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Duomatic automatic feed filters reliable and flexible equipment produce profits for Bea

Published 12 February 2018 | By Bea Technologies SpA

DUOMATIC FEED FILTERS are generally installed in refineries and petrochemical plants to protect reactors and catalytic beds from premature plugging.

DUOMATIC FILTER SYSTEM is a tubular self-cleaning filter specifically designed to remove continuously oversize solids, iron sulfide, coke fines, dirt and solid contaminants from feedstocks in refineries and petrochemical plants. It is applied primarly for solids control in HYDRODESULFURIZER, HYDROCRACKER and in PETROCHEMICAL REACTORS to protect the catalyst beds from contamination or plugging.

Infact solid particles and dirt begin to plug catalyst bed long before the catalyst is spent with a pressure drop faster increase through the reactor. When further pressure drop increase cannot be tolerated premature top-bed change-out is necessary to regain process maximum performance.

DUOMATIC FEED FILTER, by preventing solid particles from entering and building up in the catalyst bed, allow to reduce substantially top-bed change-outs and to maintain optimum reaction parameters.

Extended catalyst life thus results in longer reactor run times, higher production rates and real savings in operating costs. This system can be even used for clarification of a broad range of oils and distillates .

These automatic backwashable systems are suggested when it is necessary to filter consistent flow rates with a contamination load exceeding the percentage usually accepted for the installation for consumable cartridge filters.

DUOMATIC FEED FILTERS are characterized by the capacity to be fully regenerable by backwashing using a small portion of the same filtered fluid without to stop the filtration and the need to flush with steam and nitrogen before to open any vessel to change the filter elements.

This fact is of great importance when the liquid to be filtered is processed at high pressure and temperature. These condition are often present in process incorporating reactors with fixed bed catalyzers as HYDROTREATING, HYDROREFINING, HYDROCRACKING.

Generally in these reactors the flow of the liquid is from TOP to the BOTTOM and the potential contaminants particles are retained on the top surface of the catalyst bed. The solid contamination builds up on the surface of the catalyst bed reducing the available area for the liquid flow and increasing the pressure drop in the TOP layer.

The pressure drop is one of the parameters which are impacting on the efficiency of catalytic reaction and the overall economy of the process.

Infact the increase of pressure drop is forcing to compensate the effect with or an increase of temperature of the liquid or with a decrease of the speed through the catalyst bed which may facilitate the production of undesiderable reaction subproducts. The final results is an increase of operation costs (more fuel burnt to increase temperature) and reduced service life of catalyst bed before next changeout.

The typical solid particles to be retained are Iron sulfide, coke fines, rust, resin agglomerated and oxidated subproducts. Those solid particles are just plugging the top layer of the bed but are not deteriorating the catalyst which can be recovered.
DUOMATIC FEED FILTER is installed before the reactor to separate all the solid particles exceeding a certain size and to avoid the plugging of the TOP surface of the catalyst bed.

The solid particles are retained on the external surface of the filter elements to form a "cake" which is maintaining certain characteristic of porosity depending from the amount of particles in the liquid. When the pressure drop increases to a set value then is starting the backwashing cycle to regenerate the filter surface. Only one filter vessel at the time is subjected to regeneration while all the other are remaining in filtration.

During the backwashing cycle there is no visible impact on the flow to the reactor because the DUOMATIC FEED FILTER is designed to maintain constant the flow to the reactor and to use only a small portion of filtered liquid for backwashing.
Infact the backwashing lasts for few seconds for each filter vessel.

The full backwashing cycle , regenerating all filter elements , is completed in few minutes recovering the initial clean pressure drop.

BEA Technologies has experimented that the efficiency of backwashing is very high even after more than 15 years of filter operation.

It has been recorded that the presence of water in the intermediate phase of process or storage, before filtration, is facilitating the formation of inorganic sub-products when there is a concentration of iron around 1 PPM in the liquid fed to the reactor. If the concentration of iron is reduced to below 0.25 PPM then the service life of the catalyst bed can be easily increased by a double digit. The presence of water and oxygen accelerates the formation of different oxides. In this case is suggested to reduce the storage time and to feed the liquid still hot to the Feed filter. In case of storage for longer time before filtration it is necessary to maintain a pressure of nitrogen in contact with the product to reduce the activity of oxygen and to control the polimerization of hydrocarbons.

BEA

The installation of "DUOMATIC" FEED FILTER makes really possible to control and slow down the increase of the pressure drop through the catalyst bed and to maintain the efficiency of the catalyst reaction for a longer time.

From data taken on some hydrocracking units where DUOMATIC FEED Filters were installed and working since seven years it results that the Filters have been repaid in less than 3 years due to following facts:

  • Increase of Service life of catalyzers and consistent reduction of change-out frequency
  • Reduction of plugging of the catalyst particles which maintain efficiency of reaction through time and yields of products.
  • Reduction of pressure drop increase which requires less energy for the reaction, avoid the need to increase reaction temperature with potential increase of corrosive sub-products on the metallurgy of reactors.
  • Possibility to process more heavy crudes to increase the flexibility of different feed conditions for the refinery and improve production profits.