On-stream analyzer sample returns
On-stream analyzer sample returns is a topic that needs careful though. Most of the sample flow of 60-100 liters/minute is not used by the analyzer and needs to be returned to the process. There are a few different options at hand.
First of all one should decide if samples should be returned to different places or if all can go to the same place, usually back to the first step in the process.
If the samples should return to different places we recommend using individual pipes for each sample. Flow by gravity is most economic in this approach.
If all samples should return to the same place they can be collected in a vessel and pumped back to the beginning of the beginning of the process. Flow by gravity is still more economic, however a single pump is not a major cost.
The most suitable approach can only be decided by studying the plant layout and process itself, and needs to be considered in each case. The smaller amount of sample used by the analyzer is usually returned to the beginning of the process.
Secondly one needs to decide if the return flow should flow by gravity or be pumped.
We recommend sample return by flow of gravity because it is the most economic way of transporting the sample. Compared to the flow from the primary samplers the flow from the secondary sampling tanks is more stable and therefore much more suitable for flow by gravity.