RheoVac - Moisture Separator For Wet Condenser System Technical Notes

INTEK, Inc.751 Intek WayWesterville, OH 43082-9057Ph: 614-895-0301 • Fax: 614-895-0319e-mail: sales@intekflow.com©2007 Intek, Inc.Figure 1. Intek Moisture Separator Test Set-upRheoVac Technical Notes®Moisture Separator for Wet Condenser SystemFor the past few years, Intek has been researchingand developing solutions for the issue of liquid waterimpinging on the RheoVac instrument’s probe tips.®Through these efforts, Intek has discovered that thiswater mist is initiated by design limitations inside thecondenser. These deficiencies cause the air andsaturated water vapor mixture to contain water mist thatis not normally found in most condenser vent lines.While this condition negatively affects RheoVacmeasurements, it is also extremely harmful to condenserperformance. This water condition can damage sensorsin the RheoVac probe and can result in an erroneouslyhigh indicated total mass flow (lbs/hr) of water vaporand air. This in turn leads to excessively high ACFMand SCFM calculated readings. In addition to affectingthe RheoVac system’s operation, the design limitationsinside the condenser and/or inadequate air removalsection of the condenser contribute to excess backpressure, low heat transfer, high dissolved oxygen,corrosion, lost load, and high heat rates — effectsdetrimental to performance.These findings have been reported in severaltechnical papers and presentations. As an example,water in the vent line can cause significant reduction ofventing capacity if SJAEs are used. The liquid wateruses up a portion of the SJAE’s constant mass flowpumping capacity, thereby reducing its gas phasepumping capacity.In addition to understanding the root cause of “wet”vent line probes, Intek has invested resources intodeveloping methods for eliminating the water. The mostdesirable and beneficial method is to correct thedeficiencies by implementing condenser fixes. Intek offersan analytical service that not only develops modificationsto permit a dry and properly operating system, but alsocorrects the other consequential performance problems.Reference Intek’s Condenser Performance Evaluation andImprovement Services program.For plants interested in an immediate solution andwho wish to delay addressing excess back pressure andthe other identified performance issues, Intek hasdeveloped and tested a moisture separator that isinstalled in the vent line just prior to the probes. Wateris flung to the outside of the pipe and bypasses theRheoVac probe with only a very small pressure drop(less than 0.01" HgA in a 3.5" diameter pipe). Thispressure drop is negligible in larger line sizes. Figure 1shows the test set-up whereby water mist is introducedinto a RheoVac calibration line. Two probes aremonitored, one upstream of the separator where wateris present, the other downstream of the separator. Theupstream probe detects the mist and displays dataindicative of the wet condition, the downstream probedisplays an accurate, dry reading, demonstrating theeffective use of the separator. The Figure 1 insertillustrates a cross sectional view of a pipe with amoisture separator installed. In a 10" line the moistureseparator occupies only 2.5% of the pipe’s crosssectional area.The graph of Figure 2 shows measured data, TotalMass Flow before and after separator installation, at apower plant. After installing the separator, total massflow rate dropped from an erroneous reading of 1450lbs/hr as shown in the left side of the Figure (error inmeasurement due to water), to an expected value of 500lbs/hr as shown on the right side of the Figure. Notealso a corresponding drop in ACFM, from 6,500 to2,000, with the separator in place. After the separatorwas installed during a shutdown at this plant, a large airin-leak was noted at start-up as indicated by theRheoVac instrument, this leak amounted to 42 SCFM.Intek appreciates your business and continues towork diligently to help you eliminate the undesirableeffects of water on the RheoVac probes and the realnegative economic impact on your profits. Pleasecontact us, “your process flow partner” for solutions wecan offer.Separator cross sectionINTEK, Inc.751 Intek WayWesterville, OH 43082-9057Ph: 614-895-0301 • Fax: 614-895-0319e-mail: sales@intekflow.com©2007 Intek, Inc.Figure 2. RheoVac data, before and after Moisture Separator InstallationFigure 2 below contains RheoVac data provided by a power plant in the US which has installed Intek’s moistureseparator. Page 1 Page 2