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Combustion of rapeseed oil and diesel oil mixtures for use in the production of heat energy
Fuel Processing Technology 87 (2006) 97 – 102 www.elsevier.com/locate/fuproc
Combustion of rapeseed oil and diesel oil mixtures for use in the production of heat energy ´ vila b, E.J. Lo´pez Romero b J. San Jose´ Alonso a,*, J.A. Lo´pez Sastre b, C. Romero-A a
b
Departamento Ingenierı´a Energe´tica y Fluidomeca´nica, E.T.S. de Ingenieros Industriales, Universidad de Valladolid, Paseo del Cauce s/n, 47011 Valladolid, Spain Departamento Quı´mica Orga´nica, E.T.S. de Ingenieros Industriales, Universidad de Valladolid, Paseo del Cauce s/n, 47011 Valladolid, Spain Received 18 May 2005; received in revised form 20 June 2005; accepted 1 July 2005
Abstract The energy policy of both Europe and Spain considers biomass to be the renewable energy source with the greatest possibilities of growth, from both the point of view of forestry and energy crops. One alternative to energy crops is the use of rapeseed oil as the fuel in thermic processes. This paper studies the use of rapeseed oil and diesel oil mixtures as the fuel for producing heat in a conventional diesel installation. The paper is set out as follows: a) Characterization of the properties of rapeseed oil as fuel and of diesel oil, as well as the mixtures of both. b) Selection of the mixtures according to their physical – chemical properties and to how they adapt to a conventional installation consisting of a mechanical pulverization burner. c) Experimentation with the selected mixtures in a conventional combustion installation, allowing the main combustion parameters to be measured. d) A study is carried out of the yield of the combustion. The conclusions show that the use of rapeseed and diesel mixtures for producing heat energy in conventional equipment is feasible. D 2005 Elsevier B.V. All rights reserved. Keywords: Characterization; Mixtures; Rapeseed; Diesel; Heat energy
1. Introduction Vegetable oils have already been used in the generation of energy [1], although most work has been related with their use as engine fuel, mainly following transesterification [2 –7]. The possibility of using mixtures of sunflower oil and diesel in the production of heat energy has been dealt with in various previous works [9 –15]. This paper examines mixtures of rapeseed oil and diesel. Rape is an oily plant from Europe and Asia. It was originally a weed that was genetically improved, thus transforming it for the use of its oil, first in industry, and then for animal and human consumption. The cultivation of rape began in Asia, where it was used as fuel for lamps. Its cultivation in Europe began in Holland in the 13th century. It then passed to Belgium and France and later, in the 16th century, to Germany. The great development of rape is closely linked to the shipbuilding industry, as its oil shows a * Corresponding author. Tel.: +34 983423685; fax: +34 983423363. E-mail address: [email protected] (J. San Jose´ Alonso). 0378-3820/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.fuproc.2005.07.004
greater adherence to metallic surfaces than other vegetable oils. This ensured its expansion to countries such as Canada, currently the world’s largest rape producer. Canada is also working on improvements to rape, as shown by the nutritional Table 1 Chemical composition of rapeseed oil, data provided by KOIPE S.A. factory Andu´jar (Jae´n) Fatty acid profile and characteristics
Myristic Palmitic Palmitoleic Estearic Oleic Linoleic Linolenic Iodine index Title Saponification index Saturated/unsaturated
C < 14 C 14:0 C 16:0 C 16:1 C 18:0 C 18:1 C 18:2 C 18:3 C 20
Refined rape (%) – 0.06 4.72 0.24 3.01 54.62 27.2 7.14 3.01 98 13 172 0.1
Raw rape (%) – 0.05 4.32 0.23 2.77 60.27 19.58 9.19 3.59
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J. San Jose´ Alonso et al. / Fuel Processing Technology 87 (2006) 97 – 102
Table 2 Physical properties of rapeseed oil, analysis carried out by the Regional Fuel Laboratory (LARECOM), Junta of Castilla and Leo´n Density at 15 -C (kg/m3) Density at 35 -C (kg/m3) A 40 -C est A 100 -C est %S in mass %C in mass %H in mass %O in mass HHV (MJ/kg) LHV (MJ/kg)
Rape
Diesel
921 909 35.1 8.1 0.03 79.6 11.4 8.97 39.2 36.8
848 635 2.7 1.2 0.07 86.6 12.3 1.03 44.9 42.3
properties of the ‘‘cake’’ sub-product for human consumption after the Second World War. It was not until after the First World War that researchers (especially French, German, Italian and English) considered the need to find an alternative fuel to petroleum which could allow countries to become independent from imports in the question of energy [16]. The researchers followed two different lines of investigation: a) Obtaining fuels from carbon. The work of Bergius and Franz Fischer stand out in this field. b) The use of alternative fuels, including: – Alcohols. – Methane. – Benzol. – Vegetable oils. In particular, research into vegetable oils followed two paths: to obtain petrol and diesel fuel from vegetable oil, and the direct use of vegetable oils as the fuel in diesel engines. The use of rape in conventional diesel engines caused problems with low proportion mixtures in a continuous regime. However, the use of heat energy from rapeseed in heating installations does not cause problems due to the simplicity of the liquid fuel burners. The use of unrefined vegetable oil mixtures with diesel fuel to produce heat, quite apart from the environmental, social, strategic and economic advantages, also have the following further advantages. i) The oil is obtained in conventional plants which supposes that: a) these plants increase their production, thus increasing their profitability and b), as several markets exist, the price of the rapeseed oil can be controlled. ii) Conventional diesel installations are used, which supposes Table 3 Chemical composition of type C diesel
