Thermoacoustic Refrigeration

Nonconventional Methods of Gas Liquefaction

Chemical Engineering Thermodynamics-II Project

Group membersAnum Yousuf KhanArooj FatimaFatima KhalidHiba MujeebImtisal-e-NoorRida Altaf Syed Shahrukh MadniTaibah Jaffery

IntroductionThis presentation elaborates upon some nonconventional methods of gas liquefaction.The most widely used methods are applications of Lindes and Claudes cycle, however over time various variations have brought about improvements in yield and efficiency. Thermoacoustic RefrigerationBy: Syed Shahrukh MadniIntroductionThermoacoustic liquefiers convert gas to liquid using sound waves.

This process relies on Thermoacoustic heat engines, which rely on sound to perform heat exchange.

Thermoacoustic heat engines have almost no moving parts which makes them more reliable.

ComponentsA Thermoacoustic liquefier consists of three heat exchangers a pulse tube refrigerator arranged in a network of piping and filled with pressurized helium.

The only moving part is the helium in the pipes and the only energy expended is the input heat provided.

WorkingIn the engine, one heat exchanger is heated to roughly 700C (1300F), a second heat exchanger is held at ambient temperature, and a third, between the other two, is thermally floating. The input heat sets up a temperature gradient across the heat exchangers, which produces an oscillating pressure wave in the helium gas. This oscillating wave drives the pulse tube refrigerator producing refrigeration power at cryogenic temperaturesApplicationsCurrently, it is only being used for natural gas liquefaction.But it has the scope for being used for the liquefaction of system gases in the industry.It can also be used for mobile liquefaction facilities for offshore oil rigs.Magnetic Liquefactionof Hydrogen gasBy Hiba MujeebImportance of liquefied hydrogenHydrogen energy for a fuel cell society is ever-increasing.Technology for hydrogen infrastructure consists of: preparation transportation storage utilization

It is desired to be in a liquid form for transport efficiency.

11Based on Thermo Siphon MethodLiquefaction principle of magnetic refrigerator based on thermo-siphon method.a method of passive heat exchange based on natural convection, which circulates liquid without the necessity of a mechanical pump.

Thermo siphon: a method of passive heat exchange based on natural convection, which circulates liquid without the necessity of a mechanical pump12Magnetic refrigerationThis method makes use of the magneto caloric effect.This effect causes magnetic materials: to become warm by magnetizing and to cool by demagnetizing the magnetic fieldAn efficient methodCooling cycle closely follows Carnot's cycleIn consideration of these circumstances, a new method of hydrogen liquefaction with a newly developed magnetic refrigerator has been developed.13Process

Properties of magnetic refrigerantsThe magnetic refrigerants are required to have relatively large entropy change at: Liquefaction temperature of hydrogenHydrogen resistance.

Since most metal compounds dont satisfy thelatter condition, we have developed a new ceramic polycrystalline magnetic refrigerant named dysprosiumgadolinium aluminum garnet (DGAG). In the liquefaction experiments,

15AdvantagesIt was found that the condensation efficiency accomplished 90% CarnotThe liquefaction power at atmospheric pressure was 25.3 W

Collins Helium Liquefaction System

By Arooj FatimaChallenge of Helium LiquefactionHelium is one of the most difficult (i.e., expensive) gases to liquefy because the maximum inversion temperature for helium is only (-229C). Before the Collins Helium Cryostat, every low-temperature laboratory had to build its own low-temperature apparatus using liquid hydrogen, a devious and dangerous material.Because every device was unique and expensive, there were only a few cryogenic laboratories throughout the worldPrior to 1946, low-temperature research laboratories generally designed and constructed their own liquefiers some of which used liquid hydrogen as a pre-coolant18IntroductionIn 1946, Dr. Collins and his colleagues at MIT built what became know as the Collins Helium Cryostat. This was a modification of the basic Claude liquefier. The device provided for the first time reliable, relatively in expensive and adequate supplies of liquid helium. This makes it possible to produce liquid helium without the aid of external coolants. Professor Collins' achievement revolutionized cryogenics. Its commercial introduction made helium liquefaction accessible and economic.ProcessHelium gas is compressed to 1275 kPa and passed through the first heat exchanger. After leaving the first heat exchanger, a portion (about 16%) of the stream is bypassed through the first expander. The gas temperature at the expander inlet is between (248 to 229C).The remainder of the helium gas flows through the second heat exchanger, and leaves the exchanger at about (252C). A fraction (about 56%) of this stream is by passed through a second expander after the helium has passed through a third exchangerProcess The remaining flow passes through two more exchangers and expands through the J-T valve, in which a portion of the stream is liquefied.The vapor formed is returned to provide cooling for the incoming gas stream.Liquid nitrogen pre-cooling is usually used to improve the liquid yield and offset some of the heat exchangers inefficiencies.

