This is the sixth and final installment of the special screw compressors in which the main features in operation and design will be presented.
by Germán Robledo*
In summary, it has been seen then that the Mono Tornillo is a compressor within the family of screw-type compressors that has benefits and characteristics superior to its brothers: the Double Screw, for the purposes of its design and principle of operation, which are the virtue of being able to equalize the pressures or allow the suction gas to be located both in the front and the back of the compressor, achieve a dynamic balance of axial sense, eliminating any axial thrust force or horizontal arrow.
Having two compressions (a star or rotor gate is responsible for a section or upper part of the screw while the other star is responsible for the other section or bottom of the screw, as if simulating two compressors in one) and two discharges located in a symmetrical and opposite radial shape, allows any type of effort generated by the compressed gas and by the discharged gas, are balanced or nullified by going in opposite directions, achieving once again dynamic equilibrium for forces or loads of radial direction or vertical arrow. Being then, the bearings or points of support the backbone of any compressor, and especially and with greater importance in screw type compressors, the balance of loads or stresses in an absolute way allows these forces or loads never to act on the bearings, achieving that they do not wear them in a severe way and thus achieving as a final result a longer service life or long life of the compressor bearings.
In this way, the constant changes or bearing agents required by other types of compressors or manufacturers are minimized, minimizing maintenance costs, maintenance stoppages, production downtime and reduction of final product inventories. In this way, the Mono Tornillo becomes a more reliable and efficient compressor for long life and low maintenance requirements. It does not require tracking or vibration analysis, you should not worry about when the bearings think they will fail and in advance forecast it with the follow-up by means of vibration analysis.
The system of guides or sliding parts of capacity and variable volume ratio separately and independently provides greater energy savings or energy consumption by the exact location without interfering with each other, for each point of capacity and discharge, especially for partial loads where the effects of overcompression or subcomprehension that represent an unnecessary wear of energy are eliminated, compared to its even screw siblings, that the position of one is affected by the over command of the other, placing itself at the wrong points of capacity and discharge for partial loads, increasing energy consumption.
The use of two stars or compression gates in opposition to a male-female screw pair, allows a balanced compression, better efficiency, low noise level and with less brake or power requirement. In this way less lubrication or injected oil is required in the compressor in the opposite way to the pairs of screws that require greater lubrication or injected oil since the pairs must be lubricated well and form a compression seal between it with oil, it is worth mentioning that the less oil is injected into the compressor, less the capacity of the compressor is penalized, achieving greater efficiencies and a lower brake or power is consumed, since no more amount of gas-oil mixture should be compressed. The stars, being manufactured in ultra-resistant resin and thermoplastic materials, have a long service life and are almost non-deformable and resistant to any type of solvent, gas, liquid and other materials, giving greater resistance than a pair screw compressor.
But, not only does it provide efficiency and long life, but the replacement of them returns the compression efficiency to its original 100% compared to the wear of screw pairs that cannot recover their efficiency without the absolute change of the compressor or the pair of screws. In this way, the Mono Tornillo compressor becomes an element of almost all life without its replacement or replacement compared to other styles or manufacturers.
The Length/Diameter ratio (L/D) of the screw is always constant and is a 1:1 ratio in all Monkeys, always achieving a robust screw that will never suffer from deflection compared to other screws that to achieve greater capacities, without increasing the power much, extend the length of the screw, resulting in deflection problems, achieving hasty wear of the screw and therefore the premature change or replacement of them.
The Screw Monkey does not use compression veins or compression seal, its seal is made by stars or gates. By not using a seal or compression profile or vein, but using a wall of variable thickness, it allows to minimize the cascade effect, which allows the return of compressed gas to the anterior cavity, reducing efficiency. This effect is common to all screws, but it is minimal in Screw Monkeys due to their variation in wall thickness and the non-use of vein or profile. The combination of opposite discharges, allows the gas pulsations to be canceled, the non-loading in the bearings, the combined cycle of stars and the non-use of pairs of tonillos, achieve a free compressor of lower noise level compared to other systems of this class available in the industry.
* German Robledo is a Mechanical Engineer. He has 15 years of experience in the industrial refrigeration industry, was manager of after market and services for the north of Latin America in the company York Refrigeration and is currently the sales director for Latin America of the company Vilter Manufacturing - Emerson Climate.
