MATEC Web of Conferences 168, 07014 (2018) https://doi.org/10.1051/matecconf/201816807014 XXI. AEaNMiFMaE-2018 Experimental Modelling of Autoignition Temperature for Alkyl/Alkenyl Products from Fischer-Tropsch Synthesis Jan Skřínský1,*, Ján Vereš, and Karel Borovec 1Energy Research Centre, VSB-TU Ostrava, 708 33 Ostrava - Poruba, Czech Republic Abstract. Interest in Fischer-Tropsch technology is increasing rapidly. Alkyl/alkenyl products from Fischer-Tropsch synthesis are alternative, renewable, environmentally and economically attractive fuels and there are considered one of the most favorable fuels for conventional fossil-based fuels. The chemistry of this gas-to-liquid industry converts synthesis gas containing carbon monoxide and hydrogen to oxygenated hydrocarbons such as alcohols. The fire hazards associated with the use of these liquid hydrocarbons mixtures are obvious. This article aims to explore the fundamental fire and explosion characteristics for main products composition from Fischer-Tropsch synthesis. 1 Introduction 1.1 Interest and challenges Nowadays there is a worldwide demand to develop energy efficient and economical processes for sustainable production of alternative chemical compounds and fuels as a substitute for those emerging from petroleum [1]. Autoignition temperature (AIT) is one of the most important variables used to assess fire and explosion hazards of flammable liquids. It is the lowest temperature at which the test substance will ignite when mixed with air under the conditions defined in the test method. In the industry, it is used for convenient and reliable classification of the flammability of liquids. Investigation of autoignition is always a challenge because AIT depends on several physical-chemical properties, which are discussed in [2]. 1.2 Previous studies We realized after a careful bibliographic search autoignition temperature data for methanol, ethanol, propanol, 2-butanol, 1-butanol, and 2-methyl-2,4-pentanediol [3]. These authors soon carried out a re-investigation of the effect of experimental conditions on measuring autoignition temperatures of pure liquid chemicals [4]. In our recent investigation, we identify the effect of experimental conditions on measuring autoignition temperature of * Corresponding author: [email protected] © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/). MATEC Web of Conferences 168, 07014 (2018) https://doi.org/10.1051/matecconf/201816807014 XXI. AEaNMiFMaE-2018 methanol and ethanol binary mixtures [5]. We have extended the measurement of autoignition temperature of 1-pentanol and its binary mixtures with water [6]. Presented results should provide essential information for the chemicals prepared by Fischer-Tropsch micro catalyst bed avaible at Energy Research Centre, VSB-TU Ostrava and include light hydrocarbons (C1 and C2), olefins, LPG (C3-C4), naphtha (C5-C11), diesel (C12-C20) and wax (>C20) [7]. 2 Experiment 2.1 Experimental device Experiments were done in the test vessel made by OZM Research s.r.o. and is described in [2]. It generally consists of: 1) mirror mounted above the flask so that the observer may see into the flask without having to be directly over it; 2) insulated cover; 3) electrically heated crucible furnace; 4) aluminium, to promote temperature uniformity; 5) test temperature Chromel-Alumel thermocouple; 6) borosilicate round-bottom, short-necked boiling flask; 7) external thermocouple (bottom); 8) external thermocouple (middle); 9) external thermocouple (top). The photography of the whole system is at Figure 1a and schema is introduced at Figure 1b. a) b) Fig. 1. a hotography a scheme f he utoigniti teperature appratus. 2.2 Experimental procedure The experimental procedure meet the test requirements described by the test method of ASTM E659-78:2005. The amount of substance and the temperature of the test vessel, which is filled with air are varied to find the lowest temperature (of the hot surface) that causes ignition. This standard test method is designed to determine the autoignition temperature of a flammable vapour in air mixture with air at ambient pressure and temperature up to 650 °C. After the internal flask temperature has reached the desired temperature, we have adjusted the temperature controller to maintain this temperature within the designated limits and allow the system to equilibrate. The sample, approximately 50-250 uL, was injected into the uniformly heated flask containing air at a predetermined temperature. After insertion of the sample, the contents of flask were observed in a dark room for 10 min, or until autoignition occurred. 