US2133991A - Superheater - Google Patents

Description

Oct. 25, 1938. KERR I 2,133,991

SUPERHEATBR v Filed July 18, 1934 3 Sheets-Sheet 1 INVENTOR Howa rdJKerr A ORNEY 1 v Oct. 25, 1938. v H. J. KERR 2,133,991

SUPERHEATER Filed July 18, 1934 3 Sheets-Sheet 3 INVENTOR [:[award J Kerr NEY Patented Oct. 25, 1938 PATENT OFFICE sursanna'ma Howard .1. Kerr, Westileld, N. 1., assignor to The Babcock & Wilcox Company, Newark, N. J., a corporation of New Jersey Application July 18, 1934, Serial No. 135,780

21 Claims.

This invention relates to fiuid heat exchange apparatus and is more particularly concerned with improvements in the superhating of fluids used under high pressure.

An object of the invention is to provide improved apparatus for controlling and maintaining a constant superheat. A more specific obiect is to accomplish this control in such a manner that the superheating operation is further improved by the reduction of solids which may be contained in the steam entering the superheater, such reduction taking place before the steam entersthat section of the superheater which is subjected to furnace gases of high temperature. The operative life of the tubes of this section is thereby materially increased.

A further object of the invention is to accomplish superheat control by the use of a contact desuperheater acting upon the steam at high pressures, the apparatus for attaining this resuit effecting a substantial economy of installation at such pressures.

Further objects of the invention will appear from the following description of illustrative embodiments of the invention.

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

Fig. 1 is a diagrammatic view in the nature of a vertical section, showing a system illustrat- 0 ing the invention.

Fig. 2 is a view similar to Fig. 1, but showing another embodiment of the invention.

Fig. 3 is a detail view, mainly in vertical sec-' tion, showing the valve mechanism which con- 5 trols thedesuperheating.

t Fig. 4 is a. detail view showing one of the orifice plates in an intermediate header.

Fig. 5 is a view in the nature of a vertical section taken on the line 5-5 of Fig. 2.

40 Fig. 6 is a detail view showing the valve mechanism which may be employed in the system shown in Fig. 1.

Fig. -7 is a detail section of the valve mechanism of Fig. 6.

45 Fig. 8 is a plan view of the steam distributor 'in the desuperheater chamber.

In Fig. 1 there are shown 4 groups of tubes which preferably extend across a gas pass in which the gases are flowing in the direction in- 50 dicated by the arrow III. The tubes of the groups 12 and H are elements of a primary superheater. They are connected to an inlet header is and are arranged so that steam may flow therethrough the upper chambers l8 of'intermediate 55 headers 20. 7

- A secondary superheater in which the tubes of groups 22 and 24 are subjected to heating gases of high temperature, receives steam which is passed through the primary superheater. Their inlet ends are connected to the lower chambers 5 26 of the intermediate headers 20, orifice plates 28 being disposed between the upper and lowerv chambers of the intermediate header. The outlet ends of the tubes of the groups 22 and 24 are connected to an outlet header 30 from which 10 steam is conducted through a main 32 to a point of use.

The illustrative superheater is intended for use in a power generating installation in which power is developed by steam turbines using steam 15 at pressures of the order of 1200# per square inch. Such turbines show marked increases in efficiency as the superheat approaches a constant value, and a high efliciency of the entire installation is attained. The present superheater '20 apparatus also is advantageous when used with furnaces developing heating gases of high temperatures, Such temperatures are of an order which would cause frequent burning of the tubes of the high temperature section of the super- 25 heater in the event of excessive deposits caused by solids contained in the steam entering those tubes. The apparatus now being described maintains the desired superheat standard and reduces the percentage of solids which might 30 otherwise deposit in the tubes of the secondary superheater.

