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Technical Difficulties in Performing Industrial Solvent Management Plans
Conference Paper · September 2006
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TECHNICAL DIFFICULTIES IN PERFORMING INDUSTRIAL
SOLVENT MANAGEMENT PLANS
Vanda Martins and Ana Fonseca
CEMAS – Centre of Modelling Studies and Environmental Systems Analysis
Fernando Pessoa University, Praça 9 de Abril, 349, 4249-004 PORTO, PORTUGAL.
Tel: +351 22 507 1308; Fax: +351 22 550 82 69; E-mail: afonseca@ufp.pt
SUMMARY
A large percentage of wood processing industries are in the scope of the European Union
legislation regarding volatile organic compounds’ emissions (VOC) associated with
solvents usage (Directive 1999/13/CE), namely in wood impregnation, wood coating and
wood lamination activities. This legislation requires each industrial operator to perform a
solvent management plan (SMP) to calculate the amount of fugitive VOC emissions and
compare it with an imposed limit. The SMP is therefore an important part of the
environmental management procedures for several industries. The aim of this work is to
compare different approaches for performing the SMP in industrial context, and identify
the main factors of inaccuracy in the quantification of fugitive emissions. The results
obtained indicate that, depending on the methodology used in the SMP, different
conclusions regarding the compliance of the Directive are achieved. Several factors of
inaccuracy in the calculation of the fugitive emissions were identified. According to the
results of this work, the most important of those is the extrapolation of the VOC
emissions in waste gases for the time period of the SMP. Since the compliance with the
requirements of this legislation must be achieved no latter than 31st October 2007, the
main conclusion of our work is that more technical information should urgently be
provided to industry regarding the methodology to perform a SMP.
INTRODUCTION
Volatile Organic Compounds (VOCs) are gaseous air pollutants that, under certain weather
conditions, contribute to the formation of photochemical oxidants (smog). This
photochemical pollution causes risk at different scales, either in human health (sore eyes, sore
throats and respiratory problems), as well as in vegetation (due to lower light intensity) and in
the green house effect.
VOCs are emitted to the atmosphere in several processes, namely transport, industry and
agriculture. According to a report of the European Environmental Agency (EEA), the main
source of man made VOC emissions in the EU in 1999 was ‘solvent and other product use’
(EEA, 2002). The emission of VOCs to the atmosphere resulting from the use of organic
solvents in certain activities is regulated in the European Union (EU) by the Council
Directive 1999/13/CE, which will be fully in application in October 2007. With this
legislation, known as the Solvent Emission Directive (SED), the EU seeks a 57% drop in
industrial VOC emissions in the period 1990-2010 (Belis-Bergouignan et al., 2004). The
methodologies proposed in the SED are: promoting substitution of products and/or
technologies; using mass balances to verify emission limits (Solvent Management Plans); and
opening the possibility of option for alternative measures to reduce emissions (Reduction
Scheme). More detailed information on this legislation and its requirements may be found,
for example, in GFEA (2002), SEEG (2003) or Fonseca (2004).
An important tool introduced by the SED is the ‘Solvent Management Plan’ (SMP) which is
used to verify the compliance with emission limit values through mass balances. All the
installations in the scope of the SED are required to perform a SMP, therefore this procedure
is of high importance for the environmental management of several industries.
The aim of this work is to compare different approaches for carrying out the SMP. In this
process it is aimed to identify the main factors of inaccuracy that might influence the results
obtained in the SMP, including, in several cases, conclusions relating the compliance with
emission limit values. A real industrial case will be used as an example to illustrate these
findings.
THE SOLVENT MANAGEMENT PLAN
All the installations executing at least one of the activities listed on Annex I of the SED, with
a total annual solvent consumption above the threshold value defined in Annex II-A of this
regulation, is required to perform a SMP.
The SMP consists in the identification and quantification (if possible) of all the solvent’s
inputs and outputs in a given installation. Its purpose is to provide the operator with
information concerning the total amount of solvent used in the SED activity (input) and the
destination given to this solvent (output). Through adequate mass balances it is possible to
obtain the total VOC emissions or the fugitive VOC emissions, which have legal limits
(Annex II-A of the SED). The results obtained in this process will serve the following
purposes: evaluation of the compliance with emission limit values; and identification of
possible reduction measures.
