HRSG Impact Assessment of Gas Turbine UpgradesDan Blood, Uniper TechnologiesEuropean HRSG Forum, Bilbao, 15th -17th May 2018

Rationale for gas turbine upgrades

Understanding the impact on the water / steam cycle

Summary

Questions

Agenda

Case study: Impact of VLP upgrade for GE 9FA / 9FB

About Uniper

We are Uniper

Where we operate:

40+ countries around the world4th largest generator in Europe

Employees: 12,000Our operations:

Power Generation

Commodity Trading

Energy Storage

Energy Sales

Energy Services

Power generation, Storage, Services - Europe

Power generation - International

Commodity Trading, Energy Sales

€ 1.7 bnEBITDA

100 yearsExperience

36 GW Total generation

Main activities:

Data: Uniper Annual report 2017

Gas fired plants19.2 GW

Coal fired plants10.5 GW

Energy storageGas: 8.2 bn m3

Gas pipelines and infrastructure

Regasification

Nuclear plants1.9 GW

Hydroelectric plants 3.6 GW

Trading Energy sales (small to large clients, electricity and gas)

Services

Expertise built on engineering excellence and asset owner / operator experience

We are independent of equipment and component suppliers, giving us freedom to choose the best solution for clients

We are a one-stop shop offering a broad range of services that work closely together, reducing complexity and risk for clients

Our background as an asset owner/operator gives us deep understanding of the energy industry and our clients’ needs

Expertise based on experience

1926 1957 1970 19901978 2000 2016

Innwerke

1917

UK Central Electricity Generating Board

Pipeline Engineering GmbH

VEBA KraftwerkeRuhr AG

PowergenPower Technology

Rationale for gas turbine upgrades

Understanding the impact on the water / steam cycle

Summary

Questions

Agenda

Case study: Impact of VLP upgrade for GE 9FA / 9FB

About Uniper

Rationale for gas turbine upgrades

Site / market specific but themes are: � Increased need for flexibility due to

renewables growth, commodity prices, demand volatility and demand for balancing services

� Plants are displaced in the dispatch order by new market entrants

� Change from hours-based to starts-based operating regime increases focus on start cost

� Low power prices and uncertain environment for new-build investment

0

50

100

150

200

250

2008 2009 2010 2011 2012 2013 2014 2015

GWh/start Starts

→ Market survival → Market optimisation

Potential offered by gas turbine upgrades

GT upgrades offer a range of measures to improve market value, including: � Improved speed of response (fast starts,

fast ramps, fast shutdown)� Increased maximum load � Increased cycle efficiency � Reduced minimum load � Enhanced ability to offer grid services

Such upgrades offer a CAPEX efficient means of keeping plants competitive → push back up the dispatch order

→ Increase revenue→ Generate value

Standard Combined Cycle

Open Cycle

Combined Cycle with VLP

Improved start-up time:

Reduced minimum load:

Rationale for gas turbine upgrades

Understanding the impact on the water / steam cycle

Summary

Questions

Agenda

Case study: Impact of VLP upgrade for GE 9FA / 9FB

About Uniper

Key questions when considering GT upgrades

� What will be the impact on the water / steam cycle? � Will it cope with the new process conditions? � Will it be safe to operate? � Will the water / steam cycle restrict the full capabilities of the upgrade? � Will I get the full value of my investment? � Will pressure part inspection regimes need to be adjusted or enhanced? � How do I understand, quantify and manage the potential risks? � Will reliability be compromised? � Will the GT supplier ensure that the water / steam cycle is ‘fit for purpose’?

→ A formal process is needed to understand and mitigate the risks→ GT suppliers may not do a comprehensive assessment or may make

assumptions which are not truly valid

Uniper’s recent experience of water / steam cycle impact assessment

2011 2012 2013 2014 2015 2016 2017 2018

Service Pack 7 package

Variable Load Path

Enhanced Variable Load Path

Black start capability

Variable Load Path

Low Load Operating Concept

Minimum Load Reduction

Advanced Performance Package

Variable Load Path

Variable Load Path

‘Open Cycle’ start-up

Low Part Load

Variable Load Path

CO Reduction / Extended Turndown

GE 9FA GE 9FB Alstom GT26 Siemens SGT5-4000F

Includes VLP experience at 12x 9FA units and 1x 9FB unit and global ‘first of kind’ installations for both GT types