Table 4 Physical characteristics of type C diesel, analysis carried out by the Regional Fuel Laboratory (LARECOM), Junta of Castilla and Leo´n Density at 15 -C Sulphur content Cetane index Distillation: 50% Distillation: 65% Distillation: 80% Distillation: 85% Distillation: 90%
collected collected collected collected collected
at at at at at
Water and sediments Water Ash content Copper corrosion (3 h at 50 -C) Highest calorific power
0.853 kg/l 0.11% by weight 47 271 -C 297 -C 326 -C 338 -C 369 -C 2.81 mm/s 0.04% by volume 168% by weight 0.0001% by weight 1st 45.0 MJ/kg minimum
that: a) there is no increase in investment, b) the percentage of substitution can vary up to a maximum of 30% of sunflower – seed oil (thus allowing the installation to function continuously and therefore eliminating the temporal nature of biomass) and c) the oils do not present storage problems. 2. Rapeseed oil Rapeseed oil today is a high quality product in the list of vegetable oils. Oils in general are mainly made up of fatty acids which may be either saturated or unsaturated. The former are bad for the health while the latter are beneficial and their presence increases the quality of the product. Rape has very low levels of saturated acids. There are at least four criteria to be taken into account when evaluating oils: i) the intrinsic chemical quality (degree of humidity, impurities, impossible to saponify, peroxides, inevitable fraction, fatty acid polymers, strange or toxic substances, etc.); ii) energy potential and composition (energy content, percentage of triglycerides, composition and richness in essential fatty acids, etc); iii) use; and iv) price offered. The chemical composition of rapeseed oil is shown in Table 1 by mass percentage. The physical properties of the oils are shown in Table 2. Looking more closely at Table 2, the greater differences between the oils and diesel can be appreciated, thus indicating the problematic points to be found when using oils (or mixtures with oils) where only diesel was previously used. The most critical variations are the viscosities at both 40 -C and 100 -C. This probably means that a high percentage of oil could not be used, as the high viscosities could cause problems in the pump; Table 5 Guidelines used to characterize fuels by LARECOM
Composition of fuel
Type C diesel (%)
C H S N Water Ashes
86 11.1 0.8 1 1 0.1
Properties
Test guidelines
Upper and lower calorific power Density at 15 -C and 35 -C Cinematic viscosity at 40 -C and 100 -C Point of cloudiness Sulphur percentage Carbon percentage Hydrogen percentage
UNE 51116 UNE 51116 UNE 51106 UNE 51129 ASTM D-4239 LECO CHN-600 LECO CHN-600
J. San Jose´ Alonso et al. / Fuel Processing Technology 87 (2006) 97 – 102
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Table 6 Composition of the mixtures obtained through theoretical and laboratory analysis
Table 8 Characteristics of generator group used in combustion tests
Name
Boiler type Calorific power Water capacity Approximate weight Maximum working temperature
C-0 C-10 C-20 C-30 C-40 C-50 C-60 C-70 C-80 C-90 C-100
Laboratory analysis
Theoretical analysis
%C
%H
%O
%S
%C
%H
%O
%S
86.60 84.70 84.80 84.40 83.00 82.40 80.90 81.30 80.30 80.50 79.60
12.30 12.50 12.50 12.30 12.00 12.10 12.00 11.70 11.70 11.60 11.40
0.99 2.68 2.58 3.2 4.92 5.46 7.06 6.97 7.98 7.88 8.97
0.11 0.12 0.11 0.10 0.08 0.04 0.04 0.03 0.02 0.02 0.03
86.60 85.83 85.08 84.31 83.55 82.79 82.03 81.27 80.51 79.74 79.60
12.30 12.20 12.10 12.01 11.91 11.81 11.71 11.61 11.52 11.42 11.40
0.99 1.87 2.73 3.60 4.46 5.33 6.20 7.07 7.93 8.80 8.97
0.110 0.100 0.090 0.080 0.075 0.066 0.057 0.049 0.040 0.031 0.030
unless, that is, the fuel were heated to a temperature at which the viscosity was within the recommended limits. A higher density than that of pure diesel can also be seen, supposing a constant volumetric flow of fuel. This would partly compensate for the lower calorific power of the fuel. That is, when burnt, the mixture gives off less calorific energy; however, as a greater quantity is burnt, the said effect is compensated for [17,18]. 3. Diesel The diesel is a liquid of low viscosity, originally colorless or slightly yellowish and which is colored in Spain for tax reasons. Its main characteristic is that it belongs to a category of liquid fuels derived from petroleum denominated pure distillates, made up of a range of hydrocarbons whose number of carbon atoms is between 14 and 20. Their boiling points range from 220 to 390 -C. They are classified in three types (A, B, and C), depending on their quality and the use to which they are put. The type C diesel (the one to which this study refers) is of a slightly lower quality than the other two and therefore has a lower price. It is an almost homogeneous product that maintains its composition and characteristics throughout storage and use.
