US3762690A - Mixing system for floating roof tanks - Google Patents

Mixing system for floating roof tanks Download PDF

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Publication number
US3762690A
US3762690A US00221966A US3762690DA US3762690A US 3762690 A US3762690 A US 3762690A US 00221966 A US00221966 A US 00221966A US 3762690D A US3762690D A US 3762690DA US 3762690 A US3762690 A US 3762690A
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US
United States
Prior art keywords
roof
impeller
tank
motor
liquid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00221966A
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English (en)
Inventor
H Harrington
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mixing Equipment Co Inc
Original Assignee
Mixing Equipment Co Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mixing Equipment Co Inc filed Critical Mixing Equipment Co Inc
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Publication of US3762690A publication Critical patent/US3762690A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D88/00—Large containers
    • B65D88/34—Large containers having floating covers, e.g. floating roofs or blankets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
    • B01F27/80—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis
    • B01F27/91—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis with propellers

Definitions

  • FIG- 2 FIG. 4
  • the invention involves recognition of the possibility of mounting a tank mixer on the floating roof.
  • a tank mixer on the floating roof.
  • there were several serious problems involved in such an arrangement and it was initially very doubtful that satisfactory mixing could be accomplished by a roof-mounted mixer.
  • further study of the problem and laboratory experiments have shown that not only can satisfactory mixing be accomplished with a roof-mounted mixer, but safety requirements can be met, mounting and other problems can be solved, and the result has many surprising economic advantages over side-entry mixers.
  • the inventive mixing system applies to a liquid storage tank having a floating roof, and it includes a mixer motor mounted on top of the roof over a through opening in the roof.
  • a generally vertical'shaft turned by the motor extends through the roof opening into the liquid below, and an impeller is mounted on the shaft below the roofin the liquid for mixing the liquid.
  • the impeller is configured to pump predominantly vertically to establish a vertical flow preferably in the center of the tank to induce radial flow along the top and bottom of the tank for full circulation.
  • Flexible power connections lead to the motor, and a vapor lock is preferably formed between the roof and the shaft.
  • FIG. I is a partially schematic, sectional elevational view of the interior ofa liquid storage tank using the inventive mixing system
  • FIG. 2 is a partially schematic, partially cut-away elevational view of a vapor lock for the mixer shaft of FIG. 2;
  • FIGS. 3 and 4 are partially schematic, fragmentary views of preferred liquid flow patterns for the inventive system.
  • storage tank is generally known and preferred for storing petroleum products. It
  • a floating roof 1 that is also generally known for floating on the stored product and rising and falling with its level.
  • liquid mixing within tank 10 was accomplished by side-entering mixers mounted in the lower wall of tank 10, but by the inventive system, a mixer 12 is mounted on roof 11 as illustrated.
  • Mixer 12 includes a mixer motor 13 mounted on a plate 14 preferably in the center of roof 11.
  • Plate 14 covers a substantial central opening in roof 11, and as best shown in FIG. 2, has a small through opening 15 for receiving the drive shaft 16 of mixer 12.
  • a preferably liquid-filled, vapor lock 17 surrounds shaft 16 for a vapor seal between shaft 16 and roof 11 at opening 15.
  • Shaft 16 extends below roof 11 into the liquid in tank 10 and supports an impeller 18 that is configured for vertical pumping. With mixer 12 in the center of roof 11 as preferred, vertical pumping by impeller 18 can keep the product in tank 10 well mixed and circulated.
  • Plate 14 is preferably removable and large enough so that mixer 12 can be removed by lifting impeller 18 up through roof 11 through the opening normally coveredby plate 14. This can be accomplished with a lifting jib 19 such as shown in FIG. 1.
  • plate 14 can be omitted, and mixer 12 with its shaft 16 and impeller 18 can be permanently installed in roof 11 to be removed or repaired only when tank 10 is drained and opened for inspection and repair.
  • a sump or well 20 is preferably formed in the bottom center of tank 10 in registry with impeller 18, so that roof 11 can sink to its lowermost position without any interference from impeller 18.
  • Another way to keep the heel of tank 10 to a minimum is to mount impeller 18 as close under roof 11 as feasible.
  • Motor 13 is powered through a power transmission conduit 21 leading in from outside tank 10.
  • Motor 13 can be either electrical with conduit 21 carrying energized electrical conductors, or motor 13 can be hydraulic with conduit 21 carrying pipes filled with pressurized liquid. Either way, motor 13 rises and falls with roof 11 relative to tank 10 to require flexing of conduit 21 between tank 10 and motor 13.
  • Several forms of flexible conduit are available, and there are several ways that can be arranged to carry power safelyto motor 13. Many safety requirements have to be met, and especially for an electric motor 13, electric or spark hazards must be avoided.
  • FIG. 1 One preferred solution to the flexible conduit problem is shown in FIG. 1 where conduit 21 is fixed in place and rigid from motor 13 along the top of roof 11, along ladder 22, and along the outside of tank 10. Ladder 22 moves between top and bottom positions of roof 1] as illustrated and provides part of the conduit connection.
  • a flexible conduit connection includes a fixed post 23 having a swivel top 24 supporting a section of flexible conduit 25 connecting to rigid conduit 21 at the upper end of ladder 22.
  • Flexible conduit 25 and swivel top 24 allow the illustrated conduit movement between the upper and lower positions of ladder 22 as illustrated.
  • a rigid post 26 leads conduit 21 to a swivel top 27 from which a length of flexible conduit 28 leads to a support post 29 at the bottom of ladder 22.
  • Flexible conduit section 28 moves between upper and lower positions of ladder 22 as illustrated, to keep a free loop of conduit between posts 26 and 29 and safely out of contact with other equipment to allow rise and fall of roof Ill without hazard.
  • FIGS. 3 and 41 The circulation flow created in tank It) by impeller 18 is schematically represented in FIGS. 3 and 41 showing two alternative preferred embodiments.
  • impeller 18 is oriented to pump upward to draw liquid up from the bottom of tank it) in a central column that is directed against the under side of roofllll and forced radially outward across the top of tank 10. This causes a downward flow around the walls of tank It) and an inwardly radial flow across the bottom of tank back to the uprising central flow to impeller 18. The result keeps the liquid in tank well mixed and prevents sediment settling.
  • Such flow can be assisted by a draft tube and diffuser 30 arranged around impeller 18 as illustrated to help guide upflowing liquid into impeller 18 and to help speed the radially outward flow under roof 11. Draft tube and diffuser 30 can be omitted, and this is preferred, especially for minimum projection of mixing equipment down under roof 11.
  • the impeller 18 of FIG. 4 is oriented for downward pumping to establish a circulation pattern the reverse of FIG. 3.
  • impeller 18 draws liquid radially inward under roof 11 and pumps liquid downward to the bottom center of tank 10 where the liquid turns radially outward to sweep across the bottom of tank 10 and rise along the outer walls to be drawn radially inward under roof 11 for another pass through impeller 18.
  • the down-pumping impeller of FIG. 43 requires a little more clearance under roof l1 and is preferably spaced'below roof II by about its radius.
  • the inventive roof-mounted mixer system is superior to side-entry mixers in many ways.
  • a well-designed mixer system in the center of a tank roof can mix the entire tank with one mixing unit, where the same size tank could require several side-entry mixers.
  • the installation of a roof mixer is much simpler and safer than a side entry mixer which requires a very strong and well constructed flange mounting with a secure stuffing box forming a liquid seal around the mixer shaft.
  • the roofmounted unit is also easier to maintain, partly because only a vapor lock is required around its shaft, and it can be removed without draining the tank.
  • Side-entry mixers require a much higher minimum roof clearance above the bottom of tank 10 to make a much larger and more costly tank heel of unusable volume.
  • An improved mixing system for a liquid storage tank having a floating roof comprising:
  • a mixer motor mounted on top of said floating roof to travel up and down with said roof relative to said tank;
  • said roof having a through opening in the region of said motor
  • said impeller being configured to pump predominantly vertically in said liquid
  • said power supplying means including a power transmission line fixed to the outside of said tank, a power transmission line fixed relative to said floating roof, and a flexible power transmission line for connecting said fixed lines to accommodate relative motion between said fixed lines.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Mixers Of The Rotary Stirring Type (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)
US00221966A 1972-01-31 1972-01-31 Mixing system for floating roof tanks Expired - Lifetime US3762690A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US22196672A 1972-01-31 1972-01-31

Publications (1)

Publication Number Publication Date
US3762690A true US3762690A (en) 1973-10-02

Family

ID=22830193

Family Applications (1)

Application Number Title Priority Date Filing Date
US00221966A Expired - Lifetime US3762690A (en) 1972-01-31 1972-01-31 Mixing system for floating roof tanks

Country Status (8)

Country Link
US (1) US3762690A (enrdf_load_stackoverflow)
JP (1) JPS5611494B2 (enrdf_load_stackoverflow)
AU (1) AU469301B2 (enrdf_load_stackoverflow)
CA (1) CA962999A (enrdf_load_stackoverflow)
DE (1) DE2304225C2 (enrdf_load_stackoverflow)
FR (1) FR2170005B1 (enrdf_load_stackoverflow)
GB (1) GB1397042A (enrdf_load_stackoverflow)
NL (1) NL176769C (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4136974A (en) * 1977-08-10 1979-01-30 Palotsee John J Seal and propeller drive assembly for industrial cleaning tanks
US4884245A (en) * 1989-03-21 1989-11-28 Jwi, Incorporated Quick-connection drive coupling for mixing tank
CN105080383A (zh) * 2013-07-15 2015-11-25 Spx流动有限公司 可伸缩的混合装置和方法
US11352201B2 (en) * 2020-01-08 2022-06-07 Jing Kai Industrial Co., Ltd. Peripheral sealing assembly for an internal floating roof

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2427274A1 (fr) * 1978-05-30 1979-12-28 British Petroleum Co Toit flottant allege pour reservoir de stockage de produit petrolier

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2931534A (en) * 1958-04-07 1960-04-05 John H Wiggins Automatic emergency drain mechanisms for floating roofs
US3329301A (en) * 1963-11-21 1967-07-04 Exxon Research Engineering Co Floating tank top
US3343817A (en) * 1966-06-29 1967-09-26 Interchem Corp Apparatus for mixing materials in the substantial absence of air
US3411756A (en) * 1967-09-11 1968-11-19 Ziegler Moses Mixing device for fluids

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1912595A (en) * 1930-08-29 1933-06-06 Pacific Flush Tank Co Sludge digestion tank
US2516917A (en) * 1945-12-14 1950-08-01 Allis Chalmers Mfg Co Agitator
NL301206A (enrdf_load_stackoverflow) * 1962-12-07 1900-01-01
US3294372A (en) * 1964-12-14 1966-12-27 Union Oil Co Floating roof mixing tank

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2931534A (en) * 1958-04-07 1960-04-05 John H Wiggins Automatic emergency drain mechanisms for floating roofs
US3329301A (en) * 1963-11-21 1967-07-04 Exxon Research Engineering Co Floating tank top
US3343817A (en) * 1966-06-29 1967-09-26 Interchem Corp Apparatus for mixing materials in the substantial absence of air
US3411756A (en) * 1967-09-11 1968-11-19 Ziegler Moses Mixing device for fluids

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4136974A (en) * 1977-08-10 1979-01-30 Palotsee John J Seal and propeller drive assembly for industrial cleaning tanks
US4884245A (en) * 1989-03-21 1989-11-28 Jwi, Incorporated Quick-connection drive coupling for mixing tank
CN105080383A (zh) * 2013-07-15 2015-11-25 Spx流动有限公司 可伸缩的混合装置和方法
US11352201B2 (en) * 2020-01-08 2022-06-07 Jing Kai Industrial Co., Ltd. Peripheral sealing assembly for an internal floating roof

Also Published As

Publication number Publication date
FR2170005B1 (enrdf_load_stackoverflow) 1978-03-03
AU5150073A (en) 1974-08-01
DE2304225A1 (de) 1973-08-09
GB1397042A (en) 1975-06-11
FR2170005A1 (enrdf_load_stackoverflow) 1973-09-14
CA962999A (en) 1975-02-18
DE2304225C2 (de) 1984-11-08
JPS5611494B2 (enrdf_load_stackoverflow) 1981-03-14
NL7301363A (enrdf_load_stackoverflow) 1973-08-02
NL176769C (nl) 1985-06-03
JPS4887462A (enrdf_load_stackoverflow) 1973-11-17
AU469301B2 (en) 1976-02-12
NL176769B (nl) 1985-01-02

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