US2655347A - Heat exchanger - Google Patents

Description

Oct. 13, 1953 P. w. BIELFELDT 2,655,347

HEAT EXCHANGER Filed 001,. 11, 1950 ATTOR EY INVENTOR. Paul w Bielfeldt Patented Oct. 13, 1953 HEAT EXCHANGER Paul W. Bielfeltlt, Harvey, Ill., lssignor to Whit.- poration, a corporation of Illinois Application October 11, 1950, Serial No. 189,657

6 Claims. 1

My invention relates generally to heat exchangers, and particularly to the type of heat exchanger adapted for the generation of clean dry steam from contaminated, relatively wet steam.

In various fields of industry, and particularly in the chemical process industries, it is frequently necessary to convert wet or contaminated steam or other vapor into clean dry steam before the heat content of the vapor can be effectively utilized. This may be accomplished by condensing the dirty steam in a heat exchanger, which transfers the heat in the vapor to a body of water, the latter being thus vaporized to yield clean steam at a somewhat lower pressure.

To accomplish this conversion economically, care must be observed in the construction of the apparatus to avoid fouling or stoppage of the heat exchange passages by foreign particles carried into the apparatus by the incoming dirty steam, as well as to avoid the discharge of unvaporized water with the steam generated in the ebullition chamber.

An important object of my invention is to provide heat exchange apparatus particularly adapted for the generation of clean dry steam from wet or dirty steam, which is highly resistant to fouling or stoppage of the heat exchange passage, which provides an improved path of circulation for the liquid being heated, which incorporates novel baffle arrangements effective in decreasing the water content of the generated steam, as well as providing for the efficient disposition of foreign particles introduced by the dirty steam, which is efficient in operation, and which may be operated for extended periods of time without maintenance.

Other objects of my invention, which refer generally to various novel combinations and subcombinations of the component parts of my apparatus, will be disclosed in the course of the following detailed description and in the appended drawing in which is shown a partially sectioned elevation of a preferred form of my apparatus.

In brief, my heat exchanger includes a tube bundle extending through tube or end plates which are sealed within an elongated upright shell, thereby defining an ebullition chamber above a condensate chamber and surmounted by a steam inlet chamber. A generally cylindrical upright bafile, open at its upper end, encompasses the open upper ends of the tubes in the steam inlet chamber. Steam or other vapor is introduced tangentially into the steam inlet chamber below the level of the top of the baiiie, thus separating by centrifugal force the foreign particles and a majority of the water droplets carried into the steam inlet chamber by the contaminated or wet steam. The tubes are surrounded by water 2 or other vaporisable liquid introduced through a suitable inlet into the ebullition chamber which condenses the steam in the tubes and is in turn heated above its boiling point.

A lower cylindrical baflle extends around the tube bundle in the ebullition chamber and is spaced both from the shell and from the end plates. Preferably, one wall of this baffle is longer than the other, the longer wall extending upwardly past the water level towards the steam outlet, which is formed in the upper portion of the ebullition chamber. An upper cylindrical baffle, also having a long wall portion and a short wall portion, extends downwardly from the upper end plate between the steam outlet and the upper extremity of the lower ballle preferably to below the water level, it being understood that the long wall portion is spaced from both the lower battle and the shell. The short wall portion of the upper bafile is disposed diametrically opposite the long wall portion and the steam outlet and is above both the water level and the lower baffle.

Thus, a majority of the water and foreign material iseliminated from the incoming dirty steam by cyclonic action in the steam inlet chamber, the relatively clean vapors passing downwardly into the tubes and transferring their heat to water or other liquid in the ebullition chamber, thereby vaporizing this liquid.

