ISpecifications for PVC-FRP Packed Bed Scrubber for chlorine gas

Design, manufacture, supply, erection and commissioning of PVC·FRP packed bed scrubber forneutralization of chlorine gas, as per the following specifications

1. SCOPE

This specification covers the requirements of design of the packed bed scrubber, preparation of itsdetailed drawings, fabrication according to accepted specifications, testing and inspection atcontractor's works, supply, erection/installation, testing and commissioning at site and carrying outperformance / acceptance tests of the equipment along with necessary accessories (including fluidtransfer equipment, piping/ducting) of a Packed bed scrubber for neutralization of chlorine gas withcaustic soda solution.

It is not the intent to specify completely herein all details of design and construction of equipment ormaterials to be supplied or of services to be rendered. However, the equipment, materials and servicesshall conform in all respects to high standards of engineering design, workmanship and be capable ofperforming in continuous commercial operation in a manner acceptable to purchaser who will interpretthe meaning of drawings and specifications and shall have the power to reject any work or materialwhich in his judgement are not in full accordance herewith.

Equipment:

~ Packed bed scrubber for neutralization of chlorine - 1 No.~ Pump for recirculation of scrubbing liquid along with ball valves at pump inlet andoutlet- 2Nos.~ Connecting liquid pipelines from scrub solution tank to pump, pump to scrubber andback to tank. The distance between the scrubber column and recirculation tank is about20meters however, exact location and distance will be fixed after the placement oforder~ Connecting ducting line for gas (from existing duct) to scrubber inlet and from scrubberoutlet to existing blower inlet duct. The header duct diameter is 600mm and total length isapproximately 40 meters.~ All supporting structure, inspection/maintenance platform, pedestals, foundation, bolts,nuts, washers. base plates etc for the pump and scrubber.

2. DESIGNBASIS

i. F d 8 "fi ree pee tea Ions81. Parameter DescriptionNo1 Exhaustqases C12,CO, C02 and ZrCI42 Operating! desiqn temperature (oC) Ambient3 Operatinq pressure (mm wc) 300-400 mm we less than atm4 Gas flow rate 15000 m3!hr5 Maximum chlorine input 80 kq/hr6 Minimum chlorine input 1.6 kg/hr1 Efficiency of the scrubber Better than 99% @ 2% NaOH concentration of

the scrubbing solution at maximum as well asminimum chlorine input.

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ii. Product SpecificationSI. Parameter DescriptionNo1 Maximum allowable pressure drop in the scrubber 100 mmWC

3. PROCESS DESCRIPTION

Chlorination of zirconium oxide and zircaloy scrap are carried out in chlorination section of ZirconiumSponge Plant, NFC, Hyderabad. The chlorination reactions are as follows.

Zr02 + 2CI2 + 2C = ZrCI4 + 2CO -----(1)Zr02 + 2Cb + C = ZrCI4 + C02 ----(2)Zr + 2Cb + = ZrCI4 ------(3)Here the exhaust gas from the reactors consist of un-reacted chlorine gas, CO and C02 along withsome ZrCI4 dust, which is the inlet of the packed bed scrubber. The scrubbed gas coming out of thecolumn shall join the main exhaust duct so that they can be exhausted through a 32.5-meter highstack by means of blowers.The scrub solution being presently used in plant is sodium hydroxide. The probable reactions ofchlorine with NaOH are given below.2NaOH + CI2- NaCI + NaOCI + H20.NaOCI + CO- NaCI+C02 .ZrCI4+7H20- ZrOC126H20+2HCI.HCI+NaOH-NaCI+H20ZrOCI26H20 may salt out and stay in the solution. There can be formation of NaHC03 andNa2C03 during the scrubbing operation.

