US2854960A - Vapor generating apparatus - Google Patents

Description

Oct. 7, 1958 VAPOR GENERATING APPARATUS Filed Oct. 2, 1953 3 Sheets-Sheet 1 99 52 /04 47 /04 55 Jnventor /V/pem/ FP/Jc/-f (Ittorneg Oct. 7, 1958 M. FRlscH vAPoR GENERATING APPARATUS 5 Sheets-Shea?l 2 Filed Oct; 2. 1953 nventor /7/Le7//v FIG/SCH tforneg Oct. 7, 1958 M. FRlscH VAPOR GENERATING APPARATUS Filed Oct. 2, 1953 3 Sheets-Shea?l 3 Cttomeg United States Patent Office 2,854,960 VAPOR GN'IATG APPARATUS Martin Frisch, New York, N. Y., assignor to Foster Wheeler Corporation, NewYork, N. Y., a corporation of New York Application october z, 1953, serial'Nmssasz'/ s claims.- (orizz- 441),

quite expensive. High. pressure joints are-required in sucliY heat exchangers because the feed water is introduced to the heat-exchangerat a pressure which is ator greater than boiler pressure and the pressure onthe outside of4 the hea't exchanger corresponds substantially to atmospheric pres'- sure. It has also been found that heat exchangers of the above type areV not wholly satisfactory becau-se leakageY of feed water oftentimes occurs at the tubesheetsY so that the steamin passing over the tubes becomes con-` taminated and causes damage to the superheater Vtubes andto the turbine. are employed toregulate the flow of feed water passing through the heat exchanger to control the temperature of the superheated steam, less than maximum eiciency isV obtained because some of the condensate produced in the heat exchanger is not carried in suspension'by the steam delivered to the` superheater.

In accordance with the present invention animproved novel vapor generating apparatus isprovidedwherein high pressure joints for high pressure heat exchangers are not required and contamination of steam passingin indirect heat exchange relationship with the feed Water is' prevented. p

The present invention provides a heat exchanger having joints subjecton both sides thereof to substantially the same pressure andl means are' provided for maintaining leakage feed water out of contact with-the steam passing through the heat exchanger. Maximum efciency ofte'mperature regulation ofthe superheated steam is obtained by the present invention in providing means for collecting substantially all the condensate produced in the heat`exchanger and delivering it in admixture'with the steam passing into the superheater.

The invention will be understoodfrom the followingV description when considered with the accompanying drawings in which:

Fig. 1 is a morelor less diagrammatical vertical sectional view illustrating the upper portion of a vapor generator embodying the present invention;

Fig. 2 is an enlarged portion of a section of a heat exchanger of the present invention disposed in the vapor generator of Fig. l and taken on line 2-2 of Fig. 4;V

Fig. 3 is an enlarged portion of a collectingtr'ough and aspirator tubes of the present invention;

Fig. 4 is an enlarged portion, in section, of the water and steam drum of the vapor generatorv of Fig. 1 and is taken along line 4-4 of Fig. 5; and

Fig. 5 is a plan sectional view of the heatexchanger of the vapor generator of Fig. 1'taken on line 5-5 of Fig.

Furthermore, where automatic controls' 2,854,960 Patented Oct. 7, 1958 4 and rotated 90 degrees about a vertical axis from the position disclosed in Fig. 4.

Like reference characters refer to like parts through out the several views. Y

'Referring nowto the drawings for a more detailed description Iof the present invention and more particularly to Fig. l wherein one embodiment thereof is illustrated, a vapor generating apparatus, generally designated by the numeral 10,\comprises a setting 11 havingl a combustion chamber 12 therein with a front Wall (not shown), arear wall 13,.and a roof 14 above which, is positioned a steamand Water drum 15. Water wall tubes 16 are provided along the front wall (not shown) of combustion chamber 142 and are connected at the uppery ends with the drum 15, while rear Wall 13'is provided with water wall-tubes 17 `also connected at the upper ends with the steam drum 15. A plurality of riser tubes 19 are arranged alongside Wall 18 and are connected at the upper end with a header 20 (shown in broken lines) which in turn communicateswith drum 15 through tubes 21 (shown in broken lines). Wall 18, and a side Wall (not shown) opposite the wall 1S may, if desired also be lined with water wall tubes communicatingV with an upper header, lsimilar to header 20,.which communicateswith drumv15. Riser tubes16,17 and 19communicate at their oppositeV ends withv headers (not shown) which headers receive feed water through dowhcomers (not shown) in communicationrwith drum 15 by a plurality of other downcomers 23.

Chamberv 12V is provided with a gas outlet 24 acrossn which outlet the upper portion of the Water wall tubes 17 extend. Gas outlet 24 communicates Witha downwardly inclined gas passage or heating zone 25 which passage communicates with a vertically extending gas passage 26 communicatingat the other end with a Hue (notsh'own).

