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Home » Electrostatic Precipitators » Max 9 » Frequently asked questions

A unique, but simple, combination of technologies enables the Max-9 to achieve unprecedented collection efficiency. The discharge electrodes in the unit are the same type used in a conventional electrostatic precipitator. In the Max-9, the discharge electrodes serve to ionize (charge) the dust, which is then collected on the surface of the fabric filter. Since the dust particles are charged to the same polarity, they repel each other, making the dustcake more porous. The charge also makes the dust easier to remove from the filters. Cleaner filters, a porous, breathable dust layer, and high cleaning efficiency enable the Max-9 to operate at high air-to-cloth ratios, and state of the art filter media ensure the highest possible dust removal.

No. The Max-9 operates at very low current densities, meaning that power levels are just too low to generate sparks, even in heavy dust concentrations. The design of the Max-9 is engineered to keep grounded surfaces far away from the discharge electrodes, while ensuring a very evenly dispersed electrical field. The Max-9 can actually operate without a voltage control, although you'll probably want one or more just for data acquisition.

The choice of filter media is dependent upon the application. Variables such as temperature, moisture content, and dust chemistry will determine which type of fabric is best for your particular application. Each Max-9 installation is site-specific and custom designed to ensure the best possible results and reliability. So to answer your question, the best media for you is what you'll get. We're not limited to any specific material.

Yes, there are other systems that use some sort of discharge electrode intermingled with filters. But the Max-9 is completely different, and is patented by the USEPA. The other systems use some sort of collecting electrode to capture particulate, but the Max-9 does not. In the other designs, the dust either loses its charge by the time it hits the fabric filters, resulting in an agglomerated dustcake and high pressure drop, or the larger particles are collected electrostatically, leaving the small particles to blind or penetrate the filter media. The Max-9 avoids these problems because the charged particles never contact the grounded collecting surfaces, and retain their charge for a much longer period. Therefore, the pressure drop remains low, the particulate is easily removed, and the filters are not blinded or penetrated by fine particulate.

The USEPA recognized the need for more effective pollution control technology to enable compliance with pending regulations. They partnered with Southern Research Institute (SRI) to develop an electrostatically stimulated fabric filter, which proved itself in plant testing. BHA became the sole licensee to the new technology, and commercialized the design. BHA has a great deal of experience with both baghouses and electrostatic precipitators, and has rebuilt and retrofitted hundreds of each.

Right now, everyone is operating under a certain degree of regulatory uncertainty. However, the Max-9 fits in well with just about any possible combination of compliance technologies. BHA believes that the most likely approach for coal-fired utilities will include SCR or SNCR for NOx control. The existing baghouse or precipitator will be retained for primary particulate removal. There will probably be activated carbon or other agent injected after the precipitator for mercury abatement, probably in conjunction with a wet or semi-dry scrubber for SOx control. The fine particulate created in the scrubber and mercury control module will be collected in the Max-9 unit, which can also be used to supplement the existing baghouse or precipitator right now, since the efficiency is so much higher. Regardless of what comes down the pike as far as regulations, Max-9 provides an extremely high degree of efficiency that will help meet PM 1.0 regulations.

Therein lies the beauty of the Max-9 collector. The efficiency is so high, and the footprint so small, that almost any plant does have room for the Max-9 modular collectors, especially in a slip-stream configuration. If the goal is to reduce particulate, Max-9 collectors can be installed in slip-stream to treat, say, 25% to 40% of the total gas volume. The resultant collectors would take up very little space. For mercury and SOx emissions, a bank of small semi-dry scrubbers can be installed, followed by Max-9 collectors to treat a portion of the gas stream. They don't have to treat the total gas volume to be effective. BHA is willing to assist anyone with an interest in this new technology. We can probably find a place for it! The various design configurations also provide some intriguing alternatives.