US2866444A

US2866444A - Vapour generating and vapour heating units

Info

Publication number: US2866444A
Application number: US399812A
Authority: US
Inventors: Edward G Hutchings; Alan F Hodgkin
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1953-12-22
Filing date: 1953-12-22
Publication date: 1958-12-30
Anticipated expiration: 1975-12-30

Description

Dec. 30, 1958 E. G. HUTCH INGS ET AL 2,365,444

VAPOUR GENERATING'AND VAPOUR HEATING UNITS Filed Dec. 22, 1953 5 Sheets-Sheet 1 Inuen o mmfiw Dec. 30, 1958 E. G. HUTCHINGS ET AL 2,865,444

VAPOUR GENERATING AND VAPOUR HEATING UNITS 5 Sheets-Sheet '2 Filed Dec. 22, 1953 Dec. 30, 1958 E; G. HUTCHINGS Em 2,866,444

VAPOUR GENERATING AND VAPOUR HEATING UNITS Filed Dec. 22, 1953 5 Shets-Shet 4 as 4s 37 43 Dec. 30, 1958 E. G. HUTCHINGS ET AL 2,866,444

VAPOUR GENERATING AND VAPOUR HEATING UNITS File d Dec. 22, 1955 5 Sheets-Sheet 5 Inventors gas flow path.

VAPOUR GENERATING AND VAPOUR HEATING UNITS Application December 22, 1953, Serial No. 399,812

I 13 Claims. (Cl. 122-480) This invention relates to vapour generating and vapour heating units arranged to effect both superheating and reheating of vapour and more particularly to units intended to provide power for ship propulsion. During the astern operation of a ship, reheating of the vapour is no longer required, but a large quantity of vapour at a temperature of superheat below normal may be needed. An object of the invention is the provision of units suitable for giving high vapour outputs during periods when reheating of vapour is not required. A further object is to provide units in which safety of the reheaters is ensured during starting or periods of operation without reheating. A still further object is the provision of improved units such that the temperatures of superheat and reheat may be nicely controlled. Yet a further object is the provision of units suitable for providing relatively low temperature vapour at fractional loads.

The present invention includes a tubulous vapour generating and vapour heating unit comprising a first furnace chamber, a gas outlet from the first furnace chamber to a first gas pass containing vapour superheating surface, a gas outlet from the first furnace chamber to a second gas pass the path through which extends in parallel flow relationship with the path through the first gas pass, a second furnace chamber arranged to be separately fired and so disposed that gases may flow therefrom, without contacting the superheater, to the second gas pass and vapour reheating surface screened from the first furnace chamber and so located in the gas flow path from the second furnace chamber as to be untouched by gases flowing from the first furnace chamber.

The invention also includes a tubulous vapour generating and'vapour heating unit comprising first and second furnace chambers separated by a vapour generating tube bank including parts respectively disposed in two parallel gas passes leading from the first furnace chamber, separated by a passageway and provided with damper means adapted to control the distribution of gas flow through the passes,vapour superheating surface disposed in one of the passes, a gas flow path including the passageway leading from the second furnace chamber to the second pass and vapour reheating surface disposed in the said The invention furthermore includes a tubulous vapour generating and vapour heating unit comprising a first furnace chamber, two gas passes leading from the first furnace chamber and extending in parallel flow relationship, vapour superheating surface disposed within one of the passes, damper means for controlling the distribu- -tion of gas flow between the passes, a second furnace chamber arranged to be separately fired and extending along a side of the first furnace chamber remote from the gas passes, a gas flow path from the second furnace chamber leading to the first furnace chamber and vapour reheating surface screened from the first furnace chamber and so disposed in said gas flow path as to be untouched gases flowing from the first furnace chamber.

