4-02 25-250-B Specification - 46 41 27.11 Vertical Turbine Mixers.pdf

Specification – 46 41 27.11 Vertical Turbine Mixers 25-205-B PWAS and Blend Tank Mixers

SPECIFICATION

46 41 27.11 VERTICAL TURBINE MIXERS

1.00 GENERAL

1.01 SCOPE OF WORK

A. This section covers suspended Vertical Turbine Mixers for installation in the PWAS Holding

Tank (1) required and Blend Tank (2) required. Hyperboloid Mixers per Section 46 41 27.33 are an acceptable alternative if applicable for the Blend Tank.

B. Furnish mixer base plates, and epoxy anchors for mounting to the concrete deck of the covered tanks in the approximate center of the tank.

C. The system shall be capable of complete homogeneous mixing of the tank contents.

D. The Manufacturer shall review the conditions of service and mounting arrangements for the Manufacturer’s proposed mixers including basin geometry, flow path, freeboard, and shall propose mixing equipment suitable for the application and in accordance with these specifications. Any deviation from these specifications shall be identified in the proposal information accompanied by a letter of qualification documenting the variances and explaining why acceptance is in the best interest of the Owner.

1.02 STANDARDS

A. The mixing equipment furnished shall comply with the following standards as applicable

1. American Society for Testing and Materials (ASTM) Publications

2. Anti-Friction Bearing Manufacturers Association (AFBMA)

3. American Gear Manufacturers Association (AGMA)

4. American National Standards Institute (ANSI) Standards

5. Occupational Safety and Health Administration (OSHA) Standards

1.03 SYSTEM DESCRIPTION

A. Supply vertical turbine mixers for the PWAS Tank and Blend Tank as shown on the drawings.

The mixers shall completely mix the contents of the tanks at maximum volume to maintain a uniform solids concentration throughout the tank.

B. The vertical mixer shall consist of an adequately sized drive motor, specially designed gear reducer with robust bearing capacity for sustaining the bending, thrust and torsional loads imposed by the cantilevered shaft and suspended impeller, vertical shaft and impeller sized to achieve complete tank mixing.

C. A coated steel base plate and stainless-steel epoxy anchors sized by the manufacturer to transmit the static and dynamic loads to the supporting concrete structure.

1.04 SUBMITTALS

A. All submittals shall be approved by the Engineer or the Owner prior to delivery.

1.05 ACTION SUBMITTALS / INFORMATIONAL SUBMITTALS

A. The following items shall be submitted with the proposal for bid:

1. Shop Drawings

a. Shop Drawings detailing the mixer mechanical components, materials, and coating specifications.

1) Shaft size and material

2) Impeller size, type and material

3) Complete bill of materials for the equipment.

b. Details demonstrating that the impeller components will pass through the 4 x 4 foot aluminum access hatch for the PWAS Tank and 4 x 6 foot aluminum access hatch for the Blend Tank hatch for assembly inside the covered tanks.

2. Coatings for components that are not fabricated from stainless steel recommended slab openings and baseplate sizing and anchor arrangement.

3. Any deviations from this specification must be accompanied by a formal Certification or

Qualification Letter.

4. A general arrangement drawing of the proposed mixer for the PWAS and/or Blend Tank.

5. Delivery conditions:

a. Specify lead times for fabrication and delivery.

B. The following items should be submitted after award:

1. CFD model – submit a report using CFD modeling or equivalent analysis demonstrating that the mixing equipment proposed will completely mix the tanks with the geometry shown on the plans and described herein. Modeling shall be based on an assumed specific gravity of 1.0 and a solids concentration of 24,000 mg/L (ppm) for the PWAS Tank and a specific gravity of 1.01 and a solids concentration of 74,000 mg/l (ppm) for the Blend Tank. The modeling report shall include data confirming that the motor horsepower proposed is adequate to impart the required mixing energy to keep the basin completely mixed at the maximum surface elevation, including consideration for electrical and mechanical efficiency.

