Heat Exchanger Cleaning Equipment

Heat exchangers are at the heart of so many industrial processes that they are often forgotten and taken for granted. Heat exchangers have a long lifespan, so it is a gradual process of losing efficiency. Since this decline is such a long and slow process, it’s rarely even noticed that the heat exchanger is headed toward failure. Until something goes wrong. When something goes wrong with the heat exchanger, it goes really wrong, and it is urgent to remedy the situation immediately.

Heat exchangers often go so long without being properly cleaned and maintained that by the time there is a heat exchanger cleaning, the original specs and records have been lost or misplaced. This creates an additional problem, because without the original specs, no one knows what kind of performance the heat exchanger is supposed to have.

Once the heat exchanger finally is opened up for cleaning, it’s common to find that it has become so fouled that the heat exchanger cleaning takes significantly longer than it would have if it had been regularly maintained and cleaned. Ultimately, the lack of regular maintenance and cleaning results in a higher cost, longer cleaning duration, and greater loss of production.

This might sound like some sort of a rare, worst case scenario, but it’s entirely routine for the specialis cleaning companies. When cleaning is done, it’s often done without any real knowledge of what kind of performance benefit there will be, and how long this increased efficiency will last.

One of the most used heat exchanger configurations in industrial use is the straight of hairpin shell-and-tube-exchanger. This has bundles of hundreds or thousands of small-bore tubes. Even a moderate amount of scaling can take considerable cleaning and effort to return the heat exchanger back to optimal performance. If the outside of the bundle has heavy scaling, it’s exponentially more difficult to adequately clean the heat exchanger.

Advancements in design would be able to make heat exchanger cleaning faster, safer, and result in better waste containment. This would result in less time spent offline, and better performance.

Currently, heat exchangers are generally designed to have the capacity to operate even when they are significanly fouled. They are designed to operate with about 30% or 40% excess capacity. This is what industrial facilities want. They prioritize continued functionality over ease of maintenance and cleaning. Heat exchangers are designed and installed to use one of 3 methods of cleaning: mechanical, chemical, or pressure-jetting. This has been the standard for over 50 years.

Refineries, like other industries, use a 21 say shutdown process during which maintenance, including heat exchanger cleaning is done. This is the way it has been done for decades. Industry continues to use the same methods for heat exchanger cleaning that it has always used. The primary method is pressure washing with water.

It’s normal for a company to have their heat exchangers designed to continue running, even if not at optimal performance, instead of having them designed for efficiency, or ease of cleaning. This could require more frequent cleaning, but it would be easier, safer, and more cost effective, resulting in a more efficiently performing heat exchanger. BP (British Petroleum) was able to cut cleaning time of a shell and tube heat exchanger down to 3 hours by changing their heat exchanger cleaning method. Prior to that, cleaning would take 3 days.

If a company designs their heat exchangers for ease of cleaning and maintenance, the plant can remain at near full production capacity throughout the duration of the cleaning process. Banks of heat exchangers can be taken offline, while the rest remain on line. Heat exchangers designed to allow the header to be removed allows for heat exchanger cleaning with alternate methods to the usual high pressure water jet. This can cut heat exchanger cleaning time down to just a few hours, instead of a few days.

More frequent cleaning can also reduce the occurrence of heat exchanger fouling, and also minimizes the amount of time that the tubes are exposed to open air during cleaning. This results in a reduction of corrosion of the heat exchanger tubes.

Cleaner, smoother heat exchanger surfaces allow for more efficient heat transfer. When fouling does occur, it is easier and less time consuming to do the heat exchanger cleaning, and also allows for a wider variety of cleaning methods.

Generally, plants have heat exchanger cleaning intervals of 3 or 4 years. Unfortunately, spreading out the time period between cleanings winds up with a greater cost, not a lesser one. In the short term, it seems like a good idea to stay fully operational, but when the time for maintenance finally does come, down time, lost productivity, and cost is significantly higher than the shorter down times of a quicker maintenance schedule would be. Long maintenance schedules result in a much bigger job.

Big picture thinking, and better design can ultimately be a huge advantage in minimizing the cost of heat exchanger cleaning.

There are many kinds of heat exchangers, but for this article, we will be referring to the heat exchanger in your furnace.

The part of your furnace that heats up is the heat exchanger. As the air or water that carries heat through your home passes the heat exchanger, it heats up. The forced air, or water carries itself throughout your home and keeps it warm. On the inside of the heat exchanger, the combustion process occurs. To the outside of the heat exchanger wall, water or air passes by and get warmed as it then distributes to the rest of your home.

