ANALYSIS OF WORK PARAMETERS OF THE FORCED-DRAFT MACHINES WITH DIFFERENT ANGLES SETTINGS OF IMPELLERS BLADES

In the thermal power plants and heating plants about 30% of the total cost of energy for their own needs is spent on the forced-draft system. When these systems were designed and was created the basic capacity thermal power complex, as blowers were used forced-draft machines: VD series draft fans and exhaust fans series D. Development of fan structure and aerodynamics оf the blade flow in the impeller predetermined ineffectiveness of used impeller design with forward curved blades and approved the higher performance for fans with backward curved blades. In order to save energy sources instead of draft machines series VD and D mainly were used blowers series VDN and DN. Installation of new high-efficiency blowers led to efficiency increasing, but at the same time occurred a significant reduction of the boiler thermal rating. Focusing on maximum fan efficiency, modern blowers basically became a system limiting problem, which causes draft and forced draft systems production limiting. Analysis of aerodynamic parameters of the most common draft machines VD - 15,5 and VDN - 17 showed that on the characteristics of the VD - 15,5 with rotations n = 730 rev / min in maximum efficiency ηv = 70%, the fan supplies Q ? 65 K. m3/hr and at maximum efficiency fan VDN- 17 efficiency ηv = 85%, the supply in the zone of maximum efficiency does not exceed Q ? 56 К. m3/hr. According to the comparison of the parameters can be seen that blowers performance with forward curved blades is up by 20% and the efficiency is 15% lower. Selection priority in the process of design and modernization of forced draft systems between two types of fans still has not been resolved. Therefore to summarize and derive concepts to solve the problem of optimal choice of a blower were made the following general conclusions: - Changing the approach to the economic value of optimal operating mode TDM providing their stable work will partially solve the nominal power derating problem of heating boilers and thermal power plants; - Indication of the aerodynamic efficiency of the systems is still efficiency blowers - fans or smoke exhausts that doesn’t fully reflect processes in the power systems, as blowers are only part of the complex processes of compression and transportation of air or flue gas; - It is advisable to analyze the representations of forced-draft parameters of the boilers, and the calculation of the efficiency of their work in order to have more accurate representation of the characteristics of blowers as well as individual sections of aerodynamic systems.