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27-572: SWAS may become: Steam and water analysis system Submillimeter Wave Astronomy Satellite Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title SWAS . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=SWAS&oldid=1195189680 " Category : Disambiguation pages Hidden categories: Short description

54-499: A fully or partially closed design, depending on the choice of the user, the environment it is supposed to operate in & the criticality of operation. In the sampling system, sample coolers play a major role in bringing down the temperature of hot steam (or water) to a temperature acceptable to the sensors of the on-line analyser. Some of the important design aspects of sample coolers are: These sample coolers handle very high pressure and Temperature steam and Water samples and thus it

81-521: A source of feed water alkalinity has well known advantages e.g. : a)        It prevents foaming and carryovers from boiler. b)        It minimizes deposits on metal surfaces. c) Reduce Dissolved oxygen corrosion In addition to its oxygen-scavenging function, hydrazine helps to maintain a protective magnetite layer over steel surfaces, and maintain feed water alkalinity to prevent acidic corrosion.  The nominal dosage rate for hydrazine in feed water

108-465: Is a difference between these three types of measurements. pH measurement is also very basic yet very critical measurement for steam and water cycle. Monitoring the pH value of the feed water gives direct indication of alkalinity or acidity of this water.  The ultra pure water has pH value of 7.  In steam circuit it is normal practice to keep the pH value of feed water at slightly alkaline levels using chemical dosing.  This helps in preventing

135-425: Is a double helix coil in shell type design providing contraflow heat exchange. The remaining part of cooling (i.e. from 35 to 25 °C) is achieved by using chilled water in the secondary cooling circuit. A chilled water supply is required from the plant or else an independent chiller package can be considered for this purpose along with SWAS. The sampling system can be an 'open-frame free standing' type design or

162-473: Is about three times its oxygen level.  Under dosing of hydrazine leads to increased corrosion; overdosing represents a costly waste.  Monitoring the dissolved oxygen levels is not sufficient to control the optimum concentration because its provides no measure of any excess hydrazine. The typical points in steam circuit where hydrazine monitoring is required are .  Re-heaters, Economizer inlet, L.P. heaters. When it comes to safety and efficiency of

189-613: Is almost close to zero(as low as 0.05 microsiemens/cm), while with addition of even 1 ppm of any salt, the conductivity can shoot up to even more than 100 micro siemens/cm.  Thus conductivity is a very good general purpose watch dog which can give a quick indication of plant malfunctioning or possible leakages.   Typical points in the steam circuit where conductivity should be monitored are . Drum steam, Drum water, High pressure heaters, Low pressure heaters, Condenser, Plant effluent, D.M. plant, Make-up water to D.M. plant. Three types of conductivity measurement are usually done: There

216-417: Is also called Analyser Panel , Dry Panel or Dry Rack . It is usually a free-standing enclosed panel. The system contains the transmitter electronics, usually it is mounted on panels. In this system stage, sample is analyzed on its conductivity , pH , silica , phosphate , chloride , dissolved oxygen , hydrazine , sodium etc. [1] In Steam and Water Cycle conductivity measurement is very basic, but

243-541: Is also called sampling system , Wet Panel or Wet Rack . This is intended to house various components for sample conditioning. This may be an open rack or a closed enclosure with a corridor in between. The system contains sample conditioning equipment and a grab sampling sink. In this system stage, sample is first cooled in Sample Coolers, depressurized in Pressure Regulator and then fed to various analyzers while

270-688: Is an important aspect. It is very important that the sample meets least resistance. Hence joints and bends in the pipeline need to be minimal. Also, sample lines must be continuously sloping to avoid accumulation of samples in lines. (2) Line Material: Minimum Stainless steel SS316 Grade material must be used for sample Transport Lines. This is to avoid corrosion of lines which leads to wrong measurement and analysis. For High pressure and Temperature samples (Super heated steam, Reheated Steam, Saturated Steam, Separator drains, Feed water at Economizer inlets) SS316H must be used which withstand High Temperature of samples. Sample conditioning system in some countries

297-558: Is considered to be the most reliable and safe device. Single Rod in Tube System is a system in itself that takes care of some important aspects of sample conditioning. The pressure reducer in the Sampling system is rated for high very high pressure 450 Bar. There is no need of filters before the Rod in tube Pressure Reducers, as cleaning is on-line, without using any tools. For maintenance, no-shut-down

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324-408: Is different from Wikidata All article disambiguation pages All disambiguation pages Steam and water analysis system Corrosion and erosion are major concerns in thermal power plants operating on steam. The steam reaching the turbines need to be ultra-pure and hence needs to be monitored for its quality. A well designed Steam and Water Analysis system (SWAS) can help in monitoring

351-956: Is required for cleaning these pressure reducer. Analyzers must be protected from high temperature samples. This is to avoid situations in case of failure of cooling water to primary sample coolers. There are various methods for stopping sample to analyzer in such a situation. The most popular and simple method is use of mechanical thermal shut off valves. These valves close and block samples to analyzer in case of cooling water failures. These valves must be with: (1) High pressure rating and designed inline with ASME standards to assure safety of operator and instruments downstream. (2) This valves must be with MANUAL RESET design as recommended in ASME PTC 19.11-2008 standards. (3) These valves must be equipped with potential free alarm contact for operator indication in Control system. A sample analysis system in some countries

378-597: Is very important and critical to monitor and control Dissolved oxygen and pH values in Feed water systems. The typical points in steam circuit where dissolved oxygen monitoring is required are . Condenser outlet, L.P. heaters, Economizer inlet. In All Volatile Treatment-Reducing (AVT-R) treatment chemicals Like Hydrazine/ Carbohydrazine or DEHA are dosed in Boiler feed water. Such treatments are used for Steam water circuits with mixed metallurgy. These Chemicals act as an oxygen scavenger and

