In industrial processes where we need heat in the manufacturing process, the most common equipment to use is the industrial furnace. A furnace is required when we need high heat and other methods are inadequate. The high temperature inside the furnace allows us to work with extreme heat in a safe and secure manner.
There are different kind of furnaces. Some use electrical energy, while some use fuel. The basic design of an industrial furnace consists of a burner into fuel is supplied. Air comes in through an air blower. The burner has tubes that heat up, raising the temperature of the burner cavity. An industrial furnace company uses this basic design to make a furnace. There are different types of furnaces and this depends on the individual designs as well as method used to generate heat.
Components of an industrial furnace
An industrial furnace can be broadly divided into the following sections:
This is the section where the tubes are heated from the fuel source. The arrangement of tubes can differ from one furnace to another. These can be vertical, horizontal, arranged along the burner wall, in the middle or arranged in cells. The tubes are held in place with tube guides, while studs are used to place insulation inside. The tubes are placed so that a uniform temperature can be achieved inside.
Located above the radiant section, the convection section is cooler. It is named so because of the convection method that is used in this section for heat transfer. The tubes are finned here to aid heat transfer. It has a shield section which contains bare tubes, so named because it shields the rest of tubes in the convection section. This lies at the bottom of the section, just above the radiant section. The tubes are exposed to radiation coming out of the firebox in the furnace.
The function of radiant coils is to absorb heat. Contained in a box, these coils are placed vertically or horizontally in a hairpin arrangement. Since the coils absorb heat, these will also expand. Hence, an industrial furnace company will have to keep enough space for coil expansion. The material of the coil depends on the temperature we require. For low temperature, we use carbon steel and for high temperature we use high alloy steel. The coils are supported by high alloy steel.
A burner is where the fuel burns in the furnace. It is lined with tiles that are capable of withstanding high temperatures. The flame is controlled by manipulating the flow of air inside. This is achieved through the flaps and vanes that can be moved to control the flow of air inside. We can ensure whether we want the flame to swirl around or spread. This is a very important function, since a loss of control can be disastrous.
Burners are further divided into primary, secondary or tertiary according to the way air enters the cavity. Primary air is the first to enter a burner, followed by secondary air and so on. Some burners also mix the air and fuel before being introduced in the cavity. Sometimes steam may be used to pre-heat the air.
Located in the radiant section, a sootblower’s function is simply to remove the soot in the furnace. It uses materials like air, steam or water to remove deposits. It is a very important function in the overall maintenance of the furnace. A sootblower is usually employed when the efficiency of the convection section decreases. However, many industrial furnace companies recommend a regular use of sootblower to ensure optimum efficiency.
Flue gas stack
The flue gas stack is a conical structure that is situated at the top of the furnace. The flue gas is collected in a section just below the stack and then released into the atmosphere so as to avoid a build up of heat. The flue gas must also pass through the convection section. The stack regulates the pressure and amount of air that passes through.
Insulation is essential in a heat chamber to ensure minimal heat loss, thereby maintaining its efficiency. Insulation is used on various components like the walls and floors. Materials used for insulation include ceramic and firebrick.
The overall design will differ from one industrial furnace company to another, but these essential components are common to all furnaces.