T 0121/94 29-05-1996

1. The appeal is admissible.

Main request:

2. Novelty

2.1 The closest prior art is described, undisputed by the parties to the appeal proceedings, by document (D1) which discloses all the features of the pre-characterising portion of Claim 1.

In this known method, a burner being supplied with air, oxygen-enriched air or pure oxygen is provided (see page 2, lines 67 to 69 and page 3, lines 115 to 130).

The skilled person is further informed (see page 2, lines 82 to 90 and page 4, lines 14 to 20 that, depending on the density of the pulverised fuel medium conveyed in a carrier gas it may be possible to discontinue or reduce the rate of supply of the combustible fluid once the desired operating temperature has been reached ..., that is at the desired point of operation.

2.2 The method according to Claim 1 differs from the method known from (D1) by the features according to the characterising portion of Claim 1.

Since (D1) reflects the closest prior art, it follows that the subject-matter of Claim 1 is novel in the sense of Article 54 EPC.

3. Inventive step

3.1 Starting from the prior art disclosed by (D1) as analysed in the description of the patent in suit, the underlying problem is seen in providing a more efficient combustion, in particular avoiding an appreciable quantity of uncombusted carbon in the ashes.

In order to solve this problem, in accordance with the characterising portion of Claim 1, the dense phase material flow transport system delivers between 20 and 30 kg of pulverised material to the oxy-fuel burner per 1 kg of propellant whereby substantially complete combustion takes place without the necessity of adding fuel gas to the burner.

In the introductory portion of the description it is pointed out that in testing the method according to the invention the pulverised fuel and oxygen burnt with an intense high-temperature flame and that the ash had the appearance of silica sand and negligible residual carbon was found.

These test results have not been disputed by the Respondent and the Board sees also no reason to question them. As a further factor relevant to the efficiency and the degree of combustion, the amount of oxygen and the degree of mixing of the oxygen with the fuel have to be considered.

Claim 1 contains, however, no information concerning these points. Assuming that the supply of the oxygen to the fuel, and their mixing, are effected under technically satisfactory conditions, it is credible to the Board that the problem as outlined in the description is solved by Claim 1.

3.2 In the technical field of combustion of fossilised fuels, it is a constant aim to achieve a high efficiency of combustion with a content of combustible compounds in the ashes as low as possible, since otherwise a waste of energy would occur.

The problem of providing a more efficient combustion, in particular avoiding an appreciable quantity of uncombusted carbon in the ashes, cannot, therefore, be regarded as comprising an inventive idea, but originates from the normal economically-based approach of the person skilled in the art.

3.3 It is undisputed by the Appellant (see page 2, section 8 of the Statement of Grounds of Appeal) that document (D2) describes a method of operating a system for burning pulverised fuel, namely coal, in which the dense phase material flow transport system delivers between 20 and 40 kg of pulverised material per 1 kg of propellant to a lance, that is a range within which the method according to Claim 1 is working (see (D2), page 215, left-hand column, paragraphs 3 to 6).

The document WO86/05520 submitted by the Respondent during the oral proceedings relates to a method of iron-making by means of a smelting shaft furnace including the steps of supplying iron ore and coke to the top of the furnace and injecting coal and oxygen into the smelting zone of the furnace to promote combustion.

As indicated in Claim 13, coal and oxygen are injected by means of oxygen and coal burners disposed around the furnace.

Page 3, line 23 ff. of the citation is worded as follows:

"The oxygen and coal may be introduced by means of a single entry element or assembly such as a lance or burner or the coal may be separately entered into the furnace from the oxygen, for example, by separate lances ..."

It is clear from this disclosure that the term "lance" is used in a two-fold way, that is according to the first meaning, it is equivalent with the term "burner" and according to a second meaning it is an element of a burner, the latter meaning being also confirmed by (D2), Figure 14 on page 217, which illustrates a coal-conveying lance as an element of a burner.

Thus, the skilled person conceives a lance either as an equivalent to or an essential part of a burner. The argument of the Appellant in this respect that the operation of a lance is clearly distinguished from that of a burner does not convince the Board, since it is not supported by the terminology used in the art.

