US1894791A - Desuperheater - Google Patents

Description

Jan. 17 1933. a w R DORF 1,894,791

'DESUPERHEATER Filed Aug. 1, 1931 2 Sheets-Sheet l lNVENTOR ATTORN EY Jan. 17, 1933. w, R'UDQRFF 1,894,791

DESUPERHEATER Filed Aug. 1, 1931 2 Sheets-Sheet 2 4.4 III IIIIIII III! ii? Iiiii ATTORN EY Patented Jan. 17, 1933 DAGOBERT W. RUDGRFF, 0F EEK YORK, ."cl'. Y., ASSIGNOE TO THE SUPERHEATER GCMEAHY, 8F NEW 5503K, N. Y.

DEfiUlEREEATEB .Appiicatieu filed August 1, 1931.

This invention relates to the art of desuperheating steam and relates more particularly to the case where superheated steam of high pressure is to be changed to desuperheated steam of considerably lower pressure.

The particular form of the apparatus used in the invent-ion is immaterial except that it must be apparatus in which the steam does not come into direct contact with the desuperheating agent. Ordinarily this desuperheating agent will be Water, this water being in a casing through which pipes extend containing the steam to be treated.

My invention has for its purpose to provide improved apparatus for and an improved method of treating steam in the manner and for the purpose indicated.

The high pressure steam under the conditions to which my invention relates is to be changed to steam of the lower pressure. This is effected by means of a reducing valve. Two arrangements can be used, and in practice have been used. The reducing valve may either be arranged in advance of the desuperheating apparatus or it may follow such apparatus. Under some conditions one or the other of these arrangements is satisfactory. There are, however, cases where neither of these old arrangements can be used. Suppose, for example, we have steam of iOOqqE pressure and 775 deg. F. total temperature which is to be changed to saturated steam at pressure. Assume further that the pressure in the water space is 401 i, which would be the usual situation making it possible to add the steam generated in the desup-erheater to the desuperheated low-pressure steam. It the reducing valve is placed at the outlet of the desuperheating apparatus, and the steam is reduced to saturation in the desuperheater before being expanded to the 40 pressure in the reducing valve, the steam after such pressure reduction will have a temperature of 33% or 67 degrees superheat. The desired result of having saturated steam at 40a pressure is therefore not obtained. One could of course condense a part of the high pressure steam and thereby ob tain saturated low pressure steam after expansion through the reducing valve. This,

Serial No. 554,452.

however, is a very unsatisfactory procedure largely because of the danger of injurying the reducing valve and the possibility of carrying water over into the low pressure apparatus.

If on the other hand the reducing valve is placed ahead of the desuperheating appara tus, then the steam at 40$]: pressure will have a temperature much nearerthe temperature of the desuperheating water and the heat so transfer will be less efiicient with the result than an unreasonably large desuperheater will be required.

my arrangement, apparatus is provided which is neither unreasonably large as under the second arrangement mentioned above nor has the disadvantages or impossibilities inherent in the first arrangement. Briefly, my arrangement includes a two-stage desuperheater with the expansion valve between them. Steam at the original high pressure is desupei'heated in the first stage substan tially down to its saturation temperature, or some other suitable temperature above this point, is then expanded to the lower pressure in the expansion valve, and then desuper- I heated to saturation temperature or other desired point above saturation temperature in the second stage of the desuperheater. Preferably, the two desuperheater sections are arranged in the same casing, the desuperheating tubesbeing immersed in the same b'oc y of water although this is optional.

1 illustrate my invention in the-drawings on the accompanying sheets where Fig. 1 represents a horizontal section on line 1-1 of Fig. 2, Fig. 2 shows an external prospective view on a smaller scale o1 the apparatus, and Fig. 3 shows a vertical central section on line 33 of Fig. 1.

