EP0010390B1 - Verfahren und Mittel zum Vermindern der Korrosion auf kalten Stellen - Google Patents

Verfahren und Mittel zum Vermindern der Korrosion auf kalten Stellen Download PDF

Info

Publication number
EP0010390B1
EP0010390B1 EP19790302132 EP79302132A EP0010390B1 EP 0010390 B1 EP0010390 B1 EP 0010390B1 EP 19790302132 EP19790302132 EP 19790302132 EP 79302132 A EP79302132 A EP 79302132A EP 0010390 B1 EP0010390 B1 EP 0010390B1
Authority
EP
European Patent Office
Prior art keywords
additive
combustion
amount
combustion gases
cold
Prior art date
Legal status (The legal status 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 status listed.)
Expired
Application number
EP19790302132
Other languages
English (en)
French (fr)
Other versions
EP0010390A1 (de
Inventor
Richard J. Sujdak
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BetzDearborn Europe Inc
Original Assignee
Betz Europe Inc
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
Priority claimed from US05/950,960 external-priority patent/US4185071A/en
Priority claimed from US06/019,687 external-priority patent/US4206172A/en
Application filed by Betz Europe Inc filed Critical Betz Europe Inc
Publication of EP0010390A1 publication Critical patent/EP0010390A1/de
Application granted granted Critical
Publication of EP0010390B1 publication Critical patent/EP0010390B1/de
Expired legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
    • C23F11/02—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in air or gases by adding vapour phase inhibitors