The application of heat to the liquid sets up relatively strong and well defined thermal currents, which pass upwardly within the lower bafile and downwardly between the shell and the outer wall of the baflle. Violent boiling occurs at the water surface around the tubes, and under ordinary conditions results in the entrainment of a considerable number of water particles with the vapor. The upper and lower bailies, however, act to prevent the entrainment of water particles in the steam passing to the steam outlet, since they force the vapor to travel around the upper internal surface of the shell and around the long wall portions of both baffles before reaching the steam outlet. This permits the water particles to settle, and in addition, brings the particles in contact with the walls of the equipment, which aids in a separation.

Referring to the drawing, the preferred form of my apparatus includes an elongated upright shell H) of generally cylindrical cross section having a lower portion H and an upper portion [2 connected by a throat 3. The upper portion i2 is somewhat greater in diameter than the lower portion H, and is closed by a cap Hl, while the bottom portion ii is closed by a cap l6, having a discharge opening I l and gas elimination openings l8.

A battle it is disposed within the upper portion of the shell 12 and includes lower side walls 'b'alile 3 .5.

2| secured to the shell It and extending upwardly and inwardly to an upright cylindrical wall portion 22, which defines an opening communicating with the interior of the shell it below the cap [4. A tangential steam inlet 23 is formed in the shell between the upper and lower extremities of the baffle I9. 1

An upper tube, or end plate 24, is sealed across the bafile l9 approximately at the junction of the wall portions 21! and 22 and is provided with a multiplicity of opening through which a plurality of tubes 25 are sealed. The lower ends of the tubes 2% are sealed through a lower tube or end plate 21, which is peripherally secured to the shell it! near the bottom cap 15. Thus, the plates 2% and 2? define an ebullition chamber, designated 28, a steam inlet chamber 38, and a condensate chamber (5. A water inlet 23, preferably having a solenoid valve 3|, extends through the shell it and serves to introduce water into the ebullition chamber 28. A steam outlet 32 extends through the upper portion l2 oi the shell It near the junction of the baiiie 19 with the shell.

Since it is highly desirable in operation to maintain the level of water in the ebullition chamber 23 substantially constant and prefer ably at or near the level indicated at 33, I prefer to utilize automatic control equipment, generally designated 34, which may be connected with the solenoid valve to open and close the water inlet 29, as required. The control apparatus 3 may be of any conventional construction and is not therefore herein described in detail.

A cylindrical bafile 38 is telescoped over the tubes 25 Within the ebullition chamber 28 and is supported in spaced relation to the plates 28 and 21 and to the shell by suitable means, such as arms 3'! secured to the shell Hi and to the baifie Thus, the baffle 3t and shell It define a peripheral water passage 38 around the b-afiie 36. Preferably, although not necessarily, the upper end of the bailie SS is out along a plane disposed at an acute angle to the axis, thereby forming a long side 39 and a short side 4|. The long side 39 extends upwardly past the water level 33 towards the steam outlet 32 in such manner as to intercept vapor escaping from within the baffle 36 and traveling towards the outlet 32. The upper extremity of the short side 4! is preferably located slightly below the water level 33. If the baiile 35 is constructed in the form of a right cylinder, the upper extremity should be disposed above the water level 33, and preferably slightly below the level of the steam outlet 32.

A second cylindrical bafile 42 having a long side 43 and a short side Mis secured to the baflie is or to the plate 24 and extends downwardly into the ebullition chamber 28 around the tubes 26. Preferably the diameter of the bafile 62 is somewhat greater than the diameter of the bafile s6 and is arranged in such manner that the long side 43 is disposed between the steam outlet 32 and the'upper extremity'of the bafile 36. The lower extremity of the short side 54 of the baiiie S2 is disposed well above the water level 33 and above the upper extremity of the Although not always essential, it is desirable that the long side 33 extend downwardly toIa level below the water level 33.

