Skip to Content
Exit

Category Archive: Heat Exchanger Cleaning

Tag Archive: Heat Exchanger Cleaning

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Preserving ethanol equipment with faster cleanups

    Leave a Comment

    Prepare for plant downtime

    Ethanol processing plants must ensure their equipment can withstand months of products running through shell and tube heat exchangers. This process builds up dirt and grime on the equipment, which must be cleaned periodically. According to Ethanol Producer Magazine, facilities have to prepare for cleanings in advance to ensure downtime for the process is limited.

    Matt Werzyn, maintenance manager for Louis Dreyfus Commodities, Elkhorn Valley Ethanol LLC, explained that ethanol processing facilities must ensure they schedule downtime for the cleaning process, the source reported. The plant managers must follow through with the deep cleanse; otherwise, the facilities will see downtime from grime and dirt buildup.

    The cleaning process must be quick and simple. If there are too many steps, the plant could be shut down for multiple days for repairs and equipment maintenance. In addition, certain metals and alloys tend to corrode over time, Engineer’s Edge reported. Finally, some of the chemicals and gases used with heat exchangers in ethanol processing plants can damage the metal.

    That’s why investing in stainless steel shell and tube heat exchangers is essential. According to the source, stainless steel is much easier to clean and can withstand multiple cleanings.

    Carbon steel is typically used in manufacturing plants but has a somewhat weak passivity, leading to rusting and corrosion. However, stainless steel contains additional alloy elements that increase corrosion resistance and provide more strength over time. This can deliver a quicker return on investment for processing facilities that frequently replace heat exchangers.

    Fouled equipment slows plants down

    Werzyn added that once equipment becomes fouled or dirtier, there are other consequences for plant operation, Ethanol Producer Magazine reported.

    “As we get closer to shut down, there is a definite performance decrease and an increase in the required energies needed to run the process,” said Werzyn. “If duct lines are not cleaned over a long period of time, duct fires can result, which can be very expensive, if not destructive, if they occur.”

    Equipment needs regular cleaning to last and perform required duties at its highest level. Werzyn said keeping equipment continuously clean could help save a lot of money in the grand scheme of things, the source stated.

    Need a stainless heat exchanger solution? Reach out to an Enerquip Sales Engineer today.

    More from the Enerquip Blog

    This post was last updated 1/22/24.

  7. Poultry liquid a major cause of campylobacter outbreaks in processing plants

    Leave a Comment

    One of the biggest concerns for food processing plants is battling bacteria on equipment and other surfaces. According to a recent study by the Institute of Food Research, liquids from chicken carcasses in poultry products can lead to a persistent increase in campylobacter.

    Campylobacter is a common bacteria found in raw or undercooked poultry meat or cross-contamination items, the U.S. Center for Disease Control reported. Annually, the bacterium affects more than 1.5 million people, and food processing plants work diligently to protect consumers from the illness.

    Helen Brown, lead on the IFR study, said these infectious liquids are often collected through defrosting stages for chicken carcasses. The bacteria can attach to glass, polystyrene and stainless steel to form biofilms and threaten work environments.

    “We have discovered that this increase in biofilm formation was due to chicken juice coating the surfaces we used with a protein-rich film,” said Brown, according to the report. “This film then makes it much easier for the campylobacter bacteria to attach to the surface, and it provides them with an additional rich food source.”

    Easy-to-clean equipment is essential

    Campylobacter are not necessarily long-lasting or tough bacteria, but they are often protected by a thin coating that keeps them alive. According to the IFR report, the bacteria stay alive since they are more resistant to disinfection treatments and antimicrobials.

    Food processing plants need proper equipment so bacteria can be easily killed off at the right temperature.

    Shell and tube heat exchangers provide food processing facilities with equipment that can heat products enough to eliminate the appropriate bacteria, and the stainless steel forged equipment makes the cleaning process easier.

    The ability to clean massive equipment in food processing facilities remains one of the most important ways to eliminate cases of campylobacter.

    “This study highlights the importance of thorough cleaning of food preparation surfaces to limit the potential of bacteria to form biofilms,” Brown said in the IFR report.

    With more attention on preventing food-based bacterium outbreaks in processing facilities, the IFR hopes the additional insight will prevent more cases since many locations are prone to these illnesses. Supermarket shelves, deli or meat areas, food processing facilities, and poultry delivery areas can spread the bacteria or cross-contaminate other products if the meat is not handled correctly.

    Want to talk through your thermal processing needs? Meet Enerquip’s Sales Engineers.

    More from the Enerquip Blog

    This post was last updated 1/22/24.