Lengthy-time POWER readers could keep in mind Marmaduke Surfaceblow, a fictional character whose engineering escapades have been brilliantly portrayed in lots of of tales printed inside POWER journal’s pages over greater than 30 years starting in 1948. Right now, the fictional collection continues by way of Marmy’s granddaughter, Marnie, who’s an engineering wiz in her personal proper.
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Not everybody needs to be an skilled. Having a purpose to do the suitable factor, listening to your workforce, and in search of skilled assist usually ends in an skilled answer.
Wayne Fritz, the supervisor of a struggling ammonia manufacturing plant in North Dakota, summed up the challenge objectives: “We’re the most important ammonia manufacturing plant within the area, with no actual competitors, however our unreliability is dropping us clients—a 3rd of them within the final 5 years. We need to know if we will fairly enhance our plant reliability sufficient to stabilize our enterprise. I’ve some handouts of our market analyses and lifecycle aggressive prices.”
A stack of shiny printouts was handed across the convention room desk. Marnie Surfaceblow, vice chairman of Surfaceblow & Associates Worldwide, handed her copy unread to her lead discipline engineer, Maya Sharma. Considerably extra within the firm’s said route, Maya quickly flipped by way of the pages. After reaching the top, she requested, “Excuse me, Mr. Fritz? There are line objects of ‘O&M Price’ and ‘Unavailability Price,’ however no particulars. The place may these be discovered?”
“Ron Sorrel, our upkeep supervisor, generates studies every month,” replied Wayne. “What specifics are you needing?”
“Small issues, actually,” answered Marnie in Maya’s stead. “Precisely what points restrict plant reliability? When did they begin? Are they enhancing, worsening, or staying the identical? These kinds of issues.”
Caught flat-footed, Wayne nonetheless gave an sincere reply. “My workforce leads right here might want to reply most of your questions. I’m not an engineer, scientist, or mechanic. I’m an financial strategist. Science was at all times boring to me, however I respect and respect it, and people who are specialists at it.”
Marnie shook her head with some disbelief. “I perceive attempting to do your greatest once you’re in over your head—typically—however this facility produces half 1,000,000 tons per 12 months of a chemical so poisonous that simply 0.03% in air is lethal. Whenever you’re working with one thing that harmful, plant reliability and operations tackle a complete new stage of significance,” she stated. “Situation 1: you’ve been the boss for 3 years. Previous to your taking cost, this plant averaged 68 unplanned outage days per 12 months. Because you took cost, the annual compelled outage price elevated to 88 days. You’ve additionally filed a Hazardous Substance Launch Report each quarter. Within the three years prior, not a single report was filed.”
Wayne nodded soberly and began to answer, however was interrupted by Sheila Bell, the location well being and security lead (Determine 1). “With all due respect, Ms. Surfaceblow, you aren’t contemplating another components. In those self same three years our misplaced hours price from accidents decreased by 78%, and our extreme damage price was 0. And I do know you didn’t have entry to this information, however many compelled outages have been issued by Wayne over security issues,” she famous.
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1. Sheila was fast to defend Wayne’s security file. Supply: POWER |
Wayne began to talk once more, however was interrupted by Hector Jimenez, the plant lead engineer. “Women, you say our upkeep prices are very excessive. That is appropriate, as a result of Mr. Fritz elevated our upkeep funds every year for higher security coaching, protecting tools, leak monitoring, and preventive upkeep,” he added.
Wayne nodded and tried once more to talk, however one other of his employees, operations chief Claude Blackbird, piped up. “What you girls don’t see in your studies is earlier than Mr. Fritz got here right here, we had extra ammonia leaks than now. The previous supervisor by no means filed the studies,” he recounted.
Wayne nodded his head, opened his mouth, and Sheila snuck again in. “Proper, Claude! And Mr. Fritz requires us to report each leak, even ones under the authorized threshold, so we will keep on our toes. In case you look rigorously, a lot of the leaks by no means reached the OSHA eight-hour publicity restrict of fifty ppm,” she identified.
Giving up hope of getting a phrase in edgewise, Wayne silently appeared expectantly at Marnie and Maya. Whereas Maya furiously typed notes on her pill, Marnie was specializing in buffing a tough spot on a fingernail whereas carrying a sly smile. Upon noting the silence, Marnie appeared up and stated, “Oh, we already knew all of that. Maya is a researcher nonpareil and gave me a complete pre-trip report.”
