This document provides the system description for the Water Treatment System for NGHI SON 2 Thermal Power Plant. Raw sea water from CW pump is directly fed to the pretreatment system and seawater must be treated by Lamella Clarifier, Ultra Filtration (UF), and Sea water Reverse Osmosis (SWRO) process as a source for the service water required. The service water shall be transfer to Demineralized Water Treatment System to make demineralized water which is consist of Brackish Water Reverse Osmosis (BWRO), Degasifier and Mixed Bed Polisher
FOR CONSTRUCTION Rev Owner 16.10.2019 J.H.SEOK Y.H.PARK S.K.LEE 25.07.2019 J.H.SEOK Y.H.PARK S.K.LEE Date Prepared Checked Approved FOR CONSTRUCTION FOR CONSTRUCTION Details of Revision Owner’s Engineer Contractor DOOSAN HEAVY INDUSTRIES & CONSTRUCTION Sub-Supplier SAFBON WATER TECHNOLOGY Project NGHI SON BOT THERMAL POWER PLANT (2 x 600MW) Title [water treatment plant]_SYSTEM DESCRIPTION Document No Rev NS2-XS00-P0GCF-120001 Page-No 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 RECORD OF REVISION Rev Date Page Affected Description of Revision 25.07.2019 16 For Construction 16.10.2019 For Construction Rev.1 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 INTRODUCTION SYSTEM / COMPONENT DESCRIPTION 2.1 GENERAL REQUIREMENT 2.2 DESIGN AND FLOW PATH DESCRIPTION MAJOR EQUIPMENT DESCRIPTION 3.1 PRETREATMENT SYSTEM 3.1.1 COAGULANT DOSING SYSTEM 3.1.2 POLYMER (COAGULANT AID) DOSING SYSTEM 3.1.3 SODIUM HYPOCHLORITE DOSING SYSTEM 3.1.4 ACID DOSING SYSTEM 3.1.5 CLARIFIED WATER POND 3.1.6 ULTRA FILTRATION SYSTEM 3.1.7 UF CLEANING PUMPS 3.1.8 UF AIR BLOWERS 3.1.9 FILTERED WATER POND 3.2 SWRO SYSTEM 3.2.1 SODIUM BISULFITE DOSING SYSTEM 3.2.2 ANTISCALANT DOSING SYSTEM 10 3.2.3 CARTRIDGE FILTERS FOR SWRO 10 3.2.4 SWRO HIGH PRESSURE (HP) PUMPS WITH VFD 10 3.2.5 SWRO TRAINS 11 3.2.6 ENERGY RECOVERY DEVICE WITH BOOSTER PUMPS WITH VFD 11 3.2.7 SWRO FLUSHING PUMPS 11 3.2.8 RO CIP SYSTEM 12 3.3 BWRO SYSTEM 12 3.3.1 BWRO HIGH PRESSURE PUMPS WITH VFD 13 3.3.2 BWRO TRAINS 13 3.3.3 DEGASIFIER 14 3.4 MIXED BED POLISHER UNITS 14 3.4.1 MBP FEED PUMPS 14 3.4.2 MIXED BED POLISHER UNITS 14 3.4.3 REGENERATION SYSTEM 14 3.5 POTABLE WATER SYSTEM 15 3.5.1 ACTIVATED CARBON FILTER VESSELS 15 Rev.1 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 3.5.2 SODIUM HYPOCHLORITE DOSING SYSTEM 15 3.6 CHEMICAL STORAGE 15 3.6.1 ACID STORAGE, UNLOADING / TRANSFER SYSTEM 15 3.6.2 CAUSTIC STORAGE, UNLOADING / TRANSFER SYSTEM 15 3.6.3 ANTISCALANT, COAGULANT, NAOCL STORAGE, UNLOADING / TRANSFER SYSTEM 16 3.6.4 SBS, COAGULANT AID STORAGE, UNLOADING / TRANSFER SYSTEM 16 3.7 FINAL TREATMENT OF WASTE WATER FROM WTP 16 3.7.1 NEUTRALIZATION CHEMICAL WASTE WATER 16 3.7.2 DISPOSAL OF SEA WATER WASTE 16 OPERATION 17 4.1 SYSTEM OPERATION 17 4.1.1 LAMELLA CLARIFIER 17 4.1.2 ULTRA FILTRATION (UF) SYSTEM 18 4.1.3 SWRO UNITS 20 4.1.4 BWRO UNITS 21 4.1.5 MIXED BED POLISHER UNITS 21 4.1.6 POTABLE WATER SYSTEM 23 DESCRIPTION OF CHEMICAL STORAGE & FILLING 24 INSTRUMENT AND CONTROLS 24 6.1 INSTRUMENTS 24 6.2 CONTROL 25 CODE AND STANDARD 25 REFERENCE 25 APPENDIX A 26 Rev.1 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 INTRODUCTION This document provides the system description for the Water Treatment System for NGHI SON Thermal Power Plant Raw sea water from CW pump is directly fed to the pre-treatment system and seawater must be treated by Lamella Clarifier, Ultra Filtration (UF), and Sea water Reverse Osmosis (SWRO) process as a source for the service water required The service water shall be transfer to Demineralized Water Treatment System to make demineralized water which is consist of Brackish Water Reverse Osmosis (BWRO), Degasifier and Mixed Bed Polisher SYSTEM / COMPONENT DESCRIPTION 2.1 General Requirement The water treatment system plant is designed for the production of service water, potable water, and demineralized water and consist of the following major equipment • • • • 2.2 Pretreatment system and associated chemicals: Lamella Clarification system, Ultra Filtration (UF) system, coagulation and flocculant aid chemcial feed systems and sludge treatment system RO system and associated chemicals which consist of SWRO trains, antiscalant chemical feed systme, sodium bisulfite chemical feed system, Energy Recovery Device (ERD) with booster pumps, SWRO permeate tank, Demineralzied water system consisting of BWRO trains, a degasifier with blowers, mixed bed polisher (MBP) trains, caustic and acid chemical regeneration feed systems, Potable water system consisting of activated carbon filters and chlorination Design and Flow Path description Raw water passes through a static mixer, coagulation tank, flocculation tank, a lamella clarifier, and finally is collected into clarified water pond Coagulant – ferric chloride (FeCl3) and sodium hypochlorite (NaOCl) are dosed into coagulant tank directly and hydrochloric acid (HCl) is dosed into the static mixer located on raw water feed common line The static mixer ensures proper mixing of the acid before acid treated raw water reaches the clarifier An agitator is installed in the coagulation tank to mix the chemicals rigorously The coagulation tank effluent overflows into the flocculation chamber which is equipped with an agitator for slow & gentle mixing In the flocculation tank, coagulant aid (polymer) is slowly mixed with coagulated water to agglomerate smaller flocs formed in the coagulation tank into larger one The agglomeration of flocs or the creation of larger flocs will make it easier for suspended solids to settle in the clarifier downstream Rev.1 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 Dosing rates for both coagulant and coagulant aid (polymer) is determined at the site based on jar tests and will be adjusted seasonally to account for changing water quality The chemically pretreated water flows through a basin with inclined (Lamella) plates where the separation of solids occurs Water flows upward through the inclined plates while solids slide downward through the plates The accumulated sludge at the bottom of clarifier will be pumped to thickener by sludge disposal pump and will be further treated by filter press The