Foam arises in many industrial processes. It can be produced biologically—due to anaerobic digestion or brewing—during wastewater cleanup, or while cleaning and preparing starchy vegetables.
Antifoam additives are often used to prevent foam forming in industrial processes, but the amount used can be difficult to control, and overdosing can be costly. Using insufficient quantities of additives can result in excess foam generation, causing potential equipment failures and/or requiring extensive cleanup. Overuse use of antifoam additives (a common problem) is expensive and creates the potential for product and environmental contamination.
WE HAVE HELPED INCREASE THE PROFITABILITY OF MANUFACTURING & TREATMENT PLANTS BY ADDRESSING LONG-RUNNING FOAM ISSUES.
Do you have any of these concerns?:
“We need to reduce our use of antifoam additives in order to control costs.”
In processes where foam must be kept at bay, processing and manufacturing plants often rely on continuous dosing of antifoaming agents. This method assumes that the process will always produce foam, even when it doesn’t.
It is often the case that there is a limited budget for remedying the issue, the typical short-term solution is to install a manual foam control solution, which allows operators to turn on a pump to dispense antifoam agents when needed.
However, this relies heavily on someone noticing the problem and keeping tabs on it until it is resolved. This results in a tendency to “overdose,” because pumps are left running too long due to operators being called away to attend to other matters. Thus, whether this reactive strategy is automated or manually implemented, it is clear that the high cost of de-foaming additives makes this method an expensive foam control solution.
The ideal approach is to install an automated foam detection and control system that only adds antifoam chemical when foam is present, eliminating reliance on continuous human surveillance and significantly reducing the amount of chemical used.
“We keep having issues with unexpected foam overflows, which result in downtime and require extensive cleanup.”
In plants where foam is a common occurrence, antifoam chemicals are often continuously added to counteract foam generation. However, the dosage rate used does not necessarily prevent “foam-outs” or “foam-overs” caused by unexpected changes in process conditions. Plant outages and upsets can often require the manual addition of antifoam chemical over and above the quantity already being dosed.
This is not an efficient or effective approach to controlling foam, and often leads to overdosing due to the urgency of resolving the situation quickly. In these situations conditions often seesaw between excessive and insufficient use of antifoam additives, and operators find themselves frustrated with continued frequent foam-outs despite increasing usage of antifoam.
The best possible solution is to implement a foam detection and control system. Solutions range from control using a “shot and delay” pump strategy to add antifoam chemical whenever excess foam is detected or, for continuously foaming conditions, a PI control regime to continuously adjust the dosage rate of antifoam chemicals depending upon real time conditions. Adding automated foam control will go a long way to ensuring that the potential for foam-outs is mitigated before they become a problem.
Even if you choose not to automate foam control, a lower cost solution is to implement foam detection instrumentation that immediately raises awareness of a foaming event occurring. Immediate warning will allow more time to deal with the problem before it gets out of hand.
“Production numbers have been down due to antifoam chemicals contaminating the end product.”
Switching to an automated foam control method which dispenses only as much antifoam as is measured by foam detection systems significantly reduces the total amount of antifoam agent used, mitigating the potential for product contamination.
Traditional, semi-autonomous foam control relies on the continuous feed of antifoam chemical into the process but the resulting level of entrained antifoam chemical can affect the quality of the end product.
“We have to dedicate employees to monitoring foam levels. We would like to be able to devote them to more critical and profitable tasks, and potentially reduce our overhead.”
Fully automated foam detection and control systems can manage foam without the need for human intervention, freeing up staff to attend to other necessities. Systems with automated antifoam control systems can even be left unattended during night shifts and weekends, potentially allowing for either reduced staffing during these periods, or re-dedication of employees to other, more critical needs.
“Our final product requires multiple washing stations to remove antifoaming agent residue.”
The stopgap solution for reducing reliance on the use of antifoamer chemicals and washing stations is to reduce the process flow and agitation that creates foam. However, a lower flow inevitably means lower yields.
In the long term, the best results are produced by implementing an automated foam control solution which utilizes three probes to detect foam at various process states and can dispense antifoam chemicals as needed, early in the foam formation process.
“The probes we currently use to monitor foam levels become fouled on a regular basis, requiring frequent manual cleaning. Is there a better measurement solution?”
A common mistake is to install instruments such as capacitance level probes to monitor process foam levels. However, capacitance (and other technology) probes are designed to measure liquids, not foam. Foam is only ~1% liquid, therefore misapplying a liquid level probe in this manner is bound to have issues, particularly when coatings are involved. Even high-quality liquid level probes will struggle to measure foam reliably – on average, they will perform about 50% of the time at best.
Obviously, this isn’t an ideal solution. There are now probes on the market which incorporate technology which control for the effect of accumulated material on the probe. This allows the monitoring technology to effectively ignore the product buildup, and continue to deliver accurate readings.
“We need to show the EPA and other regulatory agencies that we are reducing the levels of chemicals and other contaminants in the effluent we discharge into the environment.”
