TRAINING MANUAL FOR STEAM AND WATER SAMPLING SYSTEMEROOM TECHNOLOGY CO., LTD. TRAINING MANUAL FOR SWSS FOR HRSG UNIT CONTENTS 1. SWSS General 2. Basic Cycle Chemistry of Drum-type Units 2.1 Steam Generator (Boiler) Conditioning 2.2 Feedwater Cycle Conditioning 3. Sample Points and Analysis Selection 3.1 Feedwater Pump Inlet (Sample #1, 8) 3.2 LP Drum Water (Sample #2, 9) 3.3 LP Superheated Steam (Sample #3, 10) 3.4 LP Saturated Steam (Sample #4,11) 3.5 HP Drum Water (Sample #5, 12) 3.6 HP Saturated Steam (Sample #6, 13) 3.7 HP Superheated Steam (Sample #7, 14) 3.8 Condensate extraction pump discharge (Sample #15) 3.9 Condensate polisher outlet (Sample #16) 3.10 Aux. cooling water (Sample #17) 4. Sample Obtaining and Transport 4.1 Sample Obtaining 4.2 Sample Transport -2- TRAINING MANUAL FOR SWSS FOR HRSG UNIT 5. Sample Conditioning 5.1 Pressure control 5.2 Flow control 5.3 Temperature control 5.4 Other sampling system components 5.5 Instrumentation and control 6. Sample Analysis 6.1 Precautions for grab sampling 6.2 Precautions for on-line analysis 6.3 Analysis definition, methods and applications 7. References -3- -4- . pressure and flow regulators. temperature and pressure 1. pressure reducing valves.1 Purpose of SWSS ㆍTo transport and condition samples without altering the constituents in the samples. 1.TRAINING MANUAL FOR SWSS FOR HRSG UNIT 1 SWSS General 1.3 Components constituting Sampling System : pipes (tubes). blowdown valves. control systems.2 Parameters to be controlled : Velocity (flow). isolation valves. Primary and secondary coolers. ㆍTo provide information on cycle chemistry to help assure the performance determination of significant components and of the steam cycle in general. analyzers and instruments. resin columns. Corrosion products from condensate and feedwater systems.1 Problems that could be caused by inappropriate steam generator chemistry (1) Deposition of solids on inside boiler tube walls. -5- . mechanical carryover . Silica presents most difficult problem due to its high solubility in steam at intermediate S/G pressure.1. and hardness constituents (Ca and Mg) in boiler water.TRAINING MANUAL FOR SWSS FOR HRSG UNIT 2 Basic Cycle Chemistry of Drum-type Units 2. volatilization of impurities in drum water. drum water entrainment in steam Vaporous carryover . (2) Corrosion of S/G material which causes material loss heat transfer resistance by resultant oxides resulting in tube failure due to overheating and caustic attack (3) Contamination of steam entering turbine beyond the steam purity requirements of the turbine Steam could be contaminated by mechanical and vaporous carryover of boiler water.1 Steam Generator (Boiler) Conditioning 2. form scales on high heat flux area of S/G reduces heat transfer and results in overheating and failure of tubes. 2 Methods to minimize the problems (1) Blowdown of S/G . In general.2.1 Conventional Treatment (1) Elevates cycle pH in reducing environment by removing oxygen -6- . 2.1. (2) Corrosion within S/G can be minimized by maintaining pH of S/G water at 9.0 or above. sodium phosphate (Na3PO4) is injected to drum water to obtain desired pH level. SiO2 Total Iron (Fe) Total Copper(Cu) Target value < 0. Na Silica.TRAINING MANUAL FOR SWSS FOR HRSG UNIT - Steam quality requirement for typical HRSG plant during normal and constant operation Parameter Cation conductivity Sodium.2 Feedwater Cycle Conditioning Cycle conditioning is performed to minimize corrosion and subsequent transport of corrosion products to downstream and to the S/G. by continuously blowing down a portion of drum water (less than 1% of feedwater flow rate) the impurities concentrated in drum water can be removed.2 < 10 < 20 < 20 <3 Units ㎲/㎝ ㎍/㎏ ㎍/㎏ ㎍/㎏ ㎍/㎏ 2. 2. depending on the operating pressure. 0 is used in case copper is present in cycle. -7- . 2. (4) If copper is present in cycle material. N2H4). which could be obtained at pH value of around 8.2 Oxygenate Treatment (OT) (1) Mostly for all-steel cycle of once-through boiler.TRAINING MANUAL FOR SWSS FOR HRSG UNIT from feedwater at condenser and deaerator or by adding reducing agent (Oxygen scavenger. the copper solubility also has to be minimized. oxygen or other oxidizer is fed to the cycle to make oxidizing environment in the feedwater. pH should be kept around 9. (2) In the oxidizing environment. (5) Compromised pH value of around 9. with the solubility of the former much lower than the latter. (2) Reducing environment forms protective layer of magnetite (Fe3O4) over steel material.2.5. protective corrosion layer of ferric hydrate oxide is formed over base layer of magnetite. thus reducing corrosion.5. (6) Ammonia typically is used as pH control agent. (3) To minimize the solubility of magnetite. 