Applications

Controllable environment in greenhouse facilities

GRASYS is specialized at the production of nitrogen plants aimed at maintaining a stable microclimate through the sustained nitrogen concentration in the storage facility atmosphere. The increase in stock life of agricultural products at the minimum deterioration rate is achieved with the help of a control system which is designed to preserve the required gas composition in storage facilities. Nitrogen is widely used in the food industry for the purposes of products storage and conservation. The cost of nitrogen produced with the company plants is ten-time less than that of the nitrogen supplied by the cryogen or absorbance technologies or the one ready-bottled.

• Company plants which provide a cost-conscious solution to the nitrogen producing objectives are based on the hollow-fiber membrane technology bringing in the following advantages:
• Optional adjustment of nitrogen purity and output capacity to the ratings required, without the necessity for adding oxygen to the bottled nitrogen due to the outmost purity of the latter.
• Designed simplicity as a basic principle, with no moving components integrated into the systems. Nitrogen is separated from other gases once the compressed air is forced through the membrane system to be supplied directly into the storage facility with the controlled atmosphere.
• No necessity in the application of scrubber for CO₂ removal. After the unit start-up the air flow from the controlled-atmosphere facility space (containing nitrogen, oxygen and CO₂) is recycled with the removal of CO₂, and the elimination of the need for scrubber use.
• No combustion involved. Many atmospheric control systems are based on the principle of propane combustion aiming at the reduction of oxygen in the air. This risky method is associated with the accumulation of hazardous CO₂ hydrocarbon residues. Company units provide for no combustion, thus, producing no contaminants to be emitted into the controlled atmosphere. The residual gases that are separated from the nitrogen-oxygen mixture (air) are emitted in the atmosphere to be subsequently utilized in other processes.

Stunning results were produced in the experiment undertaken in the apple storage facility, and aided by the atmospheric control system.

Poor storing ability of the fruit and vegetables exposed to the atmospheric air was indicated by two experiments.

The first experiment featured various fruits including red delicious apples. Two fruit batches have been stored in a facility with an overall volume of some 2000m3 fitted with the control system maintaining the steady environment parameters. The third check-out batch has been stored in a facility where the microclimate was supported by the combustion products generator and the CO₂.

As to the first example, oxygen and carbon dioxide concentration in the air monitored with the atmospheric control system accounted for 1.5%  and 2.0%  respectively. Obviously, the system was capable of reducing the oxygen presence in the air. This air composition has been maintained for the period of six months.

As a result, the preservation rate in the storage facility with the controlled environment system was recorded at 83%, whereas the second example indicated only a 73% preservation rate in the storage facility with the combustion products generator.

The second experiment was undertaken on the basis of an experimental horticultural shop. The experiment featured various sorts of apples stored in small premises of about 90m3 each in volume. Three batches of Mackintosh apples have been stored at 3°С with the stable storing microclimate supported by the special system which maintained the CO₂ and oxygen concentration at 1.5%  and 1.8%  during 173 days. The preservation rate arrived at 92%. The batch of Empire apples has been stored for 216 days.

At the same time another apple batch has been stored under the same conditions (1.5% CO₂ and 1.8% CO₂) at 0°С for 219 days. The result was by far, no less spectacular — 92% apples preserved the firm shape of a freshly plucked fruit, while one sort apples, namely Red Chief, appeared to be 100% fresh preserved.

The table below provides the storage terms for various fruits with the standard cooling system and with the company atmospheric control system.