Shell & Tube Chiller Evaporator Maintenance

Grey shell & tube chiller evaporator being maintained with centrifugal compressor above

Shell & Tube Chiller Evaporator Maintenance

With shell & tube chiller evaporator maintenance to be carried out- it was time to sign the permit to work and get going. There are 5 chillers in total, but 1 of the chillers had been dismantled by the previous company and is unlikely to run again. This left 4 flooded systems to be maintained while the factory was still in production. Therefore, it had been decided in the Method Statement that one chiller would be done at a time. The plant had been designed with N+1 in mind, as it is critical not to loose the process- causing a factory shutdown. This means that so long as 2 of the chillers are running, there will be no loss in production. With 1 chiller out of service and another being worked on, this left 3 chillers in operation. If 1 were to fail, then there would still be the minimum of 2 left running.

Hire Chillers

In the unlikely event that 2 of the 3 chillers left running were to fail, an action plan was in place to lift in 1 MW of hire chillers.

Pump Sets and Hoses

The hire chillers would come with 2 engineers to pipe the pump sets into the onsite water system. This water system has been designed with this in mind so ‘stab ins’ have been built into it with shut off valves for the connection of temporary hoses.

Vanes

The chilled water is close control with a critical 6°C to 8°C set point. The chillers in the photo are very good at achieving this close control as they use vanes on the inlet to the suction. These vanes can be adjusted from anywhere between fully closed, with a small amount of bypassing, to fully open.

0161 370 7193

service@maximuschillers.com

Contact Form

Buffer Vessel

The hire chillers, on the other hand would not be close control. They would be multiple system chillers with various stages of loading on each chiller. One 600 kW chiller and another 400 kW. Each of the chillers onsite are 1.3 MW, but as they never run at 100% the onsite maintenance manager agreed to the proposal. It is unlikely that this plan would be needed, but planning for it is critical. A 10,000 ltr buffer vessel was decided upon to make the hire chillers close control. The chillers discharge into the buffer vessel, then the water mixes around before returning back to the chillers. The process water too being discharged into the buffer vessel before returning to the process. The position of the inlet and outlet on both water systems being strategically decided upon to ensure a steady exchange of heat and a smooth water out temperature back to the process.

Valve off and Drain Down

The Water In and Water Out pipes were valved off and the contents of the evaporator drained down. There was no glycol or chemicals in the water system which made the job easy. Otherwise, the water in the evaporator would have to have been pumped into vessels for disposal.

End Plate Removal during Shell & Tube Chiller Evaporator Maintenance

The lift and shift team were on site to assist with the removal of the end plate. After the bolts were removed, they attached their lifting eyes and straps, then lifted the end plate to the side.

Evaporator Cleaning 

We have in our stores a specialist evaporator cleaning tool. After a period of time, the evaporator tubes become fouled with impurities picked up from the water system. Also, contaminants get in from the air into the water tower. The strainer has some effect, but thermal insulation builds up on the water side of the tubes. It prevents latent heat being absorbed into the fridge system from the process. After the cleaning process, the efficiency of the copper tubes was increased to the same level as when the chiller was new. This is part of what we call the MAXIMUS ADVANTAGE Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere. 

Reassembly after Shell & Tube Chiller Evaporator Maintenance

The seal was replaced from our range of seal sizes, on the shelf in our stores. The reassembly being the reverse of the strip down, the lift and shift team aligning the end plate for refitting on guide runners. It was then tightened to the correct torque setting. A little at a time, the water system valves were opened until full flow and water system pressure was achieved. No leaks occurred, so it was time to go on to the next phase of the job…

0161 370 7193

service@maximuschillers.com

Contact Form

Run Up after Shell & Tube Chiller Evaporator Maintenance

After bringing this chiller back online, it went through a timer, then loaded up steadily to 68%. The refrigerant system readings had been taken previously, so they were compared to the readings taken after the job. A lot more heat transfer being achieved with more latent heat being absorbed from the process.

