Pumps range from very large to very small, from those handling gas to those handling liquid, and from those suited to high volumes to others better suited to low volumes. Based on the method of operation, there are primarily two types of pumps available in the market – dynamic pumps and positive displacement pumps.
Dynamic pumps account for a sizeable proportion (close to 95 per cent) of the total pump market in India. Typically, these pumps add energy to the liquid flowing through it via the dynamic action of a rotation blade, which increases the velocity of the liquid. This dynamic action of the liquid is carried out by an impeller, which is a revolving wheel with curved vanes.
Dynamic pumps can be further classified into two categories. These are rotary pumps (comprising centrifugal pumps, axial flow pumps, mixed flow pumps and peripheral pumps) and special pumps (such as jet pumps, electromagnetic pumps and fluid actuated/gas lift or hydraulic pumps).
Of all the types of dynamic pumps, centrifugal pumps are the most commonly used. These pumps use a rotating impeller to move water into the pump and pressurise the discharge flow. While the pump operates, it creates an increase in the liquid pressure from the pump inlet to its outlet. This pressure difference drives the liquid through the system or plant. It can be used for pumping all kinds of liquids, including those with low viscosity. These pumps work best with thin liquids and at high flow rates. The rotational energy in these pumps is derived from an electric motor or an engine. They find use in several applications in industries such as chemical, petrochemical, food processing, dairy, beverages, pharmaceutical and cosmetic, and wine-making, among others. These pumps are used to transfer juice and bottled water in the beverage industry; dairy products such as milk, butter milk, flavoured milk, etc., in the dairy industry; glucose, lactose and other drugs and personal care products of low or medium viscosity in the pharmaceutical and comestic industry. The application need and the viscosity of the fluid help decide the model of a centrifugal pump that should be used.
In the water treatment industry, centrifugal pumps find use for metering precise amounts of liquid for the purpose of treating drinking water, boiler water, swimming pool water and wastewater. Typically, they can also be used for applications that require high water pressure. Some of the key characteristics of centrifugal pumps are higher discharge vis-à-vis regenerative pumps, exceptional hydraulic performance and high operating efficiency. Besides, they are the simplest pumps as they do not require any valves or many moving parts. This makes them easy to deploy with many different materials. It also allows them to move at high speeds with minimal maintenance.
Overall, dynamic pumps are preferred over positive displacement pumps owing to their lower maintenance requirement and cost effectiveness. The other benefit that they offer is their ability to operate at high speeds and at high fluid flow rates. However, these pumps usually offer low efficiencies in comparison to positive displacement pumps.
Positive displacement pumps
Positive displacement pumps account for around 5 per cent of the total pump market in the country. They operate on the principle of filling and displacing liquid from a cavity. These pumps help maintain a steady flow and volume of liquid and are devoid of any discharge pressure or head. Hence, they are a type of constant flow machine. Positive displacement pumps can be classified into the following main subcategories – reciprocating pumps (piston/plunger/ diaphragm pumps) and rotary pumps (single- rotary and multiple-rotary pumps).
A reciprocating positive displacement pump works by the repeated back and forth movement of a piston, plunger or diaphragm. These cycles are called reciprocations. These pumps are typically used in cases where a relatively small quantity of liquid has to be handled or where the delivery pressure is high. The repeatable and predictable action of reciprocating pumps makes them ideal for applications where accurate metering or dosing is required. By altering the stroke rate or length it is possible to provide measured quantities of the pumped fluid. Reciprocating pumps find applications in the oil and gas sector, power plants, sugar industry, petrochemical plants and refineries, water treatment plants, among others.
Reciprocating pumps can further be subdivided into three categories. Based on the reciprocating member of the pump, a reciprocating pump can be a piston pump, plunger pump or a bucket pump. On the basis of the action of the liquid upon the end of the piston, these pumps can either be single acting or double acting. And fially, they can either be direct-acting pumps or power pumps on the basis of drive.