The outer cylindrical casing 1 has its lower end closed by the hollow header 2 and has at its upper end an outlet 3. The space within the casing 1 is filled to the desired point with water which is supplied as required through the connection 4:. as is a connection for av safetyvalve. The inside of the header 2 is divided into the tour chambers 2a, 2b, 20 and 256' by the partitions 26, 2f, 2g, and 27a. A connection 5 communicates with space 2a; a connection 6 communicates with space 26; a connection 7, with space 2d and a connection 8, with space 20. The connections 6 and 7 are in turn connected to each other by means of the pipe 9 and pressure reducing valve 10, the latter being of any usual or preferred type. Rolled into the upper plate 11 of the header 2 are the lower ends of a plurality of tubes of inverted U-shape. One set of these, 12a, connects the two spaces 20 and 2d, and the other set, 12?), connects the two s aces 2a and 21). Both sets extend. upward into the space inside of the drum 1. Opposite the lower ends of the tubes 12a and 121) are openin s 13-13 through which tools can be inserte for rolling the tubes in. These openings are closed by means of hand hole covers when the apparatus is in use.

The operation of the apparatus 5 s as follows: lVater' is filled into the shell 1 to the desired height. The superheated hi h-pressure steam is admitted through the connection 5. It flows through the tubes 1% from chamber 2a to chamber 27). The water on the outside of the tubes 12?) desuperheats the steam. Preferably the apparatus is so designed that to do this at the pressure preveiling in the drum the water level is above the up an ends of the tubes 1%, although the design may be such that the level stands below such point. This desuperheated steam is next allowed to flow through connection 6 and pipe 9 to the expansion valve 10 where it ex ands to the lower pressure. The result will be lower pressure steam of a degree of superheat depending upon the amount of expansion. This superheated steam is next carried through connection '7 to flow through the pipes 12a where either all or the desired part of the superheat is removed, after which the steam is taken through connection 8 to the point of use. The amount of desuperheating in the tubes 12a can be accurately determined by the design.

It will be noted in the illustrative example shown in the drawings that the number of inverted U-shape tubes 1% is considerably smaller than the number of inverted U-shape tubes 12a. The actual relative numbers of these two will of course depend upon conditions such as the initial and final pressures, the initial temperature, and the final temperature desired. In any case, however, the total of the two will be cut down by my ar rangement by a large amount as compared with the total that would be required if the expansion valve were placed at the inlet of the apparatus.

As stated above, I prefer the arrangement in which both sets of tubes are placed in a common desuperheating casing, but it will be obvious that in some cases it might be desirable to have them in. separate casings. Moreover the desuperheating might be done in more than two stages with expansion valves between successive stages. These and other variations are clearly within the scope of my invention and are meant to be included within the appended claims.

I claim:

1. In the art of steam treatment the process of changing high-pressure superheated steam to low-pressure desuperheated steam comprising the steps of first abstracting a large part of the super-heat, then allowing the steam to expand to the lower pressure whereby it again becomes more highly superheated, and then finally reducing the superheat to the desired point.

2. In the art of steam treatment the process of changing high-pressure superheated steam to low-pressure desuperheated steam comprising the steps of first removing substantially all of the superheat, then reducing the pressure thereby again raising the superheat, and finally again desuperheating the steam by the desired amount.

3. Desuperheating apparatus including a stage in which high-pressure superheated steam is desuperheated by water in heat-exchanging relation but out of contact with the steam, a low pressure stage in which lowpressure superheated steam is desuperheated by water in l1eat-e:-:ehanging relation but out of contact with the steam, a pressure reducing valve, and connections to the high-pressure stage inlet, from the high pressure stage outlet to the valve, from the valve to the low pressure stage, and from the low pressure stage.

4. Apparatus in accordance with claim 3, a single drum containing the water for both desuperheating stages.

5. A desuperheater comprising a vertical cylindrical casing, a four-chambered header closing it at the bottom, two sets of inverted U-shaped elements secured to the header wall and extending into the cylindrical casing the first set connecting the header chambers in pairs, an inlet to one chamber of the first pair, a conduit including a pressure reducing valve connecting the second chamber of the first pair to a chamber of the second pair, and an outlet from the other chamber of the second pair.

DAGOBERT V. RUDORFF.

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