In the illustrative apparatus a variable part of the steam passing from the primary superheater is subjected to a contact desuperheater 85.

before it enters the inlet chambers 26 of the secondary superheater. The contact desuperheater includes a desuperheating chamber preferably formed by a cylindrical pressure vessel 34, of relatively small diameter and arranged in up- 40 right position. The upper part'of the desuperheater chamber, and by far the major portion oi. the chamber constitutes a steam and water separator 33. In the lower part of the chamber there is maintained a body of water of a concentration preferably less than that of the steam which passes therethrough from' the primary superheater.

The annular steam distributor 36 is positioned below the water level in the desuperheater chamber and is provided with a large number ofsmall lateral openings 35 from which steam passes in jets 31 through the water in the desuperheater chamber. Externally of the desuperheater chamber the steam distributor is connected with 56 the outlets of the primary superheater by connections which include the conduit 38 and the cross header 40. Nipples 42 join this header with the chambers I8 and a T 44 is included in the connections.

A second cross header 46 is positioned in front of the chambers 26 of the intermediate headers 20 and is connected thereto by a number of nipples 48. As shown, both cross headers are directly connected by the T 44 and the flanged fit-.

tings 50 and 52. When steam is being desuperheated the cross header 46 receives steam through a line 54 which is directly connected to the top of the steam and water separator 33.

When the conditions of operation are such that superheat is maintained at the desired temperature without intermediate desuperheating, the controlled portion of steam passes directly from header to header 46 by their interposed connection without passing through the desuperheater. In the event, however, that the temperature of the superheated'steam in the line 32 attainsv too high a degree, it is desirable that some of the steam passing from the header 40 to the header 46 be desuperheated. This is attained by movement of the valve 58 to such an intermediate position as that shown in Fig. 1 of the drawings. This valve is preferably pivotally mounted in the T 44 so that it can close off that part of the T communicating with the line 38 and establish direct communication through the T and between the headers 40 and 46. In order that the amount of steam desuperheated may vary directly with the increase in temperature of the steam in the outlet main 32 the valve is thermostatically controlled. The apparatus for accomplishing this result includes a thermally responsive element 60 mounted in the steam line 32 and connected to a valve actuator 62. The valve actuator is connected by a link 04 to a crank arm 66 mounted upon the valve spindle extension 68. This extension is illustrated clearly in Fig. 6 as being'operatively connected with a main valve spindle I0 which is rotatably mounted in the walls of the T 44. The valve 38 may be welded or otherwise rigidly secured to the main valve stem I0. The valve spindle extension 68 is rotatably mounted in a finned gland I2, the outer end of which cooperates with the member I4 to provide a stuffing box. This arrangement of elements causes the condensation of any steam which may leak through the T 44 around the main valve stem I0 into the journal provided by the member I2 and the resulting water acts as a lubricant for the valve stem extension 68.

It is desirable that a constant water level be maintained in the lower part of the desuperheater chamber and that this water level be at a position considerably above the steam distributor 36, or at such a level as that indicated at I6 in Fig. 1 of the drawings. When this water level is maintained by the admission of feed water a suitable feed water regulator 18 is provided. This is connected to a tube 80 extending into the desuperheater chamber, and the tube 80 is connected to the fluid heater 82 preferably consisting of coils positioned above the water level. The coils are for the purpose of preheating the water by surface heating of the coils by steam from the steam space. After passing through the heater the feed water discharges from a spray head 84 which causes the water to form a conical spray in falling. H

The fluid heater 82 is by preference a partof a feed water line to a boiler. In any case the water in the fluid heater 82 must be close to the saturation temperature of the steam in order to prevent water hammer in the fluid heater. This condition may be attained by passing the water through a preheater before it passes to the fluid heater 82. In starting the operation of the illustrative apparatus steam is caused to flow through the desuperheater chamber for an appreciable length of time before water is allowed to flow through the fluid heater 82.

Before the steam passes out of the desuperheater chamber it is caused to pass through a steam and water separator which has an effective area much greater than the cross sectional area of the desuperheater chamber. This separator is shown as including a number of ring sections which are spaced vertically of the chamber, and are of smaller and smaller diameter as the top of the desuperheater chamber is approached. The lower ring section '90 is preferably secured to the wall of the chamber in the position shown and has an annular channel 92 communicating with a drain tube 94 extending downwardly in the desuperheater chamber and having its outlet at one side of the feed water heater 82.

