Duvha Water Supply During KWS Outage Concept …iliso.com/public_participation/Duvha_Pipeline/382-ECM-BBBB-D00139-6...Duvha Water Supply During KWS Outage Concept Design Unique

Duvha Water Supply During KWS Outage Concept Design

CONTROLLED DISCLOSURE

When downloaded from the EDMS, this document is uncontrolled and the responsibility rests with the user to ensure it is in line with the authorised version on the system.

Unique Identifier: 382-ECM-BBBB-D00139-6

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CONTENTS

Page

1. INTRODUCTION ...................................................................................................................................................... 6

2. SUPPORTING CLAUSES ........................................................................................................................................ 6

2.1 SCOPE .............................................................................................................................................................. 6 2.1.1 Purpose ..................................................................................................................................................... 6 2.1.2 Applicability................................................................................................................................................ 6

2.2 NORMATIVE/INFORMATIVE REFERENCES .................................................................................................. 6 2.2.1 Normative .................................................................................................................................................. 6 2.2.2 Informative ................................................................................................................................................. 7

2.3 DEFINITIONS .................................................................................................................................................... 7 2.3.1 Disclosure Classification ........................................................................................................................... 7

2.4 ABBREVIATIONS .............................................................................................................................................. 7 2.5 ROLES AND RESPONSIBILITIES ...................................................... ERROR! BOOKMARK NOT DEFINED. 2.6 PROCESS FOR MONITORING ........................................................................................................................ 9 2.7 RELATED / SUPPORTING DOCUMENTS ....................................................................................................... 9

3. CONCEPT DESIGN INFORMATION ..................................................................................................................... 10

3.1 SCOPE OF CONCEPT DESIGN .................................................................................................................... 10 3.2 KEY DESIGN ASSUMPTIONS ....................................................................................................................... 10 3.3 DESIGN APPROACH ...................................................................................................................................... 10

3.3.1 Design Inputs........................................................................................................................................... 10 3.3.2 Design Process ....................................................................................................................................... 10 3.3.3 Design Outputs ........................................................................................................................................ 11 3.3.4 Design Verification .................................................................................................................................. 11 3.3.5 Design Criteria ......................................................................................................................................... 11 3.3.6 Codes and Standards .............................................................................................................................. 11

3.4 KEY DESIGN DRIVERS .................................................................................................................................. 12 3.5 ALTERNATIVE STUDIES PERFORMED ....................................................................................................... 12

3.5.1 Alternative 1: Utilise System As Is........................................................................................................... 12 3.5.2 Alternative 2: Blending Plant Connection ................................................................................................ 16 3.5.3 Alternative 3: Reservoir Connection ........................................................................................................ 24 3.5.4 Comparison of Alternatives ..................................................................................................................... 29 3.5.5 Recommendation .................................................................................................................................... 30

3.6 SYSTEM DESCRIPTION ................................................................................................................................ 30 3.6.1 Process Description ................................................................................................................................ 30 3.6.2 System Architecture ................................................................................................................................ 30 3.6.3 External Interfaces .................................................................................................................................. 30 3.6.4 Operating Concept .................................................................................................................................. 31 3.6.5 Safety Concept ........................................................................................................................................ 31 3.6.6 Information Technology ........................................................................................................................... 31 3.6.7 Operational Technology Strategy ............................................................................................................ 31

3.7 SITING ............................................................................................................................................................. 31 3.7.1 Site Selection........................................................................................................................................... 31 3.7.2 Site Characteristics ................................................................................................................................. 31 3.7.3 Site Layout ............................................................................................................................................... 31

3.8 BUILDING OR FACILITY LAYOUT DESIGN .................................................................................................. 31 3.9 CIVIL INFRASTRUCTURE AND BUILDING DESIGN .................................................................................... 32 3.10 MAJOR PIPING DESIGN .............................................................................................................................. 32 3.11 ELECTRICAL DESIGN .................................................................................................................................. 32 3.12 CONTROL AND INSTRUMENTATION DESIGN .......................................................................................... 32 3.13 PRIMARY PLANT DESIGN ........................................................................................................................... 32 3.14 SECONDARY PLANT DESIGN .................................................................................................................... 32 3.15 LINES DESIGN ............................................................................................................................................. 32 3.16 UTILITIES REQUIRED .................................................................................................................................. 32





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3.17 TECHNOLOGY REQUIREMENTS ............................................................................................................... 32 3.17.1 Maturity of Selected Technology ........................................................................................................... 32 3.17.2 New Technology Required .................................................................................................................... 32

3.18 WASTE MANAGEMENT ............................................................................................................................... 32 3.18.1 Water Purification .................................................................................................................................. 32 3.18.2 Waste Storage and transportation ........................................................................................................ 33

3.19 DESIGN CONFORMANCE ASSESSMENT ................................................................................................. 33 3.19.1 Environmental Assessment ................................................................................................................... 33 3.19.2 Reliability, Maintainability, Availability Assessment .............................................................................. 33 3.19.3 Project Cost Assessment ...................................................................................................................... 33 3.19.4 Expandability ......................................................................................................................................... 33 3.19.5 Safety Assessment ................................................................................................................................ 33

3.20 SECURITY DESIGN ...................................................................................................................................... 33 3.21 TEST AND COMMISSIONING ...................................................................................................................... 34 3.22 RISK AND ISSUE REGISTER ...................................................................................................................... 34 3.23 OTHER DESIGN ISSUES ............................................................................................................................. 34 3.24 LESSONS LEARNED .................................................................................................................................... 34

4. AUTHORISATION .................................................................................................................................................. 35

5. REVISIONS ............................................................................................................................................................ 35

6. DEVELOPMENT TEAM ......................................................................................................................................... 35

7. ACKNOWLEDGEMENTS ...................................................................................................................................... 36

APPENDIX A : BOQ .................................................................................................................................................. 37

APPENDIX B : OPERATING PHILOSOPHY DRAWINGS ....................................................................................... 38

APPENDIX C : WATER TREATMENT PLANT IMPACT STUDY ............................................................................. 44





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FIGURES

Figure 1: Alternative 1 - Current System .................................................................................................................... 13 Figure 2: Current South WTP Site Layout .................................................................................................................. 14 Figure 3: Current Plant Layout ................................................................................................................................... 15 Figure 4: Blending Plant Valves ................................................................................................................................. 16 Figure 5: Alternative 2 - Blending Plant Connection ................................................................................................... 17 Figure 6: Blending Plant Connection Site Layout ....................................................................................................... 19 Figure 7: Steel Pipe Supports ..................................................................................................................................... 22 Figure 8: Current State of the Pipe Supports on Site ................................................................................................. 23 Figure 9: Alternative 3 - Reservoir Connection .......................................................................................................... 25 Figure 10: Reservoir Connection Site Layout ............................................................................................................. 26 Figure 11: Interconnecting Valve ................................................................................................................................ 27 Figure 12: Flownex Model .......................................................................................................................................... 28 Figure 13: Modified Raw Mater Supply System P&ID ................................................................................................ 39 Figure 14: Modified Raw Water Clarification South P&ID .......................................................................................... 40 Figure 15: Modified potable water clarifier P&ID ........................................................................................................ 41 Figure 16: Modified demineralised water clarifier P&ID ............................................................................................. 42 Figure 17: Filtered and clarified water pumping P&ID ................................................................................................ 43

