An original method for estimating fouled deposit thickness on the inside surfaces of natural gas cooler tubes is presented. This method does not require opening and inspecting a cooler as it is based on the measurement of gas cooling degree, i.e. the gas temperature difference between the cooler inlet and discharge. The deposit layer on the internal heat transfer surfaces is of semi-liquid consistency and its thermal conductivity coefficient has not been investigated until now. This paper describes the experimental determination of the deposit thermal conductivity coefficient. This parameter enables determination of a cooler's performance as a function of current deposit thickness. Practical application of the method is illustrated in the case of CH_R cooler working in the KS01 compressor station in Veľké Kapušany, Slovakia. For this type of cooler, a diagram for deposit thickness as a function of the gas cooling degree is presented.

The article describes a methodology for determination of permeability and inertial resistance coefficient of filter inserts used for the separation of solid and liquid impurities in natural gas. The parameters of the filter inserts are described by analytical relations and their real values are obtained experimentally. The realized experiment was focused on the measurement of the pressure drop in the insert, with which both permeability and inertial resistance coefficient were possible to be expressed. The experiment was performed on the reduced physical model of the filter separator, which was constructed at a scale of 1:127. During the experimental measuring the working medium was pressure air. In a real filter separator there is compressed natural gas used as the working medium. The reduced model, therefore, had to meet the basic requirement of similarity of flowing in the model and the real object, which was based on equality of the Reynolds criteria for the work and the model.

The paper summarizes the experiences acquired from on-line acoustic emission monitoring (herafter AE) of heavy castings during their manufacturing (solidification and following cooling in the mould). They are usually monitored elastic waves generated above all by stress changes in the solid state. In order to exactly determine plastic-elastic transition state the investigation was focused on raising the sensitivity of detection. The suitable experimental technique is discussed in the first part of this article. The main problem of the measurement by high temperatures was solved by using waveguides. It is very important in this case to select useful signal sources from mechanical and electromagnetical disturbances. Some laboratory experiments were done for studying the signal origin in the first state of solidification. The results from on-line monitoring of two types cast rolls during manufacturing were compared. Each type of casting has its typical AE histogram. For the quality evaluation ( in our case) is significant the time period of approximate 5 days after pouring . The time delayed stress induced cracking generates high level AE signal in this time period and the presence of such signal indicates defective product. The study of high temperature tensile tests, structural phase transformation and solidification processes using AE is very important for analysis of AE sources. The use of the laboratory results for the AE source analysis on real products will be subject to futher research.