US1428198A - Steam circulating and regenerating system - Google Patents

Description

I. 0. woons'oNIE AND I. II. SWAN.

STEAM CIRCULATING AND REGENERATING SYSTEM. APPLICATION FILED JUNE 27. 192|.

Patented Sept. 5, 1922.

2 SHEETS-SHEET l.

YSTEM.

STEA

APPLICATION FILED JUNEZ?. |921.

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v Wfl@ JOHN o. wooDsoME, oF-sYaAcs'E, NEW YORK,

AND JOHN H'. SWAN, oF cHIoAGo,

LILLINOIS.

STEAM CIRCULATING AND.

Application fil-ed .Tune 27,

To all fwwm t may concern:

WooDsoME Beit known that we, JOHN O1.

\ and JOHN H. SWAN, citizens of the United States of America, and residents of Syracuse, county of Onondaga, State of New` York, and Chicago, county of C'ook, State of Illinois, respectively, have invented a new and useful Improvement in Steam Circulating and Regenerating Systems, of which the following is a specification.

This invention relates to .a means for circulating steam through, for example, a series of heating or dryingunits, and consists in causing the steam to successively pass throughl said units by the use of ejectors operated by steam or other fluid at sufficiently high pressure to remove water and air and circulate steam, and to change the used steamand condensate-'into a dry or saturated steam `suitable for continued use throughout the series of units.' 4

The invention also relates to multiple steam operated apparatus or steam controlled devices wherein it is desired, irrespective of work performed, to maintain the steam at different temperatures or pressures in its passage in series through said devices. The particular means employed `for accomplishing 'this purpose consists in the use of a plurality of pressure regulators between the operated units, whereby, as the used steam from one unit passes to the next, it leaves a region of higher pressure and enters one of a lower pressure and therefore whatever condensate remains is'partly or largely converted into steam at the desired temperature.

Another purpose of the invention is 'to combine such arrangement of differential regulators with suitably located ejectors for removing air and condensate from thedrying units or operated apparatusv and converting part of this. condensate into steam by forcing the required circulation.

The invention has a number of applications in the arts, but its objects may be accomplished by the system as illustrated in the accompanying drawings, and designed for the requirements of paper making machines. I

Figures lA and lB show in diagram ythe piping arrangement, controlling devices, valves, and other fittings arranged 1nfa su1tl able manner for applying theinvention tol a paper making machine.

Fig. 2 is a detail for more clearly showing machine toward the dry end.

lBy the use of the present apparatus the i -tribution of moisture.

REGEN ERATIN G SYSTEM.

1-921. Serial No. 480,621.

a pressure regulator at the inlet end of a supply conduit for the ejectors.

Fig. 3 is a sectional detail taken on line 3 3 of Fig. lA and illustrating the supply and return fittings for an individual drying roll at they point of communication with the main supply header.

. 1g. lis a sectional detail of one of the ejectorslwhich is employed in the system for Inalntainingthe deslred circulation and effecting the regeneration of used steam or condensate to steam at the desired temperature.

l Fig. 5 is a detail illustrating the construction of one of the auxiliary regulators for.

controlling the supply valves and differential valves.

Fig. 6 is a sectional detail illustrating the construction of a piston operated differential valve. v

In the paper making art one of the most diflicult and important operations is to properly control the temperature and rate of drying of the paper web driers. The wet end of the machine, orwhat is sometimes referred to as the Ycondensing section, should deliver considerable heat to the paper, but at a low temperature in order not to sear the paper asA it would then trap moisture, resulting in uneven drying and requiring excess heat to remove such moisture. The driers further along in c,the machine should be successively at higher temperatures except that in some casesthere is again a slight drop in temperature in the last` section. It is essential for good results that an even and low temperature bemaintained on the face ofthe driers, andffor this promptly. Water in the drying rolls also causes them to be strained by unequal expansion, and the paper does not shrink and dry uniformly atthe desired rate. The tem- A perature and rate of drying should belincreased gradually from the wet end of-the paper may -be run through the `machine fasterv than is generally possible, Yand its quality is improved due to fixed graduation of temperature and the proper proportional delivery` of' heat, and a better lnish is imparted to the paper due to more even dis- With respect to coloredpapers, mottling-is absent andtI colors as it passes over the v-reason all condensate should be removed 'K chine. return header. This trap is,

` mon to all of are not bleached or faded due to too high tenlperautures. The beater-man may, therefore, follow given formulas and not compensate for peculiarities of operation of any one drying machine.