Since the combustion process happens inside the heat exchanger, there are many toxic gases contained inside the walls. Carbon Monoxide is one of these deadly gases. If the heat exchanger becomes cracked or warped, these gases can escape from the inside, and get into the ventilation system, or simply permeate throughout your home. Carbon Monoxide is both deadly and odorless, so you won’t be aware of carbon monoxide poisoning from noticing a funny smell. You will notice the effects, however. Some of the symptoms are nausea, dizzyness, and other flu like symptoms. You need to catch carbon monoxide poisoning early, or you will die, so a good carbon monoxide detector is inexpensive and well worth the cost.

Many modern furnaces have a lifespan of about 15 years, however, poor maintenance is sure to shorten this time frame. Rust can form in the heat exchanger if condensate from the evaporator seeps in. Dust and dirt can form on the high limit switch. This will cause the furnace to switch off and on more frequently. Dirty furnace filters can reduce air flow, and cause your heat exchanger to run too hot. This will also cause the furnace to switch off and on more often. Dirty burners will decrease the flame efficiency, and lead to a build up of soot on the heat exchanger. Any of these conditions will reduce the lifespan of your heat exchanger, and make it more prone to cracking or warping.

Yearly servicing of your furnace is the best defense against these conditions that reduce the lifespan of your furnace. Have a certified Heating Ventilation and Air Conditioning (HVAC) technician check your unit prior to the heating season each year. A certified HVAC technician will know what to look for in inspecting your furnace, and can tell if there will soon be a problem with your heat exchanger.

If your furnace is over 10 years old, it is especially important to have annual checks of the health and safety of your unit. The heat exchanger is made of metal, and it expands as it heats up. When the furnace shuts off, the metal cools and contracts. This happens each and every time the furnace turns on, and back off. Over the course of years, this amounts to thousands of times that your heat exchanger is expanding and contracting. At some point, the metal can no longer take the stress of continued expanding and contracting, and the heat exchanger walls crack, or warp. If this happens, there is the danger of Carbon Monoxide poisoning mentioned earlier. This is most certainly no laughing matter. Keeping your furnace properly maintained can be the best plan for a long life, for both you and your furnace.

With just a few simple steps, you can keep your heat exchanger and furnace running at optimal performance. The heat exchanger is the part of your furnace that transfers heat from the heat source in your furnace, to the air or water, which is then distributed throughout the house.

Your furnace burns gas, natural gas, or oil, or runs on electricity, which then produces heat. The heat exchanger is the containment system for this heat source. As the air or water flows past the heat exchanger, the air or water heats up, just like putting a pot of water on a stove. In essence, the heat exchanger is the heart of your furnace. In most furnaces, the heat exchanger is hidden from view.

In a gasoline furnace you would find:

• Solid state furnace control – This is an electrical component which has a fan assembly. you can find it in the rear of your furnace.
• Draft inducer – This uses a fan to force air through.
• Igniter and flame sensor
• Gas valve, manifold, gas burners

Surrounding all these components is the heat exchanger. Then the furnace filters, and other air filters. Some of the components may vary a bit, depending on the exact type of furnace you have, but this is the basic diagram of a home heating system.

Usually, a heat exchanger will fail because of warping or cracking of the metal walls of the heat exchanger. When the furnace runs, the metal expands, and during off cycles, the metal contracts. As your furnace runs on and off, the heat exchanger expands and contracts over and over. Eventually, this repeated expanding and contracting can result in failure of the integrity of the metal walls of the heat exchanger.

When the heat exchanger warps or cracks, it can lead to an escape of toxic exhaust gases, including carbon monoxide (CO). Most heat exchangers can last a very long time. With proper maintenance of your home heating system, it can even last longer than the average life expectancy. In fact, regular cleaning and maintenance can be the primary factor in the life span of a heat exchanger.

Reduced airflow can also be a major factor in premature failure of a heat exchanger. Dirty furnace filters are the most common cause of impaired air flow. Also contributing are obstructions and dirt in the air vent or duct work, dirty fan blade, and dirty, worn fan motors. All these factors will reduce the efficiency and lifespan of the heat exchanger.

When airflow is reduced, the heat exchanger, and other components can overheat. Most heating systems will have a preset limit switch that will cause the unit to shut off if it gets too hot, but if it is operating outside the optimal parameters, it can still lead to additional strain and metal fatigue of the heat exchanger.

The best way to maximize the lifespan of your heat exchanger is to inspect it every year prior to the heating season. Monthly cleaning of your furnace filters is also recommended. Always use a qualified service technician to inspect your furnace. The cost is reasonable and affordable, especially compared to the cost of allowing your heat exchanger to fail. Carbon Monoxide detectors are also a valuable and inexpensive precaution to indicate carbon Monoxide leaks.

Always refer to manuals, manufacturer specifications, and use the proper heat exchanger cleaning equipment.