An Improved Horizontal Continuous Annealing Furnace and a Method for Reducing Oxidation of Silicon Steel Strips

Abstract

The invention discloses an improved horizontal-type continuous annealing furnace and a method of reducing oxidization on silicon steel plate strips. In the invention, a newly-added pipeline is added to the end of a dry protective gas pipeline at a soaking section in a conventional horizontal-type continuous annealing furnace so that the dry protective gas is leaded to the first section and the third section of a circulating gas jetting quick-cooling segment and is connected to existing four nitrogen feeding points at the two sides of the first section and the third section of the circulating gas jetting quick-cooling segment of a furnace body. A manual ball valve is added to the total pipeline of the newly-added dry protective gas pipeline and is matched with the existing four manual ball valves at the four nitrogen feeding points at the two sides of the first section and the third section of the circulating gas jetting quick-cooling segment of the furnace body to accurately control the content of hydrogen in the circulating gas jetting quick-cooling segment to be 3-8%. From the first section and the third section of a resistance strip soaking section and the circulating gas jetting quick-cooling segment, the dry protective gas is fed into the continuous annealing furnace according to the feeding amount of 100-150 Nm<3> / h. Even when the oxygen content reaches 300 ppm in the circulating gas jetting quick-cooling segment, the bright degree of the surface color of silicon steel plate strips discharged from the furnace can satisfy the requirements of surface quality and coating quality of silicon steel.

Description

technical field [0001] The invention relates to the field of metal technology, in particular to an improved horizontal continuous annealing furnace and a method for reducing oxidation of silicon steel sheets. Background technique [0002] For medium and low-grade non-oriented silicon steel, the current typical annealing equipment is a horizontal continuous annealing furnace, such as figure 1 and 2 The main components shown are the inlet sealing chamber, the full radiant tube heating section, the 1# expansion joint, the soaking section, the furnace throat, the 2# expansion joint, the circulating gas injection control cooling section, the circulating gas injection rapid cooling section, and the outlet sealing room. [0003] A typical protective gas introduction method is: dry (wet) nitrogen-hydrogen mixture is passed through the soaking section, and low-pressure nitrogen is passed through the protective gas injection cooling section. It flows against the direction of the st...

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Problems solved by technology

[0004] However, in the actual production process, due to factors such as thermal expansion and contraction or equipment aging, the suction port of the fan in the circulating gas injection cooling section is not tightly sealed to a certain extent, so that a small amount of air is sucked in, and the trace amount of oxygen in the protective gas is oxidized with the steel strip. Make the surface of the steel strip out of the furnace black, seriously affecting the surface quality and coating quality of the silicon steel

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