A superheater comprising'an inlet section 2S, an intermediate section 29, and an outlet section 30 is disposed inthe path of gases of combustion flowing through passage 25 from gas outlet 24. Inlet section 28 receives steam from an inlet header 31 which in turn has steam delivered to it from drum 15 by a saturated vapor conduit 27. Intermediate section 29 of the superheater communicates with inlet seetionv28 through a header 32 and with outlet section 30 through a header 33. Superheatedsteam is Withdrawn from the superheater and delivered to an outleteheader 34 which receives steam from `outlet section 30. Feed water for the vapor generator of the present invention is fed to drum 15 through a, feed water distributing pipe 36 (Fig. l) extending longitudinallyfof the drumandconnected with a feedwater supply line 37. n

A heat exchanger 38 (Fig. 4) is arranged in the upper portion of a steam space 40 of drum 15 and comprises two inclined groups or sections 42 and 43 of horizontally` extending tubular members in spaced relationship with one another, the-outside of the tubes being exposed to the steam Within the steam space. The tubular members ex tend longitudinally of the drum 15, and the ends thereof are spaced from the end walls of the drum. Section 42 comprises upper and lower tube banks or parts 46 and 47, respectively, while section 43 comprises upper and lower tube banks or parts 49 and 50, respectively. l

Substantially rectangular shaped tube sheets 51 and 52 (Fig. 2) have openings which accommodate adjacent ends of the tubular members of upper and lower tube banks 46 and 47, respectively, and the tube sheets are separated by a pair of plates 53. Fixedly spaced from tube sheets 51 and 52 by van encompassing edge plate 55 are a pair of cover plates 56 and 57 which are in substantiall alignment with the tube sheets 51 and 52, respectively. The opposite ends vof tube banks 46 and 47 are accommodated within openings formed in a single tube sheet 58, and a cover plate 60 is fxedly spaced from the tube sheet by an encompassing edge plate 59. Cover plate 56 and tube sheet 51 together with the plates 53 and edge plate 55 define an inlet chamber 61 for tube bank 46 lwhich is in communication with a feed water conduit 62 connected to a source of feed water (not shown), while cover plate 57 and tube sheet 52 together with the plates 53 and edge plate 55 define an outlet chamber 63 for lower tube bank 47 which is in communication with one end of a substantially U-shaped transfer conduit 64. Cover plate 60 and tube sheet 58 together with edge plate 59 define a single chamber 65 which is in communication with both inlet and outlet chambers 61 and 63 by way of the tubular members of tube banks 46 and 47, respectively. The other end of transfer conduit 64 (Fig. 5) is accommodated within an opening formed in a cover plate (not shown) spaced from a tube sheet (not shown) for lower tube banks 50 of section 43. The construction and arrangement of section 43 is identical with the construction of section 42, and Fig. fully illustrates the construction of upper tube bank l49 of section 43. The end of section 43 opposite the end adjacent transfer conduit 64 has a chamber 67 in communication with the tubular members of both upper and lower tube banks 49 and 50, which chamber is defined by tube sheet 68 and cover plate 60 (Fig. 5). The end adjacent transfer conduit 64 has an outlet chamber 70 defined by a tube sheet 71, a cover plate 72, an encompassing edge plate 73 and a separating plate 74 (Fig. 4). Outlet chamber 70 communicates with one end of a feed water discharge conduit 75 accommodated within an opening formed in cover plate 72.

The path of flow of feed water through heat exchanger 38 may be traced as follows: The feed water enters inlet chamber 61 of tube bank 46 by way of feed-water conduit 62, passes through the tube bank 46 into chamber 65, thence through lower tube bank 47, transfer conduit 64, lower tube bank 50, into chamber 67 through tube bank 49 into outlet chamber 70 and thence is discharged from the heat exchanger by way of discharge conduit 75.

Reference will be made hereinafter to connector joints and it is to be understood that Ythe term when used will refer to the portions of the tube sheets, cover plates and associated ends of conduits secured thereto, the separating plates and the encompassing edge plate which define the inlet and outlet chambers for the tube banks.

Discharge conduit 75 projects through drum 15 and is connected to an externally disposed conduit 77 which has two projecting portions 78 and 79 extending inside of the drums (Fig. 4). Portions 78 and 79 are arranged in a pair of wash chambers 80 and 81, respectively, inside the drum, and openings 82 are provided in the upper part of the walls of portions 78 and 79 for discharging water into the wash chambers. Chambers 80 and 81 are partly defined by partition walls 83, 84, 85, and 86, respectively, which partition walls are spaced from the inner periphery of the drum and extend longitudinally to the opposite ends of the drum. Partition walls 83 and 85 cooperate with the inner periphery of the drum to define steam inlet chambers 87 and 88 communicating with riser tubes 21- and 16, respectively. Steam from the riser tubes enter inlet chambers 87 and 88 and pass into chambers 80 and 81 by way of openings (not shown) in partition walls 83 and 85. The steam in chambers 80 and 81 is washed by the water issuing from openings 82 in projecting conduit portions 78 and 79 and the washed steam passes from the chambers 80 and 81 into steam space 40 through outlets 90 and 91 adjacent portions 78 and 79 of conduit 77.

