5B10_3X1 (3)-29-33.pdf

GPP-5 I.A.-3 04 CONTROLS 04.1 General Operation and Maintenance Manual The Wastewater Treatment Unit consists of several vendor package units interconnected with individual equipment items. Package units will be complete with sufficient controls, alarms, trips etc to allow steady, automatic an...

GPP-5 I.A.-3 04 CONTROLS 04.1 General Operation and Maintenance Manual The Wastewater Treatment Unit consists of several vendor package units interconnected with individual equipment items. Package units will be complete with sufficient controls, alarms, trips etc to allow steady, automatic and safe operation of the equipment. Operating data will be made available to the operator by transmission of selected package data to the DCS. Refer to vendor P&ID’s and the following sections of vendor operating manuals for details of package instrumentation. − Arsenic Removal Unit A5-1001 − Flotation Treatment Unit A5-1002 : section 1 of operation part − Wastewater Filters Unit A5-1005 : section 3 : section C&E Controls for individual equipment items are described below and on Unit 10 UFD’s. 04.2 Control Loops by Equipment Items 04.2.1 Chloride Scrubber Wastewater Pit (T5-1001) The level of the chloride scrubbing wastewater is controlled with LT-0132 that: − in case of high level will start the pump P5-1001A or B. − in case of low level will stop the pump. The interlock LALL-0132 shuts down pumps P5-1001A/B. 04.2.2 Chloride Scrubber Wastewater Pumps (P5-1001A/B) Controller for pump minimum flow recycle via FC-0122 is as follows. Valve FV-0122A in T5-1001 is split ranged with FV-0122B. As FV-0122B closes to maintain set flowrate and the flowrate of the pumped liquid from T51001 is less than pump minimum flowrate, FV-0122A opens to return excess flow back to the chloride scrubber Wastewater Pit T5-1001 and to maintain pump minimum flowrate. 04.2.3 Preseparators (T5-1002A/B) The level of the Continuously Oil Contaminated (COC) drain in the Preseparator is controlled by means of: − LT-0101 located in the bay A which acts as start / stop signal for P5-1002A or B. − LT-0102 located in the bay B which acts as start / stop signal for P5-1002C or D. The following interlocks are provided: Unit 10 - Waste Water Treatment 5B10_3X1.doc Controls / Page 1 of 12 Rev.01 GPP-5 I.A.-3 Operation and Maintenance Manual − LALL-0103 located in the bay A shuts down pump P5-1002A/B. − LALL-0104 located in the bay B shuts down pump P5-1002C/D. 04.2.4 Preseparator Pumps (P5-1002A/B/C/D) The pumps are provided with automatic control to ensure the minimun flow. It consists of FC-0101 which operates the control valve FV-0101 located on the common recycle back to the Preseparator. The set point of the controller will be determined by the number of pumps operated. 04.2.5 Oil Sump (T5-1003) The level of the recovered oil in the Oil Sump is controlled by means of LT-0105 that acts as start / stop signal for the pumps P5-1005A or B. The following interlock LALL-0160 shuts down the pumps P5-1005A/B. 04.2.6 Slop Oil Separators (T5-1007) The pressure control of T5-1007 is obtained by means of PCV-0107 that works with PCV0108 to provide a fuel gas blanket in Slop Oil Separator T5-1007 at approximately 2 bar(a). Refer to operating pressure in the Slop Oil Separator as shown at table 04.5. The level of the oil in the Slop Oil Separator is controlled by means of LT-0113A that acts as start / stop signal for the pumps P5-1007A or B. The interlock LAHH-0115 stops pumps P5-1005A/B. The interlock LALL-0115 shuts down the pumps P5-1007A/B. The level of the separated water collected in the vessel boot is obtained by means of the LC-0116 that controls the valve LV-0116 with gap action maintaining the oil/water interface level between the high and low level. The interlock AAHH-0107 closes XV-0107. The interlock FALL-0108 shuts down the pumps P5-1007A or B. 04.2.7 Equalization Tank (T5-1008) To ensure a nitrogen blanket in the Equalization Tank T5-1008 at approximately 1.01 bar (a) the PCV-0109 working with a breather valve (PSV-T5-1008A) has been provided. In the event of maloperation of PCV-0109 and PSV-T5-1008A, PSV-T5-1008B works to protect the Equalization Tank T5-1008. The LC-0141 has been provided to control the level in the tank: − High and Low levels will act respectively as lead pump start and lead / lag pumps stop signals. − Control valve LV-0141A is split ranged with LV-0141B which together control a constant level in the Equalization Tank T5-1008 when the inlet flowrate is lower than the capacity of the CPI Feed Pumps. Adjustable range have been provided in Control room via HC-0141A/B. Unit 10 - Waste Water Treatment 5B10_3X1.doc Controls / Page 2 of 12 Rev.01 GPP-5 I.A.