April 27, 1954 A. J. ROSENBERGER 2,676,575 STEAM SUPERHEAT CONTROL

7 Filed July 8, 1950

BY _

ATTORNEYS Patented Apr. 27, 1954 2,676,575

UNITED STATES PATNT OFFICE 2,676,575 STEAM SUPERHEAT CONTROL Albert J. Rosenberger, Chicago, 111., assignor to Republic Flow Meters Company, Chicago, 111., a corporation of Illinois Application July 8, 1950, Serial No. 172,700 3 Claims. (01. 122-479) 1 2 This invention relates to a steam superheat lower load conditions, a recirculating connection control and particularly to a control to maintain 13 is provided from the header [2 at the outlet a uniform superheat temperature under varying side of the superheater to the inlet side of the loads. superheater between the superheater and the In boilers equipped with superheaters, the C31 boiler drum I8. The recirculating connection l3 superheat temperature tends to be higher at high leads to an injector I4 which functions in re loads than at low loads. It has been the usual sponse to flow of steam from the boiler drum to practice to design and adjust the superheater to the superheater to induce a ?ow of steam through produce the desired superheat at approximately the recirculating connection. half load and to desuperheat at higher loads. At 10 The injector is constructed as best seen in Fig— lower loads the steam has been used at reduced ure 2 with a hollow body l5 providing an enlarged superheat. chamber it having an inlet connection at I‘! for It is one of the objects of the present invention connection to the boiler drum and an outlet 18 to provide a steam superheat control which will for connection to the superheater inlet. The in maintain a uniform superheat temperature under 15 let connection ll preferably opens into the side of varying load conditions. the chamber, and the chamber tapers toward the Another object is to provide a steam superheat outlet connection as indicated at 19. control in which steam is recirculated through the An inlet chamber 2! is provided at one end of superheater at lower loads. the chamber it and is separated therefrom by a Still another object is to provide a steam super wall 22 having a circular central opening there heat control in which the amount of steam recir through opposite to the outlet 18. An injector culation is controlled in response to a function, nozzle 23 extends slidably through this opening preferably the temperature, of the steam at the in alignment with the outlet [8 and is shiftable outlet side of the superheater. Preferably an ad axially toward and away from the opening it’. justable injector is employed to produce the re With this construction the area of the passage circulation and is adjusted in response to varia . around the nozzle 23 and within the tapered por tions in the selected steam function. tion is can be varied to vary the injector effect A further object is to provide an adjustable and the quantity of steam circulating through steam injector. the recirculating connection. The nozzle is ‘The above and other objects and advantages of 30 formed with lateral inlet openings 24 communi the invention will be more readily apparent from eating with the inlet chamber to receive steam the following description when read in connection from the bypass H3. with the accompanying drawing, in which— The nozzle is adapted to be shifted by an oper Figure 1 is a diagrammatic view of a steam ating rod 25 extending through the outer end of superheat control embodying the invention; and the inlet chamber and sealed by means of a pack Figure 2 is a sectional View through the adjust ing 26. The rod 25 is moved by a control device able injector. indicated generally at 26 which may be any de— As shown in Figure l, the invention is applied to sired type of regulator or controller capable of a steam generator or boiler having a. steam drum shifting the rod in response to a controlling force. I0. Steam from the drum ?ows through a super 40 The regulator 25 is preferably responsive to a heater H to a header 12 from which the steam function of the steam in the header I2 such, for is withdrawn for any desired use. These parts example, as the rate of flow of steam through the represent a conventional boiler construction ex header, the pressure in the header, or the tem cept that the superheater, according to the pres perature in the header. As shown, the regulator ent invention, is designed and adjusted to pro is responsive to the header steam temperature, duce the desired superheat of the steam in the and for this purpose a bulb 21 is mounted in the header 12 at some predetermined high load ap header and is connected by a tube 28 to the regu proaching maximum load, that is, when the maxi lator 26. As the temperature in the header in mum quantity of steam is ?owing from the boiler creases, the regulator will move the nozzle 23 to and the header in the normal operating range. 