US2289969A

US2289969A - Fluid heat exchange apparatus

Info

Publication number: US2289969A
Application number: US205229A
Authority: US
Inventors: Howard J Kerr
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1938-04-30
Filing date: 1938-04-30
Publication date: 1942-07-14
Anticipated expiration: 1959-07-14
Also published as: US2413717A; FR853654A

Description

July 14, 1942. H. J. KERR FLUID HEAT EXCHANGE APPARATUS Filed April 50, 1 938 5 Sheets-Sheet l INVENTOR. Howard J Kerr ATTQRNEY.

3 Sheets-Sheet 2 July 14, 1942. H. J. KERR FLUID HEAT EXCHANGE APPARATUS Filed April 30, 1938 INVENTOR. Howard J Kerr ATTORNEY.

July 14, 1942. H. J. KERR FLUID HEAT EXCHANGE APPARATUS 3 Sheets-Sheet 3 Filed April so, 1938 Fig OOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOO 8900000000000 OOOOQOOOOOOQOOOOOOOOO 0O00000000OOOOOOOOOOOOOO000000000000 2 oounaoaaooou 00 caonooocacoo 8 .oonoeeooooaao INVENTOR. Howard J Keri" E l AT'fORNEY.

Patented July 14, 1942 UNITED STATE 2,289,969 FLUID HEAT EXCHANGE APPARATUS Howard J.-Kerr, Westfleld, N. J.,

Babcock a Wilcox Company,

assignor to The Newark, N. 3., a

corporation of New Jersey Application April 30, 1938, Serial No. 205,229

90laims'.

This invention relates to fluid heat exchange apparatus, and it is exemplified in improvements in water tube steam boilers whereby the safe steaming capacities of such boilers are increased.

In the art of steam generation progressively" greater efllcieneies havebeen attained by the utilization of higher operating pressures. Progressively higher rates of steam generation have also been a factor in the development of the art. Both factors have demonstrated the importance of securing eflicient steam and water separation without increasing the steam and water separating space in the drums. If this space were increased in accordance with prior art teachings, greater drum diameters would be necessary and, for the pertinent high pressures (of the order of 1000-2000 lbs. per sq. inch) the provision of drums of the necessarily greater diameter would result in excessive increases in drum wall thickness. They would be excessive from many standpoints including manufacturing limitations and cost-limitations. The present invention provides improvements which effect a safe degree of steam and water separation at high pressures and high capacity operation without necessitating drums of excessive diameter.

The high capacities of modern steam boilers have also made it particularly diillcult to insure continuous supply of dry steam without excessive drum capacity. The high heat input into the furnace wall tubes under such high capacity conditions causes those tubes to produce high velocity discharges of steam and water into the drum, and the natural tendency of this condition is to keep the steam and water mixed within the drum. Furthermore, the necessity of providing adequate ligaments in the drum prevents the concentration of the drum connections for such furnace wall tubes. They must be distributed over wide drum areas. This also has an additional tendency to produce high drum turbulence and make steam and water separation increasingly diflicult. The present invention overcomes these difficulties, and, in so doing, utilizes the high velocity of the discharges into the drum to promote steam and water separation and render a given boiler capable of supplying dry steam while operating at water levels higher than would otherwise be permissible.

The present invention also provides a means for increasing the safe steaming capacity or a natural circulation steam boiler by minimizing the amount of steam carried down with the water from the drum to the steam generating tubes, and by increasing the amount of water received by them, through an increase in the boiler circulation rate.

Another object of the invention is to provide improvements which will enable a given water tube steam boiler- 'to operate at maximum capacities by permitting effective operation of the boiler under high water level conditions. To accomplish these results, the invention contemplates the use or centrifugal water and steam separators having whirl chambers each of which is provided with an exit for the separated water limited to the region of the perimeter of the chamber, preferably tangentially. Other objects of the invention will appear as the following description proceeds.

The invention will be described with reference to the accompanying drawings in which certain embodiments of the invention are illustrated.

In the drawings:

Fig. 1 is a vertical section through a threedrum boiler of the bent-tube type, constructed in accordance with the teachings of the invention;

Fig. 2 is a vertical sectional view showing the front drum of the Fig. 1 boiler on an enlarged scale;

Fig. 3 is a detailed sectional view indicating the construction of the illustrative steam and water separator. This view may be considered as taken on the line 3-3 of Fig. 4;

Fig. 4 is a sectional view of the separator taken along a plane at right-angles to the plane of Fig. 3 and on such a section-line as that indicated at 0-4 of Fig. 3;

Fig. 5 is a vertical section taken upon the section-line 5-5 in Fig. 4 and looking in the direction of thearrows;

Fig. 6 is a vertical section of a two-drum type of bent-tube boiler to which the invention is applied in another manner;

Fig. 7 is a vertical section of the steam and water drum of the Fig. 6 boiler, on an enlarged scale;

. Fig. 8 is a horizontal sectional view of the Fig. 1 boiler taken approximately on the section-line 8-0 of Fi l; v

Fig. 9 is a horizontal section taken on the section-line 99 of Fig. 6;

Fig. 10 is a vertical section showing a modification of the structure indicated in Fig. 2.

