US2201626A - Steam generating apparatus - Google Patents

Description

y 21, 1940- w. D. LA MONT 2,201,626

- sum GENERATING APPARATUS Original Filed Oct. 5, 1933 '2 Sheets-$heet 1 INVENTOR. Wa'lfer flougias Z aflonl May 21, 1940. w. D. LA MONT STEAM GENERATING APPARATiJS 2 Sheets-Sheet 2 Original Filed Oct. 5, 19253 Patented May 21, 1940 PATENT OFFICE STEAM GENERATING APPARATUS Walter Douglas La Mont, North Colebrook, Conn; assignor to W. D. La Mont Inc., Wilmington, Del., a corporation of Delaware Original application October 5, 1933, Serial No. 692,236. Divided and this application August 26, 1935, Serial No. 37,973

Claims.

This invention relates to rapid fluid heating apparatus as applied to high speed steam generating apparatus. This application is a division of my application Serial No. 692,236, filed October The present invention relates to a boiler construction having for its purpose the generation of steam of high energy content and high output capacity which necessitates an arrangement for circulating the several fluids such as water,

steam and mixtures thereof, as well as the combustion gases and the air for supporting combustion in the most eflicient manner with the circulating paths of each co-operating with each other to a maximum degree. The structural arrangement in accordance with the present invention seeks to mimimize abrupt turns of the fluids in order not to establish dangerous pressure conditions in any of the circulating paths.

This present invention is particularly concerned with the improvement of high speed steam boilers, and power plants embodying the same, and methods of operating said boilers and said power plants. Where my invention, and/or any of its features, applies to flash boilers and to high speed power plants using said flash boilers, such improvements are well within the scope of my invention as herein described.

While my invention, which has been described herein as relating to steam generating apparatus, is intended especially for the generation of steam from water, it will he understood that the terms steam and water as used in the specification and claims are intended to include as equivalents, any liquids which might be handled by the novel process and/or apparatus herein described, resulting in the generation of any vapors which might be handled by, or be useful in connection with my process and/or apparatus, and it will also be understood that many of the novel features of this invention are applicable in other fields than that for which the apparatus herein specifically illustrated and described is particularly intended.

l 3 Other objects and features will be particularly pointed out and disclosed hereinafter in the illustrations, description, specification and claims of this present patent application.

In the drawings:

50 Fig. 1 is a complete power plant showing the direction the various fluids flow in their respective paths through my boiler and'the close inter-relation between the action of the boiler and my high speed power plant as a whole of which my boiler forms a part;

Fig. 2 is a plan view of one of my fluid heater heat absorbing elements, with its pressure drop device as shown in position in Fig. 1 at point A;

Fig. 3 is an enlarged detailed assembly drawing partially cut away, partially in elevation and 5 section of parts of my high speed steam boiler;

Fig. 4 is a view looking downward on the top of the boiler (reduced in size) showing the turbine driven air supercharger delivering air tangentially to my boiler and a pipe releasing burnt l0 gases tangentially;

Fig. 5 is a detail of Fig. 1 showing the path of travel of burnt gases as applied in connection. with my new methods of heat extraction and heat transfer to the working fluid of the boiler; 15

Fig. 6 is an enlarged view of certain of the working fluid tubes or steam generating elements shown in other figures of the drawings;

Fig. '7 is an enlarged sectional view of my .heat interchanging tube with longitudinal fins 20 attached;

Fig. 8 is a sectional view of several heat interchanging tubes as they are arranged in the assembly sectional view shown in Figs. 3 and 5.

In Figure 1 of the drawings is shown the power 25 plant including as a part thereof, a steam generator adapted to produce steam of high energy content, in accordancewith the present invention. The steam generator is designated by I, having a plurality of steam generator water wall 30 tubes 34 therein receiving water from the water wall inlet header 33, and discharging water and/or steam to the steam generator outlet water wall collecting header 36. The tubes 34 may be arranged helically within the combustion 35 chamber rather than straight. These tubes are exposed to a source of radiant heat produced by a flame fed with fuel from burner 2 in the burner throat 3. The combustion of the fuel oil is assisted by a source of air which may be supplied 40 from the super-charger 5, to which air is admitted through inlet 4|, feeding air through the discharge lead 4 to the burner throat. The steam generator tubes are shown fitted with pressure drop devices 35, for controlling the input of water into each tube in suflicient quantity to protect the tube and to control the flow of steam and Water in each tube to insure the proper operation thereof, said pressure drop devices being placed in an intermediate portion of the length of each tube, in accordance with a preferred form of the invention. Such a device is shown in detail in Fig.2.

