WO2022063381A1 - Analyseur thermoacoustique de gaz de combustion - Google Patents

Analyseur thermoacoustique de gaz de combustion Download PDF

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Publication number
WO2022063381A1
WO2022063381A1 PCT/EG2020/000029 EG2020000029W WO2022063381A1 WO 2022063381 A1 WO2022063381 A1 WO 2022063381A1 EG 2020000029 W EG2020000029 W EG 2020000029W WO 2022063381 A1 WO2022063381 A1 WO 2022063381A1
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WO
WIPO (PCT)
Prior art keywords
gas
flue
stack
hot
thermoacoustic
Prior art date
Application number
PCT/EG2020/000029
Other languages
English (en)
Inventor
Ahmed Ibrahim ABD EL-RAHMAN
Mohamed Aziz Youssef Mohamed MOUSA
Hindawi Salem Mohamed SALEH
Original Assignee
Abd El Rahman Ahmed Ibrahim
Mousa Mohamed Aziz Youssef Mohamed
Saleh Hindawi Salem Mohamed
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Abd El Rahman Ahmed Ibrahim, Mousa Mohamed Aziz Youssef Mohamed, Saleh Hindawi Salem Mohamed filed Critical Abd El Rahman Ahmed Ibrahim
Priority to PCT/EG2020/000029 priority Critical patent/WO2022063381A1/fr
Publication of WO2022063381A1 publication Critical patent/WO2022063381A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/02—Analysing fluids
    • G01N29/036—Analysing fluids by measuring frequency or resonance of acoustic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/021—Gases
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/028—Material parameters
    • G01N2291/02809—Concentration of a compound, e.g. measured by a surface mass change

