Correct pre charge pressure ensures that the top roll floats about its design position which ensures good extraction and protects the mill from damage.
One major advantage of using hydraulic drives in sugar mills is the flexibility of speed ratio adjustment i.e. the pressure Feeder Roll (hydraulic drive speed) to Mill Rolls can be adjusted from, let's say, 0.8 to 1.6, as required in order to accommodate:
- Variations in mill settings,
- Roll Surface roughness, and,
- Turbine Nozzle Bowl pressure.
- The flexibility also allows for optimal use of the mill under varying cane quality condition.
When applying hydraulic drive, the greatest benefit is in the capacity improvement and plant reliability areas. For example, the additional power enables fiber loading to increase (e.g. if loading is 28 tones per hour it increases to 32 tones per hour).
Time efficiency of the hydraulic drive has been proven to be 99%, as there are never serious breakdowns. The only parts that require regular replacement is the Potentiometer providing the Swash Plate position feedback signal, Oil Filters and O-ring seals.
The lower energy consumption experienced in hydraulic system application in sugar mills is because the hydraulic drive is connected directly to roller shafts thereby eliminating loss of energy through gear drives; it is also as a result of electro-hydraulic controls automatically setting the drive to the lowest appropriate speed. Because power required of the drive is almost directly proportional to the speed, a Conventional Turbine Drive wastes energy by running at a virtually constant speed.
Brands of Low-speed, high torque motors provide an effective, compact, light weight and energy efficient methods of driving cane mills at maximum speeds of only 5.5 rpm. The motors deliver power directly to the shafts with no need for auxiliary speed reduction.
General points to note in the application of a hydraulic system in a sugar mill – the advantages include:
- Low energy consumption
- Reduction of installation costs.
- No need for additional gear installations.
- Improved production as there are no regular breakdowns of the mill.
- Most hydraulic systems are self-monitoring with all the necessary warning and alarm facilities.
Hence, we can say that the hydraulic system is more reliable, reduces maintenance costs, and, there are throughput benefits.
The applying of electric hydraulic motors in variable speed drive configurations facilitate the speed of feed belt conveyor to be controlled by a suitable control system. This brings about optimization of grinding performance of the mill.
Typically hydraulic rams together with a gas accumulator (which acts as an air spring) provide the downward force on the bearing caps to resist the upward force of the bagasse on the mill roll. As we know, the hydraulic oil in the system is not compressible, but the gas in the accumulator is, and, it is this gas that has the give that allows the roll to float. As the gas in the accumulator is pre charged with specific gas pressure; the higher the pre charge pressure, the softer the spring rate. Low pre charge pressure makes the system very stiff which may not allow sufficient float to let tramp iron through the mill and thus may cause damage. On the other hand, a high pre charge pressure makes the system very soft and the top roll bearing may continually rise up to its maximum lift. This means that the head stock may be subjected to very high forces not anticipated in design.
Sukan is trade house of hydraulic pumps in India. We supply Yuken make vane pumps, Vickers make vane pump in all over India.