US3026043A - Blowdown tank and heat conservor - Google Patents

Description

March 20, 1962 J. w. LACY ETAL BLOWDOWN TANK AND HEAT CONSERVOR Filed May '7, 1959 5 Sheets-Sheet 1 FIG./

5mm PRESSURE VESSEL z 22 BOILER J BLOW Dow/v TANK AND HEAT CU/VSERVER INVENTORS Johnson W. Lacy 6. Kepler Brown, Jr

ATTORNEY March 20, 1962 J. w. LACY ETAL 3,026,043

BLOWDOWN TANK AND HEAT CONSERVOR Filed May 7, 1959 5 Sheets-Sheet 2 FIG. 2

- Johnson W. Lacy 6. Kepler Brown, Jr.

March 1962 J. w. LACY ETAL 3,026,043

BLOWDOWN TANK AND HEAT CONSERVOR Filed May 7, 1959 5 Sheets-Sheet 4 HEAT EXCHANGER 2 HEAT 5 EXCHANGER 1 INVENTORS Ja/mson W. Lacy C. Kepler Brown, Jr.

7 WATER L/NE March 20, 1962 J. w. LACY ETAL BLOWDOWN TANK AND HEAT CONSERVOR 5 Sheets-Sheet 5 Filed May 7, 1959 FIG.9

INVENTORS Johnson W Lacy C. Kepler Brown, Jr BY wcbm iw United States Patent 6 "ice 3 026 043 nLoWnowN AN AN HEAT CONSERVOR Johnson W. Lacy and Charles K. Brown, Jr., Richmond,

Va., assignors to Concrete Building Units Company,

Inc., Richmond, Va., a corporation of Virginia Filed May. 7, 1959, Ser. No. 811,680 10 Claims. (Cl. 231-167) at the end of each operation cycle in order that the cham-.

ber may be opened for unloading and reloading. The steam supply boiler is less frequently blown down, but nevertheless it is a standard practice. A blowdown not only wastes heat but also produces annoying exhaust blast.

It is, therefore, an object of this invention to provide various arrangements of blowdown tanks and heat conservers for condensing blowdown steam from any pressure device and reclaiming a high percentage of heat energy contained therein together with a total elimination of blast effect.

Another object of this invention is to provide various arrangements of heat exchange systems for more efiicient operation of cyclic pressure vessels.

These and other objects and advantages of this invention will become more readily apparent and understood from the detailed specification of the invention considered in connection with the accompanying drawings in which:

FIG. 1 is a schematic diagram of a steam pressure systern for a pressure vessel incorporating features of this invention;

FIG. 2 is a vertical cross-section of a first embodiment of a blowdown tank;

FIG. 3 is a cross-section viewed in the direction of the arrows 33 of FIG. 2, with one jet thereof being shown in cross-section;

FIG. 4 schematically illustrates a second arrangement of an efiicient steam pressure system using a second embodiment of a blowdown tank;

FIG. 5 is a cross-section of a heat exchanger, partly in elevation, used in the steam pressure system of FIG. 4;

FIG. 6 is a vertical section of a third embodiment of a blowdown tank used in the steam pressure system of FIG. 1 or FIG. 4;

FIG. 7 is a schematic of a proposed heat exchanger system for use in one of the steam pressure systems of FIG. 1 or FIG. 4;

FIG. 8 is a vertical section of a fourth embodiment of a blowdown tank used in the steam pressure system of the present invention; and

FIG. 9 is a plan view of the autoclave illustrated in- FIG. 1, showing the door in open position.

Referring now to FIG. 1 of the drawings, there is shown a conventional steam pressure vessel or autoclave 10 having the usual door 11 at one end, hinged as at 1141, Condensed steam or condensate is removed from the autoclave 10 by a condensate conduit 22, and replenishing steam is supplied to the autoclave through a steam line or conduit 14 leading from a heated boiler 12,

To avoid the loss of heat carried by the withdrawn condensate or condensed steam, the condensate or steam is channeled through the conduit 22 through a top aperture 38 into a cylindrical water filled blowdown tank 30..

Autoclave 10 is blown-oil or reduced to atmospheric pressure by a blowdown conduit 16 and the boiler 12, by means of a boiler blowdown conduit 18 Suitable control 3,02%,il43 Patented Mar. 29, 1962 valves V positioned in conduits 16 and 18 are provided for these operations. This blow-oft steam from the conduits 16. or 13. is channeled by means of a blowdown injector conduit 20 through branched injector lines 34 and 36 into the lower portion of the blowdown tank 31} on diametrically opposite sides, as shown best in FIGS. 2 and 3.

A boiler Water feed conduit 24 interconnects blowdown tank 30 with the boiler 12. A cold water supply line 26 and an overflow Water conduit 28 are also provided and attached to tank 30, as shown in FIGS. 1 and 2. The blowdown tank 30 is almost completely filled with water 58. The condensate conduit 22 discharges beneath the surface of water 58 near the top center of blowdown tank 30 and alongside of a centrally disposed heat extractor 50.

Heat extractor 50 is made up of a plurality of tubes 52 joined at the top and bottom to hollow headers 54. A cold water supply line 26 is joined to the lower header 54 and, the boiler water feed conduit 24 joins to the upper header 54. A tubular strut-supported sleeve 56 is arranged to coaxially surround the cluster of tubes 52.

Each injector branch line 34 and 36 terminates in a jet injector 42 tangentially positioned with respect to the circumference of blowdown tank 30 near the bottom and oppositely directed as best shown in FIG. 3.

Each jet injector 42 consists of an outer tube 46 and a coaxial strut-supported inner tube 44. The inner tubes 44 may be continuations of the branch lines 34 or 36 and preferably have a plurality of end perforations 48.

In operation, the hot condensate or condensed steam enters the blowdown tank 3i through the conduit 22 at the top thereof and spreads over the heat extractor 50. The cooled condensate moves downwardly inside of the sleeve 56 and it starts a convection flow indicated by the arrows in FIG. 2 and a recirculation of the fluid down over the heat extractor 50. The recovered heat is thereby fed into the boiler feed water into the lower header 54 and upwardly through the tubes 52 to the upper header 54 and then passing out through the conduit 24 and on to the boiler 12.

The cooling of the condensate water by the heat extraction process described above lowers its temperature to a level that will allow it to efficiently absorb the heat of a blowdown cycle. Blowdown steam from either the auto clave 10 or boiler 12 as desired is injected into the tank 30 through the jet injectors 42. As the steam passes through the jet injectors 42 through the end perforations 48, it draws suficient water 58 with it to completely condense it thus killing the blast normally associated with blowdown. The heat is also drawn off and reused by means of the above-mentioned convection currents transferring heat to the boiler feed water in heat extractor 50.

Water 58 is held to a fixed level by withdrawing the coolest water from the bottom of the tank 30 through the overflow conduit 28. This overflow water may be recovered if purified by a filter 40 and channeled through a conduit 32 back into the water supply.

An alternate form of blowdown tank 60 is shown in FIG. 4. Instead of using an internal heat exchanger 50 as just described, an external heat exchanger 74) is provided in duplicate.

One heat exchanger 70 is inserted into the condensate conduit 22 leading from the autoclave 10 to the blowdown tank 6%. This cools the condensate to a temperature at which the immersed jet injector 42 can eificiently dispose of the blowdown therethrough.

A perforated bafile plate 62 forms a barrier to turbulence of the liquid water between the bottom and top of the tank 69 but still allows convention currents of the heated water to rise and the cooled water to fall. The hot water which rises in the blowdown tank 60 is withdrawn by a pump P through an outlet conduit 64, circu- \1 lated through a second external heat exchanger 70 and back to the bottom of the blowdown tank 60 through an inlet conduit 66.

Heat exchangers 70 are typically of the construction illustrated in FIG. 5. The hot water travels through a heating coil 78 in its passage through the heat exchange 70. Cold water enters the heat exchanger 70 by an inlet port 74 and traverses the coil 78 in passing across a fluid space 72 to the outlet port 76.

Cold water from the line 26 may pass serially through the two heat exchangers 70, joined as shown by an interconnecting conduit 68, and on into the boiler water feed conduit 24. Optionally, the two heat exchangers 1 and 2 may have their inlet ports joined and outlet ports joined in a parallel connection of exchangers, as shown in FIG. 7. A thermostatically controlled diverting valve 101 with a thermo sensing element 100 for each heat exchanger 1 and 2 may be used to feed the greater amount of cold water to the heat exchanger 1 or 2 with the highest temperature. In this way, the heat diflerentials would be kept at a maximum and thus recovery of heat would proceed at maximum efliciency.

FIG. 6 shows another arrangement of blowdown tank 31 having a tapered or conical shaped bottom instead of a cylindrical bottom as shown in FIGS. 1, 2, and 4, which can be used as a sludge settling bowl and removal system having an outlet conduit 84 with either a manual control valve 86 or a thermostatically controlled valve in lieu thereof. The valve 86 can be opened manually or automatically prior to blowdown to lower the water level in the blowdown tank 31, thus providing space for the blowdown condensate passing into the system.

The bottom of the blowdown tank 31 of FIG. 6, that is, the conical section deflector can be utilized to mechanically induce upward movement of the water. The inlet conduit 90 can be used to pass the cold water through the coil 92 in tank 94 prior to being passed to the lower header 54 of the heat extractor 50 as previously described to heat the water before passing therethrough. Hot water at the bottom of the conical shaped blowdown tank 31 of FIG. 6 can be passed through the conduit 82 to. the tank 94 to heat the cold water passing through the coil 92 to the heat extractor 50. An overflow conduit 33 can be associated with tank 94 if desired. The upper end of the tank 94 can be opened or closed as shown.

Instead of utilizing the blowdown tanks 30 of FIGS. 1, 2, or 31 of FIG. 6, or the blowdown tank 60 of FIG. 4,

. in the steam pressure system, the blowdown tank 30 of FIG. 8 can be used, wherein a coil 114 is substituted for the heat extractor 50 of FIGS. 2, 3, and 6. This coil 114, which can be of any desired shape and size, has an inlet conduit 112 for cold water and an outlet conduit 110 for hot water. The other components of the blowdown tank 30 of FIG. 8 will correspond to the components illustrated in FIG. 2, with the exception of the heat extractor 50. In some cases, it might be desirable to serially connect the coil 114 with the heat extractor 50.

It should be understood that there is normally suflicient time between blowdowns of the autoclaves 10 or boilers 12 to allow the heat gradient by convection to be established between top and bottom of either tank 30 or tank 60. Also sufficient water 58 should be provided in the blowdown tanks 30 and 60 so that all of the heat from one blowdown period will be absorbed without heating the water above 200 F. because to do so would cause vaporization of the water and loss of heat in the system.

Obviously many other modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A blowdown tank and heat conservor in combination with a steam pressure device comprising structure defining a vertically disposed tank, a heat exchanger having an inlet passage and an outlet passage, means for passing condensate from said steam pressure device through said heat exchanger and said tank, in such manner as to maintain said tank substantially full of water, and means including at least one horizontally directed jet injector located near the bottom of said tank for discharging blowdown steam from said steam pressure device, whereby convection currents are created in the water in said tank and the blast effect of the discharged steam is minimized.

2. In combination, an autoclave, a boiler for supplying steam to said autoclave, a blow-down tank, means for delivering into said tank the condensate from said autoclave, said tank having an overflow near the top thereof, a heat exchanger having an inlet and an outlet through which the hot condensate in said tank circulates and also having a passageway through which the feed water for said boiler flows, whereby the feed water is heated, at least one horizontally directed submerged jet device located near the bottom of said tank, and means whereby steam from said autoclave may be discharged into said tank through said submerged jet device, whereby the heat of the steam is absorbed by the water in said tank. 3. An arrangement in accordance with claim 2 in which means are provided whereby steam from either said autoclave or said boiler, as desired, may be discharged into said tank through said submerged jet device.

4. An arrangement in accordance with claim 2 in which the overflow is constructed to withdraw water from near the bottom of the tank, whereby the coldest water is discharged.

5. An arrangement in accordance with claim 2 in which a plurality of horizontally disposed oppositely directed submerged jet devices are positioned near the bottom of the tank, and means are provided for discharging steam from either said autoclave or said boiler simultaneously into both of said jet devices.

6. An arrangement in accordance with claim 2 in which the body of the tank is circular and its lower portion, in which said jet device is located, is conical, to serve as a mechanical deflector for causing upward movement of the water adjacent the Walls of the tank.

7. An arrangement in accordance with claim 2 in which the heat exchanger is located within the tank, and means whereby convection currents are set up to cause the water in said tank to circulate over said heat exchanger.

8. An arrangement in accordance with claim 2 in which the heat exchanger is located outside of said tank, and through which the hot condensate in said tank is caused to circulate. 9. An arrangement in accordance with claim 2 in which the heat exchanger is located outside of saidtank at a point between the tank and said autoclave, and means for conducting the condensate from said autoclave through said heat exchanger on its way to said tank.

10. An arrangement in accordance with claim 2 in which two heat exchangers are employed, one heated by the condensate on its way from the autoclave to said tank, and the other heated by the hot condensate in said tank, and in which means are provided for causing the boiler feed water to flow through both heat exchangers.

References Cited in the file of this patent UNITED STATES PATENTS 973,603 Winslow Oct. 25, 1910 ;1,850,797 Jaeger Mar. 22, 1932 2,055,211 Yoder Sept. 22, 1936 2,289,953 Aldridge July 14, 1942 2,312,217 King et a1 Feb. 23, 1943 2,582,198 Etheridge Jan. 8, 1952 2,582,889 Barnebey et al. Jan. 15, 1952

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