Sayoub:

In 2003 I helped one of our Student members from Spain in his formal thesis related to the design of an MTBE process plant.  He succeeded in his endeavor at the University of Salamanca - one of the oldest universities in Spain.  As an act of gratitude, he sent me his complete work in a formal printed, 150-page bound book as well as in a CD.  This work contains all the calculations, sketches, drawings, tables, background, and formal written presentation of all the work effort that went into his product - all subjected to review and detailed questions and inquiries.

This includes the basic flow diagram.  The product is in Spanish.  If you are interested I can try to send you a copy of the flow diagram used to generate all the subsequent related calculations.

At present I am 100% dedicated as a caregiver to my wife of 62 years who has medical care needs.  I have entered the Forums again due to a rare availability of free time while my wife rests, so I have had time to read your thread.  Let me know if I can help - but tell us your time schedule or deadlines.

Liquid:

This response to your query may be late from me but I see some trouble for you in trying to recover the flue gas CO2 content from your power boiler and I think its important to pass my experience of many years to you in order to avert any bad financial investment and time possibly put into your proposal.

First and foremost: Although you don’t mention any thing about your proposed process in recovering the CO2, I think I can safely guess that you intend to use Monoethanolamine (MEA) – hopefully at a solution concentration of no more than 15%.

Secondly, you will never have any success in trying to recover the CO2 with any amine.  Your flue gas is contaminated due to too much excess Oxygen.  12% Oxygen will literally burn up your amine, converting it into very corrosive compounds.  You’ll be out of business in less than a year.

Additionally, your CO2 content is too low!  Perhaps you are mistaking your Orsat analysis on the flue gas, but if you are burning bunker C or even #2 Fuel Oil, you should be getting approx. 14% CO2 in your stack gas.

I don’t know what you are burning as fuel and why you are using so much excess combustion air in your boiler (perhaps you are burning bagasse or wood chips) but I can definitely tell you can’t succeed with the data you furnish.

Sorry.  But better you know this up front before investing time and money.  Doing any modeling work in my opinion is a waste of time.  The basic fact is that the input and expected recovery won't work.

Ponnusj:

I’ve designed, built, and operated adsorption dryers for air, CO2, Oxygen, Nitrous Oxide, and other gases to meet conditions of moisture content down to 1 ppm volume.  What you are describing is nothing more than an adsorption dryer for compressed air that relies on the discharge temperature of the associated air compressor discharge temperature as the source of heat for regenerating the spent adsorber bed.

I agree with your suspicions that you can’t expect to save 75% of regeneration heat requirements with the proposed system design.  In order to fully analyze the operation and calculate any energy consumption you have to first state the basic design, such as the very poor moisture removal, the need for more valves, the bigger adsorbent beds, and the required drop in pressure from the compressor discharge.

The pressure drop is a basic requirement in the flow diagram furnished by Breizh.  This is not a result of the adsorbent bed solely.  The basic pressure drop is a requirement in order to divert the hot compressor flow through regeneration and cooling and subsequently enter the drying adsorbent bed.  The IR flow diagram doesn’t show this detail very well, so that need is not perceived.

Basically this system is adequate if you only need -40 F dew point – which isn’t very dry.  And IR doesn’t tell us what compressor discharge temperature is required in order to achieve that dew point.  The normal discharge temperature I would expect is approx. 225 F – which is not very hot considering it has to vaporize the captured water in the spent bed.  A higher discharge temperature would mean a larger required compression ratio – which would mean more hp and more oil decomposition and adsorbent bed contamination.  These factors would be trade-offs and might be acceptable.  It all depends on what one needs, can afford, or tolerate.  There are no free rides or free lunches in life.

Juan:

This reply comes at a late date with regards to your post, but perhaps it may help you understand the correct responses from the veteran Forum members to your basic question:

Are PSV valves a type of safety valve? 

The correct and proper response from such veterans as fallah, Latexman, Breizh, and Bobby Strain should satisfy you and allow you to understand what PSVs are and what is the nature of what they basically do.  This knowledge will allow you to further understand any other name, title or acronym is used to describe the very basic service of safety that these devices do.

As you know, you can call a pig in Venezuela a "chancho", a "cerdo", a "puerco", a "marrano", or "cochino".  But all these names still identify the same animal - a pig.  And so it is with PSV, SV, RV, etc., etc.

I am attaching a document that you should read - sooner than later - to appreciate the importance and the need to know as much as you can about PSVs.

Saludos

 Introduction to Safety Valves.docx   201.36KB   26 downloads

Evelyn:

I just dropped in to see how some of my old professional friends are doing in furnishing excellent, intelligent responses to other engineers with queries.  Your thread interests me because we covered this same issue many times in the past in this forum.  The helpful responses have not changed and they are all highly recommended.

In order to get a detailed, accurate recommendations on how to accomplish what you want to do I highly urge you to respond to Latexman with what he is requesting.  If you do, you will obtain the kind of detailed recommendations and advice that you need to do your project safely and efficiently.  Basically, what is needed is Basic Data, the exact type and size of tank you are planning to inert, the rates of glycerin fill, the availability of the proposed inert nitrogen in flow rate, its pressure and temperature.

The Forum members have to have the above data and information in order to ensure that what they recommend is SAFE engineering design that will not only work, but that will carry out exactly what you require.  Some items of concern I would pass on to you are:

• The API 650 design has a maximlum pressure rating as well as a mazimum vacuum operation.  Be aware that when you enclose this tank with an inert gas you are subject to a potential vacuum condition as well as over-pressure.  You should hold one or several Hazops to ensure that all potential future issues and safety concerns are resolved before going forth.
• The maximum rates of glycerin inlet and outlet flows must be taken into consideration for the operation to be considered safe.
• There may be a difference between the inlet nitrogen temperature and that in the tank (50 C).  What I have done in the past is that I introduced the nitrogen through a submerged pipe in order to allow it to go through the hot (or warm) liquid fluid in order to be preheated before entering the tank's vapor space.  This stabilizes any pressure variations in the vapor space and over-feeding of nitrogen with subsequent vapor purging.
• Take careful consideration of your tank vacuum breaker and pressure relief.  I consider the vacuum breaker as a major item to design carefully.  Any sudden tank leak or major liquid outlet can cause a potential vacuum and tank collapse.
• Constant, available nitrogen supply must always be present.
• Always design for and alert all operating and maintenance personnel about the inherent dangers of nitrogen inside the tank during any mainenance or clean-out.  The nitrogen feed line should be designed with a positive method of removing a section of pipe downstream of the nitrogen feed line block valve.  Never trust that the nitrogen feed block valve is shut closed while doing internal maintenance.
• Nitrogen deaths due to asphyxiation have been far too numerous and can be halted if proper steps are taken.

I hope the above helps.  Saludos.

My best regards to all my old friends.