Technical Specifications
- Tempest Drying System
- Injector/Airlock
- Blower
- Pre-Separation Cyclone
- Separation Cyclone
- Tempest Controls
- Ancillary Equipment
GRRO's Tempest Drying System
The Tempest has received a patented status on the method and apparatus in the US.
Tempest Product Conditioning Unit
The Tempest
Product Conditioning Unit (TPC) utilizes the exhaust heat and
radiator waste heat from the diesel power plant, electrical resistance
heat or waste heat from other processes. Utilizing this heat from the
exhaust helps capture the energy that is normally lost from the power
plant. The material is heated to 80 degrees C or higher for pathogen
destruction, with some loss of water due to evaporation and
vaporization.
The material is then injected into the airflow and enters the cyclonic dryers.
Tempest Pneumatic System
This process is a pneumatic high velocity process resulting in the reduction of water content and the reduction of particle size of feed materials. The process utilizes high volume airflows, cyclonic separations, centrifugal actions, heat of compression, impact, frictional, kinetic energies and psychrometrics to dry the material. The reduction in particle size with an increase in surface area increases the rate of desiccation of the material. Water is removed via mechanical / physical separation, desiccation (air vapor) and evaporation.
The high air velocity causes the impingement of the material upon a striking surface or other materials. This impingement of the materials imparts energy while shattering and rupturing the material into fine particles. High volumes of dry air are supplied via the pressure blower.
The second stage cyclone separates the materials by specific gravities and will produce a material with total solids greater than 80%. There are microbial population reductions through microbial cell rupture due to sudden deceleration upon impact, sudden pressure variations and thermal exposure.
The resulting dry material is discharged from the bottom of the cyclone with the water-entrained airflow exiting the top of the cyclone and passing through a scrubber to remove particulates, water particles and water-soluble compounds. Additional emission treatment can be added if required.
GRRO's Tempest Drying System Components
Feed Hopper
The Tempest Drying System is equipped with an input feed hopper that provides waste material at an even, controlled flow rate to the Tempest.
Tempest Product Conditioner (TPC) (Patent Pending)
The Tempest Product Conditioner consists of three concentric tubes that allow material and inlet air to the blower to be heated. In addition, the conveying auger in the TPC is internally heated utilizing the diesel coolant as the heating medium.
Tempest
Product Conditioner
Exhaust gas from the Caterpillar diesel is directed through the second
of the Tempest Product Conditioner's three tubes, heating the waste
material in the center tube and the blower air in the outer tube. An
exhaust pipe removes waste diesel exhaust gases from the Tempest
Product Conditioner.
Heating the material
The customer feeds material to the Tempest Product Conditioner at a
controlled rate. A feed auger rotating at selected revolutions per
minute conveys the material through the center tube of the product
conditioner, ensuring that all the material comes into contact with the
heated surfaces contained in the TPC. The Tempest Product Conditioner
drops the heated material into the injector auger or into a
rotary/sliding air lock.
Heating the Cyclonic Air
A blower forces air through the outer tube of the Tempest Product
Conditioner.

Injector/Airlock
The injector consists of a hopper and a hydraulically driven high-speed injector auger. The auger is user-controllable and accelerates the product into the Tempest air stream.
The Tempest Product Conditioner introduces the heated material into the high velocity air stream. The air conveys the waste material into the Pre Separation cyclone.
Blower
The Tempest relies on a centrifugal blower to convey material through the system to be processed in two cyclones and a wet scrubber. The blower is sized for the input tonnages and the type of material.
Blower Functions
The Tempest uses the output of the blower for the following purposes:
- Conveying of material from the Injector/Air Lock to the Pre-Separation Cyclone.
- Conveying of material from the Pre-Separation Cyclone to the Separation Cyclone.
- Conveying of air and water from the Separation Cyclone to the air scrubber.
Pre-Separation Cyclone
The Pre-Separation Cyclone uses air to agitate, separate and accelerate the material, further reducing the particle size and releasing water from the surface of the particles. The resulting mixture of solid particles, water vapor and air leaves the Pre-Separation Cyclone through the top and is conveyed to the Separation Cyclone.
The Pre-Separation Cyclone includes a variable vortex finder that may be adjusted if the composition or type of processed material changes. Contact GRRO for more information on making this adjustment.
Separation Cyclone
The Separation Cyclone continues to remove water from the material as centrifugal, impact, kinetic, frictional forces act upon the material. The Separation Cyclone separates the solid particles from the mixture of water vapor and air. The solids drop out the bottom of the Separation Cyclone; the water vapor and air mixture is directed into the wet scrubber.
Tempest Controls
The controls for the Tempest are located on a main panel and regulate the output. The product retention time in the separation cyclone is controlled by adjusting a few settings. Product dryness is a function of retention time. When the retention time minimized, the product dryness is also minimized. As retention time is increased, product dryness is also increased. Particle size can also be control by a few adjustments.
Discharge Auger
The discharge auger conveys the dried particles from the Separation Cyclone to the container used to store final product.
Wet Scrubber
The Tempest uses various air-wet scrubbers to combat air pollution, depending upon the application and type of material being processed.
In general, a mixture of water vapor and air from the Separation Cyclone is discharged into the wet scrubber, which slows and cools the mixture. The water vapor condenses and is removed with any fugitive dust that was not discharged via the discharge auger. The wet scrubber can also remove soluble compounds and some odorous volatiles.
Ancillary Equipment
Caterpillar Diesel Engine
The Tempest power-plant is a Caterpillar Diesel Engine, an efficient diesel engine with electronic fuel control that meets all present California Tier II standards.
The Caterpillar is responsible for the following activities:
Driving the gearbox that drives the blower.
Through heat from the radiator pre-heating air flowing into the Tempest Product Conditioner auger.
Through the exhaust heating the Tempest Product Conditioner, which in turn heats the waste material and the air flow.
Driving the pump that powers the hydraulic system.
Hydraulic System
The hydraulic system powers the following Tempest system components:
- Feed auger
- High-Speed Injector auger / Air Lock
- Separation cyclone tilt on larger models
- Discharge auger
- Discharge auger tilt
- Wet scrubber pump motor
- Wet scrubber exhaust fan
Trailer
The Mobile Tempest Models are deployed on a generic trailer with enclosures that contain a number of Tempest system components. Enclosures feature access panels.

