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Fire safety in commercial plastic recycling facilities
Devine, C. K. 2025. Fire safety in commercial plastic recycling facilities. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/ecf8c879-18c6-45e5-abee-2d67a87807e2
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| Format: | Thesis |
| Language: | English |
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Stellenbosch University
2025
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| _version_ | 1867614116400594944 |
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| access_status_str | Open Access |
| author | Devine, Courtney Kaylor |
| author2 | Walls, Richard Shaun |
| author_browse | Devine, Courtney Kaylor Walls, Richard Shaun |
| author_facet | Walls, Richard Shaun Devine, Courtney Kaylor |
| author_sort | Devine, Courtney Kaylor |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Devine, C. K. 2025. Fire safety in commercial plastic recycling facilities. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/ecf8c879-18c6-45e5-abee-2d67a87807e2 |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132162 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:46:55.727Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch University |
| publisherStr | Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132162 Fire safety in commercial plastic recycling facilities Devine, Courtney Kaylor Walls, Richard Shaun Quiroz, Natalia Flores Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. Plastics -- Recycling Recycling industry -- Fires and fire prevention Fire protection engineering Plastics -- Thermal properties Industrial buildings -- Fires and fire prevention UCTD Devine, C. K. 2025. Fire safety in commercial plastic recycling facilities. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/ecf8c879-18c6-45e5-abee-2d67a87807e2 Thesis (PhD)--Stellenbosch University, 2025. ENGLISH ABSTRACT: Fires in recycling and waste management facilities are an increasing problem. This research aims to promote plastic recycling by increasing fire safety in commercial plastic recycling facilities by quantifying fire hazards and risk through experimental testing, numerical modelling and consideration of design guidance. The plastic recycling process is mapped out and hazards within the recycling process and auxiliary operations are identified. A recycling process map with identified hazards and preliminary mitigation and prevention strategies is produced. Due to the replicability and consistency of testing, plastic pellets made of recycled plastic material is chosen as the primary material of interest in this research and testing. The plastic types chosen for this research are low density polyethylene (LDPE), high density polyethylene (HDPE) and polypropylene (PP) as these are of the most commonly recycled plastic types in South Africa. Material characterization of these plastic pellets, through cone calorimeter tests, was conducted. Numerical models were developed in fire dynamics simulator (FDS) and used to validate ignition and initial horizontal flame spread. The model’s material and thermal properties (density, thermal conductivity and specific heat capacity) were investigated to identify which parameters gave the most consistent predictions of ignition relative to experimental data. The models were then used to compare experimental test to numerical simulations in which horizontal flame spread was observed. Prevention and mitigation strategies found in codes and standards for facilities handling commodities such as plastic or exposed to hazards present in plastic recycling facilities are detailed. Following this, preliminary large-scale simulations were conducted in which some of these prevention and mitigation strategies identified are implemented and the effectiveness observed. The simulations presented looked at the effect of headroom (ceiling height – stacking height), aisle clearance and partial compartmentation in delaying and/or preventing ignition. The primary fire hazards identified are (i) bulk storage, (ii) production of combustible dust during shredding and (iii) heat sources during the melting and extrusion process. In addition, the change in geometry of plastic material through the recycling process was identified. Thermal properties obtained during cone testing were include time to ignition (TTI), heat of combustion (HOC) and heat release rates (HRR) of varying sample depths (10-90 mm) of plastic pellets. The TTI observed during testing was compared to the analytical equations for TTI of both thermally thin and thermally thick materials. The TTI calculated using the thermally thin equation and loose bulk density showed the best agreement to the TTI observed during experimental testing. HRR curves for different sample depths were produced at 25, 35 and 50 kW/m2. The smaller, shallow samples were concluded to be representative of a thin layer of plastic material lying on the floor while the deeper samples were considered to be representative of the bulk storage. From observations made during material testing, the plastic pellets were found to be difficult to ignite and required a significant and constant heat source in order for a bag of plastic to burn vigorously. However, once alight and sufficient mass was involved in the fire, the plastic pellets burned intensely with high HRRs and released thick, black smoke. Limitations of the numerical models developed include prediction of spread beyond ignition and initial fire spread. The liquid flow of burning plastic material observed during experimental testing was not readily modelled by the solid conduction of heat from one cell to another as governed numerically in FDS. Initial flame spread of the numerical model slightly overpredicts spread, although making use of these models will result in a conservative system design. Finally, the preliminary large-scale simulations indicate that increasing the aisle clearance was an effective strategy in the simulations. However, observations from experimental tests revealed that the bags containing the plastic pellets burns readily, spilling the plastic pellets and rendering predefined aisle clearances