Such as the ones in LABORATORY or R&D UNITS.
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(2) An ANALYTICAL INSTUMENT is one that measures the quality of a product or stream. It can be classified into two major groups 1.ON LINE ANALYZER (PROCESS ANALYZER), Meant for continuously monitoring the quality of a stream. 2.OFF LINE ANALZER. Such as the ones in LABORATORY or R&D UNITS..
(3) PRODUCT PURITY ANALYZERS Moisture Density PH Conductivity Oxygen Chromatograph Vapour pressure Flash point Pour point. PROCESS OPTIMISATION / FURNACE EFFICIENCY Oxygen CO H2S SO2.
(4) POLLUTION MONITORING CO, CO2 NOX SUSPENDED PERTICLES REALIVE HUMUDITY, AMB. TEMPERATURE WIND SPEED WIND DIRECTION DUST pH DISSOLVED O2. SAFETY CONDITION MONITORING HYDRO CARBON LEAK DETECTORS HYDROGEN SULPHIDE DETECTORS TRACE BENZENE MONSTORS..
(5) Oxygen Measurement.
(6) Zirconia Oxygen Analyzer. At high temperatures the zinconia element, as a solid electrolyte, is a conductor of oxygen ions. Platinum electrodes are attached to the interior and exterior of the zirconia. Heating the element allows different partical oxygen concentrations of the gasses to come into contact with the opposite side of the zirconia creating an oxygen concentration cell..
(7) In other words, oxygen molecules gain electrons to form oxygen ions with higher partial oxygen concentrations. These ions travel through the zirconia element to the other electrode. At that point, electrons are released to form oxygen molecules.
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(9) V Measured voltage K Natural constant T Temperature, is kept constant P1 Partial pressure of reference gas; is constant, if air is used as reference gas and mixture prevented with process gas. C Constant offset 20.9 PERCENTAGE OXYGEN = ------------------------------{( e.m.f.) / [(T + 273)(0.0215)] } e.
(10) Paramagnetic oxygen measurement. Oxygen is one of very few gases with a strong magnetic susceptibility . The movement of the electrons within a molecule generates magnetic moments.
(11) The principle of measurement is based on a sensor in which a dumb-bell comprising two nitrogen-filled spheres is arranged in rotational symmetry within a magnetic field. The gas to be measured passes through the sensor. If the sample gas contains oxygen, the oxygen is drawn into the magnetic field on account of its paramagnetic property, thereby strengthening the field. The nitrogen inside the glass spheres has the opposite magnetic polarization and is forced out of the field, causing the dumb-bell to rotate. The degree of rotation is directly proportional to the oxygen concentration..
(12) pH measurement.
(13) pH is a logarithmic measurement of the number of moles of hydrogen ions (H+) per litre of solution. Thus: 1 moles of hydrogen ions in 1 liter of liquid = 11 pH. 5.3 moles of hydrogen ions in 1 liter of liquid = 5.3 pH.
(14) The electrode, made of a special glass, is called the measurement electrode. It's job it to generate a small voltage proportional to pH (ideally 59.16 mV per pH unit).. The reference electrode uses a porous junction between the measured liquid and a stable, neutral pH buffer solution (usually potassium chloride) to create a zero-voltage electrical connection to the liquid. This provides a point of continuity for a complete circuit..
(15) Conductivity Measurement.
(16) Conductivity is the ability of a material to conduct electric current. The principle by which instruments measure conductivity is simple - two plates are placed in the sample, a potential is applied across the plates (normally a sine wave voltage), and the current is measured. Conductivity (G), the inverse of resistivity (R) is determined from the voltage and current values according to Ohm's law: G = I/R = I (amps) / E (volts). The unit of measurement commonly used is one millionth of a Siemen per centimeter (micro-Siemens per centimeter or µS/cm)..
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(18) Temperature Compensation Temperature plays a role in conductivity. Because ionic activity increases with increasing temperature, conductivity measurements are referenced to 25ºC. The coefficient used to correct for changes in temperature, β is expressed as a percentage per degree Celsius. For most applications, beta has a value of two. In order to establish the true value of beta a solution is measured at the elevated temperature (without temperature compensation). Then the solution is cooled and re-measured. β can then be exactly calculated for that particular solution..
(19) CO, CO2, SO2 MEASURMENT IR ANALYSERS.
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(22) Heteroatomic gases exhibit an unique property that they absorb IR energy. This absorption frequency is different for different gases.
