se4011 (d herron)

DAN HERRON DATE 03/04/16

MSc PROFESSIONAL ENGINEERING

CURRENT TECHNOLOGIES & APPLICATIONS SLUDGE TRANSFER PUMPING APPLICATION MODULE SE4011

CURRENT TECHNOLOGIES AND APPLICATIONS

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TABLE OF CONTENTS

GLOSSARY ................................................................................................ 3

LIST OF FIGURES AND TABLES .................................................................. 3

1. INTRODUCTION .................................................................................... 4 1.1 Selection Motive .......................................................................................... 4 1.2 Overview of Process ..................................................................................... 4 1.3 Key Aims ..................................................................................................... 5

2. SLUDGE PUMPING PROCESS CONDITIONS ............................................. 6

3. CURRENT PUMPING TECHNOLOGY ANALYSIS ......................................... 8 3.1 Positive Displacement - Progressive Cavity Pumps .......................................... 8 3.2 Pump Specification – MONO Compact C18A ................................................ 10 3.3 Investigation Justification ........................................................................... 10

4. ALTERNATIVE SLUDGE TRANSFER METHODS ........................................ 12 4.1 Positive Displacement Pumps ...................................................................... 12 4.2 Centrifugal Pumps ..................................................................................... 13 4.3 UK Utility Companies and NWG Different Opinions/Methods ........................ 14

5. RECOMMENDATIONS .......................................................................... 16 5.1 Grit/Silt Management Techniques ............................................................... 16 5.2 Practical Limitations ................................................................................... 16 5.3 Professional Limitations .............................................................................. 16 5.4 Recommendations for Pump Selection ......................................................... 17

6. CONCLUSION ..................................................................................... 18

7. REFERENCES ...................................................................................... 19

8. BIBLIOGRAPHY .................................................................................... 21

APPENDIX 1 – NWG SCADA REPRESENTATION – SLUDGE PROCESS .......... 22

APPENDIX 2 – WARKWORTH SLUDGE THICKNESS SAMPLES ...................... 23

APPENDIX 3 – SEEPEX SPLIT ROTOR/STATOR DESIGN .............................. 24

APPENDIX 4 – WARKWORTH PSP PERFORMANCE DATA ............................ 25

APPENDIX 5 – NWG JOB HISTORY ON WARKWORTH PSP’S ....................... 26

APPENDIX 6 – QUESTIONNAIRE FOR DIFFERENT UTILITY COMPANIES ...... 27


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GLOSSARY GAC Gravity Activated Carbon NWG Northumbrian Water Group N.D. No Date PAC Powdered Activated Carbon PCP Progressive Cavity Pump Poly Polyelectrolyte (Binding process to thicken sludge) PS Primary Sludge PDP Positive Displacement Pump PSP Primary Sludge Pump RCM Reliability Centered Maintenance RGF Rapid Gravity Filters SCADA Supervision, Control and Data Acquisition – electronic system that demonstrates various

processes throughout the site, system has automated control or manual user desktop inputs.

VSD Variable Speed Drive WTW Water Treatment Works

LIST OF FIGURES AND TABLES Figure 1 Warkworth Site Layout Figure 2 Warkworth Sludge Treatment Process Figure 3 Sludge Thickness Calculations Figure 4 Water Treatment Process Diagram Figure 5 Worn v New Pump Stator Photos Figure 6 Progressive Cavity Pump Basics Figure 7 Rotor/Stator and Abrasive Particles Diagram Figure 8 Speed v Abrasion Test Figure 9 Warkworth PSP Drawing Figure 10 PD v Centrifugal Pump Comparison Figure 11 Brainstorming Abrasion Measures Figure 12 Brainstorming Potential Pump Modifications Table 1 PSPs Overall Cost in 11 year Period Table 2 Relative Positive Displacement Pump Analysis Table 3 Strongest Theme Answers from Questionnaire Table 4 System Recommendations Evaluation


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1. INTRODUCTION

1.1 Selection Motive After stressing the desire to develop my professional understanding within the ever-changing utilities business, I opted to analyse systems/processes that are particularly troublesome from a maintenance and operational perspective. The Primary Sludge transfer system at Warkworth WTW has historically cost NWG valuable time/money through constant breakdowns. It would appear the abrasive composition of the sludge is incompatible with the current pumping equipment. This excessive abrasion in the system is thought to be the key factor causing the significant wearing of rotor/stator parts in the progressive cavity pumps. Thus wasting valuable maintenance/operational time, and incurring large capital costs for vital spares. This study was selected to address the issues highlighted with the two Primary Sludge pumps at Warkworth WTW, intending on producing feasible solutions/recommendations.

1.2 Overview of Process Primary Sludge systems are essential for WTW’s; it allows the production plant to transfer the ‘after product’ of water treatment, to the sludge treatment plant. It is imperative at least one pump in the system is available; otherwise the sludge tanks would overflow or require emergency tanker removal at high cost to the business. The Primary Sludge on a WTW is mainly composed of backwash slurry/debris and sand from the sediment and GAC filters. It is imperative that a steady flow is delivered from the PSP’s, to allow even mixing during the sludge thickening process.

Figure 1 is a layout drawing of Warkworth WTW; it shows location of the Primary Sludge Pumps and the distance they pump to the ‘Press Building’ (Highlighted in Red). Estimated linear distance is around 250m, approximate height difference between Primary pumps and thickener tank is 3.5m. The basic Key Stages of the Sludge treatment process at Warkworth are as follows; Sludge Holding Tank, Primary Sludge Pumps, Sludge Thickener (Poly), Buffer Tank, Filter Press and finally taken by

PRIMARY SLUDGE PUMPS

Figure 1 - Warkworth Site Layout (Source: NWG Technical Drawings)


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tractor for agricultural spreading. Appendix 1 is a NWG ‘Scada’ flow chart, to represent where the sludge/wash water comes from, and the subsequent methods of treatment. The sludge process is only one key stage in the treatment of river water at Warkworth WTW. Figures 2 and 4 demonstrate the key treatment principles in the process, all being essentially critical for highest quality production. In basic terms, water passes through several filters to remove solids and bacteria (producing waste by-product of sludge), before finally having the relevant chemicals applied to correct pH and disinfect water before distribution to the public.

1.3 Key Aims The key intentions of this investigation is to demonstrate the following: • Technically broaden knowledge of engineering, scientific and mathematical principles

surrounding sludge pumping techniques. • Examine technology currently utilised; assess how if functions and performs. • Analyse all investigation data, providing recommendations for future installations. Expected benefits of the study are: • Improve technical understanding of technology available for sludge transfer in the utilities

industry. • Technical deepening of the scientific principles surrounding sludge pumping techniques. • Enhance technical knowledge of pumping systems for future installations. • Understand the practical and professional limitations that apply to sludge pumping techniques. • Provide Warkworth with several solutions/recommendations for moving forward in the future. Throughout the main body of this report, I will describe my reflective thoughts and initial actions in clear segregation of the report facts. They will be highlighted exactly as this passage; this excludes the ‘Conclusion’ – a reflective passage alone.


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2. SLUDGE PUMPING PROCESS CONDITIONS My first action for understanding the process conditions: consulting the senior process technician. His valuable knowledge provided key information surrounding the operating process; I applied this knowledge and coupled it with literature research to form opinions on the subject.

