SPECIFICATIONS MODEL EHV X VACUUM OIL PURIFIER

Transcription

1 SPECIFICATIONS MODEL EHV X VACUUM OIL PURIFIER

2 1 DEGASSING TECHNOLOGY This proposal describes the equipment which shall be supplied by ENERVAC for a system for processing (degassification, dehydration and filtration) transformer insulating fluids. Removing dissolved vapor and gas from a liquid is a physical process. Vapor or gas molecules randomly leave the surface of a liquid into surrounding gas, and also randomly leave the gas and enter the liquid. When the rate of molecules entering the liquid is equal to the rate of molecules leaving an equilibrium is achieved which is called saturation. Henry's Law states that the mass of gas dissolved in a given volume of solvent is proportional to the pressure of the gas with which it is in equilibrium. In a vacuum oil purifier the pressure of the gas is reduced by a vacuum pump and the oil is treated so that equilibrium can be achieved quickly. One approach is to extend the surface between liquid and gas and another is to encourage the formation of bubbles below the surface of the gas. Several approaches can be taken to the removal of dissolved vapors and gases from liquids as shown below. TRAYS extend the surface of the liquid, but no means of encouraging the bubbles to form are included. Trays require a high processing temperature which results in light ends being permanently removed from the oil. RINGS extend the surface of the liquid but no means of encouraging the bubbles to form are included. Rings require a high processing temperature which results in light ends being permanently removed from the oil. GLASS FIBER DEGASSING ELEMENTS both extend the oil surface and present millions of sharp ends to the flow of oil and each creates a "point of release" which encourages the formation of a bubble. This is similar to the stream of bubbles which can often be seen in a glass of Coca Cola or beer, the point from which the bubbles come is a scratch causing a "point of release". ENERVAC degassing accelerator elements are constructed in a way to maximize the "point of release" density. The elements not only stimulate the formation of small bubbles they also help large bubbles to collapse, tests prove that there is much less tendency to foam than with other degassing methods. Using this technique, ENERVAC Vacuum Oil Purifiers provide effective degassing at higher pressures and lower temperatures than other methods. The lower processing temperature assures that light ends, which preserve low viscosity for good cooling properties, are retained in the oil to perform exactly as the oil manufacturer intended. 2

3 2 SCOPE The scope of supply of this specification shall include the design, fabrication and factory testing of one (1) ENERVAC Model Number EHV X Vacuum Oil Purifier, as shown schematically in Bulletin , and shall consist of the equipment and components as subsequently described. The system, when received by the purchaser, shall provide a fully workable unit and shall perform in accordance with this specification. ENERVAC shall supply all necessary physical arrangements, mechanical, electrical connection, piping schematic and all necessary data for use in the operation and maintenance of this system. Prior to delivery of this system, ENERVAC shall provide three (3) copies of the instruction manual. One (1) complete copy of the manual shall be included with the shipment. This manual shall contain: Detailed Operating Instructions Maintenance Information Equipment drawings including Physical Arrangement, Electrical Diagram and Flow Diagram A Recommended Spare Parts List 3 PERFORMANCE Clean oil containing 100 PPM total water content and fully saturated with air at 12% by volume shall be dehydrated and degassified at the full rated capacity of the system, at a minimum oil supply temperature of 2 o C and shall meet the following specifications. Dielectric strength by ASTM Method D-877 shall not be less than 40 KV with new oil. Total soluble water content by ASTM Method D or D (Karl Fisher) shall be less than 10 PPM. Total gas content shall not be greater than 0.25% by ASTM Method D or by Doble Gas Content Analyzer ASTM D CAPACITY The maximum continuous purification capacity shall be 6,000 litres/hour. The ultimate pressure of the vacuum pump shall be less than 0.08 mbar. Capacity of the vacuum system shall be 300 m 3 /hr (50Hz). The system shall be capable of processing at reduced flow if required. 5 POWER REQUIREMENTS 380 Volts, 3 Phase, 50 Hertz - (110 kw Max.) 3

