Dofasco Mechanical Tuyere Extractor

Background of the Invention

In a blast furnace, air must be supplied for making iron products. Thus, several tuyeres are installed near the bottom portion of the furnace for feeding air into the furnace.  The tuyeres must be periodically removed from the furnace for maintenance and replacement.

Generally the furnace has a wall member or rosette providing an entry hole into the external wall of the furnace, with a tubular cooling ring retainer secured therein.  The purpose of the cooling ring or tymp is to protect the refractory brick in the furnace interior from being exposed to the localized high temperature air being blown through the entry hole. The tuyere is a tubular frustaconal body that is fitted into the interior of the frustaconal-cooling ring, both of which are made of copper. The tuyere is designed such that it is held in place by a frictional fit due to its smaller diameter, while the end portion of the tuyere extends beyond the end of the cooling ring into the furnace interior.  When disassembling a tuyere from a cooling ring, the hot air source is turned off and the hot air injection piping is removed from the injection port exposing the cooling ring and tuyere opening. This allows a bar, typically of about 4 meters in length, with a hook (“toe”) on the end, to be inserted into the interior of the cooling ring/ tuyere assembly from outside the furnace. The toe is hooked over the interior nose of the tuyere extending into the body of the furnace and up to 12 laborers join forces to pull the “hooked” tuyere forward, away from the cooling ring, using sliding impact on the end of the bar, extending out of the furnace. Significant force is required to break the frictional fit between the outer frustaconial surface of the tuyere body and the inner frustaconal surface of the cooling ring or tymp. Therefore, disassembly of the tuyere from the cooling ring is a labor-intensive, time consuming operation. In addition, because of the tight engagement between the cooling ring and the tuyere and the amount of force required to dislodge it, injuries to operators can easily occur during the disassembly operation, causing among other things back strain and crushed limbs.

Various mechanical methods have been described in the literature and in particular US patents # 5,127,633, US 5,925,312 that are specifically directed to the removal and installing of tuyeres in a blast furnace.

In the case of US Patent 5,127,633, Mailliet describes a hydraulic device consisting of a 3-claw head for removal of either a tuyere or a cooling ring (tymp) from a furnace wall.  The device is overly complicated in design, heavy and awkward for a laborer to use, requiring mechanical lifting means to position the device.  It also employs ancillary equipment, including hydraulic piping and compressors which all must be available at the work site.

In the case of US 5,925,312, Lin describes a hook device requiring the use of a for...