US2082401A - Steam generating apparatus - Google Patents

Description

awe/whom June 1, 1937. M. H. KUHNER STEAM GENERATING APPARATUS 2 Sheets-Sheet 1 Filed Dec.

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MAX H KUHNER June 1, 1937. M. H. KUHNER STEAM GENERATING APPARATUS Filed Dec. 11, 1934 2 Sheets-Sheet 2 3 YW c/rvto'r, MAX A. KUHNER Patented June 1, 1937 UNi'lED STATES PATENT QFMQE STEAM GENERATING APPARATUS Application December 11, 1934, Serial No. 757,010

1 Claim.

This invention relates to steam generating apparatus, and more particularly to apparatus of this type having a desuperheater and means for controllingthe temperature of the desuperheated 5 steam.

In many industrial steam generating plants there is a demand for steam at different pressures and temperatures. High pressure high temperature steam is required for the production of power in steam turbines or engines, and low pressure low temperature steam is needed in connection with various manufacturing processes. In some cases low pressure steam may be required at a temperature lower than the boiling point of water at the high pressure, so that it is impossible to obtain the desired result by using the high pressure boiler water as a desuperheating medium. For economical reasons it is undesirable to provide two separate boilers to operate at different pressures, and-various prior constructions have accordingly been proposed to provide the required steam supplies from a single boiler. These prior arrangements have, however, been complicated, expensive,

5 bulky, and subject to various difiiculties in actual operation.

It is accordingly one object of the invention to provide a simple and inexpensive apparatus for producing steam at two different pressures go and temperatures.

It is a further object of the invention to provide a simple and reliable apparatus for accurately controlling the temperature of superheated steam.

It is a further object of the invention to provide a simple and reliable apparatus for 0btaining low pressure steam at a temperature below the boiling point of the water from which the steam is generated.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claim appended hereto.

Referring to the drawings illustrating one embodiment of the invention, and in which like reference numerals indicate like parts,

Fig. l is a longitudinal section through a steam generating apparatus, the section being taken on the line il of Fig. 2;

Fig. 2 is an enlarged section taken on the line 2-2 of Fig. 1; and

Fig. 3 is a section on the line 33 of Fig. 2.

I In the drawings I have illustrated a water tube boiler of a well-known type, comprising a mud drum It], a water drum H, and a steam and water drum i2. Drums l0 and H are connected by an upwardly and forwardly sloping bank of tubes l4, and drums H and I2 are connected by an upwardly and rearwardly sloping bank of tubes iii. A substantially vertical bank of tubes It connects drums Hi and 12. With this c'onstruction a complete circulating system is provided for the water and steam through'the drums and the interposed banks of tubes. A furnace or combustion chamber I3 is located beneath the tube bank lithe rear wall IQ of the chamber being beneath the mud drum l0, and the front wall 20 of the chamber being adjacent to the water drum II.

A steam drum 22 is mounted above the water drum l l, and a row of substantially horizontal tubes 23 leads from the steam and water drum I2 to the steam drum. The tubes 23 support refractory material 24 which forms a roof for the boiler.

The tubes of the first tube bank M are bent upwardly intermediate their lengths to provide a space for a superheater 26 therebeneath. The inlet'ends of the superheater tubes are connected to the steam drum Z2, and their outlet ends are connected to a horizontal header 2! located above the roof 24. A row of water tubes 28 ektends between the drums Hi and II below the superheater, to protect the superheater tubes to some extent from the radiant heat of the furnace. Baifies of refractory material are arranged to direct the hot gases from the furnace over the superheater 2i; and the tube banks Hi, 15 and H5 in the order named to a gas outlet 30. It will be apparent that all the steam generated in the boiler will be delivered to the steam and water drum l 2, and from this drum it will flow through the tubes 23 to the steam drum 22, and thence through the superheater 26 to the header 2?.

In passing through the superheater the steam will be raised to a high temperature and hence will be suitable for use in a steam turbine for the generation of power. Many industrial plants however require steam for process work as, well as power generation, and the process steam is usually needed at a lower temperature and pressure. Moreover, there is usually no definite relationship between the quantities required for the two purposes, and these quantities may vary entirely independently throughout the day.

In order to supply the process steam from the same boiler as the steam for power, I withdraw from the high pressure high temperature supply and then reduce both the temperature and pressure of this steam to the desired value. This temperature reduction is preferably effected by bringing the steam into heat-exchange relation with flowing water at a lower temperature through heat-conducting walls.

