Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D9/00—Stators
  • F01D9/02—Nozzles; Nozzle boxes; Stator blades; Guide conduits, e.g. individual nozzles
  • F01D9/023—Transition ducts between combustor cans and first stage of the turbine in gas-turbine engines; their cooling or sealings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
  • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
  • F23R3/002—Wall structures

Definitions

• the present invention refers to a device for conducting a hot gas into a rotor machine, wherein the hot gas is surrounded by a fluid, which has a different pressure and a different temperature relative to the gas, and the device comprises means for separating the gas and the fluid.
• Such devices are known in connection with gas turbines where a hot gas, for example a flue gas from a combustion chamber, is conducted into the turbine to thereby operate the latter.
• the gas turbine in its turn may be used to operate a generator and/or a compressor.
• PFBC- plants pressurized fluidized bed combustion
• the compressor operated by a gas turbine, is used to compress air which thereafter is conducted into the combustion chamber.
• a coaxial conduit is provided in the inner channel of which the gas flows to the gas turbine and in the outer channel of which, which channel is coaxial with and surrounds the inner channel, the compressed air is permitted to flow from the area of the gas turbine inlet to the combustion chamber.
• the device according to the present invention is particularly advantageous in a case as described above, it will hereafter, in an exemplifying but not in a limiting manner, be described with reference to this application.
• PFBC-plants where a hot gas is conducted into a gas turbine, it is desirable that the device, the so-called gas collector, which conducts the gas into the turbine, is not cooled by the medium which surrounds the latter so that cooling of the hot gas is thereby achieved, which would result in a decrease of the power of the plant.
• a pressure difference exists between the gas which is conducted into the turbine and the compressed air which is conducted from the compressor to the combustion chamber.
• the device which conducts the hot gas into the gas turbine thereby also has the purpose to carry the mechanical load which this pressure difference gives rise to at the means which are used for separating the gas and the fluid, i.e. the compressed air.
• a wall is used for separating the gas and the surrounding air, wherein this wall is provided to both conduct the gas into the gas turbine and to carry the pressure difference mentioned above.
• This wall of the gas collector has to be isolated from the compressor air in order to prevent cooling of the hot gas. It thereby assumes the temperature of the hot gas, which consequently results in that it becomes softer, loses carrying capacity and in some cases has a problem in carrying the load which the pressure difference gives rise to.
• the problem is solved by accurate adaptation of the wall thickness of the gas collector to the conditions which will prevail in the area of the same. However, the problem is accentuated with increasing size of the gas turbine and the gas collector and very large wall thicknesses may be necessary in order to guarantee the demand that the gas collector is able to carry the pressure difference.
• the object of the invention is to provide a device, which permits a hot gas to be conducted into a rotor machine while cooling of the hot gas is minimised at the same time as it has a good ability to carry the loads to which it is subjected due to a pressure difference which exists between the hot gas and a fluid which surrounds the gas.
• the means which separates the gas and the fluid comprises an inner wall, suitable to conduct the gas into the rotor machine, and a partition wall, located outside of the inner wall, suitable to carry substantially the whole pressure difference between the gas and the fluid.
• the inner wall may thereby be permitted to adopt the same temperature as the gas since it has not any carrying function.
• the hot gas which is conducted into the rotor machine and which thereby will come into contact with the inner wall is thereby not subjected to any cooling effect from the wall.
• the means which separates the gas from the fluid comprises a heat insulating layer. It is thereby possible to isolate the partition wall from the hot gas, which in turn has the advantage that the temperature of the partition wall may be kept at such a low level that its mechanical strength remains such that it with reliability may carry the mechanical loads to which it is subjected. Furthermore, with such a heat insulating layer it is possible to avoid that the partition wall to any greater extent has a cooling effect on the hot gas.
• a space is arranged between the inner wall and the partition wall and the device comprises a passage, which permits that the gas is given access to the space.
• a gas pressure which is substantially the same on both sides of the inner wall is thereby achieved, which wall consequently does not need to withstand any mechanical load worth mentioning .
• the heat insulating layer is attached to the inside of the partition wall and the device comprises a protective layer suitable to shield the heat insulating layer from heat radiation from the inner wall.
• the carrying function of the partition wall is thereby guaranteed at the same time as it is avoided that the heat insulating layer is exposed to heat radiation, which could destroy the same and thereby result in a reduced function of the device.
• the passage is arranged to permit the gas to quickly access and leave the space.
• This aspect is in particular important in connection with the quick pressure changes which for example arise at quick disconnection of load, for example in connection with gas turbine trip.
• the fluid has a higher pressure than the gas
• the device comprises an outer wall and a channel for the fluid is defined between the partition wall and the outer wall.
• the device thereby forms a coaxial conduit of the kind which advantageously is used in, for example, PFBC-plants.
