US2249301A - Flue gas heat exchanger - Google Patents

Description

Jul 15, 1941.

H. SIMMON Y 2,249,301 FLUE GAS HEAT EXCHANGER Filed June 15, 1936 2 Sheets- Sheet 1 Ifiven 'oPL 8' Haws 94377577072 AZ Z O/fij'ey y 5,1941. 7 H; SI'MMQN 1,249,301

BLUE GAS HEAT EXGHANGER Filed June 15, 1936 2 Sheets-Sheet 2- 46 Edi 7 34% 36\;

Hand 95177 2710 2 Patented July 15, 1941 UNITED STATES PATENT OFFICE FLUE GAS'HEAT EXCHANGER Hans Sir'nmon, Vienna, Austria Application June 15, 1936, Serial No. 85,387

In Austria June 28, 1935 7 Claims.

'it is hardly possible to keep the same permae nently fluid-tight. Y

The present invention relates to a rotary flue gas heat exchanger for pre-heating feed-water, generating steam, and superheating steam, the exchanging elements of which consist of a plurality of heating tubes closed at their outer end, and connected with their inner ends to a hollow shaft in such a manner thatthey aredispos'ed radially'or after the manner of spokes and communicate with the exit end of the bore of the hollow shaft to form an outlet system. i The invention further consists in providing inthe interior of the heating tubes admission pipes which extend almost up to the closed end of they heating tubes, and which are either connected into a length of tube disposed with clear ance in the hollow shaft so as to admit of the inflow of the medium to be heated or otherwise adapted to communicate with the entry end of the hollow shaft to form an inlet sys'tem' communicating with the outlet system only-through the said admission pipes and heating tubes. the intermediate space formed between the admission pipe and the heating tube there may be provided (as is known in connection with stationary heat exchangers) inclined blades which on the one hand hold the admission pipe fast in a central position, and which, on the other hand, may be adapted to impart an additional rotary motion to the medium to be heated in the revolving heat exchanging vessel, with the result that the rate of heat transmission is increased, such blades being shown by way of example,at 39, in Fig. 4 of the accompanying drawings. Such blades preferably extend or are distributed over substantially the wholelength of the said intermediate space. In order'to still further increase the thermal efi'iciency there may be provided in the casing a. rake the prongs of which constitute a baflle for the flue gases car-' ried along by the 'heating'tubes, so that these gases are constantly eddied, with the result that not-only is'efiective heat delivery obtained but in addition the formation .of an insulating deposit of soot 'and' flue ash is prevented. 'At a part of' the system at which the flue g'ases'liave become greatly cooled down the tubes maybe I providedwith ribs which enable the total area of the 'heating' surface to be increased,-an d whichfi' if they be disposed obliquely; canalso be ar-' ranged to act as blower fans to accelerateth Y movement of'the flue gases. 'In' order to pre vent an excessive increase in the salt-content of the water due to evaporation there is provided a salt-eliminating pipe which is in perma-' nent communication with the water space inside" the hollow shaft, and the bore of which is regulable to suit the rate of water discharge. To

avoid loss of heat by radiation, the casing surrounding the rotary exchanger is preferably enclosed by a jacket beneath which (as is known in connection with furnace plant) there is 'a' hollow space for an insulating layer of air, from which space the air, as it becomes heated, may be fedywith the aid of a blower, as pre-heated air for'combustion, to the furnace. The-favor able co-operation of all these measures makes it possible for the apparatus to be built with'very small heating surfaces, which is'of importance i from the economic point 'of view, more particularly. in conjunction with very high pressure boilers.

Forms of construction embodying the invention are shown, by way of example, in theaccompanying drawings, in which: i Fig. 1 shows a heat exchanger in accordance with the invention, in vertical longitudinal section.

Fig. 2 is a vertical transverse section of the same heat exchanger, on a reduced scale. 3

Fig. 3 showsone half of a heat exchanging member in accordance with the invention, as seen in an axial direction, on an enlarged scale. 1 Fig. 4 shows a part of a modified form of construction, in vertical longitudinal section.

