JPS6218610B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a salt bath furnace for treating flexible continuous heat objects such as wire rods or metal strips.

As is well known, salt bath furnaces have various features such as being able to uniformly heat and cool, and avoiding oxidation and decarburization, as well as being able to heat and cool in a short time and have a small furnace body. Although the salt bath furnace has a unique feature, it consumes a huge amount of heat for heating, and also requires a large amount of energy for cooling.

The present invention aims to significantly reduce energy consumption in the above-mentioned salt bath furnace by using the amount of heat wasted during cooling for preheating and greatly improving thermal efficiency.

An embodiment of the present invention will be described below. The salt bath furnace shown in the figure is of a horizontal type, with numeral 1 indicating a metal strip as a heated object, and numeral 2 a furnace body, which is filled with salt as a heat medium. Reference numerals 3 and 3 indicate reversing rolls provided in the inner part of the furnace body, and the object to be heated 1 is carried into the furnace through the seal roll 4 on the upper part of the end wall, and is stretched around the reversing rolls 3, 3. By folding back and exiting from the furnace through the seal roll 5 at the bottom of the end wall, the object to be heated is conveyed within the furnace in such a manner that the outward side 1' and the incoming side 1'' are substantially parallel. The area where the reversing rolls 3, 3 are located is divided by a partition wall 6, and a heat source is provided to heat the salt in this area in order to make this area a heating/soaking area 7.The heat source is electricity. There are various known types such as a direct heating type in which electricity is applied directly to the salt, and one using combustion heat of gas or heavy oil fuel. Heat exchange is performed by forced convection. Reference numeral 9 denotes a partition wall that partitions the heat exchange zone into 8a and 8b, and the partition wall 9 restricts the free flow of salt in the direction of transport of the object to be heated. Note that seal rolls 10 are provided in the heated object through holes of the partition walls 6 and 9.

In the salt bath furnace configured in this way, when the heated object 1, which has been uniformly heated to a predetermined temperature by passing through the heating/soaking zone 7, is carried into the heat exchange zones 8b and 8a, the next side The salt in the heat exchange zones 8b and 8a is heated by the amount of heat possessed by the heated object 1'', and the salt is further subjected to natural convection or forced convection by a stirrer (not shown), so that the salt is heated. Heat is transferred to the object to be heated 1' on the outgoing side.For this reason, the object to be heated 1 is preheated by passing through the heat exchange zones 8a and 8b, and then transported to the heating/soaking zone 7. Therefore, it is possible to uniformly heat up to a predetermined temperature with a small amount of heat, and the object to be heated 1'' on the next side coming out of the heating/soaking zone 7 is slowly cooled in the heat exchange zone 8b and further cooled in the heat exchange zone 8a. be.

In the illustrated embodiment, a horizontal type salt bath furnace has been described, but this can also be a rigid type in which the heating/soaking zone 7 is at the bottom and the sealing rolls 4 and 5 are at the top.

As explained in the embodiments above, the salt bath furnace according to the present invention uses salt as a heat medium, so much of the heat used in the heating and soaking zone can be efficiently recovered in the heat exchange zone. It is used for preheating, and compared to conventional salt bath furnaces, the thermal efficiency is about twice as high, and the thermal energy consumed is about half, contributing to a very large reduction in fuel consumption and cooling costs.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view of a salt bath furnace showing an embodiment of the present invention. 1... Heated object, 2... Furnace body, 3... Reversing roll, 6... Partition wall, 7... Heating/soaking zone, 8a,
8b... Heat exchange zone, 9... Partition wall.

Claims (1)

[Claims] 1. A reversing roll is installed in a furnace filled with salt, and flexible objects to be heated, such as wire rods and metal strips, are stretched over the reversing roll and folded back to move the heated object from one side to the other in the furnace. The salt is transported in such a manner that the sides are approximately parallel to each other, and the part where the reversing roll is located is divided by a partition wall, and a heat source is provided to heat the salt in this part to make this part a heating/soaking zone. Furthermore, heat exchange is carried out between the opposing outgoing and incoming sides of the heated object by natural or forced convection of salt, and a partition wall is also provided in the heat exchange zone to prevent the heated object from being heated. An energy-saving salt bath furnace characterized in that the free flow of salt in the transport direction of objects is restricted by the partition wall.