The ring section 96 next above the section 90 presents an upwardly opening channel 98 and'a downwardly opening channel I00, the diameter of the latter channel being substantially the same as that of the channel 92. Extending from the ring section 90 to the ring section 95 and disposed in the channels 92 and I00 is an annular band I02 of granular or fibrous material which may be held in place by any suitable means such as perforate plates. The channel 98 has a drain pipe I04 which is at one side of the feed water heater. As shown, the remaining parts of the separator are constructed and arranged similarly to those above described, and the entire construction is such that all of the desuperheated steam must pass through the granular or flbrous material before it emerges from the desuperheater and passes through the conduit 54 to the header 40.

The desuperheater'is provided with a water gauge construction I06 and there is a drain I08 for the desuperheater chamber, to be used to control the concentration of the water. through the drain I08 can be governed bythevalve IIO so that the concentration of the water in the desuperheater can be less than the concentration of steam that enters the desuperheater from the primary superheater.

In the embodiment of the invention shown 'in Figs. 2 and 5, the steam leaving the primary superheater may be led directly to the desuperheater chamber I I2 through a plurality of con duits II4. Internal upright tubes IIIi constitute substantial extensions of the conduits H4 and are arranged within the desuperheater chamber as clearly indicated in Figs. 2, 3, and 5. At the lower ends of these tubes there are disposed steam distributing manifolds II 8 positioned beneath the water level I20 which is maintained by a feed water regulator I22 disposed in a line I24 leading to the feed water heater I26, the arrangement and functioning of these elements being somewhat similar to those in the Fig. 1

' embodiment.

Desuperheated steam is led directly from the desuperheater chamber I I2 to the inlet chambers 26 of the secondary superheater by conduits I30 which are connected to the tubes II6 within the desuperheater chamber as clearly shown in Fig. 3 of the drawings. This figure discloses flanged tubular drum connections I32 preferably expanded in openings in the wall of the chamber uh and welded to that wall as indicated at m. Within the flanged portion I30 there is positioned a perforated tube I 88. This tube is preferably held rigid with the connections I24 by a circumferential weld I40.

Each tube I38 has a perforate section I42 which joins the tube H6. At this point oLJuncture there is arranged a valve I44 which may rotatefrom the position indicated in full lines to that indicated in dotted lines. In the full line position shown, no steam is being desuperheated, all of the steam coming from the primary superheater passing through the connections shown in Fig. 3 directly to the secondary superheater. when the valve is in its dotted line position all steam passing through the conduits H4 is desuperheated before it passes to the secondary superheater. Different amounts of steam will be desuperheated depending upon the intermediate position to which the valve ismoved. In order that the amounts of steam desuperheated may vary directly as the temperature changes in the line 22 the valve I44 is connected to a valve actuator I46 which is governed by a thermally responsive element I41 disposed in the line 32. The connections between the valve I44 and the actuator I 48 include a rock shaft I48 connected to the actuator by a link I50. This connection is externally of the desuperheater chamber, the rock shaft passing into the chamber through a stui'iing box I52 and being rotatably mounted in supports I54 which are fixed to the wall of the chamber. Each valve has a crank arm I56 rigid therewith, and the outer end of each crank arm is connected to a rock arm I58 rigidly mounted on the rock shaft. .This connection is through a linklfll.

As indicated in Fig. 3 mounting of the tubes I IS in the drum is carried out in the same manner in which the tubes I08 are mounted. Connections for accomplishing this include the tubular drum connectors I02, and the circumferential welds I04 and I00.

The desuperheater chamber H2 is provided with a gauge glass 0 and a drain pipe I12 by the control of which the concentration of the water in the desuperheater chamber may be maintained at a figure preferably less than that of the concentration of the steam to be desuperheated.

Fig. 2 shows the superheater casing I14, which confines the heating gases so that they will contact with the superheater elements. It will be understood that the arrangement of superheater.

tubes 01' the Fig. 1 modification will, in practice, be positioned within a gas pass which is formed by such a casing as that illustrated in Fig. 2.

It will also be understood that, in practice, the various conduits must be arranged somewhat diilerently than they are shown in the drawings. For example, the conduits 38 and 54 as shown in Fig. 1 of the drawings must be offset or provided with large radius bends where they cross each other.

Relative to the thermally responsive devices shown in the drawings it will be understood that the elements 60 and I41 are connected to the valve actuator mechanisms 82 and I 46 by tubes I10 and I which contain expansible fluid.

The steam distributor 36 is shown'in detail in Fig. 8 of the drawings. It preferably consists of two annular parts I82 and I94, the latter being mounted within the former and held rigid therewith by connecting members Il6.- These annular parts may have a cross section such as that indicated in Fig. 1 of the drawings and they are Joined by a connector I88, preferably located opposite the steam inlet for the distributor.

Referring again to the steam and water separator in the upper part of the pressure vessel 34 it will be understood that above the annular band I02 there are mounted similar bands I00, I92, etc., until a top-most band I94 of relatively small diameter is reached. A cap I 96 prevents the steam from freely flowing from the separator without first passing through the granular or fibrous material of the bands. At the top of the pressure vessel 34 there is provided a manhole 200 through which there may be access to the parts of the steam and water separator. This manhole is normally closed by the members 202, 204 and 206.

The valve construction shown in detail in Fig. 6 of the drawings is intended to indicate that the finned gland I2 is rigidly held against the annular boss 208 formed on' the side of the T 44. It may be detachably secured thereto by bolts.

At the other end of the finned gland I2 there is a stufilng box construction which includes a flange sleeve 2I0. The latter may be secured to the flange portion 2I2 of the finned gland by means of bolts so as to compress packing material 2I4. The valve spindle extension 68 has on its inner end an enlarged portion 2I6 which forms a shoulder bearing against the left-hand end of the finned gland and the main valve spindle I0 is extension 68. The extension 68 is not subjected to the same conditions of temperature and fluid flow which affect the operation of the main valve spindle I0.

It will be understood that the orifice plates 28 may be removed and that other plates having oriflces of diflerent sizes substituted therefor.

The illustrative apparatus which involves an upright cylindrical desuperheater chamber has the advantage of lower cost of installation, to-

gether with the advantage of permitting the instaliation of a steam and water separator which has a separating area much greater than the cross section of the desuperheater, or separator chamber.'

In the operation of the apparatus shown in Fig. 1 it is to be appreciated that there will be a change in the quality of the steam entering the desuperheater chamber. A considerable portion of whatever solids may be carried by the steam will be removed and the life of the tubes of the high temperature section of the superheater will be correspondingly increased.

While the invention has been described with reference to the particular embodiments shown in the accompanying drawings, it is to be understood that the invention 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 steam conditioning apparatus, a primary luperheater section, a second nines-heater section subjected to a heating medium at higher temperature, connections providing for a continuous fiow of part of the steam leaving the primary section directly to the second section without intermediate desuperheating, a desuperheater including a water chamber, a regulator for maintaining a predetermined supply of water in the chamber, a by-pass means causing steam from the primary section to pass through the water in said chamber and then to the second section in amounts directly proportional to variations of the exit temperature of the steam from the second section, and ,means including elements of the bypass means associated with the desuperheater to cause a part of the by-passed steam to pass directly to the second section without-contact with the water in the desuperheater chamber and to vary the latter part inversely as the exit tempera= ture of the steam from the secondary section.

