Posted 02 May 2011 - 09:16 AM
Fallah:
As you well know, there is nothing “theoretical” about an entrance (or exit) loss – and that is the theoretical minimum pressure loss that flowing steam will have as it enters the bonnet of the vaporizer or heat exchanger. Therefore, in the real-life world the pressure in the steam line upstream of the bonnet WILL ALWAYS BE LARGER than the pressure inside the condensate drum. That means that the described “equalization” method will NOT yield the true condensate level in the drum.
Since we have not been given a detailed piping sketch, I am forced to assume that the OP will make the connection wherever he can conveniently do it – not necessarily where it is required for an accurate process indication of the true drum condensate level. Since we are honestly and candidly asked for our recommendations, I cannot give a specific recommendation based on an assumption or guess that the OP will make the connection as close to the bonnet as possible. To do so would be to give a careless and irresponsible recommendation without accountability for the field results. I won’t do that.
You make the statement that there is no “significant difference between Ghasem's configuration and yours in pressure equalization point of view”, but yet you are unable to prove or backup such a statement because of the simple fact that neither you or I are in control of the ultimate and final piping configuration. I can assure you that if I had the desire and the authority to install the equalization line on the steam supply line, that I could do so and cause a MAJOR indication error in the condensate level within the steam bundle inside the exchanger. The fact that I have the ability to purposely design and install such an error into the operation simply means that anyone else could also do the same – but in an innocent, uninformed manner. And that is what I have interpreted as what Ghasem is genuinely trying to avoid happening and why he has generated this query. What I have recommended is not my design or what I have a preference for, but rather what I have identified as the safest, surest, and best way to install a condensate drum in the field with a maximum degree of safe, predictable performance. There is nothing theoretical about it. In fact, it is based on 51 years of empirical field experience.
I am very aware that there are probably a large number of reboilers that are currently operated with an un-recommended configuration without any problems. I know this to be a fact because I have, in the past, had to remedy many such types of installations in the field that once put to the test of design performance and accurate instrumentation control, they started to demonstrate the failure to indicate the true condensate level – leading to faulty operational control and judgment.
In my opinion, any so-called engineering “executive” who decides that he/she can save capital monies by not installing dedicated support for a 3/4" line is a fool and not an experienced and professional engineer. Additionally, any design process engineer who knowingly designs a condensate drum to the bonnet of reboiler and fails to include a 1” nozzle on the bonnet is either un-experienced (and unqualified) or sloppy and irresponsible for the consequences that follow when the operations personnel are taxed to deliver the promised and expected results. The design and field installation of a supported 3/4" line and a 1” nozzle at the time of design and installation is a minuscule cost that isn’t even included in the normal contingency costs of any project such as what we are discussing. Therefore, to fail to include or discuss what I have recommended in the original design and during the operational review is, in my opinion, a professional failure on the part of the design engineer. And I have interpreted that Ghasem is seeking such comments in order to evaluate and reach his own decision regarding his installation.
I am not seeking to offer nor impose what I perceive as MY design. I want our members to have as many diversified comments as can be obtained from our membership in order so that the OP can have an ability to logically select what is the optimum choice for his/her specific installation.
I hope I have responded to your valued comments in a manner that explains my recommendations and their basis.
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Condensate Pot1.pdf 140.74KB
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