Figure 2 demonstrates the process arrangement for treating the sludge at Warkworth WTW, ‘arrow 32’ in the diagram is the key focus of this investigation. Primary sludge is typically a very low percentage of thickness; the value is dependent various different factors including wash-water volumes and other incoming plant sludge. Punmia et al (1998, p. 479) state, “Typical solids concentration in raw primary sludge are 6 – 8%”. The Author selected 3-months of Warkworth samples in attempt to demonstrate average conditions; please see Appendix 2 for the full sample data. Key statistics to note from the sample data; 3-month average primary sludge thickness was 4.69%, the 3-month average value of flow was 14.94m!/H. Interestingly, the average thickness sample is slightly less than the ‘typical’ primary sludge value provided by Punmia. After consulting the senior process technician, he suggests it is considerably thinner because of the sediment and GAC filter backwash-water, and is also arguably the cause of abrasion within the system. Sludge density/thickness is continually measured by automatic instrumentation; the sludge percentage accuracy is solely dependent on the accuracy of this equipment. Instrument technicians, to ensure the reliability of their outputs, continually calibrate them. Figure 3 demonstrates the manual method of calculating sludge density when different sludge’s are combined, typically utilised when instrumentation is out of service. The instrumentation can quantify the sludge thickness; Sand/Carbon will contribute to this percentage. Instrumentation cannot demonstrate the presence of abrasive material within the sludge, the sharp and hard composition of sand/carbon particles is undetectable – however are clearly visible when equipment failure occurs.

Figure 3 - Sludge Thickness Calculat ion (Source: Price 1998, p. 108)

Figure 2 - Warkworth Sludge Treatment Process (Source: NWG Technical Drawings )


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Figure 4 - Water Treatment Process Diagram (Source: Pizzi 2010, p. 107)

The process diagram in Figure 4, demonstrates a basic layout of the water treatment process in stages. The key outputs to focus on for this investigation are; ‘Wash Water’ and ‘Sludge’. These two are combined in Warkworth’s sludge holding tank, awaiting transferring to the sludge treatment plant – by the Primary Sludge Pumps. It is widely assumed that the abrasive nature within the primary sludge is a result of sand and carbon presence in the wash water. Wash water in this instance is used to clean the sediment/GAC filters, ensuring bacteria is not present, however the by-product of this process is thought to considerably hinder the sludge treatment process.

The photographs in Figure 5 are evidence of the abrasive wear apparent in the primary sludge system. On the left is a ‘Rotor’ removed from one of Warkworth’s PSP’s, on the right is the new replacement before installation. The abrasive nature of the PS has caused the majority of chrome finish to wear off, and cut considerable grooves into the steel, thus resulting in the pumps not performing. Information on configuration of the pump ‘stator’ is available in Chapter 3.

Figure 5 - Worn v New Pump Rotor Photos (Source: Author)

Deep scores on Rotor

Chrome worn off


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3. CURRENT PUMPING TECHNOLOGY ANALYSIS When analysing the current pumping system, I decided to obtain manufacturers information on performance under ‘ideal conditions’. It was my objective to compare this information against the on-site performance, and demonstrate the costs to the business. When discussing the issues with experienced engineers within NWG, it was clear that this issue has been highlighted before, and never resolved. This suggests a possible knowledge gap, or lack of interest to take on the challenge of providing a solution. This possibly reflects a lack of ownership between Maintenance/Operational teams, suggests a failing in the working system – it is likely an issue between budget allocation.

3.1 Positive Displacement - Progressive Cavity Pumps Warkworth’s current primary sludge pumping technique is a particular method known as a ‘Positive Displacement’; Progressive Cavity pumps are a specific type of Positive Displacement pump. Positive displacement pumps essentially move a fluid by isolating a fixed volume, and forcing/displacing the trapped liquid into discharge pipework; either by rotating components or linear moving rams. They are particularly desirable for long pumping distance, high-pressure heads and steady flow delivery. Figure 6 is a diagram to demonstrate the basic pumping principles for progressive cavity application. Continental Ultra Pumps (2015, pg. 1) state that: “Abrasive fluids can significantly shorten the life of the stator.” Huskey (N.D., pg. 9) describes “the big three” critical influences in the application of PCPs as being: Abrasion, Temperature and Viscosity. This investigation focuses on one of those three key influences; Abrasion. Huskey (N.D., pg. 10) also continues to describe the conditions and influences surrounding abrasive wear:

• Wear is proportional to shaft speed, reduce the speed to reduce wear.

• Reduce pressure per pump stage (Minimise slippage between rotor and stator). • Select oversized rotor, increases interference fit and equals longer life span (Less Slippage). • Select specific abrasion resistant stator material, e.g. RM 100M, RM 103 or Urethane. • Double chrome rotor for extra base protection.

Vetter and Wirth (1993) conducted a very extensive experiment, investigating characteristics of PCPs and methods to avoid abrasive wear when designing a system. Their investigation covered a range of different tests to analyse performance, power, efficiency and resistance to wear. Similar to Huskey (N.D.), they highlighted rotor interference fit as influential to the amount of abrasive wear on the moving components. Examine Figure 7 and note the ‘sealing line’, this is a fluid gap generated by the

Figure 6 - Progressive Cavity Pump Basics (Source: Continental Ultra Pumps 2015, pg.1)

Figure 7 - Rotor/Stator and Abrasive Part icles Diagram (Source: Vetter & Wirth, 1993 pg. 55)


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viscous material being pumped. Theory surrounding this thin film of fluid, suggests it aids with protecting against abrasive wear; thus rejecting material labeled ‘f’ in Figure 7. However when increasing speed rate, or introducing abnormal rotation patterns (i.e. bearing/gearbox failure) the fluid film is eradicated in areas. This allows larger suspended solids within the fluid, to have direct exposure onto the wearing components, this process is known as slippage. It is also understood that the protective fluid film, cannot be generated if the gap between rotor-stator is too large. The hydrodynamic principles of the slippage issues suggest, a differential pressure between cavities removes the fluid film – particularly occurring in startup, as cavity pressures differ in this situation. More wear results in a larger gap, proportionally increasing slippage further. Within the investigation they conducted an experiment directly analysing wear, using quartz particles at diameter 15μm. They compared perfect rotation within the abrasive fluid (B ), against a slightly oscillating rotation (A) (Exactly as a PCP on site) and measured the wear relative to speed. Figure 8 depicts the results; it is evident that the fluid film protects the perfect rotational components from any major wear. Looking at data from line ‘A’, it is would suggest that there is little protection due to the offset rotation. Moreover it would appear that speed does proportionally increase wear to the rotor, thus supporting Huskeys original statement. In a more recent study Whittaker (2003) completed more tests surrounding abrasive wear on PCPs. She believes that for every size of pump, there is one critical particle size range that will create maximum damage to the pump components. As all other literature stated, rotational speed of the pump is heavily correlated the amount of abrasive wear on the rotor/stator. Interestingly, she discovered the coating of the rotor had no relation to the abrasive wear. The main conclusion to note was: “Reducing the contact pressure between the rotor/stator was found to have a detrimental effect on both components. It increased the width of, and the amount of particles embedded in, the type a and b stator wear regimes which consequently increased the width of the wear bands on the rotor (Whittaker 2003, p. 188).” After analysing the reviewed evidence, there are several options to consider if PCPs are the equipment of choice moving forward with Warkworth’s PSPs. Firstly, selecting an oversized PCP would be advisable, thus reducing the required rotational speed, in turn reducing abrasive wear. Secondly, a slightly larger PCP, with an oversized rotor, applying literature theory that increasing the contact pressure – will reduce abrasive wear. This option may also create minor maintenance issues however. Progressive Cavity Pumps Analysis SOURCE ADVANTAGES DISADVANTAGES PC Pumps (2015) • Low operating costs.

