D19 5 EN Chemical Properties - p29596.typo3server.infoEN 15290 major elements Detection methods For the detection of the concentrations of Al, Ca, Fe, Mg, P, K, Si, Na, Ti in the digests

Chemical methods for solid biofuels

Martin Englisch

ofi – Österreichisches Forschungsinstitut für Chemie und Technik

Fritz Bakker

ECN- Energy Research Centre of the Netherlands

Solid fuels

solid biofuel

combustiblefraction

non combustiblefraction

water volatiles charash

Composition of wood

Chemical composition:

51% carbon

42% oxygen

6% hydrogen

< 1% nitrogen

< 0,1% sulphur, halogenes

Components:

50% cellulose

25% hemicellulose

25% lignin

< 5% resins etc.

< 1% ash formingminerals

Harmful substances, pollutants

N, S, halogenides are environmental harmful substances

Nitrogen− Fuel nitrogen is mainly responsible for NOx-emissions

− Origin in wood: natural content up to 0,3%, higher concentrations are due to glues or other adhesives

Sulphur− Mainly from organic sulphur compounds SO2 is formed during combustion which

forms sulphurous acid causing acidic rain

− Origin in wood: usually very low concentrations, significant amounts may occur if e.g. lignosulphonate is used as binding agent in pellets

Chlorine− Forms hydrochloric acid in combustion which is mainly responsible for corrosion

− Origin in wood: usually very low concentrations, contamination from plant sprays, fertilizers, thawing salts. In other solid biofuels higher concentrations are often found – very critical chemical parameter!

NOx-formation

Aerosol formation

Chemical test methods

EN 15104 Solid biofuels — Determination of total content of carbon, hydrogen and nitrogen — Instrumental methods

EN 15289 Solid biofuels — Determination of total content of sulphur and chlorine

EN 15105 Solid biofuels — Methods for determination of the water soluble content of chloride, sodium and potassium

EN 15290 Solid biofuels — Determination ofmajor elements

EN 15296 Solid biofuels — Determination ofminor elements

EN 15297 Solid biofuels — Calculation of analyses to different bases

EN 15104 Determination of total content of carbon, hydrogen and nitrogen — Instrumental methods

Principlesample is burnt completely in oxygen

gaseous products: carbon dioxide, water vapour, elemental nitrogen and/or oxides of nitrogen, oxides and oxyacids of sulphur and hydrogen halides

Treatment of gases: hydrogen associated with sulphur or halides is liberated as water vapour

Oxides of nitrogen are reduced to elemental nitrogen

products of combustion which interfere with the subsequent gas-analysis procedures are removed

Carbon dioxide, water vapour and nitrogen are determined quantitatively by appropriate instrumental gas- analysis procedures

EN 15104 carbon, hydrogen and nitrogen — Instrumental methods

Instruments and reagents

Automatic systems are used e.g. Leco, Elemental

− Requirements on performance of systems is given in the standard

Calibration standards are used for calibration

Accuracy of method is tested by certified reference materials

For Nitrogen, the Kjeldahl method may be used!

EN 15104 carbon, hydrogen and nitrogen — Instrumental methods

ProcedurePreparation of test sample and test portionCalibration of systemAnalysis of sampleExpression and calculation of resultsPerformance of methods:

Maximum acceptable differences between results

(on dry basis)

repeatability reproducibility

Carbon content 0,5 % absolute 1,5 % absolute

Hydrogen content 0,25 % absolute 0,5 % absolute

Nitrogen content 10 % relative if N > 0,5 %

0,05 % absolute if N < 0,5 %

20 % relative if N > 0,5 %

0,1 % absolute if N < 0,5 %

Results from BioNormII nitrogen

Precision of method

Nitrogen Contentmean

[wt %, d.b.]

R abs [%]

R rel[%]

r abs [%]

r rel[%]

wood without bark 0,060 0,060 99,2 0,027 45,1

woodchips 0,106 0,087 82,0 0,079 74,7

hardwood with glue 0,342 0,144 42,2 0,036 10,5

rapestraw 0,406 0,159 39,2 0,090 22,1

bark 0,669 0,221 33,1 0,076 11,4

straw 0,713 0,191 26,7 0,078 10,9

cynara 1,006 0,241 24,0 0,107 10,6

Orujillo (olive) 1,314 0,333 25,3 0,090 6,8

Reproducibility Repeatability

EN 15289 Determination of total content of sulphur and chlorine

PrincipleCombustion and transfer of acidic gaseous components into solution

• Combustion in an oxygen bomb and absorption of the acidic gas components in an absorption solution (method A);

• Decomposition in closed vessels as described in EN15290 (method B).

EN 15289 Determination of total content of sulphur and chlorine

Determination of sulphate and chloride in receiving solution

• Ion chromatography applying the principles of EN ISO 10304-1;

• ICP, applying EN ISO 11885

• Other suitable analytical methods.

• A large number of methods for the quantification of sulphate andchloride exists but detection limits and precision vary significantly.

