Section 11365B DEWATERING CENTRIFUGES – ALFA LAVAL

Section 11365B

DEWATERING CENTRIFUGES – ALFA LAVAL

PART 1 - GENERAL

1.1 SCOPE

A. Work described in this section includes furnishing equipment, materials, tools, incidentals and services required for a complete and operable installation and performance testing of three (3) horizontal decanter dewatering centrifuges, and control panels, instrumentation, power panels, and related appurtenances. The centrifuges shall be Alfa Laval Decanter Model No. ALDEC G3-165.

B. All equipment shall be installed, adjusted, performance tested, and placed in operation in accordance with these Specifications, the manufacturer’s recommendations, and as shown on the Drawings.

C. Equipment to be provided for each centrifuge shall include, but not be limited to:

1. Solid bowl centrifuge.

2. Electric main motor drive.

3. Electric scroll motor drive.

4.

5. Variable frequency drives with harmonic mitigation.

6. Local centrifuge control panel with I/O components, operator interface terminal

(OIT) and PLC.

7. All necessary sensors and monitoring equipment.

8. All necessary vibration isolators.

9. Centrate and dewatered sludge chutes.

10. Density meters for feed connection.

11. All flexible connections except for electrical connections

12. All necessary bolts, anchor bolts, and hardware for centrifuge, lube oil unit, panels, and chutes.

13. Spare rotating assembly.

14. Spare parts and tools.

D. All equipment shall be fabricated, assembled, erected, and placed in proper operating condition in full conformity with the Drawings and Specifications, engineering data, and instructions provided herein. The dewatering centrifuge systems shall be specifically designed for the intended conditions of service and materials shall be suitable for service conditions described herein. All equipment shall be new and shall be designed, fabricated, and assembled in accordance with the best engineering and shop practices.

E. The installation of all materials and equipment supplied herein shall be completed by the CONTRACTOR. The Manufacturer shall be responsible for:

1. Design and fabrication of the centrifuge equipment and integrated control system.

2. Conduct all shop, field, and performance tests of equipment and integrated control system.

3. On-site advisory assistance during installation of all centrifuge related equipment.

4. Start-up and training services for all equipment supplied under this specification section.

5. Eight months of on-site operations and maintenance assistance services agreement (O&MASA), providing the service of a qualified centrifuge manufacturer representative to assist OCSD staff in process optimization and routine maintenance of the dewatering centrifuges. The manufacturer’s representative qualifications and role in the O&MASA is discussed in PART 3 – EXECUTION of this Specification section. The O&MASA shall extend for eight month period following acceptance of the Reliability Acceptance Test (RAT) as defined in Section 01810, Commissioning. The O&MASA parameters shall be as follows:

a. The O&MASA shall be on centrifuge manufacturer representative man-day basis and limited to 35 man-day worth of work in the eight month of the O&MASA duration.

b. The service shall be scheduled by OCSD’s staff and shall be one-half day minimum per visit and limited to a total of 35 man-days total.

c. CONTRACTOR to pay the manufacturer’s monthly invoices based on OCSD

approved time spent up to the 35 man-days.

d. Man-day is actual 8 hours worth of work in Plant 1 and does not include travel time. Traveling cost and living expenses for the manufacturer’s representative shall be included in the man-day unit cost.

e. This O&MASA does not cover or pay for any time spent on warranty issues throughout the warranty period.

f. Manufacture’s representative shall submit a report on the status and findings after each service visit.

6. Submittal of all shop drawings, certifications, Operation and Maintenance manuals, warranties, etc as required in these Specifications.

1.2 RELATED SECTIONS

A. The requirements of the following sections and divisions apply to the Work of this section. Other sections and divisions of the Specifications, not referenced below, shall also apply to the extent required for proper performance of this Work.

1. Division 01, Additional General Requirements

2. 01783, Vendor Equipment Manuals

3. 05505, Metal Fabrication

4. 09800, Protective Coating

5. 11005, Equipment: Basic Requirements

6. 11309, Progressing Cavity Pumps

7. 11121, Sludge Collection: Screw Conveyors

8. 11341, Grinders

9. 11369, Thickening Centrifuge

10. 16220, Electric Motors

11. 16418, Variable Frequency Drives Below 100 Horsepower

12. 16419, Variable Frequency Drives 100 hp and Above

13. 16442, Control Panels

14. 17405, Process Instrumentation and Control

15. 17410, Programming by Contractor

16. 17411, Programming by OCSD

1.3 DESIGN REQUIREMENTS AND PERFORMANCE

A. All equipment and appurtenances with the exception of the centrifuge control panels and motor controller cabinets shall be suitable for exposure to splash and spill conditions, and operation in continuous 95 percent relative humidity conditions and in ambient air temperatures from 40 to 104 degrees F.

B. Centrifuge control panels and motor controllers will be located in an electrical room provided with conditioned air.

C. The units shall be capable of continuous operation for 24 hours per day, seven days per week.

D. The centrifuges shall be capable of dewatering sludge having the following characteristics:

1. Sludge Type: Municipal.

2. Sludge Composition: Digested sludge that is a blend of primary sludge, waste activated sludge (WAS), trickling filter sludge and surface waste (Nocardia waste from aeration basins).

a. Primary sludge includes iron salts used for enhanced solids removal from primary clarifiers.

3. Percent of total dry solids contributed by each sludge stream (average):

a. Primary Sludge: 76 percent b. WAS: 19 percent

c. Trickling Filter Sludge: 4 percent d. Surface Waste: 1 percent

4. Feed solids concentration:

a. Start-Up Conditions

1) Average: 2.0 percent

2) Range: 1.7 percent to 2.3 percent

b. Long-Term Conditions (after centrifuge thickening is fully operational)

1) Average: 3.5 percent

2) Range: 3.0 percent to 4.0 percent

5. Feed sludge volatile solids fraction:

a. Average: 58 percent

b. Range: 53 percent - 63 percent

E. The plant sludge characteristics are highly variable. The Manufacturer recognizes the variability of the sludge and the equipment supplied shall be suitable and compatible with the Plant sludge under the range of sludge characteristics described in this Specification.

F. The centrifuges shall be optimized for dewatering with continuous addition of polymer as a conditioning chemical. In addition, the adjustable pond setting dams may require changing for optimum process capabilities.

G. A polymer chemical addition conditioning system is being provided by the CONTRACTOR for chemical conditioning of the raw solids prior to dewatering. The polymer system is based on using bulk liquid mannich or emulsion polymers. The centrifuge performance guarantee must be based on this type of system. The design parameters for the polymer system include:

1. Polymer Dosage Rate: 0 to 30 pounds (active polymer) per ton of dry solids.

2. Polymer feed pumps, including dilution water (per unit):

a. Capacity: 47 gpm

b. Secondary Dilution water: Industrial (potable water after a backflow preventer) or recycled water

3. Polymer Feed Concentration: 0.10 to 0.25 percent (including secondary dilution). H. Each centrifuge shall be capable of the following performance for a minimum 45-day

continuous RAT testing:

1. All requirements listed in Table 1.

Table 1. Minimum Performance Requirements

Performance Point	1	2	3	4
Feed Sludge Type	Digested	Digested	Digested	Digested
Operating Condition	Start-up Average	Start-up Maximum	Long-Term Average	Long-Term Maximum
Minimum Feed Concentration, percent TSS	1.7	1.7	3.0	3.0
Maximum Feed Concentration, percent TSS	2.3	2.3	4.0	4.0
Solids Throughputa, lb/hr	7,000	11,500	12,000	20,000
Hydraulic Throughput, gpm	600	1,000	600	1,000
Maximum polymer dosage, lb/ton	b	b	b	b
Minimum Capturec, percent	95	92	95	90
Thickened sludge solids content, percent TSS	32	30	30	25
Maximum energy requirementd, Hp/gpm	0.42	0.42	0.42	0.44
a. Based on raw suspended solids in raw feed only. b. Maximum polymer dosage = 4 lb/dt x percent VSS fraction/10 c. The percent solids capture shall be determined as follows: (QR)(SSR) - (QR + QP)(SSC) Capture rate (%) = (Q )(SS ) x 100 R R where: QR = flow rate of raw solids, gpm QP = flow rate of polymer (including dilution water) SSR = suspended solids content of raw solids feed, mg/l SSC = suspended solids content of centrate, mg/l d. Total centrifuge power used, measured at the centrifuge breakers divided by the measured sludge feed flow.

