AIGA 056 14 Safe Practices Guide For Cryogenic Air .
SAFE PRACTICES GUIDEFOR CRYOGENICAIR SEPARATION PLANTSAIGA 056/14Based on CGA P-8 -2013Fifth EditionAsia Industrial Gases Association3 HarbourFront Place, #09-04 HarbourFront Tower 2, Singapore 099254Tel : 65 62760160 Internet : http://www.asiaiga.org
AIGA 056/14SAFE STARTUP ANDSHUTDOWN PRACTICESFOR STEAM REFORMERSDisclaimerAll publications of AIGA or bearing AIGA’s name contain information, including Codes of Practice, safety procedures and othertechnical information that were obtained from sources believed by AIGA to be reliable and/ or based on technical information andexperience currently available from members of AIGA and others at the date of the publication. As such, we do not make anyrepresentation or warranty nor accept any liability as to the accuracy, completeness or correctness of the information contained inthese publications.While AIGA recommends that its members refer to or use its publications, such reference to or use thereof by its members or thirdparties is purely voluntary and not binding.AIGA or its members make no guarantee of the results and assume no liability or responsibility in connection with the reference to oruse of information or suggestions contained in AIGA’s publications.AIGA has no control whatsoever as regards, performance or non performance, misinterpretation, proper or improper use of anyinformation or suggestions contained in AIGA’s publications by any person or entity (including AIGA members) and AIGA expresslydisclaims any liability in connection thereto.AIGA’s publications are subject to periodic review and users are cautioned to obtain the latest edition.NOTE—Technical changes from the previous edition are underlined. Reproduced with permission from Compressed Gas Association. All rights reserved.ASIA INDUSTRIAL GASES ASSOCIATION3 HarbourFront Place #09-04 HarbourFront Tower 2 Singapore 099254Internet: http://www.asiaiga.org
AIGA 056/14ContentsPAGE iiiPage1Introduction. 12Scope . 13Typical ASU features. 14Definitions. 35Health hazards . 85.1Cryogenic liquids . 85.2Gas products . 85.3Asphyxiation . 85.4Oxygen hazards . 95.5Protective clothing and personal protective equipment . 106General plant considerations. 106.1Site selection . 106.2Safety factors in plant layouts . 106.3Materials of construction. 116.4Insulation—other than coldbox . 126.5Cleaning . 126.6Electrical requirements . 126.7Noise . 137Intake air quality . 137.1Contaminants . 137.2Reactive contaminants that concentrate in oxygen . 147.3Reactive contaminants that concentrate in nitrogen . 157.4Plugging components . 157.5Haze and smoke from fires. 167.6Contaminant sources. 167.7Identification of contaminants . 177.8Location of air intake . 177.9Monitoring intake air . 178Compressors . 178.1Axial compressors . 178.2Centrifugal compressors. 188.3Other dynamic compressor considerations . 188.4Reciprocating compressors . 198.5Diaphragm compressors . 218.6Rotary positive displacement compressors . 218.7Refrigerant gas compressors . 218.8Screw compressors . 218.9Lubrication systems . 218.10 Coolers and separators . 238.11 Suction filters or screens . 238.12 Special considerations for oxygen service . 238.13 Operating and maintenance procedures . 249Air contaminant removal . 249.1Removal methods. 249.2Contaminant removal stages . 259.3Prepurification unit operation . 279.4REVEX operation . 299.5Supplemental mechanical chillers . 319.6Caustic scrubbers . 32
AIGA 056/14PAGE iv10 Expanders . 3210.1 Loss of loading and overspeed. 3210.2 Oil contamination of the process . 3310.3 Abnormally low temperatures . 3410.4 Solids in gas stream . 3410.5 Loss of lubrication. 3410.6 Abnormal bearing temperature . 3510.7 Abnormal vibration. 3510.8 Abnormal speed . 3510.9 Critical speed . 3510.10 Fouling of expander with ice or carbon dioxide . 3510.11 Startup and shutdown. 3610.12 Operating and maintenance procedures . 3611 Cryogenic pumps . 3611.1 General . 3611.2 Types of pumps . 3711.3 Materials of construction. 3711.4 Pump system design . 3711.5 Special considerations for oxygen service . 3811.6 Pump motor . 3811.7 Pump operation . 3911.8 Operating and maintenance procedures . 3912 Coldbox . 3912.1 Removing particulate material . 4012.2 Cryogenic adsorbers . 4012.3 Liquid levels . 4112.4 Monitoring contaminants . 4212.5 Argon separation and purification . 4312.6 Noncondensable purge . 4412.7 Coldbox cleaning . 4412.8 Safe holding time for LOX . 4412.9 Liquefaction of air in the main heat exchanger . 4412.10 Process upsets . 4413 Control systems . 4613.1 Instrumented systems functions . 4613.2 Critical safety systems . 4613.3 Operational safety systems . 4713.4 Routine plant operation control systems . 4713.5 Unattended or partially attended operation . 4813.6 Remote operation . 4813.7 Additional considerations for computer-based control systems . 4813.8 Additional considerations for failsafe systems . 4913.9 Alarm system . 4913.10 Regulatory considerations . 5014 Product handling equipment . 5014.1 Liquid storage . 5014.2 High pressure gas storage vessels . 5114.3 Liquid vaporizers . 5215 Cooling systems . 5216 Plant piping. 5316.1 General design considerations for plant piping . 5316.2 General design considerations for check valves . 53