United States Patent The invention will now be described, by way of example, with reference to the accompanying, somewhat diagrammatic, drawings, in which:

Figure l is an isometric view, with some parts omitted, of one form of tubulous marine vapour generating and superheating unit, as seen looking towards a rear corner of the unit, parts of the unit having been broken away so as to iillustrate the arrangement of tubes therein;

Figure 2 is an isometric view similar to Figure 1, looking toward the other rear corner of the unit;

Figure 3 is a sectional plan view taken on the horizontal plane IHIII-III of Figure 1 or Figure 2;

Figure 4 is a sectional elevation on the line IV-IV of Figure 3;

Figure 5 is a schematic sectional elevation of a modified form of tubulous marine vapour generating and superheating unit;

Figure 6 is a sectional plan view taken on the line V[Vi of Figure 5;

Figure 7 is a view taken on the line VII-VII of Figure 5;

Figure 8 is a schematic sectional elevation of a further form of tubulous marine vapour generating and superheating unit; and

Figure 9 is a sectional plan view taken on the line IXIX of Figure 8.

The units illustrated in the drawings each include a first furnace chamber 1 and a second furnace chamber ports 9 are provided in the front wall 11 of the chamber 3 through which burners of a group 12 are arranged to discharge rearwardly.

The furnace chamber 1 is provided with a lateral gas outlet 121 which extends from front to rear of that chamber affording communication between the chamber 1 and parallel gas passes 13 and 15 which are separated by a passageway 17 and lead from the chamber 1 to a common uptake 19 within which heat exchanger surface, suitably an economiser 20, is provided. As an alternative or in addition to the economiser 20 an air heater may be provided within the uptake 19. Disposed within each of the

passes

13 and 15 at the entry to the uptake 19 is a group of dampers 21 movement of which, during operation of the unit, effects variation in the distribution of the total gas flow through the passes.

A vapour generating tube bank 23 including

sections

25 and 27 respectively disposed within the

passes

13 and 15 comprises tubes, upper and lower ends of which respectively open into a horizontal liquid and vapour drum 29 and a liquid drum 31 extending parallel with the drum 29. Within the pass 13, between the first furnace chamber 1 and the section 25 of the tube bank 23, is located a superheater 33 formed by horizontally extending, looped tubular elements 35, respectively connected between upright inlet and

outlet headers

37 and 39.

Large diameter tubes

41 and 42 connected between the

drums

29 and 31 serve to support the elements 35 and are arranged so that the superheater may be withdrawn forwardly through the side wall 43 of the pass 13 after removal of a part 45 thereof.

A screen 47, formed by rows 51 of staggered vapour generating tubes connected between the

drums

29 and 31, is disposed between the chamber 1 and the superheater 33. The tube rows 51 also extend across the outlet from the furnace chamber 1 to the pass 15 and form part of a tube bank 49.

A reheater 53 formed by looped tubular elements 55 connected between

headers

57 and 59 is arranged in the path of gases flowing from the second furnace chamber 3 and is shielded from that chamber by a screen formed by rows of staggered tubes. The location of the reheater is such that, during operation, it remains untraversed by gases flowing from the first furnace chamber.

The unit shown in Figures 1 to 4 includes a metallic casing 61. During operation, a space 63 inwardly of the casing is supplied, in known manner, with combustion air, through a duct (not shown) which communicates with the space 63 through an opening 65 in the roof 67 of the casing.

The side wall 69 and roof 71 of the chamber 1 are defined by a row 73 of vapour generating tubes which have radial studs (not shown) welded thereto for supporting refractory material supplied to the tubes and the row extends upwardly from a header 75 disposed at the bottom of the wall 69 parallel with the

drums

29 and 31. The upper ends of the tubes of the row 73 open into the liquid space of the drum ,29. The tubes of the rear part 77 of the side wall 69 and of the roof 71 are packed with refractory material 79 such as chrome ore, applied in plastic form, which also fills the inter-tube spaces. Those tubes of the row 73 lining the side wall 69 which are disposed near the front or firing end of the chamber 1 are further covered with refractory material as indicated at 81. The rear wall 83 of the chamber 1 is defined by row 85 of vapour generating tubes extending between lower and upper headers (not shown) suitably connected into the circulatory system of the unit and is formed in a manner similar to that of the part 77 of the side wall 65. The outside of the roof 71 and

walls

69 and 83 is covered with appropriate heat insulating mate rial S7. The floor 89 of the chamber 1 is formed with heat resistant tiles 91 backed by heat insulating material 93 and the front wall 5 comprises a layer 95 of heat resistant material backed by a layer 97 of heat insulating material.

