The hood annealing furnace generally uses hydrogen or a mixed gas of hydrogen and nitrogen as a shielding gas, but hydrogen has better thermal conductivity than hydrogen and nitrogen, and 100% of hydrogen has stronger decarburization ability than hydrogen and nitrogen, and hydrogen is used as a cover for shielding gas. The surface of the strip treated by the annealing furnace has less carbon residue and more uniform mechanical properties. Therefore, the use of all hydrogen as a shielding gas has been applied in some metallurgical industries. So what is the process of such a hood annealing furnace annealing process? How does it finish annealing the workpiece?
The main process equipment of the full hydrogen hood annealing furnace includes an annealing furnace table with a supply pipe and a discharge pipe, an inner cover, a heating cover, a cooling cover, a valve station and the like. At the beginning of the annealing, the steel coils to be annealed are first stacked on the annealing furnace table, the inner cover is hoisted, and the cold seal test of the furnace and the inner cover system and the hydrogen inlet valve is performed. After the test is successful, it is also required. Nitrogen purge, while hoisting the heating hood, and then heating the hood to ignite. When the nitrogen purge is satisfied, the nitrogen in the inner casing is replaced by a hydrogen purge. The heating starts and the heating curve is selected according to different materials for temperature control until the temperature of the coil core reaches the process requirements.
In the process of the full hydrogen hood annealing furnace, the cooling starts from the heating hood on the top of the furnace. First, air is blown into the heating hood, and then the heating hood is removed. The cooling hood is then hoisted and the inner hood is cooled by suctioning the ambient air through a fan above the cooling hood. When the circulating atmosphere inside the inner cover reaches the set temperature, the cooling cover fan stops running, and after a while, the spray cooling starts. After the temperature of the coil core reaches the set value, the cooling is completed and the cooling hood is removed. Then, a nitrogen purge is performed to replace the hydrogen in the inner cover, the inner cover is removed, and the steel coil is hoisted later, so that a process is completed.