TABLES

Table 1: Duvha Water Requirements ......................................................................................................................... 10 Table 2: Clarifier Codes .............................................................................................................................................. 14 Table 3: Blending plant valves (as is) ......................................................................................................................... 16 Table 4: Water Use Scenarios .................................................................................................................................... 18 Table 5: Alternative 2 Flownex Model Results ........................................................................................................... 20 Table 6: Blending plant valves (alternative design 2) ................................................................................................. 24 Table 7: Alternative 3 Flow Parameters ..................................................................................................................... 27 Table 8: Alternative Comparison ................................................................................................................................ 30 Table 9: Estimated Capital Cost for Alternative 3 ....................................................................................................... 33 Table 11: Bill of Quantities for Alternative 3 ............................................................................................................... 37 Table 12: Operation data for demineralised plant ...................................................................................................... 44 Table 13: Vaal water analysis ..................................................................................................................................... 44 Table 14: Vaal water simulation results ...................................................................................................................... 45 Table 15: Komati water analysis ................................................................................................................................. 46 Table 16: Komati water simulation results .................................................................................................................. 46





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Executive Summary

Duvha Power Station receives water from two sources the Komati Water Scheme (KWS) and the Vaal River Eastern Subsystem. Komati water is of a better quality and is the preferred source to produce demineralised and potable water. The KWS is however scheduled for an outage from the middle of 2016, which will impact the supply of Komati water to Duvha Power Station. Duvha Power Station has two raw water reservoirs which can be independently filled with Vaal Water and Komati Water.

To mitigate the impact of the outage, the reserve capacity of the Komati water reservoir will be maximised by only using Vaal water as source of make up for the condenser cooling water systems. Modification to pipe network is required to achieve supply of Vaal water for cooling and Komati water for water treatment plant. The most feasible option will be to install a connection line from the raw water reservoir to the Water Treatment Plant (WTP) on the south side of the Power Station.

The estimated execution cost of the project is R9 484 200.





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1. INTRODUCTION

Duvha Power Station is located in Witbank, Mpumalanga. This power station has six units, each with a generating capacity of 600 Megawatts (MW). The Power Station was designed for water supply from the Komati Water Scheme (KWS) and from the Witbank Dam.

Duvha Power Station is located at the end of the KWS, and had to find an alternate raw water supply source due to the return of service of Komati Power Station. The Witbank Dam, which was one of Duvha Power Station’s original raw water supply sources, could no longer be used due to the deterioration of the water quality in the dam. Following studies, the new raw water supply for Duvha Power Station was identified to be from the Vaal system via the Rietfontein weir and this new supply source was commissioned in May 2013. The raw water is stored at the station reservoir, which has two compartments, for the respective water sources.

The largest usage of raw water is in the cooling water system, which is split in two systems. Vaal water is used in this application for the North system, while Komati water is utilised on both the North and South system. Raw water (Komati) is further treated to produce demineralised water and potable water; and also used for service water.

Two outages on the raw water supply are expected. The Department of Water Affairs (DWA) is planning a three week inspection/repair on the KWS (which includes the Hendrina-Duvha pipeline) in 2016 and then a possibility for further refurbishment which could last between six to twelve months. In this case, there is a risk to the availability and reliability of demineralised water supply to the power station. Considering the state of the water treatment plant (WTP), the runtime will be reduced and it is highly probable that the required quantity of demineralised water will not be produced. This is verified in Appendix C.

Following the Stakeholders Requirements Definition (SRD) (382-ASF-01-BDDD-D00185-1), a concept design is required, to mitigate this risk.

2. SUPPORTING CLAUSES

2.1 SCOPE

The concept design provides the system design overview and the results of technical assessments to determine the ability of the design to meet technical requirements.

2.1.1 Purpose

This document summarises the status and outcome of the concept design phase related activities and

describes the achievement of the design goals in terms of meeting the stakeholder requirements.

2.1.2 Applicability

This document shall apply throughout Eskom Holdings Limited Divisions.

2.2 NORMATIVE/INFORMATIVE REFERENCES

Parties using this document shall apply the most recent edition of the documents listed in the following paragraphs.

2.2.1 Normative

[1] 240-58479576 - Required Operational Capability for Water Supply to WTP During KWS Outage at Duvha Power Station

[2] 382-ASF-01-BDDD-D00185-2 SRD Duvha Water Supply During KWS Outage





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[3] 382-ASF-01-BDDD-D00185-1 SRD End-of-Phase Design Review Report for Duvha Water Supply During KWS Outage

[4] 240-53114002 Engineering Change Management Procedure

2.2.2 Informative

[5] ISO 9001 Quality Management Systems.

[6] Occupational Health and Safety Act, No 83 of 1993

2.3 DEFINITIONS

Definition Description

System

An integrated set of constituent pieces that are combined in an operational or support environment to accomplish a defined objective. These pieces include people, hardware, software, firmware, information, procedures, facilities, services and other support facets.

2.3.1 Disclosure Classification

Controlled disclosure: controlled disclosure to external parties (either enforced by law, or discretionary).

2.4 ABBREVIATIONS

Abbreviation Description

BOQ Bill of Quantities

CCCC Central Change Committee

COTS Commercial Off-The-Shelf

CoE Centre of Excellence

C&I Control and Instrumentation

CRA Concept Release Approval

CCW Concentrated Cooling Water

DRA Definition Release Approval

DRC Design Review Committee

ERA Execution Release Approval

EDWL Engineering Design Work Lead

FRA Finalisation Release Approval

GPS Global Positioning System

HDPE High Density Polyethylene

KKS Kraftwerk Kennzeichen System

KWS Komati Water Scheme

LDE Lead Discipline Engineer

LPS Low Pressure Services

NB Nominal Bore

OEM Original Equipment Manufacturer





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Abbreviation Description

P&ID Piping and Instrumentation Diagram

PARICS Participate, Accountable, Responsible, Inform, Consult, Sign-Off

PPE Personal Protective Equipment

PSR Plant Safety Regulation

PTW Permit To Work

RAM Reliability, Maintainability, Availability

PCM Process Control Manual

PEIC Production Engineering Integration Coal

PFD Process Flow Diagram

RACI Responsibility, Accountability, Consult and Inform

ROC Required Operational Capability

SHE Safety, Health & Environmental

SRD Stakeholders Requirements Definition

WTP Water Treatment Plant

Unit Description

hr Hour

km Kilo metre

kPa Kilo Pascal

m Metre

ML Mega Litre

mm Millimetre

s Second

2.5 ROLES AND RESPONSIBILITIES

The Plant EDWL is delegated with the authority to perform the following functions:

Ensure that all steps are performed according to procedure Perform a further technical review, if required, of the feasibility study and/or the engineering

change package Put together an engineering team led by himself/herself, who is responsible for ensuring that

Level 1 and Level 2 classified Engineering Change Requests have been subjected to the appropriate review cycles and are acceptable for implementation.

