Borehole Pumps Best Practises

Transcription

1 Borehole Pumps Best Practises When it has been identified that water should be abstracted for any reasons a Scope of Work should be developed. 1. Essential Steps when determining Scope. - Determine the amount of water to be pumped and then add comfortable % i.e. on small pump i.e. < 10 kw 50% can be added but the larger the pump the % can be reduced i.e. > 300 kw add 10% - Determine the Total dynamic head i.e. from pump outlet to discharge point vertically + friction - Do a Comprehensive Water analysis - Determine Ambient Temperature above ground as well as bottom of borehole Once you have these estimates. - Research the market to see what pumps and motors are available and very importantly consider the maximum Outside diameter of the pump & motor. Add 25% to this size to determine the casing size / borehole to be drilled ( inside diameter.) NOTE: The power cable must be taken into consideration as well. - Consider available power source versus cable size to be used between the Motor and the Electrical panel. The lower the voltage the longer, the larger and heavier the power cable. - Your equipment is as good as the equipment installed and care must be taken on the electrical installation. 2. Pipe Selection. Pipe selection is based on the following factors - Flow in pipe line of ± 2.5 meter per second - Weight of pump, motor, cable, pipe and electrical cable - NPSH (minimum submergence) of the pump must be considered for the total column length - Anticipated Surge - Safety factor 2 - Baseplate, lifting device - Safety factor 2 Borehole check sheets 1

2 1. Pump Selection. CHPPS Prefers Cast Pumps of Duplex for Mining applications. This give Abrasion and wear resistance. 2. Electrical Panel Design. - Application will determine most practical starting combination tied in with cable selection. i.e. o Direct on line = Full load amps x 8-15 o Soft Start = Full load Amps x 3-4 o VSD = Full load Amps x 1 NB: Pumps must Run Up 30 Hz under 5 seconds to protect bearings - Electrical Panel should have following mandatory functionality. o Run hour meter o Volt meters all phases o Amp meters all phases o Instantaneous trip o Under / over currant o Under / over voltage o Earth leakage o Reverse Phase o Phase imbalance o Phase loss o Surge arrestors o History logger all above Borehole check sheets 2

3 Recommendation to move from LV 400 or 550 v to MV 1, 3.3 or 6.6 kv after 250 kw and holes deeper than 300 m 3. Site Inspection 4. Preparation - Check Casing for sharp edges - Check base area - Borehole, Panel, Foundation strong enough to carry the load, flatness - Check source of power - Check lifting applications - Crane, Slings, I bolts ( shackles ) - Position Panel - Check motor integrity - Check pump & Shroud if applicable - Check tools - Check Installation Apparatus - Check fasteners & Seals - Check cable integrity 5. Start assembly - Fasten/Assemble Pump & Motor - Make electrical cable connection - Fasten installation base - Fit first ZSM pipe to pump - Show insert of chain when lifting device is inserted 6. Installation - Lift pump, motor evenly back and front (safely) - Insert into casing/hole & close clamp - Fetch ZSM pipe - lifting protocol - Fit O-rings - Rub Vaseline - Insert pipe - Insert chains - Close cover plate - Lift & Open clamps - Lower 1/3 and strap cables - Strap level sensor to pipe - Lower 1/3 and strap cables - Strap level sensor to pipe - Lower and grab with clamp 7. Check installation dispenser 8. Header works put completed or not necessary behind each point to mark accordingly Borehole check sheets 3

4 - Header works - Install ZSM to flange - Install 90 degree Bend - Install Air release & pressure transducer upstream - Install Maric Valve Selected 10% before Max Flow & lowest head - Spool piece pipe header works - Install full face or ring gasket - Install multi hole orifice plate - Spool piece pipe header works - Install Wafer Check valve - Spool piece pipe header works - Mag flow meter/ultrasonic flowmeter - Isolating Valve - Spool piece pipe header works - Pipe support brackets 9. Build Cable Rack - Connect Pump to Electrical Panel - Commission system according to component supplier check list. Borehole check sheets 4

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7 Dewatering System Borehole Checklists The check lists detailed in this document form an integral part of the Standard Operating Procedure (SOP) for the borehole section of the dewatering system at Frontier mine. The primary purpose of the lists is to guide role players, at all levels, through the process of installing, operating, monitoring and maintaining of the ground water pumping system. Detailed below is a model that shows the overall process of the SOP. The check lists will be detailed under each of the processes shown in the model. Ongoing: Analysis & no repeats Day 1 Preparation: Data capture, pump & motor Ongoing: Routine performance monitoring as per data sheet Day 1 On site assembly: Pump, motor & rising main Day 2: Installation & completion of first phase commissioning sheet Day 2: Site preparation and first lift Borehole check sheets 7

8 Day 1 1. Preparation: Data capture - pump and motor Pump end Date Pump model number All nuts present and tight Boreline adaptor fitted Pump to motor flange clean & undamaged Lead shields fitted correctly Strainer fitted correctly Coupling fitted to pump and in good condition Coupling (motor shaft cavity) greased Serial number: (also to be engraved on flange of last stage casing) Measure shaft height (flange to coupling thrust disc) Borehole check sheets 8