Fig. l of the drawings discloses a bent-tube boiler having front and rear upper drums l0 and I2 connected with the submerged drum M by the banks of tubes i6 and I8, respectively. The steam generating tubes of the tube bank l8 are exposed to the heat of the furnace 20, the furnace gases passing over these tubes.

Steam and water is discharged by the tubes l8 into the front drum l0, and water together with some steamfrom this drum passes through the large diameter circulators 22, and then across the rear drum I2 through the

cross-over tubes

24 and 26 into the rear tubes 23 of the boiler. This arrangement permits the use of the pressure differential between the drums l and I2 to establish the tubes 28 definitely as downcomers, and with the use of the centrifugal-separators 30 interposed in the cross-over tube connections, the discharge through the circulators 22 is relieved of steam, and circulatory advantages are obtained because of the higher density of fluid in the tubes 28 over their full heights. The density of the fluid in these tubes is here compared with the density of the fluid in the tubes l8.

It will be understood that there are a number of the circulators 22 and a corresponding number of the separators 30 disposed longitudinally of the drum I2. The construction of the separators is indicated in Figs. 3 and 4 of the drawings. Each separator consists of a whirl chamber 32, operating independently of gravity to insure steam-free water in the downcomers 28 and thereby'increase maximum safe boiler capacity. The cross-over tube 24 is arranged tangentially to the whirl chamber 32 so as to set up a circular flow of water within that chamber. This fiow is indicated by the arrow 34 in Fig. 3. In the operation of the whirl chamber, the pressure of the water at its perimeter is substantially greater than the pressure in the center of the chamber, and the pressure of the water is sub stantially equivalent to the combined velocity of the steam and water entering that chamber from the inlet cross-over tube 24. The pressure at the perimeter of the chamber is always greater than the pressure in the center.

The liquid or water outlet of each whirl chamber 32 is provided in the present instance by the cross-over tube 26 which is arranged at the perimeter of the whirl chamber and preferably tangentially of that chamber. The latter arrangement is indicated in Fig. 3 of the drawings. The water in the whirl chamber outlet 26 will have a velocity substantially equal to the combined velocity of the vapor (or gas) the tangential entrance 24, whereby a pressure is developed in the water equivalent to this velocity.

The delivery water separators pressure of such steam and may be utilized to lift the water chamber 40, the delivery pressure will cause the separated water to be delivered, or discharged, from the separating zone against the resistance of the higher water level.

of this drum is above the 4 With reference to the steam and water separators 40, it is to be noted that they receive the restricted streams of steam and water mix.ures from the wall tubes 50 which are highly heated by reason of their exposure to radiant heat from the furnace 20. These wall tubes 50 are in communication with the risers 42 through the upper wall tube header 52.

In the form of the centrifugal steam and water separator indicated in Figs. 3 and 4 of the drawings the whirl chamber is closed except for the above mentioned steam and water inlet 24, the water outlet 26, and the steam outlet 54. The latter is arranged centrally of the whirl chamber so that the steam may be discharged axially of that chamber. The steam outlet 56 of the horizontally arranged separators 40 are similarly axially arranged.

The vertical baiile a higher percentage rators 30,

generating capacity.

' Fig. 10 shows an embodiment of the invention similar to that indicated in Fig. 2, but having the water outlet connection 65 for the water chamber 40 directly connected to and discharging into a downcomer as shown.

Steam vented from the separators 30 through the outlets 54 passes into the steam space of the I2 and thence through the steam scrubbers ofitake 64. From this ofitake it passes to a superheater 66, the relation of the superheater tubes to the remainder of the tubes of this boiler being indicated in Fig. 8 of the drawings. The furnace gases pass over the steam generating tubes [8 and then over the tubes of the superheater 66 through the first gas pass 68 defined by the boiler setting wall 10 and the baffle 12. In passing over some of the tubes of the bank l6 at the exit of the gas pass 68 the gases turn into the second gas pass 14, pass back across the tubes l6, and then make a second turn through a third gas pass 16. The tubes in the last two gas passes are separated from the gas flow equalization chamber by a baffle 82 which is shown in section in Fig. 1 From the outlet of the gas pass 16 furnace gases may pass over an economizer, and thence to an air heater,

