US1917595A - Heater - Google Patents

Description

July l1, 1933. 1 R MCDERMET 1,917,595

HEATER Filed July 16, 1929 Wa fer @af/.0f

c)o 0000000o o oooooOoo/L 2 OOOOOOOOOO OOOOOQOOOO` 2 OOOOOOOOOO/O OOOOOOOOOO Patented July 11, 1933 UNITED STATES PA'I'E'ENT OFFICE JOHN R. MCDERMT, JEANNETTE, l?ENNSYLVANIA, ASSIGNOR T0 ELLIOTT COM- IPANY, OF JEANNETTE, PENNSYLVANIA, A CORPORATION OF 'PENNSYLVANIA HEATER Application led July 16,

The present invention relates broadly to the art of heat exchange, and more particularly to heat exchange apparatus of the type referred to as closed heaters.

In view of the fact that a steam turbine is fundamentally a device for converting heat energy into work and that steam is an effective carrier of heat, the efficiency of a steam turbine is dependent primarily on the amount of heat which the steam carries and the difference in temperature head available. The temperature head obviously measures the availability of the heat to be converted into work. In view of these conditions, it is quite customary to utilize steam having a high degree of superheat in order to obtain as large an amount of heat and heat head as possible. In the process of. expansion, as the steam passes through the turbine, the superheat is gradually destroyed and the steam finally arrives at the turbine exhaust in a saturated condition. y

It is customary in the art of heating feed Water for boilers in a modern station utilizing turbines to pass the water in' sequence through a plurality of closed heaters successively connected to stages on the turbine having increasing pressures, the increasing pressures being produced by the progressive expansion of the steam. Where a large number of heaters is utilized, certain of these heaters inevitably cooperate with the turbine at such a point that they receive superheated steam from the turbine.

A conventional closed feed water heater` will deliver water within from three to six degrees of the temperature of saturated steam, the difference in heat head measured by the three to six degrees being necessary` in order to force the heat through the heater surfaces.

It may thus be stated that superheat in steam lis extremely valuable from the standpoint ofthe turbine, but is of no value to a feed water heater other than the actual heat quantity which it contains. Feed water heaters as at present designed are not capable of raising the water temperature above the point indicated.

It is one of the objects of the present infor the opposite end. The head 4 1929. semi uo. 379,599.

vention to provide a heater of improved construction, eifective for utilizing heat in superheated steam for elevating the Water temperature ab ove the temperatures now attained with feed water heaters. By such a construction, the heater will also to some extent be able to utilize the heat head and thereby secure increased efficiency.

In the accompanying drawing I have shown more or less diagrammatically, a preferred embodiment of the present invention.

In the drawing Figure 1 is a longitudinal sectional view of one form of heater embodying the present invention, and

Figure 2 is a transverse sectional view on the line II-II of Figure 1, looking in the direction of the arrows.

In carrying out the present invention, there may be utilized a closed heater comprising a shell 2, provided with a closure 3 for one end thereof, and with a removable head 4 is of such construction as to provide a water inlet 5l and a water outlet 6. 4It is also provided intermediate the inlet andoutlet with transversely extending partitions 7 and 8, dividing the water box into a plurality of separate chambers. 1

Cooperating at one end with the tube plate S0 9 forming part of the header 4 is a nest of tubes so arranged as to provide successive passes p, p, p2, and p3. These tubes, at their opposite ends, cooperate with a floating head 10 mounted within the shell and providing a water box 11 formed with a transverse partition 12. By reason of the location and arrangement of the partitions 7, 8 and 12, it will be apparent that the water is caused to pass from the inlet to the outlet in the direction indicated by the arrows, the fiow being progressively through the passes p, p', p2, and p3.

A construction of the character referred to provides a heater of the so-called parallel shell type. Such a construction provides, of necessity, an annular space S around the entire tubenest, the dimensions of the annular space being determined primarily by the room required for the bolts which secure the 100 floating head in position, it being impossible to insert tubes in a space required for such bolts.