2. Noise to be below 92 dBA for all performance conditions and is not to be exceeded at any time during testing.

3. Vibration to be below 10 mm/sec RMS for all performance conditions and is not to be exceeded at any time during testing (horizontal, vertical, and axial).

4. For the duration of the test, dewatered solids concentration to be maintained above 25.

5. The minimum feed solids concentration to be maintained for the duration of the test is 1.7 percent.

6. During the duration of the test, the maximum polymer dose may not exceed 4.0 lb/dry ton for each 10 percent increase in volatile solids fraction (e.g., 23.6 lb per dry ton if volatile solids fraction is 59 percent)

7. The type of polymer used during the testing shall be jointly agreed to by the Manufacturer and the ENGINEER. The polymer shall be readily available in Southern California and shall have a unit cost per pound of active polymer that is competitive with the unit cost of other polymers used for municipal centrifuge dewatering applications in Southern California.

8. Compliance with the thickened sludge solids concentration, solids capture, and polymer dosage is required for the range of feed solids concentrations above (including minimum and maximum values).

1.4 SUBMITTALS

A. Submit drawings and equipment data in accordance with Specification section

11005, Equipment: Basic Requirements, and the following. All documents to be in English or with all captions in foreign languages translated into English. Documents with any un-translated captions will be automatically rejected. Submit all required data for design of support structures, piping system, electrical system, and instrumentation as per the time frame defined in Division 1.

1. Equipment Data Sheet and detailed shop drawings for all equipment supplied, providing dimensions, gross and net weight, and minimum clearances.

2. G-volume calculations; provide calculations based 1) bowl only and 2) bowl and cone.

3. Design Data for main drive and bearings.

4. Materials of Construction/Abrasion Protection Features.

5. Anchor Bolts Calculations

6. Vibration Isolator Detail

7. Standard Instruction Manual.

8. Detailed Centrifuge Installation Instructions and details.

9. Part lists and bills of materials of all equipment.

10. Proposed test procedures and test reports for:

a. Laboratory testing of abrasion resistant materials. b. Witness shop tests of centrifuges.

c. Field tests of centrifuges.

d. Performance tests of centrifuges.

11. Lubrication and Preventive Maintenance Schedule.

12. Equipment Shipment, Storage, Unloading, and Handling Instructions.

13. Field wiring diagrams and outline drawings showing field wiring, requirements for conduit locations, stub-ups, and physical sizing information. Physical location of the electrical devices on the centrifuge and its ancillary equipment should be shown on the Drawings, which shall be made specifically for this project. Wiring instructions shall be in English, NEMA and ANSI standards shall be used for all electrical connections.

14. Spare Parts and Special Tools List.

15. Surface Preparation and Painting Details.

16. Sample Factory Test Report.

17. Certification of calibration for the shop test instruments and field test instruments.

18. Discharge Connection Details.

19. Electric Motor Submittal in accordance with Specification section 16220, Electric

Motors.

20. Control Panel Engineering Submittal per the requirements of Specification section 17405, Process Instrumentation and Control.

21. Sequence of Operations.

22. Vibration Monitor Details.

23. Variable Frequency Drive Submittal in accordance with Specification section

16419, Variable Frequency Drives 100 hp and Above.

24. Installation Plan and Performance test procedures.

25. Process & Instrumentation Diagrams, electrical diagrams, elementary diagrams, and control loop drawings.

26. Warranties for the Work performed under this Contract and, in particular, the wear and performance guarantees.

27. Evidence of welder’s qualifications.

28. Training lesson plan.

29. Test procedures for the Control panels, VFDs, Motors and Centrifuge for different phases, including FDT, ORT 1, 2, & 3, FAT and RAT per Section 01810, Commissioning and 17405, Process Instrumentation and Control.

30. Test and gate reports as required in Section 01810, Commissioning.

31. Programming submittals as required in Section 17410, Programming.

B. For equipment or material for which specific tests are not requested in this Specification, the Manufacturer’s standard quality control test reports shall be submitted. The tests shall have been performed not longer than three (3) years before the date of submittal of the reports for acceptance.

C. Six (6) sets of operation and maintenance manuals and final As-built Drawings (Record Drawings) to be provided at the completion of the job and in accordance with Specification section 01783, Vendor Equipment Manuals. One (1) CD-ROM copy of the O&M manual and drawings shall be provided in Adobe Acrobat format.

1.5 QUALITY ASSURANCE

A. The centrifuge shall be the product of manufacturers regularly engaged in the design, fabrication, service, and repair of high-speed centrifuges. The centrifuge shall be manufactured utilizing the latest manufacturing machine tool technology. The bowl, scroll, rotating assembly, and frame shall be manufactured to precise tolerances and shall with readily interchangeable with those components of currently installed models.

B. Certificate of Compliance: The manufacturer shall warrant that the centrifuge shall be manufactured in accordance with the Specifications.

C. All manufacturing facilities shall be ISO 9001 certified for quality assurance in the design, development, production, installation, and servicing of machines and installations for mechanical separations.

D. The centrifuge manufacturer must have experience manufacturing decanter-type dewatering centrifuges with bowl diameters of 30 inches or larger and operating g-force in excess of 2,500 xg. The referenced installations must demonstrate a history of reliability and service consistent with the OCSD’s expectations, specifically related to dewatered solids concentration control. Provide a list of a minimum of four (4) such installations with description, solids processing data, contact names, addresses and telephone numbers with the bid proposal. Failure of a referenced installation to meet these criteria for performance, reliability, and service will be grounds for excluding a manufacturer as an acceptable supplier.

E. The centrifuge and ancillary equipment shall be designed and manufactured in accordance with the following listed Standards and Specifications, including applicable addenda in effect as of the date of bid submission. They shall be considered an integral part of this specification and shall govern the design, fabrication, testing and inspection of equipment, except as otherwise shown or specified herein:

1. American Gear Manufacturers Association (AGMA)

2. American Welding Society (AWS) D1.1-82, Structural Welding, and ASME Boilers and Pressure Vessels

3. Deutsches Institute for Normal Standards (DIN), if applicable

4. Verein Deutsche Inginieure (VDI), if applicable

5. National Electrical Manufacturers Association (NEMA)

6. Anti-Friction Bearing Manufacturers Association (AFBMA)

7. American National Standards Institute (ANSI)

8. National Fire Protection Association (NFPA)

9. Joint Industrial Council (JIC)

10. American Society of Mechanical Engineers (ASME)

11. Underwriters Laboratory (UL)

12. Institute of Electrical and Electronics Engineers (IEEE)

13. American Society of Testing Materials (ASTM)

14. American Institute of Steel Construction (AISC)

F. Proof of qualification of the technicians that the centrifuge manufacturer shall provide for the installation, testing, and startup of the centrifuge assemblies, shall be submitted to the Engineer for acceptance before the installation is initiated. Welders shall have passed AWS qualification tests, or equivalent tests in Countries other than the United States such as DIN, within the last 12 months prior to the time they are employed. Evidence of compliance must be submitted to the ENGINEER.

G. The manufacturer shall own and operate at least one full service repair facility in the United States, capable of performing all repairs on all portions of the rotating assembly. The repair facility shall be capable of performing balancing of all rotating components at the full nameplate rpm of the rotating assembly. The Manufacturer shall employ a minimum total of 20 Field Service and Process personnel dedicated to centrifuge service and shall maintain a United States based spare parts inventory in excess of five (5) million dollars.

