CZ299596A3 - Means for regulating flow of gaseous combustion products in power plants with combined mode of operation - Google Patents

Abstract

A fume deflecting damper for combined-cycle power stations. The damper consists of a shutter (10) hinged to shaft (11) provided only for supporting said shutter (10). The shutter (10) is moved by means of tie-rods (13) hingedly connected to the lower portion of the shutter (10), preferably via ball joints (15), and extending through a sloping side wall (22) of the fume duct (21) in the damper body (2).

Description

The invention relates to an improvement of the arrangement of the means for controlling the flow of flue gas in power stations operating in the so-called combined mode.

BACKGROUND OF THE INVENTION

Combined-mode power plants are equipped with a combustion turbine driving an alternator, a waste heat boiler producing steam, and a steam turbine driving a second alternator.

In the boiler, steam is used to produce waste heat generated by the combustion of gas, which is a large volume and a high flue gas temperature.

Combined-mode power plants have a high output, start-up is very fast and relatively little polluting.

In this type of equipment, the diversion of the flue gas flow from the combustion turbine is controlled in a by-pass, which is installed in front of the boiler, so that the hot flue gas can be discharged directly to the atmosphere or to the boiler as required.

In this way, the independence of the gas and steam modes is ensured, while at the same time the advantages of the combustion turbine, which is an extremely fast start-up and a short commissioning time, can be exploited.

the mode is not or cannot be operating in this case if the steam combustion turbine is in the open mode, ie. with direct exhaust of flue gases into the atmosphere.

In this arrangement, the bypass duct must be provided with a control means which deflects the flow of the hot flue gas.

It should be noted that combustion turbine manufacturers tend to offer ever more powerful machines, which currently range from 100 MW to 230 MW and can be expected to achieve even higher performance in the near future.

In such conditions fluently slept i ny flows speed 100 to 150 km / h and their temperature reaches to 650 ° C. Arrangement of the resource regrulation gas flow flue gas is technical difficult. Must meet many conditions. especially absolute impermeability, fast and for all circumstances reliable and maneuverability. Operating conditions means are

At the same time, it is very demanding: it is a medium of large dimensions (of the order of 6m x 7m x 7m), its parts are exposed to considerable temperatures, high thermal shock, high velocities and turbulence of the flue gas.

Known industrial control means have certain advantages and disadvantages.

There is known a so-called snap-in arrangement in which one control means is installed on the bypass duct and the other on the flue gas duct to the boiler.

Each such means is provided with substantially several regression flaps which rotate in axis and open or close the respective flue gas duct.

Techniques of this type divert flue gas flow very well, but this characteristic is not essential in the combined mode of operation. The disadvantage of such an arrangement is the problem of ensuring perfect impermeability of the flue gas, in particular with respect to the total length of the profile to be sealed, and the risk of accidental closure of both control means at the same time, which would cause considerable material damage.

For these reasons, such means are not practically applicable in combined-mode power plants and find application in industry where the regression of the flue gas flow is technologically justified.

There are also control means provided with a simple regression flap which is mounted on the drive shaft. The flap closes either the flue gas duct to the boiler or closes the flue gas inlet to the bypass duct.

These control dampers have very good sealing properties, ensure maximum performance of the combined mode of the aforementioned dampers and are usable on plants with an output of up to 120 MW.

However, the release flap is subjected to a high pressure of gaseous flue gas in the first phase of opening and substantially up to its halfway. This pressure first prevents, then suddenly facilitates its opening, generating considerable vibration and the shaft, including the entire damper control system, is heavily stressed. For this reason, the means of regulation and its flap must be relatively massive. A disadvantage is also the technical limit of the height of the damper, which prevents its use in modern and high-performance combustion turbines.

In the meantime, however, this type of control means is by far the most widely used in combustion turbines of limited power.

In view of the above-mentioned drawbacks, control means provided with a single flap with a tilting shaft have been proposed (it is referred to as To ^ gTe).

In this embodiment, the flap is mounted on a support shaft and is controlled by an additional tubular-shaped guide shaft that is coupled to the flap by rods.

