US2023646A - Tubular heat exchange apparatus - Google Patents

Description

Dec. 10, 1935. H. A. RICHARD TUBULAR HEAT EXCHANGE APPARATUS Filed Aug. 11, 1934 Patented Dec. 10, 1935 UNITED STATES PATENT OFFICE TUBULAR HEAT EXCHANGE APPARATUS Henri Andr Richard, Tram France Application August 11, 1934. Serial No. 739,481 In Great Britain August 1'1, 1933 This invention comprises improvements in and connected with heat exchange apparatus and particularly water tube boilers or heaters. In. this type of boiler or heater, the tubes are usually" 5 spaced apart, and individually .jointed in theheadersor tube plates, so that the flames play all around the tubes. partly due to conduction arising'from direct contact of the flame with the metal of the tubes and contact with the metal. Therefore, it is possibleto reduce the size of boilers or heaters or to increase their efficiency by eliminating the spaces between the tubes.

According to this invention the tubes of a water tube boiler or heater are assembled so that each tube, excepting the end tubes, is in contact or metallic connection with two neighbouring tubes along its length. Each tube assemblage may be connected with a collector or header at each end.

Thus, each tube assemblage constitutes, as it were,

a wall filled with water ducts, this structure having a greater capacity for rapid'heat absorption than one composed of spaced tubes. This is due to the fact that, inthe plane of the tubes, the

flame is-everywhere in direct contact with a cooling surface.

The heat absorption is greater than can be obtained'with double flat walls with water between,

because the cylindricalform of the tubes presents a greater surface area for contact than that presented by flat walls, The tube structure in accordance with these improvements conduoes to a better distribution of the gases of combustion which can be induced to make an extensive or I long contact with the surfaces to be heated.

Thus it is possible to have a progressive diminution of the temperature of the gases down to a minimum compatible with the draught.

With tubes of small diameter and sufllciently intense heat, an emulsion of water and vapour is produced within the tubes which results in an exceedingly active circulation of water in the boiler or heater. In fact, the tubes become'fllled with beads of water and vapour so that an energetic 50- displacement occurs.

A structure composed of tube assemblages as aforesaid combines the advantage of good circulation of water tube boilers with the advantage of good heat absorption of boilers having continuli ous metal walls.

Thus, the heat exchange is" If each tube of an assemblage had to be tightly jointed in a header or tube plate. the tightness could notbe relied upon. Thus, if the joints were to be welded it would be essential that the welder should be able to pass the welding flame all around 5 7 each tube end. Autogenous welding of an assemblage of tubes might be faulty as leaks might occur along the irregular welding line which could not be repaired.

The invention therefore provides for the weld- 10 ing of the ends of the tube assemblages to form blocks, before jointing or welding them in the header. Thus, these end blocks only require welding along lines, and this operation, which can be performed with ease and great facility, rel5 suits in a very reliable jointing of the parts.

The invention is particularly advantageous when the improved heat exchange device is employed in connection with furnaces in which gas or gasified combustible matter is consumed. In 20 such furnaces the flaming combustible is more highly aerated and combustion is more perfect and complete than is the case with coal, as the burners aspirate, or are supplied with, the proper quantity of air. Owing to this perfection of com- 25 bustion, the flames have a minimum of development, and with such relatively short flames it is necessary to present heat absorption surfaces having a maximum eiiiciency and occupying a minimum of space. These requirements are satis- 30 fled by a structure in accordance with these improvements. Moreover, these structures are economical to produce and offer a minimum of resistance to water flow or circulation.

This invention is particularly advantageous in 35 its application to boilers of relatively small capacity, such as are employed for central heating purposes and especially in dwelling houses and flats.

In order to enable this invention to be readily 40 understood, reference is made to the accompanyingdrawing illustrating one practical example of a heater construction in accordance with the present improvements, in which drawing:--

Figure 1 is a perspective view of a tubular element of a heater, the lower part of the figure showing how the said tubular element may be united to a header.

" Figure 2 is a vertical section, on the line II-II of Figure 3, of a heater embodying two elements of the kind illustrated in Figure 1.

Figure 3 is a horizontal plan section on the line 111-111 of Figure 2.