Disposed in steam space 40 are a pair of W-shaped chevron dryers 92 which are arranged between the outlets 90 and 91 and heat exchanger 38. vThe washed steam from chambers 80 and 81l flows through the dryers and thence over the tubular members of the heat exchanger 4 38 between the tube sheets, and passes out of drum 15 through a plurality of longitudinally arranged and parallel spaced openings or steam outlets 93 (two shown in Fig. 4) in drum 15. The steam conduits 94 (only two shown in Fig. 4) communicate with outlets 93 and deliver the 'steam to the superheater by way of conduit 27. The

steam in passing through the heat exchanger is cooled by the feed water which flows in indirect heat exchange relationship with the steam.

To obviate contamination of the steam by any leakage of feed water which may occur where the ends of the tubular members are secured to the tube sheets, a tube plate 95 is arranged adjacent to and spaced from the tube sheets of each section of the heat exchanger. Any feed water leakage occurring at the tube sheets ows between the tube plates and the tube sheets to discharge into the water space of the drum thereby preventing contamination of the steam passing between the tube, sheets.

The flow of feed water through feed water conduit 62 is regulated by a movable valve 96 (Fig. 1) arranged in the line. Movement of valve 96 is controlled by a con- Y troller 97 which is responsive to temperature variations of the steam leaving superheater outlet 34, the superheated steam being sampled by controller 97 by way of a conduit 97A connected to outlet 34. When the temperature of the superheated steam at the superheater outlet varies from a predetermined desired value, controller 97 operates to move valve 96 in the proper direction to regulate the ow of feed water to the heat exchanger. It will be understood that if the temperature of the superheated steam goes above the predetermined desired value, then valve 96 is moved in a direction to provide greater flow of feed water to the heat exchanger to thereby cool the steam passing into the superheater and, when the temperature of the superheated steam goes below the desired value, then valve 96 is operated to decrease the flow of feed water to the heat exchanger.

In order to provide maximum eiciency of operation of the superheat temperature control arrangement, all of the condensate produced by the heat exchanger 38 must be delivered to the superheater with the steam going thereto because controller 97 is calibrated on the basis that predetermined flows of feed water to the heat exchanger causes predetermined amounts of condensate. In the present arrangement, some of the condensate produced by the heat Vexchanger is not carried in suspension by the steam passing through the steam outlets 93 and therefore means are necessary for causing all of the condensate including the portion of condensate, not carried, to be delivered to the superheater. To this end, reservoir means or troughs 98 are arranged immediately below each of the sections of the heat exchanger to collect the condensate not carried in suspension by the outgoing steam. The troughs 98 (Fig. 4) each comprises a longitudinally extending bafe having a horizontally arranged portion 99 and a pair of vertically extending portions 101 and 102. Arranged adjacent the vertically extending portion 101 are a plurality of longitudinally extending vertical aspirator tubes 103 (only two shown in Figs. 3 and 4) which are secured at one end to the horizontally extending portion 99 and at their other ends extend through the steam outlets 93 and into the conduits 94. T he aspirator tubes 103 have openings or slots 104 adjacent the ends secured to the portions 99 and are at all times below the level of the condensate in the trough. Since the pressure within the steam conduits 94 is less than the pressure on the condensate in the troughs the condensate will bc sucked up or drawn through the aspirator tubes for admixture with the steam flowing through the conduits 94.

In operation, the steam from riser tubes 16, 17 and 21 passes into chambers 87 and 88 and flows therefrom into steam chambers and 81, where it is mixed with water from conduit 77. The steam. and Water mixture then flows from chambers 80 and 81 through chevron dryers 9,2 where the water is separated from the steam. The

Cu? resulting clean steam passes in indirect heat exchange relationship with the feed water flowing through the tubular members of the heat exchanger 3S and thence llows through the steam outlets 93 into the conduits 94, and iinally passes into the superheater. The condensate produced in the heat exchanger, which is not carried in suspension by the steam owing out of ldrum 15, falls into the condensate collecting troughs 98 and then is drawn up by the aspirator tubes to pass into the steam conduits 94 along with the cooled steam. Part of the heat output to the superheater is utilized to evaporate the condensed steam owing into the superheater so that the final steam temperature may thereby be controlled. By controlling the ow of feed water by means of valve 96, the temperature of the superheated steam at the outlet of the superheater may be effectively controlled.

lt is now apparent that the present invention provides a novel arrangement for eliminating high pressure joints in high pressure heat exchangers by utilizing connector joints within the steam and water drum. Furthermore, steam passing over the tubular members of the heat exchanger are prevented from being contaminated by leakage feed Water by the tube plates of the present invention. By utilizing all of the condensate produced in the heat exchanger, a more eilective means is provided to control superheat temperature.