AIGA 056/1416.316.416.516.616.716.816.9PAGE vOxygen piping hazards . 53Pressure relief devices . 53Cryogenic piping . 54Dead legs . 55Carbon steel piping. 55Venting . 55Product delivery . 5617 Shutdown procedures . 5617.1 Coldbox shutdown . 5617.2 Liquid and gas disposal . 5617.3 Plant derime . 5718 Repair and inspection. 5818.1 General maintenance considerations . 5818.2 Supervisory control . 5818.3 Special construction and repair considerations . 5818.4 Coldbox hazards. 5818.5 Hazards of working in oxygen-enriched or oxygen-deficient atmospheres . 5918.6 Cleaning . 5919 Operations and training . 6019.1 Operating procedures . 6019.2 Commissioning procedures . 6019.3 Emergency procedures . 6019.4 Management of change . 6019.5 Personnel training. 6120 References . 61FigureFigure 1—Representative air separation plant flow diagram . 2TablesTable 1—Effects at various oxygen breathing levels . 9Table 2—Plugging, reactive, and corrosive contaminants in air . 13Table 3 Typical default air quality design basis . 14Table 4—Typical removal in PPU process . 26Table 5—Typical removal in REVEX process . 26Table 6—Cryogenic adsorber names . 40
AIGA 056/141PAGE 1IntroductionAs part of a programme of harmonization of industry standards, the Asia Industrial Gases Association (AIGA)has adopted the Compressed Gas Association (CGA) standard P-8, 5th edition.This international harmonized document is intended for use and application by all IHC member associations.The AIGA edition has the same technical content as the CGA edition, however, there are editorial changesprimarily in formatting, units used and spelling. Also, references to regional regulatory requirements havereplaced US regulations where appropriate.This publication provides guidance on the safe operation of cryogenic air separation plants. It is based on theexperience of CGA member companies that operate cryogenic air separation units (ASUs).Industrial cryogenic air separation has some potential hazards that must be recognized and addressed. Thehazards include electricity, gases under pressure, very low temperatures, the ability of oxygen to acceleratecombustion, and the asphyxiant properties of nitrogen, argon, and the rare gases [1].1Cryogenic air separation technology is not static; it has been progressing for decades and will continue to do sobecause of engineering development efforts. Consequently, plant process cycles, equipment, and operatingconditions can be and are of varying kinds. Therefore, this publication must include generalized statements andrecommendations on matters for which there is a diversity of opinion or practice. Users of this guide shouldrecognize that it is presented with the understanding that it cannot take the place of sound engineeringjudgment, training, and experience. It does not constitute, and should not be construed to be, a code of rules orregulations.2ScopeThis publication serves the interest of those associated or concerned with air separation plant operations andapplies to safety in the design, location, construction, installation, operation, and maintenance of cryogenic airseparation plants. Emphasis is placed on equipment and operational and maintenance features that arepeculiar to cryogenic air separation processes. Limited coverage is given to plant equipment such as aircompressors, which are used in other industrial applications and for which safe practices in design, installation,and use have already been established elsewhere. Further, as this publication is not intended as a universalsafe practice manual for specific design and safety features, it is also important to refer to the operatingmanuals of the equipment suppliers.The following are excluded from this publication:–cylinder filling facilities;–rare gas purification systems; and–product transmission piping outside the plant boundaries.3Typical ASU featuresCryogenic ASUs have these features:–air compression;–air contaminant removal;–heat exchange;–distillation; and1References are shown by bracketed numbers and are listed in order of appearance in the reference section.
