Normal working stresses for the material involved were used in calculating the stresses for the parts of the hoists and stems at the normal operating pressure of 750 pounds per square inch. For the maximum pressure of 1,000 pounds per square inch, all stresses were limited to two-thirds of the yield point of the material. For normal operating conditions the large regular pump requires about 6 minutes to open the gate, but the gate will close in about 30 seconds by gravity. If the gate sticks during the closing cycle, the pumps will force it down. The large pump will require about 6 minutes to close the gate, while if only the small emergency pump is operating it may require as long as 1-1/2 hours. 72. The func Turbine Draft Tube Bulkhead Gates and Service Bay Bulkheads. tion of the draft tube gates is to close off the outlet ends of the draft tubes in the event it is necessary to unwater the unit for inspection or maintenance of the unit or draft tube passages. The service bay bulkhead is used to seal off the downstream end of the stilling basin into which the outlet valves discharge. The gates and bulkhead are interchangeable in their respective openings and are sufficient for closing either generating unit and either stilling basin. Three gates having nominal dimensions of 6 feet 9 inches wide by 10 feet 2 inches high and one bulkhead 12 feet wide by 15 feet high were furnished in accordance with figures 35 and 36. The gates and bulkhead were shipped assembled except for the rubber seals, which were installed at the project. (a) Storage. --Each gate and bulkhead is stored in the upper portion of the gate slot above the draft tube opening and is supported on both sides by latches located in such manner that the lifting ears of the gate or bulkhead are just below the grating covering the gate slot opening. (b) Handling and Operation. --The gates and bulkhead are lowered, raised, and transferred from one opening to another by means of a 4-ton hand-operated twin hoist suspended on a push-type gantry crane operating on rails located on the deck. During maintenance or inspection of the stilling basin the bulkhead is lowered and left attached to the hoist. In the case of the turbine draft tubes the hoist must handle three gates; therefore a lifting frame was provided for grappling purposes. The gates and bulkhead operate on continuous guides, and during the last foot of lowering travel, leaf springs engage an offset on the guides forcing the gates to contact the bronze seats mounted on the side frames. The gates and bulkhead must be lowered and raised only under balanced head conditions. In case high-pressure penstock water is unintentionally admitted to the turbine and draft tube while a gate is in place, the gate will blow off its seat due to the relatively few bronze bolts fastening the guide angles to the side frame. The service bay bulkhead has no top seal; therefore the blow off feature is not provided on the bulkhead. (c) Construction. --The gates and bulkhead are fabricated from structural steel and seating is accomplished by a bronze to bronze contact of the gate side seats against the embedded gate frames. Sealing is accomplished by a music-note type of molded rubber water seal mounted continuously around four sides of each gate and on the sides and bottom of the bulkhead. Water pressure compresses the side and top seals and the weight of the gate or bulkhead compresses the bottom seal against the embedded steel sill. Four leaf springs are mounted on the sides of each gate and bulkhead to hold the unit in correct position when in a seated position and under a balanced water pressure condition. (d) Design. --For the draft tube gates, maximum stresses are calculated on the basis of a dry draft tube and maximum tailwater surface. The bulkhead is designed for a normal water surface which also represents the height of the bulkhead. Under these conditions the combined stress of face plate and beams is permitted to reach 24,000 pounds per square inch. Other stresses conform to the American Institute of Steel Construction. A spring pressure of approximately 14 pounds per square foot of gate area is provided for initial gate seating, and the gate frame guide angles are designed to fail at approximately a 15-foot differential head on the draft tube side of gate. Holes to match! Allowed for seal Bart 1.26 FM Cop screw Steel 12 Top seal, 5-9 long Rubber 40-0-536 * 13 BOTTOM CORNER SEAL CLAMP Top corner sea! Rubber 40-0-3087 Gates shall be shipped with small parts attached unless otherwise noted. Estimated weight of one bulkhead gate 4700 lbs. 6 SPRING Spring shall deflect if with a load of 508: 5% without permanent set. Symm about SPRING KEEPER Figure 35.--6-foot 9-inch by 10-foot 2-1/8-inch bulkhead gate for turbine draft tubes. LIST OF DRAWINGS ASSEMBLY-LIST OF PARTS-CLAMPS -SPRING. GATE LEAR REFERENCE DRAWINGS CONCRETE OUTLINES. BULKHEAD GATE FRAME 285-0-606 205-0-530 AND 841 ..209-0-600 UNITED STATES DEPARTMENT OF THE INTERIOR BUREAU OF RECLAMATION MISSOURI RIVER BASIN PROJECT BOYSEN POWER PLANT TURBING DRAFT TUBE @`8*2 10-28 BULKHEAD GATE ASSEMBLY-LIST OF PARTS-CLAMPS-SPRINGS TRACED.....C.R.. SUBMITTED...st RECOMMENDED APPROVED DENVER, COLORADO, BEAT 2,1980 285-0-606 SHEET I OP BOTTOM CORNER SEAL CLAMP 22 Spaces @ 6" 11'-0" "Holes to match BOTTOM SEAL CLAMP STEEL ONE REQUIRED (26 Spaces @6"× 13-0° ++ Bor 2. 7 Approx "Holes to match i Warp to fit leaf side seal see! See Side Elev. Dag 285-0-602 SIDE SEAL CLAMP NOTES Bulkhead shall be shipped with small parts attached unless Seat bases shall be welded in place before machining to a rough finish. Welting symbols apply to joints of all members of similar identification 7600 lbs Cerner radius on these edges Figure 36.--12-foot by 15-foot 0-1/2-inch bulkhead gate for service bay. D. Handling Equipment 73. Powerhouse Crane. A 60-ton-capacity crane was installed in the powerhouse. The main hoist is capable of handling the generator rotor weighing 114,000 pounds as a unit. The lifting speed of the main hoist (6 feet per minute) is low to ensure safe handling of the larger pieces of equipment. The auxiliary hoist of 10-ton capacity was designed for a lifting speed of 31 feet per minute. Moderate trolley and bridge speeds are used in conformance with standard practice for this type of service. The main and auxiliary hoists are mounted on a single trolley which travels on rails mounted on the bridge structure. The bridge structure, consisting of two built-up structural girders spaced 11 feet on centers, is equipped at each end with two two-wheel trucks mounting 24-inch-diameter wheels. A bridge drive motor with suitable gear reductions and shafting are utilized for driving one wheel on each end of the bridge. The crane is controlled from an operator's cab suspended below the drive girder. All hoist and travel drives are electric-motor operated. A stairway extends from the bridge footwalk to the operator's cab. Toe guards and angle-iron handrailing are provided on all platforms. Mechanical load brakes are supplied for the main and auxiliary hoist units. These brakes are arranged to prevent the load from lowering until power is applied in the lowering direction by the hoist motor. Spring bumpers, located at the four corners of the bridge and trolley, prevent damage to the crane in case of collision with the runway or bridge girder stops. The bridge drive motor is equipped with a hydraulically operated brake remotely controlled by a foot pedal in the operator's cab. A warning gong is attached to the operator's cage. Alternating current at 440 volts, 3-phase, 60 cycles is supplied to the crane by angle-type main conductors installed near one of the runway rails. Trolley conductors are mounted on the outside of the idler girder. All main and trolley collectors are the under-running type. The controls, mounted in the cage, provide variable speed control in each direction for all travel and hoisting motors. The controls are designed to control the vertical movement of the main and auxiliary hoists, when starting from rest, to within onesixteenth inch, and the movement of the bridge and trolley travels, when starting from rest, to within one-fourth inch. Limit switches operated by the upward travel of the load blocks determine the upper limits of the main and auxiliary hoist movements. 74. Draft Tube Gate and Stilling Basin Bulkhead Crane. A 4-ton gantry crane is located on the transformer deck of the powerplant and is used on a standby service basis for raising, lowering, or transporting the draft tube gates and stilling basin bulkheads during servicing of the units. ner. The built-up structural steel gantry is mounted on four wheels, one at each corA 4-ton-capacity, twin-hook, hand-operated, chain hoist is suspended over the gate slots by a cantilever section on the upstream side of the gantry. A concrete counterweight on the downstream side of the gantry provides stability against overturning. The gantry is moved by hand and a locking device is provided which holds the crane against movement due to wind load. The crane was designed with a safety factor of not less than 5, based on the ultimate strength of the material. 75. Hoists. - (a) Outlet Works Bulkhead Gate Hoist. --The bulkhead gate hoist for the outlet works consists of a fixed frame and a floor-mounted hoist. The hoist is of sufficient capacity to lift the 48, 000-pound bulkhead gate when the water loads on each side of the gate are equalized. The floor-mounted hoist drum is driven through reduction gearing by an electric motor. A mechanical load brake and a motor brake are provided on the hoist. A drum-type controller for reversing service is provided for the motor. A limit switch of the block-actuated type limits the hoisting travel of the lifting eye. The hoist was designed with a factor of safety of 5, based on the ultimate strength of the material. (b) Radial Gate Hoists. --Two 100,000-pound radial-gate hoists are installed on the operating deck of the spillway for raising the radial gates. A 10-horsepower electric gear motor is coupled to a worm gear reducer above the centerline of the gate. Drive shafts extending from either side of the worm gear unit are coupled to the hoisting units located above the ends of the gates. The hoisting units consist of a wire-rope drum and two stages of spur reduction gearing. Two parts of wire rope lead from the hoisting drum to an equalizing bar located near the bottom of the gate on the upstream side. A gate position indicator is connected to one of the end units on each hoist. Each hoist is equipped with a motor brake and a limit switch which limits the hoist both in raising and lowering. E. Miscellaneous 76. Ventilating Fans for Boysen Railroad Tunnel. - (a) Requirement. --Ventilating equipment was required for the evacuation of exhaust smoke and gases from the Boysen railroad tunnel during and after passage of steam-driven or oil-fired trains. The length of tunnel was 7, 113 feet and the tunnel has a continuous eastbound upgrade of 0.5 percent. Design studies and consultation with Chicago, Burlington, and Quincy Railroad officials and various ventilating fan manufacturers culminated with adoption of the following recommendation. An exhaust fan, centrifugal type, was to be installed over two riser shafts from the railroad tunnel to exhaust to atmosphere. The first riser was to be located approximately 1,310 feet inward from the portal of the lower elevation and the second was to be 2,550 feet beyond the first. Each fan was to deliver 200,000 cubic feet per minute at 0.625 inch of water-gage static pressure when operating at 4, 800 feet elevation with a 70° F. air temperature. One fan was to be installed at the first riser and two at the second. (b) Design of Ventilating Equipment. --The fans and their appurtenances being commercial products, the responsibility for a coordinated and adequate design of equipment required to meet the foregoing condition was left with the supply contractor. Robinson Ventilating Co., Zelienople, Pa., received the award, and following is the ventilating equipment furnished: (1) Three 12- by 8-foot double-inlet blowing fans. Each is complete with fabricated steel fan wheel of backward curves design; three-quarter housed fan casing arranged for top vertical discharge, having inlets protected with screen guards; forged steel fan shaft 12 inches diameter at fan hubs, 7 inches diameter under bearings; three 7-inch-diameter precision pillow blocks mounted on independent fabricated steel pedestals. Each fan was arranged to receive V-belt drive. (2) Three V-belt drives, each rated not less than two times the fan requirements, using one 10-groove C-section sheave 11. 6-inch pitch diameter, and one 72-inch-diameter flat pulley. (3) Three 40-horsepower induction-wound-rotor, sleeve-bearing motors, rated at 720 r. p. m., 440 volts, 3-phase, 60 cycles, with double shaft extensions (one to receive drive, the other provided with brake assembly) with base rails. (4) Three automatic controllers with appurtenances. |