Improvement of the demin water plant for steam production with AquaSPICE Project

Identifier:  TFG:5544

Handle: https://hdl.handle.net/20.500.11797/TFG5544

Authors:  Heras García, Eduard de las

Abstract:
Organic acid anions are formed in boilers by hydrothermolysis due to the presence of organic carbon in the boiler water[1]. This generates corrosion on the steam-water cycle components, increasing the amount of condensate generated, and reducing the lifetime of the components and the boiler efficency[2]. Optimizing water production and specifications are key to avoiding water losses in industrial processes. The Dow Böhlen processes are highly dependent on water, both for cooling and steam production. Fresh water is taken from primarily two sources, Lake Witznitz and River Elster. This is further processed to achieve the required specifications to use as cooling tower make-up (CTMU) and supply for the Demin water production. Dow key water-stressed sites, such as Böhlen, have set a global target to reduce freshwater intensity by 20% by 2025 [4]. This thesis evaluates how to enhance the existing Demin Water production plant with the objective of obtaining the required water specifications to meet site needs and future demand. This reduces the corrosion formation in the equipment downstream while avoiding unnecessary losses in the form of condensate. Two mobile research facilities (IMPROVED containers) from the University of Gent are used to perform pilot tests and select the most appropriate technology train. These containers comprise several water treatment technologies which can be configured in different sequences and equipped with smart controls and online sensors that ensure a safe and stable continuous operation. Six different technology trains have been evaluated. A technology train composed of a pre-treatment of coagulation/flocculation followed by rapid sand filtration and ion exchange resins has been selected. The proposed train adds into the current demin water system an organic scavenger SCAV4 Cl resins column, this presents affinity within specific hydrophobic organic compounds and biopolymers that are not removed within the current treatment. The fact of adding this step allows Dow to reuse most of the assets in the existing demin water plant (lower CapEx) while meeting the desired specifications, thus, resulting in the most cost- effective solution. A full-scale design is proposed to modify the existing demin water, including the design of the new column and pumping system. This will help the Dow Bohlen site to have a first general estimation for further evaluate the implementation of this project. Total capital of 3.5 million euros1 is estimated through TURTON’s methodology to modify current assets.