liquid co2 production plant recovery liquefaction and purification technology has developed rapidly in the past decade. Although the raw materials come from different sources, the process routes used are similar, which are nothing more than gas compression, purification, cooling liquefaction, and distillation.
liquid co2 production plant recovery liquefaction and purification technology
liquid co2 production plant recovery liquefaction and purification technology has developed rapidly in the past decade. Although the raw materials come from different sources, the process routes used are similar, which are nothing more than gas compression, purification, cooling liquefaction, and distillation. It’s just that the purification process is different, and the quality and energy consumption of the obtained liquid carbon dioxide products are quite different. Regardless of the quality of the liquid carbon dioxide product, most of them use the low-temperature liquefaction process in their production process, that is, the CO2 gas at normal pressure is pressurized to 2.0 ~ 3.0 MPa, and at the corresponding saturation temperature, the refrigeration unit is used to absorb the latent heat to liquefy it. The heat released during the condensation process is taken away by the refrigeration unit, so that the CO2 gas is liquefied into liquid.
Low-temperature liquefaction There are many mature technologies in the liquid co2 production plant recovery industry, but the problems of high energy consumption and high cost of CO2 recovery and liquefaction are still prominent. Although many CO2 liquefaction companies have done a lot of research and exploration in the optimization of device processes and energy-saving transformation, and have achieved good results, the energy consumption per unit product (ton of product) is still high. At present, the power consumption per ton of product of raw CO2 gas with a purity of more than 95% is 190 to 230 kW·h, and the power consumption per ton of product of raw CO2 gas with a purity of 80% to 90% exceeds 250 kW·h, and some enterprises even consume about 270 kW·h. The overall energy consumption is high, which is too different from the theoretical consumption value, and has a great impact on the cost of CO2 recovery and liquefaction of enterprises, especially in the context of the sluggish liquid CO2 market in recent years, which has brought serious impact on the economic benefits of CO2 recovery and liquefaction enterprises.
analyzes the entire CO2 liquefaction and purification process. Each process has an impact on the energy consumption and cost of its products, but the energy consumption of the process is mainly concentrated in the two key processes of compression and liquefaction of raw gas.
A brief analysis of energy consumption distribution in the process of CO2 liquefaction and purification
Taking a certain CO2 raw gas as an example, we simulate the process according to the general process through Aspen Plus software and analyze the energy consumption in the process.
In the CO2 liquefaction and purification process, the power consumption of compression and refrigeration is basically the power consumption of the entire process. Reducing the power consumption of compression and refrigeration is the key to CO2 liquefaction.
Achieving CO2 emission reduction in industrial production is a daunting challenge and an important technical route to address global warming. liquid co2 plant capture technology has been developed to a certain extent, among which the cryogenic liquefaction method is feasible and economical. The process simulation software Aspen Plus was used to simulate the entire process of the cryogenic liquefaction and separation of CO2. Three physical property methods were selected to simulate and analyze the bubble dew point line of the mixed gas, and the PR (Peng Robinson) state equation was selected as the physical property method of this process. The effects of liquefaction pressure and temperature on the liquefaction rate of the mixed gas and the CO2 purity were analyzed. The optimal liquefaction conditions were determined with the goal of a CO2 liquefaction rate of not less than 90% and a purity of not less than 99.5%. In order to minimize energy consumption, the process parameters such as cooling medium flow, condensation temperature difference, and evaporation temperature were optimized. Under the optimal conditions, the CO2 liquefaction rate reached 91.80%, the purity reached 99.50%, and the lowest total energy consumption per liquefaction unit was 12.22 kW·h/kmol.
Global warming has brought significant impacts to the world, including frequent natural disasters, ecological problems, and even harm to human health. Excessive CO2 emissions are considered to be an important cause of global warming. According to reports, the total global CO2 emissions in 2022 were about 368×108t, an increase of 0.9% compared with 2021, a record high. Among them, the industrial production process is one of the main sources of CO2 emissions, with a total of 106.4×108t of CO2 produced. Therefore, achieving CO2 emission reduction in industrial production is a daunting challenge and an important technical route to cope with global warming.
liquid co2 plant Carbon capture, utilization and storage (CCUS) is a technically feasible method that can significantly reduce CO2 emissions in industrial production and has been widely used in industrial production. At present, CO2 capture technology has been developed to a certain extent. According to different capture mechanisms, it can be divided into absorption (physical and chemical methods), adsorption, membrane separation, cryogenic liquefaction separation, chemical circulation and other methods. Each method has its own advantages and disadvantages. The appropriate carbon capture method can be selected according to the different carbon sources and process requirements. It is generally believed that the low-temperature liquefaction method is suitable for the separation of high-concentration CO2 mixed gases, and has practical feasibility and economic superiority.
Domestic and foreign researchers have conducted a lot of research on the process flow of capturing high-concentration CO2 mixed gases by low-temperature liquefaction. These studies have shown the unique advantages of low-temperature liquefaction in separating high-concentration CO2.
It avoids the replenishment of solvents and the emission of potentially harmful chemicals, can separate CO2 at lower pressures, is insensitive to impurities, and is mature in industrialization. However, the low-temperature liquefaction method also has shortcomings, such as high energy consumption and poor separation effect for low-concentration CO2 mixed gases.
Therefore, the study and screening of process conditions suitable for separating high-concentration CO2 has important theoretical and practical significance for energy saving and emission reduction in the process of separating high-concentration CO2 by low-temperature liquefaction.