The DRC responsibilities include:

Concurrence with the design review procedure and processes applied to the engineering design or engineering change.

Ensuring that all design input has been adequately considered. In particular to ensure that the engineering change has been adequately reviewed with regard to interface issues between various disciplines, contractors etc.





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Ensuring compliance to all review cycles.

The CCCC responsibilities include:

Authorising the proposed design for Level 1 and Level 2 engineering changes. Authorising the engineering change based on the principles, use of technologies, and alignment

to the process and procedure.

The LDE responsibilities include:

Ensuring that the technical work pertaining to their specific CoE area is carried out and that the correct procedures and governances are adhered to.

The Duvha system engineer responsibilities include:

Providing the LDE with design base information

2.6 PROCESS FOR MONITORING

All design work shall be in accordance with the engineering governance procedures with particular reference Design Review Procedure (240-53113685). This will ensure that the design achieves the requirements as set out in the SRD.

2.7 RELATED / SUPPORTING DOCUMENTS

Refer to Section 2.2





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3. CONCEPT DESIGN INFORMATION

In this section the concept design for the Water Supply during KWS Outage project at Duvha Power Station will be described. A system description will firstly be given, followed by a breakdown of the design alternatives. The alternatives will be compared and a preferred design will be suggested.

3.1 SCOPE OF CONCEPT DESIGN

The scope of the concept design is to provide the various concept design alternatives and establish which option is most feasible from both economic and technical perspectives.

3.2 KEY DESIGN ASSUMPTIONS

The outage on the KWS pipeline will not take longer than 30 days per section of pipeline.

3.3 DESIGN APPROACH

3.3.1 Design Inputs

The authorised Required Operational Capability (ROC) and Stakeholder Requirements Definition (SRD) Report was used as the design input into the concept design.

The water requirements for the power station are listed in the Table 1. Data between 1 April 2014 and 31 January 2015 was considered. The worst case (95th percentile) scenario flowrate dataset was selected.

Table 1: Duvha Water Requirements

Flow rate (m3/hr)

Flow rate (ML/day)

Flow percentage (%)

Pressure (kPa)

WTP 421.63 10.12 (7.6)

Demineralised Water 75.47 1.81 1.4

1000

Potable Water 346.17 8.31 6.2 1000

Service Water 15.00 0.36 0.3 1000

Cooling Water

123.13 92.2

South 2565.24 61.57 1000

North 2565.24 61.57 1000

Total 5567.12 133.61 100

3.3.2 Design Process

The following PCMs in the design processes were used:

Control Configuration Changes (240-51093273)

Engineering Change Management Procedure ( 240-53114002)

Design Review Procedure (240-53113685)





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Research was done into the various options available and other Power Stations were also consulted to verify the technology installed.

3.3.3 Design Outputs

The selected design will meet the stakeholder requirements as per Required Operational Capability (ROC) in accordance with the design review procedure.

3.3.4 Design Verification

The design is to be verified by Eskom’s Central Change Committee (CCCC) as well as the internal Eskom design review engineer.

3.3.5 Design Criteria

The plant shall be designed to meet the following performance parameters:

Komati water to the WTP should have a flow of 12 ML/day and pressure of 1000 kPa. Individual

flow rates for demineralised and potable water are respectively 4.8 and 7.2 ML/day.

Komati water to the station for service water should have a flow of 0.36 ML/day.

Vaal water to the North and South cooling water systems should each have a flow of 10.8

ML/day (21.6 ML/day total) and pressure of 1000 kPa.

90 % availability of the system

The upgraded system will have a lifespan of approximately 30 years.

3.3.6 Codes and Standards

LPS Codes and Standards

1. SANS 62-1 – Steel pipes Part 1: Pipes suitable for threading and of nominal size not exceeding

150 mm

2. SANS 62-2 – Steel pipes Part 2: Screwed pieces and pipe fittings of nominal size not exceeding

150 mm

3. SANS 719 – Electric welded low carbon steel pipes for aqueous fluids (large bore)

4. SANS 1123 – Pipe Flanges

5. SANS 4427 – Polyethylene (PE) pipes for water supply - Specifications

Electrical Codes and Standards

1. SANS 121 – Hot dip galvanized coatings on fabricated iron and steel articles - Specifications and

test methods

2. 240-56227516 – LV Switchgear Cntr Gear Assembly Associated Equipment for Voltage 1000V

AC and 1500V Standard

3. 240-56227443 – Requirements for Control and Power Cables for Power stations Standard

4. 240-55714363 – Coal Fired Power Stations Lighting and Small Power Installation Standard

5. 240-56357424 – MV and LV Switchgear Protection Standard





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3.4 KEY DESIGN DRIVERS

The following design drivers were utilised:

Cost

Constructability

Risk Involved

System Simplicity

3.5 ALTERNATIVE STUDIES PERFORMED

Three alternatives have been identified to ensure uninterrupted supply of water to the power station. The first alternative describes the system operating as it currently functions. The other two alternatives propose water during the outage:

System as is

Blending plant connection

Reservoir connection

3.5.1 Alternative 1: Utilise System As Is

A Process Flow Diagram (PFD) for the current system is given in Figure 1.





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Figure 1: Alternative 1 - Current System

There are two compartments in the raw water reservoir, each with a capacity of 440 ML (880 ML total). The minimum storage level is 20% and the maximum operating level is 85%. This leaves storage capacity of 286 ML for each reservoir.

The Komati Raw Water Reservoir gets its water from the Vygeboom Dam via the KWS. Other stations in the scheme are Arnot, Komati and Hendrina Power Station. Duvha Power Station is the last station in this series to receive Komati water. This water can be fed directly to the station or the reservoir, depending on the water requirements. An additional emergency supply line (HDPE) is available to for demineralised water production.

The Vaal-Usutu Raw Waster Reservoir was historically supplied with Witbank dam water, via the Naauwpoort pump station, which takes suction in the Witbank Dam. Supply has however stopped due to deteriorated water quality. This reservoir is also supplied with Vaal water via the Rietfontein weir. The Vaal water line was only commissioned in 2013 in response to less Komati water being available with Komati Power Station coming online. Similar to the Komati Reservoir, Vaal water can be supplied to either the station or reservoir.





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After the reservoir, there is a Blending Valve Pit which would allow the Komati and Vaal water to be mixed (blended), to give the pipeline network more flexibility. This facility is not operational at present due to various mechanical, electrical and control and instrumentation defects.

The main users of Komati water are service water, cooling water (on both the south and north sides of the station), demineralised water production and potable water production. Vaal water is only supplied to the north cooling water system.

3.5.1.1 Chemical Baseline

A layout of the South WTP is given in Figure 2.

