Biodiesel process study and processing Final report

Transcription

1 Biofuel Series Biodiesel process study and processing Final report Report BFUEL-FR-046 Laurent Sourya Doré Vientiane July 2013

2 Lao Institute for Renewable Energy LIRE REPORT BFUEL-FR-046 Biodiesel process study and processing-final report Laurent Sourya Doré Vientiane July 2013 July

3 DOCUMENT REVISION HISTORY Rev Date Description Author(s) Reviewer(s) # dd/mm/yyyy July

4 About us LIRE is a non-profit organization dedicated to the sustainable development of a self sufficient renewable energy sector in the Lao PDR. The institute offers agronomical, technological and socio-economic research services, and works to provide a free public resource of information and advice on the use of renewable energy technologies in Laos. LIRE strives to support the development of the country by exploring commercially viable means to establish renewable energy technologies in rural parts of the country, in areas without connection to the national grid and with little access to technical expertise. Lao Institute for Renewable Energy (LIRE) ø í É ¾ - êö ìº É¾ ²½ìñ ¾ êö Áê Lao-Thai Friendship Road Wattnak village, Vientiane, Lao PDR P.O. Box 8010 Tel: Fax: address: contact@lao-ire.org. 4

5 1 CONTENTS TABLE OF FIGURES... 7 TABLE OF TABLES... 8 TABLE OF PLATES... 9 LIST OF ABBREVIATIONS EXECUTIVE SUMMARY INTRODUCTION SUMMARY OF RESEARCH AND DEVELOPMENT PHASE OIL DEGUMMING Hydratable phospholipids Non hydratable phospholipids ACID VALUE DECREASING PROCEDURE FOR DECREASING BIODIESEL LOSS DURING THE WASHING RESULTS OF RESEARCH AND DEVELOPMENT PHASE Oil degumming and acid value decreasing Decreasing biodiesel loss during the washing Summary of research and development phase results IMPLEMENTATION OF BIODIESEL PRODUCTION BIODIESEL PROCESSING STEPS Centrifugation (CF) Citric acid degumming (CAD) Decreasing acid value (DAV) Trans-esterification of acyl glycerol (TAG) EQUIPMENTS AND PROCEDURES Equipments Biodiesel processing procedures PROCESS MONITORING AND TOTAL PRODUCTION EXPENSE Batch data recording sheet Batch report Total production expense

6 3 BIODIESEL PRODUCTION START UP ENCOUNTERED PROBLEMS Processing problems Equipment problems BIODIESEL YIELD AND QUALITY Biodiesel yield Biodiesel quality ASSESSMENT OF BIODIESEL PRODUCTION EXPENSE PRODUCTION EXPENSES OF PRESENT BIODIESEL PROCESSING Production expenses decreasing Processing capacity increasing PRODUCTION EXPENSES AFTER DECREASING RAW MATERIALS COST AND INCREASING PRODUCTION CAPACITY RECOMMENDATIONS FURTHER RESEARCH AND DEVELOPMENT WORKS PROCESSING EQUIPMENTS BIODIESEL PRODUCTION CONCLUSION BIBLIOGRAPHY APPENDIXES APPENDIX 1 : BIODIESEL PROCESS DIAGRAM, EQUIPMENTS CODE AND VALVE NUMBERING APPENDIX 2 : BIODIESEL PROCEDURES... 3 APPENDIX 3 : PRODUCT IN STORAGE IDENTIFICATION SHEET APPENDIX 4 : BATCH DATA RECORDING SHEET APPENDIX 5 : BATCH REPORT APPENDIX 6 : CALCULATION OF SODIUM HYDROXIDE QUANTITIES THAT ARE NEED FOR CITRIC ACID DEGUMMING, FREE FATTY ACID NEUTRALIZATION AND TRANS-ESTERIFICATION ACCORDING THE WEIGHT OF OIL AND THE ACID VALUE ANNEXES ANNEX 1 : SAFETY DATA SHEET OF METHANOL AND SODIUM HYDROXIDE ANNEX 2 : ANALYTICAL RESULTS OF BIODIESEL PRODUCED FROM WASTE COOKING OIL AT THE PILOT OF LAO STATE FUEL COMPANY ANNEX 3 : ANALYTICAL RESULTS OF BIODIESEL SAMPLES PRODUCED FROM JATROPHA OIL DURING LABORATORY PHASE ANNEX 4 : ANALYTICAL RESULTS OF WASTE COOKING OIL AND BIODIESEL SAMPLES PRODUCED IN LABORATORY FROM WASTE COOKING OIL

7 TABLE OF FIGURES Figure 1 : Molecular structure of phosphatidyl choline (PC) Figure 2 : Molecular structure of phosphatidyl inositol (PI) Figure 3 : Molecular structure of phosphatidyl ethanolamine (PE) Figure 4 : Molecular structure of phosphatidic acid (PA) Figure 5 : Neutralization of free fatty acid Figure 6 : Esterification of free fatty acid

8 TABLE OF TABLES Table 1 : Oil degumming and acid value decreasing procedure Table 2 : Results of gelatin treatment Table 3 : Biodiesel processing steps according the origin and acid value of oil Table 4 : Material balance presentation Table 5 : Electrical consumption presentation Table 6 : Net raw material expense presentation Table 7 : Obtained biodiesel yields during biodiesel production start up Table 8 : Water content measurement of processed biodiesel batches Table 9 : Laboratory testing with oil and chemicals from biodiesel pilot Table 10 : Biodiesel equipments depreciation Table 11 : Production expenses of present biodiesel processing Table 12 : Biodiesel production expenses after decreasing raw materials cost and increasing production

