Classifications

• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
  • G05D11/00—Control of flow ratio
  • G05D11/02—Controlling ratio of two or more flows of fluid or fluent material
  • G05D11/13—Controlling ratio of two or more flows of fluid or fluent material characterised by the use of electric means
  • G05D11/131—Controlling ratio of two or more flows of fluid or fluent material characterised by the use of electric means by measuring the values related to the quantity of the individual components
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N1/00—Sampling; Preparing specimens for investigation
  • G01N1/02—Devices for withdrawing samples
  • G01N1/10—Devices for withdrawing samples in the liquid or fluent state
  • G01N1/20—Devices for withdrawing samples in the liquid or fluent state for flowing or falling materials
  • G01N1/2035—Devices for withdrawing samples in the liquid or fluent state for flowing or falling materials by deviating part of a fluid stream, e.g. by drawing-off or tapping
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/0004—Gaseous mixtures, e.g. polluted air
  • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
  • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
  • G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
  • G01N33/0044—Sulphides, e.g. H2S
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/18—Water
  • G01N33/182—Specific anions in water
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T436/00—Chemistry: analytical and immunological testing
  • Y10T436/11—Automated chemical analysis
  • Y10T436/115831—Condition or time responsive
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T436/00—Chemistry: analytical and immunological testing
  • Y10T436/11—Automated chemical analysis
  • Y10T436/117497—Automated chemical analysis with a continuously flowing sample or carrier stream
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T436/00—Chemistry: analytical and immunological testing
  • Y10T436/11—Automated chemical analysis
  • Y10T436/117497—Automated chemical analysis with a continuously flowing sample or carrier stream
  • Y10T436/118339—Automated chemical analysis with a continuously flowing sample or carrier stream with formation of a segmented stream
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T436/00—Chemistry: analytical and immunological testing
  • Y10T436/18—Sulfur containing
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T436/00—Chemistry: analytical and immunological testing
  • Y10T436/18—Sulfur containing
  • Y10T436/182—Organic or sulfhydryl containing [e.g., mercaptan, hydrogen, sulfide, etc.]
  • Y10T436/184—Only hydrogen sulfide
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T436/00—Chemistry: analytical and immunological testing
  • Y10T436/25—Chemistry: analytical and immunological testing including sample preparation
  • Y10T436/25375—Liberation or purification of sample or separation of material from a sample [e.g., filtering, centrifuging, etc.]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T436/00—Chemistry: analytical and immunological testing
  • Y10T436/25—Chemistry: analytical and immunological testing including sample preparation
  • Y10T436/25875—Gaseous sample or with change of physical state

