Development of water deaeration technologies with boiler exhaust gases

The calculation of the heat and mass transfer efficiency of the proposed technology for deaeration of water by the exhaust gases of a gas-proof boiler in deaerators of serial design has been performed. The conditions and criterial values of the media consumption in the apparatus have been studied. It is shown that the technology can be successfully applied in operating thermal power plants.

Investigation and Evaluation of Potential Aerosol Release by Maquet/Getinge Heater–Cooler Units Used during Cardiac Surgery

Background Heater–Cooler units (HCUs) supply tempered water through blood heat exchangers and through warming/cooling blankets to control the body temperature of heart surgery patients. Bacteria which potentially colonize the stored water may escape from the tank into the environment and are carried by the device's cooling air exhaust into the sterile field and finally may infect open chest heart surgery patients. Reports from several countries are connecting the infection of open chest heart surgery patients to airborne transmitted Mycobacteria chimaera which were found in the water of heater–cooler devices. As a consequence of the vigilance system for medical products, we investigated the potential release and the possible transmission of bacteria from the tank water into the sterile operating field. Materials and Methods In the absence of an evaluation standard for this problem, measurable acceptance criteria for particle releases and a qualitative method for bacteria transmission assessment have been deployed. To assess potential bacteria transmission into the sterile field, tank water of the test devices was inoculated with high concentrations of Pseudomonas aeruginosa (reference strain ATCC15442) and operated in an operating room with simulated use. Results The particle release at the tank lids of the Maquet/Getinge HCU 30 and HCU 40 during the filling of the tubes with water (deaeration) and during the removal of water from the tubes (emptying) increased slightly, but close to the blank readings for the larger particles. As expected, the particle release at the cooling air grids was higher than around the tank openings. Consistent with the particle measurements, no bacteria from the tank water were found in the sterile field during simulated use of all highly inoculated machines in an operating room. Conclusion In summary, we assess the risk of infecting open chest heart surgery patients with aerosol-transmitted bacteria from water inside the Maquet/Getinge HCU 40, HCU 30 to be negligible, if handled in accordance with common clinical hygienic precautions.

Evaluation of moraine loams' filtration properties

In Lithuania, surface moraine loam, clay and other lithologic varieties with low permeability take around 60% of the territory. Roads, railway tracks, bridges, dumps intended for keeping waste of different level of danger and other overground structures are built in these areas. Moraine formations with low water permeability become the foundation for earth bank, roads, bridge supports, dumps and other engineering structures. Through these foundations water filtration, infiltration, movement of capillary water and evaporation to the atmosphere continue during the entire period of operation. In wintertime, the volumetric changes of water, contained and freezing in these soils, and water migration in soil towards the surface of freezing determine deformations of foundations or road surface and the occurrence of frost cracks. All the mentioned water migration processes in the layers take place in various directions and in different intensity. This determines the change in geomechanical and geofiltration properties of foundation soils. Foundation soil deformations are likely also due to the processes of drying, bloating and filtration of clayey soils. Thus, the goal of the present work is to evaluate the evolution of filtration features and evaporation intensity of moraine loam in time. The continuous duration of laboratory investigations was over 10 months. For filtration, the filtrometer was used containing the Proctor Standard moulds, water deaeration device and pressure measuring stand with three tubes of different diameter (piezometers). Water and air temperature and relative humidity of the laboratory were measured during each experiment.

Paper machine white water deaeration and two-stage flotation with channel flow

Detrimental substances that originate from deinked pulps and other raw materials tend to build up in paper machine circulation waters, hindering process efficiency and paper quality. The applicability of selective flotation to remove substances from circulation waters was investigated in a two-stage flotation process in which no chemical additives were used. The first stage of the process consisted of a flow channel for white water deaeration, including first-stage flotation. The overflow of the channel flow flotation was further treated in a separate second-stage flotation. The efficiency of the flow channel and a secondary flotation to remove bubbly gases, ink, stickies, and wood extractives were quantified in relation to the reject flow rates or solids yield. The total removal efficiency of a simulated two-stage flotation process was then analyzed for a specific case. The results showed that a considerable reduction of contaminant load can be obtained using a two-stage flotation process without affecting the deaerating function of the channel flow. Further optimization of the proposed internal white water purification scheme may provide substantial benefits to paper or board machine operations with reasonable solids recovery rate.