Cross flow turbine

Types of Cross Flow Turbines

A cross flow turbine is a type of hydroelectric turbine. It is suitable for medium to low heads and utilizes water flows from various directions. The working principle of cross flow turbines is that water flows into the turbine blades in two directions, which could be horizontal or vertical. They are generally divided into two categories.

• The impulse cross flow turbine: This kind of turbine applies the impulse principle, which means that water flows strike the turbine blades, causing the turbine to rotate. It typically boards a small to medium-sized power output. Impulse cross-flow turbines have some distinct characteristics that allow them to serve specific applications effectively. They often feature a simple and robust design, which contributes to their low maintenance requirements and long operational lifespan. Additionally, impulse cross-flow turbines excel in their ability to maintain efficiency over a wide range of water flow conditions. This versatility makes them suitable for various hydropower sites where water flow rates can fluctuate significantly. Furthermore, their efficiency curve is generally flat, meaning that they can operate effectively even when the water flow is not at its peak. This trait enables the impulse cross-flow turbine to generate electricity consistently, ensuring a reliable power supply. Moreover, their adaptability to different water heads and flow rates allows them to harvest hydro energy from diverse environments, making them a valuable asset in the renewable energy landscape.
• The reaction cross flow turbine: This cross-flow turbine was designed based on the reaction principle. It could also be housed in a penstock. However, it would be less common as the impulse variant is more popular.

Specifications and maintenance of a cross flow turbine

The performance of an industrial cross flow turbine can be gauged by two key specifications: overall efficiency and capacity factor. Overall efficiency compares the hydraulic energy converted into useful work to that of the energy available. A good cross flow hydro turbine will usually have an overall efficiency ranging between 60 and 90 percent. The capacity factor compares the actual energy output of the turbine in a year to what it could achieve if it operated at rated capacity all the time. A well-designed cross flow turbine with better blades can have a capacity factor of 30 to 50 percent.

A quality cross flow water turbine needs periodic maintenance to work optimally. The maintenance can be divided into two parts: regular inspections and periodic maintenance. Regular inspections should ensure that no debris gets lodged in the turbine, blocking the flow of water. Muds, leaves, and other debris should be removed as required. The water passageway of the turbine should also be inspected for wear and tear and cleared if required. The bearings of the turbine should be lubricated occasionally to ensure smooth operation. Operators should also ensure that there are no abnormal sounds coming from the turbine while it is operating.

Periodic maintenance for cross flow turbines can be done every 1 to 3 years. This would involve thorough cleaning of the turbine and its components. The components like water passages, blades, and bearings, which are critical for operation, must be cleaned thoroughly. Dynamic balancing of the turbine can also be done during this maintenance to ensure that the rotor runs smoothly at high speeds. Belts and coupling should also be inspected and adjusted or replaced if necessary. The electrical connections of the turbine and the generator should be checked to ensure that there is no corrosion or loose connections.

Industry scenarios of cross flow turbines

The urban neighborhood of Dhaka, Bangladesh heavily relies on hydroelectric power from cross flow turbines due to limited land space. Similarly, small-scale cross flow turbines operate in urban areas of Nepal, Thailand, Vietnam, and Indonesia. They provide clean energy without the need for long-distance energy transmission, reducing costs. Meanwhile, Malaysia's Selangor state has begun assisting Malaysian rural areas by installing low environmental impact cross flow turbines with no pressure head requirements to supply electricity. They are also boosting efforts to develop kinetic energy micro generation projects in Kuala Lumpur to generate power from water currents in drainage pipes. This intends to alleviate the persistent flood issues in the state by converting floods into electricity. Additionally, the kinetic energy of wastewater in sewers is expected to generate more electricity than the projects in Kuala Lumpur alone. Similarly, Turkey has more than 90 water pipelines that can be used to generate electricity, which will help replace the use of fossil fuels in the energy production sector.

Cross flow turbines are versatile. Industries like pulp and paper, municipal, agriculture, food, beverages, chemistry, pharmaceuticals, and textiles use them to reuse wastewater and piping pressure to generate on-site electricity. This reduces operating expenses and aids in pollution management. Other sectors that may benefit from cross flow turbines include.