The differential valves which are employ'ed in the present system for maintaining the steam dry by insuring a drop in pressure of the steam as it passes through the rolls are disclosed in the application for Patent of John H. Swan, filed January 15, 1917, Serial No. 142,466. n

A method now commonly used and probably one of the oldest for handling the condensate in a paper drying machine consists in the use of a common supply header having separate connections for delivering steam to each of the ldrying rolls. Each of these rolls also hasa connection to a common return header, resulting in substantially one steam pressure throughout the ma- A steam trap isv connected with the therefore, comthe driers in handling the cona method does not provide but simply the densate. ISuch for graduated temperatures,

' handling of the condensate without waste of steam. `'Due toy all the driers carrying the same steam pressure and for the reason that the driers at the wet end do approximately ninety per cent (90%) more work than the driers at the dry end, the pressure in the driers at the wet end drops somewhat below the pressure in the machine supply header. YAs the driers at the dry end do little work, the lsteam pressure in these driers is not lowered, and consequently steam blows through the same vinto the drain header and tends to build pressure in this header nearly equal to the pressure in the supply header. the wet end to lose pressure and to become filled with condensate. Some forty per cent (40%) of the driers of the machine are so affected. To overcome this undesirable condition, a system of individual traps for each drier return came into use. Tt was thought that'by putting an individual trap on each drier return steam would be prevented from blowing through the driers into the drain header thereby allowing the `condensate to be removed from each drier. Tn practice, however, it was found necessary to add a vacuum rump to lower the pressure in the return eader and to drill a small hole lirough traps to permit the desired action of the vacuum pump on the return header to help bring the condensate up the siphon pipe in each drier or to overcome the head in bringing the condensate in to the center or journal through which the Siphon pipes pass. This individual trap system is much in use, but is still unsatisfactory for not properly emptying the driers of condensate. Accordingly, paper machine This causes the driers at f the bottom of the driery builders have attempted to empty the driers by placing buckets just inside the shell forming the same, but were not successful due to the fact that after the drier obtains a peripheral speed greater than five hundred feet per minute the condensate in the drier is thrown by centrifugal force outwardly, where it forms a film or fiat sheet revolving with the cylinder.

ReferringI to the drawings, Figure 1^ and 1B, the paper web passes over the c-ustomary arrangement l 1, from the wet end 2 of the machine to the dry end 3. Steam enters thev system through a main controlling valve 4 for regulating'the pressure ofthe steam delivered to the machine. This valve is controlled by an auxiliary 5 installed as illustrated in Fig. 1A. The supply header 6 for the machine is divided into a plurality of sections, for example, 7, 8, 9, by differential pressure regulators 10 and 11. The steam enters the header 6 at the section 7. i The pressures in the sections 8 and 9 are respectively controlled by the differential regulators 10 and 11. Sections Tand 8 of the header are connected to a plurality of driers by the conof cylinders or driers f duits 12 and 13, individual to' each drier.

Corresponding connections to driers from section 9 are indicated by numbers 14 and 15. The steam in leaving the header to a drier passes successively through the fittings 16, 17, 18 and the conduit 12, and a hollow trunnion of the drier. One of the bearings for thev drier as usual surrounds this trunnion. The Siphon pipe 13 for removing condensate from the drier vpasses through the same hollow trunnion and then downwardly into an ejector 20 by means of which used steam and condensate is forced through the conduit 24 passing centrally through sleeve 16 back into the supply header.

Steam at highr pressure, or superheated steam or water for the ejectors is supplied through the header 25, the pressure of this steam being controlled by piston valve 26 which is controlled by the automatic regulator 5. The header 25 has an individual connection 27 with each ejector 20. The construction of the ejectors 20 is shown in Fig. 4. The used steam and condensate from ea drier enter the ejector'through a screwed connection 28. -The live steam for operating the ejector enters at the top passing through the nozzle 30 and then downwardly through the venturi 31 tothe header 6. The used steam from a drier is dra-wn into the venturi 31 through the gap 32, but the ejector is a two-stage arrangement since apertures 33 are provided in the venturi. The condensate is drawn into these apertures and therefore does not interfere with circulation as effected by the ejector as would be the case if water clogged the same at the gap 32. The live or superheated steam or water or whatever fiuid is employed for the main header.

the section of lower pressure in the main. h

i l structed as illustrated in Fig. 6.

l turn control trol temperatures in the operating the ejectors is of sufiicient temperature to insure the regeneration of steam from the condensate removed from theA driers. y

The differential regulators 10 and 11 conpaper machine by insuring successive drops in steaml pressure but function similarly to the ejectors in respect to causing condensate Vto flash back into steam when the steam from one section of the header passes through a differential regulator into a section where a lower pressure is maintained.

Fig. lB illustrates the connections for the last two driers through which the steam passes. These are located at section 9 of the main supplyheader. The return for the last driers passes direct to conduit 34 leading to a vacuum pump which serves to draw out air and water, but the pressure in the driers of this section, whether above or mosphere, is controlled by differential valve 11. The section 9 of the header is also connected to the lvacuum pump through the steam trap 36.

The different sections of the main header 6 may be separated'by differential valves as illustrated .in Fig. 6.

The main header is provided with a drip by- pass 40, 41 around each section for use in carrying air or condensate when steam is first turned-into the machine. `Alfter the paper is on the machine and complete circulation is established, condensate largely disappears and these by-passes are handling a minimum amount of condensate.

' Steam traps 42 as shown in Figs. 1A and 1B are in Aby-passes around the differential valves and between the different sections of Eachv trap 42 receives water from the lower end of one of the differential valve bodies, and releases water to walter attains a certain n height in the trap. The communication between the trap and the section ofhigher pressure is afforded by conduit 4() and with the section of lower pressure by conduit 43.

Differential valves.

The differential valves 10 and 11 are con- These valves may be piston or diaphragm operated, theI opposite sides of the pistons or diaphragms beingl respectively under the influences of the pressures in the sections of the main header to the right and left of the valve, or as illustrated in the drawings, these different pressures infiuence the operation of auxiliary regulators 44 and 45 which in the action of the pistons 46`in the differential regulators. The pistons are fast to valve stems 47, y 48, and are depressible to open the valves eader when the` resistance.

below at-A which carry the valves,

against the action of an adjustable spring The auxiliary regulators 5, 44" and 45 each have a diaphragm chamber which is divided by diaphragm 49, Fig. 5. This detail which may illustrate the regulator 44 shows a conduit 5() communicating with the diaphragm chamber below diaphragm 49, and another` conduit 51 communicating with the chamber above the diaphragm. The conduit 50 as shown in Fi 1A communicates with the section 7 of t` e main header 6, whereas the conduit 51 communicates with the section 8, through the connecting pipe 52, Figures 1A and 1B. The diaphragm in regulator 44' is therefore subject to the opposed pressures` in sections.- 7 and 8. The diaphragm is fast to the valve stem 53 for controllinga valve 54. Water, at for example fifteen pounds pressure, is vsupplied through the pipe 55, Fig. 1A, and may waste out of the pipes 56, passing through valves 54 of the auxiliary regulators. If one of these valves is moved toward its closed position by an increase in pressure below the diaphragm 46 and a decrease in pressure above the diaphragm beyond a predetermined minimum as determined by an adjustment of the weights 57 on auxiliary regulators, the waste at the usual rate, and accordingly builds up a pressure in the pipe 58, and as this pipe communicates with the piston cylinder at a point above the piston 46, Fig. 6, the valves 48 are shifted more or less toward open position, and allow t-he flow `of steam water cannot constantly maintain the desired differences in pressure between the sections 7 and 8. The pressure regulator 45 is similarly connected and controls the differential valve 11, the diaphragm in this regulator being subject on its lower surface to the pressure in section 8, due to the communication provided by conduit'52. The upper side of the diaphragm'is influenced by the pressure in section 9 through the conduit 59.

he auxiliary regulator 5 controls the operation of piston operated main control valve 60 and the ejector supply valve 26. The operation of these valves is dependent upon the pressure in section 7A of the main supply headerv. Weights on this regulator are adjusted to urge its valve 54 toward closed position and thus allow a water pressure to be builtup above the pistons in valves 60 and 26', and opening'these valves, ting steam to flow through the system as' regulated by some predetermined maximum pressure in section 7. When this predetei-mined pressure is reached, the valve 54 is lagain opened by the pressure above the the communture tending to spring in the main admission steam valve 60 is of' different strength than the spring in valve 26 to insure the closing of valve 60 in advance of the closing of valve 26. A minimum pressure in the supply header 25 for the ejectors is provided .by the bypass Gl encircling valve 26, and which is provided with a dash-pot reducing valve 62 of usual construction illustrated i'n Fig. 2.