1. 0~200 ppb -8- . grab sampling facility is furnished to enable further diversified analysis at laboratory environment. In the following sections.1. 3.1. ㆍTo determine compliance with the steam generator feeedwater purity requirements. 8) 3.3.TRAINING MANUAL FOR SWSS FOR HRSG UNIT 3 Sample Points and Analysis Selection Sample points and the analyses of each sample are selected based on the criteria that they should give data for the decision whether steam and water quality requirements of the cycle are met and the performances of important equipment in the cycle are satisfactory.2 Types of on-line Analysis and measuring ranges ㆍDissolved oxygen.1 Purpose of analysis ㆍTo monitor the performance of deaerator ㆍTo check the effectiveness of oxygen scavenging and use the data for dissolved oxygen control.1 Feedwater Pump Inlet (Sample #1. each sample is discussed for the necessity of its selection and types of analysis for a typical HRSG Cycle as shown in Fig. In addition to the on-line analyses of each sample as selected. 3. 11 #3.9 -9Chem. dosing #16 #1. 3. dosing #6. dosing #5.) is for HRSG#2 #15 . 1 Simplified diagram of typical HRSG cycle #2.8 Chem.10 TRAINING MANUAL FOR SWSS FOR HRSG UNIT Fig.13 #7.12 #4.Chem.14 for ex.14 Chem. dosing Note : The second sample number in a set of two numbers (#7. TRAINING MANUAL FOR SWSS FOR HRSG UNIT ㆍCation conductivity.1 Purpose of analysis ㆍTo determine the quantity of moisture and chemical carryover from . 0~100 ㎲/㎝ 3.2 Type of on-line analysis and measuring ranges ㆍpH.1 Purpose of analysis ㆍTo determine compliance with the turbine steam purity requirements 3. 0~14 pH 3.4.10 - .2 LP Drum Water (Sample #2. 0~2 ㎲/㎝ 3. 10) 3.2 Type of on-line analysis and measuring ranges ㆍpH.3.11) 3. 0~14 pH ㆍCation conductivity.3 LP Superheated Steam (Sample #3. 0~14 pH ㆍSpecific conductivity.2.4 LP Saturated Steam (Sample #4. 0~2 ㎲/㎝ ㆍpH. 9) 3.2.3.1 Purpose of analysis ㆍTo monitor the purity of boiler water which is critical for the performance and operational lifetime of boiler unit ㆍTo use the analysis results as the basis for blowdown control 3. 5. 14) .2 Type of on-line analysis and measuring range ㆍCation conductivity. 0~2 ㎲/㎝ 3. 0~2 ㎲/㎝ 3.6 HP Saturated Steam (Sample #6.6.1 Purpose of analysis ㆍTo determine the quantity of moisture and chemical carryover from the boiler 3.7 HP Superheated Steam (Sample #7. 13) 3. 0~100 ㎲/㎝ 3. 0~14 pH ㆍSpecific conductivity.5 HP Drum Water (Sample #5.TRAINING MANUAL FOR SWSS FOR HRSG UNIT the boiler 3.11 - .1 Purpose of analysis ㆍTo monitor the purity of boiler water which is critical for the performance and operational lifetime of boiler unit ㆍTo use the analysis results as the basis for blowdown control and Na3PO4 dosing 3.2 Types of on-line analysis and measuring ranges ㆍpH.4. 12) 3.2 Types of on-line analysis and measuring range ㆍCation conductivity.6.5. 0~2 ㎲/㎝ ㆍDissolved oxygen.2 Types of on-line analysis and measuring ranges ㆍpH. ㆍTo determine compliance with the turbine steam purity requirements 3.8.9.8 Condensate extraction pump discharge (Sample #15) 3.1 Purpose of analysis ㆍTo check for proper function of condensate polisher ㆍTo obtain base data for determining the performance of deaerator . 0~200 ppb ㆍSodium.7.7.TRAINING MANUAL FOR SWSS FOR HRSG UNIT 3. 0~2 ㎲/㎝ 3.1 Purpose of analysis ㆍTo monitor for in-leakage of cooling water in condenser ㆍTo monitor for air in-leakage in condensate extraction pump ㆍTo check for proper functioning of air ejectors 3.9 Condensate polisher outlet (Sample #16) 3.2 Types of on-line analysis and measuring ranges ㆍpH.8.12 - . 0~14 pH ㆍCation conductivity.1 Purpose of analysis ㆍTo check for the contamination of superheated steam due to attemperation water impurities. 0~50 ppb 3. 0~14 pH ㆍCation conductivity. 0~14 pH ㆍSpecific conductivity.1 Purpose of analysis ㆍTo monitor for contamination of auxiliary cooling water of the plant. 0~100 ㎲/㎝ ㆍDissolved oxygen.9. 0~100 ㎲/㎝ .10. 0~500 ppb 3.10. 0~2 ㎲/㎝ ㆍSpecific conductivity. Therefore.2 Types of on-line analysis and measuring ranges ㆍpH.13 - .10 Aux.TRAINING MANUAL FOR SWSS FOR HRSG UNIT 3. cooling water (Sample #17) 3. 3. 