USRE21745E - murray - Google Patents

Description

T. E. M URRAY March 11, 1941.

B0 ILER Original Filed May 31, 1923 2 Sheets-Sheet 2 5. Mun/m Y. A/VO' Thoma E. Mun/m y. m

Reissued Mar. 1 l, 1941 UNITED STATES PATENT OFFICE 21.745 BOILER Thomas E. Murray. deceased, late of Brooklyn, N. Y., by Joseph B. Murray and ThomaslE. Murray, Jr., executors, Brooklyn, N. Y., assignors to Metropolitan Engineering Company, Brooklyn, N. Y., a corporation of New York Original No. 2,042,618, dated June 2, 1936, Serial No. 642,427, May 31, 1923. Application for reissue August 5, 1936, Serial No. 94,490

8 Claims. (Cl. 122-235) i2, a'front wall It and rear wall l6, and-a top wall or roof I.

The side walls It and ii are formed of a series of upright units comprising tubes with lateral metal extensions such as the flanges ii, for instance, Fig. 4, welded, to the tubes or otherwise attached thereto with good heat conducting joints. Inner curved portions 21 partly overlying the tubes facilitates such a welded connection. The tubes 20 are connected into the circulation of the generator, communicating at the top and lzxittom, respectively, with hollow headers 23 and 1 The rear wall ll of the boiler is formed of a multiplicity of upright tubular sections 25 which maybe similar to the members 2.. II, or may be ordinary tubular headers. and which are united at the top and bottom to transverse headers l4 and (6 (Fig. 2) The hollow'members 20 forming the front wall are connectedat the top to a header u. sheet the bottom to a header u by communicating nipples orother suitable connection. The header II is elevated to leave an opening for the entrance of a known. type of stoker. Insteadiof such stoker, the boiler can be tired manually, in which case; flre doors and ash pit doors. not shown. will be provided. The boiler may be provided with a suitable grate dia-w grammatically shown at-Ql, Fig. 2, and bridge wall ll and boiler tubes 2 extending. approximatelyho'rlzontally overhead and heated chiefly by convection. their opposite ends with the hollow header members 25 and 2'. Suitable bailles it. such as tile, water tubes or brickwork, are secured in known manner to the boiler tubes so as to cause the products of combustion to follow a sinuous path through the boiler. v A flue opening it is formed in the roof, leading to the stack.

The tubular side walls are combined with .1.

outer layer or covering of refractory material, such, for exampleas the layer or sheathing H The tubes 82 communicate at of plastic insulating materlalheld in place by a reinforcement of woven wire mesh 18 which is bent to the shape shown in Fig. 3 and welded or otherwise at intervals 'to the tubular units, either the tubes ll or the projections 2i,

or both. This insulating material can be plastered onafter the metal work has been erected and, if desired, may be enclosed by a thin sheet metal shell. This insulating material may be a magnesia mixture of plastic compounds of asbestos and like heat insulators As shown in Figs. 3 and 4. the refractory makes contact with the metal structure throughout substantially the entire face of the latter so as to form a unitary composite wall structure of metal and refractory. The refractory portion conserves the-heat to subold type of furnace. The composite wall structure, by reason of the cooling effect of the tubes,

is maintained in condition and has a useful life many times that of the old refractory walls. Preferably the refractory material overlies the anchoring means at the outside. or substantially so, so as to prevent any substantial transmission of heat through the metal to the outer face of the wall; The'support which the refractory material derives from the netting or equivalent anchoringmeans is important particularly with boilers for power plants which are'generallyvery large and work at high temperatures and high pressure The furnace walls of such boilers are subject to noticeable and sometimes violent vibration and to distortion under the intense heat. The mere adhesion of the plastic to themetal-cannot be depended upon to hold the plastic in place. Even stantially the same extent as in the walls of the is apt to beg-displaced under the conditions of use.

The nettinglllustrated not onlyl holds the plastic insulation together but also'supports its weight from the; tubular structure.

The boiler tubes may be of the usual round shape secured to the hollow headers 25 and 28; these being provided withgopenings opposite the ends of the tubes. which openings are closed'by suitable plugs u- 1,1118 upright hollow corner tubes II are provided 'withplugged openings Ill which give access to the interior. Similar open lugs and plugs may be used in the various members forinsertlon oftools in assembling, or for cleaning sediment or scale.

Thefeed-water may be introduced at one or more points and for this purpose, I have shown in Fig. 1 a pipe-M entering the lower. header. Similar feed pipes may be located at the opposite side of the boiler, or the feed water can be where it is enclosed by-an outer shell of metal, it

supplied from a common header to several of the tubular members 20. a

. usual masonry wall; to the fire. I shows that such walls are rapidly deteriorated under modern high temperature firing.

The boiler walls may be supported in the usual manner on a floor or other foundation Or walls of the kind described can be hung or'suspended from the structural beams or girders in a power house or other building.

ilers of the present type are designed, to generatelarge quantities of steam at high. temperature' and pressure by the use of. water walls immediately surrounding the combustion chamher, and utilizing the radiant heat of the burning fuel in addition to the inclined tubes above the combustion chamber heated by convection.

The improved boiler is designed to produce steam at a rate of several hundred per cent of the usual rating based on area exposed to the heating gases and requires for this result a high volume oi intensely hot gas. It becomes im-, portant therefore to prevent the, exposure of the Experience The metal fillers or extensions of the improved boiler form a shield which protects any outside sheathing, the tubes with the metal fillers or extensions constitutingin effect a wall of the combustion chamber so thatthe plastic material on'the out-J side may be a mere insulating sheathing supported by the wall of tubes and fillers.

