Immersion Heaters – Whitepaper

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Knowing how to properly heat a solution or other liquid is critical to the integrity of the liquid. The right method can save time, energy and money. Using an inadequate approach to the task of heating a full tank of solution can have consequences ranging from damaged equipment to increased energy costs.

In many cases, heating a solution quickly and accurately is essential. The fluid may need to be raised to a specific temperature and kept at that temperature consistently. Sacrificing accuracy can result in overheating and coking.

There are many ways to heat mass quantities of liquid. Band heaters can be installed around a pipe or tank. Wrap-around heaters can surround a vat. Fluids can be placed in a separate heating vessel. However, each of these options has a drawback. Band and wrap-around heaters aren’t energy efficient. Band heaters can lose up to 40 percent of their wattage input because they aren’t fully in contact with the solution being heated. Instead, a portion of the heater is facing outward, away from the solution and its vessel.

Other indirect methods, such as using a heated tank or wraparound heaters, take longer to heat up the solution, since the heat-transfer method needs to reach the desired temperature before the liquid can. Heating vessels can also take up floor space, a precious commodity many manufacturers and equipment operators appreciate having. This is also an expensive option, as a new, large piece of equipment will have to be purchased.

Benefits of Immersion Heaters

An alternative option to these choices is the immersion heater. These devices come in many shapes, sizes and styles. However, each is advantageous to the manufacturer who wants to effectively heat liquids.

Buying the proper equipment to heat and process fluids is an essential part of following best practices and keeping standards high. However, it is also one of the more costly aspects of the industry. It is important to keep costs down whenever possible while maintaining quality and quantity.

 Energy efficiency has become a concern for many industries in the past few years. Not only does cutting energy mean reduced operational costs, but it is also better for the environment. Both of these concerns – cost and energy efficiency – are addressed with immersion heaters.

Immersion heaters impact the solution or fluid from all sides. There is no wasted energy because the heating element is actually submerged in the liquid being heated. This allows the heater to operate more efficiently.

The heaters’ design also saves space on the production floor. Since the element is placed directly into the vessel holding the liquid, no extra space is used. This makes room for additional necessary equipment or creates more space for equipment operators to work.

Some versions of immersion heaters also make the cleaning process easier than if larger equipment were used. Over-the-side heaters, typically used when a tank is not outfitted with the required hardware for a bayonet or U-tube heater, are easily taken off the tank. The tank or the heater can then be cleaned and replaced. If the heater needs to be cleaned, this can be done without first emptying the tank, which saves time and resources.

Types of Immersion Heaters

Immersion heaters come in various shapes, sizes and styles. Each of them provides the same benefit of heating the fluid from within, saving on energy expenses and creating a more thorough, even heat distribution. They also provide efficient heating and cooling to liquids when needed.

An immersion heater, often referred to as a bayonet heater, is inserted into the tank from the side.  Therefore, it is in direct contact with the fluid being heated. It is held in place by attaching to a flange connection on the side of the tank. Bayonet heaters are comprised of a tube or group of tubes stabilized with support baffles, with the entire assembly sometimes cradled by foot supports inside the tank.  In most cases, u-tubes are used, as they can readily expand and contract and won’t be damaged by rapid heating or cooling.  Typically, a bayonet heater is used to heat extremely large quantities of liquid.

Bayonet heaters require the tank to accommodate their installation using flanged or threaded ports. In a flanged design, the tank has a flanged port installed on the side of the tank, and the heater has a matching flange to allow for installation and proper sealing.   A screw-plug design can also be used for smaller heaters, with these being attached through a threaded opening in the tank.

When the tank does not have a connection for a bayonet heater, an over-the-side immersion heater is able to do the job. These heaters are installed at the top of the tank, rather than the side. The heating element then rests along the side or bottom of the tank.

Regardless of which style of heater is used, it is usually stationed near the bottom, while being installed high enough to avoid the sludge and buildup that collects on the tank’s floor.

Immersion heaters can be fabricated in many different metals and alloys, such as copper, steel, cast iron or titanium. Stainless steel is one of the most popular materials used for immersion heaters. According to The Stainless Steel Information Center, the material is a cost-effective option when considering the lifespan of the equipment. Stainless steel is resistant to corrosion and scaling in a multitude of environments. This makes it ideal for use with chemicals, acids and alkaline solutions, as well as in extreme hot or cold temperatures. It is easy to clean and maintain. Manufacturers appreciate this quality, as it is extremely important that all equipment used in the processing of a product is sterile to avoid contamination.

Because stainless steel is more resistant to corrosion and scaling than its counterparts used in making immersion heaters – and because of its hygienic nature – stainless steel has a longer life span, with relatively low maintenance costs.

TEMA and ASME Certified

Users need to know the equipment they are purchasing is of the highest quality. Purchasing and subsequently using equipment that isn’t up to standard can lead to distributing defective products or decreased effectiveness. The Tubular Exchanger Manufacturers Association (TEMA) has the knowledge and understanding of how excellent equipment is made, and has developed a standard for design and manufacture of tubular exchangers.  So, when users purchase equipment from manufacturers who build to the TEMA Standard, they know they are buying quality machinery that meets or surpasses their requirements.

The American Society of Mechanical Engineers (ASME) brings together engineers from many different disciplines and helps inspire collaboration and research. ASME helps to advance the industry and ensure quality in the work that its members do. For more than a century, ASME has been creating standards to which mechanical engineers must strive to adhere. Today, engineers volunteer to review and improve product requirements to guarantee equipment and practices will result in products safe for consumer use.

When an immersion heater is built to the TEMA Standard and ASME Code, users know the product was created with the highest standards in mind. Users can trust equipment with these

Enerquip’s Immersion Heaters

Enerquip has been providing stainless steel shell and tube heat exchangers to companies in the sanitary and industrial markets, as well as the U.S. military, for more than 40 years. Its line of U-tube immersion heaters is a natural extension of the company’s current product base. The immersion heaters are made according to the standards of both TEMA and ASME. They are made of stainless steel to ensure product quality and safety.