Product/Service

External Low Flow Dilution Probe

Source: STI
Engineered for extractive CEMS, the external low flow dilution probe consists of a passive barrel inserted in the process and a sampling enclosure located outside the process
STIfor extractive CEMS, the external low flow dilution probe consists of a passive barrel inserted in the process and a sampling enclosure located outside the process which houses a heated filter assembly, an eductor assembly, and temperature control. For dry basis systems, the probe also includes a heat exchanger and an O2 analyzer. This unit is a four-ft probe (standard) with a 5° bend to prevent excess water buildup in saturated processes. It is typically constructed of Hastelloy but can also be made from other materials to accommodate specific process streams.

The fiberglass sampling enclosure is designed to protect instrumentation and controls from highly corrosive atmospheres. The enclosure temperature can be sufficiently controlled to prevent freezing and provide increased stability in certain applications, but precise temperature control is not required. Temperatures of critical components inside the enclosure such as the sample filter, sample orifice, and dilution eductor are precisely controlled. The sample filter is a high capacity, glass filter element with a Teflon binder that filters particulate to 0.1 micron. The filter can be replaced without removing the pipe barrel from the process. Filter temperature is controlled to 300° ±10°F by a cartridge heater element. The dilution eductor is constructed of appropriate material. The dilution air flow rate is set and controlled by a critical orifice that is part of the eductor jet.

For dry basis measurement, a heat exchanging system is located in the sample path to remove moisture and condensable acid gases from the filtered sample before it reaches the dilution eductor. The heat exchanging system includes a thermoelectrically cooled Teflon block, Teflon heat exchanger, moisture collection reservoir, a remote controller, and a local purge valve. Sample gas exits the conditioning assembly with dew points as low as -35°F typically at 40° ±5°F.

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