• the gas is flue gas from a PFBC- combustion chamber and the fluid is air which has been compressed in a compressor and which via a coaxial conduit is conducted from the compressor to the combustion chamber.
• Fig 1 is a schematic cross sectional view of the device according to the invention at the inlet to a rotor machine
• Fig 2 is an enlarged cross sectional view of a portion of the device according to Fig 1
• Fig 3 is a diagram which approximately shows a temperature curve across the cross section in Fig 2.
• a device for conducting a hot gas into a rotor machine is shown.
• the hot gas is constituted by a particle containing flue gas from a PFBC-combustion chamber, wherein the gas has a temperature of about 850°C.
• the rotor machine is constituted by a gas turbine, which among other things operates a compressor from which a compressed fluid in the form of air is conducted to the PFBC-combustion chamber.
• the conveyance of gas to the rotor machine and compressor air to the PFBC- combustion chamber, respectively, takes place in a manner known per se by the use of a so-called coaxial conduit, which, as is shown in Fig 1 , extends from the area of the inlet into the rotor machine.
• the device comprises means 1 , 2, 3, 4, which separates the gas and the fluid.
• These means comprises an inner wall 1 , suitable to conduct the gas into the rotor machine and a partition wall 2, located outside of the inner wall 1 , suitable to carry substantially the whole pressure difference between the gas and the fluid.
• the inner wall 1 is tubular and defines a central gas channel 1 1 .
• the partition wall 2 is also tubular and provided outside of the inner wall 1 .
• the gas pressure is about 14 - 16 bar while the fluid pressure is about 16 - 18 bar.
• the inner wall 1 is arranged to have substantially the same temperature as the gas. This is made possible in that a space 5 is arranged between the inner wall 1 and the partition wall 2 and in that the device comprises a passage 6, which permits that the gas is given access to the space 5. Consequently, the inner wall 1 is both on the inside and on the outside surrounded by the gas. During normal operation, a significant flow of gas takes place inside of the inner wall 1 , while the gas which is present in the space 5 outside of the wall 1 is substantially stationary.
• the mass flow in the central gas channel 1 1 is about 400 kg/s and the flow rate is about 70 m/s.
• the means comprises a heat insulating layer 3.
• the heat insulating layer 3 covers substantially the whole extension of the inside of the partition wall 2 and works as a lining.
• a protective layer 4 is provided on the inside of the heat insulating layer 3 the purpose of which is to shield the layer 3 from heat radiation from the inner wall 1 .
• the protective layer 4 is by means of fastening members 7 fixed in its position, wherein the fastening members 7 here comprise pins or bolts, which penetrate through both the protective layer 4 and the heat insulating layer 3 and which in their one end are attached to the partition wall 2 and at their other end comprise nuts or locking washers 8 for the fixation of the protective layer 4.
• the gas which is present in the space 5 has, as well as the gas which flows inside of the inner wall 1 , a temperature of about 800-850°C.
• the fluid which flows in an annular channel 10 outside the partition wall 2, has a lower temperature than the gas.
• the temperature of the fluid near the partition wall 2 is about 300°C, which is also clear from the temperature curve in Fig 3, which approximately shows the different temperature levels which are the case in the partition wall 2, the heat insulating layer 3, the protective layer 4 and the inner wall 1 at the given values of the gas temperature and the fluid temperature.
• the device also comprises an outer wall 9 which defines a channel 10 between the outer wall 9 and the partition wall, in which channel the fluid is meant to flow.
• the outer wall 9 is provided to carry the whole pressure of the fluid, i.e. a pressure of about 16 - 18 bar. Due to the design of the device, the outer wall 9 is relatively cold which is an advantage for its pressure carrying capacity and therefore it does not need to be over-dimensioned with regard to the influence of temperature.
• the inner wall 1 is provided to carry the loads to which it is subjected in connection with maximum gas temperature and in particular the transient pressure difference, which arises between the space 5 and the central gas channel 1 1 when load disconnection occurs and the pressure quickly decreases in the central channel 1 1 .
• An important aspect hereby is that the passage 6 is provided to permit a quick flow of gas from the space 5 to the channel 1 1 .
• the passage 6 is arranged such that, during normal operation and applied loads, i.e. when gas is initially supplied to the rotor machine, it permits as few particles as possible to pass with the gas when the gas fills the space 5.
• the different walls and the insulation comprise suitable materials for the purpose.
• the pressure carrying partition wall may comprise a low alloy-treated steel
• the heat insulating layer may comprise a ceramic fibre material
• the protective layer 4 may comprise a sheet of austenite stainless steel.
• the inner wall 1 which ought to be both resistant to wear, with regard to the influence of particles, and resistant to high temperatures, suitably comprises a material based on nickel, for example Hastaloy.
• coaxial conduit used here not only refers to conduits with identical, coincident axis but refers to all conduits where an outer channel, such as the channel 10, surrounds an inner channel, such as the channel 1 1 .

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20410748

Family Applications (1)

Country Status (2)

Citations (4)

• 1998
  • 1998-03-27 SE SE9801066A patent/SE511692C2/sv not_active IP Right Cessation
• 1999
  • 1999-03-19 WO PCT/SE1999/000441 patent/WO1999050544A1/en active Application Filing

Patent Citations (4)

Also Published As

Similar Documents

Legal Events