MEETING PLACE
valves were subsequently reevaluated by both Flowserve and a third-party materials lab . The investigation found the root cause of the leakage to be shrinkage at a level II or better as specified by ASTM E446 , through which micro tunnels created a leak path across the pressure boundary . Simulation was used to accurately predict shrinkage in the areas of interest and the gating was adjusted and analytically verified to remove the shrinkage from the castings .
Control valve selection severe service
Most liquified natural gas ( LNG ) plants utilize a variation of the propane pre-cooled , mixed refrigerant liquefaction process , which utilizes propane refrigerant to chill the feed gas and a mixed refrigerant to achieve liquefaction and sub-cooling . A cascade liquefaction process typically utilizes three pure-component refrigerant loops : propane , ethylene , and methane . Feed gas is precooled as it passes through the propane chiller before undergoing liquefaction and sub-cooling through ethylene and methane cold boxes . The Joule-Thomson effect is leveraged throughout all the primary liquefaction processes to achieve cooling of the feed gas and the refrigerant streams . It is used to achieve cooling of liquids , gases , or multi-phase fluids . Traditionally , this effect has been regulated by a control valve that reduces the pressure of the fluid significantly and induces the desired cooling . Because of the elevated pressure drop , control valves in this service can experience excessive 15 per cent N2 outgassing , high noise levels if not specified and designed correctly .
Highly responsive
These control valves must also operate reliably at very low process temperatures , and they must be capable of precise throttling down to full cryogenic temperatures . In some facilities , expanders are utilized to facilitate Joule-Thomson cooling , while also recovering energy from the fluid to improve overall process efficiency . Expanders are used in both gas and liquid applications
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( commonly referred to as hydraulic turbines in liquid applications ). Regardless of the fluid , expander bypass valves are installed in parallel with expanders to ensure process availability . In instances when the expander is required to go offline , the bypass valve is opened to facilitate Joule-Thomson cooling of the process stream and allow the unit to continue operating in the absence of the expander . The bypass valve must be highly responsive and reliable to ensure process availability . Controllability with special dynamic performance complying with Main Cryogenic Heat Exchanger controller is crucial to improve LNG throughput of the plant . It is also commonly subjected to a
Green hydrogen , designed to be a carrier for renewable energy , is the talk of the town . Hydrogen has the characteristics of high combustion calorific value with abundant resources on earth , and the final emission product is water , which is one of the cleanest energy sources in the world .”
large pressure differential , which creates the potential for significant noise levels in gas applications and flashing in liquid applications .
Selecting the best option
The presentation , given by Emerson , will discuss these specific challenges in detail , then follows with a discussion of valve designs specifically engineered to excel in this type of LNG service . These and other critical design details are discussed to help end-users choose the best option for their specific LNG application . The following aspects are of importance . First , to achieve stable control . Precise throttling control is required to maintain
a stable flow of refrigerant to chillers and cold boxes . Secondly , to reduce maintenance . Balance seal materials must be carefully selected to enhance cycle life . Noise reduction is needed to keep levels below 40 decibels . Furthermore , efficiency , for example by eliminating bypass flow around the expander during normal operation using balance seal and seat ring technologies to provide full shutoff in compliance with cryogenic test . But not least , selecting the correct expanded outlet design to allow for flashing in liquid applications , and in the downstream expansion of lighter hydrocarbon constituents .
Special control requirements
Decarbonisation is the trend to stay as governments and companies strive to reduce their CO2 footprint in order to meet the Paris agreement objectives . There are various ways to reduce CO2 emissions , such as Capture Capture and Storage , biomass energy , nuclear energy and green hydrogen to mention a few .
Download the Advance Conference Program for an overview of the 12th International Valve Conference & Expo .
Valve World Expo & Conference 2022
12 th International Valve Conference & Expo
29 November - 1 December 2022 | Messe Düsseldorf , Germany
Advance Conference Program
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