Simulation and optimization of the third and fourth distillation columns in the recovery section of polyvinyl alcohol production

doi:10.16085/j.issn.1000-6613.2023-0926

Abstract

Abstract:

Polyvinyl alcohol (PVA) is a polymer material with excellent performance. The main purpose of the recycling section is to recycle the alcoholysis waste liquor rich in methyl acetate (MeOAC), methanol (MeOH) and other chemical materials generated upstream. The main separation task of the third and fourth distillation columns of the recycling section (TQ-603 and TQ-604) is to simultaneously process the column kettle liquor from the second column (TQ-602), the column kettle liquor from the first column (TQ-601) and the column kettle liquor from the third column of the polymerization section TQ-302. Their main composition is a mixture of methanol and water. In this article, Aspen Plus chemical process simulation software was used to simulate and optimize the 100kt/a PVA recovery section in the third and fourth towers. The thermodynamic method was selected, and the parameter regression was conducted for the main MeOH-H₂O system. The optimal operating parameters of the single tower were obtained after optimization. On this basis, the double-effect distillation technology was implemented for the energy-saving renovation of the original process. A multi-tower heating process was developed through simulation and optimization to achieve deep energy saving.

Key words: polyving alcohol(PVA), recycling tower, double effect distillation, simulation, optimization

摘要：

聚乙烯醇（PVA）是一种性能优良的聚合物材料，其回收工段的主要目的是对上游产生的富含醋酸甲酯（MeOAC）、甲醇（MeOH）等化工原料的醇解废液进行回收处理。其中回收工段第三精馏塔和第四精馏塔（以下简称TQ-603和TQ-604）主要分离任务是同时处理来自回收二塔TQ-602的塔釜液、来自回收一塔TQ-601的塔釜液及聚合工段第三精馏塔TQ-302的塔釜液，其物料的主要组成均为甲醇与水的混合物。本文采用Aspen Plus化工流程模拟软件对10万吨/年 PVA回收工段中回收三塔和四塔进行模拟优化，针对所分离的主要体系MeOH-H₂O体系进行了热力学方法的选择及参数回归，最终选用NRTL模型进行了模拟与优化。优化后得到单塔的最佳操作参数。在此基础上将双效精馏技术用于原工艺流程的节能改造并开展模拟优化，构建多塔供热流程，实现深度节能。

关键词: 聚乙烯醇, 回收塔, 双效精馏, 模拟, 优化

CLC Number:

LI Mengyuan, GUO Fan, LI Qunsheng. Simulation and optimization of the third and fourth distillation columns in the recovery section of polyvinyl alcohol production[J]. Chemical Industry and Engineering Progress, 2023, 42(S1): 113-123.

李梦圆, 郭凡, 李群生. 聚乙烯醇生产中回收工段第三、第四精馏塔的模拟与优化[J]. 化工进展, 2023, 42(S1): 113-123.

Figures/Tables 35

T/K	x₁	y₁	T/K	x₁	y₁
327.45	1.000	1.000	339.77	0.332	0.706
328.20	0.948	0.983	341.06	0.289	0.674
330.31	0.819	0.935	342.54	0.246	0.638
331.93	0.707	0.888	346.11	0.160	0.538
333.76	0.620	0.849	352.16	0.075	0.366
335.03	0.536	0.816	355.88	0.039	0.235
336.93	0.449	0.769	358.06	0.020	0.139
338.16	0.393	0.744	361.51	0.000	0.000

x₁	x₂	$p 1 s$	$p 2 s$	ln(γ₁/γ₂)
1.0000	0.0000	65.7474	15.2172	—
0.9481	0.0519	67.8536	15.7761	-0.3046
0.8193	0.1807	74.0832	17.4433	-0.2897
0.7072	0.2928	79.1836	18.823	-0.2471
0.6200	0.3800	85.2935	20.4921	-0.1888
0.5364	0.4636	89.7602	21.7229	-0.0735
0.4487	0.5513	96.8044	23.6812	-0.0006
0.3928	0.6072	101.6047	25.0271	0.1004
0.3321	0.6679	108.1848	26.8862	0.1830
0.2887	0.7113	113.7083	28.4589	0.2414
0.2459	0.7541	120.3308	30.3583	0.3096
0.1598	0.8402	137.6269	35.3854	0.4523
0.0747	0.9253	171.597	45.5045	0.6356
0.0386	0.9614	195.7048	52.8565	0.7151
0.0199	0.9801	211.0762	57.6097	0.7697
0.0000	1.0000	237.4105	65.8599	—