0~14 pH ㆍCation conductivity. the sample is not taken from feedwater cycle but from the cooling water supply line being introduced to Steam and Water Sampling System.2 Types of on-line analysis and measuring ranges ㆍpH. . the nozzle should not be installed on the bottom of the pipe.1 Water sampling (1) Sampling nozzles ㆍSee Fig. 1 for typical nozzle for water sampling ㆍSample taking from vertical pipe is preferable to avoid settling resulting from low velocity ㆍIn case the water sample has to be taken from horizontal pipe. 1 Typical Nozzles for Sampling Water> (2) Boiler Water Sample ㆍThe sample has to be taken from the location of maximum impurity concentration.14 - . < F i <Fig. 4.1.1 Sample Obtaining 4. 4.TRAINING MANUAL FOR SWSS FOR HRSG UNIT 4 Sample Obtaining and Transport The most important criteria in deciding methods of obtaining and transporting samples are whether they guarantee truly representative samples of fluids at their respective sampling points. 4. requiring isokinetic sampling.2 Saturated steam sampling (1) Saturated steam is often a two-phase fluid.2R of the pipe from pipe inner surface. . < Fig. See Fig. assuming fully developed turbulent flow. (2) Isokinetic sampling requires that the velocity of the fluid entering the sample port(s) is exactly same as the velocity of the stream being sampled at the location of the sampler. 4.1.15 - . since this is the location where actual and average velocities are equal. 2 Effects of Non-isokinetic Sampling> (3) Location of sampling nozzle : on long vertical pipes to avoid stratification of suspended solids and ensure that all water droplets are carried in the flow stream. made up of steam and droplets of water.TRAINING MANUAL FOR SWSS FOR HRSG UNIT 4. the nozzle is normally inserted 0. (4) Nozzle insertion length : For single port nozzle. 2. 4. 4. isokinetic sampling requirement may not apply.TRAINING MANUAL FOR SWSS FOR HRSG UNIT Multi-point nozzle can be used at locations where the velocity profile across the pipe is known. Physical phenomena such as deposition and erosion. thermal stress cycling and other possible causes. can deposit on the surfaces causing biased analytical results. (6) Structure and material of nozzle: should be designed strong enough to prevent failure due to vibration.3 Superheated steam sampling (1) Since superheated steam is usually regarded as single phase fluid. as steam pressure and temperature are reduced at nozzle and sample line. (2) High-pressure superheated steam can dissolve most contaminants which. (5) Port size : is determined to maintain isokinetic sampling in the nozzle port(s) at the desired sampling rate and design flow. But port diameter should be larger than 1/8 inch to prevent plugging. Nozzles normally are made of 316 stainless steel or other austenitic stainless steel or alloy 600.16 - . the same nozzle described for use with saturated steam can be used.2 Sample Transport Sample can be affected in many ways when they are transported from nozzles to sample conditioning system.1. However. thermodynamic . 4. particulate traps(such as strainers). (2) Sample line material selection. double valves may be required depending on safety considerations. crystallization and sorption are major causes that change the sample constituents. and low velocity zones. They should be as . Fitting also should be selected based on their temperature and pressure rating and made of materials compatible with the sample.3.2.TRAINING MANUAL FOR SWSS FOR HRSG UNIT changes such as throttling and heat loss. For high pressure samples. Tube inside diameter should be selected based on considerations of sample velocity and pressure drop as discussed in section 4. Design of sample transport system should be focused on the ways to minimize these changes and keep the samples unaffected as possible during the transport. Wall thickness and material of the tubes should be suitable for the temperature and pressure of the sample source and should be of corrosion-resistant material. (3) Installation : Sample lines should be free of dead legs. Stainless steel 316 is preferred material for wet part of the valve.1 Sample line construction (1) Valves : Root valves should be installed at sample source.17 - . 4. 316 Stainless Steel is preferred. Valve and bore diameter should be selected so that velocity of sample through the valve does not change much. and chemical and physical changes such as reactions of oxygen scavengers. Steady state deposit weights are at the minimum when liquid velocity is at 1.18 - .5 to 2. . 