An Investigation of a Drum Level Controller Points to a Process Issue.
I got the phone call in October; it was a grey, overcast day. It was from the ‘Family’, a large industrial conglomerate that owned and operated many plants and mills around the world.
I recognized The Voice at the other end of the line… it was a slow-paced, very deliberate, and precise conversation. The Voice explained to me that they were having difficulties controlling the drum level in their boiler. I knew that their plant had a gigantic boiler, producing up to 300 tons of steam per hour. The Voice explained that if the boiler were to trip, it would cost The Family at least $200k an hour in lost production ($600k for a three-hour restart of the boiler) and that wasn’t ‘good for business.’
“We invited new members to The Family recently,” the voice explained. They were the new Strainer Twins. They were replacing the retiring Older Strainer Twins. It was when these New Strainer Twins joined The Family that ‘troubles began soon thereafter.’ The Voice said that The Family was suspicious of these newcomers; “Would you help us investigate them?”
I’ve heard of these New Strainer Twins. They were from a distant branch of The Family. They were professional. Well-dressed. And shiny. Their expertise was to remove the small particulates from the feedwater. I knew that they were ambitious; they were admitted into The Family because unlike the retiring Old Strainers, they could be cleaned while they were working.
The Voice asked me to look into the changes that they have introduced to The Family, maybe they were a bad influence on the business.
I donned my raincoat, lit up a dollar store cigar, and drove my 1959 Peugeot 403 Cabriolet to the plant… it was a two-day drive. Along that drive, I was thinking about the usual suspects… I knew about the Drum Level Controller… she was the matriarch of The Family. She was very much involved in The Family business and she ran her own crew; three level transmitters, a flow meter, and a control valve (they were known as the Flow Control Brothers) working for her. She also had a Specialist measuring the steam flow as well. This Specialist would tell the Drum Level Controller what was happening downstream in real time. This feedforward information was directly transmitted to flow control crew.
I also had some fleeting thoughts about The Family’s older twins; the Pump Twins. They were called EL Primo and EL Segundo. They had been working for The Family since the operation began. They were a tag team, when one was tired or needed some care, the other would step up.
I arrived at the Family’s compound in two days. I parked my car amidst a cloud of blue smoke.
I was greeted by The Family’s security. After reciting the Family’s creed, I gained permission to enter the compound.
The Voice greeted me at the compound gate; I was led to a very tall building, the tallest in the area I was told, and was brought into the ‘Control Room.’
My initial goal was to interview the usual Suspects. The Drum Level Controller and her crew were the first on my list.
The Voice introduced me to The Drum Level Controller, the Matriarch of The Family. She was exactly as I expected…long, dark graying hair, and spoke with a mild French accent. She lit up a Gitane and said, “Listen, I understand why you are here. Me and my crew have been operating good for a long time, but in the last while, we have been having a hard time keeping up. All eyes are on us, and when things don’t go well, they (The Family) bypass us and take direct control. That hurts me and my crew’s pride.”
My initial goal was to interview the usual Suspects. The Drum Level Controller and her crew were the first on my list.
She butted out her half smoked Gitane.
“I know that me and my crew can do the job… maybe we just need a little adjustment or tweaking.”
I began by examining location and installation of the Drum Level transmitters (The Triplets). It looked like a standard surveillance installation.
I then proceeded to examine the Feedwater Flow Transmitter. I already knew his type, he worked well under differential pressure when well-situated. But if located in a bad spot such as near a squawky pipe elbow or too near the heat of the muscle, the Flow Control Valve; he would make a lot of noise; making him difficult to understand.
I climbed a few stairs to look at the Flow Control Valve. As I mentioned, the Flow Control Valve was the muscle of the crew. He always needed to be at his best. He needed to be surgical in his operation and he needed to be quick. He was also very mindful of his workout routine; he couldn’t be too big or too small. Too big and he could over correct and possibly create some gravelly noise.
I concluded that the Flow Meter and the Flow Control Valve were well-situated and sized for the tasks.
