Oxygen solubility in high-temperature water at 220°C

Under high temperature and pressure conditions, the calculation of oxygen solubility in water is complex, as it involves the thermodynamic properties of water as well as the solubility of oxygen in water, all of which change with variations in temperature and pressure. Traditional models for gas solubility in water, such as Henry’s law, may no longer be applicable under high temperature and pressure conditions. You can refer to the formulas and data tables for thermodynamic properties published by the International Association for the Properties of Water and Steam (IAPWS); these typically provide accurate information on the thermodynamic and transport properties of water and water vapor, including data under high temperature and pressure conditions. When using process simulation software such as Aspen Plus for simulations, you need to select appropriate property models and take into account the gas-liquid equilibrium (VLE) conditions. In Aspen, the solubility of oxygen in hot water can be simulated by defining components and setting temperature and pressure, using appropriate property methods such as the NRTL, UNIQUAC, or Peng-Robinson equation of state. During the simulation process, you may also need to rely on experimental data or correlation coefficients from literature to adjust the parameters in order to ensure the accuracy of the model. The specific steps may include: 1. Setting your constituent species in Aspen, which are water and oxygen here. 2. Enter the operating conditions, including a temperature of 220°C and the corresponding pressure. 3. Select a property method suitable for high-temperature and high-pressure systems. 4. Run VLE calculations to simulate the solubility of oxygen. For systems under high temperature and pressure, it is highly recommended to consult specialized chemical engineering literature to obtain more accurate data and calculation methods, and collaboration with experts in this field may be necessary. .

At a high temperature of 220°C, water is beyond the normal temperature range of liquid water (0–100°C under standard atmospheric pressure), and is in a state close to or above its critical point (374.12°C, 22.064 MPa). Under these conditions, the properties of water are similar to those of a supercritical fluid, and the solubility of oxygen is strongly influenced by temperature, pressure, and the physical state of water. Under such extreme conditions, it becomes very difficult to use empirical formulas directly to calculate the solubility of oxygen. It is usually estimated using experimental data or advanced equation of state models (such as the Peng-Robinson equation of state). For process simulation software like Aspen, although it can be used to simulate various chemical processes, simulating solubility under supercritical conditions may require special models and parameters. You need to use Aspen Plus or Aspen HYSYS and select appropriate property models; experimental data may be required to adjust the model parameters in order to accurately predict solubility under supercritical conditions. I recommend that you consult relevant books on chemical thermodynamics, especially those covering supercritical fluids, as well as scientific literature and databases such as the NIST Chemistry WebBook; these may provide experimental measurement data on the solubility of gases in water under high temperature and pressure conditions. If no existing data or models are available in Aspen, it may be necessary to measure the actual solubility data in the laboratory, and then enter this data manually into the simulation or create custom models. It is recommended to work with process simulation experts or chemical engineers to ensure an accurate simulation of this complex system. .

“Is it possible to store hot water at 220°C in a tank, using high-pressure air to maintain pressure and keep the water in a liquid state? Is this a condition that exists in reality? Could it be nothing but wild speculation? Compared to actual operating conditions, a boiler is a system in which high-temperature steam and high-temperature hot water coexist; therefore, the boiler feed water should be deoxygenated. There’s also steam condensate. I remember there was a deaeration station specifically designed to remove the dissolved oxygen from the condensate before it is sent back to the boiler. To obtain a liquid heat source at 220 degrees, heat transfer oil is typically used. Air protection cannot prevent hot water from evaporating into steam. According to the law of partial pressures, the pressure in this closed system should be the saturated vapor pressure of water at 220 degrees Celsius plus the pressure of the air trapped inside