2. The" method of superheating steam and regulating the temperature thereof which consists in supplying steam to a high temperature superheater and raising its temperature therein, leading the superheated steam from the superheater to the point of use at substantially the exit temperature of the superheater, regulating the exit temperature of the superheated steam from the superheater by supplying it with superheated steam at a temperature which varies inversely as the temperature of steam leaving said superheater, and conditioning the inlet steam supplied to the high temperature superheater by causing the inlet steam to pass through water and then in counter-flow relation through a spray in amounts which vary directly with the temperature of the steam leaving the superheater.

3. In apparatus for superheating steam and controlling the final temperature thereof, a first superheating section of low temperature, a sec-- ond superheating section of high temperature subjected to the same furnace gases as the first section, connections imposing a fixed resistance to the dew of steam from the first section to the second but always permitting a certain steam how, a desuperheater chamber, tubular means establishing communication between the outlet of the first section and the lower part of the chamber at a position below its water level, steam distributors at the outlet ends of said means, feed regulating devices for maintaining such a predetermined water level in the chamber that there is a large separation space above that level, a steam and waterseparator in said space, means connecting said space and the inlet or" the high temperature section, a by-pass through which communication is established between said tubular means and the inlet of the second section above the water level, means varying the steam flow through the by-pass inversely to superheat changes at the outlet of the second section and varying the steam. fiow through the distributors directly with said superheat changes.

4. In a device for superheating steam andregulating the temperature thereof, a fuel-fired aieaaai providing a water spray through which the steam must pass after passing through a body of water in the desuperheater.

5. In a device for supplying superheated steam, a first and a second stage of superheating involving the preheating of steam before it reaches the second stage, means for feeding steam in a successive manner from a source of supply through the two stages of superheating, means for heating the steam in second stage of superheating by furnace gases at a temperature higher than the heating gases of the first stage, a direct action desuperheater including a spray head above a body of water and steam supply means below the surface of the body of water, said desuperheater being located between the stages and causing the steam to be spray washed after it passes through a body of. water and before it reaches the second stage, and means for varying the amounts of preheating of the steam before it is delivered to the second stage.

6. In superheat regulating apparatus, a primary superheating section of low temperature in which steam is heated by'furnace gases, an upright cylindrical pressure vessel acting as a desuperheater chamber and having a large ratio of height to its diameter, a steam heated fluid heater in the pressure vessel, means at the outlet of said fluid heater for causing the fluid discharged therefrom to form a spray, means associated with the heater to control the flow of fluid therethrough and maintain a water level in the lower. part of the chamber, an annular steam distributor mounted in the chamber below said water level, means for connecting the outlet of said low temperature superheater section to the steam distributor so that steam will pass up through the water in the bottom of the pressure vessel, a steam and water separator in the upper part of said pressure vessel for separating water from the steam which proceeds from the distributor and past the spray, a high temperature superheater section constantly receiving a part of the steam directly from said low temperature section, means connecting the steam and water separator to the inlet of said high temperatm'e section, a bypass connecting the outlet of the low temperature section and the inlet of the high temperature section, and means associated with the by-pass to vary the amount of steam passing through the by-pass inversely as the temperature of steam varies at the outlet of the high temperature section.

7. In the superheating of steam for power purposes, generating steam, imparting a primary degree of superheat to the generated steam,'sub jecting a part of the resulting superheated'steam to a steam washing action wherein the superheated steam is contacted with water to efiect desuperheating and a reduction in. the entrained solids, subsequently separating water from the steam leaving said water contact .by an action in the nature'of a mechanical filtration, returning the washed and purified steam to a high temperature superheating zone wherein the washed steam joins steam passing directly from the zone of primary superheat, and maintaining an inverse ratio between temperature of the steam at the outlet of the high temperature superheating zone and the part of the generated steam which is not subjected to the steam washing action.

8. In a superheater including a high temperature section and a low temperature section, a direct contact desuperheater including an upright cylindrical pressure vessel operatively interposed I greater than the cross section of the vessel, means for causing a proportion of the steam leaving the low temperature section to pass through the water in the desuperheater, and means for varying said proportion directly as the temperature of the steam leaving the high temperature section, said last named means also varying the temperature of the steam at the inlet of the high temperature section inversely as the exit temperature of the steam from that section.

