Skip to Content
Exit

Category Archive: Heat Exchanger Tube Cleaning

Tag Archive: Heat Exchanger Tube Cleaning

  1. Chiller Tube Maintenance Step-by-Step Guide

    Leave a Comment

    Chiller tube maintenance is likely not on the top of facility managers’ minds during cold months. But just because they may not be in use, doesn’t mean you shouldn’t give them some attention during the winter season. In fact, this extended period of time when chillers are not a critical component of your building’s HVAC efforts is the perfect opportunity to address any chiller tube maintenance concerns.

    Of the many components of a chiller, the tubes are one of the most impactful in terms of overall energy efficiency, according to The NEWS. Chiller tubes and coils can become dirty or coated with scale over time, which decreases their heat transfer capabilities. As a condenser’s heat transfer ability goes down, its energy consumption goes up – sometimes by 30 percent or more, according to the U.S. Department of Energy. A well-maintained system, therefore, can save energy and money. If your condenser was struggling to reach a full refrigeration load or was reaching higher pressures than expected, it’s likely you have buildup that’s increasing your energy spend.

    Begin Your Chiller Tube Maintenance with Clean Tubes

    An initial water cleanse is a good step toward cleaner tubes, but it shouldn’t be your only means to achieve greater energy efficiency. There will likely still be scaling left clinging to the tube walls after the cleanse is finished, especially considering that most chiller tubes have ridges in them.

    A rotary tube cleaner, like the Goodway Ram-Pro sold by Enerquip, includes a brush that rotates to get into those grooves and can help immensely. Newer models of rotary tube cleaning systems also allow you to add antimicrobials and corrosion inhibitors onto the surface of the tubes to minimize future scaling.

    Choose the brush you use with the rotary tube cleaner carefully, as different models are designed to clean specific types of fouling. There’s a big difference between removing softer fouling like algae and mud compared to tougher scaling and mineral deposits.

    You may also consider using chemical descalers to tackle more difficult forms of buildup like calcium, rust and lime. However, before you choose chemicals to insert into your tubes, make sure they’re compatible with the equipment’s materials of construction. If your tubes were fabricated with an alloy that’s highly resistant to corrosion, such as stainless steel, this may be less of a concern.

    Cleaning your tubes should be at least an annual or biannual task, and doing so during the colder months can give you ample time to address any issues before the weather warms up again.

    Do an Eddy Current Test

    Many chillers go through eddy current testing after fabrication and installation to test for any damage that may have occurred before the unit is fully operational, Process Cooling explained. It’s also a good method to test for issues that may arise during the lifetime of the chiller.

    An eddy current test may be able to detect small defects that can lead to leaks, but it shouldn’t be confused with an actual leak test, Texas Eddy Current explained. An eddy current test, sometimes called a magnetic field test, can highlight corrosion, erosion, mechanical damage and more. It can also indicate whether your tube walls have lost thickness over the years, Facilities Net reported. To conduct this test, a metal probe that creates a full-circle magnetic field is inserted into the tube. As the tester moves the probe through the tube, the magnetic field will either remain stable or show signs of a disturbance. Those signals indicate an issue at that location.

    You don’t necessarily need to do an eddy current test each time you clean your tubes. Once every two or three years for your chiller or three to five years for your evaporator should be sufficient.

    Treat Your Water

    The quality of the water that enters and flows from your chiller plays a big role in determining how often you should perform chiller tube maintenance and cleaning. When you know the water quality in your area, you can take proactive measures to prevent scaling and fouling in your tubes.

    “When you know the water quality in your area, you can take proactive measures to prevent scaling.”

    Closed-loop systems, which are most common in chillers, generally require a one-time chemical treatment to reduce the risk of fouling. If you have an open-loop system, which may be found in condenser systems or atmospheric cooling towers, you’ll likely need to arrange for continuous chemical treatment. In any case, water treatment should be tailored to the unique qualities of the local water source. A water treatment specialist in your area is the best resource to consult.

    Though keeping the risk of fouling at a minimum may be your highest priority, you should also keep in mind other conditions of the water, such as the temperature and flow rate, Contractor Business explained. Colder water is generally more efficient to use in chillers. In fact, if your chiller isn’t running optimally and you aren’t prepared to clean the tubes just yet, lowering the temperature may be a good temporary solution for improving efficiency. Don’t mistake this as a long-term fix, though – if you’re looking for sustained improvement, it’s critical to remove scale and other buildup in the tubes.

    The flow rate should generally be between 3 and 12 feet per second. Fall below this range and you’ll get laminar flow that reduces the efficiency of the chiller. Higher flow rates can cause the equipment to vibrate and shake, and increases the risk of damage to the tubes.

    Create a Prevention Plan for Your Chiller Tube Maintenance

    Setting aside enough time to conduct thorough chiller tube maintenance and inspection is a great first step toward lasting energy efficiency, but it’s important to plan for the future, too. Every system is different, so you should create a plan to keep your unit running well for years to come.

    Creating a daily operating log will help you visualize small day-to-day changes in the chiller’s performance, which will indicate how often you should repeat the cleaning process. It will also clue you into small issues that occur. Identifying and addressing these before they escalate into larger problems can help you maintain a functioning chiller for longer.

    In time, you may start to notice patterns in your chiller’s performance. This will help you create a schedule for inspections and maintenance.