• Farms

  Cross flow turbines help farms produce their own energy by utilizing water from rivers, streams, ditches, or rainfall runoff. This reduces reliance on the electrical grid and lowers expenses.

• Rural electrification

  Cross flow turbines provide electricity to remote rural areas not served by conventional power grids. They offer a sustainable energy solution to off-grid communities that improves living standards.

• Desalination plants

  Cross flow turbines produce electricity to power desalination plants that convert seawater into freshwater for consumption. Tapping the energy from seawater flow enhances the sustainability of desalination.

• O&M (Energy recovery)

  Cross flow turbines recover energy from high-pressure water streams in industrial processes, such as cooling water and pressure relief valves. They convert wasted energy into usable electricity, improving operational efficiency.

• Hotels/ resorts/ cruise lines

  Cross flow turbines in the hospitality sector generate electricity from wastewater and piping pressure. This reduces operating expenses and aids in pollution management.

• Commercial hotels

  Cross flow turbines allow hotels to generate electricity from on-site water systems, reducing reliance on the grid and lowering energy costs.

• Green buildings

  Cross flow turbines serve as one of many sustainable features in green buildings. They harness energy from building water systems to promote environmentally friendly construction.

• Environmental conservation

  Cross flow turbines minimize the ecological impact of hydroelectric projects by operating in low-flow environments, such as irrigation channels and drainage ditches. They help conserve valuable natural resources.

How to choose cross flow turbines

Cross flow turbines are suitable for small hydropower plants with medium to high flow rates. When selecting the right turbine for a specific site, many variables, including water flow, water head, site constraints, efficiency, reliability, and cost, must be considered.

• Flow and load

  Cross flow turbines are ideal for small-scale hydropower applications where water flow is limited or an intermittent resource. A good approach is to estimate the annual energy production based on the water flow rate and head and determine the plant's output capacity. This will help in understanding the load or scale of the hydropower project, which requires a cross flow turbine.

• Site constraints

  Site constraints such as available space are critical to cross flow hydro turbines. Buyers should consider the installation footprint of the turbine to ensure that the selected turbine fits within the available space and is the proper type for the project site. In addition, the layout should be convenient for construction, operation, and maintenance.

• Efficiency and reliability

  Generally, cross flow turbines convert water energy into mechanical energy. The turbine's efficiency is a crucial factor in the long-term economic viability of a hydropower project. Besides that, a cross flow turbine's operational reliability and durability affect its long-term economic performance and maintenance costs. Buyers should choose a turbine with proven reliability and a robust design to withstand long-term operating conditions.

• Cost

  The initial capital cost of the turbine and generator, installation cost, and maintenance cost should be considered. Buyers should undertake a comprehensive economic assessment, selecting a turbine that meets the project's technical requirements while also considering its economic benefits.

Cross flow turbine FAQ

Q1: What are the benefits of Crossflow turbine hydropower plants?

A1: The low water requirement is one of the key advantages. Cross flow turbines can work in low head sites, as previously mentioned. In addition, they have high efficiency. When working in sites with low river flow, this could actually produce more energy. Third, the structure is just simple. With fewer parts, the assembly or maintenance task could be easier.

Q2: What is the limitation of Crossflow turbine power?

A2: The main drawback of cross flow turbines is that they are less efficient in high-head situations. In fact, they work better in low heads, as mentioned earlier. In high-head areas, water streams more quickly, and another type of turbine–the Pelton turbine–is more suitable.

Q3: Are Crossflow turbines suitable for large-scale power generation?

A3: Cross-flow turbines are more suitable for small to medium-sized hydropower plants. They may not be the best choice for large-scale power generation with large capacities.

Q4: Can a cross-flow turbine be used in an existing hydroelectric power station?

A4: Yes, cross-flow turbines are often used to update or enhance the efficiency of existing hydropower stations. For example, if there is some station that works with low heads, it is possible that installing a cross-flow turbine could improve energy output without major modifications to the site.