The steam and water collected in header 36 discharges by way of conduits 31 (Figure l) in- I to water level cylinder 8 for maintaining a water level in the system, furnishing reserve power, and insuring water supply to the circulating pumps. The steam is separated from the water in the cylinder 8, and passes through the main high pressure steam line 9, having main control valve 6| therein for controlling the steam to the main turbine I8. Furthermore, a 'pipe line 66 extends from the steam line 9 to auxiliary steam turbine 6 having control valve 42 therein for controlling the drive of auxiliary turbine 6, which drives the fuel oil pump 21, boiler feed pump I1 and boiler circulating pump 26. A separate auxiliary turbine 59 supplied with steam from pipe 56 with control valve 51 therein, drives the air super-charger fan 5.

The main exhaust lead I8 from the main turbineextends from the latter to the main condenser II. Pipe I2 represents the'inlet for circulating cooling water to the main condenser II,

and pipe I3 is the outlet pipe therefor. Ripe I4 is the condensate water discharge from the main condenser II to the main feed tank I5 having feed water inlet 46 and control valve 43 therefor. Vent 41 is associated with the feed water tank, and suction lead 28 extends from the latter to the condensate pump I6 or feed pump I'I. I8 is a discharge pipe connecting feed pump H with the water level cylinder 8; I8 is a by-pass line for by-passing feed water around the feed pump I'I through water level regulator valve I9, for controlling the water level in the system; and 28 is a feed' stop and check valve on the feed pump discharge lead I8 for stopping and checking the feed of water into the system.

Associated with the cylinder 8 is a safety valve 2| for the boiler at the top of the cylinder, and

a blow-off valve 22 at the bottom thereof. The cylinder has a gauge glass 23, and an automatic water level regulator 24 from which extends a pipe 25 to the control valve I9.

The main steam generator circulating pump is represented at 26. The suction line for pump 26 is connected with the water level cylinder 8, through pipe 3I, and the discharge pipe 32 of this pump extends therefrom to the inlet header 33. The main circulating pump 'is fitted with a by-pass 45 therearound, to control the quantity of water which is circulated by means of control valve 44 in this by-pass.

The fuel'oil tank is represented at 38 with its suction line 39, vent 58,,filling line 48, and control valve therefor, 49, and burner by-pass return oil discharge lead 6|. Opening into the fuel line into the burner is a pipe havinga control valve therein 6I for introducing starting oil into the burner, and 6I is a valve for shutting ofi the oil normally used in the operation of the plant, while using the starting fuel oil. Pipe 28, constituting the exhaust lead from the auxiliary turbine 6, opens into the main turbine exhaust lead ID The novel circulating arrangement for the combustion gases and the preheated air is shown generally in Figure 1 and in greater detail in Figures 3 and 5. \l

The central combustion chamber I86, as shown, has steam generator tubes 34 therein through which water is circulated from inlet header 33 to outlet header 36; The steamand water pro-- duced in accordance with the present invention, is discharged into the tube 31 at the end of the boiler opposite the burner, and thence to the water level cylinder 8. Tube 5| extends from the upper end of the cylinder 8 at 5", to deliver saturated steam therefrom to the superheater tubes coiled around the interior of the combustion chamber which are sh elded by the steam generator tubes 84.

In addition to the steam generating tubes 84 in the combustion chamber, auxiliary steam generating tubes 52 are coiled in annular passage I88, formed on the outside of the combustion chamber I86, and confined by an external wall 282, which forms a tapered passage extending from the inlet thereof at I81, to the outlet thereof, at I89. The combustion gases travel upwardly to the top end of the chamber I86 and then pass through passage I81 downwardly, through the passage I88, giving up the heat contained therein to the steam-generating tubes 52. The tubes 52 may be supplied with circulating water from the main steam generator circulating pump 26 and these tubes discharge the steam and water therein into the waterlevel cylinder at 52 These tubes 52 in the convection passage may be provided with fins 52 and 52, extending in parallel to the axis of the tubes-as shown in Figures 6, '1 and 8, for the purpose of more eflectively extracting the heat from the combustion gases.

In addition to the steam generating tubes 84 and 52 described above, tubes 55 may be provided for protecting the combustion chamber inlet wall 286, which receive water from the inlet header 33 and discharge water and/or steam to the collecting header 36.

The combustion gasespassing downwardly through the convection passage I 88, pass through the exits I88 into a series of spirally disposed burnt gas passages II 8. These spiral passages terminate near the top of the boiler into a passage III, which open into a common outlet passage II2, to which is connected the tangential stack outlet passage II8 opening into the atmosphere, (Fig. 4).