Remaining Chillers

The above mentioned process was repeated to the remaining chillers one at a time. No issues were encountered and the whole job proceeded steadily to completion.

Compressor Loading

The load from the factory is very steady, so each time another chiller evaporator was cleaned, the row of chillers would unload slightly. They were running at 72% on arrival, then 68%, then 63% then 59%. This was demonstrated to the customer as a visual way of proving how we had improved the efficiency of his plant. Compressor unloading uses less electricity, so lower carbon emissions and a lower electricity bill are the direct result of our maintenance. Also, kilowatt hour meters are linked to the maintenance manager's computer for monitoring.

Shell & Tube Evaporator Chiller Maintenance Tidiness

As with all of our jobs, the work location of the chillers was left in a better condition than when we arrived. Any waste and unused items being recycled or returned to the stores on site or the stores at our Head Office. The chillers being wiped down and the end plates re painted. With regular maintenance, we at Maximus Chillers will take years off the life of your plant. It is not unusual for us to keep this kind of plant running for more than 50 years.

Related Articles:
Chiller Parts Supplier

Chiller Compressors

Air Cooled Chiller Condenser Maintenance

Screw Chiller Compressor Maintenance

Scroll Chiller Compressor Maintenance

Chiller Controls

Centrifugal Chiller Compressor Maintenance

Chiller Condensers

Reciprocating Chiller Compressor Maintenance

Chiller Controls Company

To read more about shell & tube chiller evaporators hit the Tag at the top of the page.

Read more about shell and tube heat exchangers on Wikipedia | Click Here


A pile of completed chiller maintenance checklists on a table

Chiller Maintenance Checklist

Introducing a series of in depth news articles, this time featuring the chiller maintenance checklist:

News Article No.1

This article has been written with you- the customer in mind. Read below for practical advice on how to keep your chillers in the best condition.

Each day when you walk round, you can check to see if your plant is starting to malfunction. Become accustomed with the usual readings to help you diagnose the faults.

Here are the things to check for and how to remedy them:

Water System Pressure

Keep an eye on the pressure in the water system.

Small Chiller Maintenance Checklist

On a small chiller, there will be a water outlet pressure gauge. Make a mark on the gauge where the pressure is when the chiller is in good working order. You can use this mark to notice if the pressure is starting to drop off.

Strainer

The most common cause for low water system pressure is a blocked strainer. It is usually a ‘Y’ type with a bolted fitting. With the chiller off and the water system valves closed, unscrew it and check for debris. If it is blocked, make a note of how long it took to block, then add the cleaning of the strainer into the periodic maintenance schedule.

Pump

Ensure the pump rotation is correct by checking that the cooling fan is sucking into the pump. If it is going backwards: isolate electrically, then swap any 2 of the 3 phase wires. Brush down the inlet to the cooling fan to ensure good air flow and a cool pump motor.

Large Chiller Maintenance Checklist

On a large chiller, the water system pressures may be available in the controller- have a look through the menus. The pressure will be measured in bar. Another popular method on a large chiller is a flow meter. This may be a stand alone device on the chiller panel, or on a control panel nearby. It will read in m3/hr. Check to see if the pressure or flow is lower than usual. If so, ring one of our trained professionals.

0161 370 7193

service@maximuschillers.com

Contact Form

Water System Temperature

The chiller should be:

  • Matching the load and running continuously.
  • Loading and unloading in sequence with other chillers.
  • Going through a cycle and achieving set point.

In any case, you will become accustomed with the usual chilled water temperature according to varying load conditions. If the plant is struggling to achieve set point, or is running higher than usual- this is a sign of system faults.

Walk along the chillers that feed the same water system and make a log of the faults showing on the controllers.

Here are the things to check when you have high water system temperature:

Small Chiller Maintenance Checklist

Low Pressure

If the chiller has a low pressure gauge, look to see if the pressure is lower than usual. If so, this is a sign of refrigerant shortage in the plate evaporator. A scheduled visit from one of our trained engineers to carry out a pressure test can be arranged.

