T 0337/93 07-02-1995

1. The appeal is admissible.

2. Amendments (Article 123 EPC)

The claims according to the main request and the first auxiliary request comply with the requirements of Article 123(2) and (3) EPC. Moreover, no objection under Articles 100(c) and 123(2) and (3) EPC, respectively, was raised in the proceedings so that this issue requires no further consideration.

Main request:

3. Novelty

None of the prior art citations discussed by the parties to the proceedings discloses all the features of Claim 1 and Claim 2, respectively, so that the subject-matter of these claims is novel in the sense of Article 54 EPC.

The question of novelty was also not in dispute in the appeal proceedings. This issue requires, therefore, no further consideration.

4. Inventive step

4.1. It is undisputed that (D3) discloses a process for incinerating combustible materials in which these materials are pyrolysed and in which the gases produced in the pyrolysing step are incinerated and reach an incineration temperature of 1200 C. This citation, lying in the technical field of waste combustion under very high temperatures constitutes, therefore, a relevant piece of prior art and will be considered by the expert in this field.

4.2. Claim 1 differs from (D3) in that the gases produced in the pyrolysing step are incinerated by means of air enriched with oxygen, said enrichment being sufficient to reach the incineration temperature of 1200 C while the amount of oxygen contained in the air used for the incineration is sufficient so that a demand for 6% of oxygen in the flue gases exists, so as to cut down noxious nitrogenous gases as well as dioxines, furans and other poisonous products. Furthermore, there is no explicit indication in (D3) that the combustible materials contain precursors of dioxines and furans.

4.3. In accordance with page 2, lines 48 to 52 of the patent in suit, the object of the invention is to provide a process for incinerating combustible materials containing precursors of dioxines and furans, the process ensuring a reduction of the amount of noxious gases (nitrogen oxides, NOx), and at the same time a reduction of the amounts of fresh air necessary for this incineration while still ensuring that there is enough oxygen to reduce all the hydrocarbons as well as dioxines and furans to their more harmless precursors.

The use in the combustion process of air having an increased content of oxygen per unit volume has the effect that less nitrogen as compared to a combustion with normal air is introduced into the combustion chamber which reduces the amount of nitrogen oxides produced per unit oxygen used in the combustion. At the same time, an effective cutting down of the polychlorinated compounds may be arrived at as illustrated for example by the prior art process described in (D2), see section 1.3.2, operating in a range of the combustion temperature above 1200 C.

The problem as indicated in the description of the patent in suit is manifestly solved by the subject- matter of Claim 1. This applies also in respect of Claim 2 which differs from Claim 1 only in that the feature concerning the availability of oxygen in the flue gases of 6 to 8% has been substituted for the feature concerning a demand for 6% of oxygen in the flue gases. As set out by the Respondent with reference to (D10), an availability of oxygen in the flue gases of at least 6% safeguards a complete combustion of the PCB compounds and thus achieves the decomposition of the dioxines and furans.

4.4. The process known from (D3) relates to solid waste in general without dealing with a particular kind of waste. The skilled person in the field of waste processing is aware that precursors of dioxines and furans are nearly always present in the waste, in particular, waste of industrial origin.

Therefore, the skilled person carrying out the process for incinerating waste according to (D3) will have to take account of the recommendations (constituting even regulations for one of the EPC Contracting States) provided for by "TA Luft 1983" (D10). He will make provisions in processing the waste such that an incineration temperature of at least 1200 C and an oxygen content in the flue gases of at least 6% is maintained.

It derives immediately from the requirement of having a 6% oxygen content in the flue gases that the combustion air must contain a correspondingly high proportion of oxygen so as to comply with this requirement. It is clear to the skilled person already from his basic knowledge of the combustion technology that a high proportion of oxygen in the combustion air can be obtained by an enrichment of the air with oxygen. Thus, the application of the recommendations according to (D10) in view of the processing of waste containing precursors of dioxines and furans to the process known from (D3) in a consistent manner leads the skilled person to the subject-matter of Claim 1 and Claim 2, respectively, without any difficulties having to be overcome or inventive measures being required.

It may be added that, without regard to the above considerations in view of the general knowledge of the skilled person, also (D1) would be taken into account when the production of noxious gases in processing spent materials is to be decreased. (D1) teaches that in order to reduce the pollution load of pollutants, such as SO2 and NOx, in the stack gas, air enriched with oxygen is fed into the furnace. Since the ratio of oxygen to inert gases in oxygen-enriched air is higher, less inerts are introduced into the process per mole of oxygen consumed which results in a substantial reduction of pollutants released to the atmosphere. It is further emphasised in (D1) that the burner temperature increases as the concentration of oxygen is increased (see in particular column 2, "Summary of the invention"). Thus, also (D1) would suggest to the skilled person to make use of air enriched with oxygen in the incineration process both for the purpose of reducing the noxious nitrogenous gases and for the purpose of reaching a sufficiently high incineration temperature for cutting down dioxines and furans.