Boiler model AR/25GT by ROCA Smelting 26.7 kW 26 l 210 kg 110 -C
Burner model KADET-TRONIC by ROCA Nozzle GPH Angle Pump pressure (bar) 0.6 6012
Flow (l/h) 2.3
Air regulation 3
The chemical composition of this diesel is shown in Table 3, by mass percentage: The physical characteristics of type C diesel are shown in Table 4. 4. Rapeseed oil and type C diesel mixtures The mixtures used as fuel are made by volumetric percentage. Thus, and to aid understanding, from now on a FC-10_ mixture will mean a mixture with 10% rapeseed oil and 90% type C diesel. Thus, C-0 means pure diesel and C-100 means pure refined rapeseed oil. The properties of the mixtures can be determined: a) by weighting this property with respect to the weight percentage of each of the components of the mixture and b) by the elemental composition of the mixtures which can be determined empirically. Nevertheless, to validate the results, the Regional Fuel Laboratory (LARECOM) of the Junta of Castilla and Leo´n have carried out analyses of the mixtures used, following the guidelines indicated below in Table 5. The elemental composition by weight percentage obtained in the laboratory and the theoretical compositions of the mixtures used are shown in Table 6. The physical properties of the mixtures, estimated and determined in the laboratory, are shown in Table 7.
Table 7 Physical properties of the type C diesel and rapeseed oil mixtures obtained through laboratory analysis (LARECOM) and theoretical analysis Name
C-0 C-10 C-20 C-30 C-40 C-50 C-60 C-70 C-80 C-90 C-100
Laboratory analysis
Theoretical analysis
LHV (MJ/kg)
HHV (MJ/kg)
Density 15 -C (kg/m3)
Density 35 -C (kg/m3)
Viscosity 20 -C (cSt)
Viscosity 40 -C (cSt)
Viscosity 50 -C (cSt)
LHV (MJ/kg)
HHV (MJ/kg)
Density 15 -C (kg/m3)
Density 35 -C (kg/m3)
42.3 41.9 41.4 40.8 40.5 39.5 38.9 38.5 38.0 37.5 36.8
44.9 44.5 44.0 43.5 43.0 42.1 41.4 41.0 40.5 39.9 39.2
848 857 864 871 879 886 893 900 907 914 921
835 842 849 856 864 873 880 887 894 902 909
3.4 5.2 7.0 9.0 12 15.6 19.8 26.4 37.1 43.3 53.2
2.7 3.6 4.7 5.9 7.72 10.2 13 16.8 21.1 27.5 35.1
2.3 2.97 3.8 4.69 6.07 8.07 10.29 13.03 14.12 21.18 27.77
42.3 41.7 41.1 40.5 39.9 39.3 38.7 39.2 37.5 36.9 36.8
44.9 44.3 43.6 43.0 42.4 41.8 41.2 40.6 40.0 39.4 39.2
848 855 864 872 880 888 896 904 912 920 921
835 843 851 859 867 875 883 891 899 907 909
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J. San Jose´ Alonso et al. / Fuel Processing Technology 87 (2006) 97 – 102
4 V5
2
3 X1 X3
6
5
1
D E
7
8
V1
V2
INSTALLATION OF THERMAL GROUP AND DISSIPATION OF HEAT 1 - Boiler of I hurt fused AR/GT 2 - Security Valve 3 - Funnel security valve 4 - Automatic Purge 5 - Originator key 6 - Originator 7 - Originator Purge 8 - Connect 9 - Closed expansion deposit 10 - Valve filled installation 11 - Drainage valve 12 - Retention valve 13 - Sphere valve 14 - Atmosphere thermostat 15 - Circulator 16 - Burner V1 - Baseboard V2 - Emptied installation V5 - Minimum slope 2‰ XO - Filled installation D - Pipe oil aspiration E - Pipe oil return
Fig. 1. Diagram of the start of the experimentation installation.
From the data in Table 7, it can be seen that the viscosity increases along with the increase in the proportion of rapeseed oil. Given that conventional type C diesel installations use mechanical pressurized pulverization burners, this technology is limited to a viscosity of 10 cSt at 20 -C. As can be seen, valid mixtures are those with percentages below 30% of rapeseed oil, that is C-0, C-10, C-20 and C-30 mixtures. This study therefore centers on these and uses them to carry out fumes analyses and performance calculations, [19]. 5. Installation and measuring apparatus The installation can be divided into three clearly different parts: – Generator group. – Heat dissipation installation. – Measuring apparatus.
