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Cooling Water Systems


Company: Saudi Aramco, Saudi Arabia

About the customer:

Saudi Aramco is a government owned company and is not only known as the world largest producer of oil, but also as the world’s most valuable company. Also, it is common knowledge, Saudi Aramco has the most proven production of oil and oil reserves in the world. With almost 60,000 employees, Aramco produces more than 250 oil and gas fields. Next, to the production and transportation of the oil and gas, Saudi Aramco also operates a row of refineries, where Riyadh Refinery is one of them.

The refinery was commissioned in 1981 and is producing more than 100KBD. The cooling water system has central cooling towers, that feed a several kilometer long piping networks with almost 300 heat exchangers and different machines. The total amount of water in the system is around 5.500 m3. The feed water has approximately 2,000 TDS and the blow down around 5,000 TDS.

The refinery has a planned shutdown, every three years. During this shutdown most of the heat exchangers on the water side are opened and inspected. In most of these heat exchangers heavy fouling and scaling are found, both on the tubes and at the shell, as well as, at the inlet and outlet pipes. Corrosion is a big issue at some places. The procedure for the cleaning is to disassemble the heat exchanger, do chemical cleaning and assemble again. This is very time consuming and expensive.

The first trail with the Pursanova DiskTM has been done at a few, most critical Heat Exchanger tubes, where there was a possibility to open and check the results during regular operation.
The two pictures on the top (marked as before) show how normally the inlets of the heat exchanger tubes are looking. Next to scale, corrosion and mud artificial particles are found as well.
When taking the photos there was no mechanical cleaning done. The photos were just taken and the heat exchanger was closed again, in order to see if Pursanova TM was able to remove the existing fouling.
The two pictures at the bottom show an outlet and an inlet of each one pass of this 6path heat exchanger. The surface results were after six months using Pursanova TM which has been totally clean, and no scale, no fouling or no trace of corrosion could be found. On the lower right side, where the sludge can be seen originated from the sacrificial anode.
After seeing the results of the Pursanova TM treated Heat Exchanger, the trial was broadened and installation took place with another 50 Heat Exchangers, in order to verify the previous results during the regular shutdown of the refinery. During the shutdown, all Heat Exchangers were opened and cleaned. It was very obvious; the Pursanova TM treated Exchangers were either totally clean or far cleaner than the untreated one.
On the U-bend the Pursanova TM was installed on the U-bend. To confirm the effect of Pursanova TM photos where taken, both upstream and downstream of the position of the disk. As Pursanova TM is working only downstream, it can be seen that the untreated pipe still has fouling and scale whereas downstream the rings all scale is gone.

Here two inlets to a heat exchanger can be seen, as well one from upstream and one from downstream the point of installation.
The photo to the right shows the header of a heat exchanger when it was dropped on a truck. This was done to move the header to the cleaning of the heat exchanger, which has taken place not inside the refinery but a dedicated cleaning place.
When dropped, all the scale and fouling just fell to the bottom on the truck. There was no scale sticking to the surfaces and no corrosion can be found. The cleaning of the Heat Exchangers which has been treated, has been very easy withno need of aggressive chemicals.In most cases the mud and debris could be removed just by using a normal water hose or a regular pressure cleaner.
After the shutdown, they discussed future decisions moving forward. The ultimate goal would be to control the entire cooling system.
What to expect and how to achieve this, is described below.
The whole project is divided on four phases, only when one phase is realized, documented and approved, will the next phase start.
The whole project will run over three years, and only at the end will it can be decided, if it is possible, with the results seen, to the extent the service cycles for the heat exchangers on the water side.