Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
  • B01D53/86—Catalytic processes
  • B01D53/8696—Controlling the catalytic process
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
  • B01D53/86—Catalytic processes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/30—Controlling by gas-analysis apparatus
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
  • B01D53/86—Catalytic processes
  • B01D53/8668—Removing organic compounds not provided for in B01D53/8603 - B01D53/8665
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/0053—Details of the reactor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/14—Production of inert gas mixtures; Use of inert gases in general
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
  • B01J2208/00008—Controlling the process
  • B01J2208/00017—Controlling the temperature
  • B01J2208/00106—Controlling the temperature by indirect heat exchange
  • B01J2208/00168—Controlling the temperature by indirect heat exchange with heat exchange elements outside the bed of solid particles
  • B01J2208/00256—Controlling the temperature by indirect heat exchange with heat exchange elements outside the bed of solid particles in a heat exchanger for the heat exchange medium separate from the reactor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
  • B01J2208/00008—Controlling the process
  • B01J2208/00017—Controlling the temperature
  • B01J2208/00106—Controlling the temperature by indirect heat exchange
  • B01J2208/00265—Part of all of the reactants being heated or cooled outside the reactor while recycling
  • B01J2208/00274—Part of all of the reactants being heated or cooled outside the reactor while recycling involving reactant vapours
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/78—Preparation processes
  • C08G63/80—Solid-state polycondensation
• • 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
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S423/00—Chemistry of inorganic compounds
  • Y10S423/05—Automatic, including computer, control