9 TABLE OF PLATES Plate 1 : Plate 2 : Oil before degumming 19 Oil after degumming.19 9

10 LIST OF ABBREVIATIONS AV CAD CF CVO DAV D DT FT I MIX n PA PC PE PF PI R1 S ST SV TAG WKO Acid value (milligram of KOH per gram of oil) Citric acid degumming procedure Centrifugation Crude vegetable oil Acid value decreasing procedure Annual depreciation Degumming tank Feeding tank Investment Methanol/sodium hydroxide mixer Number of years of use Phosphatidic acid Phosphatidyl choline Phosphatidyl ethanolamine Plate filter Phosphatidyl inositol Trans-esterification reactor Salvage value Settling vessel Storage tank Trans-esterification of acyl glycerol. Waste cooking oil 10

11 EXECUTIVE SUMMARY The purpose of the study was to assess the technical an economical feasibility of small-scale biodiesel production. Two parts made up this feasibility, research and development phase implemented in laboratory and production start up implemented at pilot level on the site of Lao State Fuel Company. Research and development phase has focused on procedures for removing some impurities contained in the oil before trans-esterification (biodiesel reaction). During this phase two kinds of oil were used, Jatropha oil and waste cooking oil coming from Vientiane restaurants. The procedures implemented during research and development phase were then use for producing biodiesel at pilot level during the second phase. Biodiesel was produced from waste cooking only and the yield and the quality were compared with the results obtained in laboratory. Yield of biodiesel are similar to laboratory results but quality was different because of un-suitable equipments, quality of chemical and waste cooking oil. Economical feasibility study of has shown un-sustainability and un-profitability of small-scale biodiesel production because of expensive waste cooking oil selling price. Recommendations were mad for improving the biodiesel quality and production profitability. 11

12 INTRODUCTION This report centers on four main chapters and gathers the results and the data obtained during research and development works implemented in laboratory and the start up of small-scale biodiesel production on the site of Lao State Fuel Company. The first chapter briefly describes molecular structures and chemical behavior of components to remove from oil before trans-esterification (biodiesel reaction) in order to avoid processing problem and to match quality standards. Three main components should be removed from oil; free fatty acid, metals and phospholipids. Procedures for removing these impurities are described; the results are analyzed in term of yield and efficiency and the limits of procedures are specified. The chapter one also describes the main reactions that occur during trans-esterification. Three main reactions occur during biodiesel processing; trans-esterification of acyl glycerol for producing fatty methyl esters (biodiesel), saponification of free fatty acid and hydrolyze of fatty methyl esters. Saponification of free fatty acid and hydrolyze of fatty methyl esters are side reaction that impact the yield and the quality of biodiesel. Saponification and hydrolyze reactions produce water and soap. The water affects the purity of biodiesel and soap decreases biodiesel yield during purification step. A procedure for removing soap before biodiesel purification step is described and the obtained results are analyzed. The chapter discusses the implementation of biodiesel production. The numbers of processing steps to implement during biodiesel production depend on the origin and the quality of oil. Each processing step is implemented according specific procedure. Procedures specify the quantities of inputs to implement, the kind of equipments to use and theirs schedule. The efficiency of biodiesel production is assessed by collecting data at the processing level. These data are collected by process operators and recorded in the batch data recording sheet. Process supervisor calculate mass balance and energy consumption of biodiesel production from batch data recording sheet. The batch report gathers the results of mass balance and energy consumption. Mass balance and energy consumption are used with other economical data for calculating production expenses and assess the efficiency of the production at the head factory level. The chapter three relates about the start up of biodiesel production from waste cooking oil. Biodiesel production start up has encountered equipments and processing problems. Some equipments were replaced and procedures were adapted in order to run the process. Biodiesel yields of pilot were similar to laboratory results but biodiesel purity did not reach quality standards. The causes of purity decreasing were identified and came mainly from un-suitable equipments, chemical and oil quality. The biodiesel production expenses are assessed in the chapter four and show that current waste cooking oil price makes un-sustainable and un-profitable biodiesel production from this raw material. The causes of high raw material price are highlighted and a simulation shows the profitability and the sustainability of biodiesel processing from waste cooking oil in Lao PDR if Government issues regulations for controlling waste cooking oil price. 12

13 The results and the data obtained from research and development phase and biodiesel production start up brought us to make some recommendations in the chapter five. These recommendations deal with further research works to implement, biodiesel equipments and biodiesel production. 13