Figure 2: Current South WTP Site Layout

Cooling water is the main user of raw water in the Power Station. The cooling systems are divided in two sections (north and south). Each section has 3 clarifiers to either treat the raw water makeup or concentrated cooling water (CCW). The numbering codes for the clarifiers are listed in Table 2. The south clarifiers are located at the WTP.

Table 2: Clarifier Codes

Function North equipment code South equipment code

Raw 46 (20VB10D001) 157 (10VB10D001)

Raw/CCW 47 (20VB20D001) 158 (10VB10D001)

CCW 48 (20VB30D001) 159 (10VB10D001)





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Raw water clarifier 157 also treats water required for potable and demineralised water production. There are two smaller clarifiers for potable (156) and demineralised (186) water, but are not utilised because of their size limitations.

3.5.1.2 Mechanical Baseline

Inspections done on the emergency line showed that in some places the line is broken and will need to be repaired so that it can be used. The pipe supports are incorrectly installed and this will also need to be addressed. The emergency line’s diameter is 200NB and it taps off from the main supply line as shown below:

Figure 3: Current Plant Layout

The emergency line terminates with a connection to the demineralised water clarifier line in valve pit A as shown in Figure 3.

3.5.1.3 Control and Instrumentation Baseline

With no electrical power to the blending plant, the valves in this system are currently fixed in the positions listed in Table 3. Refer to Figure 1 and Figure 4 (extract from 24.57-47022 Raw Water Supply System) for the layout of the valves.





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Table 3: Blending plant valves (as is)

Valves KKS Size (mm) Type Position

00VA10S011 800 Needle Open

00VA20S011 800 Needle Open

00VA13S011 600 Needle Closed


Figure 4: Blending Plant Valves

3.5.2 Alternative 2: Blending Plant Connection

This alternative utilises the emergency supply line to deliver Komati water to the WTP and ensure Vaal water is used for the cooling water on both the North and South sides of the Power Station.

A PFD for the proposed system is given in Figure 5.





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Figure 5: Alternative 2 - Blending Plant Connection

The blending plant is brought back in operation, to direct Vaal water to the cooling towers on the south. A new pipeline is installed before the blending plant to send Komati water for demineralised and potable water production. The new pipelines are indication in Figure 5.

3.5.2.1 Chemical Design

When an outage occurs on the Komati KWS, the best possible use of Komati water must be found. The raw water storage capacity in the Komati reservoir compartment is 286 ML. From the water requirements of Table 1 three scenarios are sketched in Table 4 to maximise the use. The design objective is to maximise the reserve capacity for the reservoir storing Komati water.

Scenario 1: As is Scenario 2: Only cooling water uses Vaal water Scenario 3: Only demineralised water production using Komati water





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Table 4: Water Use Scenarios

Flow rate (m3/hr)

Flow rate (ML/day)

Komati water reserve capacity (days)

Scenario 1

Vaal 3001.87 72.04 Komati 2565.24 61.57 Reservoir capacity

4.65

133.61

Scenario 2


27.29

133.61

Scenario 3


157.91

133.61

Under the circumstances that the Power Station currently operates, there is only a supply for about 4.5 days, which will be too short during the outage period. Both scenario 2 and 3 allows adequate storage of Komati water during the outage.

To minimise the flow required though the emergency line (see mechanical design), the Komati requirement was reduced, by to only producing demineralised water. The configuration of the plant allows this with the operation of demineralised water clarifier 186. The scenario is however unfeasible at this stage, considering that potable water will need to be produced from the Vaal water; which the plant is not optimised to produce and additional modification to the WTP will be required.

3.5.2.2 Mechanical Design

The blending plant’s location is shown in the Figure 6 and the site layout of the South WTP in Figure 6.





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Figure 6: Blending Plant Connection Site Layout

The distance between 1 and 2 is 355m; while the emergency line section between 2 and 3 is 1405m.

The plant has deteriorated over time mainly due to corrosion and infrequent operation. The valves in the blending plant are ceased in their current positions and thus can’t provide a seal. The original use for this plant was to provide infrastructure so that Vaal and Komati water could be blended. It has been advised by Duvha that there is no need to blend the waters in this manner anymore. Therefore this blending plant is no longer required.

3.5.2.2.1 Flownex Model

The system was modelled to determine the feasibility of this option. The system is modelled on the existing raw water infrastructure at Duvha. The additional tap off point for the new Komati supply line was modelled to take supply from the blending plant and to discharge into the pipework (800NB) at Valve Pit A. A 450NB HDPE pipe (PN 2.5) will be used to convey the raw water in this new Komati supply line. The operation of the valves is explained in Table 6, of the C&I design section.

The following results were extracted from the Flownex model. The model’s flows for cooling water and the South WTP were fixed at the required values after the model was run. The fixed flow rate is necessary because the pipelines are able to provide more flow that is required by the plant. If those results are presented it does not describe the plant adequately and hence provides an incorrect basis for





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the alternative. It is important to note that the pressure available at the discharge points is considerably higher than atmosphere and shows that the pipelines do in fact have additional capacity.

Table 5: Alternative 2 Flownex Model Results

Parameter Value Unit

Flow to North Cooling Towers 2571.425 m3/hr

Discharge pressure at North Cooling Towers 176.598 kPa

Maximum Velocity in line to North Cooling towers 0.909 m/s

Flow to South Cooling Towers 2571.432 m3/hr

Discharge pressure at South Cooling Tower 202.461 kPa

Maximum Velocity in line to South Cooling Towers 0.738 m/s

Flow to Potable/Demin Clarifier 432.781 m3/hr

Discharge pressure at Potable/Demineralised Clarifier 182.681 kPa

Maximum Velocity in line to Potable/ Demineralised Clarifier

0.957 m/s

3.5.2.2.2 Major Mechanical Scope Items

To execute this option work will need to be done at the Blending Plant. The Blending Plant will require extensive refurbishment as the equipment installed is non-functional. There will also be work required to be performed at Valve pit A, where a connection to the clarifiers will need to be made.

If there was a connection made at the Blending Plant it will require the following work:

Reinstallation of the valves on the Komati line

Installation of a t-piece and a valve in the Blending Plant, before the Blending Plant valve.

Installation of a pipeline from the Blending Plant to the South WTP.

Connection of the new supply line to the South WTP demineralised and potable water clarifiers.

In order to perform this work the following risks will be faced:

The Power Station will not have supply from the reservoirs for the duration of the work, which means that the station will not be able to receive raw water.

Unforeseen events will prolong the time that the station is disconnected from the reservoir.

Based on experience the work required is approximated to take up to two days to complete which would entail a station shut down as demineralised water production would have ceased.

3.5.2.3 Electrical Design

3.5.2.3.1 Inspection Methodology

Only a visual inspection was conducted. No electrical tests could be conducted as the entire Blending Plant was decommissioned and completely isolated.





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3.5.2.3.2 Control and Power Cables

The voltage levels on the existing cables are as follows:

380V, 220V – Power cables

24V – Control cables

Generally, the outer insulation on all the cables has deteriorated due to exposure to direct sunlight. Most of the cables were not properly secured on the cable racks or along the blending structure. The cables are recommended to be tested and reused or replaced where necessary.

