Heat Integration Scheme for Benzene Production and C8 Units Based on Actual Cold and Hot Composite Curves
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摘要: 不同装置间的热联合是炼厂提高能量利用率的有效措施。为获得热联合的实际节能潜力和提高改造方案的抗波动能力,提出了基于实际冷、热复合曲线的热联合改造方法。基于某石化企业中制苯装置和碳八装置的工业数据,使用Aspen HYSYS 建立了换热网络模型,并利用Aspen Energy Analyzer进行换热网络分析,提出了制苯装置的换热网络改造方案。通过所提出的改造方法,给出了装置间热联合的节能潜力,并综合改造实施的限制和复杂程度,提出了两个热联合方案,并对方案结果进行了对比和讨论。结果表明,节能较多的方案需要更多的投资成本,投资回收期略长,但从长远来看经济效益更好。Abstract: Heat integration across different units is an effective measure to improve energy utilization in chemical plants. In order to obtain the actual energy-saving potential across the units and improve the fluctuation resistance of the retrofitting schemes, a retrofitting method based on the actual cold and heat composite curves is put forward. Based on the industrial data of benzene production and C8 units in a petrochemical enterprise, the heat exchanger networks of the two units are simulated in Aspen HYSYS and the pinch analysis is done with Aspen Energy Analyzer. Considering the unreasonable heat transfer of benzene production unit and the safety constraints, retrofitting schemes for the heat exchanger network of benzene production unit are proposed to reduce the steam consumption. Since the energy-saving potential of the C8 unit is limited and the unreasonable heat transfer is distributed in different heat exchangers, it is not cost-effective to retrofit the heat exchanger network of the C8 unit. The energy-saving potential of heat integration between the two units is analyzed by constructing the actual cold and hot composite curves. The advantage of using the actual cold and hot composite curves to guide the heat integration across the two units is that it uses the actual residual energy, which is more practical than the theoretical situation such as the grand composite curve. Besides, limitations and complexity of implementation are also considered to make retrofitting schemes. As a result, two heat integration retrofit schemes across the two units are proposed, compared, and discussed. The results show that the scheme with more energy saving needs more investment costs and has a slightly longer payback period, but has more economic benefits in the long term.
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Key words:
- actual composite curve /
- heat integration /
- pinch analysis /
- energy saving
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表 1 制苯装置换热器数据(B,H和C分别表示苯,热流和冷流)
Table 1. Data of heat exchangers in the benzene production unit (B, H, and C represent the benzene production unit, hot streams and cold streams, respectively)
Heat exchangers Hot streams Cold streams Load /kW Description tin/°C tout /°C Description tin /°C tout /°C E-102A/B Medium pressure steam — — BC1 124.7 127.0 4145 E-103 BH1 57.1 41.0 Cooling water — — 3127 E-1103 BH2 63.4 48.4 Cooling water — — 6053 E-1104A/B Medium pressure steam — — BC2 138.3 143.6 5462 E-1104N BH3 180.0 165.0 BC2 138.3 143.6 1271 E-1111RN BH4 138.3 75.0 BC3 30.0 45.79 309 E-202 BH5 84.4 40.0 Cooling water — — 40160 E-303N BH6 131.1 98.1 BC4 80.0 99.6 823 E-304AN BH7 285.6 125.6 BC4 99.6 243.6 7124 E-402 BH7 129.7 39.2 Cooling water — — 2553 E-408 BH6 155.0 131.1 BC5 103.3 128.1 641 EA-401 BH8 96.4 39.0 Cooling water — — 116 E-406 Medium pressure steam — — BC6 155.1 158.0 819 EA-502 BH9 112.0 99.7 Air — — 5356 E-503 BH9 99.7 48.2 Cooling water — — 1326 E-109R Medium pressure steam — — BC6 155.7 158.7 3823 E-504 BH10 158.7 40.0 Cooling water — — 1063 E-3606 BH3 165.0 152.8 BC7 45.0 90.4 1010 E-3608 BH3 152.8 118.7 Cooling water — — 2733 E-3601 BH11 81.4 41.3 Cooling water — — 2800 E-3602A/B High pressure steam — — BC8 154.7 176.5 6370 E-3603 BH12 45.4 40.4 Cooling water — — 4694 E-3604 High pressure steam — — BC9 204.2 205.0 2940 E-3605 BH3 208.0 180.0 BC10 144.3 167.7 2446 E-3609 BH3 160.1 55.0 Cooling water — — 189 E-3610 High pressure steam — — BC9 157.3 160.1 129 表 2 碳八装置的换热器数据(O,H,和C分别表示碳八,热流和冷流)
Table 2. Data of heat exchangers in the C8 unit (O, H and C represent the C8 unit, hot streams, and cold streams, respectively).