14 1 SUMMARY OF RESEARCH AND DEVELOPMENT PHASE At the beginning of the research and development phase, laboratory works have focused on biodiesel processing from crude Jatropha oil. Jatropha seeds were provided by Lao State Fuel Company and pressed at the Institute for Renewable Energies located at Donenoun village. After cold pressing the obtained oil was darkly colored and during the oil storage a quiet considerable amount of deposit occurred in the bottom of oil container. The color of oil and the occurrence of deposit during the storage are indicative of the presence of gums and solid particles in the oil. The gums contained in crude vegetable oil should be removed quickly after pressing in order to avoid oil deterioration during the storage before biodiesel processing. The gums are also combined with metallic salt like calcium, magnesium and phosphorus. The amount of these compounds in the crude vegetable intended for biodiesel production should be under some recommended values in order to match biodiesel quality standards. The crude Jatropha oil obtained after seed pressing also contains quiet high amount of free fatty acid. If transesterification is implemented with oil containing quiet high amount of free fatty acid these compounds can react with the catalyst of trans-esterification and decrease its efficiency (Mathiyazaghan and Ganapathi, 2011). By reacting with catalyst free fatty acids also produce soap and water. The occurrence of water during trans-esterification decreases the yield of biodiesel (Canakci and Van Gerpen, 2001). Biodiesel containing quiet high amount of soap is also difficult to purify because during the washing of biodiesel with water emulsion occur every time. Emulsion increases the solubility of biodiesel with water resulting in biodiesel loss. Emulsion of biodiesel with water also need lengthy duration of theirs separation. The high amount of gums and free fatty acid contained in the oil produced from Jatropha seed supplied by Lao State Fuel Company make it un-suitable for direct trans-esterification after oil pressing. In order to make the Jatropha oil suitable for trans-esterification some treatments should be implementing for decreasing the amount of gums and free fatty acid contained in the oil. During the research and development phase the laboratory works have focused on procedures for decreasing the amount of gums (oil degumming) and free fatty acid (acid value decreasing) contained in crude Jatropha oil and on procedure for decreasing the loss of biodiesel during the washing. Works have also been implemented on waste cooking oil because this later is more affordable and cheaper than Jatropha oil. 1.1 OIL DEGUMMING Vegetable oil obtained from mechanical expelling or solvent extraction contains a number of impurities. Some of these impurities like seed fragment or meal fines are not soluble in the oil and can be remove by centrifugation or filtration. Others including free fatty acid, hydrocarbons, ketones, tocopherols, glycolipids, phytosterols, phospholipids, proteins, pigments, metal and resins are soluble or form stable colloidal suspensions in the oil. Most of these have unfavorable effects on the flavor, odor, appearance, shelf life of the oil, and therefore have to be removed from the crude oil. Among these impurities phospholipids are gums that pose many problems during the storage and processing of the crude oil due to their emulsifying action and theirs potentiality for splitting acyl glycerol in free fatty acid. Some phospholipids contained in crude vegetable oil are also combined with element like calcium, magnesium and phosphorus and theirs amount in the oil should be under some recommended values in order to match biodiesel quality 14

15 standards (Banga and Varshney, 2010). There are two kinds of phospholipids in crude vegetable oil, hydratable and non hydratable phospholipids Hydratable phospholipids In contact with water, hydratable phospholipids produce gums that are not soluble with oil and can be separated from oil by centrifugation. There are two main hydratable phospholipids phosphatidyl choline (PC) and phosphatidyl inositol (PI). PC contains a quaternary ammonium salt (figure 1) with a positive charge at all ph values and good affinity for water. At ph less than 3 phosphatidyl choline has only a positive charge. PC is hydratable at all ph value. At ph less than 5 phosphatidyl inositol (figure 2) has no charge and at ph over 5 PI has one negative charge. Hydroxyl group of inositol structure give to PI hydrophilic behavior and consequently PI is hydratable by water at all ph values. Figure 1 : Molecular structure of phosphatidyl choline (PC) Figure 2 : Molecular structure of phosphatidyl inositol (PI) Non hydratable phospholipids The main non hydratable phospholipids are phosphatidyl ethanolamine (figure 3) and alkali salts (calcium and magnesium salts) of phosphatidic acid (figure 4). 15

16 Figure 3 : Molecular structure of phosphatidyl ethanolamine (PE) Figure 4 : Molecular structure of phosphatidic acid (PA) PE can be hydratable with water and produces insoluble gum only if the ph is lower than 3 or higher than 9. Phosphatidic acid is mainly associated with calcium and magnesium salts in vegetable oils. Calcium and magnesium salt should be dissociated from phosphatidic acid and ph increase to at least 10 for making it insoluble with oil. Citric acid or phosphoric acid are chemicals that can be used for the dissociation of calcium and magnesium salt from phosphatidic acid (Sekretar et al., 2008). According to the project objective Jatropha seed have been pressed for producing crude oil intended for biodiesel production. For this purpose the oil degumming procedure to implement should allow decreasing the amount of calcium, magnesium and phosphorus under some recommended value in order to match biodiesel quality standards. The oil degumming procedure will be the one that uses citric or phosphoric acid because these chemical are effective for removing calcium, magnesium and phosphorus from crude vegetable oil. For implementing the oil degumming citric acid will be use instead phosphoric acid because it is more affordable than phosphoric acid in Lao PDR. 1.2 ACID VALUE DECREASING Biodiesel is produced by trans-esterification of oil with basic catalysts like sodium or potassium methoxide or sodium or potassium hydroxide. Sodium hydroxide is the most used catalyst for trans-esterification because it is affordable and cheaper than the others catalysts. The quantity of sodium hydroxide that is need for trans-esterification is one percent to oil weight basis. This quantity is enough if the oil has an acid value less than 1 milligram of KOH per gram of oil but for higher acid value additional quantity of catalyst is need for the neutralization of the excess of free fatty acid contained in the crude oil. 16

