Thermal Oil Heaters

What is a Thermal Oil Heater?

A Thermal Oil Heater, also known as a hot oil heater, is an industrial heating system that uses thermal oil as a heat transfer medium instead of steam or water. These systems are particularly advantageous in processes that require high and homogeneous temperatures, typically reaching up to 350°C or more, as they provide heat transfer without the need for high pressures seen in steam systems.

In a typical setup, thermal oil is heated within the heater and then circulated through a closed-loop system using a pump, directly transferring heat to the desired process equipment, such as reactors, dryers, or heat exchangers. The oil, after losing its heat, returns to the heater to be reheated, thus maintaining a stable temperature with high thermal efficiency.

Hot oil heaters are widely used in industries such as petrochemical, textile, food processing, and plastics due to their precise temperature control, low maintenance requirements, and thermal stability. Unlike water-based systems, these systems do not face the risks of corrosion and scaling, extending the equipment's lifespan and ensuring safer operation in challenging thermal environments.

Vimpo VTH Thermal Oil Heater

The Vimpo VTH Hot Oil Heater, with a capacity ranging from 200 to 2,000,000 kcal/hour, is designed in a container type for easy transportation.

The hot oil heater is used in countless production methods. Various industries require thermal oil to carry process heat. The Vimpo hot oil heater is heated by flue gas inside and operates as a single-pass system.

Vimpo VTH Hot Oil Heater Features

• Capacity: 100,000 Kcal - 3,000,000 Kcal
• Fuel: Liquid - Gas
• Operating Temperature: Up to 350°C
• Control: Automatic
• Insulation: Rock Wool
• Safety: Pressure Sensor

Working Principle of Thermal Oil Heaters

A hot oil heater is a closed-loop heating system that uses specially formulated thermal oil instead of water or steam for heat transfer. The basic working principle of this system is to heat the thermal oil to high temperatures on the heating surfaces within the heater and then direct it to the process equipment with the help of a circulation pump.

When the heated oil reaches the target devices, it transfers the heat it contains. During this process, there is no evaporation or pressure increase because the system operates at a pressure close to atmospheric pressure. The oil, after losing its heat, returns to the heater, and the cycle continues. This continuous circulation ensures both homogeneous and stable temperature control.

Hot oil heaters are especially preferred in industrial applications that require high temperatures but wish to avoid the high pressure risks associated with steam. The system eliminates water-specific problems such as corrosion and scaling, while also offering significant advantages in terms of energy efficiency and operational safety.

Where Are Hot Oil Heaters Used?

Hot oil heaters are used in a wide range of industries, including textiles, paper, chemicals, food, paint, leather, construction, oil, and crane manufacturers. They are employed in industrial facilities where high temperatures are required for various processes.

• Chemical and Petrochemical Industry: Used for the safe and controlled heating of reactors and process tanks.
• Food Industry: Provides stable temperatures in industrial ovens, cooking systems, frying units, and drying lines.
• Used in processes requiring high temperatures, such as drying drums, calender machines, and dyeing lines.
• Plastic and Rubber Industry: Preferred for temperature control in extrusion lines, mold heaters, and thermal forming machines.
• Wood and MDF Production: Plays an important role in the uniform heating of press systems and dryers.
• Paint and Resin Production: Helps maintain stable temperatures in mixing tanks and reactors for production.
• Asphalt and Bitumen Plants: Used for heating bitumen storage tanks and asphalt production machines.
• Energy and Recycling Plants: A reliable heat source in waste heat recovery systems and energy production processes.

How Does a Hot Oil Heater Work?

A hot oil heater works by heating the oil inside with flue gas and operates as a single-pass system. It is suitable for burning diesel and natural gas. The heater consists of intertwined spiral-shaped tube bundles. The harmful effects that may arise due to heat are eliminated through these spirals.

Thermal oils are used for heat transfer in hot oil heaters. The system can operate without pressure at high temperatures. All the oil in the system circulates through the spiral tubes, heats up, and then exits the heater to be delivered to the required locations. The flow is fully controlled. The thermal oil used as the heat carrier in the system does not leave residue in the installation and does not cause scale formation in the heater.

How to Use a Thermal Hot Oil Heater?