• Can pump very high viscosity fluids. • Ability to pump high concentrations of solids.

• Limited production rates • Restricted lift height • Rotor and Stator Wear

Figure 8 - Speed v Abrasion Test (Source: Vetter & Wirth 1993, pg. 57)

A

B


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PetroWiki (2015) • Moderate Cost • Low Profile • Handle sand and viscous fluid well. • High electrical efficiency.

• Elastomers in stator swell in some fluids. • Pumps off control is difficult. Lose efficiency

with depth. • Rotors and stators wear considerably.

Author Opinion (2016)

• Steady flow rate. • Can pump very viscous fluids. • Will pump solids well if correctly designed. • Cheap operating costs.

• Awkward to overhaul from maintenance perspective (Working alone).

• Very problematic if designed incorrectly. • Replacement components are expensive.

Looking objectively from a maintenance perspective, selecting an oversized pump appears a good option to reduce abrasive wear. It is my opinion however, that abrasive wear can only be minimised and not eradicated. Therefore I would prefer to recommend installing equipment that is easily maintained after abrasive damage. Speaking from experience with PCP’s and abrasive sludge, I would select a ‘Seepex’ PCPs every single time. Why? Their bespoke design is unrivaled in speed and efficiency during maintenance activities. Reduction of working hours and production downtime is an imperative aim for this investigation. Appendix 3 contains more expansive diagrams explaining the concept of a split rotor/stator, Seepex state: “this design makes replacement of rotor/stator up to 85% faster” (Seepex, 2016 p. 3).

3.2 Pump Specification – MONO Compact C18A The PSP’s at Warkworth are ‘Mono-bloc Compact Range’ progressive cavity pumps. Performance data for the current pumps is located in Appendix 4. Figure 9 gives a visual representation of the PCP’s installed at Warkworth. The key details of the equipment to note are as follows: • Linear pumping distance of approximately

250m, a height differential of 3.5m and outlet pipe size of 100mm.

• Sludge average thickness (from investigation sample range) is 4.69%, with an average flow rate of 14.94 m!/H . Performance data from the charts in Appendix 4 suggests the viscosity is approximately 80strokes – a typically medium-high abrasion rating (Demonstrated by RED lines).

• Pump has VSD fitted with a 4KW motor, motor speed ranges from 107-740rpm on 11-77Hz scale. Shaft speed is reduced by gearbox of ratio 2.94/1, reducing the shaft speed range to 36.4-251.7rpm.

3.3 Investigation Justification The PSPs at Warkworth WTW have been constantly problematic from a Maintenance perspective and are often described as “unfit for purpose”. From a business perspective however, we must understand the financial and efficiency impact they have on NWG. Appendix 5 represents the reported jobs on the PSPs between 23/09/2004 to 09/10/2015. Combining the data, it shows that 516.91 hours of work have been completed on the PSPs in that 11+ years period. When analysing the reported tasks, a very high majority of the issues are caused by the abrasive wear. A cost of

Figure 9 - Warkworth PSP Drawing (Source: Mono, 2014 Sect ion 4 pg. 1)


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£1681.92 is incurred each time the pump is worn beyond repair (assuming no gearbox/motor damage), quotation documents are available but seem irrelevant to include in the report. Table 1 represents the overall financial implications from the PSP in that sample period. Calculated by charging the relevant technician repair rate to the hours spent, and adding the relevant spares required to solve the issue.

!

Primary'Sludge'Pump'1'

Primary'Sludge'Pump'2' Overall'10'Year'Combined'Cost'(£)'

Maintenance'Labour'Cost'(£)' 8693.03! 6906.74!!Maintenance'Parts'Cost'(£)' 26798.75! 20103.36!!Total'Costs'(£)' 35491.78' 27010.1' 62501.88'

Table 1 - PSPs Overall Cost in 11year Period (Source: NWG Internal Job Costing System)

It is very clear that the PSPs are causing significant issues to NWG; incurring £62501.88 over an 11 year period is unacceptable. Considering maintenance efficiency, it could also be argued that 516.91 hours of work would not be required if the equipment was fit for purpose. It was essential to demonstrate why this issue required addressing; the figures in Table 1 are ‘how’ this issue is highlighted. The approach intended to quantify cost and time to the business, because they are key measures of efficiency. The difference of costs incurred between pump 1 and 2 is significant, there may be several reasons for this. The most probable reason would be duty rotation from an operational perspective, for example pump 1 is normal duty with 2 running as a spare for maintenance downtime. This could be resolved through an auto-duty rotate system. Alternatively it could be a result of inlet pipework arrangement, causing difference between the volumes of sand/silt able to enter each pipe (Solids may gather naturally around pump 1’s inlet in the sludge tank). This is however speculation, it would be interesting to investigate this difference further in the future. Drawing conclusions from the investigation so far does force questioning the original design. Why were these theories not considered originally? Depending on the original installer, it could be argued the system was designed to shorten the lifespan of wearing components, thus requiring NWG to purchase more from suppliers. Or it could also be complete naivety in the design process. Regardless of the reason, the issues still require resolving. After completing this section of the investigation, I was very surprised at my findings. In fact I was overwhelmed with how much I had learned about Progressive Cavity Pumps. The research and investigation data has allowed me to be confident in what I would recommend regarding PCPs. Before I began this study I would state that I knew a considerable amount about PCPs, this investigation has demonstrated that I knew very little actually. Moreover I was interested to further deepen my knowledge of Primary Sludge pumping through different methods in the forthcoming chapter. So far, I have been very pleased with the investigation work – especially regarding the questions I have raised with the original system. This further enhances my reflective nature as an engineer.


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4. ALTERNATIVE SLUDGE TRANSFER METHODS In this section of the study, I was very eager to learn what other industries considered best practice for Primary Sludge Pumping. I was also intrigued to discover what type of Primary Sludge Pumping systems other UK Utility companies utilise. My intention was to gather wide range of opinions from different sources and industries, and provide an alternative recommendation to the current system. I also opted to briefly analyse different WTWs within NWG, to evaluate different PSP styles within the same organisation.

4.1 Positive Displacement Pumps PDP PUMP TYPE ADVANTAGES DISADVANTAGES LOBE • Pass medium solids and abrasives.

• No metal-to-metal contact. • Positive suction, non-pulsating output. • Bi-directional.

• Reduced suction capability with thin liquid. • Requires timing gears and two seals. • Overhung Load on shafts.

INTERNAL GEAR • Only 2 moving parts, 1 shaft to seal. • Non-pulsating flow, Bi-Directional. • Easy to maintain, handles abrasives. • Flexible design offers application

customization

• Larger pumps usually require reduced speeds

• One bearing runs in process fluid. • Overhung load on the rotor shaft.

DIAPHRAGM • No shaft seal required. • Handles solids and abrasives well. • Inexpensive.

• Pulsing flow. • Discharge limited to motor/air supply

capacity. Table 2 - Relevant Positive Displacement Pump Analysis (Source: Petersen, N.D. p. 2-7)

A positive displacement pump appears the logical selection for Warkworth’s’ PS, due to the long pumping distance, height differential and steady flow rate required. Which type of Positive Displacement Pump? And Why? Are key questions to ask. Table 2 represents information collated in a research project on the selection of Positive Displacement pumps; all advantages/disadvantages are relative to the equipment type. However in an ever-changing environment with new technology, manufacturers are very competitive in terms of marketing their products. Which evidently, makes it very hard to select the correct equipment for application. Extensive research of different PD pump manufacturers resulted as expected. Different Progressive Cavity, Diaphragm and internal gear pumps were all very capable in the application of pumping abrasive sludge. Grzina et al (2002, Section 9 p. 2) state, “The final textbook for optimum slurry pump design is yet to be written and even powerful computer programs are just beginning to approach this goal. Personal knowledge and past experience is much more important in the design of slurry than of water pumps.” I concur; gathering past experience and advice appears to be the best method of obtaining ‘best practice’ for Primary Sludge Pumping. Evidence would suggest that there are many capable products available to pump abrasive sludge, however gathering opinions/recommendations from experience appear to aid in their selection.