less effective. Partial compartmentation, achieved through placing prefabricated walls dividing the aisles of material, proved to be a potentially effective mitigation strategy for delaying ignition or containing a fire. AFRIKAANSE OPSOMMING: Brande in herwinnings- en afvalbestuurfasiliteite is 'n toenemende probleem. Hierdie navorsing het ten doel om plastiekherwinning te bevorder deur brandveiligheid in kommersiële plastiekherwinningsfasiliteite te verhoog deur brandgevare en risiko te kwantifiseer deur eksperimentele toetsing, numeriese modellering en oorweging van ontwerpriglyne. Die plastiekherwinningsproses word gekarteer en gevare binne die herwinningsproses en hulpbedrywighede word geïdentifiseer. ’n Herwinningsproseskaart met geïdentifiseerde gevare en voorlopige versagting- en voorkomingstrategieë word vervaardig. Die primêre brandgevare wat geïdentifiseer is, is (i) grootmaatberging, (ii) produksie van brandbare stof tydens versnippering en (iii) hittebronne tydens die smelt- en ekstrusieproses. Daarbenewens is die verandering in geometrie van plastiekmateriaal deur die herwinningsproses geïdentifiseer. As gevolg van die herhaalbaarheid en konsekwentheid van toetsing, word plastiekkorrels gemaak van herwonne plastiekmateriaal gekies as die primêre materiaal van belang in hierdie navorsing en toetsing. Die plastiektipes wat vir hierdie navorsing gekies is, is laedigtheid poliëtileen (LDPE), hoëdigtheid poliëtileen (HDPE) en polipropileen (PP) aangesien dit van die mees algemeen herwonne plastiektipes in Suid-Afrika is. Materiaalkarakterisering van hierdie plastiekkorrels, deur middel van kegelkalorimetertoetse, is uitgevoer. Termiese eienskappe is bepaal, insluitend tyd tot ontbranding (TTI), verbrandingshitte (HOC) en hittevrystellingtempo's (HRR) van verskillende monsterdieptes (10-90 mm) van plastiekkorrels. Die TTI wat tydens toetsing waargeneem is, is vergelyk met die analitiese vergelykings vir TTI van beide termies dun en termies dik materiale. Die TTI bereken deur die termies dun vergelyking en los massadigtheid te gebruik, het die beste ooreenstemming met die TTI getoon wat tydens eksperimentele toetsing waargeneem is. HRR-krommes vir verskillende monsterdieptes is teen 25, 35 en 50 kW/m2 geproduseer. Die kleiner, vlak monsters is verteenwoordigend van 'n dun laag plastiekmateriaal wat op die vloer lê, terwyl die dieper monsters as verteenwoordigend van die grootmaatberging beskou is. Uit waarnemings wat tydens materiaaltoetsing gemaak is, is gevind dat die plastiekkorrels moeilik is om aan die brand te steek en het 'n beduidende en konstante hittebron nodig om 'n sak plastiek sterk te laat brand. Sodra dit egter aan die brand gesteek is en voldoende massa by die brand betrokke was, het die plastiekkorrels intens gebrand met uiters hoë HRR's en aansienlike dik, swart rook vrygestel. Numeriese modelle is ontwikkel in branddinamika-simulator (FDS) en gebruik om ontsteking en aanvanklike horisontale vlamverspreiding te valideer. Die modelle het materiaal en termiese eienskappe (digtheid, termiese geleidingsvermoë en spesifieke hittekapasiteit) gekalibreer om ontsteking te valideer. Die modelle is toe gebruik om eksperimentele toets met numeriese simulasies te vergelyk waarin horisontale vlamverspreiding waargeneem is. Beperkings van die numeriese modelle is geïdentifiseer in die voorspelling van verspreiding na ontsteking en aanvanklike brandverspreiding. Die vloeistofvloei van brandende plastiekmateriaal wat tydens eksperimentele toetsing waargeneem is, is nie maklik gemodelleer deur die vaste geleiding van hitte van een sel na 'n ander soos numeries in FDS beheer nie. Aanvanklike vlamverspreiding van die numeriese model oorvoorspel verspreiding effens, alhoewel die gebruik van hierdie modelle 'n konserwatiewe stelselontwerp tot gevolg sal hê. Voorkoming- en versagtingstrategieë wat gevind word in kodes en standaarde vir fasiliteite wat kommoditeite soos plastiek hanteer of blootgestel word aan gevare wat in plastiekherwinningsfasiliteite voorkom, word gedetailleer. Hierna is voorlopige grootskaalse simulasies uitgevoer waarin sommige van hierdie voorkoming- en versagtingstrategieë wat geïdentifiseer is, geïmplementeer en die doeltreffendheid waargeneem word. Die simulasies wat aangebied is, het gekyk na die effek van kopruimte (plafonhoogte – stapelhoogte), gangruimte en gedeeltelike kompartementering om ontsteking te vertraag en/of te voorkom. Die verhoging van die gangruimte was 'n effektiewe strategie in die simulasies, maar waarnemings van eksperimentele toetse het aan die lig gebring dat die sakke wat die plastiekkorrels bevat, maklik brand, die plastiekpellets mors en voorafbepaalde gangruimte minder effektief maak. Gedeeltelike kompartementering, wat bereik is deur voorafvervaardigde mure te plaas wat die gange van materiaal verdeel, het geblyk 'n potensieel effektiewe versagtingstrategie te wees om ontsteking te vertraag of 'n brand te beheer. Doctoral 2025-05-28T09:34:08Z 2025-05-28T09:34:08Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132162 en Stellenbosch University 143 pages : illustrations application/pdf Stellenbosch University |
| spellingShingle | Plastics -- Recycling Recycling industry -- Fires and fire prevention Fire protection engineering Plastics -- Thermal properties Industrial buildings -- Fires and fire prevention UCTD Devine, Courtney Kaylor Fire safety in commercial plastic recycling facilities |
| title | Fire safety in commercial plastic recycling facilities |
| title_full | Fire safety in commercial plastic recycling facilities |
| title_fullStr | Fire safety in commercial plastic recycling facilities |
| title_full_unstemmed | Fire safety in commercial plastic recycling facilities |
| title_short | Fire safety in commercial plastic recycling facilities |
| title_sort | fire safety in commercial plastic recycling facilities |
| topic | Plastics -- Recycling Recycling industry -- Fires and fire prevention Fire protection engineering Plastics -- Thermal properties Industrial buildings -- Fires and fire prevention UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132162 |
| work_keys_str_mv | AT devinecourtneykaylor firesafetyincommercialplasticrecyclingfacilities |