US 1918966 A
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Description (OCR text may contain errors)
July 18, 1933.
A. M. HARKNESS APPARATUS FOR TREATING GAS Filed June 20, 1930 Patented July 18, 1933 UNETED STATE s Parser lhalti ce l ANDREW" 11E. HARKNESS, 0F NYACK, NEW YORK, ASSIGNOR T0 GENERAL CHEMICAL jjj COMPANYr OF NEW' YORK, N. Y., A CORPORATIQN or. new vonkI APPARATUs Fon TREATING cas Application filed June 20,
My invention relates to heat exchc nge devices such as Waste heat boilers and particularly to methods and means for controlling the temperature of materials.
Heat exchange devices are usually designed to edect the maximum transfer of heat from one medium to another in order that the apparatus may operate With high efficiency. However, in some instances it is desira le to effect only a limited amount of heat transfer or to control the temperature of one or both of the media receiving and giving up heat. For example, in the manufacture of sulfuric acid by the contact process, het sulfur dioxide gases issuing from a sulfur burner are ordinarily cooled to a predetermined temperature prior to their purification, catalysts to S03 or to other stages of the process. In order to reduce the hot gases to the desired temperature,itisusual to pass a portion of the hot gases through a heat exchanger or Waste heat boiler and to pass a regulated amount of the hot gases through a by-pass directly from the sulfur burner to be mixed with the cooled gases leaving the heat exchange device to thereby control the temperature of the gas. Heat exchange devices thus employed are not variable or controlled to effect either a greater or lesser amount of heat transfer from the hot burner gases. The by-pass and valves used to control the ioW of hot gasesfrom the sulfur burner are continually subjected to high temperature and have but short life. Furthermore, if a break should occur in the valve in the exterior by-pass there Would be danger of destroying or injuring subsequent units of the system.
Among the objects of my invention are to provide improved means and methods for controlling' the temperature of materials, to utiliz-e excess heat transferred from the heated medium to the cooling' medium and to render the operation of heat exchange del vices variable at will to alter the amount of heat exchange effected by such devices.
In accordance with my invention the amount of heat transfer effected and the temperature of the heating and cooling media are regulated by controlling one or both of 1830. Serial No. 462,525.
the following variable factors:v (l) The rate A ferring surface in Contact with the heat transferring media.
ln practicing my invention the heat transferring media are passed in indirect heat exchanging relation With'each other on the opposite sides of a heat transferring surface.
or example, in cooling hot sulfur burner gases the hot gases may be passed through. the tubes of a Waste heat boiler which are surrounded by Water and steam. The rate of flow of the hot burner tubes of the Waste heat boiler-may be varied in any suitable Way as by restricting the flow of het gaseslthrough a portion of the tubes While permitting unrestricted flow of the gases through the remaining tubes. In this Way the rate of flow of the heated gases passing through -the unobstructed tubes ofthe boiler is altered so that the temperature of the gases is varied to somedierent degree. Thus the temperature of the gases leaving the heat exchange device may be controlled manually or automatically by restricting the rate of flow of the gases passing through any portion of the tubes to any desired extent.
If desired the flow of gasesthrough any portion of the tubes may be cut olf altogether so that the effective area ofthe heat transferring surfaces of the tubes Within the Waste heat boiler is decreased and the rate of flow of the gases through the remaining tubes is increased. In thisway the temperature of the gases leaving the heat exchange device is i variable at will either manually or automat-v ically as desired. y
The process of my invention may -be car-4 ried out in any suitable heat exchange apparatus and may be utilized to effect heat exchange between various forms of heat transferring media. However, l have illustrated in the figures of the drawing' and will hereinafter describe preferred types of Waste heat boilers for carrying out the process Vand embodying the apparatus features of my in-n vention. l
gases through ythe l loo In the figures of the drawing,
Fig. 1 is a vertical sectional view of a waste heat boiler embodying my invention;
Fig. 2 is a view of a portion of a waste heat boiler embodying a modilied form of my invention taken at right angles to the view shown in Fig. 1; and
Fig. 3 is a similar view illustrating a further modification of my invention.
In the form of the invention illustrated in the drawing, a waste heat boiler is shown comprising a casing 2 in the form of an upright metallic cylinder provided with base 4 and a top 6. An inlet 8 for the hot gas-es from a sulfur burn er communica-tes with the lower portion of the casing 2, and an outlet 10 for the gasesleaving the waste heat boiler connects with the upper portion of the casing. A header 12 is provided in the upper portion of the casing spaced from the top 6 to provide a chamber 14. The edges of the header 12 are flanged and secured directly tothe cylindrical casing 2. A lower header 16 is spaced from the base 4 of the waste heat boiler to provide chamber 18 between header 16 and the base. rIhe periphery of the header 16 is flanged and secured to the corrugated expansion member 20, the lower portion of the expansion member being secured to the cylindrical casing 2. The interior of the chambers 14 and 18 may be lined with insulating material 22 and firebrick 24 to protect the casing and prevent loss of heat through these portions of the apparatus. Heating tubes 26 extend between the headers 12 and 16 to provide a passage for the hot gases from the lower chamber 18 to the upper chamber 14. One or more heating tubes 28 preferably of a comparativelylarger crosssection than the heating tubes 26 also extend between headers 12 and 16 to provide an additional passageway for the hot gases'passing through the heat exchange device. Tubes 26 and 28 together form a passage for the hot gases through the cooling section of' the boiler.
