Mobile power stations bridge the energy supply

The operation of hospitals, social institutions and hotels does not allow for any interruption in the supply of heat, for heating the building and for providing hot water. Whenever modifications need to be carried out on the district heating grid in Gelsenkirchen-Buer, all of the major consumers throughout the urban area had to be found an alternative source of heating for an interim period. The Gelsenkirchen subsidiary of energy service provider Hotmobil got involved, supplying 12 mobile heating units to do this job.

In early 2012, in the Gelsenkirchen district of Buer, a temporary interruption in the supply of district heating was announced to four hospitals and care institutions, an AWO building and six hotels: reconnection work was required on the district heating lines, meaning that the energy provider was obliged to take these major consumers off the grid briefly in early May. For a few days, this meant that it was no longer possible to transport a proportion of the total of 70 MW of heating power produced by the coal-fired power station operated by E.on Kraftwerke GmbH on Glückaufstrasse in Gelsenkirchen to customers. A new way therefore had to be found of generating heating power in the immediate vicinity of the institutions affected and of feeding that power into the heat distribution grid.

Hospitals without an alternative to district heating
Due to their connection to the nearby CHP plant, none of the buildings affected had their own energy system or a backup form of heat generation. The energy provider company responsible, E.on, therefore appointed the Gelsenkirchen-based subsidiary of Hotmobil Deutschland GmbH to maintain the supply of heat using mobile heating units. Reconnection work on the district heating grid was scheduled for the first weekend in May. Two days before the deadline, the energy service provider Hotmobil rolled up with no fewer than 12 mobile heating units, set up the connections and got the boilers into operation.

About half of the total heating power of 2.7 MW was accounted for by two of the hospitals - Marienhospital and Bergmannsheil - with over 700 beds between them. The Bergmannsheil hospital had the highest demand for heating power because its complex of buildings also houses Gelsenkirchen's pediatric and young person's clinics as well as a rehabilitation clinic. On 3 May 2012, Hotmobil drove up to this complex of buildings with a mobile 950 kW heating unit on the towbar which it duly connected to the heating supply equipment. In the basement of the Technical Building, the pipework system already had flange connections with shutoff valves and suitable quick-release coupling adapters welded into place in order to direct the district heating produced outside the building to the district heating transfer station. With flexible, pressure-tight and hot water-resistant pressure hoses supplied by Hotmobil it was a quick task to connect their mobile heating units up via the basement staircase to the distribution network within the building.

An additional oil tank safeguards heating operations
Mobile oil heating units deliver the requisite independence on site from remote technical facilities in the event of a failure or an interruption in the supply of heating. After the start-up process, Hotmobil hands over the protocol for mobile heat generation to the person(s) responsible and provides training to the employees responsible - in this instance pipework specialists from the local energy provider. The company renting the equipment is responsible for providing the power supply and - depending on order and formal agreement - the filling of on-site systems with heating fuel. If any faults develop on the burner or in the combustion chamber, the 24-hour service from Hotmobil leaps into action. For the anticipated multi-day operation of its mobile heating unit at Bergmannsheil hospital, Hotmobil supplied an additional 7000 litre oil tank. Although the mobile 950 kW heating unit is equipped with a 1000 litre heating fuel tank, for operation throughout the weekend at a rating of almost one megawatt, it was necessary to compute in a correspondingly high level of consumption. Mobile heating oil tanks in sizes of 6000 to 25,000 litres are therefore an integral part of the product range of this pioneering company in the mobile energy supply market - as are special-purpose exhaust silencers because at these power ratings, an oil blower-burner causes a correspondingly high degree of noise emissions. To keep the noise emissions for local residents and patients at the hospital to a minimum, the energy provider fitted an exhaust silencer to the exhaust journal which cut the noise level by about 10 dB.

Mobile energy supply for heat, cold or vapour
Mobile heating units with ratings of up to 950 kW bridge the heating supply to buildings or for parts of district heating grids. To supply major consumers or public institutions and for longer rental periods, mobile heating units can be housed in transportable containers and are capable of delivering heating at ratings of up to 2500 kW. The range of mobile refrigeration plants extends from room air-conditioning units rated at 4 kW through to transportable large refrigeration generators with cooling power ratings of 1200 kW. Mobile refrigeration plants and transportable air-conditioning devices are used to provide an ongoing air-conditioning service to buildings in the event of breakdown of refrigeration plants, the supply of refrigeration to bridge downtime in production or inventory facilities or to protect computer centres. To supply the needs of vapour consumers and steam-powered district heating grids, Hotmobil can also supply turnkey vapour supply units with power ratings of 600 to 16,000 kg/h.

The customer base of this mobile energy provider includes utility companies, industrial companies, large buildings, municipal authorities and HVAC trade businesses. For specialist TGA planners and architects, the head office site of Hotmobil in Gottmadingen is manned by competent specialists who are there to provide sound advice. For utility companies (energy providers), mobile power plants offer a flexible solution to the need for temporary supply which, depending on requirements, can be employed directly in the power station or locally in the supply area. As examples of practical applications, Hotmobil would name grid extensions, the safeguarding of peak load cover during ongoing maintenance work, the conversion of vapour to hot water supply or - as in the case in Gelsenkirchen-Buer - repair work to district heating pipework.In new-builds and the modernization of energy systems or remote (district) heating distribution networks, 'on-demand' power can be supplied up to the two-digit megawatt range, thereby ensuring that utility companies can dispense with 'redundant', i.e. backup, plant systems.