城市生活污水处理厂电气和控制系统的节能优化研究

发布时间：2018-12-10 17:38

【摘要】：城市污水处理厂是解决水污染问题最有效和最重要的途径,具有显著的社会、经济和环境效益。然而,由于在建设过程中重点考虑了处理工艺的先进性和稳定性及工程投资等问题,而忽视了污水厂高能耗对后续运行成本的影响,造成许多污水处理厂建成后给当地财政造成较大压力,甚至有些污水厂由于运营成本过高而不能正常运行。本文通过对污水厂运行过程中能耗构成和能耗分布的分析,提出了污水处理厂工程设计阶段电气和自控系统的节能优化设计方法,并通过乌兰浩特东区污水厂项目进行了验证,取得明显节能效果。本文的主要结论如下:(1)污水处理厂按工艺单元划分为预处理段工艺单元、生化处理段工艺单元和污泥处理段工艺单元。其中,预处理段能耗约占全厂能耗的18%~25%,生物处理段能耗约占全厂能好的55%~70%,污泥处理段能耗约占全厂能耗的8%~10%。污水提升和曝气系统是全厂能耗最大的两个环节,约占全厂80%以上电耗。(2)污水处理厂电气系统节能优化设计主要应包括:合理确定设备工作制和选择需要系数优化负荷计算算法;选用节能变压器选型、合理确定容量选配、优化运行方式;按照负荷分布,优化变电站选址布局;通过动力设备选型、低压侧集中无功补偿和变压器接线方式提高功率因数与谐波抑制;选择低损耗电缆,优化配电路由;采用高效率电机、软启动和变频调速手段降低设备运行能耗;选用高效节能灯具、合理布光、合理选择照度、优化控制降低照明能耗。(3)污水处理厂自控系统节能优化设计主要应根据污水厂控制规模和控制要求选择控制系统。目前我国污水厂控制系统主要采用集散型控制系统(DCS)和现场总线型控制系统(FCS);预处理段自控系统节能优化设计包括格栅液位差控制、污水提升泵组轮询控制和变频调速控制,以及管理节能方法,如夜间来水量低时,水泵低速运行或停止运行,尽量利用水池蓄水能力,保持高液位运行,减少水头损失。生物处理段自控系统节能优化包括生化池工艺设备连续控制,优化生化池处理效率;消化液回流泵变频控制;鼓风机变频控制按需供气。污泥处理段自控系统节能优化设计包括,污泥池泥位控制和污泥脱水机自动控制。
[Abstract]:Urban sewage treatment plant is the most effective and important way to solve the water pollution problem. It has remarkable social, economic and environmental benefits. However, due to the consideration of the advanced nature and stability of the treatment process and the project investment in the construction process, the influence of high energy consumption on the subsequent operation cost of the wastewater treatment plant is ignored. As a result, many sewage treatment plants are under great pressure on local finance after completion, and some sewage treatment plants can not operate normally because of the high operating cost. Based on the analysis of the energy consumption composition and energy consumption distribution during the operation of the wastewater treatment plant, this paper puts forward the energy saving optimization design method of the electric and automatic control system in the design stage of the sewage treatment plant project, and verifies it through the Wulanhaote East District sewage Plant Project. Obvious energy saving effect has been achieved. The main conclusions of this paper are as follows: (1) the wastewater treatment plant is divided into pretreatment unit, biochemical treatment section process unit and sludge treatment stage process unit according to the process unit. Among them, the energy consumption of pretreatment stage accounts for about 18% of the energy consumption of the whole plant, the energy consumption of biological treatment section accounts for 5570 of the energy consumption of the whole plant, and the energy consumption of sludge treatment section accounts for 8% and 10% of the energy consumption of the whole plant. Sewage lifting and aeration systems are the two most energy-consuming links in the plant. About 80% of the power consumption in the whole plant. (2) the optimal design of energy saving in the electric system of sewage treatment plant should include: reasonably determining the working system of the equipment and optimizing the load calculation algorithm for selecting the demand coefficient; Select the type of energy-saving transformer, reasonably determine the capacity selection, optimize the operation mode, according to the load distribution, optimize the substation location layout; Power factor and harmonic suppression are improved by selecting power equipment, low voltage side centralized reactive power compensation and transformer wiring, and low loss cable is selected to optimize distribution route. Adopt high efficiency motor, soft start and frequency conversion speed regulation means to reduce the equipment running energy consumption; Select high-efficiency energy-saving lamps, reasonable distribution of light, reasonable selection of illumination, optimization control to reduce the energy consumption of lighting. (3) the optimal design of energy saving of automatic control system of sewage treatment plant should be mainly based on the control scale and control requirements of the sewage plant control system. At present, (DCS) and (FCS); are mainly used in the control system of wastewater treatment plant in China, which is based on distributed control system (DCS) and fieldbus control system (FCS);). The energy saving optimization design of automatic control system in preprocessing section includes grid level difference control, polling control of sewage lifting pump group and variable frequency speed regulation control, and management of energy saving methods, such as low water flow at night, low speed operation or stop operation of water pump, Make full use of water storage capacity to maintain high water level and reduce head loss. Energy saving optimization of automatic control system in biological treatment section includes continuous control of biochemical pool process equipment, optimization of treatment efficiency of biochemical tank, frequency conversion control of digestible liquid reflux pump and frequency conversion control of blower on demand for gas supply. The energy saving optimization design of automatic control system of sludge treatment section includes sludge level control and automatic control of sludge dewatering machine.
【学位授予单位】：北京建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X799.3

【参考文献】