Heat exchangers Hot streams Cold streams Load /kW Description tin /°C tout /°C Description tin /°C tout /°C E-2111 OH1 120.5 40.0 Cooling water — — 309 E-2112 Low pressure steam — — OC1 120.5 124.5 4583 E-2113 OH2 69.1 44.4 Cooling water — — 323 E-2201 OH3 33.0 29.0 Cooling water — — 38 E-2202 OH4 33.0 20.0 Cooling water — — 1 E-2301 OH5 100.0 95.0 OC2 40.0 73.5 99 E-2302 OH6 63.2 42.5 Cooling water — — 122 E-2304 OH6 42.5 6.2 Cooling water — — 2 E-2305 Low pressure steam — — OC3 90.0 130.0 3437 E-2313 Low pressure steam — — OC4 136.5 140.0 144 E-2308 OH5 95.0 79.8 Cooling water — — 293 E-2310 OH7 50.3 40.0 Cooling water — — 32 E-2312 Low pressure steam — — OC5 101 120 1604 E-2307A OH5 110.0 100.0 Cooling water — — 198 E-2400 OH8 69.5 12.7 Cooling water — — 1 E-2407 Ultra-low pressure steam — — OC6 78.0 82.0 216 E-2411 OH9 81.5 52.0 Cooling water — — 48 E-2401 OH10 71.0 28.1 Cooling water — — 510 E-2403 OH11 32.0 30.7 Cooling water — — 2 E-2404 Ultra-low pressure steam — — OC7 71.5 72.0 299 E-2405 OH11 67.0 32.0 Cooling water — — 40 表 3 制苯装置现行换热网络的不合理换热
Table 3. Unreasonable heat transfer in the current heat exchanger network of benzene production unit
Heat exchangers Load /kW Unreasonable type E-3608 1058 Cooler above the pinch point E-3606 1010 Heat exchanger across the pinch point E-304AN 433 Heat exchanger across the pinch point E-408 325 Heat exchanger across the pinch point E-504 187 Cooler above the pinch point E-3609 143 Cooler above the pinch point Total 3156 表 4 制苯装置方案的投资成本和经济效益
Table 4. Investment costs and economic benefit of the scheme in the benzene production unit
Heat exchangers Investment cost
/104 CNYEconomic benefits
/104 CNY/aE-100 107.6 833.8 E-101 60.2 表 5 碳八装置现行换热网络的不合理换热
Table 5. Unreasonable heat transfer in the current heat exchanger network of C8 unit
Heat exchangers Load/kW Unreasonable type E-2307A 198 Cooler above the pinch point E-2308 159 Cooler above the pinch point E-2111 135 Cooler above the pinch point E-2301 94 Heat exchanger across the pinch point Total 586 表 6 热联合方案的投资成本和经济效益
Table 6. Investment costs and economic benefits of the schemes of heat integration across units
Schemes Heat exchangers Investment
cost/104 CNYEconomic
benefits /104 CNY/a1 HCE-100 78.6 399.8 2 HCE-100 81.3 523.6 HCE-101 51.9 -
[1] 王彧斐, 王伟, 冯霄. 考虑中间介质换热的厂际热联合[J]. 华东理工大学学报(自然科学版), 2014, 40(2): 202-205. doi: 10.3969/j.issn.1006-3080.2014.02.012 [2] 曾惠平. 炼油事业部装置热联合节能效果明显[J]. 高桥石化, 2007, 022(2): 38. [3] 潘罗其. 重油催化裂化与苯乙烯装置的热联合节能[J]. 炼油技术与工程, 2013, 43(3): 24-27. [4] 常安, 翟晓靖, 张睿, 等. 炼油装置间热联合可行性分析及优化建议[J]. 石油石化节能, 2016, 6(11): 5-7. doi: 10.3969/j.issn.2095-1493.2016.11.002 [5] 王珊珊, 潘登, 孙绍鹏. 催化分馏塔顶循系统低温热源的综合利用[J]. 