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Maintenance
YouTube - Car Maintenance and Repair Tips : How to Check Engine Coolant Levels in a Car
www.youtube.com - Learn how to check car engine coolant levels with expert car tips in this free online automotive repair video clip.Expert: William MyersContact: www.austinsu...
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Visit : 101 , Submited 20 Oct 2009 03:19
YouTube - Car Maintenance and Repair Tips : How to Check Your Transmission Fluid in a Vehicle
www.youtube.com - Learn how to check your car s transmission fluid with expert car tips in this free online automotive repair video clip.Expert: William MyersContact: www.aust...
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Visit : 97 , Submited 20 Oct 2009 03:19
Making Linker for Friendster [update Februari 2009]
www.aleusia.com - Ini adalah point utama agar semua kode-kode tambahan untuk modifikasi bisa bekerja dengan baik. Make Linker for Friendster still working, linker friendster, update linker friendster, maintenance friendster, patch update, patch linker, tweak friendster, hack friendster, linker terbaru, friendstertalk, new linker, linker java, ripway, aleusia
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Visit : 13 , Submited 06 Mar 2009 17:31
Firefox Loncat dari 3.1 ke Versi 3.5
tekno.kompas.com - JAKARTA, Kompas.com – Sudah mencobai RC2 dari Firefox 3.1 Beta 3? Berukuran 17MB dan stabil berjalan di Mac dan Windows, rilis Beta 3 boleh-boleh saja Anda gunakan untuk test drive teknologi terbaru Mozilla. Beta 3 ini kebanyakan merupakan rilis bug-fix. \r\n\r\nKabar terakhir dari Mozilla Developer Center, setelah rilis Beta 3 ini Firefox 3.1 akan dinamai Firefox 3.5. Nah, minggu ini bersiaplah menerima kehadiran versi final dari Beta 3 tersebut. Beta 3 final ini kelak dijanjikan akan menampilkan penanganan video online, update software, kompatibilitas add-on dan kinerja yang lebih baik. \r\n\r\nSebenarnya Firefox 3.1 Beta 3 dijadwalkan akan dirilis 10 Maret lalu. Namun jadwal Mozilla ternyata meleset. Beta 4-nya dijadwalkan hadir 14 April. Kemungkinan besar jadwal itu juga tidak akan dipenuhi mengingat saat ini nyaris 100 bug masih menghantui produk tersebut, dan tiga di antaranya merupakan bug serius yang dikategorikan sebagai Priority 1 Blockers.
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Visit : 11 , Submited 16 Mar 2009 11:25
Atasi Bad Sector pada Hard Disk
tekno.kompas.com - KOMPAS.com — Suatu ketika, seorang rekan memeriksa kondisi suatu hard disk dengan sebuah peranti lunak. Ia merasa hard disk-nya kurang beres. Ternyata, dugaannya benar. Hasil uji peranti itu menyatakan bahwa ada bagian atau sektor tertentu pada hard disk yang rusak (bad sector), dan kerusakannya mengkhawatirkan. Peranti itu pun memberi tahu kalau ia sebaiknya bersiap untuk mengganti hard disk karena kemungkinan terjadi crash sangat besar. \r\n\r\nWah, perlukah rekan PCplus itu mengganti hard disk? Apa sudah tidak bisa diperbaiki?\r\n\r\nSaran PCplus, ada baiknya coba perbaiki hard disk itu dulu. Siapa tahu masih bisa bekerja lagi. Maklum, sebagian besar hard disk yang beredar sekarang ini memiliki sektor cadangan, yang ditujukan untuk kondisi seperti ini. Kalau Anda bisa memanfaatkan sektor cadangan itu, Anda bisa menunda pembelian hard disk baru.\r\n\r\nKalau pakai Windows XP, jalankan MS-DOS Prompt. Ketikkan perintah “chkdsk /R” lalu tekan [Enter]. Perintah itu akan membuat Windows mencari posisi bad sector dan mengembalikan data atau informasi yang masih bisa dibaca. \r\n\r\nSiapa tahu Anda masih pakai Windows 95, Windows 98, atau Windows Millenium, coba pakai Scandisk bawaan sistem operasi yang memiliki opsi untuk melakukan pemindaian sekalian perbaikan seadanya.\r\n\r\nCara barusan adalah tindakan cepat yang bisa Anda lakukan apabila Anda mencurigai hard disk punya bad sector. Kalau cara tadi tidak sukses, coba cara ini.\r\n\r\nPakai Utiliti\r\nAnda bisa pakai peranti yang mampu menghilangkan logic bad sector dan memperbaikinya. Asal tahu saja, bad sector dibagi jadi dua: logic dan physic. Peranti itu membuat hard disk kembali bekerja dengan “menghapus” bad sector-nya. \r\n\r\nHard disk biasanya dipaketkan dengan suatu peranti lunak untuk fungsi manajemen sekaligus perbaikan. Misalnya, Maxtor dan Quantum punya MaxBlast, Samsung punya ClearHDD, Seagate punya Seagate Format, Western Digital punya Old DLG Diagnostic, dan Fujitsu punya FJ-IDE Drive Initializer Utility.