1.6 EQUIPMENT GUARANTEES

A. Equipment Wear: The Manufacturer shall furnish a guarantee for equipment wear based upon 10,000 hours of operation for abrasion resistant protection system. The equipment shall not exhibit a wear greater than 20 millimeter after 10,000 hours of operation. Warranty certificates in English, or accompanied by certified translation, shall be submitted as part of the shop drawing submittal. Manufacturer shall provide service and materials to disassemble and inspect the supplied machine after 10,000 hours of operation or 24 months, whichever comes first. If inspection reveals greater wear than guaranteed or damage of any sort, Manufacturer shall repair as necessary.

B. The scrolls will bear a warranty against faulty workmanship and design for 60 months starting at the time of delivery. Normal wear and tear is excluded from the scroll warranty.

PART 2 - PRODUCTS

2.1 GENERAL DESCRIPTION

A. The centrifuge shall be Alfa-Laval Series ALDEC G3-165 Decanter. The centrifuge shall be a solid bowl, horizontal, continuous feed, scroll type unit. The centrifuge equipment shall be designed and built to operate continuously or intermittently. The centrifuge shall be designed for counter-current flow characteristics such that no centrate tubes are required. The bowl/scroll design shall utilize the conical section for optimal dewatering of the dewatered solids. The dewatering centrifuge shall be able to separate at a G-force between 2,000 and 2,700, corresponding to a speed range between 1,200 –

2,150 rpm

B. Individual parts shall be identical in design and workmanship and shall be interchangeable with existing units

C. The centrifuge shall have a 316SS nameplate securely fastened to the base or other visible location. The nameplate shall indicate the manufacturer’s name, date manufactured and installed, model number and serial number. Minimum size of the nameplate shall be 6 inch x 12 inch.

D. The centrifuge manufacturer shall be responsible for providing a complete centrifuge system, as described herein. The equipment shall be installed by the project CONTRACTOR who shall be responsible for off-loading the equipment, providing any temporary storage, and installing the equipment in place. Installation shall include mounting the unit, piping the unit, providing power to the panels and all inter-connected wiring and piping required between the various components.

E. Individual parts shall be manufactured to standard sizes and gauges. Components of the centrifuge shall be designed for the stresses, which may occur during fabrication, shipping, erection or maintenance. Materials shall be suitable for service conditions and as described herein. The equipment shall be installed in a manner that prevents movement between interconnecting structures, pipes, conduit, etc.

F. The dewatering centrifuge and its components shall have the following nominal dimensions:

1. Rotating assembly 234 inches long x 43 inches wide-including gearbox.

2. Frame assembly 256 inches long x 81 inches wide.

3. Motor assembly Main Drive 52 inches long, Backdrive 41inches long.

4. Overall centrifuge height of 89 inches.

5. Overall centrifuge length of 326 inches.

6. Overall centrifuge width of 81 inches.

7. All of the above components shall be within the lifting capacity of a 20-ton bridge crane.

2.2 MATERIALS, FABRICATION, AND FINISHING

A. All wetted parts of the centrifuge rotating assembly shall be a minimum of 316 stainless steel except for the “O” rings, seals, and abrasion-resistant material. “O” rings shall be Viton rubber, lip type seals shall be Viton. The feed tube, sludge feed pipe, solids discharge, and liquid discharge compartments shall be constructed of 316 stainless steel. The frame and casing shall be fabricated of carbon steel. All protective guards shall be constructed of painted carbon steel. Fiberglass reinforced plastic covers shall not be allowed.

B. Design of all support structures and bracing shall be in accordance with AISC

standard.

C. Structural steel shall conform to ASTM Specification A36. D. Welding shall conform to AWS Structural Code D1.1-82,

E. All carbon steel surfaces shall be protected by a paint system specifically designed to resist chipping, cracking, and lye or acid corrosion. The paint shall consist of a two-part epoxy metal primer and a polyurethane finish coat

F. All bolts, anchor bolts, hangers, fasteners, and hardware for the centrifuge and associated equipment shall be AISI Type 316 stainless steel

2.3 BOWL

A. The bowl shall be manufactured from centrifugal castings of type duplex stainless steel, and designed to operate at a maximum of 2,700 x G at the inside bowl wall diameter based on 2,200 rpm for maximum process flexibility and reliability and to withstand all centrifugal forces encountered at design operating speeds with adequate safety factors.

B. Nominal bowl thickness of the cylindrical and conical sections will be a minimum of

0.95 inches. The front and rear bowl hubs shall have a minimum nominal thickness of

3.15 inches and 2.9 inches respectively. The centrifuge bowl shall be supported by roller bearings mounted in pillow blocks and fitted for convenient external lubrication. Main bearings shall have a calculated life of at least 100,000 hours at standard operating speeds in accordance with DIN ISO 281 requirements.

C. Flow through the centrifuge shall be counter current such that there are no centrate tubes to maintain. Pond depth shall be readily adjustable via power plate weirs located at the large diameter end of the bowl and shall not require removing the rotating assembly from the frame. Solids shall be discharged at the small diameter end of the bowl.

D. Power tubes weirs shall be utilized for maximum energy efficiency. The power tubes weirs will direct the centrate in the opposite direction of the bowl rotation to provide additional for bowl rotation.

2.4 SCROLL CONVEYOR

A. The centrifuge shall include a duplex stainless steel hub for the horizontal conical- cylindrical scroll conveyor. The conveyor shall be equipped with duplex stainless steel flights on the conical section and 316 stainless steel helical flights on the horizontal section, independently mounted concentrically within the bowl. The scroll shall utilize a differential speed to convey solids from the cylindrical section to the conical section and out of the bowl with a minimum disturbance to the pool, and to the maximum advantage of the variable speed back drive described in this section. The scroll conveyor shall be supported on grease lubricated anti-friction ball or roller bearings sealed from process contamination.

B. The edge and the face of the conveyor flights shall be protected by a series of welded on sintered tungsten carbide tiles, as described in the abrasion protection section. The tiles shall extend from the feed zone area to the point of solids discharge.

C. The scroll conveyor shall be designed such that the feed leaving the feed tube is accelerated in a feed zone. The feed material leaving the conveyor hub will pass through tungsten carbide hard surfaced feed nozzles. The feed shall be evenly discharged into the bowl. The flights on the conveyor shall be designed with flow equalization windows to allow axial flow of centrate for minimum disturbance to the pool and maximum settling of fine particles.

2.5 GEAR BOX

A. The centrifuge shall be equipped with a multistage planetary gearbox to provide control of the differential speed between the centrifuge bowl and conveyor.

B. The gear unit shall have a torque capacity of 100 kNm.

C. Lubricating oil is self-contained and shall be high performance gear oil.

D. The gearbox shall be independently balanced from the centrifuge, and interchangeable. Each gear unit should be protected from damage due to high torque overload.

E. A thermal overload protection device shall not be considered as providing for sufficient protection for the gear un

F. Hydraulic drive units or externally cooled gearboxes will not be acceptable.

2.6 BEARINGS

A. The centrifuges shall be designed so that the entire rotating assembly is supported by two main pillow block bearings. Main bearing shall be grease lubricated type bearing. Bearings for the scroll shall be permanently grease lubricated with lithium-saponified grease. The bearings shall have a minimum L10 lifetime rating of 100,000 hours.

B. The main bearings shall be equipped with RTD type temperature sensors which monitor the temperature of the bearing race directly. The sensors shall be platinum ohm resistance type PT100. Monitoring of the oil temperature shall not be an acceptable method of protection for the bearings.

2.7 FRAME AND CASING

A. The rotating assembly and bearings of the centrifuge will rest on a steel frame.

B. The frame and casing shall be supplied on a modular frame and shall be fabricated from structural tubular steel. The modular frame shall support both the drive motor and back drive and shall provide a minimum clearance of 28 inches from floor to the casing solids and liquid discharge openings. The casing assembly will be provided with a 316 stainless steel upper casing, specifically designed for rigidity and noise reduction. Fiberglass upper casing shall not be allowed to maintain safety. The case shall be designed to act as a protective guard and to provide a complete enclosure for odor containment. The casing top shall be gasketed.

