Last updated on August 4th, 2020 at 01:16 pm

Industrial Heaters, or Process Heaters, as they are commonly referred to, are used to make a wide variety of processes more efficient across a large range of industries including the water purification, medical, aerospace, injection molding, textile, food service, packaging, paper making, automotive, among many, many other manufacturing sectors. There are several different ways in which these heaters contribute to the overall production of companies working within these industries. The most dominant role these heaters play is in heating chemicals as a component of the production process. It’s the introduction of electricity to this process that provides the energy necessary for the heating elements to desired temperatures. Which allows them to carry out a number of different processes within these industries.

The seamless and reliable conduction of heat, among other reasons, make immersion heaters a particularly effective option those looking to improve the quality of production within the pulp and paper industry as well.  

Understanding How Electric Process Heaters Compare to Other Heater Types

Different electric types of electric heaters that are used across a number of different industries. The flanged immersion or circulation type are perhaps the most widely used as a method for heating tanks. To understand how they work; when idle, the elements of the immersion heater remain within the heating tank while submerged within a process fluid until its desired temperature is reached through a natural process of convection.

With respect to the circulation types of these heaters, the heating process differs from that of the immersion heater in that its heating element reaches desired temperatures through a process that involves immersing its element into a vessel containing the process fluids. In doing so, those fluids are forcibly heated via convection as opposed to being done so naturally, resulting in the reverse of what happens with an immersion heater.  

The Uses of Electric Process Heaters in the Pulp & Paper Industry

Perhaps one of the most popular uses of immersion heaters is in completing work processes within the pulp industry. In paper mills, using other types of heaters can adversely impact the quality of the final work due to variations in temperature, which in turn leads to expansion and contraction of the calendar roll.

Particularly when housed in areas known to have harsher winter climates, presses that are subjected to fluctuations in temperatures can be exposed to more pronounced quality control issues than those living in more moderate climates, creating less reliable results. Electric heaters are much more effective regulating temperature necessary to ensure more streamlined outputs, especially when equipped with onboard thermostats.  

Heating Biomass

One use of immersion heaters within the pulp and paper industry centers around the heating of the pulp biomass in a way that is necessary to move forward in the calendaring process. In this case, the immersion heater’s heating element, which has previously been encapsulted by some other heavy duty alloy, is placed into water or another liquid to begin the heating process. Its internal heat sensor sounds an alarm once the tank reaches its desired temperature. With a wattage rating of up to 2,000 kW and functionality adapted to a three-phase process, the heating process is relatively fast. While this is the case, the build up of scale, also known as calcium carbonate, can greatly impact the boiling efficiency of the heater, especially when biomass residue is added to the mix.

Speaking of which, within the pulp and paper industry, boiled biomass residue can accumulate with typical scaling expected, breaking off and settling at the base of the tanks greatly reducing not only capacity, effectiveness as regular maintenance is delayed. To better understand the impact of irregular maintenance, watt density of a limestone and pulp residue filled unit will fall at around 40 W/in2, but in a properly maintained unit, can be as high as 60 W/in2.  

Improved Paper Calendaring

Within the pulp and paper industry, immersion heating is utilized as a way to improve the overall paper calendering process. Among the many inconsistencies in production found in situations where other heating systems are used in lieu of immersion heaters, issues abound including:

• Unequally distributed or streaking of moisture content among calender rolls
• Uneven distribution of heat across heating elements and rollers resulting in an inconsistent finishing
• Difficulties in transitioning from power up to production and utilizing caliper controls

The deployment of immersion heaters is a particularly effective solution for many of these problems, especially as far as the more technical aspects are concerned to include:

• Reducing the incidence of streaking and buildup of high levels of moisture when calendaring and overall waste while improving finishing
• Reducing energy use by up to 95%
• Improving production speed as well as caliper control

How Immersion Heaters Improve Production Across the Board

Of the many reasons these heaters have such varied appeal, perhaps the one reason that comes the forefront is the sheer number of different solids, liquids or gasses that they are capable of heating. Among the many different types of matter these heaters and their heating elements can accommodate, there is: air, ammonia, petrochemicals, fuel oils or gases, water, or nitrogen.  

Once in operation, these fluids enter from the application end of the tank and pass through the respective heating element before being pushed out the other end of the tank where the heating occurs. This transfer process is known as radiant or convective heat transfer.  

How Immersion Heaters Improve Productivity within the Pulp Industry

No matter what the size of the plant, critical to the operations of the pulp and paper industry are having efficient heaters that are capable of handling the sheer volume of work that is demanded of them to produce. Across the different aforementioned industries, there are a number of environmental and preference factors which will affect how the heating unit performs its desired task.