High-temperature gas heating method and device for pickling hot rolled steel strip

Abstract

The invention discloses a high-temperature gas heating method and device for pickling a hot rolled steel strip. The method comprises the following steps of: firstly, heating high-temperature gas: heating the passing steel strip to 85-500 DEG C through high-temperature gas in a box; then, leading the heated steel strip to enter a pickling tank; heating acid liquid to 60-98 DEG C through the steel strip; and reacting the steel strip with acid to remove the oxide of ferrum on the surface. In the method disclosed by the invention, the surface temperature of the steel strip is increased to above the normal pickling temperature through use of the high-temperature gas; then, the high-temperature steel strip enters the pickling tank; the pickling solution is heated by the accumulated heat of the steel strip, the rapid pickling is realized, the aim of rapid dissolution of the oxide is achieved, and the steel strip without oxide on the surface is obtained. The traditional method for increasing the temperature of the steel strip and the acid liquid is changed; and the steel strip is not in direct contact with the acid liquid during heating in the method, the heating speed is high, and the blockage condition caused by the deposition and gumflower of colloid and oxide film suspensions in a heater is basically prevented.

Description

technical field [0001] The invention relates to a pickling technology for steel strips, in particular to a heating method and device for pickling hot-rolled steel strips. Background technique [0002] The existing steel strip pickling generally adopts the method of continuous pickling, that is, the hot-rolled steel strip passes through several pickling tanks continuously, and the pickling acid concentration and flow direction of the pickling tanks are opposite to the running direction of the steel strip. In order to increase the pickling speed in the pickling of the steel strip, the steel strip and the acid solution need to be heated. The current common method is that the acid is indirectly heated by external steam to raise the temperature, and the steam and the acid solution are separated in two non-contact channels of the heater, and the acid solution is heated by conduction. The temperature of the steel strip is raised by heating the acid solution. Under the high-tempera...

AI Technical Summary

Problems solved by technology

The disadvantages of this heating method that relies on steam to heat the acid solution, and the acid solution to reheat the steel strip are: 1) In most cases, the steel strip enters the first pickling tank at the entrance at room temperature, and then the steel strip enters the first pickling tank at the entrance. Room temperature is heated to the desired temperature, so a major function of the first pickling tank is to increase the temperature of the steel strip as a heater. Relatively speaking, the temperature of the steel strip in this tank is relatively low, and the pickling speed is slow

When the colloid and oxide film suspension flow in the acid pipeline or are heated by the heater, they will adhere to the wall of the acid pipeline or heater, which will affect the use of the acid pipeline and heater, and seriously cause the continuous pickling line to fail to operate

3) Non-ferrous oxides in steel (for example: silicon dioxide) exist in the form of colloids or membranes in the acid solution. Due to the high temperature on the surface of the heater, the colloidal sols are converted into gels and membranes , deposited on the surface of the heater acid solution, as time goes by, the deposit becomes thicker and thicker, resulting in loss of equipment function

Since the temperature of the steam is generally not high, and the speed of steam heating the steel is slow, it takes a long time for the heat transfer of the steel to slow down the pickling speed.

At the same time, the steam heating tank (hot water circulation) occupies a very large space and cannot be set arbitrarily, which cannot solve the problem of maintaining the required temperature in the pickling tank of the entire pickling line

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