Fast Ramp Rate

Fast Ramp Rate

PLANNING TESTING IMPLEMENTATION

A structured approach to impact assessment

Initial review of risks (e.g. HAZOP or HAZID)

Quantify risks (engineering impact assessment)

Review impact of mode of operation (e.g. by plant modelling)

Define new mode of operation Assess

plant trials

Reassess

Undertake plant trials

Adapt and enhance maintenance / inspection regimes (e.g. pressure parts)

Instigate risk reduction plan

Implement

Thermal plant modelling

� PROATES® is a whole plant modelling software package – enables impact of plant upgrades, modifications or changes in operation to be quantified

� Outputs are used to inform: - HAZOP studies and resulting risk mitigation measures prior to testing - engineering impact assessment - future pressure part component inspection strategy

Build site-specificmodel and validatewith real plant data

1Model the impactof the new GT exhaust conditions

2Identify differencesbetween pre- andpost- upgrade process conditions

3Calculate criticalparameters such as saturation andsuperheat margin

4

Typical PROATES model for a CCGT plant

Modelling is essential to understand the complex interactions between components and process flows!

HAZOP (HAZard & OPerability) Study

� Reduces risk of potentially disastrous incidents and operational problems by identifying hazards and suitable risk controls

� Detailed review fulfilling international, local and company requirements� Used on new plant, ageing plant and for plant modifications� Uniper provides HAZOP study leadership and plant specialists to

complement the knowledge and experience of site personnel (and OEM) � Considers the causes of process deviations, consequences and safeguards � Provides recommendations with actions & responsibilities categorised as:

- ‘pre-commissioning’- ‘commissioning’ - ‘post-commissioning’

Rationale for gas turbine upgrades

Understanding the impact on the water / steam cycle

Summary

Questions

Agenda

Case study: Impact of VLP upgrade for GE 9FA / 9FB

About Uniper

GE9FA / 9FB Variable Load Path ‘VLP’ upgrade

� GE / Uniper joint development project (2011-)

� VLP is a GT control feature which uses IGV control to keep exhaust temperature low during start-up

� Allows independent control of GT load and exhaust temperature within an ‘operating space’

� Significantly decouples GT output from HRSG / ST thermal constraints

Conventional operating ‘path’:

VLP enables: → more MW in less time→ reduced fuel burn → reduced load imbalance→ reduced start emissions→ reduced start cost

VLP operating space:

HOT PATH

COLD PATH

Plant A Hot Start Comparison

Pre-VLP VLP

Start-up Fuel Cost Savings

40%

Start Time c.130 mins c.65 mins

Plant B Hot Start Comparison

Pre-VLP VLP

Compare Op Jun’14 – May’15

143 Starts1,900 Hours

233 Starts3,100 Hours

Time to 150MW 55 mins 10 mins

GE9FA / 9FB Variable Load Path ‘VLP’ upgrade

BUT…this causes a redistribution of heat in the balance of plant – requires detailed HRSG & ST assessment

HOT

PATH

COLD PATH

VLP Impact/Risk: HRSG Heat Balance Comparison

At same output:

Cold path reduces heat in the HP and Reheat sections and “pushes” more heat energy to the IP and LP sections of the HRSG

HO

T PA

TH

COLD PATH

VLP Impact/Risk: HRSG Heat Balance Comparison

At same exhaust temp:

For the cold path, modelling predicted that the IP Evaporator would be overwhelmed (more than 100% of full load heat input)

→ the VLP operating space needed to be reduced

Cold path enables the GT to deliver more output and increases / redistributes the overall heat energy into the HRSG - particularly in the IP & LP sections

300

350

400

450

500

550

600

650

0 50 100 150 200 250

GT

Exha

ust T

empe

ratu

re (°

C)

GT Load (MW)

Control system prohibits operation in

this region

VLP: Requirement for ‘Exhaust Flow Boundary’

� In some assessments, modelling predicted that the IP Safety Valve capacity would be insufficient at the extremes of the VLP operating space

� Required ‘Exhaust Flow Boundary’ to be imposed for plant integrity / safety � Boundary determined via plant modelling, impact assessment, HAZOP and

carefully monitored and controlled plant trials HOT L

OAD PATH

COLD LOAD PATH

EXHAUST FLOW BOUNDARY

VLP: ‘Exhaust Flow Boundary’ relaxation

� Flow boundary provides a safeguard, but restricts full exploitation of VLP � Desirable to relax the boundary as far as possible, subject to rigorous

assessment / implementation of additional risk control measures� At one site, relaxation possible via retrofit of additional IP Drum safety valve

