Power’s easy pieces
USA, Poland and Germany have already caught on: Worldwide, Siemens offers the construction of its Combined Cycle Power Plants (CCPPs) with prefabricated modules, increasing safety at the building site, improving the quality and installation of parts and accelerating construction weeks ahead of schedule.
by Moritz Gathmann
What is a big construction site? It is orderly chaos. There are hundreds of construction workers from different contractors, trucks arriving and leaving, there is dust and dirt. Then there is the most unpredictable factor: weather – rain, snow and wind. The huge job of the construction company, no matter if we talk about a big apartment building or a CCPP, is to keep control of that anthill. And stay on schedule.
That is why the search for ways to minimize the risks is always on. A solution to most of these issues are prefabricated power plant modules. More and more, they are becoming an alternative to the traditional stick-built construction, that is: constructing all kinds of systems and structures on site.
What is it all about? The less people you have working on site, the smaller your risk of accidents. And the more parts you prefabricate under workshop conditions and then ship them to the construction site, the less time delays you’ll have because of missing spare parts or weather conditions. More effective planning of construction progress, greater flexibility, and less time spent on coordination and communication at the construction site – this is the highest standard of modern power plant construction.
Siemens Solutions Blocks for Combined Cycle Power Plants (CCPPs)
Worldwide, Siemens is now offering the construction of its CCPPs with prefabricated Siemens Solution Blocks. The first examples have already been successfully implemented. For Siemens Energy Solutions in Germany, it started with a first small pilot module, in the Knapsack II CCPP near Cologne. In parallel, the Orlando based project of La Caridad in Mexico piloted the use of prefabricated pipe rack modules. In this project, an overall reduction of approximately 40,000 man-hours on site could be achieved along with an overall schedule reduction by one month.
By the end of 2017, a 596-megawatt electric plant for Eastern Europe’s largest mineral oil company in the Polish city Plock is to be commissioned. As in the case of La Caridad, 40,000 man-hours on site could be saved. Nearly twice as powerful is the 940-megawatt electric CCPP that’s also being built using Siemens Solution Blocks in Lordstown, Ohio, USA.
As always, the “centerpieces” of the plant, such as turbines and generators, are manufactured in Siemens’ own factories and then delivered to the site. But apart from those main components, there are dozens of pipe racks, pump and component modules that are needed in the architecture of a power plant. The new thing is that most of them, too, are prefabricated.
A serious time gain
“In a workshop, the conditions will always be much better than at the construction site: You have all the tools you need, rain or snow doesn’t bother you, and you don’t interfere with other workers in a very limited space”, says Peter Seyller, Siemens’ Principal Key Expert for Modularization and Standardization. If properly planned, the system allows a serious time gain. The on-site time saving for a single pipe rack alone is 10,000 man-hours.
One reason for the time savings is that working in parallel at the construction site always causes problems because of limited space, whereas in the workshops there is no such issue: In one workshop they produce the pipe rack, in another one the pump module, and so on. The company that’s doing the job may even be as far away as China. The main thing is that the building of the modules doesn’t interfere with other work on site.
Due to the complete and compact arrangement of prefabricated modules, the units are relatively easy to transport and have an almost negligible time of installation. While the stick-built construction of a pipe rack may take up to 15 weeks, the installation of a prefabricated one on site can be done in five days.
One of the main issues is that in the end the cut surfaces of the different parts have to fit. But that problem is solved through 3D-Engineering, where all cut surfaces are simulated. Additionally, the contractor will always conduct tests under workshop conditions.
Another issue that is much easier to handle under workshop conditions is obligatory testing: hydrostatic pressure tests or nondestructive testing like X-ray for piping systems is always a problem at the construction site.
Putting economic good sense to use
The concept is convincing. In Hong Kong, Siemens struck a deal this year with Castle Peak Power Company Limited (CAPCO) for the delivery of a power block for a new combined cycle unit in its Black Point Power Station. Scheduled to be in operation before 2020, the plant will have an installed total capacity of 550 megawatts to supply approximately a million households with electricity. One of Siemens’ arguments was a simple calculation: The use of Siemens Solution Blocks would mean approx. 70,000 man-hours less at the construction site. For the client, that means less safety issues, better quality and accelerated schedules.
Moritz Gathmann is a journalist based in Berlin.
Picture credits: Siemens AG, Independent Medien Design
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