    Know When to Replace Your Chiller

    Every chiller will be replaced sooner or later. Though these units can generally be relied upon for several decades, they’ll eventually become more costly to maintain than it would be to install a newer, more updated model. If your chiller is presenting frequent issues and is close to 25 or 30 years old, it’s likely ready to be retired, Facilities Net explained.

    When choosing your next model, seek out a manufacturer that can provide reliable, high-quality equipment. The engineers at Enerquip are here to help identify shell and tube requirements for a wide range of assets, including chillers. Request a quote.

  2. How often should you clean your shell and tube heat exchanger?

    Leave a Comment

    Keeping your shell and tube heat exchanger contaminant-free is critical to creating a high-quality final product. However, every company must face a hard (and sometimes calcified) reality: Fouling happens. When it does, the built-up matter needs to be removed, and the equipment sanitized.

    Of course, there are some downsides to cleaning your shell and tube heat exchanger. The process usually needs to be done offline, thus eliminating some production time. Reducing the number of hours your equipment is productive will have an impact on your company’s bottom line. Then again, so will fouled material if allowed to continue to build up in your equipment. Further, excessive buildup will reduce heat transfer efficiency, causing processes to increase in price and length of time.

    Thus, equipment operators must strike a balance between regular cleaning times and fouling accumulation. To make sure your shut-down day has as low an impact on your business as possible, take these factors into consideration when planning your cleaning schedule:

    Fouling allowance

    The Tubular Exchanger Manufacturers Association recommends that companies determine well in advance what they would consider an allowable amount of fouling and take these into consideration when calculating heat transfer resistance, as well as determining a cleaning schedule, according to Conoco Consulting Corp. When your level of fouling nears this level, you’ll know it’s time to plan your next shut-down day, though you’ll usually define a loose maintenance schedule when calculating your fouling allowance.

    Engineers typically determine the allowable amount of fouling during the design stage, according to InTechOpen, an open access science, medical and technology book publisher. This is an important factor to take into consideration when calculating the heat transfer coefficient. A higher fouling allowance will result in a lower coefficient, but may also result in fewer necessary cleaning days.

    Fouling allowance can be thought of in several different ways, including a percentage of fouled matter as compared to the overall surface area, how clean the equipment is or what the maximum fouling resistance should be.

    Cost of operation

    Keeping a close eye on the cost of your operations is a good indicator of efficiency and productiveness. As fouling builds up, so too will your cost of operations per hour. The increase in cost is due to greater energy needed to achieve the same heat transfer rate, a lower rate of production, or a combination of the two.

    Referencing a 1981 report, “Optimum Cycles for Falling Rate Processes,” published in The Canadian Journal of Chemical Engineering, Conoco Systems suggested determining when your process will reach its minimum value to the company. When calculating this, you’ll need to take several factors into consideration, including the cost of cleaning, the cost of the lost production time and any interest accumulated due to borrowed funds, if applicable. Compare all this to the cost of reduced efficiency of the heat exchanger.

    Your production cycle

    No one knows your production cycle better than you and the people at your company. You know when your busy seasons are and when business slows down, as well as when you’ll have three-day weekends. Use this knowledge when planning out your cleaning schedule.

    With this information, you’ll be able to choose a day or several days to shut down your plant for much-needed cleaning without taking away from a busy or usually productive day. Additionally, you know your staff won’t feel pressured to make up for lost production time when everything is shiny and new once more. If it makes sense to schedule cleaning over a three-day weekend, take advantage of the day off and turn it into a day offline.

    Every operation is different and will require different intervals between cleaning. Some plants may require multiple shut-down days each year; others might be able to hold off for a decade using effective fouling mitigation tactics and discretionary maintenance tasks. It’s important to decide what’s right for your company so you can ensure consistent quality at as low a cost of production as possible and with minimal disruption to normal business operations.

    If you’re in the market for a new shell and tube heat exchanger, reach out to the helpful engineers at Enerquip. When you explain your operation and needs, they’ll be able to work with you to design and fabricate a custom shell and tube solution that works.

  3. What you need to know about cleaning different tube configurations

    Leave a Comment

    When considering your options for a new shell and tube heat exchanger, one important factor is the tube configuration.

    Various options benefit different types of processes. For example, a floating head configuration is better suited to processes prone to significant thermal expansion because the tubes aren’t constrained by the tube sheet or the shell, and can therefore expand or vibrate without risking damage to the rest of the equipment.

    Beyond taking into account the intended use for the exchanger, and other elements like location of the exchanger or the product that will be introduced to it, it’s also a good idea to think about cleaning methods. Not all cleaning strategies are appropriate for all configurations, but all exchangers will need to be properly and thoroughly cleaned sooner or later. It’s best to know what cleaning capabilities you’ll have with a particular configuration beforehand so you can factor it into your decision, or at least prepare for new sanitation needs.

    How to Clean a Fixed Tubesheet Shell and Tube Heat Exchanger

    A fixed tubesheet is a popular shell and tube heat exchanger design for several reasons, including cost effectiveness and ease of cleaning. Since the tubes are straight and the tubesheet is welded straight to the shell, construction is relatively simple.

    To clean a fixed tubesheet shell and tube heat exchanger, the bonnet first needs to be removed. This is a relatively simple task with this configuration. The insides of the tubes can be cleaned mechanically, and the straight configuration makes it easy for brushes, hoses or other cleaning supplies to be fed into the bores. The tubes can also be cleaned chemically, and running the cleaning solution through the tubes is fairly easy, again, because of the straight design.