Systematic reduction of the use of antifoam chemicals throughout the process will reduce the antifoam residual amounts in the final effluent discharge. Adopting the automatic “dose as required” system, rather than a “dose on upset” will help to reduce the amount of antifoam chemical used, leading to the overall reduction of antifoam chemicals in final effluent discharge.
This has been an effective approach for a variety of industries and applications, from vegetable processing to oil and gas production.
We have found that in wastewater treatment, foam can sometimes be controlled with water sprays which disrupt bubbles in foam, keeping them at bay. This approach does not, however, change any foaming tendency in the flowing stream as it still contains surfactants (the surface-active substances which cause foam). Monitoring the stream after or upstream of the water spray nozzles can help determine whether antifoam chemical is also necessary. Foam control systems which feature multiple inputs allow for multistage process monitoring, and can dispense antifoam chemicals only as needed.
South Fork Instruments supplies industry-leading foam detection and control instrumentation for use across all industries. To learn how we can help your business with foam management, fill out the form and select your industry to instantly receive a free case study.
Frequently Asked Questions
How can bioreactor processing yields be increased?
By implementing a foam detection and control system which detects foam and trigger dosing pumps to dispense antifoam chemical only when needed, thus reducing excessive levels of antifoam in the media which can allow for a healthy oxygen transfer rate for maximum cell growth.
The bioreactor filter becomes clogged with foam, causing the pressure relief valve (PRV) to vent. How can this be prevented?
Install a foam control system which allows for real-time monitoring and control of foam buildup, which can prevent filter clogging and ensure that the PRV does not vent and possibly contaminate the media.
Are there bioreactor probes that don’t give false positive readings when they are coated or fouled?
New probes have come onto the market which utilize patented sensing technology that allows them to ignore probe coating and fouling and continue to deliver accurate foam measuring.
What is the best way to control foam-over events?
Implement foam detection and control instrumentation that will provide automated control of foaming events and allow for a rapid response. This saves labor associated with cleanup, and also reduces potential slipping hazards.
How can I reduce chemical agents in my final effluent?
Systematic reduction of the use of antifoam agents throughout the wastewater treatment process will reduce antifoam chemicals in the final effluent discharge. The best means for doing so is the adoption of an automated foam detection and control system that only doses as required.
pulp & paper manufacturing
How can I reduce the number of holes and spots in my final paper product?
These defects are often due to entrained air/foam in the pulp feed. Installing a foam detection probe in the head box allows for the measurement of foam, and the dispensing of defoamer chemical to reduce the amount of entrained air.
How can I reduce foam buildup in our settling tanks?
Strategically placing foam detection probes and automated control systems can reduce the incidence of foam buildup in open tanks, vessels and pits throughout the pulp mill.
How can I fix slow and inconsistent drainage rates on our forming tables?
Defoamers can often remedy this issue, but should be introduced into the media before the pulp feed reaches process equipment, such as hydrocyclones, that can entrain air. By dosing through proportional, integral control, surface foam levels are controlled by controlling the amount of dosing. As foam levels increase/decrease, the amount of dosing also increases/decreases, maintaining the proper media balance.
How best can we reduce the amount of antifoam residue on our end product?
When antifoam chemicals are present in such high quantities that they contaminate food products, manual management of foam is usually to blame. Installing an automated foam detection and control system can significantly reduce the amount of antifoam used, as it is only dispensed when needed, and in the proper amounts from an automated foam control system.
How can we keep foam from entering and potentially damaging process equipment?
Foam generally only presents a threat to process equipment when it forms in such large quantities that foam-over events occur. A foam detection system that can automatically inject antifoam chemicals when foam is present can prevent such events from happening.
Can we automate how we control foam in the food manufacturing process to reduce our housekeeping costs?
As with damage to equipment, foam-overs are the products of inadequate foam management, usually in the form of visual inspection and manual dosing of antifoam additives. Transitioning to an automatic foam detection and control system can quickly resolve issues with rising foam.
Oil & Gas
How can we stop liquid—in the form of foam—from being carried-over through the amine scrubber and associated knock-out vessels downstream, and getting into the fuel gas compressors?
The installation of foam detection and control systems in both the scrubber and subsequent knock-out pot will alert operations to the presence of foam in the system and allow for its remediation before it can be carried into the compressors.
We use a continuous dosing method to control foam formation and protect our compression set. How can we reduce chemical usage and associated costs?
Controlling foam can be a fully automated process, and eliminate extraneous dosing being performed when no foam is present. This can translate to significant cost savings against a relatively low investment in operating infrastructure.
How do we show the EPA that we are reducing chemicals and contaminants in effluent we’re discharging into the environment?
Many chemicals are used to convert crude oil into refined products, including antifoam additives, which are injected into the process and waste streams to aid in foam reduction and elimination. Monitoring for foam generation in waste streams, pits, and channels can reduce antifoam chemical consumption, and consequently reduce total chemical discharge.