珠海香洲水质净化厂PLC控制系统设计(二)

>>>本文紧接上篇 * DO meter No. 2, MLSS meter No. 1-3 and bypass flowmeter No. 1-2 are served as monitoring purposes. No control function is given on these instrumentation. * 溶解氧计2号, 污泥浓度计1号–3号, 旁通流量计1号–2号, 只作监测, 不参与控制。Description 详述: Selector switches for the disc aerators No. 1-8 are located on MCC2, each equipment is equipped with an emergency stop. 转碟1 – 8号的选择制设在MCC2上, 每台设备旁设紧急按钮。Selector Switch选择制: Manual Mode手动模式: Disc aerators No. 1- 8 are operated continuously. 转碟1 – 8号连续运行。Remote Control Mode遥控模式: Operation of disc aerators No. 1-8 is controlled by the computer inside central control room or by PLC under automatic mode. 由中控室内的终端机控制转碟1 – 8号连续运行或由PLC控制自动运行。 Automatic Operation自动运行: Organic degradation and simultaneous nitrification/denitrification occur in the Orbal oxidation ditch. In outer channel, dissolved oxygen is controlled between 0-0.5mg/l. This also ensures a sufficient mixing effect in the outer channel. According to the pre-requisite requirement, PLC is therefore programmed for controlling disc aerators MA-501 and MA-502 at outer channel. Depending on influent quality and flowrate, it is possible to select whether one disc aerator or two disc aerators to be operated from the computer. The PLC will monitor outer channel dissolved oxygen level via DO meter No. 1 DO-501 at a preset T15 interval. If dissolved oxygen level exceeds a preset value of 0.5mg/l, disc aerators will stop in operation at a preset value of T16 (To prevent biomass settling in the oxidation ditch, disc aerators shall not be stopped for more than 30 mins.). When one of aerators is selected for operation, another aerator will be in standby mode. If one aerator is fault, automatic change over will carry out. Change over of aerators’ operation is preset at 20 hrs intervals. Orbal氧化沟的外沟主要是将碳源氧化, 并同时进行硝化及反硝。沟内溶解氧须控制在0 – 0.5mg/l之间, 并须保持外沟有足够的搅拌混和能力。PLC程序根据上述两点要求, 控制安装在外沟的转碟ZMA-501, ZMA-502的操作模式, 首先按进水水质及流量等实际情况, 在终端机上选择只操作一台转碟或两台转碟同时操作。当选择只操作一台转碟时, 另外一台作为备用, 一旦转碟出现故障, 将自动切换备用转碟。两台转碟按操作时间(设定为20小时)轮换主、备用。 Operation of disc aerators MA-503 – MA-508 is controlled by DO meter DO-503 at inner channel. DO level in middle channel is controlled at 0.5-1mg/l and inner channel is controlled at 2-2.5mg/l. DO level is preset at 2.5mg/l. PLC will monitor DO value of DO-503 at inner channel in accordance with preset timer T17. If DO is lower than 2.5mg/l, the number of disc aerators in operation will be increased. If DO is higher than 2.5mg/l, the number of disc aerators in operation will be reduced. One set of disc aerator will be switch on or off during the change on the number of disc aerators in operation. If a high DO value persists, all disc aerators will be off; however to present biomass settling, two disc aerators will be switched on in accordance with time T18. On the other hand, to ensure sufficient mixing at the oxidation ditch, only a maximum of 4 set disc aerators are preset to be off. PLC is also programmed that the operation of disc aerators can be change over automatically, e.g. change over will occur automatically if one aerator is fault. 