What issues?

Typical issues around antisurge controller in centrifugal compressors are, for example:

- The recycle valve (or blow-off valve, depending on the application) is partially open in normal operation. This causes a big waste of energy.

- The recycle valve (or blow-off valve, depending on the application) opens too many times (when there is not a real risk of surge)

- It is not possible to make maintenance because if we disconnect one of the instruments connected to the antisurge controller, the controller wil trip the compressor.

- The antisurge controller is fighting with other controls in the plant, because there is not a good integration betweent them. This causes process inestability.

There are systems that control surge on the market The Air Miser is one the other is the CMC from ingersolrand both use a sophisticated Antisurge Control Response. The Air Miser is made by Compressor Controls Corporation. It is a very exspensive system, The CMC and the Air Miser both were installed at my plant in 1999 at the time the CMC did not control surge as good as the Air Miser so we used the CMC panel for local operation which replaced the old air/elec. system to the CMC panel which was then connected to a Annuciator panel where the Air Miser actually controlled the compressor if set right this system is almost impossiable to surge it throttles back all compressors to its point of surge as long as system wide psi is maintained. It depends on how your facility uses air in the textile industry the air psi must be maintained other wise you will compromise the quality of the finished product. If it is a plant that basically uses air for tools etc. then there maybe times where everyone stops working you get a high psi. on the system because you have no flow which backs off your compressor and forces it to surge. If you had one of theses systems you would save a lot of money. They can even automatically shut down and or start up your machine which can be daisy chained to a PC which can be monitor and log your machinery. We used the Intillution software it is great for this stuff. If you ever had to work with the old pneumatic controls these new digital controls with a nice GUI LED screen is great. Plus you can sit in your office and see what your whole system is doing. However your equipment is only as good as its operators. I had to go in at 2:00am one morning because the leadman had a power failure and could not get the plant up and going again. He had all 7 machines running and every one of them was surging blowing out the top.LOL We normally only run 5 machines.

Hello!

Thank you very much for your advice, it is very good to receive expert feedback from real cases.

From your answer, I understand that we could give the following tips:

TIP nº1: Get an expert company to tune your antisurge controller (or to upgrade it if necessary). It cost money, but the ROI will be almost immediate.

TIP nº2: Implement an HMI to show the operators and maintenance team the compressor operating point with regards to the surge line and also all the signals involved in the antisurge control.

My email is julsaez@gmail.com, what is your email? I would like that we can be in contact to share experience.

Thank you for your remarks. If the blow off valve is open during normal operation then it has been my experience that instruments are not set up properly or not calibrated. What type of controls do you use at your facility? I spent 7 years at as a Master Mechanic in the compressor room at a textile mill. We had seven centac compressors which were made by Ingersoll-rand. I think they have been bought out now I am not sure who bought them. Thats not relevant any way. My email address is ukstoolman@yahoo.com feel free to contact me at any time.

This is very true.

We can so give

TIP Nº3: Check the proper calibration of all the instruments connected to the antisurge controller and to the recycle valve (or blow-off valve, depending on the application) valve.

Other cause for the recycle valve (or blow-off valve, depending on the application) open in normal operation is that the antisurge controller is not properly tuned.

The compressor is wasting energy incompressing the gas to recycle part of it to the compressor suction (or vent part of it, depending on the application), instead of delivering it to the compressor discharge (that is what a compressor is aimed for).

With the years of use, the compressor caracteristic curves can variate (small variations). This means that the surge curve can have also an small change. Then the original tune for the antisurge controller might not be valid for present situation. Other cause that might require the retuning of antisurge controller is when there is a change in the composition of the process gas.

So, we can give

TIP Nº4: Get an expert company to study the compressor characteristic curve and make

a surge mapping exercise and retune your antisurge controller if required. This will help to ensure that the recycle valve (or blow-off valve, depending on the application) only opens when it is strictly necessary to protect the compressor.

Hi julsaez,

We are using few IR CENTAC centrifugal air compressors, however lately we are encounter surge problems .

Pls advise your comments on this matter.

Regards