\r\n\r\nAnda tidak wajib pakai peranti lunak paketan. Anda bisa juga pakai peranti lain. Perbaikan hard disk yang dijelaskan pada artikel ini memakai SpinRite (www.grc.com). Peranti lunak buatan Gibson Research ini cukup baik buat mengatasi masalah bad sector pada hard disk. Versi terbaru peranti ini—versi 6,0—seharga 89 dollar AS.\r\n\r\nSpinRite mendukung FAT, NTFS, Linux, Novell, drive dengan beberapa sistem operasi serta hard disk yang belum diformat. Cara menggunakannya mudah saja. Tinggal ikuti langkah-langkah ini.\r\n\r\n1. Buat disket atau CD yang bisa boot. Buatnya di SpinRite. Klik [Create Boot Diskette], [Create ISO or Image File], atau [Install SpinRite on Drive]. Biar gampang, pilih bikin CD boo. Asal tahu, SpinRite hanya berjalan dalam modus DOS.\r\n\r\n2. Setelah file image sudah jadi, gunakan software pembakar CD, seperti Nero Burning ROM, untuk membuat CD. Restart komputer dan boot dengan CD yang barusan dibuat.\r\n\r\n3. SpinRite punya 5 opsi atau level. Level yang kemungkinan besar Anda butuhkan adalah level 2 ataupun level 4. Tindakan di level 2 adalah pengembalian data, sedangkan level 4 adalah pemeliharaan drive dan analisis. Pilih saja tindakan yang ingin Anda lakukan.\r\n\r\n4. Level apa pun yang Anda pilih, Anda akan diminta untuk memilih drive atau partisi yang ingin Anda periksa atau perbaiki. Setelah itu, lihat atau ubah opsi bagaimana SpinRite memeriksa hard disk Anda. Kalau sudah, lanjutkan dengan langkah selanjutnya, yakni menguji kinerja drive.\r\n\r\nProses pemeriksaan bisa berjalan beberapa jam, tergantung kapasitas dan kecepatan hard disk. Menurut informasi dari pembuatnya, kecepatan maksimal SpinRite adalah 120 GB per jam. \r\n\r\nNamun, banyak hal yang memengaruhi kecepatan pemeriksaan itu, misalnya kerusakan hard disk, dukungan Ultra DMA, atau konfigurasi sistem. Untungnya, Anda bisa menghentikan proses pemeriksaan untuk dilanjutkan di lain waktu. Agar tidak perlu mengulang, catat saja posisi pemeriksaan ketika Anda menghentikan proses.\r\n\r\nKalau SpinRite mendeteksi perlunya perbaikan, SpinRite akan langsung bekerja di Level 4 untuk memperbaiki dan mengembalikan data. Level 4 kembali memakan waktu yang tidak sebentar. Hitungan waktu pengerjaan bisa dalam satuan jam bahkan hari, lagi-lagi tergantung kerusakan. \r\n\r\nSpinRite punya screen saver yang aktif ketika SpinRite sedang bekerja. Anda bisa pula menampilkan jalannya proses yang sedang berlangsung. Jika hard disk Anda mendukung fitur pembacaan suhu, SpinRite akan melaporkan informasi suhu hard disk. Temperatur hard disk akan naik terus saat SpinRite memperbaiki data Anda. \r\n\r\nKetika bekerja, SpinRite juga memiliki opsi untuk melihat lebih dekat proses perbaikan yang berlangsung. Opsi tersebut namanya adalah “DynaStat Data Recovery”. \r\n\r\nJika hard disk masih rusak setelah diperbaiki dengan peranti seperti SpinRite, barangkali memang sudah waktunya Anda mengganti hard disk baru. *
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Visit : 94 , Submited 16 Mar 2009 11:27
Pipeline Cleaning
www.articlerich.com - ike Watson of Tube Tech International, UK , reports on how innovation and planning can reduce the cost of pipeline cleaning and de-scaling without using cutting equipment. ( as featured in World Pipelines magazine) \r\n\r\nThe complexity of gas and oil pipelines has not substantially changed, but the demands for pipeline cleaning and de-scaling have. Millions of dollars are at stake in lost production time and equipment costs if pipelines have to be dismantled to be cleaned. \r\n\r\nThe key for pipeline cleaning and specialist companies such as Tube Tech International, is the ability to bring innovative thought to problems that have always bedevilled the petrochemical industry. Indeed, the company’s reputation is growing rapidly on the back of the proposal that won it a three-year contract with Nigeria LNG Ltd (NLNG).1 \r\n\r\nProblems at the gas processing plant in the West African state, which opened in 1999, were classified as ‘uncleanable’. Condenser, heat exchanger tubes, and pipelines had become seriously contaminated by deposit, and millions of dollars in new equipment