In the future, the market demand will present the following characteristics: high requirements on the level of product quality, such as environmental protection, energy-saving products will be the key points for future development; require the product cost-effective increase; the demand for the product's personalized, diversified trend is strong; Gradually pay attention to the selection of branded products; major projects favor large companies or enterprise group products.
The good opportunities brought by the domestic economic development and the convertibility of imported products together indicate the good development prospects of the heat exchanger industry in China. At the same time, the development of the industry must focus on the research and development of high-end products.
(1) Heat exchanger thermal protection system: The conventional thermal protection system is composed of imported smoke temperature protection and hot air temperature protection. Imported smoke temperature protection is to use cold air blower to add cold air to the front of the heat exchanger, adjust the amount of cold air according to the detected flue gas temperature, so that the smoke temperature entering the heat exchanger is not greater than the set value, thus preventing the heat exchanger tube wall Temperature is too high. Hot air temperature protection is to reduce the air temperature by reducing the air temperature by increasing the air flow when the sudden sudden load reduction of the air volume of the furnace and the flue wall due to thermal inertia can not be synchronized cooling to increase the air temperature, thereby reducing the heat exchanger tube wall temperature. The target of the above control is the wall temperature, and the detection items are all gas temperatures. In recent years, SH Company of France has added a project to directly inspect the wall temperature on the basis of the above, and has used special electric couples to fix it on multiple pipe walls to display the true temperature of the pipe wall online and improve the heat protection level of the heat exchanger. General thermal protection system flow.
(2) Heat exchanger cryogenic protection system: As mentioned above, the low smoke temperature is an effective measure to prevent low temperature dew point corrosion. A bypass is set on the air flow, and the valve on the bypass pipe is adjusted according to the temperature of the heat exchanger outlet flue gas. When the smoke temperature is too low, a portion of the cold air is passed directly from the bypass pipe without a heat exchanger to reduce the air flow of the heat exchanger to reduce the heat exchange amount and increase the exhaust gas temperature. If there is a gas heat exchanger behind the air heat exchanger, then the temperature of the flue gas after the gas heat exchanger is the control basis. This technology is common in the design of major furnace companies abroad and has not yet been applied in China.
Hot air system temperature conditions: The air preheating temperature of foreign furnace heat exchanger is often considered in the 500 ~ 600 °C, hot air pipe material is made of heat-resistant steel at this time, the temperature of the pipeline accessories such as the valve is also increased accordingly. However, China’s conditions are not the same as those in foreign countries. The main difference is that the price of heat-resistant steel is too different from the price of carbon steel. The increase in heat recovered from the air temperature between 100 and 200°C and the increase in the temperature level of the hot-air duct system increase the cost. The ratio is too inappropriate, so it is not advisable to use too high air temperature. It is advisable to use no more than 450 °C before the burner.