2 MATEC Web of Conferences 168, 07014 (2018) https://doi.org/10.1051/matecconf/201816807014 XXI. AEaNMiFMaE-2018 methanol and ethanol binary mixtures [5]. We have extended the measurement of Autoignition evidenced y sudden pearance of flam insid th flask d y autoignition temperature of 1-pentanol and its binary mixtures with water [6]. Presented sharp is in temperature of g mixture. hen h mixtur exhibited lam a the results should provide essential information for the chemicals prepared by Fischer-Tropsch pr temperature, nex samp was ed lower temperature. h rocedures micro catalyst bed avaible at Energy Research Centre, VSB-TU Ostrava and include light wer repeated ntil e west temperatur which th mixtur xhibited flames was hydrocarbons (C1 and C2), olefins, LPG (C3-C4), naphtha (C5-C11), diesel (C12-C20) and obtained [5]. wax (>C20) [7]. 3 Results 2 Experiment 3.1 Autoignition images 2.1 Experimental device Figure 2 depicted e occurrence f n toignition by he udden pearance f flame Experiments were done in the test vessel made by OZM Research s.r.o. and is described in outsid lask following by harp ris th peratur f th mixture i Figure 3- [2]. It generally consists of: 1) mirror mounted above the flask so that the observer may see 4. Th illustrativ samp s en from [5]. Th ten of this temperatur is epends into the flask without having to be directly over it; 2) insulated cover; 3) electrically heated upon difference etween r of ea generation within h mixtur and r of crucible furnace; 4) aluminium, to promote temperature uniformity; 5) test temperature hea loss chamber walls. Th characteris erm effects when combustible liqui Chromel-Alumel thermocouple; 6) borosilicate round-bottom, short-necked boiling flask; i introduced to h chamber at differen in mperatur illustrated y the time- 7) external thermocouple (bottom); 8) external thermocouple (middle); 9) external temperatur rv o igure 4. thermocouple (top). The photography of the whole system is at Figure 1a and schema is introduced at Figure 1b. a) b) Fig. 2. Deelopment of the flames emitted above the top of the flask (200 ul, 432 °C). 3.2 Combustion plots Fig. 1. a hotography a scheme f he utoigniti teperature appratus. According E659-78, ecorded wo alu for ach temperature, ignition delay me). Figure 3 str minimum utoignition peratur for alkyl/alkenyl 2.2 Experimental procedure produ rom Fischer-Tropsch ynthesis tha is enoted y h red lour. The measuremen f th auto-ignition tarted cording previous stud (between 40- The experimental procedure meet the test requirements described by the test method of 460 °C) th was n e mperatur region wher our ermometer h its highes ASTM E659-78:2005. The amount of substance and the temperature of the test vessel, sensitivity and wher th lowes ho as its AIT. Th amp to tested, which is filled with air are varied to find the lowest temperature (of the hot surface) that approximately uL, w inserted to uniformly heated 00-m glass lask ntaining causes ignition. This standard test method is designed to determine the autoignition air predetermined mperatur (460 °C). This rocedur led etection f mor than temperature of a flammable vapour in air mixture with air at ambient pressure and 350 dentified AIT mos of em n h 430-480 °C. elatively w nitia temperature up to 650 °C. After the internal flask temperature has reached the desired temperatures, ther may further therma fects. The presented AIT record includ h temperature, we have adjusted the temperature controller to maintain this temperature following nformation ot-flam selfignition mperature, SIT (°C), ignition mperature within the designated limits and allow the system to equilibrate. The sample, approximately IT (°C), minimum gnition mperature, T (°C), slo combustion C (°C), and reaction 50-250 uL, was injected into the uniformly heated flask containing air at a predetermined threshold temperature, RTT (°C), for reflame reaction. Figure 4 show combustion lot temperature. After insertion of the sample, the contents of flask were observed in a dark of xperiments or th alkyl/alkeny rodu from Fischer-Tropsch ynthesis. I his figure room for 10 min, or until autoignition occurred. th -axis the ignition elay me between plication of eat mater d s ignition, and he y-axis s h preheated mperatur of h combustion ntainer. 3 MATEC Web of Conferences 168, 07014 (2018) https://doi.org/10.1051/matecconf/201816807014 XXI. AEaNMiFMaE-2018 600 MITSC RRT 580 IT (100 ul) IT (200 ul) SI 560 540 preparation experiment 520 500 480 460 440 Ignition temperature / °C / temperature Ignition 420 400 380 360 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 Time / s Fig. 3. AIT owing to the alkylalkenyl poducts fom Fisher-Topsh snthesis. 500 ASTM 659-78 (2005) 490 500 ml (borosilicate flask) 200 ul 480 430 deg C (MAIT) 54.20 s (ignition delay time) 470 Lowest autoignition temperature: 460 430 deg C hot air gun Verification range (+-1,5 %): 450 423.5 - 436.5 deg 440 430 Ignition temperature / °C / temperature Ignition 430 420 54.20 410 14750 14800 14850 14900 14950 15000 15050 Time / s Fig. 4. Example of the AIT time curve with minimum autoginition tempeatue. 4 MATEC Web of Conferences 168, 07014 (2018) https://doi.org/10.1051/matecconf/201816807014 XXI.