/ Marley Class 800 Mechanical Draft Cooling Tower / User Manual 95-1356A }Ê/iV }ià >ViÊNÊ >Ê ÀÞÊ }ÊNÊ >ÀiÞ
Notice The following defined terms are used throughout this manual to bring attention to the presence of hazards of various risk levels, or to important information concerning the life of the product. Warning Indicates presence of a hazard which can cause severe personal injury, death or substantial property damage if ignored. ▲ Caution Indicates presence of a hazard which will or can cause personal injury or property damage if ignored.
Contents General.................................................................................................... 4 Before Start-up........................................................................................ 5 Initial Starting Procedure......................................................................... 7 Routine Starting Procedure..................................................................... 8 Operation..............................................................................
General A cooling tower, like any heat exchanger, exchanges all heat imposed upon it from one fluid to another fluid. For a cooling tower, heat from the water is put into the air. The plant process replenishes the heat to the water, typically at another heat exchanger such as a condenser. A cooling tower differs from many heat exchangers in that heat is transferred in two forms—sensible and latent heat.
Before Start-up Safety ▲ Caution Temporary safety barricades should be placed around any exposed openings in the operating (or nonoperating) tower, safety harnesses should be worn by personnel where appropriate, and other safety precautions should be taken in compliance with OSHA regulations and standards. Cleaning Clean any nozzles that are clogged. Remove any sediment from the cold water basin, sump and screens. Use a water hose to flush cold water basins.
Before Start-up See Geareducer Service Manual for oil filling procedure and list of recommended lubricants. • Rotate fan by hand to be sure of free rotation and ample tip clearance. See Marley Fan Service Manual. • Check motor insulation with a “Megger.” See maintenance section of Marley Electric Motor Service Manual. • Lubricate the motor according to motor manufacturer’s instructions. • Test run each fan separately for a short time. Check for excessive vibration or unusual noise.
Initial Starting Procedure 1— Fill the cold water basin and circulating water system to a level 1/2” (13 mm) below the overflow. 2— Bypass valve should be closed unless start-up is in cold weather. (See Routine Starting Procedure on page 8.) 3— Prime and start the circulating water pumps one at a time. Increase the flow of circulating water gradually to design water rate to avoid surges or water hammer which could damage the distribution piping.
Routine Starting Procedure After periods of routine shutdown, the following restarting procedure should be followed: • Start the circulating water pump(s). Increase the flow of circulating water gradually to design water rate to avoid surges or water hammer which could damage the distribution piping. ▲ Caution Circulating cold water over a tower in freezing weather will cause ice to form, which may cause damage to the fill system.
Operation Tower Performance The following is intended to serve as a guideline for the operation of this counterflow mechanical draft cooling tower. The owner may use this information to develop preliminary operating procedures. As operational experience with the system accumulates, more definitive responses to specific conditions will be developed by the owner’s operating personnel. Keep the tower clean and the water distribution uniform to obtain continued maximum cooling capacity.
Operation When changing fan direction of rotation, allow a minimum of two minutes time delay before energizing the fan motor. Hot Water Distribution System Hot water from the process flows through an inlet to each cell, which supplies a distribution header and a system of branch arms and nozzles. Each distribution header may be equipped with a vent standpipe to minimize water hammer, to maintain a slightly pressurized water distribution system, and to provide vacuum release at pump shutdown.
Freezing Weather Operation ▲ Note During periods of low ambient air temperatures, 35°F to 40°F (2°C to 4°C) or below, it is advisable to maintain the cold water temperature at or above 70°F (21°C) to retard the formation of ice and to assist in its control. The methods used in Minimizing Tower Energy Use, described on page 13 are those which the operator would use to maintain water temperature at or above 70°F (21°C).
Freezing Weather Operation • Under extended extreme cold conditions, it may be necessary to operate the fan in reverse. This forces warm air out through the air inlets, melting any accumulated ice. Reversal may be at either full or half speed; however, full speed is recommended if adequate heat load is available. Reverse operation of the fan should be avoided, where possible, and should not exceed 15 to 20 minutes.
Temperature Control and Energy Management The wet-bulb temperature of the ambient air varies significantly on a daily basis, and considerably from season to season. As the wet-bulb temperature reduces, the tower becomes capable of producing colder and colder water—or it becomes capable of producing a given cold water temperature at reduced airflow through the tower. These characteristics are the “opposing forces” referred to on page 4.
Temperature Control and Energy Management number of seconds it takes your fan to get to full-speed (by observation) and divide that number into 30 to obtain the recommended maximum number of starts per hour. Two-speed motors cycling between half and full speeds permit a commensurately greater number of control cycles. Variable frequency drives, of course, provide the ultimate in both temperature control and energy management and can be easily retrofitted to your system.
Maintenance Well maintained equipment gives the best operating results and the least maintenance cost. A regular inspection schedule is recommended to insure effective safe operation of the cooling tower. Use the Inspection and Maintenance Schedule on page 25 to obtain continuously good performance with least tower maintenance. See the Inspection Checklist on pages 26 and 27 in this manual. Keep a continuous lubrication and maintenance record for each cooling tower.
Maintenance sibility to institute a program of water treatment and maintenance that will minimize their impact. (See Water Treatment on pages 18 and 19.) Tower Framework Inspect for cracks and spalling and repair if necessary. Keep bolts tight in the mechanical equipment supports. Maintain a positive Langelier index in your circulating water. (See Water Treatment on pages 18 and 19.) Drive Shaft Check drive shaft alignment and condition of couplings every six months.
Cleaning Warning Any evaporative-type cooling tower must be thoroughly cleaned on a regular basis to minimize the growth of bacteria, including Legionella Pneumophilla, to avoid the risk of sickness or death. Service personnel must wear proper personal protective equipment. Do NOT attempt any service unless the fan motor is locked out.
Water Treatment Blowdown Blowdown, or bleed-off is the continuous removal of a portion of the water from the circulating system. It is used to prevent dissolved solids from concentrating to the point where they will form scale. The amount of blowdown required depends upon the cooling range (design hot water temperature minus design cold water temperature) and the composition of the make-up water (water added to the system to compensate for losses by blowdown, evaporation, and drift).
Water Treatment predict the corrosive tendencies of the tower water toward concrete. An explanation and method of calculating the Langelier index can be found in all books on water treatment. Maintaining a positive Langelier index provides excellent protection of concrete. Slime, a gelatinous organic growth, and algae, a green or brown plant growth, may grow in the cooling tower or heat exchangers. Their presence can interfere with cooling efficiencies.
Seasonal Shutdown Instructions Tower Drain all tower piping. During shutdown, clean the tower and make any necessary repairs. Apply protective coating as required to all metal parts. Particular attention should be given to mechanical equipment supports, drive shaft and drive shaft guards, Geareducers, and motors. See Warning note on page 17 regarding tower cleaning. Visually inspect for concrete deterioration. If ambient temperature is 32°F (0°C) or below, do not put cold water on tower.
Spare Parts and Accessories Spare Parts SPX Cooling Technologies manufactures and maintains a stock of replacement parts for all cooling tower mechanical equipment. Shipment of these parts is normally made within ten days after an order is received. If emergency service is necessary, contact the local Marley sales office or representative for assistance.
Troubleshooting Trouble Cause Remedy Motor Will Not Start Power not available at motor terminals 1. Check power at starter. Correct any bad connections between the control apparatus and the motor. 2. Check starter contacts and control circuit. Reset overloads, close contacts, reset tripped switches, or replace failed control switches. 3. If power is not on all leads at starter make sure overload and short circuit devices are in proper condition.
Troubleshooting Trouble Cause Remedy Wrong Rotation (Motor) Geareducer Noise Wrong sequence of phases Geareducer bearings Switch any two of the three motor leads. If new, see if noise disappears after one week of operation. Drain, flush, and refill Geareducer. See Geareducer Service Manual. If still noisy, replace. Correct tooth engagement. Replace badly worn gears. Replace gears with imperfect tooth spacing or form. Tighten all bolts and cap screws on all mechanical equipment and supports.
Safety The tower has been designed to provide a safe working environment while either operating or shut down. The ultimate responsibility for safety rests with the Operator and Owner. When flow to the tower is shut off or when portions of the tower require maintenance, temporary safety barricades may be required around openings. Other safety precautions such as safety harnesses should be utilized where appropriate for compliance with OSHA regulations and standards and good safety practices.
Inspection and Maintenance Schedule General Recommendations 1. Inspect for clogging 2. Check for unusual noise or vibration 3. Inspect keys, keyways, and set screws 4. Make sure vents are open D D D D W Davits, Derricks, Hoists Stairs, Ladders, Walkway, Doors, Handrails Casing and Louvers Fan Cylinder Structural Members Control Valves or Gates Suction Screen Water Make-up System Hot Water System Cold Water Basin Fill Drift Eliminators M M W S S S S 5. Lubricate (grease) S R 6.
Inspection Checklist Date Inspected Inspected By Owner Location Owner's Tower Designation Tower Manufacturer Model No. Process Served by Tower Operation: Design Conditions GPM Cell No. Number of Fan Cells HW °F Serial No.
Inspection Checklist Condition: 1—Good Mechanical Equipment Speed Reducer Type Belt ❏ 2—Keep an eye on it Gear ❏ 3—Needs immediate attention 1 2 3 Direct Drive ❏ Comments Belt Drive Unit Belt Designation Fan Sheave Designation Motor Sheave Designation Gear Drive Unit Manufacturer Oil Level Oil Condition: Model Add Immediately ❏ Contains Water ❏ Full ❏ Good ❏ Ratio Low, check again soon ❏ Contains Metal ❏ Contains Sludge ❏ Oil Type Used Seals Backlash Fan Shaft Endplay Unusual Noises? No ❏
Cooling Technologies Balcke | Hamon Dry Cooling | Marley / 7401 W 129 Street // Overland Park, KS USA 66213 // +1 913 664 7400 // spxcooling@ct.spx.com // www.spxcooling.com / In the interest of technological progress, all products are subject to design and/or material change without notice. ©2006 SPX Cooling Technologies, Inc.
