Illustration: Paul Lange; Photograph: Rich Fee. |  |
| Steam traps were invented in 1835 and have been widely used ever since. They separate liquid from steam and reduce water hammering and other problems in steam systems. Now, Lauren Kiest, who invented the Equaply NH3 system 10 years ago, has developed a reverse steam trap to take vapor out of anhydrous ammonia (NH3) as it flows from nurse tanks to manifolds on application equipment. You can also think of it as an upside-down steam trap. Vapor is the 800-pound gorilla when it comes to handling NH3. It's virtually impossible to measure and meter a combination of liquid and vapor. Consequently, it's a challenge to apply the desired rate, and some outlets on many applicators apply much more nitrogen (N) than others. |
Kiest says his invention, called the Liquimatic Vapor Separator, eliminates the need for heat exchangers. "The only purpose for the heat exchanger in an anhydrous ammonia system is to condense ammonia vapor back to a liquid," he says.
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| According to Kiest, the stream of NH3 entering the Liquimatic is about 45% gas and 55% liquid, by volume. NH3 is a liquid in nurse tanks, but vapor is formed by friction as it flows through hoses and pipes after leaving the tank. In addition to eliminating most of the vapor, Kiest says the Liquimatic also has more capacity than heat exchangers. For example, he says the two heat exchangers on his company's original Equaply system can supply about 60 gallons per minute, whereas the Liquimatic system can handle rates in excess of 80 gallons. "That's enough capacity for a 60-foot applicator going 12 mph to apply 250 pounds of anhydrous ammonia per acre," he says. (That's just over 200 pounds of N). |
After 5 years of development, Kiest and his company -- aNH3 Company -- are now starting to sell the new devices, which are patented (U.S. 7,096,802).
The Liquimatic is surprisingly simple. A weir, or metal dam, in the canister diverts the incoming mix of liquid and vapor upward. The liquid flows up and over the dam. Meanwhile, the vapor rises to the top of the canister (see illustration above).
When the amount of vapor reaches a certain point, a float inside the canister trips a switch that opens a solenoid valve and allows the vapor to escape. A small tube attached to that valve carries the vapor to a knife or opener. The Liquimatic system actually has two identical solenoid valves. One is basically a backup for the other one. As the vapor or gas is bled off, the liquid rises, turning off the switch and closing the solenoid valve.
The liquid in the canister or tower has a small amount of head pressure. "The head pressure assures that the liquid leaving the bottom of the tower is below saturation pressure and not boiling," Kiest explains. "Therefore, a flowmeter after the tower senses pure liquid and reads correctly. Similarly, a pump after the tower does not have vapor to cause cavitation."
Applicators applying low rates may not need a pump in the system. But Kiest expects that most customers will order a system with a pump and use it at least part of the time.
"If you are running when it is really cold or if you have a really high rate of flow, you are probably going to need a pump," he says.
The pump is a Hypro hydraulic pump with special seals for NH3. Two nurse tanks with big hoses will be needed to apply high rates. The list price for a Liquimatic without a pump or any other component is $7,900.
Prices for a complete system range from about $10,000 to $25,000 depending on the size of the applicator and complexity of the system. The high end of the range is for an applicator with 24 outlets and swath control valves (but not a controller).
When a complete system is purchased, it comes assembled and mounted on a base plate that can be attached to the applicator.
"I expect the Liquimatic to replace the original Equaply system with heat exchangers this fall," says Kiest.
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