| 摘要 |
PURPOSE:To pevent the corrosion of a waste heat recovery heat exchanger by sulfuric acid liquid by controlling the flow rate of brine to the heat exchanger in such a way that temperature detected by a temperature detector provided inside a waste heat duct becomes higher than the dew point temperature corresponding to the concentration of sulfuric acid vapor in the gas inside the waste heat duct. CONSTITUTION:A SO3 concentration detector 10 is provided in a duct 1a on the upwind side of a waste heat recovery heat exchanger 3, and also a temperature detector 11 is provided in the duct 1b on the downwind side. A SO3 concentration signal a and a temperature signal b are put in an arithmetical controller 12 where calculation is made in such a way that the temperature inside the duct 1b becomes higher than the dew point temperature all the time, and a signal C to control a flow rate controller 7 is send out. By this, the flow rate of brine to the heat exchanger 3 is adjusted. For example, when the detector 10 detects a SO3 concentration of 10ppm, dewfall is likely to occur on the surface of the heat exchanger 3 when the temperature of waste gas is about 130 deg.C. Thus, the circulation amount of brine is reduced by throttling the valve 7 in such a way as to lower the temperature of waste gas to about 150 deg.C. |