C. The bottom of the casing shall be fitted with a flexible splashguard for cake discharge. The liquid discharge shall be fitted with a flexible connection fitted with a flanged connection for the centrate. The lower casing shall be fabricated from carbon steel with stainless steel cladding on the wetted parts.

D. The case top shall be hinged (left or right sided) or removable bolted in place, and be equipped with a cover switch so the centrifuge cannot be started when the cover is open.

E. Vibration isolators for the drive motor and back drive shall be supplied as required. Conduit boxes for all centrifuge mounted switches, except those specifically related to the main drive motor, shall be mounted on the base.

2.8 DRIVE SYSTEMS

A. Main Drive System:

1. The bowl drive system shall consist of a 350 hp electric motor and a belt drive system. The belt drive system shall consist of individual V-belts to provide full load capacity and to withstand the full starting torque of the system with a variable frequency drive (VFD). Refer to Section 16419, Variable Frequency Drives 100 hp and Above, for VFD requirements and manufacturers.

2. The main motor shall be a squirrel cage induction motor and shall be provided with thermal protection. The motor shall have copper windings and be of a high thermal capacity design for operation of 460 V / 3Ø / 60 Hz power. The motor temperature shall not exceed 130 degrees C at 90 percent nameplate voltage. The noise level shall not exceed 85 dbA sound pressure measured at 3 feet from the motor in all directions. For additional motor requirements, refer to Section 16220, Electric Motors.

3. With the motor at ambient temperature, it shall be capable of making two (2) complete starts in succession with coasting to rest between starts. The motor shall also be capable of at least one restart within one hour after any shutdown. The motor bearings shall be grease lubricated, ball or roller anti-friction type of standard manufacture. The bearings shall be conservatively designed to withstand all stresses of the service specified.

B. Back Drive System:

1. Each centrifuge shall be furnished with a complete direct drive back drive system to control differential speed between the conveyor and the bowl. The back drive shall provide an infinitely adjustable differential speed variation over its range of operation.

2. Each back drive system shall be furnished with all the required instrumentation and electrical controls to meet the operating requirements of this specification and as indicated on the drawings.

3. The differential motor is a 75 hp 1800 RPM motor mounted on the motor frame.

4. The torque overload protection feature functions by reading the amperage draw of the differential motor and tripping an alarm upon reaching a two stage set point. The first stage set point will signal the control system to shut off the sludge feed and begin flushing the centrifuge. The second stage set point shall shut down the main motor.

2.9 ABRASION PROTECTION

A. In order to minimize wear due to abrasive materials in the feed, replaceable hard surfacing shall be provided at all points where the abrasive action of the sludge will cause wear on the metal parts of the centrifuge. The following shall be considered a minimum degree of hard surfacing required.

1. Bowl Wall: The bowl wall and conical extensions shall be protected with minimum of eight (8) welded ribs designed to trap a protective layer of solids between the bowl wall and the conveyor.

2. Conveyor Feed Ports: The conveyor feed ports shall be protected from abrasion by field replaceable solid sintered tungsten carbide elements.

3. Solids Discharge Ports: The solids discharge ports shall be protected from abrasion by field replaceable tungsten carbide wear saddles.

4. Solids Discharge Casing: A replaceable stainless steel or urethane insert shall protect the solids discharge casing.

5. Scroll Conveyor Flights: The edge and face of the conveyor flights shall be protected against abrasion from the solids by a series of welded-on sintered tungsten carbide tile assemblies from two wraps beyond the feed zone through the solids discharge end. Each tile assembly shall be weight correct, and consist of a solid sintered tungsten carbide wear part braised to a stainless steel back-up holder. Spray hard surfacing applied to a back-up plate will not be allowed. Each assembly shall be individually replaceable and shall include the ability to monitor wear by means of visual inspection. The tile assemblies must extend 0.75 inches beyond the radial edge of the conveyor flight. The remaining scroll conveyor edge and face shall be protected from abrasion by flame sprayed hard surfacing containing a minimum

40 percent tungsten carbide particle. Stellite or ceramic hard surfaced tiles are not acceptable.

2.10 NOISE AND VIBRATION

A. The centrifuge shall be equipped with noise suppression devices of an energy efficient design, such that the average noise level measured at three (3) feet around the periphery of the complete centrifuge assembly shall not exceed the 92 dBA when tested at the manufacturing facility without feed and with the inlet and discharge closed.

B. The centrifuge shall be equipped with accelerometer type vibration monitors located on each pillow block to protect against excessive vibration. The monitor shall be interlocked with the controls to shut down the centrifuge if excessive vibration is sensed. The monitors shall provide an analog output signal proportional to the vibration magnitude for display and monitoring at the HMI operator interface.

C. The centrifuge, when running without feed, shall be measured for vibration at the manufacturing facility. The vibration shall be less than or equal to 10.0 mm/s RMS when measured at the pillow blocks under dry shop conditions.

D. Vibration Isolators:

1. The centrifuge shall be mounted on rubber-type vibration isolators. The number and vibration constant of the isolator shall be as recommended by the manufacturer for the load and impact resulting from the operation of the centrifuge provided.

2. There shall be no rigid connections at the feed tube, vents, solids discharge, liquid discharge or other components whatsoever to the machine, thus preventing transmission of vibration to structure, piping and appurtenant equipment.

E. Flexible Connectors:

1. To insure a quiet installation, flexible connectors shall be provided to isolate the centrifuge from the building structure. Flexible connectors include the solids discharge splashguard, flexible feed connections, flexible centrate connection, and flexible polymer connection for the feed tube. These items are to be supplied by the centrifuge manufacturer:

a. The flexible solids splashguard shall be constructed of 1/8 inch black neoprene. All hardware shall be constructed of type 316 stainless steel.

b. The flexible feed connection shall be constructed of black neoprene hose with a hose clamp fitting mounted on a 150 lb. flange connection.

c. The flexible centrate connection shall be 8 inches long and constructed of black neoprene with a flanged connection.

d. The flexible polymer connection shall be constructed of hose with a custom connector on the centrifuge feed tube side and a one and a half inch(1½”) polymer connection to process piping.

2. Due to local conditions, flexible connectors for the main drive motor, scroll drive motor and centrifuge junction boxes must be furnished by the CONTRACTOR, such that all local electrical codes are met.

F. Centrate and Solids Chutes:

1. The manufacturer shall supply chutes to be mounted below the discharge of the frame, as shown on the Drawings All chutes to be fabricated from 1/8” thick 316 L stainless steel plate. Chutes and supports to confirm to Section 05505, Metal Fabrications.

G. Inlet Manifold:

1. The manufacturer shall supply the inlet manifold for each centrifuge assembly, which shall combine and direct into the centrifuge the sludge feed, polymer feed, and wash water feed. Final arrangement of the inlet manifold should match the process drawings provided. The manifold shall be manufactured of 316 stainless steel.

H. Vibration Monitoring:

1. The centrifuge shall be equipped with vibration monitoring system consisting of an accelerometer, digital display, 4-20 mA output, alert alarm and danger alarm.

2. Upon reaching an alert (stage 1) alarm, the control system will issue a warning alarm at the panel. Upon reaching a danger alarm (stage 2), the control system will shut down the centrifuge in a controlled shut down sequence.

3. The vibration monitor shall be equipped with the following outputs to the centrifuge PLC:

a. Analog Input (AI) to the PLC:

1) Liquid side vertical vibration.

2) Liquid side horizontal vibration.

3) Solids side vertical vibration.

4) Solids side horizontal vibration.

4. The vibration monitor shall be Bentley Nevada 3500 Series, Or Equal.

2.11 LUBRICATION

A. All bearings on the centrifuge shall be grease lubricated through suitably located fittings.

B. Bearing temperature monitors will be provided on each main bearing pillow block, with an analog output signal sent to the data management system (DMS) for display and monitoring at the HMI operator interface.