4. Tube bends are recommended instead of right angle fitting. Minimum deposits is desirable because of their shorter period of time for equilibrium and less susceptibility to particulate bursts.1 m/s.TRAINING MANUAL FOR SWSS FOR HRSG UNIT short as practical. diffusion or gravity. Adequate support to prevent fatigue failure from vibration should be provided but free expansion and contraction with temperature change should be allowed. oil free air or flushed prior to installation.2.2 Deposition Results from chemical analysis can be biased either by the loss of contaminants to the deposit on the tube wall or the gain of contaminants from the deposits. Sample lines normally should not be insulated. Burrs that could be produced after use of hacksaws and tube cutters should be blown out with clean. Mechanisms of deposition of contaminants are. (1) Settling of particles: particles in the sample can stick to the wall crossing the boundary layer by inertia. (4) Fabrication : Weldings on the sample tubes on small diameter tube (up to 3/8 inch) should be avoided as possible. Particles so deposited can be eroded later by fluid drag force becoming reentrained in the fluid stream. which could be attained only in case of liquid (condensate). where steam of pressure less than 35㎏/㎠ are produced.2. this pressure drop temporarily causes the steam to enter the superheat region. ㆍWhen the steam velocity entering sample line is high. In case of combined cycle plants.3 Saturated steam (1) Typical behavior of saturated steam during transport. ㆍSample velocity decrease from high speed of steam to lower speed of liquid. (3) Crystallization: Most contaminants can be dissolved in superheated steam. increase the volume then further decrease the pressure.5 to 2. As the pressure and temperature of steam decrease. 4.19 - . it will cause pressure drop.TRAINING MANUAL FOR SWSS FOR HRSG UNIT All colloidal materials such as ion oxides and effluents from demineralizers tends to form deposits also. (2) Sorption of dissolved species: Deposits on tube walls are porous and tend to sorb dissolved species by ion exchange. The .1m/s. absorption. the solubility of many contaminants is decreased and the contaminants crystallize and deposit on the surfaces of dry wall tubes. adsorption or other mechanism. ㆍPhase changes from saturated steam to two phase liquid of vapor and liquid then to liquid as the sample temperature decreases. As the desirable velocity of sample in the tube is 1. the length of steam portion in the transport tube should be short as possible. which gives harmful effect to obtaining representative sample. . Steam Vmax : Maximum velocity of steam at recommended length. regional changes of phase and resulting flow.R. Max.TRAINING MANUAL FOR SWSS FOR HRSG UNIT phase changes.” indicates not recommended for any length due to excessive pressure drop. from saturated steam to superheat steam then to liquid water will result in abrupt flow speed changes. Cond.1 summarizes the calculations for typical tube sizes at different pressure and flow condition. required steam velocity is given. “ * ” indicates that the steam is not condensed within recommended length. In the table. Table 4. Where tube size is not recommended for any length. (2) Sample flow rate should be maintained constant as possible to avoid condensing length changes. Vmin : Velocity of condensate at 500ft(154m). “ “ indicates * that the steam is not fully condensed in the recommended length or within 500ft(154m).20 - . Cond. A bullet(ㆍ) indicates that the steam velocity is increasing due to expansion. (3) Steam sample line sizing : For deciding sample line size and length. L : Length where all steam is condensed. “N. calculations to determine heat loss and pressure drop for different flow condition is required. following abbreviations are used. L : Maximum recommend length. 1 Recommended Sample Tube Sizes .21 - .TRAINING MANUAL FOR SWSS FOR HRSG UNIT Table 4. 1 are based upon straight tubing. Where applicable. 