Like COOL Cats on a HOT Tin Roof
John Robinson of PCS, in Aurora, NC, prides himself on running one of the most efficient sulfuric acid operations in the country, and he enjoys the support of a management that trusts his ability to get the job done.
But when he loses a plant during a high production period, he feels the same pressure to get back on line as quickly as possible that every plant manager in the country feels. So when the catalyst bed became plugged on a plant just a few days after coming back from an extended shutdown, Robinson knew he had to get the plant back in operation in a hurry.
“We called VIP International in to hot screen our fourth pass, and we were back in business in about 48 hours,” Robinson said. VIP International’s high temperature entry procedure may have saved PCS thousands of dollars in lost production.
“Performed under normal conditions, that job might take a week or more, sulfur to sulfur,” said Bubba Miller, VIP operations director, and 13-year veteran of the sulfuric acid maintenance business.
VIP developed its high temperature entry process in response to the demands of an industry where lost production costs have gone through the roof in the past 10 years. No other company provides this service to sulfuric acid plants.
High temperature entry operates on the concept that acid plants can cool their converters to about 550 degrees rather quickly and efficiently, then reheat them to conversion temperature without substantial production losses. VIP high temperature entry technicians, using state-of-the-art protective equipment can enter a converter at this temperature, make repairs, and have the system back in operation in minimal time. In addition, high temperature work reduces the stress cooling and reheating a plant can have.
Under high temperature conditions VIP can:
- skim, screen or rake catalyst beds
- repair damaged or fallen support grates
- repair gas baffles
“The process works on the theory of cooling the man and not the converter,” said Hoss Maddry, VIP vice president. VIP technicians enter the hot converter wearing specially designed heat resistance acid suits that are supplied with cooled breathing air and are equipped with radios that allow them to communicate with technicians outside the converter. Technicians’ vital signs, the temperature of the suits and the temperature of the converter are constantly monitored by a life support system positioned outside. In addition, each suit is fitted with a triple backup breathing system.
Each technician is trained first on how to work in “inert” atmospheres, or oxygen-deficient environments, and then given the skills to work in high temperatures.
“Only our most experienced vessel entry technicians are allowed to do high temp work,” Miller said. “They are brought into it very slowly, in the classroom and in the field. It is dangerous, but we know what we’re doing. And we’re proud of the fact that we’ve never had a safety incident on a high temperature job.”
George Carpenter, superintendent of the IMC-Agrico Uncle Sam plant in Louisiana, said high temperature entry is a valuable service, adding that timing is very important.
Carpenter learned firsthand when the deflector baffle fell into the catalyst bed in the first pass of his converter. The velocity blew the rock and catalyst from around the baffle to expose the grates in a horseshoe shape.
VIP entered the converter under high temperature conditions, hoisted and welded the baffle back into place and leveled the catalyst bed. The converter was still far too hot for normal entry when the work was complete.
Using high temperature technicians, VIP can repair a fallen grate in about four hours, skim a 60,000 liter catalyst bed, and reload it in about 16 hours; or completely remove and replace an entire first bed in less than 48 hours.
“And their converter should never drop below about 300 degrees .” Maddry said.
(Reprinted from Sulfuric Acid Today November 1994 issue.)