New IP Drum safety valve

VLP: ‘Exhaust Flow Boundary’ relaxation

� At another site, safety valve capacity was reassessed against current design code requirements (EN12952) which supersede the original design code

� Enabled a case for flow boundary relaxation to be made � ‘Relaxation test’ confirmed the high IP steam volumetric flow anticipated,

confirming the validity of the predictive modelling

Relaxation test profile

Test moves beyondflow boundary

HOT LO

AD P

ATH

COLD LOAD PATHFLOW BOUNDARYTEST PATH IP/LP steam volumetric flows

Beyond EFB

126%

VLP: Example impacts / risks to Balance Of Plant Impact Typical Risks (site-specific) Potential Mitigations

Reduced sub-cooling margin at economiseroutlet

• Economiser steaming causing stagnation / reverse flow / water hammer / drum level fluctuations

• Steam flashing across level control valves causing valve damage

• Drum level instability due to loss of natural circulation• Forced circulation pump damage due to cavitation

• Monitor for indications of boiler / Balance of Plant control issues or equipment damage

• Increase steam pressure to reduce steam volumetric flow

• Use economiser bypass to improve sub-cooling margin and reduce steam flow

• Limit gas turbine exhaust flow by using the Exhaust Flow Boundary control feature

• Retrofit high pressure trips to HP / IP / LP drums prior to testing

• Enhance maintenance / inspection regimes to target areas where modelling / testing suggests enhanced rates of damage

• Minimise personnel exposure• Consider probability of failure in

risk assessments, given the duration of operation expected at challenging conditions

Increased steam flow from IP & LP Evaporators

• Increased feed water demand requiring backup pumps to operate

• Insufficient capacity of safety pressure relief valve(s)• Water carryover from drums • Insufficient capacity of steam turbine bypass systems

and attemperation• Change in steam turbine thrust (bearing loading)

Increased steam velocity in IP & LP steam circuits

• Droplet impingement in superheaters• Liberation of debris with consequent risk of erosion &

steam turbine damage

Increased gas-side conditions • Stack temperature exceeds design limit

Rationale for gas turbine upgrades

Understanding the impact on the water / steam cycle

Summary

Questions

Agenda

Case study: Impact of VLP upgrade for GE 9FA / 9FB

About Uniper

Summary

� GT suppliers offer upgrades to increase plant flexibility and competitiveness

� Upgrades can have negative impacts on the HRSG / ST or the benefits can be restricted or negated by balance of plant limitations

� Plant modelling, engineering impact assessment and HAZOP before upgrade implementation is key to understanding the risks and appropriate mitigations

� A structured approach minimises risks to component integrity, process safety and operability, ensuring maximum value can be gained from the investment

Rationale for gas turbine upgrades

Understanding the impact on the water / steam cycle

Summary

Questions

Agenda

Case study: Impact of VLP upgrade for GE 9FA / 9FB

About Uniper

Any questions?

2011 2012 2013 2014 2015 2016 2017 2018

Service Pack 7 package

Variable Load Path

Enhanced Variable Load Path

Black start capability

Variable Load Path

Low Load Operating Concept

Minimum Load Reduction

Advanced Performance Package

Variable Load Path

Variable Load Path

‘Open Cycle’ start-up

Low Part Load

Variable Load Path

CO Reduction / Extended Turndown

GE 9FA GE 9FB Alstom GT26 Siemens SGT5-4000F

Fast Ramp Rate

Fast Ramp Rate

Thank you!

If you need any further information, please contact:

dan.blood@uniper.energy

Uniper TechnologiesTechnology CentreRatcliffe-on-SoarNottinghamNG11 0EEUNITED KINGDOM

www.uniper.energy

This presentation may contain forward-looking statements based on current assumptions and forecasts made by Uniper SE management and other information currently available to Uniper. Various known and unknown risks, uncertainties and other factors could lead to material differences between the actual future results, financial situation, development or performance of the company and the estimates given here. Uniper SE does not intend, and does not assume any liability whatsoever, to update these forward-looking statements or to conform them to future events or developments.