If you’ve ever worked in industrial air pollution control or process gas scrubbing, you’ve probably used a spray tower—they’re the workhorses of pretty much any setup that needs to clean gas streams before releasing them to the atmosphere, or recover valuable chemicals from a process. As a spray tower supplier, I talk to folks every day who’ve run into headaches with these systems, and a lot of the time, it’s not that the tower itself is a bad piece of equipment—it’s just that people don’t fully grasp the little common issues that trip them up. Today, I’m breaking down the most frequent problems we see, why they happen, and what you can do to avoid them, straight from the people who build, install, and service these towers every single day. Spray Tower
Let’s start with the big one: clogging. This is hands down the most common complaint we get, and it’s almost never because the tower was designed wrong. Clogging happens when solid particles—whether they’re dust from the incoming gas, crystallized chemicals from the scrubbing liquid, or even leftover scale from the pipework upstream—get stuck in the nozzles, the packing layers (if your tower uses them), or the liquid distribution system. I remember a client a few months back running a metal finishing operation; their spray tower was supposed to clean out acid fumes and particulates, but within a week, their nozzles were completely blocked with tiny metal shavings and crystallized acid. The problem? They didn’t have a pre-filter on the incoming gas line, and they were using a scrubbing liquid that was too concentrated, so it crystallized before it even hit the nozzles. Another twist on clogging we see is biological growth—if you’re using a water-based scrubbing system that’s sitting stagnant for more than a few days, algae or bacteria will form slimy mats that coat the nozzles and packing, leading to uneven spray, reduced flow, and eventually, total blockages. The fix here sounds simple, but it’s skipped all the time: add a small pre-filter to catch solids before they reach the tower, use a slightly diluted scrubbing liquid to prevent crystallization, and keep the system running (or flush it with biocide) if it’s idle for more than 48 hours.
Next up, poor liquid-gas contact. A spray tower only works if the liquid and gas are mixing the right way; if one is skipping the other, your scrubbing efficiency drops off a cliff. A lot of people blame “low efficiency” on the tower size, but more often than not, it’s bad distribution. For example, if your liquid isn’t sprayed evenly across the cross-section of the tower, some areas are getting way more scrubbing liquid than they need, and other areas are totally dry. Or if the nozzles are worn out—after a few months, nozzle tips can erode from high-pressure liquid, so they start spraying a distorted, non-uniform pattern instead of the fine, even mist they’re designed to. We had a chemical manufacturing client last year whose tower was only removing 60% of their target contaminant, instead of the 90% they needed for compliance. Turns out, half their nozzles were worn down, spraying at a 45-degree angle instead of 90, so the liquid was all collecting on one side of the tower, leaving the other side’s gas stream barely touched. They replaced the nozzles, and the efficiency jumped right back up to 92%—no need for a whole new tower. Another side of bad contact is flooding, which happens when the gas flow is too high, pushing liquid back up the tower instead of letting it fall. If you operate a spray tower beyond its maximum gas velocity, that’s exactly what you get: liquid droplets get dragged upward, so they don’t interact with the gas, and you end up with messy, inefficient operation. Stick to the design velocity, and you’ll avoid that issue.
Foaming is another huge pain point, especially for towers that use organic scrubbing liquids or process water with high organic content. Foam forms when the scrubbing liquid has surface-active compounds that create bubbles that don’t break easily—think of it like the foam in a soda, but way more persistent. If foam builds up in the tower, it can get carried out with the clean gas stream, which means you’re losing scrubbing liquid, and you might even be releasing contaminant-laden foam into the atmosphere (which is a compliance red flag, by the way). Foam can also overflow from the liquid sump at the bottom of the tower, leading to messy, unscheduled downtime. We’ve seen clients try to fix foaming by just adding more anti-foam agent, but that’s a band-aid. The root cause is usually too many dissolved solids in the scrubbing liquid, or an organic load that’s too high. For that metal finishing client I mentioned earlier, their foaming was coming from leftover oil and grease in their process water, which was carrying over into the scrubbing system. We suggested adding a small oil-water separator upstream of the tower, and reducing the anti-foam usage by 70%—it fixed the foam overnight. The takeaway here: test your scrubbing liquid regularly, and address the source of the foaming instead of just dumping more chemicals into the sump.