4 6 DIMENSIONS AND WEIGHT The purifying system shall be approximately 1,778 mm Wide x 3,048 mm Long x 1,980 mm High and shall weigh approximately 3,100 kgs. 7 DESCRIPTION OF COMPONENTS The purification system shall be fully assembled on a heavy duty steel base, which shall be sufficiently braced to minimize vibration. A drip lip shall be provided on the base to collect spillage and drippage. The system shall consist of the following components. 7.1 One (1) Oil Inlet Ball Valve 1-1/2 inch NPT. 7.2 One (1) Strainer, complete with a 30 mesh basket. 7.3 One (1) Inlet Flow Sight Indicator. 7.4 One (1) Positive Displacement, Inlet Pump, with mechanical seal. The pump shall be rated at 10% approximate higher flow than discharge pump. It shall be direct driven by a 1.5 kw, 1800 RPM TEFC electric motor. 7.5 One (1) Inlet Pump Relief Valve. 7.6 One (1) 96 kw Electric Inlet Oil Heater. The heater shall contain six, 16 kw heater elements, which shall have a watt density not greater than 1.7 W/cm 2. The heater shall be capable of increasing the oil temperature 30 o C in a single pass. The heater elements shall be controlled in two banks by contactors. Fuses shall be used for over current protection of each bank of heater elements One (1) Flow Switch, which shall be interlocked with the heater and shall require flow prior to energizing heaters One (1) Indicating Temperature Controller, which shall be used to control the electric heating elements to maintain the desired oil temperature. The controller shall be panel mounted. The temperature controllers, on deviation from the set point, activates the heater contactors through a series of time delay relays, which energize the required number of heating elements, raising the oil temperature to the set point. The digital controller set point is adjustable by a single adjusting button, thereby changing the set point on all elements simultaneously. The heater controller is designed to drop out the heating load on loss of power or oil flow. On resumption of power or flow, the controller resumes function and begins to energize banks of heating elements as required through the time delay relays. 4

5 The heater element banks are energized individually at timed intervals to prevent an overload on the power supply to the system. 7.8 One (1) Degassification Chamber. The illuminated chamber shall have a viewing port and a hinged service door. 7.9 One (1) Float Actuated Level Control Valve. The valve is actuated by a float mechanism in the degassification chamber to maintain the desired oil level. The level control valve is fully modulating and will maintain an inlet flow equal to the capacity of the discharge pump One Vacuum Gauge, 0-50 Torr range, to indicate the vacuum in the processing chamber One (1) Pressure Gauge, which is used to monitor pressure drop across the degassification accelerator elements, thus showing the need to replace the elements One (1) Foam Detector, which shall be activated on the appearance of excessive foam One (1) Solenoid Operated Valve to break vacuum on appearance of foam. The valve shall be operated by the Foam Detector. The inlet pump shall be stopped on appearance of, or persistent foaming condition One (1) Degassification Header, which shall contain chemically inert accelerator degassing elements One (1) High Level Detector. This level switch shall stop the inlet pump to prevent flooding and is a back-up for the flow control valve Float Actuated Level Control Valve One (1) Low Level Switch shall be interlocked with the discharge pump to prevent it from operating unless sufficient oil head is present One (1) Positive Displacement Discharge Pump with double mechanical seals. The pump shall have a rating of 6,000 litres/hour and shall be belt driven by a 1.1 kw, 1200 RPM, TEFC electric motor One (1) Discharge Pump Relief Valve Two (2) Sampling Cocks shall be provided, one for the incoming oil and one for processed oil, as shown on the Flow Diagram One (1) Outlet Flow Sight Indicator 7.22 One (1) Discharge Ball Valve 1-1/2 inch NPT One (1) Manual Recirculation Ball Valves One (1) System Relief Valve One (1) Enervac Model E858B-1-EP-718-1/2A2 Oil Filter to be installed after the outlet pump. The Afterfilter is furnished with replaceable pleated paper elements with a micron selectivity of 0.5 microns and a filtration efficiency of 98%. Standard filter units are of steel construction and complete with manual drain valve and pressure gauges to monitor differential pressure. 5

