A nice job for our overseas engineer: to carry out chiller condenser tube cleaning in Cadiz, Spain. We have The Spanish Office near Malaga with a manager and an engineer out in the field- so our Spanish engineer assisted our overseas engineer.
Centrifugal Chiller Condenser Tube Cleaning
The factory has 4x water cooled centrifugal chillers with a combined cooling capacity of 8 MW. The chillers cool down a process involved with the production of an industrial chemical.
High Condenser Pressure
When we looked through our Tick Sheets we could see a gradual deterioration of the high side readings over a period of time. This showed us that an overhaul needed to be carried out on the condensers.
Water Tower Contaminants
We think that the fouling was due to contaminants that were carried in the air from around the factory. Each condenser has a water tower which is open to atmosphere. The condenser cooling water enters the cooling tower at the top. It runs down along plastic slats which are stacked on top of each other. In the opposite direction, air is blown up using large blowers. The air flow cools down the water, which then returns to the condenser. This process is how the contaminants from the air end up in the water.
This is an algebraic way of saying that there is twice as much cooling as is needed. Where N is an amount of something and +1 means another one. Redundancy is needed when a process is critical. In this instance, the factory would grind to a halt if the chillers went down. Therefore, only two of the 4 chillers run at any one time.
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A sequencer is available to switch between the chillers when they go into fault and to balance the compressor run hours. We decided to start work on Chiller 1 as this was a system in standby. The next chiller in standby was Chiller 2. After this chiller had been overhauled, we switched Chiller 3 off which brought Chiller 1 on. Then, when we isolated Chiller 4, the sequencer brought Chiller 3 on. Before leaving site, we temporarily lowered the setpoint for all 4 chillers to watch the sequencer bring all of the chillers on together. We then put the set point back to its usual setting, whereby Chillers 1 and 2 remained running.
Shipping for Chiller Condenser Tube Cleaning
We keep tube cleaning equipment in our stores in Jeddah, Saudi Arabia which we ship to our Middle East customers. We also have tube cleaning equipment in our stores at Head Office in Manchester, UK. We use a pallet shipping company based in Rochdale to ship parts, materials and equipment overseas. Therefore, we packed all of the necessary equipment on to a pallet, then shipped it to Cadiz. For the consumables used on the job, we have suppliers in Spain, but we usually prefer to ship these smaller things from the UK along with the equipment. This is because our engineers are more used to the brands and types of consumables that we get from our UK suppliers.
RAMS for Chiller Condenser Tube Cleaning
All of our paperwork, Tick Sheets and Risk Assessment Method Statements have been professionally translated into Spanish. Therefore, our Spanish engineer carried out a site survey to assess the risks, he then sent a report to Head Office. We decided upon the appropriate measures to control the risks, then sent the RAMS to site prior to the visit.
Permit to Work for Chiller Condenser Tube Cleaning
The onsite health and safety officer looked at our RAMS and decided how to compose his Permit to Work. Then, both of our engineers signed it at the start and at completion of the job.
Walk Round before Chiller Condenser Tube Cleaning
On completion of the paperwork, our engineers, the onsite health and safety officer and an onsite engineer had a walk round to assess the job. This was to make sure that all was okay to carry out the tube cleaning.
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Chiller Condenser Tube Cleaning Operation
Each of the 4 chillers was worked on in turn in the order as described above.
Each condenser was valved off with the configuration of the pipework changed. This was to ensure that the flow rates were correct for all 4 of the chillers. Otherwise, a catastrophic failure of the chillers could occur.
The condensers were then drained down and vented using a selection of fittings that were shipped out with our equipment.
Our engineers unbolted the end plates and lifted them to the side using specialist lifting equipment.
In Spain they just use a 220v supply for electrical equipment instead of the 110v equipment that we commonly use in the UK. As our equipment is 110v, we shipped our transformer on the pallet. Once the equipment was set up- we carried out the cleaning of each condenser tube according to standard industry guidelines.
The seal on the end plates is prone to leak after breaking into the system so we shipped replacements from Head Office. Our engineers found it a fiddly job as the new seals had been folded up in a different position in the packet. This meant that they kept jumping out of the grooves. When the seals eventually remained in the grooves, the end plates were bolted into position according to the correct torque setting.
Air Purge and Valve Configuration
The air was purged from the shell of the condensers and the valve configuration was returned to the original position.
Each of the 4 chillers was run tested in turn and the system readings were recorded on our paperwork. A dramatic increase in performance was recorded on each system. The refrigerant pressures and temperatures were a lot better and the coefficient of performance was markedly higher. This means a lower carbon footprint and lower electricity costs.
Chiller Tube Cleaning Service
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