AIGA 056/14–PAGE 2expansion (or other refrigeration sources).Figure 1 is an example of a flow diagram for separating air by cryogenic distillation producing oxygen, nitrogen,and argon products. Air is compressed in the main air compressor (MAC) to between 4 atm and 10 atm. It isthen cooled to ambient temperature. Trace contaminants such as water, carbon dioxide, and heavyhydrocarbons are removed using systems such as a prepurification unit (PPU) or a reversing heat exchanger(REVEX). The main heat exchanger cools the air to near its liquefaction temperature before entering the highpressure (HP) distillation column. Some of the air is reduced in pressure in the expander to producerefrigeration, overcoming heat leak and process inefficiencies. Gaseous nitrogen from the top of the HP columnis condensed by the reboiler and the liquid used to reflux both columns. Condensing nitrogen releases heat tovaporize liquid oxygen (LOX) in the low pressure (LP) column sump, which is then taken as product or sent asstripping gas to the LP column.Nitrogen productGas storageNitrogencompressorOxygen productGas tChillerNitrogenliquefier unitLo ExpanderWastechilltowerPumpsRefluxvalvesAdsorbers Gaseousoxygen (alt)DirectcontactaftercoolersLiquidoxygen idproductProduct liquidoxygen re 1—Representative air separation plant flow diagramOxygen has the highest boiling point of the three main components and is taken from the bottom of the LPcolumn. Nitrogen is taken from the top of the LP or HP columns. An argon-rich stream can be withdrawn fromthe middle of the LP column and refined to a pure product in other distillation columns. The product streams arewarmed to ambient temperature against incoming air in the main heat exchanger to recover the refrigeration. Itis also possible to remove the products from the distillation system as liquid, if sufficient refrigeration isavailable. Producing large quantities of liquid products requires extra refrigeration, often supplied by a nitrogenliquefier unit. Liquid may be stored for pipeline backup or merchant sales.There are two typical ASU configurations for producing pressurized oxygen. In the gas plant configuration (alsocalled gaseous oxygen [GOX] process or classic gas process), oxygen is taken as a vapor from the bottom ofthe LP column and warmed by incoming air in the main heat exchanger. If an HP oxygen product is needed, itis compressed to the required pressure. A LOX purge stream is taken from the sump of the LP column toprevent the trace contaminants from concentrating above allowable safety limits. In the pumped LOX process(also known as the internal compression process), oxygen is taken as a liquid from the LP column sump,pumped to the required pressure, and vaporized in the main exchanger against HP air from the booster aircompressor. The pumped oxygen stream removes trace contaminants from the LP column sump, so aseparate LOX purge stream from the LP column sump may be eliminated.
