US2310234A - Gas condenser - Google Patents

Description

Feb. 9, 1943. .I. s. HAUG GAS CONDENSER Filed Sept. 27, 1939 2 Sheets-Sheet l .1. S. HAUG GAS CONDENSER Feb. 9, 1943.

Filed Sept. 27, 1939 2 Sheets-Sheet 2 Patented Feb. 9, 1943 GAS CONDENSER John S. Haug, Philadelphia, Pa... assignor to' United Engineers & Constructors, Inc a corporation of Delaware Application September 27, 1939, Serial No. 296,724

6 Claims.

This invention pertains generally to a gas condenser in which one of the fluids flowing therethrough is a liquid.

The invention pertains particularly to a gas condenser of the indirect heat-exchange type provided with at least one series of passages forming a downpass tor a liquid cooling medium.

The invention pertains more particularlyto a gas condenser or surface cooler of the tubular type wherein a liquid cooling medium (usually water) flows downwardly through a series of vertical or inclined tubes or passages at least once during its flow through the condenser.

In a typical arrangement it is conventional practice to provide a series of tubes or passages within which flows the cooling medium. The gas to be cooled and/or condensed flows into the spaces surrounding the passages provided for the coolant and, by heat exchange to the coolant through the walls of the tubes or passages, the gas is cooled while the liquid cooling medium is being heated.

It has been found, however, and particularly in condensers having more than a singleseries' of tubes or passages (i. e. in multi-pass condensers in which the liquid cooling medium normally flows upwardly through some of the tubes and downwardly in other of the tubes), that efliciencies considerably less than expected were had due to thermal recirculation of the liquid cooling medium in some of the tubes or passages in the downpass portion of the condenser.

Such thermal recirculation results from the fact that the liquid cooling medium (which may hereinafter be called water for simplicity), is heated as it cools the incoming hot gases by indirect heat exchange. Although the Water'is heated as it flows downwardly through the downpass portion of the condenser, yet its natural tendency is to rise due to the decrease in itsv specific gravity, as is the case with any liquid which expands and becomes lighter when heated.

In any given tube or passage in a downpass section of the condenser, if this tendency of the heated water therein to rise (which I may term the "thermal recirculation head and which is a function of the difference in weight between a tube length of hot water and a tube length of cold water) exceeds the normal tendency of the water to flow downwardly through the tube (which may be considered roughly as the normal pressure loss in the tube due to flow) then backflow of water will occur in that particular tube. The overall effect is to provide a closed circuit for water within the downpass portion of the condenser, thus correspondingly diminishing its useful capacity for cooling since the tubes in which the water is flowing in the wrong direction become hot and cease to cool the gasto a large extent. In other words, the effective cooling surface of the condenser is reduced.

It will, of course, be understood that the hot water which thus recirculates upwardly from the bottom hot water box to the top water box containing cooler water mixes therewith and returns to the bottom hot water box through other of the tubes, thus further diminishing the cooling capacity of the latter tubes.

It is an object of my invention to overcome this deflect in gas condensers or coolers generally.

It is a further object to provide apparatus for substantially eliminating the said defect of thermal recirculation in a manner which shall be simple and inexpensive to apply to any gas condenser generally, whether new or already installed.

I have found that one apparatus arrangement for overcoming the defect comprises means for positively distributing or metering the flow of water into each tube of the liquid downpass section or sections so that the head which promotes downward flow is increased enough to exceed the thermal recirculation head (chimney efiect) and thus overcome its tendency to cause the water to flow in a reverse direction.

(line such means for thus distributing the flow among the tubes of the liquid downpass portion of the condenser comprises ferrules or elements constituting flow controlling means associated with such said tubes which serve to at least momentarily increase the velocity of flow within the tubes.

Another means comprises tube extensionsifor such tubes which shall project to some extent above the upper tube sheet and into the upper water box space of the condenser. These tube extensions may be provided with V-notches or,

the like, if desired, but in any event they act as weirs to control the flow of water into the tubes with which they are associated. With such a construction the condenser is preferably of the open top type, i. e., the upper water box is open to the atmosphere.