I examined The Specialist. The Specialist was the half-sister of the Feedwater Flow Meter. She also measured flow, but she measured steam flow instead of water flow. Just like her half-brother, she worked very well under differential pressure and, just like her half-brother, she needed a quiet place to work, away from screeching piping elbows.
I noticed that she spoke loudly, a little too loud in my opinion. Her relayed information about the steam flow was very important but her mother, the Drum Level Controller could overreact to the ‘loud’ information
I recommended that she turned down the volume knob on her amplifier from 11 to 8.
With The Voice beside me, I calmly asked the matriarch, the Drum Level Controller, if I could make some minor adjustments to herself and some of her crew members. In order for me to make my adjustments, I would have to bypass the matriarch’s control and make small changes to the muscle, the Feedwater Flow Control Valve. I did explain that there was some risk to The Family’s operation, but it was necessary
After some deliberation with the rest of The Family, the matriarch acquiesced.
My bump tests excelled, the business continued, though some side operatives were nervous. I collected the necessary data. I punched in the data into my Lambda calculator and made my tuning adjustments.
I communicated these new changes to the matriarch, her crew and the rest of The Family. They were very pleased with the results from their adjustments.
We collected data on the performance of the Matriarch and her crew for the remainder of the day to ensure that all was well.
The next morning, after reviewing the data, I decided that it was time to return home.
I donned my raincoat, threw my suitcase in my Peugeot, pulled another dollar store cigar out of my breast pocket hoping that my car would start, never mind survive the two-day trip back home.
As I lit up my cigar in the parking lot, The Voice walked up to me. “I know that The Matriarch is operating well now, she is happy… The Family is happy…. but what about the New Strainer twins? What are they up to?”
I knew that the New Strainers were just trying to fit into The Family. But since they were the newcomers, everyone gave them the malocchio, or the ‘evil eye.’
At high steam production rates, EL Segundo was not able to deliver the goods. The discharge pressure was dropping significantly, and the Feedwater valve-flow profile was flattening out.
I drew on my cigar and walked towards my car, releasing a cloud of smoke. I stopped halfway, I slightly twisted towards him, looking downwards and say, “You are right, I haven’t paid much attention to the New Strainer Twins.” I slowly turned around and looked him in the eye, “I don’t think that they are guilty.”
“Do you have surveillance data records when the New Strainer and the pumps were in operation?
The Voice gave me a perplexed look. “The Pump Twins? EL Primo and EL Segundo? They have been with The Family since the beginning.” I mildly chomped on my cigar and looked him in the eye and nodded. The Voice told me he would consult The Family’s Historian and get me that data.
Nothing more was said at that point. I started my car. There was a cloud of blue smoke and I began my (hopefully only) two-day journey back home.
I did make it home in two day. By then, The Voice had already sent me (literally) millions of data points on the operation. This data included surveillance report on not only the Drum Level Controller and her crew, but all the other side operatives including the Feedwater Pressure. It also recorded the time when each strainer (Old and New) and pump (EL Primo and EL Segundo) were in use.
For three days, I sliced, diced, and parsed those surveillance data records using the EnTech Toolkit. There were no discernible changes in The Family’s operation when either set of strainers were in or out of operation. Hence, the New Strainer Twins (as I suspected) were not responsible for the operating problems in The Family’s business.
However, through the clouds of cigar smoke, a pattern emerged within those millions of data records.
I noticed that the Second Feedwater pump, EL Segundo, was getting tired.
In fact, El Segundo was worn out.
At high steam production rates, EL Segundo was not able to deliver the goods. The discharge pressure was dropping significantly, and the Feedwater valve-flow profile was flattening out. This in turn slowed down the Drum Level controller’s ability to respond to steam load demands, it increased the risk of interrupting The Family’s operation.
I sent my analysis to The Voice. My report showed how El Segundo was getting tired and that he should be retired. The Family should, at the moment, rely only on El Primo, and they should look for a replacement for El Segundo.
I spoke with The Voice a few days later, once him and The Family had time to review my findings. They agreed and they were already looking at replacing El Segundo.
The Voice thanked me for my service.
I hung up, thinking about El Primo; after all, he was the same age as El Segundo.
It will only be a matter of time, I thought.
… to be continued