The generator group is a thermal group AR/Gt of the heating segment by the firm ROCA, made up of the boiler body, insulation, circulator, burner and control panel. The main characteristics are shown in Table 8 [20]. The burner is a mechanical pulverization type burner, working under pressure with a non-return nozzle. This limits its use to fuels with a viscosity lower than 10 cSt at 20 -C. The installation of the heat dissipator is bitubular, with direct return and radiators. A diagram of the installation is shown in Fig. 1. The measuring apparatus used were: – Fumes analyser. – Temperature probe. – Pressure probes. The characteristics of the different pieces of equipment are shown in Table 9: 6. Test plan
Table 9 Measuring equipment used in tests, with measuring range Fumes analyzer (a set) Make and model Type k thermostat Electrochemical O2 probe CO probe (with H2 compensation) NO electrolytic cell probe Temperature probes (three probes) Thermopar type Measurement interval Pressure probes (two probes) Manometer type Impulse pressure interval Aspiration pressure interval
TESTO model 342-3 Range 40 to 1200 T 0.1 -C Range 0% to 21% Range 0 to 4000 ppm Range 0 to 3000 ppm
The scope of these experiments is the use of an existing diesel boiler for the combustion of mixtures of diesel and rapeseed oil to determine their combustion characteristics, but not to optimize the boiler process. Table 10 Test plan to be carried out according to control parameters Type of fuel
K 40 to 1000 T 0.5 -C
Spiral 1 to 40 bar precision 1% 0.2 to 1 bar precision 1%
Fuel pressure (bar)
C-0 10 C-10 12 C-20 14 C-30 The total number of tests is 4 3 3 = 32
Position of air entrance (%) 1.5 2.5 3.5
J. San Jose´ Alonso et al. / Fuel Processing Technology 87 (2006) 97 – 102
101
Concentration in smoke
(Pressure of injection 12 bar, position grill of air 1,25) 1,8 1,6 1,4 1,2 1 0,8 0,6 0,4 0,2 0 C-0
C-10
C-20
C-30
Mixture type CO2 en m3/kg
CO en cm3/kg
NO en cm3/kg
Graph 1. Analysis of combustion.
The test plan was carried out with different percentages of rapeseed oil, different fuel injection pressures and different positions of the air inlet grating to the burner. The number of tests that were carried out is shown in Table 10. The data measured are as follows: – – – – – –
Temperature of fumes. O2 content in fumes. CO2 content in fumes. CO content in fumes. NO content in fumes. Excess of air in combustion.
8. Conclusions
During each test, an average of six sets of measurements was taken. The data obtained were treated statistically, allowing data to be obtained concerning:
In addition to the decrease of sulphur oxide and CO2 emissions, the most important conclusions reached by this study are detailed below: i) No modifications to existing installations are needed in order to use the tested mixtures of rapeseed oil. ii) The efficiency of the combustion increases with these mixtures as a consequence of the decrease in losses due to fumes. As the percentage of rapeseed oil increases, the volume of fumes generated per kilogram of fuel falls. iii) Due to the increased efficiency of the combustion, the heat emitted per kg for the different mixtures is higher than that emitted per kg of diesel, in spite of the fact that the percentage of rapeseed oil in them decreases. iv) From an economic point of view, the use of these mixtures would be profitable provided that adequate tax and agricultural policies for encouraging biomass fuels are carried through.
CO2 emissions. CO emissions. NO emissions. Instant performance of combustion. 85,5
85
Yield of combustion %
– – – –
7. Results The results in all the tests show the same tendency. Graphs 1 and 2 show the results obtained for tests carried out with a fuel pressure of 12 bar and an air grating opening of 1.25. The increase in CO shown in the graph decreases when the injection pressure is increased. This is justified by the increased viscosity of the fuel used, as the percentage of rapeseed oil is increased. This requires a greater injection pressure to maintain adequate pulverization.
84,5
84
References 83,5
83 C-0
C-10
C-20
Mixture type Graph 2. Yield of combustion.
C-30
[1] C.E. Goering, M.J. Daugherty, Energy accounting for eleven vegetable oil fuels, Transactions of the ASAE, American Society of Agricultural Engineers (1982) 1209 – 1215. [2] J.A. Lo´pez Sastre, L. Guijosa, J.M. Sanz, Los aceites vegetales como combustibles ecolo´gicos, Energı´a 21 (1995) 71 – 76. [3] R.W. Pryor, M.A. Hanna, J.L. Schinstock, L.L. Bashford, Soybean oil fuel in a small diesel engine, Transactions of the ASAE, American Society of Agricultural Engineers (1983) 333 – 337.