The incoming air used for combustion which is commingled with the fuel supplied by burner 2' in the throat I84, is admitted to the throat through openings I 83, after passing in heat-exchanging relatio'nship with the burnt gas passages II8. The air is supplied from the air supercharger 68 (Figure 4), to the pipe I88 opening tangentially into the casing of the boiler 28I. This casing forms in conjunction with the walls 283 forming the passage I I8, a plurality of spiral air-preheater passages II", which travel do'Wnwardly in Figures 1 and 3 towards the air inlet I83. The area of the spiral air-preheater passages increase from the air inlets to the air outlets, while the burnt gas passages II8 decrease from the inlets to the outlets thereof, for the reasons set forth below.

The improved design of my boiler embodiments described above are predicated upon the theories and features set forth below.

I have found that, with my high speed steam generators with supercharged combustion. a large amount of power can be produced from a small combustion, chamber. High initial temperatures are produced in said combustion chamber sending gases of high initial temperature to the convection surfaces. To reduce the temperature of the convection gases, it is general practice to complete the superheating of the steam,

the generation of the steam by the convection gases and the preheating of the air by the convectlon gases.

In order to keep my units in a compact form all convection surfaces must be grouped around my comparatively small combustion chamber; It

cross flow is used or parallel fiow on straight tubes, the length of gas travel available is very short without using many abrupt 180 turns of the gas, with the gas traveling repeatedly back and forth on said surfaces. It is very desirable to obtain longer gas travel or a type of gas travel over the surfaces which produces a more disruptive effect or upsetting of the gas than is obtained bypresent methods with cross flow or parallel flow. I

In this invention I show the use of spiral flow made by forming spiral passages around my combustion chamber with tubing or metal or both, said passages being tapered to obtain the proper gas velocities as the gas changes in volume and density in its flow throughout the spiral passages.

This arrangement gives a long travel for thegas mainly in parallel spiral flow and permits the using of very high gas velocities considerably above the beginning of the critical condition of flow, with low draft loss.

Where the heat effects are very high the pas-.

sage may be lined with tubing adjacent to each other eliminating the need of a close contact of the tubing with the metal walls and a carefully designed spacing apart of the tubing on these walls to meet the given heat load.

Where the heat effects are low and the spacing of the tubing is merely a question of obtaining the maximum transfer results to the entire tube surface, metal spiral passages may be used and the tubes spaced only in reference to the heat transfer to the tube surface.

It is a general characteristic of my circumferential heat exchanging for such passages, to taper from a ring shaped inlet opening of wider width to a ring shaped outlet opening of a narrower width, and where tubes or other heat exchange elements occupy such passages in spiral arrangement, the distance between such tubes, (as they spiral in the wider circumferential portion of the passage to the narrower circumferential portion of the passage), is, in accordance with my invention, closer; the tubes are progressively more closely packed, or lay nearer to each other.

The purpose of the more closely packed arrangement of the tubes is to obtain passages of diminishing volume as the heat is withdrawn from the burnt gases, which release their heat to the cooler walls of the tubes containing rapidly flowing boiler working fluids. The velocity of the flow of the heating gases is not slowed down, due to the diminishing density of the hot gas on account of the removal of its heat which corresponds to the diminution of the volume of the circumferential spiral space through which the gases flow, as those gases flow from a hotter zone to a cooler zone.

In my structural design, my air preheater passages, -both for air flow NH and burnt gas flow III], are spiral, curved around the boiler and tapered, the taper of each passage for the burnt gas, decreasing in area with the decrease in vol- As the air passes from the circular air inlet passage l A into the air preheater spiral tapered air passages "II, it is given a further whirling motion in the same direction by having the spiral tapered air passages IOI spiralled in the proper direction to accomplish this purpose.

The air leaving the spiral tapered air preheater air passages passes into the burner circular entrance air passage I02 still whirling into the burner entrance I03.

the spiral tapered convection steam generating burnt gas passage I08.

The spiral of the convection steam generator tubing 52 is wound opposite to that of the waterwall 34 and superheater tubing 5|, so that the burnt gases travelling in said passage I08 from the combustion chamber I06 continues to whirl in the same direction.

From the spiral tapered air preheater burnt gas passage H0 the burnt gases travel through the exit connectors III of the spiral tapered air preheater burnt gas passages H0 to the circular exit convection burnt gas passage I I2 and then through the tangential stack outlet passage H3 to atmosphere.

I have found with my supercharged light weight steam generator that it is necessary to get as high a rate of heat transfer as possible from the convection heating surface, in order to use a minimum amount of surface in this part of the apparatus for reducing the gas temperature and thereby keep the weight of this surface to a minimum.