4. CONSTRUCTION MATERIALS

4.1. Scrubber Housing - The scrubber shall be made of Grade I PVC sheet of minimum 6 mmthickness coated with at least 12 mm thick FRP layer. The scrubbing column/housing shall be verticallymounted on a truss coated with Polyurethane paint. Bisphenol resin shall be used for all FRPworks. The needful reinforcement shall be provided for the scrubber column to meet the strength andservice requirements. The suitable structural supports and platforms shall be provided for scrubber tomeet the operational and maintenance requirement. All metallic parts shall be given 2 coats of PUpaint after applying the primer. The scrubber shall have a fixed-location lug system (for anchoring to aconcrete pad) consisting of at least four (4) evenly spaced lugs. The lugs shall be 316L stainless steel.Suitable working platform with ladder to reach it shall be provided for the supporting structure to carryout maintenance on the columns and other serviceable components on it. Discharge of solution fromthe scrubber shall be at 2 meter height.4.2. Exterior Gel Coat - The scrubber-housing exterior shall utilize an industrial grade gel coatand shall contain UV inhibitors.4.3. Fiberglass Reinforcement - Glass fibers shall be of an industrial grade.

,4.4. Inlet and Outlet Transitions - The gas inlet and outlet lines of the column shall be provided withbutterfly valves for isolation at the time of maintenance. Inlet and outlet transitions shall be fabricated ofthe same material as the scrubber vessel. Each transition shall be designed to provide a smoothtransition from duct velocity to scrubber velocity without causing airflow disruptions. The transition willinclude a flange to match the scrubber body as well as duct connections.

5. LIQUID RECIRCULATION SYSTEM

The recirculation system shall be designed to pump the required scrubbing solution from.the tank to thespray headers, as determined by the surface area of the packing material and the scrubbing efficiency.5.1. Piping - All pipings should be of Schedule 40 mild steel coated with PU paint. About 20 meterslength of 90mm schedule 40 MS pipes should be supplied along with the suitable valve and the sameshall be laid from existing water washing header line to the proposed scrubber inlet line.5.2. Spray Nozzles -Make: Spraying systems/Chemtrols Samil/Lechler. The nozzle material shall bePP/PVC. The nozzles should be attached to a PVC nipple which shall be welded to the spray headers.5.3. Spray Headers - The spray header shall be PVC/PP. Each spray header shall be designed tocarry the appropriate liquid flow to ensure proper liquid loading rates across the scrubber packing.5.4. Pump -The pump shall be centrifugal type and MOC of the wet parts shall be of PP/PVDF. Therecirculation liquid contains HCI, NaOH, NaCI, Sodium Hypochlorite etc.5.5. Plumbing Accessories - A check valve shall be provided at the recirculation pump discharge. Ballvalves shall be provided at the inlet and outlet of pump All valves shall be constructed of PP/PVCmaterial and all wetted parts should be resistant to process chemicals.

6. PACKING AND SUPPORT

6.1. The bed height shall be sufficient to meet the minimum efficiency as detailed within thisspecification.

6.2. Packing material shall be designed for proper mixing of liquid and gas and to achieve the highestpossible contact surface area and flow distribution. The packing shall be manufactured from PVC.6.3. The packed bed shall be designed with a maximum pressure drop of 100 mm wc.6.4. The packing supports shall be strong enough to carry the weight of the packing. It shall also haveample free area to allow for flow of liquid and gas with minimum restriction. Packing restrainers shallalso be used if deemed necessary.6.5. The scrubber shall have provisions for easy removal and cleaning of the packing material as wellas provision for easy replacement of the packing.

7. ENTRAINMENT SEPARATOR

7.1. The scrubber shall have an impingment-type entrainment separator of chevron design located inthe outlet section of the scrubber prior to gas discharge.

7.2. The entrainment separator shall be capable of removing in excess of 99 percent of the entraineddroplets larger than 15-micron diameter on a total weight basis. The pressure drop through the misteliminator shall not exceed 10 mm wc at maximum operating airflow rates.7.3. The entrainment separator shall be configured in a cartridge assembly to allow removal forcleaning and replacement. The scrubber entrainment section shall include a bolt-on access door oneach side of the transition to facilitate easy removal of the cartridge. The cartridge shall be provided ina minimum of four (4) pieces.

8. ACCESSORIES

8.1. Nozzles/Couplings - All connections through the scrubber body shall be integrally attached flangedor coupling connections. Bulkhead fittings shall not be permitted.