4.5. The Appellant argues that the plant according to (D10) needs a post-combustion chamber and that the oxygen content in the flue gases could be less than 6% and thus insufficient for reducing efficiently the dioxines and furans.

(D10) discloses in fact that an additional burner is to be provided in the post-combustion chamber which is switched on automatically when the temperature falls below the indicated minimum value. However, a post- combustion chamber is not required in plants operating according to the fluidized bed process or in plants achieving an equivalent degree of burn-out (see page 47, section 3.2.1.2.1 (d) of (D10)). Thus, a post-combustion chamber is only required in the case where the main combustion chamber does not allow to obtain the minimum temperature of 1200 C, in all other cases it may be dispensed with. In the opinion of the Board, the reference in (D10) can only be interpreted such that the content of oxygen in the flue gas of at least 6% is maintained at a position in the combustion chamber where the predetermined temperature of 1200 C has been reached, i.e. downstream of the area of combustion or post-combustion if any.

Besides, the Board would point out that Claim 1 and Claim 2, respectively, do not exclude the possibility that the incineration temperature of 1200 C is reached in a process comprising a main and a post-combustion.

The Appellant argues further that (D10) only teaches that in order to have a maximum Cl or F content in the flue gases, a sufficient amount of air has to be used so that a sufficient dilution of Cl or F can be obtained in the flue gases.

This argument is based on the passage on page 47, section 3.2.1.2.1 (k) of (D10) according to which gaseous emissions of inorganic chlorine and fluorine compounds must not be in excess of a given mass per cubic metre of flue gas.

The conclusion from this instruction is not to increase the amount of air for diluting the pollutants, there being no teaching in (D10) in this direction. In the view of the Board, the instruction advises the skilled person rather to limit the amount of pollutants present in a unit of flue gas volume by appropriate measures. By no means is the instruction to be interpreted in the sense of increasing the amount of the combustion air since this measure would lead inevitably to an increased amount of pollutants, in particular NOx, in the flue gas which would be contrary to the general aim of reducing the noxious gases underlying the regulations pursuant to (D10).

The above arguments of the Appellant cannot, therefore, be accepted by the Board.

4.6. For the above reasons the Board comes to the conclusion that the subject-matter of Claim 1 and Claim 2 respectively, according to the main request is the result of routine activities of the skilled person and does not involve an inventive step within the meaning of Article 56 EPC. These claims cannot, therefore, be allowed.

First auxiliary request:

Claims 1 and 2 according to the first auxiliary request differ from the corresponding claims according to the main request only in that the term "solid combustible materials" has been substituted for the term "combustible materials". Since the method for thermal processing of waste known from (D3) relates to solid combustible waste, the above considerations apply analogously also to the independent Claims 1 and 2 of the first auxiliary request. These claims can therefore, likewise, not be maintained.

5. Claims 3 to 9 are dependent on the non-allowed Claims 1 and 2 respectively, according to the main and first auxiliary requests and cannot, therefore, be maintained.

Second auxiliary request:

As already illustrated in the Board's communication dated 16 August 1994, the decision under appeal is based upon the disclosure of the prior art documents (D1), (D2) and (D3). These documents have been cited by the Respondent in the Notice of Opposition which was communicated to the Appellant by the letter dated 6. December 1991. In the view of the Board, all the relevant facts upon which the decision under appeal is based were known to the Appellant from the Notice of Opposition so that no infringement of Article 113(1) EPC occurred in view of the issuing of the said decision. This present case is distinguished in this respect from the case referred to in decision T 669/90, "principle of good faith".

Besides, in the present case reimbursement of the appeal fee may not be ordered since the Board deemed the appeal not to be allowable (Rule 67 EPC).

The Appellant supports his request for remittal of the case to the first instance on the observation that the citation "TA Luft" was cited by the Respondent only recently so that the first instance had no opportunity to consider this citation. In this context, the Respondent referred to the circumstance that reference was made by him to the version of "TA Luft" valid on the priority date of the patent, that is in respect of Claims 3 and 4 of the patent as granted, already in the Notice of Opposition dated 25 November 1991, on page 6, paragraphs 3 and 4. The relevant substantial content of the citation "TA Luft" could therefore be taken into consideration already in the proceedings before the first instance.

The Board accepts this argument of the Respondent. Pursuant to Singer EPC Article 111 cipher 3 (see also decision T 273/84, OJ EPO 1986, 346) remittal to the first instance is considered inter alia in the case where new facts and evidence not taken account of in the preceding procedure have been revealed. As illustrated above, this situation does not apply in the present case so that the reason for remittal of the case put forward by the Appellant is, in fact, not convincing.

The requests for reimbursement of the appeal fee and for remittal of the case to the first instance for further prosecution are, therefore, rejected.