Direct Contact Heaters (DCHs) have become more efficient than Closed Feedwater Heaters (CFHWs). CFHWs have been a mainstay in power plants for decades. Modern technological advances, however, have made DCHs the ideal solution for current and future power plant applications.
Direct contact heaters are not new to the power generation industry. In the early 1900s, DCHs were introduced. They offered some advantages but the limitations of the early steam-injectors resulted in some drawbacks.
These early DCHs had a notable decrease in pressure. This meant they required an intermediate storage system and pump just to resolve the reduced pressure recovery. Closed feedwater heaters did not have this same issue, so even though they were otherwise less efficient, they were the more attractive option.
As a result, direct contact heaters did not achieve the worldwide popularity in power plants they had seemed suited for. Over the past few years, however, steam injection technology has advanced to a point where DCHs can outperform CFWHs without the same concern for pressure recovery.
Steam injectors draw in cool liquid from one end, mixing it with the injected steam. They are used in feed water and heating water in power plants. The introduction of Fisonic Devices (FDs) into steam injectors, helped to make direct contact heaters a more viable option.
Fisonic devices utilize two-phase flow for hyper-efficient heat exchange. The internal geometry allows for mixing steam and water through direct contact without sacrificing mechanical energy. Used with DCHs, this can replace conventional jet apparatus steam injection.
In contrast to a fisonic device, a jet apparatus uses a single-phase flow which lacks the efficiency of an FD. A jet apparatus needs an extra heating process to achieve a similar efficiency. The nozzle design and two-phase flow of fisonic steam injection technology provide greater energy efficiency without an additional heating process. This helps to streamline and simplify operations.
An FD can handle a greater range of counter pressures while delivering a constant flowrate of the target mixture. As well as providing a higher outlet pressure than that of the working medium.
In addition to efficiency, this technology is more versatile and is a simpler device with no moving parts and minimal space requirements.
Electric heaters offer an ideal solution for direct contact heaters, particularly in use with fisonic devices. Their simple design complements that of the FDs, minimizing the risk of failure and making maintenance and cleaning easy.
In operations, electricity is the most efficient option for heating. Direct contact heating is a process designed for efficiency, while also requiring the precision temperature control and monitoring only available through electric heaters.
Wattco custom designs and manufactures electric immersion heaters for the power generation industry. Our direct contact heaters are tailored to the exact requirements of your process. Get in touch with our team to choose the right heater type, materials, wattages, and design to match your needs and budget.
Contact Wattco for power plant heater quotes and information.