US1296739A

US1296739A - Superheater.

Info

Publication number: US1296739A
Application number: US3168915A
Authority: US
Inventors: John E Bell
Original assignee: Individual
Current assignee: Individual
Priority date: 1915-06-02
Filing date: 1915-06-02
Publication date: 1919-03-11
Anticipated expiration: 1936-03-11

Description

J. E. BELL.

SUPERHEATER.

APPLICATION FILED JUNE 2. I915.

Patented 2 SHEETS-SHEET 1. F Z.

INVENTOH WIT'N ESSES J. E. BELL.

SUPERHEATER..

APPLICATION FILED JUNE 2. 1915.

Patented Mar. 1], 1919.

2 SHEETS-SHEET 2.

INVENTOR WITNESSES 7% Q? M Ol) (3T Uni/H3 voluine of the furnace emit radiant energy in a E. BELL, or NEW YORK, N. Y.

suPEnHEATnn.

To all whom it may cmicem:

Be it known that I, JOHN E. BELL, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented a new and useful Improvement in Superheaters, of which the following is a full, clear, andr-exact description, reference being had to the accompanying drawings, forming part of this specification, in which:

Figures 1, 2 and 3 are sectional views of a portion of a furnace embodying oneform of my improved superheater; Fig. 3 being taken on the line III-4,11 of Fig. 2, and Fig.

showing a portion of said Fig. 1 on a larger scale; p i

Fig. 4 isa view similar to Fig. 1,- but showin a modification; v

iig. 5 is a section on the line VV of Fig. 4:; i

Figs. 6 and? are sectional views showing another" form of my invention; and

Figs. 8, 9'and 10 are detail views here1n fafter more fully described.

I S My nvention has relation to superheaters,

and is designed to provide a superheaterv which is located in one of the side walls or in the roof of a furnace, the superheatcr to be in whole or in'part out of the path of the furnace gases, ,and the heat absorbed thereby to be in a large part radiant heat. To utilize radiantheat in'this way, it is necessary, that some portion of the surface or combustion ofthe illuminants or flame in the furnace.

Heat is (transmitted from a hot to a cold body which are separated in two ways: first,

tion.

by the combination of conduction and convection in the intervening, medium; and second, by radiatlon or the transfer of .heat

through a wave motion in the ether. Heatagainst a rush of cold air inward is radiant heat and isgin sufficient amount to quickly burn and blister the fireman unless he protectshimSeIf. In ordinary boiler work from twenty-five to fifty per cent. of the total Specification of Letters Patent.

tween the driving firebrick 6. Back of the Patented Mar. 11, @919.

Application filed June 2, 1915. Seria1 No. 31,689.

heat absorbed by the boileris radiant heat, and comes from the surface of the fuel bed; or if there is a sensible flame in the furnace, part of it from the carbon particles constituting the flame. This .portion of the heat is absorbed by the heating surface exposed to the furnace. There is also some radiation from the brick work of the setting, but; the amount of heat emitted by a hot body through radiation diminishes rapidly with a falling temperature. In a general way, the radiation is determined by the application of Stefans law, and is proportional to the fourth'power of the absolute temperature.

It is consequently obvious that the amount of heat that is transferred by radiation is more or less negligible, except where the temperatures are high.

. My invention provides a super-heater hav ing many practical advantages, some of which will be hereinafter more particularly pointed out.

Referring first to that form of my invention shown in Figs. 1, 2 .and 3, in which I have shown the superheater located in the roof of a furnace, the numeral 2 designates a furnace and 3 the furnace grate. 4 designates superheater tubes, arranged in parallel, and which may be of the ordinary drawn steel manufacture, but which are surroundedby a metal casing 5. p This casing preferably consists of a plurality of sections of cast iron. Adjacent tubes 4 are separated from each other by-intervening sections 6 of firebrick or other refractory material.

Each section of the cast iron casings 5 preferably has a bottom or face portion 5 of a shape to completely fill the space bebottom or face portion, each casing pref-- erably has a reduced neck portion 5 which joins it to that part of the casing which. immediately surrounds the superheater tube 4. The purpose of this neck is to provide means for controlling the amount of heat which flows by conduction to the superheater tube. The amount of heat absorbed by radiation diminishes as the temperature of the absorbing surface increases, and the temperature 'of the absorbing surface will be increased as. the area of this neck is diminished. Therefore, by reducing the size of the neck a very material reduction can be made in the amount of heat reach ing the superheater. The metal in those portions of. the casing sections immediately surrounding the 'superheater tubes is of sufiicient mass to permit, the conduction of heat to all sides of the tube and to insure its being taken up by the-tube. The casing Y supported by the casings, and these, in turn,

are supported by the hook bolts 8 from the overhead beam 9, the tubes, casings and refractories constituting the entire roof.

It is unnecessary to provide a hook bolt for each section of the casing, but they should be used at proper intervals to prevent any warping or bending of the tubes. In fact, one of the important advantages of this method of construction is the preventing of the tubes from getting out of line. The firebricks 6 not only form a part of the furnace roof, but they preferably extend considerably below the face portions 5 of the casing sections, so that they shroud or protect the supefheater to a certain extent from the radiations, and thus afford another means of regulating the intensityof the heat absorption.

In Figsafl and 5,-the superheateris shown as arranged in the wall 10 of the'furnace opposite the checkerwork outlet 11. The snperheater, is constructed in substantially the same manner as in the preceding figures, but in this case, the sup-port back of the superheater tubes consists-of a buck-stay 12, to which thebol-ts 13,connected to the casing sections, are secured. By locating the superheater directly opposite the checkerwork, the checkerwork is prevented from becoming overheated and the location and arrangement is a very practical and desirable one.