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[4] J. Zubik, S. Sorenson, C. Goering, Diesel engine combustion of sunflower oil fuels, Transactions of the ASAE, American Society of Agricultural Engineers (1984) 1252 – 1256. [5] A.W. Schwab, M.O. Bagby, B. Freedman, Preparation and properties of diesel fuels from vegetable oils, Fuel 66 (1987) 1342 – 1372. [6] S.M. Geyer, M.J. Jacobus, S.S. y Lestz, Comparison of diesel engine performance and emissions from neat and transesterified vegetable oils, Transactions of the ASAE, American Society of Agricultural Engineers (1984) 375 – 381. [7] P. Gateau, J. Guibet, G. Hillion, R. Stern, Utilisation des huiles ve´ge´tales et de leurs produits de transesterification comme carburants diesel, Revue de l’Institut Franc¸ais du Pe´trole 40 (1985) 509 – 528. ´ vila, Los aceites [9] J.A. Lo´pez Sastre, J. San Jose´ Alonso y, E.J. Romero-A vegetales como biocombustibles, in: M. Pineda, P. Cabello (Eds.), Energı´a de la Biomasa. Realidades y Perspectivas, Universidad de Co´rdoba, 1998, pp. 49 – 63. ´ vila, J.F. San Jose´ Alonso, M. Molina [10] J.A. Lo´pez Sastre, E.J. Romero-A Leyra, Generacio´n de calor para calefaccio´n utilizando biocombustible, Montajes e Instalaciones 49 – 54 (1999) 278. ´ vila Garcı´a, E.J. [11] J.A. Lo´pez Sastre, J. San Jose´ Alonso, C. Romero-A ´ vila, C. Rodrı´guez Alonso, A study of the decrease in Lo´pez Romero-A fossil CO2 emissions of energy generation, by using vegetable oils as combustible, Building and Environment 38 (2003) 129 – 133. ´ vila Garcı´a, E.J. [12] J. San Jose´ Alonso, J.A. Lo´pez Sastre, C. Romero-A ´ vila, C. Izquierdo Iglesias, Using mixtures of diesel and Lo´pez Romero-A
[13]
[14]
[15]
[16] [17] [18] [19]
[20]
sunflower oil as fuel for heating purposes in Castilla and Leo´n, Energy 30 (2004) 575 – 584. J.A. Lo´pez Sastre, E.J. Lo´pez Romero Avila, J.F. San Jose´ Alonso, C. Romero-Avila, Caracterizacio´n y combustio´n de mezclas de aceite de colza y gaso´leo C para su utilizacio´n en produccio´n de energı´a te´rmica, Montajes e Instalaciones 377 (2003) 43 – 49. J.A. Lo´pez Sastre, E.J. Lo´pez Romero Avila, J.F. San Jose´ Alonso, C. Romero-Avila, M. Alvarez-Gerra, Utilizacio´n de las mezclas de gaso´leo C y aceite de girasol como combustible con fines te´rmicos en Castilla y Leo´n, Revista Montajes e Instalaciones 353 (2001) 117 – 122. E.J. Lo´pez Romero-Avila, ‘‘Study of the combustion of sunflower oil and c-diesel mixtures’’, Proyecto Fin de Carrera, E.T.S. Ingenieros Industriales, Universidad of Valladolid (1998). INTA, The cultivation of rapeseed canola, Ministry of Agrarian Matters and Production Government of the county of Buenos Aires (1996). Fundacio´n Espan˜ola para el Desarrollo de la Nutricio´n, ‘‘Fatty and oils’’, WWW.etsia.upm.es/fedna/grasasyaceites, Madrid 1999. Ministry of Agriculture, Fisheries and Feeding, ‘‘Annual’’, (2002). J. Alonso Ruiz, Characterization and combustion of mixtures of rapeseed oil and diesel oil for their use in the production of thermal energy: I. Study environmental and economic, Proyecto Fin de Carrera, E.T.S. Ingenieros Industriales, Universidad of Valladolid (2000). ROCA, ‘‘Technical monograph, heating boilers’’, Company Roca Radiators, CORP. Division Heating, Barcelona (2001).
Combustion of rapeseed oil and diesel oil mixtures for use in the production of heat energy ´ vila b, E.J. Lo´pez Romero b J. San Jose´ Alonso a,*, J.A. Lo´pez Sastre b, C. Romero-A a
b
Departamento Ingenierı´a Energe´tica y Fluidomeca´nica, E.T.S. de Ingenieros Industriales, Universidad de Valladolid, Paseo del Cauce s/n, 47011 Valladolid, Spain Departamento Quı´mica Orga´nica, E.T.S. de Ingenieros Industriales, Universidad de Valladolid, Paseo del Cauce s/n, 47011 Valladolid, Spain Received 18 May 2005; received in revised form 20 June 2005; accepted 1 July 2005
Abstract The energy policy of both Europe and Spain considers biomass to be the renewable energy source with the greatest possibilities of growth, from both the point of view of forestry and energy crops. One alternative to energy crops is the use of rapeseed oil as the fuel in thermic processes. This paper studies the use of rapeseed oil and diesel oil mixtures as the fuel for producing heat in a conventional diesel installation. The paper is set out as follows: a) Characterization of the properties of rapeseed oil as fuel and of diesel oil, as well as the mixtures of both. b) Selection of the mixtures according to their physical – chemical properties and to how they adapt to a conventional installation consisting of a mechanical pulverization burner. c) Experimentation with the selected mixtures in a conventional combustion installation, allowing the main combustion parameters to be measured. d) A study is carried out of the yield of the combustion. The conclusions show that the use of rapeseed and diesel mixtures for producing heat energy in conventional equipment is feasible. D 2005 Elsevier B.V. All rights reserved. Keywords: Characterization; Mixtures; Rapeseed; Diesel; Heat energy