9. In steam conditioning apparatus, a primary superheater section, a secondary superheater section subjected to heating gases of higher temperature, connections providing for a \continuous flow of part of the steam leaving the primary section directly to the secondary section without intermediate desuperheating, a desuperheater including an upright cylindrical water chamber, a regulator for maintaining a predetermined water level in the chamber, a steam and water separator above said water level, means causing steam from the primary section to pass through the water in said chamber and then to the secondary section in amounts directly proportional to the exit temperature of the steam from the secondary section, and means associated with the desuperheater to cause a part of the steam from the primary section to pass directly to the secondary section without contact with the water in the desuperheater chamber and to vary that part inversely as the exit temperature of the steam from'the secondary section.

10. The method of superheating steam and regulating the temperature thereof which consists in supplying steam to a high temperature superheater and raising its temperature therein, leading the superheated steam from the superheater to the point of use at substantially the exit temperature 01' the superheater, regulating the exit temperature of the superheated steam from the superheater by supplying it with superheated steam at a temperature which varies inversely as the temperature of steam leaving said superheater, and conditioning the inlet steam supplied to the high temperature superheater by washing and subsequent filtering in amounts which vary directly; as the temperature of the steam leaving the superheater.

11. In the production of superheated steam for power purposes, generating steam, imparting a primary degree of superheat to the generated steam, subjecting a part of the resulting superheated steam to a steam washing action wherein the superheated steam is contacted with water to effect desuperheating and a reduction in the entrained solids, subsequently separating water and any entrained solids from the steam leaving said water contact by an action in the nature of a mechanical filtration, returning the washed and purified steam to a high temperature superheating zone wherein the washed steam joins steam passing directly from the zone of primary superheat, utilizing furnace gases as the heating medium in the high temperature zone and maintaining an inverse ratio between temperature of the steam at the outlet of the high temperature superheating zoneand the proportion of the generated steam which is not subjected to the steam washing action.

12. In steam treating apparatus, a pressure vessel forming a steam chamber, means for maintaining a water level in said chamber, means for causing steam to be discharged in the chamber below said level, a fiuid heater above the level, discharge means whereby said heater discharges a spray of water across the chamber and downwardly toward said level, a filter type steam and water separator positioned above said discharge means and having a separating area greater than the cross section of the chamber, and steam discharge means at the upper part of the chamber.

13. In a superheater including a high temperature section and a low temperature section, a direct contact desuperheater operatively interposed relative to the sections, means for maintaining a predetermined water level in the desuperheater, means for causing a part only of the steam leaving th low temperature section to pass through the water in the desuperheater before it reaches the high temperature section, means providing a water spray through which the steam must pass after leaving said water, a steam and water separator above said spray means, and means for varying said part in direct proportion to temperature changes in the steam leaving the high temperature section, said last named means also varying the temperature of the steam at the inlet of the high temperature section inversely relative to temperature changes in the steam from that section.

14. In superheat regulating apparatus, a primary superheating section of low temperature in which steam is heated by furnace gases, a pressure vessel presenting a desuperheater chamber and a large steam and water separator space, a steam heated fluid heater in the pressure vessel, means at the outlet of said fluid heater for causing the fiuid to be discharge therefrom downwardly in the form of a spray, means associated with the heater to control the flow of fluid therethrough and maintain a desired water level in the lower part of the chamber, a plurality of steam distributors mounted in the chamber below said water level, means for connecting the outlet of said low temperature superheater section to the steam distributors so that steam will pass up through the water in the bottom of the pressure vessel, a steam and water separator in the upper part of said pressure vessel for separating water from the'steam which proceeds from the distributor and then through the spray, a high temperature superheater section constantly receiving a part of the steam from said low temperature section before it passes to the distributor, means connecting the steam and water separator to the inlet of said high temperature section, a bypass connecting the outlet of the low temperature section and the inlet of the high temperature section, and means associated with the by-pass to vary the amount of steam passing through the by-pass inversely as the temperature of steam varies at the outlet of the high temperature section.

