Modeling analysis for product distribution control and optimization of heavy oil FCCU

doi:10.11949/0438-1157.20211245

Abstract

Abstract:

The higher coke yield in heavy oil fluid catalytic cracking unit(FCCU) will increase the load of the regenerator and reduce the catalyst-to-oil ratio(COR) and light oil yield. In this regard, an external heat extractor is added to the catalytic cracking unit. By adopting the method of combining external heat extraction and external oil slurry rejection, the yield of light oil from the catalytic cracking of heavy oil can be improved. The function of the external cooler is to remove the excess heat of the regenerator part quickly and effectively, so as to achieve the purpose of cooling the regeneration catalyst. The function of the slurry drawoff is to reduce the coke yield and reduce the heat generation of scorching. The reduction of heat can effectively increase the COR and increase the light oil yield. The value of carbon residue in crude oil has a direct impact on product distribution. The higher the residual carbon value of the feedstock, the more coke is produced in the reactor of FCC unit. The carbon mass fraction on the spent catalyst will also increase, and after reaching the regenerator, it will release a large amount of heat. The increase in heat will not only affect the life of the regenerator, but also reduce the COR in FCCU, thereby reduce the light oil yield. In this paper, the control vector parameterization method is used to control and optimize the CO combustion-supporting agent, main air flow rate, heat of external cooler and slurry drawoff on various levels. The results show that the optimization effect of CO combustion-supporting agent and main air flow rate is limited for heavy oil FCCU, but the mutual promotion of heat of external cooler and slurry drawoff can effectively improve the COR and the light oil yield.

Key words: process system engineering, FCCU, external cooler, slurry drawoff, light oil yield, regulation and optimization

摘要：

重油催化裂化焦炭产率较高，会加重再生器负荷，降低剂油比和轻质油收率。对此，在催化裂化装置基础上添加外取热器。通过采用外取热和外甩油浆相结合的方法，实现重油催化裂化轻质油收率的提高。外取热器的作用是为了快速有效将再生器部分过多的热量取走，达到再生催化剂降温的目的。外甩油浆的作用是为了降低焦炭产率，减少烧焦产生热量。热量的降低可以有效提高剂油比，增加轻质油收率。原料残炭值的大小对产品分布有直接影响。原料残炭值越大，催化裂化装置的反应器部分产生焦炭越多，待生催化剂上含碳量也会升高，到达再生器烧焦以后释放大量的热量，热量增加不仅会影响再生器的寿命，也会使催化裂化装置中的剂油比降低，从而降低轻质油收率。通过控制向量参数化方法对CO助燃剂、主风、外取热和外甩油浆进行了不同层次的调控与优化，结果发现，对于重油催化裂化，CO助燃剂、主风的优化影响效果有限，而外取热和外甩油浆相互促进可以有效提高剂油比和轻质油收率。

关键词: 过程系统工程, 催化裂化装置, 外取热装置, 外甩油浆, 轻质油收率, 调控与优化

CLC Number:

TQ 021.8

Jianfei ZHANG, Jiajiang LIN, Xionglin LUO, Feng XU. Modeling analysis for product distribution control and optimization of heavy oil FCCU[J]. CIESC Journal, 2022, 73(3): 1232-1245.

张建飞, 林嘉奖, 罗雄麟, 许锋. 重油催化裂化装置产品分布调控与优化模拟分析[J]. 化工学报, 2022, 73(3): 1232-1245.

Figures/Tables 18

References 34

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变量	数值
F_fresh	85 t/h
F_hco	12.75 t/h
F_slurry	7.25 t/h
G_Crg2	504.2 kg/s
COR	4.81
V_air,rg1	49340 m³/h
V_air,rg2	6658 m³/h
M_pro	4 kg
x_pro	0.004%(mass)
W	24/5/5 kg
T_riser	493.5℃
T_rg1	695.4℃
T_rg2	703.6℃
C_SC	0.95 kg/kg
C_rg2	0.04 kg/kg