9 Motor Motor diameter 6 /150mm 8 /200 mm 10 /250 mm 12 /300 mm Measure motor shaft height Measure Axial play on shaft mm mm Shaft rotates by hand Yes No Filling solution to specification Yes No Filling solution topped up Yes No Motor (pump connecting flange) clean. NO PAINT, RUST OR FOREIGN MATERIAL. Diaphragm depth measured Yes mm Motor shell condition Good Bad Leaks (filling solution from motor) Top Bottom None Serial number Condition of motor lead out cables New Good Damaged: NB NO INSULATION TAPE No Winding resistance U (mohms) V (mohms) W (mohms) Insulation resistance U MOhms V MOhms W MOhms Borehole check sheets 9

10 Vertical assembly of pump and motor On site Pump end placed in crate or horizontal cradle. Secure with blocks (in crate) or Boreline straps (in cradle). Motor placed in reinforced crate or original crate as received from Original Equipment Manufacturer (OEM). Pump, motor & vertical cradle(s) loaded onto truck. Housekeeping container (rubbish bin) & tools loaded. Arrival at site: Co-ordination of activities and housekeeping. Team leader to determine best and most safe position for offloading and assembly of pump and motor. Offload vertical cradle(s). Remove motor from crate and securely clamp in vertical cradle. Motor shaft clean & lightly greased Lift pump end and fit to motor. Use only stainless steel bolts and nuts to secure the two. NUTS TO BE TIGHTENED EVENLY TO ENSURE ACCURATE ALIGNMENT OF PUMP & MOTOR. Motor leads are left out of the lead shields. Jointing of the cables is completed. Joints to be left for 24 hours to set. Pump discharge head removed and fitted to rising main. Riser pipe laid out Cable(s) laid out and inspected Cable(s) attached to riser per spec Dipper tube unrolled without kinks and crimps, ready for installation with riser pipe. Control cables, if fitted, to be rolled out and attached to rising main pipe. Additional security for the equipment to be arranged. Borehole check sheets 10

11 Day 2 Site preparation and first lift Housekeeping routines and safety presentation completed. Motor leads reinstalled in lead shields Cables and leads attached to riser First lift with discharge head only. Lowered onto pump which is still clamped in the vertical cradle. Discharge head fitted to the pumps and nuts tightened evenly. Ensure that OEM O ring is fitted. DO NOT USE SILICONE SEALER AS THIS CREATES A GAP BETWEEN THE MATING FACES. Pump unit lifted out of vertical cradle. Check: No tension on leads or cables, no snag points on cables and leads. Pump unit ready for installation. Installation and First Phase Commissioning Sufficient cable looping to prevent tension & rubbing on casing Cables checked for damage while lowering All OK Slight scuffs Damaged Dipper tube attached and no kinks or crimps found OK Replaced Insulation resistance reading: pump +/- 10m under water MOhms Insulation resistance reading After 50m MOhms Insulation resistance reading After 100m MOhms Insulation resistance reading After 150m MOhms Final insulation reading MOhms Pressure gauge and vacuum breaker assembly fitted Borehole check sheets 11

12 First Phase Commissioning Data Borehole reference details Date Time Completed by Water level Discharge pressure Motor speed Total hours Total m 3 pumped Insulation resistance Volts Current Phase1 Phase2 Phase3 Phase1 Phase2 Phase3 Pre-start Startup n/a +30mins n/a +2 hrs n/a +24 hrs n/a Borehole check sheets 12

13 Routine Performance Monitoring Performance parameters Date Q (m 3 /h RPM kw Amps Water level (m) Pressure gauge (bar) Dynam. head Pump TDH (m) Q (m 3 /h RPM kw Amps TDH (m) Trends Comments For new starts or repaired pumps data collected once a day for 1 week after installation. Once performance has stabilised, data collected every second day. Trends converted into graphical format and disseminated to dewatering team. Sub-standard performance will trigger Removal. Borehole check sheets 13

14 Removal All procedures completed as per Preparation for Transport and First Lift up to House-keeping routines completed. Pressure gauge and vacuum breaker assembly(ies) removed Lay-down of riser pipe planned and indicated to the team. Cables disconnected from VSD Lift to be done slowly and cable and dipper tube condition inspected for damage by two members of the team. All cable straps to be undone and placed in bin All cable ties to be cut with side cutters and placed in bin Photos taken of any fault conditions Pump and motor marked Date removed Borehole no. with permanent pen Motor serial no. Pump serial no. Pump unit secured in vertical cradle and riser pipe removed. DO NOT REMOVE PUMP DISCHARGE HEAD. Pump and motor separated, cables cut immediately ABOVE the cable joint Pump lowered to horizontal position & placed in mobile cradle. Motor placed in reinforced crate. Cables checked for damage or water ingress Cables or leads: OK Damaged Contain water Removed pump transported to workshop and repair process initiated by planner within 24 hours. Borehole check sheets 14

15 Unit placed in vertical position and pump and motor separated. Preliminary checks completed. Pump & motor removed from: On (date): Completed by: Date unit was installed: Months operating: Date Motor serial kw Shaft condition Coupling condition Flange condition Thrust housing Shaft height Diaphragm depth Fill solution Leads Meg Ohms Pump serial Model Shaft height Top bearing Strainer Scrap/repair All records analysed and data collated into a single document Document tabled at No Repeats meeting and preliminary findings put forward. Short-term and longer-term remedial actions agreed on and responsibility for implementation allocated Borehole check sheets 15

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