The control damper thus arranged has the same advantages as direct control and is better adapted to the efficient combustion turbines.

Its design / Sak does not prevent vibrations which are somewhat less than those of the device described above.

In addition, the fact that when rotating a shaft that is greater than 120 °, it is difficult to introduce a hydraulic guide shaft must be large in diameter and considerable because when placed in the bypass duct, it is exposed to considerable mechanical and thermal loads during handling.

There are also control means provided with three flaps which independently close one another of the passage of the flue gas. These means are suitable for high performance internal combustion turbines, but are characterized by lower sealing properties (due to the length of the profile to be sealed), complicated control of the three shafts and unreliability for possible accidental opening, eg in the event of a power failure.

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WO 88/09458 discloses a flap actuation mechanism for opening and closing the high temperature flue gas passage at which both the shaft and the rods are subjected to a thermal load that can cause them to deform and consequently damage the seal of the flap. The flexibility of the elastic joints in this case is insufficient and cannot compensate for the deformations caused by deflection of the flap.

US-A-3 605 811 discloses a control means provided with a slide or a compressed air distribution slide. A disadvantage of this composition is the insufficient sealing ability at high temperatures.

The valve dimensions are very small. The sliding mechanism requires precise machining of the sliding surfaces to align the contact surfaces. For this reason, the use of the gate valve in an environment of high temperatures and a large volume flow of flue gas is inappropriate.

In addition, it is obvious that this environment also affects the lifter actuating the slide since its temperature is subject to considerable temperature.

EP-A-0 533 282 discloses a flap control mechanism mounted on a hinge-type shaft. This technique is also intended for small-size butterfly valves and for smaller power turbines. Increasing the dimensions of the flap would result in an increase in the torque of the shaft motor and an overall oversizing of the mechanism. This would not solve the problem of vibration when handling the flap.

US-A-4,354,528 discloses a regression means for a completely different application (dust collector) in which a sealing requirement is not preferred. The flap guide rod passes through the outlet tube and cannot be subjected to high temperatures as it could become stuck in the tube.

FR-A-2 305 666 discloses a flue gas control means in a flue gas duct which is not suitable for combustion turbines. In this document, the flue gas flow is described as irregular, articulated to continuous. Control of the damper by the rope system is problematic due to the working environment. When the flap is set to a certain position, flue gas turbulence and aerodynamic pressures of varying intensity and direction occur in front of the flap face. This generates vibrations which may intensify after the subsequent vibration of the flexible damper control system and, in the worst case, cause the entire mechanism to be deformed. The actuation of the damper by the rope system does not ensure precise positioning of the damper, which essentially depends on the equilibrium position of the flue gas pressure on the damper front wall and the elasticity of its actuation system.

The essence of the invention

SUMMARY OF THE INVENTION The present invention provides a means for controlling the flow of flue gas, the technical improvements of which can be applied to existing control means and the arrangement is also suitable for future, more powerful devices, which largely removes the drawbacks of the prior art.

In particular, the composition according to the invention has the following advantages: good sealing properties, control not exposed to high temperatures, simple arrangement of the control damper mechanism and the possibility of its installation in wide exhaust ducts of powerful turbines.

To achieve these parameters, it was necessary to arrange the device in such a way that the control flap control elements were protected as much as possible from thermal shock.

The solution according to the invention is characterized in that the control means is provided with a single regression flap which is inserted into the shaft and, as in the Togrgrle embodiment, the shaft only carries the flap.

The damper is controlled by means of rods which are inserted into the spherical pins © at the bottom of the damper. The rods pass through the bevelled side wall of the flue gas duct outside the control means body.

The tie rods are connected to a transverse sliding beam which is controlled by suitable means mounted on both sides of the body of the control means.

The sliding beam is controlled by two jacks, whose linear movement allows the flap to be opened or closed by pushing the sliding beam substantially vertically in the sliding beam guideways.

