challenges facing performance evaluations of igcc … · thermal performance tests are the “final...

by

Justin Zachary and Lee SchmoeBechtel Power Corporation

Presented at

© Bechtel 2007. All rights reserved. 8130-10/07-1

Challenges Facing Performance Evaluations of IGCC Power Plants

Coal Gasification ConferenceSan Francisco, California

Thermal performance tests are the “FINAL EXAM”where the guarantees made by suppliers and contractors to owners must be demonstrated. Millions of dollars are at stake, so plan and prepare 4–5 years in advance!Conventional power plant performance tests are guided by ASME codes. To date, the testing procedures for gasification processes have been left to the discretion of the parties to the testA new performance code ASME PTC 47 has been specially developed for an IGCC power plant. Subcomponent procedures are in the works, so get involved now.

© Bechtel 2007. All rights reserved. 8130-10/07-2

8130-10/07-3© Bechtel 2007. All rights reserved.

Outline

Performance Test Code Basics

The Significance of Test Significance

Codes Applicability

Performance Guarantees

Test Tolerance Versus Test Uncertainty

Data Reduction Methodology

Summary and Recommendations


Performance Test Code Basics

1. Reach an agreement on the test philosophy and guarantee/test parameters during contract discussions

2. Determine the boundaries of the plant and define all the crossing streams

3. Design of the plant to accommodate accurate permanent and temporary instrumentation to match Step 2

4. Develop performance test procedures on how to collect data and correct to reference conditions

5. Conduct the test, collect data and perform the calculations to determine the guarantees at reference conditions

6. Demonstrate compliance or determine bonuses/ penalties


PTC 47 Overall Test Boundary

PowerBlock

GasificationBlock

Air Separation

Unit

MakeupWater and

Condensate

CoolingWater/Air

CoolingWater/Air

ExportSteam

NetPower

Vent N2

Inlet Air

Raw FuelSorbent

SecondaryFuel

ExportSyngas

VentGas

ImportSteam

HRSGExhaust

ByproductsAsh/Spent Sorbent

Sulfur/Sulfuric

ByproductsO2, N2


PTC 47.2Gasification

Block

Other IGCC Test Code Boundaries

PTC 47.4(PTC 46)Power Block

PTC 47.1Air

Separation Unit

PTC 47.3Fuel GasCleaning

N2

Raw FuelSorbent

SecondaryFuel

VentGas

Ambient Air

Power

Fuel Gas

Process Steam

Process Water

Condensate

Gasifier Steam

NitrogenAir

Cooling WaterProcess Water

Power

ByproductsAsh

Spent SorbentSulfur

Steam HRSG Exhaust

ByproductsO2, N2 Vent N2

MakeupWater and

CondensateCooling

Water/Air

CoolingWater/Air

ExportSteam

NetPower

O2

Required forTest Calculation

Not Required forTest Calculation

PTC 47.4Test

Boundary

SyntheticGas


PTC 47—IGCC Technical Challenges

IGCC plant test procedure differs from any existing codes for conventional power plants by attempting to evaluate in addition to Power Output and Heat Rate:

Direct solid fuel measurement of flow and compositionPoly generation byproducts: Sulfur, O2, N2, syngas


Test Significance—It’s Important!Thermal performance evaluation in a power plant is a challenging technical issue with very significant commercial implications. Typical case impact of performance on IGCC liquidated damages

Plant output Test Uncertainty %

LD's Value $/kW $

Power kW 450,000 2200 0.49 1,250 2,750,000

Plant Heat Rate

Test Uncertainty %

LD's Value $/(BTU/kWh) $

Heat Rate Btu/kWh 8,000 80 1 40,000 3,200,000

The Test Uncertainty of 0.5% Power and 1% HR equals $6M


Test Uncertainty and Test ToleranceTest Uncertainty is a technical issue dependent on:

Measurement uncertainty • Accuracy of the instrumentation (systematic and random errors) • Proper calibration

Test conductance and corrections methods• Correct conductance of test• Adequate data collection and processing

Test Uncertainty is determined by a well established statisticalanalysis (PTC 19.1)

Test Tolerances are commercial issues negotiated between the parties, to suit the project and financial institutions requirements.Test Uncertainty cannot be zero while Test Tolerance might be set at any value, including zero and equal to Test Uncertainty


Typical Test Uncertainties

Corrected ValuesPTC 46

Combined Cycle Example

PTC 46 Steam Cycle

ExamplePTC 47 Power-

Only Case

Input fuel flow 0.75% N/A 3%

Input fuel heating value 0.5% 1% 1%

Plant thermal efficiency 1.3% 1.6% 3.5%

Plant electrical output 0.8% 0.8% 1%


IGCC Plant Typical UncertaintiesCorrected Values

Power Only

Multiple Products

Input fuel flow

3%

3%

Input fuel heating value

1%

1%

Export syngas temperature

3 °C (5 °F)

Export syngas pressure (abs.)

