This case study involves a cart-type degreasing and carbonization furnace, model RT3-360-5, a cycle-operated furnace with a chamber working dimension of 6,000 mm in length, 2,000 mm in width, and 2,000 mm in height. The equipment serves two purposes: first, degreasing metal cylinders and pipes of different diameters; second, burning off rubber insulation and lining inside cylinders and pipes of varying diameters in carbonization processes.
The common feature of these two processes is that the workpieces contain organic or polymer materials inside that need to be removed, and the combustion products must be discharged promptly. The workpieces themselves are elongated cylindrical structures, imposing relatively high requirements on furnace temperature uniformity. The rated temperature of the equipment is 500°C, with adjustable operating temperature.
The rated power of the equipment is 500 kW, adjustable within a percentage range; rated voltage 380V, three-phase 50Hz. The full-load heating rate is adjustable from 20 to 80°C per hour, and the empty furnace heating time does not exceed 90 minutes. Furnace temperature uniformity during the holding stage does not exceed ±5°C. The temperature control instrument is a Japanese Shimaden SRS13A with an accuracy of no more than ±1°C. The temperature control method combines a touch screen human-machine interface with the Shimaden intelligent instrument and a power regulator for PID voltage regulation control.
The heating elements are 0Cr25Al5 high-resistance alloy resistance strips produced by Shougang Group, processed into a waveform structure using a special mold, and arranged on five surfaces: both sides of the furnace, the furnace door, the rear wall, and the furnace bottom. The number of temperature control zones is set at 4, with each zone independently equipped with an ammeter, voltmeter, and on/off indicator for ease of fault localization.
The furnace body insulation material is standard aluminum silicate refractory fiber cotton with a thickness of 240 mm. The furnace air guiding mechanism material is 304 stainless steel with a thickness of 2 mm. The furnace bottom plate material is CrMnN cast steel with a thickness of 30 mm, in strip form.
The lining uses standard aluminosilicate refractory fiber blankets, specially processed into large plate structures with a density of 230 kg/m³, finally assembled into a lining with a thickness of 240 mm. The fiber cotton modules are anchored to the steel structure of the furnace body using SUS304 stainless steel round bar anchors.
The weight of an all-fiber lining is approximately one-thirtieth that of a refractory brick furnace body. The direct consequence of this weight difference is a substantial reduction in steel structure load. The comparison reference given in the proposal is that, under the same specifications, the all-fiber structure saves approximately 30% more energy than a brick-based resistance furnace. This figure is an engineering empirical value; actual energy savings depend on operating conditions such as furnace sealing condition, heating curve, and loading rate.
All-fiber refractory structures have good thermal shock resistance, can withstand rapid heating and cooling, and have a longer service life than brick structures.
The heating elements adopt an advanced suspension structure with high radiation efficiency, enhancing heat exchange within the furnace, improving furnace thermal efficiency, and extending heating element life. The resistance strips are processed from 0Cr25Al5 into a waveform structure, convenient for installation and maintenance.
The furnace door adopts a steel frame structure with refractory fiber as the heat insulation material, installed in the same manner as the furnace body. The furnace door is equipped with a 2-ton electric lifting mechanism, with the electric hoist installed above the furnace door gantry frame. The door lifting speed is 8 m/min.
The furnace door sealing employs a cam mechanism for automatic clamping combined with a soft-edge sealing device, ensuring the door automatically seals against the furnace body. The function of this sealing mechanism is to guarantee furnace sealing throughout production, prevent the escape of high-temperature furnace gases, improve the working environment, and also ensure furnace temperature uniformity and enhance energy efficiency. This sealing device is simple in structure, safe, reliable, and easy to maintain, having been verified over years in the production of all-fiber cotton cart-type furnaces.
Regarding safety protection, both upper and lower travel of the furnace door are equipped with double safety limit mechanisms, along with an interlocking device with the furnace car. Heating power is automatically cut off the moment the furnace door opens. Limit switches are Omron brand.
The trolley consists of a frame, trolley furnace lining, furnace bottom plate, and trolley traction mechanism. The frame is welded from channel steel, with 10 mm side plates and 5 mm bottom plates (Q235), firmly and reliably constructed, not easily deformed or warped.
