CASE HISTORY: ACETIC ACID RECOVERY PLANT

ESMIL Process Systems were briefed to design an acetic acid recovery and concentration plant for a client’s new Petrochemical Plant in Europe in 2021. The new Acetic Acid Recovery plant (AARP) design specifications included:

  • Hydraulic recovery of 90% (minimum) final permeate to plant feed ratio
  • An acetic acid recovery efficiency of 80% (minimum)
  • A robust, modular & fully automated plant
  • Plant manufactured to Petrochemicals standard manufacturing specifications suitable for Hazardous Zone 2 area.

Process design

Esmil typically conduct rigorous process analysis before finalising the process design & engineering. Normally a 2-stage process is followed, wherein the process fluid is analysed using laboratory scale units at Esmil’s High Wycombe site to confirm the initial proposed design. Secondly, site trials are held on the customer site with pilot plant units to quantify process variation, and measure membrane fouling & cleaning requirements for the final design.

In this case, the process fluid was simulated in the laboratory before extensive laboratory test work was undertaken. As this is a green field build, no site trials were possible.

Extended testing of membrane performance after soaking for the prolonged period in concentrated acetic acid was conducted to determine changes in acetic acid rejection and flux characteristics. Prolonged runs were conducted to establish membrane cleaning requirements and any adverse effects by the acidic medium on the membrane material.Esmil image

Process description

The feedstock which is a PTA process by-product is at 1-2% (w/w) acetic acid concentration. This is fed to the first pass of reverse osmosis membranes to effect initial separation, and the concentrate recovered is returned to the process.

The acetic acid is concentrated through the use of a second pass of RO membranes wherein the concentrate from the second pass is returned to the first pass feed tank. The final treated water from second pass goes to the site effluent treatment plant.

Plant Data

Parameter
Units
Pass 1
Pass 2
Nos. of Trains
Nos.
2
2
Cleaning Unit
Nos
10 - 40
Op. Pressure
barg
55
45
Location
-
Indoor
Area Classification
-
Zone 2 Gas Group IIA/IIB Temp T4

Typical delivery of system

The complete design, engineering, manufacture and installation of similar separation/concentration membrane systems is between 40 – 50 weeks from placement of firm order.

Waste water treatment facilities on Corrib terminal now ready for use (Bellanaboy Bridge Gas Terminal)

The state-of-the-art waste water treatment plant on the Bellanaboy Bridge gas terminal has been handed over by the Construction team to the Operations team that will run the plant when gas comes on stream.

As the Corrib facility is located in an environmentally sensitive area, it is necessary to treat any waste water for eventual discharge to both onshore and the immediate environment offshore, to a set of very strict parameters, as set by the Environment Protection Agency. To meet these extremely stringent levels, a bespoke suite of equipment was put together.

There are two separate waste water streams treated in the plant. The Surface Water Plant treats run-off from the paved areas and has a capacity of up to 30m3 per hour, while the Produced Water Plant treats water which comes from processing the gas and has a capacity of up to 6m3 per hour.

To ensure that EPA levels are complied with, a number of innovative and top-of-the-range solutions have been introduced, both for the surface water run-off from the paved areas and for the treatment of the condensate from the process gas. These include tilted plate separators, multi-media filters, ultra-filtration membrane packages for oil removal, and nano-filtration membranes together with carbon filters and ion exchange resin for the removal of metals from the condensed and formation water.

Combined Sludge Treatment

The rejected process waste together with any cleaning and regeneration waste products are treated via a precipitation and fl occulation process before being passed through a fi lter press unit, with the filter cake being removed for disposal and the fi ltrate returned to the start of the process. According to Michael Flannery, Project Delivery Engineer, the combination of technologies used in the Produced Water Treatment Plant is “very advanced and purposely designed for the Corrib project”.

Contact ESMIL

For further information or enquiries, please complete the contact form or e-mail Esmil direct at info@esmil.co.uk

Feedback form