低共熔溶剂捕集烟气CO2模拟研究

doi:10.11949/0438-1157.20240441

摘要/Abstract

摘要：

开发新型吸收剂是碳捕集的重要研究方向。低共熔溶剂（DES）是由两种或多种化合物通过氢键结合的混合物，被视为一种具有潜力的绿色溶剂。以氯化胆碱/尿素（ChCl/urea）（摩尔比1∶2）、氯化胆碱/甘油（ChCl/Gly）（1∶2）和氯化胆碱/乙二醇（ChCl/EG）（1∶2）作为吸收剂，基于Aspen Plus建立DES的热力学模型，回归汽液相平衡等物性相关参数，使用COAMO-SAC模型预测N₂、O₂在DES中的溶解度并构建CO₂捕集工艺流程，研究吸收压力、吸收温度、塔板数以及CO₂浓度对捕集系统的影响。结果表明，CO₂捕集率为90%、CO₂纯度为90%的前提下，ChCl/urea（1∶2）、ChCl/Gly（1∶2）、ChCl/EG（1∶2）的再生能耗比胺溶液捕集系统分别降低35.17%、35.00%、15.28%。综合考虑3种DES的再生能耗、吸收剂需求量和吸收剂损失量，ChCl/Gly（1∶2）最具应用前景。相关研究可为DES工业捕集CO₂的可行性提供一定参考。

关键词: 二氧化碳捕集, 低共熔溶剂, 吸收剂, 相平衡, 再生能耗, 模拟

Abstract:

The development of new absorbents is an important research direction for CO₂ capture. Deep eutectic solvent (DES) is a mixture of two or more compounds formed by hydrogen bonding and is regarded as a potential green solvent. The DESs were selected as the CO₂ absorbents, namely choline chloride/urea (ChCl/urea)(molar ratio 1∶2), choline chloride/glycerol (ChCl/Gly)(1∶2), and choline chloride/ethylene glycol (ChCl/EG)(1∶2). The thermodynamic models of DES were established based on Aspen Plus by regressing the vapor-liquid equilibrium parameters and the other thermophysical parameters. The COAMO-SAC was used to predict the solubility of N₂ and O₂ in DES, and a CO₂ capture process was built. The effects of absorption pressure, absorption temperature, the number of stages, and CO₂ concentration were studied. The results show that the regeneration energy consumption of ChCl/urea(1∶2), ChCl/Gly(1∶2) and ChCl/EG(1∶2) process can be reduced by 35.17%, 35.00% and 15.28% compared with the traditional amine process at 90% of CO₂ removal efficiency and 90% of CO₂ purity. Considering the regeneration energy consumption, solvent demand and solvent loss of DES, ChCl/Gly(1∶2) has the most promising application prospect. The study can provide reference for the feasibility of CO₂ capture industry by DES.

Key words: CO₂ capture, deep eutectic solvent, absorbent, phase equilibria, regeneration energy consumption, simulation

中图分类号:

TQ 53

孙琼, 杨富鑫, 谭厚章, 王晓坡. 低共熔溶剂捕集烟气CO₂模拟研究[J]. 化工学报, 2024, 75(10): 3705-3717.

Qiong SUN, Fuxin YANG, Houzhang TAN, Xiaopo WANG. Simulation study of CO₂ capture from flue gas by deep eutectic solvent[J]. CIESC Journal, 2024, 75(10): 3705-3717.

图/表 33

图1 CO2捕集工艺流程

Fig.1 Process of CO2 capture

表1 DES临界参数

Table 1 Critical properties for DES

DES	M/(g·mol^-1)	T_b/K	T_c/K	p_c/MPa	V_c/(cm³·mol^-1)	ω
ChCl/urea(1∶2)	86.58	445.6	644.4	4.935	254.37	0.661
ChCl/Gly(1∶2)	107.93	515.4	680.67	3.306	315.17	1.251
ChCl/EG(1∶2)	87.92	439.0	602.0	4.039	259.67	0.952

