Hydrocarbon Processing Issue 04 | Page 10

EXPERT FOCUS OXYGEN ANALYSIS IN ETHYLENE OXIDE PRODUCTION FLARE STACK EMISSIONS Ethylene oxide (C 2 H 4 O) is a versatile chemical building block used in the manufacture of many products including glycol-based antifreeze, synthetic clothing fibers, foam rubber, detergents, paint, various modern plastics, and as an important sterilizing agent. Reliable oxygen (O 2 ) monitoring is essential for safety and efficiency in the C 2 H 4 O production process. A flare stack is one of the most important safety mechanisms in industrial plants, burning off flammable gases released by pressure relief valves, thereby avoiding unplanned pressure build-ups and disposing of excess gases. VOTING SYSTEM LOCATION OXYGEN REACTOR 1 REACTOR 2 REACTOR 3 The desired C 2 H 4 O intermediate is produced by feeding the two primary feedstock materials, in minor amounts, to a reactor maintained between 145 and 365psig (260psig is typical) and 200-300 o C (392-572 o F). A suitable catalyst, usually silver oxide, is also used. ETHYLENE POTASSIUM CARBONATE REACTOR 4 CARBON DIOXIDE REMOVAL POTASSIUM BICARBONATE Most C 2 H 4 O is commercially produced by the direct oxidation of ethylene (C 2 H 4 ), using a mix of air and pure O 2 . The exothermic nature of the process means that safety is of paramount concern. Ethylene is a very reactive gas, and readily burns to form carbon dioxide (CO 2 ) and water vapor (H 2 O). If not carefully handled, it does this explosively. GAS COMPRESSOR MIX NOZZLE The analyzer’s Paramagnetic sensor responds specifically to changes in gaseous O 2 levels, while the only sample preparation components required are a filter and a pressure reducing station. The non-depleting Paramagnetic cell should never need replacement, and requires only occasional calibration checks, especially when used in safety shutdown duties. It provides proven, A flare stack is an elevated vertical stack or chimney, and steam-assisted flaring of the associated gas occurs at the top of this structure to control the combustion efficiency (CE). Combustion of the vent gas is a much more environmentally responsible process than simply releasing the gas into the air. For example, if methane is burnt, the products are carbon dioxide (CO 2 ) and water, which are much less harmful than releasing methane itself. Flares are active all the time, with a continuous release of gas being burned off at the flare stack. When this mix of steam and hydrocarbons is correct, the flame is clean and no harmful emissions escape into the atmosphere. SERVOMEX ANALYZER SOLUTIONS FOR THE FLARE STACK PROCESS ETHYLENE OXIDE ABSORBER SERVOTOUGH OxyExact 2200 Using air as the oxidant means that the inherently high proportion of nitrogen acts as a major diluent, keeping components outside of the explosive limit. It is essential to keep O 2 levels below 8% to avoid formation of an explosive mixture. However, it must be above 5%, otherwise the C 2 H 4 O yield becomes uneconomic. FAT WATER EO RECOVERY When the process uses pure O 2 , the desirable operating range is very different and much narrower, typically 0.8% O 2 with a variation of ±0.1% O 2 . Integrated Systems (SIS) required for safe operation and production. The OxyExact 2200 can be used to measure the quality of the O 2 feedstock. More critically, however, it is employed in a voting system – either one out of two or two out of three – to measure O 2 on the inlet and each outlet of the reactors. The OxyExact 2200 is SIL 2 hardware compliant to make integration into such safety systems simple. Ethylene oxide reactors are monitored on a frequent basis, to detect gases other than O 2 in order to assess conversion efficiency and unwanted waste compound build-up. Signals from these analyzers can be continuously fed to the OxyExact 2200s to modify the O 2 analyzer output as required. This produces an online O 2 reading to better than ±0.02% accuracy. These safety critical measurements are a fundamental element of the Safety SERVOTOUGH SpectraScan 2400 SERVOMEX H2scan SERVOTOUGH Oxy 1900 A Tunable Filter Infrared absorption on-line gas analysis platform ideal for continuous flow-through monitoring of light hydrocarbons. Non-depleting thin film technology providing a robust and reliable direct measurement of hydrogen. Award-winning, safety-enhanced digital O 2 analyzer designed to deliver accurate Paramagnetic measurements in challenging applications. SERVOTOUGH OxyExact 2200 SERVOTOUGH Laser 3 Plus Process In either case, the reactions are optimized by keeping the O 2 level as high as possible to obtain the best yield, while remaining within safe limits. long-term stability, reliability, and a fast speed of response. Want expert support customized to your process? Contact us now: servomex.expert/contact-us P10 They are also used for the planned combustion of gases over short periods during plant start-ups or shut-downs, both full and partial, and are employed by petrochemical facilities, natural gas processing facilities, chemical plants and refineries. LEAN WATER A PARAMAGNETIC O 2 ANALYSIS SOLUTION The SERVOTOUGH OxyExact 2200 gas analyzer is ideal for monitoring these processes. SERVOMEX’S BENCHMARK-LEVEL ANALYSIS OF HYDROCARBON COMPONENTS AND OXYGEN MIXTURES ACROSS THE FLARE STACK PROCESS See our analyzers across the process OVERLEAF Hazardous area process O 2 analyzer using high-precision Paramagnetic sensing technology for ultimate monitoring performance. Highly-compact Tunable Diode Laser gas monitor for fast and accurate O 2 measurements in in-situ cross-stack applications. P11