An overpressure event may occur from runaway reactions, inadvertent reactions, thermal expansions and unintended temperature changes to media. Fike’s comprehensive selection of rupture discs come in all shapes and sizes, corrosive-resistant materials, burst pressures, burst temperatures and operating ratios; they can be used to protect pressure relief valves; and they can be custom engineered to fit nearly any special request. Our pressure relief solutions may be used to protect nearly any equipment within a chemical processing facility from overpressure, but some of the most common applications include the following:
Products such as oxygen, argon nitrogen and hydrogen are often stored as liquefied gases at -150° C or lower within cryogenic vessels. Not only are rupture discs recommended to quickly alleviate a rapid increase in pressure, but they may also be used in concert with thermal relief valves, spring safety valves and pilot-operated safety valves to prevent them from freezing.
Large Chemical Reactors
Exothermic runaway reactions often result in overpressure, potentially more than the vessel is designed to withstand. And in batch processes, the frequent filling and emptying, and the polymerization process itself, creates fluctuating pressures and temperatures. Therefore, rupture discs equipped with high-cycling capabilities, burst pressures and burst temperatures are required to combat against oscillating conditions. Fike’s Axius and Atlas rupture discs have unmatched service life in cyclic applications.
Designed to transfer heat from one liquid or gas to another, shell and tube heat exchangers are susceptible to overpressure. The substance or media within the tubes is often at a higher pressure compared to the shell. Damage to those tubes can occur over time, caused by corrosion, erosion or vibrations, resulting in tube ruptures and therefore a build-up of pressure within the shell. Tube leakage may also result from a chemical reaction, increasing the chances of an exothermic reaction within a resulting rapid rise in pressure. Rupture discs protect against these potential hazards, and may need to be compatible with both liquid and vapor media, high and low burst pressures, two-phase flow conditions and different types of holders.
Separators are used to separate any combinations of solid, liquid or gas mixtures such as crude oil from natural gas or water droplets from steam. Closed separators are at risk of overpressure due to potential blockages, processing errors and expansion from heating or exothermic reactions. Choosing the appropriate rupture disc based on media, burst pressures and burst temperatures protect separators from overpressure events. High rupture disc operating ratios and cycling capabilities equate to longer service life within separators.
With its varying processed dusts in confined spaces and of fluctuating temperatures, chemical refineries are one of the most susceptible industries of combustible dust explosions. Fike offers comprehensive explosion protection solutions custom fit for your facility to protect people, equipment and downtime.
Dust collectors are found in most processing industries, as they reduce the amount of dust and pollution in the air, protect against dust-build up around sensitive machinery and minimize waste. A facility’s finest dust is often found within these dust collectors, meaning a rogue spark or flame can cause a violent deflagration. Connecting pipes and ducts may act as fuses into other areas of the facility, causing secondary downstream explosions. Explosion vents are often the most cost-effective solution to protect dust collectors; however, indoor processes may not allow for the safe escape of harmful gases. In these scenarios, chemical suppressant systems are required to protect the vessel and isolate the explosion from downstream equipment.
Using centrifugal force, cyclones separate large volumes of dust and collect it at its base—a common source for a dust explosion hazard. However, even more likely is a dust explosion originating from interconnected equipment, such as a dust collector, creating a secondary explosion and igniting the dust found within the base of the cyclone. Explosion vents may be placed on the top of cyclones or connecting pipes and ducts to redirect the resulting pressure and flame. Isolation valves and chemical suppression provide additional, often necessary, protection to ensure quick mitigation within the vessel from which the deflagration originated.
Often positioned upstream from cyclones and dust collectors, flash dryers remove moisture from dust until particles are fine enough to rise into the air stream. The flash drying process does, however, create a combustible dust hazard, as it propels dry particles into a dust cloud. Therefore, the combustion risk is often located toward the top of the flash dryer, where explosions vents may be installed to protect against deflagrations within the flash dryer or from other connecting equipment. Isolation valves and chemical suppressants also may be recommended to protect accompanying vessels from deflagrations originating within flash dryers, and vice versa.
In chemical industries, belt and chain conveyors may be used to move bulk materials throughout a facility. These materials may be dry and dusty, and they may be moved within a closed system to protect from contamination or to keep the dust from transferring throughout the facility. Malfunctioning conveyor parts have been proven to create hot spots. These hot spots may ignite the dust into a dust cloud or move smoldering clusters of product to other downstream combustible dust hazards. Inlet and outlet chutes, and every few meters of the conveyor, must be protected with explosion vents. Valves or suppression are also recommended to isolate the explosion to the conveyor.
Fire Protection in the Chemical Industry
Because of the amount of combustible dust found in many chemical processing facilities, even a small ember can result in devastating consequences. Fike’s fast-acting fire detection and suppression solutions quickly mitigate fires in their incipient stages before culminating in catastrophe.
Machinery spaces often feature a variety of processes and pumps that use Class B flammable liquids. Equipment found in machinery spaces may include internal combustion engines fueled by gasoline or diesel fuel; electrostatic coating, dipping or cleaning processes; and pressurized containers for hydraulic-pumping equipment. In combination with heat detection and video detection and analytics, watermist has been proven to effectively suppress fires caused by pools of fuel leakage, fuel sprays and potential Class A involvement caused by ignition of fuel-soaked materials.
Removing dust and impurities from the system, dust collectors are an essential component of most chemical processing facilities. However, statistically most explosions occur in dust collectors because they concentrate the smallest particles. The newest combustible dust standard, NFPA 652 regulates that all dust collectors are protected with fire suppression systems to protect against combustible dust explosions and other fire hazards. CO2 systems are recommended for non-metallic flammable dusts, and Argon-filled PROINERT systems are recommended for metal dust hazards—both used in concert with a heat detector.
Flammable Liquid Storage
Flammable liquid storage areas are often segregated from processing areas due to their volatile substances and special handling procedures. Static electricity, leakage of flammable material or operator error can all lead to a fire in a liquid storage room; thus, effective fire protection for these spaces is required. Each type of fire suppressant has proven effective: inert gas may be used to improve flow distance from cylinder bank; watermist may be used for non-hydrocarbon flammable liquids; CO2 may be used for unoccupied spaces; and various chemical agents may be used depending on environmental friendliness or cost-effectiveness. Ultra-violet infrared detectors or video detection and analytics are ideal for detecting fires in the earliest of stages.
Diesel engines provide backup power in the event of a loss of primary power in chemical facilities. However, diesel engines’ reliability may be challenged from fire hazards presented by flammable hydraulic fluids, fuel and lubricants, which in the presence of high temperatures, can lead to pool and spray fires.
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Metal Dust Explosion Protection – What Chemical Plant Managers Need to Know
Dust explosions are a known hazard in chemical processing, and metal dusts pose a unique danger due to the handling, processing and storage that can create combustible dust clouds and dust accumulations. Metal dusts are unique from organic fuels because they typically require a lower amount of energy to ignite and have higher energetic content.