In order to significantly reduce the pressure loss of the flue gas in the open mode and to reduce noise when the flue gas direction changes sharply, special measures are provided according to the invention.

The control flap is deflected with respect to the horizontal in the channel closed position towards the boiler, i.e. in the open mode operation position.

This facilitates the evacuation of the flue gas in the open mode operation to the chimney.

The upper corner of the side wall towards the bypass channel is tapered and is substantially parallel to the control flap in its closed position.

The bottom of the control means is provided with a recess in which the bottom edge of the flap rests.

All these measures contribute to the elimination of turbulence, which could cause pressure losses and noise. The bevelled corner facilitates the passage of the rods through the side wall of the control means.

The damper consists of a cylindrical frame, whose resistance to torsional stress has been verified. The frame ensures great stability of the whole set. Sealing surfaces fitted with single or double sealing joints and thermal insulation are embedded in the frame. The surfaces are connected to the frame in a flexible manner which allows free expansion of the individual elements of the control flap.

Sealing joints are classic type with flexible metal strips, which are around the sealing surfaces in one or two rows, possibly with air injection, ensuring a perfect impermeable flue gas.

The passage of the rods through the body of the control means is sealed by a labyrinth seal, which may be provided with sealing segments so as not to impede the movement and displacement of the rods transversely to the body of the device. The lateral displacement of the rods thus arranged is relatively small.

The shaft in this embodiment only carries the regulating flap. The shaft is not driven and its ends do not pass through the body of the control means. No other driven shaft (as in the Toggle embodiment) exists in the device of the invention, which eliminates sealing problems at this level.

The flap support shaft is also mounted in ball joints.

The body of the control means is similarly provided with external or internal thermal insulation.

The wiper system, including jacks, can be mechanical or hydraulic. In the case of hydraulic control, a regression device is provided for a control system to ensure synchronized operation of both jacks.

In addition, the regression device may be provided with a cover plate which is installed at the outlet of the device towards the boiler. The cover plate ensures complete impermeability of the flue gas and temperature and allows the boiler to be connected and / or maintained while the combustion turbine is running in the open mode.

Compared to the prior art, the device has the following significant advantages:

- smaller, shaft dimensions that only support the flap and are not driven.

- the linkage pulls or pushes the flap and is therefore lightly loaded: heavy parts that are not resistant to high temperatures are excluded from the device.

- the pressure loss of the flue gas when it is discharged by the bypass duct is small when the combustion turbine is running: the performance of the open-mode turbine is significantly higher.

- the dimensions of the installation are suitable for each combustion turbine, irrespective of its power and temperature of the flue gas.

the regression flap is mounted at four points with limited clearance and is therefore stable.

- there is no flue gas leakage around the shaft because the shaft does not pass through the device body. This results in efficiency gains and reduced risk of hot flue gas leakage.

- noise is significantly reduced, there is no need to add an additional silencer to the device.

Over-lie pictures on the vykrege

The invention will be explained in more detail in the drawing, in which:

Fig. 1 is a schematic diagram of a combined mode power plant;

FIG. 2 is a side view of a control means according to the invention; the regulating flap is in the position of opening of the bypass channel and diversion of the flue gas flow;

FIG. 3 is a side view of the control means showing both flap positions;

FIG. 4 is a view of the regression means in the direction away from the combustion turbine;

FIG. 5 is an overall side view of the control means; flue gas from the combustion turbine stream! when viewed from the right;

Fig. 6 - detail of the connection of the control flap to the shaft (detail A from Fig. 3);

Fig. 7 - detail of the rod seal in the passage through the body of the bypass channel (detail B of Fig. 3).

An example of an embodiment of the invention

Figure 1 schematically illustrates a combined mode power plant. The power plant is equipped with a combustion turbine X driving an alternator, a boiler 2 in which the waste heat is used to produce steam, the expansion of which is used to drive a steam turbine to drive! second alternator.

The control means 2 directs the flue gas either directly through the chimney 4 to the atmosphere or to the boiler 2, from where it exits to the atmosphere through the chimney 5.

