CN105673091B - A kind of seal clearance selfregulated glandpacking device with gas suspension effect - Google Patents

Abstract

A sealing gap self-adjusting seal device with gas suspension effect, comprising a plurality of seal arcs, auxiliary sealing strips and springs arranged between the seal arcs; seal teeth are arranged on the seal arcs; The sealing teeth cooperate with the rotor surface to form a sealing gap, and the high-pressure side steam seal tooth gap is larger than the low-pressure side steam seal tooth gap; the middle position of the steam seal arc section is respectively provided with a high-pressure steam vent slot and a low-pressure steam vent slot, and the back cavity of the steam seal arc section is respectively The high-pressure side and the low-pressure side are connected, and the high-pressure steam and low-pressure steam are blocked by the auxiliary sealing strip. The sealing gap self-adjusting steam seal with gas suspension effect of the present invention not only realizes the automatic change of the sealing gap according to the two states of steam turbine startup and shutdown and normal operation, but also automatically adjusts the sealing gap according to the position of the rotor in real time, and keeps the sealing gap in the running state all the time. Within the design range, it maintains good sealing performance for a long time, and also has the function of reducing the vibration amplitude of the shaft system, which can comprehensively improve the safety and economy of steam turbine operation.

Description

A Self-adjusting Gas Seal Device with Sealing Gap Effect

technical field

The invention relates to a sealing gap self-adjusting steam seal device with gas suspension effect, which belongs to the field of steam turbine steam seals.

Background technique

As one of the three main equipments of a thermal power plant, the efficiency of the steam turbine greatly affects the economic benefits of the power plant. It is an effective way to improve the operating efficiency of the unit through technical transformation of equipment and improvement of unit operation mode. The design and manufacturing technology of the flow part of the steam turbine is becoming more and more perfect, and the loss of steam leakage has become the main factor restricting the improvement of the efficiency of the steam turbine (accounting for more than 60% of the heat efficiency loss of the flow of the whole unit), so the performance of the steam seal is improved to reduce the leakage of the steam flow of the steam turbine The loss is very important to improve the operating efficiency of the unit.

In the prior art, the comb-tooth seal is the most widely used seal technology. The axial width of a single comb-toothed steam seal is generally designed to be no more than 60mm, and the corresponding number of equivalent teeth is no more than 10 (for high and low-toothed steam seals, one high tooth is recorded as one equivalent tooth, and the distance between two high teeth A low tooth is also recorded as an equivalent tooth, further explanation, no matter how many low teeth there are between two high teeth, it is recorded as an equivalent tooth), and the gradual pressure reduction is realized through multiple steam seal teeth in the axial direction to reduce leakage .

The outstanding advantages of the comb-tooth seal are low cost, safe use, and relatively stable sealing effect, but this stability is a low level of stability. Generally, a radial clearance of 0.5-0.8mm should be reserved for the installation of the comb-toothed steam seal. Even so, it is still impossible to avoid excessive wear caused by factors such as the increase in the amplitude of the overcritical speed during the start-up and stop of the steam turbine, and the deformation caused by uneven heating of the cylinder. Once rubbed, the gap is permanently enlarged. Over the years, how to reduce and maintain a small seal gap has become a difficult problem for those skilled in the art.

The operation of steam turbines has its own particularity. Research reports in recent years, such as "Study on the Selection of New Types of Steam Turbines for Various Parts of Steam Turbines" jointly published by Huadian Electric Power Research Institute and Shanghai Steam Turbine Works, pointed out: "The way out of the steam seal can be based on the The change of the operating state changes the seal clearance. A more scientific steam seal should automatically change the seal clearance according to the two states of startup and shutdown of the steam turbine unit and normal operation, and at the same time meet the safety clearance and economic clearance required in the two states. Generally speaking, the safety clearance of a steam turbine is 3 to 5 times the economic clearance.”

