Implementation of a Comprehensive Inspection, Cleaning and Disinfection Regime.

Background

The Wilton Site at Middleborough houses SABIC’s pioneering LDPE plant, the largest of its type in the world, which has been operating for over 5 years. The LDPE plant utilises a 4 cell induced draft cooling tower to perform a critical cooling function in the process and this asset was identified as an area of interest regarding the continual monitoring and trending of fouling build up within. As a result SABIC were introduced to EPSCO due to our extensive experience in cooling tower inspection, cleaning and disinfection procedures using unique and innovative processes.

Objective

The objective tasked to EPSCO was to perform a thorough inspection of all 4 cells of the cooling tower using a combination of our patented PackScan® inspection tool and traditional endoscopic inspection to ascertain the condition of the tower, grade the condition against the HSE’s HSG274 guidance and recommend any remedial action if required.

Stage 1 – Inspection of 4 Cells using PackScan® and Endoscopic Techniques:

Following the initial meeting between SABIC and EPSCO we attended site to complete the inspection of all cells with one cell isolated for inspection at a time while the remainder were online. This allowed the plant to continue normal operation throughout with the inspections being completed within 3 hours on each cell.

The inspections revealed that the condition across the tower was similar with a build-up of bacteriological deposits in the upper areas exposed to sunlight and a light build-up of deposits within the packing.

During the inspections a sample of the deposits present within the pack was obtained and EPSCO had these analysed by an independent laboratory to determine the exact make up to allow adjustments to be made to the online water treatment and to plan an effective chemical cleaning procedure. The data and images produced during the inspection illustrated that the cooling tower had a deposit build up that should be removed in order to comply with the associated guidance.

Stage 2 – Cleaning and Disinfection of Cooling Tower:

Following completion of the inspection regime and the identification of the need to remove the deposits, EPSCO submitted a proposal to complete a thorough cleaning and disinfection procedure. This was to be completed in the scheduled plant turnaround using our patented Microsolve® process. The proposal covered the treatment and removal of deposits from the upper dry areas, drift eliminators and fill pack with a chemical treatment that had been tailored according to the analysis of the deposits present.

Upon acceptance of the proposal an operations team attended site and completed the cleaning and disinfection of the identified areas in all 4 cells within 6 days on site. EPSCO used its own patented Microsolve® system for the chemical cleaning and disinfection of the cooling tower. The system consists of a range of specifically designed chemical treatment agents along with a number of chemical pumping rigs to facilitate dilution and delivery of treatment agents to the areas of application.

The success of the works were verified by the use of both PackScan® and endoscopic inspection and these showed that over 90% of the deposits within the pack were removed by the  procedure. All wash water and spent chemicals were contained within the sumps and the discharges of these materials were handled by SABIC’s preferred waste contractor.

The Outcomes

A full and detailed completion report was produced following the procedure which was inclusive of a cleaning and disinfection certificate, observations report and supporting PackScan® data, endoscopic and  digital images from all of the cells treated for the client’s records. Some representative images are shown below.

 

Fill Pack - Pre                                                                                                                    Fill Pack – Post

PackScan – Pre                                                                                                                PackScan - Post

Upper Dry Area - Pre                                                                                                Upper Dry Area -Post

                                                      

The project was completed on-time and on budget through a process of effective communication and teamwork between EPSCO project teams, on-site contacts and permit authorities. All work was undertaken safely in-line with site procedures with ZERO ACCIDENTS or near-misses. It is intended that a regular cleaning period shall be determined by continuing routine inspections to monitor and trend any deposit accumulation.