The shell may be provided with any desired form of steam inlet 13 by means of which the steam, in superlieated condition, as drawn from the turbine, is delivered to the interior of the heater and the space around the tubes.

Extending in substantially parallel relation to the tubes and substantially normal to the axis of flow through the inlet 13, is a baille 14, causing the steam to travel in the direction indicated by the broken arrows substantially along the tubes to the spaces 15 provided adjacent the ends of the baille.

Provided below the baille 14, and in substantially parallel relation thereto, are bailles 16 of similar construction extending to the ends of the tube nests, but spaced at their iiitermedi'ate portions to provide a port 17. This construction compels the steam.. which is passed through the spaces 15 to ilow in a direction substantially parallel to the tube axes to the port 17, and thence downwardly through the port in a direction at substantially right angles to the aXes of the tubes.

The space below the bailles 1G is divided into a series of chambers by means of bailles 18 and 19, the baillcs 18 being suitably secured to the baiiles 16 and providing a steam flow space below the lower ends thereof, while the baffles 19 extend into a position substantially adjacent the condenserrshell. Thisstaggered arrangement of the bailles requires the steam to pass in a direction generally at right angles to the tube axes, the direction ,being reversed adjacent each of the bailles. Adjacent the ilow termini of the steam in the heater are provided vents 20, by means of which the air and other noncondensable gases are withdrawn from the heater shell. The heater is also provided with one or more condensate drains Q1.

With a construction as described, that portion of the heater above the baille 14 comprises a space occupied by tubes and a portion of the space S which is available for steam distribution.

The area of the space available for steam distribution is preferably greater than the area occupied by the tubes. This not only insures eilieient distribution of the steam` but provides a comparatively large quantitypt steam in contact with the tube pass 793, which is the last pass through the heater and the one in which it is desired to raise the temperature of the water to its highest point. The baffles 1S and 19, on the other hand, substantially completely cover and hug the circumference of the shell, except in so far as they provide steam ilow ports. As a resultot this construction', the annular .space S below the batHes 1G is divided in a manner different from that in which it is divided above these battles.

The superlieat of steam supplied to a heater is an extremely variable quantity in practice, so that it is not feasible to give precise figures to indicate the magnitude of the saving efi'ected by a construction of the character before described. In actual practice, however, I have found that it is possible to effect an increase in water temperature of from four to six degrees, this representing the additional amount of heat contributed hy thc superheat in the steam in contact with the last tube pass. The steam is giving up this heat quantity to the water in the last tube pass is substantially desuperheated, so that the section of the heater above the baille 14 may be considered as a desuperheating section or as a temperature boosting or elevating section, depending upon whether it is desired to construe the operation from the standpoint of the steam or from the standpoint of the water being heated by the steam.

The steam, after losing its superheat in the desuperheating section, passes through spaces 15 into contact with the tubes in the tube pass 722, and thence alternately across the tubes of the passes p andip.

To those skilled in the art, it will thus be apparent that I have provided a heater which may be efficiently directly connected to any desired stage of a turbine and which, when .so connected, is effective for utilizing the superhcat in the steam to obtain an increase in the temperature of the feed water being heated. At the same time, by destruction of the superlieat, it reduces the steam substantially to a condition of saturation ready for condensation in the succeeding passes oi the heater wherein there is rendered available the latent heat ot the steam in condensing.

I thus provide in a single structure a combined closed heater and desuperheater. In this combination, the desuperlieater is preferably of sueh construction that the area available for steam distribution is greater than that available for heating tubes.

The advantages arising from such a coinbination in a unitary structure are obvious from the statement of the problems attendant upon the use of superheated steam as hereinbeforc referred to.

While I haveherein illustrated and described a preferred embodiment of the present invention, it will be apparent that changes in the construction and operation ot the heater may be made without departing either from the spirit of my invention, or the scope of my broader claims.