(23) Inside of the Analyzer Module, two equal-energy infrared beams are directed through two parallel optical cells, a flow-through sample cell and a reference cell. The reference cell may be sealed or may contain a continuously flowing reference gas. The infrared radiation is interrupted by a chopper at a frequency of 5 Hz. During analysis, a portion of the infrared radiation is absorbed by the component of interest in the sample. The quantity of infrared radiation that is absorbed is proportional to the component concentration The detector is a "gas microphone" based on the Luft principle. The detector is generally filled with the same gas being analyzed. The infrared energy is therefore absorbed at the same wavelengths in the detector as that in the sample cell, making the detector specific for the analyzed component. The detector converts the difference in energy between sample and reference cells to a capacitance change. This change, which is proportional to component concentration, is processed and expressed as the primary variable on the network.
(24) The IR ANALYZER is based on the principle of IR absorption of a gas.
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(26) H2S Analyser.
(27) The measurement principle is based on the absorption spectrum of hydrogen sulfide (H2S) gas in the UV range. The UV light is generated by a pulsed Xenon lamp guaranteed for 1,000,000,000 flashes, giving a lifetime of many years with continuous operation. H2S is measured directly through a quartz gas flow cell without any converter, eliminating the need for any maintenance or parts replacement. There is no risk of interference with CO2, CH4 or H2O as these gases do not have UV absorption..
(28) SOX ANALYZERS.
(29) Pulsed UV-fluorescence detectors offer an inexpensive and efficient way to measure SO2, and are widely used both in ambient air and flue gases. In these instruments SO2 is electronically excited by the radiation of an UV lamp, yielding an excited species which fluoresces in the UV Sulphur dioxide absorbs light in three primary UV regions. Out of these, the band between 190 nm and 230 nm is best suited for fluorescence measurements. Absorption of ultraviolet radiation at a frequency v1 by SO2 yields an excited species SO2*. SO2* can then release its excess energy by fluorescence at a different wavelength, typically between 240 - 420 nm..
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(33) NOx ANALYZERS.
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(36) NITRIC OXIDE DETERMINATION BY CHEMILUMINESCENCE METHOD The chemiluminescence method for detection of nitric oxide (NO) is based on its reaction with ozone (O3) to produce nitrogen dioxide (NO2) and oxygen (O2). The nitrogen dioxide molecules thus produced are initially in an electronically excited state (NO2*). These revert immediately to the ground state, with emission of photons. This gives out a light emission between 590 – 2750 nm. The reactions involved are: NO + O3 → NO2* + O2 NO2* → NO2 + hv where h = Planck's constant v = frequency, Hz As NO and O3 mix in the reaction chamber, the chemiluminescence reaction produces light emission that is directly proportional to the concentration of NO. This emission is measured by a photomultiplier tube and associated electronic circuitry..
(37) NOX DETERMINATION The NOx determination is identical to the NO determination except that, prior to entry into the reaction chamber, the sample is routed through a molybenum converter where the NO2 component is converted into NO. The reaction is: 2NO2 → 2NO + O2 Instrument response is proportional to total NO in the converted sample, that is, to the sum of the NO originally present in the sample plus the NO resulting from conversion of NO2. This sum of NO and NO2 is commonly termed NOx, i.e., ([NOx] = [NO] + [NO2])..
(38) OZONE GENERATION Ozone for the chemiluminescence reaction is produced in a flow chamber where a stream of air or oxygen from an external cylinder is exposed to ultraviolet radiation from a source lamp. The reaction is: hv 3O2 → 2O3.
(39) NO2 to NO converter.
(40) GAS CHROMATOGRAPHY.
(41) chromatography (GC), is a common type of chromatography used in organic chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, or separating the different components of a mixture (the relative amounts of such components can also be determined)..
(42) When a gas or vapour comes in contact with an adsorbent, certain amount of it get adsorbed on the solid surface. This takes place according to a phenomenon called Langmuir phenomenon given by x/m = k1c+k2c where k1,k2 are constants x = mass of gas or vapour adsorbed m = mass of adsorbent c = vapour concentration in gas phase.
