HARARE AGRICULTURAL SHOW 2017

The Harare Agricultural Show was held from the 21st to the 26th August 2017 under the theme ‘Seed to Food: Innovate, Consolidate, Sustain.’ The TRB won the best display in the Parastatals and State Enterprises challenge category under the theme ‘Enhancing Food Security through Tobacco Production’ The highlights of the TRB Harare Agricultural Show exhibits were:
• Showcasing the value addition chain from seed to high yielding and high returns tobacco production to purchase of food
• Innovative environmentally friendly seedling production with Gromix plus (tobacco and gum seedlings), Gromix ultra (horticultural seedlings), floatfert, dibble board and mechanical seeder
• Chemical analysis and Plant disease diagnosis fostering good agricultural practices
• Tissue culture produced disease free plantlets e.g. potato, sweetpotato, banana and strawberry
• Environmental friendly heat exchange systems of energy efficient curing facilities including the innovative Kutsaga barn




Environmental friendly energy efficient curing facilities

ROCKET BARN
Rocket barn, How it works: ambient air entering the barn flows through a brick furnace then the hot flue gases flow inside the heat exchanger, made from thin (1 mm) steel metal and a brick firebox. From the brick heat exchange firebox, the hot gases enter the metal inner chimney then into the outer metal chimney heating the cooler air inside the outer metal chimney creating a pressure drop. The pressure drop in the outer metal chimney generates suction, drawing air through the vents on the front wall across the leaves in the inner barn space, through the window in the back wall of the barn and out of the metal outer chimney.

Rocket barn heat exchanger display
Kutsaga Counter Current 1 (KCC1) heat exchanger display

Kutsaga Counter Current barn display

Kutsaga Barn Principle of operation The Kutsaga barn introduces air uniformly inside the curing room unlike in the rocket barn where inlet air enters the curing room randomly. The hot flues have more residence time in contact with the ambient air thereby enhancing more heat exchange. There are no flue pipes involved in the new barn, making it cheaper and easier to construct and maintain. In short, it has low fuel consumption despite its capacity (45 000 leaves per cure) compared to (15 000 leaves in the rocket barn per each curing cycle). Better cured leaf quality. Tobacco drying is a function of 3 factors:

— • Temperature
— • Humidity
— • Airflow

INTERVENTIONS TO ENHANCE DRYING FACTORS IN THE NEW BARN

—  Counter current airflow (The air inlet vents in the rocket barn) are simply holes in the wall and the air enters at random and is dispersed.
 Counter current flow gives more room to extract more heat from the hot fluid
 — Insulation (the bottom of the firebox is insulated using broken pieces of kaylite)
 — Increase hot flue gases residence time (use of meandering firebox)
 — Trap chimney exhaust temperatures (built the chimney inside the barn to make use of waste heat)

FUEL USE EFFICIENCY (KG’S OF FUEL PER KG OF CURED LEAF)

• Kutsaga Smallholder barn 3 - 3.5 kg of fuel/kg of cured leaf
• Rocket barn 4 - 4.5 kg of fuel/kg of cured leaf
• Conventional barn 7 - 9 kg of fuel/kg of cured leaf