Definitions

• the present invention relates generally to wet chemical analyzers, and more particularly to an analyzer used for monitoring hydrogen sulfide in waste water. Description of the Related Art
• Hydrogen sulfide is a gas released as a by-product of biological activity in the collection and treatment of waste water.
• H 2 S is extremely corrosive to equipment and poisonous to the human body.
• the majority of odor complaints incurred by waste treatment operations can be traced to fugitive emissions of H 2 S.
• H 2 S gas is soluble in water. However, if water containing dissolved H 2 S is agitated, the H 2 S tends to come out of solution as a gas. This gas is corrosive and poisonous.
• Several control strategies are employed in the industry to control the emission of H 2 S gas. It is common practice to mount free air H 2 S detectors just above flowing streams of waste water at points of agitation.
• H 2 S that is dissolved into waste water
• various chemicals are fed into the waste water that convert H 2 S into non-toxic and non-destructive compounds. These chemicals are fed into the waste water based upon the volume of water to be treated.
• H 2 S may or may not be present in the waste water at all times or in consistent concentrations. This results in too little or too much destructor chemical being injected into the waste water the majority of the time. When too little destructor chemical is fed, only a portion of the H 2 S will be destroyed. When too much destructor chemical is fed, the user is paying for chemicals that are being wasted. Once injected, most destructor chemicals are active for approximately 15 minutes or until consumed, whichever comes first.
• the present invention discloses a hydrogen sulfide analyzer that continuously samples waste water from a waste stream or reservoir and measures the concentration of purgeable H 2 S present (H 2 SP) This information, when combined with the volume of water present, provides a control quality signal that regulates the feed rate of the destructor chemical into the waste stream. This results in chemical savings for the user.
• a second result is the reduction in odor complaints and the corrosion problems associated with H 2 S emissions.
• the analyzer measures only the purgeable H 2 S contained in the liquid sample. The analyzer violently agitates the sample containing dissolved H 2 S in solution to simulate actual conditions at points of agitation in the waste water stream.
• An object of the present invention is to provide an analyzer that measures the purgeable H 2 S in the liquid substrate.
• a further object of the present invention is to provide a H 2 S analyzer that creates control quality signals that can control the dispensing of destructor chemicals.
• a still further object of the present invention is to provide a H 2 S analyzer that controls the injection of destructor chemicals if, when, and in the proper amount based upon need.
• Still another object of the present invention is to provide an analyzer wherein the sample temperature is maintained at ambient conditions or controlled prior to analysis, since temperature affects H 2 S volatility.
• a further object of the present invention is to provide an analyzer that measures purgeable H 2 S at the current ambient sample conditions.
• a still further object of the present invention is to provide a H 2 S analyzer that is self cleaning.
• Another object of the present invention is to provide a H 2 S analyzer that combines and accounts for the liquid flow rate of the stream when creating control signals for the destructor chemical dispensing equipment.
• FIG. 1 is flow schematic of the hydrogen sulfide analyzer of the present invention
• FIG. 2 is a schematic illustrating the inputs to and outputs from the analyzer on-board microprocessor
• FIG. 3 is a schematic illustrating the gas/fluid flow in the destructor loops that prevent the release of H 2 S from the analyzer;
• FIG. 4 is a schematic illustrating the gas/fluid flow in the glass fitting that is an alternative to the destructor loops
• FIG. 5 is a perspective view of the analyzer showing the two-cabinet design
• FIG. 6 is an enlarged front elevational view illustrating the keypad and display
• FIG. 7 is a schematic of the analyzer of the present invention integrated with an alarm triggered automatic sampler
• FIG. 8 is a schematic illustrating a typical in-stream injection system
• FIG. 9 is a schematic illustrating a typical air misting system.
• FIG. 1 shows a flow schematic of the hydrogen sulfide analyzer 1 of the present invention.
• the analyzer operation is based upon the volatile nature of H 2 S.
• H 2 S gas is soluble in water. When water containing H 2 S is agitated, the H 2 S comes out of solution.
• the analyzer 1 continuously draws a sample stream from the waste water source to be analyzed.
• the sample is drawn into the analyzer 1 from the source by a peristaltic pump 10. This stream is then injected into the sparging column 20.
• the sparging column 20 is also fed by a stream of compressed gas to be described later.
• the waste water is agitated by the flow of the gas stream as it flows upwards through the sparging column 20 due to buoyancy.
• the gas stream simultaneously provides a partial pressure situation that strips the H 2 S out of solution and carries it away.
• the volumetric flow of the gas stream is regulated for consistency.
• the volumetric flow of waste water being analyzed is also regulated for consistency.
• the waste water flow is regulated via the peristaltic pump 10 being driven by a synchronous constant speed AC gear motor 30.
