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Energy Analysis and Product Quality Comparison of Supercritical CO2 Extraction: A Case Study on Sichuan Pepper

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Supercritical CO2 extraction is an efficient and environmentally friendly technique that has gained significant development in recent years for extracting natural substances. By adjusting the temperature and pressure of CO2, it can be brought to a supercritical state, forming a fluid that lies between a liquid and a gas. Supercritical CO2 exhibits high solvency and selectivity, and it can be separated from the extracted material by adjusting the temperature and pressure. With its non-toxic, odorless, non-flammable, and cost-effective properties, CO2 offers advantages in terms of both cost and product quality compared to other methods. Furthermore, the process is easily automated for continuous production, allowing for the extraction of various plant components using the same equipment.

However, current research in China on supercritical CO2 extraction primarily focuses on the dissolution and mass transfer processes of various substances in supercritical CO2, with limited reporting on energy consumption in industrial applications.

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Case Study: Energy Consumption Analysis of Supercritical CO2 Extraction of Sichuan Pepper

The process of supercritical CO2 extraction of Sichuan pepper involves the following steps:

Process Flow

  • Fluid CO2 is pumped from an outdoor storage tank to an intermediate storage tank via a CO2 pressurization pump.
  • The CO2 is then heated using a heat exchanger, causing it to transition to a supercritical state.
  • The supercritical CO2 enters the extraction vessel, where it comes into contact with the Sichuan pepper, selectively dissolving the desired components.
  • The high-pressure fluid containing the dissolved extract undergoes pressure reduction through a throttling valve and enters a refining column for primary separation.
  • The product from the column is Sichuan pepper oil resin, while the CO2 at the top of the column undergoes heating and enters the first and second separation vessels for secondary and tertiary separation.
  • The bottom of the first and second separation vessels releases Sichuan pepper oil resin, which is cooled, depressurized, and collected as liquid Sichuan pepper oil.
  • The CO2 released from the bottom of the separation vessels is recompressed and recycled.

Energy Consumption Analysis

In supercritical CO2 extraction, the main sources of energy consumption include heating, pumping, and cooling. Heating energy is provided by the CO2 heat exchanger, pumping energy by the CO2 pressurization pump and CO2 high-pressure pump, and cooling energy by the cooling water supply system. Actual measurements and analysis of energy consumption should be conducted in specific engineering applications to determine the potential for energy savings and identify improvement measures.

Energy Consumption Improvement Measures

To reduce the energy consumption of the supercritical CO2 extraction process, the following improvement measures can be considered:

  • Optimization of heat exchange systems to improve efficiency and minimize energy losses.
  • Selection of efficient CO2 pressurization pumps and CO2 high-pressure pumps to reduce pumping energy consumption.
  • Implementation of waste heat recovery technologies to recycle and utilize part of the heat energy, thereby reducing energy consumption.
  • Efficient use of cooling water through optimization of the cooling water system and circulation to minimize cooling energy consumption.

These improvement measures should be validated through engineering practices and technical research to assess their feasibility and effectiveness. Their gradual implementation can lead to energy reduction and process optimization in supercritical CO2 extraction.

Comparison of Product Quality Before and After Process Improvement

The following table presents the product quality indicators of Sichuan pepper extract before and after process improvement:

Product Quality Comparison

Production DateProductPungencyMoistureVolatile OilPungency Yield
20170506Pepper Oil Resin351.77%o0.44%Not provided89.3%
(Before)Pepper Essential Oil25.99%o0.62%830.25%oNot provided
20180302Pepper Oil Resin353.54%o0.55%Not provided89.4%
(After)Pepper Essential Oil28.4%o0.58%830.65%oNot provided

Based on the data in the table, it can be observed that there are slight variations in the product quality indicators before and after the process improvement. The pungency of the improved Sichuan pepper oil resin has slightly increased compared to the previous version, while the moisture content has also slightly increased. Similarly, the pungency of the improved pepper essential oil has slightly increased, while the moisture content remains relatively stable. As specific values for volatile oil are not provided, a direct comparison cannot be made.


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In conclusion, the case study on the energy consumption analysis of supercritical CO2 extraction of Sichuan pepper highlights the importance of considering energy efficiency in the industrial application of this technology. Various improvement measures, such as optimizing heat exchange systems, selecting efficient pumps, implementing waste heat recovery, and optimizing cooling water usage, can contribute to energy reduction. Moreover, the comparison of product quality indicators before and after process improvement demonstrates that the improved process does not adversely affect the product quality. These findings provide valuable data support for the widespread adoption of supercritical CO2 extraction technology.