Many sulphur-burning plants are plagued by high ash content levels, which contaminates both the waste heat boiler and the catalyst bed in the acid plant’s converter. The answer to this problem is installing a liquid sulphur polishing filter after the pressure leaf filter. The liquid sulphur polishing filter with ceramic elements will drastically improve the run time of the sulfuric acid plant.
How does it work
The filter holds ceramic filter tubes. This is a combination of surface and depth filtration. The sulphur flows from the outside of the filter element. Solids are retained on the surface of the filter tubes and clean sulphur comes through the outlet of the sulphur storage. The filter is cleaned by injecting steam into the reverse direction.
Possible complications in the polishing filter operation
The operation of a liquid sulphur polishing filter is demanding and, in some cases, problematic. Some of the possible problems, along with recommended solutions are:
1. DESIGN
Most filters are designed on flow rate, typically handling ash levels as low as 20 ppm at the inlet. However, when problems are encountered at the pre-filter, the ash content can build up fast and the polishing filter will be plugged.
Solution: A flow-based overdesign of 10-20 % is a must to avoid possible breakthroughs of ash, preventing short cycles and overloading the filter with solids.
2. CLEANING
The ceramic filter tubes are cleaned by injecting high-pressure steam in reverse. The steam will follow the path of the lowest pressure drop, so clean filter tubes will allow steam to pass through, while plugged filter tubes will not be cleaned efficiently.
Solution: In this case, the solution is to use individual outlets. This allows for sequential cleaning of each filter tube register. This approach enhances cleaning efficiency and often doubles the lifespan of the filter tubes.
3. SEALING OF CERAMIC FILTER TUBES
Ceramic filter tubes are fitted with glued-on gaskets that often loosen due to high temperatures, damaging the sealant.
Solution: To address this, a specially designed filter tube holder keeps the gaskets in place, ensuring a reliable seal. This holder also allows for the extension to accommodate double-length filter tubes.
4. BLOCKING CAKE DISCHARGE OUTLET
Accumulation of high amounts of solids in the polishing filter can block the cake discharge opening.
Solution: This can be prevented with a specially designed heated cake outlet valve, which can be supplied with an opening of up to 16 inches.
5. STEAM VAPOURS AROUND THE FILTER
Backflushing the filter with steam releases vapors from the bottom outlet, posing a danger to operators and causing corrosion on the filter and surrounding equipment.
Solution: Sulphurnet has designed a special cake discharge drum that directs the steam to a safe zone. Using this discharge drum allows for high-pressure air to be used for thorough and efficient cleaning instead of steam.
Implementing these features not only extends the lifespan of ceramic filter tubes but also enhances the safety and reliability of the operation. Reliability is further ensured by installing pressure instruments to measure pressure differentials and automating the system.
For more information about the polishing filter and its features, do not hesitate to contact us at [email protected]
Thank you for article. The problem we are facing is the dumping of the ash. Due to the hazard classification, the dumping costs are high.
The promulgated waste management act requires that all recycling options be considered before dumping is considered.
One option is to consider the positive results obtained from agricultural sector. Micronised Sulphur may be considered as a plant food.
Do you foresee any toxic complications for plants if micronised Sulphur ash is used as a micro element in fertilizer formulations?
I’ll appreciate your response tremendously even if you suggest a specific pot plant test.
Looking forward to your comments, kindest regards
Leon,
the toxicity of the sulphur is not an issue if the sulphur is originated from refineries.
If it is Frash mined sulphur (still in the market) you need to analyse carefully on organics and especially for metals.
Micronised filter cake could be used as fertiliser, it contains S, Lime, Gypsum and ashes, and filter aid (which is mainly SiO2 and Al2O3).
I have sent you an email with alternative options for the re-use of the filtercake.
JAN