Please find herewith the reply from PERSTORP on the Technical documents submitted.
 
Reply on Selection of Interphase Level controller
 
The LLE operation is instrumental and the selection & responsibility of the instruments will be by M/s. Techno Force. Therefore we request you to decide the type (may be Mechanical or Microwave Type) of instrument & LTL shall procure the same for our requirement as per M/s. Techno Force's specification.
Reply on P & I D, Layout & GA Drawings
 
Please find herewith the quoted reply from the PERSTORP & next to the quoted reply find the LTL's clarifications on the reply.
 
Quote
 
Comment to the P&ID.
The lower separation vessel V-802A will in normal operation not have organics going to V-816 (See PEL-121b), and there is no need for an density control. The line to V-816 will normally be closed, and the adjustable U-pipe can be at it’s lowest position.

If a lot of organics accumulate, then the density meter will alarm, and the operator drains the organic phase manually.

 Layout:

Are you sure gravity flow from V-820 and V-802A to V-816 and V-802 will function?. We had the original placement of V-820 at 13m. See PEL-086

 Drawing V-802

Should there be a continuous stream of organics coming with the salt phase, the unit will have to operate with an adjustable overflow weir. Target is to have the interface where the sight glass is at:

There will be a 569 mm of salt phase at density 1200 and 443 [1138-226+100-569] mm of organic phase at density 900. Makes overflow U pipe at 901 mm. This overflow should be adjustable +/-100 mm from that point as the actual densities will not be exactly 900 and 1200. 

 
  
 Normal
 Extremes
 
 
  
 Dens
 Dens
 Dens
 
Top layer
 443
 900
 800
 950
 
Bottom layer
 569
 1200
 1300
 1050
 
Overflow
 mm
 901
 842
 970
 

 Drawing E-821

We have had a slight misunderstanding. I would like an additional 2â€ nozzle with blind at ~ 2,5 below the top. This is the spare nozzle for moving the feed down and introduce the washing through the old feed nozzle. N18 is not needed.

 Operating manual

I found the operating manual very thin on information regarding trouble-shooting and the like. Kühni had a lot more. I think you should insist on the level interface instrument to be part of the vendor’s undertaking, as it is instrumental in operation of the column

Unquote
 
PEL-121b mail for REFERENCE for a comment on P & ID above.
Quote

I assume the operation is as follows, otherwise you must clarify:


We want to keep a level in V-802A more or less constant. Via an “underflowâ€ weir the raffinate flows to V-802, much like in vessel V-846. The line to V-802 is normally closed, so level will oscillate a bit. After a long operating time, enough organics have accumulated for DI-802A to detect low density, and an operator opens the line towards V-802 and decanters the organic phase.

Should the extractor always have entrained droplets of organic in the raffinate (something we hope not), the decanting has to become continuous. 

Now: internals about an “underflowâ€ weir in V-802A are not shown, it looks like the vessel will always be empty as liquid entering will flow directly to V-802.;

liquid entering from P-821 should do so below the surface, not to cause ripples.

Unquote
 
LTL's clarifications:
Consider Density Transmitter with indication only & no control required therefore consider only manual globe valve on V802A to V802 line. 
Keep height of U pipe accordingly so that the sight glasses can be used for top layer collection visualization in the bottom settler. 
Locate all equipments (E821, V820 & V802A) on floor +13.00 m level instead of +10.00 level. 
Refer quoted reply of PERSTORP for GA Drawings & Operating manual.
Please note that the SLEI/ LTL's comment will be forwarded to you on 28/09/07.
