BENSON Boiler

Description
Efficiency
Flexibility
Research & Development
Licensees
BENSON HRSG

Lippendorf power plant, Germany

Leading boiler manufacturers construct BENSON boilers worldwide under Siemens license. The success of the technology is based on achieving the highest economy in power plant operation through:

High efficiency due to high steam parameters
Flexible operation in sliding pressure mode

Extensive experience together with fundamental research and development assure the highest reliability for BENSON boilers.

Modern boilers are characterized by three essential features. All of them have been introduced by Siemens:

Once-through principle
Supercritical steam pressure
Sliding pressure mode

Power plant efficiency as a function of steam parameters

Increase of power plant efficiency

The most effective measure for achieving high power plant efficiency is selecting high steam pressure and high steam temperature. Increasing the steam pressure from 167 bar, the standard for drum boilers, to 250 bar enhances the efficiency by roughly 1.5% without significant increases in investment costs.

The design concept of BENSON boilers is independent of subcritical and supercritical steam pressure. To date BENSON boilers have been built for pressures up to 310 bar and temperatures up to 650°C.

A coal fired power plant with BENSON boiler can sustain load transients of 4 to 6% per minute over a wide load range and in sliding pressure mode. Sliding pressure is an essential requirement for reducing thermal stresses in the turbine.

Operating mode of power plants

The size and geometry of the furnace of a BENSON boiler can be optimally adjusted to the fuel without restrictions on the water/steam side, because the transition from evaporation to superheating is not fixed in location. The BENSON boiler is constructed with the widest possible range of firing systems including fluidized bed combustion.

Firing systems

Siemens BENSON test rig

The high reliability of BENSON boilers is based on scientifically-founded design fundamentals and experiences:

Intensive research and development especially in the field of heat transfer and pressure drop for two phase flows in evaporator tubes. Tests are continuously performed in the Siemens BENSON test rig in Erlangen, Germany. In this way the world's largest database for heat transfer and pressure drop in evaporator tubes has been established.

Continuous exchange of information between Siemens, the BENSON licensees and their customers.

Evaporator tube tests performed in the BENSON test rig

Matrix of evaporator tube tests

BENSON technology is available everywhere, as leading boiler manufacturers in all parts of the world have obtained licenses from Siemens.

Ansaldo Caldaie, Italy
Ansaldo Caldaie Boilers India Pvt. Ltd., India*
Babcock-Hitachi, Japan
Babcock & Wilcox, USA
Beijing Boiler Works, China*
Thermax Ltd., India*
Burmeister & Wain, Denmark
Cethar Vessels Ltd., India (direct license restricted to CFB boilers)
Dongfang Boiler Group Co., China
Doosan Babcock, Great Britain
Doosan Heavy Industries, Korea*
Harbin Boiler Co., China*
Foster Wheeler Energia Oy, Finland
Foster Wheeler North America, USA
BHI, Korea*
Saraswati Industrial Syndicate Ltd. (ISGEC), India*
Shanghai Boiler, China*
Hitachi Power Europe, Germany
BGR Boilers Pvt. Ltd., India*
Rafako S.A., Poland
Riley Power, USA
Cethar Vessels Ltd., India*
Shanghai Boiler, China (direct license restricted to CFB boilers)

* indicates sublicense

The licensees use the comprehensive BENSON know-how based on continuous research and development and global exchange of information. The Siemens know-how regarding the interaction between boiler, turbine and other major components, as the basis for cost-effective and reliable power plant operation, completes the BENSON technology experience.

Examples of BENSON boilers

The first combined cycle power plant with a BENSON heat recovery steam generator (HRSG), the 390 MW CCPP Cottam CDC located in Great Britain, was successfully commissioned in 1999. Today numerous further combined cycle power plants with BENSON HRSG are either in operation or are currently being built.

The BENSON HRSG technology is based on the once-through principle in combination with the BENSON Low Mass Flux Design originally developed for coal fired steam generators and patented by Siemens.