Heating Performance and Application Analysis of the Low-Pressure Injection Heater With Tapered Mixing Space

A new type of low-pressure injection heater was presented. The tapered structure of the heater’s mixture space was designed. Heating performance of the low-pressure heater was studied through the experimental method. Then, the influence of entrance parameters on the outlet temperature, the outlet pressure and the ejecting coefficient were analyzed. The results show that the increase of water mass flow rate can lead to the ejecting coefficient declines under the condition of steam pressure (0.2MPa). Meanwhile, the increases temperature at the outlet can be over 60°C at the inlet water temperature T_w = 20°C. The injection heater has a good adaptability for changing the entrance parameters, which can eliminate the danger that high pressure water enters system. At the same time, based on the theory of Equivalent Enthalpy Drop Method (EEDM) and thermodynamic system state equations, the results of calculation are also shown that the optimization transformation can improve a certain economic profit. The injection heater could be used in the low-pressure feed water system of 200MW steam power plant. The calculated results also indicate that it can replace the sub-last stage surface heat exchanger and raise thermal efficiency of the whole system by 0.07%. Moreover, if all low-pressure surface heat exchangers are replaced by the injection heater, the thermal economy of the whole system can be enhanced by 0.224%.