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21/09/2016
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Jeffin Jefferson, Abu Dhabi Oil Refining Company, jeffinjefferson@gmail.com
To add to the query, has there been a case in any of the Refineries, where the backwash stream (post backwash) is routed back to the cold feed tank instead of slops. The idea is to minimize sloping and reprocess it.
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15/12/2010
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Mark Willingham, Purolator Advanced Filtration, mark.willingham@purolator-afg.com
Please advise what type of filter media you are using. Some filter media will blind off faster than others, and there is a major difference in porous metal filter media in terms of ability to adequately recover after the backwash cycle.
Our company- Purolator Advanced Filtration- offers a high permeability sintered wire cloth that has been proven in a variety of applications in refineries where previous porous metal filters had failed. The key to our success is in the design of the pore structure. The media is designed with a high permeability to allow free access of the backwash fluid/gas to the layer of filter mesh that is plugged with fines or asphaltenes. We have had very good success in VGO filtration in residue oil, and other areas as well.
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22/02/2009
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Marcello Ferrara, ITW SrL, mferrara@itw.it
If the problem is related to asphaltene precipitation and/or heavy hydrocarbon deposits, as well as polymer deposition, ITW Online Cleaning will help.
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28/01/2009
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Mike Watson, Tube Tech International Ltd, mike.watson@tubetech.com
From our perspective on-line filter recovery depends very much on its design and accessibility.
One supplier has suggested that you could alternate filter bundles between the filtering cycle. However, if these could be designed in such a way as to isolate for a short period from the process then a very quick Jet wash / Ultrasonic / Bio chem flush / rinse process could be applied.
Although that won't help you right now in regard to online cleaning if direct access is unavailable to the filters where we can place a high pressure / high temperature access seal.
Our global service provides very large ultrasonic chemical cleaning tanks that can cope with multiple filters of any size. Hydrotreater related fouling, ie asphaltenes, gums are easy to remove. Personal experience with solvent soaking has limited effect as velocity of chemical is critical i.e. flow must exceed 2.5m/s.
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27/01/2009
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Lindsay McRae, Pall Corporation, Lindsay_McRae@pall.com
To effect on-line filter recovery depends very much what it is that is fouling the filter elements and on how the backwash filter unit is designed.
Some clients select 3 x 100% filter vessels that allows maintenance such as filter bundle cleaning while the other 2 vessels alternate between the filtering cycle and backwashing (and solvent soaking). If the filter system has 2 x 100% units, then maintenance is more difficult as the available maintenance time is limited to the backwash cycle time which for a fouled filter may be quite short. In this case partial or full bypass of the filter system may be needed for maintenance if the bundle requires cleaning. Spare filter element bundles should be kept for such occurences.
The filter media type and micron size used is also important in optimum BW filter operation. At least 3 different types of media types are commercially used with varying success. Some are more prone to fouling than others.
Investigation of the fouled filter elements plus also understanding the the feed type (or types) and also the feed routing can determine the cause and provide possible solutions.
The type of backwash method being employed and the source and quality of the backwash fluid being used is also should be considered in a troubleshooting study. With liquid backwash filters, dirty backwash fluid is often a source of reverse plugging, and often results in short cycle and excessive reprocessing or downgrading of feed.
There are a number of possible causes of hydrotreater feed filter fouling including:
i) Fouling by asphaltenes. May be countered by raising the feed temperature, and employing a filter system with an automatic solvent soak cycle.
ii) Incompatible feedstocks (where more than one feed is used at a time). Can cause severe asphaltene precipitation. Don't use incompatible feeds.
iii) Fouling by gums. If hydrotreater feed is via tanks; ensure the tanks have adequate Nitrogen blanketing in place. This is especially important for cracked feedstocks.
iv) Inconsistent filtration rating. Filters with non-fixed pore sizes or some slotted wire media may suffer reverse plugging during backwashing when particles bypass the filter media and are later driven into filter media during backwashing. Backwash fluid quality is known to vary considerably from plant to plant. Gas Assisted type backwash reduces the problems of reverse plugging and reduces backwash fluid generation.
v) Filtration level too fine. Finer filters foul quicker than courser filters. 25um nominal is generally considered to be adequate to protect fixed bed rectors from fouling although finer may be appropriate depending on the particle size distribution present.
vi) Valve failure - mechanical problems have been known to reduce backwash efficiency and decrease effectiveness of regeneration.
We would recommend an audit to be undertaken to understand the root cause and define the solutions. Such consulting services are available from some experienced filter vendors.
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25/01/2009
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Mike Watson, Tube Tech International Ltd, mike.watson@tubetech.com
Yes, there is a possibility of cleaning online. Images, isometrics and a bit more detail are required as existing online technology could likely be used.
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23/01/2009
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Keng Chung, Well Resources Inc., kengchung@hotmail.com
No. Some filter vendors recommend solvent soak. It does not work. You should understand the root cause(s).
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23/01/2009
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keith bowers, B and B Consulting, kebowers47@gmail.com
Absolutely--install parallel filters. Ronninger-Petters makes just such a system--automatic switching, bafckwash, etc. This IS NOT an area to economize. Use a package vendor that can prove successful operations in similar service. Install the package system properly and you can expect years of good reliable service and excellent filtration of your dirty feed. It is VITAL that the characteristics of th feed contaminants be well characterized. Particle size distribution is a key part of the anaylsis. Some contaminants are too small to filter (collodial iron or even soluble iron for example)
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