In the article "Study on the Standardization of the Optimum Combination Scheme for Steam Turbine Seal Selection", the following conclusions were also drawn:

state duration Clearance requirements Purpose Start and stop status short The dynamic and static clearance of each part should maintain a large safety clearance Start and stop smoothly Grid-connected running status long The dynamic and static gaps of each part should be kept at a small economical gap cost-effective operation

In the prior art, a typical technology capable of realizing the above-mentioned gap self-adjusting characteristic is the Braden seal technology. The Braden steam seal cancels the spring leaf on the back of the traditional comb-toothed steam seal, and replaces it with at least four circumferential bolt springs installed at the end face of each steam seal arc section, and mills a spring on the back of each steam seal arc section. The steam inlet groove makes the pressure on the back of the arc section of the steam seal approximately equal to the pressure on the upstream high pressure side. During the startup and shutdown phase of the steam turbine, the pressure difference between the upstream and downstream of the steam seal is small, and under the action of the circumferential spring, the steam seal is fully opened, and a large safety gap is maintained between the steam seal and the rotor, generally 2 to 4mm; In the normal operation state of the steam turbine, the pressure difference between the upstream and downstream of the steam seal increases, and the steam entering the back of the arc section of the steam seal from the steam inlet groove generates a large centripetal closing force, and the steam seal closes accordingly, and the gap between the steam seal and the rotor is maintained. Smaller economic gap, generally 0.3~0.5mm, to achieve high-efficiency sealing.

However, the industry has mixed opinions on the actual application effect of the Braden seal. It is generally believed that the possible problems of the Braden seal include at least: 1. Spring quality problems; 2. The arc of the seal cannot be completely closed; 3. After the Layden steam seal is closed, there is still a problem similar to that of the traditional comb tooth seal, once the gap is permanently enlarged once it is rubbed.

In addition, steam flow excitation is easy to occur on the high-pressure rotor of the steam turbine. Existing studies have shown that steam seal vibration excitation force is the main cause of the above phenomenon. Due to the dynamic eccentricity of the rotor, the circumferential distribution of steam pressure in the steam seal is uneven, and with the circumferential flow of steam, a resultant force perpendicular to the eccentric direction of the rotor is generated, which promotes the rotor whirl, and at least causes the seal teeth to rub and increase Leakage of large steam seals will cause rotor instability and seriously threaten the safe operation of the unit.

Contents of the invention

In order to solve the above-mentioned problems in the prior art, the present invention provides a self-adjusting steam seal device with a gas suspension effect.

In order to solve the problems of the technologies described above, the technical scheme adopted in the present invention is as follows:

A sealing gap self-adjusting seal device with gas suspension effect, including multiple seal arcs, auxiliary sealing strips and springs arranged between the seal arcs; seal teeth are arranged on the seal arcs, the overall The number of equivalent teeth is not less than 10; the sealing teeth cooperate with the rotor surface to form a sealing gap, and the high-pressure side sealing tooth gap is larger than the low-pressure side sealing tooth gap; the middle position of the sealing arc section is respectively equipped with a high-pressure steam vent groove and a low-pressure vent. The steam tank and the cavity on the back of the steam seal arc section are respectively connected to the high pressure side and the low pressure side, and the high pressure steam and low pressure steam are blocked by the auxiliary sealing strip.

As a conventional concept in this field, the seal arc section includes lugs, necks, seal bases and seal teeth connected in sequence from the outer ring to the inner ring in the radial direction, and the outer ring surface of the lugs is called a large back arc. The inner surface of the lug (that is, the surface opposite to the base of the steam seal) is called a small back arc; in application, the lug of the above-mentioned steam seal is matched with the wider part of the T-slot of the stator, and the neck and the T-slot of the stator are narrower. Part of the fit; the back cavity of the arc section of the steam seal refers to the cavity formed by the cooperation of the lug and the T-slot of the stator.

The above self-adjusting seal with gas suspension effect has a large number of teeth and a wide axial width. It is mainly used in bridges between high and medium pressures of steam turbines, speed-regulating stage blade tops, high-pressure first-stage diaphragms, and shaft ends. In the position where the pressure difference between the front and rear of the steam seal is high, such as the inner side, due to the high pressure difference between the front and rear of the steam seal, in order to reduce the leakage, these positions need to design more steam seal teeth. Tooth seal, the installation space is relatively large. Therefore, the single-channel steam seal of the present invention can replace the traditional multi-channel steam seal, and keep the number of teeth of the steam seal and the occupied space in the axial direction unchanged. Preferably, in the reconstruction project, the single steam seal of the present invention replaces the two traditional steam seals.