The liquid is placed in an open container, and heating begins to determine the flash point of the liquid. During this process, electrical arcs and gas flames form on the heated container. As the temperature rises, the liquid starts to evaporate. When sufficient vapor is produced, the vapor ignites with the open flame above and flickers. The temperature of the liquid at this moment is defined as the flash point of the liquid.

Next, the liquid must be heated further to generate much more vapor. As a result, the temporary flickering turns into steady flames over time, and the fluid temperature is known as the ignition point. Hot oil heating systems flow and operate within insulated pipes. Closed-cell type insulation or insulation without insulation is recommended for potential leak points.

After making the plumbing connections and filling the system with oil, the circulation pump is started, and the correct rotation control is checked according to the directional marks on the pump. Once the circulation pump starts, if the differential pressure light turns on, the burner on/off switch should be moved to the right, and the "burner on" light will turn on while the burner start command goes off.

The operating thermostat has two digital displays. The section marked "PV" shows the immediate oil temperature exiting the heater. The section marked "SP" shows the temperature at which the burner will stop. The temperature can be increased or decreased using the up and down buttons. The safety thermostat has two digital displays, the first one marked "PV" shows the current oil temperature, and the "SP" section shows the temperature at which the burner will stop for safety. This can be changed using the up and down arrow keys.

The Ø80 sized valve placed before the degasser is closed, and then filling is done from the nozzle. The oil capacity level is monitored from the expansion tank's level indicator. The oil level should be about 1/3 of the expansion tank's volume. The system should then be left to rest for about 1 hour. Before the heater is turned on, the circulation pump should be started. The pump is started after the manometer pressure value is read from the pump outlet.

The burner unit is connected to a circulation pump unit, expansion tank level, flow sensor, and safety thermostats. It should be noted that the burner will not work without the circulation pump running, the burner will not work if there is no oil in the expansion tank, and the burner will not work when the system is at high or sufficient temperature.

In fuel system applications, all pre-heaters should be turned on at least half an hour before starting the burner unit. The line, pot, and burner pre-heaters should be operated by starting the circulation pump. The outlet thermostats should be set to the desired value. Afterward, the burner unit is turned on.

It should be ensured that the system temperature reaches 100°C. The burner is stopped. The burner should be paused every 20°C, and the system should be checked each time until the set value is reached.

When the set value is reached, the burner operation should be observed, and it should be checked that the burner starts again when the set value drops. To stop the heater, the burner should be turned off. Refractory and steel materials will continue to heat the oil due to absorbed heat. The pump should be turned off when the system is still hot.

Thermal Oil Heaters Prices

Thermal Oil Heaters prices vary depending on several factors such as the system’s capacity, the quality of materials used, the level of automation, and the technical support provided by the manufacturer. Commonly preferred in industrial facilities for processes requiring high temperatures, these boilers offer stable and safe heating at temperatures up to 350°C.

Key pricing factors include the boiler's capacity (e.g., ranging from 200,000 kcal/h to 4,000,000 kcal/h),the surface area of the coil, whether it has a single or double coil design, the type of combustion system (such as natural gas, diesel, or biofuel),and designs that enhance energy efficiency. Models manufactured from stainless steel or special alloy steel tend to be more expensive than those made from standard carbon steel.

Boilers equipped with automatic control systems, remote monitoring capabilities, and integrated safety systems may have a higher upfront cost, but they provide significant long-term advantages in terms of operational safety and energy savings. Therefore, when investing in a hot oil boiler, it is important to consider not only the initial cost but also factors such as ease of maintenance, energy consumption, and durability.

How is Hot Oil Boiler Maintenance Performed?

While inspecting the hot oil boiler, valves and threaded connections around the pipeline should be checked. Odors can be a clue and early sign of leakage. The system ventilation pipe located above the expansion tank should be monitored to detect the presence of steam or soot, which may indicate the presence of water or the onset of oil degradation.

If hot oil leaks into the expansion tank during system operation, it narrows the diameter of the boiler’s ventilation pipe and prevents hot oil from reaching the expansion tank. Once hot oil comes into contact with air, it can ignite very easily.

While circulating through the plumbing system, attention should be paid to vibrations or odors, and their source should be located. Due to the risk of fire, a sufficient number of fire extinguishing devices must be kept in accessible and clearly visible locations.