US1963524A - Method and apparatus for generating steam - Google Patents

Description

M. H. KUHNER METHOD AND APPARATUS FOR GENERATING STEAM June 19, 1934.

Filed July 29, 1932 2 Sheets-Sheet 1 1 INVENTOR MAX H. KUHNER BY W ATTORNEY June 19, 1934. M, H, KUHNER 1,963,524

METHOD AND APPARATUS FOR GENERATING STEAM Filed July 29. 1932 2 Sheets-Sheet 2 F l6 2 LW MAX H. KUHNER A TTORNEY Patented June 19, 1934 METHOD AND ArPARA'rUs Fort GENERATING STEAM Max lL'Kuhner, Worcester, Mass, assignor to Riley Stoker Corporation, Worcester, Mass, a corporation of Massachusetts Application July .29, 1932, Serial No. 626,09

3 Claims.

- This invention relates to a method and apparatus for generating steam and controlling the temperature of superheated steam, and more par-- 'ticularly to the generation of steam at two differ- 25 cut pressures and temperatures.

In many industrial steam generating plants there is a demand for steam at different pressures andtemperatures. 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. .For economical reasons it is undesirable to provide two separate boilers to operate at'different pressures, and l 18 various prior constructionshave accordingly been proposed to provide the required .steam supplies froma single boiler. These prior arrangements have, however, been complicated, expensive, bulky, and subjectto various difficulties in'actual operation.

.It is accordingly-the main object of the inventiontoprovide a simple and inexpensive method of. producing steam at two different pressures and temperatures, together with a compact and reliable apparatus for carrying on the said method of steam-production.

;It is a furtherobject of the invention toprovide 'a simple and reliable method and apparatusfor accurately controlling the temperature of superheated steam. 7

With these and other objects in view, as will be "apparent to thoseskilled in the art, the invention resides in the combination of parts and the steps of the process set forth in the specification and a, covered by theclaims appended hereto.

-Referring to the drawings illustrating one em- 'ly needed at a lower temperature and .pressure. Moreover, there is usually no definite relation- I bodiment of the invention, and in which like reference numerals indicate like parts,

Fig. 1 is a longitudinal section through a steam the line 1-1 of Fig. 2;

Fig. 2 is an enlarged 2-2 of Fig. l;;and

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

section taken on the line ,In the drawings I have illustrated a water tube boiler of the well-known Badenhausen type, com- ..prising a mud drum 10, a waterdrumll, and a steam and water drum 12. Drums 10 and 11 are connectedby an upwardly and forwardly sloping 4150 bank of tubes 14, and drums 11 and 12 are con- 7 .hot gases from the ever require steam generating apparatus, the section being taken on and the interposed banks of tubes. A furnace or combustion chamber 18 is located beneath the tube bank 14, the rear wall 19 oi the chamber being beneath the mud drum 10, and the front wall 20 of the chamber being adjacent to the water drum 11.

A steam drum-22 is mounted above the water drum l1, and a row of substantially horizontal tubes 23 leads from the steam and water drum 12 to the steam drum. The tubes 23 support refrac- 1 tory material Zi'WhlCh forms a roof for the boiler.

The tubes of t e first tube bank 4 r ben upwardly intermediate their lengths to provide a space for a superheater 26 therebeneath. The inlet ends of the superheater tubes are connected j'to the steam drum 22, and'their outlet'ends are connected to a horizontal header 2'] located above the roof '24. vA row of water tubes 28 extends between the drums 10 and 11 below the superheater, toprotect the superheater tubes to some extent 57 -5 from the radiant heat, of the furnace.

Baflies 29 of refractory material are arranged todireot the furnace over the superheater 26 and the tube banks l4, l5 and 16 in the order named to a gas outlet 30. It will be apparent that all the steam generated inthe boiler willbe ,de-

livered to the steam and water drum l2, and from this drum it will flow through the tubes 23110 the steam drum 22, and thence through the superoheater 26 to the header 27.

.185 5, In passing through the .superheater, the steam will be raised to a high temperature and hence will besuitable for use in a steamturbine for-the Many industrial plantshowfor process work as well as 0 power generation, and the process steamis usualgeneration of power.

ship between the quantities required for the two purposes, and thesequantitiesmay vary entirely independently throughout the day.

preferably accomplished by desuperheating aportion only of the steam for process, and controlling this portion in, relation to the total quantity M 5 process steam to provide the desired result.

In the preferred construction illustrated I have provided a desuperheater comprising an inlet header 32 and an outlet header 33 connected by a group of tubes 34. Key caps 36 are provided in 110 the headers for convenience in expanding the tube ends. This desuperheater is shown mounted in the boiler drum 12, but it will be apparent that it can be mounted in any drum which contains a supply of water. The drum 12 is provided with the usual manholes 37, through which the parts of the desuperheater may be inserted to be assembled inside the drum. The manholes 3'? are of course normally closed by cover plates (not shown). The headers 32 and 33 are preferably vertical, and the tubes 34 are located in the lower part of the drum below the water level. The upper ends of the headers 32 and 33 are connected by flanged joints to welding necks 39 and 40 respectively, which are welded to the lower ends of welding necks 41 and 42 respectively. These fittings 41 and 42 are expanded and welded to the upper wall of the drum 12. The usual safety valve 44 is mounted on the drum, and connections 45 are provided for the usual water column.

