How did people heat the water before the invention of pots, tanks, electricity, and controlled natural gas? They would heat a heavy stone in a fire and roll it into a pit lined with animal skins. That hot stone would quickly transfer heat to the water. This method is the world’s first immersion heater.
Today, many liquids other than water require constant heat to maintain a set viscosity, accelerate the fermentation, or prevent freezing. Since rolling hot stones into a tank filled with 16 million gallons of crude oil are “impractical,” engineers have come up with better solutions.
In this blog article, we’ll explore the history of industrial tank heaters and discuss how they have changed over the years.
What are Industrial Tank Heaters?
Industrial tank heaters are devices used to heat liquids in large tanks and vessels. They mostly install through the tank’s wall with the heating element protruding inside. Tank heaters use electricity or circulate steam or heated oil to transfer heat. Tank heaters come in various sizes and can be used to heat different types of liquids in almost every industry, from petrochemicals to food and beverage.
Industrial tank heaters evolved as a solution to the problem of not having a reliable source of hot water on demand.
A Brief History of Hot Water Heaters
Norwegian inventor, Edwin Ruud, patented the first water heater in 1890 while working for George Westinghouse in Pittsburgh, Pennsylvania. Like most tank water heaters today, it consisted of a water tank and gas burners below to provide the heat. It incorporated a thermostat to maintain the temperature and automatically turn the gas on and off.
In 1897, Ruud patented the “Ruud Instantaneous Automatic Water Heater” and started the company with his name, which is still in business today. The design did not use a tank. Instead, copper coils circulated water inside a cast iron shell. Thermostatically controlled gas burners provided heat, creating hot water on demand.
It wasn’t until after World War II that the first electric water heater became available. Herbert Lindahl, Sr. initially manufactured coal and wood-burning stoves in his garage in Nashville, Tennessee. He founded the State Water Heaters company in 1946 and began producing them for commercial and residential use. His electric water heaters revolutionized the water heating industry.
How Did Antique Water Heaters Work?
Early water heaters worked much as they do now, and they either had a tank or were tankless heaters. The heat source was a gas flame or coal fire. The fire warmed the tank wall, conducting heat to the water inside. Alternatively, the water ran inside a coil of tubing hung inside the flue. The tubing absorbed the heat from the hot gases rising through the stack.
The first industrial water tank heaters were boilers called Fire Tubes. Scottish engineer Sir William Fairbairn invented the Lancashire boiler in 1844. His design would lead to innovations such as marine and locomotive steam engines.
The boiler was a large iron cylinder. At one end would be a firebox. In the middle would be a series of hollow tubes that ran through a water tank. The tubes allowed the hot combustion gas to flow through and exit the chimney or smokestack while transferring heat to the surrounding water. The hot water or steam circulated inside a building’s piping or harnessed as a power source like a locomotive engine.
The immersion-fired boiler was the next step in the evolution of large water tank heaters. The immersion-fired boiler injects premixed air and natural gas under pressure inside the tubes. The radiant heat transfers from the flame to the inside surface of the fire tube. Conductive heat transfer occurs from the metal tube to the fluid surrounding it. It’s far more efficient than a fire that draws air and circulates at ambient pressure.
It’s still in use as one of the methods of heating water and other liquids in tanks.
Four Types of Water Heaters
Industrial water heaters are a crucial part of many industrial processes. There are four types based on the fuel used to create the heat.
- Electric water heater – This type heats the water quickly and efficiently when other fuels are unavailable.
- Gas water heater – Natural gas or propane can be more cost-effective than electric when heating large amounts of water. However, installation and maintenance can be more complex.
- Steam water heater – Steam is the primary heat source for this type. It requires a more complicated installation process.
- The Heat Pump – Heat pumps are recent industrial heating solutions. They reuse surplus heat from industrial processes or wind power. Reusing the process energy for space heating and hot water is sustainable and cuts energy costs.
There are other liquids besides water that require storage and heating. Engineers began solving petroleum storage, heating, and movement in the 1860s.
The Rise of Bulk Storage Tanks and Immersion Heaters
The first cylindrical tanks for oil appeared in the 1850s. Oil producers could buy wooden storage tank kits and have them shipped to their location. A 24 ft. diameter tank used 16 ft. wood staves and could hold over 51,000 gallons of oil. Riveted iron cylindrical tanks started replacing wood in 1864. They became necessary as petroleum became a significant fuel source.
It wasn’t long until oil producers discovered they needed a way to keep the oil flowing during the cold months.
Industrial Immersion Heaters and Suction Heaters
As bulk storage tanks began to proliferate in the 20th century, so did the demand for safe and efficient oil storage tank heaters to keep products flowing. Storage tank design went from large wooden vessels with open tops to massive, enclosed steel cylinders. The problem was how to heat viscous liquids such as heavy fuel oil or asphalt (bitumen) without risking a fire or explosion.