My invention may be further described in connection with the accompanying drawing illustrating several embodiments of my invention as applied to gas condensers or coolers.- Other means will be readily apparent to those skilled in the art upon becoming 'familiar with the description herein.

In the drawings, Figure 1 represents more or less diagrammatically a multi-pass gas condenser equipped with one form of anti-recirculators according to my invention- Figure 2 is an enlarged sectional view through one anti-recirculator of the type shown in Figure 1, showing its assembly into the tube.

Figures 3 to 5 are further modifications oi. my anti-recirculating devices. v

Figures 6 and 7 show two forms of tube extensions adapted to act as weirs for the discharge of water into the associated tube.

Figure 8 shows a single pass condenser with an open top water box in which the tubes extend above the upper tube sheet and are notched to form weirs oi the type shown in Figure 6.

Figure 9 shows a three pass condenser with an open top water box in which the tubes in the liquid downpass section extend above the upper tube sheet and have unbroken edges to form weirs of the type shown in Figure 7.

Figure 10 shows a modification wherein the condenser tube itself is extended above the tube sheet, the extended portion functioning similarly to the tube extensions shown in either of Figures 6 and 7.

In Figure 1, the gas condenser is indicated generally at I and is divided into a liquid up-pass section A and a liquid downpass section B by the partition 2. Th partition extends from the bottom 5 of thegas condenser, through the lower tube sheet 4 and nearly to the upper tube sheet 3, thereby providing a space or opening 1 to permit flow of gas to be cooled between the two sections A and B.

The upper tube sheet 3 (and the top 6 if the condenser is not of the open top type) together with the shell of the condenser define the top water box 8 while the bottom tube sheet 4 and the bottom 5 of the condenser together with the shell of the condenser define the bottom water boxes which are two in number in the particular instance shown because of the partition 2. Thus, the bottom cold water box 9 is situated adiacent the cold water inlet I I while the bottom hot water box III is similarly situated adjacent the hot water outlet Hi.

The cold water (or other liquid cooling medium) is admitted at H and discharged at l2 and is finally withdrawn from the condenser through the overflow water leg H.

In the condenser, the water flows up through a series of tubes or passages l3 in the up-pass section A and down through a series 01' tubes or passages l4 in the downpass section B.

The ends of the tubes are inserted into the respective tube sheets in a manner well known in the art. Thus, they may be held in both tube sheets by means of ferrules and packing (to permit contraction and expansion due to temperature changes) or they may be expanded into the bottom tube sheet and packed into the top tube sheet or they may be expanded into the tube sheets at both ends, as desired, all in accordance with conventional construction practice.

The gas to be cooled fills the space between the tube sheets and surrounding the water tubes l3 and I4 andmaybeadmitted at l5 and discharged at It or conversely, if con-current heat exchange is desired. As thus far described the structure is purely conventional.

In practicing my invention, a flow distributor or anti-recirculating element 20 (Figure l) is positioned preferably at the top inlet of each of the tubes in the downpass section (or sections) of a condenser. The fiow distributor may take the form of an element for controlling or metering" the flow oi. cooling water into each tube such as shown in enlarged section in Figure 2. A portion of a tube ll in assembled relation with a portion of the top tube sheet 3 is shown, as well as the tion, a narrowing or restriction 2| is provided which is similar in shape to a Venturi meter.

In Figure 3, the restriction 22 in the flow distributor 20 is provided which takes the form of a short tube orifice of a diameter smaller in any desired degree relative to the water tube into which the anti-recirculator is fitted.

In Figure 4, the restriction 23 in the flow distributor 20 takes the form of a standard sham edged orifice.

While the flow distributor means 20 may preferably be located at the top of these tubes for convenience in installation and subsequent inspection, it will be understood they might alternatively be located at the other end (outlet) of the tubes or at any intermediate position.