50 the left, as seen in Figure 2, and as the temper With the superheater so designed and adjusted, ature decreases, the regulator will move the noz the superheat temperature of the steam will be zle to the right. lower than the designed temperature at all load In operation, when the apparatus is operating conditions other than maximum load. at full load, the temperature in the header will To correct for the lower temperature at the 55 be high at the desired superheat value, and the 2,676,575 3 4 nozzle 23 will be shifted fully to the left. At this direct recirculating connection from the steam time the injector provides a minimum degree of outlet to the steam inlet, an injector connected suction on the nozzle so that there will be a mini~ to the steam inlet and the recirculating connec mum or zero return flow of steam through the tion to draw steam from the steam outlet through recirculating connection. At lower loads the the recirculating connection into the steam inlet, temperature in the header tends to drop so that adjustable means to control the quantity of steam the nozzle 23 will be shifted to the right. This ?owing through the recirculating connection, increases the injector effect causing a circulation and a control device including a sensing element of steam from the header through the recirculat responsive to the temperature of the superheated ing connection to recirculate through the super 10 steam to adjust said adjustable means to main heater. As the steam recirculates through the tain a uniform superheat temperature at said heater, its temperature will be increased and by steam outlet under varying load conditions by properly adjusting the regulator the correct increasing the quantity of steam ?owing through amount of steam can be recirculated to maintain said recirculating connection when said tempera the desired superheat temperature in the header ture decreases and decreasing said quantity when under all load conditions. said temperature increases. While one embodiment of the invention has 3. In combination, a steam generator includ been shown and described in detail herein, it will ing combustion means for steam generation, a be understood that this is illustrative only and is convection superheater connected to the genera not to be taken as a de?nition of the scope of the tor and heated by said combustion means and invention, reference being had for this purpose to designed to produce the desired superheat at a the appended claims. predetermined high load, a steam header con What is claimed is: nected to the superheater, a direct recirculating 1. In a steam generator including combustion connection from the steam header around the means for steam generation and a convection 25 superheater, and means responsive to the tem superheater heated by said combustion means perature of the steam flowing from said super and having a steam inlet connected to said gen heater to said header to maintain a uniform erator and a steam outlet and designed to pro superheat temperature at said header under duce the desired superheat at a predetermined varying load conditions by increasing the quan high load, a superheater control comprising, a 30 tity of steam flowing through said recirculating direct recirculating connection from the steam connection when said temperature decreases and outlet to the steam inlet, control means to con decreasing said quantity when said temperature trol the quantity of steam ?owing through the increases. recirculating connection, and a control device in cluding a sensing element responsive to the tem References Cited in the ?le of this patent perature of the superheated steam to regulate UNITED STATES PATENTS the control means to maintain a uniform super Number Name Date heat temperature at said steam outlet under 123,264 Korting ______Jan. 30, 1872 varying load conditions by increasing the quan 40 395,456 Sauer ______Jan. 1, 1889 tity of steam flowing through said recirculating 1,014,919 Sweeny et a1. ______Jan. 16, 1912 connection when said temperature decreases and 1,449,228 Hasegawa et a1. ____ Mar. 20, 1923 decreasing said quantity when said temperature 1,661,106 Broido ______Feb. 28, 1928 increases. 1,934,724 Lucke ______Nov. 14, 1933 2. In a steam generator including combustion 1,973,517 Armacost ______Sept. 11, 1934 means for steam generation and a convection 1,992,115 Belohlavek ______Feb. 19, 1935 superheater heated by said combustion means 2,257,805 Kolling ______Oct. '7, 1941 and having a steam inlet connected to said gen 2,594,818 Sprague et al ______Apr. 29, 1952 erator and a steam outlet and designed to pro 2,594,962 McDonald ______Apr. 29, 1952 duce the desired superheat at a predetermined high load, a superheater control comprising, a 0