and downtime were at stake if the complex system had to be dismantled. \r\n\r\nTube Tech won the initial pipeline cleaning and de-scaling contract on three grounds: \r\n\r\n* A pledge that production loss would be minimal because none of the pipelines would need to be cut \r\n* Work in Nigeria could start within two weeks \r\n* Regardless of dimension ( 2 – 36 in) deposit could be cleaned \r\n\r\nWork began immediately at the company’s headquarters in Essex , England , focusing on the logistics on getting 32 multi-disciplined operatives and 46 t of cleaning and de-scaling equipment onsite at Bonny Island as soon as possible. \r\n\r\nProject planning was also started, involving 12km of pipeline and 60,000 heat exchanger tubes. With a convolution of bends and ‘T-offs in a maze of differing diameters of pipe work, there was no ‘one size fits all’ cure. In the event, the project team came up with a combination of 12 techniques to clear highly stubborn scale and blockages. \r\n\r\nAn airborne assault was organised, and 3 cargo aircrafts of equipment were off- loaded in Nigeria just 2 weeks after the initial site visit. Working continuous day and night shifts in frequently extreme weather conditions the teams completed the cleaning and integrity inspection three times faster than the nearest competing estimate. \r\n\r\nThe plant was quickly restored to full production using 12 techniques. The first cleaning system was a novel ‘mini pig’, only 150mm in length and conforming to the tube internal diameter. Propelled by water, the rotating blades only extended as far as the tube diameter and not beyond, thereby avoiding any damage. \r\n\r\nThe middle third of the dart houses a rotating bladed turbine, and with a water pressure of 500 psi, these blades (emulating the turbine blades on an aircraft engine) are forced to rotate at a speed of approximately 4000rpm. \r\n\r\nIn this instance, the scale causing the blockage consisted of calcium and iron oxide product. The rotating blades remove impeding scale in their path at a travel rate averaging out at approximately 2 m/s. using this method, pipe work can be cleaned in a matter of hours rather than days. \r\n\r\nThis particular turbine blade is entirely bespoke and manufactured by hand in materials that can be ferrous or non-ferrous. Tube Tech has a wide range of Dartts™ to suit diameters ranging 10mm to one metre. \r\n\r\nA second system used at Bonny Island was a traditional, automated high-pressure water-jetting lance, but this was modified by Tube Tech to create a new, more effective, method for the smaller pipes. Its engineers adapted this system by modifying the traditional high pressure jetting hose system, which normally reaches a maximum pipe length of 400m, so that it can extend as far as 2km. \r\n\r\nA further 10 systems were also mobilised, thereby avoiding the worst case scenario of substantial downtime at Bonny Island and the vast financial impact that would be implicit. \r\n\r\nThere was also a considerable amount of pipe work that was deemed ‘un-pigable’ by the client, but it too required cleaning and de-scaling as part of the contract. \r\nCutting is costly \r\n\r\nThe only solution option proffered by many experts at that time was either to fill the entire arterial network of pipe with acid or to cut into the pipeline and pressure jet. \r\n\r\nHowever, along with this option came environmental implications and costs. There were also considerable safety issues, as well as the cost of cutting the pipe open at various points. \r\n\r\nTube Tech went ahead with an environmentally sound solution using non-standard pigging. The volume of scale built up in the pipeline was such that it needed to be cleaned over the whole surface area, or the flow rate would have been compromised. The result was that more than 40 t of iron oxide and calcium water scale was removed using a variety of innovative pigging processes and types, including: \r\n\r\n• Pigs that could be inserted into a 25mm aperture and inflated to match the given pipe diameter. \r\n\r\n• Bi-directional pigs adapted with pressure bypass valves so that, in the event of sticking due to the volume of deposits ahead, the increased water back pressure would engage a solenoid in the nose of the pig, turning it into a pressure-jetting