In the case of the three modifications just described, the increase in pressure loss through the downpass tulbes due to the flow distributors associated therewith is suflicient to oiiset the thermal recirculationhead resulting from the heating of the water (and its consequent decrease in specific gravity) as it descends in the condenser tubes and, hence, no thermal recirculation occurs. Instead, a relatively smooth even flow is assured in each of the tubes with a resultant increas in efficiency.

According to Figure 5, the flow distributing means 20 may take the form of the swaged end of the tube which is merely swaged or reduced in cross-section by any conventional method and fixed within the tube sheet 3. The action of the modification is similar to that of the several Just described. It will be understood that other types of orifices might be utilized as fiow distributin means. For example, a plug containing one or more notches in its periphery might be inserted in each of the tubes in the liquid downpass section, the decrease in the eii'ective cross-section of the tube for fiow of water serving to increase the velocity of the liquid as it flows past the plug as in the modifications just described. The notches might be V-shaped, semicircular, or otherwise.

With regard to Figures 2 to 4, the particular method of assembly 01' the flow distributor means and associated tube into the tube sheet is not critical. Any equivalent method of assembly may be adopted, that shown being merely for purposes of illustration.

I may control the flow of water in other ways, however.

Thus, I may prefer 'to'meter or control the fiow of water into each downpass condenser tube by means of a tube extension in the form of a weir. These are used at the top 01' the tubes in a condenser with a top water box.

Thus, as shown, in Figure 6, I may provide a relatively short tube extension 25 at the top or its associated tube ll. In the upper periphery of the tube extension 25, I provide a V-notch 26 so that the extension 25 acts as a weir. By suitably regulating the water fiow rates into and out of the condenser in conjunction with the use 01 the weir, I may in one method of operation readily obtain a condition of flow wherein none of the water ever completely fills the whole cross-section of any of the downpass tubes. In other words, the water merely spills over the weir and down along the inner surfaces only 01' the downpass tubes in a free-fall." Hence, no columns or slugs" of water which would be forced back up the tubes (due to thermal recirculation head) ever form.

Generally, however, the condenser is operated in such a mannerthat the tubes are flooded or anti-recirculating element 20. In this modiflca- 7 full oi water throughout at least'substantially their entire length. By providing tube (or weir) extensions of such a length that their tops are always somewhat above the highest level to which the water in the warmest tubes (in the downpass section) could ever rise (due to any reasonable thermal recirculation head which might be encountered in operation of the condenser) it will be obvious that the water in the top water box wfll be forced to spill over the weir into the downpass tubes at all times and, therefore, no back or reverse flow can take place in the tubes so equipped.

The operation according to Figure 7 is similar but I provide a tube extension 21 with an unbroken rim to form a curved sharp edged weir instead of the V-notch weir of Figure 6. In this modification the tube extension need not be quite so high as in Figure 6.

Figure 8 shows diagrammatically a single pass condenser provided with the V-notched weirs similar to that shown in Figure 6 and formed in the tubes extended above the upper tube sheet. In general, the construction and operation is similar to that shown in Figure 1, except that the top water box is open to the atmosphere. The weirs maintain the water in the top water box at about the level denoted by Y. The highest level which heated water within the flooded condenser tubes can attain is indicated by X. Thus, while the cooling water is free to spill through the V-notches of the tube 'extensions and into the tubes from level Y to level X, it is obvious that heated water due to any thermal recirculation tendency cannot flow up from level X to level Y.

Figure 9 represents diagrammatically-a three pass condenser provided with the curved sharp edged weirs similar to that shown in Figure 7 and formed by the downpass tubes extended above the upper tube sheet. As before, the construction and operation is similar to that of Figure 1, except that the top water box is open to the atmosphere. As in Figure 8, the liquid levels are indicated at X and Y and reverse flow of water is prevented in a similar manner. In these modifications, it will be evident that the particular method of assembly of the tube extension or weir and its associated tube into the tube sheet is not critical, that shown being merely for purposes of illustration. For example, if desired, the tube extensions might be inserted (as by pressing) in the condenser tubes of condensers already constructed, as shown in greater detail in Figures 6 and 7. Alternatively, as when designing and/or constructing new condensers, the tube extensions might be formed merely by extending the condenser tubes themselves the desired distance above the top tube sheet. Such a construction is shown in Figures 8, 9 and 10.