1. Introduction Vegetable oils have already been used in the generation of energy [1], although most work has been related with their use as engine fuel, mainly following transesterification [2 –7]. The possibility of using mixtures of sunflower oil and diesel in the production of heat energy has been dealt with in various previous works [9 –15]. This paper examines mixtures of rapeseed oil and diesel. Rape is an oily plant from Europe and Asia. It was originally a weed that was genetically improved, thus transforming it for the use of its oil, first in industry, and then for animal and human consumption. The cultivation of rape began in Asia, where it was used as fuel for lamps. Its cultivation in Europe began in Holland in the 13th century. It then passed to Belgium and France and later, in the 16th century, to Germany. The great development of rape is closely linked to the shipbuilding industry, as its oil shows a * Corresponding author. Tel.: +34 983423685; fax: +34 983423363. E-mail address: [email protected] (J. San Jose´ Alonso). 0378-3820/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.fuproc.2005.07.004
greater adherence to metallic surfaces than other vegetable oils. This ensured its expansion to countries such as Canada, currently the world’s largest rape producer. Canada is also working on improvements to rape, as shown by the nutritional Table 1 Chemical composition of rapeseed oil, data provided by KOIPE S.A. factory Andu´jar (Jae´n) Fatty acid profile and characteristics
Myristic Palmitic Palmitoleic Estearic Oleic Linoleic Linolenic Iodine index Title Saponification index Saturated/unsaturated
C < 14 C 14:0 C 16:0 C 16:1 C 18:0 C 18:1 C 18:2 C 18:3 C 20
Refined rape (%) – 0.06 4.72 0.24 3.01 54.62 27.2 7.14 3.01 98 13 172 0.1
Raw rape (%) – 0.05 4.32 0.23 2.77 60.27 19.58 9.19 3.59
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J. San Jose´ Alonso et al. / Fuel Processing Technology 87 (2006) 97 – 102
Table 2 Physical properties of rapeseed oil, analysis carried out by the Regional Fuel Laboratory (LARECOM), Junta of Castilla and Leo´n Density at 15 -C (kg/m3) Density at 35 -C (kg/m3) A 40 -C est A 100 -C est %S in mass %C in mass %H in mass %O in mass HHV (MJ/kg) LHV (MJ/kg)
Rape
Diesel
921 909 35.1 8.1 0.03 79.6 11.4 8.97 39.2 36.8
848 635 2.7 1.2 0.07 86.6 12.3 1.03 44.9 42.3
properties of the ‘‘cake’’ sub-product for human consumption after the Second World War. It was not until after the First World War that researchers (especially French, German, Italian and English) considered the need to find an alternative fuel to petroleum which could allow countries to become independent from imports in the question of energy [16]. The researchers followed two different lines of investigation: a) Obtaining fuels from carbon. The work of Bergius and Franz Fischer stand out in this field. b) The use of alternative fuels, including: – Alcohols. – Methane. – Benzol. – Vegetable oils. In particular, research into vegetable oils followed two paths: to obtain petrol and diesel fuel from vegetable oil, and the direct use of vegetable oils as the fuel in diesel engines. The use of rape in conventional diesel engines caused problems with low proportion mixtures in a continuous regime. However, the use of heat energy from rapeseed in heating installations does not cause problems due to the simplicity of the liquid fuel burners. The use of unrefined vegetable oil mixtures with diesel fuel to produce heat, quite apart from the environmental, social, strategic and economic advantages, also have the following further advantages. i) The oil is obtained in conventional plants which supposes that: a) these plants increase their production, thus increasing their profitability and b), as several markets exist, the price of the rapeseed oil can be controlled. ii) Conventional diesel installations are used, which supposes Table 3 Chemical composition of type C diesel
Table 4 Physical characteristics of type C diesel, analysis carried out by the Regional Fuel Laboratory (LARECOM), Junta of Castilla and Leo´n Density at 15 -C Sulphur content Cetane index Distillation: 50% Distillation: 65% Distillation: 80% Distillation: 85% Distillation: 90%
collected collected collected collected collected
at at at at at
Water and sediments Water Ash content Copper corrosion (3 h at 50 -C) Highest calorific power
0.853 kg/l 0.11% by weight 47 271 -C 297 -C 326 -C 338 -C 369 -C 2.81 mm/s 0.04% by volume 168% by weight 0.0001% by weight 1st 45.0 MJ/kg minimum
that: a) there is no increase in investment, b) the percentage of substitution can vary up to a maximum of 30% of sunflower – seed oil (thus allowing the installation to function continuously and therefore eliminating the temporal nature of biomass) and c) the oils do not present storage problems. 2. Rapeseed oil Rapeseed oil today is a high quality product in the list of vegetable oils. Oils in general are mainly made up of fatty acids which may be either saturated or unsaturated. The former are bad for the health while the latter are beneficial and their presence increases the quality of the product. Rape has very low levels of saturated acids. There are at least four criteria to be taken into account when evaluating oils: i) the intrinsic chemical quality (degree of humidity, impurities, impossible to saponify, peroxides, inevitable fraction, fatty acid polymers, strange or toxic substances, etc.); ii) energy potential and composition (energy content, percentage of triglycerides, composition and richness in essential fatty acids, etc); iii) use; and iv) price offered. The chemical composition of rapeseed oil is shown in Table 1 by mass percentage. The physical properties of the oils are shown in Table 2. Looking more closely at Table 2, the greater differences between the oils and diesel can be appreciated, thus indicating the problematic points to be found when using oils (or mixtures with oils) where only diesel was previously used. The most critical variations are the viscosities at both 40 -C and 100 -C. This probably means that a high percentage of oil could not be used, as the high viscosities could cause problems in the pump; Table 5 Guidelines used to characterize fuels by LARECOM