C. The gearbox lubrication shall be self-contained and consist of high performance gear oil.

2.12 GUARDS

A. Guards for all gearboxes and belt drives shall be a minimum 0.11 inch 316 stainless steel and shall be designed to OSHA standards. Completely enclose the entire belt drive system and construct to minimize vibration. Guards manufactured from fiberglass reinforced plastic shall not be allowed.

2.13 ANCHOR BOLTS

A. Anchor bolts shall be sized by the centrifuge manufacturer and supplied to the installing contractor and be constructed of 316 stainless steel.

B. CONTRACTOR shall install anchor bolts.

C. Provide structural calculations for the required force level for each component.

1. Use seismic design criteria listed in Section 01332.

2. Provide summary of loads to each anchor.

3. Structural calculations shall be signed and sealed by a professional Civil Engineer registered in the State of California.

4. Number calculation pages.

2.14 CENTRIFUGE BOWL TRUCK

A. The manufacturer shall supply one (1) cart for moving the rotating assembly and scroll within the Thickening and Dewatering Facility.

2.15 PAINTING

A. This section includes the protective coating of all indicated surfaces including surface preparation, pretreatment, coating application (including primer, intermediate and finish), protection of surfaces not to be coated, and all appurtenant Work.

B. The following surfaces shall not be protective coated hereunder unless indicated.

1. Stainless steel.

2. Machined surfaces.

3. Grease fittings.

4. Glass.

5. Equipment nameplates.

C. Coating system must comply with state and local regulations.

D. Definitions: The terms "paint," "coatings," and "finishes" as used herein, shall mean surface treatments, emulsions, enamels, paints, epoxy resins, and all other protective coatings, except galvanizing or anodizing, whether used as a pretreatment, primer, intermediate coat, or finish coat. The term "DFT" means minimum dry film thickness.

E. The manufacturer shall use coating materials suitable for the intended use and recommended by the coating manufacturer for the intended service.

F. Protective Coating Materials: Products shall be standard products produced by recognized manufacturers who are regularly engaged in production of such materials for essentially identical service conditions.

G. Coating System - Inorganic Zinc/Polyurethane: The inorganic zinc primer shall be a water or solvent based, self-curing, zinc silicate 2-component inorganic coating which contains at least 85 percent of metallic zinc by weight in the dried film, and is recommended by the coating manufacturer as a primer for this system. The intermediate coat shall be a high-build two component epoxy with a solids content of at least 70 percent by volume. Finish coats shall be a 2-component aliphatic acrylic or polyester polyurethane coating material that provides superior color and gloss retention, resistance to chemical fumes and severe weathering, and a minimum solids content of 58 percent by volume.

1. Prime coat (DFT = 2 mil), Dimetcote 12, Carbo Zinc 11 HS, Tnemec 90-92, Or

Equal.

2. Intermediate coat (DFT = 4 mils), Ameron 400, Carboline 893, Tnemec 104, Or

Equal.

3. Finish coats (one or more, DFT = 3 mils), Amershield, Carboline D134 HS, Tnemec 73, Or Equal.

4. Total system DFT = 9 mils.

5. Intermediate coat shall be applied in excess of 4 mils DFT or in more than one coat as necessary to completely cover the inorganic zinc primer and prevent application bubbling of the polyurethane finish coat.

6. More than one finish coat shall be applied as necessary to produce a finish with uniform color and texture.

7. Coating manufacturers and paint numbers are listed to show type and quality of coatings.

2.16 MISCELLANEOUS

A. Seal water, cooling water, sample gauges, and valves to be supplied by the CONTRACTOR as indicated on the process and plumbing drawings in the construction bid documents.

2.17 SPARE ROTATING ASSEMBLY

A. Provide one spare rotating assembly for the dewatering centrifuges.

B. The spare rotating assembly shall be manufactured and tested in the same manner as the rotating assemblies for the installed unit. The rotating assembly shall be factory tested in one of the dewatering centrifuges supplied for this project.

C. The spare rotating assembly will be stored on the main centrifuge floor at Plant 1. CONTRACTOR shall supply stationary oak cradles or similar support structures to reliably support the entire rotating assembly. Support system shall allow access to the rotating assembly for all maintenance activities including periodic rotation of the equipment.

2.18 STANDARD TOOLS, SPARE PARTS, AND ACCESSORIES

A. Manufacturer shall supply all tools, (supplies, spare parts, and special equipment as described in Schedule 11365-1 and below.

B. Provide one year’s supply of all lubricating oils and greases recommended by the manufacturers, and as per accepted shop drawings, for all components for a continuously operating machine.

C. Spare parts shall be identical and interchangeable with the original parts and marked with their respective part numbers.

Schedule 11365-1 Dewatering Centrifuge Tools, Supplies, Spare Parts and Special Equipment for Westfalia Unit
	Minimum Requirements
Item No.	Description of Item	Quantity
	Tools
1	Set of Special Tools for Centrifuge Maintenance	1
2	Bowl Lifter	1
3	Conveyor Extracting Tools	1
4	Torque Wrench	1
5	Bearing Puller	1
6	Pillow Block Lifting Eyebolts	1
7	Pillow Block Bearing Remover	1
8	Pillow Block Dowell Pin Remover	1
9	Seal Holder Puller	1
10	Gearbox Adaptor Removal Aid Kit	1
	Supplies
11	One Years Supply of Centrifuge Lubricants	1
	Spare Parts
	Grease Lubrication System
12	Grease Lubrication System Complete	1
	Wear Protection
13	Set of Solids Discharge Bushings	3
14	Set of Solids Discharge housing Wear Plates	3
	Bearings
15	Set of Main Bearing	2
16	Set of Scroll Conveyor Bearing	2
17	Set of Miscellaneous Bearings	1
	Gaskets
18	Set of Gaskets (rotating assembly)	3
19	Set of Gaskets (frame)	3
	Miscellaneous
20	Set of V-belts	2
21	Set of Nuts/Bolt/Washers(10 of each size)	1
22	Scroll Conveyor Tiles	40

Sludge Dewatering and Odor Control at Plant 1 DEWATERING CENTRIFUGES -

2.19 INSTRUMENTATION AND CONTROLS A. General:

1. The centrifuge control system shall have a PLC with an Operator Interface Terminal (OIT). The control system shall be designed to work in manual and automatic modes. Should a disruption occur, the centrifuge monitoring system shall indicate the cause with a first out sequence and define the fault.

B. Centrifuge Control Panel:

1. NEMA12 single-door free-standing enclosure. The Centrifuge Control Panel design shall be as indicated in the instrumentation drawings. A Modicon Quantum PLC shall be supplied and programmed to operate the necessary sequences. The PLC supplied shall be as specified in Section 17405, Process Instrumentation and Control, and shall be programmed per OCSD standards and as defined in Section

17410, Programming by Contractor. Included shall be a centrifuge automatic torque control module that shall maintain process optimization within adjustable preset limitations and operate in differential speed and torque modes. Included in the front door shall be an E-stop pushbutton, an alarm acknowledge pushbutton, an alarm silence pushbutton, and alarm horn. All pushbuttons and pilot lights shall be water tight and corrosion resistant. The OIT shall be utilized for major operational adjustments. The panel will house the PLC and industrial hardware components. All field wiring labeling shall be per OCSD standards.

2. All components in the control panel shall be completely factory wired. All external control connection points shall terminate on a terminal strip. There shall be a minimum of 10 percent spare terminal connections supplied. The PLC shall be capable of interfacing via Ethernet, to the Plant SCADA system. The OIT shall display Centrifuge monitoring and control information including alarms and events with actual time and date.

3. If the PLC supplied is not a Modicon Quantum, or is not programmed per OCSD programming standards then the manufacturer shall provide a Gateway PLC as shown on the Drawings. Design and dimensions of the Gateway PLC shall be as shown on the Drawings, without exceptions. The Gateway PLC shall be programmed to provide Centrifuge related I/O necessary to develop screens at OCSD’s SCADA system that are identical to the Centrifuge OIT screens. The gateway PLC shall be programmed per OCSD programming standards and per the requirements of Section

17410, Programming by Contractor. Programming and use of memory registers shall be in compliance with guidelines setup by OCSD’s programming staff. Coordination assistance and copies of the OCSD’s software programming guides shall be obtained from OCSD by the manufacturer after the effective date of the Notice to Proceed.

C. Centrifuge Power Equipment:

1. Separate VFDs shall be provided for each of the main drive and scroll drive motors.

D. Field Instruments:

1. Vibration Monitoring System (Located in the centrifuge control panel)

a. Function: Vibration monitoring of rotating machinery b. Style: 19 inches EIA rack

c. Power Input to Rack: 120 VAC. 60 Hz.

d. Power Supply Module: Shall produce output to transducers: : 0 - 24 VDC +/-

2.5 percent ; transducer voltages shall be overload protected per channel on the individual monitor circuit boards.

e. Temperature Range: Operating: +32 to +150 degrees F; Storage: -40 to

+185 degrees F.

f. Relative Humidity: 95 percent max. non-condensing. g. Rack Housing Rating: Weatherproof.

h. System Monitor Module: Shall monitor all rack power supply voltages. Shall include front panel push buttons to adjust alarm set points for any monitor on the rack; alarm reset switch. Terminals shall be available in the rear signal input module for connection of contact closures inputs from remote locations.

i. There shall be two alarms (alert and danger) 1 per channel for each type of module. Dual epoxy-sealed relay modules sha1l be furnished with each module. All relays shall include arc suppressors. Contact rating shall be 5A @ 120 VAC. Contact life shall be 10,000 cycles minimum at rated load.

j. Vibration Monitoring Modules: Refer to Paragraph 2.10.H above.

2. Frequency Current Converter:

a. Centrifuge bowl and speed sensors shall be provided to monitor speed. The control module shall transmit a current output proportional to an input frequency.

b. Key features shall include:

1) 120 VAC supply voltage.

2) Adjustable input frequency range of .001 Hz to 999 Hz.

3) 4-20 mA output signal.

c. Units shall be Pepperl and Fuchs Model WEM/EX-FSU, Electro Sensors Or

Equal.

3. Suspended Solids Concentration Analyzer:

a. The Suspended Solids analyzer shall be microprocessor-based and directly accept a suspended solids concentration sensor manufactured by the analyzer manufacturer. The analyzer shall be as specified in Section 17405, Process Instrumentation and Control.

2.20 SEQUENCE OF OPERATIONS

The following pages describe the Control Strategies to be implemented by the

Manufacturer under this Division.

A. General:

1. The Control Strategy provided herein is subject to revisions during the shop drawing phase of the contract The Centrifuge manufacturer shall submit a control strategy for the Control of the Dewatering Centrifuges furnished under this contract. The OCSD reserve the right to make changes to the basic control strategy described below during shop drawing review at no additional cost to OCSD . A minimum of Ten (10) days on site engineering shall be provided by the Centrifuge manufacturer for making changes to the Control strategy, process optimization, and coordinating with the OCSD's auxiliary control system. The cost of providing this service shall be included in the Centrifuge Manufacturer's Lump sum price for this Contract as indicated in the Bid Documents.

2. The Dewatering Centrifuges shall operate with minimal operator intervention. The START sequence shall be initiated either from a Centrifuge LOCAL control Panel or from the OCSD's REMOTE control workstation. The selection of LOCAL or REMOTE control shall be made at the Centrifuge LOCAL control Panel OIT. Under alarm or "EMERGENCY STOP" conditions, the shutdown sequence shall be automatically triggered.

B. Auto Mode:

1. Start up Sequence:

a. The Centrifuge control system shall verify that no fault conditions exist, and that all centrifuge system permissives have been met including all auxiliary systems permissives.

b. The START sequence shall be initiated by the operator from the Centrifuge LOCAL control panel operator interface or REMOTE operator workstation depending on the MODE selected at the LOCAL control panel or from any location with proper password authority,

c. The main motor shall start and the bowl and scroll begin to rotate. The main motor shall be ramped up to the preset speed. The preset speed shall be set at the Centrifuge Control Panel; this setting shall be password protected to prevent unauthorized changes. The ramp-up time shall be determined by the manufacturer. The ramp-up time shall be adjustable as per centrifuge manufacturer recommendations with an initial setting of 30 minutes. During this start cycle, the scroll shall convey any remaining solids out of the bowl before the bowl full speed setting is reached. The Centrifuge panel PLC shall continuously monitor all interlocks and fault conditions.

2. Alarms/Interlocks:

a. Note: The Centrifuge manufacturer shall determine the vibration monitoring system delay time for run up. This will prevent nuisance vibration trips during startup with unequal sludge on the rotating assembly. Below is a partial list of alarms. Alarms shall be provided per P&IDs.

1) Main motor VFD fault.

2) Main motor winding temperature High.

3) Main motor Circuit Breaker Trip.

4) Scroll motor VFD fault.

5) Scroll motor winding temperature High.

6) Scroll motor Circuit Breaker Trip Lube oil pump overload.

7) Torque alarm HI.

8) Torque alarm HI HI.

9) Solids side bearing temp HI.

10) Solids side bearing temperature HI HI.

11) Liquid side bearing temperature HI.

12) Liquid side bearing temperature HI HI.

13) Vibration alarm HI.

14) Vibration alarm HI HI.

b. If any of the interlock conditions are present, the centrifuge shall not start. If the HI HI conditions are reached during the operation, the centrifuge shall shut down. Once the centrifuge reaches full speed, a feed permissive (READY for Sludge) shall be set in the Centrifuge PLC. This permissive shall be transmitted to the Dewatering PLC as a hard wired normally open contact. The normally open contact shall close when the Centrifuge is ready to accept sludge feed. This permissive will allow the auxiliary system equipment associated with the sludge feed system (i.e. polymer system, sludge feed) to RUN.

c. The sludge feed rate shall be determined by the operator based upon predetermined criteria including:

1) Sludge feed percent concentration.

2) Centrifuge sludge discharge desired concentration. C. Polymer Feed Pumps:

1. Polymer is delivered to the Centrifuge from the Polymer Mix/Aging System via a

Polymer feed pump tied directly into the sludge feed line to each Centrifuge.

2. The sludge feed flow rate input signal to the Centrifuge PLC is wired directly to the centrifuge control panel PLC from the sludge flow meter.

3. Centrifuge System Control

4. Scroll drive system of dewatering centrifuge will provide automatic speed variation between the scroll and the bowl based on torque. The scroll drive system shall provide for the automatic, torque-controlled regulation of relative scroll speed, corresponding to changes in feed concentration or quality, in order to continuously maximize cake solids concentration. Torque monitoring shall consist of an alert limit and alarm limit. The alert limit shall shut down the sludge feed pumps. The alarm limit shall shut down the centrifuge. In addition, appropriate adjustments to the centrifuge operating speed (manual adjustment by centrifuge manufacturer) polymer dosing, etc. shall be made based on Centrifuge Discharge Solids Concentration by the Centrifuge Manufacturer to optimize the operation of the Centrifuge.

D. Shutdown Sequence:

1. The shutdown sequence shall be initiated by the operator by selection of “AUTO SHUTDOWN” at either the LOCAL centrifuge panel operator interface or at OCSD’s REMOTE workstations. In addition, any of the faults indicated previously shall trigger an auto shutdown sequence. The Centrifuge PLC shall remove the sludge feed permissive to the Dewatering PLC which shall result in a shutdown of the feed systems. The polymer system and sludge feed pump will shut down. The flush water comes on at 400 gpm and below as the sludge feed begins to stop. The purpose of the dilution water is to prevent the sludge from dewatering. The main motor then cuts off and the CIP sequence starts.

