2.6 Work Package 7 : Biological Content
2.6.2 Research programme
For the realisation of the Work Package 7, all in all, the mentioned below investigations have been accomplished.
• Manual Sorting of reassembled SRF material and determination of the biomass content in percent by weight
• Selective Dissolution Tests with different SRF materials. Determination of the biomass content in percent by weight,
percent by total carbon, percent by calorific value.
• Comparison of the Manual Sorting Method and Selective Dissolution Test
Calculation of the biomass content with manual sorting as defined in the CEN/TS 15440 and with variances in the classification
Determination of water content, TC, ignition lost, calorific value of single fractions Comparison with results of the Selective Dissolution Test
• Further Selective Dissolution Tests with materials provided from WP 4 of the QUOVADIS project Soft pellets
Hard pellets SRF-Samples
• Grain size influence on the Selective Dissolution Test • Reductionistic Method with reassembled SRF material
An overview of the conducted investigations is given in the following table.
Table 23: Investigations for ruggedness and validation testing
Material Manual Sorting (Annex C) Selective Dissolution Method (SDM) (Annex B, D, E)
Grain size influence on SDM (Annex B, D, E) Reductioni-stic method (Annex F) Reassembled SRF from
municipal solid wastes
X X X
SRF from municipal solid wastes
X X
Soft pellets X
Hard pellets X
SRF-samples X
For the investigation of the Selective dissolution method the following exercises have been done: • Twofold, threefold and fivefold determination of single laboratory samples
• Twofold, threefold, fivefold laboratory samples of a single material • Influence of the grain size on the result of the selective dissolution In this report, the results of this experimental phase are reported. 2.6.3 Results
In the following, the results are presented differentiated between the Manual Sorting Method, the Selective Dissolution Method and the Reductionistic Method, whereas the last-mentioned method was not at focus of this project.
Manual Sorting Method
Mainly in this project, the Manual Sorting Method has been used to get values for the comparison with the results of the Selective Dissolution Method. Nevertheless, the working with this Method leads to results, that should be regarded from the TC 343 before upgrading the TS to an European Standard. For the inquiries of the Manual Sorting Method reassembled SRF samples, which were prepared as described in figure 1 have been used.
Figure 62: Flow chart for the preparation of the reassembled SRF samples
SRF- Sample, < 80 mm;
dryed
Manual Sorting acc. to table C.2 of the CEN/TS 15440
Composition of the reassembled SRF- Samples on the basis of
the lumpy material
Calculation of the biomass content acc. to annex C of
CEN/TS 15440
Calculation of the biomass content acc. to
annexe B, D, E of CEN/TS 15440
Threefold selective dissolution for every
SRF-sample acc. to annexe B, D, E of
for the manual sorting. The composition of the reassembled solid recovered fuel samples are shown in Figure 63. Paper/Cardbord 19% Wood 8% Hard plastics 13% Carpets / Mats 3% Fines (< 10 mm) 13% Liquid packaging board 3% Tissue / Sanitary products 12% Fabrics 14% Leather / rubber 3% Soft plastics 12%
Figure 63: Composition of the reassembled SRF samples
The main fractions of the pictured SRF sample were paper / cardboard (including the liquid packaging boards, 21 %), fabrics (14 %), fines (13 %), hard plastics (13 %) and soft plastics as well as sanitary products with 12 % each.
The reassembled SRF samples were used for the determination of the biomass content on the basis of the manual sorting and on the Selective Dissolution Test. For the manual sorting, the classification of some fractions seems problematic, especially:
• Fines
The CEN/TS 15440 classifies the Fines as inert, but the ignition lost, that is about 50 % indicates, that the fines, especially from SRF produced of household wastes, also contain biomass. Therefore, a modified calculation should consider this fraction partly as biomass.
• Liquid packaging board:
The ignition lost of the liquid packaging board, that is classified as paper / cardboard, indicates, that this material partly consists of non-biomass, so that in a modified calculation a part of 80 % of this material should be classified as biomass.