    While cleaning the tubeside is pretty straightforward, shellside cleaning is a bit more complicated with fixed tubesheet designs. Because the tubesheet is welded to the shell itself, it’s nearly impossible to mechanically clean the outsides of the tubes. Chemical cleaning must be done instead. However, it’s critical that operators are confident that the chemical cleaning agent can be thoroughly rinsed from the shellside before operation reconvenes. Leftover residue can damage the material of construction or contaminate the product.

    The bonnet type plays a role in how easy it is to reach the tubes. L-type and N-type bonnets, which have removable covers, grant easy access to the inside of the tubes without removing any piping. The M-type bonnet does not have this removable cover, which means the entire head needs to be taken off to access the tubes.

    The difficulty in shellside cleaning isn’t always a problem. If the shellside of this heat exchanger is only used for clean fluids rather than fouling services, there’s virtually no need for future cleaning.

    How to Clean a U-Tube Shell and Tube Heat Exchanger

    As the name suggests, the tube bundle of a U-tube exchanger is curved at the end and returns the fluid back to the same side it entered, rather than providing a point of exit on the opposite end of the exchanger. Thus, only one tubesheet is required, leaving the other end free to expand or vibrate without risking damage to the rest of the construction.

    While the U-shaped bend provides benefits in some ways, it becomes cumbersome when it comes time to clean the equipment. The curve at the end of the tube makes it challenging for mechanical cleaning, unless a flexible-end drill shaft is utilized. Chemical cleaning is possible, but certain types of fouling, make it challenging – particularly scaling that hardens to the sides of the tubes and is difficult to remove without physical force. Additionally, with scales forming at the point of the bend, it may be difficult to assess whether all fouling has been completely removed. The solution to this dilemma is to use clean fluids on the tubeside with this configuration, Thermopedia pointed out.

    An articulating brush is advantageous for cleaning U-tubes.

    While cleaning the interior of the tubes on U-tube exhchangers is a challenge, the shellside is very easy. Since there’s only one tubesheet, deconstruction is simple. Once removed, the shell and the outside of the tubes can be cleaned easily.

    How to Clean a Floating Head Shell and Tube Heat Exchanger

    The floating head tube bundle configuration is the best of both worlds. Only one end of the two tubesheets is welded to the shell, allowing the other to expand as needed according to the process it’s engaging in, similar to the U-tube configuration. Meanwhile, the straight tube design makes cleaning easier, comparable to the fixed tubesheet configuration.

    These advantages make floating head shell and tube heat exchangers a favorite among operators who are concerned both about thermal expansion as well as fouling on both sides, such as petroleum refineries or kettle reboilers, for example.

    A number of methods can be employed to sanitize floating head shell and tube heat exchangers and remove fouling. Mechanical cleaning is a practical solution, as the straight tubes make it easy for brushes, bits and sprayers to reach all areas of the bores. The floating head configuration makes it easier to remove the tube bundle than with the fixed tubesheet design, so it’s easy to reach the outsides of the tubes and the interior of the shell.

    Chemical cleaning is also a possibility, especially because it’s easy to spot inconsistencies in the cleaning job. When insufficiently cleaned areas are identified, they can be mechanically or chemically cleaned again before the equipment is put back into operation.

    The bonnet type associated with a particular exchanger’s construction plays a role in how easy this configuration can be cleaned. A P-type rear header, which is an outside packed header, gives convenient access to the tubeside but does not allow the tube bundle to be removed so the shellside can be difficult to clean.

    The S-type header also allows the tube bundle to be removed, but it is hard to take apart for bundle pulling, which can cause some complications when it’s being cleaned, inspected or repaired. The T-type header is easier to dismantle and remove than the S-type, often making it a more desirable configuration, though it also tends to be a bit pricier. The W-type header is also easy to remove and is often the least expensive of the options for a floating head heat exchanger.

    Proper Cleaning Prevents Fouling

    No matter what type of shell and tube heat exchanger you have, it’s important to know how to properly clean it to prevent fouling and ensure deposits left behind won’t cause corrosion.

    To learn about the right configuration for your operation, reach out to the helpful engineers at Enerquip

    More from the Enerquip Blog

    Preventing Cross Contamination in Your shell and tube heat exchangers

    Five Important Qualities to Look for in Pharmaceutical Process Equipment

    Pharmaceutical manufacturers must meet ASME-BPE standards

    Closed-loop process cooling can help reduce water, energy use in pharmaceutical manufacturing

    Enerquip Pharma Exchangers meet cGMP’s

  4. Heat Exchanger Routine Maintenance Tips

    Leave a Comment

    How do you tackle your shell and tube heat exchanger routine maintenance? When heat exchangers are an essential aspect of your operation, it’s important that they’re working at top efficiency. Dirty or fouled exchangers can slow down your processes, contaminate your product and lower your company’s overall efficiency. To avoid these negative consequences, it’s important to be vigilant about shell and tube heat exchanger routine maintenance and proper cleaning.

    Here are five factors to keep in mind to make your shell and tube heat exchanger routine maintenance as effective as possible:

    1. Create a Plan for your Heat Exchanger Routine Maintenance

    When it’s time to clean your shell and tube heat exchanger, there’s a good chance that you’ll need to shut down operations temporarily. This is lost production time, which translates to reduced output and efficiency. However, there are ways to minimize the effects of a plant shutdown. One of the most effective ways to lower the impact is to prepare for it.

