Techno Economic Assessment of Axial Flow Pumps in Thrissur Kole Lands

Abstract

Water-logged areas of wetland paddy systems must be drained in the shortest time to initiate seed bed preparation. The short time for seed bed preparation demands the adoption of low head-high discharge pumps for draining the field. A typical example of a water-logged wetland paddy system is the Kole lands lying in the Thrissur and Malappuram districts. Dewatering from these fields is mainly done by ‘petty and para’ pump, a locally made crude form of axial flow propeller pump. The petty and para pump has very low overall efficiency and requires significant installation cost and maintenance cost. Thus, as an alternative to this pump, modern axial flow pumps such as vertical submersible and vertical turbine type are gradually replacing them. At the same time, this replacement operations are capital intensive. Hence, it is necessary to assess the hydraulic and economic performance of the modern pump sets with the traditional one. Therefore, this study was conducted on the axial flow pumps in operation in the Kole lands of Thrissur District in Kerala, India, during the year 2020-2022. Performance evaluation of 50 hp petty and para pump, vertical submersible pump and vertical propeller pump was done through field pumping test and the economic analysis was carried out by considering the capital costs, operation and maintenance costs and the benefits derived from the paddy cultivation. The study revealed that overall efficiency of 50 hp petty and para pump varied from 18.51 to 22.64 percent, with a mean of 20.58 percent. In the case of vertical submersible pump, the same varied from 54.46 to 60.48 percent with a mean of 57.47 percent and in the case of propeller pump it ranged from 42.67 to 50.69 percent with a mean of 46.68 percent. It is evident that vertical submersible pump has the highest Benefit-Cost Ratio (BCR), Net Present Worth (NPW), Internal Rate of Return (IRR), and the lowest Payback Period (PP) and pumping costs among the three 50 hp axial flow pumps.