17 The neutralization of free fatty acid by the catalyst produces soap and water according the reaction depicted by the figure 5. The neutralization of free fatty acid is only effective if the acid value is under or equal to 2 milligrams of KOH per gram of oil. Over this value the neutralization of free fatty acid by the catalyst will produce more quantities of soap and water that will affect the yield of trans-esterification. Figure 5 : Neutralization of free fatty acid RCO 2 H + NaOH RCO 2 Na + H 2 O Free fatty acid Sodium hydroxide Soap Water Over an acid value of 2 milligrams of KOH per gram of oil, free fatty acid should be removed from oil before implementing the trans-esterification. The most used process for decreasing acid value of oil is esterification of free fatty acid with methanol in presence of acid catalyst according to the reaction depicted by the figure 6. Figure 6 : Esterification of free fatty acid RCO 2 H + MeOH H Free fatty acid Methanol RCO 2 CH 3 + H 2 O Fatty methyl ester Water In presence of acid catalyst like sulphuric acid or hydrochloric acid free fatty acid react with methanol for producing fatty methyl ester (biodiesel) and water. This reaction is the most used for decreasing acid value of oil before transesterification however it has three main drawbacks that are: - The need of corrosion tight equipment; - The need to recover methanol after the completion of the reaction; - The acid value should be higher than ten milligrams of potassium hydroxide per gram of oil. 17

18 Esterification is a reversible reaction and if it is implemented according the quantities of the figure 6 that are one mole of free fatty acid to one mole of methanol, after some time the reaction reaches equilibrium and no more fatty methyl ester is produced. In order to transform all the free fatty acid in fatty methyl ester, methanol should be use in excess and consequently the methanol that was not consumed by the esterification should be recovered after the reaction. Esterification is implemented with acid catalyst like sulphuric acid or hydrochloric acid. These chemicals are very corrosive and esterification should be implemented in corrosive tight vessel like glass lined reactor or glass vessel. The kinetic of chemical reaction (the rate of reagent consumption or rate of product appearance) is proportional to the concentration of initial reagents. Low concentration of reagent results in slow rate of reagent consumption and lengthy process. In case of esterification of oil with low acid value a very large excess of methanol should be used in order to increase the rate of the reaction. The esterification of free fatty acid can be implementing with sufficient quantity of methanol only if the acid value of the oil is equal or higher than ten milligrams of KOH per gram of oil. At the beginning of the research and development phase the available Jatropha oil contained quiet large amount of free fatty acid (more than 10 percents) making it unsuitable for direct trans-esterification. Despite the fact that esterification with methanol and acid catalyst is the most used process for decreasing acid value of oil before trans-esterification we did not choose this process because of the unsuitability of the pilot equipment for this kind of reaction. Facing to this equipment un-suitability we have decided to find another alternative than esterification of free fatty acid for decreasing oil acid value. The degumming procedure consist to mix oil with a solution of citric acid then to add the necessary quantity of alkali to neutralize citric acid and to raise the ph to 10 for separating calcium and magnesium from phosphatidic acid (see paragraph I.1.1.2). If the added quantity of alkali is sufficient to neutralize citric acid, free fatty acid and raise the ph to 10, calcium and magnesium compounds will be separate from phosphatidic acid and insoluble soap will be produce from free fatty acid. The transformation of free fatty acid in soap and their separation from oil will result in acid value decreasing. This oil degumming procedure will remove gums and free fatty acid in the same time. 1.3 PROCEDURE FOR DECREASING BIODIESEL LOSS DURING THE WASHING When implementing trans-esterification of oil with sodium hydroxide or potassium hydroxide for producing biodiesel, some quantities of soap are always produced even if the oil contains no free fatty acid (Vicente et al., 2003). The catalyst of trans-esterification reacts with oil for producing fatty methyl ester (biodiesel) but it also reacts with oil for producing soap by saponification during the trans-esterification. Saponification is a side reaction of trans-esterification. If the oil has an acid value lower or equal 2 milligrams of KOH per gram, the quantity of sodium hydroxide to implement for trans-esterification is one percent to oil weight and the necessary quantity for neutralizing the free fatty acid contained in the oil. In this case soap will be produce by saponification and by the neutralization of free fatty acid. After trans-esterification and glycerol separation the biodiesel is washed with water to remove any trace of catalyst and glycerol derivatives. The presence of soap during the washing affects the yield of biodiesel because it increases the solubility of biodiesel in water resulting in biodiesel loss. Soap also makes stable emulsions with water and biodiesel that take lengthy time for the separation. If after trans-esterification and glycerol separation, the soaps produced during the trans-esterification are removed from biodiesel before the washing less biodiesel will be loss and no stable emulsion will occur during the 18

19 washing. After glycerol separation the treatment of biodiesel with a solution of gelatin can effectively separate soap from biodiesel resulting in less biodiesel loss during the washing. 1.4 RESULTS OF RESEARCH AND DEVELOPMENT PHASE Research and development phase has focused on the implementation of procedures for oil degumming, acid value decreasing and decreasing biodiesel loss during the washing Oil degumming and acid value decreasing The implemented procedure for oil degumming and acid value decreasing consist to treat the crude oil with a citric acid solution at 80 o C during 30 minutes then to cool the mixture to room temperature. When the mixture reaches room temperature a solution of sodium hydroxide is added to the mixture for neutralizing citric acid and free fatty acid. After neutralization soap and gums are separated from the oil by centrifugation and the oil is washed with de-ionized water and dry to remove any trace of water. By comparing the plate 1 (crude oil) and the plate 2 (oil after treatment) we can notice that the procedure can effectively remove gums and impurities from crude oil. Plate 1 : Oil before degumming Plate 2 : Oil after degumming 19