• Fabrics
Especially modern fabrics are often composed of synthetic fibres. For this reason the fabrics were sorted again into the sub fractions “synthetic fibres” and “natural fibres”. The result was, that about 65 % of the material was composed of synthetic fibres. A modified classification only should regard about 35 % as biomass.
• Leather / rubber
The ignition lost of this material again indicates, that this material partly consists of non-biomass. These results should lead to a modified classification for single fractions.
Table 24 summarises the mentioned above proposals and compares them with the regulations of the CEN/TS 15440.
Table 24: Classification of some sorting fractions
Fraction CEN/TS 15440 Modified classification as
proposed from INFA
Fines Inert 50 % Biomass
Liquid packaging board Biomass 80 % Biomass
Fabrics Biomass 35 % Biomass
Leather / rubber Biomass 80 % Biomass
For the investigated SRF samples especially the classification of the Fines and the Fabrics has a greater relevance, whereas the classification of liquid packaging board and leather / rubber is less important, because of the small appearance of these two fractions in the regarded samples.
The biomass content on the basis of the manual sorting analyses of the reassembled SRF samples, has been calculated as described in the CEN/TS 15440 and with modified
classification is shown in Table 24.
Under consideration of the results for the different methods and calculation mode, that are shown in Figure 64, it becomes obvious, that on the basis of the Manual Sorting Method according to CEN/TS 15440 the biomass content might be over-determined.
With this method, the determined biomass content is nearly 60 %. The mentioned above modifications of the fraction classification led to a biomass content of about 56 %, that is more comparable to the result of the Selective Dissolution Test (ca. 54 %). All in all, the shown results confirm the results of previous experiences. In preliminary tests the results also indicates that the biomass content on the basis of the Manual Sorting Method is higher, than the results of the Selective Dissolution Tests.
59,5 55,8 53,9 0 5 10 15 20 25 30 35 40 45 50 55 60 Biomass co ntent [ma ss-% d s]
Manual Sorting accor- ding to CEN/TS 15440
Manual Sorting with
modified Classification Selective Dissolution accor-ding to CEN/TS 15440
Figure 64: Biomass content of SRF samples subject to the used method (manual sorting or selective dissolution) and calculation modus
Method gives a first appraisal of the biomass content of a SRF sample and could be useful for investigations e. g. for internal quality control.
Selective Dissolution Method
For the investigations with the Selective Dissolution Method, this method has been used for reassembled and different original SRF samples. The focus of these investigations were the repeatability, that was tested by multiple investigations of one sample combined with investigations of multiple samples with the same composition. Furthermore it was tested, if the grain size of the laboratory sample influences the result. In the following the essential results are shown, after the restrictions of the applicability, mentioned in the TS has been described.
Restrictions of the Applicability of the Technical Specification
In chapter 1 “Scope of the Technical Specification”, it is remarked, that it is not applicable to:
- Pure fractions of waste, products and by-products classified as CO2-neutral biomass according to Annex G;
- Charcoal, peat and solid fossil fuels like hard coal, coke, brown coal and lignite and to mixtures of these and solid recovered fuels;
- Solid recovered fuels that contain more than 10 % of natural and/or synthetic rubber residues; - Solid recovered fuels that contain a combination of more than 5 % by weight of:
• Nylon, polyurethane or other polymers containing molecular amino groups; • Biodegradable plastics of fossil origin;
- Solid recovered fuels that contain a combination of more than 5 % by weight of: • Wool or viscose;
• Non-biodegradable plastics of biogenic origin; • Oil or fat present as a constituent of biomass.
It is noted, that in typical municipal and assimilated waste the content of nylon, polyurethane, biodegradable plastics of fossil origin, wool, viscose, non-biodegradable plastics of biogenic origin and oil / fat present is rather small and the error is negligible.
On the other hand, beside the solid recovered fuels out of municipal and assimilated waste, further solid recovered fuels, like (dried) sewage sludge, meat and bone meal, tyres and rubber are used. Materials like sewage sludge and the meat and bone meal are considered as CO2-neutral, in Annex A of the Technical Specification, so that the CO2 emissions from the thermal utilisation of these need not to be investigated in terms of biomass or fossil origin. But, tyres consist of natural and / or synthetic rubber, textiles and metal, that means, they partly consist of a biomass fraction. Because concerning to the high amount of annually thermally utilised tyres, the thermal utilisation of tyres is not negligible.