Referring to Figure 1, the tubular element therein illustrated comprises five tubes a held 66 or joined together to form a tubular wall, each of these tubes, excepting the end ones, being in contact with two neighbouring tubes along lines parallel with its axis. Each of the two end tubes, of course, is in. contact with only one tube. An assemblage of only flve tubes would provide a very small heater element and in practice a greater number would usually be employed, as will appear from the description of Figures 2 and 3. The tubes a may be of any suitable metal or alloy, copper or steel being suitable for ordinary purposes. Moreover, the tubes 11 instead of being in contact only along the lines aforesaid, may be put into metallic connection along such lines, as by means of welding, brazing, or solder- The tubes (1 may be held together in contact with one anotherby any suitable means, as by welding, brazing, or soldering at the ends. In view of the difficulty which might be experienced in making a tight joint between the cylindrical tube ends of an assemblage and a header or junction chamber, such as b, these improvements provide for the formation of blocks a at each end of a tube assemblage. As seen in Figure 1, the block 0 is formed with straight parallel sides and rounded ends 0 but the ends may be straight in which case the blocks would be rectangular. These blocks c may be formed by casting metal on the tube ends of the assemblage, or they may be formed or applied by an autogenous welding operation. An aperture d is formed in a wall or plate of the header or chamber b, this aperture having a shape and dimensions similar to those of the block 0. A block c is introduced into an aperture (1 and is readily jointed to the wall or plate of the header or chamber b by means of a line of welding, brazing or soldering e. By this means, a very tight and durable joint is produced with great facility and economy, as the workman has only to follow straight or regular lineswith his welding or other tool and the difllculty of welding all around the closely disposed cylindrical surfaces of numerous tubes is avoided.

Figures 2 and 3 illustrate a water heater embodying two tubular elements a a of the kind described with reference to. Figure 1, but'with many more tubes in each element. The tubes are of small diameter in order to obtain the greatest efliciency with a heater occupyi the smallest possible space. Thus, in the example illustrated, the heater may have a height of very little more than one metre and a width across the tubular elements a a. of about twenty centimetres, each element comprising 14 tubes. Naturally, more tubes may be used for each element and small tubes of other diameters may be employed, the particulars of the example illustrated being given in order to show the nature of the tubular elements with which this invention is principally concerned. The two elements a a are mounted within a casing g of appropriate material, the element a being supported at a short distance behind the element a and slightly elevated. The top and bottom headers b of the element a are connected to the top and bottom headers of the element a. by pipe bends f sothat the flow through these elements is in parallel, the inflow-taking place into the bottomheader of the element a at 1 and the outflow h being connected with the top header of the element a.

The said inflow j and outflow n my be connected water.

with a heat radiator or system of radiators of a central heating system for a house. At the foot of the casing g and in front of the element a a gas burner It extends across the width of the element, the said burner being ignitable through an aperture 1 and the condition of the flame being observable through a window m. The flame from the burner is may be relatively short but the path of the flame and gases of combustion is extensive, for the said path passes up in front of 10 the element (1!, down between the elements a and a and up behind the element a to the outlet 0 at the top of the casing as indicated by arrows. This extensive flow of the hot gases over the large surface areas presented by the tubular elements, has 15 the effect of producing the intense heating of the elements and the lively circulation of water therein, in the manner hereinbefore explained.

It is presumed that the bubbles of vapour, I formed in the tubes at according to the intensity 2 cf the flame in the heater, can only rise by displacing the water vertically, because the diameter of these tubes approximates to the diameter of the bubbles of vapour. There are created as many vertical currents as there are tubes of 25 The heater strongly draws in cold water and energetically delivers the hot water, it acts as a pump in the central heating system, in creating a high speed of circulation of water, without setting up local resistance. This activity of circulation increases the efllciency owing to the fact that colder water is led into contact with superheated metal walls.

I claim:-- 1. Tubular heat exchange apparatus comprising a tube assemblage having a number of tubes in conductive connection with one another along their lengths to provide heat absorption surfaces and blocks formed on the ends of the tubes.

2. Tubular heat exchange apparatus compris- 40 ing a tube assemblage having a number of tubes in conductive connection with one another along their lengths and blocks formed on the ends of the tubes, headers having apertures to receive and fit around the blocks, and metallic jointing be- 45 tween the blocks and headers at the edges of said apertures.

3. A heater comprising an outer casing, a plurality of heat exchange elements each comprising a tube assemblage having a number of water tubes of small diameter in conductive connection with one another along their lengths and headers at the ends of each tube assemblage, the several elements being arranged vertically in the casing in horizontally spaced relation and one higher than another, means connecting the headers to provide flow of water through the several elements, and heating means at the bottom of the casing in front of the foremost heat exchange element.

4. A water heater comprising a screen of tubes extending across the heating chamber, said screen being composed of a number of tubes of small diameter assembled side by side in contact with'one another along their lengths to provide 55 an unbroken heat absorption surface over the whole area of the screen, said tubes being held in the desired assemblage without deformation by metal bondings at their ends, which bondings serve also as connectors for the screen in headers o of the'heater. HENRI ANDRE RICHARD.

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