Automatic equipment may be used when the method is validated with biomass reference samples of an adequate biomass type

X-ray fluorescence may be used to determine sulphur and chlorine directly in the solid biofuel samples

EN15289 sulphur and chlorine

Combustion in a closed bombMost frequently used method, combination with NCV1 g sample is pressed to a pellet, put into a quartz glass or metal crucible and combusted in 30 bar oxygenEventual use of combustion aid− Liquid combustion aid e.g. dodecane− Solid combustion aid: combustion bag or capsule with known weight

Combustion in a closed bombAfter combustion absorption solution is filled in a flask (50 or 100 ml)

Attention:− Check complete combustion− Thoroughly rinse the bomb− Eventual chemical treatment

of the solution − Check losses during venting

(gas washing bottle)

EN 15289 sulphur and chlorine


Detection methodsIon chromatography− is the recommended method for the detection of sulphate and

chloride (EN ISO 10304-1)− use a syringe equipped with a 0,45 µm pore size filter

Other analytical methods:

Method Cl S References (examples)

ICP X X EN ISO 11885photometric (colorimetric) X DIN 51727

Turbidimetric X ASTM D516 - 02

photometric titration X ISO 587

Coulometric X DIN 38405 - 1 (method D1-3)

potentiometric titration X DIN 38405 - 1 (method D1-2)


Precision of method

Maximum acceptable differences between resultsContent of sulphur and chlorinedry basis

Same laboratory(Repeatability)

Different laboratories(Reproducibility)

Chlorine ≤ 500 mg/kg> 500 mg/kg

50 mg/kg10 % of the mean result


Sulphur ≤ 500 mg/kg> 500 mg/kg



Results from BioNormII for chlorine

Precision of method

Chlorine contentmean

[wt %, d.b.]

R abs [%]

R rel[%]

r abs [%]

r rel[%]

wood without bark 0,003 0,006 174 0,003 93

woodchips 0,005 0,010 185 0,006 103

bark 0,010 0,010 99 0,005 53

hardwood with glue 0,015 0,012 83 0,007 51

straw 0,11 0,030 26 0,016 14

Orujillo (olive) 0,20 0,043 21 0,013 7

rapestraw 0,28 0,065 23 0,027 10

cynara 1,59 0,44 27 0,18 11

Reproducibility Repeatability

EN15105 Solid biofuels — Methods for determination of the water soluble content of chloride, sodium and potassium

Principle

The fuel sample is heated with water in a closed container at 120 °C for 1 hour.

The concentrations of chloride, sodium and potassium in the obtained water extract are determined by:

− Chloride: Ion-Chromatography (IC) or potentiometric titration with silver nitrate (any contents of water soluble bromide and iodide will be included in the determination)

− Sodium and potassium: Flame Emission Spectroscopy (FES) or Flame Atomic Absorption Spectroscopy (FAAS) or Inductively Coupled Plasma Optical Emissions Spectroscopy (ICP-OES).

EN 15105 water soluble content of chloride, sodium and potassium

Precision of method

Maximum acceptable differences between resultsContent of water solubleelement,

as analysed same laboratory(repeatability)

different laboratories(reproducibility)

Chloride ≤ 500 mg/kg

> 500 mg/kg

50 mg/kg

10 % of the mean result

100 mg/kg


Sodium / potassium ≤ 100 mg/kg

> 100 mg/kg

10 mg/kg


20 mg/kg


EN15290 Solid biofuels — Determination of major elements

Major ash forming elements:

Al, Ca, Fe, Mg, P, K, Si, Na, Ti

Principle

The sample is digested in a closed vessel by reagents, temperature and pressure. The digestion is either carried out directly on the fuel (part A) − 500 mg sample, 3,0 ml H2O2 (30 %), 8,0 ml

HNO3 (65 %) and 1,0 ml HF (40 %) in the vessel.

− The heating of the vessel should not be to fast. A heating procedure is given in the standard

− After cooling HF is neutralised by H3BO3 (4 %). Reheat the sample.

− After cooling, transfer the digest to volumetric flask.

or on a 550 °C prepared ash (part B).

EN 15290 major elements

Detection methods

For the detection of the concentrations of Al, Ca, Fe, Mg, P, K,Si, Na, Ti in the digests the following methods can be used:

− ICP/OES according to EN ISO 11885.

− ICP/MS according to EN ISO 17294-2.

− AAS according to EN ISO 7980, ISO 9964-1 and ISO 9964-2.

− FES according to ISO 9964-3.