Another form of my invention is illustrated in Figs. 6, 7 and 8, in which I have shown the superheater as located in the side wall of a. boiler furnace and boiler of the Stirling type. In this form of my invention the superheater tubes 1% are of U-form and are stifi'ened against bending or warping by a cast iron casing lti, generally similar to the casing before described, except .that one casing is common to at least both branches of one U-tube. Preferably, the casing is made up in separate sections for each Utube, although it may be in one piece. The area of the casing around and between the tubes is sufficiently great to permit the rear tube to be heated bythe conduction of heat in the usual way through This feature of the cast iron around it. my invention, namely, the protection of two or more adjacent tubesagainst bending or warping by a cast metal casing may also be used to advantage in water tubes.

In Figs. 9 and 10, I have shown another mcans for regulating the degree of superheat. This device consists of a movable firebrick shutter 16, with refractory portions 17, extending between adjacent tubes, and which can be moved relatively to the tubes, so as to expose them to a greater or less extent to the heat.

The heat absorbed by a supcrheater located in the usual way is entirely by contact with the gases, and as a consequence, a relatively large amount of surface must be provided, while I expose the snperheater directly to the radiations from the furnace.

To increase the surface exposed and also to' obtain a material that can withstand high temperatures, Iv surround the ordinary superheater tube with a heavy cast iron casing. The face of the casing 5, as shown in Fig. 3, is, in width, for instance, over twicethe diameter of the steel tube and since the projected area only is effective in absorbing radiation, the surface exposed is practically double,

The heat absorbed by the face 5, of course, raises the temperature of the portion of the casing marked 5, and if there were no loss of heat, this portion would eventually assume a temperature equal to that of thcfire and would be melted and burned away. Since, however, iron is a good conductor, the heat absorbed by the face 5 is carried back through the metal and finds its Way out through the super-heater tube into the steam.

The difference in the temperaturebetween the face 5 and the superheater tube will depend upon the resistance to the conduction of heat between the two parts. This, in turn, depends inversely on the conductivity of the metal and the area provided for the If, therefore, either the conductivity or the area is reduced, the temperature of the face 5 will be elevated as compared with the temperature of the superheater tube. By increasing or diminishing the amount of metal in the neck 5*, the temperature of the face 5" can be made higher or lower at will. Asthe temperature of the face. 5 increases, the amount of .heat that. it re-radiates back to the furnace, according to the law of interchanges, increases, and as a consequence, the net amount of heat absorbed by radiation diminishes.

My invention provides a :superheater which can be located conveniently in the setting of the furnace. Under ordinary conditions, it reduces the area of the heating surface very materially, and thus effects a great saving in cost. It also, as has been described, permits the use of simple means whereby the superheater can be adjusted at will. 1 This has not heretofore been possible except in special instances, and by the use superheater may be widely varied in diiferent furnaces, Without departing from the spirit and scope of my invention asdefined in the appended claims.

I claim: 1

1. A furnace having a superheater located in one of the walls thereof, a heat conducting casing surrounding the superheater and within the Walls of the furnace, a portion of the outer face of said casing being exposed to the radiant heat of the furnace, substantially'as described.

2. A furnace having a superheater located in one of the Walls thereof, a metallic heat conducting casing surrounding the superheater and Within the wall of the furnace, a

ortion of the outer face of said casing bemg exposed to the radiant heat of the furnace, said casing having a reduced portion between the exposed face and the superheater incased therein to conduct the heat from the exposed face to the superheater, substantially as described.

3. A furnace having a superheater located in the roof thereof, a metallic heat conducting casing surrounding the superheater and Within the roof of the furnace, a portion of the outer face of said casing being exposed to the radiant heat of the furnace, said casing having a reduced portion between the exposed face and the superheater incased therein to conduct the heat from the exposed face to the superheater, substantially as described.

4. A furnace having a superheater comprising a series of superheater tubes and a solid metal casing for said tubes, said casing having a body portion, a head portion arranged to be exposed to the radiant heat, and a neck portion connected to the body portion and the head for conducting the heat from the head to the body portion, sub stantially as described.

5. A furnace having a superheater comtion arranged to be exposed to the radiantheat, and a neck portion connected to the body portion and the head for conducting the heat from the head to the body portion, substantially as described.

6. A furnace having a superheater comprising a series of superheater tubes, metal casing surrounding said tubes and arranged to conduct heat thereto, and refractory dividing members intermediate the casings of the different tubes, and arranged to prevent the major portions of the bodies of the casings from being exposed to the radiant heat of the furnace, substantially as described.

7. A furnace having a superheater comprising a series of superheater tubes, metal casings surrounding said tubes and arranged to conduct heat thereto, refractory dividing members intermediate the casings of the different tubes, and arranged to prevent the major portions of the bodies ofthe casings from being exposed to the radiant heat of the furnace, means for supporting said casings, said casings being arranged to support the dividing members, and projections on the dividing members arranged to engage the metal casings to support them in posi-' tion. substantially as described.

8. A metallic superheater easing having a body portion, a head portion, and a reduced neck portion connecting the head to the body portion, substantially as described. 1 9. A superheater having a plurality o tubes, metallic superheater casing members I having openings therethrough through which the tubes of the superheater extend, superheater supports, and means for connecting some of the casing members to said supports, substantially as described.

In testimony whereof I have hereunto set my hand. A J OHN- E. BELL.

Witnesses:

ELIZABETH ARMSTRONG, F. FALLA,