The floor 101, side wall 103 and roof 105 of the second furnace chamber 3 are defined respectively by upwardly inclined sections 107, upright sections 109 and upwardly inclined sections 111 of a row 113 of vapour generating tubes of which each tube is connected between the drum 29 and a lower header 115, the latter extending parallel with the

drums

29 and 31.

The construction of the floor 101 and roof 105 is similar to that of the roof 71 of the chamber 1 and the side wall 103 is formed after the manner of the side wall 69 of chamber 1. A tube row 117 defines the rear wall 118 of the furnace chamber 2, which wall is constructed in a manner similar to that of the rear wall 83 of the chamber 1. The construction of the front wall 5 of the chamber 1 is appropriate also to the front wall 11 of the chamber 3 as is the construction of the part of the side wall 69 adjacent the firing end of the chamber 1 to the side wall 11.9 of the chamber 3 which is opposite the wall 103 of that chamber.

The furnace chamber 3 is provided with a lateral gas outlet 123 which extends between the inner end of the side wall 119 and the rear wall 118 of that chamber. The cooling tube screen 60 which is connected between the lower header and the drum 29 is disposed across the outlet 123, the latter affording communication between the chamber 3 and the passageway 17 which leads to the parallel gas pass 15.

Rear walls

125 and 127 respectively of the parallel gas passes 13 and 15 extend parallel with the side walls of the chambers 1 and 3 and are defined by the tube rows 129 and 131 the tubes of which are connected between the

drums

29 and 31. An outer part 133 of the wall- 125 and an outer part 135 of the wall 127 are each constructed in a manner similar to that of the part 77 of the first furnace chamber side wall 69. Tubes of the rows 129 and 131 respectively defining inner parts 137 and 139 of the

walls

125 and 127, have studs (not shown) welded thereto which extend laterally between the tubes and serve to support refractory material 121 filling the 4 inter-tube spaces, the refractory material being applied so as to leave

surfaces

143 and 145 of the tubes exposed respectively to gases from the chamber 3 and gases within the

appropriate gas pass

13 or 15.

Inner side wall 147 of the parallel gas pass 13 which also defines one side of the passageway 17 extends from the inner end of the rear wall 125 to the tube screen 47, whilst inner side wall 149 of the pass 15 which defines the other side of the passageway 17 extends from the inner end of the rear wall 127 towards the tube screen 47 and stops short of the screen so that a turning space 151, serving to direct gases flowing out of the passageway 17 towards the parallel pass 15, is provided between the screen 47 and the end of the passageway 17 adjacent thereto. Inner side walls 147 and 149 of the

passes

13 and 15 include tubes connected between the

drums

29 and 31 and are constructed in a manner similar to that of the wall parts 137 and 139 of the

rear walls

125 and 127, there being, however, in these walls, portions 153 and 155 which extend respectively alongside the

sections

25 and 27 of the tube bank 23 and each of which includes two,

rows

157 and 159 of tubes. The side wall 43 of the pass 13 is formed with heat insulating material and extends in line with the front wall 5 of the chamber 1, between that chamber and the outer end of the rear wall 125 of the gas pass 13, whilst the gas pass 15 has an outer sidewall 158 also formed with heat insulating material and extending in line with the rear wall 83 of the chamber 1 and between that chamber and the outer end of the rear wall 127 of the gas pass 15.