AIGA 056/14PAGE 3There are many other configurations of the ASU process that are specifically tailored for different productsmixes and customer needs. A detailed discussion of these is beyond the scope of this publication.44.1DefinitionsPublication terminology4.1.1ShallIndicates that the procedure is mandatory. It is used wherever the criterion for conformance to specificrecommendations allows no deviation.4.1.2ShouldIndicates that a procedure is recommended.4.1.3MayIndicates that the procedure is optional.4.1.4CanIndicates a possibility or ability.4.2Acid gasAir contaminants such as chlorine, NOx, and SOx that can form acid when combined with water.NOTE—Acid gases can create corrosive conditions in brazed aluminum heat exchangers (BAHXs) and other equipment.4.3AdsorptionPurification process in which one or more components from a gas or liquid is preferentially adsorbed onto asolid desiccant or other adsorbent.NOTE—Typical adsorbents include:–Molecular sieve—granular adsorbent (typically 13X) used in air PPUs for water, carbon dioxide, and hydrocarbonremoval;–Alumina—granular adsorbent typically used in air PPUs or dryers for water removal; and–Silica gel—granular adsorbent typically used in cryogenic adsorbers for carbon dioxide and hydrocarbon removal.4.4AsphyxiationTo become unconscious or die from lack of oxygen.4.5Blow outMaintenance or commissioning procedure in which a fluid, typically dry air, is blown through piping andequipment to eliminate dirt, moisture, or other contaminants.4.6Brazed aluminum heat exchanger (BAHX)An aluminum plate and fin heat exchanger consisting of corrugated sheets separated by parting sheets and anouter frame consisting of bars with openings for the inlets and outlets of fluids, equipped with headers andnozzles to connect to external piping.NOTE—The approximate thickness of the corrugated sheets is 0.2 mm to 0.5 mm, while the parting sheets havethicknesses between 1.0 mm and 2.4 mm. More information is provided in AIGA 057, Safe Use of Brazed Aluminum HeatExchangers for Producing Pressurized Oxygen [2].4.7CasingOutside walls of a coldbox or cryogen
SAFE PRACTICES GUIDE FOR CRYOGENIC AIR SEPARATION PLANTS AIGA 056/14 Based on CGA P-8 -2013 Fifth Edition Asia Industrial Gases Association 3 HarbourFront Place, #09-04 HarbourFront Tower 2, Singapore 099254
NASAD program administrators, AIGA educator leaders (including current and lapsed members, as well as AIGA conference attendees), and educa-tional leader respondents to AIGA’s 2006 Design Educators Salary Survey. Only unduplicated emailable individuals were invited. Data was collected via an adaptive web–based survey from May 2 to June 19,
AIGA student groups offer aspiring professionals the opportunity to get involved, create community, and build leadership skills. There are more than 200 AIGA student groups at college campuses across the country. AIGA encourages the formation of student groups and is committed to developing these groups as a way of encouraging students to take the
AIGA - Austin Chapter 815-A Brazos St., PMB 549 Austin, TX 78701 www.aigaaustin.org Mission and Goals AIGA's mission is to advance designing as a professional craft, strategic tool and vital cultural force. AIGA is the premier place for design - to discover it, discuss it, understand it, appreciate it, be inspired by it.
AIGA Design Educators Salary Survey 2008 www.aiga.org Compensation overview poSition title All full-time design educators saLarY/WaGes saLarY/WaGe comparIson addItIonaL casH suppLementaL Income totaL compensatIon respondents 25tH% medIan 75tH% 25tH% medI
Aiga Ārste-Avotiņa Managing Partner Amrop Riga, Latvia T 371 29 236 717 F 371 67 210 422 E aiga.arste@amrop.com W www.amrop.lv Aiga has been working in executive search business since 1996, when she joined Amrop International in Latvia as a first local
CODE OF PRACTICE ACETYLENE AIGA 022/13 Revision of AIGA 022/05 Asia Industrial Gases Association 3 HarbourFront Place, #09-04 HarbourFront Tower 2, Singapore 099254
AIGA Aquent Survey of Design Salaries 2008. section Contents introduction Letter from the executive director 2 . Median total cash compensation 2000-2008 11 AIGA design leaders confidence index 14 2008 compEnsation Compensation overview 17 Solo designer 18 Owner, Partner, Principal 20 Creative/Design director 22 Art director 24 Senior .
‘Stars’ can allow a business to be a market leader ‘Problem Child’ products give businesses opportunity to invest ‘Dogs’ should be divested Increased profits can ari se f rom selling different products Newer products can replace thos e at the end of the life cycle A range of pro ducts increases brand awareness Easier to launch new products with larg e existing portfolio 5 Award 1 .
