Control.com - Nerds in Control

Hi guys,

I'm new in instrumentation,so I'd like to ask your help to solve my problem.

I want to measure the coal-gas pressure inside the Fluidized bed Gasifier reactor (gasification reactor) using Pressure transmitter (PT).

The problem is the temperature is quite high, 1478oF, and the fluidized particle is rough coal with 3mm diameter; at the other side PT measured temperature only allowed to 500oF.

The questions are:
1. How to install the PT, do I need to install another component to protect the PT from overheat temperature?
2. How bad is the abrasion effect caused by rough coal in SS tube (impulse pipe)? (coal fluidized velocity: 4m/s in reactor)

You just need to isolate the transmitter from the heat with a few feet of tubing. How you place the tube into the bed is critical, you need to avoid plugging. I expect the tube should slope down so that any solids that enter the tube fall out again.

It might also help to have a small flow of purge gas.

Roy

Thanks Roy for the respond. However I still have doubt how to make small flow of purge gas.

In my concept:
from the tapping point, connected with slope down ss tube (3m length? is that enough), then install a tee (3-way) connector at <=1/3 length from the end of the tube.

about the tee connector:
one way connected with the PT, the other way connected to the needle valve for small flow of purge gas line.

What do you think?
need your help , thanks :)

Yes, I think you have the right idea. Even a meter of tubing will be more than enough to isolate the heat from transmitter, gas and SS tubing are poor conductors of heat. You can add the purge gas either at the transmitter or as you say closer to the tapping point. You may find once you are operating that you can turn the purge off altogether. As for the tee I would connect the transmitter on to whichever connection is facing up. The purge gas can be connected to a horizontal, just avoid having anything pointing down, always slope down toward the bed.

You may find you have to try a couple of times to get it right.
Instead of a needle valve and rotameter you could also try just a valve and give it a blast now and then or have a steady connection from your fluidizing source.

Send me a sketch if you want me to comment on the installation
roy_matson at yahoo.ca

Good Luck
Roy

1) You have two challenges:

- The Process temperature
- Fluidized particles

You can use a Diaphragm seal (refer Rosemount 1199 diaphragm Seal systems)with a suitable fill fluid (may be syltherm 800 Silicone - this is used upto 750DegC)

Please do note that the Material of Lower as well as upper housing and capillary shall be able to with stand your process temperature.
Please Check for the Nozzle material of construction of gasification reactor) You may advise the vendor to provide diaphragm seal with the same material.

For taking care of Fluidized particle process shall advise purge connection.

when you use a diaphragm seal , you cannot use SS tubing simultaneously