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4.2 Centrifugal Pumps It is important to consider Centrifugal pumps in the investigation, even if they aren’t typical practice for Warkworth’s particular sludge system. Although centrifugal pumps would not be labeled useless in this application, they could compromise efficiency. It is also feared that flow rate could be inconsistent over that distance, thus affecting the thickening process.

Figure 10 represents the comparison between PD and centrifugal pumps, and demonstrates why PD pumps are the preferred method at Warkworth. The ‘Performance’ graph compares the flow capacity with change in head, clearly showing PD pumps maintain the imperative steady flow rate. Flow rates and viscosity are also considered, again demonstrating superiority of PD pumps with any viscous materials. Comparing efficiency and head height, the centrifugal pump begins to deteriorate when the head is too large; PD pumps are also stronger in this comparison. Although Centrifugal pumps aren’t the key selection for Warkworth WTW, there are some excellent designs that are very capable to pump abrasive material. These designs are worth considering, as the option could be available in the future, depending on extensive system alterations. An interesting article produced by Water and Wastewater Treatment Magazine (2013) reviewed United Utilities success on overcoming pumping grit/solids at one of their particular sites. Albeit a sewage pump, the principles of transferring abrasive material remains similar. It states: “the only maintenance that these grit pumps require is the occasional replacement of the mechanical seals.” The article focused on a particular pump model ‘WEMCO’ – designed by Weir Pumps. According to the literature, they appear to have various methods to solve abrasive pumping issues. Goulds SRL centrifugal pumps are another adapted design; they also claim to provide equipment that handles the pumping of ‘sand and gravels’. A key design benefit is a larger diameter semi-open impeller, running at slower speeds to reduce abrasive wear. “The SRL is built to stand up to the toughest services, while providing maximum reliability and extreme ease of maintenance.” Goulds Pumps (2015, pp. 2,5). Centrifugal pumps are clearly available to handle heavily abrasive fluids; however a tentative approach should be taken when selecting products from manufacturers sales brochures. If the Centrifugal option were more feasible for Warkworth, more in-depth research would be completed.

Figure 10 - PD v Centrifugal Pump Comparison (Source: Pump School, p. 1)


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4.3 UK Utility Companies and NWG Different Opinions/Methods In this section, I composed a selection of questions surrounding PS pumping techniques. I sent a blanket email to all other UK Utilities companies, requesting answers to my investigation questions. This was an attempt to gain insight into how other Water companies operate relative to Primary Sludge Pumping. I also asked the same questions of different WTW managers within NWG. Taking Ethics into consideration, all persons questioned were specifically asked if their information could be documented in this report. The questions I composed for the UK’s other Utility Companies and NWG’s other site managers are as follows: 1. What type of pumps do you use for Primary Sludge Pumping on your Water Treatment Works? 2. Do you suffer with abrasive wear on your equipment? 3. Can your provide me with details of your primary sludge system and pump specification? 4. Does your sludge system incorporate wash water from sediment filters? 5. Do you have any special measures to counteract abrasion within your Primary Sludge Pumps? Appendix 6 contains a detailed information table, consisting of answers received from the other UK water providers and two separate NWG sites. All companies were asked the same matrix of questions, in attempt to keep the data range as accurate as possible. The data clearly shows a trend in most popular PSP types; Progressive Cavity pumps are by far the most common between the evidence collected, second were hydraulic RAM pumps. Centrifugal and diaphragm pumps are apparent, obviously depending on their bespoke system arrangements – significant modifications are required to install at Warkworth. All specifications appear different also, resulting in more ambiguous further recommendations. Selecting ‘best practice’ from this data is onerous; it is advisable to apply the equipment that best suits the current system arrangement. Measuring the amount of abrasive wear is difficult; it is all relative to normal operation and experience. Evidence suggests that having grit measures could be beneficial, although this would require considerable capital investment from NWG. Evidently it appears dosing powdered carbon significantly increases wear at Broken Scar, clearly supported by the issues apparent at Warkworth. Most interesting of all the evidence is the counteraction to abrasion, RCM and Lean methodologies, grit removal, different materials selection and filter backwash monitoring. All methods appear feasible to apply without major constraint; these could be incorporated with recommendations for equipment replacement/upgrade. In reflection of this evidence gathering process; the results are interesting, although some not entirely conclusive. Exceptions are: PCP’s appear the most popular method for Primary sludge transfer, and GAC/PAC significantly increases equipment wear. The majority of data incorporates sediment filter backwash in the sludge system, this however correlates inconclusively with the relative diagnosis of ‘excessive wear’. Why? It would appear the opinions of ‘excessive wear’ seem to differ; predictably this will always be the case with human nature. Methods to minimise abrasion, are strong testament to the importance of gathering different opinions. This provides a wider scope on the consideration of ‘best practice’, thus strengthening future recommendations. Summary Table 4 represents the key answer themes across the questionnaire matrix.


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Common Themed Answers 1. Primarily Progressive cavity pumps and secondly RAM pumps. 2. Very mixed responses as discussed, ‘excessive wear’ is open to personal interpretation. 3. Hard to provide particular specifics, ones provided described ‘Mono’ progressive cavity pumps. 4. Every returned questionnaire incorporated sediment filter backwash-water. 5. The majority of companies have implemented a various range of methods to reduce the amount

of abrasive wear in their equipment. Table 3 - Strongest Theme Answers from Questionnaire

I was very pleased with the positive input I received from the UK’s other utility companies and other NWG sites. I was pleased that ‘Welsh Water’ shared my preference for Seepex PCP’s. I suspect the preference will particularly apply to maintenance personnel, rather than on a managerial level. It would be interesting to compare the initial capital cost of Mono and Seepex, and their operational efficiency – perhaps future work for this investigation.


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5. RECOMMENDATIONS When providing recommendations, I had to be very considerate of several limitations surrounding the current system and business constraints. In reflection, I have collected a lot of important information to provide strong recommendations, also developing my own skills and knowledge throughout this investigation process. After evaluating the evidence gathered throughout the investigation, there are several options to consider for improving Warkworth’s Primary Sludge system. Each option would require different a modification in unique ways – some are cheaper/easier, some expensive and complicated. It is important to think logically in terms of cost versus benefit to the business, the thought rationale (Of the Author) for evaluating these choices can be seen in Figures 11 and 12.

5.1 Grit/Silt Management Techniques The evidence taken from the grit-management brainstorming task (Figure 11) was incorporated from other utility companies – essentially consisting of their best practice. Raising awareness for reducing amounts of sand/GAC being washed into the sludge system would be very beneficial, could also highlight any methods/ideas within the team for reducing the magnitude of abrasion. Application of RCM techniques for the equipment would also be beneficial when considering breakdown costs. A bespoke brief and procedure would be required; this would be modeled against the pump during planned maintenance – providing indication of abrasive wear on the equipment. Installing grit removal equipment would significantly reduce abrasive wear, however the capital installation cost would require comparison to PSP costing – to assess the feasibility of an extra system to protect the PSP’s.