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(44) In gas chromatography, the moving phase is a carrier gas, usually an inert gas such as helium or a non reactive gas such as nitrogen. The stationary phase is a microscopic layer of liquid or polymer on an inert solid support, inside a piece of glass or metal tubing called a column. The instrument used to perform gas chromatography is called a gas chromatograph.. The gaseous compounds being analyzed interact with the walls of the column, which is coated with different stationary phases. Separation occurs as a result of the adsorption process, or adhesion of the molecules in an extremely thin layer on the stationary phase. This causes each compound to elute at a different time, known as the retention time of the compound.. A number of detectors are used in gas chromatography. The most common are the flame ionization detector (FID) and the thermal conductivity detector (TCD).
(45) Flame Ionization Detectors.
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(47) When a hydrocarbon sample passes through a hydrogen flame, the molecular structure is altered so that the bond is broken and the carbon atom becomes a negatively charged and the hydrogen atoms become positively charged. When placed in an electric field, the ions may be collected. This current may be converted to a voltage for further processing. The hydrogen/air mixture that supports the flame is converted to water and exits the burner through the vent. Most of the oxygen is consumed by the flame with only small amounts of excess hydrogen remaining. The excess hydrogen (H2) passes through the flame to the vent without being ionized. The only ionization that occurs is with the hydrocarbon samples. By placing the burner tip within the effective electric field, all positive ions will be collected and measured by the measuring circuit. All negative Ions will be attracted to the positive polarizing plate. In a chromatograph system, each component to be measured is separated so that there is no interference between components..
(48) Thermal Conductivity Detector. When an analyte elutes and the thermal conductivity of the column effluent is reduced, the filament heats up and changes resistance. This resistance change is often sensed by a Wheatstone bridge circuit which produces a measurable voltage change. The column effluent flows over one of the resistors while the reference flow is over a second resistor in the four-resistor circuit..
(49) R1. R3. measure. U. Uo R2. compensation. R4.
(50) Viscosity meter.
(51) For an ideal gas in the isothermal case, where the temperature of the fluid is permitted to equilibrate with its surroundings, and when the pressure difference between ends of the pipe is small, the volumetric flow rate at the pipe outlet is given by. where: Pi inlet pressure Po outlet pressure L is the length of tube η is the viscosity R is the radius.
(52) The relationship between the various properties and physical dimensions of the capillaries, at constant temperature is given approximately by the Hagan-Poseuille equation.. η. =. 1.45 X 10 ^ 5 X d ^ 4 P -------------------------------QL. = = = = =. absolute viscosity, centipoises capillary bore in mm capillary length in mm sample flow in mm/minute differential pressure across capillary in bar. Where. η. d L Q P. NOTE : For a single capillary where flow rate is 60.7 ml/min, this equation simplified to : 2.4 X 10 ^ 3 X d ^ 4 P η = -----------------------------L.
(53) A precision metering pump driven by a synchronous motor passes a sample of the process stream continuously through as capillary restriction at a constant flow rate and constant temperature. The pressure drop across the restriction is measured by a differential pressure transmitter and is directly proportional to absolute viscosity (centipoises)..
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(55) A filtered sample slipstream is pulled into the microprocessor controlled heat exchanger oil bath which brings the sample temperature to the specified measuring temperature. An AC synchronous motor and dual precision pumping system simultaneously raises the sample pressure to a preset limit and pushes a small portion of this sample through a capillary restriction where the pressure is measured at both ends. This pressure differential is recorded by the instrument and a corresponding absolute viscosity is output. NOTE : For a single capillary where flow rate is 60.7 ml/min, this equation simplified to :. η. =. 2.4 X 10 ^ 3 X d ^ 4 P -----------------------------L.
(56) Mass flow / Density meter.
(57) The mass flow of a u-shaped coriolis flow meter is given as:. where Ku is the temperature dependent stiffness of the tube, K a shape-dependent factor, d the width, τ the time lag, ω the vibration frequency Iu the inertia of the tube..
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(60) When there is a flow, there is some twisting of the tubes. The arm through which fluid flows away from the axis of rotation must exert a force on the fluid to increase its angular momentum, so it is lagging behind the overall vibration. The arm through which fluid is pushed back towards the axis of rotation must exert a force on the fluid to decrease the fluid's angular momentum again, hence that arm leads the overall vibration. The inlet arm and the outlet arm vibrate with the same frequency as the overall vibration, but when there is mass flow the two vibrations are out of sync, the inlet arm is behind, the outlet arm is ahead. The two vibrations are shifted in phase with respect to each other, and the degree of phase-shift is a measure for the amount of mass that is flowing through the tubes..
(61) Hydro Carbon Analyser.
