[Gasification] soot on heat exchanger tubes

[N. Selvakumar]

Hi all,

The deposition of soot on heat exchanger surface could be exploited for
removing these contaminates efficiently.

The research projects at IIT Bombay have aimed at design of such a PG cooling
/ cleaning system through understanding of the involved aerosol processes. 
The study undertaken as envisaged has unfolded a design pathway leading to a
system in which particulate matter and tar separation can be affected by use
of a well designed temperature profile in a simple pipe conduit at the exit of
a gasifier.  These processes do not need any water supply and promise
considerably clean gas devoid of tar and PM.  An actual system using the
information generated has been designed, being fabricated and under testing.

The project in series focused on understanding the behaviour of particle and
tar vapour interaction and transport processes with a controlled
time-temperature history. This was essential to understand the development of
appropriate design strategies for clean-up of producer gas to be used in power
generation by I.C. Engines which require stringent clean-up levels.

A computer code was developed for the particle-vapour interaction,
representing nucleation, condensation and coagulation processes and other
transport processes. The bench scale experiments was done to verify the
computer simulation.

The deposition of soot/tar on the pipe wall involves many process which is
complex to model and test by experiments. However, the nature and behaviour of
deposition is depends on the information of particle size distribution and tar
species. I can not say further on this because i yet to submit my PhD thesis.
This work was done with the supervison of Professor P.P.Parikh and Professor.
Virendra Sethi at IIT Bombay, India.


We are in the process of publishing this work in Biomass and Bioenergy. The
list of published conference paper could be found at
http://www.cese.iitb.ac.in/people/facinfo.php?id=vsethi

Regards
Selvakumar
______________________________________

With Regards
N. Selvakumar
Research Scholar
CESE, IIT Bombay
Powai,Mumbai
India 400 076

doug.williams wrote:
> Hi Rex,
>
> You Ask:
>> Please can you elaborate more on the soot formation in cooling gas down.
>> While I knew that soot occurs, I got an undertone from your comment that
>> it may coat the cooling heat exchanger. Has this been your experience?
>
> Remember that I said it depends on where the exchanger is located in the
> system. Until the gas is stripped of dust, it will coat the inside of any
> tubing.
>
>> If it does coat, what do you do to keep it from doing so or to get
>> it off?
>
> You have to open them up and scrape the tubes, or have some type of
> mechanized scraper system. The rate of sooting depends on many factors,
> which is why designing these cooling systems is more than just calculations.
> For sure you will need to know what quality of gas you are going to cool,
> because if pyrolisis oils are present, nothing will stop the tubes fouling.
> Producer gas is a very challenging task master, and many normal design rules
> just do not apply.
>
> The alternative is wet scrubbers, or water sprays in the tubes, but then it
> becomes a liquid disposal problem.
>
> Regards,
> Doug Williams,
> Fluidyne.
>
>
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