Wait times are another underdiscussed problem, mostly for people who run batch processes. A spray tower is a continuous system usually, so if you’re running a batch operation that only needs to scrub gas for a few hours at a time, you might run into issues with sump buildup. When you run the tower for a short burst and then shut it down, the liquid in the sump doesn’t circulate, so solids settle to the bottom, and the liquid becomes stagnant (which ties back to that biological clogging we talked about earlier). We had a pharmaceutical client a while back that ran small 8-hour batches of solvent extraction every couple of weeks. Their spray tower would clog every time they started a new batch, because the sump had settled solids that got pulled into the nozzles when they restarted. The fix here was simple: add a small automatic drain valve that flushes the sump for 10 minutes after each batch, and a sediment trap in the line leading to the nozzles. No more clogging, no more lost production time.
Another issue we see, especially with older spray towers, is corrosion. A lot of people go with the cheapest material when they first set up a tower, like regular steel, and don’t account for the corrosive nature of their process gas or scrubbing liquid. If you’re scrubbing acid gases like sulfur dioxide or hydrochloric acid, even diluted, they’ll eat through regular steel in a matter of years. Corrosion doesn’t just weaken the tower structure—it also releases metal particles into the scrubbing liquid, which can get carried out with the gas, leading to product contamination (if you’re using the scrubbing system for recovery, not just pollution control) or even damage to downstream equipment. We had a fertilizer plant client whose 10-year-old steel spray tower started leaking from the bottom seams, and the scrubbing liquid had picked up so much iron from corrosion that their recovered ammonia was useless, costing them thousands in lost product. The solution? Upgrade to a corrosion-resistant material like FRP (fiberglass reinforced plastic) or 316 stainless steel if you’re dealing with harsh chemicals. It’s a higher upfront cost, but it saves you way more in downtime and repairs down the line.
Heat loss and temperature mismatch is a more niche issue, but it trips up a lot of folks who are recovering heat or using the scrubbing liquid for process heating. If your incoming gas is hot (like from a furnace or reactor) and your scrubbing liquid is cold, the liquid will evaporate quickly, which reduces the amount of liquid available for scrubbing, and can lower the gas temperature too much for downstream processes. Conversely, if your scrubbing liquid is way hotter than the incoming gas, you might end up with water vapor in the clean gas stream, which can cause condensation in downstream pipes and lead to corrosion there. We had a food processing client last year whose spray tower was recovering heat from oven exhaust, but their cold scrubbing liquid was evaporating so fast that they were only capturing 50% of the heat they should have. We helped them adjust the liquid temperature to match the incoming gas, and added a small heat exchanger to preheat the scrubbing liquid, which bumped their heat recovery up to 85%—exactly what they needed.
Now, I want to be clear: none of these problems are dealbreakers, and most of them are totally preventable with a little planning and regular maintenance. A lot of the time, the biggest mistake we see is people treating the spray tower like a “set it and forget it” piece of equipment, instead of a system that needs basic upkeep, like changing nozzles every 6 months, checking the sump for solids weekly, and testing the liquid chemistry monthly.
If you’re dealing with any of these issues right now—clogging, low efficiency, foaming, or anything else with your spray tower—we’re here to help. We don’t just sell towers; we work with you to diagnose the problem, tweak your existing system, or design a new one that fits your specific process. No generic solutions, just straight talk from people who’ve been in this industry for decades. Reach out to us to chat through your setup, and we can help you get your spray tower running smoothly, no headaches included.
Aerobic Aeration Products References
- Wark, K., Warner, C. F., & Davis, W. T. (1997). Air Pollution Control: Design and Operation. John Wiley & Sons.
- Cheremisinoff, N. P. (2002). Handbook of Air Pollution Control Technology. Butterworth-Heinemann.
- Stern, A. C. (1976). Air Pollution. Academic Press.
Jinan Guangbo Environmental Protection Technology Co., Ltd.
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