Burner fuel lance configuration and method of use

1. A burner for a combustion chamber of a turbogroup, the burner comprising:

a burner head;

a swirl generator enclosing a burner interior on an inlet side and which has at least one tangential air inlet relative to a longitudinal center axis of the burner;

a mixer enclosing the burner interior on an outlet side and which has an outlet opening which is open towards a combustion space of the combustion chamber;

a lance configured and arranged to introduce pilot fuel into the combustion space, which lance is arranged coaxially to the burner longitudinal center axis and extends from the burner head into the burner interior;

wherein the lance is configured and arranged so that at least when in a pilot mode of the burner the lance extends far enough into the burner interior for a flame front of a combustion reaction, which takes place in the combustion space, to extend at least partially into an end section of the burner interior which is enclosed by an outlet-side end region of the mixer; and

wherein the lance is positioned on the burner head and is longitudinally-adjustable so that, depending upon requirement, the lance can be retracted by a greater or lesser depth into the burner interior and can be extended from the burner interior by a greater or lesser distance.

2. The burner as claimed in claim 1 , wherein the lance has an outlet-side end in a section of the burner interior which is enclosed by the mixer.

3. The burner as claimed in claim 2 , wherein a distance of the lance end from the outlet opening is between 25% and 50% of the distance between an outlet-side end of the swirl generator and the outlet opening.

4. The burner as claimed in claim 1 , further comprising:

an inlet pipe for liquid fuel which projects coaxially relative to the lance into the section of the burner interior which is enclosed by the swirl generator, the inlet pipe forming an annular inlet passage for liquid fuel and having at least one axial outlet opening, the inlet pipe being arranged on the burner head.

5. The burner as claimed in claim 4 , wherein:

the inlet pipe is hollow-walled;

the inlet pipe encloses the lance, forming an axially open annular passage for air; and

the inlet passage is formed in the hollow wall of the inlet pipe.

6. The burner as claimed in claim 1 , wherein:

the lance comprises a plurality of concentrically arranged pipes including a central inner pipe and a hollow-walled outer pipe;

wherein the central inner pipe includes a central passage for liquid fuel and has at least one axial outlet opening at the lance end;

wherein the hollow-walled outer pipe encloses the inner pipe, forming an inner annular passage for guiding air, and the hollow wall of the hollow-walled outer pipe includes at least one outer passage for gaseous fuel; and

wherein the inner annular passage terminates axially open at the lance end for guiding air.

7. The burner as claimed in claim 6 , wherein the at least one outer passage in the hollow wall of the outer pipe comprises an annular passage which has:

at least one axial outlet opening at the lance end; or

a plurality of radial outlet openings in a lance end section which has the lance end; or

both.

8. The burner as claimed in claim 6 , wherein:

the at least one outer passage comprises at least one passage which has at least one axial outlet opening at the lance end, at least one outer passage being formed in the hollow wall of the outer pipe; or

the at least one outer passage comprises at least one passage which has a plurality of radial outlet openings in a lance end section which includes the lance end, the at least one passage being formed in the hollow wall of the outer pipe; or

both.

9. The burner as claimed in claim 6 , wherein the inner pipe projects axially beyond the outer pipe.

10. The burner as claimed in claim 1 , further comprising:

a wall of the mixer comprising means for film cooling.

11. A method of operating a burner for a combustion chamber of a turbogroup, the method comprising:

providing a burner for a combustion chamber of a turbogroup, the burner comprising

a burner head,

a swirl generator enclosing a burner interior on an inlet side and which has at least one tangential air inlet relative to a longitudinal center axis of the burner,

a mixer enclosing the burner interior on an outlet side and which has an outlet opening which is open towards a combustion space of the combustion chamber,

a lance configured and arranged to introduce pilot fuel into the combustion space, which lance is arranged coaxially to the burner longitudinal center axis and extends from the burner head into the burner interior,

wherein the lance is configured and arranged so that at least when in a pilot mode of the burner the lance extends far enough into the burner interior for a flame front of a combustion reaction, which takes place in the combustion space, to extend at least partially into an end section of the burner interior which is enclosed by an outlet-side end region of the mixer; and

operating the burner in a pilot mode for forming a combustion reaction, including

combusting a fuel delivered through the lance, and

longitudinally adjusting the position of the lance so that the lance tip extends far enough into the burner interior for a flame front of the combustion reaction in the combustion space to extend at least partially into an end section of the burner interior which is enclosed by an outlet-side end region of the mixer.