I claim:

1. In a heat exchanger, a shell, tubes therein, bailling means dividing the interior of the shell into two substantially equal divisions, longitudinally extending bailling means cooperating with one division, and transversely extending bathing means cooperating with the other division. l

2. In a heat exchanger, a shell, a tube nest therein circumferentially spaced from said shell to provide a substantially annular space between the tube nest and shell, and battling means within said shell so arranged that a portion of said space on one side of the longitudinal axis ot the heat exchanger is available for free longitudinal steam flow throughout substa utially the entire length of the shell on opposite sides of a longitudinally extending battle while the space on the opposite side of said axis is divided transversely.

In a heat exchanger, a shell` a tube nest therein circumferentially spaced from said shell to provide a substantially annular space between the tube nest and slell, battling means within said shell so arranged that a portion of said space on one side of the longitudinal axis of the heat exchanger is available for free longitudinal steam flow throughout substantially the entire length of the shell while the space on the opposite side ot said axis is divided transversely, and longitudinally extending battling means for the portion of said space on the lirst mentioned side of the heat exchanger axis.

4. In a heat exchanger, a shell, a tube nest therein circumterentially spaced from said shell to provide a substantially annular space between the tube nest and shell, bathing means within said shell so arranged that al portion ot said space on one side of the longitudinal axis of the heat exchanger is available for free longitudinal steam flow throughout substantiallyl the entire length of the shell while the space on the opposite side of said axis is divided transversely, longitudinally extending battling means for the portion of said space on the lirst mentioned side of the heat exchanger axis and a steam inlet communicating with the portion of the space having a free longitudinal steam flow.

5. In a heat exchanger, a shell, tubes therein, longitudinally extending baliiing means dividing the interior of the shell into two substantially equal divisions, longitudinally extending battling means within one of'said divisions, and transversely extending bailling Ameans within the other of said divisions.

6. In a heat exchanger, a shell, tubes therein longitudinally extending baliling means dividing the interior of the shell into two substantially equal divisions, longitudinally extending baiiling means within one of said divisions, and transversely extending baffling means within the other ol'i said divisions, said longitudinally extending battling means contacting with said shell throughout the length of the bailling means.

7. In a heat exchanger, a shell, tubes therein extending longitudinally of the shell, means dividing the tubes into a number of distinct passes, a plurality of transversely extending baliling means cooperating with certain of said passes, and a plurality of longitudinally extending battling means extending to said shell and cooperating with other of said passes.

8. In a heat exchanger, a shell, a head at each end of the shell, water tubes extending longitudinally of the shell, means dividing the tubes into a plurality of distinct passes, there being a steam inlet into the shell adj acent the last tube pass, means cooperating with said last mentioned tube pass for producing a substantially unobstructed steam flow from said inlet longitudinally of the shell and in opposite directions along and in contact with the tubes of said last nientioned pass toward said heads then away from said heads' along a second tube pass, the steam flow space along the tubes of said last mentioned passes being unobstructed transversely from head to head, and means cooperating with other of the tube passes for producing a steam flow in a direction generally transversely of the shell and toward said heads. y

9. In a heater, a shellhaving a steam inlet, a tube nest having a water inlet and a water outlet, and battling means within said shell spaced from both ends of the shell but engaging the sides thereof and extending substantially parallel to the axes of the tubes of said nest, said bathing means providing thereabove a desuperheating space having a materially greater area available for steam distribution longitudinally of the shell than the area occupied by the tubes therein.

l0. In a heater, a shell having a steam inlet, a. tube nest having a Water inlet and a water outlet, battling means within said shell spaced Jrom both ends of the shell but engaging the sides thereof and extending substantially parallel to the axes of the tubes of said nest, said baiiing means providing thereabove a desupe'rheating space having a materially greater area available for steam distribution longitudinally of the shell than the area occupied by the tubes therein," baffling means below said first mentioned baffling means and extending substantially parallel thereto and engaging the ends of the shell,` and transversely extending batlling means entirely on one side only of said last mentioned batlling means.

In testimony whereof I have hereunto set m hand.

y JOHN R. MODERMCET.Y

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