Definitions

  • the sulfur in the fuel is converted to sulfur dioxide and sulfur trioxide.
  • sulfur trioxide and water vapor are in equilibrium with sulfuric acid. Below about 232°C. essentially all of the S0 3 is converted to H Z S0 4 for typical flue gas compositions of oil fired boilers.
  • the resulting sulfuric acid condenses upon metal surfaces which are at temperatures below the acid dewpoint. Corrosion results from the attack of the condensed sulfuric acid on the metals.
  • United States Patent Specification No. 2,053,024 there is disclosed a method of conditioning steam systems to prevent corrosion of the metal parts, which comprises introducing into the system an alkaline, water-soluble, volatile, non-aromatic amine.
  • United Kingdom Patent Specification No. 1,338,908 discloses a method of preventing the corrosion'of a distillation apparatus producing an acid substance, which comprises controlling the pH of the finally condensed liquid to be in the range of 7-8 by adding at least one alkaline component selected from ethylene diamine, trimethylenediamine. propylene diamine and piperazine to the acid substance within the apparatus.
  • the basic area to which the present invention is directed is often referred to in the industry as the "cold-end" of a boiler. This area is generally the path in the boiler system that the combustion gases follow after the gases have, in fact, performed their primary service of producing and/or super-heating steam.
  • the last stages through which the hot combustion gases flow include the economizer, the air heater, the collection equipment or electrostatic precipitator, and then the stack through which the gases are discharged.
  • the present invention is drawn to the present inventor's discovery of ethylene polyamines optionally in combination with aliphatic, water-soluble alkanolamines, as cold-end additives. It was determined that if this additive is fed, preferably in droplet form, and preferably as an aqueous solution, to the moving combustion gases upstream of the cold-end surfaces to be treated and preferably at a point where the gases are undergoing turbulence, it will travel along with the gases as vapor and/or liquid droplets and deposit on the downstream cold-end surfaces. It is understood that any reference to ethylene polyamine is intended to include mixtures of such compounds and any reference to alkanolamine is intended to include mixtures thereof.
  • a point of turbulence of the combustion gases is a preferred feed point for the additive
  • a point of laminar gas flow could also be used, provided that suitable mechanical means are utilized to create a zone of relative turbulence for proper treatment distribution.
  • suitable mechanical means are utilized to create a zone of relative turbulence for proper treatment distribution.
  • an increased number of spray nozzles may be suitably arranged within a gas flow conduit to provide adequate treatment distribution.
  • the invention in addition to providing a method of reducing the amount of sulfuric acid corrosion of metal parts at the cold-end of a combustion system also provides a composition for such use which comprises (i) aliphatic, water-soluble alkanolamine, and (ii) ethylene polyamine.
  • ethylene polyamines is intended to include hydrocarbon chains consisting of at least two amino groups connected by ethylene group(s). For example, the lowest homolog in the series would be ethylene diamine having the following structure:
  • ethylene polyamines according to the present invention could best be described by the following:
  • n is 0. It is the present inventor opinion that there is no upper limit for n in Formula I other than that based on the commercial availability of the material.
  • the highest homolog tested was poly(ethylenimine) having the formula: which material had an average molecular weight of about 50,000 to 100,000; and, therefore, n was about 1000 to 2500. While all of the compounds tested had ethylene groups connecting the amino groups, it is believed that other lower alkyl interconnecting groups could be used. For example, it is the present inventor's belief that trimethylene or tetramethylene groups are suitable equivalents for the ethylene group. However, preliminary testing has indicated the hexamethylene interconnecting groups are unsuitable for the purpose.
  • the additive can be fed neat; however, an aqueous solution of additive is preferred. Due to its high solubility in water, the concentration of actives in the aqueous solution could, of course, vary over a wide range, depending only on economics of handling and shipment and the characteristics of the feed system. For example, the additive could be shipped neat and diluted at the point of application. If dilution at the point of application is undesirable or not possible, then the additive would be sent pre-diluted. Due to costs of shipment and handling, it would be undesirable to ship very dilute aqueous solutions. The preferred lower concentration limit would be about 5% actives on a weight basis, with the most preferred lower limit being about 15%. The upper concentration limit could approach 100%, however, about 60% represents the preferred upper limit.
  • the additive is preferably added to the combustion gases upstream, in the direction of flow of the combustion gases through the combustion system, of the metal parts, and may be added to the combustion gases at a point of turbulence or at a point of laminar flow.
  • the additive may be added in droplet form, it may be added in aqueous form, it may be sprayed into the combustion gases.
  • the additive could be sprayed at a point of turbulence of the combustion gases upstream of the problem area using any well known atomizing spray nozzle(s).
  • precautions should be taken to ensure that the problem areas will encounter treated flue gas. For instance, if the problem area is located centrally within a flow conduit for the combustion gases, the spray should be directed into the conduit in such a manner as to ensure that a sufficient amount of additive is present in the centre of the conduit upon reaching the location of the problem area.
  • an axially located spray nozzle which sprays the additive in the same direction that the combustion gases flow would be recommended for such a centrally located problem area. While the additive could be fed neat an aqueous solution is preferred.
  • the amount of additive used could vary over a wide range depending on the nature and severity of the problem to be solved and would be a function of the sulfur content of the oil.
  • the particular species is also seen to be an important consideration with respect to feedrate.