The bottom insulation layer of the trolley furnace base consists of two layers of alternating diatomaceous earth bricks and lightweight straight bricks, while the refractory layer is constructed using heavy bricks. The trolley perimeter uses irregularly shaped bricks to prevent furnace gas from directly contacting the trolley side plates. The refractory layer on the trolley is constructed in a groove shape for placing heating elements, which also serves as a support for the furnace bottom plate.
The furnace bottom plate is made of CrMnN cast steel with a total thickness of 30 mm, resting above the groove where heating elements are placed to prevent oxides from falling onto the heating elements after the workpiece is heated. The furnace bottom plate is equipped with a snap-fit design to prevent movement.
The rear of the trolley is equipped with RT0 moving and stationary contacts for power connection, completing the power supply to the heating elements on the trolley. This contact method has a large and sufficient contact surface, good contact, and no electric sparks or overheating after long-term use.
The traction device uses a frame structure for load-bearing and movement. The frame is mainly welded from 16 channel steel and steel plate. The wheels are forged from 45# steel with strong wear resistance. The drive is a motor plus a reducer, with an entry/exit speed of 6 to 8 m/min, driven by one motor.
Both furnace entry and exit are equipped with double safety limit mechanisms and interlocking mechanisms – if the trolley does not reach the correct position, the furnace door cannot be opened or closed, and the entire furnace body cannot be powered. Synchronous geared motors make the trolley entry and exit flexible, stable, and accurately positioned.
To achieve uniform furnace temperature, 4 centrifugal circulating fans are installed at the top of the furnace along its length, each rated at 7.5 kW, 4-stage motors. The fan blades and shaft are made of 304 stainless steel. The fan is a one-piece design, with the motor rotor and fan shaft as a single unit, providing stable speed, low noise, and strong airflow.
The furnace air guiding mechanism is made of heat-resistant SUS304 steel plate, with convection walls on both sides. Considering that the workpieces are plate-shaped or cylindrical, the hot air circulation direction is designed as horizontal – air flows horizontally from one side of the convection wall to the other, that is, air passes through the middle of each layer of workpieces. This airflow path ensures even heating and uniform temperature of the workpieces, further improving product performance.
This case study involves a cart-type degreasing and carbonization furnace, model RT3-360-5, a cycle-operated furnace with a chamber working dimension of 6,000 mm in length, 2,000 mm in width, and 2,000 mm in height. The equipment serves two purposes: first, degreasing metal cylinders and pipes of different diameters; second, burning off rubber insulation and lining inside cylinders and pipes of varying diameters in carbonization processes.
The common feature of these two processes is that the workpieces contain organic or polymer materials inside that need to be removed, and the combustion products must be discharged promptly. The workpieces themselves are elongated cylindrical structures, imposing relatively high requirements on furnace temperature uniformity. The rated temperature of the equipment is 500°C, with adjustable operating temperature.
The rated power of the equipment is 500 kW, adjustable within a percentage range; rated voltage 380V, three-phase 50Hz. The full-load heating rate is adjustable from 20 to 80°C per hour, and the empty furnace heating time does not exceed 90 minutes. Furnace temperature uniformity during the holding stage does not exceed ±5°C. The temperature control instrument is a Japanese Shimaden SRS13A with an accuracy of no more than ±1°C. The temperature control method combines a touch screen human-machine interface with the Shimaden intelligent instrument and a power regulator for PID voltage regulation control.
The heating elements are 0Cr25Al5 high-resistance alloy resistance strips produced by Shougang Group, processed into a waveform structure using a special mold, and arranged on five surfaces: both sides of the furnace, the furnace door, the rear wall, and the furnace bottom. The number of temperature control zones is set at 4, with each zone independently equipped with an ammeter, voltmeter, and on/off indicator for ease of fault localization.
The furnace body insulation material is standard aluminum silicate refractory fiber cotton with a thickness of 240 mm. The furnace air guiding mechanism material is 304 stainless steel with a thickness of 2 mm. The furnace bottom plate material is CrMnN cast steel with a thickness of 30 mm, in strip form.
The lining uses standard aluminosilicate refractory fiber blankets, specially processed into large plate structures with a density of 230 kg/m³, finally assembled into a lining with a thickness of 240 mm. The fiber cotton modules are anchored to the steel structure of the furnace body using SUS304 stainless steel round bar anchors.