根据内沟的溶解氧计ZDO227控制转碟ZMA-503至ZMA-508的开关组合, 来控制中沟的溶解氧在0.5 – 1.0 mg/l之间, 内沟的溶解氧在2 – 2.5之间。为确实足够的搅拌混和, 最少开2台（即一组）转碟，溶解氧的设定值为2.5mg/l, PLC程序会按T16的设定值, 定时检测内沟的溶解氧计ZDO227的数值, 如数值低于设定值(2.0mg/l), 增加转碟操作数量; 如数值高于设定值(2.5mg/l), 减少转碟操作数量, 每次增加或减少一台转碟。 如转碟发生故障, 即自动切换备用转碟。转碟分为3组：第一组为ZMA-503、ZMA-506；第二组为ZMA-505、ZMA-508；第三组为ZMA-504、ZMA-507。PLC程序按时间8H进行组先后顺序的轮换： (第一组 第 二组 第 三组)。 在先 开第一组，增加转碟时开的顺序为： ZMA-505 ZMA-508 ZMA-504 ZMA-507； 在先开第二组，增加转碟时开的顺序为： ZMA-504 ZMA-507 ZMA-503 ZMA-506 ； 在先开第三组，增加转碟时开的顺序为： ZMA-503 ZMA-506 ZMA-505 ZMA-508。停的顺序与开的顺序相反。T16设定值可在终端机机上设定。见表4-8和4-9 * MLSS meter No. 3 and No. 4 are served as monitoring purposes. No control function is given. * 污泥浓度计4号, 污泥浓度计5号, 只作监测, 不参与控制。Description 详述:Suction Clarifier No.1 & No.2 吸刮泥机1号及2号Selector switches for the suction clarifier No. 1 and No. 2 are located on Local Control Panel, each equipment is equipped with an emergency stop. 吸刮泥机1号及2号的选择制设在现场控制盘上, 在设备旁设紧急按钮。Selector Switch选择制: Manual Mode手动模式: Suction clarifiers No. 1 and 2 are operated continuously. 吸刮泥机1号及2号连续运转。终端机不进行吸刮泥机的控制，但监视其运行、故障、过载信号。 Vacuum Pump 真空泵 Electric supply device and selector switch for the vacuum pump is located in Local Control Panel on the scraper bridge. The vacuum pump is not put on fixed installation, when the air in the suction pipe is removed, a siphon effect will be induced, and the vacuum pump can then be taken away. 真空泵的配电装置及开关制安装在吸刮泥机上的现场控制盘。真空泵不作固定安装, 抽出吸泥管的空气, 吸泥管形成虹吸后, 把真空泵搬走。见表4-10与表4-11 * Return sludge flowmeter is served as monitoring purposes. No control function is given. * 污泥回流流量计, 只作监测, 不参与控制。 Description 详述: Return Sludge Pump No.1, No.2及No.3 污泥回流泵1号, 2号及3号 Selector switches for the return sludge pump No. 1 - 3 are located on MCC2, each equipment is equipped with an emergency stop. 污泥回流泵1号, 2号及3号的选择制设在MCC2上, 在水泵旁设紧急按钮。 Selector Switch选择制: Manual Mode手动模式: Return sludge pumps No. 1 – 3 are operated continuously. 污泥回流泵1号, 2号及3号连续运转。 Remote Control Mode遥控模式: Operation of return sludge pumps No. 1-3 is controlled by the computer inside central control room or by PLC under automatic mode. 由中控室内的终端机控制污泥回流泵1号, 2号及3号连续运行或由PLC控制自动运行Automatic Operation自动运行: Return sludge pumps and inlet pumps are operation simultaneously. When one set inlet pump is switched on, one set return sludge pump will be automatically switched on by PLC. When two sets inlet pump are in operation, two sets return sludge pump will be automatically switched on by PLC. When three sets inlet pumps are in operation and the inlet pump with frequency invertor is also in full load operation, three sets return sludge pump will be automatically switched on by PLC. 污泥回流泵与进水泵同步运行, 当启动QP1进水泵, PLC程序将相对启动QP222污泥回流泵，其频率与QP1的频率相同; 当进水泵有两台运行时, PLC程序将相对启动两台污泥回流泵; 当进水泵有三台运行时, PLC程序将相对启动三台污泥回流泵。三台定速泵每隔24H轮换一次先后顺序。 If any of return sludge pumps is in off mode, it will be regarded as standby unit. If fault is found on duty pump, the standby pump will be automatically change over. The