1. Application Context

EGB boilers are typically used in marine vessels or diesel power plants, where they capture waste heat from diesel engines to produce low- or medium-pressure steam. This steam is used for heating, auxiliary systems, or even driving small turbines for power generation on ships.

On the other hand, HRSG boilers are essential components of combined cycle power plants (CCPPs). They recover heat from high-temperature gas turbine exhaust to generate high-pressure, high-temperature steam, which then powers steam turbines to produce additional electricity. HRSGs are the backbone of achieving high efficiency in combined cycle systems, often pushing overall efficiency above 55%.

2. Structural and Technical Complexity

An EGB is relatively simple in design, often consisting of basic components like an evaporator section and sometimes a superheater. It doesn’t usually have multiple pressure stages, and its control system is straightforward.

HRSGs, in contrast, are far more complex. They are designed with multiple pressure levels (HP, MP, LP), and include economizers, evaporators, superheaters, and sometimes reheaters. Some HRSGs also integrate duct burners to provide supplemental firing during high steam demand. They are managed by advanced control systems and are tightly integrated with both gas and steam turbines.

3. Steam Parameters and Operating Characteristics

Because they serve different roles, the steam generated by each system varies greatly:

• EGB boilers typically produce steam with lower pressure (≤1.6 MPa) and temperature (≈200–250°C).

• HRSGs can produce steam at very high pressures (≥10 MPa) and temperatures exceeding 500°C, suitable for large steam turbine power generation.

While EGBs are auxiliary systems aimed at improving overall energy utilization, HRSGs are core elements in the power generation cycle.

4. Installation and Operational Modes

EGBs are compact and easy to install directly after engine exhaust outlets, making them ideal for confined environments such as ships or offshore platforms.

HRSGs, however, are part of a larger, integrated system requiring careful planning alongside gas turbines, steam turbines, condensers, and control systems. Their operation is tightly linked with the real-time performance of the entire power plant.

5. Summary Table

Below is a summary comparison of EGB and HRSG boilers: