grain recommends going to three of the more common continuous-flow dryers they sell.
FAST DRY Check List
Design for future expansion – plan your bin site so it is easier to move grain from FAST DRY bins.
✓ It’s work – dry grain must be moved away from any kind of dryer.
✓ Add – roof fans for the late harvest so no moisture sticks to the walls.
✓ Add – adjustable spreader for more even drying and less work.
✓ Understand how much water must be removed – use the FAST DRY calculator or charts.
Talk to others who have successfully done it for coaching tips.
Now, with these latest tools it is easy to fill the bins to the correct level, turn the fans and burners on and in 5-6 days your batch is done!
A dryer can be $100,000+ for 400-500 BPH. You will also need wet bins and often bucket elevators and/or a blower system. This can easily add up to $200,000-$300,000 once the system is complete. FAST DRY is a cost-effective way to convert bins into grain dryers. As you grow your farm these bins can be used in future grain-drying systems.