变量	数值
F_fresh	85 t/h
F_hco	12.75 t/h
F_slurry	7.25 t/h
G_Crg2	504.2 kg/s
COR	4.81
V_air,rg1	49340 m³/h
V_air,rg2	6658 m³/h
M_pro	4 kg
x_pro	0.004%(mass)
W	24/5/5 kg
T_riser	493.5℃
T_rg1	695.4℃
T_rg2	703.6℃
C_SC	0.95 kg/kg
C_rg2	0.04 kg/kg

序号	外甩油浆量/(t/h)	取热比例/%	柴油/%	汽油/%	焦炭/%	气体/%	烧焦罐底部温度/℃	密相床温度/℃
1	0	0	30.92	43.65	10.37	15.06	709.4	737.4
2	1.81	0	30.10	42.04	9.82	14.55	700.9	728.6
3	3.63	0	30.05	40.41	8.65	13.72	689.8	717.2
4	5.44	0	29.99	39.84	7.85	11.71	676.8	704.6
5	7.25	0	30.01	39.51	6.15	10.17	666.2	691.9
6	0	10	30.97	44.64	10.27	14.12	707.5	730.4
7	1.81	10	30.04	43.24	9.83	13.36	699.5	726.2
8	3.63	10	30.06	42.09	9.21	11.56	688.3	721.7
9	5.44	10	30.30	40.09	8.61	10.39	675.6	700.6
10	7.25	10	30.11	39.84	7.04	9.86	664.7	688.6
11	0	20	31.51	45.20	10.03	13.25	705.5	723.5
12	1.81	20	31.19	43.12	9.63	12.53	698.1	715.8
13	3.63	20	30.83	41.39	8.73	11.97	687.7	714.1
14	5.44	20	30.43	40.63	7.81	10.52	674.2	699.3
15	7.25	20	30.17	40.21	6.01	10.45	662.1	686.2
16	0	30	31.68	46.18	10.96	12.19	703.5	717.4
17	1.81	30	31.22	44.15	10.73	10.16	696.8	715.5
18	3.63	30	31.08	42.09	10.45	9.30	685.0	713.5
19	5.44	30	30.70	41.14	8.44	9.12	672.6	696.7
20	7.25	30	30.42	40.41	6.30	8.72	661.3	684.1

序号	外甩油浆量/(t/h)	取热比例/%	柴油/%	汽油/%	焦炭/%	气体/%	烧焦罐底部温度/℃	密相床温度/℃
1	0	0	30.92	43.65	10.37	15.06	709.4	737.4
2	1.81	0	30.10	42.04	9.82	14.55	700.9	728.6
3	3.63	0	30.05	40.41	8.65	13.72	689.8	717.2
4	5.44	0	29.99	39.84	7.85	11.71	676.8	704.6
5	7.25	0	30.01	39.51	6.15	10.17	666.2	691.9
6	0	10	30.97	44.64	10.27	14.12	707.5	730.4
7	1.81	10	30.04	43.24	9.83	13.36	699.5	726.2
8	3.63	10	30.06	42.09	9.21	11.56	688.3	721.7
9	5.44	10	30.30	40.09	8.61	10.39	675.6	700.6
10	7.25	10	30.11	39.84	7.04	9.86	664.7	688.6
11	0	20	31.51	45.20	10.03	13.25	705.5	723.5
12	1.81	20	31.19	43.12	9.63	12.53	698.1	715.8
13	3.63	20	30.83	41.39	8.73	11.97	687.7	714.1
14	5.44	20	30.43	40.63	7.81	10.52	674.2	699.3
15	7.25	20	30.17	40.21	6.01	10.45	662.1	686.2
16	0	30	31.68	46.18	10.96	12.19	703.5	717.4
17	1.81	30	31.22	44.15	10.73	10.16	696.8	715.5
18	3.63	30	31.08	42.09	10.45	9.30	685.0	713.5
19	5.44	30	30.70	41.14	8.44	9.12	672.6	696.7
20	7.25	30	30.42	40.41	6.30	8.72	661.3	684.1

（a）优化前后参数对比
参数	优化前	优化后
M_pro/kg	5	5.17
V_air,rg1/(m³/h)	49340	49011
COR	4.12	4.23
η₀/%	20	21.55
y/(kg/kg)	72.22	72.43
y_n/(kg/kg)	41.39	41.52
y_d/(kg/kg)	30.83	30.91