-3 Operation and Maintenance Manual The oil layer thickness in the tank is controlled via LT-0139 that acts on on/off valve XV0143. The interlock LAHH-0140 starts P5-1004A/B/C lag pump and shuts down P5-1002A/B/C/D. The interlock LALL-0140 shuts down P5-1004A/B/C lead/lag pumps. 04.2.8 Skimmed Oil Tank (T5-1009) The level of the skimmed oil collected in the tank is obtained by means of the LT-0124 that will start / stop the Skimmed Oil Pumps P5-1012A/B. 04.2.9 Filter Backwash Tank (T5-1010) Level in the Filter Backwash Tank is controlled with LT-0150 that: − in case of low level will open the valve XV-0132 on the inlet line. − in case of high level will close the valve XV-0132. The interlock LAHH-0151 closes XV-0132. The interlock LALL-0151 opens XV-0132. 04.2.10 Wastewater Sludge Sump (T5-1013A) Sludge level in the Wastewater Sludge Sump is controlled with LT-0165 that: − in case of high level will start the pump P5-1008A. − in case of low level will stop the pump. The interlock LALL-0166 shuts down pump P5-1008A. 04.2.11 Wastewater Sludge Sump (T5-1013B) Sludge level in the Wastewater Sludge Sump T5-1013B is controlled with LT-0167 that: − in case of high level will start pump P5-1008B. − in case of low level will stop the pump. The interlock LALL-0168 shuts down pump P5-1008B. 04.2.12 Clear-Water Sump (T5-1014) The LC-0170 has been provided to control the level in the sump: − High and Low level will act respectively as lead pump start and lead pump stop signals; − Control valve LV-0170B is split ranged with LV-0170A. As valve LV-0170B closes to maintain level of Clear Water Sump T5-1014, LV-0170A opens to maintain pump minimum flowrate. LT-0169 acts as stop signal for P5-1009A/B lag pump. The interlock LAHH-0169 starts P5-1009A/B lag pump. The interlock LALL-0169 shuts down P5-1009A/B lead / lag pumps. 04.2.13 Waste-Water Sump (T5-1016) Unit 10 - Waste Water Treatment 5B10_3X1.doc Controls / Page 3 of 12 Rev.01 GPP-5 I.A.-3 Operation and Maintenance Manual Level in the Wastewater Sump is controlled with LT-0157 that: − in case of high level will start P5-1013A/B lead pump. − in case of low level will stop the lead / lag pumps. 04.2.14 Pump Control as lead and lag Normal operating conditions are such that lead pumps will satisfy capacity required to transfer normal flowrate of liquids to each downstream compartment. When incoming liquids exceed output capacity of lead pump and reach set level in Sumps, lag pump will automatically start to increase flowrate of liquid and prevent liquid overflow. Manual field switchings are used to determine lead or lag pump of the same service pumps. Following pumps operate as lead and lag, either to protect the pumps against low level or to protect the equipment against overfilling. − Clear Water Pumps P5-1009A/B − CPI Feed Pumps P5-1004A/B/C − Waste Water Sump pumps P5-1013A/B 04.3 Complex Loops − Backwashing operation of Wastewater Filters Package A5-1005 (UFD 050/1110/117) A filter bed can function properly only if the backwashing operation cleans the clogging material within the filter bed to be washed out effectively. The method used for this operation is water backwashing with auxiliary air scour and the initiation of the backwashing cycle is set to be occured automatically on; • • • • set volume of filtered water elapsed time bed pressure drop manual initiation The backwashing cycle shall be as follows; • • • air scour slow backwash rapid backwash Unit 10 - Waste Water Treatment 5B10_3X1.doc Controls / Page 4 of 12 Rev.01 GPP-5 I.A.-3 04.4 Operation and Maintenance Manual Operator Interface: DCS and Local Panels Operator console is the interface between the operator and the DCS. The operator console is designed in such a way to meet operator needs in terms of monitoring, controlling and recording plant operation; moreover, facilities are available to configure and maintain the system. The DCS is provided by two (2) operator console, one for utilities operation and the other for process operation. Local Control Panels for Arsenic Removal Package, Flotation Treatment Package and Wastewater Filters Package are equipped with VDU (Video Display Unit) which enables the operator to access the control system and then monitor/control each package as part of User Interface devices. In addition, additional Pushbuttons and Lamps as required are mounted on Local Control Panel for specific operation. On the other hand packages which don’t have PLC i.e. CPI Separator and Sludge Filter, are provided with Local Control Panel for controlling and monitoring purposes. 04.5 Controller Settings, Alarms and Trips - Table 04.5 includes trip and alarm set points. Unit 10 - Waste Water Treatment 5B10_3X1.doc Controls / Page 5 of 12 Rev.01