Multiple determinations of the biomass content in reassembled solid recovered fuel samples
With the reassembled solid recovered fuel samples, that were composed as shown in Figure 63, threefold Selective Dissolution Tests have been made. Concerning the results, that are shown in figure 4 to 6, it has to be considered, that the Sample 1 to 5 nearly have the same composition, so that the results for the biomass content should nearly be the same for every sample.
Regarding the results of the threefold determination (Lot A-C) of one sample, it can be stated, that just sample 1 show a slightly greater variation of the lots A to C. The results of the different lots of the other samples are very similar, so that all in all, the results of the single lots can be judged as comparable among each other.
Furthermore, the mass related biomass content of the investigated SRF samples vary from 53.1 % to 55.8 % (Figure ). The average of all samples is about 53.9 % with a comparable low standard deviation of 1.2 %. The slightly higher biomass content in sample 4 might be for reasons of partly different
material composition, that could occur, because the samples were composed out of the lumpy material. These results implicate a good repeatability for the determination of the mass related biomass content.
0 5 10 15 20 25 30 35 40 45 50 55 60 65 1A 1B 1C 2A 2B 2C 3A 3B 3C 4A 4B 4C 5A 5B 5C Bioma ss co ntent [m a ss-% ds]
Sample 1 Sample 2 Sample 3 Sample 4 Sample 5
53.1 53.8 53.7 55.8 53.1
Average all samples 53.9
Figure 65: Mass-related biomass content of the reassembled SRF samples
Concerning the biomass related total carbon content [TC] and the calorific value [CV] related biomass content it generally has to be remarked, that the allocation base also is the dry matter. This has to be taken into account for all the presented results.
The results of the lots A to C of the biomass related TC content show greater ranges, than the ones for the mass related biomass content.
All in all, the biomass related total carbon content, that is shown in Figure 66, vary from 42.3 % to 49.7 %. The average is about 46 % and shows a standard deviation of 3.6 %. Compared with the mass related biomass content, the range of the values of the samples 1 to 5 is higher, that means, that the repeatability for the determination of the carbon related biomass content is not as good as for the mass related biomass content. This could be a result of the fact, that the residue after the selective dissolution is less homogeneous than the laboratory sample before the selective dissolution.
Furthermore the TC-determination necessitates only very small amounts of test material (some mg), that means, that the production of a representative sample is very important. Therefore, an appropriate accuracy for the TC-determination is to demand. This results in appropriate repeated determinations or higher amounts of test material for each measurement (depending on the TC-analyser). Especially because the emission factor for different materials is often calculated on the basis of the TC related biomass content, these demands are very important.
0 5 10 15 20 25 30 35 40 45 50 55 60 1A 1B 1C 2A 2B 2C 3A 3B 3C 4A 4B 4C 5A 5B 5C Bi oma ss r e la te d total car bon c ontent [% TC]
Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 42.3 42.6
46.3
49.7 49.2 Average all samples: 46.0
Figure 66: Biomass related total carbon content of the reassembled SRF samples
The calorific value related biomass content of the reassembled SRF samples varies from 54.2 % to 60.8 % (Figure 67). The average of all samples, that is about 57.9 % shows a standard deviation of 2.6 %. The repeatability seems to be better, than for the total carbon related biomass content, but worse than for the mass related biomass content. The results of the different lots A to C of one sample show a greater variance than for the mass related biomass content and a significant smaller one, than the biomass related TC content.
The variance of the results can be traced back on the fact, that the quality of the residue has the same high influence on the results of the calorific value determination that is illustrated for the determination of the total carbon determination. With respect to the results, an appropriate accuracy for the determination of the calorific value is also demanded. This could often lead to a greater personnel expenditure, because of the small residue amount of a single selective dissolution, that often is not sufficient for the determination of the calorific value, several Selective Dissolution Tests for one material could become necessary to obtain sufficient residue.