clarified water quality to be; • Turbidity ≤ NTU The clarified water (Turbidity≤4 NTU) is collected in a clarified water pond where it is pumped to the UF unit for further filtration and solids removal The filtrate (Turbidity≤0.1 NTU, SDI≤3) from the UF is directed to the filtered water pond UF cleaning water source for the UF will be filtered water stored in the same tank Air scour is employed to reduce the cleaning wastewater and extend the service run The UF filtrate quality to be; • Turbidity ≤ 0.1 NTU • SDI ≤ For the SWRO system, The SWRO feedwater is injected with sodium bisulfite for dechlorination of SWRO feed water and ensure that no residual chlorine is present prior to entering the SWRO as well as antiscalant is added as a safety factor for controlling scaling potential of all other ions The SWRO permeate quality to be; • pH : 7.5 – 8.5 (after NaOH injection) • Silica < 10 ppm • TDS < 300 ppm • Chloride < 175 ppm The SWRO permeate is routed to plant & fire water storage tank as a source of service water required SWRO permeate is also routed to SWRO permeate tank for demineralized system which consists of BWRO and MBP for boiler make up water The BWRO permeate quality to be, • TDS ≤ 10 ppm (Max) • Silica < 0.1 ppm Permeate from the BWRO trains is routed to a permeate header which supplies water directly to the Mixed Bed Polishers after passing through degasifier and BWRO brine is returning to SWRO Feed The Mixed Bed Polishers exchange the remaining anions and cations and CO2 in the RO permeate producing ultrapure water to the Demineralized Water Storage Tank Rev.1 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 The produced Demineralized water qualtity to be, • Conductivity at 25C < 0.1 àS/cm ã Total Silica as SiO2 0.01 ppm The mixed bed polisher resin is regenerated on a weekly (168 hr) basis, using acid and caustic The regenerated wastewater flows to chemical wastewater pond which is combined with UF cleaning chemical waste The combined chemical wastewater is transferred to Waste Water Plant The potable water system will take service water by potable water pumps from the plant & fire water storage tank passing through a set of activated carbon filters to remove mainly organics The filter effluent is treated with sodium hypochlorite, to ensure that a residual chlorine remains in the potable water tank Typically, the system works based on the level in the potable water tank When there is a call for water, the activated filter is on, and when tank is full, the service inlet valve to the activated carbon filter closes On a periodic basis the activated carbon filter is backwashed from plant & fire water storage tank and the wastewater generated is directed to the chemical waste water pond Major Equipment Description Here is a description of the major equipment in the three major sections of the plant: Pretreatment, SWRO, BWRO, and Mixed Bed Polishers 3.1 Pretreatment System The Raw water pretreatment system comprises of following major equipment: • x 50% Coagulation Tank • x 50% Flocculation Tank • x 50% Lamella Clarifier System • x 100% Coagulant Dosing System • x 100% Polymer Dosing System • x 100% Sodium Hypochlorite Dosing System • x 100% Acid Dosing System • x 100% Sludge Disposal pumps • x 100% Thickener • x 100% Thickened Sludge Transfer pumps • x 100% Filter press • x 100% Clarified Water Pond • x 50% UF Feed Pumps • x 50% Auto Strainers • x 50% Ultra Filtration Trains • x 100% UF Air Blowers • x 100% UF Cleaning Pumps Rev.1 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 • x 100% Filtered Water Pond 3.1.1 Coagulant Dosing System The coagulant is dosed into the coagulation tank and the coagulant dosing system consists of following equipment: • x 100% Dosing Tanks • x 50% Dosing Pumps It is expected the coagulant to be used is 38% ferric chloride solution which will be delivered to the site and stored in the coagulant dosing tank and dosed into the feed water as per the dosing rate that is established after conducting jar tests at site 3.1.2 Polymer (Coagulant Aid) Dosing System The polymer is dosed into the flocculation tank as a coagulant aid The Polymer Dosing System comprises of the following equipment: • x 100% Polymer Auto Dissolving Unit • x 50% Dosing Pumps 3.1.3 Sodium Hypochlorite Dosing System Sodium hypochlorite will be dosed to maintain residual chlorine in the raw water Sodium hypochlorite dosing system comprises of the following equipment: • x 100% Dosing Tank • x 50% Dosing Pumps 3.1.4 Acid Dosing System Acid (HCl) solution will be dosed to decrease pH of the raw sea water The acid flows by transfer pumps from the acid storage tank which is a vertical 22 m³ tank used to supply acid for the entire plant including acid for mixed bed regeneration and UF cleaning • x 100% Dosing Tanks • x 100% Dosing Pumps 3.1.5 Clarified Water Pond The Clarified Water Pond (above ground) collects Clarified water from the Lamella Clarifier and provide feed water connecting to UF feed pump This pond is built of concrete and painted internally This Clarified Water Pond is provided with Level Transmitter 3.1.6 Ultra Filtration System Rev.1 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 Ultrafiltration (UF) is a process that filters particles on the basis of size In membrane separations, UF is typically used to separate or remove relatively large particles, such as microbes, bacteria, and macromolecules with molecular weights greater than approximately 300,000 Daltons or sizes greater than approximately 0.08 μm The primary objective of the UF membrane filtration system is to treat feed water high in suspended solids to a quality acceptable for use as RO feed water The UF membrane filtration system consists of membrane modules installed in a skid assembly for space savings and ease of operation The membrane fibers are constructed of polyvinylidene difluoride (PVDF), which provides good chemical and mechanical stability and capacity Clarified sea water is pumped through the UF filters by the UF Feed Pumps In order to protect the UF membrane fibers from damage by large debris and to prevent the growth of crustaceans, raw seawater is pre-screened with