Definitions

  • Flue gas analyzers are measurement instruments that can detect and characterize the composition of gas emissions produced during the combustion processes of fossil fuels. These devices further allow the specification of the corresponding air-to-fuel ratios and the determination of whether they fall within the proper limits for maximum heat output and optimal combustion.
  • a typical flue gas essentially contains carbon dioxide (CO 2 ), carbon monoxide (CO), oxygen (O 2 ) and nitrogen (N 2 ), besides minor traces of unburned Hydrocarbons (HCs), nitrogen oxides (NO x ) and sulfur dioxide
  • Electrochemical devices are however based on the oxidation of a target gas at a certain electrode, which results in the circulation of an electric current, within the electrode cell, in proportion with the percent of gas concentration. These sensors are generally compact, consume lesser amount of energy and possess good sensitivity and relatively fast response. However, they suffer from remarkable drift effects besides low overall lifetimes.
  • NDIR sensors are spectroscopic sensors that are often used to measure the concentration of carbon monoxide in a certain gas mixture through the calibration of its characteristic absorption of particular wavelengths in response to an emitted infrared light. Although reliable and stable, these infrared sensors are rather expensive, necessitate frequent calibration and their usage is mostly limited to heating, ventilation and air-conditioning applications besides the internal combustion engines.
  • the present invention is a fluc-gas analyzer that relies in its operation on the thcrmoacoustic technology.
  • low-GWP thermoacoustic engines are becoming much more reliable and offer attractive and promising path to convert available waste heat at modest temperatures into acoustic power to generate electricity at relatively high efficiency and low cost.
  • These systems are designed to be thermo-acoustical ly unstable such that spontaneous thermofluid interactions between the operating gas and the solid walls of a porous media, referred to as the stack, are taking place within an acoustic, mostly cylindrical, resonator.
  • the present standing-wave thcrmoacoustic flue-gas analyzer enables the detection of the four main flue-gas components; namely, the CO 2 , the CO, the O 2 and the N 2 gases, typically produced in different fossil-fuel combustion processes.
  • the present device particularly allows for the determination of the combustion efficiencies in many industrial applications through accurate specification of the different gas concentrations while building on the basic principles of thermoacoustics and exploiting the state-of-the-art knowledge of thermoacoustic technology.
  • This new sensor offers a simple, reliable and relatively inexpensive alternative to existing flue-gas analyzers, that helps assess the thermal performance of different fossil-fuel-based energy systems.
  • a standing-wave thermoacoustic engine mainly consists of a cylindrical duct 'resonator' that is filled with the working gas.
  • a porous ceramic material 'stack' is carefully positioned within the resonator, as sketched in Fig. 1 , while being heated from one side using an electric heater or preferably a waste-heat source and cooled from the other side through a cold heat exchanger. This helps maintain a nearly uniform temperature gradient along the stack plates.
  • the stack porosity in a standing-wave engine is consistently chosen such that the spacing between the stack solid walls is approximately 3-4 times the gas thermal penetration depth where a and ⁇ represent the gas thermal diffuisivity and the angular frequency, respectively. While interacting thermally with the stack walls, the temperature gradient of the gas particles within the stack increases gradually till reaching a certain specific limit known as the critical 'onset' temperature gradient ⁇ T crit at which the system becomes thermo-acoustical ly unstable and gas-particles oscillations are encouraged inside the resonator.
  • the present resonator is assumed to be filled with a dry mixture of exhaust gases, which are produced -for instance, from water tube boilers- at steam power plants and contain the four main combustion products, namely the O 2 , N 2 , CO 2 and CO gases with negligible traces of nitrogen and sulfur oxides.
  • the gas mixture has a temperature T H that falls in the range from 500 to 900 degrees Celsius based on the particular application.
  • the critical temperature gradient ⁇ T crit becomes a function of the effective specific heat ratio ⁇ mix for the flue gas mixture.
  • the introduced exhaust gases are allowed to reject their heal content into ambient within the cold duct of the acoustic resonator through the cold heat exchanger sketched in Fig. 1 while the hot duct is insulated to help maintain the initial gas temperature together with the heating coil.
  • the temperature difference between the stack ends increases gradually upon cooling its cold end. It is not until nearly all gas particles within the stack pores are subjected to the critical temperature gradient of Eq. 2, that consistent and continuous oscillations of the gas particles are evident.
  • the generated acoustic wave has a well-defined fundamental resonant frequency ⁇ that varies with the resonator length L, the mean temperature of the entire resonator, the specific heat ratio ⁇ mix and the molecular weight M mix of the flue-gas mixture.
  • the specific heat ratio is evaluated at the mean temperature.
  • the usefulness of the present technique for flue-gas analysis depends on the accuracy with which the onset temperature difference between the stack ends and the resonant frequency ⁇ of the self-sustainable acoustic oscillations can be determined.
  • thermoacoustic flue-gas analyzer In the design process of the present thermoacoustic flue-gas analyzer, the engine is constrained to operate at low ranges of onset-temperature-difference to help reduce the non-trivial cooling load.
  • the preliminary analysis reveals a trade-off between and the engine sensitivity with respect to different flue-gas mixtures.
  • the resulting ternary plot shown in Fig. 2 is generic in the sense that it imposes no limits on either or
  • the three axes are clearly extended to include up to 100% of the respective mole fractions using an incremental step of 1% along each axis.
  • the relative concentrations of the exhausted combustion products are rather limited because of the introduced air-to-fuel ratio. This restricts the CO 2 -content in flue-gas mixtures mostly to less than 25%, as indicated by the gray-shaded area in Fig. 3.
  • the present ternary diagram can be employed for general artificial gas mixtures having arbitrary CO 2 concentration as well as particular fluc-gas mixtures with limited CO 2 content.
  • the introduced air-fuel mixtures along the red path become progressively richer such that they have insufficient oxygen to bum all the fuel.
  • the air-fuel mixtures become increasingly leaner with a rather abundant oxygen.
  • the present calculations indicate that the combustion of rich mixtures produce a continuous increase in ⁇ CO along with a consistent decrease in whereas, the concentration results for lean mixtures show a rapid increase in along with a faster drop in as shown in Figs. 5 and 6.
  • the figures also illustrate the potential domains of gas concentrations for either CO 2 , CO or O 2 as comprised between the respective rich-mixture (red) and lean-mixture (blue) concentration results. Approximately, the onset temperature difference ranges from 168 to 179.5°C, while the resonant frequency ranges from 317 to 326Hz.
  • ⁇ CO values are mostly ⁇ 5%, which consequently limits the corresponding domains of interest of CO 2 and O 2 , as gray-shaded in Figs. 5 and 6.
  • the figures also show how sensitive the concentrations of different gases are to the induced ⁇ T crit and ⁇ , respectively, considering CH 4 .
  • the present analysis reveals relative increases In both and ⁇ CO at respective rates of 0.6% and 4%, against a relative decrease in at a rate of 6.7%, per unit shift in ⁇ .
  • the frequency being held constant at 320Hz
  • the results show consistent decreases in both and ⁇ CO at corresponding rates of 1.9% and 2.2%, respectively, against a relative increase in at a rate of 6.4% per unit shift in ⁇ T crit .
  • Figure (1) represents a schematic drawing of the standing-wave thermoaco.uslic flue-gas analyzer.
  • Fig.1 represents the body of the device, a tube made of stainless steel with both ends closed and sealed.
  • Number (2) in Fig.1 represents a stack of thermally non-conducting porous media.
  • Number (3) in Fig.1 represents an electric heater that maintains the stack hot-end temperature.
  • Number (4) in Fig.] represents a cooling coil that cools the stack cold end.
  • Number (5) in Fig.1 represents a sealed nut to keep the device closed.
  • Number (6) in Fig.1 represents a controlled inlet valve to allow for introducing the hot flue gas sample.
  • Number (7) in Fig.1 represents a filler at the inlet passage to filter the introduced hot flue gas sample.
  • Number (8) in Fig.1 represents a check valve to prevent the return of air to the analyzer.
  • Number (9) in Fig.1 represents a vacuum pump to pull the air from the tube and allow for sucking a pure flue gas sample.
  • Fig.1 Number (10) in Fig.1 represents two thermocouples to measure the temperatures of the hot and cold ends of the stack.
  • Number (11) in Fig.1 represents a pressure sensor to measure the gas-particle oscillations of the generated acoustic wave.
  • Numbers (12) and (13) in Fig.1 represent an amplifier and DAQ to process the wave frequency, and stack ends temperatures signals.
  • Fig.1 represents a display to show the molar concentrations of the quaternary-gas components (CO 2 , CO, O 2 , and N 2 ) of the introduced samples.
  • Figure (2) represents a ternary diagram that helps determine the relative concentrations of CO 2 , O 2 , and the combined concentration of CO and N 2 within arbitrary gas mixtures following the intersections of both ⁇ (solid) and ⁇ T crit (dashed) lines.
  • the gray area in the bottom-right corner refers to the ranges of typical flue-gas compositions.
  • Figure (3) represents an enlarged figure of the gray area in the bottom-right comer in Fig. 1 that refers to the expected operational conditions of the proposed thermoacoustic flue-gas analyzer.
  • Figure (4) represents the ranges of typical flue-gas compositions in case of using natural gas (CH 4 ) in combustion.
  • the black dots refer to mole fractions of flue-gas species resulting from complete combustion.

