Is it more energy-efficient to convert superheated steam into saturated steam?
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Dear experts, I earnestly beg for the correct answer. At present, our facility uses superheated steam at 0.7 Ma and 240 degrees to heat materials in heat exchangers. I plan to reduce the temperature of this superheated steam by using saturated condensate at 120 degrees for cooling. My calculations show that approximately 83 kg of condensate is needed to cool 1 ton of superheated steam. The calculation process is as follows: the heat enthalpy of superheated steam at 0.7 Ma and 240 degrees is 2955, while that of saturated steam at 0.7 Ma and 170 degrees is 2768. The heat enthalpy of the condensate used for cooling, at 0.1 MPa and 120 degrees, is 503. To cool 1000 kg of superheated steam, 120 kg of saturated condensate is required, calculated as follows: 1000 * (2955 – 2768) / (2768 – 503) = 83 kg. There are two main issues: 1. Is my calculation method correct? 2. When heating the same material using the same heat exchanger, and with superheated steam and saturated steam at the same pressure, which method is more cost-effective? How much can the difference be?
Did the condensate at 0.1 MPa and 120°C turn into saturated steam at 0.7 MPa and 170°C? ;P
Let’s not discuss whether the calculations are correct for now. I would like to ask you: from a cost perspective, would it be cheaper to use saturated steam instead? Generally, superheated steam is used to prevent condensation during pipeline transportation; of course, in terms of process operation, pressure reduction from the main pipelines still results in superheated steam… in order to avoid the formation of condensate water. ------------------------------------------------------------------------------------------------- It goes without saying that, in terms of energy supply, superheated steam can provide more energy than saturated steam. ------------------------------------------------------------------------------------------------ So... it is recommended to proceed with the process in this manner. As for the equipment, it depends on whether its design and operating temperature can handle such high temperatures. ------------------------------------------------------------------------------------------------ The above are my suggestions
Everything has been explained upstairs; it is suggested that the original poster sort out the details more carefully
1. First, if superheated steam is cooled down and the two materials do not come into contact, then the outlet temperature of the condensed water still needs to be determined; an appropriate outlet temperature must be selected.
2. When using superheated steam for heating, the thermal conductivity of gas is low, resulting in a low overall heat transfer coefficient at the gas phase. This necessitates an increase in the heat exchange area of the equipment. Moreover, when the steam temperature is high, the temperature gradient in the heat exchanger becomes large, and prolonged operation can cause damage to the equipment.
Whether using superheated steam for heat exchange is more energy-efficient than using saturated steam is a well-discussed topic. The key points to consider are as follows: 1. Whether the use of saturated steam can meet the requirements of the material; it is well known that there is a one-to-one relationship between the temperature and pressure of saturated steam. The saturated steam pressure at 0.8 MPa is only around 176 degrees. However, if the superheat of the superheated steam is high, the temperature can be much higher than 176 degrees. Saturated steam will undergo condensation as long as there is a temperature difference with the surrounding environment. Heat loss and consumption will increase. The poster should evaluate this themselves. 2. Heat exchange efficiency issue. The heat exchange efficiency of saturated steam is much higher than that of superheated steam. In other words, using saturated steam for heating improves production efficiency, reduces corrosion of the heat exchanger, and extends its service life. From this perspective, saturated steam has advantages over superheated steam. 3. Steam cost issue. Generally, the price of high-pressure steam supplied in industrial parks is higher than that of low-pressure steam, and the price of superheated steam is higher than that of saturated steam. In terms of cost, saturated steam also has significant advantages. Comprehensive analysis: If the distance between the enterprise’s steam supply pipelines is large, it is recommended to use superheated steam with a superheat of 5–10 degrees; if the pipeline distance is short, a superheat of around 2–3 degrees will suffice. This approach helps to minimize heat losses while ensuring good steam quality.
Water at 0.1 MPa cannot be added to steam at 0.7 MPa