EN 15290 major elements - Precision

5,18110,31651 5981,47315Oliveresidues

6,6411,76545,56915Wood chips

Fe

4,36077,31 03514 21606513Oliveresidues

1,6246,61001 5021,85411Wood chips

Ca

4,71107,21702 36405511Oliveresidues

4.121884755712Wood chips

%mg/kg%mg/kgmg/kg%Al

CVrsrCVRSRxoln

n= number of lab. i=individual values, o=% % of replicate determ. x= overall meanSR=reproducibility std dev. CVR= coefficient of variation of reprod. sr= repeatability std.devCVr= coefficient of the variation of the repeatability

EN 15290 major elements – Precision

1,94686,41 56524 5245,55211Oliveresidues

1,81211,1776913,16313Wood chips

K

3,9588,51271 48806513Oliveresidues

3,426,75743,65311Wood chips

P

4,71497,72423 14306513Oliveresidues

1,737,21419406012Wood chips

%mg/kg%mg/kgmg/kg%Mg

CVrsrCVRSRxoln


EN 15290 major elements – Precision

4,467,9111381,85411Oliveresidues

5,90,327,40,405,54,4439Wood chips

Ti

5,49234017104910Oliveresidues

142486130449Wood chips

Na

7,776912,21 22610 0434,04910Oliveresidues

11,236331063202,5398Wood chips

%mg/kg%mg/kgmg/kg%Si

CVrsrCVRSRxoln


EN 15296 Solid biofuels — Determination ofminor elements

Minor elements: Arsenic, Cadmium, Cobalt, Chromium, Copper, Mercury, Manganese, Molybdenum, Nickel, Lead, Antimony, Vanadium and Zinc principle

Method similar to major element

EN 15296 minor elements

Detection methods

As, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Sb, Se, Sn, V and Zn can be detected by ICP-MS, ICP-OES or GF-AAS provided that the detection limits of the used method are sufficient for the fuel specifications

As and Se can be determined by HG-AAS (EN ISO 11969).

Hg can be determined using CVAAS (EN 12338)

ICP/OES (EN ISO 11885)

ICP/MS (EN ISO 17294-2)

Other instrumental methods may be used after validation with biomass reference material of a suitable type.

EN 15296 minor elements - Precision

5,40,056120,1281,041,85411Oliveresidues

2,90,0109,70,0330,344,4439Wood chips

Co

200,0050230,00570,0250408Oliveresidues

2,90,0096,40,0210,323,16313Wood chips

Cd

6,00,0369,50,0570,607,3388Oliveresidues

340,012640,0230,03610276Wood chips

%mg/kg%mg/kgmg/kg%As

CVrsrCVRSRxoln



220,0026400,00480,0122,24410Oliveresidues

130,0010230,00160,00723,6276Wood chips

Hg

3,40,858,602,22507515Oliveresidues

7,000,091120,161,296,65712Wood chips

Cu

7,61,08243,414,347215Oliveresidues

210,077310,120,374,4439Wood chips

%mg/kg%mg/kgmg/kg%Cr

CVrsrCVRSRxoln



5,40,686,50,8212,51,85411Oliveresidues

70,042170,1030,6004710Wood chips

Ni

8,20,018250,0560,227,5378Oliveresidues

410,012520,0150,0280235Wood chips

Mo

3,61,462,52,5440,22,77315Oliveresidues

1,43,781817,72611,46914Wood chips

%mg/kg%mg/kgmg/kg%Mn

CVrsrCVRSRxoln



4,50,83111,9718,235,37115Olive residues

4,80,67141,9413,845,47015Wood chips

Zn

4,90,21110,454,267,35111Olive residues

120,009230,0180,0764,5429Wood chips

V

110,010150,0140,0944245Olive residues

100,001310,00420,0130255Wood chips

Sb

9,30,357150,5753,836,75613Olive residues

9,60,072160,1170,7510,9419Wood chips

%mg/kg%mg/kgmg/kg%Pb

CVrsrCVRSRxoln


EN 15296 minor elements

Precision of methodComing soon!

Validation in progress

EN 15297 Solid biofuels — Calculation of analyses to different bases

Symbols

The symbols employed in the subsequent clauses are as follows, with the suffixes "ad" (air dried), "ar" (as received), "d" (dry), "daf" (dry, ash free) where appropriate:

− A ash (EN 14775)

− C total carbon content (EN 15104)

− Cl total chlorine content (EN 15289)

− qp,net net calorific value at constant pressure (J/g) (EN 14918)

− H total hydrogen content (EN 15104)

− M moisture content (EN 14774)

− N total nitrogen content (EN 15104)

− O total oxygen content (percentage by mass)

− S total sulphur content (EN 15289)

EN 15297 Calculation of analyses to different bases

Hydrogen

Oxygen

Net calorific valuedifficult – still errors in standard!

EN 15297 Calculation of analyses to different bases

Thank you for the kind attention!

ofi – Österreichisches Forschungsinstitut für Chemie und TechnikFranz-Grill Str. 5, Arsenal Objekt 213A-1030 WienTel.: +43-1-7981601-490Fax: +43-1-7981601-480

www.pelletstesting.com

Documents

D19 5 EN Chemical Properties - p29596.typo3server.infoEN 15290 major elements Detection methods For the detection of the concentrations of Al, Ca, Fe, Mg, P, K, Si, Na, Ti in the digests