6 7.27 Free displacement of vacuum package 300 m 3 /hr (50Hz). Ultimate vacuum level: 0.08 mbar All necessary pressure gauges and valves as shown on the Flow Diagram shall be provided to complete system. Suitable flexible connections shall also be provided in the piping to minimize vibration A NEMA 12 Control Cabinet shall be provided, which shall contain all necessary control items required for the system. All motors shall be provided with magnetic starters for full voltage, across-the-line starting. Each motor shall have sufficient overload protection. Fuses shall be provided with each motor starter The following instruments shall be mounted on the control box: Temperature Controller All other gauges shall be locally mounted The following conditions shall have audible and visual alarms: High Foam/High Level Low Oil Level 7.33 Electrical System 7.34 Piping All components shall be suitable for 380 Volt, 3 Phase, 50 Hertz power supply. One (1) dry-type 500 VA transformer shall be supplied for control circuits. All piping shall be carbon steel, sized for the designed flow, braced and supported to prevent vibration. Piping will be welded construction when possible, to minimize leaks. Special vacuum tight welded 'O' ring unions and pipe flanges shall be provided to allow removal of components for maintenance, when necessary. 8 OPTIONAL VOLTAGE - (INCLUDED) Option 38 is included, 380 Volt, 3 Phase, 50 Hertz power supply. 9 PRE-FILTER OPTION OPTION P - (SEE QUOTATION) The Pre-filter is furnished with replaceable pleated paper elements with a micron selectivity of 5 microns and a filtration efficiency of 98%. Standard filter units are of steel construction and complete with manual drain valve and pressure gauges to monitor differential pressure. 10 FLOW METER OPTION OPTION M - (SEE QUOTATION) One (1) electronic in-line flow totaliser to provide a dependable and accurate totaling. The meter is furnished with digital menu display, for multi-choice flow units (lpm, Usgpm, IMPgpm), resettable main totaliser and daily totaliser. This display is registered in a choice of litres in 7 digits, and US Gallons, Imperial Gallons or cubic meters, all in 6 digits. 6

7 11 VACUUM BOOSTER OPTION VB - (NOT INCLUDED) One (1) Roots type vacuum blower, Kinney model KMBD-1600 or equivalent to improve the vacuum pump down time when vacuuming a transformer. The vacuum booster will have a free air displacement of 2,700 m 3 /hr. 12 HYGROMETER OPTION H - (SEE QUOTATION) One (1) Doble Domino Hygrometer can be supplied, digital readout for monitoring water content in the transformer oil, complete with probe, cable, sampling cell. Probe locations are as follows: H1 H2 Discharge or Inlet of Vacuum Oil Purifier Discharge or Inlet to Vacuum Oil Purifier in addition to H1 above. 13 ELECTRONIC VACUUM CONTROLLER OPTION - OPTION C1 - (NOT INCLUDED) C1 C2 C3 Electronic Vacuum Controller with one probe Electronic Vacuum Controller with two probes Electronic Vacuum Controller with three probes 14 CASTERS OPTION W - (NOT INCLUDED) Unit can be mounted on casters for in-plant mobility. Wheels would be 6" diameter polyolefin, 2 swivel, 2 stationary. 15 CIRCUIT BREAKERS OPTION B - (NOT INCLUDED) Circuit breakers can replace fuses for over current protection. 16 VITON GASKETS - OPTION V - (NOT INCLUDED) Viton gaskets and seals can be incorporated in the vacuum oil purifier replacing Buna-N material. 17 SPECIAL OPTIONS - OPTION X - (INCLUDED) Vacuum Oil Purifier will be mounted in a tag-a-long aluminum enclosed trailer with double open rear doors, side access doors, interior fluorescent lights, convenience receptacles, pintle hook type hitch. 7