E. Emergency Shutdown:

1. The Emergency shutdown (initiated either by the E-stop push button (Maintained mushroom head type) at the Centrifuge LOCAL panel; the E-stop near the lube pumps; the E-stop at the centrifuge; the E-stop at the main drive or scroll drive VFDs; or by system alarms/interlocks) shall shutdown all pieces of equipment. The alarms and shutdown shall follow the shutdown sequence. Upon clearance of the alarm conditions or resetting of the E-STOP push button, the system can be restarted.

Alarm condition	Action
Bearing temp. HI (solids or liquid side)	Alarm at Local panel and Remote workstations. No other action.
Bearing Temperature HI HI (solids or liquid side)	Controlled shutdown initiated. Operator acknowledges alarm.

Alarm condition	Action
Vibration HI	– Alarm at local panel and Remote workstations – Operator acknowledge alarms – Feed system given signal to stop – Bowl flushing sequence starts – When condition clears, bowl flushing stops, and feed system given OK to start
Vibration HI HI	– Initiates controlled shutdown sequence – Alarm at local panel and remote workstations – Operator acknowledges alarm
Torque HI	– Sends signal to Stop feed system – Alarm at local panel and remote workstations – Bowl flush sequence starts
Torque HI HI	– Alarm at local and remote workstations – Emergency shutdown sequence initiated – Operator acknowledges alarm
Centrifuge Main Motor faults	– Alarm at local and remote workstations – Controlled shutdown initiated
VFD faults	– Controlled shutdown sequence initiated – Alarm at local and remote workstations
Low oil Flow ( solids or liquid) side	– Controlled shutdown sequence initiated – Alarm at local and remote workstations
Loss of Sludge or Polymer Feed to Centrifuge	– Centrifuge placed in idle mode – Alarm at local and remote workstations
High percent solids or failure of percent solids analyzer at Centrifuge solids discharge	– Alarm at local and remote workstations

F. System Maintenance Mode:

1. The system maintenance mode shall be designed to allow the operator to individually jog motors. It shall be intended for troubleshooting purposes only. The system shall not be operated in this manner when processing sludge. The feed system (polymer and sludge shall also shut down and will not be allowed to start).

2.21 OPERATOR INTERFACE TERMINAL

A. The unit shall be located on the front of the Centrifuge Control Panel front face and be setup to display information graphically and provide control graphics to completely control the Centrifuge system.

B. Unit shall be Magelis Compact iPC, Maple Systems, Or Equal. C. Display:

1. Display Size: 15 inch.

2. Operator Input: Touch Screen.

3. Real Time Clock: Battery backed clock time stamps for alarm data.

4. Resolution: XGA 1024 x 768.

5. Application Memory: 2GB.

6. Communication Ports: Ethernet, USB, RS-232.

7. Programming: Vijeo Citect Designer.

8. Input Voltage: 120 volt, AC.

9. Storage: 40 GB Hard Drive.

D. Environmental:

1. Operating Temperature: 32 degrees F to 131 degrees F.

2. Storage Temperature: -13 degrees F to 158 degrees F.

PART 3 - EXECUTION

3.1 GENERAL

The manufacturer is responsible for all aspects of the centrifuge system, with the exception of the installation of the major components and external wiring. All internal wiring and skid-mounted wiring required in the shop shall be the responsibility of the Manufacturer. Responsibilities include design and fabrication, shop performance tests, safe delivery to the site, check out the installation by the CONTRACTOR, field checkout tests, field performance tests, equipment startup services, furnishing all tools, supplies, spare parts, and special equipment, and proper training of OCSD personnel.

3.2 FACTORY/SHOP TESTING

Factory testing of the centrifuge shall be performed at the centrifuge manufacturer’s facility to demonstrate the absence of mechanical or electrical defects and that the centrifuge operates within the specified limits. Equipment to be shop tested including the centrifuge, main drive motor, control panels, and VFDs. Factory testing of the control panels and VFDs shall be performed independently at the respective locations of manufacture. Test requirements for control and drive panels are in Division 17.

A. Shop Testing Procedure:

1. Centrifuge manufacturer shall allow inspection and witness of the shop test of the equipment by the ENGINEER and OCSD. In case of a failure of a test and consequent necessity to repeat the test, all related expenses shall be borne by the manufacturer.

2. Equipment to be shop tested and witnessed by the Engineer shall include:

a. Centrifuge.

b. Control Panels. c. VFDs.

3. Centrifuge manufacturer shall notify ENGINEER of the test schedule not less than 14 days in advance.

4. Test Conditions:

a. The following tests shall be completed before the centrifuge is released for shipment. Testing shall consist of a four hour dry run followed by a two hour wet run. During the test the machine shall be run at maximum, minimum, and 3 rpm differential speeds. Shop testing shall meet the tolerances in Article 1.3 before shipping and delivery.

1) Vibration measurement with bowl empty.

2) Vibration measurement with bowl filled with water.

3) Operation of machine for 2 hours with water.

4) Motor starting amperage.

5) Test equipment/procedures:

a) Test equipment shall be calibrated.

b) Unit shall be tested with a simulation panel.

6) In a separate shop test, all circuits on the control system panel shall be checked and all alarms and shutdown conditions simulated to check the alarm circuits.

5. Certified test results shall be submitted after completion and prior to shipping and delivery.

6. Shop testing shall include testing of the spare rotating assembly which shall be placed in one of the frames of the other machines for testing purposes.

3.3 SHIPMENT AND DELIVERY TO SITE

A. The manufacturer is responsible for shipment and delivery of the equipment as described in the General Requirements. The manufacturer shall coordinate with the installation contractor as needed to allow effective delivery to the area of work. each centrifuge shall be delivered as 9 separate pieces – rotating assembly, frame, casing, motor, VFDs, panels, and chute plus miscellaneous minor shipments of ancillary equipment, tools and spare parts.

3.4 INSTALLATION REQUIREMENTS

A. The Manufacturer shall provide written guidance and on-site advisory assistance in the installation of all equipment supplied herein.

1. Submit detailed instructions on preparation and installation of the centrifuge assemblies. Provide technical assistance to the Engineer as requested to clarify or expand information as needed.

2. Observe installation contractor during unloading of the centrifuge assembly. Inform the installation contractor in method of storage and notify when storage does not conform to manufacturer’s requirements. Provide all necessary maintenance on centrifuge assemblies during period of storage.

3. Provide technical assistance to the installation contractor.

4. Additional polymer injection point will be provided by the installation contractor during installation. The manufacturer shall verify that the proposed location and arrangement of the additional injection point is acceptable for proper performance of the centrifuge. Proposed injection points will be the same as current.

5. Coordinate with the installation contractor to arrange a mutually acceptable schedule to ensure substantial and final completion of special services consistent with the construction completion dates.

3.5 MAINTENANCE OF INSTALLED EQUIPMENT, GATES AND VALVES

A. Maintain the operability and functionality of all installed equipment, gates and valves between the time of installation and the commissioning period. See Specification section

01660 for requirements.

3.6 FIELD MECHANICAL TESTING

A. The manufacturer shall conduct field testing of the centrifuge to confirm all equipment is properly installed and ready for operation and to demonstrate:

1. The equipment was not damaged during storage, transportation, or installation.

2. The equipment is properly installed and aligned

3. There are no mechanical defects

4. The equipment is free of overheating, objectionable vibration, and overloading. The centrifuges and ancillary equipment shall operate without overheating, overloading of any parts or systems, and within the specified limits of vibrations, noise, temperature, pressures, and torque.

5. The proper interaction and effective control of the centrifuge, drive motor, scroll drive, lubrication system, and control panel, and drive panel will also be demonstrated, including all interlocks, safeties, and controls function as intended.

6. That the centrifuges can operate without problems within the specified limits of solids feed and polymer feed flow rates producing dewatered sludge of the specified consistency.