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

Des analyseurs de gaz de combustion, tels que ceux fondés sur des cellules électrochimiques et des capteurs infrarouges, sont couramment utilisés pour déterminer les concentrations molaires des différentes espèces dans les mélanges de gaz de combustion, et pour fournir des informations concernant le rapport air-combustible associé et l'efficacité de combustion résultante. La présente invention concerne une nouvelle méthodologie d'analyse des gaz quaternaires, reposant sur une technologie thermoacoustique et permettant la détermination de la composition des mélanges habituels de gaz de combustion. Les mélanges de gaz de combustion chauds, résultant de la combustion d'un combustible fossile quelconque, peuvent remplir le résonateur d'un moteur thermoacoustique à demi-longueur d'onde optimisé à TH=900 °C. Sous refroidissement contrôlé, des oscillations de particules de gaz spontanées apparaissent à différentes valeurs de fréquences de résonance et de gradients de température de début, dépendant en particulier des concentrations molaires des constituants du gaz quaternaire (CO2, CO, O2 et N2) des échantillons introduits. Des diagrammes ternaires fonctionnels sont examinés en détail. Le nouveau capteur offre une alternative simple, fiable et relativement peu coûteuse aux analyseurs de gaz de combustion existants, aidant à évaluer l'efficacité thermique de différents systèmes d'énergie à base de combustibles fossiles. Le travail de l'invention représente la pierre angulaire des applications d'analyse des gaz de combustion reposant sur la technologie thermoacoustique.
PCT/EG2020/000029 2020-09-23 2020-09-23 Analyseur thermoacoustique de gaz de combustion WO2022063381A1 (fr)

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PCT/EG2020/000029 WO2022063381A1 (fr) 2020-09-23 2020-09-23 Analyseur thermoacoustique de gaz de combustion

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2653471A (en) * 1948-06-14 1953-09-29 Socony Vacuum Oil Co Inc Thermoacoustic gas analyzer
US7143586B2 (en) * 2002-04-10 2006-12-05 The Penn State Research Foundation Thermoacoustic device

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2653471A (en) * 1948-06-14 1953-09-29 Socony Vacuum Oil Co Inc Thermoacoustic gas analyzer
US7143586B2 (en) * 2002-04-10 2006-12-05 The Penn State Research Foundation Thermoacoustic device

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
ARTUR J JAWORSKI ET AL.: "Development of thermoacoustic devices for power generation and refrigeration", PROC IMECHE PART A: J POWER AND ENERGY, vol. 227, no. 7, pages 762 - 782, XP055303922, DOI: 10.1177/0957650913493622 *
DANIEL LOZANO-MARTÍN ET AL.: "Speeds of sound for a biogas mixture CH 4 + N2 + C02 + CO from p = (1-12) MPa at T = (273, 300 and 325) K measured with a spherical resonator", J. CHEM. THERMODYNAMICS, vol. 102, 2016, pages 348 - 356, XP029687354, DOI: 10.1016/j.jct.2016.07.033 *
J. HODGKINSON ET AL.: "Non-dispersive infra- red (NDIR) measurement of carbon dioxide at 4.2 µm in a compact and optically efficient sensor", SENS. ACTUATORS, B, vol. 186, 2013, pages 580 - 588, XP055289201, DOI: 10.1016/j.snb.2013.06.006 *
S. L. GARRETT ET AL.: "Helium gas purity monitor for recovery systems", PHYSICA B+C, vol. 107, 1981, pages 601 - 602, XP024639229, DOI: 10.1016/0378-4363(81)90603-3 *
SPOOR P. S., SWIFT G W: "Thermoacoustic Separation of a He-Ar Mixture", PHYS. REVIEW LETTERS, 1 January 2000 (2000-01-01), pages 1646 - 1649, XP055922497, Retrieved from the Internet <URL:https://www.lanl.gov/org/ddste/aldps/materials-physics-applications/condensed-matter-magnet-science/thermoacoustics/_assets/docs/PRL00MixSep.pdf> [retrieved on 20220518] *

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