In the preferred construction illustrated I have provided a desuperheater comprising an inlet manifold 32 and an outlet manifold 33 connected by a group of horizontal tubes 34. These parts are shown mounted in the upper portion of the drum l2 above the axis of the drum and thus above the normal water level therein. The manifolds 32 and 33 are connected to nozzles 35 and 31 respectively, which are secured to the upper wall of the drum 12. Steam is delivered to the nozzle 36 from the superheater outlet header 2'! through a pipe 38, which is provided with a branch pipe 39 (Fig. 1) for delivery of high pressure high temperature steam to a steam turbine or other apparatus. A pressure reducing valve 4! is mounted in the pipe 38 between the branch 39 and the nozzle 36, this valve being of the well-known diaphragmoperated type. A pipe 42 is connected to the nozzle 31 for the delivery of low pressure low temperature steam to apparatus requiring the same, and the pressure in this pipe is transmitted to the diaphragm of the valve 4| through a small control pipe 43.

In order to reduce the temperature of the steam as it flows through the tubes 34, water at a comparatively low temperature is caused to flow in contact with the outside of the tubes. For this purpose I preferably utilize the feed water which is supplied to the boiler to replenish the water which has been changed to steam. In the drawings there is shown a casing 45 enclosing the tubes 34. A horizontal pipe 46 is welded to the bottom of the casing, and a row of openings 41 is provided in the upper wall of the pipe for the discharge of water therefrom into the interior of the casing. Slots 48 are provided in the upper wall of the casing so that the water may escape and thereafter mix with the boiler water.

The temperature of the steam as it leaves the desuperheater is regulated by controlling the efiectiveness of the heat exchange, and this is preferably accomplished by delivering a portion only of the feed water to the pipe 46 and controlling the amount so delivered. In the embodiment illustrated I have provided a proportioning valve 50 of the well-known diaphragmoperated type having an inlet 5| and two outlets 52 and 53. The .boiler feed water is delivered to the inlet 51 by a pipe 55, and the outlets 52 and 53 are connected to nozzles 55 and 51 respectively, which are secured to the upper Wall of the drum I2. The nozzle 56 is connected to the pipe 45 leading to the desuperheater, and the nozzle 51 is connected to a horizontal pipe 59 extending longitudinally within the drum and provided with a. row of openings 60 for the discharge of the feed water. The proportioning valve 50 is regulated automatically in accordance with the temperature of the steam in the delivery pipe 42. For this purpose the valve is connected by a small tube 6| with a temperature responsive bulb 62 located in the pipe 42.

The operation of the invention will now be apparent from the above disclosure. Hot gases from the furnace l8 pass through the boiler and generate steam at a comparatively high pressure, all of which flows through the superheater 26 and is raised to a high temperature.

. The superheated steam flows through the header 2'! and pipe 38, a portion being withdrawn through the branch pipe 39 for use in a turbine or other apparatus. The remainder of the steam flows through the valve 4|, where its pressure is reduced, and enters the tubes 34 where its temperature is reduced by the transfer of heat to the surrounding feed water in the casing 45. vThe steam then travels through the pipe 42 to a place of use. The valve 4| operates automatically to maintain a substantially constant pressure in the pipe 42. The feed water, which is ordinarily at a comparatively low temperature, is supplied by the pipe 55, and the valve 50 serves to proportion the water between the pipes 46 and 59 in accordance with the temperature of the steam in the pipe 42. It the steam temperature rises slightly, the valve will deliver a larger proportion of the water to the pipe 46, thus causing a more effective desuperheating action and maintaining a substantially constant steam temperature. A reduction in steam temperature will cause a similar action in the reverse direction. It will be noted that the area of wetted wall surface in the desuperheater remains constant, the steam temperature being controlled by varying the rate of flow of the feed-water through the interior of the casing 45.

By arranging the various parts in the manner disclosed, I have reduced the space requirements and heat radiation losses to a minimum. The use of feed water in the desuperheater makes it possible to reduce the steam temperature if desired to avalue below the boiling temperatude of the water corresponding to the boiler pressure. This is of great importance in many plants.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

Steam generating apparatus comprising a boiler having a horizontal cylindrical steam-andwater drum, tubes connected to the drum and arranged to deliver a mixture of steam and water thereto, additional tubes connected to the drum and arranged to withdraw water therefrom, a superheater arranged to receive steam from the drum, a desuperheater located within the drum and above the normal water level thereof, means to deliver steam from the superheater to the desuperheater, and means to deliver boiler, feed water to the desuperheater, the desuperheater having an outlet for the discharge of the feed water therefrom into the drum.

MAX H. KUHNER.

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