2. Additional information to be submitted:

a. Coupling details if used

b. Shaft size and material

c. Impeller size, type and material

d. Impeller assembly details

e. Type and ratings of shaft support bearings.

f. Complete bill of materials for the equipment.

g. Recommended spare parts list.

h. The weight of each component: motor, gearbox, shafting and impeller.

i. The recommended installation, operation, and maintenance procedures.

j. Mounting details

k. The anticipated static and dynamic loads under full load

l. The total weight of the complete assembled mixer.

m. Draft O&M manual

n. Complete motor data including size, make, type and characteristics of the electric motor along with wiring diagrams.

3. Bearing life calculations.

4. Calculations supporting shaft and impeller design criteria (stresses and critical speed).

5. Layout of installed mixer with recommend placement horizontally and recommend placement of impeller or impellers if multiple impellers are proposed, clearance requirements from tank features and existing equipment and piping.

1.06 CLOSEOUT SUBMITTALS

A. Letter from the representative of the mixer manufacturer certifying that the furnished equipment was installed in accordance to the manufacturers recommendations and is ready for beneficial use.

1.07 MAINTENANCE MATERIALS SUBMITTALS

A. O&M Manuals

1. O&M manuals shall demonstrate procedure to suspend wetted parts from mixer mounting plate or support structure during gearbox replacement.

2. A final O&M manual shall be delivered with the equipment.

3. The maintenance summary form, warranty certificate, equipment installation report shall be included with final O&M manual.

1.08 DELIVERY, STORAGE, AND HANDLING

A. Avoid supporting or lifting the mixer in a manner that will place excessive stress on parts or shafts that are not designed to support the weight of the unit. The mixer assembly shall be lifted by eyebolts provided in the top of motor drive or by slings.

B. The Owner shall inspect equipment prior to unloading and notify the manufacturer of any damage to delivered equipment.

1.09 WARRANTY

A. The mixer manufacturer shall warrant and guaranty the provided equipment is free from manufacturing defects and is suitable for the intended application as described herein.

Components that fail in application within 24 months from start-up and final acceptance shall be replaced without charge..

2.00 PRODUCTS

2.01 MANUFACTURERS

A. Acceptable mixer manufacturers with demonstrated competence are:

1. SPX FLOW Inc. Lightnin Series 70 Top Entry

2. NOV, Inc. Chemineer – Model 20 GT Top Entry

3. Engineer’s approved equal

2.02 PERFORMANCE REQUIREMENTS

Location PWAS Holding Tank Blend Tank

Number of mixers (1) Centrally Located (2) Lightnin Model No. 17QT10 15QT3

Chemineer Model No. 23GTD-10 22GTD-7.5 Mounting Arrangement Baseplate Baseplate

Tank Dimensions

Tank Length 22’-8” 22’ Tank Width 28’-4” 12’ Tank Height 11-4" 18-8"

Minimum Liquid Level 584.75 577.42 Maximum Liquid Level 594.5 591.88 Tank Ceiling Thickness 1' 8"

Liquid being Mixed Waste Activated Sludge Primary Sludge, Thickened

Sludge, and Scum Maximum Percent Solids 2.4 (24,000 mg/L) 7.4% (74,000 mg/L)

Specific Gravity 1 1.02 Percent BioMag 0.05 % <0.05%

Number of Impellers 1 2 Vapor Seal Assembly Yes Yes Desiccant Breather Yes Yes

Power 460V, 3ph, 60 Hz 460V, 3ph, 60 Hz Installed Motor Minimum Horsepower per mixer 10 7.5

Speed 1800 rpm 1800 rpm Enclosure TEFC TEFC

Space Heater Yes Yes Motor Winding Temperature

Switches Yes Yes

2.03 MATERIALS AND/OR EQUIPMENT

A. Gear Reducer

1. The mixer gear reducer shall be mounted on a pedestal base above the tank deck with the output shaft rigid coupling below the base of the mixer to allow the disassembly of the coupling above the tank deck. The pedestal shall be integral to the gear reducer.