中外能源, 2021, 26(5): 88-92. [6] BONHIVERS J C, MOUSSAVI A, ALVA-ARGAEZ A, et al. Linking pinch analysis and bridge analysis to save energy by heat-exchanger network retrofit[J]. Applied Thermal Engineering, 2016: 443-472. [7] AHMAND S, HUI D C W. Heat recovery between areas of integrity[J]. Computers & Chemical Engineering, 1991, 15(12): 809-832. [8] HONG X D, LIAO Z W, SUN J Y, et al. Transshipment type heat exchanger network model for intra- and inter-plant heat integration using process streams[J]. Energy, 2019, 178: 853-866. doi: 10.1016/j.energy.2019.04.112 [9] BAGAJEWICZ M, RODERA H. Multiple plant heat integration in a total site[J]. AIChE Journal, 2002, 48(10): 2255-2270. doi: 10.1002/aic.690481016 [10] HUI C W, AHMAD S. Minimum cost heat recovery between separate plant regions[J]. Computers & Chemical Engineering, 1994, 18(8): 711-728. [11] HU C W, AHMAD S. Total site heat integration using the utility system[J]. Computers & Chemical Engineering, 1994, 18(8): 729-742. [12] DHOLE V R, LINNHOFF B. Total site targets for fuel, cogeneration, emissions, and cooling[J]. Computers & Chemical Engineering, 1992, 7: S101-S109. [13] KLEMEŠ J, DHOLE V R, RAISSI K, et al. Targeting and design methodology for reduction of fuel, power and CO2 on total sites[J]. Applied Thermal Engineering, 1997, 17(8/10): 993-1003. doi: 10.1016/S1359-4311(96)00087-7 [14] 尹洪超, 张英, 李振民. 改进的全局能量集成法及其在炼油联合装置中应用[J]. 大连理工大学学报, 2001, 41(5): 552-556. doi: 10.3321/j.issn:1000-8608.2001.05.012 [15] 章琦, 张冰剑, 王北星. 夹点技术分析在装置间热联合优化的应用[J]. 节能, 2013, 032(7): 53-57. [16] BOLDYRYEV S, SHAMRAEV A A, SHAMRAEVA E O. The design of the total site exchanger network with intermediate heat carriers: Theoretical insights and practical application[J]. Energy, 2021, 223: 120023. doi: 10.1016/j.energy.2021.120023 [17] . 韦鉴, 夹点技术分析在装置间热联合优化的应用[J]. 化工管理, 2019(17): 124-125. [18] 任思月, 冯霄, 周树叶, 等. 基于总复合曲线的催化裂化-气体分馏装置热联合方案[J]. 石化技术与应用, 2021, 39(2): 87-92. [19] BÜTÜN H, KANTOR I, MARÉCHAL F. A heat integration method with multiple heat exchange interfaces[J]. Energy, 2018, 152: 476-488. doi: 10.1016/j.energy.2018.03.114 [20] PAVÃO L, COSTA C, RAVAGNANI M. Heat exchanger networks retrofit with an extended superstructure model and a meta-heuristic solution approach[J]. Computers & Chemical Engineering, 2019, 125: 380-399. [21] RODERA H, BAGAJEWICZ M. Multipurpose Heat-Exchanger Networks for Heat Integration Across Plants[J]. Industrial & Engineering Chemistry Research, 2001, 40(23): 5585-5603. [22] TARIGHALESLAMI A H, WALMSLEY T G, ATKINS M J, et al. Total Site Heat Integration: Utility selection and optimisation using cost and exergy derivative analysis[J]. Energy, 2017, 141: 949-963. doi: 10.1016/j.energy.2017.09.148 [23] NORDMAN R, BERNTSSON T. New pinch technology based HEN analysis methodologies for cost-effective retrofitting[J]. The Canadian Journal of Chemical Engineering, 2001, 79: 655-662. -