Annex III of the SED presents guidance for performing SMPs. In this guidance, 2 possible
inputs and 9 possible outputs are identified for the solvents (see Table 1).
Table 1: Possible inputs and outputs of solvents in a SED installation (adapted from Annex III of the SED)
Inputs
I1
Solvents purchased (including in preparations) and used in the SED activity
I2
Solvents recovered and reused in the SED activity
Outputs
O1
VOC emissions in waste gases
O2
Solvents lost in water
O3
Solvents in the final product as waste or contaminants
O4
Uncaptured VOC emissions to air
O5
Solvents lost or destroyed in gaseous or waste water treatment devices
O6
Solvents contained in collected waste
O7
Solvents contained in preparations sold or intended to be sold
O8
Solvents recovered for reutilization outside the SED activity (not counted on I2
or O7)
O9
Solvents released in any other way
In Annex III of the SED two alternative equations are proposed for calculating fugitive
emissions (F), which are subject to emission limit values for some SED activities:
F = O 2 + O 3 + O 4 + O 9 (Eq. 1)
F = I1 − O1 − O5 − O6 − O7 − O8 (Eq. 2)
Equation (1) implies the direct measurement of the fugitive emissions, while in equation (2)
the fugitive emissions are calculated through the difference between the solvents’ input and
the solvents’ emissions that are controlled (not fugitive). The fugitive emissions value which
is to be compared with emission limit values is the ratio (expressed in %) between F and the
total input of solvent (I1+I2).
Some SED installations are due to calculate a total VOC emission value (E), given in Annex
III of the SED by:
E = F + O1 (Eq. 3)
This total VOC emission is then to be divided by the relevant product parameter (for
example, m3 of impregnated wood in the time frame of the SMP, for the activity of wood
impregnation) and compared with the corresponding emission limit value.
No orientation regarding the methodology to quantify the inputs/outputs necessary to perform
a SMP is given in the SED, or, to our knowledge, in any other EU official publication.
Nevertheless, it is possible to find some guidance on the interpretation of the SED published
by some State Member’s Environmental Agencies (for example, Germany (GFEA, 2002) and
Scotland (SEEG, 2003)), and by industrial associations (for example FIM, 2004), as well as
by consultancy organizations (for example Verspoor, 2002).
It is not expected that a single SED installation performing its SMP should have to quantify
all the inputs and outputs of solvents referred in Table 1. For example, in a study performed
by the German Federal Environmental Agency (GFEA, 2002) concerning 7 SME wood
coating installations, in the performance of their SMP none of those quantifies O5, O7, O8 or
O9, only one quantifies O3, two quantify O2 and two quantify I2. All of them quantify I1, O1
and O4, and almost all (6 out of 7) quantify O6.
In deciding which inputs/outputs to quantify in its SMP, the operator of a SED installation
should keep in mind the purpose of the SMP and keep it as simple as possible. The total
amount of solvents consumed (C) in one year in each SED activity has to be determined in
order to verify if the installation is in the scope of this legislation. Annex III of the SED
defines C as:
C = I1 − O8 (Eq. 4)
Therefore I1 has always to be quantified, as well as O8 in those installations where solvents
are recovered and reused outside the SED activity. As for the other input/output streams, in a
first approach the operator should seek to quantify those which are expected to have the most
significant impact in the total amount of emissions. For example, consider a SED installation
where a SMP is being performed to verify the compliance with the corresponding fugitive
emissions limit in Annex II-A. Considering that equation (2) is being used to quantify F, the
operator should start by quantifying the output which he expects to be the highest between
O1, O5, O6, O7 and O8. Supposing the decision falls on the quantification of O1, equation (2)
should then be used to calculate F, considering all the other outputs as zero. If the value
obtained for F is below the corresponding limit, then no further quantifications are necessary
since compliance with this limit has already been proved. If, on the other hand, F is higher
than the limit, then the operator has to quantify one of the other solvent outputs (in this case
O5, O6, O7 or O8) and the calculation of F should be repeated, including this new output.
