Method of rebuilding a sootblowing system of a recovery furnace, a sootblower for a recovery furnace, and a sootblowing system including a plurality of sootblowers

1. A recovery furnace comprising:

a plurality of sootblowers, wherein a first sootblower comprising:

a first frame,

a first moveable carriage supported by the first frame,

a first motor for moving the first carriage,

a first lance tube mounted on the first carriage to be insertable into and retractable from the recovery furnace, wherein the first lance tube having a first valve mounted thereon;

a second sootblower comprising:

a second frame,

a second moveable carriage supported by the second frame,

a second motor for moving the second carriage,

a second lance tube mounted on the second carriage to be insertable into and retractable from the recovery furnace, wherein the second lance tube having a second valve mounted thereon, wherein said first and second lance tubes each having at least one associated nozzle, and a steam feed tube connected to the first and second valves for feeding steam to be ejected through said at least one nozzles into the recovery furnace, and

a control system/arrangement constructed for admitting steam through said at least one nozzle only when the carriage with the lance tube is in an active position, wherein in a plurality of the steam feed tubes, each of the first and second sootblowers having an associated directionally controlled valve provided upstream of the first valve, wherein the control system/arrangement permitting a start of the sootblowing action of a sootblower at an arbitrary point of time between when a retraction of a preceding sootblower starts and when the retraction is completed.

2. The recovery furnace according to claim 1 , wherein said control system arrangement includes sensing means arranged to identify a position or direction of movement of said lance tube.

3. The recovery furnace according to claim 2 , wherein said sensing means includes electronic or optical sensing means.

4. The recovery furnace according to claim 1 , wherein said control system/arrangement is/are arranged to control so that only one of the directionally controlled valves is open.

5. The recovery furnace according to claim 1 , wherein said control system/arrangement includes a central control unit.

6. The recovery furnace according to claim 1 , further comprising the directionally controlled valve and a throttled bypass arranged to permit a reduced flow of steam to pass by, or through, the directionally controlled valve to cool the lance tube when the directionally controlled valve is in its closed state.

7. The sootblowing system as claimed in claim 1 , further comprising closure means that facilitates closure of said first and second valves also when the lance tube is in its activated position.

8. The sootblower system according to claim 7 , wherein said closure means is mechanically connected to a position indicating device of the sootblower.

9. The sootblower system according to claim 8 , further comprising said closure means and said closure means is arranged to facilitate activation of an opening device of the valve when said existing position indicating device is in its activated position, whereas not when said position indicating device is in its inactivated position.

10. A recovery furnace comprising:

a plurality of sootblowers, wherein a first sootblower comprising:

a first frame,

a first moveable carriage supported by the first frame,

a first motor for moving the first carriage,

a first lance tube mounted on the first carriage to be insertable into and retractable from the recovery furnace, wherein the first lance tube having a first valve mounted thereon;

a second sootblower comprising:

a second frame,

a second moveable carriage supported by the second frame,

a second motor for moving the second carriage,

a second lance tube mounted on the second carriage to be insertable into and retractable from the recovery furnace, wherein the second lance tube having a second valve mounted thereon, wherein said first and second lance tubes each having at least one associated nozzle, and a steam feed tube connected to the first and second valves for feeding steam to be ejected through said at least one nozzles into the recovery furnace, and

a control system/arrangement constructed for admitting steam through said at least one nozzle only when the carriage with the lance tube is in an active position, wherein in a plurality of the steam feed tubes, said first second valves each comprise a directionally controlled valve, wherein the control system/arrangement permitting a start of the sootblowing action of a sootblower at an arbitrary point of time between when a retraction of a preceding sootblower starts and when the retraction is completed.

11. The sootblowing system as claimed in claim 10 , further comprising closure means that facilitates closure of said first and second valves also when the lance tube is in its activated position.

12. The sootblower system according to claim 10 , wherein said closure means is mechanically connected to a position indicating device of the sootblower.

13. The sootblower system according to claim 12 , further comprising said closure means and said closure means is arranged to facilitate activation of an opening device of the valve when said existing position indicating device is in its activated position, whereas not when said position indicating device is in its inactivated position.