SECTION 11368
COARSE BUBBLE AERATION SYSTEM
PART 1 GENERAL
1.1 SECTION INCLUDES
A. Coarse Bubble Aeration Systems:
1. Dryer off-gas treatment system.
1.2 REFERENCES
A. ASTM International:
1. ASTM A240 - Specification for heat-resisting chromium and chromium-nickel stainless steel plate, sheet, and strip for pressure vessels.
2. ASTM A554 - Specification for stainless steel tube, welded, for mechanical applications.
3. ASTM A774 - Specification for austenitic stainless steel fittings (as-welded), for general corrosive service at low/moderate temperatures.
4. ASTM A778 - Specifications for welded, unannealed tubular products (for low/moderate temperatures and corrosive service).
1.3 DESIGN REQUIREMENTS
A. Dyer off-gas treatment systems: As shown on the Contract Drawings, provide two headers of diffusers in two aeration tanks. See Contract Drawings for diffuser location and tank dimensions.
B. Design diffusers and header to operate at the following conditions:
Diffuser Header Location
Design Air Flow Rate per Header (scfm)
Number of Diffusers per Header
Air Rate Per Diffuser (scfm)
Pressure at Top of Dropleg (PSIG) at Std. Conditions
Aeration Tanks No. 1 and 2
300
12
25
6.8
Note: Air volume flowing conditions and headloss calculated at 14.7 psia, 70ยบ F and 38% relative humidity.
C. Design the system to uniformly distribute the air from the first drop to the last drop with no more than a + 10% deviation in airflow
1.4 SUBMITTALS
A. Shop Drawings: Submit in accordance with Division 1, including the following.
1. Complete assembly and installation drawings, including plan and elevation views and appropriate cross-sections of aeration equipment.
2. Certified performance curves for pressure loss.
3. Descriptive information on material and equipment furnished.
B. Submit operations and maintenance data under the provisions of Division 1.
C. Submit certificates of proper installation and operator training under provisions of Division 1.
1.5 DELIVERY, STORAGE AND HANDLING
A. Deliver, store and handle the equipment under the provisions of Division 1.
PART 2 PRODUCTS
2.1 MANUFACTURERS
A. Sanitaire, Xylem Water Solutions Inc.; Brown Deer, WI.
2.2 GENERAL
A. All equipment shall be the end product of one aeration system manufacturer. The manufacturer shall be responsible for the complete system including all items covered herein.
2.3 MATERIALS AND FABRICATION
A. Stainless Steel:
1. Fabricate manifolds, drop legs and headers of stainless steel tubular products and fittings that meet ASTM A778, ASTM A774, and ASTM A554.
2. Furnish all nuts, bolts, and washers including anchor bolts in 316 series stainless steel.
B. Welding:
1. Do all welding in the factory using MIG, TIG or plasma-arc welding inert gas processes.
2. Add filler wire to all welds to provide for a cross section equal to or greater than the parent metal. Use ER 316L filler wire.
3. Fully penetrate butt welds to the interior surface and provide gas shielding to interior and exterior of joint.
4. Interior weld beads shall be smooth, evenly distributed with an interior projection not exceed 1/16" beyond the I.D. of the air header or fittings.
5. Continuously weld both sides of face rings and flanges.
6. Field welding will NOT be permitted.
C. Corrosion Protection and Finishing: Pickle all stain-less surfaces by using the following procedure:
1. Wire brush all outside weld areas to remove weld splatter. Brushes shall be of stainless steel and used only on stainless steel.
2. Remove all carbon deposits, greases and oils by pickling and neutralization to aid the regeneration of a uniform corrosion resistant chromium oxide film.
a. Completely immerse all stainless steel assemblies and parts after welding and brushing in a pickling solution of 10% nitric acid and 3% hydrofluoric acid in a water bath at 140 degrees F for a minimum of 15 minutes. Parts shall be free of iron particles or other foreign material after this procedure.
b. Scrub as required. Immediate final thorough rinse in clean hot water and let dry.
3. Corrosion protection techniques not using full immersion will not be acceptable.
2.4 AIR DISTRIBUTION PIPING
A. Manifold Piping:
1. Material: 316L Stainless steel.
2. Diameter: 4-inches.
3. Minimum wall thickness: 12 gauge.
4. Provide manifold piping with a welded-in horizontal run-out coupling at the location of each individual air diffuser. Weld in couplings prior to full immersion passivation for full corrosion protection.
5. Provide a loose follower flange, drilled for 150 pound bolting, for the connection to air piping.
B. Drop Legs and appurtenances:
1. Material: 316L Stainless steel.
2. Diameter: 1-inch.
3. Minimum wall thickness: Schedule 40.
4. Provide pipe nipple and orifice union for connection to the air manifold piping.
5. Provide a cleanout tee at the top of the drop leg to provide accessibility to the drop and diffuser. The tee assembly shall include a CPVC orifice insert plug in the top position. The side outlet of the stainless steel tee shall be fitted with a type stainless steel nipple.
C. Supports:
1. Each diffuser and droplet assembly shall have a dedicated fixed support
a. Fixed support shall prevent lateral and rotational movement of the dropleg. Supports shall allow longitudinal movement of the dropleg section to prevent stress build up due to expansion/contraction forces.
b. Fixed supports shall consist of a hold down mechanism and self-limiting clamp device.
2. Provide 316 stainless steel, adhesive concrete anchors, as specified in Section 05500.
2.5 AIR DIFFUSERS
A. General: Coarse bubble, one-piece construction, consisting of an air release tube and a double tapered deflector.
B. Design:
1. Materials of construction: Pressure injection molded ABS plastic
2. Air release tube:
a. Air release tube shall have an inside diameter equal to or greater than that of the drop pipe throughout its length and shall terminate with a full diameter opening.
b. Provide vertical slots at least 1/4 inch wide to distribute airflow to all quadrants of the deflector. The slots shall extend to full width openings at the open bottom of the air release tube to facilitate cleaning. Separating vanes shall be spaced to form four quadrants to contain the air release from each slot and shall distribute air to each shear plane.
3. Deflector: The deflector portion of the diffusers shall break up the coarse bubbles generated at the release tube slots into the finer bubbles required for efficient oxygen transfer.
PART 3 EXECUTION
3.1 INSTALLATION
A. In accordance with Drawings, shop drawings and manufacturer's instructions.
B. Layout and install support anchors in accordance with equipment manufacturer's recommendations and anchor setting plan.
C. Follow equipment manufacturer's recommendations for sequencing of equipment installation.
D. Level aeration system such that all diffusers connected to a manifold are within plus or minus 3/8 inch of a common horizontal plane.
3.2 MANUFACTURER'S SERVICES
A. Provide manufacturer's services under provisions of Division 1.
B. Minimum Service Requirements:
1. Installation: As required for proper installation.
2. Start-up and field testing: Two trips, one half day on site each trip.
3. Operator training: One half day on site.
C. Service to Repair Defective Work: Provide during one-year warranty period under the provisions of General Conditions.
END OF SECTION
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