Determination of annual heat losses from heat and steam pipeline networks and economic analysis of their thermomodernisation

•Method of selective evaluation and thermomodernisation of heat pipeline networks.•Concept of evaluation of the pipeline on the basis of its one-off infrared testing.•Method of forecasting annual heat losses from existing pipelines under operation.•Simulation of pipeline network operation in terms of its heat losses within a year.•Example of evaluation of existing pipeline network in real industrial plant.

The paper presents a method of evaluation and selective thermomodernisation of overhead thermal pipeline networks. The expression “thermomodernisation” is used for determination of all those activities that deal with improvement of heat insulation features of the pipelines under consideration. The method is particularly useful for extensive and complex heat or steam pipelines. A novel method for the determination of annual heat losses from overhead pipelines into the environment has been developed in the work. The heat losses from the pipelines are generated during the whole year. The proposed method is based on the concept of one-off examination of the pipeline under consideration by means of a thermovision camera, performed in existing weather conditions. An example of an analysis has been carried out and results are presented for an existing industrial pipeline network. In this analysis the whole pipeline network was divided into segments characterised by identical technical features. To determine the annual heat loss, the operation of the considered pipeline during the whole year in different meteorological conditions was simulated numerically. Next, economic factors were calculated for each pipeline segment. Generally, the selection of line segments recommended for thermomodernisation was done on the basis of heat losses and SPBT (simple pay-back time) calculations.