• H 2 S molecule effective volatilization of the H 2 S would result. Vibration of the sample liquid containing H 2 S could be accomplished mechanically. As indicated above, matching the vibration frequency and amplitude to the molecular structure would optimize results. Sparging by heating the sample liquid would also cause the H 2 S to come out of solution. There would be a specific temperature at which all of the H 2 S would exit the solution. Heating past this temperature would have no further benefit. This would be similar to a distillation process where specific weight volatiles come off at specific temperatures. Also, chemical stripping could be done by the addition of a weak acid, and possibly other chemicals, to drive the H 2 S from solution by reducing the solubility of H 2 S in the sample substrate.
• the liquid emanating from the GLS 40 is routed to drain through a standard P-trap arrangement. Any solids that entered the analyzer 1 in the sample substrate will be collected in the lowest portion of the P-trap. The liquid portion of the substrate over flows the P-trap and is routed back to the sample source via a gravity drain.
• a pinch valve 50 and a purge valve 55 are utilized on the gas exit of the P-trap.
• the pinch valve 50 is a two way normally open valve.
• the purge valve 55 is a 2-way normally closed valve located between the air supply and the P-trap. The valves 50 and 55 are energized at time intervals entered into the program by the user.
• valves 50 and 55 When the valves 50 and 55 are energized the flow of gas from the P-trap is blocked. This results in the gas stream being forced through the liquid portion of the P-trap.
• the purge valve 55 also opens and injects 30 psi air into the top of the P-trap.
• the action of this gas flow exiting through the P-trap at high velocity flushes out any solids that accumulate in the base of the trap and routes them to the drain. The interval between these flush events is selected based upon the rate of solids accumulation in the trap. This time interval will vary depending upon the sample conditions.
• the gas stream exits from the GLS 40 and passes through the pinch valve 50 descried above. This gas stream contains the carrier gas and any H 2 S that was purged from the sample. From this point the gas stream is routed to the H 2 S sensor 60 where the concentration of H 2 S in the gas stream is measured.
• H 2 S concentration data from the sensor is monitored by the on-board microprocessor 70. (See FIG.2).
• the processor 70 is able to determine the amount of purgeable H 2 S that is present in the sample being analyzed.
• This data when scaled with flow data, provides a control quality 4-20mA signal that is used to control the treatment of purgeable H 2 S in the waste water.
• the signal controls the feed rate of destructor chemical to eliminate the purgeable H 2 S.
• effective treatment of the H 2 S in the waste water may be accomplished by means other than the addition of destructor chemicals such as hydrogen peroxide or chlorine.
• Other effective treatments of the H 2 S include activation or deactivation of liquid-gas scrubbers; addition of biological substances; adjustment of the pH; adjustment of dissolved oxygen levels; and other treatments currently known or that may be later developed.
• destructor chemical After passing through the H 2 S sensor 60, destructor chemical is fed into the gas stream within the analyzer 1. Due to the pulsing nature of the peristaltic destructor chemical pump 80 and the nature of gas flow in circular conduit, the resulting gas liquid stream is comprised of volumes of gas separated by volumes of destructor liquid. See FIG. 3, showing the destructor liquid/sample gas flow detail.
• the conduit carrying this mixture is formed into a number of destructor loops to provide enough contact time for the destructor chemical to convert the H 2 S present in the gas stream into inert compounds.
• a typical destructor liquid is hydrogen peroxide or chlorine. However, there are many compounds known to chemically convert H 2 S into inert compounds.
• the number of destructor loops can be varied depending upon the concentration of H 2 S in the gas stream and the effectiveness of the chosen destructor liquid.
• the analyzer 1 illustrated in FIG. 1 contains one loop, but the number of loops may be increased if needed to prevent any emission of H 2 S by the analyzer 1.
• An alternative method of achieving the injection of destructor chemical into the analysis gas stream is to use a glass fitting in place of the destructor loop. Referring to FIG.
• the destructor chemical is fed into the bottom of the glass fitting that is essentially an enlarged T-fitting.
• the gas stream containing the H 2 S flows into the top of the fitting, the contact of the gas to the free surface of the destructor chemical will begin the conversion of the H 2 S into inert compounds. This conversion will continue as the gas/liquid mixture flows in an interrupted pattern in the conduit away from the glass fitting.
• the gas liquid mixture After passing through the destructor loop or destructor glassware, the gas liquid mixture is routed to the drain of the GLS 40. Here it combines with the liquid portion of the original sample as it falls by gravity drain back to the sample source.
• the analyzer 1 will clean the sparging column 20.
• the sample pump 10 is stopped and the clean pump 90 is started simultaneously.
• the clean pump 90 is of the same type and drive as the other two peristaltic pumps 10 and 80 described earlier.
• a cleaning solution typically 1.5 molar sodium persulfate solution in water, is pumped into the sparging column 20 instead of the sample.
