A cup of coffee is only as good as the roasting operation behind it.

For coffee roasters, one of the most important decisions to make is how to remove harmful pollutants produced during the coffee roasting process.

In our last post, we examined different product alternatives to afterburners that can create a cleaner roast. This time, we will re-visit afterburners and look at the specific benefits and drawbacks of each type. Each afterburner is offered by Inproheat Industries through our line of Smoke Dog afterburners.

Here’s a closer look at each afterburner.

Catalytic Afterburner / Thermal Oxidizer

The Pros:

  • First of all, catalytic afterburners operate on natural gas or propane.
  • They offer low to medium operating costs due to low gas prices and the advantage of a catalytic advantage.
  • Additionally, they are highly adaptable¬†to larger coffee roasting operations.
  • Compared to traditional afterburners, catalytic models also use less gas.
  • Where emissions are concerned, this model eliminates nearly all smoke, odor, and VOCs.
  • In environmentally-strict areas like Los Angeles or Seattle, catalytic afterburners are effective compliant pollution control devices.
  • Finally, low NOx can be enabled on catalytic models.

The Cons:

  • The catalytic element creates backpressure, which negatively affects the roasting system.
  • Over time, catalytic elements age and lose their ability their emission control efficiency.
  • Furthermore, replacing catalytic elements is a large capital expense.
  • Another consideration is that the weight of catalytic afterburners makes roof-mounted installations challenging.
  • There is a high up-front purchasing cost for catalytic models.
  • Lastly, advanced venting and electrical efforts are needed, along with industrial controls.

Traditional Afterburner/Thermal Oxidizer

The Pros:

  • Traditional afterburners operate on natural gas or propane.
  • Additionally, they boast medium operating costs and low gas prices.
  • For larger operations, traditional afterburners are highly flexible.
  • They eliminate over 99% of smoke, odor and VOCs.
  • They comply with environmentally-strict areas like Los Angeles and Seattle.
  • Traditional afterburners can be built with low NOx capabilities.
  • There is zero backpressure, which allows for a consistent roasting operation.
  • Traditional models require low maintenance.
  • They carry long lifespans.

The Cons:

  • Traditional afterburners produce combustion byproducts like CO2.
  • As well, there is a medium upfront purchasing cost.
  • Additionally, they leave a large footprint.
  • Finally, they require moderate venting and electrical installation efforts to go with basic industrial controls.

Recuperative Afterburner/Thermal Oxidizer

The Pros:

  • Recuperative afterburners use natural gas or propane for operation.
  • They also boast low operating costs thanks to low current gas prices.
  • The larger the roasting operation, the greater the increase for investment returns.
  • They eliminate over 99% of VOCs, smoke, and odor.
  • Recuperative afterburners comply with strictly-regulated cities like Seattle or Los Angeles.
  • They can feature low NOx capabilities.
  • Recuperative models produce no backpressure, which delivers a consistent roast.
  • They need only a medium amount of maintenance.
  • Furthermore, recuperative afterburners possess long lifespans.
  • The return on investment for recuperative afterburners is as low as 1.5 years.
  • Lastly, they produce less combustion byproducts than traditional afterburners.

The Cons:

  • They carry higher up-front costs to purchase.
  • For smaller sizes, the return on investment is noticeably lower.
  • Recuperative afterburners are heavy and are not intended for all rooftops.
  • Owners must plan for the expense of eventually replacing a recuperative afterburner’s heat recovery banks.
  • Finally, advanced venting and electrical efforts are required for installation along with advanced industrial controls.

Ultimately, it’s up to the roaster to decide the most important factors for their operation. Roaster size, area of operation, budget, and future capacity plans are just a few critical considerations. At Inproheat Industries, we work with coffee roasting clients to determine exactly which type of Smoke Dog afterburner is best.

Ready to adopt your own Smoke Dog afterburner? Talk to our sales department!

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Coffee roasting

Smoke and odor arise naturally as a result of the coffee roasting process, leading to pesky problems. For roasters, finding the right solution requires careful analysis as each option has a unique advantages and drawbacks.