The

reheater headers

57 and 59 are vertically disposed in a wall part 159 extending between the rear wall 118 of the chamber 3 and the inner end of the outer wall part 135 of the rear gas pass wall 127. The tubular elemnts 55 of the reheater are horizontally disposed in the space between the tube screen 60 and the

rear walls

125 and 127 of the gas passes 13 and 15 and are supported in known manner upon a tube 161. Between the wall portion 133 of the rear wall of the gas pass 13 and the side wall 119 of the chamber 3 is defined a passage 163 at the inner end of which a removable panel 165 is provided through which the tubular elements 55 of the reheater 53 may be withdrawn forwardly.

It will be appreciated therefore that the superheater 33 may be withdrawn from the gas pass 13 through the side wall 43 upon removal of the part 45 thereof, whilst, owing to the provision of the removable panel 165, any defective reheater tube may be cut out, withdrawn forwardly through the passage 163 and subsequently replaced by anew tube.

Access doors

167 and 169 respectively provided in the

walls

43 and 158 facilitate repair and inspection of the walls 147 and 149 and the wall parts 137 and 139 and cleaning or replacement of vapour generating tubes, for example, of the bank 23.

Those skilled in the art will appreciate that many details unessential to a proper understanding of the invention have been omitted in the foregoing description of a tubulous marine vapour generating and superheating unit, such as the provision of downcomer tubes from the vapour and liquid drum 29 to the

headers

75 and 115 and the liquid drum 31 and of means for separating steam from water in the drum 29.

During normal operation, when both of the furnace chambers 1 and 3 are being fired, the gases from the second furnace chamber 3 flow through the tube screen 60, over the elements 55 of the reheater 53 and through the passageway 17 to the gas turning space 151, whilst portions of the gases from the first furnace chamber 1 respectively fiow through the screen 47 and the bank 49 to the gas passes 13 and 15, the gases flowing through the pass 13 contacting the superheater 33. By adjusting the firing rate of the burner group 12 associated with the second furnace chamber 3, the temperature of reheat may be regulated; by regulating the firing rate of the burner group 8 associated with the first furnace chamber 1 the vapour output or pressure from the unit may be regulated; and by control of the dampers 21 the temperature of superheat may be regulated. During manoeuvring, when the second furnace chamber 3 and the reheater 53 are inoperative, safety of the reheater is ensured since it is screened from the first furnace chamber and is not sub-.

ject to gas flow. Under such circumstances the first furnace chamber 1 may be fired at a high rate without undue draft loss since both the parallel passes 13 and 15 are exclusively available for the flow of gases from the furnace chamber. Moreover, good use is made of the whole of the tube bank 23.

During starting, the first furnace chamber 1 only is fired and starting may be rapidly effected without damaging the reheater 53 or superheater 33, since the reheater is screened from the first furnace chamber and is not subject to gas fiow, whilst the superheater is protected by the screen 47 and the flow of gases thereover may be controlled by the group of the dampers 21 at the exit from the gas pass 13. Normally, the group of the dampers 21 controlling the flow of gases from the chamber 1 over the superheater will be kept closed until steam is generated in the unit, and a flow of steam is established from the drum 29 through the superheater. Once such a flow of steam has commenced the dampers controlling the flow of hot gases over the superheater may be opened to a suitable extent.

Since the first furnace chamber may be safely fired alone while the reheater is inoperative, the unit may be worked to give a substantial output of vapour having little if any superheat, since the distribution of the gases between the parallel passes 13 and 15 is controllable.

The design of the unit may be such that normally or under some conditions of operation a part of 'the gases which flow from the second furnace chamber through the passageway 17 to the gas space 151 flows through the second parallel pass 15, whilst the remainder of the gases flows through the tube bank 49 to the first furnace chamber 1 and through the tube screen 47 and the pass 13.