nozzle. \r\n\r\n• Pigs fired with a guide wire attached so they could be retracted \r\n\r\n• A biodegradable pig was developed to break down at the end of a potential dead-end run. This would have negated the need to cut into the pipe, as well as alleviating any risk of losing it. This particular pigging solution had been developed prior to the project. \r\n\r\nOnce the pipeline cleaning and de-scaling work had been completed. Tube Tech also put both closed circuit TV and wall thickness integrity assessment inspection equipment into action. This enabled technicians to inspect the wall thickness of the pipes electronically rather than by using expensive intelligent pigging. \r\nThe competition \r\n\r\nWhile there are many pipeline cleaning systems available global sources, with every successful contract Tube Tech has frequently found the basic equipment to be inadequate for dealing with the problems specific to each contract. \r\n\r\nIt is client’s increased dislike of the environmentally unsound chemical route and the costly cutting method that has led to the development of bespoke solutions by the research team. With this ‘applied innovation’ in conjunction with an in-depth study of the system, the company has changed the rules of pigging and exchanger cleaning by inventing new pigs and tube cleaning processes. \r\n\r\nIn the case of the Nigeria contract, the client approached a number of other companies, but none were able to offer more than three cleaning techniques involving either acid cleaning, cutting into the pipeline or high volume water jetting. Tube Tech’s involvement came through the recommendation of Shell Global Solutions International (SGSI). Without using any of these options, Tube Tech was armed with 12 techniques tailored to the varying consistencies and volumes facing them. The loss of efficiency translated quickly into financial loss, which was why the client was looking for a fast, effective cure. \r\n\r\nThe reward for restoring production to 100\\% was the three-year contract for further work. This has included advice on fouling mitigation procedures to prevent further scale blockages, particularly with the introduction of vital measures for sound quality water treatment. \r\n\r\nWhile pipeline blockages are eminently trea with expertise, there is a cause for a rethink on several fronts where prevention is better than cure. Process pipelines are not often manufactured with a view to cleanability. Tube Tech can offer end users and plant fabricators proven advice on how to modify them so that, rather than fighting fires are serious problems arise, a rethink at the manufacturing stage can tackle the root causes of scaling and blockages to out-engineer the problem.
pipeline cleaning, unblocking, maintenance, oil, gas, pipelines, condenser, heat exchanger tubes, descale, blockage, pigging
Visit : 7 , Submited 18 Mar 2009 12:26
New cure for fouled plant saves money, improves performance
www.articlerich.com - Cleaning a blocked WHRU conventionally involves costly cutting off of the serpentine bends and re-welding after cleaning; this is no longer necessary. \r\n\r\nWhen a platform s heavy plant fails, it means highly involved and often hazardous operations to disconnect it, move it off line, and then transfer it to a supply ship to be taken ashore for repair. \r\n\r\nPlant-like Waste Heat Recovery Units (WHRUs) and shell-and-tube heat exchangers are comprised of coiled tubes that can become restricted with carbon deposits. Standard industry approaches to solving the blockage problem are: \r\n\r\n* Bypass the fouled unit \r\n* Cut off the U-bends, clean the straight tubes and then weld the U-bends back in place \r\n* Replace the complete unit \r\n\r\nNone of these options are completely satisfactory. Bypassing the unit causes inefficient burning of fuel and higher platform operating costs. Cutting the U-bends is time-consuming, with no guarantee there will be access to reattach the bends. When the exchanger is returned to duty, it under-performs because deposits remain in the U- bends, so the exchanger shortly has to be cleaned again. Replacing the complete unit is the most expensive option due to the cost of the replacement unit and platform production loss lengthy downtime. \r\n\r\nA WHRU on a North Sea platform became