The seal teeth of the self-adjusting seal with a gas suspension effect include a high-pressure side seal tooth and a low-pressure side seal tooth. The distinction between "high pressure" and "low pressure" is bounded by the auxiliary sealing strip. The upstream of the auxiliary sealing strip is defined as the high pressure side, and the downstream of the auxiliary sealing strip is defined as the low pressure side. On the above-mentioned high-pressure side, the pressure of the back arc (outer arc surface) of the seal arc section is greater than the pressure on the inner wall (inner arc surface) of the seal base, thus generating a closing force directed to the rotor surface; on the above-mentioned low-pressure side, the back arc (outer arc surface) of the seal arc section Surface) pressure is less than the pressure of the inner wall (inner arc surface) of the seal matrix, so the opening force away from the rotor surface is generated. The relative size of the above closing force and opening force mainly depends on the axial width of the high pressure side and the low pressure side and the pressure difference borne by the high pressure side gland teeth and the low pressure side gland teeth respectively. The above-mentioned high-pressure side axial width is greater than the low-pressure side axial width, the number of the above-mentioned high-pressure side gland teeth is greater than the number of low-pressure side gland teeth, and the gap between the high-pressure side gland teeth is larger than the low-pressure side gland gap, preferably with a difference of 0.1～ 0.8mm. When the gland seal gaps are large, for example, the high pressure side gland gap is 2.2mm, and the low pressure side gland gap is 2mm, then the ratio of the high pressure side gland gap to the low pressure side gland gap is close to 1; When the gland seal gap is reduced, the reduction value of the high pressure side gland gap and the low pressure side gland gap are the same, for example, the high pressure side gland gap is 0.3mm, the low pressure side gland gap is 0.1mm, but the high pressure side gland gap The ratio of backlash to low pressure side seal backlash will become 3. It is precisely because of the significant change in the ratio of the clearance between the high-pressure side seal teeth and the low-pressure side seal teeth that the pressure difference between the high-pressure side seal teeth and the low-pressure side seal teeth changes significantly. Therefore, for the steam seal of the present invention with a given structure, the relative magnitudes of the above-mentioned closing force and opening force will change significantly with the change of the gap between the teeth of the seal. Under the condition of a certain steam seal tooth gap, the above closing force is equivalent to the opening force, and this gap is the design sealing gap. If the current sealing gap is significantly larger than the design sealing gap and the closing force is much greater than the opening force, the steam seal of the present invention will automatically approach the rotor surface to reduce the sealing gap to reduce leakage; if the current sealing gap is significantly smaller than the designed sealing gap, the opening force is much greater than the closing force , the steam seal of the present invention will automatically stay away from the rotor surface, and the gap will be enlarged to avoid rubbing. It is the above-mentioned characteristics that can ensure that the arc section of the seal is always suspended on the rotor surface, neither will increase leakage due to an excessively large seal gap, nor will it cause friction due to an excessively small seal gap.

Further explanation, since the arc section of the steam seal is still subject to a large axial thrust under the action of the pressure difference, it is necessary to overcome the static friction caused by the axial thrust when it is close to or away from the rotor surface. Only when the resultant force of the above closing force and opening force is greater than the static friction When the pressure is high, the arc section of the steam seal can realize self-adjustment. In addition, this feature increases the stability of the arc section of the seal and avoids frequent adjustment of the seal gap.

Since the change and maintenance of the sealing gap of the steam seal of the present invention are driven by pressure, when the steam turbine is in the start-up and shutdown state or the extremely low load state, there is no pressure difference between the front and rear of the steam seal arc or the pressure difference is too small, and the distance between the steam seal arc and the rotor The relative position will be mainly affected by gravity, which will cause the local sealing gap to be too small and may cause rubbing. In order to avoid friction between the steam seal and the rotor in the start-stop phase and the extremely low load phase, springs are added between the arc sections of the steam seal to keep the initial seal gap at the maximum value.

The above-mentioned springs arranged between the arc sections of the steam seal are helical compression springs or arc-shaped leaf springs. Preferably, the springs arranged between the arc sections of the seal are arc-shaped leaf springs. By selecting a superalloy plate with a suitable thickness, it is easier to manufacture an arc-shaped leaf spring that meets the design requirements.

The above-mentioned arc-shaped plate spring is clamped on the end face of the arc section of the steam seal. In order to facilitate installation and debugging, the arc-shaped leaf spring is fixed with screws to prevent it from falling off.

The edge of the above-mentioned arc-shaped leaf spring close to the rotor is basically flush with the lower teeth of the seal teeth, but not higher than the lower teeth. With the above design scheme, the arc-shaped leaf spring can also block the circumferential flow of steam, which is conducive to providing more stable closing force and opening force, and can also suppress the excitation of steam flow and reduce the vibration amplitude of the shaft system.