In particular, the control means is characterized in that it is provided with a single control flap 10 which is inserted into the shaft 11, which only carries it.

The flap is actuated by rods 3 which are connected to the flap in its lower part by ball pins 15. The rods extend outside the body of the control means 2 through the bevelled side wall 22 of the flue gas duct 21.

The upper ends of the rods are mounted in a transverse sliding beam 3X, which is controlled by suitable means located on both sides of the control means. These means are in this example hydraulic jacks 35.

The sliding beam 31 slides in the guide tracks 33.

The control damper may be moved from an almost horizontal position 10 (FIG. 3) when it closes the flue gas duct to an inclined position 10 (FIG. 3) where it is deflected relative to the horizontal. The corner 40 in the direction of the bypass channel is significantly tapered for the reasons given in the description.

The bottom of the control means is provided with a recess 41 into which the lower edge of the flap fits. This arrangement avoids the turbulence that would occur if its bottom were provided with a support projection. The control flap is made of a durable tubular frame in which the sealing faces are inserted.

Sealing joints are of the classic type.

Sealing of the rods 13 at the point of their passage through the body, respectively. its bevelled wall 22. According to the invention, a cuff seal 43 is provided which allows the rods to move laterally relative to the body of the control means 2.

The longitudinal movement of the rods relative to the body of the control means is made possible by a labyrinth seal with sealing segments arranged so as not to impede the longitudinal displacement of the rods.

The arrangement of the rods allows the desired movement of the regulating flap (from position 10 to positions' / 10), the transverse displacement of the rods being precisely defined.

It should also be pointed out that, unlike the prior art, no driven shaft is installed in the hot flue gas stream (smoke) leaving the bypass channel.

Claims (6)

The flue gas flow control means in combined-mode power plants, provided with a control flap (10) inserted in the shaft (11) which only carries the control flap (10), characterized in that the control flap (10) is actuated by rods (13) which they are mounted in the lower part of the regression flap preferably in the spherical pins (15) and extend outside the body of the control means (2) through the bevelled side wall (22) of the flue gas duct (21). Control means according to claim 1, characterized in that. That the tie rods (13) are connected to a transverse sliding beam (31) which is controlled by suitable means (35) located on both sides of the body of the control means (2). Control means according to claim 2, characterized in that the sliding beam is controlled by two jacks (35) whose linear movement allows the regression flap (10) to be moved to the closed or opened position by pushing the sliding beam (31) substantially vertically in the guide tracks (33) of the sliding beam (31). A control system according to any one of claims 1 to 3, characterized in that. That the regression flap (10) is deflected relative to the horizontal in the channel closed position towards the boiler and that the corner (40) in the direction of to the bypass duct is markedly tapered in order to when sudden changing the direction of flow gas flue gas v open working regime decreased t1akové losses and noise traffic. 5. Preylp eeU / c refractory according to any of the claims 1 to 4, 1 c i se t í m. that the regression flap (10) is made of a tubular frame into which sealing surfaces provided with single or double sealing joints and thermal insulation are inserted, the sealing surfaces being inserted into the frame in a flexible manner so as to allow free thermal expansion between the individual flap elements. Against Acclfik The 2-stage control according to any one of claims 1 to 5, characterized in that the sealing of the rods in the vapor passageway through the device body is performed by a labyrinth seal provided with possible sealing segments so as not to impede the movement and displacement of the rods transversely . The control according to any one of the features is mounted in ball joints. of claims 1 to 6, characterized in that the shaft (11) Twk The control device according to any one of the preceding claims, wherein the control device is internally insulated and insulated. The body of the composition or thermally externally Protiřtdtli 9.? ^. _A control system according to any one of claims 1 to 8, characterized in that it is provided with a hydraulic control means with a control system which continuously ensures the trouble-free and synchronized operation of the two jacks. 10. Controls according to any of claims 1 to 9, characterized by with it. that Yippee provided cover plate. i n with t a1 on output equipment regulation towards the boiler, which ensures perfect impermeability of gaseous flue gases and temperature.