15. In the superheating of steam for power purposes, generating steam, imparting a primary degree of superheat to the generated steam, subjecting a part of the resulting superheated steam to a steam washing action wherein the superheated steam is passed through a body of water of a concentration less than that of the superheated steam and contacted with a water spray to effect desuperheating and a reduction in the washed steam joins steam passing directly from the zone of primary superheat, and maintaining an inverse ratio between temperature of the steam at the outlet of the high temperature superheating zone and the part of the generated steam which is not subjected to the steam washing action.

16. In a superheater including a high temperature section and a low temperature section, a direct contact desuperheater including a pressure vessel operatively interposed intermediate said sections, means for maintaining a predetermined water level in the desuperheater, a steam and water separator in the pressure vessel above said level, means for causing a part only oi the steam leaving the low temperature section to pass through the water in the desuperheater, and means for varying said part in a ratio directly related to temperature changes in the steam leaving the high temperature section, said last named meansalso varying the temperature of the steam at the inlet of the high temperature section inversely to changes in the exit temperature of the steam from that section.

17. In steam conditioning apparatus, a primary superheater section, a secondary superheater section subjected to heating gases of higher temperature, connections providing for a continuous flow of part of the steam leaving the primary section directly to the secondary section without intermediate desuperheating, a desuperheater including a water chamber, a regulator for maintaining a predetermined water level in the chamber, a steam and water separator above said water level, means causing steam from the primary section to pass through the water in said chamber and then to the secondary section in amounts directly proportional to the exit temperature of the steam from the secondary section, and means associated with the desuperheater to cause a part of the steam from the primary section to pass directly to the secondary section without contact with the water in the desuperheater chamber and to vary that part inversely as the exit temperature of the steam from the secondary section.

18. The method of superheating steam and regulating the temperature thereof which consists in supplying steam to a high temperature superheater and raising its temperature therein, lead: ing the superheated steam from the superheater to a point of use at substantially the exit temperature of the superheater, regulating the exit temperature of the superheated steam from the superheater by supplying it with superheated steam at a temperature which varies inversely as the temperature of steam leaving said superheater, and conditioning a part of the inlet steam supplied to the high temperature superheater by washing in amounts which vary directly as the temperature of the steam leaving the superheater.

it. In the production of superheated steam for power purposes, generating steam, imparting a primary degree of superheat to the generated steam, subjecting a part of the resulting super heated steam to a steam Washing action wherein the superheated steam is contacted with water to effect desuperheating and a reduction in the entrained solids, subsequently separating water and any entrained solids from the steam leaving said water contact returning the washed and purified steamto a high temperature superheating zone wherein the washed steam joins steam passing directly from the zone of primary superheat, utilizing furnace gases as the heating me= dium in the high temperature zone and maintaining an inverse ratio between temperature of the steam at the outlet of the high temperature superheating zone and the proportion of the generated steam which is not subjected to the steam washing action.

20. In steam treating apparatus, a pressure vessel forming a steam chamber, means for maintaining a water level in said chamber, means for causing steam to be discharged into the chamber below said level, a fluid heater above the level, said heater including tubular elements heated by the steam discharged into the chamber by said second mentioned means, discharged meanswhereby said heater discharges a spray of water across the chamber and downwardly toward said level, a steam and water separator positioned above said discharge means, and steam discharge means at the upper part of the chamber.

21. A steam heating and temperature regulation system including, in combination: a pair of steam heater sections arranged for serial flow of gases across the tubes thereof; a connection between said sections providing for serial flow of steam therethrough; the arrangement of the sections being such that the second stage heater section is in advance of the first stage with respect to the direction of gas flow; a desupersecond stage heater section through said desuperheater and directly from the first stage heater section prior to the time of entrance of the steam into the elements of the second stage heater section.

' HOWARD 5. my;

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