Method and system for improving vacuum leakproofness of low-pressure cylinder of steam turbine and steam turbine

Abstract

The invention relates to the technical field of steam turbine optimization, and particularly discloses a method and system for improving the vacuum leakproofness of a low-pressure cylinder of a steam turbine and the steam turbine. The drainage manual door is connected with steam supply adjusting doors at shaft seals on the two sides of a low-pressure cylinder of the steam turbine. And the steam supply adjusting door is adjusted until the steam emission amount at the shaft seals on the two sides of the low-pressure cylinder reaches the national standard requirement of vacuum tightness of the low-pressure cylinder. By reasonably optimizing the running state of the low-pressure shaft seal of the steam turbine, the high sealing performance of the two sides of the low-pressure cylinder is kept, and under the condition that investment is not increased, the vacuum state of the steam turbine is improved, and related heat and working media are recycled to improve economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of steam turbine optimization, and in particular to a method, a system and a steam turbine for improving the vacuum tightness of a low-pressure cylinder of a steam turbine. Background Art

[0002] The tightness of the steam turbine vacuum system is closely related to the health of the vacuum system. Good vacuum tightness can maintain the back pressure of the unit at a low level. Low back pressure can effectively reduce the coal consumption of the unit and improve the efficiency of the unit. Since the low-pressure cylinder shaft seal of the steam turbine always works in a vacuum state, improper control will cause the vacuum tightness of the unit to decrease.

[0003] At present, the low-pressure cylinder shaft seal has the following problems: 1) The steam supply pipeline of the low-pressure cylinder shaft seal is long due to the pipeline layout, and the natural heat dissipation is large; 2) The opening of the low-pressure cylinder shaft seal steam supply adjustment valve is small, the throttling effect is obvious, and the flow resistance is large; 3) The steam supply pipeline is a U-shaped pipe structure, which is prone to water accumulation.

[0004] At present, the low-pressure cylinder shaft seal system adopts self-sealing steam supply. The steam supply temperature varies with the load, 145 degrees Celsius at high load and 130 degrees Celsius at low load. The steam supply pressure is about 30kPa. At low load, the steam supply superheat is basically zero after the throttling of the regulating valve. The long steam supply pipeline has obvious heat dissipation, and the throttling effect of the regulating valve will cause condensation after part of the steam is throttled. The water accumulation in the steam supply pipeline in a U-shaped pipe structure will form a water seal and produce wet steam, which will affect the steam supply to the shaft seal and make the shaft seal fail.

[0005] Therefore, how to improve the vacuum tightness of the low-pressure cylinder of the steam turbine by adjusting the operating state of the low-pressure cylinder shaft seal is a technical problem that urgently needs to be solved. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a method, system and steam turbine for improving the vacuum tightness of a low-pressure cylinder of a steam turbine.

[0007] In a first aspect, the present invention provides a method for improving the vacuum tightness of a low-pressure cylinder of a steam turbine, and the technical scheme of the method is as follows:

[0008] Open the manual drain door of the steam turbine; the manual drain door is connected to the steam supply adjustment door at the shaft seals on both sides of the low-pressure cylinder of the steam turbine;

[0009] The steam supply adjustment valve is adjusted until the steam emission at the shaft seals on both sides of the low-pressure cylinder reaches the national standard requirement for the vacuum tightness of the low-pressure cylinder.

[0010] The beneficial effects of the method for improving the vacuum tightness of the low-pressure cylinder of a steam turbine of the present invention are as follows:

[0011] The method of the present invention reasonably optimizes the operating state of the low-pressure shaft seal of the steam turbine, maintains high sealing performance on both sides of the low-pressure cylinder, improves the vacuum state of the steam turbine and recovers related heat and working fluid to improve economic benefits without increasing investment.

[0012] On the basis of the above scheme, the method for improving the vacuum tightness of the low-pressure cylinder of a steam turbine of the present invention can also be improved as follows.

[0013] In an optional manner, the number of the manual drain doors is two, and a manual drain door is respectively connected to the steam supply adjustment door at the shaft seal on each side of the low-pressure cylinder.

[0014] In an optional manner, the step of opening the manual drain door of the steam turbine includes:

[0015] The opening of the steam turbine manual drain door is adjusted to a target opening; the target opening is: 5%-10% of the maximum opening of the steam turbine manual drain door.

[0016] In an optional manner, the method further includes:

[0017] A safety valve bypass is arranged on the steam supply pipeline corresponding to the low-pressure cylinder; wherein the number of the safety valve bypass is at least one.

[0018] In an optional manner, the method further includes:

[0019] The manual drain door is also connected to a check valve, and the other end of the check valve is connected to the main pipe between the steam leakage from the door rod and the shaft seal heater to recover the working fluid and heat.

[0020] In a second aspect, the present invention provides a system for improving the vacuum tightness of a low-pressure cylinder of a steam turbine, and the technical solution of the system is as follows:

[0021] It includes: a first optimization module and a second optimization module;

[0022] The first optimization module is used to: open the manual drain door of the steam turbine; the manual drain door is connected to the steam supply adjustment door at the shaft seals on both sides of the low-pressure cylinder of the steam turbine;

[0023] The second optimization module is used to adjust the steam supply adjustment valve until the steam emission at the shaft seals on both sides of the low-pressure cylinder reaches the national standard requirement for the vacuum tightness of the low-pressure cylinder.