strainers with 120 μm or smaller pore size This pre-screened water is then directly fed to the UF membrane skids The UF membrane system operation consists of filtration, flushing, air scouring, Maintenance Cleans (MC), Recovery Cleans (RC), and Membrane Integrity Test (MIT) During filtration, feed water is pressurized on the outside of the membrane fiber and forced into the inner lumen, outside-in configuration UF has two flushing steps in control One is feed flushing and the other filtrate flusing Feed flushing will be conducted by UF feed pump and filtrate flushing will be done by the cleaning pumps Cleaning water is the filtered seawater supplied from the filtered water pond and thus, all cleaning waste water will be dumped to the seawater waste pond containing other seawater waste and transferring to outfall 3.1.7 UF Cleaning Pumps The cleaning pumps are provided to carry out cleaning operation of the UF membrane Hydraulic cleaning and maintenance cleaning are performed with chemical using UF cleaning pumps, sodium hypochlorite dosing pumps, and hydrochloric acid dosing pumps The cleaning initiation is automatically triggered by the PLC based on timer (once every 24 hours) 3.1.8 UF Air Blowers The air scouring blowers are provided for the air scour of the UF membrane The UF membrane modules contain air manifolds and houseing on the bottom of each module to deliver air from the UF air blowers This air provides shear to the membrance surface, dislodging debris, which is then flushed from the system 3.1.9 Filtered Water Pond Rev.1 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 The Filtered Water Pond (above ground) collects filtered water from the UF trains and provide in return the water required for cleaning of the trains This pond is built of concrete and painted internally This Filtered Water Pond is provided with Level Transmitter The outlet header of the UF trains is provided with a turbidity analyzer to indicate the quality of water going into the filtered water pond 3.2 SWRO System The RO System for service water production comprises of following major equipment: • x 33% SWRO Feed Pumps • x 100% Sodium Bisulfite Dosing System • x 100% Antiscalant Dosing System • x 33% Cartridge Filters for SWRO • x 33% SWRO High Pressure (HP) Pump equipped with VFD • x 33% SWRO Trains • x 33% Energy Recovery Device (ERD) with booster pump with VFD • x 100% SWRO CIP System • x 100% SWRO Flushing pumps • x 100% SWRO Permeate tank Water supplied to the SWRO trains is at high pressure and is monitored whether enough suction pressure is provided for the SWRO high pressure (HP) pumps On the same line, the followings shall be installed: • Pressure transmitter at both suction and discharge of HP pumps • On/Off feed isolation valve to isolate all three trains • Static mixer for antiscalant and sodium bisulfite • On/Off dump valve to divert feed in case of ORP alarm which may indicate presence of chlorine residual in the feed water to the SWRO trains 3.2.1 Sodium Bisulfite Dosing System RO membranes cannot tolerate the presence of residual chlorine, therefore a de-chlorination chemical is used whenever residual chlorine is present in the feed water to the RO Sodium metabisulfite in the powder form is used as the de-chlorinating agent When sodium metabisulfite is mixed with water, it transforms into sodium bisulfite solution (SBS) As the dechlorination reaction is very rapid, it is recommended to dose SBS at the upstream of RO Cartridge Filters SBS Dosing System comprises of the following equipment: • x 100% Dosing Tanks • x 100% Dosing Pumps Rev.1 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 The mixed bed units are regenerated using dilute hydrochloric acid and sodium hydroxide approximately once per week The regeneration process is fully automatic and initiated by a totalizer or when the effluent exceeds the high conductivity setpoint alarm 3.5 Potable Water System The Potable water system treats the SWRO permeate with carbon filtration and chlorine, ensuring that it is suitable for potable water consumption in accordance with WHO guidelines and Vietnamese regulation Potable Water System comprises of the following equipment: • x 100% Activated Carbon Filter Vessels • x 100% Sodium Hypochlorite Dosing System Potable water from the treatment system is directed to a potable water storage tank from where it is distributed to the potable water distribution lines 3.5.1 Activated Carbon Filter Vessels Service water from plant & fire water storage tank passes through activated carbon filters (ACF) for color and odor removal Two (2) ACF – one operating and on standby – are provided 3.5.2 Sodium Hypochlorite Dosing System Sodium hypochlorite will be dosed to maintain residual chlorine in the potable water line Sodium Hypochlorite Dosing System comprises of the following equipment: • x 100% Dosing Tank • x 100% Dosing Pumps The filling of chemical solution into the dosing tank is done manually 3.6 Chemical Storage 3.6.1 Acid Storage, Unloading / Transfer System Acid Storage Tank of vertical cylindrical type are provided Acid is supplied by chemical delivery trucks There is one common fume scrubber connected to both tanks to remove any humidity from the air inside the vessels A service line is connected to the fume scrubber to scrub all the acid 3.6.2 Caustic Storage, Unloading / Transfer System The system consists of Caustic Storage Tank of vertical cylindrical type The tank is equipped with flange immersion type heater to keep the caustic hot during cold weather to prevent crystallization of the caustic Rev.1 15 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 3.6.3 Antiscalant, Coagulant, NaOCl Storage, Unloading / Transfer system Antiscalant, Coagulant, NaOCl are supplied by liquid drum and these chemical drums shall be placed at chemical storage area Each chemical dosing tank shall be filled in with chemical drum pumps 3.6.4 SBS, Coagulant aid Storage, Unloading / Transfer system SBS, Coagulant aid are supplied by powder bag and these chemical bags shall be placed at chemical storage area SBS powder shall be dissolved in dosing tank with agitator and coagulant aid shall be