    Have a dedicated datefor planned maintenance, Ethanol Producer Magazine suggested. This way, you can plan and prepare for the event, allowing you to choose an inconsequential day for the shutdown. Additionally, since contractors who specialize in equipment maintenance often have busy schedules, planning and preparing can help you choose the date and time that suits you best – not when the contractor has a free space in his schedule.

    Make sure that any spare gaskets or replacement tube bundles are ordered in plenty of time to arrive by your scheduled maintenance date. Without a predetermined date for planned maintenance, it’s all too easy to let this important task get pushed back. When this happens, your equipment is more likely to run into problems. Sooner or later, you’ll either have to shut down your operation yourself, or a piece of equipment will fail, and you’ll have to quickly schedule reactive maintenance. There’s no predicting if or when this will occur, and it may not always be in your favor.

    2. Inspect Your Equipment

    Excessive fouling is never a good thing for your heat exchanger. If not identified or addressed in a timely manner, it could result in several problems, including contaminated or unusable product, corrosion or leaks. Ethanol Producer Magazine pointed out that, in some cases, material buildup can become a fire hazard.

    To prevent these issues, it’s important to note when fouling begins to form and to remove it promptly. Check your tube bundles as well as the shell side for signs of material buildup or corrosion.

    3. Test your Heat Transfer Fluid

    Another area of concern is the heat transfer fluid. When using chemical-based HTFs, it’s inevitable that the material will eventually become degraded and less effective. When this happens, it can reduce the efficiency of the exchanger and, depending on the chosen fluid, can adhere to the surface of the tubes, become a more volatile solution or create a fire hazard, Processing Magazine reported.

    Regularly testing the HTF will tell operators where in the lifespan the fluid is. Take the fluid from several different places to get a more complete idea of how good the fluid still is. Additionally, be sure to test the fluid while it’s in operation; cooled HTF will display different properties than the HTF in action, making the reading of fluid from a shutdown machine a less informative sample. Additionally, shutting down a piece of equipment for the purpose of taking a sample will slow down operations, put undue stress on the equipment and HTF, and takes more time out of your workday.

    Test the fluid periodically; Processing Magazine noted that quarterly testing typically provides the best results.

    4. Collaborate with the Right People

    Shell and tube heat exchanger routine maintenance is no small task, so it’s important to include any and all relevant personnel in planning it. Work together to identify maintenance needs, a day that works best for the company and the right professionals to assist or carry out the job.

    “Approach your planned maintenance day with a checklist.”

    “The maintenance manager, the environmental health and safety coordinator, and I typically work together on scheduling and making sure we have the proper documentation, training records, etc.,” Tyler Edmundson, the plant manager at ethanol plant Mid-Missouri Energy, told Ethanol Producer Magazine. “Safety is the No. 1 priority – making sure contractors have proper credentials and understand our policies and expectations.”

    When you include people from different departments, such as your environmental health and safety team, you’ll be able to collaborate on smart decisions that are good for the company overall. Additionally, when you approach your planned maintenance day with a checklist, you’re more likely to have as productive a shutdown day as possible.

    Edmundson noted that working with different people to plan out the maintenance day also allows them to collect all the necessary documentation that any incoming professional would need to know. For example, Matt Werzyn, maintenance manager with Louis Dreyfus Commodities, Elkhorn Valley Ethanol LLC, told Ethanol Producer Magazine that he creates and sends an informational packet to any contractors that will work on their equipment. It includes the company’s safety rules and requests items from the contractor, like employee training records, to demonstrate their credentials. Then, after arriving on-site, but before they get their hands on the equipment, the team goes through a contractor orientation.

    Other information you may want to provide any contractor that will be working with your equipment is a maintenance log, documentation from the original equipment manufacturer or information about the products or fluids used in the equipment.

    5. Cleanup after your Heat Exchanger Routine Maintenance

    Depending on your cleaning method, there may still be necessary tasks to carry out once everything is all cleaned. Whether you used chemical or mechanical cleaners to remove fouling, there could be debris left over. This could contaminate your product if left unaddressed. Give your equipment a rinse to ensure there are no leftover chemicals or dirt.

    Your shell and tube heat exchanger is designed to be closed up tight most of the time. As such, opening it can sometimes cause damage to the gasket, Marine Insight explained. Be sure to double-check your gasket and gasket cover before wrapping up your heat exchanger maintenance. Make sure that you have spare gaskets on hand and replace them if necessary.

    Heat exchanger routine maintenance and cleaning can be a time-consuming task, but it’s not one that’s worth putting off. By being proactive, you can help your equipment perform more efficiently and last longer. When you have questions about proper care for your heat exchanger, need replacement parts, or when you’re ready for a replacement unit, reach out to the helpful heat exchanger experts at Enerquip. Clickhere to contact us today.

  5. Why you should consider mechanically cleaning your shell and tube heat exchanger

    Leave a Comment

    Sooner or later, your heat exchanger will foul. Over time, residue will build up on the walls of your tubes and diminish the heat transfer rate. Eventually, your heat exchanger will underperform and you’ll need to take action.

    While fouling is unavoidable, it can be addressed in a way that minimizes the impact. Heat exchanger performance must be closely watched so that dips in productivity are recognized right away. When efficiency begins to fall, the tubes need to be inspected for fouling, and cleaned in a timely manner.