At Inproheat, we develop Smoke Dog afterburners (or thermal oxidizers) to reduce smoke and odor for roasters in the coffee and food industries. An efficient afterburner reduces and even eliminates smoke and odor, but what other options are available and how do they compare to afterburners?

In this post, we’re going to outline the pros and cons of air filtration systems, which are known alternatives to afterburners.

As food roasting often involves coffee, nuts, or fish, let’s break up the two main components involved in the roasting process.

First of all, roasting produces smoke. This is often dark black or light grey in colour and contains suspended particles, unburnt hydrocarbons, greenhouse gases and VOCs.

Secondly, roasting produces odor – which has no visible spectrum.

Interestingly enough, the critical difference between these two roasting components relates to our own human senses. Smoke concentrations have to be somewhere in the parts per millions to be detected by the human eye. By comparison, odor is much less concentrated – somewhere in the parts per billions – and still be detectable.

By using air filtration methods, roasters reduce smoke and odor to varying degrees, depending on exactly which system they are using.

Here’s a look at the benefits and drawbacks of several air filtration systems.

Filter Scrubbers

The Pros:

  • Cost-wise, filter scrubbers are an inexpensive upfront investment.
  • On the set-up front, they install easily.
  • Filter scrubbers benefit very small roasting operations.
  • Where the environment is concerned, there is no direct greenhouse gas generation.

The Cons:

  • Disappointingly, filter scrubbers have short lifespans and need replacement when an element is full.
  • In addition, backpressure from filters negatively affect the roasting process.
  • As well, the roasting odor is not fully eliminated from using them.
  • Furthermore, discarded filters generate waste.
  • Also, filter scrubbers fail to eliminate roasting-related VOCs.
  • Lastly, they are not compliant pollution-control devices in areas with stringent emission laws like Los Angeles or Seattle.

Electrostatic Filters

The Pros:

  • Electrostatic filters use electricity, so they generate no direct greenhouse gases.
  • For maintenance, there are simple controls with basic venting and electrical components.
  • On smoke removal efficiency, they remove approximately 80% of smoke particles.
  • In terms of odor removal, they reduce some without removing it all.
  • Cost-wise, they carry a medium up-front cost.
  • For roasters surrounded by neighboring businesses, electrostatic filters offer great technology to keep them happy.
  • As for durability, these products possess a long lifespan.

The Cons:

  • First off, electrostatic filters require elemental cleaning ranging from daily to weekly.
  • Also worth noting, larger models with increased duty do not fully eliminate smoke.
  • Without proper motivation, backpressure from filters has a poor effect on the roasting process.
  • Additionally, they reduce without fully eliminating odor.
  • Unfortunately, they do not eliminate VOCs.
  • Finally, electrostatic filters do not comply with pollution control laws in environmentally-stringent markets like Los Angeles or Seattle.

Wet Scrubbers

The Pros:

  • For controls, they are simple to operate with a basic venting and electrical set-up.
  • Concerning cost, they boast a medium up-front and low operating cost.
  • In terms of environmental impact, wet scrubbers generate no direct greenhouse gases because they use electricity.
  • As a final benefit, micro level wet scrubbers are scalable.

The Cons:

  • Most notably, scrubbers create waste water during the roasting process. Waste water’s harmful contaminants require specific disposal procedures.
  • In addition, these products don’t fully eliminate smoke and odor.
  • Furthermore, they do not eliminate VOCs.
  • Unfortunately, in environmentally-strict markets, scrubbers do not comply to emission laws and regulations.

In conclusion, air filtration systems are best-suited to smaller roasting operations in markets with more relaxed emission bylaws. Because of their low cost and basic operation , they have their own appeal.

Ultimately, roasters need to weigh these benefits against drawbacks like regular cleaning, waste water creation, and the failure to completely eliminate smoke, odor, VOCs.

Our next blog post will examine the different variations of afterburners and their respective pros and cons.

Interested to know more about Smoke Dog afterburners by Inproheat? Get in touch! Contact us to discuss your roasting operation and discover our afterburner products.

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