Fig. 7 shows the arrangement of the illustrative densifier or steam and water separator 200 when used for primary separation of water and steam in the drum 202 of the type of boiler indicated in Figs. 6 and 9 of the drawings. The water and steam mixture discharged into the drum from the

steam generating tubes

204, 206, and 208, as well as the remaining steam generating tubes, is confined to a space 2") on the 202, this space being to a superheater the drawings at In the boiler illustrated in Figs. 6 and 9, furnace gases pass from the furnace ill across the steam generating tubes 2" in the first gas pass 232 and then around the rear edge of the bai'lle 234. The gases then pass forwardly over steam generating tubes 238 in the second gas pass 2". Beyond the tubes 23! the gases tum rearwardly of the bailie 240- and pass out of the boiler through the third gas pass 242.

What is claimed is:

1. In a water tube steam generator, a furnace, means forming a submerged water chamber, a plurality of upper steam and water drums, steam generating tubes connecting the water chamber to said drums and exposed to the heat of the furnace gases, wall cooling tubes associated with a wall of the furnace and arranged to discharge the steam and water mixture therefrom into one of said drums, whirl chamber densifying means within one of the drums and having direct connection with the wall cooling tubes so as to act upon the steam and water mixture discharged from the wall cooling tubes to separate thesteam and water of said mixture, the densifying means having an outlet connection to discharge the separated water in a confined stream to a'position beneath the water level of that drum, said densifying means discharging its separated steam directly into the steam space of said drum, downcomer tubes connecting the water space of a succeeding one of said drums with said water chamber, water circulators connecting the first of said drums to said succeeding drum, and crossover tubes so associated with the circulators and downcomers that water may flow directly to said downcomers from said first mentioned drum, means connecting the steam spaces of the drums, and steam offtake means arranged on one of the drums.

2. In a 3-drum steam generator of the bent tube type, a front upper drum, a rear upper drum, a steam outlet from the rear drum, means forming a lower water chamber, downcomers and steam generating tubes connecting said water chamber to said drums and extending across the path of furnace gases, steam circulators connecting the front and rear upper drums, means forming a circular whirl chamber of a steam and water separator disposed within the rear drum,

means for conducting steam and water directly from the front drum to a tangentially arranged inlet of the whirl chamber, and a direct connec-,

tion between a downcomer inlet and the water outlet of the whirl chamber conducting separated water in a confined stream from the whirl chamber to a downcomer, said whirl chamber being arranged with its steam outlet in direct communication with the steam space of the rear drum.

3. In a steam generator, a furnace, a plurality of upper drums, a lower drum, front and rearward banks of tubes connecting the lower drum to the upper drums and disposed in the path of the furnace gases, a rearward bank of tubes including downcomers, circulators connecting the upper drums, the front bank of tubes discharging steam and water mixtures into the front upper drum at high velocities by reason of the exposure of those tubes to furnace gases at high temperatures, means in a rearward upper drum directly connecting tubes of a rearward bank with circulators conducting steam and water mixtures from the front drum, kinetic steam and water separators in said connecting means, the separators having steam outlets communicating with the steam space of the rearward drum, the

separated water passes from the separators in confined streams tothe connected downcomer tubes of the rearward bank, and a steam outlet in said rearward drum.

4. In a steam generator, a steam and water drum normally having a water level therein, a steam offtake leading from the steam space of the drum, means forming a cylindrically walled whirl chamber of a steam and water separator within the drum, said whirl chamber being disposed at least in part above said level, steam generating tubes, steam and water inlet means directing steam and water eccentrically or tangentially into the whirl chamber at high velocity in such a way as to set up a whirling action of all of the steam and water in the whirl chamber, fluid confining means establishing direct communication between the steam generating tubes and the steam and water inlet means, said whirl chamber having an interior wall which is unobstructed in line with the steam and water inlet and at least to a position beyond the steam and water inlet, means including a restricted and liquid sealed whirl chamber outlet providing for the discharge of the separated water in a confined stream, outlet means beginning centrally of the end of the whirl chamber whereby separated steam may pass to the steam spac of the drum, and means connecting the water space of the drum to the inlets of the steam generating tubes, the whirl chamber and its outlet being constructed and arranged to cause water entering the chamber at the inlet to flow through the outlet with a velocity head sufficient at least to balance the static head of the water in the drum when the drum water level is higher than the level of the entrance of the outlet.

