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Kitchen Exhaust PCU/Exhaust Scrubber

Kitchen Exhaust Scrubbers (or Pollution Control Units (PCUs)) are becoming more and more popular as urban areas continue to grow and mixed-use construction becomes increasingly more popular. But just what are these units and how do they work?

There are several different technologies on the market for capturing the grease, smoke and odors from commercial kitchen exhaust, but let’s look at the two most popular technologies that are used today.

Mechanical Media Filtration

Mechanical Media Filtration is the most popular technology on the market. It is simplistic and easy to understand. The exhaust goes through a pre-filter section which pulls out large particulate. It then passes through one or more sections of high-efficiency filters to remove smaller particulate and then finally passes through an Odor Module loaded with some sort of adsorption media to remove odors and VOCs.

mechanical media filtration diagram

Although this is the most popular system due to its simplicity, it has some drawbacks.

  1. The filters need frequent replacement due to all the grease-laden vapors that pass through the system.
  2. Replacement filters are very expensive. It is not uncommon to spend as much on filters in one year as what the entire PCU costs.
  3. If filters are not changed frequently, they can load-up to the point where the exhaust can no longer pass. This results in smoke backing-up into the kitchen and restaurant during high cooking times such as the dinner rush; think of the dollars lost by shutting down during this peak time.
  4. Because of the multiple sections needed and the size of the filters, these systems are much longer in length than other technologies.
  5. Mechanical Media Filtration systems require larger horsepower blowers which will consume more power.

Electrostatic Precipitators (ESP)

Electrostatic Precipitators create an ionization field which will positively charge the grease, smoke and fine particulate in the exhaust. The positively charged particles then pass through collector plates which are alternately charged. The particulate is attracted to the negatively charged collection plates which capture the positive particles and hold them until they are washed off.

electrostatic precipitator airflow

An Odor Control Module is placed downstream from the precipitator to capture odors and VOCs.

electrostatic precipitator airflow diagram

This technology offers many advantages over media filtration systems including:

  1. Much lower operating costs. Electronic cells are simply washed to remove collected particulate and re-used over and over. Because of this, there is a substantial savings by eliminating expensive replacement filters.
  2. It’s a greener solution. Cells are cleaned and re-used which keeps greasy, spent media filters from filling up landfills.
  3. Smaller footprint. Because of the high efficiency of the precipitator, there are less stages to the filtration process which makes these a good solution for space-limited projects.
  4. Lower static pressure means smaller horsepower blowers and less power consumption.

With proper care and maintenance, an ESP system will provide decades of highly efficient filtration in a commercial kitchen exhaust application. With all things being considered, an ESP system is clearly the best option to use when a PCU is needed for the kitchen exhaust.

Air Quality Engineering

Air Quality Engineering