In contrast, rotary positive displacement pumps use the actions of rotating cogs or gears to transfer fluids, instead of the backward and forward motion of reciprocating pumps. The three main kinds of rotary positive displacement pumps are gear pumps which are the simplest rotary pumps where the liquid is pushed between two gears, screw pumps where two screws turn against each others to pump the liquid, and the rotary vane pump which have a cylindrical rotor cover in a similarly shaped housing.
Essential variables determining pump selection
The critical aspect is to determine the right kind of pump to meet the needs of an application. The right choice would enhance overall efficiency and reduce operation costs, and also improve the life of not only the pump but the system as a whole. One of the key factors influencing the choice of a pump is its size. The critical factors that need to be considered while choosing the pump size are the fluid’s viscosity, power consumption, commercial availability and life cycle costs. Ironically, in some cases the use of multiple pumps instead of a single pump helps in reducing energy consumption. This usually happens in situations where demand is cyclical. Accordingly, in low demand phases, one small pump is sufficient while in higher demand phases, multiple pumps working together with each other are useful.
Increased emphasis on technological advancements
Pump manufacturers in the country have increasingly been involved in the development and implementation of the latest technology in pumps and valves. There has been an increase in the use of smart, sustainable and energy efficient pumps at the global level, and India is no exception to the trend.
Pump dimensions and technologies have witnessed significant advancements. Recent innovations in this field include solar-based pumping systems, lowest life-cycle-cost pumps, high capacity concrete volute pumps and vertical turbine pumps.
Solar-powered pumpsets can address the issues associated with conventional pumpsets and provide a cost-effective irrigation solution to farmers. As of December 2017, 147,527 solar pumps have been installed in the country. A key initiative in this segment has been the Kisan Urja Suraksha Evam Utthaan Mahaabhiyan (KUSUM) in Union Budget 2018-19 to promote the installation of about 1.75 million solar pumps and move the existing 7.25 GW of grid-connected and diesel-based pump capacity to solar based. Under the scheme, an investment of Rs 1,400 billion has been planned, which includes central government assistance of Rs 480 billion. Since a key challenge facing the market is the high cost of solar pumpsets (a 5 horsepower [HP] solar water pumpset costs Rs 100,000-Rs 120,000), the government plans to provide subsidies under KUSUM for solar pumps. Financial assistance of 60 per cent has been proposed, which will be equally divided between the state and central governments, while nearly 30 per cent will be funded by banks and financial institutions in the form of loans. Thus, only 10 per cent is required to be invested directly by farmers, in the form of equity.
Moreover, technological advancements have also been made for reducing pumping requirements. For instance, increasing the net positive suction head available to a pump, allowing a higher cooling water temperature rise across heat exchangers to reduce cooling water pumping requirements, and heating a viscous process fluid prior to pumping to reduce viscosity have all been useful developments.
Further, the government has been taking several initiatives to promote the use of energy efficient pumps across all sectors, with special focus on the agricultural sector. Through Energy Efficiency Services Limited (EESL), an energy service company under the Ministry of Power, the government announced the National Energy Efficient Agriculture Pumps Programme, for which Rs 4 billion has been earmarked. The pilot of this project was launched in Andhra Pradesh in 2016. The programme is aimed at replacing inefficient agriculture pumps with energy efficient, IoT-enabled pumps, free of cost to farmers with free maintenance for five years.
The way forward
At present, the size of the Indian pumping market is relatively small compared to the global pump industry. However, the country has been catching up through its rising exports. It is thus crucial for Indian manufacturers to maintain a high quality standard for them to be able to compete with global players. Besides, quality maintenance is also crucial considering the extreme nature of chemicals and liquids that the pumps are exposed to.
In particular, domestic players are continuously working on the productivity, quality and service of their pumps. Going forward, greater focus on the use of new materials for manufacturing pumps with better efficiency and reliability will prove to be the crucial factor for driving the market for Indian pumps.