Določitev eksplozijskih parametrov pšeničnega in riževega škroba

Jeraj, Petra (author), Novosel, Barbara (mentor)

Nevarnost pojava prašne eksplozije obstaja v industrijah, kjer se pri procesih uporablja gorljiv prah. Za pojav prašne eksplozije mora biti hkrati izpolnjenih več pogojev, na nastanek, razvoj in posledice fenomena pa vpliva več spremenljivk. V diplomskem delu so predstavljene fizikalne karakteristike in eksplozijski parametri za pšenični in rižev škrob. Predstavljene so vrednosti za nesušena in sušena vzorca. Prikazani so rezultati fizikalnih karakteristik, ki so bile določene s pomočjo termične analize in masne spektrometrije, meritve določanja velikosti delcev in porazdelitve velikosti delcev, meritve specifične površine ter meritve vrstične elektronske mikroskopije. Določeni so bili naslednji eksplozijski parametri: minimalna vžigna energija ter minimalna eksplozijska koncentracija in maksimalni eksplozijski tlak ter maksimalna hitrost porasta tlaka. Vrednost Es je pred sušenjem za pšenični škrob znašala 322,7 mJ, za rižev škrob pa je znašala 256,4 mJ. Po sušenju se je pšeničnemu škrobu Es vrednost znižala za 21 %, riževemu škrobu pa za 90 %. Vrednost MEK je pred sušenjem za pšenični škrob znašala 90 g/m3 in za rižev škrob 105 g/m3. Po sušenju se vrednost MEK riževemu škrobu ni spremenila, pšeničnemu škrobu pa se je znižala za 22 %. Vrednost maksimalnega eksplozijskega tlaka je bila enaka za oba vzorca pšeničnega škroba ter za vzorec nesušenega riževega škroba in je znašala 8,5 bar. Pri sušenem riževem škrobu pa je bila vrednost za 8 % višja. Glede na izračunane vrednosti deflagracijskega indeksa KSt spadata tako nesušen kot sušen pšenični škrob v prvi razred prašne eksplozije, kar pomeni, da sta slabo do zmerno eksplozivna. Rižev škrob pa v obeh primerih spada v drugi razred, kar pomeni, da je močno eksploziven. Glede na rezultate opravljenih določitev ugotavljam, da sušena vzorca predstavljata večjo nevarnost za pojav prašne eksplozije kot nesušena vzorca ter da je rižev škrob v primerjavi s pšeničnim bolj eksploziven, kar pomeni, da bodo v primeru eksplozije riževega škroba hujše posledice kot v primeru eksplozije pšeničnega škroba.

• Language: Slovenian
• Keywords: prašna eksplozija, fizikalne karakteristike, eksplozijski parametri, pšenični škrob, rižev škrob
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2019
• PID: 20.500.12556/RUL-109896
• COBISS.SI-ID: 1538408131
• Publication date in RUL: 10.09.2019

Secondary language

• Language: English
• Title: /

Abstract

The danger of a dust explosion exists in industries where combustible dust is used in the production process. For the dust explosion to occur, several conditions have to be met simultaneously. The occurrence, development and consequences of the phenomenon are influenced by several variables. This thesis examines physical properties and explosion parameters for wheat and rice starch. The values for non-dried and dried samples were measured. Physical properties were analysed based on thermal analysis and mass spectrometry, measurement of the particle size and particle size distribution, measurement of the specific surface area and measurement of the scanning electron microscopy. The following explosion parameters were examined: the minimum ignition energy, the minimum explosible concentration, the maximum explosion pressure and the maximum rate of pressure rise. Before they were dried, wheat starch had the Es value 322,7 mJ and rice starch had the Es value 256,4 mJ. After they were dried, the value of wheat starch was 21 % lower and the value of rice starch was 90 % lower. Before they were dried, wheat starch had the MEC value 90 g/m3 and rice starch had the MEC value 105 g/m3. After they were dried, the MEC value of rice starch remained the same and the value of the wheat starch was 22 % lower. The maximum explosion pressure value was the same for both wheat starch samples and for the non-dried rice starch and was equal to 8,5 bar. The value of dried rice starch was 8 % higher. According to the deflagration index KSt, both non-dried and dried wheat starch belong to the first dust explosion class, which means they are weakly to moderately explosible. Rice starch belongs to the second class in both cases, which means it is strongly explosible. The results of measurements carried out showed that dried starches pose a bigger danger of dust explosion than non-dried starches and that rice starch is more explosible than wheat starch, which means that the consequences of rice starch explosion would be graver than the consequences of wheat starch explosion.

• Keywords: dust explosion, physical properties, explosion parameters, wheat starch, rice starch