dissolved in auto dissolving unit 3.7 Final Treatment of Waste Water from WTP 3.7.1 Neutralization Chemical Waste Water All the chemical waste generated in the Demineralization Plant is transferred to the Chemical Waste Water Pond through the drain pipes laid in concrete trenches The Chemical Waste Water Pond is sized adequately to hold and neutralize the waste generated by regeneration of a Mixed Bed Polisher Unit, MBP non-chemical waste, ACF backwash waste, BWRO brine, and RO CIP waste The system comprises of the following equipment: • x 100% Chemical Waste Water Pond (below ground), • X 100% Chemical Waste Water Transfer Pumps, • x 100% Acid Dosing Pumps (shared with MBP regen acid dosing pumps) • x 100% Caustic Dosing Pumps (shared with MBP regen caustic dosing pumps) • pH transmitter, Level transmitter, When the chemical waste water is received in the chemical waste water pond, initiation of neutralization operation starts: • The neutralization acid & caustic dosing pumps start • The dosing of chemicals is initiated based on the pH reading from the pH Transmitter • Wastewater recirculation start while acid / caustic addition takes place Once the pH has reached acceptable value, the valve on the recirculation line closes and the discharge side valve opens and the waste is discharged to the sump 3.7.2 Disposal of Sea Water Waste All the sea water waste generated in the Demineralization Plant is transferred to the Sea Water Waste Water Pond The Sea Water Waste Water Pond is sized adequately to hold seawater waste Rev.1 16 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 generated from Auto Strainer backwash, SWRO brine, Thickener, filter press, clarifier, RO offspec waste and UF cleaning waste (seawater) The system comprises of the following equipment: • x 100% Seawater Waste Pond (below ground), • x 100% Seawater Waste Transfer Pumps, • x 100% Portable Pumps, • Level Transmitter, Once seawater waste received & collected, and the level in the pond reaches the high level, the transfer pump starts and waste water is discharged to the sump The slope and drain pit at the pond will be considered for solids settling and accumulation The collected solids shall be removed by potable pump regularly just in case Operation The Water Treatment System consists of three subsystems: • Pretreatment System • SWRO/ BWRO System • MBP System Each system will be controlled and monitored from the local control rooms via the PLC panel with operator station Each system will have PLC panel with operator station Appropriate interfaces between local control panel and the plant DCS will be provided (hardwired & soft signals) The important status of the Water Treatment System will be monitored from the plant DCS 4.1 System Operation 4.1.1 Lamella Clarifier If raw sea water becomes available, seawater is directly fed to the pre-treatment system with CW pumps, along with all the chemicals dosing system in the pretreatment process will start Acid (HCl) is dosed prior to the inline static mixer located in the feed line to regulate pH value to an optimum level for coagulation The static mixer ensures proper mixing of the acid before it reaches the clarifier The water flows past the static mixer after, into a common feed channel connecting the coagulation tank and flocculation tank Sodium hydochlorite (NaOCl) and Coagulant (FeCl3) are dosed in the coagulation tank for removal of dissolved iron and organic and for increasing the size of particles for effective settling Water in these tanks passes through a flash mixer and overflows into the flocculation tanks with coagulation aid (Polymer) dosing to interconnect and enmesh the colloidal particles into giant flocs Water in the flocculation tanks passes through a paddle type slow mixer and overflows into a common feed channel Water in the channel flows by gravity into the two clarifier basins Rev.1 17 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 equipped with inclined plates (lamella plates) Each clarifier basin is equipped with sluice gate to isolate the whole basin Afer the flocculation tank the treated water enters the clarifier section where the influent is directed upwards through banks of inclined plates where the effluent water exits at the upper surface and the solids (sludge) separate out, by gravity, falling to the bottom of the clarifier The sludge scraper in operation continuously moves the precipitate settling on the floor of the clarifier Sludge buildup inside the clarifier basins is connected by pipelines to two sludge disposal pumps The sludge disposal pump transfers accumulated sludge to thickener and treated by filter press finally Clarified water from the basins is collected into common channel where clarified water is piped into a common clarified water pond by gravity Service: Removal of particulates using a clarification process and chemical aids Inlet Flow: x 550 m3/h (Inst Max) Equipment: Coagulation Tank – Qty: x 50% Flocculation Tank – Qty: x 50% Agitators – Qty: Clarifier – Qty: x 50% Clarified water pond – Qty: x 100% Sludge Disposal Pumps – Qty: x 100% Thickener – Qty: x 100% Thickened Sludge Transfer Pumps – Qty: x 100% Filter Press – Qty: x 100% Retention Times: Coagulation Tank: minutes Flocculation Tank: 20 minutes Chemical Dosing: Coagulant: 11.2 liters/hr Polymer: 770 liters/hr Thickener hydraulic loading: m3/m2/day Transfer By: Gravity to clarified water pond Pumps for sludge waste Next Process: Ultra Filtration System 4.1.2 Ultra Filtration (UF) System Filtrate: The UF feed pumps are used to apply sufficient pressure to force feed water through the pre-screen as well as through the UF membranes at the design flow The feed water is forced through the fiber into the lumen in an outside-in flow path The filtered water flows from the UF skid to filtered water pond To prevent the excessive build-up of foulants on the membrane surface, the filtration time is set based on projection results and adjusted based on operational experience During filtration, the filtrate flow is monitored via a flow transmitter at feed line and controlled with a flow control valve If the filtrate flow rises above or falls below the upper and