x₁	x₂	$p 1 s$	$p 2 s$	ln(γ₁/γ₂)
1.0000	0.0000	65.7474	15.2172	—
0.9481	0.0519	67.8536	15.7761	-0.3046
0.8193	0.1807	74.0832	17.4433	-0.2897
0.7072	0.2928	79.1836	18.823	-0.2471
0.6200	0.3800	85.2935	20.4921	-0.1888
0.5364	0.4636	89.7602	21.7229	-0.0735
0.4487	0.5513	96.8044	23.6812	-0.0006
0.3928	0.6072	101.6047	25.0271	0.1004
0.3321	0.6679	108.1848	26.8862	0.1830
0.2887	0.7113	113.7083	28.4589	0.2414
0.2459	0.7541	120.3308	30.3583	0.3096
0.1598	0.8402	137.6269	35.3854	0.4523
0.0747	0.9253	171.597	45.5045	0.6356
0.0386	0.9614	195.7048	52.8565	0.7151
0.0199	0.9801	211.0762	57.6097	0.7697
0.0000	1.0000	237.4105	65.8599	—

x₁	y₁（NRTL）	y₁（Wilson）	y₁（UNIQUAC）
0.0000	0.0000	0.0000	0.0000
0.0476	0.2739	0.2743	0.2678
0.0952	0.4285	0.4284	0.4236
0.1429	0.5287	0.5282	0.5257
0.1905	0.5994	0.5988	0.5981
0.2381	0.6526	0.6519	0.6525
0.2857	0.6944	0.6939	0.6952
0.3333	0.7286	0.7283	0.7299
0.3810	0.7575	0.7573	0.7591
0.4286	0.7825	0.7825	0.7842
0.4762	0.8048	0.8050	0.8065
0.5238	0.8250	0.8254	0.8266
0.5714	0.8438	0.8443	0.8452
0.6190	0.8616	0.8621	0.8628
0.6667	0.8787	0.8793	0.8796
0.7143	0.8955	0.8960	0.8961
0.7619	0.9121	0.9125	0.9124
0.8095	0.9288	0.9291	0.9289
0.8571	0.9458	0.9459	0.9457
0.9048	0.9632	0.9632	0.9630
0.9524	0.9813	0.9811	0.9810
1.0000	1.0000	1.0000	1.0000

平均

偏差

最大

偏差

序号	P/bar	T/℃
1	0.0	65.1
2	0.5	75.5
3	1.0	83.6
4	1.5	90.7
5	2.0	95.2
6	2.5	100.2
7	3.0	104.0
8	3.5	108.1
9	4.0	112.9

R	Q_R/MW	Q_C/MW	Q=(-Q_C +Q_R)/MW
1.85	5.370	-3.896	9.266
1.9	5.436	-3.961	9.396
1.95	5.501	-4.026	9.527
2	5.567	-4.091	9.659
2.05	5.633	-4.157	9.790
2.1	5.700	-4.223	9.923
2.15	5.766	-4.289	10.055
2.2	5.833	-4.355	10.188
2.25	5.900	-4.422	10.321
2.3	5.967	-4.488	10.455
2.35	6.033	-4.555	10.588

组分	TQ-603进料（自TQ-602釜液）		采出		塔釜液
组分	W₂/kg∙h^-1	w	D₃/kg∙h^-1	w	W₃/kg∙h^-1	w
MeOH	4963.0	0.2605	4939.4	0.9952	23.6	0.0000
MeOAc	0.3	0.0001	0.3	0.0000	0.0	0.0017
H₂O	14084.3	0.7393	22.1	0.0045	14062.2	0.9982
Ald	0.0	0.0000	0.0	0.0000	0.0	0.0000
Ace	2.5	0.0001	1.3	0.0003	1.3	0.0001
NaAc	0.0	0.0000		0	0	0
总量	19050.1	1	4963.0	1	14087.1	1
T/℃	85.0		100.2		138.8
P/atm	1.05		2.5		2.6

组分	TQ-604进料（自TQ-601釜液）		TQ-604进料（自TQ-302釜液）		TQ-604采出		TQ-604釜液
组分	W₁/kg∙h^-1	w	W₃₀₂/kg∙h^-1	w	D₄/kg∙h^-1	w	W₄/kg∙h^-1	w
MeOH	43526.0	0.9713	12370.0	0.3800	56249.8	0.9955	6.4	0.0003
MeOAc	4.1	0.0001			3.9	0.0001
H₂O	1184.4	0.0264	20770.0	0.6200	231.9	0.0042	21722.5	0.9960
Ald	0.001	0.0001
Ace	14.4	0.0003			14.4	0.0002
NaAc	81.1	0.0018					81.1	0.0037
总量	44810.0	1	33500.0	1	56500.0	1	21860.0	1
T/℃	68.2		80.0		64.6		100.0
P/atm	1.12		3.96		1.02		1.00

序号	P/atm	T/℃
1	1	64.87
2	1.5	75.53
3	2	83.57
4	2.5	90.11
5	3	95.65
6	3.5	100.49
7	4	104.79
8	4.5	108.68
9	5	112.24
10	5.5	115.52
11	2.5	118.57

序号	精馏采出量D/kg·h^-1	w(MeOH)_塔底	T/℃
1	30000	0.9220	66.18
2	31000	0.9166	66.41
3	32000	0.9104	66.76
4	33000	0.9032	67.03
5	34000	0.8946	67.43
6	35000	0.8842	67.88
7	36000	0.8715	68.28
8	37000	0.8556	68.45
9	38000	0.8349	68.73
10	39000	0.8071	69.16
11	40000	0.7677	70.06
12	41000	0.7076	71.40
13	42000	0.6046	73.72
14	43000	0.3871	79.20
15	44000	0.0000	100.55

D/kg·h^-1	w(MeOH)_塔顶	D/kg·h^-1	w(MeOH)_塔顶
25300	0.9951	25400	0.9942
25310	0.9951	25410	0.9938
25320	0.9951	25420	0.9934
25330	0.9951	25430	0.9931
25340	0.9951	25440	0.9927
25350	0.9951	25450	0.9923
25360	0.9951	25460	0.9919
25370	0.9950	25470	0.9915
25380	0.9950	25480	0.9911
25390	0.9946	25490	0.9907

组分	TQ-603进料（自TQ-602釜液）		TQ-603进料（自TQ-302釜液）		TQ-603进料（自TQ-604塔釜）		采出		塔釜液
组分	W₂/kg∙h^-1	w	W₃₀₂/kg∙h^-1	w	W₄/kg∙h^-1	w	D₃/kg∙h^-1	w	W₃/kg∙h^-1	w
MeOH	4963.0	0.2605	12370.0	0.3800	7691.8	0.8741	25255.4	0.9951	0.1	0.0000
MeOAc	0.3	0.00001
H₂O	14084.3	0.7393	20770.0	0.6200	1026.8	0.1167	122.2	0.0048	40888.3	0.9980
Ald	0.0	0.0000
Ace	2.5	0.0001			0.3	0.0000	2.4	0.0001	0.5	0.0001
NaAc	0.0000	0.0000			81.1	0.0092			81.1	0.0019
总量	19050.1	1	33500.0	1	8800.0	1	25380	1	40970	1
T/℃	85.0		80.0		69.7		108.5		149.3
P/atm	1.05		3.96		1.08		4.5		4.6

组分	TQ-604进料（自TQ-601釜液）		TQ-604采出		TQ-604釜液
组分	W₁/kg∙h^-1	w	D₄/kg∙h^-1	w	W₄/kg∙h^-1	w
MeOH	43526.0	0.9713	35818.0	0.9950	7691.8	0.8741
MeOAc	4.1	0.0001	2.1	0.0001	0.0	0.0000
H₂O	1184.4	0.0264	166.0	0.0045	1026.8	0.1167
Ald	0.001	0.0001
Ace	14.4	0.0003	13.9	0.0004	0.3	0.0000
NaAc	81.1	0.0018			81.1	0.0092
总量	44810.0	1	36000.0	1	8800.0	1
T/℃	68.2		64.7		69.7
P/atm	1.12		1.00		1.08

操作参数	改造前 TQ-603	改造后 TQ-603	改造前 TQ-604	改造后 TQ-604
N（理论板）	25	28	21	21
R	2.05	2.50	0.70	0.40
N_F	20	7/12/20	8/18	7
D/kg∙h^-1	4963	25380	56500	36000
P/atm	2.5	4.5	1.02	1.02

操作参数	塔顶温度 /℃	塔底温度 /℃	冷凝器能耗/MW	再沸器能耗 /MW
改造前TQ-601	53.4	68.2	11.14	11.64
改造前TQ-602	55.4	88.0	7.56	9.22
改造前TQ-603	100.0	138.8	4.30	5.46
改造前TQ-604	64.6	100.0	29.41	29.84
改造后TQ-601	53.4	68.2	11.14	11.64
改造后TQ-602	55.4	88.0	7.56	9.22
改造后TQ-603	108.5	149.3	22.59	27.29
改造后TQ-604	64.7	69.7	15.45	15.34

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