US2137373A - Double pipe chiller - Google Patents

Description

Nov. 22, 1938.

DOUBLE PIPE CHILLER Filed Sept. 29, 1936 2 Sheets-Sheet 1 Jesse .D. Vl iflzlamsfi Gum/swan J. D. WILLIAMS, JR 2,137,373

i 4 WW /ls 22, 1933- .1. D. WILLIAMS. JR

DOUBLE PIPE CHILLER Filed Sept. 29, 1956 2 Sheets-Sheet 2 1.79555 17: Vl jllz'ams,

Patented Nov. 22, 1938 PATENT OFFICE v DOUBLE PIPE CHIILER Jesse D. Williams, Jr.,

Shively, Ky., asslgnor to Henry Vogt Machine Co. Inc., Louisville, Ky., a corporation of Kentucky Application September 29, 1936; Serial No. 103,181

.5 Claims.

This invention relates to heat exchanging apparatus and. particularly to double pipe chillers either of the brine or direct expansion type. As conventionally constructed, such chillers com- 5 prise inner and outer pipes assembled in vertical relationship flow through the inner pipes and the annular space between inner and outer pipes, the

flow through the inner pipes being assisted by rotary devices such as conveyors or scrapers and whichare designed also to keep the surfaces of the inner conduits free from deposits.

The general object of the invention is to improve the construction and efliciency of operation of such apparatus as well as to facilitate the disassemblage of the same for the purpose of cleaning or repair. I

One of the specific objects of the invention is the provision of packing for the conveyor or scraper shafts at the points where they pass through the return bends designed to prevent loss of fluid through leakage, either by returning the escaped fluid by a common manifold back to the process,. or by enabling external-pressure in excess of the internal pressure to be applied to the packing to prevent leakage.

Another object of the invention is the provision in apparatus of the type described of driving means for the conveyors or scrapers located adjacent the return bends at one end of the chiller with couplings between said drive means and the conveyor or scraper shafts of that type which permits the disconnection of any single conveyor or scraper from the driving system without disturbing the other conveyors or scrapers of the chiller. Still another object of the invention is the provision of a scraper or conveyor made in sections and in axial alignment when installed within the chiller, said sections being both coupled and journalled in roller bearing spiders positioned within said conduits.

Still another object of the invention is the provision of spring-type scrapers which continually engage the walls of the inner tubes and keep them polished and free from sedimentary accumulations.

A further object of the invention is the arrangement of the chiller pipes whereby the warm entering liquid in the inner pipe and the cold exiting liquid in the annular space between the pipes flow downward between one tier or stand of coil and upward through the other stand.

The invention also contemplates the aforementioned improvements and those which shall be. disclosed in the course of the disclosure applied to the chiller of the direct expansion type in which liquid refrigerant is admitted at one end to the outer conduit and the gasified refrigerant drawn off at the opposite portion of the conduit.

Other objects of the invention will appear as ,the following-description of a preferred and practical embodiment thereof proceeds.

In the drawings throughout the several figures of which the same characters of reference have been employed to denote identical parts:

Figure 1 is a side elevation of double pipe chiller apparatus embodying the principles of the present invention;

Figure 2 is a top plan view of the upper left hand end of the chiller shown in Figure 1;

Figure 3 is a longitudinal section through two adjacent transverse sections of the chiller;

Figure 4 is a section taken on an enlarged scale of the bearing at the left hand end of Figure 3; t

Figure 5 is a section taken along the line 5--5 of Figure 3;

Figure 6 is a section taken along the line B6 of Figure 3;

Figure 7 is a transverse section taken along the line of Figure 3;

Figure 8 is a modification in which a ribbon conveyor is substituted for the spring-type scraper;

Figure 9 is 'a longitudinal elevation showing a scraper of the twisted or lawn mower type; and

Figure 10 is a modification showing in section a construction in which one end of the shaft of the scraper or conveyor does not come-through the return bend and therefore requires no pack- Referring now in detail to the several figures, the numeral I, Figure 1, designates in general a double pipe chiller of the direct expansion type. As shown, it-consists' of a coil built up in the form of two stands or tiers of which one only is shown, the other being directly behind it. Each tier consists of a plurality of superposed transverse sections 2, each consisting of an inner pipe 3, see Figure 3, and an outer pipe or jacket l. With the exception of the extreme ends of the coil, the ends of the inner pipes 3 are serially connected by return bends 5. As shown, the return bends alternatelyconnect the adjacent ends of the inner pipes of the same horizontal bank and the ends of the inner pipes of adjacent transverse sections enter'a tier so that the direction of circulation of liquid through the inner pipes in transversely through a section of one tier, across to the adjacent tier, back through the transverse section of said tier and vertically into the adjacent section of said tier. Thus the flow is serially through the entire coil, but alternating from one tier to the other.