The applicant found through research that when the rotor is eccentric relative to the steam seal ring due to vortex, the rotor surface will generate a radial force opposite to the eccentric direction of the rotor due to the pressure difference, which will increase the damping of the shaft system, thereby reducing vibration and improving the performance of the steam turbine. Shaft stability.

Preferably, the above-mentioned steam seal tooth clearance on the high pressure side is 0.1 to 0.8mm larger than the low pressure side steam seal tooth clearance, and the steam seal teeth on the high pressure side gradually shrink along the steam flow to the sealing gap, and the steam seal teeth on the low pressure side flow along the steam flow to the sealing gap constant. By adopting the above-mentioned design scheme, factors such as processing errors and adjustment deviations have very little influence on the working characteristics of the steam seal of the present invention.

In order to reduce the leakage of high-pressure steam on the back of the steam seal of the present invention to the low-pressure side, the auxiliary sealing strip at least includes a C-shaped seal arranged on the inner surface of the neck of the steam seal. The opening of the C-shaped seal is connected to the high-pressure side and self-expands under the pressure difference Tight for a good seal.

In order to further improve the reliability of the back seal of the steam seal, the auxiliary sealing strip also includes an O-shaped seal arranged on the inner side of the steam seal lug. A small hole is opened on the inner side of the O-shaped seal. Once high-pressure steam enters, it will expand automatically under the action of pressure difference. Tight for a good seal. The function of the above-mentioned C-type seal is basically the same as that of the O-type seal, and the concept of redundant design is adopted to improve the reliability of the seal.

In order to facilitate installation and debugging, the above-mentioned C-type seal is divided into multiple arc segments, each steam seal arc segment corresponds to a C-type seal arc segment, and a riveting groove is provided inside the C-type seal installation groove to fix the C-type seal arc segment.

In order to facilitate installation and debugging, the above O-shaped seal is divided into two semicircles, which are respectively placed in the T-shaped grooves of the upper and lower cylinders, and are crimped with the inner surface of the steam seal lug.

The above-mentioned high-pressure steam vent groove and low-pressure steam vent groove are generally arranged in the middle of the arc section of the steam seal, and the specific shape is not limited, as long as they can be connected to the upstream and downstream of the steam seal respectively, but it is necessary to ensure that the steam vent formed in cooperation with the T-shaped groove The groove flow area is at least 50 mm ² .

The technologies not mentioned in the present invention refer to the prior art.

The sealing gap self-adjusting steam seal with gas suspension effect of the present invention not only realizes the automatic change of the sealing gap according to the two states of steam turbine startup and shutdown and normal operation, but also automatically adjusts the sealing gap according to the position of the rotor in real time, and keeps the sealing gap in the running state all the time. Within the design range, it maintains good sealing performance for a long time, and also has the function of reducing the vibration amplitude of the shaft system, which can comprehensively improve the safety and economy of steam turbine operation.

Description of drawings

Fig. 1 is a schematic diagram of a steam seal in an open state under the action of an arc-shaped leaf spring in Embodiment 1 of the present invention.

Fig. 2 is a schematic diagram of the steam seal in the closed state under the pressure difference in Embodiment 1 of the present invention.

Fig. 3 is a schematic structural view of the steam seal arc section in Embodiment 1 of the present invention.

Fig. 4 is a schematic diagram of the partial structure of the end face of the steam seal arc section in Embodiment 1 of the present invention.

Fig. 5 is a three-view view of the arc-shaped leaf spring of Embodiment 1 of the present invention.

Fig. 6 is a radial cross-sectional schematic view of the cooperation between the steam seal and the rotor and stator of the steam turbine according to Embodiment 1 of the present invention.

Fig. 7 is a schematic diagram of the relative magnitudes of the closing force and the opening force of the steam seal in the open state expressed by the area method in Embodiment 1 of the present invention.

Fig. 8 is a graph showing the variation trend of inter-gear static pressure along the axial direction (steam flow direction) when the ratio of the high-pressure side seal tooth clearance to the low-pressure side seal tooth clearance is different in Example 1 of the present invention. As the ratio increases, the closing force increases. Significantly reduced, while the opening force was significantly increased.