5. In a boiler having a steam and water drum and a plurality of steam generating tubes con nected to said drum, a centrifugal steam and water separator inside the drum and comprising a whirl chamber, a tangential steam and water inlet toward one end of said chamber, fluid confining means establishing direct communication between the steam generating tubes and the' whirl chamber inlet so that the whirl chamber said chamber, said whirl chamber having an interior wall which is unobstructed in line with the steam and water inlet and at least to a position beyond the steam and water inlet, a steam outlet at the end of said chamber nearest the inlet, and a restricted water outlet at the end of said chamber opposite the steam outlet end, constructed and arranged to cause water entering said chamber at said inlet to flow through said outlet with a velocity head sufficient at least to balance the static head of the water in the drum when the drum water level is higher than the level of the entrance to said outlet.

6. In a boiler having a steam and water drum and a plurality of steam generating tubes connected to said drum, a centrifugal steam and stantially the pressure of the mixture leaving the tubes to cause a whirling of the fluid within said chamber, said whirl chamber having an interior wall which is unobstructed in line with the steam and water inlet and at least to a position beyond the steam and water inlet, a steam outlet at the end of said chamber nearest the inlet, and a restricted water outlet at the opposite end of said chamber, constructed and arranged to cause water entering said chamber at said inlet to flow through said outlet'with a substantial continuation of the velocity of the water within said chamber.

7. In a steam generator, a steam and water drum normally having a water level therein, a steam offiake leading from the steam space of the drum, means forming a cylindrically walled whirl chamber of a steam and water separator within the drum, said whirl chamber being disposed at least in part above said level, steam generating tubes, steam and water inlet means directing steam and water eccentrically or tangentially into the whirl chamber at high velocity in such a way as to set up a whirling action of all of the steam and water in the whirl chamber, fluid confining means including a separate inlet compartment of the drum establishing direct communication between the steam generating tubes and the steam and water inlet means, said whirl chamber having an interior wall which is unobstructed in line with the steam and water inlet and at least to a position beyond the steam and water inlet, means including a restricted and liquid sealed whirl chamber outlet providing for the discharge of the separated water in a confined stream, outlet means beginning centrally of th end of the whirl chamber whereby separated steam may pass to the steam space of the drum, and means connecting the water space of the drum to the inlets of the steam generating tubes, the whirl chamber and its outlet being constructed and arranged to cause water entering the chamber at the inlet to flow through the outlet with a velocity head sufficient at least to balance the static head of the water in the drum when the drum water level is higher than the level of the entrance of the outlet, said inlet compartment communicating with .said inlet means on one side and having the steam generating tubes discharging thereinto at its opposite side.

8. In a boiler having a steam and water drum and a plurality of steam generating tubes connected to said drum, a centrifugal steam and water separator including a whirl chamber inside the drum, a tangential steam and water inthe inlet, and a restricted steam outlet at the end let toward one end of said chamber, fluid confining means including a separate inlet compartment of the drum establishing direct communication between the steam generating tubes and the whirl chamber inlet so that the whirl chamber receives the unseparated steam and water mixture from the steam generating tubes at substantially the pressure of the mixture leaving the tubes to cause a whirling of the fluid within said chamber, said whirl chamber having an interior wall which is unobstructed in line with the steam and water inlet and at least to a position beyond the steam and water inlet, a steam outlet at the end of said chamber nearest water outlet at the end of said chamber opposite the steam outlet end, constructed and arranged to cause water entering said chamber at said inlet to flow through said outlet with a velociy head sufiicient at least to balance the static head of the water in the drum when the drum water level is higher than the level of the entrance to said outlet, said inlet compartment communicating wih the outlets of the steam generating tubes and having direct connection with said whirl chamber inlet.

9. In a boiler having a steam and water drum and a plurality of steam generating tubes connected to said drum, a centrifugal steam and water separator including a whirl chamber inside the drum, a tangential steam and water inlet toward one end of said chamber, fluid confining means including a separate inlet compartment of the drum establishing direct communication between the steam generating tubes and the whirl chamber inlet so that the whirl chamber receives the unseparated steam and water mixture from the steam generating tubes at substantially the pressure of the mixture leaving the tubes to cause a whirling of the fluid within said chamber, said whirl chamber having an interior wall which is unobstructed in line with the steam and water inlet and at least to a position beyond the steam and water inlet, a of said chamber nearest the inlet, and a restricted water outlet at the opposite end of said chamber, constructed and arranged to cause water entering said chamber at said inlet to flow through said outlet with a substantial continuation of the velocity of the water within said chamber, said inlet compartment communicating with the outlets of the steam generating tubes and having direct communication with said whirl chamber inlet.

HOWARD J. KERR.