Fan Pump or Split-Case Pumps | | Use of Fan Pump in Paper Making Plant | |

What is a horizontal split case pump?

          "Horizontal split case pump is a type of centrifugal pump, within which the casing is divided into two separate chambers". It is completely different from an End suction pump (or) Inline pump. Within the End suction pump casing, the suction nozzle, and also the discharge nozzle are all enclosed in a single chamber.

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          Based on design the split casing pumps are divided into two major types. When the casing is split along a vertical plane, in regard (reference) to the impeller, it is stated as a vertical split case pump; When it is split on horizontal plane, it is stated as horizontal split case pump. This kind of casing style is a lot of economical for higher flow applications, and also the impeller can be supported by bearings on both sides, an advantage for large, high flow pumps.

          The pump has the suction and discharge connections in the lower half of the casing, opposite to one another. The impeller is mounted on a shaft which is supported by bearings on each side.

          Split casing pumps are more costly than End-suction or Inline pumps and also not flexible and not adaptable as vertical turbines. However they are most durable, efficiency and dependability.

          A properly designed, installed, and operated split case pump can provide decades of life.

Axially- split horizontally- mounted pump Advantages:

          The most common split case pump is axially split (-- meaning the flange at which the pump casing separates in the same plane as the pump axis), a single- stage, between bearing, non-self priming centrifugal volute pump. The design of the pump allows for easy removal of the pump's top casing to enable easy and quick access to the pump's components without interfering with the motor or the piping system.

          Radially split casing pumps are also available in market; they are useful in very high pressure and high temperature industrial applications (Boiler- feed pumps are a common use for radially-split pumps).

          In some sort of designs, the independent bearing casing permits for easy maintenance without the requirement for removing pump's top casing. The pump's double volute design minimizes the radial load on the shaft, increasing parts life and reducing vibrations to provide quite operation.

          The split case pump is available on the market in numerous designs and also made from diverse materials to suit a wide range of applications. The main parts in the pump such as, impeller, casing, wear rings and shaft can be available in various materials to suite the fluid that is being pumped and the environmental conditions.

          The pump also comes in a variety of configurations and designs including horizontal, vertical open shaft and close coupled configurations; with counter clockwise or clockwise rotation design options.

Balanced Design:

Between-the-bearings: These pumps are also called as "Between-the-bearing" pumps. Because the impeller on the shaft is supported by bearings on both sides.

Double- suction impeller: A double suction impeller imposes fewer loads on the bearings when compared to the impeller that only draws in water from one side of the impeller (single-suction type).

Applications:

         Split case pumps are by design, a more balanced machine than the most other types of pumps. The versatile design of the split case pump, robust bearings and a maintenance friendly casing design makes it suitable for a wide range of domestic, municipal water, industrial (Paper, oil & gas plants) and other commercial applications. Multi-stage split case pumps provide economical, reliable high-head pumping for uses like booster service and boiler feed. Other applications include irrigation, public water supply, process cooling, public waterworks cooling systems, and HVAC.

Use of FAN PUMP in Paper Plants:
          The finished slurry is diluted in silo with white water. The fan pump propels this diluted slurry for paper making towards the headbox. These pumps have been designed to reduce the pulsation, since the pump goal is to maintain constant weight overtime and avoid "Baring". At the inlet of the fan pump, thick stock, generally 3 to 5% consistency is diluted with white water. At the delivery end of the fan pump, the consistency of thin-stock around 0.3 to 1% solids. Mixing action of chemicals like fillers, acids and bases by paper makers before the fan pump happen within the fan pump.

Suction couch roll

          Couch roll (also known as “cooch”) is used in paper machine to remove water by application of vacuum. It acts as the last “wrap” where the wet web leaves the forming wire (wire part) and enter into the wet-press section (press part). On the surface of the couch roll we found rows of small holes to suck the water. Inside the roll baffles (long and end strips) are present. These baffles direct the vacuum towards the portion of the roll where the wet web of paper is on the fabric. Below of the long baffle strips air tubes are present for strip movement. Below the end baffle strips springs are present to seal the roll for vacuum suction creation. In the vacuum box one shower will present, it cools the rubber material on the roll. In vacuum boxes if we increase the vacuum we need more power to drive the forming fabric. But in couch roll if we applied too high vacuum it produces visible suction-hole “shadows” due to the movement of fines within the sheet.