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3.2 Identification of Materials and Chemical Hazards in the Process
The production of reformate involves first hydrodesulphurisation process, going to catalytic reforming unit and also alkylation process to produce toluene as a reformate. Then it will go through desalter to get the final product. In this production of reformate, there are several materials and chemicals involved that may carry potentially hazardous risk towards the production plant, as it can be seen in the previous topic there are hazards in the production of methanol and handling of chemicals in general. These different hazards could bring unwanted health and safety hazards towards employees and also the community who is living around the plant. Therefore, hazard identification of the materials and chemicals which are being used in the process should be performed in order to understand the risk involved.
The materials and chemicals that is involved in the process includes:
n-Hexane
1-Pentanethiol (amyl mercaptan)
Hydrogen
Propane (LPG)
Hydrogen sulphide
Toluene
Benzene
Methanol
The methodology to identify potential hazards that these chemicals and materials bring is to analyse the material safety data sheets (MSDS) of these various materials and analysing incompatibilities with other materials and also exposure limits being specified by it.
3.2.1 n-Hexane
n-Hexane is a major feed for reforming process compared to other elements. It is clear colourless liquid. However, it is flammable with auto-ignition temperature 225oC (437 oF). Hexane is a chemical commonly extracted from petroleum and crude oil. It is a colourless liquid that gives off a subtle, gasoline-like odour. Hexane is highly flammable, yet it can be found in many household products such as stain removers for arts and crafts projects. Because of its potential dangers, it is important to know how to handle and store this chemical properly and what to do in the unfortunate event of a fire or human exposure.
Short-term exposure to air contaminated with hexane affects the nervous system and can cause dizziness, nausea, headaches, and even unconsciousness. Chronic exposure can cause more severe damage to the nervous system. If swallowed, it may cause severe abdominal pain and impact the respiratory system, resulting in shortness of breath, coughing, burning of the mouth, throat or chest, and even chemical pneumonitis. Personal protective equipment is recommended whenever handling hexane.
To prevent an explosion of this flammable chemical, hexane should be stored in a closed environment with proper ventilation and explosion-proof electrical equipment and lighting. Do not use compressed air for filling, discharging, or handling and always use non-sparking hand tools
3.2.2.1-Pentanethiol (amyl mercaptan)
1-Penatanethiol or amyl mercaptan is one the minor feed in the process. It is a water white to yellowish liquid with a garlic-like odour. It is usually used in making organic sulphur compound and as a synthetic flavouring agent. It is on the Hazardous Substance List because it is cited by DOT, NIOSH and NFPA. This chemical is on the Special Health Hazard Substances List because it is flammable. Amyl mercaptan can affect when breathed in and contact can irritate the skin and eyes. Breathing this chemical can irritate the nose and throat causing coughing and wheezing. High or repeated contact to 1-pentanethiol may cause a skin allergy. If allergy develops, very low future expose can cause itching and a skin rash. It is a flammable liquid and a dangerous hazard. One of the ways of reducing exposure is where possible, enclose operations and use local exhaust ventilation at the site of chemical release. If local exhaust ventilation or enclosure is not used, respirators should be worn.
3.2.3Hydrogen
Hydrogen is required as the makeup for hydrodesulphurisation process. In normal conditions it’s a colourless, odourless and insipid gas, formed by diatomic molecules, H2. Effects of exposure to hydrogen: Fire: Extremely flammable. Many reactions may cause fire or explosion. Explosion: Gas/air mixtures are explosive. Routes of exposure: The substance can be absorbed into the body by inhalation. Inhalation: High concentrations of this gas can cause an oxygen-deficient environment. Individuals breathing such an atmosphere may experience symptoms which include headaches, ringing in ears, dizziness, drowsiness, unconsciousness, nausea, vomiting and depression of all the senses. The skin of a victim may have a blue colour. Under some circumstances, death may occur. Hydrogen is not expected to cause mutagenicity, or reproductive toxicity. Pre-existing respiratory conditions may be aggravated by overexposure to hydrogen. Inhalation risk: On loss of containment, a harmful concentration of this gas in the air will be reached very quickly.
Physical dangers: The gas mixes well with air, explosive mixtures are easily formed. The gas is lighter than air. Chemical dangers: Heating may cause violent combustion or explosion. Reacts violently with air, oxygen, halogens and strong oxidants causing fire and explosion hazard. Metal catalysts, such as platinum and nickel, greatly enhance these reactions
3.2.4Propane (LPG)
Propane or LPG is one of the product in this plant. It is a colourless gas with a faint petroleum-like door. It is shipp
ed as a liquefied gas under its vapour pressure. For transportation it may be stanched. Contact with the unconfined liquid can cause frostbite by evaporative cooling. Easily ignited. The vapours are heavier than air and a flame can flash back to the source of leak very easily. The leak may be either a liquid or vapour leak. The vapours can asphyxiate by the displacement of air. Under prolonged exposure to fire or heat the containers may rupture violently and rocket.