A cross fitting 4'7 is mounted on the welding neck 41, and a pipe 48 leads from the superheater outlet header 27 to one lateral branch of the cross. The upper branch of the cross is connected to a pipe 49 which may lead to a steam turbine or other apparatus for using high pressure high temperature steam. The welding neck 42 at the outlet of the desuperheater 34 is connected to a delivery pipe 51 leading to apparatus requiring low pressure low temperature steam, and this pipe is pro-- vided with a valve 52. A by-pass pipe 53 leads from the cross 47 to the pipe 51 and preferably connects with said pipe at a point beyond the valve 52. The by-pass pipe is provided with a valve 55 and an expansion loop 56.

It will now be apparent that the pressure and temperature of the steam in the pipe 51 will depend upon the adjustment of the valves 52 and 55. Both of these valves are preferably of the wellknown diaphragm-operated type, one being actuated in accordance with the pressure in pipe 51 and the other in accordance with the temperature in pipe 51. In the embodiment illustrated, valve 52 is pressure actuated, being connected to pipe 51 by a small control pipe 58, and valve 55 is temperature actuated, being connected by a small tube 59 to a temperature responsive bulb 60 located in the pipe 51.

The operation of the invention will now be clear from the above disclosure. Hot gases from the furnace 18 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 27 and pipe 48 to the cross 47, and a part of this steam flows through the pipe 49 to a turbine or other apparatus. The remainder of the steam divides, a portion flowing through the desuperheater 34 and a portion through the by-pass pipe 53. The steam which passes through the desuperheater is reduced in temperature by the transfer of heat to the water in the drum 12. This heat is of course not wasted, but aids in the generation of steam. The valves 52 and 55 function automatically to maintain the desired steam conditions in the pipe 51 leading to the process steam consuming apparatus. If the pressure in pipe 51 increases, valve 52 will close slightly to reduce the steam flow and restore the desired pressure. If the temperature in pipe 51 increases, valve 55 will close slightly to reduce the flow of high temperature steam through the by-pass pipe 53 and thus restore the desired temperature. The valves 52 and 55 thus cooperate in controlling both the total steam flow to the delivery pipe and the relative rates of flow in the desuperheater and by-pass.

Since there is a substantial pressure drop through both the valves, they can be of comparatively small size, and hence are relatively inexpensive. The pressure in the drum 12 is but slightly in excess of that within the desuperheater, so that the tubes 34 and headers 32 and 33 can be of light construction. The desuperheater takes up no space in the boiler room, and can readily be disconnected from the welding necks 39 and 40 and pushed to one side in case the boiler tubes are to be cleaned. All the steam generated in the boiler passes through the superheater, so that the superheater is protected from overheating even though the turbine is shut down and all the steam is used for process work. The desired pressure and temperature for the process steam will be maintained constant irrespective of the relative quantities of steam used for power 01' process, and regardless of any variation in the temperature or pressure of the steam delivered by the superheater.

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

1. Steam generating apparatus comprising a boiler, a superheater arranged to receive steam from the boiler, a desuperheater arranged to receive steam from the superheater, a delivery pipe arranged to receive steam from the desuperheater, a valve in the delivery pipe, a by-pass pipe for the desuperheater arranged to discharge superheated steam into the delivery pipe at a point beyond the valve, a valve in the by-pass pipe, means to actuate one of said valves in accordance with the steampressure in the delivery pipe, and means to actuate the other of said valves in accordance with the steam temperature in the delivery pipe.

2. Steam generating apparatus comprising a boiler, a superheater arranged to receive steam from the boiler, a desuperheater arranged to receive steam from the superheater, a delivery pipe arranged to receive steam from the desuperheater, a valve in the delivery pipe, means to actuate said valve in accordance with the steam pressure in the delivery pipe, a by-pass pipe for the desuperheater arranged to discharge superheated steam into the delivery pipe at a point beyond the valve, a valve in the by-pass pipe, and means to actuate the last mentioned valve in accordance with the steam temperature in the delivery pipe. I

3. The method of operating a desuperheater having a by-pass comprising the steps of supplying superheated steam at a comparatively high temperature and pressure to the desuperheater and by-pass, mixing the desuperheated steam with the superheated steam flowing through the by pass, controlling the rate of flow through the desuperheater to provide a substantially constant reduced pressure in the mixture, and controlling the rate of flow through the by-pass to provide a substantially constant reduced temperature in the mixture.

MAX H. KUHNER.

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