20 In order to check the efficiency of the procedure it has been implemented with several kinds of oils with different acid value and the obtained results are gathered in the table 1. Table 1 : Oil degumming and acid value decreasing procedure Batch number Oil Initial acid value (mg KOH/gram of oil) 20 Final acid value (mg KOH/gram of oil) CAD 24 Waste cooking oil CAD 27 Jatropha oil /Waste cooking oil CAD 28 Jatropha oil /Waste cooking oil CAD 29 Jatropha oil /Waste cooking oil CAD 20 Jatropha oil a a : oil yield after centrifugation The procedure for oil degumming and acid value decreasing has been implemented with waste cooking oil, Jatropha oil and mix of Jatropha oil and waste cooking oil in order to have an initial acid value of the oil ranging from 1.38 to milligrams of KOH per gram of oil. According the results of table 1 the procedure is quiet efficient for decreasing the acid value of the oil less than 1 milligram of KOH per gram. However if the acid value of the oil is higher than 5 milligrams of KOH per gram, the yield of oil decreases dramatically and with an acid value over 30 like the test CAD 20 it was impossible to recover the oil because of the occurrence of stable emulsion during the washing. For this test the yield of oil has been measured after centrifugation and not after washing and final acid value was not measured. This procedure is suitable for oil with an acid value less or equal to 5 milligrams of KOH per gram because for higher acid value the low yield of oil makes the treatment un-profitable. However in the case of oil with high acid value it is possible to mix it in small proportions with oil having low acid value in order to decrease the acid value of mixed oil under 5 milligrams of KOH per gram. Concerning the amount of metallic salts like calcium, magnesium and phosphorus contained in crude oil, we do not know if the procedure is efficient for removing these compounds from the oil because there is no laboratory in Lao PDR with suitable analytical equipment (atomic absorption spectrophotometer) for quantifies these compounds in vegetable oil Decreasing biodiesel loss during the washing The treatment for decreasing biodiesel loss during the washing is implemented just after the separation of glycerol from biodiesel. The trans-esterification is implemented by heating the oil one degree Celsius under the boiling temperature of methanol (64 o C) and when the oil reaches this temperature the catalyst is introduced in the oil and the transesterification is ran for one hour at 63 o C under mixing (400 rpm). After one hour the mixing is stopped and the mixture is let for decantation during one hour in order to separate the glycerol from the biodiesel. Yield (%)

21 After glycerol separation the biodiesel is mixed at room temperature during 15 minutes with an aqueous solution of gelatin (5 % w/w) than the mixture is let at rest for one night. After one night the gelatin solution is separated from biodiesel and this later is washed with de-ionized water. The end of washing is assessed by putting some drop of turmeric extract in the water used for washing. If the water turns red (ph over 7.4) the biodiesel is washed again. If the water turns yellow (ph under 7.4) the washing is stopped. In order to assess the efficiency of the treatment several tests have been implemented with and without gelatin treatment and with different percentages of gelatin. The obtained results are gathered in the table 2. From the results of table 2 by comparing the yield of the batch TAG-17 with the yields of the batches TAG-20, TAG-21 and TAG-22, we can observe that gelatin treatment can effectively decreases biodiesel loss during the washing. An amount of five percents of gelatin by weight is enough for decreasing biodiesel loss during the washing. Gelatin treatment can also be implemented with oil with quiet high acid value like in the case of the batch TAG-31. This batch gives the lower yield of all the tests but the number of washing is similar to the other batches showing that gelatin treatment is quiet effective for removing soap produced during the trans-esterification. From the table 2 one can also observe that biodiesel yield decreases when acid value of the oil increases. Table 2 : Results of gelatin treatment Batch number Oil Acid value (mg KOH/g) Gelatin treatment Percent of gelatin (%) Numbers of washing TAG-17 Refined soy bean No TAG-20 Refined soy bean Yes TAG-21 Refined soy bean Yes TAG-22 Refined soy bean Yes TAG-23 Refined soy bean Yes TAG-24 Refined soy bean Yes TAG-25 Refined soy bean Yes TAG-26 Refined soy bean Yes TAG-27 Refined soy bean Yes TAG-28 Refined soy bean Yes TAG-29 Citric acid degummed oil 0.66 Yes TAG-31 Waste cooking oil 2.05 Yes Yield (%) 21

22 1.4.3 Summary of research and development phase results The procedure for oil degumming and acid value decreasing can effectively remove gums and decrease acid value less than 1 milligram of KOH per gram of oil. However the oil to implement should have an acid value less than five milligrams of KOH per gram of oil. Over this value the yield of oil decreases dramatically and the treatment is unprofitable. In case of oil with high acid value it is possible to mix it in small quantities with oil having low acid value in order to have an acid value less than five milligrams of KOH per gram of oil. Treatment with gelatin is efficient for removing soap from biodiesel after trans-esterification and for decreasing biodiesel loss during the washing with de-ionized water. A gelatin solution of five percents by weight is enough for effectively remove soap from biodiesel and only four washing with de-ionized water are need for clean the biodiesel instead nine without gelatin treatment. 2 IMPLEMENTATION OF BIODIESEL PRODUCTION Before the implementation of trans-esterification for producing fatty methyl ester (biodiesel), the oil should undergo physical and chemical treatments in order to remove some impurities contained in the oil in order to make it suitable for trans-esterification. The main impurities to remove are water, gums (phospholipids), solid particles, metallic salts like calcium and magnesium and free fatty acid. The number of processing steps to implement depends on the origin of oil, its composition and the amount of free fatty acid contained in the oil. According to the origin of oil the impurities contained in the oil are different. Crude vegetable oil like Jatropha oil contains solid particle coming from the pressing and gums (phospholipids) whereas waste cooking oil contains solid particles coming from the food processing. Concerning free fatty acid contained in crude vegetable oil their concentration increase with seed moisture during the seed storage before pressing. For cooking oil the concentration of free fatty acid increases with the number and the temperature of frying. 2.1 BIODIESEL PROCESSING STEPS The numbers of processing steps of biodiesel production depend on the oil origin and acid value. The origin of oil can be crude vegetable oil, waste cooking oil or mixed oil. Sometime the crude vegetable oils intended for biodiesel production have high acid value (over 5 milligrams of KOH per gram of oil) that making them unsuitable for oil degumming and acid value decreasing procedure because of the low obtained yield (see table 1). In this case the oil with high acid value can be mixed with oil having low acid value in order to have an acceptable acid value in the mixed oil before the implementation of oil degumming and acid value decreasing procedure. The table 3 lists the processing steps to implement according the origin and the acid value of the oil. 22