  • mol/I triethylenetetramine per liter
  • the upper limit would be considered to be 6.3x10 -3 mol/I based on economic considerations, with 3.2 10 -3 mol/I representing a preferred upper limit.
  • the active alkanolamine could be fed in an amount as low as 3.2x10 -4 mol/I.
  • the preferred lower limit is 6.3x10 -4 mol/I.
  • the amount of active alkanolamine could be as high as 6.3x10- 3 mol/I, with 4.7x10 -3 mol/I representing the preferred upper limit.
  • the inventive additive is considered to comprise from 2.5 x10 -6 to 6.0x10 -3 mol/I of ethylene polyamine and from 3.2x10 -4 to 6.3 ⁇ 10 -3 mol/I of alkanolamine.
  • the preferred relative proportions are from 6.3 to 10 -4 to 3.2x10 -3 mol/I ethylene polyamine and from 6.3x10 -4 to 4.7x10 -3 mol/I alkanolamine. Based on economic considerations, the total amount of active additive should not exceed 6.9x 10 -3 mol/I.
  • the temperature of the combustion gases at the point of feed is typically 204°C to 399°C, but this range could widen depending on the gas temperature at the furnace exit.
  • a cold-end additive should be capable of travelling along with the combustion gases and depositing on the downstream cold-end surfaces to be treated, the various additives tested were sprayed, using a standard atomizing spray nozzle arrangement, into the combustion gases at a point of turbulence located upstream of the air-cooled probe.
  • the boiler was taken through a soot blowing cycle, and the burner tip was manually cleaned. The boiler was then base loaded for one hour prior to initiating testing. Fuel oil of precisely the same composition was fired over a given period of time to ensure reproducibility of baseline data throughout the period. However, for critical testing, daily determination of baseline data is recommended.
  • the boiler was fired with number 6 grade fuel oil containing 1% sulfur (by weight). The oil was preheated to 76.7°C and atomized with steam. Combustion air was at ambient temperature. Flue gas temperatures at the sampling point ranged from 227°C to 249°C.
  • the sulfuric acid dewpoint using either a Land Dewpoint Meter or a corrosion probe was typically 128°C. Using a Research Appliance Corporation sampling device, the concentration of S0 3 was determined to be above 7 parts per million parts of combustion gas (ppm, on volume basis).
  • the materials tested were ethylene diamine, available from Union Carbide; diethylenetriamine, obtained from Fisher; triethylenetetramine, obtained from Aldrich; tetraethylenepentamine, obtained from Aldrich; poly (ethylenimine), also obtained from Aldrich, and ethylamine, obtained from Pennwalt.
  • the results of a series of tests are reported below in Table 1, wherein a different test number indicates that tests were conducted on a different day.
  • the % O2 reported is the oxygen content of the combustion gas on a volume basis.
  • the additive feedrates are reported as mole(s) of feed per 10 3 liters of fuel oil consumed (mol/10 3 l, and the probe corrosion results are reported as % reduction in iron content of the probe washings for the indicated temperatures as compared to base condition corrosion.
  • Figure 1 are reported the results of tests comparing diethylenetriamine and triethylenetetramine to base conditions. As can be seen from the figure, the results are graphically reported as a plot of concentration of iron in the probe washings, in ppm, against the sampling temperature in °C. The results for base conditions are represented by circles, the results for diethylenetriamine are represented by squares, and the results for triethylenetetramine are represented by triangles.
  • the boiler was operated at approximately 6,350 kg of steam per hour with oxygen being 6% of the flue gas.
  • the additives were both fed at a rate of 2.1x10 -3 mole per liter of oil consumed (2.1 x 10 -3 mol/I).
  • Figure 2 are reported the results of tests comparing ethylene diamine and poly(ethylenimine) to base conditions.
  • the poly(ethylenimine) has a molecular weight average of about 50,000 to 100,000 such that n in Formula I above would be about 1000 to 2500.
  • the results are graphically reported as a plot of concentration of iron in the probe washings, in ppm, against the sampling temperature °C.
  • the results for base conditions are represented by solid circles
  • the results for ethylene diamine are represented by solid squares
  • the results for poly(ethylenimine) are represented by solid triangles.
  • the boiler was operated at approximately 5,450-5,900 kg of steam per hour with oxygen being about 6% of the flue gas.
  • the ethylene diamine was fed at a rate of 2.4x 10- 3 mol/I of fuel oil consumed, and the poly(ethylenimine) was fed at a rate of 0.23 milliliters per liter of oil consumed. Due to the uncertainty of the exact molecular weight of the poly-(ethylenimine), no exact molar feedrate was calculable. However, based on the noted molecular weight range for the material and a density of approximately 1 gram per milliliter, the feedrate was about 2.5 10 -6 to 4.4 x 10 -e mol/I.
  • the various additives tested were sprayed, using a standard atomizing spray nozzle arrangement, into the combustion gases at a point of turbulence located upstream of the air-cooled probe.
  • the boiler was fired with number 6 grade fuel oil containing 1% sulfur (by weight).
  • the oil was preheated to 77°C and atomized with steam. Combustion air was at ambient temperature. Flue gas temperatures at the sampling point ranged from 227°C to 249°C.
  • the sulfuric acid dew point using either a Land Dew Point meter or a corrosion probe was typically 128°C.
  • concentration of S0 3 was determined to be about 7 parts per million parts of combustion gas (ppm, on volume basis).
  • the oxygen content of the flue gas was kept at about 6%.
  • the materials tested were monoethanolamine, obtained from Fisher; 2-(ethylamino)ethanol, obtained from Fisher; 3-amino-1-propanol, obtained form Eastman; 2-amino-2-methyl-1-1 propanol, obtained from iMC; 2-dibutyl-amino-ethanol, obtained from Eastman; 2-amino-2-ethyl-1,3-propanediol, obtained from Aldrich; 1-amino-2-propanol, obtained from Eastman; triethanolamine. obtained from Eastman; and diisopropanolamine, obtained from Dow.
  • the additive feedrates are reported as mole(s) of additive per liter of oil consumed (mol/l,) and the probe corrosion results are reported as 96 reduction in iron content of the probe washings for the indicated temperatures as compared to base condition corrosion. Negative results indicate a condition of increased corrosion of the probe as compared to base conditions.
  • the steam loads are reported as kilograms per hour (kg/h).

