Make-up water, sidestream filtration and condensate polishing packages – Pakistan

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Project Description


IDC was selected by ENI Snamprogetti for the supply of three water and treatment packages to be installed into the New Ammonia/Urea Plants Project in Daharki – Pakistan.
IDC was asked to design and supply three packages suitable for installation outside, and in particular:


The aim of the package is the physical filtration of raw water to remove suspended solids (expected TSS content 20 – 10 ppm) and provide make-up water to cover the losses during the site processes.

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The system consists of 6 horizontal Quarts Sand filters, 2 air blowers and 2 pumps for the backwash to ensure the automatic cleaning. The sand filters are design to ensure a stable production of up to 1500 m3/h of make-up water even when a filter is out of service for the backwash.


The aim of the package is the removal of ions impurities from condensate water (more than 500 m3/h) coming from a mixture of different streams to provide quality condensate to be used again, reducing the Opex saving water and energy consumption.

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The plant consists of 3 mixed-bed columns and accessories, such as blowers, centrifugal pumps and dosing station for acid and caustic soda, for the regeneration and what is necessary for the neutralization of the eluates.

Normally two mixed bed exchangers are in service while the third one is in stand-by or under regeneration.

Ion exchange is a chemical process in which the resins remove unwanted ions from the water, while giving back an equivalent number of a wanted species. When the ion exchanger is saturated, it is necessary a washing with regenerating solution to restore the resin.

The complete cycle usually includes backwash, regeneration, rinsing and service.


The purpose of this package is filtration of cooling water (1500 m3/h) using 5 atmospheric Quartz Sand filters, in order to reuse the water in the system.

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The raw water flows through the sand bed and is collected on the upper part of the filters. As the pressure drop increases, the water level in the inlet and backwash pipes increases as well, up to the level in backwash pipe reaches the discharge pipe. At this point a siphon is primed, sucking water stored in treated water compartment and backwashing filtering media.

The filters are atmospheric type and are feed by the splitter box, a fundamental part of the supply, that allows the correct distribution of the water flow in the 5 filters.

Due to the dimensions, the filters were delivered partially assembled to be completed and tested on site with the last welding and painting.

Project Details

  • Our goalThe most challenging requirements was to design a dedicated system for the make-up filters in order to backwash them automatically without any automatic valve or instrument as per Client requirement. This let us find innovative ways to use only physical laws where normally instruments and signals are used, providing superior reliability and safety in operation.
  • DetailsThe IDC supervision was a key service in the supply of this project. The different technologies involved, the assembly activities and the test to be performed on site, the packages’ automation and the personnel training had a crucial role in the Customer satisfaction. In particular, the Customer appreciated our attitude to problem solving finding solutions both during the design phase to optimize the whole performances and during the start up activities.