5.2 Practical Limitations • Pipework and panel modifications. • Process arrangements for thickening. • Plant downtime during upgrades. • Installation of grit removal equipment, physical dimensions of space.

5.3 Professional Limitations • Limited to companies/equipment to be installed off NWG’s contractor framework. • Presenting the justification for changes, persuading decision makers on improvements. • Obtaining funds to complete recommendations. • Considering social factors, reducing workload – potentially affecting job security. • Demonstrating the importance of abrasive sludge monitoring to field teams.

Figure 12 - Brainstorming Abrasion Measures (Source: Author)

Figure 12 - Brainstorming Potentia l Pump Modifications (Source: Author)


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5.4 Recommendations for Pump Selection A comprehensive range of research and investigation data was completed, to analyse primary sludge pumping methods. All methods were essential in evaluating ‘best practice’ for pumping abrasive sludge; this information narrowed the recommendations to three feasible options when considering the process conditions:

• Progressive Cavity Pumps • Diaphragm Pumps • Centrifugal Pumps

All three methods will require bespoke modifications, and all incurring different cost to the business. Advantages and disadvantages of each method have been evaluated; they are available in Table 3.

Potential System Modifications SUGGESTION ADVANTAGES DISADVANTAGES

Install larger Progressive Cavity Pumps (Preferably Seepex with split Rotors/stators), reducing the running speed and proportionally reducing wear.

Small pipework modifications required to install. Very efficient pumping method, less wear at a slower speed – theoretically. Constant flow rate, good for current thickening mix process.

Are susceptible to slippage wear when starting up.

Install diaphragm pumps, best equipment for minimal abrasive wearing.

Excellent at pumping abrasive material. Cheaper replacement parts, less wearing components.

Give a pulsating flow when pumping, affecting the thickening process. Would require altering the poly, thickening and mixing process. Considerable pipework modifications.

Install centrifugal pumps, very capable at pumping abrasive material for limited distances/heads.

Reliable equipment, handle abrasive sludge very well.

Would require extensive modification to sludge holding tanks, or sludge press location.

Table 4 - System Recommendations Evaluation

Considering the Diaphragm pump proposal, this would be a very sensible option in terms of reducing abrasive wear. This system however, would require considerable modification to the thickening process. Pulsating flows from the pumps would cause the sludge flocculation mix to be inconsistent, affecting the process – therefore the mixing arrangement with the poly would require modifying for this proposal. The proposal for installing Centrifugal pumps is arguably the least feasible of the three. It is important to consider the effectiveness of this pump for abrasive sludge, however the civil, mechanical and electrical modifications appear large/complicated. Modifications would require re-location of sludge holding tanks, or sludge treatment press equipment. The injection of initial funds, would far outweigh the benefit for this study, estimated figures could potentially escalate into the millions – rendering the proposal, somewhat unrealistic. Looking objectively at the three proposals, installing larger Progressive Cavity Pumps appears the most sensible solution to the issue. Reasons why: As mentioned earlier, speed is proportional to wear with PCP’s. Installing larger pumps would considerably reduce the wear of moving components. Very minimal pipework modifications would be required for this installation; the main capital investment would be the new pumps and VSD’s. No extra modification would be required to accommodate the pumps within the process, only configuring flow rates to ensure the correct sludge thickening mixture. The abrasive nature of sludge will always be apparent, but hopefully reduced; therefore from a maintenance perspective it is important to consider the simplest equipment to maintain. This would clearly be Seepex split rotor/stator PCP – for a positive impact on reducing maintenance repair times.


18

6. CONCLUSION In reflection, my knowledge surrounding abrasive sludge pumping was minimal. Initially I considered myself to have extensive knowledge on PCP’s, it became clearly evident I knew very little throughout this investigation. This study has allowed me to technically enhance knowledge in areas I considered strong, also broadening in areas that required it. Conducting the investigation has technically enhanced my knowledge of various abrasive pumping methods, and their application. It has highlighted key improvements available, through practical and professional methods. Applying the relevant practical equipment, lean maintenance activities and field team training – could potentially make the business more efficient in terms of cost and time. Completing this module has aided my professional development as an engineer in three key ways: • Reflection and analysis of positive/negative aspects during an investigation. • Improved Investigation Skills – research and analysis, gathering qualitative and quantitative data. • Management of time – had small personal commitments that slowed the investigation, against my

wishes. This provided key motivation to stick to my planning schedules rigidly. I would have preferred to conduct an experiment, consisting of different percentages of abrasive material – with various pumping methods. In attempt analyse performance in those conditions, and provide my own compiled results. Unfortunately time and cost constraints concluded this process, channeling me towards looking at best practice between literature and other businesses. When gathering data for the investigation, I learned to be very cautious when obtaining it from manufacturers. They have a tendency to verbally enhance their equipment’s capabilities; this is human nature from a sales perspective. Therefore I decided to focus on data coming from personal experience, incorporating their process and maintenance issues provides clearer understanding of potential performance. I regret not widening the scope of my ‘questionnaire data’, particularly into separate industries. In hindsight I should have collected data from other countries, those claiming to be ‘world leaders’ and different industries e.g. oil and gas. I could also have made the questions slightly more specific, allowing for a more concise collection of data. Another improvement I would include if investigating again, would be to allocate time to research into grit/silt management techniques for best practice. I learned considerable amounts about my learning style. Instead of gathering the majority of the data initially, I tend to be unorthodox and enhance areas I wish to develop throughout the investigation. Sometimes I would write the report, and improve areas I feel lack engrossing or required technical content. It would be interesting to attempt another approach in future modules, although I feel my current method allows me to question the investigation information at every opportunity. As an engineer, questioning ‘why’ is an underpinning principle in my thought process. This investigation highlights the importance of having senior Mechanical Engineers within NWG, knowledge is key when designing an important process – the pumps in question are possibly a result of inadequate design/knowledge. The investigation has given me a positive outlook; I feel I can make a difference to the business when studying modules. I now face the challenge of having the recommendations delivered, and contributing the knowledge to further PCP projects.


19

7. REFERENCES Continental Ultra Pumps (2016) How Progressive Cavity Pumps Work. [Online] Available at: http://www.continentalultrapumps.com/store/kcfinder/upload/files/Pump%20Guide(2).pdf (Accessed: December 2015). Goulds Pumps (2015) Goulds SRL – Designed for Abrasive and Corrosive Slurry Services. Internal Brochure: Goulds Pumps. Unpublished. Grzina, A., Roudnev, A., Burgess, K. E. (2002) Slurry Pumping Manual. Internal Manual: Weir Group PLC. Unpublished. Huskey, C. (N.D.) Maintenance and Trouble Shooting of Progressive Cavity Pumps. [Online] Available at: https://www.cwea.org/sarbs/pdfs/Huskey_Maintenance%20and%20Troubleshooting%20of%20Progressive%20Cavity%20Pumps.pdf (Accessed: January 2016). Mono (2014) Compact Range – Installation, Operation and Maintenance Instructions. Internal Manual: Mono Pumps. Unpublished. PC Pumps (2015) PCP Systems. [Online] Available at: http://www.pc-pump.com/pcp-systems (Accessed: January 2016). Petersen, J. E. (N.D.) Best Practices in Selecting and Applying Positive Displacement Pumps. Internal Report: Viking Pump Inc. Unpublished. PetroWiki (2015) Relative Advantages and Disadvantages of Artificial Lift Systems. [Online] Available at: http://petrowiki.org/Relative_advantages_and_disadvantages_of_artificial_lift_systems (Accessed January 2016). Pizzi, N. G. (2010) Water Treatment: Principles and Practices of Water Supply Operations, 4th ed. Denver, CO: American Water Works Association. Price, J. K. (1998) Applied Math for Wastewater Plant Operators, 2nd ed. Florida: Technomic Publishing. Pump School (2007) When to use a Positive Displacement Pump. [Online] Available at: http://www.pumpschool.com/intro/pd%20vs%20centrif.pdf (Accessed December 2015). Punmia, B. C., Jain, A. K. (1998) Waste Water Engineering. New Delhi: Laxmi Publications. Seepex (2016) Smart Conveying Technology. [Online] Available at: http://www.seepex.com/uploads/tx_templavoila/SCT-APP_e.pdf (Accessed January 2016). Seepex (2016) Smart Conveying Technology. [Online] Available at: https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0ahUKEwiehdur1-vLAhVJORQKHTh3AaMQFggvMAI&url=http%3A%2F%2Fwww.seepex.com%2Ffileadmin%2Fuserfun


