3 replies to this topic

[sarah khan]

for hydrocarbon dew point control why mechanical refrigeration method is better than other technologies like JT method or supersonic method or turboexpander method??
nd vl it be feasible/ possible to use a mixture of refrigerants in mechanical refrigeration method than using a single refrigerant like propane??

[Art Montemayor]

Your questions are answered below:

For hydrocarbon dew point control, why is the mechanical refrigeration method better than other technologies such as JT method or supersonic method or turboexpander method??
Mechanical refrigeration is well understood, flexible in designing to different needs and specifications, and is the current state-of-the-art. The design required dew point can be controlled easily and with conventional equipment and instruments.
I don’t know anything about a JT method or a supersonic method.
A turboexpander application is complex and expensive and should be used where large, steady, and constant capacities are needed. It is more difficult to control and turn-down.

And will it be feasible/ possible to use a mixture of refrigerants in mechanical refrigeration method than using a single refrigerant like propane??
Of course you can use a variety of refrigerant mixtures that are “environmentally friendly” with a mechanical refrigeration unit. You can also use an old “standard” and efficient refrigerant – like ammonia.

[sarah khan]

sir firstly thankyou so very mch for ur reply.will you plz explain the term CURRENT STATE OF ART and dnt u thnk so being the oldest technique it must has some drawbacks or limitations sort of things as other technologies which are more efficient than this are being developed and empolyed.
and what percentage of the worlds natural gas processing industries are still using this method specifically for HCDP.?

[Art Montemayor]

Sarah:

For the sake of clarity and clear understanding while discussing engineering topics, please do not use “Texting” spelling, composition and words. It is difficult to understand and communicate with this type of codified writing that is based on social chatter rather than technical topics.

By the term “state-of-the-art”, it is meant that the current technology is what it is. There are no “clever”, unique, pioneering, or “superior” technologies being employed industrially at present – other than the basic thermodynamic designs that are being taught in university. What – exactly – do you mean to ask by stating that “other technologies which are more efficient than this are being developed and empolyed”? Are you trying to refer to Thermoacoustic (TA) Refrigeration? If so, please just state it specifically.

TA refrigeration is nothing “new” as far as technology is concerned. Lord Rayleigh proposed it well over a hundred years ago – before the development of mechanical refrigeration. Thermoacoustic is the interaction between heat and sound and the TA refrigerator uses the energy of sound or pressure waves to bring about refrigeration. Research on TA refrigeration didn't start until 1969 - so it is still in the "embryo" stage. The main components of a TA refrigerator are:

• The resonator
• The stack
• The acoustic driver
• The heat exchangers

The most efficient TA devices built to date have an efficiency approaching 40% of the Carnot limit – or about 20 to 30% overall.

Just because you believe that mechanical refrigeration is “the oldest technique” that “it must has some drawbacks or limitations”. This is erroneous and flawed logic on your part. You should do your homework first, before making such a statement. Investigate the existing resulting capital requirements and energy efficiencies of both process today, and THEN make your conculusions.

I don’t know what you mean by HCDP. Please always define your acronyms used. I also don’t know the percentage of the worlds natural gas processing industries still using mechanical refrigeration. But I am willing to bet that when compared with absorption refrigeration, the percentage is very high. Turboexpander refrigeration is never compared by me with mechanical refrigeration. Turboexpander technology is based on the Claude engine and employs process energy to do an adiabatic, reversible expansion of fluids to obtain refrigeration. The entropy of the process is maintained constant.