lower flow limits respectively for an allotted amount of time, the system will shut down and go into fault Additionally, if the transmembrane pressure (TMP) rises above the set limit for an allotted amount of time, the system will shut down and go into fault An effluent turbidity analyzer will monitor the filtrate quality and alert operators if turbidity rises above acceptable limits Rev.1 18 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 Air Scouring: In order to maintain optimal performance and to prevent irreversible fouling, UF membranes require cleaning at regular intervals Membrane aeration blowers provide low pressure air into the bottom of the membrane module for air scouring Air scour cleanings for the membranes incorporate a series of air scouring, draining, and refilling to remove debris from the membrane surface and restore performance Maintenance Clean: Air scours alone are not sufficient to fully recover performance of the UF membranes Over time, a gradual decrease in membrane permeability is observed due to irreversible fouling from adsorption on the membrane surface and within the pore structure In order to recover this performance, maintenance cleans are automatically performed at regular intervals and consist of chemical soaking combined with air scouring Although feed water can be used for maintenance cleans, filtrate from the filtered water pond is recommended for this application due to a lower amount of suspended solids and lower chlorine demand The chemicals used for maintenance cleans consist of hydrochloric acid (HCl) and sodium hypochlorite (NaOCl) Sodium hypochlorite is used to oxidize organic foulants and acid is to remove inorganic scaling The waste from maintenance clean is discharged to chemical waste pond and then to waste after neutralization As stated above, maintenance cleans are performed at pre-programmed intervals However, maintenance cleans can also be triggered by high TMP, which would result in situations where the feed water is highly fouling (i.e inordinately high levels of suspended solids) Typical maintenance clean intervals range from 1-2 times per day Frequency is dependent on feed water quality as well as operational parameters Recovery Clean: At intervals determined by membrane performance and performance recovery via air scouring and maintenance cleans, recovery cleans can be performed to remove foulants that are not removed by the above mentioned methods Recovery cleans are an aggressive cleaning intended to restore the permeability of the membranes to near new levels Recovery cleans consist of aggressive air scouring and chemical backwashes combined with extended chemical soaking at elevated concentrations Elevated temperatures may also be used to increase cleaning efficiency Recovery clean frequency is site specific, but typically ranges from monthly to semi-annually Service: Inlet Flow: Equipment: Retention Times: Transfer By: Removal of particulates using a clarification process and chemical aids 572 m3/h (Inst Max, each) UF Feed Pumps – Qty: x 50% Auto Strainers – Qty: x 50% UF Trains – Qty: x 50% Filtered Water Pond – Qty: x 100% UF Air Blowers – Qty: x 100% UF Cleaning Pumps – Qty: x 100% Filtered Water Pond: at least 20 minutes Pumps to Filtered Water Pond for filtrate Rev.1 19 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 Next Process: Gravity drain to Waste water ponds for UF waste SWRO Please find the typical deail UF cleaning procedure in Appendix A 4.1.3 SWRO Units During normal operation, the recovery is monitored by the flow transmitters at permeate and reject lines The recovery is automatically adjusted by reject control valve if it varies due to inlet water condition changes The conductivity analyzer continuously monitors the permeate conductivity If the conductivity of permeate is higher than preset value then, the permeate dump valve opens after a time delay and permeate is allowed to drain for some time until conductivity is restored to a value below the high conductivity alarm setpoint If this does not occur, then the unit shuts down and goes into flushing cycle The work exchanger type energy recovery device (ERD) exchanges the residual pressure from the SWRO concentrate stream, boosting the filtered seawater supply pressure As there are some hydraulic losses in the membrane system and ERD, a booster pump is used to make up these losses thereby producing the required influent pressure to the RO train The SWRO high pressure pumps and ERD booster pumps are VFD controlled to maintain a constant permeate flow regardless of the feed water temperature or membrane age The concentrate control valve on the ERD is controlled by its own flow loop to maintain constant recovery These two (2) control loops ensure that the membrane flux rates and system recovery is maintained in accordance with manufacturers recommendations RO cleaning is required to be done once every to months depending upon the conditions of the RO feed water When the normalized differential pressure across the RO membranes exceeds 15%, the PLC initiates a warning for operator in order to plan for system shut-down and cleaning RO cleaning or CIP starts by preparing alkali or acid solution using RO permeate un-chlorinated water, turn on the heater inside the CIP tank, recirculation of the chemical solution until temperature reaches 35°C and pH adjustment is finalized, and recirculation thru one stage of the RO Each stage of the RO should be cleaned separately, and the chemical solutions used for cleaning the previous stage shall be discarded and fresh solution is prepared for the next stage The complete cleaning cycle has two steps for RO Unit In the first step, the RO CIP Pumps recirculate the solution through the fouled RO train, where each membrane gets cleaned thoroughly In second step, RO CIP Tank is filled with service water where it is pumped through the RO train to flush the RO High Pressure Pump and the entire RO unit The flushing ensures that all residual RO cleaning solution from the RO vessels and feed/reject piping has been flushed to drain Service: Inlet Flow: Dissolved solids removal for Serivce water application 340.7 