US1768056A - Water-tube boiler with steam superheater - Google Patents

Description

June 24, 1930. o. H. HARTMANN WATER TUBE BOILER WITH STEAM SUPERHEATERS Filed Aug 20,. 1926 3 Sheets-Sheet l Inventor:

June 24, 1930. o. H. HARTMANN 1,

WATER TUBE BOILER WITH STEAM SUPERHEATERS Filed Aug. 20, 1926 v 5 Sheets-Sheet 2 "mii =5 I j as /n ventop: 0%0 if. War" a/nn,

O. H. HARTMANN WATER TUBE BOILER WITH STEAM SUPERHEATERS 3 Sheets-Sheet 3 June 24, 1930.

Filed Aug 20, 1926 Fig.5.

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Filer qr Patented June 24, 1930 UNITED STATES PATENT OFFICE SCHMIDT'SCHE HEISSDAMPF-G. M. H

A. CORPORATION OF GERMANY OF OASSEL-WILHELMSHOHE, GERMANY,

WATER-TUBE BOILER 'W'ITH STEAM SUPERHEATEB Application'flled August 20, 1926, Serial Na. 130,545, and in Germany October 19, 1925.

My invention relates to water-tube boilers fitted with steam superheaters. A main object of my invention is to provide arrangements of water-tube boilers fitted with steam superheaters which shall be specially apceptionally igh steam pressures and correspondingly with high degrees of s'uperheat.

, With such an object An important feature of my invention consists in dividing the steam superheater 1nt0 two parts, one part of the superheater tubes being arranged among the water tubes lying in the first section of the main flue while the plicable *to power plants working with ex-- other part of the superheater tubes is arranged in a special chamber through which the furnace gases flow. This division of thesuperheater may be carried into effect in such a way that the first part of the superheater (the prima'rsuperheater) lies-in the first section of t e main flue and the second part of the superheater (the secondary superheater) lies in the special chamber.

In order that the degree of superheat may be accurrately regulated, a damper or the like is provided for adjustingthe volume of, furnace gases passing through the special chamber. I

According to amodification ofthe invention, the primary superheater may be arranged in the special chamber and the secondary superheater among the water tubes inthe first section of the flue.

5 Further objects of the invention, in a watertube boiler'in which the eva orator portion consists of two banks of tu es with corresponding upper and lower drums arranged over the grate in the form of a roof, are to submit'the front bank of tubes to a more intense action of the furnace gases and to heat more uniformly the individual tubes of this bank and in addition to secure a more favourable water circulation. in the boiler. This object is attained by the introduction of superheater tubes among the water tubes of the rear bank adjacent to the second section of the flue,-by a special arrangement of the unheated downcomers or connecting v5 tubes and. by deflecting a part of the tubes them.

of the rear bank to the upper drum of the front bank of tubes.

Different forms of the invention are shown by way of example in the accompanying drawings :-v

Figure 1 shows a section through a boiler with vertical or steeply-inclined water tubes fitted with a superheater according to this invention; 7 1

Figure 1 is a fragmentary view of a modified form of the invention shown in Figure 1. I

Figure 2 shows to a somewhat larger scale a section on the line 2-2 of Figures 1 and 3 of the rear bank of water tubesin the first section of the furnace flue with the superheatertubes arranged among them;

Figure 3shows a modified form of boiler with vertical or steeply-inclined water tubes provided with two banksof tubes forming as it were a roof over the grate;

Figure '4 shows the superheater tubes for a modified form of the invention; Figure 5 is a'section through a boiler with slightlyincined water tubes and divided superheater, an

' Figure 6 shows the shape of the headers of the. water-tube boiler of Figure 5 and the distribution of the superheater tubes between The water-tube boiler with steeply-inclined tubes shown in Figure 1 consists, as is desirablein steam boilers for exceptionally high pressures,'of the evaporator proper, A, and the feed-water heater, B. The evaporator, A, is arranged after the manner of a roof over the grate, 1, and comprises two lower drums,

' 2 and v3, and two upper drums, 6 and 7, connected to the former by banks of water tubes, 4 and 5. The front bank of tubes, 4, is inclined at a considerable angle while the tubes of the rear bank, 5, are substantially vertical. An additional drum, 8, is provided with a steam collector, 9, and lies outside the combustion chamber proper from which it is separated by a wall, 10, of refractory material. A portion of the tubes of the rear bank of water tubes, 5, .adjacent to the combustion chamber, as seen at 11, are bent at their upper ends and connected, not to the upper drum, 6, of the rear bank of tubes, but to the upper 100 drum, 7, of the front bank of tubes. Tubes, 12, connect the steam spaces of the drums, 7 and 8. The drum, 8, lying outside the combustion chamber, is connected with the lower drum, 3, solely-by means of a series of unheated tubes, 13. Screens of refractory material, 14, protect those regions of the drums into which the water tubes are expanded from the direct action of the furnace gases.