restricted and had to be shutdown. The unit already had been disconnected and transported ashore when the operator decided to have Tube Tech try to clean it before ordering a $500,000 replacement. It can take up to a year for a new replacement unit to be installed because of a six-month manufacturing lead-time plus WHRUs can only be taken off line once a year when the platform s gas turbines are down for maintenance. \r\n\r\nTube Tech established a three-stage plan. Phase one was locating the position and length of blockages within the unit; phase two was a systematic unblocking; and, phase three was a thorough cleaning. This did not involve removing any U-bends. \r\n\r\nBecause of the size of the WHRU, two 14.5-metric ton (14.9-ton) cranes were used to change the position of the unit during cleaning. The WHRU was de-scaled, unblocked in two weeks, and restored to peak efficiency. \r\n\r\nThe operator saved £150,000 ($297,350) in possible manufacturing costs and subsequent rig production losses through on-site cleaning. After considering cost implications of a failure in one of two other WHRUs they owned, the operator contracted Tech Tube to clean both units on-site as a precaution. \r\n\r\nA serpentine shell-and-tube exchanger on a Persian Gulf platform developed a similar fouling problem. Tube Tech decided on a seawater-fed jetting system they had devised. It features low-flow, high-pressure water delivered through unblocking and de-scaling nozzles, supplemented with a specially-developed U-bend nozzle which can negotiate close-radius bends. Even in the limited confines of the platform, a comprehensive clean was completed on time and on-budget.
blocked, whru, unblock, cleaning, pipelines, pipe, tubes, u bends, fouling, maintenance, jetting, de scaled, descaling, exchanger
Visit : 8 , Submited 18 Mar 2009 13:49
Cutting edge cleaning
www.articlerich.com - Mike Watson of Tube Tech International, UK , explains the advantages of new heat exchanger and pipe cleaning techniques over traditional methods. (as featured in Hydrocarbon Engineering magazine) \r\n\r\nA five day shut down had been planned at an oil refinery to accommodate traditional pressure jetting and chemical cleaning methods to clean four crude train heat exchangers. \r\n\r\nTube Tech challenged this route using an alternative innovative method to overcome the main disadvantages: Difficult to clean with lengthy downtime leading to expensive lost production. \r\n\r\nThe company was able to clean each bundle in a few hours without chemicals or high pressure water jetting, while the other three exchangers were kept running to maintain continuity of production, effectively ‘flat lining’ the production output. The cleaning procedure delivered a substantial Kj/C-hr improvement on just one bundle compared to all four bundles previously cleaned with either of the traditional procedures. \r\nCleaning technology \r\n\r\nThere has been little change over the decades in the methods and equipment used to clean and de-scale heat exchangers and pipelines. The low-tech approach of high pressure water jetting has kept it as a low skilled job with largely unimpressive and variable results. \r\n\r\nDespite being armed with demonstrable evidence of being able to achieve better results than traditional methods, the company has faced an up hill struggle to get its innovative techniques widely accepted. \r\n\r\nIt has not been easy persuading potential clients to consider trialling new techniques designed to improve substantially on traditional water jetting methods. \r\n\r\nThere has even been outright scepticism that Tube Tech’s claims can be substantiated. Persistence and determination were needed to change the industry mind set regarding the effectiveness of current cleaning methods. \r\n\r\nLong-term maintenance contracts can also act as a barrier to an investigation of the company’s advances. \r\n\r\nThe historical reliance on low tech, low skill water jetting for pipe cleaning has meant that clients have accepted that this is the best that can be achieved. \r\n\r\nThis meant that there was often no quantifiable data against which Tube Tech’s improved results could be measured. \r\n\r\nSetting out to devise a more scientific approach to the whole cleaning and de-scaling process, \r\n\r\nThe