Figures 5, 6 and 7 illustrate another embodiment of the invention in which the second furnace chamber 3 extends along the side of the first furnace chamber 1 remote from the parallel gas passes 13 and 15. A common wall 171 separates the furnace chambers and is defined by a row 173 of tubes, of which tubes such as the tube 175 have radial studs (not shown) welded thereto serving to support refractory material 174 which fills the inter-tube spaces and covers the tubes as indicated at 176 and 178. The inter-tube spaces between tubes such as the tubes 177 of the row 173 are filled with refractory material supported in the manner described with reference to the inner wall parts 137 and 139 of the rear

gas pass walls

125 and 127 of the unit shown in Figures 1 to 4. The second furnace chamber has a rear gas outlet 179 which occupies the width of the chamber and across which extends the tube screen 60. The tubular elements 55 of the reheater 53 extend Vertically at the rear of the screen 60 between the

reheater headers

57 and 59, the latter extending horizontally and parallel with the front wall 11 of the chamber 3.

Behind the reheater is a gas turning space 181 provided with a lateral outlet 183 which extends from the rear end of the common wall 171 to the rear wall 184 of the unit and across which extends a screen 185 comprising rows of staggered tubes. The screen 185 serves to protect the reheater from radiation from the chamber 1.

Removal of the reheater may be effected through side wall 187 of the gas space 181 upon removal of a side will portion 189 thereof. Further removable panels (not shown) are included in the outer side walls of the gas passes 13 and 15 and between the rear walls thereof so as to render the walls of the passageway 17, which comprise tubes having studs welded thereto which support refractory material in the inter-tube spaces, accessible for inspection and repair.

Operation of this unit is conducted in a manner similar to that described in respect of the unit shown in Figures 1 to 4. However, during starting-up or manoeuvring, when the second furnace chamber 3 is inoperative, the reheater 53 is protected from damage by radiation from the first furnace chamber 1 by the tube screen 185, whilst during normal operation, when both furnaces are being fired, gases from the first furnace chamber flow over the tube screen 60 and reheater 53 and turn in the gas space 181 to flow over the tube screen and enter the first furnace chamber. From the furnace chamber 1 the gases generated in that chamber and in the furnace chamber 3 flow through the parallel passes 13 and 15, the dampers of the groups 21 being positioned so as to control the distribution of the total gas flow through the passes.

In the unit illustrated in Figures 8 and 9 the second furnace chamber 3 extends along the side of the chamber 1 remote from the parallel passes 13 and 15 and is separated from that chamber by a wall 191 including tubes connected between lower header 192 and the vapour and liquid drum 29 and of similar construction to the wall 171 shown in Figure 6. A wing wall 193 extends across the rear end of the wall 191 and within the chambers 1 and 3 to define a lateral gas pass 195 between the wing wall and the rear wall 197 of the unit. The reheater 53 is disposed within the gas pass 195 and is flanked by the screen 60 which extends across the inlet to that pass and by the tube screen 185, comprising tube rows 186 and 188, which extends across the outlet therefrom. The tubes of the row 186 are bent so that lower portions thereof occupy the spaces between lower portions of the tubes of the row 188 to form a bafile wall in which studs welded to the tubes and extending therebetween serve to support refractory material filling the inter-tube spaces. The tubular elements 55 of the reheater extend horizontally across the pass and are connected at opposite ends thereof to the

headers

57 and 59 which extend vertically along the rear wall 197 of the unit.

A part 191 of the rear wall 197 of the unit is removable so as to enable the reheater elements 55 to be withdrawn rearwardly from the unit. Further removable wall portions (not shown) are provided respectively in the outer side wall 43 and between the rear walls of the

passes

13 and 15 to render accessible for inspection and repair the

side walls

205 and 207 of the passageway 17 which side walls are formed by tubes having studs welded thereto which support refractory material in the inter-tube spaces.

During operation of this unit, as in the case of the unit illustrated in Figures 5, 6 and 7, the reheater 53 is protected from radiation from the furnace chamber 1 by tube screen 185. Also, during normal operation, gases flow from the second furnace chamber 3 through the screen 69 over the reheater elements 55 and through the screen 185 into a region of the first furnace chamber 1 above the main combustion zone thereof. From the furnace chamber 1 the gases generated in that furnace chamber and in the furnace chamber 3 flow through the parallel passes 13 and 15, the dampers of the groups 21 being positioned so as to control the distribution of the total gas flow through the passes.