4. In case unusual number of bends is used in the sample transport line. 4. (2) Once the sample lose all its superheat.2.22 - .TRAINING MANUAL FOR SWSS FOR HRSG UNIT The calculations for Table 4. source cooling is recommended for this purpose.4 Superheated steam (1) To minimize deposit and loss of contaminants on the dry wall portion of sample line where the temperature is higher than the saturation temperature of the steam. This velocity range will result in minimum equilibrium deposit weight reached in the minimum operation period of about 30 days.1 m/s.5 Liquid samples Liquid sample lines should be sizes for sample speed of 1.2.1 includes recommendations for superheated steam also.5 to 2. it will behave in the same manner as saturated steam. it is recommended that superheat be removed from steam sample as early as possible. allowance for additional pressure drop has to be made. Table 4. . pressure and flow rate of the samples from the sample sources so that they are safe for grab sampling or are compatible with the requirements of on-line analytical instruments. Normally.5㎏/㎠. variable rod-in-tube type orifices are recommended for they ㆍprovide varying pressure drop ㆍare cleanable in place . Final target of these controls is to establish a constant pressure zone so that analyzers being fed from this zone get constant flows independent of actions taken in other branch lines. the pressure at the constant pressure zone is controlled at 0. pressure reduction and back pressure control.23 - . 5. 5.TRAINING MANUAL FOR SWSS FOR HRSG UNIT 5 Sample Conditioning The objective of steam and water sample conditioning system is to modify and control the temperature.1.1 Pressure control Pressure control of a sample is performed by incorporating two control methods.1 Pressure reducer (1) Pressure reducer is located down stream of primary sample cooler so that the liquid is sub-cooled before pressure reduction.5~1. (2) For samples greater than 35㎏/㎠. while maintaining constant flow in the main sample line. .TRAINING MANUAL FOR SWSS FOR HRSG UNIT Fig.24 - . 5. 1 Typical arrangement of a sample conditioning system for a high-pressure high-temperature sample. 2.1 Total flow rate through a sample line is basically decided considering optimum velocity requirement in the sample transport line (1. other factors such as pressure drop along the transport line. back pressure regulator performs two important functions.25 - . (3) Fore pressure regulator cannot provide constant sample line flow.1m/sec for water). needle valve is recommended for pressure reduction.2 Flow control Flow control is attained by adjusting flow meter control valve for each analyzer in conjunction with pressure control of section 5.5~2. (2) Back pressure regulator continuously discharges the flow difference between total main sample flow and the sum of flows to analyzers. 1. 5. feeding constant flows and pressure to analyzers and maintaining fixed total sample flow. total transport time etc. 5.5㎏/㎠). However.1.5~1.TRAINING MANUAL FOR SWSS FOR HRSG UNIT ㆍeliminate possible sample bias due to dissociation of water into hydrogen and oxygen that can occur across throttling valves when sampling at high pressures. (1) By maintaining upstream pressure at constant value (0. also have to be taken into account and . 5. (3) For Samples less than 35㎏/㎠.2 Back pressure regulators. 3 Temperature control Temperature of all sample is reduced and controlled at 25℃ because most on-line analyzers require samples to be standard temperature to ensure repeatable and accurate results.3 Once the pressure is established at constant pressure zone. (2) Flow meter for analyzer has manual flow adjust valve as an integral part of the meter.5~1.5㎏/㎠ as described in 5. 5.TRAINING MANUAL FOR SWSS FOR HRSG UNIT compromise has to be made when required.4 Flow meters (1) Flow meters for total flow and flow to each analyzer are required. 1.2.2.3. 5.8℃ of cooling water inlet temperature for water sample and 5. 5.6℃ .26 - . Downstream pressure of the reducer is controlled by back pressure regulator at 0.1 Primary cooler Primary cooler is used to reduce the sample temperature to less than 2. 5. (3) Flow meters are normally rotameter types with visible indicator (4) The rotameter shall be made of materials that are corrosion resistant and not reactive with samples. 5.2.2 The total flow is obtained by adjusting the pressure reducer in flowing condition. flow to each analyzer should be set at rate required by the analyzer by adjusting control valve that is normally an integral part of flow meter. 2. 1 Blowdown valve (1) Blowdown valves are used to purge sample lines that are not in continuous service or where suspended solids deposition affects the sample. For high chlorides in the cooling water.3.3 Material and construction Cooler are normally tube coils in a shell type.27 - .2 Secondary cooler Secondary cooler should be capable of 0. however. (3) Blowdown valve prior to primary cooler may be operated on initial startup of the system or after long period of shutdown of the system to remove any foreign materials and deposits in the . Cooler tube and shell shall be made of stainless steel. But the decision should be based on the capability of secondary cooler and chiller unit.TRAINING MANUAL FOR SWSS FOR HRSG UNIT of the cooling water inlet temperature for steam sample at representative sample flow. preferably SS316 for tubes. primary cooler can be used.4. 