company has created more than 40 innovative techniques. This has led to several ‘firsts’ in heat exchanger and pipeline cleaning processes. These developments include: \r\n\r\n• The ability to clean exchangers in-situ where previously they were pulled. \r\n\r\n• The ability to clean and unblock hairpin bends. \r\n\r\n• Speed cleaning difficult bundles in hours instead of days. \r\n\r\n• Online cleaning of difficult heat exchangers. \r\n\r\nThe introduction of more sophisticated technology enables the cleaning and de-scaling to be carried out faster so there is considerably less downtime, and potential mechanical damage to equipment is eliminated. Less waste, dry processes and the elimination of chemicals provides a safer and more environmentally accep process. \r\n\r\nThe company has also taken traditional pigging methods and tailored them to achieve much better results. Operating in a tube and pipe environment 2mm to upwards of 1m, equipment is modified to suit the consistency of deposit and pipe configuration. A wider variety of deposits can be removed by an innovative drift system loaded into large diameter pipes through a very small aperture which then expands to suit the diameter. It also has the ability to return back down the same line without creating an expensive loop system. \r\nAluminium tubes \r\n\r\nThe scale which builds up in aluminium furfural exchangers is notorious for being highly tenacious. The accepted wisdom has been that due to their delicate nature, aluminium hairpin heat exchangers can only be cleaned using 200bar (3625 psi) bar water pressure. \r\n\r\nThis low-pressure approach only removes 20\\% of blockages and scale with the additional problem that it tends to compact coke deposits on the U bends rather than remove them. \r\n\r\nWorking with clients sample tubes, Tube Tech’s research and development team devised a combined mechanical and water jet system which used 2500 bar ( 40,000psi) to remove coke deposits and improve overall cleanliness to 90\\%. \r\n\r\nThe three-stage process included a sensitive mechanical hairpin-cleaning device coupled with exceptionally low volumes of water. First, each tube was cleaned using the Softdrill™ lance made ‘intelligent’ metals to prevent damage to the tube wall. These soften on entering the U-tube and stiffen on extraction, while an oscillating motion drills the blockage using a mixture of water and an occasional infusion of food grade media at 12 * the pressure and four times the speed of the conventional approach. Finally, a micro turbine rotating under controlled hydraulic pressure was guided through each tube. \r\n\r\nNot only were the results substantially improved but also cleaning was carried out in-situ, reducing downtime by 200\\% and avoiding possible handling damage, the cost of cranage and bundle pulling equipment. \r\nA U-bend first \r\n\r\nThe inability of traditional water jetting to remove hard coke and oily sludge in the U bends in heat exchangers in crude oil distillation complex has produced a 70\\% cleaning standard. \r\n\r\nAfter analysing the nature and composition of the deposit and its dimensions, the Tube Tech approach was used. The result was: \r\n\r\n• 99\\% of contamination removed. \r\n\r\n• Hairpins cleaned for the first time ever. \r\n\r\n• Heat exchangers returned to virtually as new condition. \r\n\r\n• Cleaning operation completed in three times faster than the standard pressure jetting times, down six to two days. \r\n\r\n• Greatly improved throughput. \r\nIn-situ cleaning \r\n\r\nSolving problems related to specific equipment often enables the company to further improve on its initial performance. The cleaning process for an important tube bundle\r\n\r\nIn a catalytic cracker was initially reduced nine days to six but this first experience subsequently lowered the barriers further. A smaller sister unit was subsequently cleaning in three hours instead of three days. \r\n\r\nFor the first time the operation was carried out in-situ, using a new turbine method, incorporating a low-pressure water jetting system avoiding the cost and effort of removing 10t of exchanger gaskets, scaffolding or cranes. \r\n\r\nIn-situ cleaning lengthens the life of the bundles, which deteriorate through damage caused when they are removed for cleaning.