What is claimed is:

1. In a vapour generating and vapour heating unit, means forming a first furnace chamber having two gas outlets, means forming a second furnace chamber having a gas outlet therefrom, a vapour generating tube bank separating said furnace chambers, said tube bank being constructed and arranged to define first and second parallel gas passes each opening to one of said first furnace chamber gas outlets respectively, damper means adapted to control the distribution of gas between the two parallel gas passes, vapour superheating tubes disposed in the first parallel gas pass, means defining a third gas pass opening to the second furnace chamber gas outlet, vapour reheating tubes in said third gas pass, said generating tube bank being arranged to define a fourth gas passageway separating the two parallel gas passes, said fourth passageway connecting the second parallel gas pass and third gas pass, and means for independently firing said furnaces.

2. A unit as specified in claim 1 having vapour generating tubes disposed in each of said gas passes.

3. A unit as specified in claim 1 having a single gas flue in communication with both of said parallel gas passes and arranged to receive heating gases from both furnace chambers.

4. A unit as specified in claim 1 having means defining a gas mixing chamber at the entrance to said second parallel gas pass, said mixing chamber being in communication with said second parallel gas pass as well as third pass and a first furnace chamber outlet.

5. A vapour generating and vapour heating unit having a setting and comprising therein an upper horizontal vapour-liquid drum, a plurality of lower liquid distributing chambers, a multiplicity of vapour generating tubes connected between said upper drum and lower liquid chambers, means forming a first furnace chamber having a plurality of gas outlets to flow gas in the same general direction and in parallel flow relationship, means including some of said vapour generating tubes defining a first gas pass on one side of said first furnace chamber and having its inlet opening to one of said gas outlets, a bank of vapour superheating tubes disposed in said first gas pass, means including some of said vapour generating tubes defining a second gas pass parallel to said first pass and on the same side of said first furnace chamber, said second pass having an inlet opening to another of said first furnace gas outlets, means including some of said vapour generating tubes forming a second furnace chamber having a gas outlet at one end thereof, means forminga third gas pass with its inlet opening to said second furnace gas outlet and its outlet in communication with and arranged to flow heating gas to said second parallel gas pass, a convection type vapour reheater disposed in said third pass and arranged to receive heat solely from the heating gases of said second furnace, a single gas outlet fiue arranged to receive all of heating gases from both of said first and second parallel gas passes, and means for independently firing each of said furnace chambers.

5 6. A unit as specified in claim 5 having some of said vapour generating tubes arrangedas a tube bank in each of saidgas passes.

7. A unit as specified in claim 5 having said furnace chambers arranged to be fired from the same side of the unit setting.

bank within which said first, second and third gas passes are defined, said third gas pass arranged to open directly to the gas fiow entrance of said second parallel gas pass, said first and second furnace chambers being separated by said upright tube bank, and damper means arranged in the outlet of said first and second parallel gas passes to control the distribution of gas flow between said passes.

10. A unit as specified in claim 5 having said third gas pass outlet opening into said first furnace chamber.

ll. A unit as specified in claim 10 having some of said vapor generating tubes disposed in spaced relationship across said third gas pass outlet to act as a radiation screen.

12. A unit as specified in claim 11 having said third gaspass outlet arranged to discharge gas above the main combustion zone of said first furnace chamber.

13. A unit as specified in claim 10 having said furnace chambers arranged to be fired from the same side of the setting and said third gas pass outlet arranged to directly open into said first furnace chamber at the end thereof away from said firing means.

References Cited in the file of this patent UNITED STATES PATENTS 2,149,438 Hartmann et al Mar. 7, 1939 2,340,086 Southcott Jan. 25, 1944 FOREIGN PATENTS 595,910 Great Britain Dec. 29, 1947 609,674 Great Britain Oct. 5, 1948