Composition of fuel
Type C diesel (%)
C H S N Water Ashes
86 11.1 0.8 1 1 0.1
Properties
Test guidelines
Upper and lower calorific power Density at 15 -C and 35 -C Cinematic viscosity at 40 -C and 100 -C Point of cloudiness Sulphur percentage Carbon percentage Hydrogen percentage
UNE 51116 UNE 51116 UNE 51106 UNE 51129 ASTM D-4239 LECO CHN-600 LECO CHN-600
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Table 6 Composition of the mixtures obtained through theoretical and laboratory analysis
Table 8 Characteristics of generator group used in combustion tests
Name
Boiler type Calorific power Water capacity Approximate weight Maximum working temperature
C-0 C-10 C-20 C-30 C-40 C-50 C-60 C-70 C-80 C-90 C-100
Laboratory analysis
Theoretical analysis
%C
%H
%O
%S
%C
%H
%O
%S
86.60 84.70 84.80 84.40 83.00 82.40 80.90 81.30 80.30 80.50 79.60
12.30 12.50 12.50 12.30 12.00 12.10 12.00 11.70 11.70 11.60 11.40
0.99 2.68 2.58 3.2 4.92 5.46 7.06 6.97 7.98 7.88 8.97
0.11 0.12 0.11 0.10 0.08 0.04 0.04 0.03 0.02 0.02 0.03
86.60 85.83 85.08 84.31 83.55 82.79 82.03 81.27 80.51 79.74 79.60
12.30 12.20 12.10 12.01 11.91 11.81 11.71 11.61 11.52 11.42 11.40
0.99 1.87 2.73 3.60 4.46 5.33 6.20 7.07 7.93 8.80 8.97
0.110 0.100 0.090 0.080 0.075 0.066 0.057 0.049 0.040 0.031 0.030
unless, that is, the fuel were heated to a temperature at which the viscosity was within the recommended limits. A higher density than that of pure diesel can also be seen, supposing a constant volumetric flow of fuel. This would partly compensate for the lower calorific power of the fuel. That is, when burnt, the mixture gives off less calorific energy; however, as a greater quantity is burnt, the said effect is compensated for [17,18]. 3. Diesel The diesel is a liquid of low viscosity, originally colorless or slightly yellowish and which is colored in Spain for tax reasons. Its main characteristic is that it belongs to a category of liquid fuels derived from petroleum denominated pure distillates, made up of a range of hydrocarbons whose number of carbon atoms is between 14 and 20. Their boiling points range from 220 to 390 -C. They are classified in three types (A, B, and C), depending on their quality and the use to which they are put. The type C diesel (the one to which this study refers) is of a slightly lower quality than the other two and therefore has a lower price. It is an almost homogeneous product that maintains its composition and characteristics throughout storage and use.
Boiler model AR/25GT by ROCA Smelting 26.7 kW 26 l 210 kg 110 -C
Burner model KADET-TRONIC by ROCA Nozzle GPH Angle Pump pressure (bar) 0.6 6012
Flow (l/h) 2.3
Air regulation 3
The chemical composition of this diesel is shown in Table 3, by mass percentage: The physical characteristics of type C diesel are shown in Table 4. 4. Rapeseed oil and type C diesel mixtures The mixtures used as fuel are made by volumetric percentage. Thus, and to aid understanding, from now on a FC-10_ mixture will mean a mixture with 10% rapeseed oil and 90% type C diesel. Thus, C-0 means pure diesel and C-100 means pure refined rapeseed oil. The properties of the mixtures can be determined: a) by weighting this property with respect to the weight percentage of each of the components of the mixture and b) by the elemental composition of the mixtures which can be determined empirically. Nevertheless, to validate the results, the Regional Fuel Laboratory (LARECOM) of the Junta of Castilla and Leo´n have carried out analyses of the mixtures used, following the guidelines indicated below in Table 5. The elemental composition by weight percentage obtained in the laboratory and the theoretical compositions of the mixtures used are shown in Table 6. The physical properties of the mixtures, estimated and determined in the laboratory, are shown in Table 7.
Table 7 Physical properties of the type C diesel and rapeseed oil mixtures obtained through laboratory analysis (LARECOM) and theoretical analysis Name
C-0 C-10 C-20 C-30 C-40 C-50 C-60 C-70 C-80 C-90 C-100
Laboratory analysis
Theoretical analysis
LHV (MJ/kg)
HHV (MJ/kg)
Density 15 -C (kg/m3)
Density 35 -C (kg/m3)
Viscosity 20 -C (cSt)
Viscosity 40 -C (cSt)
Viscosity 50 -C (cSt)
LHV (MJ/kg)
HHV (MJ/kg)
Density 15 -C (kg/m3)
Density 35 -C (kg/m3)
42.3 41.9 41.4 40.8 40.5 39.5 38.9 38.5 38.0 37.5 36.8
44.9 44.5 44.0 43.5 43.0 42.1 41.4 41.0 40.5 39.9 39.2
848 857 864 871 879 886 893 900 907 914 921
835 842 849 856 864 873 880 887 894 902 909
3.4 5.2 7.0 9.0 12 15.6 19.8 26.4 37.1 43.3 53.2
2.7 3.6 4.7 5.9 7.72 10.2 13 16.8 21.1 27.5 35.1
2.3 2.97 3.8 4.69 6.07 8.07 10.29 13.03 14.12 21.18 27.77
42.3 41.7 41.1 40.5 39.9 39.3 38.7 39.2 37.5 36.9 36.8
44.9 44.3 43.6 43.0 42.4 41.8 41.2 40.6 40.0 39.4 39.2
848 855 864 872 880 888 896 904 912 920 921
835 843 851 859 867 875 883 891 899 907 909
100
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4 V5
2
3 X1 X3
6
5
1
D E
7
8
V1
V2
INSTALLATION OF THERMAL GROUP AND DISSIPATION OF HEAT 1 - Boiler of I hurt fused AR/GT 2 - Security Valve 3 - Funnel security valve 4 - Automatic Purge 5 - Originator key 6 - Originator 7 - Originator Purge 8 - Connect 9 - Closed expansion deposit 10 - Valve filled installation 11 - Drainage valve 12 - Retention valve 13 - Sphere valve 14 - Atmosphere thermostat 15 - Circulator 16 - Burner V1 - Baseboard V2 - Emptied installation V5 - Minimum slope 2‰ XO - Filled installation D - Pipe oil aspiration E - Pipe oil return
Fig. 1. Diagram of the start of the experimentation installation.