Fig. 5 shows a further modification, in a simi-- 1arview.-

In the form of construction of the;appliance according to the invention shown in Figs.-1 and-2 I fit in stuifing-boxes pertaining to the'pipes (not shown in Fig. 1) forthe feeding in and discharg canbe driven; from a source of 7 power.

ing of the water and/or steam. The heat exchanging elements consist of heating tubes 6 disposed radially in the manner of spokes, closed at their outer ends, and communicating with the interior of the hollow shaft I. Within each of the heating tubes 6 there is a smaller bore admission pipe I the outer end of which extends almost up to the closed end of the heating tube 6, while the inner end, in the case of the first ofthe star-shaped sets of tubes, adjoins a closed tubular extension at the end 2 of the shaft I and communicates, through the bore of this extension, with the water feed pipe, and in the case of the remaining sets of tubes adjoins a length oftube Ill or II which is inserted in the hollow shaft I within which it fits tightly by means of a flange 8 and 9, respectively, and which is closedat its end. Each of the lengths of tube I carries a.-

set of tubes for pre-heating and steam generation, while to the length of tube I I there are connected aplurality of such sets oftubes serVing-forjthe superheating of steam. Atthe end '2;ofthe;hollow, shaftI there is secured 'acord pulley ljlwhich 'I'herrotary: exchangerjis enclosed in a casing I-3;-beneath which thereislocated .a fire arch I4 and aggrate I5; The furnace may alternatively'besituatedat' the side, it; being merely necessary-thatthe casing beinterposedin the path ofjflow-of'the fluegases coming'from-a furnace; Intheupperpart of the casing there, are provided bars I6 which; constitute a. rake engaging between the sets;of tubes, to prevent flue gases from becoming -carrie d;round withthe heatingtubes B, and1to effectthrougheddying of-these gases. The cas-. ing- Iiis made-from heat-insulating.material; or jacketediwi-th suchmaterial; and itais in addition enclosed within a shell IIiwhichis spaceda cer-' tain distancefrom the casing to form an-inte're veningzair, space, so that an insulating layer'of air issituatedbeneaththis shell; The flue pipe connection I8 on the casing containsan: adjust.- abledamper I9. which servesto regulate-the rate ofx'gas escape, and5which if desired may. be auto-. matically controlled:in dependence on the'stam pressure. The shell It! is provided withafpipe connection through which .the heatedair: may be drawn off and: fed tolthe furnace as. preheatedi'air-for combustion. In a region lessexposedto the. action of the flue-gasesthe heating tubesimay, beprovided with ribs 21' (Fig. 3')- which,-. as indicated? by the transverse section shown in chain-dotted lines on the right in Fig. 3;

mayiif desired be obliquely. disposed; so thatthey actras blower blades, to accelerate the flow of the flue gases. Y

Themode of operation of the heat exchanger shown-in the drawings-is as follows:

The flue gases rise from the furnace, and-are caughtyup byethe rapidly. revolving heating tubes 6 and thoroughlyeddied. At'the same time these gases; are. movedfforward helically in an axial direction whilebeing gradually. cooled oil. Final-- 1y, the-gases are forced out through the outlet I8: Water entering. at theend 2 of the hollow-shaft passes into thefirstset'ofadmissionpipes I; and is carried=bycentrifugal:force to the ends of the heating tubes 6 of this set, where it becomes heated, andsin consequenceofits lower specific gravity thiswater. is displaced by. theinfl'owing coldgwateriinto the interior-of thehollowshaft I;

second gsetiofgadmission .pipes I :and'heating: tubes 3 5, thenithroughzthe next length of tube I0 into the third set of admission pipes I and heating tubes 5. After complete evaporation of the water the resulting steam passes into the length of tube II through which it enters a plurality of sets of heating tubes simultaneously, to become superheated. As will be clear from this description and the drawings, pre-heating and evaporation are eflected in the first of the sets of tubes, which come in contact with the flue gases after the latter have become more or less cooled down, while in the sets of tubes which are exposed to the flue gases at their hottest the superheating of the steam is efi'ected.

In the formof construction shown in Fig. 4 the saturated steam generated can be continuously converted into superheated steam, for which purpose means for eliminating salt from the feeding water must be provided, in order to prevent the salt content of the water from exceeding the admissible limit. The hollow shaft I is divided into two chambers by means of the flange pertaining to an inserted member 22 which is closed atone end; one of these chambers being in communication with the water feed pipe, while the other is situated at the side at which the steam sion pipes 25 associated. with the'superheating- Thence the steam passes out throughtubes 26. a-stufiing-box 21 into the steam discharge connection 28. there serves a salt-eliminating pipeZB the T-' shaped end 30 of which dips with itstwo inlet orifices intothe annular body of water forming I on the-inlet-side of the hollow shaft l during rotation. A1 closuremember- 3I enables the quantity of water conducted away to be regulated, so thatithe desired salt content of the water can be kept constant. The end of'the salt-eliminating pipe -is rotatably mounted inla' stufling-box 32:

Between the admission pipe 23" and the heating tube- 24 there are inserted obliquely set blades 39' whichserve'on the one'hand to hold the admis-' sion pipe in the middle ofthe heating tube, and on: the other hand to impart a supplementary:

atedly reduced length, the arrangement being such that'the tubes are shortest where the'gases' are hottest, and longest where the gases have been cooledfidown most and where the strongest eddying isrequired. Fig; 5 also shows a blower 31 mounted on the hollow shaft I, which blower feeds the air heated b'eneath theshell l'l by the shortest route, through an air conduit'38; to the combustion chamber of the furnace:

The economy of working of the describcdheat exchanger is due to thefact'that it' can be used" both .as a Water pre-heater, as a steam generator,

and as a' steam superheater, and can at the-same time be made to serve in addition for the conveying of 'the combustion gases and also of the air for combustion. r

I'claim: 1. A rotary'flue gas pre-heating of water, generating of steam, and

superheating of steam, comprising in combination a chamber-adapted to be interposed inthe path For the elimination of excesssaltf' heat exchanger for' the of flow of flue gases from a furnace, a hollow shaft freely rotatable in the said chamberand extending but clear of said chamber through opposite Walls thereof, means for introducing a medium to be heated at one end of the said rotary hollow shaft and for discharging the heated mediiun at the other end thereof, heating tubes radially connected to the said hollow shaft and communicating with the outlet end thereof, the said tubes being closed at the outer end, hollow positioning means within the said hollow shaft communicating with the inlet end and closed off from the discharge end of the said shaft, openended admission pipes fitted with their inner ends in the said positioning means and severally extending, with clearance, into the said heating tubes to a point near the closed outer end of the said tubes, mean on the shaft for continuously rotating the assembly consisting of said shaft, heating tubes, positioning means, and admission pipes at highspeed, independently of the operation of the said furnace, to exert centrifugal force upon said medium, the said positioning means for thefirst set of admission pipes consisting of a closed extension on the entry end of the said hollow shaft, and for the remaining sets of admission pipes of length of tube flanged to fit within the said hollow shaft at the end towards the entry end of the said shaft and closed at the other end, the said lengths of tube being associated partly with single sets of admission pipes and partly with a plurality of such sets.

2. A rotary flue gas heat exchanger for the pre-heating of water, generating of steam, and superheating of steam, comprising in combination a chamber adapted to be interposed in the path of flow of flue gases from a furnace, a hollow shaft freely rotatable in the said chamber and extending out clear of said chamber through opposite walls thereof, means for introducing a medium to be heated at one end of the said rotary hollow shaft and for discharging the heated medium at the other end thereof, heating tubes radially connected to the said hollow shaft and communicating with the outlet end thereof, the said tubes being closed at the outer end, hollow positioning means within the said hollow shaft communicating with the inlet end and closed off from the discharge end of the said shaft, openended admission pipes fitted with their inner ends in the said positioning means and severally extending, with clearance, into the said heating tubes to a point near the closed outer end of the said tubes, means on the shaft for continuously rotating the assembly consisting of said shaft, heating tubes, positioning means, and admission pipes at high speed, independently of the operation of the said furnace, to exert centrifugal force upon said medium, and a rake associated with the inner wall of the said chamber and consisting of bars extending inwards between the sets of the said radially disposed heating tubes, for the purpose of increased eddying of the flue gases.

3. A rotary flue gas heat exchanger for the pro-heating of water, generating of steam, and superheating of steam, comprising in combination a chamber adapted to be interposed in the path of flow of flue gases from a furnace, a hollow shaft freely rotatable in the said chamber and extending out clear of said chamber through opposite walls thereof, means for introducing a medium to be heated at one end of the said rotary hollow shaft and for discharging the heated medium at the other end thereof, heating tubes radially connected to the said hollow shaft and cornmunicating'with the outlet end thereof, the said tubes being closed at the outer end, hollow positioning mean within the said hollow shaft communicating with the inlet end and closed 01f from the discharge end of the said shaft, open-ended admission pipes fitted with their inner ends in the said positioning means and severally extending, with clearance, into the said heating tubes to a point near the closed outer end of the said tubes, means on the shaft for continuously rotating the assembly consisting of said shaft, heating tubes, positioning means, and admission pipes at high speed, independently of the operation of the said furnace, to exert centrifugal force upon said medium, an outer shell urrounding the said chamber in spaced relation thereto, for the provision of a layer of heated air between the chamber and shell, and ablower mounted on the said hollow shaft and communicating with its suction side with the said layer of air, and with its delivery side with the combustion chamber of the furnace, for the purpose of feeding pre-heated air to support combustion in the said furnace.