20

ctions%2Fdownload.php%3Ffile%3DFSCT1e.pdf&usg=AFQjCNF4Mv-rpn8l0FwNq84GULjU1I0GyA (Accessed: January 2016). Vetter, G., Wirth, W. (1993) Understand Progressing Cavity Pumps Characteristics and Avoid Abrasive Wear. Erlangen, Germany: University of Erlangen-Nuremberg. Available at: http://turbolab.tamu.edu/proc/pumpproc/P12/P1247-59.pdf (Accessed: January 2016). Water and Wastewater Treatment Magazine (2013) Grit and Sludge Pumps get the Measure of Wastewater. [Online] Available at: http://wwtonline.co.uk/features/grit-and-sludge-pumps-get-the-measure-of-wastewater#.VsCC_sflfzJ (Accessed January 2016).


21

8. BIBLIOGRAPHY Emerson Process Management (N.D.) Front End Engineering Design Capabilities. [Online] Available at: http://www2.emersonprocess.com/siteadmincenter/PM%20PSS%20Services%20Documents/Modernization/Planning%20and%20Justification/FEED_Brochure6-05.pdf (Accessed: February 2016) Energy Pumps (2016) Ram and Diaphragm Pumps. [Online] Available at: http://www.energypumps.co.uk/thepumps.php (Accessed: January 2016). Gamboa, J., Olivet, A., Iglesias, J., Gonzalez, P. (2003) Understanding The Performance of a Progressive Cavity Pump with a Metallic Stator. Internal Report: Research and Development Institute, Venezuela. Unpublished. Gilbert Gilkes (2016) Air Operated Double Diaphragm Pumps. Internal Manual: Gilkes Pumps. Unpublished. Goulds Pumps (2015) Pump Selection Guide. Internal Manual: Goulds Pumps. Unpublished. Michael, R., Lindeburg, P. E. (2003) Environmental Engineering Reference Manual for the PE Exam, 2nd ed. Belmont, CA: Professional Publications. Wastecorp Pumps (2009) Mud-Sucker Diaphragm Pumps. Internal Manual: Wastecorp Pumps. Unpublished. Weir Pumps (2012) Wemco Model CF Chop-Flow Pump. Internal Manual: Weir Pumps. Unpublished. Whittaker, L. V. (2003) Evaluation and Analysis of Wear in Progressive Cavity Pumps. Internal Report: University of Hull. Unpublished.


22

APPENDIX 1 – NWG SCADA REPRESENTATION – SLUDGE PROCESS


23

APPENDIX 2 – WARKWORTH SLUDGE THICKNESS SAMPLES

Warkworth Sludge Thickness/Flow Data (Source: Warkworth WTW Samples – Electronically Inputted by Author)

NOTE: Blank sample dates represent operator unable to obtain sample for various reasons, e.g. treatment issues or maintenance work.

Warkworth Thickener Feed Samples Jun-15

Jul-15

Aug-15

Date

Thickness (%)

Flow !!/!

Date

Thickness (%)

Flow !!/!

Date

Thickness (%)

Flow !!/!

1

1

1

2 4.43 15.23

2

2

3 4.43 15.93

3

3

4

4

4 4.68 14.59

5

5 4 13.5

5 4.12 14.72

6 4.63 15.67

6 4.36 14.9

6 4.85 14.76

7 4.34 14.86

7 4.2 14.11

7 4.45 14.92

8 5.49 13.57

8 4.44 14.26

8 3.53 14.74

9 5.72 13.98

9 4.09 14.78

9 3.47 14.64

10

10 4.45 14.65

10

11 5.73 14.8

11 4.39 15.03

11 3.68 14.63

12 4.94 15.76

12

12 3.45 15.25

13 6.36 14.67

13

13 4.16 15.31

14 6.12 15.83

14

14 4.44 15.44

15 6.46 15.55

15

15 5.88 15.23

16

16

16 4.1 15.36

17

17

17 4.56 15.3

18

18

18 4.68 14.68

19

19 4.88 14.23

19

20 6.57 16.37

20 4.79 14.75

20

21 4.2 16.31

21 4.99 14.52

21 4.48 14.98

22 3.57 16.12

22

22 5.94 15.28

23

23

23 3.23 15.41

24 4.53 16.38

24

24

25 4.59 16.44

25

25

26 4.39 15.97

26

26 6.78 15.19

27 4.58 15.35

27

27 5.12 15.3

28 4.8 12.42

28

28 4.68 15.13

29 4.63 13.48

29

29 3.98 15.26

30

30 4.32 14.71

30 6.63 15.38

31 4.53 14.75

31

AVERAGES

5.03 15.23

4.45 14.52

4.59 15.07


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APPENDIX 3 – SEEPEX SPLIT ROTOR/STATOR DESIGN

Seepex Split Rotor/Stator Diagram (Source: Seepex 2016, p. 2)

Example of Seepex Split Rotor/Stator in Abrasive WTW Sludge Application (Source: Author)


25

APPENDIX 4 – WARKWORTH PSP PERFORMANCE DATA

Warkworth PSP Performance Data (Source: NOV/Mono Pump Manufacturer, 2014) – NOTE: Red Lines are inputted by Author to demonstrate Warkworth Process Conditions, Pumps also have ‘Mark 1 Rotors’

Fitted


26

APPENDIX 5 – NWG JOB HISTORY ON WARKWORTH PSP’S

!PRIMARY'SLUDGE'PUMP'2'–'DATA'OBTAINED'09/10/15'