It is immaterial to the invention as to whether fluid enters at the top or bottom of the coil. In the present illustrated embodiment, the coil is designed for chilling a viscous fluid such as diluted wax distillate, the chilling system being of the direct expansion type so that it is desirable to have the fluid to be chilled enter at the inlet 6 at the bottom and discharge by way of the outlet 1 at the top.

Since the invention is equally applicable to brine chillers as wellas those of the direct expansion type the details inherent in the direct expansion type of mechanism which will now be described are unessential to the invention. There is afloat chamber 3 for the liquid refrigerant such as ammonia and a valve controlled feed pipe 9 which discharges into the top of the outer pipe or Jacket 4 at the point Ill.

The liquid refrigerant fills the outer pipe of the upper section to the point from which the overflow pipe il debouches and then successively fills the outer pipes of the sections below, up to the overflow point, the overflows being on alternate sides of the stand or tier of sections. The liquid to be chilled is pumped through the pipes by a suitable pump, not shown. Ebullition takes place in the outer pipes, the gaseous refrigerant collecting adjacent-the upper walls of said outer pipes and passing into individual gas headers l2 from which the gaseous refrigerant discharges by way of the inclined conduits ilinto a stand pipe I which goes to an accumulator ii. The accumulator is so constructed that any liquid entrained with the gasified refrigerant drains back by way of a pipeii into the system. The accumulator is connected on to the suction side of a suitable compressor or other known means for re-liquefying the refrigerant.

In a brine flow system, the gas headers and accumulator would be omitted and the chilling liquid would flow serially through the outer pipes or jackets.

It is conventional in double pipe chillers to provide means in the inner pipes of the transverse sections for accelerating the flow of the chilled fluid which may have considerable viscosity, or to clear the walls of the inner pipes of sedimentary accretions. Figures 1 and 3 show that the return bends 5 and I! at the ends of the transverse sections are provided with stufling glands constituted by hollow extensions I3 and I! through which the ends of the shaft 20 of the impeller or scraping device extend. Units 2i of compression packing are positioned within the bores of the extensions II and i9 and around the ends of the shaft. One of the improvements of the present invention is the interposition between the units 2i of packing of lantern glands 22 and 23. These glands consist of spaced annular headers 24 and 25 connected by an annular web 26. An annular space 21 is formed within the lantern gland between the web 28 and the shaft, which space communicates with an outer annular space 28 between said web and the inner wall of the extensions II and I! by means of perforations 23 formed in the web. It is thus evident that oil or other fluid from the inner pipes 3 which may leak along the shaft 20 or along the inner wall of the extensions it or II will be trapped in the annular space 21 or 28. This leaking fluid is drawn off by a system of tubes 30 and 3! and carried back to the supply of liquid to be chilled. The system of tubes comprises horizontal branches communicating with lantern glands of the transverse sections of the two tiers which lie at substantially the same level and these are connected by the vertical tubes 3i which pro ceed to the source of supply.

Alternatively, fluid pressure from an outside source may be applied through the tubes 30 and 3| to the lantern glands, said fluid pressure being greater than the internal pressure within the inner pipesso as to continually force the fluid back and prevent its leaking past the packing.

Figure 3 shows that the shaft 20 operates a scraper in general designated by the reference character 32 and which consists of a plurality of realtively narrow metallic ribbons or blades 33 which in this form of the invention are parallel to the axis of rotation of the shaft 20. The manner of mounting of these blades and their mode of operation can be gathered from a consideration of.

Figure 7 in which it will be observed that the blades 33 resiliently engage the inner wall of the inner pipe 3. They are secured to spring arms M which in turn are fastened to rigid lugs bolted or otherwise made fast to the shaft 20. The edges of the blades are preferably bevelled so as to obtain a knife edge and their function is to scrape away the positive matter from the inner walls of the inner pipes. It will be understood from Figure 3 that the spring arms 34 and lug 35 are narrow and secured at spaced intervals to the shaft 20.

A variant of the ribbon type scraper is illustrated in Figure 9, the constrwtion of which is substantially like that in Figure 3 excepting that the blades 36 are given a twist and secured so as to retain this twisted position. Since the twisted blade scrapes at an angle, it is more efficient than the parallel type of blade.

Figure 8 shows a still further modified form of scraper or conveyor which differs from the con- .ventional helicoid conveyor in being a narrow ribboh 3'I contacting the inner surface of the pipes 3, but spaced from the shaft by means of radial struts 38.

The invention contemplates sectionally mounting these conveyors or scrapers regardless of the type employed and Figure 8 indicates the nature of the mounting. The shaft 20 of each section is hollow and between the sections are spiders 39, the outer ends of which may be frictionally fixed with respect to the inner wall of the inner pipes 3.

Said spider has a hub 40 and within the hub is fixed a roller bearing 4|. A short shaft 42 passes through this roller bearing extending on both sides of the spider. The diameter of the short shaft 42 is such that it just fits within the ends of the hollow shafts 20 of adjacent sections. Said sections are butted up close to the spider. Pins 43 are then inserted in aligned holes in the hollow shaft and in the shaft 42 and the assemblage of the conveyor sections is complete. At one end of the transverse section, for example, on the right hand end as illustrated in Figure 3, an end thrust bearing 44 is provided against which the conveyor or. scraper reacts.