3.5.2.3.3 Small Power and Lighting

The two light fittings mounted above the distribution boards are still in-tacked and can still be reused, however the bulbs must be tested for functionality. The two lighting control circuits also require attention and must be tested for functionality. The welding plug mounted on 380V Distribution Board “A” require attention and must be tested for functionality.

3.5.2.3.4 380V Distribution Boards

The two distribution boards located in the blending plant valve pit (380V Distribution “A” Komati and 380V Distribution “B” Naauwpoort) have corroded due to exposure to direct sunlight. Painting on the outside had deteriorated. The doors are not properly secured to the door hinges and the seals on the doors are damaged. The MCBs and relays have been exposed to rain and dust ingress. The DBs are very old and safety cannot be guaranteed. The two distribution boards must be replaced.

3.5.2.3.5 Control Panels

There are four (4) control panels i.e. Komati (North & South), Naauwpoort (North & South), Main Pump and Sump Pump mounted inside the Blending Pit. The panels are properly secured on the supporting structure and are still in good conditions and will be reused.

3.5.2.3.6 Sump Pumps

Inside the valve pit are sump pumps, but the position of the pumps was unknown and the pumps were not visible. Visual assessment on these pumps was not done and their condition is unknown. The main pump and sump pump motors must be inspected and electrical test conducted, then a decision can be taken to refurbish or replace the motors.

3.5.2.3.7 Actuators

There are four (4) electric actuators mounted inside the Blending Pit. The control circuit for one of the actuators was missing. A specialist on actuators (Frits Thuynsma) stated that it is unlikely that the valves will operate again.

3.5.2.3.8 Junction Box

The outer casing for the junction box is still rigid and can be reused. The modules inside the junction box must be tested and reused or replaced where necessary. The entire panel needs to be rewired.

3.5.2.3.9 Recommendations

Based on the visual inspection, the electrical equipment cannot be used as is; therefore the following recommendations are made:





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The 380V Distribution Boards must be replaced.

Light fittings and lighting control circuits must be tested before new bulbs are fitted. The bulbs may need to be replaced to comply with the lighting requirements.

The welding plug must be tested before reused or replaced if deemed necessary.

Provision should be made to replace both the power and the control cables in case cables fail during testing.

The control panels will be tested before reused.

The main pump and sump pump motors must be inspected and electrical test conducted, then a decision can be taken to refurbish or replace the motors.

The outer casing for the junction box will be reused. The modules inside the junction box must be tested before reused or replaced if deemed necessary. The entire panel to be rewired.

A specialist on actuators to do assessment on the existing actuators and provide feedback on the action to be taken.

3.5.2.4 Civil and Structural Design

Currently the emergency line is supported on concrete sleeper supports and once in the station it is supported on a steel support that is mounted on a short brick wall or short steel stub column as shown in the figure below.

Figure 7: Steel Pipe Supports

These supports require refurbishment as at various spots the steel saddle has broken off and the pipes are seated on the ground unsupported as can be seen in the figures below.





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Figure 8: Current State of the Pipe Supports on Site

It is recommended that remedial work be conducted that the current supports be evaluated and repaired if possible or else replaced with more durable supports.

3.5.2.4.1 PIPE SUPPORTS

New concrete sleeper supports need to be added to the new pipe line from the blending plant to the existing emergency pipe line tie-in as shown in figure 7, these sleepers can be similar to that currently being used. Exact design of these sleepers can only be done once forces in the pipes are known.

The design will consist of concrete sleepers on dimension 600x300x300 mm placed at 2 m spacing from the blending plant to the start of the existing emergency pipe line supports. The support dimensions and spacing are based on the recommendations by HDPE pipe (High Density Polyethylene) manufactures and linked to the size of the pipe. All existing supports will need to be refurbished and modified to accommodate the new pipe size.

3.5.2.5 Control and Instrumentation Design

3.5.2.5.1 Inspection Methodology

Only visual inspection was conducted. No electrical tests could be conducted as the entire Blending Plant was decommissioned and completely isolated.

3.5.2.5.2 Flow Transmitters

There is a transmitter for each pipeline (4) for monitoring the flow of water. The remaining life span for the flow transmitters are unknown, but they are not is use currently and does not need to be replaced.

3.5.2.5.3 Control Philosophy

To ensure that the Vaal water can be properly diverted to the South Water Treatment Plant, the control valves in the Blending Plant need to be used in operation.





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Table 6: Blending plant valves (alternative design 2)

Valves KKS Size (mm) Type Position


00VA20S011 800 Butterfly Open


00VA23S011 600 Butterfly Open

3.5.2.6 Advantages and Disadvantages of Alternative 2

Advantages:

1. Shorter distance from blending plant to valve pit A.

Disadvantages:

1. Blending Plant valves will need to be replaced.

2. High risks involved in the construction of this alternative.

3. Does not provide the station with an emergency operation line.

4. Electrical overhaul is required.

3.5.3 Alternative 3: Reservoir Connection

Similar to Alternative 2 the emergency pipeline route is used to transfer Komati water, however the connection point is different. A representation of the system is given in Figure 9.





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Figure 9: Alternative 3 - Reservoir Connection

In this design alternative, the Blending Plant is bypassed and a pipeline is installed directly from the raw water reservoirs to the emergency supply line.

3.5.3.1 Chemical Design

The same requirements as per Alternative 2 are valid.

3.5.3.2 Mechanical Design

In this alternative a connection to a 450NB UV HDPE (PN 2.5) pipe will have to be made at the Komati reservoir (point 1, Figure 10). This pipe will run parallel to the ash pipelines until the existing emergency line (point 1 to point 2, Figure 10). From this point onwards the pipe will run in the place of the existing emergency line to the South WTP (point 2 to point 3, Figure 10). Connections will be made to the existing pipelines to get the Komati water to the demineralised/potable water clarifiers as shown in Figure 10.





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Figure 10: Reservoir Connection Site Layout

The distance between 1 and 2 is 882 m; while the emergency line section between 2 and 3 is 1405 m.

A reconfiguration of the reservoir pipework, at point 1 in Figure 10, will need to be done to provide isolation of the Komati reservoir compartment. The existing 400NB drain valve will be used for a connection point to the new 450NB HDPE pipe. The valve 00VA12S501 will need to be closed to isolate the station’s main supply lines and valve 00VA12S501 will be open for Vaal water to be directed to the south cooling water system. The existing pipework is shown in P&ID 24.57/47022 and marked up in Figure 11 below. To provide Vaal water to both cooling tower sets the valve 00VA21S501 must be opened. The valve is shown on P&ID 24.57/47022 and marked up in the following:





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Figure 11: Interconnecting Valve

The final connection to be made is in Valve pit A. The 450NB line will be connected to the existing connection point of the Emergency line (300NB) via a reducer to valve 10VB50S501.