In operation, contaminated or wet steam is 7 introduced in my heat exchanger through the inlet 23, entering the steam inlet chamber at a relatively high velocity in a tangential direction. Centrifugal force throws the water and foreign particles outwardly against the inner walls of the chamber 30 from which they fall by gravity and may be discharged through a suitable outlet 46 extended through the shell near the level of the lower portion of the baffle IS. The vapor, now substantially freed of its foreign material and water droplets, passes over the top of the baffle I9 and into the tubes 26, which are surrounded with water. The steam is thus condensed, the condensate passing downwardly in the tubes into the condensate chamber 35, from which it may be discharged through the outlet ll. Non-condensable gas is discharged from the openings [8. Foreign particles lodging within the tubes 25 may be periodically removed by conventional methods, although it will be found that in most instances this operation is only infrequently necessary.

The latent heat of the condensing steam, as well as some of its sensible heat is transferred to the water surrounding the tubes 25 in the ebullition chamber 28, thus establishing thermal currents which cause the water to rise through the baiile 36, overflow the upper extremity of the short wall 4| into the passageway 38, and reenter the baflie below its lower extremity.

A portion of the heated water, upon reaching the water surface 33, is converted into vapor and will entrain a certain numberof water droplets. Since steam is continuously discharged through the steam outlet 32, the vapor passes to the left, through the opening defined by the lower extremity oi the short wall 44 and the upper extremity of the short Wall 4!, traveling around the inner wall of the shell I!) to the steam outlet 32. The vapor can not pass directly from the water surface 33 immediately around the tubes 26 to the outlet 32 because of the long walls'of the baflies 35 and 42, which block direct passage. Thus, the vapor travels to the outlet 32 at relatively low velocity, permitting the water particles to settle and is also continuously impinged upon theshell Ill, as well as against the baflie 36 and t2, which aids the settling out of the water droplets. As a result, steam issuing from the outlet 32 is not only clean, but is substantially free of water droplets.

Continuous circulation of the water by thermal currents within the battle 36 aids considerably in increasing the efliciency of heat transfer to the water and to some extent avoids the formation of deposits on the tubes 26. This, however, can not be completely avoided and descaling treatment will be periodically required, depending upon the hardness of the water and quantity of steam generated.

I claim:

1. A heat exchanger for generating vapor including a hollow shell, spaced end members in the shell defining an ebullition chamber, a plu 'rality of tubes extending through the end members and the ebullition chamber, a'vapor outlet for the ebullition chamber and a liquid inlet for maintaining a liquid level below said vapor outlet in said chamber, means for passing vapor into the tubes, afirst bafile around the tubes spaced from the shell and end members including a long wall portion facing the vapor outlet and terminating above the liquid level and a second baflle around the tubes supported above the first baiile, said,

second bafiie including a long wall portion dis posed in'spaced relation between the portion of theshell incorporating the vapor outletand the upper extremity of the first baflle and extending to the liquid level, and a short wall portion opposite said long wall portion being spaced axially from the first battle and having its lower extremity above said liquid level.

2. A heat exchanger for generating steam comprising a hollow upright shell, a pair of spaced generally horizontal tube plates in the shell defining an ebullition chamber, a plurality of tubes in the chamber sealed through the plates, means including an inlet in the shell for passing steam into the tubes, a steam outlet in the shell below the upper of said plates, a water inlet in the shell between the plates for maintaining a water level in the ebullition chamber below the steam outlet, a lower baiiie in the chamber around the tubes spaced from the shell and from said plates, and an upper baflie around the tubes including a long wall portion disposed in spaced relation between the upper extremity of the lower baflie and the portion of the shell incorporating the steam outlet and extending downwardly from the upper of said plates past the level of the steam outlet and a short wall portion having its lower extremity disposed above the upper extremity of the lower bailie, the portions of each of the baffies nearest the steam outlet extending past the water level.