4. A rotary flue gas heat exchanger for the pro-heating of water, generating of steam, and superheating of steam, comprising in combination a chamber adapted to be interposed in the path of flow of flue gases from a furnace, a hollow shaft freely rotatable in the said chamber'and extending out clear of said chamber through 0pposite walls thereof, means for introducing a medium to be heated at one end of the said rotary hollow shaft and for discharging the heated medium at the other end thereof, heating tubes radially connected to the said hollow shaft and communicating with the outlet end thereof, the said tubes being closed at the outer end, hollow positioning means within the said hollow shaft communicating with the inlet end and closed off from the discharge end of the said shaft, open-ended admission pipes fitted with their inner ends in the said positioning means and severally extending, with clearance, into the said heating tubes to a point near the closed outer end of the said tubes, means on the shaft for continuously rotating the assembly consisting of said shaft, heating tubes, positioning means, and admission pipes at high speed, independently of the operation of the said furnace, to exert centrifugal force upon said medium, the said sets of heating tubes being of graduatedly varied length, the said tubes being shortest where the flue gases are hottest, and longest Where the said gases are most cooled and where therefore maximum eddying is desired.

5. A rotary flue gas heat exchanger for the pre-heating of water, generating of steam, and superheating of steam, comprising in combination a chamber adapted to be interposed in the path of flow of flue gases from a furnace, a hollow shaft freely rotatable in the said chamber and extending out clear of said chamber through opposite walls thereof, means for introducing a medium to be heated at one end of the said rotary hollow shaft and for discharging the heated medium at the other end thereof, heating tubes ra-' dially connected to the said hollow shaft and communicating with the outlet end thereof, the said tubes being closed at the outer end, hollow positioning means within the said hollow shaft communicating with the inlet end and closed off from the discharge end of the said shaft, openended admission pipes fitted with their inner ends in the said positioning means and severally extending, with clearance, into the said heating tubes to a point near'the c'losefd .Iouter end of the said tubes, means on the shaftr-for continuously rotating the assembly consisting of said shaft, heating tubes, positioning-means, and admission pipes at high speed, independently of the operation of'the said'furnace, to exert centrifugal force upon said medium, and a salteliminating pipe having a 'T-shaped end provided with two inlet orifices adapted to dip in the annular body of'medium formed in the said hollow shaft when rotated, the said pipe being provided with a closure member adapted'to admit of regulating the inside cross-sectional area of flow through the said pipe.

6. A rotary flue gas heat exchanger for the pre-heating of water, generating of steam, and superheating of steam, comprising in combination a chamber adapted to be interposed in the path of flow of flue gases from'a furnace, a hollow shaft freely rotatable in the said chamber and extendingout clear of said chamber through opposite walls thereof, means for introducing a medium to be heated at one end of the said rotary hollow shaft and for discharging the heated medium at the other end thereof, heating tubes radially connected to the said hollow shaft and communicating with the outlet end thereof, the said tubes being closed at the outer end, hollow positioning means withinrthe said hollow shaft communicating with the inlet end and closed off fromthe discharge end of thesaid shaft, openended admission pipes fitted with their inner ends in the said positioning means "and severally ex-- tending, with clearance, into the said'heating tubes to a point near the closed outer endof the said tubes,'means onthe shaft forcontinuously rotating the assembly consisting'of said shaft, heating tubes; positioning means, and admission pipes at high speed, independently of the operation of the said furnace, to exert centrifugal force-upon said medium someof thesaid heating tubes,- namely those furthest removed from the point of. entry of the fiue gasesrinto the said casing, being provided with :fins "for the purpose of increasing the total heat-absorbing 'surfaceof the said tubes.

7. A rotary flue gas heat exchanger for the pre-heating of water, generating of steam, and superheating of steam, comprising in combination a chamber adapted to beinterposed' in the path of flow of flue gases from a furnace, a hollow shaft freely'rotatable in the said chamber and extending out clear'of said chamberthrough opposite walls thereof, means-for introducing amedium to be heated atone end of the said rotary hollow shaft and for discharging the heated medium at the other end thereof, heating tubes radially connected to the said hollow shaft and communicating with the outlet end thereof,ithe said tubes being closed at-the outer end, hollow positioning means within the'said hollow shaft communicating withthe inlet'end and closed off from the discharge end of the said shaft,openended admission pipes fitted with their inner ends in the said positioning mean andseverally extending, with clearance, into the said heating tubes to a point near the closed outer end of the said tubes, means on .theshaft for continuously rotating the assembly consisting of said shaft,

heating tubes, positioning means, and admission pipes at high speed, independently of the operation of the said furnace, to exert centrifugal force upon said medium, some of the said heating tubes, namelythose furthest removedfrom the point of entry of the flue gases into' the said casing, being provided with fins disposedobliquely after the manner of fan blades, for the'purpose of increasing the total heat-absorbing surface of the said tubes while at the: same time accelerating the movement of the saidflue gases through the said casing. I

, HANS SIMMON.

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