The emergency line will be decommissioned and removed completely from point 2 to Valve pit A of Figure 10. In the place of the old 200NB emergency line, the new 450NB reservoir connection line will be installed.

3.5.3.2.1 Valve operation

After the system has been installed, operation of the system will only be required when the system is required to be shut off. This will occur when the main Komati supply line is fully back in operation. This is envisaged to be anywhere between six weeks and nine months, depending on the outcomes of the main line inspection.

When the new supply line is not required, that is only when the Komati water flow has been reinstated or the main supply line work has been completed, the system will be reconfigured to operate as it currently is.

3.5.3.2.2 Flownex Model

The following results were generated by the Flownex Model for the third alternative. The model was simulated using the same fixed mass flow conditions as in Alternative 2.

Table 7: Alternative 3 Flow Parameters

Parameter Value (Unit)

Flow to North Cooling Towers 2569.628 m3/hr

Discharge pressure at North Cooling Towers 170.756 kPa

Maximum Velocity in line to North Cooling towers 1.262 m/s

Flow to South Cooling Towers 2569.637 m3/hr





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Discharge pressure at South Cooling Tower 197.500 kPa

Maximum Velocity in line to South Cooling Towers 0.631 m/s

Flow to Potable/Demineralised water Clarifier 422.394 m3/hr

Discharge pressure at Potable/Demineralised water Clarifier

173.276 kPa

Maximum Velocity in line to Potable/Demineralised water Clarifier

0.933 m/s

3.5.3.2.3 Major Mechanical Scope Items

Table 7 shows the flow characteristics under fixed flow conditions to the cooling towers. The cooling tower flow was fixed at the required flow rate because with an atmospheric discharge pressure the flows were excessively high, showing that flow capacity is not a problem. The discharge pressure in Table 7 shows that there is more capacity than is required to provide the flow. The velocity in the pipelines is stated as the maximum velocity found in the pipelines and these are below the maximum safe operating range of 2.5m/s.

The equipment that will need to be purchased is in Appendix A in the BOQ. The following image is of the Flownex Model:

Figure 12: Flownex Model

The Flownex model will be saved with the project documentation for future use.

The envisaged sequence of construction for the system is the following:

1. The HDPE pipe is laid from the Reservoir to the WTP valve pit A and supports installed.

2. The Emergency Supply line is removed as the new pipe is installed.





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3. The HDPE pipe is connected to the Emergency line tie in valve.

4. The HDPE pipe is connected to the drain valve at the reservoir.

5. Drain valve opened and the HDPE pipe is filled with water.

6. Manual valve configurations are completed and the system is running.

3.5.3.3 Electrical Design

Not required, as valves will be manually controlled in this option. The blending station is being bypassed.

3.5.3.4 Civil and Structural Design

See Alternative 2 for the current status of the emergency line pipe supports.

3.5.3.4.1 Pipe Supports

New concrete sleeper supports need to be added to the new pipe line from the raw water reservoir to the existing emergency pipe line tie-in as shown in Figure 11. The new routing will require the pipe line to pass through the station perimeter fence; this will be achieved by routing the pipe line through an existing pipe culvert that run under the security fence that is used for the Ash lines. The Pipe support sleepers will be similar to that currently being used. Exact design of these sleepers can only be done once forces in the pipes are known

The design will consist of concrete sleepers on dimension 600x300x300 mm placed at 2m spacing from the Raw Water Reservoirs to the start of the existing emergency pipe line supports. The support dimensions and spacing are based on the recommendations by HPDE manufactures and linked to the size of the pipe. All existing supports will need to be refurbished and modified to accommodate the new pipe size.

3.5.3.5 Control and Instrumentation Design

3.5.3.5.1 Control Philosophy

The operation of the Blending Plant will not change from the current philosophy and the fixed valve positions from Table 3 still apply.

3.5.3.6 Advantages and Disadvantages for Alternative 3

Advantages:

1. Minor construction required.

2. No production risk imposed during construction.

Disadvantages:

1. Pipeline length is longer that Alternative 2.

3.5.4 Comparison of Alternatives

Alternative 1, the as is alternative, will not be considered because it does not meet the storage time required for Komati water in the reservoir, during for a 20 day outage period during construction on the line. See Table 4.





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Alternative 2 and Alternative 3 are scored against each other in the following table. The table compares the alternatives to each other using criteria. The criteria are weighted according to their importance and a score is calculated. The higher the alternative’s score the higher its ranking. The option that scores the most is the option that is selected to go forward into design.

Table 8: Alternative Comparison

Alternative

Alternative 2 Alternative 3

Criteria Weighting Rating (max 5) Score Rating (max 5) Score

Cost 5 4 20 3 15

Constructability 5 3 15 5 25

Risk Involved 5 2 10 5 25

System Simplicity 4 4 16 5 20

Total 61 85

Ranking 2 1

Cost: The lowest price gets the best score (5) and the other alternative is rated according to the variance above the lowest price.

Constructability: The activities involved in the construction of the system are scored in this parameter. Simpler and fewer activities, will score the higher.

Risk Involved: The risks which are highlighted in the report inform the scoring of this parameter. The main consideration in this is the station being isolated from the reservoirs; this creates a total production risk. A higher score is allocated for a lower risk.

System Simplicity: The simplicity of the newly installed system is assessed in this parameter. The items looked at in the scoring of this parameter is how complex is the newly installed system as compared to the other alternatives. A simpler system will score higher.

3.5.5 Recommendation

In the scoring above, Alternative 3 (Reservoir Connection) is shown as the most feasible choice primarily due to the fact that this option does not isolate the power station from the reservoirs.

3.6 SYSTEM DESCRIPTION

3.6.1 Process Description

The installation of a new pipeline from the raw water reservoir to the South WTP will ensure that the usage of Komati water is optimised.

3.6.2 System Architecture

Not applicable

3.6.3 External Interfaces

The boundary conditions for the design are as follow:





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Komati reservoir compartment

Potable and demineralised water line in valve pit A, at the South WTP.

3.6.4 Operating Concept

The operation of the plant is represented with modified drawings in Appendix B.

3.6.5 Safety Concept

Compliance with all current legislation and Eskom policies and directives is mandatory.

All normal safety considerations must be adhered to and correct Personal Protective Equipment (PPE) must be worn at all times.

Risk assessments and pre-job briefings must be held before the start of every task.

When working on heights a safety harness must be worn.

Plant Safety Regulation (PSR) must be adhered to, Permit To Work (PTW) must be in place before the start of any work

3.6.6 Information Technology

Not applicable.

3.6.7 Operational Technology Strategy

Not applicable.

3.7 SITING

3.7.1 Site Selection

The design will be implemented from the raw water reservoirs to the South WTP.

3.7.2 Site Characteristics

The Altitude of the low pressure services building at Duvha Power Station is 1600 metres above sea level. The Power Station consists of 6 x 600MW units and is located approximately 15 km east of Witbank in Mpumalanga. Its Global Positioning System (GPS) co-ordinates are: 25.96391°S 29.33727°E-25.96391; 29.33727

Other site characteristics at Duvha PowerStation which were used for sizing equipment are listed on the input section.