Fig. 9 is a graph showing the relationship between the gap between the teeth of the low-pressure side steam seal and the resultant closing force (closing force - opening force) according to Embodiment 1 of the present invention.

Fig. 10 is a radial cross-sectional schematic diagram of the cooperation between the steam seal and the rotor and stator of the steam turbine according to Embodiment 2 of the present invention.

In the above figures, 1 is the steam seal arc section, 2 is the rotor surface, 3 is the arc-shaped leaf spring, 4 is the screw, 5 is the high-pressure steam groove, 6 is the low-pressure steam groove, 7 is the C-shaped seal, 8 is the Stator, 9 is the rotor, 10 is the O-shaped seal, 11 is the size of the closing force expressed by the area method, 12 is the size of the opening force expressed by the area method; H is the high pressure side, L is the low pressure side; F1 is the direction of the closing force (along the rotor radial direction and close to the rotor surface), F2 is the opening force direction (along the rotor radial direction and away from the rotor surface direction), F3 is the axial thrust direction (along the rotor axial direction), f is the friction force direction (along the rotor radial direction direction, close to or away from the rotor surface); a is the pressure drop trend line along the axial direction (steam flow direction) when the ratio of the high-pressure side steam seal tooth clearance to the low-pressure side steam seal tooth clearance is 2.5/2.3, b is the high pressure The pressure drop trend line along the axial direction (steam flow direction) when the ratio of the side gland clearance to the low pressure side clearance is 0.8/0.6, c is the ratio of the high pressure side clearance to the low pressure side clearance d is the pressure drop trend line along the axial direction (steam flow direction) when d is 0.4/0.2, and d is the pressure drop along the axial direction (steam flow direction) when the ratio of the high pressure side seal tooth clearance to the low pressure side seal tooth clearance is 0.3/0.1 Pressure drop trend line, e is the pressure drop trend line along the axial direction (steam flow direction) when the ratio of the high-pressure side seal tooth clearance to the low-pressure side seal tooth clearance is 0.2/0.

detailed description

In order to better understand the present invention, the present invention will be further explained below in conjunction with the drawings in the embodiments of the present invention, but the content of the present invention is not limited to the following embodiments. Based on the embodiments of the present invention, other embodiments obtained by persons of ordinary skill in the art without creative efforts all belong to the protection scope of the present invention.

Example 1

As shown in Figure 1-9, a sealing gap self-adjusting steam seal device with gas suspension effect includes multiple seal arcs, auxiliary sealing strips and springs arranged between the seal arcs. There are multiple seal teeth on the seal arc section, a total of 8 high teeth and 16 low teeth (16 equivalent teeth in total), the axial width of the seal arc section is 104mm; there are 5 high teeth and There are 12 low teeth (11 equivalent teeth in total), the axial width of the high pressure side is 72.2mm; the low pressure side has 3 high teeth and 4 low teeth (5 equivalent teeth in total), and the axial width of the low pressure side is 31.2mm. The seal gears cooperate with the rotor surface to form a sealing gap. The design clearance of the high-pressure side seal teeth is 0.4±0.05mm, and the design clearance of the low-pressure side seal teeth is 0.2±0.05mm. Therefore, in the manufacturing stage, it is necessary to ensure that the high-pressure side steam seal The inner diameter of the seal gear is 0.4mm larger than the inner diameter of the low-pressure side seal gear (the high and low teeth on the high-pressure side are respectively 0.2mm shorter than the high and low teeth on the low-pressure side); from another perspective, when the tolerance is not considered, 16 equivalent teeth The design gaps are 0.4-0.4-0.4-0.4-0.4-0.4-0.4-0.4-0.4-0.4-0.4-0.2-0.2-0.2-0.2-0.2 in turn.

The above-mentioned high pressure side and low pressure side are blocked by auxiliary sealing strips. The auxiliary sealing strips are C-shaped seals, riveted on the inside of the neck of the steam seal, and the opening is connected to the high pressure side. It expands and tightens itself under the action of pressure difference to achieve a good seal. The above-mentioned C-shaped seal is divided into multiple arc segments, and each steam seal arc segment corresponds to a C-shaped seal arc segment.