Water is admitted to the space 30 within the casing 2 surrounding the heating tubes 26 and 28. An inlet 32 for the water is provided in the lower portion of the casing adj acent the corrugated expansion member 2() and an outlet 34 for the steam produced is provided in the upper portion of the casing adjacent the header 12. A sight glass 36 is also provided for indicatingl the level of the water within the` chamber 30.
In order to control the operation of the heat exchange device to vary the amount of heat given up by the hot gases in passing from the inlet 8 to the outlet 10, a damper, plug or valve 38 or other suitable member is located in the upper chamber 14 above the end of the heating tube 28. The damper 38 is movable vertically toward and away from the header Y 12 and the end of the heating tube 28 to restrict the flow of gases through the tube 28 or to close the end of the tube altogether. A
shaft 40 is secured to the damper 38 and passes upwardly through a stufung box 42 secured in JAli top 6. The upper end of the shaft is formed with threads 44 whiclL en gage a complement-ary threaded member secured to the top 6 by means of the bracket 48. The shaft 40 moved vertically by rotation of the handle 50 to raise the damper 38 into the dotted line position which the damper is spaced a sufficient distance from the end of the tube 28 to permitunobstructml flow of the gases therethrough and by counter rotation of the handle is lowered into the desiredvposition with respectto the end 'of t ie tube.
.The operation of the form of the device illustrated in Fig. 1 is as follows. It will be recalled that the boiler includes one or more tubes28, the cross-sections of which are comparatively large with reference to the cross- 'sec'tion of any of the tubes 26. Assuming that the valve or valves 38 are in the lowermost position thus closing` off tube or tubes 28, the het gases from sulfur burner or other source pass through the inlet 8 into the chamber 18 and flow upwardly through the tubes 26 to the chamber 14 in the upper port-ion ofthe casing. Duringthe passage of the hot gases through tubes 26, quantities of heat arerremoved from the gases and transferred to the water surrounding the tubes with thel resulting generation of steam. .temoval of heat from the `gases while the latter are in the upper ends of tubes 26 is continued, though in a lesser degree, by the steam surrounding tubes 26 above the water` level. in the space 30. The `frases in the upper chamber 14, cooled to some mesi-red temperature in accordance with the nature of the gases and the specific design. and arrangementof the tubes26, pass out of the heat exchanger through the outlet 10.
If it should be desired to decrease the amount of heat transfer from the hot gases to the cooling liquid surrounding the tubes,
one or more of the valves 38 ma;7
through If the thus permitting passage of the gases one or more of the enlarged tubes 28.
cross-section of the enlarged tube or tubes 28 is relatively large as compared with the cross-- section of the tubes 26, it will be seen that the resistance offered to the passage of the gases through enlarged tubes 28 will be les@y than that offered to the passage of the through small tubes 26. As the gases flowing through the tubes'tend to follow tl path of least resistance, in effect, a comparatively large volume of hot gases from the chamber 18 is by-passed through the large tube or tubes 28 into the upper cb amber 14 thus raising the temperature of the gas therein, and accordingly raising the temperature of the gases leaving the boiler through the 'outlet 10.
ferring media over the heat transferring surfaces, the ratio of the area of the heat transfer surface to the volume of at least one of the heat transferring media passing over such surface, and the effective area of the heat transferring surface in contact with theheat transferring media. llien tubes 28 are opened for the passage of hot gases, the effective area of the heat exchange surface of the tubes in contact with the cooling medium in the space 30 is increased, but under certain circumstances, as for example, when the crosssection 'of tubes 28 is large as compared with that of tubes 26, the increased cooling surface is not suiiicient to effect transfer of the greater quantity of heat in the comparatively arge volume of hot gases passing through the tube o r tubes 28. In this manner the temperature of the gases passing through the outlet 10 of the heat exchanger may be readily controlled.
It is not necessary that the damper38 fit tightly against the end of the tube 28 since the limited flow of gases through the tube 28 which might occur would not materially affect the operation of the device. For this reason frequent repair and adjustment of the apparatus is not required.
which is secured to the wheel 54. The damper 38 covers se veral of the heating tubes 26, and when in its lowermost position in contact with the upper ends of the tubes 26, prevents the flow of gas through any but the outer row or rows of heating tubes. In this form of the device the damper 38 is raised and lowered by the rotation of the wheel 54, which is secured to a shaft 56 mounted in the brackets 58. The end of the shaft 56 extends outside the casing 2 and has an operating wheel 60 secured thereto. The wheel 60 may be rotated by a chain 62 or any other suitable means to raise or lower the damper 38 to restrict the flow of hot gases through the tubes to the desired extent.