3.7.3 Site Layout

The layout from the new pipeline is presented in Figure 10 and the layout of the South Water Treatment Plant in Figure 2.

3.8 BUILDING OR FACILITY LAYOUT DESIGN

Not applicable





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3.9 CIVIL INFRASTRUCTURE AND BUILDING DESIGN

See section 3.5.2.4

3.10 MAJOR PIPING DESIGN

See section 3.5.5.3.2

3.11 ELECTRICAL DESIGN

Not applicable

3.12 CONTROL AND INSTRUMENTATION DESIGN

Not applicable

3.13 PRIMARY PLANT DESIGN

Not applicable

3.14 SECONDARY PLANT DESIGN

Not applicable.

3.15 LINES DESIGN

Not applicable.

3.16 UTILITIES REQUIRED

Not applicable.

3.17 TECHNOLOGY REQUIREMENTS

3.17.1 Maturity of Selected Technology

Not applicable

3.17.2 New Technology Required

Not applicable

3.18 WASTE MANAGEMENT

3.18.1 Water Purification

Not applicable.





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3.18.2 Waste Storage and transportation

Not applicable.

3.19 DESIGN CONFORMANCE ASSESSMENT

3.19.1 Environmental Assessment

To be completed after concept phase.

3.19.2 Reliability, Maintainability, Availability Assessment

RAM will be performed during detailed design.

3.19.3 Project Cost Assessment

The breakdown of the project costs for the Alternative 3 is shown below.

Table 9: Estimated Capital Cost for Alternative 3

Civil & Structural R 3 497 000.00

LPS R 814 000.00

Total Capital Costs* R 4 311 000.00

Installation Cost (40% capital cost) R 1 724 400.00

Detailed Engineering (15% capital costs) R 646 650.00

Project Management and Construction Engineering (50% capital costs) R 2 155 500.00

Contingency (15% capital costs) R 646 650.00

Total Project Execution Costs R 9 484 200.00

*C&I and Electrical cost are R 0

3.19.4 Expandability

Not applicable.

3.19.5 Safety Assessment

1. Industrial Safety Assessment

The hazard analysis will be performed during the detailed design phase

2. Preliminary Fire Safety Assessment

No potential fire hazards as a result of the installation

3.20 SECURITY DESIGN

Not applicable.





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3.21 TEST AND COMMISSIONING

In the detail design phase the testing and commissioning strategy will be developed. Special attention needs to be taken on testing the welds of the HDPE pipeline.

3.22 RISK AND ISSUE REGISTER

The following risks have been identified in the project:

HDPE pipeline may be damaged by veld fires. This risk will be mitigated by providing a bush cleared servitude around the pipeline of a minimum of 2m.

Weld connections on HDPE in the past have been found to leak. This risk will be mitigated by quality control of the welds and a commissioning procedure that pressure tests the pipes.

3.23 OTHER DESIGN ISSUES

Not applicable.

3.24 LESSONS LEARNED

None





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4. AUTHORISATION

This document has been seen and accepted by:

Name & Surname Designation

Nalini Moodley Manager: Chemical CoE

Ronald Mandavha Engineer: Project Engineering

Terence Abboo Senior Engineer: Chemical

Schalk van Heerden Engineer: Chemical CoE

Nomfundo Mdlokovana Engineer: C&I CoE

Byron Thomas Engineer: Structural Design CoE

Keagan Naidoo Senior Engineer: Low Pressure Services CoE

Vasheer Ramdeen Engineer: Low Pressure Services CoE

Rhulani Mlambo Engineer: System Integration CoE

David Kunene Engineer: Electrical CoE

Nelly Hlophe Manager: Duvha Power Station Auxiliary Engineering

Totoma Molawa System Engineer: Duvha Power Station Auxiliary Engineering

Themba Shabalala Manager: Duvha Power Station Chemical Services

Cecil Mngqibisa Chemist: Duvha Power Station Chemical Services

Sumayyah Sulliman Chief Engineer: PEIC

Tersia Walton PED

Petro Hendriks Senior Advisor (Water Management): Sustainability CoE

Kholo Paledi Configuration Management Lead

5. REVISIONS

Date Rev. Compiler Remarks

2015/11/02 0.1 S van Heerden Concept draft

2015/12/08 0.2 S van Heerden Multi-discipline review

2015/11/10 1 S van Heerden Sign-off

6. DEVELOPMENT TEAM

The following people were involved in the development of this document:

Schalk van Heerden

Keagan Naidoo

Vasheer Ramdeen

Terence Abboo

Nomfundo Mdlokovana





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David Kunene

Ronald Mandavha

Totoma Molawa

7. ACKNOWLEDGEMENTS

Frits Thuynsma

Tersia Walton

Sumayyah Sulliman

Petro Hendriks





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APPENDIX A: BOQ

Table 10: Bill of Quantities for Alternative 2

Item Price Each Number Price

HDPE Pipe R 1 500 1405 R 2 107 500

HDPE 90° bend piece R 1 500 4 R 6 000


HDPE Pipe Reducer 450 to 400 NB R 1 000 1 R 1 000


1000NB Gate Valve R 48 000 1 R 48 000

Air Release Valve R 4 500 1 R 4 500

Butterfly Valve 600NB R 70 000 1 R 65 000

Butterfly Valve 800NB R 73 000 1 R 72 000

Concrete Pipe Support R 100 215 R 21 500

Steel Pipe Support R 1 000 750 R 750 000

Total Execution Cost

R 3 088 500

Table 11: Bill of Quantities for Alternative 3

Item Price Each Number Price

HDPE Pipe R 1 500 2287 R 3 430 500





1000NB Gate Valve R 48 000 1 R 48 000

Air Release Valve R 4 500 1 R 4 500

Concrete Pipe Support R 100 640 R 64 000

Steel Pipe Support R 1 000 750 R 750 000

Total Execution Cost

R 4 311 000





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APPENDIX B: OPERATING PHILOSOPHY DRAWINGS

To support the operating philosophy of system design of Alternative 3, the P&ID was marked-up to show the various water flows.

Drawings

1. 24.57-47022 Raw Water Supply System

2. 24.57-47023 Raw Water Clarification South

3. 24.57-47026 Potable Clarifier

4. 24.57-47027 Demin Water Clarifier

5. 24.57-47028 Filtered And Clarified Water Pumping

6. 0.57/7231 Raw water pipeline

A light line is Komati water and dark blue is Vaal water. Valves highlighted with red will be operated (either open or closed). Additional equipment that needs to be installed is indicated by dashed lines.



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Figure 13: Modified Raw Mater Supply System P&ID



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Figure 14: Modified Raw Water Clarification South P&ID



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Figure 15: Modified potable water clarifier P&ID



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Figure 16: Modified demineralised water clarifier P&ID



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Figure 17: Filtered and clarified water pumping P&ID





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APPENDIX C: WATER TREATMENT PLANT IMPACT STUDY

The original findings of this section are based on the report “Duvha Power Station - Impact of alternative Raw Water supplies to Duvha Power Station” from December 2009.

