Diagnostic Measurement at Chimney Operation

Abstract

The article is focused on the solution of heat penetration through the body of a chimney based on the measurements of output temperatures of flue gases coming out of a chimney and their dew point, in order to determine the minimum flue gas temperature at the bag filter inlet. INTRODUCTIONThe personnel of the Department of Power Engineering of the VŠB-TU Ostrava have recently solved a very interesting and unusual task. The unusual nature of the task rested both in the very subject in question and in the location of the required measurement points. One of the measuring sites was located at the top (head) of the chimney. This meant repeated climbing up the ladder to a 123 m high chimney, installation of thermocouples in the outlet section of the chimney, installation of the measuring system on the highest gallery of the chimney, stretching connecting S-net cable between the measuring system and a PC located in the measuring vehicle. Last but not least, the activities also included measurements of surface temperatures of the chimney shaft at four levels. The subject of the solution was to find the heat penetration coefficient through the chimney wall and to measure the flue gas temperatures at the outlet of the chimney, before and after its repair, and to find the dew point of the flue gases, etc. The main objective of the task was to determine the minimum flue gas temperature before the bag filter in order to prevent condensation of flue gases in the bag filter and in the chimney as well.The task also included detailed screening of the flue gas temperature at the outlet of the chimney at minimum boiler output power and calculation of the change of the heat penetration coefficient through the chimney wall, depending on the performed chimney shaft repairs.At this point, it is convenient to inform you that the concrete measurements took place during combustion of various mixtures of brown and black coal and biomass. MEASURING SYSTEM, MEASURING METHODS, MEASURING POINTSThe values necessary for subsequent calculations to meet the desired objectives were measured using both an independent technique, operated by the Department of Power Engineering personnel, and by reading the operating instruments. Continuous monitoring of flue gas temperature values was performed using SOLARTRON Schlumberger measuring system, calibrated in the stateaccredited laboratory.Flue gas temperature at the inlet into the chimney t sp1 has been determined by means of network continuous measurement technique using 9 pieces of thermocouples type "K", placed in a rectangular sheet-metal flue gas ducting before the flue gas enters the concrete chimney at the height of +8 m above the ground.The flue gas temperature at the outlet of the chimney t sp2 was continuously measured at the mouth of the outlet confusor at a height of +123 m. 5pcs of thermocouples type "K" located in the outlet section were used to perform the measurements.

Theoretic Assessment of Possibility of Leg Ventilation Duct in Thermal Insulation System of a Renovated Apartment Building

“…The calculation is based on the assumption that the coefficient of friction is calculated for the stationary air temperature in duct -18 °C. Roughness is selected according to [14] for aluminium pipes in values 0.0015, 0.003 and 0.1, for galvanized sheet 0.15, 0.5. In the case of plastic pipes (ducts) is roughness ignored.…”