As shown in Figure 1, the unheated drum, 8, may be omitted in which case the unheated downcomer tubes are arranged between the drums, 3 and 7, as indicated at 13'. The steam collector, 9, then lies above the drum, 7.

The wet steam passes out of the collector, 9, through the pipe, 15, to the superheaten wet-steam distributor header, 16, to which the superheated tubes, 17, are attached, these tubes being arranged as shown in Figure 2 among the water tubes of the rear bank 5, and parallel thereto. From the superheater collector header, 18, of this first stage of the superheater or primary superheater, the steam passes through the pipe 19, to the collector header, 20, of the second stage, of the superheater, or secondary superheater, the tubes, 21, of whichvare arran ed in a special chamber, D,'which in the orm of the invention now being described forms the second section of the main flue. The steam now superheated to the required temperature collects in the superheated steam header, 22, whence it passes through the pipe, 23, to any point desired.

Behind the second section of the main flue containing the secondary superheater lies, as above mentioned, the feed-water heater, B,

which consists of a lower drum, 24, and an upper drum, 25, connected by tubes, 26. These tubes are divided by a centre wall or partition, 27, which is provided with an aperture in its upper part for the passage of the hot gases.

In the upper part of the dividing. wall between. the second and third sections of the a controlling device, e. g., the sliding 28, is arranged. At the bottom of the second section of the flue, dampers, 29, are provided while a connecting duct, 30, between the lower ends of the second and third sections of the main flue, can be closed by a sliding damper, 31.

With the dampers, 28 and 29, closed andthe damper, 31, open, the hot gases pass successively through the first section of the flue, the second section of the flue in which is the secondary superheater, upwards through the third section of the flue containing a part 0 the feed-water heater, B, and downwards through the-fourth section of the flue containing the remainder of the feed-water heater to the chimney, the path taken by the hot gases being indicated in Figure 1 by the fullline arrows. 1

The feed water is fed through the pipe, 33, from the upper drum, 25, of the feed-water heater to the upper drum, 7, of the evaporator.

The regulation of the degree of superheat can be effected according to this form of the invention by keeping the damper, 28, more or less open so that a part of the hot gases, instead of flowing through the secondary superheater, passes directly through the aperture between the second and third sections of the flue into that part of the feed-water heater, B, lying in the fourth section of the flue and so to the chimney.

If the damper, 28, is open and the dampers, 29 and 31, closed, the secondary superheater is cut out, the hot gases from the first section of the flue then passing directly to the feedwater heater and thence to the chimney.

By appropriate adjustment of the sliding dampers, 28 and 31, and the pivoted damper, 29, it will thus be seen that the heat in the hot gases may be efliciently utilized, and regulation of the temperatures of the steam and water secured within wide limits.

By opening the dampers, 29, at the bottom' of the downwardly-leading section of the flue containing the secondary superheater and closing the dampers, 28 and 31, the feed-water heater, B, can be cut out, so that in this case the hot gases after contact with the heating surface of the superheater pass directly into the chimney.

The special advantage of the arrangement described with divided superheater lies in the fact that the heating surface of the primary superheater, 17, is not farremoved from the grate, sothat even at low duties of the boiler an exceptionally high degree of superheat can be obtained.

In the primar superheater the steam may be superheated, or example, to 300 or 350 C. while on passing through the tubes, 21, of the secondary superheater the temperature of the steam may be raised to 400 or 47 5 C.

The position of the damper described in the .upper part of the wall between the second and third sections of the flue provides a ready means of adjusting the superheat to the temperature required. 1

In addition, by means of the proposed arrangement, a high 7 velocity v of the furnace gases is rendered possible over the heating surface of the superheater-so that the coeflicientof heat transference is higher and the heating surface of the superheater .can therefore be made proportionately less, with a consequent decrease In cost of the installation.

Further, by reducing the bulk of the instalf lation in the manner described, the floor space required is likewise decreased.

An additional advantage of the arrangement described, lies in the fact that the flow of the furnace gases, which apart from the position of the primary superheater among the water tubes of the rearbank, 5, would be free and unhindered to the second section of the main flue, is to a certain extent reprimary superheater were absent. In consequence of this holding back, the furnace gases take somewhat the path indicated by the bent arrow, C, flowing upwards into the front bank of tubes, 4, where they are cooled and passed downwards so as to mix with the hot gases from the grate. In this way the tubes of the front bank, 4, which otherwise would receive heat chiefly by radiation,'are heated more intensel increased and the heat in the furnace gases better utilized. At the same time the tubes of the rear bank, 5, adjacent to the second section of the flue, in consequence of the mixing of the hot furnace gases with gases already cooled to some extent in the bank of tubes, 4, are heated to a less extent than if the uncooled highly-heated furnace gases.

passed freely over and between the tubes of the rear bank.