    There are many ways to clean a shell and tube heat exchanger. Each has its own pros and cons, so it’s important to understand which method, or combination of methods, is best for your operation.

    Three common cleaning methods are hydroblasting, chemical cleaning and mechanical cleaning. Hydroblasting and chemical cleaning are highly effective and popular ways to clean shell and tube heat exchangers. However, they also come with disadvantages that operators can’t ignore.

    Problems with hydroblasting

    One of the most commonly turned-to methods for cleaning tubes is hydroblasting, according to Business & Industry Connection Magazine. Though this is an effective cleaning method, there are some downsides involved.

    “Mechanical cleaning can use 90 percent less water than hydroblasting.”

    Hydroblasting involves shooting jets of water into the tubes at as high a pressure as 40,000 psi. This high pressure can cause damage to the tubes, including tiny leaks that are difficult to detect. Additionally, if something should go wrong during cleaning, the water pressure can be highly dangerous to any employees nearby.

    Even though hydroblasting allows for multiple tubes to be cleaned at once, it is a time-consuming process. The exchanger often needs to be disassembled, and parts transported to an area more conducive to high-pressure cleaning than the operation floor. Additionally, getting a thorough clean can be difficult on the first pass, resulting in added time inspecting and re-cleaning parts of the exchanger.

    Finally, hydroblasting requires a large space in which the process can be conducted. Pumps and cleaning utensils, water trucks and a large team of people to operate all the equipment are all necessary to the process.

    Complications with chemical cleaners

    Some manufacturers use chemical cleaning systems to maintain their exchangers. While this method is effective, disposing of harmful chemicals properly can be an expensive endeavor, Jet News, the newsletter for the Waterjet Technology Association and Industrial & Municipal Cleaning Association, explained.

    “Chemical cleaning can pose an environmental health issue.”

    Additionally, chemical cleaning can pose an environmental health issue, wrote Hassan Al-Haj Ibrahim, a professor of petroleum refinery engineering at Al-Baath University in Syria.

    Dialing down the pressure

    Fortunately, there is a highly effective cleaning alternative to hydroblasting and chemical cleaning. Mechanical cleaning uses water at 700 psi or less, and doesn’t require the use of chemicals. Reduced water pressure allows for:

    • A smaller cleaning crew.
    • Cleaning to be done in place, without disassembling the exchanger, thereby also reducing the number of opportunities for equipment damage.
    • Reduced water use.
    • Lessened chance of injury on the jobsite.
    • Less expensive cleaning.

    Cost is usually the determining factor in deciding which cleaning method to use. While this may not always be the best judge of cleaning strategies, it definitely makes mechanical cleaning more attractive. Mechanical cleaning is less expensive than hydroblasting for several reasons.

    First, mechanical cleaning uses as much as 90 percent less water than hydroblasting. According to BIC Magazine, cleaning 21 heat exchangers produces:

    • 48,000 gallons of wastewater at 20,000 psi.
    • 5,000 gallons of water at 500 psi.

    This reduction in water is partially a result of lower water pressure, but also because mechanical cleaning systems allow the water to easily be turned off when not in use, while hydroblasting systems continue to shoot water 70 percent of the time they are being used. Lower water use will make the entire process less expensive.

    It’s not always clear which cleaning method is best for your operation. Unfortunately, there are instances when the wrong cleaning solution is chosen, resulting in a damaged heat exchanger or an incomplete cleaning job.

    To learn about the best way to maintain your shell and tube heat exchanger, reach out to the experts at Enerquip.

  6. Chemical cleaning and hydroblasting: 2 ways to clean your heat exchanger’s tubes

    Leave a Comment

    Shell and tube heat exchangers are an integral part of many industries. Though the oil and gas industry may be vastly different from the food and beverage industry, the two have at least one thing in common: the shell and tube heat exchangers that help prepare products for sale to consumers must be in top condition.

    When injecting fluid into a shell and tube heat exchanger, that which is more likely to corrode or foul is typically placed in the tube side of the machine, according to R. Shankar Subramanian, a chemical and bioengineering professor at Clarkson University. This is because it is easier to clean or, if needed, replace the tubes than the shell. However, the fact that liquid with a high fouling risk is put into the tube side of the exchanger, makes it crucial that machine operators and owners know how to clean and maintain their tubes.

    Shell and tube heat exchangers come in many sizes and configurations. Some are easier to clean than others, primarily because some have tube bundles and bonnets that can be easily removed from the shell side, while others’ are connected to the body of the exchanger. Knowing what type of bonnet your exchanger has and the appropriate cleaning mechanism are critical aspects to consider when purchasing the exchanger.

    There are many different ways to clean the tubes of a heat exchanger. Each has its advantages and its disadvantages. The important thing is to know which method is right for your particular machine and operation.

    Chemical cleaning

    Chemical cleaning is a good method to use for a fixed channel box design, which is generally more difficult to clean because the tubes cannot be separated from the shell. According to Clean-Co Systems, the process for chemical cleaning can be done in several ways. Chemicals can be circulated through the tubes or cascaded. Some are foam and others liquid. Chemicals will vary depending on the type of exchanger and what it is used for. Conoco Systems explained mild acids are typically used for this type of cleaning. It is beneficial to exchangers that have high amounts of buildup, as chemicals remove more deposit than most alternative cleaning methods.

    “Chemicals remove more deposit than most alternative cleaning methods.”