While I have described my invention in terms of particular details of construction, it is obvious it is not limited thereto.

Thus, the condenser shell may be cylindrical or any other shape. The condenser tubes may be ordinary round tubes, or may be of any other shape. The tubes may be of any desired crosssectional area and may be present in any desired number and arrangement within the condenser.

The condenser may be either open with gravity flow of water or it may be closed with gravity or pressure flow of water, as desired.

As already indicated, the flow of the gas being cooled relative to the liquid cooling medium may be concurrent or countercurrent, as for instance, by suitably arranging the pipe connections to the openings l5 and it of the condenser shown in Figure l.

The substance to be cooled is usually a gas or vapor (i. e., the apparatus is primarily a gas condenser or cooler) but it may be a liquid.

The cooling medium may be water or it may be any other liquid. Toluene is an example of such a. liquid where it is desirable, for instance, 1to cool to very low temperatures without freez- The apparatus may be a single pass condenser or it may be a multi-pass condenser of any greater number of passes. In either case my invention is preferably applied to each of the tubes of the liquid downpass section or sections.

While the condenser to which my invention is applied may preferably be of the vertical tube type, it is not limited thereto but may also be used in apparatus in which the water tubes are somewhat inclined from the vertical. In such cases, if the weirs shown in Figures 6 to 10 are used it may be preferred to cut the tops of the tube extensions at such an angle that the tube openings when the condenser is in operating position will be substantially horizontal.

As illustrating the utility of my invention, one instance may be noted in which it was successfully applied to a gas condenser handling substantial quantities of hot manufactured gas containing water vapor and condensible hydrocarbons.

The condenser was of the 4-pass type, 4 feet in diameter equipped with tubes 18 feet long. The gas entered the condenser at about 205 F. and left at about 93 F. The cooling water entered countercurrently at about 78 F. and left at 127 F.

The temperature of the water in the open top water box over one of the liquid downpass sections (i. e., the one nearer the condenser water outlet) varied sharply from point to point over a range of about 95 to 151 F., indicating considerable recirculation of hot Water from the bottom hot water box. It should be noted that the maximum temperature in. this range was actually well in excess of the temperature of the water leaving the condenser, indicating that non-useful work of cooling some of the water was being done in the subsequent passes of the condenser.

Upon installing weirs or tube extensions such as shown in Figure 6, however, in all the tubes of this downpass section the temperature of the water in the top water box was thereafter maintained substantially uniform over a relatively small range, namely F. to 106 F., indicating that thermal recirculation had been substantialsubstitutions and/or modifications' comprising: acasing; upper and lower liquid flow reversing chambers therein forming a gas chamber therebetween; vertical tubes for cooling liquid, said tubes extending through the gas chamber which is to be traversed by the medium to be cooled, between the upper and lower reversing chambers, and arranged in groups for flow oi. cooling liquid successively upwards and downwards in successive groups, each tube group being connected with the adjacent one by a reversing chamber at one of the upper and lower ends of the tubes; bailies dividing the gas chamber into compartments corresponding to the tube groups so that the medium to be cooled passes through the casing among the tubes counter current to the flow of liquid through the respective tube groups; the tubes of a downflow group extending higher above the base of the upper reversing chambers than those of an adjacent upflow group.

2. A cooler for treating gases or other media comprising: a casing; upper and lower liquid flow reversing chambers therein forming a gas chamber therebetween; vertical tubes for cooling liquid, said tubes extending through the gas chamber which is to be traversed by the medium to be cooled, between the upper and lower reversing chambers, and arranged in groups for flow of cooling liquid successively upwards and downwards in successive groups, each tube group being connected with the adjacent one by a reversing chamber at one of the upper and lower ends of the tubes; baflies dividing the gas chamber into compartments corresponding to the tube groups so that the medium to be cooled passes through the casing among the tubes countercurrent to the flow of liquid through the respective tube groups; the tubes of a downflow group extending higher above the base of the upper reversing chambers than those of an adjacent upflow group and partition means preventing flow oi! liquid between the upper reversing chambers.