5. Alloy 600 is recommended. In general. 5. for sample temperature greater than 80℃.4 Other sampling system components 5.5℃ approach to the chilled water temperature. 5. (2) The blowdown valves can be located either prior to primary cooler or downstream of pressure reducer or at both.3. 4.4 Cooling water valves on sample coolers.TRAINING MANUAL FOR SWSS FOR HRSG UNIT sample transport line. 5. For sample pressure higher than 48㎏/㎠ double isolation valves are recommended. (5) Regulating type valve is used for blowdown valve prior to primary cooler and ball valve for down stream of reducer. Regulating type or ball valve rated for sample pressure and temperature are used. Cooling water flow is adjusted by the outlet valve to give optimum cooling water flow to the cooler and make balance between cooling waters to different coolers from same cooling water source. .4.5 Fitting It is preferable to use bends rather than fittings to change direction of sample tubing.4.28 - . 5. 5.4. 5.2 Isolation valves.3 Sample relief valve Each sample line should be provided with a pressure relieving device to protect components from over-pressurization. (4) Blowdown valve downstream of pressure reducer is operated every time before the sample line is put into operation to flush the cooler and reducer in addition to sample transport line. Spring-loaded type back pressure relief valve is commonly used located downstream of pressure reducer. Each sample cooler should have an inlet isolation valve and outlet throttling valve. 5.6 Sample filters may be installed in the line to trap particles and reduce plugging on downstream components. 5.5. Filters made of stainless steel 316 with mesh size of about 100 is safe enough if filters are to be used. But filters can affect sample analytical results and are not recommended normally.5 Instrumentation and control 5. 5. temperature switches may be installed on final sample line which will trigger alarms and/or divert sample flows to blowdown valves.4. 5. (2) Remote manual method : Pneumatic on-off valves are used enabling manual operation of the valve from control panel.1 In addition to monitoring flows by rotameters.2 To protect components and analyzer sensors from abnormal high temperatures due to failures on coolers. Control of sample valves and blowdown valves can be performed either local-manually.3 Control of sample and blowdown valves.TRAINING MANUAL FOR SWSS FOR HRSG UNIT Compression or socket weld fitting should be selected based on application but compression fittings are preferable. remote-manually or remote automatically.5.29 - . 5. . pressures and temperatures of final samples are monitored either by local indicators or indications on control panel. (1) Local manual method : Opening and closing of valves are done at the valve locations by hand. (3) Automatic operation of valves: In automatic operation. (5) PLC system is commonly used to realize remote and automatic operation in sample conditioning system.TRAINING MANUAL FOR SWSS FOR HRSG UNIT blowndown and sample valves are operated in automatic sequence with the blowndown duration is preset as required. .30 - . The automatic operation of sample lines can be performed individually or in groups. (4) Remote operation of valves can be initiated from control panel of the sample conditioning system or from the main control system (DCS) of the plant. maximum pressure etc.2 Precautions for on-line analysis (1) Proper sample conditioning. Blowdown time to flush six times the total line volume is acceptable. not from any dead leg in the sample conditioning system.5~2.1 m/sec. (2) If sample has not been flowing prior to grab sampling. much longer period of time for flushing (preferably several weeks) by continuous flow is required. (3) The sample velocity in transport line during flushing and sample taking should be maintained at 1. . 