Huge steam output for new power plant giant
11.6 metres long, 4.5 metres wide and almost eight metres high – these are the impressive dimensions of the four Bosch boilers for the new Ledvice power plant unit of the energy company ČEZ. In total the boilers produce up to 167 tons of superheated steam per hour for the start-up process of the new steam turbine (power generation). But the Ledvice power plant does not just supply a large quantity of power, it also supplies heat for some 300 companies and 20,000 inhabitants. The huge boilers provide additional supply during peak load periods and serve as a backup for the district heating network. This redundancy ensures that there is a very high degree of operating reliability around the clock.
In its role as general contractor, the company Škoda Praha Invest was responsible for implementing the turnkey power plant unit and the steam boiler system. The stringent safety requirements and tight time schedule demanded a high degree of flexibility and experience from all those involved in the project. "Following the complex tendering process, our objective together with our partner Škoda Praha Invest was to implement the steam boiler system as quickly as possible, and to ensure that a consistent supply of heat was provided to the towns of Teplice and Bilina," says Rudolf Rotta, sales engineer at the Bosch subsidiary in the Czech Republic.
After customer-specific manufacturing, the large boilers and their associated components were delivered by low-loader and ship from the industrial boiler factory in Gunzenhausen (Germany) to the Czech Republic. The boiler house at the power plant comprises a complete boiler system, including feed water deaeration system and control technology. The superheater modules on the reverse chambers of the boilers generate superheated steam and, thanks to high steam temperatures, prevent energy losses in the pipe network. Due to their height of more than five metres, the boilers were equipped with the superheaters on-site – and this gives them a height of almost eight metres.
The integrated economizers for using waste heat and the eight natural gas burners in total, had already been installed at the Gunzenhausen factory. The total combustion heat output is more than 136 megawatts – equivalent to the output of 250 Formula 1 engines. On this kind of scale, there is a need for a high level of energy efficiency. The burners can be operated particularly economically thanks to the installed speed controls. They reduce the power consumption during partial-load operation by up to 75 percent and also reduce the noise level to a minimum.
Fast availability of the steam boilers is essential for operation of the power plant. Each of the four boilers is therefore equipped with a heat maintenance system. The backup boilers can therefore provide additional steam generation within a very short period of time. The integrated sequence control is implemented by means of a network pressure system. As soon as the primary boiler can no longer generate the required steam pressure, the backup boilers switch in automatically. The higher-level control technology with its industrial Ethernet connection enables information flow between Bosch's control system and the control centre of the power plant. All operating messages and current process data are transmitted directly to the operators at the power plant, thus they can control the system remotely at any time.
In summary, the power plant is equipped with a consistently reliable and energy-efficient steam boiler system. Thanks to the comprehensive automation equipment, a high level of supply reliability as well as operation without continuous supervision (72 h) are guaranteed. Vilém Šarkády from the general contractor, Škoda Praha Invest, is very satisfied with the progress of the project: "In total there were four boiler manufacturers in the final selection. The crucial reasons for choosing Bosch were the product quality and brand as well as the reliability." The successful project implementation was rounded off with the commissioning of the steam boiler system on schedule.