Figure 1 shows that the shafts of the impellers or scrapers of the several transverse sections of the tiers of the coil extend in parallel relation to the right, and have aflixed thereto driving means such as the sprocket wheels 45. These sprocket wheels lie in the same plane and are engaged by a sprocket chain 46 which encompasses a sprocket 41 on the end of a motor shaft 48, the motor being thus the driving instrumentality for all of the impeller or scraper shafts.

7 It of course sometimes happens that a scraper will become broken or jammed and require to be removed for replacement or repair. The present invention provides that any scraper or plurality of scrapers may be disconnected from the driving train for removal without interfering with the operation of those not so disconnected. This provision is carried out by dividing the shafts 20 in the space between the stuffing glands 49 and the sprocket wheels 45. This is shown in Figure 3, the divided shafts being united by a compression coupling 5| separable transversely so that when unbolted it may be lifted from the divided shafts severing the connection between the driving train and the affected scraper.

Figure 10 shows a slightly modified form of the invention in which one end of the impeller or scraper shaft 20 terminates short of the adjacent return bend so that no packing expedient is necessitated at this end, one of the spiders 39 being located at the end of the transverse section and having a shaft extending into and secured to the adjacent end of the shaft 20. The slight difference in the diameters of the spider shaft and shaft 20 provides a shoulder to prevent endwise movement of the impeller or scraper shaft toward the left, that is to say, in the direction of the adjacent return bend.

It will be obvious to those skilled in the art that the improvements and refinements upon the conventional type of double pipe chiller as disclosed in the specification and defined in the appended claims are subject to variation as regards details of construction and arrangement of parts, wherefore, it is to be understood that the specific structure as shown is merely by way of example and not to be construed as restricting the scope of the appended claims.

What I claim is:

1. In a chiller, a coil for the fluid to be chilled comprising superposed straight pipe sections, return bends at the ends of said sections connecting them serially, shafts passing through said sections and through the return bends at least at one end of said chiller, rotary devices on said shafts,.stufling glands surrounding said shafts carried by the return bends through which said shafts extend, compression packing within said stufiing glands, cells interposed in said compression packing, open to the joints between said compression packing, shaft and gland, a conduit having branches communicating with said cells, said conduit leading to the supply source of the fluid circulating within said coil for carrying the leakage through said packing back to the system.

2. In a chiller, a coil including superposed straight pipe sections, return bends at the ends of said sections connecting them serially, shafts passing through said sections and through the return bends at least at one end of said chiller, rotary devices on said shafts, stuffing glands surrounding said shafts carried by the return bends through which said shafts extend, compression packing within said stuffing glands, cells interposed in said compression packing open to the joints between said compression packing and shaft and gland, a conduit having branches communicating with said cells, said conduit communicating with a source of pressure superior to that within said coil for preventing leakage through said packing.

3. In a chiller, a coil comprising superposed straight pipe sections, return bends at the ends of said pipe sections connecting them serially, shafts passing through said pipe sections and through the return bends at least at one end of said chiller, rotary scrapers on said shafts engageable with the walls of said pipe sections, stuffing glands surrounding said shafts, carried by those return bends through which said shafts extend, compression packing within said stufiing glands, cells interposed in said compression pack ing open to the joints between said compression packing, shafts and glands, a conduit having branches communicating with said cell, said conduit functioning to prevent wastage by leakage through said compression packing, outer pipe sections surrounding said straight pipe sections, means connecting said outer pipe sections serially at their ends, and means for supplying a heat exchanging medium to said outer pipe sections.

4. In a double pipe chiller, a coil including adjacent tiers of superposed straight pipe sections, transverse return bends at one end of said coil connecting horizontally adjacent pipe sections, vertical return bends. at the opposite end of said coil connecting the pipe sections in serial relation, shafts extending axially through said pipe sections and through the return bends at least at one end of said coil, scrapers on said shafts contacting the walls of said pipe sections, stufling glands surrounding said shafts carried by the return bends through which said shafts extend, compressing packing within said stufling glands, cells interposed in said compression packing, open to the joints between said compression packing, shaft and gland, a conduit having branches communicating with said cells, said conduit functioning to prevent wastage by leakage through said compression packing, driving elements at one end of said coil individual to said shafts and in axial alignment therewith, a motor for driving said elements, couplings connecting said driving elements and shafts, said shafts and scrapers being sectional, bearing-supporting spiders slidably positioned within said pipe sections between the sections of said shafts and scrapers and at the extreme ends thereof, stub shafts carried by said bearings secured within bores in the adjacent ends of said shaft sections, the

return bends at the end of said coil opposite said 7 JESSE D. WILLIAMS, JR.

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