Although one embodiment of the invention has been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the design and arrangement of the parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

What is claimed is:

l. Vapor generating apparatus comprising a vessel having a heated vapor therein and an outlet for said vapor, a heat exchanger in said vessel having a plurality of conduits arranged in a path of How of said vapor from said vessel through the outlet, means for introducing a fluid to be heated to said conduits and in heat exchange relationship with said vapor whereby the vapor is cooled and a portion thereof is condensed, reservoir means cooperating with said heat exchanger for receiving the condensate produced, and means in communication with said reservoir means and the outlet of said vessel and providing for admixture of said cooled vapor and the condensate from said reservoir means.

2. Vapor generating apparatus of claim 1 wherein the last mentioned vapor means comprises a hollow aspirator tube having its high pressure end in communication with the reservoir means and its low pressure end in communication with the outlet of said vessel.

3. Vapor generating apparatus comprising a vessel having a vapor therein and an outlet for said vapor, a conduit communicating with said outlet for delivering the vapor to a superheater, the pressure within said conduit being less than the pressure within said vessel, a heat exchanger within said vessel having a plurality of tubular members arranged in a path of tlow of said vapor from said vessel through said outlet, means for introducing a fluid to be heated to said tubular members and in heat exchange relationship with said vapor whereby the vapor is cooled and a portion thereof is condensed, a trough arranged below said tubular members for receiving and retaining the condensate produced, and a hollow member carried at one end by said trough and extending into said conduit at the other end, said hollow member having an inlet opening adjacent said one end below the level d of the condensate in said trough and an outlet opening adjacent said other end whereby the condensate in said trough is aspirated in admixture with the cooled vapor in said conduit.

4. Vapor generating apparatus comprising a vessel having a vapor therein and an outlet for said vapor, a heat exchanger in said vessel having conduit means arranged in a path of flow of said vapor from said vessel through said outlet, said conduit means having an inlet, a chamber communicating with a source of duid to be heated and with said inlet to provide passage of said fluid through said conduit means and in heat exchange relationship with said vapor whereby the latter is cooled and a portion thereof is condensed, said chamber having a wall iwith an opening for accommodating said inlet, reservoir means cooperating with said heat exchanger for receiving and retaining the condensate produced, means in communication with said reservoir means and the outlet of said Vessel and providing for admixture of said cooled vapor and of said condensate in said vessel outlet, and means deiining a leakage path for receiving leakage of tluid to be heated occurring at said opening, said last mentioned means including a second wall arranged between the path of ow of said vapor and said irst mentioned wall for maintaining the leakage uid out of contact with the vapor and the condensate in said reservoir means.

5. A vapor generator comprising a setting having a combustion chamber wherein gases of combustion are formed, a vessel having vapor and liquid spaces and a vapor outlet, means providing said vessel with liquid, vapor generating tubes connected to said vessel and extending into the combustion chamber whereby liquid from said vessel flows through said tubes and generated vaporized liquid in the tubes flows to the vessel, a super-heater in the setting connected to receive vapor from said Vapor outlet, a heat exchanger in said vessel having a plurality of tubular members arranged in said vapor space so that vapor passes over said tubular members when the vapor iloWs from the vapor space to the outlet, said tubular members having an inlet and an outlet, a chamber communicating with said inlet and receiving feed liquid for passage through said tubular members in heat exchange relationship with a vapor, a second chamber communicating with the outlet of said tubular members, each of said chambers having a wall for supporting the ends of the tubular members associated therewith, and means defining a leakage path adjacent each of the mentioned chamber walls tor receiving feed liquid leakage occurring at the portion of the Walls supporting the ends of the tubular members, said last-mentioned means including'a wall for maintaining the feed liquid leakage out of contact with the vapor passing over the tubular members and providing for discharge of leakage feed liquid into the liquid space of the vessel.

References Cited in the Vlile of this patent UNlTED STATES PATENTS 1,555,435 Rohrer Sept. 29, 1925 1,948,550 Voorheis Feb. 27, 1934 2,063,425 Fletcher Dec. 8, 1936 2,067,080 Frankel Jan. 5, 1937 2,232,936 Bimpson Feb. 25, 1941 2,287,592 Andrews June 23, 1942 2,343,897 Frisch Mar. 17, 1944 2,365,515 Bandry Dec. 19, 1944 2,655,905 Rehm Oct. 20, 1953 2,669,976 Frisch Feb. 23, 1954

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