m3/h (each) Rev.1 20 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 Equipment: Vessel Arrangement: Permeate Flow: Transfer By: Next Process: 4.1.4 SWRO Feed Pump – Qty : x 33% Cartridge Filters – Qty: x 33% High Pressure Pump – Qty: x 33% RO Train – Qty: x 33% RO Pressure Vessels – Qty: 108 (36 per train) RO Membranes – Qty: 756 (252 per train) 1st stage: 36 vessels 1st stage: 153.3 m3/h (each) Pumps to plant & fire water storage tank /SWRO permeate tank and BWRO BWRO BWRO Units The primary objective of the BWRO membrane filtration system is to treat feed water relatively high in dissolved solids to a quality acceptable for use as feed for the Mixed Bed Polisher (MBP) unit This includes the removal of small suspended particles that may have passed through the upstream treatment processes The BWRO system consists of pressure vessels installed in trains for space savings and ease of operation The membrane material is constructed of polyamide thin film composite, which provides good structural integrity and salt rejection The SWRO permeate is boosted to the feed pressure by the high pressure pumps and is fed to the BWRO membranes When water, at high-pressure, is fed to BWRO membranes, almost pure water (permeate) passes through the membrane while salts are retained on the concentrate side Permeate from each BWRO unit is delivered to the downstream MBP units and rejects is returning to SWRO feed Service: Inlet Flow: Equipment: Vessel Arrangement: Permeate Flow: Transfer By: Next Process: 4.1.5 Dissolved solids removal prior to mixed bed demineralizer 71.3 m3/h (each) BWRO Feed Pump – Qty: x 100% Cartridge Filters – Qty: x 100% High Pressure Pump – Qty: x 50% BWRO Train – Qty: x 50% BWRO Pressure Vessels – Qty: 10 (5 per train) BWRO Membranes – Qty: 70 (35 per train) 1st stage: vessels 2nd stage: vessels 1st stage: 38.5 m3/h 2nd stage: 23.6 m3/h Pumps to Degasifier basin and Mixed Bed Polisher Mixed Bed Polisher Mixed Bed Polisher Units The normal operation cycle of Mixed Bed Polisher (MBP) units is 168 hrs During this cycle, conductivity, silica and flow at outlet of MBP unit are continuously monitored If the conductivity, silica and totalizer are not within preset limit, then the working unit is taken out of service, and is regenerated until all conditions are met During the regeneration process, the other unit will be put in operation mode because there is a break tank (degasifier basin) between the RO and the mixed bed units which the break tank water shall be consumed during 18 minutes of Rev.1 21 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 fast rinse (from MBP projection) Currently, the tank has 20 retention time for the case of one MBP unit is in operation and other unit is in regeneration (fast rinse) From the service cycle to the end of the regeneration steps, the regeneration process consists of the following: Service Backwash Settling Regeneration Displacement Rinse Drain Air Mix Settling Slow refill 10 Fast refill 11 Fast Rinse 12 Back to Service These steps will describe in details in the control philosophy, all other steps follow the traditional steps implemented for typical mixed bed regeneration Acid (Hydrochloric acid) and caustic is used to regenerate the mixed bed Backwash: The BW inlet & outlet valves open allowing BWRO permeate water from the main header to BW the vessel The backwash water source is used from Demin water Settling: The step is right after shutdown backwash Backwashed and mixed resin shall be separated by different density, more dense cation resin bids shall be settled faster than anion resein bids Caustic / Acid injection : The regeneration process is simultaneous and it’s a block flow: Diluted caustic flows downward while diluted acid flows upward Chemical wastes are collected in the middle regenerant collector and is diverted to the chemical waste pond Displacement Rinse : Displacement rinse will occur the same way as regeneration using the demineralized water to displace all acid & caustic Drain : The purpose of this step is to lower water levl of resin surface in the vessel through intermediate collector for proper mixing Air mixing : Blowers will deliver air to mix the resin after the vessel being drained after drain Settling : Air mix will continue, and it will stop suddenly to let the bed collapse after the resin has mixed for some time Rev.1 22 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 Slow refill : preventing to separate mixed resin after mixing, slow demin water is induced into the vessel through middle distributor The air is vented from the vessel during the filling Fast refill : Once water level above certain level in the vessel, vessel is filling by MBP feed pump from feedwater 10 Fast rinse: The water will flow through the bed the same way as in the service flowrate until conductivity of the water have reached the set-point required to put the bed back in service Once the MBP is regenerated, the vessel will be placed in standby mode and ready for the next service cycle Service: Inlet Flow: Equipment: Time between regenerations: Chemicals used for regeneration: Backwash flowrate: Backwash duration: Air mixing velocity: Total regeneration time: Transfer By: Next Process: 4.1.6 Produce high quality process water for boiler feed 62 m3/hr (each) Mixed Bed Polisher – Qty: x 100% MBP Regeneration /backwash pumps – Qty: 2x100% Air Blowers – Qty: x 100% 168 hours (7 days) 33% Hydrochloric acid (HCl) 45% Sodium Hydroxide (NaOH) 29 m3/hr 30 minutes 60 m/hr < hours Hydraulics to Mixed Bed Polisher And Demineralized water tank Demineralized Water Storage tank Potable Water System Potable Water takes water from the plant & fire water storage tank by potable water feed pumps This water is treated by passing the water through activated carbon filters and dosed with Sodium Hypochlorite for disinfection purposes The plant will optimize the applied chlorine dosing level based on the residual chlorine at the end of the distribution line which depends on potable water demand and quality of water The plant will also monitor the chlorine level at the end of the distribution line and apply the dosing requirement of the