The bottom part of our atmospheric distillation tower operates at 350oC, and we are giving the superheated steam to the column at around 420-430oC. Let's say, we want to decrease the temperature of superheated steam to 400oC but still it is superheated steam of course. Might it have any effect on the distillation of the products or the quality of the products to decrease the temperature in this manner?
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20/03/2016
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Virendra Kapoor, Petroleum Refining Consultants, vkkapoor9@yahoo.com
Decreasing the temperature of superheated steam from 430 to 400 C would not effect the quality of the products.
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15/01/2016
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Rajkumar Chate, Sulzer, rajkumar.chate@sulzer.com
As mentioned by few of our colleagues the main purpose of stripping steam is to reduce the partial pressure in flash zone. Amount of stripping steam in the system is so low compared with crude oil or even reduced crude oil and even after reducing the temperature of stripping steam you will not notice any change if you keep the same mass flow of steam.
Temperature of steam do not matter much unless you feed water to the column, care should be take that you are not feeding water to column other wise there can be explosion inside the column in stripping section and it may dislodge the trays and it will loose the stripping.
i do not know the goal of reducing the stripping steam temperature but end of the day it will not make significant noticeable difference in yield or column temperature profile unless you vary the stripping steam rate.
Stripping is related to amount of stripping steam you put and stripping section trays design (open area for each tray is important to avoid weeping and loss of efficiency)
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15/12/2015
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S Banik, Centre for High Technology, sbdr@rediffmail.com
Purpose of adding superheated steam is to reduce partial pressure such that further evaporation of bottom material is achieved. Reducing temperature of steam by 20 deg C should not make any difference . However there may be some impact on the hydrodynamics of the contacting device although entrainment from the flash zone may reduce marginally.
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13/12/2015
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Sudhakara Babu Marpudi, Dangote Oil Refinery Company, m_sudhakarababu@yahoo.com
Any process simulation software will give the analysis. However what is the purpose of such reduction (saving some thing and improving profitability)?. Usually the steam superheat is gained free of cost from the heat left out in the Flue gases (after the preheating in the convection bank coils installed ahead of steam coils saturated). This can be reduced by ramping up BFW used for de-superheating (this is additional expense) or by improving heat transfer to the rest of the coils. coming to the basic question : is the superheated steam temp is higher than design? that means the furnace radiation zone coils are not absorbing enough, leaving much with the flue gases to pass on to convection bank. That probably also means the flames are too long and are the burning is taking place near the arch. One needs to check all these issues.
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12/12/2015
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Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
Temperature of the steam has minimal impact on the stripping effect. The stripping comes primarily from the reduction in hydrocarbon partial that the steam causes. Hotter steam adds a tiny amount of sensible heat to the system but you are unlikely to notice any difference in yields.
The primary driver for superheated steam is to make sure that you are injecting steam into the tower and not water. Superheating steam minimizes condensation in the steam line, thus reducing risk of liquid water getting into the column, which could explosively vaporize and damage tower internals (or worse)
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12/12/2015
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Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
Compared with changing the mass flow rate, no noticeable difference.
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11/12/2015
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keith bowers, B and B Consulting, kebowers47@gmail.com
Of course. Reducing the enthalpy of the steam will reduce the stripping efficiency
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