US2049455A - Fluid heat exchange apparatus - Google Patents

Description

Aug. 4, 1936. c. E. LUCKE 2,049,455

FLUID HEAT EXCHANGE APPARATUS FTZ 'INVENTOR `Char/fes E. Luc/fe ATORNEY Aug 4, 1936. c. E. LUCKE FLUID HEAT EXCHANGE APPARATUS 2 Sheets-sheet 2 Filed Oct. 2l, 1935 VENTOR Char/es E'. Luc/e IIQNEY Patented ug. 4, 1936 PATENT OFFICE 2,049,455 FLUID HEAT EXCHANGE APPARATUS charles E. Lucke, New York,

The Babcock & Wilcox Company,

N. Y., assignor to Newark,

N. J., a corporation of New Jersey Application October 21, 1933, Serial No. 694,551 8 Claims. (Cl. 122-421) This invention relates to steam boilers, and is more particularly concerned with improvements in the construction and operation of economizers.

In many cases there are important installation advantages resulting from the use of counternow economizers arranged for an upow of heating gases especially when located above the boiler. For example, marked saving in construction costs are made by the elimination of constructions separated from the boiler setting, and draft losses are minimized by the elimination of gas turns.

This arrangement requires a down flow of water to maintain the counter-current relation with upiiowing gases, and the progressive heating of the water as it reaches successively lower levels involves some difliculties which it is an object of this invention to overcome.

One of the difficulties arises from the natural tendency for hotter water to rise and colder water to fall in an interconnected system between two different levels. The hotter water being at the bottom of the economizer, its buoyancy with reference to the colder water at the top tends to resist down flow and to set up a local circulation in the economizer. When feed water is shut off there is nothing to resist the rise of water, and, in fact, steam may be formed and the steam so formed is still more buoyant than the hot water and will rise to the top and there collect. Any Water below the boiling point that is thus met by the rising steam bubbles will condense them and cause them to collapse and produce water hammer which may destroy tubes or connections by shock stresses. It is frequently advantageous to proportion the economizer surface with reference to weight and temperature of gases, as to insure that steam be formed in the economizer under normal conditions, after the water has been brought to the boiling point. When this is done in an economizer having down ow of water, the lighter steam can be resisted in its tendency to rise and downiiow is everywhere maintained by a suiciently high ow velocity at normal loads. However, at reduced l loads for which the ow velocity is less, it Will not Abe possible to maintain the downfiow everywhere as is desirable Without some special means. An object of the invention is to prevent this action by reversing the flow of water during layover or light load periods, from down to up, and venting the top of the economizer to the drum.

Other objects of the invention will appear as the accompanying description proceeds.

The invention is described with reference to the accompanying drawings, in which:

Fig. 1 is a view in the nature of a diagrammatic vertical section showin-g the normal operation of a counterflow economizer positioned above a 5 boiler and having an upfiow of heating gases.

Fig. 2 is a view similar to Fig. l but indicating the operationof the economizer with its own convection circulation when there is no boiler load and feed water is shut olf.

Fig. 3 is a diagrammatic vertical section showing an economizer positioned at the side of the boiler, the arrows indicating the iiuid flow under normal boiler load conditions.

Fig. 4 is a view of the same kind as Fig. 3, but it shows the economizer circulation when there is no boiler load and feed water is shut off.

In Figs. 1 and 2 there is shown a counterow economizer I0 mounted above a boiler so as to receive the heating gases therefrom. This boiler includes the steam and water drum I2 connected to a bank of steam generating tubes IG. At one end of this bank of tubes there are downtake headers I6 connected by nipples I8 to the drum l2. At the upper ends of the steam generating tubes uptake headers 20 connect the tubes to the steam and Water circulators 22 which enter the drum.

Under normal operating conditions the header 24 functions as the inlet header for the economizer and there is a generally down flow of water in zig-zag fashion through the economizer tubes 26. These tubes preferably extend back and forth across the economiser gas pass so as to deliver separated streams of water to the economizer outlet header 28. This outlet header is connected through pipe sections 30, 32 and 34 to the water space of the drum l2. Feed water is supplied to the header 24 through pipe sections 36 and 38 vshown as connected by the valve 4l).

The normal operative conditions referred to iml mediately above are indicated in a diagrammatic Way in Fig. l, the arrows indicating clearly the path of the fluid proceeding to the steam and water drum. The ow is directly from the header 26 through the tubes 26 and the header 28 to the boiler drum l2. In other words, feed water delivered to the header 24 flows countercurrently downward with respect to heating gas flow, directly to the boiler.

Fig. 2 shows the illustrative economizer as it is operated when the boiler is not under a load. In this case the valve Ml is closed so that no feed wateris supplied. The valve 3| also is closed so that there is no opportunity for water to pass 5,5

from the bottom of the economizer directly to the steam and water drum of the boiler. To provide for convection circulation upward through the economizer under these conditions, the upper header 24 of the economizer is directly connected to the lower header 28 by the valve 42 and associated connections 44 and 46 providing a downflow of water outside of the economizer flue. In order that the economizer may be vented to the steam and water drum to avoid excess pressure under these conditions, the upper end of the economizer is connected by the valve 42 to a line 48 leading through the valve 50 and a pipe section 34 to the steam and water drum. In the normal boiler and economizer operation indicated in Fig. l, the valves 42 and 50 are closed as indicated. l

In the event that it is desired to accelerate the flow of water through the economizer during light load or layover conditions a pump may be used.

In Figs. 3 and 4 the boiler is indicated as the same type as that shown in Figs. 1 and 2, but the economizer 52 is located at such a position that all of its fluid heating surfaces are below the steam and water drum I2. 'I'he economizer is at the side of the boiler and receives the boiler heating gases through flues 54 and 56 connecting the last gas pass of the boiler with the lower end of the economizer flue for upflow over Ithe economizer as clearly indicated.