Leaning ahead and focusing her peridot-green eyes on Wayne, Marnie continued, “I needed to substantiate Maya’s analysis by listening to and watching the interplay between you and your employees. And what your workforce stated, and the way they stated it, means this can be a challenge we need to enable you with. Now, that bit about science being boring—you and I’ll talk about that later,” she stated with a smile that would have been humorous or devious. “Because you employed us to return on-site to get a high-level view of your reliability challenges, we’d higher exit, and stroll and speak, regardless of it being so chilly the bushes are chopping themselves into firewood.”
Failing to Perceive Failures
After watching a one-hour ammonia security video and getting ready for the frigid circumstances, Marnie and Maya joined a coterie of senior plant employees to start their tour. Trudging by way of snow towards the beginning of the ammonia course of plant, Wayne commented, “I hope you girls are heat sufficient. Even I’m feeling this climate. The nighttime low may get to –40F. Hey, Ms. Sharma, you employ the metric system in India proper? What’s –40F in Celsius?”
Forcing her tooth to cease chattering, Maya replied, “It’s the identical temperature, –40C, sir.”
“Huh,” Wayne replied. “Then, why do they name it two completely different names? Why not simply Fahrenheit?”
Marnie was about to say one thing she believed could be very humorous and intelligent, when Maya cleared her throat in a means that expressed, “Ma’am, don’t take the bait.”
After arriving on the major reformer, Claude started the state of affairs narrative. “The plant was inbuilt 1979 and makes use of steam methane reforming feeding a Haber course of to make ammonia. A small scrubber simply upstream removes sulfur and different contaminant, sending cleaned gasoline to the first reformer right here. This module mixes steam with the cleaned pure gasoline, passing them each down catalyst tubes inside a containment shell. Pure gasoline burners add warmth to assist the method, firing down in parallel move to the gasoline contained in the tubing. The burner exhaust gasoline goes to the first reformer stack, and gasoline exiting the catalyst tubes is now referred to as syngas, comprised of about 50% hydrogen by quantity, together with water, carbon monoxide (CO), and carbon dioxide (CO 2).”
“Excuse me,” Maya interjected. “The info you despatched signifies the first reformer has been in service thrice its design lifespan. But, your reliability was fairly good till the final two years, when tools failures elevated markedly.”
Claude nodded. “We see the identical tendencies, however we’re undecided precisely why it’s worse,” he admitted.
Upkeep supervisor Ron Sorrel chimed in. “When tube failures began rising, we thought perhaps burner flames have been impinging on the tubes. We spent weeks tuning the burners, then changed about half of them that had dodgy efficiency, however the failure charges stayed excessive,” he reported.
“Are there any indicators {that a} failure is imminent?” requested Maya.
“In line with our thermocouple probes, scorching spots type in concentrated areas on the tubes,” Claude replied. “The reformer is designed for steady-state operation, and even when it was newer, scorching zones would typically type when one thing was out of steadiness, though we didn’t at all times have a failure in consequence. As soon as we see the recent spot type, a failure will happen at that time. It might be delayed by a few days, but it surely at all times occurs.”
Wayne added, “Nobody’s been capable of clarify why these scorching spots type close to the reformer exit, as an alternative of close to the burners on the entrance. Why would they type on the furthest level from the burners?”
Marnie and Maya gave one another “the look” with good timing.
Extra Unsolved Mysteries
“Right here’s one thing perhaps you’ll be able to assist repair,” stated Ron Sorrel as he started describing the following a part of the method. “We now have exhaust gasoline cooling tubes downstream of the first reformer shell, meant to flow into glycol to get well warmth and funky down the stack. Over time, extreme leaks fashioned within the lengthy underground runs for the cooling water traces. We didn’t lose a lot water. The issue was soil and sand ingress when the water stopped flowing. The soil clogged the warmth exchanger piping, and the sand scored the pipes, valves, and water pumps.”
“We tried to exchange them,” Wayne added. “However there’s numerous underground utilities right here, and only a few of them are marked. These water traces aren’t very deep, perhaps 18 to 24 inches, however the plastic they used not solely doesn’t present up with typical locater instruments, even floor penetrating radar had bother seeing them. If we all know the place they ran, perhaps we may repair them and restore the system to full operation.”
“Doesn’t your chimney undergo injury from the elevated exhaust temperatures?” requested Maya.
