Water is vaporized by steam

What pressure is required for the secondary steam? At atmospheric pressure? Let me give you a rough estimate by mental calculation – it should be over 50 tons. For such a large project, it’s better to leave it to professionals

To supplement the algorithm: The technician’s algorithm involves tools such as Aspen for entering data and obtaining results; the details of the process are omitted. Engineer’s estimation: The specific heat of steam is around 2 kJ/kg/°C, and the latent heat of vaporization is around 2000 kJ/kg. Cooling steam from 200°C to 100°C to evaporate hot water: 2000/(200-100)/2=10 times. In other words, 10 times as much steam is needed. Considering the temperature increase of water, with a specific heat of 4 kJ/kg/°C, and adding the factor of 4/2 = 2, the value is at least 12 times that, which amounts to 60 tons.

It seems to me that your calculations are reliable. To add some clarification for those who are not experts, it will be easier to understand. In the heating section, steam at 200 degrees is reduced to steam at 100 degrees, resulting in the consumption of sensible heat; the amount of heat q1 is equal to specific heat * temperature difference * mass, that is, 2*100*m1. On the heating side, the process occurs in two steps: first, water absorbs sensible heat as it rises from room temperature to 100 degrees, with the amount of heat q2 being equal to 4*100*m2. Secondly, the vaporization of water at 100 degrees requires 2250 units of latent heat of vaporization, not 2000. q3=2250*m2; q1=q2+q3. Therefore, m2=13.25 and m1=66.25 tons

The calculations upstairs are more or less the same. A few additional remarks. 1.0.8 Mpa – it is not clear whether this refers to operating pressure or gauge pressure, so it should be used only as a reference. The saturation temperature of saturated steam at 2.0.8 Mpa is around 170.4, while it is around 175.4 at 0.9 Mpa. The poster’s value of 200 degrees Celsius indicates superheated steam, whose enthalpy should be around 2800. Superheated steam releases its superheat energy to become saturated steam; saturated steam then releases its latent heat and mixes with water. This amount of superheat energy also needs to be taken into account. 3. The calculated values are generally conservative; taking into account pipeline losses and leaks, the actual amount should be higher, so it’s reasonable to assume a value of around 75 tons or less. 4. Water turns into a gas at 100°C under normal pressure; if there is pressure present, it needs to be calculated separately.

For those not majoring in chemical engineering or thermal engineering: an approximate calculation – what the poster is referring to is using steam at 0.8 MPa and 200 degrees Celsius to directly convert 5 tons of water into a gaseous state. My understanding is also that superheated steam at 0.8 Mpa and 200°C is converted into saturated steam through a temperature-reducing pressure regulator. 5 tons of desuperheated water are introduced; after mixing, the resulting steam has a pressure of 0.8 Mpa. It is necessary to determine how much steam can be produced in this condition. The pressure is absolute pressure, and the temperature of the desuperheating water is assumed to be 20°C. According to the \"Chart of Properties of Water and Heat,\" the enthalpy values of superheated steam, saturated steam, and desuperheated steam are 2838.5584 kJ/kg, 2767.46 kJ/kg, and 84.612 kJ/kg, respectively. Energy conservation: the enthalpy of the incoming steam multiplied by the amount of incoming steam, plus the enthalpy of the injected water multiplied by the amount of injected water, equals the enthalpy of the outgoing steam multiplied by the amount of outgoing steam. The steam input is approximately 190 tons.

This post was last edited by xyq1983 on 2021-3-25 at 16:08. A P-H diagram is used to illustrate the changes in temperature and pressure of steam; all relevant thermodynamic data can be seen on the diagram

Thank you to the original poster for sharing; it’s great material!

This post was last edited by xyq1983 on 2021-3-25 at 18:07. The question is problematic – the superheat of steam at this specification is not high; to vaporize 5 tons of water, a large amount of steam is required