Complacency can be career limiting

Recovery boilers are a beast.

Converting black liquor to smelt is a reduction process that generates a lot of heat and air-borne particles, which themselves have great value when collected.

Particle deposit in the economizer tubing can ‘plug’ a boiler leading to unneeded, and generally, unexpected downtime.

Deposits clinging to blades in the ID fan has caused many a headache for operations and maintenance and electrostatic precipitation performance can lead to environmental issues no one wants.

So, what is done to mitigate these potential troubles?

The easy one is ID fan contamination. It will show up with your vibration condition monitoring program.

Getting the blades cleaned is another issue.

Shutting down a recovery boiler is an undesirable experience and will almost always cause the entire pulping process to shutter, losing production.

Even the process of balancing the liquors to accommodate a brief shutdown is a time consuming, minutiae filled undertaking.

Keeping the air passages clean is another troublesome area.

It is not unusual for placement of 80 -100 sootblowers in a recovery boiler’s economizer and superheater sections. Each sootblower is a potential, routine maintenance issue and their failure can lead to plugging of normally open-air passages which optimize the boiler’s performance. Too many plugs, or concentrated plugs can result in downtime, again for cleaning.

https://tspace.library.utoronto.ca/bitstream/1807/97450/1/J141%20-%202015%20Recovery%20Boiler%20Sootblowers-History%20and%20Technological%20Advances.pdf

Aside from these and the normal, everyday issues with liquor spray pumps, nozzles and smelt channel cleaning the biggest issue is the possibility of a tube crack in the ‘fire’ zone of the boiler. The explosion can demolish a boiler which today is a multi-hundred-million-dollar capital investment.

Avoidance is key.

The typical mitigating task for this issue is inspection of the exposed tube condition.

Usually, these inspections are a requirement of the property loss/production loss insurance provider.

Over time these inspections have seen frequencies between inspections lengthened from six months to one year and due to good performance, thorough inspections and corrective maintenance extended now to 18 and 24 months for some operations.

This is where the process can get dicey. There are procedures published.

https://www.tappi.org/content/events/08kros/handouts/5-5.pdf

Some mills, very few, still perform their own inspections with an experienced team composed of lab techs, maintenance mechanics and supervisors, and operations personnel.

It was not uncommon, in days past, to have a specialty team composed of other mill’s experienced personnel plus internal site people to perform the inspection.

Many mills contract this critical effort to a variety of resources, some with excellent credentials, some with less. Some with great experience, others gaining experience and a few just entering the inspections arena.

This is one of those assignments that should not be determined by price.

Advice to those that are joining an organization for the first time, maybe with some previous experience with the inspection process or, maybe with no experience, and have authorization influence on the inspection process, do not become complacent and assume all is well just because you hear ‘we’ve done this before’.

Ultrasonic tube thickness inspections are one thing, visual inspections are another, and while both reference condition, experience and analysis is critical.

Any person can become a ‘thickness data collector’. Usually, the basic requirement for the job is the capability to crawl into dirty, hot, closely confined environments, clean the tube surface, smear it with petroleum jelly and record the thickness, on some prearranged grid location then move on to the next.

Complacency enters the scene when you, the responsible person for this effort, fail to assure the data being recorded is accurate, thorough and all adjacent areas are observed for condition.

Depending upon the location in the recovery boiler these observations can be easy, or not.

The bed of the boiler, for example, after it has been thoroughly cleaned of encrusted smelt, can easily be inspected and data recorded, but again someone with experience, someone who knows what they are looking for, should be part of the inspection team, be it supervisor, engineer, operations, whomever.

I know of one unfortunate former Engineering/Maintenance Manager, new to a mill, who assumed that because prior inspections had been performed by the mechanical contractor used every shutdown for boiler repairs with apparently no significant issues that all was okay on that issue.

Strictly by accident, after a review of that years’ annual inspection documentation, he became suspicious of this process by these people, including members of his own staff responsible for the management of the inspection process.

Contracted an inspection firm he had used before in his past crossed his mind. They always documented their concerns so that visuals could be presented daily in conference settings with all interested parties.

Each day their crew arrived with freshly cleaned white coveralls, which always provoked a humorous response from those working in the area. At the end of the day, though, when they emerged covered in reddish mostly, sometimes grayish or blackened colored coveralls everyone knew they had been inside the boiler’s various sections, twisting, turning, kneeling, crawling, sprawling, and sitting while performing the required inspections.

After much haggling, arm twisting and cajoling internally the E&M manager was able to hire the contractor for the current year’s inspection.

What they had discovered was neglect. A complete lack of knowing what good should look like.

Based upon their observations, thickness measurements were fine, but obviously the previous year’s, and likely before, observations of the fireside condition of the boiler floor tubes surface was ignored, keeping in mind the adage “know what good looks like”.

At the inspection firm’s suggestion, a personal inspection was performed, and observations made.

The fireside surface of the floor and sidewall tubes looked remarkably like the hide of an elephant, crevasses of varying depth pockmarked the surface of each tube on the bottom and up to the primary air entrances on all four walls of the furnace area.

In their opinion, based upon their experience, this condition likely had occurred at least a year, and more likely, longer ago, due to overheating of those exposed tubes perhaps during a extended start up on oil. (Recovery boilers are usually started with an auxiliary fuel before switching to concentrated black liquor.)

As the venerable saying goes, the ‘shit hit the fan’ when the result of the inspection was broadcast, and everyone within the immediate vicinity got splattered.

Imagine the cost of replacing four walls and the floor of a 20-year-old recovery, especially when unexpected, and worse, the loss of production.

Complacency with established practices is common, and easy to adopt.

Shareholders, and upper management, some whose past included this mill, from their viewpoint, are generally intolerant of failures especially when established past practices/policy are implicated.

Eventually the incident resulted in the dismissal of many personnel, including the E&M Manager, Power & Recovery Manager and Mill Manager.

Keep this in mind when reviewing your criticality assignments and the resulting mitigation actions.