405-400: Is very important to design these Helical Tube Heat Exchangers inline with Pressure vessel standards These are unfired pressure vessels and thus designed inline with ASME Section VIII Div 1&2, Pressure Equipment Directives (PED) Standards. Also many countries asked for local certification like After the sample is cooled, the pressure of the sample must be reduced to meet the requirement of

432-500: The Properties of Water and Steam ( IAPWS ) also gives good information on important measurement points and its significance. Sample handling system components are the most important pressure parts of sample handling system and need to have certification from ASME Section VIII Div1 & Div2 or PED. Also many times country-specific certifications required like To ensure that the sample that is going to be extracted for analysis represents

459-422: The analyzers today, it is a practice to cool the sample to 25–40 °C. with the help of a well engineered sample conditioning system and then feed the conditioned sample to the analyzers. However, if an uncompensated sample is to be analyzed, it becomes essential to cool the sample to 25 °C +/- 1 °C. This can be achieved by two-stage cooling. In the first stage cooling (also known as 'primary cooling'),

486-1164: The corrosion of pipe work and other equipment.   Typical points in the steam circuit where pH should be monitored are : Drum water, High pressure heaters, Make-up condensate, Plant effluent, Condenser, Cooling water. In Steam and Water Circuit temperature of water is increased from room temperature to superheated steam temperatures. In temperature range of 200to 250°C (feed water), dissolved oxygen causes corrosion of components and piping. Iron reacts with dissolved oxygen in feed water circuit resulting pitting may eventually cause puncturing and failures of Parts in Steam water circuits. Parts like condensers, Low Pressure Heaters (LPH), Feed water tanks, High pressure Heaters and Economizers need to be protected from dissolved oxygen attack. Dissolved oxygen also promotes electrolytic action between dissimilar metals causing corrosion and leakage at joints and gaskets. In power plants various feed water treatments like (1) All Volatile Treatment (AVT-R or AVT-O) (2) Oxygenated Treatment (OT) (3) Combine Water Treatment (CWT) are adopted to minimize corrosion. Thus it

513-475: The critical parameters in the steam. These parameters include pH, conductivity, silica, sodium, dissolved oxygen, phosphate and chlorides. A well designed SWAS must ensure that the sample is representative until the point of analysis. To achieve this, it is important to take care of the following aspects of the sample: These aspects are well explained in international standards like ASME PTC 19.11-2008 and VGB S006 -00 2012_09_EN . The International Association for

540-415: The flow characteristics is kept constant by means of Back Pressure Regulator. The need to condition the sample exists, because the sensors used for online analysis are not able to handle the water/steam sample at high temperatures or pressures. To maintain a common reference of analysis, the sample analysis should be done at 25 °C. However, due to temperature compensation logic being available in most of

567-499: The most important measurement. Specific conductivity (total conductivity), acidic conductivity (conductivity after cation exchanger CACE) and degassed cation conductivity are measured at different location in steam and water cycle continuously Conductivity measurements give indication of contamination of water / steam with any kind of salts.  These salts can get added to the water / steam from atmosphere or due to leakages in heat exchangers etc.  The conductivity of ultra pure water

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594-456: The process conditions exactly, it is important to choose the correct sample extraction probe. The validity of the analysis is largely dependent on the sample being truly representative. As the probe is going to be directly attached to the process pipe work, it may have to withstand severe conditions. For most applications, the sample probe is manufactured to the stringent codes applicable to high-pressure, high-temperature pipework. The selection of

621-420: The right type of probe is a challenge. Its use depends on the process stream parameter to be measured, the required sample flow rate and the location of the sampling point (which is also called the 'tapping point'). An important aspect of the sample extraction probe design is that the steam must enter the probe at the same velocity as the steam flowing in the pipeline from where the sample (it can be steam or water)

648-411: The sample is cooled by using available cooling water. In most of the countries, cooling water is available in the range of 30–32 °C. This cooling water can cool the sample unto 35 °C(considering an approach temperature of 3 to 5 °C). A sample cooler is used to achieve this. Sample cooler is a heat exchanger specially designed for SWAS applications. Preferred sample cooler for primary cooling

675-466: The sensors that receive this sample. Usually, the sensors like pH, conductivity, silica, sodium, and hydrazine require low pressure sample for healthy operation. A rod-in-tube type of pressure reducer is the most effective method of pressure reduction recommended in ASME PTC19.11-2008 standard. As per the latest technology, a Sample rod-in-tube pressure reducer with thermal and safety relief valve device

702-473: The steam turbine and boiler in a power plant, silica becomes one of the most critical factors to be monitored. Deposition of various impurities on turbine blades has been identified as one of the most common problems. Various compounds deposit on the turbine blades. Of all these compounds, silica (SiO2) deposits can occur at lower operating pressures also, Therefore, silica deposition is quite common in turbines than other types of deposits. Silica usually deposits in

729-1058: Was extracted. These probes are designed as per ASTM D1066 standard for steam extraction and must be designed and tested for their structural integrity in High pressure, High Temperature and Higher velocity of samples. Sample extraction probes are extremely important and necessary of proper analysis of suspended impurities like Corrosion products, Total Iron, copper, carryover effects. Section#4 in ASME PTC 19.11-2008 standard describes details for designing of sample transportation lines. Following care need to take while designing of this sample transportation lines: (1) Line Size Selection: Following aspects are very important while designing of sample Transportation lines. (a) Transportation time i.e. (Velocity) of sample from Isokinetic sample extraction probes to sampling system should be as minimum. SWAS room must be located close to low pressure water (condensate) samples from CEP discharge and condensate Polishing plants with lesser velocities. (b) Pressure drops in lines

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