(62) Hydrocarbon Analyzer utilizes the flame ionization method of detection. The sensor is a burner in which a regulated flow of sample gas passes through a flame sustained by regulated flows of air and a fuel gas (hydrogen or a hydrogen/diluent mixture). Within the flame, the hydrocarbon components of the sample stream undergo a complex ionization that produces electrons and positive ions. Polarized electrodes collect these ions, causing current to flow through electronic measuring circuitry. Current flow is proportional to the rate at which carbon atoms enter the burner. Principle components of the burner are the manifold, burner jet, and the collector Streams of sample, fuel and air delivered by the analyzer flow system are routed through internal passages in the manifold and into the interior of the burner. Here the sample and fuel pass through the burner jet and into the flame; the air stream flows around the periphery of the flame. The burner jet and the collector function as electrodes. The jet is connected to the positive terminal of the 90 VDC polarizing voltage. The collector is connected to the signal amplifier. The two polarized electrodes establish an electrostatic field in the vicinity of the flame. The field causes the charged particles formed during combustion to migrate. Electrons go to the burner jet; positive ions go to the collector. Thus a small ionization current flows between the two electrodes. Magnitude of the current depends on the concentration of carbon atoms in the sample. The burner current serves as the input signal to the electronic measuring circuitry..
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(64) SPM Analyser.
(65) Suspended Particulate Matter. The sum of all solid and liquid particles suspended in air, many of which are hazardous.
(66) Respirable Suspended Particulate Matter. The Respirable Suspended Particulate Matter is an air-borne particle, which is smaller than 4 to 5 microns cannot be stopped in the nasal tract as a result it will enter into the lungs and can causes various diseases like discomfort and sneezing to Asthma, migraine, Cancer, Heart Attacks. Normally new borne baby is more effective from the Respirable Suspended Particulate Matter.
(67) Optical opacity /dust monitor. A light beam sent through a mixture of gas and particles is attenuated by absorption and diffusion. The more particles are found in the light beam, the stronger the opacity. The ratio of received light to initial light is a measurement of the transmission or the reciprocal opacity..
(68) Basic Concepts – small solid or liquid particles suspended in gas. •. Dust from nature, wind, human activity. (pollen, road dust fly ash). •. Fog from heating/cooling. (clouds and fog). •. Mist from atomization and nebulizer. (sulfuric acid mist). •. Spray from ultrasonic's. (insecticide spray). •. Smoke from combustion or flame. (cigarette, soot, diesel). •. Smog from Sun light. (Urban Smog).
(69) 10. Relative Concentration. TSP. 8 PM 0.1. PM 2.5. PM 10. 6. Carbon. Sulfate, Nitrate, Ammonium, Organic & Elemental Carbon, Heavy Metals, Clays. Ultrafine. Accumulation. 4. 2. 0 0.01. 0.1. 1. Geological Material, Pollen. Coarse. 10. Particle Aerodynamic Diameter (µm). 100.
(70) Basic Concepts Common Gravimetric Ambient Aerosol Sampling Techniques (Gross - Tare) / Air Volume = µg/m3. Sampling Techniques •. Light Scattering, Absorption, and Extinction. •. Beta (Electron) Attenuation.
(71) Optical Type.
(72) The device operates using the double-pass method according to the autocollimation principle. The light beam traverses the measuring distance twice. The light beam looses intensity proportionally to the particle concentration in the area. The attenuation of the light beam by the dust content in the measuring section is measured and evaluated..
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(74) Beta attenuation Type.
(75) • Constant flow of aerosol is metered and sampled onto a filter stain area. • The continuous detection of Beta Attenuation is proportional to increased mass. • Every 12-24 hrs a new filter area is zeroed and introduced..
(76) At the beginning of the sampling period, beta ray transmission is measured across a clean section of filter tape. This section of filter tape is then mechanically advanced to the sampling inlet. Particulate matter is then drawn into the sample inlet and deposited on the filter paper. At the completion of the sampling period, the filter tape is returned to its original location and the beta ray transmission is re-measured. The difference between the two measurements is used to determine, with exceptional accuracy, the particulate concentration. The mass density is measured using the technique of beta attenuation. A small 14C beta source (60 μCi) is coupled to a sensitive detector that counts the emitted beta particles. The filter tape is placed between the beta source and the detector. As the mass deposited on the filter tape increases, the measured beta particle count is reduced according to a known equation..
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(79) LEL Detector.
