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Sunday, April 19, 2015

The NXT Roaster Design by Jaromir Friedrich











AT NXT ROASTERS INC. WE USE THE WORD “INNOVATIVE” AS DISTINCT FROM “IMITATIVE” TO DESCRIBE OUR APPROACH TO DESIGN.




The NXT Roaster Design

We selected fluidized bed technology for our roasting process because it provides even heat distribution, which results in product uniformity. The beans’ chaff is effectively removed from the roasting chamber, eliminating the fire potential. 

To increase roaster efficiency we re-circulate hot air, reducing power consumption by about 75 percent.  To prevent tar deposits on roasted beans (from circulated air), we include in circuit a primary afterburner, which burns away the smoke.  This arrangement increases the temperature of circulating air, which further reduces overall power consumption.

By circulating hot air in the roaster, we are open to the atmosphere only thirty seconds at the end of the roasting cycle when hot coffee beans are quenched by a blast of cool air, which is vented through our “SmokEater”.  (As an option, we deliver a roasting system that can vent to a room/space.) Loading green beans and unloading of roasted beans is done pneumatically.

The Roasting Process

Roasting requires considerable control of the process for a given degree of roast.  In any chemical engineering, operation controls address heat requirements, actual heat balances in roasting, and various heat transfer factors to determine the time required for roasting.  In such an environment are present many factors over which the user, or Roast Master is capable to exert little or no control.

The NXT Roaster and its Roasting Process Controls include features that optimize process parameters such that the quality of roasted coffee delivered remains on target and is unaffected by factors beyond one’s control.


Roaster Description

The NXT Fluidized Bed Roaster, now in it's third generation, is a 3kg batch roaster.  The complete system comprises: process controls, a primary after-burner, a SmokEater, Heating and Roasting Chambers, Chaff removal Cyclone and pneumatic control system to operate the valves, which automatically load green beans and transport roasted beans to the Packaging Silo at the end of the roasting process.

 Sequence of Operation

The Roasting Chamber is a cylindrical vessel that has at the chamber’s bottom a Butterfly Valve with Perforated Gate. Air enters the roasting chamber and simultaneously fluidizes and heats, or cools the coffee beans.  When roasting is finished, a blast of ambient air stops the pyrolysis by cooling the beans to below 150º C (320º F). When this temperature is reached, the Butterfly Valve opens and discharges roasted beans through the Poppet Valve and beans are then pneumatically transported to a Packaging Silo.

After-Burner System

The roaster is equipped with a primary After-burner and a secondary “SmokEater”.  The primary After-burner scrubs the hot air volatiles and tar before these enter the Roasting Chamber.

The “SmokEater” is used at the end of the roasting process to scrub the smoke-laden cooling air from the roasted beans before it is vented to the atmosphere.

Compare roasteries equipped with NXT and Drum Roasters 



                 NXT

                 Drum


              Roaster
   
                Roaster
Batch capacity
kg
3

5
Hourly output
kg
18

14.7
Average time per batch
min
10

20
Power consumption with afterburners
kW/hour
6

64.5
Air required for roasting  process
CFM
80

300
Exhaust gas vented per batch
Cubic Feet
40

6000
Exhaust gas vented per hour
Cubic Feet
240

18000





Annual output




Roasting days per year
300
16200

13230
Roasting hours per day
3



Power consumption
kWh
5400

58050
Exhaust gas vented to atmosphere Annually
216,000

        16,200,000





Assuming that the cost of 1kg roasted coffee
 $     38.00



Difference in annual sale revenue
 $ 615,600.00

 $   502,740.00

Friday, March 27, 2015

NXT Generation III Roaster

 
NXT Roasters Inc. is introducing its third generation advanced roasting system, which protects the purchaser’s investment, consumes the lowest possible energy, and exceed strictest air pollution standards Training time to roast is finished in days instead of months!  Its two-step roasted coffee bean cooling system provides outstanding repeatability of roast degree.

The System combines in a single unit:
  • A roasting and a heating chamber,
  • A chaff catcher,
  • Two afterburners,
  • Pneumatic conveyor to load green beans into roasting chamber, and transfer roasted beans to the packaging hopper

The NXT roaster is practically maintenance free, with threat of fire nonexistent!  Chaff from the air stream is separated prior air entering the heating chamber.  Roaster develops no tar deposits.


 
Specifications:

Batch capacity: 3 kg (green beans)
14.4 kg/Hr (roasted coffee beans)

Motor horsepower:
Main blower:                         2.2 kW
Pneumatic conveyor:             1.5 kW

Temperatures: Adjustable
Roasting: 235°C – 265°C

Heating:
Main heater:                           10 kW
Smoke Eater:                         1.5 kW  
Power consumption:      6.0 kW / Hr.
Including Built-in Afterburners!

Cycle Times: 8 – 12 minutes

Dimensions: 50” x 36” x 80

Sunday, June 1, 2014

Improving a Working Device

Unlike a painting a machine can be tuned to new requirements without changing its fundamental reason of being.

An interesting book A Culture of Improvement: Technology and the Western Millennium written by Robert Friedel in 2007, reviews the invention and evolution of many technologies.  He certainly highlights that many factors determine the course of an idea and that it is not always the best idea that dominates.  In school,  history classes often gave the impression that there were technological leaps whereas this informed text demonstrates that more often than not inventors or the mechanically inclined stood on the shoulders of others, so to say.  Often people that leaped too far did not succeed for various reasons; people did not accept such a change, existing materials did not have the required properties, incompatibility  with existing technology, competitors sidetracked "message" etc.  In essence many aspects of a development have to be "done right" to assure success.

It is baffling that the author chooses to dismiss the work of Tesla while he lauds laboratory managers who were often credited with the inventions of employees.  Design of the distribution infrastructure of alternating current is only stated not credited.  Marconi's patent applications were turned down for years because of Tesla's existing patents.  His patent was only granted when well connected wealthy business people employed their power to influence.  It is not too different to where a federal government  concluded that the tomato is a vegetable that is subject to import regulations.
Meanwhile back in the present the challenge is to find an acceptable balance between the best technology and the price of implementing the solution.  To improve the efficiency and greatly reduce pollution the roasting air is recirculated after purging it of nearly all the smoke.  Sounds simple enough but the reality of working in a hostile environment is challenging.  

Fluidizing the bed of coffee beans is essential to the proper mixing and even distribution of heat.  In the upgrade shown on the right the Blower bearings have a lubrication system to improve the Mean Time Before Failure which usually happened too soon at roasting temperatures.

The continual cleaning of the recirculated air means that the roaster does not emit smoke during the hot weather roasting process.  A distinction is made regarding the weather because when it is cooler steam is vented during the bean cooling process.  Such a roaster can be used in higher density areas thanks to the built in pollution controls.

Of course the great smell of coffee is not to be wasted therefore we vent the air used to cool the coffee beans straight to the street to act as an olfactory business sign.



Sunday, February 23, 2014

Where to Next or is it NXT ? Suggestions?

It is time to refresh the blog but the subject matter is not "gelling".  We are working on upgrades but it would be premature to discuss a modification before they are introduced.  I am open to re-examining a blog or even attempting a new topic.  Send us an email about a topic.