C.1 Operation Data

Table 12: Operation data for demineralised plant

Flow rate per line 215.5 m3/h net 220.0 m

3/h gross (x 3)

Regenerant 98 % H2SO4 48 % NaOH

Cost / kg 100% ZAR 0.70 ZAR 2.23

Flow rate per line 215.5 m3/h net 220.0 m

3/h gross (x 3)

(× 3)

Regenerant 98 % H2SO4 48 % NaOH

Cost / kg 100% ZAR 0.70 ZAR 2.23

Layout of the Plant (With Degasifier)

Weak Acid Cation –> Strong Acid Cation -> Degasser -> Weak Base Anion -> Strong Base Anion Resins used at Duvha: Amberlite IRC86SB - Amberjet 1300 H - Amberlite IRA96 - Degasifier - Amberlite IRA405 Cl

With the operational data and respective water analysis, simulation of the demineralised plant was carried out on IXCalc simulation software.

C.2 Vaal Water

Table 13: Vaal water analysis

Parameter Units Reported as Analysis Cations as CaCO3

Anions as CaCO3

Calcium mg/l as such 15.59 38.97

Magnesium mg/l as such 7.67 31.60

Sodium mg/l as such 10.51 22.82

Potassium mg/l as such 3.11 3.98

Chloride mg/l as such 7.95 11.22

Sulphate mg/l as such 17.04 17.72

Fluoride mg/l as such 0.20 0.53

Alkalinity mg/l 71.37 71.37

TOTAL mg/l as CaCO3 97.37 100.84

Difference % 3.56





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Table 14: Vaal water simulation results

Resin choice Amberlite IRC86SB

Amberjet 1300 H

Amberlite IRA96

Amberlite IRA405 Cl

Resin volume [litres] 4000 9625 6000 8500

Reference ionic form for calculation H Na Free base Cl

Volume to purchase [L] 10350

Potential running time [h] 24.7 24.7 24.7 24.7

Gross throughput [m3] 5511 5509 5477 5482

Ionic load [eq] 5033 6020 3171 2312

Organic load [g/L R as KMnO4] 37 10

Operating capacity [eq/l R] 1.26 0.63 0.53 0.27

Flow-rate [BV/h] 55.0 22.9 36.7 25.9

Regenerant mode Co-flow Reverse Co-flow Reverse

Leakage (overrun) [%] 36 0

Regenerant type H2SO4 NaOH (40°C)

Concentration [%] 0.7 3.0 2.7

The concentration shown above is an average value. Use stepped concentrations to avoid CaSO4 precipitation: 2 Steps: 2 % (1/2) 4 % (1/2)

Regenerant ratio [% theory] 246 306 329 552

Regenerant Level [g/L R] 94 60

Total regen. [kg 100%] 902 510

Consumption [g/m3 water] 171.4 95.3

Excess of regenerant [eq] 7364 7364

Dilution water [m3] 98.8 29.2 17.8

Regen. displacement [m3] 27.3 43.5

Fast rinse [m3] 12.0 28.9 36.0 51.0

Backwash water [m3] 18.0 0.0 4.2 0.0

Total waste water [m3] 367.8

TDS of waste [meq/L] 69

Safety factors 0.62 0.63 0.48 0.95

Leakage < 1.0 µS/cm < 0.03 mg/L SiO2

Sizing and pressure drop

External diameter [mm] 3000 3000 2500 2800

Filter area [m2] 6.95 6.95 4.81 6.04

Linear velocity [m/h] 32 32 46 36

Bed depth shrunk form [mm] 576 1386 1248 1406





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Bed depth swollen form [mm] 620 1427 1334 1631

Bed depth end of run [mm] 620 1399 1334 1537

Pressure drop [kPa] 46 46 89 83

Economics

Regenerant cost per m3 [ZAR] 0.12 0.21

C.3 Komati Water

Table 15: Komati water analysis

Parameter Units Reported as Analysis Cations as CaCO3

Anions as CaCO3

Calcium mg/l as such 11.18 27.96

Magnesium mg/l as such 8.09 33.34

Sodium mg/l as such 7.34 15.93

Potassium mg/l as such 2.66 3.41

Chloride mg/l as such 7.65 10.78

Sulphate mg/l as such 17.45 18.14

Fluoride mg/l as such 0.18 0.48

Alkalinity mg/l 51.66 51.66

TOTAL mg/l as CaCO3 80.64 81.06

Difference % 0.52

Table 16: Komati water simulation results

Resin choice Amberlite IRC86SB

Amberjet 1300 H

Amberlite IRA96

Amberlite IRA405 Cl

Resin volume [litres] 4000 9625 6000 8500

Reference ionic form for calculation H Na Free base Cl

Volume to purchase [L] 10350

Potential running time [h] 26.0 26.1 26.1 26.1

Gross throughput [m3] 5803 5797 5781 5783

Ionic load [eq] 4136 5265 3353 2133

Organic load [g/L R as KMnO4] 42 12

Operating capacity [eq/l R] 1.03 0.55 0.56 0.25

Flow-rate [BV/h] 55.0 22.9 36.7 25.9

Regenerant mode Co-flow Reverse Co-flow Reverse

Leakage (overrun) [%] 31 0

Regenerant type H2SO4 NaOH (40°C)

Concentration [%] 0.7 3.0 3.0

The concentration shown above is an average value. Use stepped concentrations to avoid CaSO4 precipitation: 2 Steps: 2 % (1/2) 4 % (1/2)

Regenerant ratio [% theory] 318 350 317 598

Regenerant Level [g/L R] 94 60





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Total regen. [kg 100%] 902 510

Consumption [g/m3 water] 162.5 90.2

Excess of regenerant [eq] 9015 9015

Dilution water [m3] 98.8 29.2 15.9

Regen. displacement [m3] 27.3 43.5

Fast rinse [m3] 12.0 28.9 36.0 51.0

Backwash water [m3] 18.0 0.0 4.2 0.0

Total waste water [m3] 365.9

TDS of waste [meq/L] 70

Safety factors 0.57 0.57 0.51 0.95

Leakage < 1.0 µS/cm < 0.03 mg/L SiO2

Sizing and pressure drop

External diameter [mm] 3000 3000 2500 2800

Filter area [m2] 6.95 6.95 4.81 6.04

Linear velocity [m/h] 32 32 46 36

Bed depth shrunk form [mm] 576 1386 1248 1406

Bed depth swollen form [mm] 620 1427 1334 1631

Bed depth end of run [mm] 620 1399 1334 1537

Pressure drop [kPa] 46 46 89 83

Economics

Regenerant cost per m3 [ZAR] 0.11 0.20

C.4 Results and Discussion

The most critical parameter to consider from the simulation results is the potential running time. The demineralised plant can run with Vaal water for 24.7h, while on Komati water it is extended to 26.0h.

Komati water is thus the preferred water source.

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