23 Table 3 : Biodiesel processing steps according the origin and acid value of oil Origin of oil Acid value CF CAD DAV TAG WKO AV 2 WKO 2<AV<5 Mixed oil (WKO 80%) AV 2 Mixed oil (CVO 80%) AV 2 Mixed oil (WKO 80%) 2<AV<5 Mixed oil (CVO 80%) AV<5 CVO AV<5 WKO : Waste cooking oil Mixed oil : Cooking oil mixed with other crude vegetable oil (e.g. Jatropha oil); CVO : Crude vegetable oil AV : Acid value (milligrams of KOH per gram of oil) CF : Centrifugation; CAD : Citric acid degumming; DAV : Decreasing acid value; TAG : Trans-esterification of acyl glycerol. For biodiesel production implemented from waste cooking oil only, the number of processing steps to implement will depend on the acid value of the oil. For oil with acid value lower or equal 2 after centrifugation the trans-esterification can be implementing directly. If the acid value is between 2 and five after centrifugation the DAV step will be implementing before trans-esterification. If the acid value is higher than five, it should be decreasing under this threshold otherwise the trans-esterification will not run to completion. For this case after centrifugation, the acid value of the oil can be decrease under five by mixing the oil with oil having a lower acid value. For mixed oil containing a percentage of waste cooking oil equal or higher to 80 %, with an acid value lower or equal to 2, trans-esterification of oil can be implementing just after centrifugation but if acid value is over 2 and under 5 the DAV treatment should be implementing for decreasing acid value before trans-esterification. In the case of mixed oil containing a percentage of crude vegetable oil equal or higher to 80 % the CAD step should always be implementing before trans-esterification. For crude vegetable oil the CAD step should also be implementing even if the acid value is less or equal to five because crude vegetable oil contain phospholipids that should be removing from the oil before making biodiesel. 23

24 2.1.1 Centrifugation (CF) After pressing, the crude vegetable oil contains some solid particle coming from seed shell, water and gums. Waste cooking oil also contains solid particle and water coming from food processing. These impurities are removed from the oil by a physical treatment call centrifugation. By introducing a mixture of oil, solid particle and water in a bowl rotating at high angular velocity the mixture is subject to a centrifugal acceleration allowing the separation of components mixture because of densities difference of components mixture Citric acid degumming (CAD) Citric acid degumming is implemented to remove hydratable and non hydratable phospholipids from oil but also calcium and magnesium salts associated with some non hydratable phospholipids. The process consists to make an emulsion by stirring at 800 rpm the oil with a solution of citric acid, to heat the emulsion at 80 o C for 30 minutes and to cool to the room temperature. When the mixture reaches room temperature a sodium hydroxide solution is added to the mixture and the all is stirred for 5 minutes by hand at room temperature. By adding sodium hydroxide to the emulsion the ph increasing makes possible the separation of the gums from the oil. The addition of sodium hydroxide also transforms free fatty acid in soap that decreases the acid value of oil. After the oil is filtrated for one night, centrifugated and washed with de-ionized water until the ph is neutral then the oil is centrifugated again to remove any trace of water Decreasing acid value (DAV) Free fatty acid neutralization is implemented for decreasing the acid value of oil under 2 milligram of KOH per gram of oil. A sodium hydroxide solution is added to the oil and the all is stirred at room temperature for five minutes by hand. Then the mixture is filtrated for one night, centrifugated and washed with de-ionized water until the ph is around 7 then the oil is centrifugated again for removing any trace of water Trans-esterification of acyl glycerol (TAG) The aim of trans-esterification is to transform acyl glycerol (oil) in fatty methyl esters. Fatty methyl esters are produced by reacting acyl glycerol with methanol in presence of alkaline catalyst like sodium hydroxide. Trans-esterification consists first to produce sodium methoxide by dissolving sodium hydroxide in methanol then to introduce the mixture in oil previously heated at 63 o C. The all is maintained at 63 o C for 60 minutes with stirring at 400 rpm then it is let for decantation during one hour. After decantation the glycerol phase is separated from the organic phase and an aqueous solution of gelatin is add to the organic phase and the all is emulsified at room temperature then let for decantation during one night. The aim of mixing aqueous solution of gelatin with biodiesel is to remove soap from biodiesel phase in order to avoid emulsion during the washing. The formation of emulsion during washing increases the loss of biodiesel and decrease the yield of the product. After one night of settling gelatin phase is separated from organic phase and the latter is washed with deionized water until ph neutral and centrifugated to remove any trace of water. 2.2 EQUIPMENTS AND PROCEDURES A biodiesel production is constituted by a series of processing step. Each processing step is implemented for obtaining an output by the way of chemical (or/and physical) transformation of an input. The output can be final or intermediary 24

