Maenttaeri, M.; Nuortila-Jokinen, J.; Nystroem, M. [Lappeenranta Univ. of Technology (Finland). Dept. of Chemical Technology
Nanofiltration was studied as a purification method of paper mill effluents so that the permeates could be used as press section shower water. The quality of ultrafiltered water was not assessed to be sufficiently high for that purpose. The low flux of nanofiltration membranes has restricted their use in the pulp and paper industry. This study showed that the performance of nanofiltration membranes can be improved by controlling the filtration conditions, like pH, flow velocity and pressure. It was demonstrated that a critical flux exists also for nanofiltration membranes. By adjusting the permeate flux below this critical value fouling should be low. The experiments with a spiral wound element showed its sensitivity to plugging by fibers and also the unsuitability of cartridge filters as safety filters for it. Better pretreatment methods are needed. A multilayer filter seemed to decrease the fouling of the nanofiltration element somewhat. However, a simple and cleanable pretreatment method still needs to be developed. Fouling experiments with model components pointed out the importance of pH and cross-flow velocity in minimizing fouling. (orig.) 8 refs. CACTUS Research Programme
Kaijaluoto, S. [VTT Energy, Jyvaeskylae (Finland)
The research to be done in the CACTUS research programme produces new process models and generates new knowledge about the influence of various contaminants on the runnability and the quality of paper. The generated information calls for an environment where it can be analysed and utilised. The goal of the project is to build a design environment for papermaking processes. The environment will be composed of a number of tools, all integrated together, that can be used in process design from preliminary concept screening through detailed simulation studies to the design and tuning of control systems. The design environment is based on the Balas and APMS simulation programmes developed at VTT. Balas is a general steady-state simulation package for chemical processes with emphasis on pulp and paper. Recent applications include the analysis of the influence of new drying techniques on the energy and water management of a paper mill and the evaluation of new paper machine and water treatment concepts. APMS (Advanced Pulp and Paper Mill Simulator) is a new flexible tool intended for fast modelling and efficient simulation of the dynamic performance the various unit processes in pulp and paper mill, or even of the whole integrated mill. (orig.)
Mustranta, A.; Buchert, J. [VTT Biotechnology and Food Research, Espoo (Finland); Ekman, R.; Spetz, P. [Aabo Akademi, Turku (Finland). Lab. of Forest Products Chemistry; Luukko, K. [Helsinki Univ. of Technology, Otaniemi (Finland). Paper Technology
Dissolved and colloidal substances (DCS) are dispersed into the process waters during different stages of pulp and paper production. These are lipophilic extractives (pitch), hydrophilic extractives (lignan) and carbohydrates, mainly hemicelluloses. These dissolved and colloidal substances accumulate during water circulation and results in impaired paper machine runnability. DCS can also interfere with wet-end process chemicals. In this project the chemical composition of the process waters of spruce TMP pulping have been characterized. Simultaneously, potential enzymes for modification of DCS has been produced and purified. The enzymatic treatments have been started with lipase acting on triglycerides present in extractives. The effect of enzymatic treatment on the properties of process waters and technical properties of the pulp have been evaluated. (orig.)
Pekuri, T.; Pekkanen, A. [UPM-Kymmene Oyj, Valkeakoski (Finland)
This WACI-project was divided into several subprojects, which were started with gathering of present knowledge and entering to laboratory and pilot tests. In some projects there were mill scale trials in water connections and internal purification systems. In the `Quality Demands of Water` subproject the process waters used in the printing paper machines of UPM-Kymmene were surveyed. Lab tests were made for the different applications like shower, washing, seal and dilution of internally purified circulation waters. In `Mechanical Pulp Washing` project the target was to study how the different water connections around the TMP washing press will affect the paper machine runnability. It was also started to develop separating technique for TMP fibre extractive. `Micro and Electroflotation` studies have been made mainly on pilot scale but also in new mill-scale unit. `Membrane Technology` research consisted of both lab, pilot and mill scale studies, where different membrane qualities with different process waters have been tested. `Evaporation` trials were made on pilot scale for different process waters and condensates and concentrates were analysed. Condensates were tested for different applications. The possibility to `Reuse Waste Water` concentrated mainly on how to remove the brown colour. `Simulations` were done to find out what will be the new dcs balance in different wet end processes after new water connections including so-called kidneys. In the `Paper Quality` subproject the effects of dcs on bonding ability of TMP fibres were studied on lab scale with artificial pitch component and also with circulation concentrates. This 2.5 year Tekes-project was completed at the end of April 1998. (orig.)
Mattelemaeki, R. [Enso Oyj, Imatra (Finland)
The objective of the project was to study which levels of organic and inorganic substances could be obtained by treatment of waste waters of mechanical pulper and paper machine biologically and after that with solid matter removal. Another target was also to test the utilisation of the purified water in pulp and paper manufacture, and to study the properties of purified water. The three months test runs with PK 4 and TMP plant clarified waters were carried out using a pilot-scale plant, which also consisted of two serial aerobic bioreactors and a parallel anaerobic line as a reference. The solid matter was removed by chemical flocculation, flotation and sand filtration. The purification efficiencies of both waters were similar both in aerobic and anaerobic lines. The reduction of soluble COD in biological stage was about 75 % and that of the whole line about 85 %. The solid matter reduction was 60-70 %. Solid fines, including bacteria, could not be removed sufficiently from the water by flotation and sand filtration so the water cannot be recommended to be used to replace fresh water. Circulating water sheets were produced, and pulp washing tests, retention tests and microbiological tests were carried out in order to estimate the recyclability of the water. Minor lowering of whiteness of the sheets were observed when a part of the fresh water was replaced with recycled water. Microscopic analysis shoved that after the sand filter there were a lot of free bacteria in the water. Further research will be concentrated to recycling of purified water, e.g. To research on how the colour of the water effects on the quality of the product. (orig.)
Compounds in paper machine water circulations and the effect of closure on the papermaking process and product quality; Paperitehtaan kiertovesiin rikastuvat aineet ja vesikiertojen sulkemisen vaikutukset paperivalmistusprosessiin ja lopputuotteen ominaisuuksiin - MPKT 01
Laine, J.E.; Paltakari, J.; Paulapuro, H. [Helsinki Univ. of Technology, Otaniemi (Finland). Paper Technology
The goal of the project is to study the factors involved in the closing of the water circulation of a paper machine from the standpoint of the properties of the paper as well as the stability and the runnability of the process. The purpose is to identify critical variables of the process, their mechanisms and to find the best possible strategy to run the paper machine. (orig.)
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