2. The gear reducer shall be designed in accordance with AGMA Standard 6010-F97 requirements for continuous 24-hr/day operation with a minimum AGMA service factor of

2.0 based upon motor nameplate horsepower. The basic rating of the gear reducer shall adhere to appropriate AGMA standards and the gear reducer shall bear an AGMA nameplate, or the manufacturer shall certify, in writing, that the gear reducer is designed to the applicable AGMA standards.

3. All gearing must be contained in a single housing. Auxiliary gear boxes to obtain double or triple reduction are not acceptable.

4. Gearing shall be of AGMA quality No. 10 or better per AGMA Standard 390.03.

5. All gearing shall be immersed in a common bath of lubricating oil. All rotating parts and bearings, with the exception of the output shaft and output shaft bearings, shall be immersed in oil or splash lubricated by means of the gears or a slinger rotating on the horizontal gear shafts in the oil bath. Oil leakage down the impeller shaft shall be prevented by means of an oil dam around the shaft. The gear reducer shall be provided with a dipstick and/or a sight glass to observe oil level. Lubrication systems requiring oil pumps are not acceptable. Grease packed gear reducers are not acceptable.

6. A single oil drain shall be provided at the low point of the gear reducer to allow oil drainage. The oil drain shall be extended from the gear reducer to prevent leakage and spillage during oil changes.

7. All gear reducer bearings shall be antifriction type ball or roller bearings and shall have a minimum rated B-10 life of 100,000 hours.

8. To prevent moisture from contaminating the oil, the gear reducer shall be furnished with a disposable desiccant breather. The breather shall have a disposable 3- micron polyester filter for solid particulate and a hygroscopic agent to prevent water vapor from entering the gear reducer. The gear reducer breather shall be located above possible oil foam level.

9. The mixer base and output shaft shall be furnished with a vapor seal assembly which shall include either a V-ring seal, clamping collar and Teflon wear plate or a 316 stainless steel ANSI 150 pound flange and Teflon lip seal and Teflon wear plate to prevent foul air from escaping through the shaft openings in the slab.

B. Mixer Shaft

1. The mixer shaft and all materials located below the operating deck shall be constructed of 316 stainless steel.

2. Shaft diameter shall be determined by an analysis of torques, bending moment, thrust, pressure, temperature, and critical speed. The shaft shall be designed such that the maximum combined stress considering torsion, bending and thrust shall not exceed 8,000 psi under maximum operating loads. It shall be of overhung design. The use of in-tank steady bearings is not permitted.

3. The shaft-impeller system design shall be such that its operating speed shall not exceed

70% of its first lateral critical speed. The use of stabilizing rings or fins will not influence this limitation.

4. Mixer shaft straightness, rigid coupling squareness, and gear reducer output shaft accuracy must be such that the maximum total indicated runout at the lower end of the mixer shaft does not exceed 1/8-inch per every 10 ft of shaft length, as measured when turning over by hand.

5. Shaft design shall include features to allow all wetted parts to be suspended from the mixer pedestal base or support structure during gearbox replacement. Furnish all special tools, adapters, etc. required to suspend wetted parts and reconnect during gearbox replacement.

C. Mixer Impeller

1. Impellers shall be connected to the mixer shaft with a hook key. Impellers shall be anti-ragging hydrofoils and may be 3 or 4-bladed. Impellers may be up flow or down flow as recommended by the manufacturer.

2. 3-bladed impellers shall be mechanically assembled to allow individual vanes to be removed through the 4 x 4 foot aluminum access hatch for the PWAS Tank and 4 x 6 foot aluminum access hatch for the Blend Tank.

3. Each impeller shall be constructed of AISI Type 316 stainless steel. Assembly bolts for impellers shall be Type 316 stainless steel and double nutted, or otherwise locked against loosening due to vibration.