25 product and the input can be a raw material or an intermediary product. Each processing step uses specific equipments and is implemented according specific procedures Equipments A processing step is implemented with specific equipments that should be well identified during the processing. The handling of the equipments that are need for a specified processing step should also be well understood by the process operators in order to avoid mistake, hazardous handling or accident. In order to well identify the equipments for a specified processing step, the process equipments are depicted in a scheme and labeled with specific code or numbering. This scheme is call process diagram and allows identify the equipments that are need for the implementation of each processing step and show the connections between the equipments (appendix 1). Two kinds of equipments are used for biodiesel production, fluid flow equipment (centrifuge, feeding tank, plate filter, pump and valve), heat and mass transfer equipment (degumming tank, mixer, trans-esterification reactor and settling vessel) Biodiesel processing procedures Each processing steps is implemented according one or several specific procedures (appendix 2). The established procedures should be safe, reliable and should not endanger the process operators or cause accident. A procedure is implemented for several objectives that are : -The appointment of the equipments that are need for the processing step; -The specification of process parameters (duration, quantities, temperatures); -The detailed scheduling of equipments use and tasks to implement The appointment of equipment The equipments that are need for the processing step should be well identified by the process operators in order to avoid mistake, hazardous practice or lost of product during the implementation of the processing step The specifications of process parameters The processing step should be implementing with the parameters that are specified in the procedure. The process operators and process supervisors should not change the specified parameters without the authorization of the process manager The detailed scheduling of equipment use and task to implement Like process parameters the detailed scheduling of equipment use and task to implement should not be change by process operators or process supervisor without the authorization of the process manager. 2.3 PROCESS MONITORING AND TOTAL PRODUCTION EXPENSE During the implementation of a production, one should be able to assess the efficiency of each processing step implemented during the production. The efficiency of a processing step is estimated by comparing the yield of the product obtained with the cost for producing (or purify) the product. The knowing of the efficiency of all the processing 25

26 steps implemented in a production allows estimating the global efficiency of the production. For this purpose the process should be monitored and data collected at the operational level by the process operator and recorded in a batch data recording sheet. The data from the batch data recording sheet are then transformed at the supervision level in term of material balance and energy consumption. The material balance and energy consumption and other economical data will allow the process manager to calculate the total production expense, the processing cost per unit of product and to assess the profitability of the production on a monthly or annual basis Batch data recording sheet In this document is recorded the raw data obtained during the implementation of a processing step. The data are recorded at the operational level by the process operator. The batch data recording sheet provides basic information for estimating the efficiency of the processing step but also information for checking if the processing step has been implemented according established procedure. The document includes data like the date of processing; the batch number of oil, the batch number of the processing step, the name of the process operator in charge of the processing step, the duration of equipments run, the implemented quantities (fuel, input and utilities) and obtained quantities (output). The process operators can also include some comments in case of problem encountered during the processing Batch report The batch report is implemented by the process supervisor. The data coming from the batch data recording sheet are transformed by the process supervisor in term of material balance and energy consumption. Concerning the energy consumption of biodiesel pilot plant installed on the site of Lao State Fuel Company, the equipments are run or heat with electricity so only electrical consumption will be taking into account for the estimation of energy consumption Material balance The purpose for making material balance of a processing step is to verify the mass conservation and to check if no loss has been occurred during the processing step implementation. Most of the time, the material balance is depicted by a table like the table 4. The table is made up of two main columns the input and the output that are subdivided into two others columns, one for the kind of compound and one for its weight. The compounds in the input column are the compounds that are implemented in the processing step and the compounds in the output column are the compounds that are obtained after the implementation of the processing step. For the input and output column the total weight is the sum of all the compounds. In the material balance table, the conservation of mass is checked by the calculation of weight gap. The weight gap is expressed in percentage and is equal to the difference between the total weight of the input and the total weight of the output divided by the total weight of the input. For a production like biodiesel the weight gap should not exceed 5 %, if the weigh gap exceeds this value some product has been lost or operator has mad mistake during the input or output weighting. 26

27 Table 4 : Material balance presentation Input Output Compound Weight (kg) Compound Weight (kg) Input 1 Output 1 Input 2 Output 2 Input 3 Output 3 Total weight (kg) Total weight (kg) Weight Gap (%) Electrical consumption Like material balance electrical consumption is depicted by a table like the table 5. Table 5 : Electrical consumption presentation Equipment Power (Watts) Duration of run (seconds) Energy consumption (Joules) Electrical consumption (kwh) Equipment 1 Equipment 2 Equipment 3 Equipment 4 The table for electrical consumption is made of five columns, one for the kind of equipment used in the processing step, one column for its power, one column for the duration of its run during the implementation of the processing step, one column for the energy consumption of the equipment during the run and one column for calculating its electrical consumption during the processing step implementation. The calculation of electrical consumption is implemented in three steps. The first step consists to make the conversion of run duration in second. The second step calculates the energy consumption expressed in Joules during the equipment run by multiplying the power of the equipment (Watt) by its run duration (seconds). The third step consists to convert the energy consumption (Joules) in electrical consumption (kwh) by dividing the energy consumption by 3.6 millions of Joules. The sum of all the individual electrical consumption gives the total electrical consumption during the processing step. 27