表2 DES物性参数

Table 2 Thermophysical parameters for DES

物性	方程	DES	参数			文献
物性	方程	DES	C₁	C₂	C₃	文献
液体摩尔体积	$V_{l} = C_{1} + C_{2} T + C_{3} T^{2}$	ChCl/urea(1∶2)	0.06358	2.427×10^-5	1.624×10^-8	[27]
		ChCl/Gly(1∶2)	0.07949	3.225×10^-5	1.667×10^-8	本文本文
		ChCl/EG(1∶2)	0.06747	3.545×10^-5	8.419×10^-9	本文本文
黏度	$l n η = C_{1} + C_{2} / T + C_{3} l n T$	ChCl/urea(1∶2)	-443.700	2.667×10⁴	62.14	[27]
		ChCl/Gly(1∶2)	-275.024	1.719×10⁴	37.96	本文本文
		ChCl/EG(1∶2)	-156.309	9.916×10³	21.03	本文本文
摩尔热容	$C_{p} = C_{1} + C_{2} T + C_{3} T^{2}$	ChCl/urea(1∶2)	117.300	0.2085	1.679×10^-12	[27]
		ChCl/Gly(1∶2)	327.583	-0.2293	2.914×10^-4	本文本文
		ChCl/EG(1∶2)	131.329	0.4274	9.997×10^-4	本文本文
表面张力	$σ = C_{1} {(1 - T / T_{c})}^{C_{2} + C_{3} T / T_{c}}$	ChCl/urea(1∶2)	0.09244	0.6043	0	[27]
		ChCl/Gly(1∶2)	0.06609	0.3988	-3.670×10^-5	本文本文
		ChCl/EG(1∶2)	0.06780	0.3635	-0.1384	本文本文

表2 DES物性参数

Table 2 Thermophysical parameters for DES

物性	方程	DES	参数			文献
物性	方程	DES	C₁	C₂	C₃	文献
液体摩尔体积	$V_{l} = C_{1} + C_{2} T + C_{3} T^{2}$	ChCl/urea(1∶2)	0.06358	2.427×10^-5	1.624×10^-8	[27]
		ChCl/Gly(1∶2)	0.07949	3.225×10^-5	1.667×10^-8	本文本文
		ChCl/EG(1∶2)	0.06747	3.545×10^-5	8.419×10^-9	本文本文
黏度	$l n η = C_{1} + C_{2} / T + C_{3} l n T$	ChCl/urea(1∶2)	-443.700	2.667×10⁴	62.14	[27]
		ChCl/Gly(1∶2)	-275.024	1.719×10⁴	37.96	本文本文
		ChCl/EG(1∶2)	-156.309	9.916×10³	21.03	本文本文
摩尔热容	$C_{p} = C_{1} + C_{2} T + C_{3} T^{2}$	ChCl/urea(1∶2)	117.300	0.2085	1.679×10^-12	[27]
		ChCl/Gly(1∶2)	327.583	-0.2293	2.914×10^-4	本文本文
		ChCl/EG(1∶2)	131.329	0.4274	9.997×10^-4	本文本文
表面张力	$σ = C_{1} {(1 - T / T_{c})}^{C_{2} + C_{3} T / T_{c}}$	ChCl/urea(1∶2)	0.09244	0.6043	0	[27]
		ChCl/Gly(1∶2)	0.06609	0.3988	-3.670×10^-5	本文本文
		ChCl/EG(1∶2)	0.06780	0.3635	-0.1384	本文本文

表3 CO2-DES的NRTL二元交互参数

Table 3 NRTL binary interaction parameters for CO2-DES

组分i	组分j	a_ij	a_ji	b_ij	b_ji	c_ij =c_ji	AARD/%
CO₂	ChCl/urea(1∶2)	20.2588	5.7459	-2828.6769	-1737.4156	0.2	0.75
CO₂	ChCl/Gly(1∶2)	23.8246	8.5382	-3151.5550	-2493.2859	0.2	0.78
CO₂	ChCl/EG(1∶2)	0.1016	5.8073	1064.8932	-1775.0022	0.2	0.59

表4 CO2在DES中的亨利系数

Table 4 Henry coefficient of CO2 in DES

组分i	组分j	A_ij	B_ij	C_ij	D_ij	AARD/%
CO₂	ChCl/urea(1∶2)	6462.3174	-179408.8200	-1120.7023	1.7679	2.05
CO₂	ChCl/Gly(1∶2)	-591.7956	15117.7011	103.1011	-0.1477	2.31
CO₂	ChCl/EG(1∶2)	3305.5768	-92825.7082	-572.2799	0.9036	1.46

图2 CO2在DES中的溶解度的实验值与计算值对比

Fig.2 Comparison of experimental and calculated results for CO2-DES

图3 DES与N2和O2的σ-profile

Fig.3 σ-Profile of DES, N2 and O2

图4 CO2在ChCl/urea(1∶2)中的溶解度的实验值与预测值对比

Fig.4 Comparison of the experimental and predicted solubility of CO2 in ChCl/urea(1∶2)