0 5 10 15 20 25 30 35 40 45 50 55 60 65 1A 1B 1C 2A 2B 2C 3A 3B 3C 4A 4B 4C 5A 5B 5C Cal o rif ic v a lue re la ted biomas s c ontent [% CV ] 56.7 60.8 57.8 59.9 54.2 Average all samples: 57.9
Sample 1 Sample 2 Sample 3 Sample 4 Sample 5
Figure 67: Calorific value related biomass content of the reassembled SRF samples
Multiple determination of the biomass content in with the Selective Dissolution Method
For further ruggedness tests, different materials, provided from WP 4, have also been investigated concerning their biomass content. These were the materials Hard Pellets, Soft Pellets and SRF- Samples from municipal solid wastes. The following figures show the results for the Hard Pellets. The results for the other materials are given in Table 28. It has to be considered, five parallel samples of every material were investigated. For the mass related biomass content two lots of every sample were investigated. The mass related biomass contents of the single samples and the parallel analyses of one sample are, with the exception of test portion 2 of sample 06-027-005, very comparable among each other (see Figure 68). All the other analyses show biomass results of about 60 %, with a very low variance.
0 10 20 30 40 50 60 70 06-027-001 06-027-002 06-027-003 06-027-004 06-027-005 Probe biomass conten t [mass- % ds]
Test portion 1 Test portion 2
average of all test portions
= average of the test portion 1 and 2
Figure 68 Mass related biomass content in Hard pellets
The TC related biomass content in the Hard pellets is about 58 % (average) and shows a standard deviation of 2.4 %. For this material, the variance is similar to the mass related biomass content.
Hard Pellets 0 5 10 15 20 25 30 35 40 45 50 55 60 65 06-027-001 06-027-002 06-027-003 06-027-004 06-027-005 Sample B io m ass re la ted T C content [ % TC ] Average
Figure 69: Biomass related total carbon content in Hard pellet samples
The biomass content related to the calorific value is about 51 % and show a similar range of values, than the mass related and the TC related biomass content.
Hard Pellets 0 5 10 15 20 25 30 35 40 45 50 55 60 65 06-027-001 06-027-002 06-027-003 06-027-004 06-027-005 Sample CV rel a ted bi omass content [% CV] average
Figure 70: Calorific value related biomass content in Hard pellet samples
An overview on the biomass contents related to the mass, the TC and the calorific value for the three materials, provided from WP 4 are given in the following Table 25.
[%] [%] [%] Hard Pellets 59.4 – 64.9 60.7 5.8 56.0 – 62.1 58.1 4.1 49.3 – 57.0 51.3 6.4 Soft Pellets 24.7 – 28.8 26.7 7.9 18.2 – 21.1 19.3 6.7 14.5 – 21.5 18.0 16.0 SRF from Municipal Wastes 51.7 – 53.4 52.6 2.1 42.5 – 49.9 45.8 7.4 47.1 – 51.5 48.5 4.9
RSD: Relative Standard Deviation
The ranges of the values in the three materials all in all cover mass related biomass contents from 25 to 65 mass-% ds. The relative standard deviation (RSD) of the mass related biomass content for every material is comparably low. The biomass related total carbon contents vary from 18 to 62 % TC, whereas the RSD is comparable to the RSD of the mass related biomass content. The calorific value related biomass content vary from 15 to 57 % CV and the RSD vary from 5 to 16 %. Summarising it can be stated, that, with exception of the calorific value related biomass content in Soft Pellets, the RSD of the investigated biomass contents are comparably low.
Influence of the grain size on the results of the biomass determination with the Selective
Dissolution Method
For the Selective Dissolution Test, the CEN/TS 15440 requires a grain size of < 1 mm. To investigate, if the required grain size is the best for the Selective Dissolution Method, INFA performed Selective Dissolution Tests with SRF-materials, that were crushed to the grain sizes of < 2 mm, < 1 mm and < 0.5 mm. The results are given in the following figures.
