The themes of the next few blogs will discuss safety issues with chemical feed, chemical storage, and boiler operation.
I had a customer back in 1992 that wanted to eliminate handling of heavy 55 gallon drums of 66 Baume sulfuric acid. The drums were located outdoors in a heated chemical building near the cooling tower. During the winter months, it became difficult to move palleted drums through the snow to get them close to the chemical building for transfer.
I brought up the idea of a using a 2000 gallon steel bulk storage tank with containment basin to the customer. He liked the idea and immediately issued a PO for one of our storage tanks.
After a visit to one of my refinery customers, I noticed they had desiccant dryers installed on their tanks as well as high quality tank level sight gauges specific for sulfuric acid. When I mentioned these two items to our equipment manager, he told me, ” They are not really necessary and adding they would be more expensive than the tank itself.” I took his advice on the gauge glass but did recommend the desiccant dryer anyway because I knew that moisture in the tank could cause serious tank wall corrosion at the liquid/air interface. In retrospect, I should have recommended a quality liquid level transmitter.
I became concerned when the tank arrived as the sight level gauge was a cheap piece of heavy wall tubing that was not reinforced to handle the weight of the sulfuric acid. When I asked our equipment manager about the tubing, he said, “Don’t worry about it.”
After the initial 2000 gallon fill of sulfuric acid was made, I visited the plant for a routine service call, and noticed the gauge glass tubing was in the shape of an ‘S’ caused by the weight of the acid. I told the customer (who was not very happy) about this and he went out and valved off the level gauge. This of course defeated the purpose of having it installed in the first place. Every two weeks, the level would be manually checked by an operator with a stick (he was not very happy either and let me know it).
Plant personnel finally adjusted to the inconvenience of measuring the tank level until a few months later when I got another call. This time I was told to immediately come to the plant as there had been an acid spill. The operator decided he was not going to climb on top of the acid tank and measure the liquid level because of ice and snow on top of the tank so he opened the gauge valves and ‘Wham’ the tubing blew off dumping almost 1000 gallons of acid into the containment basin.
When I arrived at the plant, the plant engineer wanted to know what to do with the acid in the containment basin. I gave him two options (neither of which he liked). One was to pump the acid out of the basin into another tank, or neutralize the acid with soda ash and have it hauled away or send it to the municipal sewer system. They decided to neutralize the acid and then called the city sewer plant top let them know what their plans.
The story has a happy ending. The plant purchased an ultrasonic level transmitter and tied it into their building management system and they permanently valved off the sight gauge glass connections.
All of this wasted time and effort would have been avoided if I had made the recommendation to install a level transmitter. Experience is the best teacher.