表5 N2-DES和O2-DES的NRTL二元交互参数

Table 5 NRTL binary interaction parameters for N2-DES and O2-DES

组分i	组分j	a_ij	a_ji	b_ij	b_ji	c_ij =c_ji
N₂	ChCl/urea(1∶2)	-4.6072	5.6872	934.4396	-566.3254	0.2
O₂	ChCl/urea(1∶2)	-3.5878	1.9443	1138.4073	112.6562	0.2
N₂	ChCl/Gly(1∶2)	-4.3276	4.9755	892.4376	-481.3364	0.2
O₂	ChCl/Gly(1∶2)	-2.8417	0.6281	1073.8115	303.3775	0.2
N₂	ChCl/EG(1∶2)	-4.8028	5.2850	1013.9117	-695.0201	0.2
O₂	ChCl/EG(1∶2)	-3.1517	0.1611	1197.0493	278.4344	0.2

表6 CO2工艺流程在Aspen Plus中的设备参数

Table 6 Equipment parameters of CO2 capture process in Aspen Plus

设备名称	设备参数	参数值
多级压缩机	级数	5
	级间冷却器冷却温度/℃	20
吸收塔	塔板数	30
	冷凝器	None
	再沸器	None
闪蒸塔2	热负荷/MW	0
	操作压力/MPa	0.01
冷却器	冷却温度/℃	20

图5 吸收压力对富液负荷的影响

Fig.5 Influence of absorption pressure on rich-phase loading

图6 吸收压力对贫液负荷的影响

Fig.6 Influence of absorption pressure on lean-phase loading

图7 吸收压力对贫液流量的影响

Fig.7 Influence of absorption pressure on lean-phase flow rate

图8 吸收压力对DES损失量的影响

Fig.8 Influence of absorption pressure on loss of DES

图9 吸收压力对闪蒸塔1压力的影响

Fig.9 Influence of absorption pressure on pressure of flash tower 1

图10 吸收压力对压缩机功耗的影响

Fig.10 Influence of absorption pressure on compressor power consumption

图11 吸收压力对泵功耗的影响

Fig.11 Influence of absorption pressure on pump power consumption

图12 吸收压力对再生能耗的影响

Fig.12 Influence of absorption pressure on regeneration energy consumption

图13 吸收温度对富液负荷的影响

Fig.13 Influence of absorption temperature on rich-phase loading

图14 吸收温度对贫液负荷的影响

Fig.14 Influence of absorption temperature on lean-phase loading

图15 吸收温度对贫液流量的影响

Fig.15 Influence of absorption temperature on lean-phase flow rate

图16 吸收温度对DES损失量的影响

Fig.16 Influence of absorption temperature on the loss of DES

图17 吸收温度对闪蒸塔1压力的影响

Fig.17 Influence of absorption temperature on pressure of flash tower 1

图18 吸收温度对压缩机功耗的影响

Fig.18 Influence of absorption temperature on compressor power consumption

图19 吸收温度对泵功耗的影响

Fig.19 Influence of absorption temperature on pump power consumption

图20 吸收温度对再生能耗的影响

Fig.20 Influence of absorption temperature on regeneration energy consumption

图21 吸收塔塔板数对贫液流量的影响

Fig.21 Influence of number of stages on lean-phase flow rate

图22 吸收塔塔板数对闪蒸塔1压力的影响

Fig.22 Influence of number of stages on pressure of flash tower 1

图23 CO2浓度对闪蒸塔1压力的影响

Fig.23 Influence of CO2 concentration on pressure of flash tower 1

图24 CO2浓度对再生能耗的影响

Fig.24 Influence of CO2 concentration on regeneration energy consumption

表7 DES的能耗情况

Table 7 Energy consumption of DES

DES	多级压缩机功耗/MW	压缩机功耗/MW	泵功耗/MW	再生能耗/(GJ·t^-1)
ChCl/urea(1∶2)	270.528	3.777	26.358	2.726
ChCl/Gly(1∶2)	270.528	4.367	26.559	2.733
ChCl/EG(1∶2)	270.528	69.938	52.415	3.562

图25 ChCl/urea(1∶2)在传统醇胺捕集CO2工艺流程的模拟

Fig.25 Simulated traditional amine CO2 capture process using ChCl/urea (1∶2)

表8 ChCl/urea（1∶2）在传统醇胺捕集CO2工艺流程模拟的能耗

Table 8 Energy consumption simulation of ChCl/urea （1∶2） in traditional amine CO2 capture process

DES	多级压缩机功耗/MW	再沸器热负荷/MW	泵功耗/MW	再生能耗/ (GJ·t^-1)
ChCl/urea(1∶2)	270.528	156.386	17.682	4.03

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低共熔溶剂捕集烟气CO₂模拟研究

Simulation study of CO₂ capture from flue gas by deep eutectic solvent

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