From the data in Table 7, it can be seen that the viscosity increases along with the increase in the proportion of rapeseed oil. Given that conventional type C diesel installations use mechanical pressurized pulverization burners, this technology is limited to a viscosity of 10 cSt at 20 -C. As can be seen, valid mixtures are those with percentages below 30% of rapeseed oil, that is C-0, C-10, C-20 and C-30 mixtures. This study therefore centers on these and uses them to carry out fumes analyses and performance calculations, [19]. 5. Installation and measuring apparatus The installation can be divided into three clearly different parts: – Generator group. – Heat dissipation installation. – Measuring apparatus.
The generator group is a thermal group AR/Gt of the heating segment by the firm ROCA, made up of the boiler body, insulation, circulator, burner and control panel. The main characteristics are shown in Table 8 [20]. The burner is a mechanical pulverization type burner, working under pressure with a non-return nozzle. This limits its use to fuels with a viscosity lower than 10 cSt at 20 -C. The installation of the heat dissipator is bitubular, with direct return and radiators. A diagram of the installation is shown in Fig. 1. The measuring apparatus used were: – Fumes analyser. – Temperature probe. – Pressure probes. The characteristics of the different pieces of equipment are shown in Table 9: 6. Test plan
Table 9 Measuring equipment used in tests, with measuring range Fumes analyzer (a set) Make and model Type k thermostat Electrochemical O2 probe CO probe (with H2 compensation) NO electrolytic cell probe Temperature probes (three probes) Thermopar type Measurement interval Pressure probes (two probes) Manometer type Impulse pressure interval Aspiration pressure interval
TESTO model 342-3 Range 40 to 1200 T 0.1 -C Range 0% to 21% Range 0 to 4000 ppm Range 0 to 3000 ppm
The scope of these experiments is the use of an existing diesel boiler for the combustion of mixtures of diesel and rapeseed oil to determine their combustion characteristics, but not to optimize the boiler process. Table 10 Test plan to be carried out according to control parameters Type of fuel
K 40 to 1000 T 0.5 -C
Spiral 1 to 40 bar precision 1% 0.2 to 1 bar precision 1%
Fuel pressure (bar)
C-0 10 C-10 12 C-20 14 C-30 The total number of tests is 4 3 3 = 32
Position of air entrance (%) 1.5 2.5 3.5
J. San Jose´ Alonso et al. / Fuel Processing Technology 87 (2006) 97 – 102
101
Concentration in smoke
(Pressure of injection 12 bar, position grill of air 1,25) 1,8 1,6 1,4 1,2 1 0,8 0,6 0,4 0,2 0 C-0
C-10
C-20
C-30
Mixture type CO2 en m3/kg
CO en cm3/kg
NO en cm3/kg
Graph 1. Analysis of combustion.
The test plan was carried out with different percentages of rapeseed oil, different fuel injection pressures and different positions of the air inlet grating to the burner. The number of tests that were carried out is shown in Table 10. The data measured are as follows: – – – – – –
Temperature of fumes. O2 content in fumes. CO2 content in fumes. CO content in fumes. NO content in fumes. Excess of air in combustion.
8. Conclusions
During each test, an average of six sets of measurements was taken. The data obtained were treated statistically, allowing data to be obtained concerning:
In addition to the decrease of sulphur oxide and CO2 emissions, the most important conclusions reached by this study are detailed below: i) No modifications to existing installations are needed in order to use the tested mixtures of rapeseed oil. ii) The efficiency of the combustion increases with these mixtures as a consequence of the decrease in losses due to fumes. As the percentage of rapeseed oil increases, the volume of fumes generated per kilogram of fuel falls. iii) Due to the increased efficiency of the combustion, the heat emitted per kg for the different mixtures is higher than that emitted per kg of diesel, in spite of the fact that the percentage of rapeseed oil in them decreases. iv) From an economic point of view, the use of these mixtures would be profitable provided that adequate tax and agricultural policies for encouraging biomass fuels are carried through.
CO2 emissions. CO emissions. NO emissions. Instant performance of combustion. 85,5
85
Yield of combustion %
– – – –
7. Results The results in all the tests show the same tendency. Graphs 1 and 2 show the results obtained for tests carried out with a fuel pressure of 12 bar and an air grating opening of 1.25. The increase in CO shown in the graph decreases when the injection pressure is increased. This is justified by the increased viscosity of the fuel used, as the percentage of rapeseed oil is increased. This requires a greater injection pressure to maintain adequate pulverization.
84,5
84
References 83,5
83 C-0
C-10
C-20
Mixture type Graph 2. Yield of combustion.
C-30
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