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
  • Solid Fuels And Fuel-Associated Substances (AREA)

Claims (12)

1. Verfahren zur Verringerung der Schwefelsäure-Korrosion von Metallgegenständen am kalten Ende eines Verbrennungssystems und in Berührung mit Verbrennungsgasen aus der Verbrennung von schwefelhaltigem Brennstoff durch Zugabe zu den Verbrennungsgasen einer entsprechenden Menge eines Additivs in Form eines Ethylenpolyamins der allgemeinen Formel
Figure imgb0011
worrin n 0 oder eine ganze Zahl sein kann.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß das Verbrennungssystem ein Dampferzeugungs-System und der Brennstoff ein schwefelhaltiges Öl ist.
3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß das Additiv eine wässrige Lösung von Ethylenpolyamin ist, welche der Verbrennungsgasen in einer Menge von 6.3 . 10-4 bis 6,3 mol/103 verbrauchten Brennstoffs zugesetzt wird.
4. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Verbrennungsgase über einen langen Weg am kalten Ende des Verbrennungssystems von einer ersten Zone relativer Turbulenz zu einer zweiten Zone strömen, in der Metallteile angeordnet sind, wobei das Additiv
a) ein aliphatisches wasserlösliches Alkanolamin und
b) zumindest ein Ethylenpolyamin der Formel aus Anspruch 1 enthält,

wobei dieses Additiv als Dampf und/oder in Form von Flüssigkeitströpfchen zusammen mit den Verbrennungsgasen aus der Zone relativer Turbulenz in die zweite Zone wandert und sich auf den Metallteilen abscheidet.
5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, daß man Ethylenpolyamin in einer Menge von 2,5 . 10-3 bis 6 mol/103 verbrauchten Brennstoff und Alkanolamin in einer Menge von 0,32 bis 6,3 mol/103 verbrauchten Brennstoff zugibt.
6. Verfahren nach Anspruch 5, dadurch gekennzeichnet, daß die Gesamtmenge an Additiv 6,9 mol/103 I verbrauchten Brennstoff nich übersteigt.
7. Verfahren nach Anspruch 4 bis 6, dadurch gekennzeichnet, daß das Ethylenpolyamid Triethylentetramin in einer Menge von 0,41 mol/103 I verbrauchten Brennstoff und das Alkanolamin Monoethanolamin in einer Menge von 0.96 mol/103 I verbrauchten Brennstoff ist.
8. Zusatzmittel zur Verringerung der Schwefelsäure-Korrosion von Metallteilen am kalten Ende eines Verbrennungssystems in Berührung mit Verbrennungsgasen aus der Verbrennung schwefelhaltigen Brennstoffs, bestehend aus
a) einem aliphatischen wasserlöslichen Alkanolamin und
b) einem Ethylenpolyamin der allgemeinen Formel, wie sie in Anspruch 1 definiert ist.
9. Mittel nach Anspruch 8, dadurch gekennzeichnet, daß das Alkanolamin Monoethanolamin ist.
10. Mittel nach Anspruch 8 oder 9, dadurch gekennzeichnet, daß das Ethylenepolyamin Triethylentetramin ist.
11. Mittel nach Anspruch 10, dadurch gekennzeichnet, daß das Molverhältnis Monoethanolamin zu Triethylentetramin etwa 2,3:1 beträgt.
EP19790302132 1978-10-13 1979-10-08 Verfahren und Mittel zum Vermindern der Korrosion auf kalten Stellen Expired EP0010390B1 (de)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US950960 1978-10-13
US05/950,960 US4185071A (en) 1978-10-13 1978-10-13 Ethylene polyamines as cold-end additives
US1968679A 1979-03-12 1979-03-12
US19686 1979-03-12
US19687 1979-03-12
US06/019,687 US4206172A (en) 1978-10-13 1979-03-12 Alkanolamines and ethylene polyamines as cold-end additives

Publications (2)

Publication Number Publication Date
EP0010390A1 EP0010390A1 (de) 1980-04-30
EP0010390B1 true EP0010390B1 (de) 1982-09-29

Family

ID=27361268

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19790302132 Expired EP0010390B1 (de) 1978-10-13 1979-10-08 Verfahren und Mittel zum Vermindern der Korrosion auf kalten Stellen

Country Status (3)

Country Link
EP (1) EP0010390B1 (de)
CA (1) CA1113236A (de)
DE (1) DE2963783D1 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103614727B (zh) * 2013-11-28 2015-12-09 阜阳安固锅炉压力容器制造有限公司 一种水基金属表面防锈液及其制备方法

