SECTION CHILLERS

Transcription

1 SECTION PART I - GENERAL 1.01 WORK INCLUDED A. Extent of work shall be as indicated on Drawings and provisions of this section, including schedules and equipment lists associated with either Drawings or this section QUALITY ASSURANCE A. Manufacturers: Firms regularly engaged in manufacturer of chillers and accessory equipment of type and sizes required, whose products have been in satisfactory use in similar service for not less than five (5) years. B. UL and NEMA Compliance: Provide electric motors and electrical components required as part of chiller equipment, which have been listed and labeled by Underwriters Laboratories and comply with NEMA standards. C. NEC Compliance: Comply with National Electrical Code (ANSI/NFPA 70) as applicable to installation and electrical connections of ancillary electrical components of chillers and accessory equipment SUBMITTALS A. Product Data: Submit manufacturer's chiller and accessory equipment specifications, installation and start-up instructions, and capacity and ratings, with selection points clearly indicated. B. Maintenance Data: Submit maintenance data and parts lists for each item of chiller and accessory equipment. Include "trouble- shooting" maintenance guides. Include this data in maintenance manual. PART II - PRODUCTS 2.01 WATER-COOLED CHILLER A. Furnish and install factory-assembled York, Trane, or equal water-cooled screw compressor water cooled centrifugal liquid chilling packages using Refrigerant R-22, R- 123 or R-134a. Model, size, and quantity, shall be as listed on the Drawings. B. Performance shall be certified in accordance with ARI Standard Only chillers that are listed in the ARI Certification Program for Centrifugal and Rotary Screw Water Chillers are acceptable. C. Each unit shall be completely factory-packaged including evaporator, condenser, subcooler, oil separator, compressor, open motor, lubrication system, micro-computer control center, solid state starter with non-fused disconnect switch and all interconnecting unit piping and wiring. Refrigerant shall be R-22, R-123 or R-134a, shipped inside the unit

2 D. The compressor shall be an open-drive, rotary-screw type or semi hermetic centrifugal. The compressor housing shall be of cast iron, precision machined to provide minimal clearance for rotors. The rotors shall be manufactured from forged steel and use asymmetric profiles operating at a maximum speed of 3570 RPM. The compressor shall incorporate a complete anti-friction bearing design to reduce power and increase reliability; four separate cylindrical roller bearings to handle radial loads; and two fourpoint angular contact ball bearings to handle axial loads. The compressor shall have an internal oil reservoir to assure a constant supply of oil to the bearings at all times. A spring actuated positive seating check valve shall be incorporated in the compressor housing to prevent rotor backspin during shutdown. The shaft seal shall be a spring loaded carbon ring with precision lapped collar cooled by low pressure oil. E. Capacity control shall be achieved by use of a slide valve or in case of centrifugal unit limit demand load to provide fully modulating control from 100% to 10% of full load. The slide valve shall be actuated by oil pressure, controlled by external solenoid valves through the microcomputer control center. The unit shall be capable of operating with lower temperature cooling tower water during part-load operation in accordance with ARI Standard If the unit cannot operate at the minimum load, the manufacturer shall provide a hot-gas-bypass system to allow operation at 10% load, and advise the minimum load and power input of the unit at the point hot-gas-bypass is actuated. F. The motor shall be two-pole, continuous duty, squirrel cage induction type, and shall have an open drip proof enclosure. Motor full-load amperes at design conditions shall not exceed motor nameplate (FLA). Motor shall be designed for use with the starter type specified. Motor shall be factory-mounted and directly connected to the compressor to provide compressor/motor alignment. G. An adequate supply of oil shall be available to the compressor at all times. During startup and coastdown, this shall be achieved by oil reservoirs in the compressor, or by prelube and postlube oil pump operation. During operation, oil shall be delivered by positive system pressure differential or full-time operation of an oil pump. An oil reservoir shall be located in the compressor to lubricate bearings in the case of a power failure. H. An immersion oil heater shall be provided, temperature actuated, to effectively remove refrigerant from the oil. An external replaceable-cartridge, oil filter shall be provided, along with manual isolation stop valves for ease of servicing. An oil eductor shall be provided to automatically remove oil which may have migrated to the evaporator and return it to the compressor. The oil separator shall be of a horizontal design with no moving parts, and shall provide effective oil separation before the refrigerant enters the heat exchangers. A refrigerant-cooled oil cooler shall be provided to allow operation of the chiller over the full range of operating conditions. I. Evaporator shall be of the shell-and-tube, flooded type designed for 300 psig working pressure on the refrigerant side, and be tested at 450 psig. Shell shall be fabricated from rolled carbon steel plate with fusion welded seams; have carbon steel tube sheets, drilled and reamed to accommodate the tubes; and intermediate tube supports spaced no more than four feet apart. The refrigerant side shall be designed, tested and stamped in accordance with the ASME Boiler and Pressure Vessel Code, Section VIII-Division 1. Tubes shall be high-efficiency, internally enhanced type. Each tube shall be roller expanded into the tube sheets providing a leakproof seal and be individually replaceable. Water velocity through the tubes shall not exceed 12 FPS. Liquid level sight glasses shall be located on the side of the shell to aid in determining proper refrigerant charge. The evaporator shall have a refrigerant relief device to meet the requirements of the ASHRAE 15 Safety Code for Mechanical Refrigeration

