An old industrial chimney in Barcelona has been given a new lease of life as part of a recent redevelopment thanks to an HBK monitoring system. The chimney was part of Ca L’Aranyo, a former textile factory, which was built in 1872. The factory closed in 1986 as the Spanish textile industry declined in importance leaving a derelict site. Universitat Pompeu Fabra (UPF) has since acquired the site for a new campus and wanted to incorporate as much of the existing historical structure as possible. It was also decided to make the chimney part of a modern heating and cooling plant for some 55 buildings by utilizing a network of pipes while retaining it as a symbol of Barcelona’s previous industrial glory.
This posed a number of engineering constraints since the chimney needed to be raised from its original height of some 36 to 46 meters to meet current legal requirements. This was achieved by inserting an exhaust tube for any smoke on the top of the chimney. The plan also demanded that the chimney form a stand-alone structure located in an open pedestrian area within the new university campus. This made safety a very important consideration. However, the chimney had a weak load-bearing structure with masonry less than 15 cms thick so that swaying in high winds might cause unacceptable stresses.
To achieve these objectives, the Spanish company, Metiri – working in collaboration with HBK Ibérica – built internal collars at the top and bottom of the chimney so that five steel cables could be fitted and pre-stressed.
Each of the wires is fitted with an HBK C6A load cell with a nominal load of 200kN. There are also two PT100 temperature sensors fitted at the base of the chimney. All of the sensors are connected to HBK’s MGCplus multichannel amplifier capable of handling both analog and digital input signals.
The output signal is linked to a panel of five bicolor LEDs giving a quick visual indication that the system is functioning properly. There is also an alarm fitted that sounds if the pre-stressing force in any of the cables decreases by more than 20% compared to the initial pre-stress force.
Control of the system is by a PC running HBK’s catmanAP software that reads the data at 1 sample/sec.
This is then automatically exported once an hour as an average data output to an ASCII file that is automatically sent through a 3G connection to a database server. The database server collects, processes and displays the data on a website programmed for the purpose. Users have an authentication code that permits the download of historical files into spreadsheet-readable format.
This system is due to be upgraded shortly with the PC and the 3G connections being replaced by MGCPLUS Profibus cards that will transmit data to the SCADA system at the customer's site. This upgrade will integrate the monitoring and management system for the chimney at the customer's SCADA system.