2. Brief Introduction of Equipment 2.1, Charge Table At the charge end of the furnace a driven roller topped table allows coils or straight tube/bar to be loaded onto trays, which are designed to carry the load through the process. Each roller on the table is mounted on bearings supported by the main structure and is driven by chains connected to a fast drive system which transports the loaded tray into the charge purge chamber. 2.2 Charge Purge Chamber (CPC) Doors are fitted at each end of the Charge Purge Chamber to seal in the atmosphere. These doors are opened and closed by an external pneumatic cylinder and are fitted with pneumatically operated clamps.. At this stage, products are remaining in standstill. The CPC entry door opens for the product batches to be transferred from the charge table into the charge purge chamber and then closes. After purging the charge purge chamber discharge door and furnace chamber doors are opened simultaneously and the loads (in the charge purge chamber, furnace and radiation cooling chamber) are indexed forward. The charge purge chamber's discharge door and furnace chamber doors are then closed before the charge purge chamber's inlet door can be opened again to accept the next load from the charge table. The Charge Purge Chamber is a gas tight steel case construction with rollers and external roller drive systems. The rollers are mounted in sealed bearings to maintain atmosphere integrity. 2.3 Heating Chamber Entry Plenum In order to ensure adequate thermal separation between the charge purge chamber (CPC) and the furnace, an entry plenum and furnace door is provided. The entry plenum is a gas tight steel structure insulated on the inside and fitted with an insulated fiber. To minimize the loss of atmosphere integrity during loading and minimize re-purge time, two filament curtains are fitted behind the doors; and ceramic fiber isolating wall which driven by pneumatic cylinder is mounted in this section. An insulated membrane explosion relief port is designed at top of the furnace. 2.4 Furnace Heating Chamber 2.4.1 Casing The main heating chamber is a gas tight steel structure reinforced with structural steel members that are arranged to be suitable for installation on a level foundation. All heating elements, and thermocouples have sealing glands, and rollers are mounted in sealed bearings with gaskets to ensure gas tightness. Gas expel canopy which connected with hydraulic pressure tank is designed at side wall to control furnace pressure. Beside, protective gas inlet is also fitted on side wall. 2.4.2 Insulation The furnace is lined with a composite construction of refractory brickwork (thickness: 330mm) and low thermal mass ceramic fibre to give good insulating properties, together with good resistance to mechanical damage and gas erosion. Removable refractory pieces are provided to facilitate removal and replacement of rollers. The partial roof sections are lined with ceramic fibre modules arranged to give resistance to high velocity gas recirculation. The modules are fixed to the casing by special anchors which are set back from the hot face to minimise heat conduction through the lining via the fixing arrangement. 2.4.3 Heating Arrangement Heat is provided from 0Cr25AL5 alloy tape resistance elements fitted in the roof and hearth. Power of each heating zone is 160Kw. Overall power is 320Kw. 2.4.5 Drive Mechanism Drive mechanism for roller conveyor of heating chamber consists of electrical speed reducer and manual speed reducer. Roller rotating method has three type: (1): Fast Speed Rotating: for discharge products rapidly out of heating chamber. (2):Slow Speed Rotating: as product are transferred into heating chamber, to reduce movement of inertia, it shall change to slow speed rotating. (3):Forward and Backward Rotating: to avoid deformation, rollers will forward and backward moving during heating process. Speed reducer of heating chamber is controlled by frequency transducer. All mechanical movements are controlled by PLC. 2.4.6 Atmosphere Gas Recirculation System . Each zone is equipped with two powerful plug in type atmosphere recirculation fans. These fans are roof mounted and supported in a water cooled bearing housing. The fan shafts are fitted with a gas tight sealing arrangement. The protective atmosphere gas is discharged radially outwards from each fan. These protective atmosphere gases move vigourously over, through and around the charge promoting high convection heat transfer coefficients with rapid and uniform heating. Each fan is driven by an electric motor via a vee belt drive, and fitted with a rotation sensor. When cooling water run out, it will set out alarm signal and power supply will cut off. 2.5 Furnace Chamber Exit Plenum It has same structure with furnace chamber inlet plenum. Isolating door in this section is opened at same time with the insolating door in inlet plenum section. 2.6 Radiation Water Cooling Section This is a double cased water jacket steel tunnel to provide radiation cooling to the tray and charge immediately following exit from the furnace. This accommodates a full tray length and allows for all tubes to be cooled by the radiation cooler before being index driven into the jet cooler. Heat is taken away through water recirculation. Radiation water cooling section is divided independent four parts. Each part has integrated pipework. The radiation cooler section is a gas tight fabricated steel construction, mounted on a structural steel stand and containing a number of driven rollers. 2.7 Primary Convection Cooling Chamber The primary convection cooler (PCC) will cool the work after it leaves the radiation cooler to approximately 130ºC. The primary convection cooler (PCC) is a double cased water jacket split into 3 atmosphere gas recirculating zones to ensure uniform cooling of the load. A plug-type fan and muffle is fitted to each zone to ensure that atmosphere is recirculated and continually cooled over the chamber walls, which are a double cased water jacket. The cooled atmosphere gases then pass into a plenum chamber and up though slots over the charge and tray to achieve the required charge output temperature. The water jacket likes a heat exchanger. 2.8 Discharge Purge and Cooling Chamber (DPCC) To cool the load to 60ºC or below and to ensure that the furnace atmosphere is not contaminated a discharge purge and convection cool chamber (DPCC) is included. In addition to cooling circulating fan in this section, the DPCC has entry and exit doors which driven and clasped by pneumatic cylinder, of the same construction as the Charge Purge Chamber and a rapid purge system such that the chamber can have the necessary full atmosphere purge in a reduced time. These doors are opened and closed by an external pneumatic cylinder and are fitted with pneumatically operated clamps. 2.9 Discharge Table At the discharge end of the installation a driven roller topped table is provided to fast drive the charge from the discharge purge and cooling chamber. This table is of a similar design to that of the charge table.
3 Other Parts 3.1 Exhaust Canopies The inlet end of the Charge Purge Chamber and the exit end of the Discharge Purge Chamber and Cooling Chamber are provided with exhaust Canopy for the purpose of removing the atmosphere discharging from these chambers. The canopy terminates at a point local to the furnace structure. The atmosphere gases discharge should be ducted by the buyer to the exterior of the building. 3.2 Protective Atmosphere A protective atmosphere gas flow distribution system is provided, together with flowmeters and valves to each section of the installation with the main header terminating in a flanged connection to accept the buyers supply from their atmosphere storage. All pipeworks are located at bottom of furnace chamber which provide a uniform atmosphere. Double pipework of atmosphere gas supply is included in each set, one is electrical controlled, and the other is manually controlled. A multi point atmosphere gas analysis system is incorporated. 3.3 Cooling Water Pipework The cooling water system includes connections, valves and drain points arranged to discharge into tundishes for connection to the recirculating water cooling system. The proper arrangement is easy installation and replacement. 3.4 Roller Conveyor Arrangement The charge is conveyed through the equipment on a series of rotating rolls. These rollers are plain or fitted with collars as appropriate to retain the work centrally throughout the equipment. All the rollers are fitted with stub shafts. These stub shafts are mounted in flange mounting, gas tight, bearings attached to the furnace casing, cooling sections, etc., each bearing being provided with a lubricating point. At one side of the conveyor roller, the stub shafts are fitted with sprocket wheels for driving purposes. All roller drives are guarded.
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