The weight of an all-fiber lining is approximately one-thirtieth that of a refractory brick furnace body. The direct consequence of this weight difference is a substantial reduction in steel structure load. The comparison reference given in the proposal is that, under the same specifications, the all-fiber structure saves approximately 30% more energy than a brick-based resistance furnace. This figure is an engineering empirical value; actual energy savings depend on operating conditions such as furnace sealing condition, heating curve, and loading rate.
All-fiber refractory structures have good thermal shock resistance, can withstand rapid heating and cooling, and have a longer service life than brick structures.
The heating elements adopt an advanced suspension structure with high radiation efficiency, enhancing heat exchange within the furnace, improving furnace thermal efficiency, and extending heating element life. The resistance strips are processed from 0Cr25Al5 into a waveform structure, convenient for installation and maintenance.
The furnace door adopts a steel frame structure with refractory fiber as the heat insulation material, installed in the same manner as the furnace body. The furnace door is equipped with a 2-ton electric lifting mechanism, with the electric hoist installed above the furnace door gantry frame. The door lifting speed is 8 m/min.
The furnace door sealing employs a cam mechanism for automatic clamping combined with a soft-edge sealing device, ensuring the door automatically seals against the furnace body. The function of this sealing mechanism is to guarantee furnace sealing throughout production, prevent the escape of high-temperature furnace gases, improve the working environment, and also ensure furnace temperature uniformity and enhance energy efficiency. This sealing device is simple in structure, safe, reliable, and easy to maintain, having been verified over years in the production of all-fiber cotton cart-type furnaces.
Regarding safety protection, both upper and lower travel of the furnace door are equipped with double safety limit mechanisms, along with an interlocking device with the furnace car. Heating power is automatically cut off the moment the furnace door opens. Limit switches are Omron brand.
The trolley consists of a frame, trolley furnace lining, furnace bottom plate, and trolley traction mechanism. The frame is welded from channel steel, with 10 mm side plates and 5 mm bottom plates (Q235), firmly and reliably constructed, not easily deformed or warped.
The bottom insulation layer of the trolley furnace base consists of two layers of alternating diatomaceous earth bricks and lightweight straight bricks, while the refractory layer is constructed using heavy bricks. The trolley perimeter uses irregularly shaped bricks to prevent furnace gas from directly contacting the trolley side plates. The refractory layer on the trolley is constructed in a groove shape for placing heating elements, which also serves as a support for the furnace bottom plate.
The furnace bottom plate is made of CrMnN cast steel with a total thickness of 30 mm, resting above the groove where heating elements are placed to prevent oxides from falling onto the heating elements after the workpiece is heated. The furnace bottom plate is equipped with a snap-fit design to prevent movement.
The rear of the trolley is equipped with RT0 moving and stationary contacts for power connection, completing the power supply to the heating elements on the trolley. This contact method has a large and sufficient contact surface, good contact, and no electric sparks or overheating after long-term use.
The traction device uses a frame structure for load-bearing and movement. The frame is mainly welded from 16 channel steel and steel plate. The wheels are forged from 45# steel with strong wear resistance. The drive is a motor plus a reducer, with an entry/exit speed of 6 to 8 m/min, driven by one motor.
Both furnace entry and exit are equipped with double safety limit mechanisms and interlocking mechanisms – if the trolley does not reach the correct position, the furnace door cannot be opened or closed, and the entire furnace body cannot be powered. Synchronous geared motors make the trolley entry and exit flexible, stable, and accurately positioned.
To achieve uniform furnace temperature, 4 centrifugal circulating fans are installed at the top of the furnace along its length, each rated at 7.5 kW, 4-stage motors. The fan blades and shaft are made of 304 stainless steel. The fan is a one-piece design, with the motor rotor and fan shaft as a single unit, providing stable speed, low noise, and strong airflow.
The furnace air guiding mechanism is made of heat-resistant SUS304 steel plate, with convection walls on both sides. Considering that the workpieces are plate-shaped or cylindrical, the hot air circulation direction is designed as horizontal – air flows horizontally from one side of the convection wall to the other, that is, air passes through the middle of each layer of workpieces. This airflow path ensures even heating and uniform temperature of the workpieces, further improving product performance.
