DESCALING

DESCALING PROCESS

During the continuous casting and rolling processes, the iron oxide formed on the surface of the metal products. Any leave of such impurities on the metal surface during the rolling operations will affect the quality of the finished products and in the worst case, can end up as scrap, which will increase the cost and waste. A reliable descaling system equipped with high-pressure pumps which generate high-pressure jet water through nozzles can be used to remove the scales on the metal surface effectively. The scale layer is being broke by temperature shock and steam bubbles. The impact pressure and pattern on high pressure water are accurately calculated, so the scale can be removed effectively, without losing too much temperature of the surface, and they are also a dependable of material properties.

TECHNOLOGY SPECIFIC

Materials

The descaling water used and looped in the system is usually accumulating solid particles, and even the most advance filtration is equipped, it is challenging to remove all particles. Solid particle accumulation in the process water can be harmful to any wet-end parts and seals. Specially coating such as tungsten carbide coated ram, as well as Kevlar packing, are recommended for such application.

Pump Loading and Unloading

Pump systems should also be designed to operate to suit the changing production cycle of the rolling mill. Pump systems are ‘on-load’ (pumping to the nozzle) when the metal is passing through the descale box for seconds to minutes, depending on the size of the metal, before the pump systems go ‘off-load’ and wait for the next piece of metal. Unloading valve (bypass valve) is used to divert the excess fluid back to the tank.

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Valve Lifter

Valve Lifter is an alternative to unloading valve, which driven by pneumatic pressure via a solenoid. The valve lifters mechanically lift the suction valve of the pump to prevent pumping and create pressure. Such device prevents waste of energy when the pump system is off-load.

ENERGY SAVING SOLUTION

Variable Frequency Drive (VFD)

VFD drive is also widely used to save energy when the pump system is off-loaded when there is nothing to descale. All pumps can ramp down to a minimum speed which reduces the load of the motor and the energy consumption. The mill can, therefore, save significant electrical cost depending on the size of the systems. Additionally, additional saving on maintenance cost can be achieved due to less wear and tear on pump components as well as downstream components, such as valves and joints. Variable speed drives also avoid motor overloads during on-line starting, and avoid the resulting large voltage fluctuations which can affect other equipment in the plant. Pump running with VFD can also reduce the size (or sometime eliminate) of downstream components to save first installation capital cost.

OUR ENGINEERING SOLUTION

Hydrofinio provides clients with an expert engineering team equipped with diverse skills to meet various challenges across industries. We leverage our knowledge to reduce risk. We’re constantly looking for new advancements and technologies to find the smartest and most optimal solutions. Contact us now with your requirement and we will come back with solutions to suit your need.