This procedure should be repeated, quantifying as many outputs as necessary until the
compliance with the fugitive emission limit is achieved.
As can be seen by the previous example, the SMP will probably follow a ‘trial and error’
sequence, and the establishment of the adequate procedure may take some time. Besides, in
some cases there is more than one methodology to quantify the inputs and outputs, and
several inaccuracy factors might affect the results obtained. This will be shown on the
following case study.
CASE STUDY: PERFORMING A SMP IN A PRINTING PROCESS
The applicability of the SED was tested in the printing activity of a flexible packaging
company. For this purpose, the total consumption of solvents (C) had to be calculated through
equation (4) in a one year basis. Since in this particular case no solvents are recovered and
reused (O8=0), C is equal to the total solvent purchased and used in the printing activity (I1).
These included pure solvents, as well as solvents contained in inks and varnishes. The solvent
content on these products (or any other coating preparation) can be obtained through two
different methodologies (ETBPP, 1998; GFEA, 2002): through direct request to the supplier,
or through the analysis of the corresponding Safety Data Sheets (SDS) (FIM, 2004, only
refers this last methodology).
In this case study, these two methodologies were used to calculate I1. The main difficulties
found were related to the SDS methodology, since most of the SDS consulted referred a
range of values for the solvent composition. Therefore the calculations led to a range of
values of I1 when using this methodology. Another difficulty found was he verification, in
some cases, that the data given by the supplier differed from the information on the SDS.
As can be seen in Table 2, the two methodologies used to quantify I1 gave different results,
reaching a 22% difference in the values obtained. In the present case study, since the
threshold value listed in Annex II-A of the SED is 15 ton solvents/year, the conclusion on the
applicability of this legislation is not affected by the different results obtained. Nevertheless it
is important to point out that these differences might lead to different conclusions on the
applicability of the SED in the case of activities having total consumption values closer to the
corresponding threshold value. In any case, these differences will also influence the SMP
results since I1 is an important variable in this process, as will be shown in the following
calculations.
Table 2: Results obtained in the quantification of I1 through two different methodologies
I1 obtained through supplier data
I1 obtained through SDS data
(ton solvents/year)
(kg solvents/year)
193,6
from 195,3 to 235,6
For the performance of this SMP, in a first approach it was considered that the main output of
solvents was O1: VOC emissions in waste gases. To quantify this output each of the stacks of
the printing area was sampled to determine the total gas flow rate and the VOC content of the
gaseous emission. The VOC concentration in the gas was obtained through gaseous
chromatography with a flame ionisation detector. The total mass flow rate of COVs was then
calculated by the multiplication of the gas flow rate by the VOC concentration. The obtained
value was a total emission of 9,9 kg C/h, considering all the stacks in the printing area. It is
important to point out that this value was obtained in a single measurement, performed in
typical operating conditions: the preparations being used in the printing section during the
stack gas analysis had a solvent composition equivalent to the average of the total
preparations identified in I1. Nevertheless a significant error is probably associated with this
measurement, since short-term sampling cannot give an accurate account of emissions if not
used in connection to continuous measurements (Ojala et al., 2006). This is due to the typical
wide range of possible different VOCs contained in the waste gas, together with other gases
and water vapour, which difficults the efficiency of the sampling process and of the VOC
analysis (Domeño et al., 2004).
To obtain the total VOC stack emissions in a one year basis (time frame selected for the
present SMP), the total emission obtained previously of 9,9 kg C/h has to be multiplied by the
total hours of effective machine operation during one year (FIM, 2004). Again two important
error factors are identified in this process: one is the difficulty on estimating accurately the
total hours of effective printing operation since many different factors influence this
parameter (like, for example, maintenance procedures or stops due to product change), and
the other is the direct extrapolation of the results of the VOC content in waste gases obtained
in a single measurement to a one year basis. The alternative methodology to obtain the total
VOC emitted in the waste gases is continuous monitoring of the stack emissions. This
process would, without any doubt, give a more accurate result, but the expenses of the
associated procedure are unaffordable to the majority of installations in the scope of this
legislation.