3. In a gas condenser having at least one downpass section in which a liquid cooling medium flows downwardly through tubes extending from an upper liquid chamber to a lower liquid chamber, said liquid chambers forming therebetween a gas chamber through which the gas being cooled is passed about said tubes, the improvement comprising separate static head increasing means associated with individual tubes said downpass section comprising tube extensions extending upwardly into said upper liquid chamber, whereby the head through said tubes is increased suflflciently to substantially prevent upward flow therethrough in spite of a lower specific gravity of said cooling liquid in said lower liquid chamber as compared with the specific gravity of said cooling liquid in said upper liquid .chamber.

4. A gas condenser comprising an upper liquid chamber, a lower liquid chamber, a plurality of i 1 tubes extending from said upper liquid chamber Qto said lower liquid chamber to form a downpass section in which a liquid cooling medium passes downwardly, a shell about said tubes and associthrough said tubes, means for withdrawing liquid cooling medium from said lower liquid chamber after flowing downwardly through said tubes, and separate head increasing means associated with each or said tubes for increasing the head in said tube in the direction of downward flow of said liquid cooling mediumss it flows downwardly through said tube, thereby largely preventing upward flow of said liquid cooling medium in any oi! said tubes due to a lower specific gravity or said liquid cooling medium upon reaching said lower liquid chamber as compared with the specific gravity of said liquid cooling medium when in said upper liquid chamber.

5. A gas condenser comprising an upper liquid chamber, a lower liquid chamber, a plurality of tubes extending from said upper liquid chamber to said lower liquid chamber to iform a downpass section in which a liquid cooling medium passes downwardly by gravitational flow, a shell about said tubes and associated with said upper liquid chamber and said lower liquid chamber in a manner to form a gas chamber through which the gas to be cooled is passed in indirect heat exchange relationship with said liquid cooling medium in said tubes, means for introducing liquid cooling medium into said upper liquid chamber for gravitational flow downwardly through said tubes. means for withdrawing liquid cooling medium from said lower liquid chamber after flowing downwardly through said tubes, and separate head increasing means associated with each of said tubes for increasing the head in said tube in the direction of gravitational flow of said liquid cooling medium as it flows by gravitation downwardly through said tube, thereby largely preventing upward flow oi said liquid cooling medium in any of said tubes due to a lower specific gravity of said liquid cooling medium upon reaching said lower liquid chamber as compared with the specific gravity of said liquid cooling medium when in said upper liquid chamber.

6. A gas condenser comprising an upper liquid chamber, a lower liquid chamber, a plurality oi tubes extending from said upper liquid chamber to said lower liquid chamber to form a downpass section in which a liquid cooling medium passes downwardly by gravitational flow, a shell about said tubes and asssociated with said upper liquid chamber and said lower liquid chamber in a manner to form a gas chamber through which the gas to be cooled is passed in indirect heat exchange relationship with said liquid cooling medium in said tubes, means for introducing liquid cooling medium into said upper liquid chamber for gravitational flow downwardly through said tubes, means for withdrawing liquid cooling medium from said lower liquid chamber after flowing downwardly through said tubes, and separate head increasing means comprising a liquid crosssectional area flow constrictor associated with each or said tubes for increasing the head in said tube in the direction of gravitational flow of said liquid cooling medium as it flows by gravitation downwardly through said tube, thereby largely preventing upward flow of said liquid cooling medium in any of said tubes due to a lower specific gravity or said liquid cooling medium upon reaching said lower liquid chamber as compared with the specific gravity of said liquid cooling medi when in said upper liquid chamber.

JOHN S. HAUG.

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