Breakers

Look for any breakers that have tripped in the panel. One reset can be carried out by a qualified onsite electrician. If the fault reoccurs- ring our support team. If the scroll compressor has tripped, check to see if the compressor is hot. If so, isolate and do not attempt a restart.

Condenser

A blocked condenser will inhibit the rejection of heat. Brush it down and give it a rinse with water. A common occurrence onsite with some condenser designs is a panel being left off with the chiller running! This happens when the onsite engineers are fault finding another issue with the chiller. The fans will suck through the opening as this is the easiest path. The gauge will be higher than usual as the condenser builds in pressure. A high pressure trip out will occur.

High Pressure Switch

To locate the switch- first identify the discharge pipe. It is the smaller of the 2 pipes on the compressor. The high pressure switch will either be bolted onto the pipe, or a thin pipe will lead from the discharge to the frame of the chiller. In any case, you are looking for a small box with a button and a wire leading to the panel. Press the button and you should hear it click. If this fault reoccurs- ring our technical support desk.

Large Chiller Maintenance Checklist

Suction

Should there be a refrigerant shortage, the controller will display a pre alarm like 'suction limiting' This is the controller preventing the compressor from loading up, so as to prevent a low pressure trip out. As above, one of our team of engineers can be sent to site to resolve the issue.

Discharge

If the controller is showing 'discharge limiting' this is a sign of a condenser issue. A full strip down and cleaning of the tubes may be required. Ring our technical support desk for further advice.

0161 370 7193

service@maximuschillers.com

Contact Form

Chiller Remote Monitoring

We at maximus chiller can install remote monitoring systems to your chillers so we can fault find and diagnose from a laptop. This means we can give you real time advice over the phone. Now you are accustomed with our chiller maintenance checklist, you can give feedback regarding the plant to assist our engineer.

Parts

For our contract maintenance customers: a range of commonly used parts are kept onsite to reduce downtime. We can give practical, step by step advice on the fitting of parts. We often carry out video calls with our customers, as chiller data plates, parts and components can be easier to show than describe.

Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere- The MAXIMUS ADVANTAGE™

Related Articles:
Air Cooled Chiller Planned Maintenance

Water Chiller Maintenance

Process Chiller Maintenance Visit

Chilled Water System Maintenance

Centrifugal Chiller Maintenance

Industrial Chiller Maintenance

Air Cooled Chiller Condenser Maintenance

Glycol Chiller Maintenance

Chiller Maintenance Schedule

Air Cooled Chiller Maintenance

Chiller Maintenance Company

Chilling Plant Maintenance

Preventative Chiller Maintenance

To read more about air cooled chiller condensers hit the Tag at the top of the page.

Read more about chillers on Wikipedia | Click Here


Yellow oil drums, ammonia refrigerant cylinders and flammable flushing agent of chiller supplier

Chiller Parts Supplier

Chiller Parts Supplier of Compressors

Centrifugal

As a chiller parts supplier, all kinds of centrifugal compressors are remanufactured in our workshop. With an overhead gantry crane and specialist equipment to hand- Maximus Chillers completes the picture. We have a lift and shift team who are skilled at getting the compressor out of the most awkward locations. A variety of lifting equipment is used, including 3 phase electric hoists and trollies. Our team do this kind of work all the time, so they are accustomed to overcoming all the difficulties and obstacles.

Screw

Screw compressors are remanufactured on the bench. With compressed air and bearing tools- our skilled technicians are seasoned in high tolerance measurements. The bearing clearance and shaft run out are accurately measured and adjusted. This means that the useful life of the compressor is extended, often to beyond the lifespan of the chiller.