Definitions

• the present invention relates to a method according to the preamble of claim 1 and to a system according to the preamble of claim 7.
• the object of the present invention is therefore to improve the effectiveness of the previous methods for purifying a gas stream of the type mentioned in the preamble of claim 1. This is achieved by the characterizing features of claim 1.
• the hypo-stoichiometric amount of oxygen is preferably 98% to ⁇ 100%, preferably at least 99%, of the stoichiometric.
• a lambda probe (It. Römpps Chemie Lexikon one writes " ⁇ " as a symbol for the molar electrolyte conductivity) represents two layers of noble metal, like Pt, on a solid electrolyte with connected electrodes. It is striking that this structure corresponds to that of the monitoring catalyst is very similar. It is therefore entirely possible within the scope of the invention to use the catalytic converter itself as a lambda probe-like measuring cell, the monitoring signal, of course, having to be correspondingly filtered out, decoupled or demodulated.
• the lambda probe is interposed, it is an essential feature of its use that a direct measurement of the elements or electrolytes involved is now possible instead of the previous indirect measurement, with the addition of the lambda probe has particularly favorable characteristics for an exact measurement.
• the fact that it has not been used so far was probably due to the fact that the stoichiometric or hyper-stoichiometric amount of oxygen was so influenced that one thought that the unburned oxygen had to be measured.
• the lambda probe is also freer in terms of process control, because if the method according to the invention is used for processes other than the polycondensation of synthetic resins, an inert gas may not be necessary at all, the measurement using the oxygen present in the process in the previous measurement method would be additionally impaired.
• an inert gas can be used as the contaminated gas, which is preferably at least partially recycled into the reactor after cleaning.
• the monitoring is carried out by means of at least one lambda probe upstream of the catalytic converter and / or that the monitoring is carried out by means of at least one lambda probe on the catalytic converter.
• the monitoring of the final result of the cleaning is after the Catalyst, of particular interest, but such monitoring can also be included in the regulation.
• a particularly preferred system for carrying out the method according to the invention has the features of claim 8.
• FIG. 1 shows a diagram of the process on which the invention is based with an exemplary embodiment according to the invention
• Fig. 4 shows another characteristic of the lambda probe
• a reactor 1 is provided for the solid-phase condensation of polyester resins, such as polyethylene terephthalate. It is of conventional design, so that a detailed description can be omitted, the supply and removal of resin material taking place via cellular wheel locks 2 and 3, respectively.
• the exhaust gas from the condensation process is first fed via a waste gas line 4 to a filter 5 for removing particulate contaminants.
• the waste heat of this gas which is still contaminated with gaseous impurities, is then advantageously used in a heat exchanger 6, which is provided in a feed line 7 to a catalyst 8.
• An air feed 9 ensures the supply of a gas containing at least oxygen, ie either pure oxygen or a gas such as air, which contains only a corresponding proportion of oxygen.
• This oxygen is used for the oxidation of the impurities contained in the gas flowing through the feed line 7 and flows to the feed line 7 shortly before the catalyst 8.
• the gas streams thus combined with one another and routed in a collecting line 11 are expediently prepared brought the catalyst 8 to an optimum temperature for the oxidation taking place in the catalyst 8 with the aid of an electric heater 10. This is expediently in the range from 280 ° C to 380 ° C.
• the collecting line 11 then enters the catalytic converter 8.
• the catalyst unit 8, 8 ' also has an outlet line 24, which is advantageously returned to the reactor, for example via a heater 23 or previously via the heat exchanger 6, in particular when - as is customary in the case of polycondensation - the gas to be cleaned is a Is inert gas, such as nitrogen.
• the catalyst body 8 ' is constructed similarly to the lambda probe ⁇ shown in a section in FIG. 2, ie a porous inert carrier layer 16 is provided, on the surface of which a noble metal layer 14 is applied.
• the lambda probe also has a solid electrolyte 17, which is coated with a noble metal layer 15.
• the layer 17 can consist, for example, of zirconium oxide ZrO 2 , whereas the layers 14 and 15 mostly have Pt, ie either consist entirely of platinum or of an alloy. While, for example, palladium alloys are common, a rhodium alloy is preferably provided for the catalyst body 8 '.
• the lambda probe itself can have pure platinum layers 14, 15.
• a DC voltage U is applied between layers 14 and 15, which produces the desired electrolyte effect.
• the gas to be examined is located on the side of the layer 16, whereas air (as a reference) is present on the side of the noble metal layer 15.
• the catalyst 8 itself as a lambda probe-like measuring device, ie for determining the electrolytes, and the output signal obtained in this way is output to line 13 (FIG. 1).
• a further lambda probe ⁇ 2 namely at the outlet of the catalyst unit 8, 8 ', can be provided. The latter can measure the result of the cleaning and send a corresponding signal to a line 18. It goes without saying that, if need be, only a single lambda probe needs to be used, as is also the case within the scope of the invention to provide further measuring points with lambda probes.
• the lambda probe ⁇ 2 measures the result achieved, it cannot be overlooked that it only measures at a relatively late point in the course of the gas flow, which may be unsuitable for rapid control. It can therefore be advantageous to provide a differentiating element in line 18 in order to more quickly identify the tendency of any control deviation. On the other hand, it will generally be more advantageous for rapid regulation if at least the lambda probe ⁇ i is used. If both lambda probes ⁇ i and ⁇ 2 are used , there is the additional advantage that the aging of the catalytic converter influencing the measurement result can be determined, as has already been established with auto-catalytic converters (Hansjörg Germann et al. "Differences in Pre- and Post-Converter Lambda-Sensor Characteristics "Electronic Engine Controls 1996, SP-1 149, pp. 143-147).
• the electrical lines 12, 13 and 18 lead to a processor ⁇ which receives the signals of lines 12 and 18 (if they are already digital) directly or has an analog / digital converter at its input.
• a preprocessing of the measurement signal supplied via it will generally be necessary in order to prevent it from noise signals and the like. cut off. This can be done in a filter, demodulator or (generally) signal shaping stage 19 at the input of the processor ⁇ .
• the chronological order of the measurements must first be taken into account. The sequence will be the shorter (and therefore less relevant for the control) as the flow velocity of the gases increases.
• the signals coming in via lines 12, 13 and 18 are also weighted before they are compared with a TARGET signal from a, preferably adjustable, setpoint generator 20. The result of this comparison results in a deviation or control gnal, which is led from the output of the processor ⁇ via a line 21 to a controller 22.
• the controller 22 advantageously changes a valve V in line 9 in a corresponding manner.
• the structure of the lambda probe ⁇ has already been described above with reference to FIG. 2.
• the advantage of using such a probe is that it has a very steep characteristic, as can be seen in FIG. 3. It shows the equilibrium oxygen partial pressure in bar on the ordinate and the ratio of oxygen to the contaminant gas to be burned on the abscissa.
• the output voltage of the respective lambda probe can be plotted (see the values for ⁇ 2 in Table 2), in which case curve C reverses and drops from the top left to the bottom right.
• the lambda probe ⁇ now has a characteristic C, which shows a particularly steep rise especially in the area of a dash-dotted line S.
• Line S corresponds to a stoichiometric ratio of oxygen to contaminant gas to be burned. From this line S to the left are the values of a "fat mixture", i.e. here is the hypo-stoichiometric range with small amounts of oxygen, in which work is carried out according to the invention. If a stoichiometric amount of oxygen is assumed to be 100%, it goes down to the left in the range of 99%, whereas to the right the hyper-stoichiometric areas corresponding to an amount of oxygen> 100% are located. Accordingly, in the control according to the invention, control is expediently carried out in a region of curve C which lies between two points P1 and P2, the spacing of which corresponds to a control region R.
• control electronics record the Nernst voltage and supply the pump cell with a variable pump voltage.
• the controller compares the measured Nernst voltage with one Setpoint and provides the pump cell with such a current that causes the oxygen concentration to approach the setpoint more and more.
• the pump current depends on ⁇ and is therefore a measure of the oxygen concentration in the exhaust gas.
• the pump current is entered in l p on the ordinate and the air number of the exhaust gas in ⁇ on the abscissa.
• the pump current l p that is established is a measure of lambda and thus also a measure of the actual oxygen concentration in the exhaust gas. Accordingly, in the control according to the invention, control is expediently carried out in a region of the curve Ci which lies between two points P1 and P2 in FIG. 4, the distance between which corresponds to a control region R.
• lambda factor i.e. the factor of the stoichiometric amount of oxygen.
• a test facility of the type shown in FIG. 1 was used, only the lambda probe ⁇ 2 being used to determine the residual oxygen content in ppm.
• the lambda probe was a Bosch product, type LSM 1 1.
• a Pt catalyst according to the prior art was used, of which the conversion of 95% was known. The values for 100% and 99% were calculated on the basis of the amounts of oxygen found.
• Test 1 used an excess of oxygen of 101% of the stoichiometric amount, as in U.S. Patent No. 5,547,652. As expected, this resulted in a relatively high residual oxygen content of 75.0 ppm. Thereafter, the stoichiometric oxygen content of 100% was checked in experiment 2. In this experiment No. 2, a residual oxygen content of 62.5 ppm was still measured. Only in the case of a 100% catalytic conversion of the gas to be oxidized, ethylene glycol, which does not occur in practice, would there be a residual oxygen content of 0 ppm.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Environmental & Geological Engineering (AREA)
• Analytical Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Health & Medical Sciences (AREA)
• Biomedical Technology (AREA)
• Organic Chemistry (AREA)
• Exhaust Gas Treatment By Means Of Catalyst (AREA)
• Exhaust Gas After Treatment (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Measuring Oxygen Concentration In Cells (AREA)
• Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
• Silicon Compounds (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
• Lasers (AREA)
• Sampling And Sample Adjustment (AREA)
• Hydrogen, Water And Hydrids (AREA)