Due to the insertion of the superheater tubes, 17, among the water tubes, 5, of the rear bank, this advantage of checking or holding back the free flow of the furnace gases so as to cause a more intense heating of the front bank of water tubes and a less intense heating of the rear bank of water tubes, is, in a water-tube boiler with its evaporator portion arranged like a roof over the grate, independent of the division of the superheater into primary and secondary parts shown in Figure 1.

Thus, the advantage in question. is also present if the superheater consists only of tubes arranged among the water tubes of the rear bank, as shown in Figure 3, in which the parts, 1 to 18, correspond with the parts, 1 to 18, in Figure 1, the parts, 24, 25, 26 and 33*, likewise corresponding with the parts of the feed-water heater denoted in Figure 1 by the same reference numbers. The difference consists in the fact that in Figure 3 the feed-water heater, B, is arranged in the second section of the flue, that is, it follows directly the evaporator, A, while the superheater tubes, 17 form the complete superheater, no secondary superheater in this case being provided.

Thus, according to the construction shown 1 in Figure 3, in consequence of the damming back of the furnace gases due to the superheater tubes, 17 depending among the water tubes, 5*, a special local circulation of the furnace gases is likewise set up, as indicated by the arrow, C, so that they transfer a large part of their heat to the front bank of water tubes, 4.

Through the less intense heating of the tubes of the banks, 5, (5) a high degree of superheater tubes.

, that is, evaporation is.

durability is secured in the water tubesand In boilers designed for pressures up to 100 atmospheres the clear bore of the water tubes cannot be as large as in boilers for lower working pressures, and with the very intense heating due to jets of flame, there is thus'a danger of the tubes being filled to a large extent with steam bubbles so that they are inefficiently cooled. The use of high pressures, however, in itself somewhat reduces this formation of steam bubbles and the less intense heating of the rear bank of tubes causes a further reduction to a sible limits.

In addition, due to the substantially uniform heating of all the water tubes, their expansion is likewise approximately uniform, a factor which assists in maintaining steam-tight the points where the tubes are expanded into their drums.

The importance of a definite and efiicient water circulation in high-pressure boilers of the kind in question is well known and special attention is given to this point in the present invention.

degree within permis- With the object indicated, the feed-water I from the feed-water heater passes directly into the upper drum, 7, (7) of the front bank of water tubes. Further, the drum, 7,

(7) is connected by balancing tubes, 34 (34 to the drum 8, (8) which in turn is connected to the lower drum, 3, (3") 'of the front bank of tubes by the unheated downcomers, 13 (13*) or if the drum, 8, (8) is not present, the drum, 7, (7) is connected directly to the lower drum, 3, (3) by the downcomers, 13', (13). The colder feed water then mixes in the upper drum with the boiler water and descends through the unheated downcomers to the lower drum, 3, (3) from which it flows through the unheated connecting tubes, 35, (35 to the lower drum, 2, (2) of the bank of tubes, 5, (5) to ascend finally in the bank of vertical tubes, 5, (5). The bendin of a part of the tubes of the bank, 5, (5) at 11, (11 to the upper container, 7, (7) is provided in the first place to assist the water circulation in the bank of tubes, 4, (4) and in the second place to distribute the intensity of evaporation as uniformly as possible over the entire heating surface of the evaporator, A.

The water circulation takes place for the most part in two principal streams. The first main stream passes from the upper drum, 7

(7 or from the upper, drums, 7, (7) and 8, (8) through the downcomers, 13, (13) or (13, 13 to the drum, 3, (3) then through the tubes, 35, (35) to the drum, 2, (2 and thence to the drum, 7, (7) by way of those I of the flue,

3, at right angles to the plane of the paper, through the bank of tubes,

drums, 2, (2) and 6, (6) with the help of lateral downcomers which are embedded in .13 (13') and upwards in theheated tubes of the front bank, 4.

In Figure 4, are shown only the superheatertubes and headers of a modified form of the invention.

In this modification, the wet steam-from the pipe,- 15", lector header, 20 of that part of the superheater having tubes, 21*, lying in the special chamber through which the furnace gases pass. From the superheated steam distributor header, 22*, the steam passes through the pipe 19", to the collector header, 16, of the second part of the'superheater, the'tubes of which, 17, are arranged among the water tubes, 5, of the bank of tubes in the first sec tion of the main flue. The steam'ithus superheated to the desireddegree is then led from the second header, 18, of this part of the superheater through the pipe, 23", to the point required.

' This form of the invention, in which the primary superheater is placed in .the second section of the flue, and the secondary superheater in the bank of tubes in the first section has the advantage that a high temperature of superheat can be attained with a very small superheater heating surface as the secondary'superheating takes place in the first section of the flue where the hot gases still have a comparatively high temperature. The reduction in the superheating heating surface is attained as shown in Figure v4 by reducing incomparison with Figure 1 the number of bends or the like in the part of the superheater (in this case the primary superheater) lying in the special chamber.

