Increasing the operation efficiency of heat exchangers with inner pipe deposits

The article studies the effect of scale formation on the efficiency of heat exchangers, as applied to condensers of steam turbines, steam-water heaters and boilers of boiler installations. The purpose of the study is to generate recommendations on how to increase the efficiency of steam turbine units (STU) condensers. This was achieved by studying the chemical and physical properties of the inorganic depositslayer and their structure; obtaining the dependencies to calculate the thermal resistance of the sediment layer on the surfaces of smooth and profiled pipes; analyzing various methods of cleaning surfaces and developing recommendations on the cleaning frequency for the capacitors. The paper also describes the results of the physicochemical analysis of inorganic salt deposition. The thermal resistance of the deposits was determined by the thickness of the scale layer and its coefficient of thermal conductivity. The layer thickness was measured with a microscope and a profilograph-profilometeron thin sections. The obtained relationship is the one between the intensity of salt deposition and the main factors determining the process: the speed of water, its average temperature and hardness, the geometry of the channel, the duration of work. Based on that it one can predict a decrease in the heat load of the heat exchanger in operation. The dependence of the influence of the temperature of the coolant and the porosity of the scale on the thermal conductivity is obtained. It is shown that in profiled pipes the scale deposition is less intensive than in the smooth ones. With a decrease in the relative depth and roll pitch, an increase in inorganic deposits is observed. The height of the knurled ridges has a greater influence than the pitch between them. The paper presents recommendations for the calculation of the relative contamination of smooth and helical-shaped tubes. The use of profiled tubes instead of smooth ones in power plants is an effective means of increasing the efficiency of power equipment. Various methods of surface cleaning are considered. An optimization technique is proposed and a technical and economic substantiation of the frequency of cleaning of heat exchangers is carried out. Rational terms of cleaning were obtained for different calendar times of the start of operation of the heat exchanger.