Scroll

We have a range of off the shelf Copeland compressors for a fast lead time on process chiller repairs. These can be sent to site on the day using our fast door to door supply chain. We have all the sizes of compressor available. The pipework and mountings can be adapted too. This means that if your compressor is a different make with a longer lead time- our compressor will be fitted and adapted to your machine- fast!

Chiller Parts Supplier of Condensers

Air Cooled

When the condenser on an air cooled chiller is in poor condition- our site survey team will attend to measure up for a new bespoke condenser. This is done free of charge and ensures that the new condenser will fit easily into the old chiller. The exact subcooling requirement of the old condenser is taken into account which is duplicated on to the new condenser. This means a like for like swap can take place even when the old condenser is obsolete.

Shell and Tube

This type of condenser is used on water cooled chillers. It is protected from contaminants by a strainer on the water system. We have these condensers built to order by our bespoke manufacturer. They are shipped to site on an overnight delivery, so we can get straight down to work in the morning. We therefore minimise downtime in the swap out of this part.

Chiller Parts Supplier of Evaporators

Shell and tube are the most popular type of evaporator for large chillers. The low temperature refrigerant is on the outside of the tubes in liquid form. The water is pumped through the tubes, releasing heat from the process and into the refrigerant. This is latent heat as the liquid refrigerant boils off into a vapour. Where the heat exchange does not greatly improve after cleaning, we recommend replacing this part.

0161 370 7193

service@maximuschillers.com

Contact Form

Vibration Eliminators

We have all of the sizes of anacondas on the shelf in our stores. This saves on the delivery time to site when your process is off due to the chiller. Maximus Chillers will get you up and running- fast! We can also fit flexible vibration hoses which achieve the same result as anacondas. Whereas two anacondas are fitted vertically and horizontally, only one, long vibration hose is needed.

Chiller Parts Supplier of Flushing Agent

When things go wrong, we stock a solvent based flushing agent which is blown through the system using nitrogen. The waste product is caught on the far end in drums that come with the kit. This is then returned to the suppliers for recycling.

Refrigerant Economizers

These are another term for a subcooler. If the refrigerant is further subcooled after the condenser- the system will run more efficiently. This part usually takes the form of a plate heat exchanger with an expansion valve providing the refrigeration effect needed to further subcool the remaining liquid.

Chiller Parts Supplier of Pressure Transducers

We can make temporary repairs to faulty pressure transducers using our test equipment. This will keep your plant running while the part arrives on site. Then we can get your chiller up and running with the correct readings in the controls. This will assist your onsite maintenance engineers in giving us useful readings when we are in communications over the phone.

Chiller Parts Supplier of Ammonia and HFC Refrigerant

A full selection of refrigerants are available including: anhydrous ammonia, R407c, R134a and R410a. These refrigerants come in small 12kg, midi 26kg, large 56kg and bomb 800kg sizes. Our vehicles are equipped with tail lifts and lifting gear to facilitate delivery. We can therefore arrange the delivery and collection of refrigerant at your site, free of charge, anywhere in the UK. For our overseas customers, we arrange the transportation from the local suppliers.

Chiller Parts Supplier of Oil

Low, medium and high viscosity oils in 5ltr cans and 20ltr drums are ready for shipping from our storage area. It is critical to select the correct grade of compressor oil as bearing wear and reduced service life will result. We take regular samples of this oil to see if things are starting to go wrong in the compressor. We can then nip these problems in the bud, giving you dramatic savings.

Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere- The MAXIMUS ADVANTAGE™

Related Articles:
Screw Chiller Compressor Maintenance

Chiller Compressors

Air Cooled Chiller Condenser Maintenance

Shell & Tube Evaporator Maintenance

Scroll Chiller Compressor Maintenance

Chiller Controls

Centrifugal Chiller Compressor Maintenance

Chiller Condensers

Reciprocating Chiller Compressor Maintenance

Chiller Controls Company

To read more about chiller evaporators hit the Tag at the top of the page.

Read more about the centrifugal vapour compressor at the Institute of Refrigeration | Click Here


Translate