Multiple Jet Venturis - A New Application for a Trusted Technology

With the convergence of tighter air pollution regulations and the development of renewable fuel sources for small- and large-scale power generation, a trusted technology has a niche in the 21st-century energy mix.

Jet Venturis have been the workhorse in industrial scrubbing for over 75 years, controlling powders, dust and particulate fly ash as well as acidic gases. They were pushed to the side when baghouses and electrostatic precipitators came on the scene to tackle much of the sub-micron particulate market for coal-fired power plants.

But now, they're back as an ideal fit with new technologies and new business models for generating power.

New biomass gasification reactors, which convert byproducts such as potato skins or corn husks into renewable synthesis gas - predominantly methane, are under commercial prototype testing. The synthesis gas can be used to fuel steam boilers, combustion plant co-firing, small reciprocating engines and combined heat and power projects. Many of these applications are off-grid applications in remote locations near their biomass sources.

Jet Venturi scrubbers were used instead of high-energy Venturi scrubbers for a prototype power generation unit using biomass fuel. The reason was the very high liquid-to-gas ratios compared with HEV, which required the scrubbing system to handle higher-than-normal solids loading.

These gasification technologies generate a fine fly ash and may also have trace HCl and sometimes SO2 gases that require control. Electrostatic precipitators, which operate under high DC voltages, are not suitable due to the presence of explosive and flammable methane synthesis gases. Baghouses may not effectively address the acid gases, and they also create a problem handling fine solids.

Seeing the need to safely control emissions in remote locations with an easy-to-operate system, The Clean Air Group has reengineered the Jet Venturi wet scrubber. It has a number of advantages for biomass applications.

First, the wet scrubber produces only a small liquid purge stream, which is more easily handled in these remote locations. That improves flexibility for site selection.

Second, conventional single-stage Jet Venturis are known to be extremely effective on 1-micron and larger particles. However, removal efficiencies drop off for the smaller percentage of sub-micron particles, capturing only a fraction of the required sub-micron particles. When coupled in series, the removal efficiencies are additive, and each subsequent stage of the Venturi scrubber continues to take a bite out of the remaining sub-micron dust. This leads to higher removal efficiencies of the sub-micron dust. Recent testing has proven that a dual- and even a triple-stage Jet Venturi scrubber can effectively remove 99.9+% of fly ash loadings from biogasification reactors.

As an added benefit, these multistage Venturi scrubbers create additive drafts that preclude the need for ID fans, simplifying the process and saving electricity. The three-stage Venturi has demonstrated the ability to create drafts of over 30" WC while removing fly ash to regulatory limits and controlling acid gas emissions.

Compact in design and simple in operation, the reliable old workhorse, the Jet Venturi, is hard at work in our new age of renewable fuel applications. Contact The Clean Air Group by email or phone (+1-908-232-4200) to see how we engineer custom-designed Venturi scrubbers to keep the next generation of power generation environmentally compliant.