MY MEMORIES

Charles Glenn Petersen

Bleach Plant (continued)

This was a major accomplishment but we still had occasional chlorine gas leaks. The chlorine gas was injected into the pulp slurry in a relatively smaller mixing tank, a cylinder about 6 ft across and 15 ft tall, with a large impeller inside to mix the gas with the slurry. I got up on top of the tank and observed the motor driving the impeller. It appeared to me to be running backward according the indicator on the belt drive. In the control room there was an amp meter for each motor in the plant. The meter dials were sized so that at normal operation the indicator needle was pointing straight up, so it was easy to spot abnormal operation. Back in the control room I noticed that the amp meter for the chlorine tank impeller was indicating 10 amps where the straight up position was 50 amps. There seemed to me to be an abnormally low load on the impeller motor. Maybe it was running backward and not doing its job. The motor was a 3-phase motor which meant that to change the direction the motor was turning one simply had to reverse two of the 3 wires in the control box that fed the motor. By this time, the operators had worked with me long enough that if I wanted to do something in the plant they went along with it. I got an electrician, located the control box for the impeller motor and asked the operator to temporarily shut off the motor. The electrician quickly reversed two of the wires, the operator restarted the motor, and the amp meter immediately registered 50 amp, it was now in the straight up position. The mixer was now doing its job. The amount of chlorine required was immediately reduced dramatically and the escaping gas problem was over. I felt like a hero but I didn’t get a medal for it. I think management was too embarrassed to admit that they had let this problem go on for ten years without figuring out the solution.

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