28 2.3.3 Total production expense Total production expense is the sum of total manufacturing expense, packaging and shipping expenses. The total manufacturing expense is the sum of net raw material expense, total direct expense and total indirect expense Net raw material expense The net raw material expense is the difference between the gross raw material expense and the total by-products credit. The table 6 gives an example of net raw material expense presentation. Table 6 : Net raw material expense presentation Raw materials Raw material 1 Raw material 2 Raw material 3 Quantities per month (kg) Gross raw materials expense (US$) By-products By-product 1 By-product 2 Total by-products credit (US$) Net raw material expense (US$) Quantities per month (kg) Unit cost (US$/kg) Unit cost (US$/kg) Cost per month (US$) Cost per month (US$) Sometime production produces by-products that have a market value or be use downstream for producing other compounds or energy. In these cases by-products are credited with an equivalent value. If the by-products are waste no credit are attributed Total direct expense Total direct expense includes utilities, operating labor, supervision, payroll charges, maintenance, miscellaneous direct expense and environmental control expense. The utilities include cooling water, compressed air, de-ionized water, electricity, fuel, steam, refrigeration, tap water, vacuum, etc. Concerning operating labor, supervision and payroll charges, the biodiesel pilot installed at Lao State Fuel Company should be run with one operator and one supervisor. In Lao PDR the payroll charges of a Lao state owned company is ten percents of the monthly salary. The cost of maintenance is estimated to one percent of the fixed capital cost of the pilot. The miscellaneous direct expenses are mainly laboratory expenses and are estimated to US$10 per hour of laboratory use. Concerning 28

29 environmental control expense the Lao State Fuel Company has its own waste disposal facility and this expense will not be taking into account for the calculations of total direct expense Total indirect expense Total indirect expense consists of two major items, the depreciation and plant indirect expense. The depreciation is an allowance for the decrease in value of equipments over the time due to wear or normal obsolescence. One of the methods for calculating annual depreciation is the straight line method expressed by the formula below : D : Annual depreciation; I : Investment; S : Salvage value; n : Number of years of use. Plant indirect expense cover a wide range of items like property taxes, personal and property liability insurance premiums, fire protection, plant safety and security, road, yard and dock plant maintenance and plant personnel staff. Without company data plant indirect expense is estimated on the order of 2 to 4 percents of fixed capital investment (Perry s Chemical Engineers Handbook, 2008) 3 BIODIESEL PRODUCTION START UP Biodiesel process has been implemented in laboratory from crude Jatropha oil, waste cooking oil and mixed oil (crude Jatropha oil and waste cooking oil). However the biodiesel production start up has been mainly implemented with waste cooking oil because the Jatropha seeds of Lao State Fuel Company were unsuitable for producing oil with acceptable yield and quality. During the start up the biodiesel production has also encountered several problems. 3.1 ENCOUNTERED PROBLEMS Two kinds of problems were encountered during the biodiesel production start up, processing problems and equipment problems Processing problems Technical problems were encountered during centrifugation, acid value decreasing, glycerol separation and gelatin treatment Centrifugation At the beginning of the start up the completion of centrifugation step took a very lengthy time. This processing step was implemented by filling completely the feeding tank with oil then the centrifuge was run just after the feeding tank filling. 29

30 During the centrifugation the flow of oil coming from the feeding tank was not constant because solid particles contained in the oil were carried away and clogged the feeding tank valve. The problem has been solved by filling the plate filter instead feeding tank with oil before centrifugation then the oil was let at rest for one night before centrifugation. During one night at rest solid particles contained in the oil have the time to settle in bottom of plate filter and are not carried away with oil during centrifugation Acid value decreasing This processing step is implemented when the oil has an acid value around 5 milligrams of KOH per gram of oil and consist to add to the oil and quantity of sodium hydroxide for neutralizing the free fatty contained in the oil. When acid value decreasing was implemented in the degumming tank under mixing, the high speed of the impeller (800 rpm) has caused soap particles erosion and the occurrence of very small soap particles that clogged the paper filter during the soap filtration. At present the acid value decreasing is implemented in plastic drum and mixed manually to avoid the erosion of soap particles Glycerol separation In laboratory after trans-esterification the mixture of biodiesel and glycerol is let at rest for one hour in order to separate biodiesel from glycerol. During this time the temperature of the mixture decreases from 62 o C to room temperature (between 25 O C and 30 O C) and after glycerol is completely separated from biodiesel. When implementing the procedure at the pilot level, after one hour the temperature of trans-esterification reactor only decreases few degrees under 62 o C because of mass effect and the glycerol is not completely separated from biodiesel, resulting in biodiesel loss during glycerol separation. In order to solve this separation problem the duration of rest after transesterification has been increased to one night in order to well separate glycerol from biodiesel Gelatin treatment This treatment is implemented at the end of trans-esterification step after separating glycerol from biodiesel. The aim of this treatment is to separate the soap from biodiesel for decreasing biodiesel loss during the washing with water. The treatment is implemented by mixing biodiesel with a gelatin solution during 15 minutes and to let at rest during one night. After one night the gelatin phase containing soap is separated from biodiesel. If the mixing is implemented in the degumming tank under mixing, the high speed of the impeller (800 rpm) mad an emulsion of gelatin and biodiesel, making impossible the separation of gelatin solution from biodiesel. An emulsion has also occurred if a mixture of gelatin and biodiesel are transferred together by the centrifugal pump of the pilot. The emulsion of gelatin and biodiesel can be demulsified and separated by heating the mixture at 150 O C but this treatment increase the acid value of biodiesel. To avoid emulsion formation during the gelatin treatment, biodiesel and gelatin should be transferred separately and mixed together by air blowing in the settling vessel Equipment problems The biodiesel production start up has also encountered problems with equipments like centrifugal pumps, temperature control, bottom tank valves and the seal of settling vessel window. 30