pressure jetting, chemical cleaning, exchangers, cleaning, inspection, maintenance, pipelines, cleaning technology, unblock hairpin bends
Visit : 6 , Submited 18 Mar 2009 13:50
Crack Down on Heat Exchanger Fouling
www.articlerich.com - Heat exchangers are the unsung heroes of many industrial processes and as such they tend to be taken for granted - nobody likes paying for what is often seen to be unnecessary maintenance. Heat exchangers provide duty for so long, that when they start to in efficiency, it s usually a gradual process that goes largely unnoticed - until their performance has deteriorated sufficiently to be a problem. Then it really is a problem - and one requiring urgent attention. \r\n\r\nWhat aggravates the situation is the heat exchanger that has never been cleaned properly, coupled with the commercial need to keep it on-line. When the decision is made to carry out cleaning, often nobody knows what the performance of the exchanger is meant to be, either because the drawings have been lost, or no record of any improvement was made after the original cleaning. \r\n\r\nWhen the exchanger finally is opened up to ascertain the extent of the fouling, it s not surprising to find it is so severe that cleaning takes a lot longer than planned. Any benefit that might have been gained by a quick traditional clean is offset by the extended cleaning duration and costs - and, of course, lost production. \r\n\r\nIf that sounds like a nightmare scenario, bear in mind that this is the sort of situation specialist cleaning companies encounter every week. Cleaning is often carried out without any firm knowledge of how much of an improvement the cleaning will give and how long its effects will last. Having to make finger in the wind predictions clearly is not a satisfactory way to plan maintenance. \r\n\r\nOne of the most popular and widely-employed heat exchanger configurations in industry, is the straight or hairpin shell-and-tube exchanger. With hundreds or thousands of small-bore tubes bundled together, the extent of quite modest scaling can involve major work to return the exchanger to anything near its commissioned performance. If the outside of the bundle is heavily scaled as well, the cleaning challenge rises by an order of magnitude. \r\n\r\nThere is potential to bring about a significant improvement in heat exchanger accessibility and cleanability , by working more closely with the people who design heat exchangers and fabricate industrial plants. \r\n\r\nBetter design would lead to improved cleaning - where improved means faster, cleaner and safer, possibly in-situ or even on-line and with better waste containment. It would then be easier and quicker to clean exchangers back to bare metal to return them to duty and their design performance faster. \r\n\r\nPlants are generally specified and ordered on the basis of throughput, not accessibility and ease-of-cleaning. Suppliers are happy to comply with this and therefore tend to design heat exchangers with 30-40\\% excess capacity to ensure that they can continue to provide duty, even when quite extensively fouled. Heat exchangers the world over are currently designed and installed with a view to using one of three systems for cleaning: chemical, pressure jetting and/or mechanical and this approach has remained unchanged for over 50 years. \r\n\r\nWhen it comes to maintenance, refineries - like most of industry - tend to compete on the same basis - a 21-day shutdown is decreed because it s been done that way for maybe the last 20 years. The same cleaning methods are generally used slavishly, with high-pressure water as the cleaning medium. \r\n\r\nMost companies look at their heat exchangers in isolation and simply try to extend their run-time, instead of having them designed or re-designed so they can be cleaned more regularly, but faster and better. BP s Coryton refinery, for instance, managed to reduce cleaning time on one shell-and-tube heat exchanger three days to three hours by applying a different approach to cleaning it. \r\n\r\nIf a plant is optimised for cleaning, almost full production can be maintained throughout the cleaning process. Relatively minor mechanical changes, such as adding isolating valves to heat exchangers, means that each exchanger, or bank of exchangers, can be taken down and cleaned while the others remain on-line. A redesign of the exchanger so that a header can be removed, means it can then be cleaned with a different system to the standard high-pressure water jetting, in a few hours instead of several days. \r\n\r\nAt Dow Corning s silicone plant in Barry, south Wales, a tubular boiler and fire tube in the Energy Recovery Unit (ERU) required the removal of a 5mm layer of deposit in as short a time as possible to minimise lost production. Another obstacle was that the unit, which carries waste gases, takes 48 hours to cool and prepare - even with the introduction of a chilled nitrogen purge - before personnel can enter to clean it manually. \r\n\r\nThe solution involved developing a bespoke remote de-scaler, which was inserted through a small 50cm man-way. Once inside, the de-scaler expanded to fit the hot fire tube, while reaching the full length of the carbon steel tube. With cooling time and man entry eliminated, the shutdown was reduced five days to three and there was a noticeable improvement in performance of the ERU when it came back on line. \r\n\r\nImproved cleaning cycles also mean the rate of future fouling build-up is reduced, which in turn reduces the risk of tubes corroding as a result of the exchanger being open to the atmosphere longer for cleaning. \r\n\r\nHeat exchange surfaces therefore remain smoother and provide better heat transfer. If and when the exchanger does foul up, it s easier to clean next time around, using whichever system is preferred. This would represent a change of practice to what has been the norm since the 1980s, for instance, when what was then Mobil in the UK was one of the first refineries to decide that it would extend run-times by abandoning the annual clean and only clean every two years. \r\n\r\nToday, typical service intervals have become stretched to three and even four years in some cases, but the apparent operational savings are actually a false economy. Shareholders are indeed happy, because they are getting longer run times, while competing refineries have little choice but to play the same game or lose millions during more frequent shutdowns. Four years down the line, however, the plant will have to come down for major cleaning and maintenance and it will experience a far higher capital replacement cost than ever before.
heat exchangers, industrial processes, maintenance, cleaning, hairpin shell and tube exchanger, high pressure water jetting
Visit : 5 , Submited 18 Mar 2009 13:50
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