How Does A Gas Turbine WHRU Work?

A gas turbine WHRU works by capturing the hot exhaust gas leaving the turbine and transferring that heat through exchanger tubes to a working fluid instead of letting the heat go straight to the stack. In gas-turbine service, suppliers use HRSG for the steam-generating version and WHRU more broadly for heat-recovery units that may produce steam, hot water, or process heat.

In a typical steam-generating arrangement, the exhaust passes across tube banks arranged in sections such as an economizer, evaporator, and superheater. Feedwater is first preheated in the economizer, then boiled in the evaporator, and then the steam temperature is raised further in the superheater before the steam is sent to a process or to a steam turbine for additional power generation.

If the project is combined cycle, the recovered steam is routed to a steam turbine, so the plant produces extra power from heat that would otherwise be wasted. If it is a cogeneration or process-heating project, the recovered energy may instead be used as steam, hot water, or direct thermal duty for industrial users.

Some gas turbine WHRUs also include supplementary firing, bypass systems, or emissions-control equipment depending on the duty and plant design. That lets the unit increase thermal output, improve operating flexibility, or help the plant meet exhaust-treatment requirements.

So in simple terms, a gas turbine WHRU works as a heat recovery boiler or exchanger placed in the turbine exhaust path: hot exhaust in, useful thermal energy out, with the goal of improving total plant efficiency and making better use of the fuel already burned in the gas turbine.