Concept and expression method of energy efficiency index (EEI) COPCO2 for carbon-capture system

Abstract

The present disclosure discloses the concept and expression method of an energy efficiency index (EEI) COP.sub.CO.sub.2 for a carbon-capture system. The COP.sub.CO.sub.2 refers to the ratio of the gain during a carbon-capture process to the cost practically, and to the ratio of the increase of CO.sub.2 chemical potential resulting from enrichment to the driving work input into the carbon-capture system physically. By introducing the concept of environmental effective state (G state), the present disclosure quantifies the “gain” during a carbon-capture process, and compares the “gain” with the “cost” to obtain the COP.sub.CO.sub.2 expression method of coefficient of performance (COP) during the carbon-capture process, which provides more accurate evaluation for the energy utilization level during a carbon-capture process and is conducive to improving the energy utilization level by carbon-capture technology, thereby improving the energy utilization rate.

Claims

1. Concept and expression method of an energy efficiency index (EEI) COP.sub.CO.sub.2 for a carbon-capture system, wherein, the EEI refers to the ratio of the gain of the carbon-capture system to the cost practically, and to the ratio of the increase of CO.sub.2 chemical potential resulting from enrichment to the driving work input into the carbon-capture system physically, indicating the energy conversion efficiency of the carbon-capture system.

2. The concept and expression method of an EEI COP.sub.CO.sub.2 for a carbon-capture system according to claim 1, wherein, the COP.sub.CO.sub.2 for a carbon-capture system has the following mathematical expression: ${\mathrm{COP}}_{{\mathrm{CO}}_2}=\frac{\mathrm{Gain}}{\mathrm{Cost}}=\frac{\Delta G}{\Delta W}=\frac{\left(\Delta G_1+\Delta h_1\right)+\left(W_{\min }+\Delta h_2\right)}{W_{\min }+\Delta h_2}.$

Description

BRIEF DESCRIPTION OF DRAWINGS

[0017] FIG. 1 is a schematic diagram illustrating the derivation of COP.sub.CO.sub.2 according to the present disclosure.

[0018] FIG. 2 is a framework diagram for the thermodynamic principle according to the present disclosure.

DETAILED DESCRIPTION

[0019] The solutions of the present disclosure are further described in detail below with reference to the accompanying drawings and specific embodiments. The specific embodiments described are only used to explain the present disclosure, but not to limit the present disclosure.

[0020] Under the framework of classic thermodynamics, the present disclosure expands the thermodynamic evaluation parameter COP to allow it to be applied to a novel energy-mass conversion system of carbon-capture technology.

[0021] The COP.sub.CO.sub.2 refers to the ratio of the gain of a carbon-capture system to the cost practically, and specifically to the ratio of the increase of CO.sub.2 chemical potential resulting from enrichment to the driving work input into the carbon-capture system physically. As shown in the formula (1), the numerator represents the Gibbs free energy change during a carbon-capture process, which is calculated from captured gas, product gas obtained from capture, and exhaust gas. The cost refers to the driving work input into a carbon-capture system, which is used to pry the increase of the gas chemical potential, thereby bringing Gibbs free energy change, as shown in FIG. 2.

[0022] The derivation and calculation method of COP.sub.CO.sub.2 is exemplified below. For example, under the following conditions: flue-gas Φ.sub.1,X (X represents gas types such as CO.sub.2 and N.sub.2) of a coal-fired power plant: 4 kmol CO.sub.2/s, 5 kmol H.sub.2O/s, 1 kmol O.sub.2/s, and 20 kmol N/s; T.sub.1: 45° C.; flue-gas pressure equal to standard state pressure: P.sub.1=P.sub.0; capture rate: 90%; product gas purity: 98%; T.sub.2: 65° C.; and unchanged pressure, the following calculation results are obtained according to the derivation formula:

[00002]$\begin{array}{cc}\Delta G_1=\mathrm{RT}\ln \left(\frac{13.3}{0.04}\right)=8.314*298.15*\ln \left(\frac{13.3}{0.04}\right)=14394J\text{/}\mathrm{mol}=327.14\mathrm{kJ}\text{/}\mathrm{kg}& \left(2\right)\\ W_{\min }=\mathrm{RT}\left[n_B^{{\mathrm{CO}}_2}\ln \left(y_b^{{\mathrm{CO}}_2}\right)+n_B^{B-{\mathrm{CO}}_2}\ln \left(y_B^{B-{\mathrm{CO}}_2}\right)+n_C^{{\mathrm{CO}}_2}\ln \left(y_C^{{\mathrm{CO}}_2}\right)+n_C^{C-{\mathrm{CO}}_2}\ln \left(y_C^{C-{\mathrm{CO}}_2}\right)-n_A^{{\mathrm{CO}}_2}\ln \left(y_A^{{\mathrm{CO}}_2}\right)-n_A^{A-{\mathrm{CO}}_2}\ln \left(y_A^{A-{\mathrm{CO}}_2}\right)\right]=6.88\mathrm{kJ}\text{/}\mathrm{mol}=156.36\mathrm{kJ}\text{/}\mathrm{kg}& \left(3\right)\end{array}$

[0023] The calculation formulas of ΔG and W.sub.min are mentioned in general textbooks and are not the focus of the present disclosure.

[0024] The physical property state parameters of related gases can be directly obtained from commercial physical property databases such as NEST, i.e., Δh.sub.1=20.35 kJ/kg and Δh.sub.2=13.2 kJ/kg.

[0025] By exemplifying the standardized test of COP.sub.CO.sub.2 and applying corresponding values to the formula for calculation, it can be seen that this carbon-capture system has the COP.sub.CO.sub.2=3.05.

[0026] Though the present disclosure is described above in conjunction with figures, the present disclosure is not limited to the above specific implementations, which are merely exemplary rather than restrictive. Other similar evaluation indexes for a carbon-capture system proposed by those of ordinary skill in the art in accordance with the teachings of the present disclosure shall fall within the protection scope of the present disclosure.