Priority Applications (9)

Applications Claiming Priority (2)

Publications (1)

Family

ID=7876417

Family Applications (1)

Country Status (15)

Cited By (2)

Families Citing this family (12)

Citations (4)

Family Cites Families (3)

• 1998
  • 1998-08-04 DE DE19835186A patent/DE19835186A1/de not_active Withdrawn
• 1999
  • 1999-07-19 PL PL99345807A patent/PL195905B1/pl not_active IP Right Cessation
  • 1999-07-19 TR TR2001/00420T patent/TR200100420T2/xx unknown
  • 1999-07-19 KR KR1020017001467A patent/KR100596263B1/ko not_active Expired - Fee Related
  • 1999-07-19 DE DE59903562T patent/DE59903562D1/de not_active Expired - Lifetime
  • 1999-07-19 US US09/700,291 patent/US6548031B1/en not_active Expired - Fee Related
  • 1999-07-19 CN CNB998087769A patent/CN1167492C/zh not_active Expired - Fee Related
  • 1999-07-19 ES ES99928992T patent/ES2188185T3/es not_active Expired - Lifetime
  • 1999-07-19 BR BR9912725-3A patent/BR9912725A/pt not_active Application Discontinuation
  • 1999-07-19 EP EP99928992A patent/EP1100611B1/de not_active Expired - Lifetime
  • 1999-07-19 AT AT99928992T patent/ATE228390T1/de not_active IP Right Cessation
  • 1999-07-19 AU AU45987/99A patent/AU752167B2/en not_active Ceased
  • 1999-07-19 PT PT99928992T patent/PT1100611E/pt unknown
  • 1999-07-19 JP JP2000563371A patent/JP2002522195A/ja not_active Withdrawn
  • 1999-07-19 WO PCT/CH1999/000332 patent/WO2000007698A1/de not_active Ceased
  • 1999-07-19 CA CA002337840A patent/CA2337840A1/en not_active Abandoned

Patent Citations (4)

Also Published As

Similar Documents

Legal Events