Production of steam for electricity generation or other purposes using fluidized bed combustion technique when applied to a high sulphur anthracite

Directorate-General For Energy

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Industrial research and development

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• Publié par: DIRECTORATE-GENERAL-FOR-ENERGY
• Nombre de lectures: 29
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

Commission of the European Communities
technical coal research
PRODUCTION OF STEAM
FOR ELECTRICITY GENERATION
OR OTHER PURPOSES
USING FLUIDISED BED COMBUSTION TECHNIQUES
WHEN APPLIED TO A HIGH SULPHUR ANTHRACITE
Report
EUR 9057 EN
Blow-up from microfiche original Commission of the European Communities
technical coal research
PRODUCTION OF STEAM
FOR ELECTRICITY GENERATION
OR OTHER PURPOSES
USING FLUIDISED BED COMBUSTION TECHNIQUES
WHEN APPLIED TO A HIGH SULPHUR ANTHRACITE
M.J. POMERY1), P. 0'BRIEN2)
') NATIONAL INSTITUTE FOR HIGHER EDUCATION
LIMERICK - IRELAND
2) ELECTRICITY SUPPLY BOARD (ESB)
Project Department
Stephen Court
18/21 St. Stephen's Green
DUBLIN 2
IRELAND
Contract No. 7220-EC/882
FINAL REPORT
Directorate-General Energy
1984 EUR 9057 EN Published by the
COMMISSION OF THE EUROPEAN COMMUNITIES
Directorate-General
Information Market and Innovation
Bâtiment Jean Monnet
LUXEMBOURG
LEGAL NOTICE
Neither the Commission of the European Communities nor any person acting on behalf
of the n is responsible for the use which might be made of the following
information
ι ECSC — EEC — EAEC, Brussels · Luxembourg, 1984 CONTENTS
Summary Page
1.0 Introduction 1
1.1 Energy in Ireland
1.2 Irish Coal Resources 2
1.3 Flui di sed Bed Combustion 3
Advantages in the Context of Irish Coals
2.0 Design of Flu1d1sed Bed Combustion System 5
2.1 Factors influencing design
2.1.1 Location 5
2.1.2 Sizing of Combustion
2.2 Requirements of Combustor 6
2.2.1 Temperature of Operation
2.2.2 Fluidising Velocity 7
2.2.3 Air Distributor 8
2.2.4 Heat Removal from Combustor
2.2.5 Start-up of Combustor 9
2.3 Andlliary Equipment 10
2.4 Instrumentation and control1
3.0 Coals Used3
4.0 Operating Experiences 1
4.1 Cold Fluidi sati on Tests
4.2 Start-up of Combustor4
4.3 Coal Combustion5 Page
5.0 Short Term Combustion Tests 15
5.1 Test Method 16
5.2 Results from short term combustion tests
5.2.1 Effect of Fluidising Velocity on Carbon Burnout 1
5.2.2t of Bed Temperature on Carbon Burnout 17
5.2.3 Effect of Excess Air on Carbon Burnout 1
5.3 Conclusions from short term combustion tests8
6.0 Retention of Sulphur by Limestone 1
6.1 Selection of Limestone8
6.2 Results from Combustor 19
7.0 Long Term Testing 21
7.1 Operating Conditions for Test
7.2g Characteristics of Combustor for Tests 22
7.3 Results from Steady State Testing3
7.3.1 Combustion of Anthracite 2
7.3.2 Sulphur Retention
7.4 Reactivation of FBC System from Slumped Conditions 24
7.4.1 Slumping Procedure4
7.4.2 Reactivation 2
7.5 Implications of Testwo^k5
8.0 Materials Evaluation7
8.1 Method of Test
8.2 Execution of Test 28
8.2.1 Preparation of Specimens
8.2.2 Exposure ofsPage
8.3 Results 29
8.3.1 General Observations
8.3.2 Deposition Effects
8.3.3 Corrosions 30
8.3.3a A.I.S.I. Type 316 Alloy
8.3.3b Incoi oy 800 Alloy1
8.3.3c Inconel 600 Alloy
8.4. Implications of Results2
9.0 Conclusions 3
10.0 References4
Figures 1 -0
Tables I - VII
Appendices I - V SUMMARY
This report presents results obtained for the fluidi sed bed
combustion (FBC) of Irish Anthracites. A review of available
literature showed that large deposits of anthracite exist in
SE Ireland. However, because of high sulphur contents and the
occurrence of these deposits in thin seams, these anthracite
reserves can be considered as low grade. FBC was considered
as an attractive method of utilising these coal reserves
particularly as the addition of crushed limestone to the
fluidised bed reduces emissions of sulphurous pollutants to
tolerable level s.
A 0.6 χ 0.6 m FBC system was designed and constructed at the
National Institute for Higher Education (NIHE), Limerick.
This combustor was used to investigate the combustion of high
sulphur anthracites with and without limestone additions to
the fluidised bed. Several combustion tests were carried out
at fluidising velocities of 1.0, 1.25 and 1.5 m s"1, excess
air levels of 10, 25 and 40% v/v and at operating
temperatures in the range 850 - 950°C.
The results obtained showed that it was possible to burn the
anthracite, sized 98% less than 2.5 mm, successfully.
However, the extents of carbon burnout were disappointing.
The greatest extent (84%) was achieved at a fluidising
velocity of 1.0 m s"1, an excess air level of 25% v/v and
an operating temperature of 900°C. At thisg
velocity however, there was a tendency for coarse coal
particles to segregate to the bottom of the fluidised bed.
Accordingly it was found necessary to operate at a velocity of
1.25 m s~', the other parameters being held the same. Under
these conditions segregation did not occur but a reduction in
the extent of carbon burnout (80 - 82%) was recorded.
Possible methods for improving the extent of carbon burnout
are discussed. The response of the FBC system to transient
conditions generated during slumping and reactivation are
reported and discussed with respect to load control.
Several limestones were assessed with respect to their ability
to retain sulphur within the fluidised bed using
thermogravimetric techniques. From these results the most
suitable limestone for use at a temperature of 900°C was
selected. This limestone, sized less than 2.5 mm, was
employed in tests using the combustor. It was found that
calcium to sulphur mole ratios of at least 5:1 were required
to complete the required levels of sulphur retention (95%).
Evidence is presented which shows that fine (1 urn) particles
of coal ash become attached to the surface of the sulpha ting
limestone. This phenomenon reduces the ability of the
limestone to react with sulphur oxides thus accounting fore
high calcium to sulphur mole ratios required to complete the
necessary level of sulphur retention.
Three alloy materials, Inconel 600, Incoloy 800 and AISI Type
316 were exposed to the environment within the fluidised bed
for 80 h at a temperature of 900^C. During this time period
the temperature of the fluidised bed was reduced to less than
600^0 on seven occasions during slumping/reactivation
operations. The resistance of these materials to corrosion was poor. For the Inconel 600 alloy the extent of corrosion
was particularly severe with the result that a 3 mm thickness
of this material was completely corroded. The Incoi oy 800
alloy also behaved poorly suffering penetration by sulphur to
depths of 0.30 mm. The AISI Type 316 alloy behaved more
promisingly. However, much more work is required in this area
before materials for in-bed components can be selected with
confidence.