4. The impeller shall be dynamically and hydraulically stable and shall not cause the equipment to overload over the specified range of liquid levels with up to the specified flow rates through the basins.

5. The use of stabilizer rings will not be permitted.

6. The impellers shall be designed to prevent vortexing.

D. Guards

1. All rotating machinery above the deck shall be provided with safety guards.

E. Flexible Coupling

1. Couplings shall be selected by the manufacturer, and shall be sized for the power transmitted with a suitable safety factor.

F. Mounting Arrangement and Anchors

1. Dynamic and static loads used to determine the mounting requirements shall be provided by the manufacturer.

2. The mixer housing shall mount to a baseplate minimum 1 inch thick; the base plate shall be anchored to the concrete deck. The baseplate shall be steel, and epoxy coated after fabrication. Concrete anchors shall be recommended by the manufacturer but not less than one inch in diameter and 304 stainless steel. Baseplate assembly shall fully cover the tank opening.

G. Drive Motors

1. Drive motors shall be 3 Phase suitable for outdoor application in TEFC enclosures.

2. Motors shall be rated for severe or chemical duty

3. Motors shall have minimum 1.15 SF.

4. A corrosion proof nameplate shall be provided with each motor and shall be securely fastened thereto. Information shall include voltage, speed, phase, insulation class, amperage, service factor, wiring diagram, and motor serial number.

5. The motors shall be Class F insulation and Class B temperature rise.

2.04 PAINTING

A. Manufacturers factory finish shall be suitable for exposed applications without recoating in field.

2.05 EQUIPMENT IDENTIFICATION

A. The equipment shall be provided with a stainless-steel nameplate, securely fastened in a conspicuous place and clearly inscribed with the manufacturer's name, year of manufacture, serial number, and principal rating data.

3.00 EXECUTION

3.01 INSTALLATION

A. Equipment shall be installed by others in accordance with the manufacturer’s submittals, drawings, and written installation instructions.

3.02 INSPECTION AND TESTING

A. All sampling and testing to be performed by manufacturer during performance test.

B. The Manufacturer will conduct a Suspended Solids test on mixers placed in service for the PWAS Tank. The suspended solids uniformity test will be conducted with solids concentrations not exceed those specified for the service conditions in Section 2.02.

C. Demonstrate that a uniform concentration of the TSS is achieved at the end of a 30-minute test period with the mixer operating and no incoming flow or recycle flows. Uniformity is defined as plus or minus 10% of the average deviation of the TSS concentration for all samples taken in the test zone.

D. The Manufacturer recommended test is required to show complete mixing of the tank for the

Blend Tank.

E. Should any portion of the system fail to meet the requirements specified, the Manufacturer shall make modifications such that the system meets the requirements of this Specification, at no additional cost to the Owner.

3.03 MANUFACTURER FIELD SERVICES

A. The manufacturer shall include the services of a manufacturer's factory trained service technician for field supervision during installation, certification the Manufacturers mixers have been installed as recommended by the manufacturer, and to instruct Owner personnel on operation and maintenance procedures as applicable.

1. A factory trained representative for the equipment specified herein shall be present at the jobsite and/or classroom designated by the Owner for installation inspection, plant startup, functional testing, and operator instructions; travel time excluded.

a. Installation: Assist in installation and leveling of mixer/aerator and in coordinating electrical and control connections or any other miscellaneous coordination: 1 Man-day for each tank (non-consecutive): Two (2) Man-day (8 hours)

b. Start-up and Operation and maintenance (O&M) instructions: One (1) Man-day (8 hours)

c. Certification and Performance Testing: One (1) Man-day (8 hours)

2. If there are difficulties in operation of the equipment due to the manufacturer’s design or fabrication, additional service shall be provided at no additional cost to the Owner.

B. The mixer manufacturer’s representative shall provide a report after inspection and testing has occurred. The report shall certify that the mixer is installed per the manufacturer’s recommendations and is ready for beneficial use by the Owner.

END OF SECTION