The fillers or extensions have an additional function to, conduct heatto the water tubes so rapidly as to utilize the intense heat of the fire,

In installations of this character the distance to i which the extensions maybe carried beyond thetubes is limited. It must be so short that the heat isconducted to the tubes sufficiently rapidly to prevent the outer portions of the-extensions from being burned away or distorted suilicientlybut is chiefly dependent on the distance from a present invention is an improvement, particularly to crack them. Such conduction of heat to the tube is afiected bythe area and the degree of contact of the extension member with the tube,

the tube to" the remotest part of the extension. Such distance puts a maximum limitation on the distance between the tubes in the case of high duty boilers (that is, steam generators as distin'guished from mere water heaters or the like).

In practice, it is found that the maximum distance should not be substantially greater than the outside diameter of the tubes. The extensions beyond the tube, with such spacing, are of less width than the diameter of the tubes and 5 can be kept within such limits as to avoid destruction by the fire.

Generally in boilers of the type on which the those designed to generate large quantities of steamat high temperature andpressure, the

walls ofth'e furnace support the overhead'structure and are made of or lined with refractory brickwork which'is exposed directly to the intense heat of the flame and which have a com-,

parativelyfshort life." There are frequent .shutdowns for repair or replacement of, such walls. The walls. of course, haveto be maintained in good order to support the weight on themf It has been proposed also to use furnace walls of composite character, including refractory material and water tubes, as lnthe patent of Hutchison, No}. 614,206, of November 15, 1898, and of gewall, No. 1,090,947, of March 24, 1914, where the walr'is made'of tubescombined with refracwry material on the inner faceand the outer' face. i r

3. YA stationary steam generator including in According to this invention the principal partof the wall is the tubular metal structure and the refractory material is anchored to and supported thereby. The netting embedded in'the plasticrefractory coating anchors the latter in place against the face of the metal wall and prevents its being loosened orwseriously damaged by the vibration or the slight relative movement of the tubular elements which occur in the use of large installations of this type. Not only does this! provide for a high capacitybecause of the rapid generation of steam in the tubes; but also the 1 life of the composite structure of metal and refractory is practically unlimited because of the chamber below said overhead tubes, a'wall of said 25 combustion chamber being composed ofgsubstantiallyupright tubes connected into the circulation of the generator, said tubesbeing spaced apart a distance not substantially'greater than their diameter, and metal extensions from said 3 tubes united thereto with *good heat conducting joints and practically closing the spaces between them but being free to move separately, ,so that only the tubes and extensions are exposed to the heat of the burning fuel and the two together constitute the wall heated only on its inner face, the other surface of such wall being covered with insulating'material.

2. A steam generator including in combination water tubes heated by convection, and a furnace having a combustion chamber adjacent to said tubes, a wall of said combustion chamber being composed of water tubes connected into the circulation of the generator, said'tubes being spaced apart a distance not substantially greater than their diameter, and metal extensions from said tubes attached thereto with good heat conducting joints and practically closing the space between them but being free to move separately, so that onlyv the tubes 'and extensions are exposed to the heat of the burning fuel and the two constitute a wall heated only on its inner face, the" outer face 'of said wall' being covered with insulating material.

combination water, tubes heated by convection" and a furnace having a combustionchamber, a wall of said combustion chamber being composed of a number of substantially upright tubular,- elements comprising tubes with lateral metal extensions united thereto with goodheat conducting joints, said tubes being connected into the circulation of the generator and beingspaced apart a distance not substantially greater than their diameter and said extensions lying in the spacesbetween the tubes and providing an increased area exposed to the radiant heat of the burning fuel and conducting such heat to'the tubes, said extensions being limited in width as 70 a maximum to the diameter of the tubes, each outer surface of such wall being covered with insulating material. 1

4. The stationary steam generator of claim 3, and means for holding said cover of insulating material against the outer surface of the wall, such means being united to the tubular elements composing the wall.

5; A steam generator including a "furnace having a combustion chamber, a wall of said combustion chamber. comprising substantially upright tubes connected into the circulation of the generator, said tubes being spaced apart and having metal extensions united thereto with good heat conducting joints and extending into the spaces between said tubes to substantially close said spaces but leaving said tubes independent one of the other, the inner face of the wall formed by said tubes and extensions being exposed to the heat of the combustion cham-f her. the outer surface of said wall being covered with insulating material and continuous anchoring means connected at intervals to the outer surface of said wall of tubes to hold,said insulating material in close contact with the sur. face of said tubes and extensions.

6. A water wall for a combustion chamber which comprises spaced vertical water tubes having sidewise metal extensions into the spaces betweensaid tubes substantially to fill said spaces while leaving said tubes independent one of the other, the inner surface of said wall facing said combustion chamber and a continuous insulating covering for the outer surface of said wall having attaching means extending continuously throughout said insulating covering and attached at intervals to said tubes by welding to .hold said covering in close contact with the sursaid upper and said lower header to form a substantially continuous wall having an inner surface exposed to the heat of said combustion chamber and a continuous insulating covering for the outer surface oi said wall and attaching means extending continuously in said covering and secured at frequent intervals to the outer surface of said water wall where the wall encloses said combustion chamber.

JOSEPH B. MURRAY. THOMAS E. MURRAY. Ja. Executor: of the Estate of Thomas E. Murray,

Deceased.

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