    However, there are several downsides to using chemicals, Conoco Systems explained. This method is one of the most expensive ones. Also, chances are, the tubes will have to be mechanically cleaned after the chemicals have done their work to remove any residual substances that could contaminate the next product batch inserted into the tubes. It is also time-consuming and a potential environmental hazard.

    Hydroblasting

    According to Goodway, hydroblasting has been a popular way to clean tubes for many years. This method uses high-pressure water systems to blast away any debris or deposits left in the tubes. NLB Corp. explained the water can be pressurized to as much as 40,000 psi.

    Hydroblasting can be done either manually or with an automated system. The manual approach involves an operator hooking a hose up to the tubes one by one and using a foot pedal to regulate the water. This method is effective and relatively inexpensive, though human error may result in uneven cleaning. There are also safety concerns regarding the speed and force at which the water comes out of the hose.

    There are two basic types of automated systems: flexible lance and rigid lance systems. Both allow multiple tubes to be cleaned at once, which saves on the amount of time spent cleaning. U-tube heat exchangers and others with curved tubes would benefit from a flexible lance system because it is easy to maneuver the hoses around the bends. For those exchangers with straight tubes, the rigid lance systems provide greater water pressure to remove debris and buildup.

    “Flexible lance systems can maneuver around U-shaped bends.”

    According to Conoco Systems, operators who choose to use hydroblasting as a cleaning method should also be aware that the pressure of the water could weaken the tubes and create leaks that may go unnoticed. Leaks in the tube side of the exchanger could result in cross contamination between the tube side and shell side fluids. Once discovered, it might even require more time spent offline to repair or replace the tubes.

    Chemical cleaning and hydroblasting are two popular ways to maintain the cleanliness of a heat exchanger’s tube side. Deciding which method will depend on the type of exchanger you have and what it is used for. Regardless of the configuration or use of your exchanger, though, it is crucial to ensure the tubes are kept clean to prevent fouling and contamination.

  7. Tight crude oil can cause fouling in shell and tube heat exchangers

    Leave a Comment

    MicroMarket Monitor released a report stating that much of the shell and tube heat exchanger industry in North America is fuelled by the chemical and petrochemical industries. According to the report, 28.8 percent of the market share of heat exchangers in 2014 went to the chemical industry. Heat exchangers are often used for oil refining and the shell and tube variety are the most commonly used.

    The American Institute of Chemical Engineers explained only four countries are currently extracting crude oil from shale formations: Argentina, China, Canada and the U.S. Crude oil from shale formations is more difficult to retrieve and hydraulic fracturing, or fracking, is the method by which it is extracted. The U.S. is the leading producer of this type of oil, commonly called tight oil.

    While customized shell and tube heat exchangers are great machines to use for processing, there are some things manufacturers and operators should be aware of. According to Emerson Process Management, the refining process is highly prone to fouling. Unexpected fouling is an especially harmful problem that is becoming more common among facilities refining light tight crude oil.

    “Crude oil fouling is one of the main causes of energy inefficiency in refineries.”

    Fouling can be harmful to a refinery because it causes lost production time, increased costs and, as a result, reduced profits. Unexpected fouling means operations need to cease production for cleaning. Plus, the fouling causes excess energy consumption and decreased throughput by the crude unit fired heater. According to a report from the Department of Chemical Engineering at the Imperial College London, crude oil fouling in pre-heat trains is one of the main causes of energy inefficiency in heat exchangers. Because of the strain it causes across multiple aspects of the refinery, the cost of crude oil fouling is high. Crude oil fouling was found to cost the U.S. approximately $1.2 billion a year.

    Asphaltene precipitation leads to accelerated fouling

    Different industries may see varying causes of fouling. In processing tight crude oil, fouling is commonly due to asphaltene precipitation buildup. This is primarily due to the blending of tight oil with other crude oil types. When tight oil alone goes into an exchanger, it tends to bottleneck in the naphtha processing and crude overhead units. This is because most refineries are designed to process oil of a specific composition, the AIChE explained. Blending them will reduce the risk of limiting the efficiency of processing units in the bottom of the barrel.

    While blending these types of oil is necessary to allow the machinery to operate correctly, this practice is also the one that contributes to asphaltene precipitation causing fouling. When incompatible crude types are blended, asphaltenes are not stable in the solution, resulting in the precipitate. AIChE noted that certain ratios of incompatible oils result in less precipitate than others. For instance, a blend of 20 percent tight oil with 80 percent of another type will create fewer asphaltenes than a 30-70 mixture.

    Tight oil also contains levels of naphtha that are higher than other types of crude oil, which can also contribute to the rapid production of asphaltene precipitation.

    Prevent fouling through monitoring

    To prevent fouling, manufacturers have inspected machines periodically and taken notes manually and recorded information in spreadsheets. While this has largely been effective in the past to respond appropriately to signs of fouling, increased production of tight crude oil, which fouls more quickly than most products, manual note-taking and periodic observation is no longer a practical form of prevention.

    “Traditional forms of fouling prevention are less effective with accelerated fouling.”

    Instead, Emerson Process Management suggested manufacturers use online capabilities to constantly monitor the state of exchangers’ performance. Wireless temperature and differential pressure measuring devices are one way to constantly monitor the performance and efficiency of a heat exchanger. By monitoring the health of the exchanger, refiners are able to carefully choose when to schedule a turnaround, rather than waiting until the fouling problem is no longer avoidable, leading to an unforeseen cleaning day. By being able to choose when to clean the tubes, refiners are able to calculate which day is best, so as to minimize the financial harm a day without production will cause.

