Insulating Performance Increased - Operational Costs Decreased
After the acquisition of the “Mitteldeutscher Olefinverbund” in 1995 and extensive restructuring works in 2000, The Dow Chemical Company (DOW for short) in Central Germany stands for integrated manufacturing processes, innovative technologies, a high level in productivity and excellent results in occupational safety and environment protection.
The manufacturer of high-quality plastics constantly works to make progress in the domains of environment, health and safety.
One of the major issues for the company is energy efficiency. By 2015, the energy consumption should be reduced by 25 % compared to 2005. In order to meet this challenging objective, all existing plants’ technical standards have been checked and are still assessed with regard to their currentness of data, and will be adjusted whenever necessary.
At the sites of Schkopau and Böhlen, The Dow Chemical Company has been operating a chemical park since 1998, which enables 21 companies to produce and transform plastics and to offer chemical-related services.
Underrated potentials
In the project which is described in the present article, the company has intended to improve the energy balance in parts of the DOW-owned supply system in the plant of Schkopau up to the state-of-the-art level. In this specific case, the steam and condensate pipelines have been modernised.
For the investigation concerning savings potentials in steam and condensate pipelines, the operator analyses first of all the technical components of his facility and in particular their functional efficiency. He will look for possible leaks and thermal bridges in the system, as nothing in the manufacturing process seems to be more expensive than an undesired heat loss. However the state, the quality and the carrying out of the insulation of the single pipelines still tend to be neglected. But there is still here a big saving potential, as the DOW-plant in Schkopau shows.
Big heat loss due to dated insulation
The steam and condensate system is part of the supply pipelines in the plant of Schkopau. Before the refurbishment was implemented, the steam pipelines had a diameter of DN 200. The insulation, which had not been renewed since about 35 years, was no longer in line with the current standard and caused a corresponding high heat loss. Despite the fact that the condensate pipelines were insulated with another material, the measurements showed that this huge heat loss was also traceable there. The pre-insulated foam-filled pipelines with a diameter of about 114 mm had been operated for 15 years and were no longer able to completely fulfil their function of thermal protection.
Requirements for the refurbishment result
The check of current insulation standards and products followed the baseline study. In order to increase the efficiency, DOW decided after having consulted the technical insulation experts of ISOVER to modernize the insulation of the pipelines. In parallel they reduced the cross-section of the steam and condensate pipelines, as the pipelines were meanwhile over-dimensioned after the cut-off of several recipients. Thus, the diameter of the steam pipelines was reduced from DN 200 to DN 100 and the diameter of the condensate pipelines from DN 100 to DN 50. This fact meant that the existing substructures and coatings could no longer be used. In order to better assess the savings potential of further pipelines, the replacement of the insulation had nevertheless to be in the same thickness as in the previous situation.
Especially for existing pipelines, the fact that there is not enough space for the realisation of a thicker insulating layer occurs very often. In the case of an unchanged thickness, the required savings can only be achieved by an optimised insulant. Then, it is possible to continue the use of the coating of the old pipelines.
The insulation material requirements which had to be used were defined by the type of pipelines and their laying in underground ducts: because of the medium temperatures, the insulating material must have very good insulating properties and a high-level of fire protection function at the same time. Due to the narrow underground pipeline shafts, materials which are easy to handle would simplify the work of the installers.
The reduction of the heat loss at the steam and condensates pipelines was of course the most important criteria. With the support of the thermo-technical calculation tool TechCalc, it was possible to define a savings potential of up to 40 % of heat loss which had to be confirmed in practice during the implementation. That’s why DOW documented the difference of the situation before and after the refurbishment of a test line through metrological analyses and an especially dedicated thermo-graphic camera.
The solution for energy-efficiency and cost-effectiveness
In regard to the product form requirements concerning its mechanical performance, the recommended insulant was a wired-mat. According to the technical directives for insulation measures, the required minimum density for wired-mats normally is 80 kg/m³, but only if the products are made of stone wool. But in terms of thermal insulation performance, the density of the insulating material is not decisive: it is much more the thermal conductivity that matters. It is the parameter for the heat loss through the insulating layer: the lower the thermal conductivity is, the lower is the heat loss - and this has a direct positive impact on the operational costs. In this reference we used a wired-mat in ULTIMATE quality. In regard to the temperature level at the reference pipelines, the thermal conductivity of ULTIMATE is by 15 % better compared to traditional wired-mats made of stone wool.
ULTIMATE is an innovative insulating material which is used in various domains. The particularity of this material is located in the combined benefits offered partly by glass wool and partly by stone wool. The patented mineral wool is comparable to stone wool as for the batch, but it is produced with manufacturing process of glass wool. Thus, we get best thermal insulation properties with a lower weight which offer high energy efficiency and cost effectiveness with at the same time space-saving benefits and an easy handling. ULTIMATE offers the high fire protection factor (melting point ≥ 1000°C, Euroclass A1, non-combustible) of stone wool too. Additionally, insulating materials made of ULTIMATE offer AS-quality according to AGI Q 132 and are water-repellent.
The installers gave a very positive feedback concerning the handling with ULTIMATE wired-mats. The quick cutting and the easy laying - even with the small pipe diameters - as well as the haptics of ULTIMATE were assessed by the company BIS Isoliertechnik Nord GmbH which carried out the insulation work, and perceived as better and more comfortable compared to common stone wool products.
ULTIMATE proves to be the reference
DOW monitored the test line with infrared photographs and thermal measurements and confirmed the previous thermo-technical calculation of the savings amounting to more than 40 % in operational costs at the steam and condensate pipelines. The convincing insulation result has been achieved with wired-mats made of ULTIMATE. In spite of the primarily higher capital expenditures, the use of wired-mats has proven to be not only an energy-efficient but also cost-effective solution in the short-term and became the reference for all the further refurbishments of pipeline-systems and containers at DOW. Besides, the benefits of the high-performance insulating material ULTIMATE are not only achievable with wired-mats but also in other types like pipe sections, slabs and rolls for various application fields.
All in all, DOW achieved with the described measures two positive results: in addition to the savings in energy and money, DOW was able to reduce its CO2 emissions. In future, this benefit will be even more interesting, when the costs of CO2 certificates will become more expensive again.
Thanks to its international orientation, ISOVER will support again DOW in future concerning projects in other locations and plant sites.
Contact: Stefan Geiger