Pressure Curing Rice
Farmers realize lower drying costs, better milling
By Carroll Smith
In 2003, Joe Mencer, who farms near Lake Village, Ark., had an option to buy a farm or build another set of grain bins. He opted to build the bins and in 2004 constructed a completely new CMC Pressure Cure system.
However, this was not Mencer’s first experience with CMC. In 1994, the company converted some of his older bins by installing fans and no-fines floors. At the time, he was told he would see a two to four pounds-per-bushel increase in test weight.
“I did see the increase with wheat and rice and thought it was a better alternative to burning butane, so when it was time to build the new set, I checked into CMC’s Pressure Cure system,” Mencer says.
“The system did cost a bit more than a system with heaters and stiralls, but I thought it would be worth the difference in energy savings and fewer repairs in the long haul.”
The Arkansas farmer ran about 150,000 bushels of rice through the system in September 2004, and his cost per bushel was 4.4 cents for drying, which was 40 cents per bushel less than he had paid the year before. He recalls that some of his moisture levels were as high as 23 percent, but he was able to dry the rice in 20 days without turning the rice or using heat.
“My milling yield ran four pounds better in the Pressure Cure bins, which paid me 20 to 25 cents-per-bushel premiums over the standard bin system,” Mencer says. “The rice that I dried in town with heat was seven pounds lighter in test weight and cost me 41 cents per bushel to do that.
“Today, the drying cost numbers have changed because the cost of electricity has gone up,” he adds. “But, we are still drying rice for eight to nine cents per bushel with the Pressure Cure system.”
As for the increase in milling yields, Mencer says that it has held steady over the years.
“We are still using some older, conventional-type bins that use heat,” he says. “We can always tell when we are shipping out and get to the older bins, the rice has a lighter test weight, and the milling yield drops off.”
The system’s four key components
Kerry Johnson, the Pressure Cure conditioning consultant, says there are four keys to the system’s success.
“First, the high volume, high pressure air pumps that we developed use a backward curved blade, which gives us a lot more volume and pressure per horsepower,” he says. “The second important thing is the no-fines floor specifically designed for this system. However, we don’t necessarily have to replace the floors if we are retrofitting a bin. We’ve made other floors work, but they are not as efficient as ours.”
The third key, Johnson notes, is that once moisture comes out of the grain, it has to get out of the bin.
Therefore, proper placement and the number of roof vents are crucial. Mencer points out that the vents on many other bins are placed down by the wall at the edge of the roof. All of the condensation or moisture that’s trapped in those bins is trapped in the peak of the bin.
“The vents must be staggered from the bottom to about halfway up the roof panel to get the best movement of moisture out of the bin,” Mencer says. “You can put as big a fan as you want to at the bottom to push air in, but if the air can’t get out of the top, you’re building up more static pressure and burning more electricity.”
A fourth component of the Pressure Cure system – temperature cables – is not part of the drying process but does show where the curing zone is and monitors the temperature and the moisture of the stored grain in the bin.
“The temperature cables eliminate the need to go up and down ladders to check the grain,” Johnson says. “You can monitor everything from outside of the bin.”
Heat and stiralls vs. forced, pressurized air drying
“That system was a lot of work,” he says. “After drying the first batch of rice and shipping it out, we changed the floors, installed new blowers and more vents and tried the Pressure Cure system in comparison to the heat and stiralls.
“We actually dried the rice a little faster, although the new system did have two blowers compared to one. Our milling yield was about six points better, so our price was better. Of course, we had less maintenance because there are fewer moving parts. We just preferred the Pressure Cure system.”
After this experience, Durand retrofitted six older bins on his farm and bought two new 48-foot bins with the whole new system from CMC. And, as of today, he is adding two more 48-foot bins.
‘The most challenging place to dry grain’
“Even with all of that,” Durand says, “we just keep the blowers going until the front goes through. Once the rice gets down to 13 percent, then we run the fans only during the day until we finish drying the rice.
“We can, and we have cut rice at 24 and 25 percent moisture and still dried it with this system, so it can be done. It makes us nervous, but we have temperature cables hanging in the bins all of the time, so we can monitor what is going on.
“We’ve never had a problem with the system. I’ve heard millers say that where people use heat, the milling quality is good at the top of the bin, but when they get closer to the bottom, the rice really starts to break up. But with the Pressure Cure system, the milling quality is consistent all the way through.
“In fact, an Energy Audit was done on our farm in November 2007 by EnSave Inc., which was funded by NRCS,” Durand says. “EnSave compared our Pressure Cure system to other drying systems and found ours to be the most energy efficient and had no recommendations for improvement.”
Contact Carroll Smith at (901) 767-4020 or firstname.lastname@example.org.