Every maintenance budget eventually runs into the same question. A critical piece of equipment is showing its age, and someone has to decide whether to fix what you have or buy something new. For steam system components like thermocompressors, that decision gets complicated by production schedules, because the unit usually cannot come off line while the plant is running.
In paper mills and other facilities that rely on steam and condensate systems, thermocompressor refurbishment has become a popular middle path between living with a worn unit and paying for a brand new one. But it is not automatically the right call for every situation. This article walks through the real costs, the downtime implications, and the factors that should drive the decision one way or the other.
First, Understand What a Thermocompressor Actually Does
A thermocompressor is a type of ejector, sometimes called a jet compressor, that uses high pressure steam as its driving force. There are no rotating parts, no motor, and no bearings inside. High pressure steam passes through a nozzle, which converts its pressure energy into velocity. That fast moving steam entrains a lower pressure steam stream and accelerates it. The mixture then enters a diffuser, where the velocity head is converted back into pressure head, and the combined flow discharges at an intermediate pressure.
In a paper mill dryer drainage system, this matters a great deal. The thermocompressor recompresses blow through steam from the dryers so it can be reused, and it provides the pressure differential that sweeps condensate out of the dryer cylinders. When the unit is worn or poorly matched to current operating conditions, the mill pays for it in two ways: higher high pressure steam consumption and poor condensate removal, which shows up as inconsistent drying and slower production.
Because the unit has so few parts, it can run for decades. That is exactly why so many thermocompressors in service today were sized for machine conditions that no longer exist.
The Case for Refurbishment
Refurbishment means restoring the unit to its original design specifications, or better yet, updating it to match the operating conditions the machine runs at today. A typical scope of work includes internal and external inspection of all parts for wear, dimensional inspection of critical components like the nozzle, spindle, and tail against original design specs, actuator inspection and testing, and replacement of wear parts such as the nozzle, spindle, stuffing box, packing, gaskets, and diffuser.
The cost argument is straightforward. A refurbishment generally costs a fraction of a new unit. The body and housing, which represent much of the material cost of a new thermocompressor, rarely need replacement. What wears is the internals, and internals are relatively inexpensive compared with starting from scratch.
The downtime argument depends on how the work is done. There are two basic approaches:
Return the unit to the factory. The complete unit ships out, gets torn down, inspected, rebuilt, and tested, then ships back. This gives the most thorough result, but it requires either a spare unit to install in the meantime or a planned outage long enough to cover shipping and turnaround time.
Install replacement parts on site. The critical parts can be supplied as a kit and installed by mill personnel or a field service technician during a scheduled shutdown. For a mill that already has an annual maintenance outage, this option can add little or no additional downtime at all. The unit comes apart, the new internals go in, and the machine starts up on schedule.
There is a third benefit that often gets overlooked. Because the critical parts are dimensionally inspected against original design specifications, a proper refurbishment is also a diagnostic opportunity. If the nozzle throat has eroded or the spindle has worn, you learn why the unit has been consuming more motive steam than it should. And if the machine has been sped up, or the syphon design has changed, or the grade mix has shifted, the refurbishment can include resizing the internals to match. That is something a like for like replacement cannot do unless someone stops to ask the same questions.
The Case for Replacement
Refurbishment is not always the answer. There are situations where buying new makes more sense.
The unit is truly at end of life. If the body itself is corroded, cracked, or warped, or if previous repairs have altered critical internal geometry, restoring internals will not fix the underlying problem. At some point the shell is the problem.
Operating conditions have changed beyond what a retrofit can handle. A modest change in machine speed or steam pressure can usually be accommodated with new internals. A radical change, such as a major capacity upgrade or a switch in steam supply conditions, may call for a fundamentally different unit size or configuration. In that case the refurbishment path converges with the replacement path anyway, and the only question is whether the old body can be reused.
You need a spare anyway. Some mills buy a new unit and keep the old one as an emergency spare, refurbishing it later so it can be swapped in during future outages. This is common on machines where a thermocompressor failure would shut down production.
Lead times and logistics favor it. Occasionally a new unit can be delivered faster than a full factory refurbishment, especially if the old unit has to ship a long distance and back.
Comparing the Numbers
Every plant is different, but the general shape of the comparison looks like this.
Refurbishment typically runs somewhere between a quarter and half the cost of a new unit, depending on scope and how much of the internals need replacement. On site part swaps push the labor cost into the mill’s existing outage budget. Factory refurbishments add shipping and turnaround time, usually measured in weeks.
New units carry the full purchase price plus installation, but they come with a warranty, known performance, and no hidden surprises from decades of service. If the old unit has been patched repeatedly, the reliability math can favor new equipment even at a higher upfront cost.
The energy side of the ledger deserves as much attention as the purchase order. A worn nozzle or a unit sized for the wrong conditions wastes high pressure steam continuously, and steam is often the largest energy cost in a mill. A refurbishment that restores proper entrainment performance can pay for itself through steam savings alone, sometimes in a single year. That is why the evaluation should always start with the unit’s minimum and maximum operating conditions, not with the price quote.
A Practical Decision Process
If you are staring at this decision right now, here is a sequence that works.
- Pull the original design documents and the current operating conditions. Compare them honestly. If the machine has changed, note it.
- Have the unit evaluated, either by sending it out or by having a specialist review the operating data. Ask specifically whether the internals match current conditions.
- Get quotes for both paths: refurbishment to current conditions, and a new unit sized for current conditions.
- Compare total cost, including installation, downtime, and expected steam savings, not just the invoice amount.
- Factor in risk. A unit with a sound body and worn internals is a refurbishment candidate. A unit with a compromised body, or one that has been repaired repeatedly, is a replacement candidate.
The Bottom Line
Neither option wins all the time. Refurbishment shines when the body is sound, the internals are worn, and the mill has an outage window where the work can happen without added downtime. Replacement wins when the unit is beyond restoration, when conditions have outgrown the design entirely, or when a spare is part of the plan.
What almost never makes sense is doing nothing. A thermocompressor that quietly loses efficiency does not announce itself with an alarm. It shows up as a slow creep in steam consumption and drainage complaints that get blamed on everything else. Whether the answer turns out to be a rebuild or a new unit, the evaluation itself is usually the highest value step, because it tells you which path you are actually on.