The method of operation in this form of the invention is as follows. The damper is lowered to restrict the flow of gases through the heating tubes located in the central porcontact with the ends of the tubes 26 prevents the flow of hot gases through the tubes located in the center of the header while leaving the remaining tubes unobstructed. The effect of closing oli" the center tubes is to reduce the effective area of the heat transfer surface, with the result that the temperature of the exit gases from the heat exraised position shown in dotted @When in its lines the flow of gases through all of the tubes is unrestricted and the amount of heat exchange effected changer of Fig. 2 is raised.
by the passage of gases through the device isI at` its maximum, andthe temperature of the exit gases is at a minimum. A.
e form of the device illustrated in Fig. 3 differs from those shown in Figs. land 2 in that the number of heating tubes complet-ely closed by the action ofthe dampers '38 may be progressively varied to vary theeftective area of the heat transferring surface of the device. In this forni of the invention a plurality of damper-s 64, the ends of which chain are secured to the wheels 66 and 68. These wheels are rmount ed on shafts 70 carried bv brackets 72. One end of each of the shafts 70 extends outside of the casing 2 and has secured'thereto. The operating wheels may be rotated to lower the chain 64 and the dampers 38 into position adjacent the ends of the heating tubes-'26 by means of a chain 76 which passes o.
and is provided with a branch chain 78 ex tending downwardly therefrom.
When operating' thisforni of the invention the dampers 38 are lowered into position adj acent the ends of the heating tubes 26 by allowing the branch chain 78 to rise, thus mitting the'operatin g wheels 7 4, shafts 70 and Wheels 66 and 68 to rotate, allowing 'the dampers 38 to drop into their operative position b v their own weight. Those dampers 38 secured to the center of the chain 64 first come into contact with the ends of the tubes 26 and upon further ro`ation of the operating wheels, a progressively increasing number of with the ends of the tubes 26, thus'varying the effective area of the heat exchanging surface of the device. In each form of the device illustrated the damper for controlling the flow of heated gases through the tubes is located inthe upper chamber of the waste heat boiler so that the damper is not suhjected to the intense heat of the gases passing into the device from the sulfur burner or other source of hot gases, but is in contact only with the cooled gases passing from the tubes of the boiler to the outlet. In this way the damper is protected against excessively high temperatures so that its length of life is indefinitely prolonged. Although this location of the damper is preferred, the damper may be located adjacent'the lower header or within the tubes themselves if desired.
Although I have` shown and described specific forms of the invention as applied in the transfer of heat from one fluid to another in a waste heat boiler, it is apparent that the invention is also applicable to the transfer of heat between fluids and solids or for controlling the temperature of either 38 are secured to a chain'L an operating wheel 74 ver the operating' wheels 74:
dampers 38 are lowered into contact uids or solids. tended that the invention to the specific embodiments shown and described since both the process and the apparatus features of' the invention may be varied considerably without departing from the invention as defined by the following claims.
1. A waste heat boiler comprising a vertical casing, headers in said casing spaced from the ends thereof to provide chambers at the top and bottom of the casing, an inlet for hot gases connected to the lower chamber, an outlet for the gases connected to the upper chamber, tubes connecting the chambers through which the hot gases pass from said inlet in the lower chamber to said outlet in the upper chamber, an inlet and outlet for water and steam connected to the space within the casing between said chambers and surrounding said tubes, and a member located in the upper chamber to which the outlet for the gases is connected and above the ends of said tubes, said member being movable vertically and so constructed and arranged that when lowered the ends of a portion of said tubes are successively closed oil leaving other tubes unobstructed.
2. A waste heat boiler comprising a casing, headers in said casing spaced from the ends thereof to provide chambers at the ends of the casing, an inlet for hot gases connected to one chamber, an outlet for the gases connected to the second chamber, tubes connecting the chambers through which the hot gases pass from said inlet in the irst chamber to said outlet in the second chamber, an inlet and outlet for water and steam connected to the space within the casing between said chambers and surrounding said tubes, and means mounted in the second chamber movable toward and away rfrom the ends of the tubes and acting when moved toward the ends of the tubes to successively .close ott1 a portion of said tubes leaving other tubes unobstructed.
3.` A waste ing, headers-in said easing spaced from the ends thereof to provide chambers at the ends of the casing, an inlet for hot'gases connected to one chamber, an outlet for the gases connected to the second chamber, tubes connecti.
ing the chambers through which the hot gases-pass from said inlet in the first chamber to said outlet in the second chamber, an inlet and outlet tor water and steam contween said chambers and surrounding said tubes, and a flexible damper mounted in the second chamber movable toward and away from the ends of the tubes and acting?` when moved toward cessively close ofi a portion of; said tubes leaving other tubes unobstructed.
4. A waste heat boilercomprising a vertical casing, headers in said casing spacey from the ends thereof to provide chambers at the top and bottom of the casing, an inlet for hot gases connected to 1the lower chamber, an outlet for the gases connected to the upper chamber, tubes connecting the chambers through which the hot gases pass from said inlet in the lower chamber tc said outlet in the upper chamber, an inlet and outlet Jfor water and steam connected to the space within the casingbetween said chambers and surrounding said tubes and a ileni- ANDREW M. iraniennes.
heat boiler comprising a casi nected Yto the: space within the casing be- 1,50
the ends ot the tubes to suclos i is