Ron replied, desiring to be humorous, “Our exit dampers melted caught open, half our stack lining is gone, and the concrete outer stack is spalling off from the warmth. So, sure.”
“Might you add a water mist curtain simply upstream of the stack to chill it down?” requested Marnie. Ron, Claude, and Wayne checked out one another, then Ron famous, “The one downside I’d see is freezing within the winter. But when we will cease the erosion three seasons of the 12 months, that’s fairly good!”
They walked to the secondary reformer, and Claude continued his narrative. “This method known as air-fired, as a result of we take our nitrogen from bleeding in air, versus pure nitrogen. This reacts with some remaining pure gasoline. After that, the syngas passes by way of high-temperature and low-temperature water-shift reactors to oxidize CO into CO2,” he stated.
Ron took over at this level, including, “If there are issues with the secondary reformer system, it’s that we expect an excessive amount of CO is passing by way of the system. This causes two issues. First, the CO isn’t captured by the MEA carbon seize system simply after the water shift reactors. Then, after the carbon seize system, we have now the Methanator. That makes use of a catalyst to take away the final of the CO and CO2. The issue is CO catalyzation releases a bit of warmth, and if the CO focus coming into the Methanator is just too excessive, the catalyst can bear a runaway response, the place the temperatures can get excessive sufficient to soften the catalyst.”
“I’ve issues,” stated Marnie. “Catalyst temperature runaways aren’t uncommon within the trade, however your plant has skilled them at greater than double the utmost anticipated price. I agree with you on the CO concern, however your DCS information reveals although the CO is everywhere in the map, the DCS says the CO coming into das Methanator (which Marnie pronounced in an terrible Schwarzenegger Austrian accent) is beneath your restrict?”
“So, are you pondering perhaps the high- or low-temperature catalyst is worn out?” requested Wayne.
“Possibly each?” Ron supposed.
Marnie shrugged, including, “Or contaminated.”
“Or your CO sensor is suspect,” Maya opined.
Persistently Lacking Marks
A condenser was positioned downstream of the Methanator to take away as a lot water as attainable from the syngas. As-built, it labored very properly, however a long time of use led to so many main tube failures that almost a 3rd of the condenser tubes have been plugged over.
“We’re lacking that condenser capability, and we’re dropping effectivity and reliability by including dryers to the system,” commented Ron. “I don’t suppose Wayne needs to pay for re-tubing or a brand new condenser, so we’re caught with it for now.”
The final space of concern for the plant employees was the syngas compressors. Compressor rebuilds had elevated from as soon as each decade to as soon as each two to 3 years. The 2 steam-driven compressors have been present process service in the course of the present outage, and the compressor space was coated by an enormous upkeep tent.
Hector referred to as from the tent door and invited everybody inside. Electrical area heaters gave welcome aid from the chilly. Each steam-driven compressors have been utterly disassembled and cleaned, solely ready on inspection for re-assembly.
When requested in regards to the compressors, Hector was blissful to inform their story. “We use multi-stage compressors to spice up the syngas strain to 200 bar [2,900 psi]—assuming every little thing’s working. Usually, we handle 160 to 175 bar, and at 150 bar or decrease strain, we come offline for servicing. We now have two small electrical compressors for startup, however they’re not rated for steady use.”
Trying over the compressor components, Maya observed one thing uncommon. “Sir, these bearing journals, I see scalloping and burnt lubricant. Did the system lose oil strain?” she requested.
Hector shrugged. “No, and we use good high quality oil. For some purpose, it goes dangerous very early. As soon as we modified the oil every year, now it’s each three months, and we nonetheless have issues,” he stated.
Marnie appeared across the compressor space, then Maya famous Marnie doing a basic double take upon studying the labels on the lube oil drums. Turning to the group, Marnie introduced, “OK! I’ve concepts to share. Inside, to espresso, heat, and extra espresso!”
Scientific and Sensible Options
After everybody returned to the assembly room and had changed a big proportion of their blood with scorching espresso, Marnie commenced the nice reveal. “You’re lucky that you just elevated the upkeep funds and preventive upkeep on the plant, Wayne, in any other case this could be a basket case,” she started. “Let’s begin with the first reformer. Maya, your ideas?”
“I suggest as different plant methods suffered extra frequent outages, the first reformer underwent many extra startup cycles. Already a lot previous its working life, fast heating cycles led to accelerated failure in components already affected by creep stress.” Maya paused, studying Marnie’s expression. “However I see there’s something I missed, sure?”
