Energy saving optimization of cyclohexane three-effect distillation in cyclohexanone production

doi:10.16085/j.issn.1000-6613.2022-1252

Abstract

Abstract:

According to the process characteristics of a 60kt/a cyclohexanone unit, the whole process calculation model of three-effect distillation of cyclohexane oxidation product separation system was established by using Aspen plus simulation software and NRTL physical property method, and the data were optimized. Taking the cyclohexanone and cyclohexanol content of overhead distillates of 1st alkane tower, 2nd alkane tower, 3rd alkane tower and the amount of hot/cold cyclohexane sent out as constraints, the variables such as reflux of each distillation tower, reflux ratio of 1st alkane tower and 2nd alkane tower, reflux of alkane 3rd tower and steam consumption were optimized, and the optimized process parameters were applied to the energy-saving optimization of actual production units. The results showed that the steam consumption can be reduced from 5.53kg/s to 3.9kg/s theoretically under the condition of 8.02kg/s total reflux of 1st alkane tower and 2nd alkane tower, 0.67 reflux ratio of 1st alkane tower and 2nd alkane tower, and 17.93kg/s reflux of 3rd alkane tower. The actual optimization results showed that 0.28kg/s steam could be reduced and the annual operation cost could be reduced by about 1.44 million yuan.

Key words: cyclohexanone, cyclohexane, three-effect distillation, energy saving optimization

摘要：

针对某6万吨/年环己酮装置工艺特点，采用Aspen plus模拟软件及NRTL物性方法，建立了环己烷氧化产物三效精馏全流程计算模型并进行了数据优化。以烷一塔、烷二塔、烷三塔塔顶馏出物醇酮含量、外送热冷烷量为约束条件，对各精馏塔回流量、烷一塔和烷二塔回流量比值、烷三塔回流量、蒸汽消耗量等变量进行优化，将优化的工艺参数用于实际生产装置的节能优化。结果表明：在烷一塔、烷二塔回流量总和8.02kg/s、烷一塔及烷二塔回流量比值0.67、烷三塔回流量17.93kg/s的条件下，理论上蒸气消耗可从5.53kg/s降至3.9kg/s，实际优化结果发现可节约蒸气0.28kg/s，节约年运行成本约144万元。

关键词: 环己酮, 环己烷, 三效精馏, 节能优化

CLC Number:

TQ028

WANG Dong, YU Pinhua, CHEN Bin, XIAO Ang, CHEN Feng, JIANG Yangyang. Energy saving optimization of cyclohexane three-effect distillation in cyclohexanone production[J]. Chemical Industry and Engineering Progress, 2023, 42(5): 2245-2251.

汪东, 于品华, 陈斌, 肖昂, 陈锋, 江洋洋. 环己酮生产中的环己烷三效精馏节能优化[J]. 化工进展, 2023, 42(5): 2245-2251.

Figures/Tables 13

References 12

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物料	质量分数/%
环己烷	93.74
环己酮	2.62
环己醇	2.56
水	0.78
戊醛	0.11
丁基环己烷	0.02
丁醇	0.07
戊基环己烷	0.03
戊醇	0.06

物料	质量分数/%
环己烷	93.74
环己酮	2.62
环己醇	2.56
水	0.78
戊醛	0.11
丁基环己烷	0.02
丁醇	0.07
戊基环己烷	0.03
戊醇	0.06

操作条件	烷一塔	烷二塔	烷三塔	烷四塔
塔顶压力（绝对压力） /kPa	501.325	289	113.325	113.325
塔顶温度/℃	142.91	117.50	85.1	—
塔釜温度/℃	147.16	122.93	88.63	143.31
现有蒸汽消耗/kg·s^-1	4.25	—	—	1.28
V0252操作条件	301.325kPa（绝对压力），气相分率0.005
V0253操作条件	130kPa（绝对压力），气相分率0.005

操作条件	烷一塔	烷二塔	烷三塔	烷四塔
塔顶压力（绝对压力） /kPa	501.325	289	113.325	113.325
塔顶温度/℃	142.91	117.50	85.1	—
塔釜温度/℃	147.16	122.93	88.63	143.31
现有蒸汽消耗/kg·s^-1	4.25	—	—	1.28
V0252操作条件	301.325kPa（绝对压力），气相分率0.005
V0253操作条件	130kPa（绝对压力），气相分率0.005

工艺参数	烷一塔	烷二塔	烷三塔	烷四塔
塔顶压力（绝对压力）/kPa	501.325	289.00	113.325	113.325
塔顶温度/℃	144.58	120.21	83.23	88.05
塔釜温度/℃	147.21	122.99	88.05	100.80
塔顶出烷量/kg·s^-1	8.81	20.58	46.25	9.45
塔顶环己酮质量分数/%	0.0002	0.0014	0.000001
塔顶环己醇质量分数/ %	0.0011	0.0059	0.099
塔底出烷量/kg·s^-1	44.64	28.98	13.87	4.43
回流量/kg·s^-1	3.28	4.92	17.93	—
装置调优前回流量/kg·s^-1	4.45	5.54	25.43	—
1.0MPa（绝对压力）蒸汽消耗/kg·s^-1	2.30			1.6