sodium hypochlorite to maintain residual chlorine in the potable water line The effluent water from the potable water tank is monitored by a set of instrumentation which consists of pH, residual chlorine, and conductivity If the any of the readings is not within limits, then the activated carbon inlet valves will close Service: Inlet Flow: Equipment: Chemical Dosing rate: Backwash rate: Treat SWRO permeate for potable use m3/hr (each) Activated Carbon Filters – Qty: x 100% Sodium hypochlorite (NaOCl): 0.5 liters/h m3/hr Rev.1 23 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 Backwash duration: Backwash frequency: Transfer By: Next Process: 10 minutes Based on elapsed time or differential pressure Filtrate to potable water tank Potable Water Tank Description of Chemical Storage & Filling The storage tanks serve to store hydrochloric acid (33%) and caustic solution (45%) used for water treatment plant (Pretreatment, RO, MBP, potable water and chemical waste neutralization systems) Typcial chemical filling procedure shall be recommendded as followings, Protective safety goggles face shield, protective suit, and rubber gloves must be worn when working on the equipment or manually pumping chemical solution The chemicals supplier, before beginning the filling process requires the authorized user to give confirmation by his signature that release into a working plant will not constitute a danger and will witness the filling process upon completion The storage tanks and pipework shall be checked at initial filling by carrying out successfully hydrostatic tests and checks with water The filling into the storage tank shall be depending on the site condition; using own tank lorry pump or using transfer pump The fillinig connection has to be identified for each chemical solution The relative isolation valves shall be opened after connection accordingly, then the discharge pump to be turned on Operator must check the level of storage tank and discharge pump to be turned off, then the relative valves to be closed out and hose to be disconnected Note that food grade chemical is required for potable water treatment only and industrial grade chemical is recommended for others chemcial treatments Instrument and Controls 6.1 Instruments Typical instruments necessary for the safe and efficient operation of the plant will be provided as followings, however please refer to the Instrument List (NS2-YL00-P0GCF-120001) and Piping & Instrument Diagram (NS2-XG02-P0GCF-120001) for the further details Flow transmitter on inlet water supply for total amount of feed Flow transmitter on product water of MBP for total amount of product Level transmitter on each pond / storage tank Turbidity analyzer upstream / downstream of a lamellar clarifier Turbidity / pH analyzer downstream of UF system pH / Cl2 / ORP / Conductivity / SDI analyzer upstream of SWRO Flow transmitter at SWRO permeate and concentrate Rev.1 24 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 pH / ORP / Conductivity analyzer upstream of BWRO Flow transmitter at BWRO permeate and concentrate 10 Sodium / Silica / pH analyzer at common MBP product 6.2 Control The water treatment plant will be primarily controlled automatically by PLC The interface between the Master Plant Control System are through hardwired connection and redundant MODBUS TCP/IP Important WTP process values are sent to the Plant DCS through MODBUS TCP/IP protocol over redundant serial links Refer to Control Configuration Diagram (NS2YF02-P0GCF-120001) Code and Standard The codes and standards applicable for these systems are as listed below: Korean Industrial Standard (KS) American Society of Mechanical Engineers (ASME) American National Standard Institute (ANSI) American Society for Testing of Material (ASTM) American Welding Society (AWS) International Electro technical Commisson (IEC) Instrument Society of America (ISA) National Electrical Manufacturers Association (NEMA) American Water Works Association 10 International Standards Organization Reference NS2-XG02-P0GCF-120001 Piping & Instrument Diagram NS2-XG08-P0GCF-120001 Process Flow Diagram & Mass Balance NS2-CC07-P0GCF-120001 Calculation Sheet NS2-XW03-P0GCF-120004 Design Criteria NS2-XXXX-P0GCF-125002 Process Control Functional Description NS2-YL00-P0GCF-120001 Instrument List NS2-YF02-P0GCF-120001 Control Configuration Diagram NS2-CQ02-P0GCF-120001 Operation & Maintenance Manual Rev.1 25 of 29 [water treatment plant]_SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 APPENDIX A (TYPICAL) UF MEMBRANE CLEARING PROCEDURE Rev.1 26 of 29 Air Scour Sequence Valve Position Step Step Description Stop Filtration Typical Step Duration (s) Typical Cumulative Sequence Duration (s) Pump Status Feed (AV-01) Filtrate (AV-05) Top Drain (AV-06) Drain (AV-07) Filtrate to Air for Air Scour Drain MIT (AV-03) (AV-08) (AV-04) MC/RC Feed (AV-02) MC/ Feed Air Chemical Chemical RC Pump Blower Dosing Pump Injection Pump (P-1) (B-1) (DP-1/2/3) (P-2) 0 O O X X X X X X X R S S S Step Transition - Feed pump speed adjustment 10 10 O O X X X X X X X R→S S S S Step Transition - Valve positioning and blower speed adjustment 15 O→X O→X X→O X X→O X X X X S S S→R S 60 75 X X O X O X X X X S S R S 80 X X O→X X→O O X X X X S S R S Air Scour Step Transition - Valve positioning Air Scour and Drain 60 140 X X X O O X X X X S S R S Step Transition - Blower speed adjustment and valve positioning 145 X X X O O X X X X S S R→S S Step Transition - Feed pump speed adjustment 10 155 O X O X X X X X X S→R S S S 30 185 O X O X X X X X X R S S S 190 O X→O O→X X X X X X X R S S S 190 O O X X X X X X X R S S S Sequence duration (s) 190 Notes: O=open valve R=Run pump Sequence duration (min) 3.2 X=Closed Valve S=Stop Pump Skid Fill Step Transition - Valve positioning Resume Filtration Valve cycling speed: Average Pump ramp-up/down speed: Average Sec 10 Sec Maintenance Clean Sequence Stop Filtration Step Transition - Feed pump speed adjustment Chemical Dosing Pump (DP-1/2/3) Air Blower (B-1) MC/RC Pump (P-2) Feed Pump (P-1) Chemical Injection MC/RC Feed (AV-02) (AV-04) Air for MIT (AV-08) (AV-03) (AV-07) (AV-06) Pump Status Filtrate to Drain Cumulative chemical