The skilled person will therefore take into consideration the disclosure of (D2) receiving the information that the ratio of mass of pulverised fuel to mass of propellant may be in the range of 20 to 40, that is within the range claimed in order to arrive at a pulverised fuel charge of the propellant favourable to the combustion.

The further feature of Claim 1 that substantially complete combustion takes place without the necessity of adding fuel gas to the burner concerns in one respect a mere repetition of the problem, that is a goal generally strived for in combustion processes. In the other respect, the skilled person is already taught by (D1) that it may be possible, depending upon the ratio of the mass of pulverised fuel to the mass of the propellant gas, to discontinue the supply of additional fuel in fluid form (see above section 2.1). (D2) provides thus a clear pointer to the possibility of operating the system for burning pulverised fuel without adding combustible fluid and the skilled person is induced thereby to check whether on the particular point of operation of the "dense phase" mass flow of pulverised material selected such a mono-fuel combustion can be maintained.

Apart from this disclosure of (D1), in any method of burning pulversived fuel, the skilled person will dispense with adding additional fuel gas to the burner whenever an efficient combustion is possible with the pulverised fuel as the only energy source. The use of more than one type of fuel not only causes a more expensive storage and supply of fuel, but also complicates the control of conveying the fuel to the burner.

3.4 The Appellant argues further that oxygen-fuel burners and air burners are totally separate and distinct.

It is clear from the commonly known principles of combustion that a burner which is charged with oxygen instead of air provides a more efficient combustion and a flame of higher temperature whilst the basic construction of the burner whether supplied with air or with oxygen is unchanged. This is confirmed by document (D1) (see page 3, line 115 to page 4, line 30) according to which the same burner may be charged with air, oxygen-enriched air or pure oxygen, depending upon the specific operation phase and conditions. The above-cited argument of the Appellant cannot, therefore, be accepted.

3.5 No convincing argument for the existence of an inventive step in the subject-matter of Claim 1 has been presented. Moreover, no obstacle can be recognised which would have prevented the skilled person from incorporating the teaching of document (D2) in respect of the mass flow ratio of the pulverised material to the propellant into the method according to document (D1). It should also be pointed out that both of these citations relate to burners fed by pulverised fuel in a dense phase mass flow and that the aspect of improving the efficiency of combustion has to be considered as being part of the normal considerations of the person skilled in this art in general.

3.6 Summing up, the Board comes to the result that the subject-matter of Claim 1 is not based on an inventive step in the meaning of Article 56 EPC, so that this independent claim cannot be maintained and the main request has to be rejected.

Auxiliary request:

4. The independent Claims 1 and 6 comprise the feature that substantially complete combustion can be maintained without the necessity of adding external heat to the oxy-fuel burner.

As admitted by the Appellant, the originally filed documents of the application underlying the patent in suit do not contain any explicit disclosure of this feature. The same consideration applies to the feature of Claim 6 "A method of recovering ash from pulverised fuel" and to the step "(e) recovering the ash formed in step (d)".

With regard to the feature concerning the avoidance of adding external heat to the burner, the Appellant argues that the original disclosure does not mention that external heat has to be added to the burner and that this absence has to be regarded as relevant disclosure.

According to the jurisprudence of the Boards of Appeal (see T 170/87 OJ EPO 1989, 441, section 8.3) the disclosure of a particular feature must be such that the feature can be inferred in an individualised form from the originally filed description, claims or drawings.

In agreement with the above-cited decision, the Board is of the opinion that the mere absence of a feature in the originally filed documents does not make it unequivocally inferable that such a feature is to be excluded and that such exclusion forms part of the invention. Such a feature cannot be regarded as specifically disclosed and may not, therefore, be integrated in a claim.

For the above reasons, Claims 1 and 6 infringe the regulation according to Article 123(2) EPC. It follows that the auxiliary request comprising the independent Claims 1 and 6 and Claims 2 to 5 and 7 to 10 dependent thereupon has also to be rejected.