3 J. Water boxes shall be removable to permit tube cleaning and replacement. Stub out water connections having Vitaulic grooves shall be provided. Water boxes shall be designed for 150 psig design working pressure and be tested at 225 psig. Vent and drain connections with plugs shall be provided on each water box. K. Condenser shall be of the shell-and-tube type, designed for 300 psig working pressure on the refrigerant side and be tested at 450 psig. Shell shall be fabricated from rolled carbon steel plate with fusion welded seams; have carbon steel tube sheets, drilled and reamed to accommodate the tubes; and intermediate tube supports spaced no more than four feet apart. A refrigerant subcooler shall be provided for improved cycle efficiency. The refrigerant side shall be designed, tested and stamped in accordance with the ASME Boiler and Pressure Vessel Code, Section VIII-Division 1. Tubes shall be high-efficiency, internally enhanced type. Each tube shall be roller expanded into the tube sheets providing a leakproof seal and be individually replaceable. Water velocity through the tubes shall not exceed 12 FPS. The condenser shall have refrigerant relief devices to meet the requirements of the ASHRAE 15 Safety Code for Mechanical refrigeration. L. Water boxes shall be removable to permit tube cleaning and replacement. Stubout water connections having Victaulic grooves shall be provided. Water boxes shall be designed for 150 psig working pressure and be tested at 225 psig. Vent and drain connections with plugs shall be provided on each water box. M. Refrigerant flow to the evaporator shall be metered by a single fixed orifice with no moving parts. N. The condenser shell shall be capable of storing the entire system refrigerant charge during servicing. Isolation from the rest of the system shall be by manually operated isolation valves located at the inlet and outlet of the condenser. Additional valves shall be provided to facilitate removal of refrigerant charge from the system. O. Each unit shall be furnished complete with a microcomputer control center in a locked enclosure, factory-mounted, wired and tested. The control center shall include a 40- character alphanumeric display showing all system parameters in the English language with numeric data in English units. P. Digital programming of essential setpoints through a color coded, tactile-feel keypad shall include: leaving chilled water temperature, percent current limit, pulldown demand limiting, seven-day timeclock for starting and stopping chiller, pumps and tower (complete with holiday schedule), and remote reset temperature range. Q. All safety and cycling shutdowns shall be annunciated through the alphanumeric display and consist of day, time, cause of shutdown and type of restart required. Safety shutdowns shall include: high condenser pressure, low oil pressure at compressor, clogged oil filter, high oil temperature, high oil pressure, high compressor discharge temperature, low evaporator pressure, motor controller fault and sensor malfunction. Cycling shutdowns shall include: low water temperature, cooler/condenser waterflow interruption, power fault, internal timeclock and anti-recycle. R. System operating information shall include: return/leaving chilled water temperatures, return/leaving condenser water temperatures (optional), evaporator/condenser refrigerant pressures, oil pressures at compressor and oil filter differential, percent motor current, evaporator/condenser saturation temperatures, compressor discharge temperature, oil temperature, percent slide valve position, operating hours and number of compressor starts

4 S. Security access shall be provided to prevent unauthorized change of setpoints and to allow local or remote control of the chiller. T. The chiller shall be provided with an RS232 port to output all system operating data and shutdown/cycling messages to a field-supplied printer. The control center shall be programmable to provide data logs to the printer at a set time interval. U. Control center shall be able to interface with a Metasys building automation system to provide remote chiller start/stop, reset of chilled water temperature, reset of current limit and status messages indicating chiller is ready to start, chiller is operating, chiller is shutdown on a safety requiring reset and chiller is shutdown on a recycling safety. V. The chiller manufacturer shall furnish a reduced-voltage solid-state starter for the compressor motor. Starter shall be factory-mounted and wired on the chiller. The started shall provide, through the use of silicon controlled rectifiers, a smooth acceleration of the motor without current transitions or transients. The started enclosure shall be NEMA 1, with a hinged access door with lock and key. Electrical lugs for incoming power wiring shall be provided. W. Protective devices shall include: phase rotation protection, single-phase failure protection, momentary power interruption protection, and high/low line voltage protection. Starter shall include: three leg sensing overloads, 120-volt control transformer for all unit controls, and a non-fused disconnect switch. Three-phase voltage and current readings shall be coordinated with the unit control center, with digital readout on the display. X. The chiller manufacturer shall include the services of a factory-trained, field service representative to supervise the initial startup and concurrent operator instruction. Y. Chillers shall be warranted for two (2) year parts and labor warranty ending thirty (30) months from shipment or twenty-four (24) months from start-up, whichever occurs first. Z. Insulation shall be ¾ thick flexible closed cell plastic factory applied with vapor-proof cement to cooler shell and tube sheets, oil cooler, refrigerant liquid distribution piping, suction connection, and auxiliary tubing as necessary. Insulation of cooler water box end plates and water nozzles will be furnished and installed as required under Specification Section "Mechanical Insulation." Insulation shall be provided with a final coat of factory applied vinyl paint. PART III - EXECUTION 3.01 INSTALLATION OF AND ACCESSORIES A. Install chillers and accessories as indicated, in accordance with manufacturer's installation instructions and in compliance with applicable codes. Units supplied shall not exceed the length of specified unit. B. An instruction manual completely describing installation, operation, and maintenance of the specific chiller being furnished, with details of all modifications, shall be provided with the unit. Copies of the chiller inspection and operational test reports shall be submitted with the manual. C. Supervision of start-up and instruction of operating staff shall be provided by factorytrained personnel. The local representative in which area the chiller is installed shall have factory-trained service personnel available on a 24-hour basis, seven days a week for emergency service

5 3.02 CARE AND CLEANING A. Repair or replace broken, damaged, or otherwise defective parts, materials, and work. Leave entire work in condition satisfactory to University's Representative. At completion, carefully clean and adjust equipment installed as part of this work. Leave systems and equipment in satisfactory operating condition OPERATION TEST A. Test each piece of equipment to show that it will operate in accordance with indicated requirements CLEANING UP A. Upon completion of Work remove materials, equipment, apparatus, tools, and the like, and leave premises clean, neat, and orderly. END OF SECTION