With supercharged-combustion as previously brought out, in the description of this invention, high initial temperatures of the convection gases can be obtained.

The recent advance in design of supercharging air fans of high speed and efficiency, small size and light weight delivering air at high pressure with low. power loss makes possible very close spacing of the convection heating surface with use of very high gas velocities and complete disruption or upsetting of the gas in its travel over the convection heating surface. The critical condition of gas flow, can be reached and utilized to a degree heretofore impossible with the limited draft loss formerly available for use with steam generators.

By using tapered gas passages in the steam generating apparatus, including the passages for air as well as for fuel gas, the high velocities initially used in said passages, may be maintained and even gradually increased or decreased, as desired, to obtain desired velocities with the changing volume anddensity. of the gas as it is cooled or heated.

I streamline many of my fluid passageways throughout the boiler structure, especially at the turns and at changes in direction of the flow of gases. High velocity of gas flow can be maintained throughout the system with small draft loss at these points leaving the main draft loss available for high speed travel over the heating surfaces where such loss is more than repaid by smooth curved turn, where the bottom casing.

205, meets the waterwall side casing 206, to guide any gas, flowing radially from the burner to the sides upward. I

At the outlet end of the combustion chamber, I use a circular conical nose, 201, projecting toward the interior of the combustion chamber at the central portion of the top casing to spread and guide the high velocity gases toward the outer circumference of the combustion chamber at this point; and where the gases are to be guided into the entrance of the convection heating surface.

The conical central portion 201, in the top casing is followed by a portion depressed in said casing, relative to the interior of the combustion chamber and this portion in turn is-followed by a smooth curved turning of the top casing, leading to the convection gas passage wall 202, so that radially from the central portion of the top casing to the circumference the said casing is first conical, then depressed, then curved, relative to the interior of the combustion chamber, to guide the gases in a smooth streamlined flow from the center of the combustion chamber to the entrance to the convection heating surface, including the turn into the convection heating pas-.

sage I08.

As the whirling burnt gases leave the convection heating passage 18, they enter the circular outlet curved convection steam generating burnt gas passage [09A and are turned smoothly into the air preheater spiral tapered burnt gas passage HO. a

As the whirling burnt gases leave the air preheater spiral tapered burnt gas passages they pass through the exit connections Ill of said passages i I 0 into the circular exit convection burnt gas passage H2 into and through the tangential stack outlet.

Although it is not shown exactly this way on the drawing the burnt gases as they leave the combustion chamber flow through heat exchanging passageways constantly diminishing in their volume, in other words to correspond with the diiference and reduction in the volume of the gases as they flow out from the combustion chamber.

It is better that when the burnt gases are making their various turns and until they-have all of their heat extracted from them not to be expanded at any point in their whirling outward travel from the combustion chamber. When such gases expand in volume due to entering a larger space they tend to absorb the heat rather bustion chamber, an outer casing around said combustion chamber enclosing an air space communicating with said burner, walls constructed and arranged to form a tangential air inlet passage in said casing for introducing air to said burner in a. whirling direction and a tangential I outlet passage for the gases passing from said combustion chamber.

2. In a steam boiler, a wall forming a combustion chamber, a water wall in said combustion chamber, a burner at one end of said combustion chamber, an outer casing around said combustion chamber enclosing an air space communicating with said burner, walls constructed and arranged to fo m tangential air inlet passages in said casing for introducing air to said burner in a whirling direction, a manifold in said casing for the gases passing from said combustion chamber, and tangential outlet passages for the gases connected to said manifold.

3. The combination set forth in claim 1 wherein said tangential air inlet passage and saidtangential outlet passage are in heat-exchanging relation.

4. In a steam boiler, a wall forming a combustion chamber, a water wall in said combustion chamber, a burner at one end of said combustion chamber, an outer casing around said combustion chamber enclosing an air space communicating with said burner, walls constructed and arranged to form a tangential air inlet passage in said casing, means connected to said air inlet means for forcing air under pressure into said air space in a whirling direction, and tangential outlet passages for the gases passing from said combustion chamber.

5. In a steam boiler, a wall forming a combustion chamber, a second wall outside of said first wall and forming a burned gas passage in heat exchanging relation to said combustion chamber, and a third wall forming an air chamber inheat exchanging -relation to said burned gas passage, means for directing air spirally in said air passage, and means for directing the burned gases from said burned gas passage spirally into said air chamber in heat exchanging relationship to the spirally flowing air therein.

WALTER DOUGLAS'LA MONT.

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