B. The test procedure, submitted by the manufacturer and accepted by the Engineer or OCSD, shall be run by a qualified representative of the centrifuge manufacturer in the presence of the OCSD and/or Engineer.

C. The field tests shall consist of:

1. Preliminary testing of control circuits, shutdowns, and control loops to verify correct interconnecting wiring to alarms by opening various field device contacts at the device and verifying loss of continuity at the appropriate control panel terminals.

2. A preliminary two hour water run of the centrifuge.

3. A four hour wet run of the centrifuge together with the polymer system, sludge feed system, washwater system, and associated instrumentation and controls. Water shall be used in this test for both the polymer and sludge feed lines.

4. A final field test consisting of a four hour sludge run. Polymer and sludge feed will be employed and dewatered the sludge produced. Sludge feed system and polymer feed system shall be part of this test.

3.7 FIELD PROCESS PERFORMANCE TESTING

A. After satisfactory completion of acceptance tests conducted on the centrifuge, each centrifuge shall be performance tested for four (4), six-hour periods conducted over a 5- day period to determine acceptable performance in accordance with the Design Requirements. The OCSD reserves the right to select and adjust test flow points (within the range given in Article 1.3. Performance tests shall be conducted two times, once during the winter season and once during the summer season (total of 8 tests runs over 2 performance tests) at dates established by the OCSD. Each test run must comply with the performance requirements in Article 1.3.

B. During each day’s performance test, the CONTRACTOR shall be responsible for collecting all required samples and measurements at 1/2 hour intervals in order to make the following determinations. The first set of samples and measurements shall be taken

1 hour after the beginning of the test run.

1. Sludge feed – total solids.

2. Centrate – total solids.

3. Centrate – suspended solids.

4. Dewatered sludge – total solids.

5. Polymer feed rate – gallons per minute.

6. Sludge feed rate – gallons per minute.

7. Centrifuge discharge rate – pounds per hour.

8. Solids capture – percent.

9. Setting for polymer feed pump.

10. Setting for sludge feed pump.

11. Differential speed, torque setting.

12. Motor amperage.

13. Power draw.

C. During the entire Performance Test period, all samples will be split, with one sample provided to OCSD and the second sample delivered to a certified laboratory for analysis. Laboratory tests will be performed by a certified lab agreed upon by the CONTRACTOR, Engineer, and OCSD, to obtain sludge feed total percent solids, centrate total percent solids and suspended solids, and dewatered total percent solids. The results will be binding. The cost for independent laboratory analysis to be paid by the Manufacturer.

D. All data collected during performance tests shall be made available for the ENGINEER for determining compliance with the Specifications. The ENGINEER may request certified test data or call for on-site test to confirm the accuracy of all instruments used in testing. All costs for testing shall be borne by the Manufacturer.

E. Test records shall be maintained to insure that the specified flow rates and polymer usage are met throughout the duration of the test. The Manufacturer is responsible for all necessary tools, meters, and test instruments.

F. Polymer dosage shall be determined as the total active polymer consumed divided by the dry solids fed to the machine during the test run period.

G. In the event the equipment is not meeting the guaranteed performance, the manufacturer shall, at his own expense, adjust or modify the equipment to meet these guaranteed performance standards. All costs associated with the centrifuge modifications shall be borne by the Manufacturer. The equipment shall be modified and the test repeated until successfully completed. New test results will govern.

H. Manufacturer shall have the use of two polymer injection points during the performance test: 1) Centrifuge feed tube and 2) centrifuge feed piping. Polymer injection points will be the same as the existing units.

3.8 TECHNICAL SERVICES

Technical Services of the manufacturer’s representative shall be supplied in the following areas:

A. Field Service Technician Qualifications:

1. The Manufacturer shall dispatch factory-trained technicians to service the equipment. The technicians shall be in the direct employ of the Manufacturer.

2. All field service shall be supported by a fully qualified field service department. The field service department shall be fully staffed with at least 20 full time employees, all of whom are factory-trained for the equipment.

3. Field service department shall be within a driving distance from OCSD.

4. Field service department shall have spare parts readily available.

5. Field service shall be available 24 hours per day, 7 days per week. B. Start-Up Services:

1. Furnish the services of authorized technical representatives of the Manufacturer to assist/inspect the equipment, conduct pre-operational mechanical checkout of the equipment, place equipment into operation, optimize the performances of the equipment and perform the field performance testing. These services shall be per Schedule 11365-2.

2. See Specification section 01820, Training for OCSD Personnel, for additional training requirements.

Schedule 11365-2 Dewatering Centrifuge Start-Up Services
Description of Service	Minimum Requirements
	Days	Number of Personnel	Total Man- Days
Installation Inspection Inspect Piping, Chutes, Flex. Connections Installation Inspect Wiring and Control Installation PLC Programming and Trouble-Shooting Mechanical Start-up (Checkout) Process Start-up (Checkout) Field Performance Testing	6 2 8 15 10 10 15	1 1 1 1 2 2 2	6 2 8 15 20 20 30
Total			101

C. Emergency Service:

1. Provide the services of the Manufacturer to be present within 24 hours for on-site emergency services of all the furnished equipment. Emergency service shall be required for failure of any major component of the centrifuge equipment.

2. Emergency service shall be provided at no charge throughout the 1 year warranty period from the day of OCSD acceptance.

D. Training:

1. The manufacturer shall provide operation and maintenance training as follows:

a. Operations Training: three (3) days, 8 hours per day not including travel time of classroom and hands-on instruction which will cover the theory of operation, actual operation of the centrifuge, polymer systems, and optimization of the centrifuge operations. Operations training shall cover OCSD’s personnel on weekends and on the daily three (3) shifts.

b. Maintenance Training: Three (3) days of classroom and hands-on training, either during or after the operations training, in separate sessions for Electrical maintenance, Instrumentation maintenance, and mechanical maintenance. Each class shall be a minimum of 4 hours per day and conducted between the hours of

8 am to 4 pm.

2. The equipment manufacturer shall schedule no less than 3 days (8 hours per day not including travel time) to supervise maintenance of the equipment over the 1 year period following acceptance.

3. Additional training is defined in Division 17.

3.9 FIRST YEAR OPERATIONS AND MAINTENANCE ASSISTANCE SERVICES AGREEMENT (O&MASA)

A. In addition to commissioning, training and other on-site services described elsewhere in this Specification section, the Centrifuge manufacturer shall provide a listing of all operations and maintenance required on the centrifuges. OCSD shall select the services to be provided by the Centrifuge manufacturer for a period of eight months following RAT acceptance.

B. The O&MASA is intended to cover the assistance of a factory certified service technician to operate, service and maintain centrifuges in accordance with the factory established operation and maintenance procedures.

C. The technician’s role shall be assisting in but not limited to the following items:

1. Assistance with regular operation and maintenance as specified in the operation and maintenance manual for the centrifuge, which includes performance optimization, inspections, adjustments and routine maintenance of each centrifuge.

2. Assistance with preventative maintenance based on the actual cumulative running hours of operation of the equipment and includes scheduled inspections as well as maintenance of wear components.

3. Assistance with Bi-Annual (twice yearly) inspections including check and adjust the equipment in accordance with the requirements of the Lubrication and Maintenance Schedule.

3.10 OCSD ACCEPTANCE

A. The OCSD will accept only complete, workable equipment and systems under the following conditions:

1. After receipt by OCSD of all the work drawings in “Accepted” or “Accepted as

Noted ” status by the Engineer.

2. After receipt by OCSD of all centrifuge documentation required by the contract.

3. After completion of all specified factory testing and receipt of all factory test reports accepted by the Engineer.

4. After completion of all specified equipment cleaning, start-up, field testing and acceptance of performance runs as specified herein and receipt by OCSD of all specification certifications accepted by the Engineer.

5. After receipt by OCSD of all spare parts and complete final draft of service manuals as specified herein.

6. After completion of Operator Training Schedule as specified herein. in any parts.