!Date'Rep' JOB'REPORTED' All'Hours'SUM'28$Sep$05! THICKENED!FEED!PUMP!2!REPACK!GLAND.! 4!04$Oct$05! RE$PPM!REPLACE!GLAND!PACKING!(KEN!DARLING)! 0.5!25$Nov$05! PUMP!FAILED!(DONE)! 4!14$May$07! REPAIR!FAULT!ON!THICKNER!FEED!PUMP!2/4! 0.5!14$May$07! REPAIR!FAULT!ON!THICKNER!FEED!PUMP!2/4! 0.5!14$May$07! REPAIR!FAULT!ON!THICKNER!FEED!PUMP!2/4! 3.5!21$May$07! CHECK!AND!REPAIR!SLUDGE!THICKNER!FEED!PUMP!NO!2! 4!21$May$07! CHECK!AND!REPAIR!SLUDGE!THICKNER!FEED!PUMP!NO!2! 0.5!25$May$07! CHANGE!ROTOR/STATOR! 8!30$May$07! CHECK!INVERTOR!ON!NO.2!THICKENER!FEED!PUMP! 0.5!30$May$07! CHECK!INVERTOR!ON!NO.2!THICKENER!FEED!PUMP! 1!26$Nov$07! CHECK!FEED!THICKNER!PUMP!NO!2/04!(BEING!DONE)! 5.5!23$Jan$09! REPAIR!THICKENER!FEED!PUMP!NO.2! 1!23$Jan$09! REPAIR!THICKENER!FEED!PUMP!NO.2! 5.5!29$Jan$09! PUMP!REPAIRS! 5.5!22$Oct$09! NOISY!GEARBOX! 6.5!02$Mar$10! NOT!PUMPING!SUSPECT!GEAR!BOX!PROBLEM.! 4.7!02$Mar$10! NOT!PUMPING!SUSPECT!GEAR!BOX!PROBLEM.! 0.62!29$Mar$10! REPAIR!GEARBOX! 16!28$May$10! SLUDGE!THICKNER!FEED!PUMP!2\04!$!PUMP!RUNNING!BUT!NOT!PUMPING! 12!22$Jun$10! PUMP!NOT!PUMPING! 6!04$Aug$10! SLUDGE!THICK!TRANS!PUMP!RUNNINGNUT!NOT!PUMPING.! 2.77!04$Aug$10! SLUDGE!THICK!TRANS!PUMP!RUNNINGNUT!NOT!PUMPING.! 0.02!14$Sep$11! G/BOX!OIL!NEEDS!CHANGED!OIL!TO!SOURCE.! 0.47!10$May$12! SLUDGE!THICK!PUMP!2/04!ROTOR!&!STATOR!REQUIRED.! 2.72!10$May$12! SLUDGE!THICK!PUMP!2/04!ROTOR!&!STATOR!REQUIRED.! 9.71!04$Dec$12! INVERTER!FAULT!ON!THICK!FEED!PUMP!2/04! 0.67!04$Dec$12! INVERTER!FAULT!ON!THICK!FEED!PUMP!2/04! 45.21!24$Jul$13! THICKENER!FEED!PUMP!NO!2!P2/04!BLOCK!PLS!INVESTIGATE! 0.02!26$Jul$13! SLUDGE!FEED!PUMP!RUNS!BUT!NOT!PRODUCING!ANY!FLOW.! 6.65!26$Jul$13! SLUDGE!FEED!PUMP!RUNS!BUT!NOT!PRODUCING!ANY!FLOW.! 0.5!21$Jul$14! THICKENER!FEED!PUMP!NO!2!P2/04!GIVING!OUT!INCORRECT!FLOW! 1.61!21$Jul$14! THICKENER!FEED!PUMP!NO!2!P2/04!GIVING!OUT!INCORRECT!FLOW! 0.02!23$Feb$15! PUMP!PERFORMANCE!IS!POOR!AND!IS!REALLY!NOISY.! 1.36!23$Feb$15! PUMP!PERFORMANCE!IS!POOR!AND!IS!REALLY!NOISY.! 20.43!19$Mar$15! PUMP!NOT!WORKING,!PLEASE!INVESTIGATE! 5.82!29$Jun$15! THICKENER!FEED!PUMP!NO!2!P2/04!$!FLUCTUATING!FLOWS!PLEASE!INVESTIGATE! 0.68!29$Jun$15! THICKENER!FEED!PUMP!NO!2!P2/04!$!FLUCTUATING!FLOWS!PLEASE!INVESTIGATE! 6.29!07$Sep$15! REPLACE!ROTOR/STATOR! 0.5!07$Sep$15! REPLACE!ROTOR!STATOR! 6!

!HOURS'TOTAL' 201.77'

Primary Sludge Pumps – Job Information for previous 11 years (Source – NWG Internal Job Recording System)

!PRIMARY'SLUDGE'PUMP'1'–'DATA'OBTAINED'09/10/15'

!Date'Rep' JOB'REPORTED' All'Hours'SUM'

23$Sep$04! SETTLED!WATER!PUMPS!$!CHECK!PUMPS.! 1.5!23$Sep$04! SETTLED!WATER!PUMPS!$!CHECK!PUMPS.! 0.5!30$Dec$04! REPAIR!THICKENER!FEED!PUMP!2$30!NO!AMPS.! 2!05$Apr$05! REPAIR!THICKENER!FEED!PUMP! 2!05$Apr$05! FITTER!REQUIRED!REPAIR!THICKENER!FEED!PUMP! 0.5!14$Apr$05! REPAIR!FAULT!THICKNER!FEED!PUMP!WILL!NOT!RUN!IN!AUTO! 0.5!19$Apr$05! REPAIR!THICKNER!FEED!PUMP!PUMPS!WILL!NOT!RUN!IN!AUTO!AGAIN! 0.5!

19$Apr$05! REPAIR!THICKNER!FEED!PUMP!PUMPS!WILL!NOT!RUN!IN!AUTO!AGAIN! 18.5!11$Jul$05! REPAIR!THICKENER!FEED!PUMP! 4.5!

09$May$06! REPACK!PUMP!DONE! 6!12$Aug$06! REPAIRS!TO!THICKENER!FEED!PUMP!INVERTER!DONE! 5!14$Aug$06! ASSIST!WITH!PUMP!REPAIR!(DONE)! 7.5!21$May$07! CHECK!AND!REPAIR!SLUDGE!THICKNER!FEED!PUMP!NO!1! 0.5!21$May$07! CHECK!AND!REPAIR!SLUDGE!THICKNER!FEED!PUMP!NO!1! 4!21$May$07! CHECK!AND!REPAIR!SLUDGE!THICKNER!FEED!PUMP!NO!1! 8!27$Apr$08! OVERHAUL!MONO!PUMP! 0.5!27$Apr$08! OVERHAUL!MONO!PUMP! 15.5!02$Jun$08! OVERHAUL!PUMP!DONE! 4.5!16$Jun$08! INSTALL!PUMP!DONE! 3!16$Jun$08! INSTALL!PUMP!DONE! 8!25$Nov$08! UNBLOCK!PUMP! 0.5!25$Nov$08! UNBLOCK!PUMP! 4.5!22$Jun$10! REPLACE!ROTOR/STATOR! 0.5!22$Jun$10! REPLACE!ROTOR!STATOR! 8!02$Aug$10! THICK!FEED!PUMPS!203!LEAKING!SLUDGE!FROM!GLAND.! 0.6!02$Aug$10! THICK!FEED!PUMPS!203!LEAKING!SLUDGE!FROM!GLAND.! 1.58!07$Jan$11! NO!1!THICKENER!FEED!PUMP!FAULT! 7.27!07$Jan$11! NO!1!THICKENER!FEED!PUMP!FAULT! 0.2!22$Feb$11! THICKENER!PUMP!$!LEAKING!FROM!GLAND.! 0.12!22$Feb$11! THICKENER!PUMP!$!LEAKING!FROM!GLAND.! 0.55!14$Jun$11! THICKENER!FEED!PUMPS!203!LEAKING!SLUDGE!FROM!GLAND.! 0.65!17$Aug$11! LEAK!FROM!SLUDGE!THICKENER!FEED!PUMP!203! 4!14$Sep$11! OIL!TOPPED!TO!LEVEL....!GLAND!REQ'RS!PACKING.! 0.72!14$Sep$11! OIL!TOPPED!TO!LEVEL....!GLAND!REQ'RS!PACKING.! 0.49!08$Feb$12! LIMITED!OUTPUT!FROM!THICKENER!PUMP!1! 4!08$Feb$12! LIMITED!OUTPUT!FROM!THICKENER!PUMP!1! 14.98!10$May$12! SLUDGE!THICKENER!PUMP!2/03!INVERTOR!FAULT.! 4.44!10$May$12! SLUDGE!THICKENER!PUMP!2/03!INVERTOR!FAULT.! 0.71!13$Aug$12! THICKENER!FEED!PUMP!NO!1!P2/03!$!LEAKING!GLAND!NEEDS!TIGHTENED!REF! 23.5!13$Aug$12! THICKENER!FEED!PUMP!NO!1!P2/03!$!LEAKING!GLAND!NEEDS!TIGHTENED!REF! 2!11$Sep$12! PUMP!LEAKIN!PAST!PACKING!$!REQ!BILL!HIND!77575! 6!23$Jul$13! THICKENER!FEED!PUMP!203!RUNS!BUT!PRODUCES!NO!FLOW.! 1.64!23$Jul$13! THICKENER!FEED!PUMP!203!RUNS!BUT!PRODUCES!NO!FLOW.! 21.48!28$Aug$14! THICKENER!FEED!PUMP!NO!1!MOTOR!NOT!RUNNING!BUT!RUNNING! 3.63!

