Atmospheric residue filter plugging

[ponderer]

In our ARDS unit, we encounter atmospheric residue filter(removing 25 micron particle) plugging problem for a long time.

The mesh size of suction strainer of the AR pump in CDU is 20. We wander if the opening the strainer is too large to remove the fine particle.

The ARDS filter plugging problem worsen during crude switch.

We guess some particle is carried with the crude oil entering the CDU, the particle then concentrate in the AR.

Who has the same experience with us?

How to solve the problem?

 

[July]

What is the BS&W of the crude? It appears you do not have a desalter. A desalter will not only remove salts but also any sludge carried with the crude.

 

[25362]

Whenever you switch crudes the new inflows come from tank settled out bottoms with a potential dirt carry over. Is a multiple set of filters with some kind of backwash a working possibility ?

 

[ponderer]

The BS&W of the crude is about 1%.

We have two stages desalter in CDU,
but no desalter in ARDS.

We have bag filter with 20 mesh in CDU
crude feed.

We have automatic backwash filter which
can remove 20 micron particle in ARDS.

 

[25362]

The BS&W is considered high. Sometimes double disalting helps. Sometimes pre-dilution of viscous crudes with lighter distillates help in settling. Others suggest the use of centrifuges or at least hydrocyclones. Water emulsions and oil viscosity are against efficient tank settling.

Anyhow, it wouldn't harm to contact Howe Baker e-mail: dking@chicagobridge.com
for electrostatic desalting, or Alfa Laval for decanter centrifuges.

The fact the AR filters plug up, indicates that the screen size is sufficiently small. Of course, it doesn't preclude smaller particles to pass through.

Is it possible you ask the supplier of the crude to take better care of his lot dispatches. Origin of sediment can be at the well by the use of drilling fluids (sand, clay, silt, shale or rock particles), or by picking up scale in transportation.

In the meantime try to use (install) a higher outlet nozzle in the crude feed tank, may be you can avoid a quick plug up of the filters.

 

[krsmani77]

You have double desalting. Have you ever cleaned the desalters? How is the interface - clean or full of interface muck? This prevents proper water settling. This may occasionally get carried over during process upsets such as crude switch. Also the water carryover to the heaters can create a mild spalling of coke/carbon particles deposited in heaters. Do you see this effect ? This spalled particles can choke your filters. Have you analysed what is the strainer deposit? A high loss ibnition will corraborate this theory and a low figure will confirm what others have told you. Best of luck

 

[nosaMgiarC]

Looking at the problem a different way. Have you challenged the need for the filters being sized at 20µm? In the offshore industry we've seen similar situations where inline filters have been over specified and through investigation have been removed or respecified to a higher size.

Just a thought!

 

[krsmani77]

Another thought. Why not trap them in a regular Basket Filters ( twin duplex, sized to suit your cleaning schedule and with back wash facility) where it is convenient for you to trap them (if not possible in tanks or desalters)? May be that is what you are doing in yr ARDS filters.