Fig. 3 indicates the arrangement of elements and the flow of fluid in the economizer under normal boiler load conditions. At such a time feed water is supplied at 58. It passes through the valve 60 to the upper header 62 of the economizer and then downwardly through the `economizer tubes to the lower header 64. From that header it passes through the line 66 which is connected to the water space of the steam and water drum at 68. Under these conditions the valve 'I0 interposed in the line 12 connecting the header 62 to the line 66 is closed.

When the boiler and economizer organization of Fig. 3 is not subjected to boiler load the valve 60 is closed as indicated in Fig. 4, and no feed water supplied to the upper economizer header 52. The valve 10 is open so that there may be a separate economizer convection circulation which is vented to the drum through the line 66.

The normal operation of the economizer with upflow of water is changed during the no load period when feed water is shut off, to upflow of wate, by the valves and piping connections, described and illustrated.

While the invention has been described with reference to the particular apparatus disclosed in the drawings, it is to be understood that it is not limited thereto, but that it is of a scope commensurate with the scope of the subjoined claims.

What is claimed is:

1. In a steam boiler installation, a bank of steam generating tubes, an economizer normally conducting a fluid including water back and forth across an upright gas pass and in a downflow from the top to the lower portion of the economizer, a first set of tubular connections providing for said fluid flow through the economizer and thence to said bank, a set of water llow reversing connections reversing the flow through the economizer and providing for a local natural circulation for the economizer, and means for rendering the first set of connections inoperative so as' to prevent said downflow, said water flow reversing connections being so arranged that the normal flow through said bank is unaffected.

2. In a steam boiler, a bank of steam generating tubes; a counterflow economizer connected to said bank and having an upflow of heating gases and a downflow of water under normal operating conditions, and water flow reversing connections between parts of the economizer for reversing the flow of water through the economizer when the boiler is under a light load to provide for a natural local convection circulation through the economizer with an upward flow of water, said connections including means regulating the flow at the normal inlet of the economizer and flow controlling means in the reversing connections, said water flow reversing connections being so arranged that the normal flow through said bank is unaffected.

3. In a steam boiler installation, a bank of steam generating tubes, a furnace from which hot gases pass across said tubes, a counterflow economizer through which the heating gases flow upwardly, the fluid space of the economizer being connected to the fluid space of said tubes, tubular connections communicating with the inlet and outlet of the economizer to provide for the normal downflow of water therethrough, said connections including a feed water pipe section leading to the inlet, and means providing for an independent local circulation circuit through the economizer during a lay-over period, the inlet being near the top of the economizer and the outlet being normally at the bottom of the economizer.

4. In a power generating installation, a bank of vaporizing tubes, means providing an upright gas pass, a fluid preheater normally conducting a fluid to be heated back and forth across the upright gas pass and from the top to the lower portion of the preheater where it is discharged into the bank of tubes, flrst tubular connections providing for said fluid flow through the preheater, and a second set of water flow reversing connections between parts of the economizer reversing the ilow of the fluid to be heated during a lay-over period and including some of the flrst connections, sai-d connections including means regulating the flow at the normal inlet of the economizer and flow controlling means in the reversing connections, said connections being such that a local circulation is set up in the economizer when said reversal takes place and said reversal taking place without affecting the flow through said bank.

5. In a steam boiler installation, a bank of steam generating tubes, a. furnace from which hot gases pass across said tubes, gas pass Wall structure providing for the passage'of furnace gases to the bottom of an economizer, a counterflow economizer through which the heating gases from the furnace flow upwardly, the fluid space of the economizer being connected to the fluid space of said tubes, tubular connections communicating with the inlet and outlet ol.' the 65 economizer, said water ow reversing connec- 75 tions being so arranged that the normal flow through said bank is unaffected.

6. In a steam boiler, a bank of steam generating tubes; a counter-W economizer, means providing for an upflow of heating gases through the economizer, the iiuid space of the economizer being connected to the iiuid space of said tubes,I

means providing a downiiow of Water through the economizer under normal operating conditions, and water ow reversing connections between parts of the economizer for reversing the flow o! water through the economizer during layover periods, or when the boiler is operating under a light load, said connections including means regulating the ow at the normal inlet of the economizer and flow controlling means in the reversing connections, said connections being so arranged that said reversal of iiow takes place without a corresponding change in said bank of tubes.

7. In a power generating installation, a bank of vaporizing tubes, an economizer normally conducting a uid to be heated back and forth across an upright gas pass and from the top to the lower portion of the economizer where it is discharged into the bank of tubes, iirst tubular connections providing for said iiuid flow through the economizer, and a set of valved connections between parts of the economizer reversing the iiow of the fluid to be heated during a lay-over period and including some of the rst connections, said second set also providing for an independent and complete circulation circuit through the economizer during a lay-over period, the reversal of fluid flow taking place in the econo- 5 mizer and said connections including means regulating the flow at the normal inlet of the economizer and ow controlling means in the reversing connections, said water flow reversing connections being so arranged that the normal ow through said bank is unaiected.

8. In a steam boiler, a bank of steam generating tubes, an economizer, means providing for a ow of heating gases through 'the economizer, the fluid space of the economizer being connected to the fluid space of said tubes, means providing a counteriiow of Water and heating gases through the economizer under normal operating conditions, and water iiow reversing connections between parts of the economizer for reversing 20 the flow of water in the economizer and causing a local economizer circulation during lay-over periods or conditions of light load, said connections including means regulating the flow at the normal inlet of the economizer and ow control- 25 ling means in the reversing connections, said water ow reversing connections being so arranged that the normal flow through said bank is unaiected.

CHARLES E. LUCKE. 30

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