Flow control of liquid waste for a waste-to-energy plant

A Scandinavian waste-to-energy company owns and operates an incineration plant. The plant plays a crucial role in managing municipal waste and a significant amount of commercial waste. This facility not only handles waste disposal but also transforms waste into sustainable energy, generating up to 12 MW of electrical power using a steam turbine and up to 35 MW of thermal energy for district heating.

The ever-increasing demand for waste processing and the fluctuating nature of waste composition requires a flexible and responsive system. Ensuring a steady burn of waste material to keep the steam generator running efficiently has been a primary challenge. To address this, the operator initiated an innovative pilot project to add liquid waste directly into the furnace.

Integrating this process with the existing system posed significant challenges. Controlling the precise amount of waste material fed into the combustion chamber, especially when liquid waste is introduced, can be complex and inefficient. The addition of liquid waste must be strictly controlled and the flow rate must be precisely regulated to avoid excessive use of liquid waste and to prevent any negative impact on the incineration process. Maintaining the correct balance is essential to ensure that the flames remain stable and the combustion process is not disturbed. Only if the desired temperatures in the different combustion zones are properly maintained can a safe and environmentally friendly liquid waste co-firing be ensured. The operator was therefore searching for an accurate and responsive solution for flow control to optimise the combustion process and keep plant uptime high.

The plant operator decided on FOCUS-1 to control the flow of the right amount of liquid waste fed into the furnace. This smart meter valve combines sensors for flow, (differential) pressure and temperature as well as actuator and control functionality in one device. With ultrasonic flow and differential pressure measurement, it can even provide redundant flow measurement using two different measurement principles. Its compact design, with no additional components such as external flow instrumentation, pressure and temperature sensors or additional flanges, enabled a time-saving, straightforward installation.

FOCUS-1 integrated seamlessly into the existing control system using PROFINET communication for easy commissioning. No additional control loop programming was required. The smart meter valve controls the flow rate autonomously, only the set point (i.e. the desired flow rate) is provided by the PLC.

FOCUS-1 has fully met the demanding requirements of the co-firing process. It provides the integrated control and measurement system required for the balance between the solid waste and the liquid waste feed by ensuring precise control of the liquid waste flow into the furnace. Monitoring all measurements in real time has significantly improved flow control and process safety. The streamlined system has reduced potential points of failure and increased the overall reliability and uptime of the plant. It contributes to efficient and environmentally friendly waste incineration.

Unlike traditional setups that require multiple components such as flowmeters, valves and control units, FOCUS-1 integrates these functions into a single device. This has not only reduced the complexity of the system but also simplified the installation process. The plant operator can set the desired setpoint for FOCUS-1 directly, monitor all measurements and achieve fast and accurate control of the process. This paves the way for improved efficiency and innovation in waste management and energy production.