There are 6 arc sections in the whole circle of steam seal, so there are 6 seams in total, and arc-shaped leaf springs are arranged in the middle of each seam. In order to facilitate installation and debugging, the arc-shaped plate spring is clamped on the end face adjacent to the arc section of the steam seal, and fixed with screws to prevent it from falling off. The edge of the above-mentioned arc-shaped leaf spring close to the rotor is basically flush with the lower teeth of the gland teeth. Since the arc section of the gland seal retreats, the spring also retreats accordingly, so it can ensure that the rotor does not collide with the arc-shaped leaf spring.

At the middle positions of the high-pressure side and the low-pressure side of each steam sealing arc section, a high-pressure ventilation groove and a low-pressure steam ventilation groove are arranged. During manufacturing, it is easy to realize by adopting milling technology, and the flow cross section of the finally formed steam vent groove is about 50×2=100mm ² .

The high-pressure side of the steam seal generates a closing force along the radial direction of the rotor and close to the rotor surface, and the low-pressure side generates an opening force along the radial direction of the rotor and away from the rotor surface. The relative size of the above closing force and opening force mainly depends on the ratio of the high pressure side steam seal tooth clearance to the low pressure side steam seal tooth clearance. When the sealing clearance is large, the ratio is close to 1, and the closing force is significantly greater than the opening force; when the sealing clearance is large Hours, the ratio increases significantly, for example, when 0.3/0.1=3, the opening force is significantly greater than the closing force. The resultant closing force is equal to the closing force minus the opening force. When the resultant closing force is greater than zero, the arc of the seal will automatically approach the rotor surface or produce this trend; when the resultant closing force is less than zero, the arc of the seal will automatically move away from the rotor surface or produce this tendency . Therefore, when the steam seal arc section is affected by factors such as small friction force and gravity (relatively small amount) in the radial direction of the rotor, its relative position to the rotor mainly depends on the relative magnitude of the closing force and the opening force. When the closing force and the opening force are roughly equal, the resultant force of all the forces on the radial direction of the rotor on the arc of the seal is zero, reaching a balanced state and keeping the position unchanged. The above equilibrium state can only be realized within a certain range of sealing clearance. In this embodiment, the gap between the teeth of the low-pressure side steam seal is approximately in the range of 0.15-0.25 mm, and the arc section of the steam seal can be in a balanced state.

When the rotor is eccentric relative to the seal ring due to whirl, the rotor surface will generate a radial force opposite to the eccentric direction of the rotor due to the pressure difference, which will increase the damping of the shaft system, thereby reducing vibration and improving the stability of the turbine shaft system. In this embodiment, when the whirl of the rotor is 0.05 mm, a damping force exceeding 100 kgf can be generated, and the vibration reduction effect is extremely remarkable.

Part of the design conditions and design results of this embodiment are shown in Table 1. The design results mainly include the closing resultant force (closing force-opening force) with the change of the ratio of the high-pressure side steam seal tooth clearance to the low-pressure side steam seal tooth clearance. The design results are plotted Became Figure 9. According to the design results, before the steam inlet of the steam turbine or when the steam inlet is very small, the steam seal is mainly in an open state due to the action of the arc-shaped leaf spring, and the sealing gap is large; If the pressure is increased, the pressure difference between the front and rear of the steam seal will increase. At this time, it is very easy to generate a large closing resultant force, which will gradually reduce the gap of the steam seal by overcoming the force of the spring; once the steam seal is in the closed state, even if the rotor is disturbed and the vibration increases or the cylinder When the deformation increases, the steam seal can still adapt to the above changes and automatically adjust the sealing gap, and it is always suspended on the surface of the rotor, ensuring a very small gap and never rubbing.

Applying the steam seal of this embodiment to the bridge bridge position of the high and medium pressure cylinders of the steam turbine can reduce the leakage by more than 50% compared with the design leakage of the traditional comb-toothed steam seal (the sealing gap is generally designed to be about 0.75mm); if compared with the traditional comb-toothed Compared with the actual application effect of the steam seal, the reduction of leakage can easily reach more than 70%, and the energy saving potential is huge.

Table 1 Part of the design conditions and design results of Example 1.

Example 2

As shown in Figure 10, it is basically the same as Embodiment 1, except that in order to further improve the reliability of the back seal of the steam seal, the auxiliary sealing strip also includes an O-shaped seal arranged on the inner side of the steam seal lug, and the O-shaped seal A small hole is opened on the inner side. Once high-pressure steam enters, it will expand and tighten itself under the action of pressure difference to achieve a good seal.

In this embodiment, the O-shaped seal is divided into two semicircles, which are respectively placed in the T-shaped grooves of the upper and lower cylinders, and are crimped with the inner surfaces of the lugs of the steam seal.