WW volume (m3) Air Scour Chemical WW Volume (m3) Drain Typical Cumulative Flowrate Chemical Cumulative chem free to waste Free WW Sequence waste (m3/h) Volume (m3) Duration (s) volume (m3) Top Drain Typical Step Duration (s) Feed Step Description Filtrate Step Number (AV-05) (AV-01) Valve Position O O X X X X X X X R S S S 10 10 0.00 0.00 O O X X X X X X X R→S S S S Step Transition - Valve positioning and blower speed adjustment 15 0.00 0.00 O→X O→X X→O X X→O X X X X S S S→R S Air Scour Step Transition - Valve positioning 60 75 0.00 0.00 X X O X O X X X X S S R S 80 0.00 0.00 X X O X→O X X X S S R S Air Scour and Drain 60 140 10.26 0.00 X X O O X X X S S R S Step Transition - Valve positioning and blower speed adjustment O→X X X→O X→O S S R→S S S→R 10.26241101 O→X X→O X O 145 10.26 0.00 X X Step Transition - RC pump and chemical pump speed adjustment 10 155 10.26 0.00 X X O X X X X O O S S→R S Fill with cleaning solution 300 455 10.26 0.00 X X O X X X X O O S R S R Step Transition - RC pump and chemical pump speed adjustment Step Transition - Valve positioning 10 465 0.09 X X O X X X X O O S R→S S R→S 470 10.26 0.09 X X O X X X X O→X O→X S S S S Chemical Soak 600 1070 10.26 0.09 X X O X X X X X X S S S S Step Transition - Valve positioning and blower speed adjustment 33 10.26 0.09 X→O O→X O→X 1075 10.26 0.09 X X O X X→O X X X X S S S→R S Chemical Air Scour Step Transition - Valve positioning 300 1375 10.26 0.09 X X O X O X X X X S S R S 1380 10.26 0.09 X X O X X→O X X S S R S Air Scour and Pressurized Chemical Drain 10 1390 10.26 5.61 X X O X O X X S S R S Step Transition - Valve positioning and blower speed adjustment 1395 10.26 5.61 X→O X X→O O→X X X S S R→S S Step Transition - Feed pump speed adjustment and valve positioning 10 1405 10.26 5.61 O X O X X O X X X S→R S S S Refill 30 1435 10.26 5.61 O X O X X O X X X R S S S 1440 10.70 5.61 O X O→X X X O X X X R S S→R S Step Transition - Valve positioning Chem Rinse Air Scour 60 1500 10.70 5.61 X X O X O X X X X S S R S Step Transition - Valve positioning 1505 10.70 5.61 X X O X→O X X X S S R S Chemical Rinse Air Scour and Drain 60 1565 16.22 5.61 X X O O X X X S S R S Step Transition - Valve positioning and blower speed adjustment 1570 16.22 5.61 X→O X O→X X X X→O S S R→S S Refill Step Transition - Valve positioning 30 1470 16.22 5.61 O X X X X O X X X R S S S 1475 16.66 5.61 O X→O X X X O→X X X X R S S S Step Transition - Feed pump speed adjustment Resume Filtration 10 1485 16.66 5.61 O O X X X X X X X R S S S 1485 16.66 5.61 O O X X X X X X X R S S S 10 11 12 Sequence duration (s) Sequence duration (min) 1485 25 318 0.440972222 318 0.440972222 5.52 O→X X→O X O X→O O→X O→X O→X X→O X O X→O O→X O→X Notes: O=open valve X=closed valve R=run pump S=stop pump Recovery Clean Sequence Stop Filtration Step Transition - Feed pump speed adjustment 10 10 Step Transition - Valve positioning and blower speed adjustment 15 Air Scour Step Transition - Valve positioning 60 75 X X 80 X X Air Scour and Drain Step Transition Transition RC Valve positioning and blower speed adjustment Step pump and chemical pump speed 60 140 X X 145 X X adjustment 10 155 X X O X Fill with cleaning solution 300 455 X X O Step Transition - RC pump and chemical pump speed adjustment Step Transition - Valve positioning 10 465 X X O (DP-1/2/3) Chemical Dosing Pump Air Blower (B-1) MC/RC Pump (P-2) Feed Pump (P-1) Chemical Injection MC/RC Feed (AV-02) (AV-04) Air for MIT (AV-08) Pumps Filtrate to Drain (AV-03) Air Scour (AV-06) (AV-07) Drain Typical Cumulative Sequence Duration (s) Top Drain Typical Step Duration (s) Feed Step Description Filtrate Step (AV-05) (AV-01) Valve Position O O X X X X X X X R S S S O O X X X X X X X R→S S S S X X→O X X X X S S S→R S X O X X X X S S R S O X→O X X X S S R S O O X X X S S R S O→X X S S R→S S X X X O O S S→R S S→R X X X X O O S R S R X X X X O O S R→S S R→S O→X O→X X→O O O→X X→O X O X→O O→X O→X X→O X→O 470 X X O X X X X S S S S Chemical Soak Step Transition - Valve positioning and blower speed adjustment 2700 3170 3175 X X X X O O X X X X→O X X X X X X X X S S S S S S→R S S Chemical Air Scour Step Transition - Valve positioning 300 3475 X X O X O X X X X S S R S 3480 X X O X X→O X X S S R S Skid Topoff Step Transition - Valve positioning 10 3490 O X O X X O X X X R S S S 3495 O X O→X X X O X X X R S S→R S X X X X O O X X X X→O X X X X X X X X S S S S S S→R S S X O O O→X X→O Chemical Soak Step Transition - Valve positioning and blower speed adjustment 2700 6180 6185 Air Scour and Pressurized Chemical Drain Step Transition - Valve positioning and blower speed adjustment 10 6195 X X 6200 X→O X Step Transition - Feed pump speed adjustment and valve positioning 10 6210 O X O X Refill Step Transition - Valve positioning 30 6240 O X O 6245 O X Chem Rinse Air Scour Step Transition - Valve positioning 60 6305 X X 6310 X X O→X X→O 12 Chemical Rinse Air Scour and Drain Step Transition - Valve positioning and blower speed adjustment 60 6370 6375 X X→O X X X O O X→O O→X O→X 13 Refill Step Transition - Valve positioning 30 6275 O X X X 6280 O X→O X X Step Transition - Feed pump speed adjustment 10 6290 6290 O O O O X X X X 10 11 14 Resume Filtration Sequence duration (s) Sequence duration (min) 6290 105 O→X O→X X O X X S S R S X→O O→X X X S S R→S S X O X X X S→R S S S X X O X X X R S S S O→X X X O X X X R S S→R S O X O X X X X S S R S O X→O X X X S S R S O O→X X X X X X X→O S S S S R R→S S S X O X X X R S S S X O→X X X X R S S S X X X X X X X X X X R R S S S S S S X→O O→X O→X Notes:O=open valve X=closed valve R=run pump S=stop pump ... of 29 [water treatment plant] _SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 INTRODUCTION This document provides the system description for the Water Treatment System for NGHI SON Thermal Power Plant. .. 29 [water treatment plant] _SYSTEM DESCRIPTION NS2-XS00-P0GCF-120001 3.2.8 RO CIP System A ‘Clean-in place (CIP)’ system will be supplied for membrane cleaning when this is required The CIP system. .. NS2-CC07-P0GCF-120001 Calculation Sheet NS2-XW03-P0GCF-120004 Design Criteria NS2-XXXX-P0GCF-125002 Process Control Functional Description NS2-YL00-P0GCF-120001 Instrument List NS2-YF02-P0GCF-120001