1. Definition and parameter range of medium temperature and medium pressure

Medium temperature and medium pressure is a key parameter system in the field of industrial thermal energy. Its temperature range is usually defined as 150℃ to 300℃, and its pressure range is 0.6MPa to 4.0MPa. This parameter range is widely used in industrial scenarios. For example, in the drying and setting devices and hot melt dyeing devices in the textile printing and dyeing industry, medium temperature and medium pressure steam can provide a stable heat source; in the chemical industry, the heat energy of this parameter can be used for distillation, evaporation and other process processes; in the food processing industry, medium temperature and medium pressure steam can meet the needs of sterilization and drying. Its core value lies in the precise control of temperature and pressure to achieve efficient conversion and utilization of energy, avoid equipment loss and safety hazards caused by high temperature and high pressure, and avoid insufficient utilization of heat energy caused by low temperature and low pressure.

2. Typical application scenarios of medium temperature and medium pressure technology

Industrial waste heat recovery and power regeneration
In heavy industrial fields such as steel and fertilizer, a large amount of medium temperature and medium pressure waste gas is generated during the production process. For example, a small fertilizer plant with an annual output of 10,000 tons has an exhaust gas flow rate of 450m³/h (under standard conditions) and a calorific value of 14,600kJ/m³ (under standard conditions). After voltage stabilization measures, the exhaust gas can directly drive a 200kW gas turbine, and the exhaust gas of the gas turbine can also be used as a heat source for a waste heat boiler to produce 0.3MPa saturated steam. It is estimated that such a waste heat power recovery system can recover all investments within three years, significantly reducing the energy consumption costs of enterprises. Steam supply and process heating
Medium-temperature medium-pressure steam is the "blood" of industrial production. In the printing and dyeing industry, traditional thermal oil furnaces have problems such as low operating efficiency, high energy consumption, and high failure rate. Medium-temperature medium-pressure steam boilers can replace thermal oil furnaces and provide a stable heat source for drying and setting devices, hot melt dyeing devices and other equipment. Taking a 10-ton medium-temperature medium-pressure gas boiler as an example, its thermal efficiency can reach more than 90%, which is 15%-20% higher than that of a thermal oil furnace, while reducing exhaust gas emissions by more than 30%. In the field of food processing, medium-temperature and medium-pressure steam can be used for processes such as sterilization and drying to ensure product quality while reducing energy consumption.

Thermodynamic equilibrium in refrigeration systems
The medium-temperature and medium-pressure parameters are also critical in the field of refrigeration. For example, R22 refrigerant (chlorodifluoromethane) is a typical medium-pressure and medium-temperature refrigerant with a boiling point of -40.8°C, a critical temperature of 96°C, and a critical pressure of 4.974MPa. In air-conditioning refrigeration systems, R22 realizes the refrigeration cycle through compression, condensation, expansion, evaporation and other processes. The condensation process requires the conversion of high-temperature and high-pressure gaseous refrigerant into medium-temperature and medium-pressure liquid. This process directly depends on the control of medium-temperature and medium-pressure parameters. In addition, R410A refrigerant (a mixture of R32 and R125) is a substitute for R22. Its operating pressure is 50%-60% higher than that of R22, but by optimizing the system design, efficient refrigeration can still be achieved within the medium-temperature and medium-pressure range.

3. Economic and environmental benefits of medium-temperature medium-pressure technology

Energy cost optimization
Take a chemical enterprise as an example. After using medium-temperature medium-pressure steam boilers to replace traditional thermal oil boilers, it saves about 2,000 tons of standard coal and reduces carbon dioxide emissions by more than 5,000 tons per year. At the same time, the thermal efficiency of the medium-temperature medium-pressure system is 10%-15% higher than that of the low-temperature low-pressure system, further reducing the energy consumption per unit product.

Extended equipment life
The medium-temperature medium-pressure parameters can reduce equipment thermal stress and reduce material fatigue damage. For example, in the field of waste incineration power generation, the superheater material requirements of medium-temperature medium-pressure boilers (400℃, 4.0MPa) are lower than those of medium-temperature sub-high-pressure boilers (450℃, 6.5MPa), and the equipment maintenance cost is reduced by 20%-30%.

Enhanced environmental compliance
The medium-temperature medium-pressure technology can reduce the emission of pollutants such as nitrogen oxides (NOx) and sulfur dioxide (SO₂). For example, by optimizing combustion control, the NOx emission concentration of medium-temperature medium-pressure boilers can be controlled below 50mg/m³, meeting the national ultra-low emission standards.

4. Future development trend of medium temperature and medium pressure technology

Intelligent control upgrade
With the development of industrial Internet technology, medium temperature and medium pressure systems will achieve real-time monitoring and intelligent control. For example, by collecting temperature, pressure, flow and other parameters through sensor networks and optimizing the combustion process with AI algorithms, the system thermal efficiency can be further improved by 5%-8%. New energy coupling application
Medium temperature and medium pressure technology can be combined with new energy such as solar energy and biomass energy. For example, in the field of solar thermal power generation, medium temperature and medium pressure heat storage systems can solve the problem of intermittent solar energy and achieve 24-hour continuous power supply.

Low-carbon refrigerant substitution
With the implementation of the Kigali Amendment to the Montreal Protocol, traditional refrigerants such as R22 will be gradually eliminated. Medium temperature and medium pressure refrigeration systems need to transform to low-carbon refrigerants such as R290 (propane) and R744 (carbon dioxide). For example, the GWP value of R290 is less than 20, which is more than 99% lower than that of R22, but its flammability and explosion problems need to be solved. Safe application can be achieved by optimizing system design (such as limiting the injection volume and using explosion-proof motors).

5. Conclusion

As the core engine of industrial energy conservation and efficient energy utilization, the value of medium-temperature and medium-pressure technology is not only reflected in parameter optimization and equipment upgrades, but also in promoting the green transformation of the industry. From power regeneration of waste heat recovery to thermodynamic equilibrium of refrigeration systems, from process heating of chemical production to coupling application of new energy, medium-temperature and medium-pressure technology is reshaping the paradigm of industrial energy utilization with its "precision, efficiency and low carbon" characteristics. In the future, with the breakthrough of intelligent control and low-carbon refrigerant technology, medium-temperature and medium-pressure technology will play a greater role in the global energy transformation and provide key support for building a clean, low-carbon, safe and efficient energy system.