3. A heat exchanger for generating steam comprising a hollow upright shell, a pair of spaced generally horizontal tube plates in the shell defining an ebullition chamber, a plurality of tubes in the chamber sealed through the plates, means including an inlet in the shell for passing steam into the tubes, a steam outlet in the shell below the upper of said plates, a water inlet in the shell between the plates for maintaining a water level in the ebullition chamber below the steam outlet, a lower bafiie in the chamber around the tubes spaced from the shell and from said plates, the upper extremity of said lower baffle being above said water level, and an upper baflle around the tubes including a long wall portion disposed in spaced relation between the upper extremity of the lower baflle and the portion of the shell incorporating the steam outlet and extending downwardly past the level of the steam outlet to water level and a short wall portion having its lower extremity disposed above the upper extremity of the lower bafiie.

4. A heat exchanger of the type adapted for steam generation comprising a closed shell, spaced transverse plate members in the shell defining a closed ebullition chamber having a water inlet and a steam outlet, a plurality of tubes extending through the chamber and plate members,

means for maintaining a water level in the chamber below the steam outlet, an upright generally cylindrical first bafiie in the chamber around the tubes, said first baflle being spaced from the shell and plate members and having an upper extremity projecting beyond the water level towards the steam outlet, a second generally cylindrical upright bailie around the tubes sealed to the upper of the plate members and having a long wall portion projecting downwardly to water level in spaced relation between said steam outlet and the upper extremity of said first baflie, said second baflie having a short wall portion opposite the long wall portion, the lower end of said short wall portion being above the water level and spaced axially from the upper extremity of the first baiiie.

5. A heat exchanger of the type adapted for steam generation comprising an elongated upright closed shell, transverse members in the shell defining a steam inlet chamber, a condensate chamber, and an ebullition chamber, said steam inlet chamber being above the ebullition chamber and having a tangential steam inlet and a drain, a plurality of tubes extending through the ebullition chamber and said members, a first cylindrical baiiie in the steam inlet chamber open at its upper end and encompassing the upper ends of the tubes, said first bafiie extending upwardly from the upper of said members in spaced relation to the shell to a level below the top of the shell, but above the level of the steam inlet, a Water inlet and a steam outlet for the ebullition chamber, means for maintaining a water level in the ebullition chamber below the steam outlet, a second baflle around the tubes in the ebullition chamber spaced from the shell and from the transverse members including an upper wall portion extending upwardly past the water level towards the steam outlet, and a third baffle around the tubes above the second baflie, the third baflie including a long wall portion disposed in spaced relation between the steam outlet and the upper extremity of said second baflie, and extending downwardly past the steam outlet to water level, the third battle also having a short wall portion opposite said long wall portion, the short wall portion having its lower extremity spaced axially from the upper extremity of the second battle and above said water level.

6. A heat exchanger of the type adapted for steam generation comprising an elongated upright closed shell, transverse members in the shell defining a steam inlet chamber, a condensate chamber, and an ebullition chamber, said steam inlet chamber being above the ebullition chamber and having a tangential steam inlet and a drain, a plurality of tubes extending through the ebullition chamber and said members, a first cylindrical baflie in the steam inlet chamber open at its upper end and encompassing the upper ends of the tubes, said first bafiie extending upwardly from the upper of said members in spaced relation to the shell to a level below the top of the shell, but above the level of the steam inlet, a water inlet and a steam outlet for the ebullition chamber, means for maintaining a water level in the chamber below the steam outlet, a generally cylindrical second bafile in the ebullition chamber around the tubes spaced from the shell and said members, the upper extremity of said bafile projecting beyond the water level towards the steam outlet, and a third generally cylindrical baflle sealed to the upper of said members and having a long wall portion projecting downwardly approximately to the water level in spaced relation between the steam outlet and the upper extremity of the second baflie, said third baifle also having a short wall portion opposite said long wall portion, the lower end of the short wall portion being above water level and spaced above the upper extremity of the second bafile.

PAUL W. BIELFELDT.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 828,524 Warren Aug. 14, 1906 989,982 Kestner Apr. 18, 1911 989,996 Parker Apr. 18, 1911 1,054,926 Mantius Mar. 4, 1913 1,568,413 Peebles Jan. 5, 1926 2,544,885 Jacoby et al Mar. 13, 1951

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