4 replies to this topic

[ASKUMAR]

Hi

i am a new member.

Can any one help me.

we are planning to commission a mechanical refrigeration (propane chiller) for natural gas hydrocarbon dew point control.

i am looking for the process parameters like pressure & temperature in stages.

we need to maintain -4 to -9.5 deg F in the chiller outlet gas to low temperature separator.

Regards
ASKUMAR

[Art Montemayor]

Askumar:

Please furnish us with all basic data and details about your unit. If you don't, this thread will grow with increased amount of questions, guesses, conjectures, and finally frustration in not being able to identify the “parameters” you mention. For example:

• If you are commissioning, then this must be a NEW, installed unit. Correct?
• If it is a new unit, who designed it and who built it? The purchase certainly involved the procurement of full pre-commissioning, commissioning, startup, normal operation, and maintenance instructions. Correct?
• What TYPE of mechanical compressor is involved? Reciprocating or centrifugal? How many stages? what capacity? what HP? what type of driver? What speed(s)? What capacity controls? What kind of instrumentation?
• Who manufactured the compressor?
• What type of condenser? What cooling fluid in condenser? what temperatures and pressures?
• The manufacturer (or the Packager) surely furnished a complete and detailed operating manual that clearly details all the related operating pressures and temperatures for the refrigerant, the lubricating oil, and the cooling fluid. Correct?

As you can see, the above information should be what is needed to identify the process parameters in the various stages.
Await your response.

[ASKUMAR]

Hi Art Montemayor
You are right. This unit is new, installed & pre commissioning done. Waiting for propane charging & commissioning.
The supply is free on board. We don’t find proper documentation from the supplier.
Sorry, I don’t want to mention the supplier name here.
The unit installed with MYCOM make screw compressor 250 BHP (model P200 LUDH), accessories like lube oil pump, Lube oil separator, 0.22 MMBTU/ Hr duty lube oil Cooler & all interlock with Murphy control panel. Compressor coupled with 300 hp / 3000 rpm flame proof motor.
The condenser is FABSCO make air cooled heat exchanger (fin fan cooler with Louvers) 1.11 MMBTU/hr duty.
Unfortunately the manufacturer given maintenance manual of some installed components , No any operation manual & procedure.
Hydrocarbon dew point control unit is equipped with Propane receiver, Economizer, kittle type chiller 0.74 MMBTU / hr duty with -20 deg F design temperature in both shell & tube side. Low temperature separator. Complete system is installed with necessary PCV, TCV, LCV, PT, TT & ext.
From the Field control panel program, we got most of the set values.
We are looking for the operating procedure & expected operation parameters.
We have skilled team in all area. We have most of the engineering details. Only we need operating parameters to proceed further.
Regards
ASKUMAR

[Art Montemayor]

Askumar:

Thank you very much for such valuable and detailed information. I’m sorry I had to be direct and ask you for this, but I have been in the same, similar situation many times before in foreign locations without any supplier information and little or no engineering support information.

I have worked as Engineering Manager for a refrigeration company and we packaged Mycom screw compressors in the late 1980’s, so I am very familiar with what I suspect is happening on your side. I don’t know where you are located or if you are with the engineering contractor or the owner of the facility, but I am going to assume you represent the engineering contractor and are thereby responsible for the commissioning and startup of this unit that has been purchased by your engineering contractor company and you had no direct hand or knowledge of the design, specification, or purchasing of this unit that has just arrived on the project site – without any information on for commissioning and startup. Your purchasing department bought the unit and did not specify or order pre-commissioning, commissioning, and startup services from the “Packager” (the unit’s designer and supplier). The purchasing contract did not specify the generation, documentation, and approval of all chiller unit calculations. You, in the field now must commission and startup the unit – with what you have been given and delivered. Correct?

If the above is correct, then I also suspect that the Mycom model is a FLOODED screw. This means that the design and packaging of this machine is very specific for efficient oil separation, filtration, and return within a closed oil system that ensures efficient flooding of the screw chambers. I also suspect that this model is designed for capacity control with a sliding vane and for unloaded startup and shutdown. The compressor is probably designed for constant speed operation, so the capacity control function is an important one for operation as well as for startup and shutdown.

If the Packager supplier has complied with all its responsibilities according to the purchasing contract, and you have no further hope of receiving any more information or help from them, then you are STUCK in the field with a very big problem. What I have done when abandoned by my own detailed engineering and purchasing departments is that I have immediately contacted the machine’s representative – in this case, Mycom. This is what I strongly recommend that you do if you are still lacking the proper, specific operating procedure & normal operation parameters. Mycom is the only other source that can help you if the engineering packager or your engineering department will not. Work with Mycom and ask for their cooperation in protecting the good name they have in the industry.

If you proceed to try to obtain such information from other sources or calculate (or estimate) them on your own, you are assuming total responsibility for the results – especially if the outcome is wrong or bad. The proper check-out and testing of the oil system in this type of screw compressor is critical to this future service. So is the capacity control mechanism and instrumentation. There is a specific, detailed Mycom procedure for this and it is highly recommended that Mycom’s procedure be followed – to the letter. The Mycom is a good machine; however, it is very specific in its design and instrumentation and Mycom protects its name and reputation by issuing such procedures and practices with all its world-wide packagers. If you have not received this information nor have you been trained by the packager or by Mycom, then you need their help or assistance in this matter. If you don’t do this, you leave the project in jeopardy with the possibility of doing startup or operational damage to a perfectly good machine or system. I don’t believe you are being paid enough to be able to take that kind of professional risk – and you should not be expected to take such a risk.

When I was a young field project engineer, I often ran into similar situations. As a senior project manager in the last 30 years, I have constantly made sure that all such processing units and equipment are not only properly designed and specified, but also purchased according to corporate standards and project requirements. Detailed calculations, drawings, and specifications generated by all suppliers should always be reviewed, checked, and approved by the purchaser and made part of the supply documentation package together with the equipment. In fact, this also involves the physical packaging, painting, crating, protection, and preparation for shipment to project site – complete with project site inspection, approval and official acceptance by a project representative – the site project manager. This type of procedure is what I am used to operating in a project and what I would expect. This type of procedure highlights responsibility and accountability on the part of all project members and aides in ensuring that you receive all that you need to successfully make the installation, commissioning, and startup.

Even though this is a rather small chiller unit, I presume it is still important part of your project and must be successfully started up. I wish I could personally help you out in the field because I know these units very well and feel confident of pre-commissioning, commissioning, and starting them up. However, the level of responsibility and accountability must be preserved. If you try to do it yourself without the proper, documented procedure, you will be taking on a very large risk. That is why you must obtain the assistance of the packager-designer or, in their absence, Mycom.

I hope this experience is of some help.

[ASKUMAR]

Hi Art Montemayor

Thanks for your reply.

Yes, it is very defficult & high risk to commissioning a equipment in hydrocarbon industries without proper documents.

we are the operator. we are marginal field operator. No EPC company, we did our own project.

we are operating last one year.

Mycom Commissioning engineer will be available during commissioning. he will take care the compressor part & accessory like lube oil system.

We have to take care the process tunning of hydrocarbon dew point control package with available information.

Thanks for your responce.

Regards
A.Senthil Kumar