US2374377A

US2374377A - Pyrometer tube

Info

Publication number: US2374377A
Application number: US481901A
Authority: US
Inventors: Percy James Ward
Original assignee: United States Steel Corp
Current assignee: United States Steel Corp
Priority date: 1943-04-05
Filing date: 1943-04-05
Publication date: 1945-04-24
Anticipated expiration: 1962-04-24

Description

April 24:, 1945. 1 w, PERY 2,374,377

PYROMETER TUBE Filed April 5, 1943 INVENTORJ JM ika/30 PEECV.

5//5 firme/VU Patented Apr. 24, 1945 PYROMETER TUBE James Ward Percy, Jersey City, N. J., assignor to United States Steel Corporation of Delaware, a

corporation of Delawarc Application April 5, 1943, Serial No. 481,90l

(c. rss- 4) 1 claim.

This invention is concemed with the problem of determining the heating rate of a metal charge in a metal heating furnace. For example, the hot-roliing of steel slabs requires heating the slabs to a proper hot-rolling temperature, this involving the necessity for determlning how long the slabs should remain in the furnace used to i bring them to such a temperature, or, in other words, the heating rate of the. slabs in the furnace.

The principles of the invention are illustrated by the accompanying drawing in which: v

F gura 1 is a partial cross section of a. continuous slab heating furnace with the invention v in operation;

Figure 2 is an enlarged longitudinal section of a detail from Figure 1;

Figure'3 is an elevation of Figure 2;

Figura 4 is a side view of Figure 3; and

F'gure '5 is a cross section from the line V-V in Figure 4.

More specifically, this drawing shows a partial cross section of a conventional continuous steel slab heatingfurnace l having a hearth 2 over which the slabs 3 are intermittently pushed transversely through the urnace, the furnace being provided with the usual series 'of observation ports 4 permitting observation of the slabs as they progress through the furnace. The various specific features involved are familiar to anyone skilled in the art.

Heretofore, the customary way of determining the heating rate of the slabsas they progress through the fumace has been to measure the external surfaces of the slabs as they pass'by the port 4, the data obtained in this manner being used to regulate the temperature and time values of the slab heating cycle to assure the slabs reaching a proper hot-rolling temperature just prior to their leaving the iumace. Frequently, the urnace is provided with an automatic photocell radiation pyrometer with its cell 5 sighted through a tube 5 on the slab surfaces at a position near the furnace slabexit, in order to determine that the slabs have in fact attained a hot-rolling temperature before they leave the furnace.

The outlined procedure involves the problem that it has been impossible to determine whether the slabs were heated throughout to the desired temperature, the heating rate of the slab surfaces being the only thing determined and this notproviding an adequately safe guide 'to the internal heating rate of the slabs. That is to say, hot rolling requires the slabs to be heated throughout to a proper hot-rolling temperature( yet the prior art has provided only for determining the heating rate of the external slab sui-faces, this involving the necessity for calculating the internal slab temperatures instead of knowing them definitely.

According to the present invention, when it is desired to determine the heating rate of the slabs, a hole is drilled to the geometrical center of a representativ one of the slabs as at 6. This V hole is drilled from the side of the slab that passes opposite the ports 4 in such a manner that the hole attains axial alignment with these ports. As the slab passes successively by the various ports a thermocouple is slid in the hole 6 to the geometrical center' 'of the slab and a temperature reading is obtained of the actual internal temperature of the slab, this involving conventional use of the thermocouple so far as obtaining the temperature value is concerned. In this fashion it is possible to obtain the heating rate at spaced time intervals of the actual inside of the slab at a point where the heat has the most difiiculty of reaching. Preferably, the external heating rate is -determined in the conventional fashion knowledge of the actual heating rate of the slab both extemally and internally as it progresses through the furnace. Obviously, any other furnace charge involving the same problem can be handled in the same fashion, and the principies involved may be applied regardless of whether the furnace is of the continuous type 'or the charge remains stationary in the furnace durin its heating. It is only :necessary to measure the internal temperature of the charge at spaced time intervals to provide the information discussed. The resulting information may be used, for examples, to adjust the time and temperature values of the heating cycle, to test a' new furnace design, or to indicate that an old furnace needs redesigning.

Preferably, special equipment should be used in carrying out this invention. With this in mind, the thermocoupleis positioned in a quartz tube 1 having a closed end 8 and with its other end open to permit passage of the necessary leads to the thermocouple, these leads and the thermocouple not being illustrated because they may follow conventional design. Heat-resisting cement 9 fastens the tube 'I concentricall'y inside a larger tube I 0 made of heat-resisting metal, such a !8-8 or 25-42 chromium-nickel stainless steel, and having a tapered end extending beyond the closed end 8 of the quartz tube 'I so 2 as to protect this relatively iragile part, the end H oi the tube o being tapered to permit its easier guidance into' the hole in the slab. The

arrangement is such that the outside of the tube 'lis spaced from the inside of the tube o, in the interest of adequately protecting the tube 'I from damage. the tube III having side openings oexposing the tube 'l directly to the slab heat. The tube I! is provided with a threaded end |2 opposite the end II and this threaded end is arranged in' screw threaded engagement with a pipe Illb, also 'made of heat-resisting metal. which is of adequate length to project the tube n to'the geometrical center of the slab by way of the hole in the latter from a position conveniently outside of the port I being used at the time.

A water-'cooled tubular jacket !3 is provided with a vertically adjustable frame 'll carried by a wheeled carriage IS, this permitting the jacket I! to be wheeled up to the port 4 and the jacket I: then thrust through this port, 'the jacket !3 having a sufllciently large inside passageway to permit projection therethroughot the pipe III carried on the end of the pipe lub, the endof the jacket I: being positioned close to the side of the siab having the hoie 'so that the pipe Ilb is to get the thermocouple to the inside of the :lab

and withdraw it as quickly as is consistent with obtaining an accurate temperature measure-` ment.

The quartz tube 'I is used to protect the thermocouple against the fumace atmosphere because it conducts heat with adequate rapidity. Actual use of equipment such as disclosed has shown that the disclosed protective features for these parts are adequate to make its use completely practica1..

. I'clain:

'I'he'combinatio'n of a closed end for enclosing a heat radiation responnot directly exposed to the furnace heat. The

jacket I: is provided with a heat shield IS for the comfort of the operator,'and is pivoted to the Irame M. and provided with a counterpoise I'I, whereby the operator may have-some 'leeway in verticallyaligning the jacket with the slab, other than by vertical adjustment of the frame il.

I Furthernore, the passageway through the jacket sive device, a heat-resisting metal tube enclosing the quartz tube and having 'at least one side i .opening exposing the quartz tube. and heatextending beyond the closed end of the quartz tube.

JAMES WARD PERCY. I

quartz tube having a