• the oxidizing nature of the cleaning solution will remove accumulated debris from the interior of the sparging column 20 and route them to the GLS 40. Some cleaning of the GLS 40 by the solution will also be accomplished.
• the interval and duration of the cleaning cycle is programmed by the user. The duration and interval are adjusted based upon sample conditions. The cleaning cycle can also be manually initiated by the user.
• the final system on the flow schematic of FIG. 1 is the air supply.
• the compressed atmospheric air enters the analyzer 1 at 30 psi.
• the compressed air can be supplied via bottles or via an air compressor. After entry into the analyzer
• the compressed air is routed to the air filter 100.
• the air filter 100 removes any particles that may be contained in the air stream that are larger than 1 micron.
• the compressed air is routed through a T-fitting to both the pressure regulator 110 and the inlet of the purge valve 55.
• the purge valve 55 is used in cleaning the analyzer 1. The function of this component is described elsewhere.
• the pressure regulator 110 controls the input pressure to the capillary tube (described later).
• the pressure regulator 110 and the capillary tube work together to adjust and maintain the proper air flow into the sparging column 20.
• From the pressure regulator 110 the compressed air passes through the visual flow meter 120.
• the visual flow meter 120 is a device that gives the operator a visual display of the current flow rate of compressed air through the analyzer 1.
• the flow switch 130 is a device that provides a contact closure any time that the air flow through the switch 130 drops below 25 cc/min. If the airflow through the switch 130 falls below 25 cc/min, it is assumed that the compressed air supply to the analyzer 1 has failed.
• the microprocessor 70 monitors the switch 130 and signals the operator if a failure in the air supply is detected. From the flow switch 130, the compressed air supply next passes through the capillary tube 140.
• the capillary tube 140 is a 1 meter long tube wrapped around a cylindrical heater. Under control of the microprocessor 70 and a temperature sensor, the heater maintains the capillary tube at 60 degrees C.
• the capillary tube is a pipe with an inside diameter of 0.020 inches. This small passage creates a large pressure differential in the compressed air supply between the inlet and the outlet of the capillary tube.
• the flow rate through the tube becomes proportional to the input pressure. This is important since this air stream is used for both sparging and carrying the purged H 2 S through the sensor 60.
• the air flow must remain constant to preserve the proper dilution ratio of H 2 S flowing past the sensor 60.
• the final component in the air supply is the check valve 150. The check valve 150 prevents liquid from entering the air system components if the compressed air supply to the analyzer 1 fails.
• FIG. 5 shows a two-cabinet design that physically separates the electronics in the upper cabinet from the chemical and hydraulic components in the lower cabinet.
• the analyzer 1 is designed to operate in harsh conditions with a NEMA 4X (IP65) enclosure for protection against corrosive atmospheres.
• IP65 NEMA 4X
• the display and keypad are shown in FIG. 6. They are self-explanatory and form the user interface for input/retrieval of information.
• the menus that appear on the display are identified in Appendix 1.
• the H 2 S sensor 60 is a solid state semiconductor H 2 S sensor part #3999 supplied by Detcon, Inc., The Woodlands, Texas 77387.
• the electrical signal that is proportional to H 2 S is communicated to the CPU 70.
• the AC controller handles all AC power distribution in the unit. Also communicating with the CPU 70 is the flow meter input and analog current output.
• the CPU 70 uses both the concentration of H 2 S being detected in the analyzer 1 and the current flow rate of the waste water to create the analog current output.
• the analog current output is then used by the destructor chemical feed apparatus to set the rate of chemical feed, or the analog current output is used to control the purgeable H 2 S in the waste stream by other means as discussed above.
• the analog current output is a 4-20mA current loop.
• FIG. 7 shows the analyzer 1 integrated with an alarm triggered automatic sampler.
• FIGS. 8 and 9 illustrate typical in-stream injection and air misting systems, respectively.
• the waste water sampler depicted in FIG. 7 could be one of several models supplied by ISCO, Inc. of Lincoln, Kansas or other suppliers.
• the flow meter depicted in FIGS. 7 and 8 is an ultrasonic sensor; however, it is to be understood that other types of flow meters including submerged probe, bubbler, variable gate, area velocity sensors, and magnetic sensors supplied by ISCO, Inc. or others could be used.

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• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
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• Sampling And Sample Adjustment (AREA)
• Automatic Analysis And Handling Materials Therefor (AREA)

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• 1998
  • 1998-10-13 US US09/170,535 patent/US5981289A/en not_active Expired - Fee Related
  • 1998-10-15 AU AU10857/99A patent/AU732672B2/en not_active Ceased
  • 1998-10-15 EP EP98953502A patent/EP1023596A4/en not_active Withdrawn
  • 1998-10-15 JP JP2000516227A patent/JP3875488B2/ja not_active Expired - Fee Related
  • 1998-10-15 WO PCT/US1998/021695 patent/WO1999019726A1/en not_active Ceased

Patent Citations (7)

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