Flow heaters are a great solution for heating liquid and gaseous media (including explosive ones). Compared to a heat exchanger that uses an intermediate heat carrier to transfer heat to the heated medium, a flow heater transfers heat directly to the medium from the electrical power. This approach allows for smoother temperature control and significantly reduces the size and cost of the equipment.
The heating processes of liquid media, including thermal oil, water, diesel fuel, oil, mazut, and others, are more effectively carried out using flow heaters due to their precise temperature control and viscosity retention of the heated substance. Improper viscosity of the substance can impede the correct progress of technological and production processes. Additionally, flow heaters are used for direct control of liquid flow rate. Their power can be regulated to obtain the desired temperature, and since the flow rate is directly proportional to the temperature/viscosity of the liquid, it can be controlled.
Flow heaters are widely used for heating argon, nitrogen, oxygen, and air, including heating of explosive media such as natural gas and fuel gas. The heating of natural and fuel gas is necessary before it is supplied to gas turbine installations that use it as fuel. Heating of nitrogen, oxygen, and argon is widely used in the chemical industry.
FLOW HEATER DESIGN
A flow heater is a device consisting of U-shaped or cartridge heating elements located on a flange or thread and placed in a flow vessel made of stainless or carbon steel, with inlet and outlet nozzles. To reduce heat loss and the risk of burns, the vessel can be insulated. The heated medium enters the device through the inlet nozzle and passes through the heating elements, removing heat from them. Then it exits the device through the outlet nozzle, having reached the required temperature, and is supplied to the consumer. Pumps are used to transport liquid through the device, which can also provide a closed heating circuit, and compressors are used for gaseous media. The material of the heating elements is selected depending on the type of heated medium and working temperature. The specific power of the heating element is also selected based on the thermophysical properties of the heated medium.
To monitor the temperature of the heated medium at the outlet of the device, a temperature sensor (mechanical thermostat, thermocouple, or resistance thermometer) is usually installed. Additionally, the device may be equipped with a temperature control system for the heating elements, which automatically shuts off the equipment in case of no flow or critical temperature rise of the heating elements. The device's design also includes ventilation and drainage pipes for maintenance purposes. Flow-through heaters can be manufactured in both industrial and explosion-proof designs. They are usually mounted horizontally, but in the case of limited space, they can also be made in a vertical design.