    Not only will monitoring the condition of the equipment using online devices keep refiners current about potential fouling, but it can also aid in preparing maintenance staff of what is to come when it’s time for a turnaround. It can also help indicate if additional parts need to be purchased ahead of time. Some exchangers are equipped with a bypass, so cleaning can be done without losing a day of production. However, for those that don’t have this capability, as is often the case, advance knowledge of the kind of maintenance that should occur may reduce the time the turnaround takes and mitigate some unforeseen obstacles.

  8. How to prepare to clean a shell and tube heat exchanger

    Leave a Comment

    As most manufacturers who work with shell and tube heat exchangers know, fouling can be detrimental to an operation. It is crucial that all equipment that goes into processing a product is working at its optimal capacity. To ensure this, manufacturers and operators need to take the time to inspect and clean shell and tube heat exchangers.

    However, this is easier said than done. Cleaning a shell and tube heat exchanger is no easy task, especially for those with hard-to-access tubes. In addition to how difficult the process is, taking a day or two to inspect and clean your machines will result in lost production and therefore, lost revenue. It’s important to think about which day is best to minimize the losses incurred by scheduled maintenance. It is also crucial to plan it ahead of time, not only to account for the downtime, but also to plan out the turnaround schedule to ensure everything goes smoothly.

    “Taking a day to clean your machines will result in lost production.”

    Knowing when to clean

    In sanitary industries, like food, dairy and pharmaceutical, there are often well established protocols established for the timing of heat exchanger cleaning. These cleanings are most commonly accomplished through the use of an automated CIP (clean-in-place) system that will clean and sanitize the tubing without having to disconnect the piping or exchanger parts. These cleanings are often done daily, weekly of between batches of product.

    According to Conoco Systems and Conoco Consulting Corp., companies in more industrial settings can determine whether a maintenance day where machines would be offline is worthwhile by considering the hourly cost of the losses over time and the cost of fouling. Determining the right time for the loss to be at a minimum will tell manufacturers what the best cleaning intervals are.

    Chemical Processing explained that over the past half-century, companies have changed the way they view scheduled maintenance days. In the past, these cleanings took place one or more times a year. The years have brought equipment that is more reliable and requires fewer cleaning days. Today, the norm is closer to cleaning once every four to 10 years. Of course, this depends on the exchanger type and what it is being used for. Some materials that pass through an exchanger are less prone to fouling than others. For this reason, it is important that operators and manufacturers know the signs of fouling and the nature of the chemicals and products they work with.

    There are many advantages to going several years without a cleaning. The fact that cleanings are less necessary indicates the resiliency and efficiency of the exchanger. It also means there are fewer days during which the company loses profit due to ceased production. However, there are some downsides to this as well. Chemical Processing points out that since the last turnaround day may have happened as long as a decade ago, fewer operators and maintenance experts will be familiar with the process of cleaning and inspecting the machines. Because of this, it is important that all people involved in the cleaning day be properly educated and prepared for it.

    Getting prepared

    Chemical Processing advised people getting ready for a turnaround day to make a checklist of everything that needs to be completed on that day. This will help someone who is inexperienced or out of practice keep track of all necessary tasks. This list should include recording how the machine is operating just before you shut it down, whether all the measuring tools available make sense or if others would be best, layout dimensions for the machine and all its parts, and whether there is any damage or other factors that could cause harm to the product or machine later on. It is also important to have any replaceable spare parts on hand, like gaskets, O-rings and hardware, so that any damaged or compressed parts can be replaced before the unit is re-connected and brought back on line. Because exchanger parts can be very heavy, it is also important to have a safe lifting plan with adequate clearance to remove bonnets, piping and other parts in order to gain access to the tube bundle.

    How to clean

    If the company will allow photography of the equipment, it’s a good idea to take pictures of everything mentioned in the notes taken throughout the day. This will help explain any damage encountered and provide reference for the notes the person performing the turnaround takes.

    Conoco Systems explained there are many ways to clean a shell and tube heat exchanger, though most require being offline. The most widely chosen method is mechanical cleaning. This involves determining what kind of deposits you will be removing from the tubes. Deposits range from small amounts of silt to substances that are more difficult to remove, depending on the materials that are used in the exchanger. Once this is determined, decide which cleaning method is appropriate. Some common examples include brushes, used for lighter debris; calcite cleaners, used to remove stubborn calcite deposits which couldn’t be removed with acid; and metal tube cleaners, used for harder deposits.

    Hydroblasting has also been commonly used, though precautions to reduce risk of injury or tube damage must be taken if managers choose to go with this option. Good Way explained this method involves water pressurized to 10,000 to 25,000 pounds per square inch, which is then blasted through the tubes to remove deposits.

    Chemical cleaning is another preferred method, though it is a more expensive option, Conoco Systems explained. Chemicals that are mildly acidic will take off debris faster and more efficiently than a mechanical process. However, the tubes will still need to be cleaned of the chemicals used to prevent contamination or environmental hazards.

  9. Maintaining your shell and tube heat exchanger

    Leave a Comment

    Your shell and tube heat exchanger could be one of the most important pieces of equipment in your business. In the food, beverage and dairy industries, a heat exchanger will protect customers from contaminated products. The pharmaceutical industry relies on heat exchangers to ensure medicines are top quality.

