Vertical submerged pumps

In sulfuric acid plants various types of centrifugal pumps are used and their constructional features depend on the type of application. The pumps for handling molten sulfur and sulfuric acid are vertical submerged type centrifugal pumps. 

The internal circulating nozzle, or immersed column, is similar to the external circulating nozzle except that all the action takes place within the column. This is a vertical column with a small diameter central axial injection tube. Liquid is pumped from a submerged pump to the top of the tube compressed air is introduced at the top of the tube and the two phase mixture is injected down the tube and into the bottom of the vessel. 

Installation and running conditions whether the pump will be installed indoor or outdoor minimum and maximum ambient temperature likely to be encountered Horizontal external mounting or vertical submerged mounting in a tank ... 

The pumps could be vertical submerged type or installed horizontally outside the circulation tank. In case of the former, a gantiy will be required for taking out the pump for maintenance. 

Vertical cantilever pumps (without submerged bearings)... 

Submerged membranes are operated with the feed in a vessel at atmospheric pressure. To obtain a TMP, the permeate side has to be below atmospheric pressure, and this is achieved by suction provided by permeate pumping. The pressure on the permeate side will be determined by the TMP defined by Eq. (10.3) as well as a presstrre drop due to permeatc-side (lumen) flow, which may be significant for hollow fibers. This situation has been analyzed for vertical submerged hollow fibers closed at the bottom and with suction at the top. The situation is depicted in Figure 10.18a for a clean water feed, and the axial flux distribution can be estimated from (Chang et al., 2000)... 

Vertical pumps experience a vortex formation due to loss of submergence required by the pump. Observe the suction surface while the pump is in operation, if possible. 

In applications, centrifugal pumps can be supplied with liquid via piping, or the pump may be submerged. Vertical pumps are called dry-pit or wet-pit types. The wet-pit pump (submerged) discharges up through a pipe system to some point above the pump. 

Vertical shaft, turbine type pumps have their impellers submerged, hence, they are ideal for conditions where a suction lift would be required for horizontal pumps. The second impeller from the bottom of the pump bowl assembly should be submerged below the lowest pumping water level. The submergence should be increased by 1 ft (0.30 m) for every 1,000 ft (305 m) of elevation above sea level. These pumps should provide 150% of the rated capacity... 

Pump installation is an important point to be carefully considered. In the case of vertical pumps, pump submergence should comply with the vendor s specifications. In the case of horizontal pumps, the designer should control the following points ... 

A set of pumps in a pit recirculates the cooled water. Submerged vertical pumps are standard in this service. When using multiple pumps with large capacities, it is necessary to space them properly and to design the pit to allow unimpeded access of the water flow to the suction of the pumps. The requirements of the pump vendors will fix this aspect of design. Any reverse flow through idle pumps recycles to the basin and reduces the efficiency of the process. Check valves and anti-reverse mechanisms help to prevent this. 

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