½%

Export syngas composition

1%

Export syngas volumetric flow

1%

Export syngas heating value 1%

Export steam temperature 3 °C (5 °F)

Export steam pressure (abs.) ½%

Export steam flow 1%

Plant thermal efficiency 3.5% N/A

Plant electrical output 1% 1%


Challenges—Heat Input Evaluation

Due to the nature of the gasification process the direct heat input measurement is commonly used.

Inlet fuel HHV evaluationFuel flow measurement

Indirect method by conducting a carbon balance

Higher Overall Test Uncertainty than conventional coal-fired plants, due to direct measurement of the fuel flow


IGCC Plant Dry Coal Measurement

Precision Belt Scale System Claimed Accuracy 0.25% (will use conservatively 1% ) Source: Thermo Electron Ramsey)


CQM PGNAA—On-Line Coal Composition

Prompt Gamma Neutron Activation Analysis

PGNAA Measurements

and CalculationsS

AshMoisture

Heating ValueAsh Constituents

SiO2

Al2O3

Fe3O4

CaOTiO2

K2O


A B A*B C t*A*CSensitivity Systematic

UncertaintySystematic Uncertainty Contribution

Standard Deviation of the

Mean

student T Coeffcient

Random Uncertainty Contribution

∑((A*B)^2+t*(A*C)^2 )

(% per %, (%) (%) (%, oF, or oC) (%)Primary coal flow

0.951 3.000 2.853 0.300 2.000 0.5718.467

Primary fuel HHV

0.951 1.200 1.141 0.470 2.570 1.1492.622

Total Uncertainty 3.330

Measured Parameter

A B A*B C t*A*CSensitivity Systematic

UncertaintySystematic Uncertainty Contribution

Standard Deviation of the

Mean

student T Coeffcient

Random Uncertainty Contribution

∑((A*B)^2+t*(A*C)^2 )

(% per %, (%) (%) (%, oF, or oC) (%)Primary coal flow

0.951 1.000 0.951 0.300 2.000 0.5711.230

Primary fuel HHV

0.951 1.000 0.951 0.470 2.000 0.8941.704

Total Uncertainty 1.713

Measured Parameter

Current PTC 47 Test Uncertainty

PTC 47 Proposed Methodology to Reduce the Uncertainty

Example Test Uncertainty—Coal Heat Input

Lower Uncertainty = $5.2 Millions


Corrections To Reference Conditions

Boundary conditions (corrections)Air pressure, temperature and humidityFuel composition, temperatureHeat sink temperature

Controlled operating conditions (no corrections)Process steam, process heat Byproducts quantities and conditionCondensate return temperature


Computer Model or Correction Curves?Tests are almost never conducted at conditions specified in the Contract.Multi-variables curves (developed in polynomial and graphic form) are used to adjust data. The curves generation is done by using simulation program—tedious, expensive, time consuming and not quite correct …PTC 47 correction terms:

30 additive 24 multiplicative

The portable computer have tremendous calculus capability … Why not using the same simulation program directly?


Applying computer programs to convert concurrently all the variables to contract conditions, will insure that the mass, momentum, and energy balance are maintained in thermodynamic equilibrium.This method is not commonly implemented due to lack of a commercially acceptable “validation procedure.”Other test codes make reference to this approach as an alternative procedure. To date no real effort has been done to implement it.

Computer Model or Correction Curves


Summary and Recommendation

Parties in new IGCC projects should:Tackle the significant commercial challenges of performance testingConfigure the plant for proper testingAllow for special instrumentation in the design and cost

The existence of PTC 47 facilitates the process and provides much needed guidance. We can expect many lessons will be learned when the code recommendations start to be implemented.

Thermal performance of IGCC plants could achieve even lower test uncertainties with better instrumentation—more work is needed.


We are looking for some people with a vested interest to participate

on the PTC 47 Committee!

Questions?

challenges facing performance evaluations of igcc … · thermal performance tests are the “final...

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