As shown in Figure 5, the division of the superheaterin accordance with the present invention can also be applied to a boiler the water tubes of which are inclined at only a small angle.

In this case the superheater tubes, 17, of the primary superheater lie among and are parallel to the slightly inclined water tubes, while the tubes, 21, of the secondary superheater lie in a special chamber above a wall or partition, 36, the furnace gases passing through this chamber, in the direction of the arrows shown in full lines.

In this modification also, the degree of superheat can be regulated by altering the 5, (5) and the flows into the wet steam'col- H volume of furnace gases passing through the special chamber, this result being attained by closing to a greater or less extent the inlet to the chamber by means of a damper, 37, thus causing that part of the furnace gases shut ofi to followa path below the brickwork, 36, to the second section of the flue.

The water-tube'boiler also comprises the water tubes, 5, passing from the front headers, 38, to the rear headers, 39. The front headers, 38, are connected to the drum, .40, and the rear headers to the drum 11, while above the drum, 40, a steam collector, 42, is arranged from which a pipe, 43, leads the wet steam to the wet-steam header,.16 of the primary superheater; the second header of this superheater being indicated a 18. This latter header is, connected by the pipe, 19, to the header, 20, of the secondary superheater, the superheated steam passing from the second header of this superheater through the pipe, 23, to any point required.

As shown in Figure 6, the form of the individual headers is sinusoidal so that the superheater tubes, 17, can readily be arrangedbetween them, the position of these superheater tubes, 17, among the water tubes, 5, being shown on the left-hand side of Figure 6.

I claim; v

1. In a water tube boiler having front and rear banks of water tubes with upper and lower drums arranged after the manner of a roof-like combustion chamber over the grate and adapted to serveas the evaporator proper, and. front, rear and upper walls enclosing said tubes and drum, one of said walls being provided with a assage forming the sole outlet of the com ustion chamber, the water tubes being substantially aligned in the direction of gas flowand the rows of tubes of the rear bank situated between the outlet of said combustion chamber and the source of combustion gases, and being spaced so as to provide lanes of travel for the said gases; superheater tubes placed in said lanes extending longitudinally of the bank and throughout the greater length of the tubes of the bank so as to impede theflow of the escaping gases and cause a swirling of part of said gases toward and through the front bank of water tubes} i 2. Int boiler construction, a grate, a boiler .comprising front and rearbanks of water tubes converging upwardly above said grate, upper and lower water drums connected to said banks, front, rear and upper walls enclosing said boiler to form a combustion chamber, the rear wall being provided with a passage forming the sole outlet from said combustion chamber, the front bank of water tubes being positioned adjacent the front wall in a position to be heated by radiation from said grate, the rear bank of water tubes being spaced and substantially aligned in the direction of gas flow, and extending across said passage so as to be heated by the combustion gases as well as by radiation from said grate, superheating tubes longitudinally disposed among the spaces between the water. tubes of the rear bank and extending throughout the majorportion of the length of the length of the bank across said passage so as to impede the flow of combustion gases through said passage and cause a swirling of said gases through the front back of water 7 tubes.

gases to escape from said combustion cham-"' her only by passing through the said bank and said superheater elements.

4;. In a boiler construction, walls forming a combustion chamber, a boiler positioned adjacent said combustion chamber comprising front and rear banks of upwardly converging water tubes within the combustion chamber, upper and lower water drums connected to said banks, and a single outlet for combustion. gases from said combustion chamber, the rear bank of water tubes extending across said outlet, a part of the water tubes of the rear bank being bent upwardly iQJIISkCOIHIGCtGd to the upper drum of the front 5. A superheater for a water tube boiler having two banks of upwardly converging water tubes and a main passage for the combustion gases, said passage traversing only one of said banks, a first superheating stage arranged among the water tubes of said one bank, a chamber forming a part of said passage, a second superheating stage located in said chamber, said first stage being connected to receive the saturated steam from said boiler and to dry and partially superheat the same, said second stage being connected to said first stage to receive steam therefrom and being connected to the point of consumption of the superheated steam.

6. In a boiler construction, a combustion chamber having an outlet passage for gases of combustion,a,plurality of water tubes disposed between the source of heat energy and said outlet passa e, a steam drum connected with the water tu es, a primary'superheating stage arranged among the said water tubes and connected to receive saturated steam from said drum, a chamber forming a part of said outlet passage, a secondary superheating stage located in said chamber, said secondary stage being connected to the outlet of the primary stage to receive the dried steam therefrom and further superheat the same, and means for rendering said chamber and its enclosed secondary superheating stage inoperative In testimony whereof I have hereunto set my hand. v

OTTO H. HARTMANN.

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