    If a heat exchanger fails, product is contaminated and lost. This could decrease productivity, and in some cases, could result in a reputation-damaging recall. To prevent failure, it is critical that the heat exchanger is reviewed and serviced regularly. Chemical Engineering Magazine explained that, without proper maintenance, heat exchangers are prone to corrosion and fouling, which could lead to leaks. This will cause the product to mix with the cooling or heating fluid and ruin the batch. Corrosion and other deposits collecting on the floor of the exchanger will decrease the efficiency of the exchanger. This could prevent the liquid from reaching the desired temperature.

    “If a heat exchanger fails, product is lost or contaminated.”

    Corrosion leads to bigger problems

    A shell and tube heat exchanger is a machine that is expected to have to be repaired or replaced eventually. The nature of its use will wear on it and eventually, corrosion will occur. The goal is to keep the exchanger in operation as long as possible. According to MTS Systems Corporation, a heat exchanger could last up to 20 years with the right maintenance. This includes careful, regular inspections of the machine and all its parts.

    MTS said it is important to make sure the heat exchanger is sanitary from the beginning of its life to the end. Before the first use, be sure to look it over thoroughly to make sure everything is secured properly and the tubes and shell have not been contaminated by dirt, dust or other foreign substances.

    Corrosion is a process that occurs over time regardless of proper maintenance schedules. It is the result of chemical reactions in or around the heat exchanger. Different metals will react with different substances differently. Stainless steel is a good material to use in exchangers when the substances used within could be harmful to other metals, such as copper alloys. According to the Stainless Steel Information Center, the material can resist corrosion from most acidic, alkaline and chlorinated substances when it is a high-alloy grade. However, the British Stainless Steel Corporation explained that while the metal is highly resistant to corrosion, it will begin to wear over time.

    “Stainless steel is resistant to corrosion from many substances.”

    Water monitoring

    MTS explained the best way to prevent corrosion is to make sure only the best substances for the exchanger’s material makeup enter the machine. Using the correct chemicals to treat and clean the tubes is essential. This information should be obtained before you begin using your heat exchanger to ensure you are prepared for its maintenance from the get-go.

    Many heat exchangers use water as the heat transfer liquid. Tap water is generally of an acceptable quality to use in the machine. However, it is important to double check the water before putting it into the exchanger. The pH should be neutral and the water shouldn’t be polluted or have any bacteria or other contaminates in it. If the water comes from a natural source, is should be treated before entering the tubes.

    If the water isn’t treated or inspected before entering the exchanger, debris could enter the machine and block the chambers. To prevent this from happening, screens or filters can be installed to keep particles out. If they do enter, they will wear against the tubes and cause corrosion.

    Monitoring the health of your heat exchanger will help to identify early signs of failure before fouling or contamination become a larger issue. MTS explained that checking on the water quality is a good way to see if failure is a risk or is already happening. Cloudy water indicates the fluid is no longer pure. Taking notes on temperature and pressure changes will reveal problems beginning to form. Reduced efficiency could be a sign of scaling, a solid precipitate resulting from chemical reactions. Scale build-up will lead to fouling and corrosion over time. Checking other aspects of the exchanger, such as tube thickness, will also give indications of emerging problems.

    If you find that you need to replace all or part of your heat exchanger, contact the helpful heat exchanger experts at Enerquip who specialize in designing custom shell and tube heat exchangers, and drop-in replacement exchangers.

  10. 5 Tips to Prevent Food Processing Contamination

    Leave a Comment

    Editor’s Note: This content was last updated 3/14/24.

    Food processing plants must adhere to stringent standards in handling food products to ensure consumer safety. Various factors, including airborne debris and facility moisture, can lead to the formation of harmful bacteria, ultimately impacting the quality of the end product.

    To prevent contamination and cross-contamination in processing facilities, here are five essential tips for maintaining food safety:

    1. Keep ramps and carts clean

    Sanitation is paramount in ensuring the safety of a food processing facility. It’s crucial to thoroughly clean and dry ramps used for moving carts containing organic and non-organic products. This extends to carts and rampways accessing freezers, as bacteria can remain dormant when food is frozen, necessitating cleaning to eliminate potential bacterial growth.

    2. Color code brushes and buckets

    To minimize cross-contamination, use color-coded brushes and buckets in food processing facilities. Assign specific colors for cleaning pasteurized food contact surfaces, non-food contact surfaces, surfaces with raw milk products, and floor drains, ensuring consistency across different areas of the plant.

    3. Clean all equipment and machinery

    Regular cleaning of all equipment and machinery is essential to prevent contamination. This includes refrigeration equipment, HVAC systems, contact surfaces, drains, and heat exchangers. Stainless steel equipment is particularly effective in preventing bacterial contamination due to its durability and ease of cleaning.

    4. Ensure workers are healthy

    Maintaining the health of workers is crucial in preventing contamination during food handling. Employees should not work while sick or exhibiting symptoms such as vomiting, diarrhea, sore throat, or fever. Proper hygiene practices, including frequent handwashing and wearing clean clothing, further reduce the risk of contamination.

    5. Heat products with appropriate equipment

    Proper heating of food products is essential in preventing contamination issues. Utilizing the appropriate shell and tube heat exchanger is crucial to achieving the required temperature to eliminate bacteria effectively. Factors such as product type, heating requirements, and production volume should be considered when selecting the appropriate equipment, necessitating consultation with a heat exchanger professional for optimal results.

     

    More from the Enerquip Blog