8.2. Names Plates - Permanently attached equipment identification tags shall be supplied with thescrubber. Equipment labels shall include:

a. Equipment name.b. Equipment identification tag number.c. Design capacity, flow rate, static pressure loss (in mm wc).d. Name of manufacturer, model, and serial number.e. Date of manufacture8.3. Side View Windows - Viewing windows shall be supplied in each transition for visual inspection ofthe packing and the entrainment separator, between the packing and entrainment separator, betweeneach spray header, and at each end of the spray chamber. The view windows shall be fabricated oftransparent plastic like PMMA. .8.4. Pressure Gauge - A valved pressure gauge shall be provided in the scrubber recirculationpumping line after the pump discharge. The gauge shall be conveniently located to facilitate viewingfrom floor level. Each gauge shall be provided with a corrosion-resistant gauge guard. The pressuregauge connection shall include a PVC true union ball valve for gauge isolation. The pressure gaugeshall be Ashcroft/Wika/Forbes Marshall.

c. The piping leak test shall include filling the recirculation piping and visually inspecting forleaks. Leak testing shall be conducted for a minimum of four (4) hours. Hydraulic pressure test shouldbe done for MS pipes at 1.25 times the max. operating pressure.d. The scrubber shall be filled with water and the recirculation system operated for a minimum of six(6) hours to demonstrate proper operation of the liquid distribution system. The pump capacity andhead as well as proper distribution shall be verified.e. All test results shall be fully documented in writing and available upon request by the purchaser.f. After completion of testing, the scrubber and piping shall be completely drained of water andprepared for shipment.g. All the inspections and tests shall be done by supplier in the presence of departmentalengineer. At least one (1) week notice shall be given prior to inspection.

9. INSPECTION AND TESTING PRIOR TO SHIPMENT

9.1. Inspection -Inspection of all PVC-FRP components after fabrication and final cure as per ASTM D2563.

9.2. Compliance Check - Verification of scrubber dimensional accuracy with respect to approveddrawings.9.3. Repair - Unacceptable nonstructural defects shall be repaired by grinding out the defect andreapplying the corrosion barrier. Structural integrity shall not be violated during these repairs. Structuraldefect repair procedures shall be reviewed by the engineer:9.4. Testing - Testing shall be performed as described below and as necessary to ensure safe andreliable operation.

a. Pre-assembly for fit: The scrubber shall be completely assembled to ensure proper fit clearance,maintenance, access, etc. The number of pieces shipped disassembled shall be kept to a minimum,and each piece shall be clearly labelled for assembly. Detailed shop drawings shall accompany theshipment to aid in assembly.

b. All the joints and connections shall be leak tested. FRP coating wherever required shall be givenonly after welding the joints and leak testingl spark testing shall be carried out. Leak testing shall alsobe carried out for the complete system to ensure that there are no leaks.

... '10. PERFORMANCE OF THE SCRUBBER

The vendor shall demonstrate that the efficiency of the scrubber is better than 99% @ 2% NaOHconcentration and chlorine input of 80kg/hr as well as 1.6 kg/hr.

11. NOTE

11.1 General layout of the complete system is given in the enclosed sketch (Ref. DrawingNo: NFC/ZSP/Scrubber/PBS/Layout-01). which is indicative only. Overall dimensions of thearea earmarked for the system are also given in the sketch. Sketches and drawings etc.enclosed are indicative only. So all the tenderers are advised to visit the site and understandthe system and tender requirements perfectly before quoting.11.2 The layout of columns. tanks. pumps. blowers and piping shall be compact so thatthey can be erected within the space indicated in the layout sketch enclosed.11.3 All the PVC pipelines shall have a pressure rating of minimum 18 kg/cm2.11.4 Complete design along with drawing of the scrubber indicating all details shall besubmitted for approval before starting fabrication work.

12. BIDDER QUALIFICATION CRITERIA

12.1 Supplier should have the prior experience of Design, Manufacture. Supply. Erection &Commissioning of packed bed scrubber. Details of Packed Bed Scrubber already suppliedto clients should be given along with the offer so that the same can be verified along withthe performance.

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