0 5 10 15 20 25 30 35 40 45 50 A (0.5) B (0.5) C (0.5) D (0.5) E (0.5) A (1.0) B (1.0) C (1.0) D (1.0) E (1.0) A (2.0) B (2.0) C (2.0) D (2.0) E (2.0) Bio m ass con ten t [ m ass -% d s ]
Average: 38.5 Average: 37.2 Average: 37.4
Figure 71: Mass related biomass content in dependency on the grain size
All in all, the mass related biomass content varied from 34.8 mass-% ds to 39.4 mass-% ds. The averages of the different grain sizes were 38.5 mass-% ds (0.5 mm); 37.2 mass-% ds (1.0 mm) and 37.4 mass-% ds (2.0 mm). The relative standard deviations showed very low values from 2.0 % (0.5 mm), 3.9 % (1.0 mm) and 3.5 % (2.0 mm).
The carbon related biomass contents (see Figure ), found in the different samples varied form 23.3 % TC to 29.2 % TC with averages of 27.9 % TC (0.5 mm); 24.2 % TC (1.0 mm) and 25.4 % TC (2.0 mm). The relative standard deviation are higher, than the ones for the mass related biomass content and for the calorific value related biomass content, what is more a result of the mentioned disadvantages of the TC determination (small amounts, no homogenous residue after selective dissolution; see chapter 3.2.2).
0 5 10 15 20 25 30 35 40 A (0.5) B (0.5) C (0.5) D (0.5) E (0.5) A (1.0) B (1.0) C (1.0) D (1.0) E (1.0) A (2.0) B (2.0) C (2.0) D (2.0) E (2.0) Car b on r e la te d b iom a ss co nt ent [% TC] Average: 27.8 Average: 24.2 Average: 25.4
Figure 72: Carbon related biomass content in dependency on the grain size
The calorific value related biomass contents (Figure 73) vary from 34.8 % CV to 39.9 % CV. The averages are 39.2 % CV (0.5 mm), 36.4 % CV (1.0 mm) and 37.1 % CV (2.0 mm) with very low relative standard deviations from 1.1 % (0.5 mm), 3.2 % (1.0 mm) and 2.5 % (2.0 mm).
0 5 10 15 20 25 30 35 40 A (0.5) B (0.5) C (0.5) D (0.5) E (0.5) A (1.0) B (1.0) C (1.0) D (1.0) E (1.0) A (2.0) B (2.0) C (2.0) D (2.0) E (2.0) Cal o ri fi c value r e la te d b io m ass con te n t [% CV] Average: 37.2 Average: 36.4 Average: 37.1
Figure 73: Calorific value related biomass content in dependency on the grain size
All in all it can be assumed, that the ranges of the results for every particle size seem to be very similar. Regarding the averages, it seems, that the samples with the grain size of 0.5 mm show the (slightly) highest values, but because of the alike ranges, this might be random. Summarising it can be stated, that, on the basis of the present result, an influence of the grain size on the biomass content could not be ascertained.
Investigations on the Reductionistic Method for the determination of the biomass content in Solid
Recovered Fuels
Annex F of the CEN/TS 15440 describes as a further method for the biomass determination, a so called Reductionistic Method. This annex is only informative, but it specifies the procedure for the method of the reductionistic calculation of the biomass fraction in solid recovered fuel. The method shall only be used for internal controlling, when net calorific value of the biomass and non-biomass fraction can be expected to remain stable. The method is not applicable for solid recovered fuels with a significant amount of fat present in the SRF.
The Annex F states, that the Reductionistic Method for determining the biomass content makes use of data relating to solid recovered fuels that are already frequently available. The reductionstic method involves the determination of the biomass fraction based on the relatively stable net calorific values of biomass and non-biomass fractions of SRF. This assumption together with the combination of a mass and energy balance makes it possible to calculate the biomass content [CEN, 2007].
In difference to the Annex F it has to be stated, that the calorific values of biomass and non biomass- fractions of SRF are not frequently available, so that several analyses has also to be done. The