Optimization for steam power system in iron and steel works

doi:10.16085/j.issn.1000-6613.2017-0237

Abstract

Abstract: With the issue of energy shortage and environmental pollution becoming more and more urgent,the iron and steel works face increasingly higher pressure of energy saving and emission reduction. A reasonable production plan plays an important role in cost saving and emission reduction. Aiming at the steam power system in iron and steel works,this paper has established a mixed-integer nonlinear programming(MINLP)model that uses fitting formulas of boilers and decomposed model of turbines,considering energy equipments,process operation and time-of-use power price. The application of the nonlinear boiler fitting formulas makes the model more consistent with the actual situation. With the minimization of operating cost,the optimal dispatch scheme of fuels and load at each period were obtained. The total cost has reduced by 4.26 percent compared to the non-optimum one. Two case studies were presented to demonstrate the feasibility of the proposed model. The influence of coal price and fuels was analyzed and the result has proved that this paper is constructive on efficiency improvement,energy conservation and emission reduction.

Key words: steam power system, time-of-use power price, environment, optimization, systems engineering

摘要： 随着能源短缺与环境污染问题日益紧迫，钢铁企业所面临的节能减排压力也越来越大，合理的生产方案对降低企业运行成本、减少污染物排放起着重要的作用。本文针对钢铁企业蒸汽动力系统，采用锅炉效率非线性拟合公式和汽轮机分解模型，考虑能源设备、生产操作以及分时电价等因素，建立了混合整数非线性规划（MINLP）模型，其中，非线性锅炉效率拟合公式的引入使得模型更加符合实际生产状况。模型以蒸汽动力系统运行成本为目标函数，通过优化求解得到各时段燃料和设备负荷的分配方案，与优化前相比，系统总的运行费用减少了4.26%。同时，本文还分析了煤价变化对优化方案的影响以及燃料结构对污染物排放的影响，为企业提高生产效率、降低运行成本及节能减排提供理论依据。

关键词: 蒸汽动力系统, 分时电价, 环境, 优化, 系统工程

CLC Number:

TK01⁺8

GAO Jintong, NI Tuanjie, ZHANG Qi. Optimization for steam power system in iron and steel works[J]. Chemical Industry and Engineering Progress, 2017, 36(11): 4301-4307.

高金彤, 倪团结, 张琦. 钢铁企业蒸汽动力系统优化[J]. 化工进展, 2017, 36(11): 4301-4307.

References

[1] ZHANG Y J,HAO J F,SONG J. The CO₂ emission efficiency, reduction potential and spatial clustering in China's industry:evidence from the regional level[J]. Applied Energy,2016,174(14):213-223.
[2] KARALI N,XU T,SATHAYE J. Developing long-term strategies to reduce energy use and CO₂ emissions——analysis of three mitigation scenarios for iron and steel production in China[J]. Mitigation & Adaptation Strategies for Global Change,2016,8(11):1-21.
[3] HE F,ZHANG Q Z,LEI J S,et al. Energy efficiency and productivity change of China's iron and steel industry:accounting for undesirable outputs[J]. Energy Policy,2013(54):204-213.
[4] AKIMOTO K,SANNOMIYA N,NISHIKAWA Y,et al. An optimal gas supply for a power plant using a mixed integer programming model[J]. Automatica,1991,27(3):513-518.
[5] KIM J H,YI H S,HAN C. A novel MILP model for plantwide multiperiod optimization of byproduct gas supply system in the iron-and steel-making process[J]. Chemical Engineering Research & Design,2003,81(8):1015-1025.
[6] 张琦,提威,杜涛,等. 钢铁企业富余煤气-蒸汽-电力耦合模型及其应用[J]. 化工学报,2011,62(3):753-758. ZHANG Q,TI W,DU T,et al. Coupling model of gas-steam-electricity and its application in steel works[J]. CIESC Journal, 2011,62(3):753-758.
[7] CHEN C L,LIN C Y. Design and optimization of steam distribution systems for steam power plants[J]. Industrial & Engineering Chemistry Research,2011,50(13):8097-8109.
[8] 孟华,王建军,王华,等. 基于环境成本的钢铁企业自备电厂锅炉负荷优化模型[J]. 钢铁研究学报,2013,25(12):28-34. MENG H,WANG J J,WANG H,et al. Optimal model of boiler load based on environmental costs in self-provided power plant of iron and steel works[J]. Journal of Iron and Steel Research,2013,25(12):28-34.
[9] ZENG Y J,SUN Y G. Short-term scheduling of steam power system in iron and steel industry under time-of-use power price[J]. Journal of Iron and Steel Research, International,2015,22(9):795-803.
[10] SAYYAADI H. Multi-objective approach in thermoenvironomic optimization of a benchmark cogeneration system[J]. Applied Energy,2009,86(6):867-879.
[11] AGHA M H,THERY R,HETREUX G,et al. Integrated production and utility system approach for optimizing industrial unit operations[J]. Energy,2010,35(2):611-627.
[12] 李晖,孙力,贺高红. 考虑不确定汽电需求的蒸汽动力系统优化设计[J]. 化工学报,2013,64(1):318-325. LI H,SUN L,HE G H. Design and optimization of steam power system with uncertain steam and power demands[J]. CIESC Journal,2013,64(1):318-325.
[13] LUO X L,ZHANG B J,CHEN Y,et al. Modeling and optimization of a utility system containing multiple extractions steam turbines[J]. Energy,2011,36(5):3501-3512.
[14] LUO X L,ZHANG B J,CHEN Y,et al. Operational planning optimization of multiple interconnected steam power plants considering environmental costs[J]. Energy,2012,37(1):549-561.
[15] LUO X L,HU J H,ZHAO J,et al. Multi-objective optimization for the design and synthesis of utility systems with emission abatement technology concerns[J]. Applied Energy,2014,136(24):1110-1131.
[16] 张鹏飞,赵浩,荣冈,等. 考虑生产成本和环境成本的蒸汽动力系统多目标运行优化[J]. 化工学报,2016,67(3):715-723. ZHANG P F,ZHAO H,RONG G,et al. Multi-objective optimization for steam power system considering production cost and environmental cost[J]. CIESC Journal,2016,67(3):715-723.
[17] SHANG Z,KOKOSSIS A. A transhipment model for the optimization of steam levels of total site utility system for multi-period operation[J]. Computers & Chemical Engineering,2004,28(9):1673-1688.
[18] VARBANOV P S,DOYLE S,SMITH R. Modelling and optimization of utility systems[J]. Chemical Engineering Research & Design,2004,82(5):561-578.