In the present case study, since continuous monitoring was out of the question, the estimation
of the duration of total effective printing during one year was 8016 h. Therefore the value
obtained for O1 was 79 358 kg C/year. Given the previous considerations on the several error
factors affecting this result, it will not seem exaggeration to consider a 10% error in the value
obtained, therefore O1 is estimated to be in the range of 71 422 to 87 294 kg C/year.
In order to use equation (2) to calculate F, I1 and O1 must be expressed in the same units,
which is not the case yet. Therefore it is necessary either to convert O1 to mass of solvent
emitted, or to convert I1 to mass of carbon purchased. In any case the chemical composition
of the solvents and preparations must be known. Again the SDS were analyzed to seek this
information, and it was found that the main component of the purchased solvents and
preparations was ethanol (C2H5OH), among ethyl acetate (CH3COOC2H5) and other
compounds present in very small amounts like metoxy propanol (CH3CHOCH3C3H6OH).
Two different calculations were performed: O1 was converted to mass of solvent emitted
considering that the VOC emission was totally ethanol, and the same conversions was made
considering an emission of 90% ethanol and 10% ethyl acetate. The results obtained are
shown in Table 3. As can be observed in this table, for the present case study the possible
different compositions in the waste gas do not have a significant influence in the results
obtained. Nevertheless this conclusion may not be valid for other printing processes or other
SED activities.
With the results obtained so far it is now possible to calculate the first iteration of the fugitive
emissions (F) using equation (2). This is a first iteration since, as explained above, all the
other controlled outputs of solvent will be considered zero in this phase. Compliance with the
fugitive emission limit value is achieved if F is less or equal than 20% of the solvent
consumption (Annex II-A of the SED for the printing activity of this case study).
Table 3: Values obtained for O1 considering two different waste gas compositions
O1 considering 100% ethanol in the
waste gas
(ton solvents/year)
O1 considering 90% ethanol and 10%
ethyl acetate in the waste gas
(ton solvents/year)
152,1
151,8
A summary of the results obtained with this SMP are presented in Table 4. Different values
of F were obtained, depending on the methodology used for the quantification of I1. And still
different values of F were also obtained when considering a 10% error in the quantification of
O1.
Table 4: Different results obtained in the quantification of the fugitive emissions (F)
I1
(ton solvents/year)
O1
(ton solvents/year)
Measured
Supplier
data
193,6
90% of
measured
110% of
measured
Measured
SDS
(maximum
value)
235,6
90% of
measured
110% of
measured
Measured
SDS
(minimum
value)
195,3
90% of
measured
110% of
measured
F
(% of I1)
151,8
21,6
136,6
29,4
167,0
13,7
151,8
35,6
136,6
42,0
167,0
29,1
151,8
22,3
136,6
30,0
167,0
14,5
The analysis of Table 4 shows that the results of the SMP have significant variations
depending on the methodology used to quantify I1 (bolded values on the last column). Both
methodologies used are valid and correct, so further guidance is necessary on which to use.
As for the quantification of O1, it was already pointed out the considerable inaccuracy of the
results obtained with a single measure on the composition of the waste gases. In Table 4 the
consequences of that inaccuracy are proven to be very significant, since the value obtained
for F might be affected by an error of more than a 100%, as shown on the last 3 rows of this
table. No possible conclusion can be drawn from the results of this SMP considering the
compliance with the 20% fugitive emission limit value referred in the SED. Therefore no
further calculations were performed to improve the SMP.
CONCLUSIONS
The SMP is an ‘obligation’ for all the installations in the scope of the SED. It is definitely a
useful and powerful environmental management tool, but it is not simple to use. The
guidance given in Annex III of the SED is not clear on the methodologies to be used on the
different quantifications necessary to perform a SMP. The results obtained in this work show
that different conclusions regarding the compliance with this legislation can be easily
achieved due to the lack of precise information on the SMP methodologies.
Several factors of inaccuracy in the calculation of the fugitive emissions were identified.
According to the results of this work, the most important of those is the measurement of the
composition of the waste gases and the extrapolation of that result for the time period of the
SMP.
Since the compliance with the requirements of this legislation must be achieved no latter than
31st October 2007, the main conclusion of our work is that more technical information should
urgently be provided to industrial operators regarding the methodology to perform a SMP.
REFERENCES
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