“Sure. Contemplate the situation of the temperature spikes. If the pure gasoline burners have been impinging on the tubes, the failures would happen close to the burners. However as an alternative, they type on the other facet of the reformer, the place the syngas has the very best hydrogen content material. What if hydrogen embrittlement results in pinhole tube leaks, the place a jet of hydrogen and carbon monoxide ignites and overheat the close by catalyst tubes?” Marnie advised.
“Wow,” stated Wayne, who in a single phrase captured the response of the room. “How can we repair that downside?”
“It’s simple, however costly. Your greatest guess at this level is an entire re-tubing, as a result of any dangerous tubes that stay can injury the brand new tubes,” she replied.
Shocked silence reigned, and Marnie, absolutely in character because the engineering detective, stated, “Now, Maya will talk about the issues of das Methanator. Maya?”
Crossing her arms and giving Marnie a stern glare, Maya replied, “Sure, ma’am, however not with that outrageous accent. We all know the methanator catalyst can undergo runaway overheating if an excessive amount of CO enters the system. Some posited the water shift methods have been faulty. I carried out a knowledge evaluation on the CO probe readings and discover with 99% confidence the CO probes produce random outcomes inside their span. The water shift methods are, sadly, attempting to manage their operations to these values, resulting in poor effectivity. The answer? Change the CO probes,” submitted Maya.
“Nice job, Maya!” congratulated Marnie. “Now, as to the compressors, I feel there are a few elements. First, I feel altering the kind of oil will do the trick. You’re presently utilizing polyalkylene glycol—PAG—oil, and it’s good for ammonia refrigeration compressors as a result of it mixes with ammonia, and although it’s hydrophilic, it tolerates some water with out compromising lubrication. However along with your condenser underperforming and permitting higher water in your syngas, the PAG is drawing extra water into the system, resulting in lack of lubrication. I like to recommend switching to an oil that doesn’t combine with water, and putting in an oil drying system, fixing your condenser, or each.”
Wayne and his workforce began peppering Marnie and Maya with questions in regards to the path ahead, when Marnie dramatically held a finger to her lips to quiet the room. “A few of you will have thought I forgot in regards to the major reformer’s exhaust gasoline cooler, and the way to deliver it again into service. Properly, come exterior, and watch some magic!” she inspired.
About quarter-hour later, Marnie had assembled the group in entrance of the disabled exhaust gasoline cooler. A laptop computer was arrange on a tripod, in addition to a thermal imaging digicam that was additionally hooked up to the laptop computer for display mirroring.
Marnie addressed the workforce once more, whereas within the background two plant employees ran water hoses out to the exhaust gasoline cooler header. “This concept got here to me after my aunt handed away final 12 months. As executrix, I needed to promote her home, however earlier than I may promote her home, the county required a map exhibiting the septic tank and its foremost lateral traces. Sadly, no such map existed, and I didn’t need to destroy her yard on the lookout for the traces. I knew the traces weren’t buried very deep, so I waited for a extremely chilly morning, ran scorching water repeatedly down the sinks, and used my thermal imaging digicam to see the warmth flowing to the septic tank, after which slowly out to the laterals, which was sufficient info to fulfill the county,” she defined.
Turning to the plant employees, who had completed hooking up the water traces, Marnie gave them a thumbs-up sign. “Fortunately, we don’t have to attend for a chilly day right here. Wayne, I hope you don’t thoughts my borrowing two of your upkeep crew. They simply hooked up scorching water traces to the exhaust cooler header, and in about 10 minutes, we should always see some magic,” she stated.
The group waited patiently, conversing quietly, till after simply 5 minutes, Marnie squealed with pleasure as her laptop computer display confirmed yellow, then orange traces of warmth slowly shifting alongside the bottom, outlining the underground piping. Guided by the digicam, the 2 upkeep crew members started inserting stakes within the floor to notice the water line areas (Determine 2). Wayne turned to Marnie, and with apparent respect exhibiting, shook her hand.
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2. A thermal digicam offered the perception wanted to seek out shallow underground piping. Supply: POWER |
“OK, you win,” he stated. “Science isn’t boring.”
“It by no means is,” replied Maya and Marnie in unison.
—Una Nowling, PE is an adjunct professor of mechanical engineering on the College of Missouri-Kansas Metropolis.