28$Aug$14! THICKENER!FEED!PUMP!NO!1!MOTOR!NOT!RUNNING!BUT!RUNNING! 61.35!11$Feb$15! PUMP!SHOWING!RUNNING!ON!SCADA!BUT!NOT!PUMPING! 31.48!11$Feb$15! PUMP!SHOWING!RUNNING!ON!SCADA!BUT!NOT!PUMPING! 0.28!

29$Jun$15! THICKENER!FEED!PUMP!NO!1!P2/03!$!LEAKING!SLURRY!REF!NICK!GRAHAM! 1.91!29$Jun$15! THICKENER!FEED!PUMP!NO!1!P2/03!$!LEAKING!SLURRY!REF!NICK!GRAHAM! 15.06!

!HOURS'TOTAL' 315.14'


27

APPENDIX 6 – QUESTIONNAIRE FOR DIFFERENT UTILITY COMPANIES

QUESTION

COMPANY OR SITE

1. What type of pumps do you use for Primary Sludge Pumping on your Water Treatment Works?

2. Do you suffer with abrasive wear on your equipment?

3. Can you provide me with details of your primary sludge system and pump specification?

4. Does your sludge system incorporate wash water from sediment filters?

5. Do you have any special measures to counteract abrasion within your Primary Sludge Pumps?

Anglian Water

No Reply. No Reply. No Reply. No Reply. No Reply.

Severn Trent 1

"Ram and Progressive Cavity Pumps. We assess for rags, abrasives etc. and combine with the duty requirements to select the pump with lowest WLC."

"On some sites but we identify these and where we can, improve the grit removal, we also work with pump suppliers to ascertain the best materials for wearing parts within the pump."

"We use WIMES specifications for progressive cavity and ram pumps."

"Some of the wash water will go back to the head of the works which will exacerbate the abrasive issue."

"No special measures apart from careful selection of materials and identification of assets with high OPEX costs so we can collaborate with pump suppliers to find solutions."

Severn Trent 2

"Usually Positive Displacement, Ram or Mono type - sized and selected depending on process design parameters for sludge thickness and head to lift. Sometimes centrifugal are fine for the duty, depending on pumping distance/height."

"No - just standard. Nothing like we experience on waste, where we specify RAM pumps for primary sludge and a special hard ceramic coating for the worst sites."

"As all our water treatment works are different having being built at different times, the systems are site specific and hence so are the specs. Pumps are selected to deal with design flows and thickness (if pumping sludge), and for the last 10 years we have not had a framework supply for sludge pumps - we have preferred suppliers but our Design & Build contractors have been free to choose - we mainly have Mono pumps or Hydrostal. Our M&E specs align with WIMES."

"Some treatment works return backwash water to the sedimentation clarifiers.

“Not really, it is very hard to be specific for all our sites."

Southern Water


South West Water


Thames Water

"Mono - progressive cavity pumps."

"Yes, particularly stator wear and is felt most when there are asset availability issues around the grit removal system."

"This is very hard to do as the system is quite large."

"We do use sediment filters." "Yes we have grit removal in the beginning of the sludge treatment phase."

United Utilities

No reply. No reply. No reply. No Reply. No reply.

Welsh Water

"We use a wide range for our sites due to the varying design. Examples of what we use; Progressive cavity pumps, centrifugal, double diaphragm and rotary lobe."

"In some areas yes, however we do our best to tackle abrasive wear as best we can."

"Our typical different pump suppliers are; PCP pumps - Mono or Seepex, Centrifugal - Flygt or Hydrostal, Double Diaphragm - Farm Gas and Rotary Lobe - Borger. Installations can vary from dry to wet well systems. Typically pumping 4-6% density

"We do have some element of filter backwash, but nothing particularly testing for the equipment."

"The carryover grit is typically picked up by planned maintenance activities, operations check for poor performance (drop off). LEAN methodology being implemented to carry out such checks and also RCM (Reliability Centred


28

sludge ranging 5-10m head lift.” Maintenance) when wear occurs it would drive the change of an impeller/wear-ring or rotor/stator depending on the pump type."

Wessex Water

"We use a various range of pump systems for sludge, some sites well have gravity feed and others have progressive cavity of centrifugal arrangements depending on head/distance of pumping."

"Nothing really out of the ordinary, however we do have grit measures in place on our larger sites."

"Unfortunately, giving specific details of our sludge system and pump specifications is difficult as there are many pumps and systems. Some of the pump suppliers we use are; Mono, Flygt and Hydrostal."

"Some do have wash-water from sediment filters, but grit control reduces the amount actually pumped through the sludge process."

"On larger sites we have, grit removal reduces the wear on plant further down the process. Any grit that does get through the process will have an effect on the life of the plant."

Yorkshire Water

"All of our sites are set up slightly different so we have a range, typically using RAM and progressive cavity pumps."

"This also depends on our different sites, some have grit measures in place and others don’t."

"Not particularly, because all of the sites we use are set up different. The specs. are too - the detailed information I received from Sandall say they use EMS RAM pumps."

"Our sites do include washwater from sediment filters, however we don’t have information on particular mixtures of the sludge/wash water."

"Sandall have a good grit system in place which makes a huge difference in regards to abrasion on the pumps, meaning we don’t have abrasion issues here."

NWG - Broken Scar

"At Broken Scar we have five Mono C1BK pumps that are fed from sludge holding tanks, which hold all the sludge generated from the clarification and RGF washes. These pumps then feed the sludge onto two sludge thickeners."

"Yes, this is made worse when we dose PAC at the head of the works, and in flood conditions with lots of silt coming out of the river Tees into the WTW."

"Sludge holding tanks, primary sludge pumps, thickeners, holding tanks, centrifuge - disposal of sludge product. The pumps are Mono C1BK's."

"Yes." "As the pumps fail the Rotors are being upgraded to a more robust stainless steel."

NWG - Lartington

"Pumps for primary sludge; Recovery Tanks - x2 Gorman Rupp, Flotation Sludge - x2 Mono."

"Medium abrasive wear." "Sludge system detail: Thickener feed pumps - x3 Mono, Thickener de-sludge pumps - x2 Mono and Centrifuge feed pumps - x3 Mono."

"Sludge system incorporates wash water from sediment filters."

"Measures to counter abrasion: filter backwash checks to review washout, standard rotors/stators fitted."