One of the pioneers in this field was Scott Ross, who started Ross Heater and Manufacturing in 1917. The company manufactured heat exchangers for the first oil refineries, such as Texaco, ESSO, and Standard Oil.
Engineers developed immersion heaters using the same principles as locomotive steam engines, where heated tubes exchange heat while immersed in a liquid. In this case, the heating tubes were resistance heating wires encased in a ceramic jacket and surrounded by a metal sheath. Alternatively, suction heater systems circulate heated oil in a closed system to provide heat inside the heat exchanger.
A suction heater is a type of immersion heater. The difference is a suction heater heats the material at the point where it is pumped out of the tank. Immersion heaters heat the entire contents in the tank. Immersion heaters are the ideal choice for processes requiring large quantities of material to maintain a specific temperature inside a tank.
How a Suction Heater Operates
The suction heater mounts through a flange attached to the tank wall at the bottom. The heating portion extends into the fluid. The shell of the heat exchanger is open at the end, allowing the product to circulate. The heat decreases the viscosity around the immersion heater for later extraction. Heating elements can be electrical or use heated oil circulating through them.
The heated liquid gets pumped into a separate external heat exchanger. The second exchanger allows operators to control the temperature accurately and then pump it back into the tank or onto the final distribution point. Suction heaters are the most efficient way to heat large amounts of viscous fluids.
Types of Immersion Heaters
German inventor Theodor Steibel patented the first 3-phase electric immersion heater in 1931. It was the beginning of reliable tank freeze protection. Since then, there have been numerous improvements in design and capacity.
Immersion heaters are the best way to heat entire tanks internally and don’t require a separate heat exchanger. As the name implies, these heaters work while submerged in a liquid. They can mount through a tank wall or drop in from above. Here is a breakdown of the primary types.
- Over-the-side immersion heaters are usually portable. An example is a deep fryer where the elements can lift out of the way for easy cleaning and oil replacement.
- Flanged immersion heaters are the best choice for large tanks, vats, or unevenly shaped vessels because they are 100% efficient. Every watt of power converts to heat. They come in a wide range of watt densities, heating outputs, and flange sizes.
- Screw plug immersion heaters are the smaller cousins of flange heaters. They are ideal for process water heating, freeze protection, and heat transfer for waxes, oils, and fats. They are compact and easily controlled for accurate temperature settings.
Immersion heaters are the heart of a heating system, whether by themselves or part of a circulation heater or a suction heater.
Storage Tank Heaters of the 21st Century
Storing liquids is problematic in areas with low or freezing ambient temperatures. Freezing water can destroy piping, valves, and instruments. Ice crystals can alter the final product, making it substandard such as food, beverage, and chemical products. Low temperatures mean high-viscosity liquids like melted wax, fats, petroleum, and honey won’t flow through the process, causing expensive production slowdowns and potential equipment damage.
To increase internal tank temperatures, engineers developed various custom tank heaters. Tank heaters maintain temperatures of the products inside vessels as small as 5-gallon pails to storage tanks holding thousands of gallons of liquids.
The two methods of heating stored liquids are external and internal, as with immersion heaters. Examples of external tank heaters include bucket heaters, tote heaters, and drum heaters. Another option is the steam-jacketed kettle which circulates steam or a heated liquid around the outside of the vessel.
Bulk storage tank heaters have evolved over the years, becoming more efficient and reliable. Today’s tank heating solutions use various power sources, including electric, gas, and oil. They are the most energy-efficient method to quickly heat large quantities of liquids and maintain a set temperature.
A recent design innovation is replaceable elements. Removing the elements for inspection or replacement is possible without draining the tank.
Another innovation is the Watt Density Chart. After studying decades of heater successes and failures, engineers devised a Watt Density Chart. This information helps maximize efficiency and reduces downtime. For example, suppose they installed a heating element based on calculations but didn’t lower the watt density for high viscosity in cold temperatures. In that case, the heater may run at higher than expected temperatures, overheating the liquid and leading to premature breakdown.
Engineers can quickly refer to the chart and lower the watt density value by half or two-thirds to help prevent any issues.
The Future of Tank Heaters
Tank heaters are constantly evolving and becoming more efficient and reliable. In the future, we can expect tank heaters that use renewable energy sources, like solar or wind power, to heat the liquids in the tanks. Microwave energy is another possibility for tank heaters. Experiments continue to show promise as an efficient industrial application.
We can also expect more tank heaters with digital controls and readouts at the source for real-time temperature control.
A Vital Component of Every Process
Industrial tank heaters have come a long way since their invention in the late 18th century. Today, we rely on them to heat large tanks quickly and efficiently. Immersion tank heaters are energy efficient and cost-effective for any industry.
Industrial tank heaters have a long and fascinating history, from the early coal-powered boilers to today’s electric versions. We hope this blog article has helped you learn more about the history of industrial tank heaters and how they have changed over the years.