6.TRAINING MANUAL FOR SWSS FOR HRSG UNIT 6 Sample Analysis Sample transported to and conditioned at sample conditioning system are either grab sampled and analyzed at plant chemical laboratory or analyzed on-line by analyzers on the sampling system control panel.1 Precautions for grab sampling (1) Samples should be taken from continuously flowing stream. have to be met. flow rate range. blowdown of the sample line has to be performed for enough time to flush and stabilize the line. particularly constant flow and temperature has to be maintained.31 - . But when the system is being started initially or when new tubes or sample coolers are installed. (2) Manufacture’s requirements for sensor operation. 6. present in the sample also has to be compensated for. special cares have to be taken to avoid critical damages to the sensors.3. morpholine.32 - . methods and applications In this section. methods and applications for the analyses being made in NEKA plant are given. especially pH and Dissolved Oxygen. 6. Detailed information on each analysis will be presented in separate class for each analyzer. are out of service or when the sample lines have to be left dry.1 Specific Conductivity (1) A measurement of all ionic species which contributes to the electric conductivity of a solution.3 Analysis definition. 6. (4) When the sensors.TRAINING MANUAL FOR SWSS FOR HRSG UNIT (3) Regular calibration of analyzers according to manufacture’s instructions has to be performed. Instructions of manufacturer’s manual has to be followed. The unique effects of ammonia. (4) Keeping the sample temperature at reference temperature of 25℃ . brief explanations on the definitions. (3) High-purity conductivity analyzer should adopt specialized algorithms to account for the dramatic change in ionization of water with temperature. (2) Unit in normal use is micro Siemens per centimeter(㎲/㎝). which is the reciprocal of the resistance in ohms measured between opposite faces of a cubic centimeter of an aqueous solution referenced to 25℃. etc. (6) Electrical conductivity methods are widely used for monitoring makeup water. where ammonia.2 Cation conductivity (1) A measurement of anionic contamination rather than total ionic species. (2) Removing cation ions will greatly sharpen sensitivity to contamination by removing the masking affects of ammonia. 6. (4) Is useful for detecting the leakage of cooling water into condensate.3. amines and other cationic contaminants are removed.TRAINING MANUAL FOR SWSS FOR HRSG UNIT is very important for accurate measurement of conductivity because the temperature compensation algorithm cannot count for all the effect of varying constituents in the water and the temperature sensor itself could produce erroneous signal. feedwater and condenser leakage for its comparatively little maintenance required. (3) Non-ionized or weakly ionized substances (for ex.3 Dissolved oxygen . Sample is passed through a hydrogen ion exchange resin before conductivity measurement. low cost and high reliability. which are a more conductive than the salts.33 - . SiO2) and hydroxide ions are not measured by this method. thus further increasing sensitivity. amine and convert salts to the corresponding mineral acids. (5) Specific conductivity tends to follow the concentration of pH adjusting agents(usually ammonia). 6.3. Unit is in ㎍/L (ppb). (2) Measured by electrochemical method. 6. (3) Dissolved oxygen measurements is used to detect oxygen inleakage at condensate pump discharge and also to monitor deaerator performance and results of oxygen scavenger (N2H4) injection.4 pH (1) The negative logarithm of concentration or activity of hydrogen ion (-log[H+]). (2) Measured by electrometric instrumental probe method.3. .TRAINING MANUAL FOR SWSS FOR HRSG UNIT (1) Oxygen dissolved/entrained in aqueous media.5 Sodium (1) Alkali metal present in water as cation Na+. The measurements also provide data for the decision of pH control agent injection. 6.34 - .3. (3) pH measurements are made on most of the samples to monitor whether the required pH level for minimizing corrosion of steam/water cycle materials are maintained. (2) Measured by ion-selective electrode method. (3) Sodium measurement is made on samples from condenser extraction pump discharge to detect condenser in-leakage and breakthrough from condenser polisher dimineralizer. Unit is in ㎍/L(ppb). Conditioning and Analysis in the Power Cycle. 1966 (2) Steam and Water Sampling. ASTM D1066-97 .35 - . ASME PTC 19.11-1997 (3) Standard Guide for Equipment for Sampling Water and Steam in Closed Conduits. ASTM D33701999 (5) Standard practice for Sampling Steam. ASTM D1192-98 (4) Standard Practices for Sampling Water from Closed Conduits.TRAINING MANUAL FOR SWSS FOR HRSG UNIT 7 References (1) Power Plant Engineering. by Chapman & Hall.