(80) The explosive limit of a gas or a vapor is the limiting concentration that is needed for the gas to ignite and explode. or The lowest concentration (percentage) of a gas or a vapor in air capable of producing a flash of fire in presence of an ignition source (arch, flame, heat)..
(81) At concentration in air below the LEL there is not fuel to continue an explosion. Concentrations lower than LEL are "too lean" to burn. eg: Methane gas has a LEL of 4.4% by volume. If the atmosphere has less that 4.4% methane, an explosion cannot occur even if a source of ignition is present. When methane(CH4)concentration reaches 5% an explosion can occur if there is an ignition source. Each combustible gas has its own LEL concentration. Flammability limits of mixtures of several combustible gases can be calculated using Le Chatelier's mixing rule for combustible volume fractions xi:.
(82) The solid state sensor utilizes a sintered tin dioxide element. When the sensor is heated to a high temperature (typically 400º C), free electrons flow easily when no oxygen is present. In clean air, oxygen is absorbed onto the element surface providing a restriction to the electron flow and therefore increasing the electrical resistance of the element. As the sensor is exposed to the target gas, the tin dioxide element absorbs molecules of the target gas causing oxidation in the process. This oxidation reduces the resistance of the element in a known and repeatable manner. The controller electronics measures this change in resistance and indicate as LEL %..
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(84) Moisture Analyser.
(85) Theory of Operation in Gases and Liquids The direct measurement of water vapor pressure is accomplished easily and effectively in gases by the aluminum oxide moisture sensor. The sensor consists of an aluminum strip that is anodized by a special process to provide a porous oxide layer over which a very thin coating of gold is evaporated. The aluminum base and the gold layer form the two electrodes of what is essentially an aluminum oxide capacitor. Water vapor is rapidly transported through the gold layer and equilibrates on the pore walls of the oxide layer. The number of water molecules absorbed on the oxide structure determines the conductivity of the pore walls. Each value of pore wall resistance provides a distinct value of electrical impedance, which in turn is functionally related to the water vapor pressure. This functional relationship holds for measurements made in either gas phase or liquid phase.
(86) Aluminum strip. Porous oxide layer. Gold layer electrodes. To Electronics.
(87) AMBIENT AIR QUALITY STANDARDS (NATIONAL) – INDIA Concentration in ambient air Residenti al, Rural Industrial & other Sensitive Areas Areas Time- weighted average Areas Method of Measurement. Pollutants. 3. 3. Annual Average*. 80 µg/m. Sulphur Dioxide (SO2). 24 hours**. 120 µg/m 80 µg/m. Oxides of Nitrogen as NO2. Annual Average*. 80 µg/m. 24 hours**. Suspended Particulate Annual Average* Matter (SPM) 24 hours** Respirable Particulate Matter (RPM) (size less than 10 microns). Lead (Pb). Annual Average*. 30 µg/m. 15 µg/m3. - Ultraviolet Fluorescence - Jacob & Hochheiser Modified (NaArsenite) Method. 3. 30 µg/m. - Gas Phase Chemiluminescense. 3. 3. 3. 3. 3. 3. 360 µg/m 140 µg/m 70 µg/m. 3. Annual Average*. 1.0 µg/m. 24 hours** 8 hours**. 3. - High Volume Sampling, (Average. 500 µg/m 200 µg/m 100 µg/m flow rate not less than 1.1 m3/minute) - Respirable particulate matter 3 3 3 120 µg/m 60 µg/m 50 µg/m sampler 3 3 150 µg/m 100 µg/m 75 µg/m 0.75 0.50. Annual Average*. Carbon Monoxide (CO) 1 hour. 60 µg/m. 120 µg/m3 80 µg/m. - Improved West and Geake Method. 3. 3. 3. 3. 15 µg/m3. 24 hours**. 24 hours**. Ammonia1. 3. 60 µg/m. 3. 3. 1.5 µg/m. µg/m3 0.75. µg/m3 1.00 3. µg/m. 3. µg/m. - ASS Method after sampling using EPM 2000 or equivalent Filter paper. 3 0.1 mg/m 0.1 mg/m 0.1 mg/m 3. 3. -. 3 3 0.4 mg/m3 0.4 mg/m 0.4 mg/m -. 3 3 5.0 mg/m3 2.0 mg/m 1.0 mg/m 10.0 - Non Dispersive Infra Red (NDIR) 3 3 3 mg/m 4.0 mg/m 2.0 mg/m Spectroscopy.
(88) Question time Email id. -. kowtham@yahoo.com.
(89) Thank You.
(90)
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