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2053024A (en) * 1934-02-16 1936-09-01 Western Chemical Company Compound and method for conditioning boiler, steam and condensate systems
US2750339A (en) * 1953-04-03 1956-06-12 Exxon Research Engineering Co Method for inhibiting corrosion
US2972681A (en) * 1956-08-10 1961-02-21 Westinghouse Electric Corp Cinefluorographic apparatus
NL262711A (de) * 1960-03-23
US3406042A (en) * 1965-12-14 1968-10-15 Cons Edison Co New York Inc Process for corrosion control
GB1338908A (en) * 1969-12-08 1973-11-28 Kurita Water Ind Ltd Method of preventing corrosion in distillation apparatus substituent
US4134727A (en) * 1976-08-12 1979-01-16 Betz Laboratories, Inc. Aqueous solution of sodium metasilicate and N-aminoethyl ethanolamine as a cold-end additive

Also Published As

Publication number Publication date
CA1113236A (en) 1981-12-01
EP0010390A1 (de) 1980-04-30
DE2963783D1 (en) 1982-11-11

Similar Documents

Publication Publication Date Title
Srivastava et al. Emissions of sulfur trioxide from coal-fired power plants
US4206172A (en) Alkanolamines and ethylene polyamines as cold-end additives
EP2337625B1 (de) Verfahren zur reduktion des tropfendurchmessers einer harnstofflösung unter verwendung einer mischung oberflächenaktiver alkoxylierter verbindungen
US3860430A (en) Filming amine emulsions
EP1848524B1 (de) Gezielte leitungseinspritzung zur so3-regelung
US9925490B2 (en) Flue gas treatment device
EP0013243A1 (de) Eine wässrige Lösung von Metallsalzen enthaltende Konditionierungsmittel für Rückstands-Heizöl und Verfahren zur Verbesserung der Verbrennung damit
US4224180A (en) Cold end additive compositions
JPH067010B2 (ja) 石油燃焼ボイラー装置よりの有害物質の放出を選択的かつ非接触的に減少せしめる方法
US4185071A (en) Ethylene polyamines as cold-end additives
US4051225A (en) Method for the heat recovery in the processes of the removal of nitrogen oxides from exhaust gases
EP0010390B1 (de) Verfahren und Mittel zum Vermindern der Korrosion auf kalten Stellen
CN101198679A (zh) 防止锅炉的热传递表面沉积氯的方法
EP0034574A2 (de) Verfahren zum Vermeiden von Korrosionen in der Ausrüstung einer Kesselanlage
US4168291A (en) Alkanolamines as cold-end additives
US4134727A (en) Aqueous solution of sodium metasilicate and N-aminoethyl ethanolamine as a cold-end additive
US20050150441A1 (en) Process for reducing plume opacity
US4134729A (en) Aqueous solution of sodium aluminate and N-aminoethyl ethanolamine as a cold end additive
US4628836A (en) Process for inhibiting corrosion and minimizing deposits in an air preheater system
US4134728A (en) N-aminoethyl ethanolamine as a cold-end additive
FI128556B (en) METHOD OF GAS FLOW TREATMENT AND EMISSIONS MANAGEMENT SYSTEM
EP0862939A2 (de) Verfahren und Vorrichtung zur Abgasbehandlung
US4310438A (en) Polyethyleneamines as sulfite antioxidants
US10626750B2 (en) Top-pressure recovery turbine deposition control
EP0018084B1 (de) Verfahren zur Entfernung von Partikeln aus einem Partikeln enthaltenden Gasstrom

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): BE DE FR GB IT NL

17P Request for examination filed
ITF It: translation for a ep patent filed
GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Designated state(s): BE DE FR GB IT NL

REF Corresponds to:

Ref document number: 2963783

Country of ref document: DE

Date of ref document: 19821111

ET Fr: translation filed
RAP2 Party data changed (patent owner data changed or rights of a patent transferred)

Owner name: BETZ EUROPE, INC.

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19830928

Year of fee payment: 5

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 19831031

Year of fee payment: 5

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19831103

Year of fee payment: 5

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: BE

Payment date: 19831130

Year of fee payment: 5

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: BE

Effective date: 19841031

BERE Be: lapsed

Owner name: BETZ INTERNATIONAL INC.

Effective date: 19841008

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Effective date: 19850501

GBPC Gb: european patent ceased through non-payment of renewal fee
NLV4 Nl: lapsed or anulled due to non-payment of the annual fee
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19850628

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Effective date: 19850702

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Effective date: 19881118

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT