Cross Flow Interceptor (CFI)
Oily water separation technology has come a long way since it was first introduced to the oil and gas industry by Shell in the 1950’s. Initially utilised API separators were later replaced by Parallel Plate Interceptors (PPI).
Although the PPI separator offered an important improvement in separating oil from water, the efficiency was low. In the search of optimising oily water separation, Corrugated Plate Interceptors (CPI) was jointly developed by Shell’s engineer, Mr. Jan Cornelissen and Mr. Jacob Pielkenrood. This CPI till date is utilised in most industries.
In MEC’s quest to further improve this technology, we have formed a strategic partnership with Pielkenrood BV who is one of the founding fathers of the Corrugated Plate Interceptors (CPI).
How it Works
How CFI Works
Specifically designed for the offshore industry where constraints of space are a concern, this unit utilizes a larger plate surface per m3 of separator basin volume and per m2 of separator basin area. As with the other types of plate packs, the CFI consists of inclined, parallel corrugated plates spaced closely together. Contrary to counter current separators (CPI) with the entry at the top or bottom, the CFI has an entry at the side. The water flows in a laminar stream between the plates in a horizontal direction.
The main advantage of the CFI is that heavy as well as light particles can be separated from the effluent simultaneously. For instance, oil is separated by floating upwards along the top of the corrugated plates to the surface of the separator tank. Heavier particles at the same time settle along the bottom of the corrugated plates and slide down the plates to be collected in a sludge cone and discharged through a blow-off valve.
- Capacities from 2.5 m3/h to 420 m3/h for a single unit;
- Removal of oil droplets of < 30 microns;
- Removal of solid particles < 20 microns.
Modification of Existing CPI or TPI separators
The CFI concept is also suitable to modify existing CPI/TPI separators. By replacing the CPI/TPI plate packs by CFI type ones; the effective plate surface area is increased without altering the outer dimensions of the CPI/TPI basin. Replacing CPI/TPI plate packs by CFI ones, instantly increases the plant capacity and/or separation efficiency. In figure 10 one can see Cross Flow plate packs applied in an existing CPI basin. The original effective CPI pack surface was 130 m2, while the effective Cross Flow pack surface is 500 m2.
When converting an existing CPI/TPI separator with CFI plate packs, we use mobile IPI separators in order not to disrupt our clients’ plant operation.
Pressurised Cross Flow Interceptors (PCFI)
The PCFI is specifically designed for the oil and gas industry where it is designed to contain live process liquids as this requires the use of pressure vessels to avoid uncontrolled emissions of hydrocarbon gases or liquids.
This is used to de-hydrate the oil or gas condensate after the first stage separation and for de-oiling the produced water in the second stage. The CFI plate packs are designed specially to fit into any (existing) pressure vessel and offer highly efficient operation. Apart from modifying existing pressure vessels to increase the oily water separation efficiency, we also design and build new pressure cross flow interceptors.
Applications & Advantages
CFI & PCFI Units are suited to the following applications:
- Where water is collected from multiple, low pressure sources
- Handles oil/solids slugs & intermittent flows
- Common in onshore centralised Water Treatment plants
- Settles larger oil droplets and coarse solids
- Mostly supplied with a Pressurised Vessel, to contain and control all gas and liquid emissions
- Primary treatment stage of a Water Treatment train where multiple stages of treatment are required to ensure reliable and effective water treatment.