How to measure furnace pressure using a differential pressure transmitter
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When the boilers in our plant are operating normally, the negative pressure in the furnace chamber is required to be between -150 and -300 Pa. Recently, it was found that the negative pressure couldn’t reach this value (the value displayed on the operation interface; the same applies hereafter). The boiler is controlled by a PLC, with monitoring being carried out via a host computer; I asked the boiler operator to adjust the pressure to positive values (by increasing the airflow from the blower so that the displayed value rises until it becomes an integer). A small gap was created at the inlet to the furnace, and the pressure was adjusted until it reached 110 Pa to 120 Pa positive, yet air continued to be drawn into the furnace. The sensor used is the Yokokawa EJA110A, with a measurement range of from -500 Pa to +1000 Pa; the pressure measuring tube is connected to the L port, while the H port is used for venting. The current reality is that the measured pressure is inaccurate; how can we make the measured values as close as possible to the actual values? Also, I’m not sure when it started that I wasn’t allowed to. The quantity conversion chart for %5Bimg=120,120%5D is shown as illustrated in %5Bimg%5D
First, check whether the pressure introduction pipeline is unobstructed. Then check the transmitter zero offset; if that doesn’t work, try another transmitter.
The Rosemount differential pressure transmitter model 3051S will work
For the furnace negative pressure, we have always measured it as positive pressure, using the same measurement range; negative pressure is measured by monitoring the vent
It seems the positive and negative voltage measurements of the poster are reversed.
All one can do is laugh; with such a testing method, it’s likely that the pressure will always be positive.
This post was last edited by xuguohui1987 on 2017-1-19 at 22:50. First of all, the wrong transmitter was chosen; do not use a regular differential pressure transmitter – an EJA120 micro-differential pressure transmitter should be used instead. Set the range to -500Pa to 500Pa. Connect the pressure transducer to positive pressure, and it’s best to place the negative pressure side inside a wind shield: lol
The 3051S series differential transformers work quite well