In this embodiment, the functions of the C-shaped seal and the O-shaped seal are basically the same, and the concept of redundant design is adopted to improve the reliability of the seal.

Example 3

It is basically the same as that of Example 1, except that the clearance between the high-pressure side seal teeth is larger than that of the low-pressure side seal teeth, and several seal teeth on the high-pressure side gradually shrink along the steam flow to the seal gap, and some seal teeth on the low-pressure side The steam flow direction seal gap remains unchanged; using specific numerical description, when the tolerance is not considered, the design gap of 16 equivalent teeth is 0.65-0.65-0.6-0.6-0.55-0.55-0.5-0.5-0.45-0.45-0.4- 0.3-0.3-0.3-0.3-0.3.

Compared with Example 1, this example optimizes the sensitivity of the resultant closing force (closing force-opening force) to changes in the sealing gap, and its significant advantage is that it reduces the influence of factors such as processing errors and adjustment deviations on the working characteristics of the steam seal .

Claims (7)

1. a kind of seal clearance selfregulated glandpacking device with gas suspension effect, it is characterised in that：Including multiple packing arcs Section, auxiliary seal bar and the spring being located between packing segmental arc；Packing segmental arc is provided with gland sealing gear, and described gland sealing gear includes height Press side gland sealing gear and low-pressure side gland sealing gear；Auxiliary seal bar upstream is defined as high-pressure side, and auxiliary seal bar downstream is defined as low pressure Side；The high-pressure side axial width is more than low-pressure side axial width, and the high-pressure side gland sealing gear number is more than low-pressure side gland sealing gear Number, and high-pressure side packing backlash is all higher than low-pressure side packing backlash, both differ 0.1~0.8mm, total yield tooth number No less than 10, the low tooth that a high tooth is designated as between an equivalent tooth, two high teeth is also denoted as an equivalent tooth, and no matter two How many is all designated as an equivalent tooth for low tooth between individual high tooth；Gland sealing gear cooperatively forms seal clearance with rotor surface, and Some gland sealing gears in high-pressure side flow to seal clearance along steam flow and are gradually reduced, and some gland sealing gears of low-pressure side flow to seal clearance along steam flow Keep constant；Packing segmental arc centre position sets high pressure steaming groove and low pressure steaming groove respectively, and packing segmental arc back cavity connects respectively Logical high-pressure side and low-pressure side, high steam and low-pressure steam are obstructed by auxiliary seal bar；The auxiliary seal bar at least includes The c-type sealing of packing neck medial surface is arranged on, c-type sealing opening is connected with high-pressure side.

2. a kind of seal clearance selfregulated glandpacking device with gas suspension effect as claimed in claim 1, its feature exists In：Described spring is spiral compression spring or arc leaf spring.

3. a kind of seal clearance selfregulated glandpacking device with gas suspension effect as claimed in claim 2, its feature exists In：Described arc leaf spring is flushed close to the edge of rotor with the low tooth of gland sealing gear, but not higher than low tooth.

4. a kind of seal clearance selfregulated glandpacking device with gas suspension effect as claimed in claim 1, its feature exists In：The c-type sealing is divided into multiple segmental arcs, each one c-type sealing segmental arc of packing segmental arc correspondence, and c-type sealing mounting groove Inner side sets riveting groove.

5. a kind of seal clearance selfregulated glandpacking device with gas suspension effect as claimed in claim 1, its feature exists In：The auxiliary seal bar also includes opening aperture on the inside of the O-shaped sealing for being arranged on packing hangers medial surface, O-shaped sealing.

6. a kind of seal clearance selfregulated glandpacking device with gas suspension effect as claimed in claim 5, its feature exists In：It is described it is O-shaped sealing be divided into two semicircles, be individually positioned in above and below cylinder T-slot in, the inner side face pressure with packing hangers Connect.

7. a kind of seal clearance selfregulated glandpacking device with gas suspension effect as claimed in claim 1, its feature exists In：The packing segmental arc is radially included hangers, neck, packing matrix and the gland sealing gear connected successively by outer ring to inner ring；Hang Ear coordinates with the wider part of stator T-slot, and neck coordinates with the narrower part of stator T-slot；Packing segmental arc back cavity refers to Hangers cooperatively forms packing segmental arc back cavity with stator T-slot.