A novel feature of the present invention is the employment of a steam header common to the different drying rolls'or steam using apparatus, which header not only delivers steam to the drying rolls, but receives the used steam from the rolls. Certain features employed inthe present system are useful in paper drying machines of the old type where a separate return header is used rather than to return the steam to a common header as in the present case, for instance, the ejectors may be employed in many types of paper making machines to advantage in forcing the required circulation through different driers, and the differential regulators would also greatly improve old types of paper making machines by insuring the exact drops in pressuresrequired throughout the series of dryingrolls.

In the operation of the steain circulating system as shown in the drawings, a chief characteristic is that the `steam is maintained practically dry or possibly superheated irrespective of the work which it performs in delivering heat to the separate driers. Any desired graduation in temperatures between the rolls or driers of the paper machine may be attained according to the number of differential valves employed. Steam isfed to the section 7, which section carries the highest pressure in the arrangement shown in the drawings. ln some installations it is desirable to reduce the pressure in the first section, in which case steam is fed to an intermediate section with a drop in p-ressure in the adjacent. sections on each side. Differential valve 10 insures the desired drop in 'pressure in section 8, and differential valve 11 in ,section 9.

Circulation "of steam through each drier is effected and maintained at the -desired uniform rate by the ejectors 20. Dry steam is fed to eachy drier, and the moist steam 'is taken away, condensate in the form of solid water being Wholly or largely absent. Moisture is 11e-evaporated by the superheated steam jets Ain the ejectors so that dry steam with an excess of temperature is fed back into the supply header, the excess temperadry out any moisture within the steam header.'

'llhe diderential valves not only regulate temperature differences between sections, but if necessary insure partial regeneration of steam in the sections of the supply header, the steam passing through these increased velocity and into an area of valves at less pressure, thus permitting the steam to takel u moisture. rlhe pressures between .the different sections of the machine may be with certain classes of paper in the following ratio: The` dry end section at zero pressure, the next or main section at five pounds pressure, other intermediate sections, respectively at eight inches and fifteen inches of vacuum, and at the pumpsection twenty inches of vacuuml The steam supplied to the ejectors may be at one hundred pounds pressure. With heavy products such as paper board, the dry end section ofthe machine carries a pressure of vfrom fifteen to twenty pounds higher than the pressure carried on the main section, but with some other classes of paper it is necessary that the dry end section 11 carry a pressure reduced from that of the main section. The differential valves provide a most nicel graduating the temperatures between the different driers. The driers in section 7 are piped direct to a vacuum pump, the vacuum pump for this section taking the place of the ejectors.

Although but one specific embodiment of this invention has been herein shown and described, it will be understood that nu'- merous details of the construction shown may be altered or omitted without departing from the'spirit of this invention as defined by the following claims.

le claim:

1. In a paper making machine, nation of a series of drying rolls, of means for .supplying steam to said rolls, and differential pressure regulators for regulating the pressures of the steam in the different drying rolls, whereby predetermined pressure relations between the different rolls may be maintained, and a uniform rise or fall in pressure throughout the entire system is made possible.

2. In a paper making machine, a plurality of drying rolls, means for feeding steam to said rolls, and fluid operated ejectors for determining the rate through the different rolls.

3. ln a paper making machine, a plurality lof drying rolls, means for feeding steam to said rolls, fluid operated ejectors fordetermining the rate of* flow of steam through the different rolls, and pressure regulators for controlling the pressures in the combidrying rolls.

4c. A paper making machine comprising a plurality of drying rolls, means forV supplying steam to the different rolls, and differential regulators for controlling relatively the pressures in the different drying rolls. 2

Signed at Syracuse this 10th day of J une f JOHN O. WOODSOME.

JUHN H. SWAN.

the differentr perfect means for of flow of lsteam i

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