Ole Hedegaard Madsen - International Solid Waste … · Ole Hedegaard Madsen ... The CFD simulation...

New furnace concept improving the electrical efficiency

Ole Hedegaard Madsen

Director Technology, Sales & Marketing

Proprietary and Confidential © 2008 Babcock & Wilcox Vølund A/S. All rights reserved. .2

Agenda

Introduction

What determine the limits for electrical efficiency?

The basic principle and concept - SteamBOOST™

The measurements and results - Alkali/Chloride release during

waste combustion

The numerical laboratory - CFD

Control the combustion process

What is on the horizon


Rankine and other steam power processes

TH

TL

1

2 3

4

Steam Process with super heating

QH

QL

Wturbine

P

Co

Wpump

Boiler

t = (Wturbine – Wpump) / QH

T

s

p2

p1

1

2

3

4

C = 1 – TL / TH


The boundaries for electrical efficiency Fuel = Waste

TH

TL

1

2 3

4

QH

QL

Wturbine

P

Co

Wpump

Boiler

t = (Wturbine – Wpump) / QH

High temperature TH:

Corrosion

• Steam temperature SH

• Flue gas temperature

Particle impact

High velocity

Low temperature TL:

Operating conditions condenser

• District heating system

• Air cooled +

• Water cooled ++

C = 1 – TL / TH


Process

Parameters Unit Guarantee 300-

Hour

Test Waste flow T/h 20 21.72 Heating value lower MJ/kg 12 11.28 Steam production Kg/s 22.42 22.55 Steam temperature ˚C/F 425/797 423/796 Steam pressure bar 50 48.6 Heat input MW 66.66 67.69 Electrical output MW 17.918 18.232 Thermal efficiency % 85.56 87.1 Electrical efficiency % 26.88 26.93 TOC bottom ash % < 2.0 < 0.23 Temperature < SH ˚C/F 620/1148 530/986 Temperature boiler

out ˚C/F 180/356 181/356

Waste Fired Power Plant: Reno Nord, Denmark 2006

Waste Fired Power Plants

High Energy Efficiency

el = 27 %

Th = 97 %


Reduce corrosion by:

Ceramic tiles

New materials

• Inconel

Co-flow super

heaters

CFD modeling


Solid Fuel Combustion on a Grate

The processes in a burning

refuse bed include:

Drying

Ignition

Pyrolysis

Gasification

Solid-phase combustion

Gas-phase combustion

The process is mainly controlled

by mass and heat transfer


Hypothesis

Cl and other corrosive elements are released during the pyrolysis.

Cl is a precursor for release of other elements with influence on

corrosion fx. Na, K, Pb, og Zn.

Char combustion releases enough energy to super heat the steam.


Steam

Super heater

+ 50 °C

Basic Principle for SteamBoost™

Improved electrical efficiency by using fraction of the

flue gas for passing through an extra super heater

Controlling flow by Nozzle design:

Create a double

rotating flow

Uniform flue gas

temperature

• Even in the corners

Good burnout in the

gas phase

• No carbon mono-

oxide

VoluMix SYSTEM™


Rankine and other steam power processes

TH

TL

1

2

3

4

Steam Process with SteamBoost™

QH

QL

Wturbine

P

Co

Wpump

Boiler

t = (Wturbine – Wpump) / (QH + QG)

T

s

p1

1

2

3

4

3’

427˚C ~ 800F

477˚C ~ 890F 3’

Furnace SH

QG

p2


Test at VF5 - WFPP

750 ton/day

Data acquisition

Gas temperature

O2, CO, and CO2

Na, K, Cl, S, Pb, Zn, and Ca in rawgas

SRO data


Data collected

Absolute gas temperature measurements with suction

pyrometer (on-line collection of data)

O2, CO, and CO2 measurements (on-line collection of

data)

Na, K, Cl, S, Pb, Zn, and Ca flue gas concentrations

(collected batch sample sent to laboratory for analysis)

Various data from the plant control system (used to

confirm stability of the unit)


Gas concentrations of O2/CO/CO2


Absolute gas temperatures at ports L2-L6

Proprietary and Confidential

S release - average Cl release - average

Concentration profiles along grate


Concentration profiles along grate

Proprietary and Confidential

Numerical Laboratory = CFD modeling CFD Design:

Heat transfer to Super

Heater

Flow pattern

Uniform flue gas

temperature

SA nozzle design


FASAN WFPP


CFD – analysis of SteamBoostTM

Furnace volume with corrosive gas

Super heater

Furnace volume with non-corrosive gas

Wall

Fasan line 4:

Steam production = 30 ton/h

Temperature = 405 °C

Pressure = 54 Bar

Retention time > 2 sec.

+ 50 °C Super heater needs to transfer

1 MW.


Velocity [m/s] vector plot, in a plane with jets,

close to the centre of the furnace

Modify direction

Re-circulation in super heater is avoided by

moving nozzles


Gas temperature distributions in the furnace

The CFD simulation indicates that it will be possible to extract at least 1 to

1 MW in the final super heater SteamBoost™ and still meet the demand

for sufficient residence time.


Shorter passage through furnace causes unburned

particles in outlet from furnace

Small leakage between the two volumes

CFD – analysis of SteamBoostTM


CO concentrations in the centre of the

furnace - note that scales are logarithmic


Control and adjustment of the position of the main combustion zone:

Ensure correct spilt of flue gases – “corrosive/clean”

Optimize energy flux to the final

super heater

Meet variations in the waste heating value and composition

• Hn, MSW fuel composition

Control speed or primary air


WaVeGRATE™

The Dynamic Movement of

Combustion


Summery

Increased steam data by final super heater in the furnace – new patent

technology - SteamBoost™

Release profile indicates volatile corrosive species to be released early

on the grate – verified by full scale experiments

A high heat flue gas flow is present with low content of corrosive species

• CFD Study indicate that the temperature increase > 50°C

A new flame front control system is develop to optimize the process

The next steps in the research program

• Development of new furnace concept including SA system

• Final development of automatic flame front control

• Full scale test


The Technology – R&D Targets

Ensure B&W Vølund’s position as a

Leading technology supplier in our business

The best research & development

• Power efficiency

• Fuel flexibility

Most advanced design tools

• CFD

• Thermoflex

• 3D - PDMS

The Waste Fired Power plant FASAN, Denmark, 2006

Ole Hedegaard Madsen - International Solid Waste … · Ole Hedegaard Madsen ... The CFD simulation...

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