Liquefin: An Innovative Process

By Imtisal-e-Noor

Introduction

Process is developed by IFP and Axens.Uses simple and reliable technologies.Easy to operate .Able to cope with isolated or harsh climate regions.With Liquefin, very high capacities can be reached with a simple scheme and standard compressors. Axens is an international provider of advanced technologies, catalysts, adsorbents and services, with a global reputation for basic engineering design excellence. The main scope of Axens' business is focused on the conversion of oil, coal, natural gas and biomass to clean fuels as well as the production and purification of major petrochemical intermediates.The French Institute of Petroleum (in French: Institut franais du ptrole, IFP) is a public research organisation in France founded in 1944 as Institute of Oil, Fuels and Lubricants (Institut du ptrole, des carburants et des lubrifiants).IFP and Axens have developed the Liquefin process with the aim of producing an LNG cheaper than with any other process, at good conditions of reliability and safety, and more friendly to environment. The process uses simple and reliable technologies, easy to operate and able to cope with isolated or harsh climate regions. With Liquefin, very high capacities can be reached with a simple scheme and standard compressors. Beyond an initial success of curiosity, most of the Majors have now closely reviewed the process in conjunction with engineering contractors. They have also thoroughly compared Liquefin with its competitors. These Majors consider Liquefin as a potential alternative for their future developments: one Front End Engineering Design is now completed and confirm all the expectations in term of efficiency and cost attractiveness

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PROCESS DESCRIPTION

Pre refrigeration cycle.Pre-refrigeration achieved by using a mixed refrigerant.The temperature is decreased down to a range of -50C to-80C.Mixed refrigerant completely condensed, no phase separation is necessary moreover the quantity of cryogenic refrigerant is substantially reducedAs the result, the overall required power is decreased. Significant AdvantageThe possibility to use directly the full power provided by the selected drivers For example, Liquefin can adapt to a half/half power balance between the two cycles for two identical gas turbines, But also to a one-third/two third power balance in case of three identical gas turbines.

Unconventional features of liquefin:No integrated cascadeA balanced powerA compact heat-exchange lineLiquid turbinesReduction of air condenser sizeKapitza Method of Helium LiquefactionBy Fatima KhalidImportance of Liquefied HeliumHelium as a super fluid shows characteristics such as heat conduction and zero viscosity.Mechanism of MethodCompression in compression pumpCooling in coilsCollected after passing through nozzleCooling by Joule -Thomson Effect

Claudes ProcessKapitzas method is a modification of the Claudes Process.Gas Liquefaction Using Supersonic NozzleBy Taibah JafferyIntroductionA new technology relating to cryogenic engineering

Based on the adiabatic cooling of swirling gas flow in a supersonic nozzle

Enthalpy converted to kinetic energy which is later reused increase pressure

WorkingReduction of stream static pressure and temperature by adiabatic gas expansion to supersonic velocityLaval nozzle accelerates the gas to supersonic speed by forming subsonic, critical and supersonic zonesCondensation of gas with formation of droplets occurs due to the resulting cryogenic temperatureFurther condensation in working section having a wallCentrifugal effects of swirl velocity separate droplets from the unliquefied gasInlet diameter > 5(throat dia)Convergent section length >= throat diameter

DesignPrechamber Gas flow whirling meansSubsonic or supersonic nozzleWorking segment

Liquid phase extracting meansSubsonic diffuser or the combination of a supersonic and the subsonic diffuser

Axially Positioned in Series are:Applications and AdvantagesLiquefaction of natural gasSeparation of one or more gases from a gas mixturePilot test facilities have shown 10-20% lesser compressor power requirements than the Joule-Thomson valve and turbo-expander

Industrial Gas Liquefaction with Azeotropic Fluid ForecoolingBy Anum KhanNeed and Advantage

efficient when refrigeration required over a large temperature range such as ambient to cryogenicprovide a less complicated multiple circuit arrangement whereby industrial gas may undergo large temperature changesoperates with a relatively lower power input requirement than available multiple refridgeration circuits

How it works?

Compressing, followed by condensing a gaseous azeotropic mixture Expanding a first portion of the condensed azeotropic mixture to generate refrigeration, and vaporizing it Sub cooling a second portion of the condensed azeotropic mixture and expanding the subcooled azeotropic mixture second portion to generate high level refrigeration.

Vaporizing the high level refrigeration bearing azeotropic mixture second portion Expanding the cooled compressed refrigerant fluid to generate low level refrigerationWarming the low level refrigeration bearing refrigerant fluidLiquefaction using Fischer-Tropsch processBy Rida Altaf

The natural gas flowing in through line 1 is cooled, then expanded in turbine T1. The liquid at the bottom of drum D2 is the liquefied natural gas. The gas at the top of drum D2 is compressed by compressor K1, then fed into the treating plant using a Fischer-Tropsch process to convert the natural gas to natural gas liquid.Process StepsDistillationLiquefactionExpandingCompressingExpansionConversion by fisher tropsch processTheFischerTropsch process, or FischerTropsch synthesis, is a collection ofchemical reactionsthat converts a mixture ofcarbon monoxideandhydrogeninto liquidhydrocarbons.

Why we need new methods?

The liquefaction of industrial gas is a power intensive operation. Typically the industrial gas is liquefied by indirect heat exchange with a refrigerant. Such a system, while working well for providing refrigeration over a relatively small temperature range from ambient, is not as efficient when refrigeration over a large temperature range, such as from ambient to a cryogenic temperature, is required.ConclusionBasically the following factors determine which method is suitable:specific conditionseconomic situation space limitationsdegree of performance required Most of these methods have been designed to cater a specific need that is not met by conventional methods