[0024] The beneficial effects of the system for improving the vacuum tightness of the low-pressure cylinder of a steam turbine according to the present invention are as follows:

[0025] The system of the present invention reasonably optimizes the operating state of the low-pressure shaft seal of the steam turbine, maintains high sealing performance on both sides of the low-pressure cylinder, improves the vacuum state of the steam turbine and recovers related heat and working fluid to improve economic benefits without increasing investment.

[0026] On the basis of the above scheme, the system for improving the vacuum tightness of the low-pressure cylinder of a steam turbine of the present invention can also be improved as follows.

[0027] In an optional manner, the number of the manual drain doors is two, and the steam supply adjustment door at the shaft seal on each side of the low-pressure cylinder is respectively connected to a filter screen and a manual drain door.

[0028] In an optional manner, the first optimization module is specifically used to:

[0029] The opening of the steam turbine manual drain door is adjusted to a target opening; the target opening is: 5%-10% of the maximum opening of the steam turbine manual drain door.

[0030] In an optional manner, the method further includes: a third optimization module; the third optimization module is used to:

[0031] A safety valve bypass is arranged on the steam supply pipeline corresponding to the low-pressure cylinder; wherein the number of the safety valve bypass is at least one.

[0032] In a third aspect, the present invention provides a steam turbine which is improved by using the method for improving the vacuum tightness of the low-pressure cylinder of the steam turbine as described in the present invention.

[0033] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are only used to illustrate the embodiments and are not to be considered as limiting the present invention. In addition, the same reference symbols are used to represent the same components throughout the accompanying drawings. In the accompanying drawings:

[0035] Figure 1 A schematic flow chart of an embodiment of a method for improving the vacuum tightness of a low-pressure cylinder of a steam turbine according to the present invention;

[0036] Figure 2 It is a structural schematic diagram of the steam turbine shaft seal system;

[0037] Figure 3 The present invention is a schematic structural diagram of an embodiment of a system for improving the vacuum tightness of a low-pressure cylinder of a steam turbine. DETAILED DESCRIPTION

[0038] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0039] Figure 1 FIG. 2 is a flow chart showing an embodiment of a method for improving the vacuum tightness of a low-pressure cylinder of a steam turbine provided by the present invention. Figure 1 As shown, the following steps are included:

[0040] S1. Open the manual drain door of the steam turbine; the manual drain door is connected to the steam supply adjustment door at the shaft seals on both sides of the low-pressure cylinder of the steam turbine.

[0041] Among them, the existing steam turbine drain manual door is in a normally closed state. Figure 2 The number of the shown manual drain doors is two by default (a first manual drain door 57 and a second manual drain door 58). The steam supply adjustment door at each side of the shaft seal of the low-pressure cylinder is respectively connected to a filter screen and a manual drain door, that is, the first steam supply adjustment door 62 is connected to the first manual drain door 57 through a filter screen, and the second steam supply adjustment door 63 is connected to the second manual drain door 58 through a filter screen.

[0042] The steam turbine manual drain door opening is adjusted to the target opening to timely drain the condensate formed by the low-pressure shaft seal steam supply to prevent water resistance and wet steam formation. The target opening is 5%-10% of the maximum opening of the manual drain door.

[0043] S2. The steam supply adjustment valve is adjusted until the steam emission from the shaft seals on both sides of the low-pressure cylinder reaches the national standard requirement for the vacuum tightness of the low-pressure cylinder.

[0044] Among them, by adjusting the steam supply size of the steam supply adjustment valves (the first steam supply adjustment valve 62 and the second steam supply adjustment valve 63) at the shaft seals on both sides of the low-pressure cylinder, the shaft seals do not absorb air and do not emit steam. Since the shaft seal is adjacent to the bearing seat, the bearing seat is at a slightly negative pressure, and the emission of steam will cause steam to enter the bearing seat, resulting in water in the lubricating oil. Since the load may change at any time, the opening of the steam supply adjustment valve at the shaft seal is increased during the adjustment process to reduce the throttling effect, and the steam supply at the shaft seal emits slightly. The appropriate size of the steam emission is determined by continuously testing the lubricating oil quality, with the critical point that there is no obvious increase in the water content of the lubricating oil at high load, so that the amount of steam emission at the shaft seals on both sides of the low-pressure cylinder meets the design requirements for the vacuum tightness of the low-pressure cylinder.

[0045] In an optional manner, the method further includes:

[0046] A safety valve bypass is arranged on the steam supply pipeline corresponding to the low-pressure cylinder.

[0047] The number of the safety valve bypass is at least one. In this embodiment, two safety valve bypasses (a first safety valve bypass 68 and a second safety valve bypass 69) are set by default. By adding a safety valve bypass, the preheating speed of the shaft seal system of the steam turbine can be accelerated.

[0048] In an optional manner, the method further includes:

[0049] The manual drain door is also connected to a check valve, and the other end of the check valve is connected to the main pipe between the steam leakage from the door rod and the shaft seal heater to recover the working fluid and heat.

[0050] Specifically, the first drain manual door 57 is connected to the first check valve 72, and the second drain manual door 58 is connected to the second check valve 73. The other end of the first check valve 72 and the other end of the second check valve 73 are connected to the main pipe between the gate rod leakage steam and the shaft seal heater to recover the working fluid and heat.

[0051] In this embodiment, a check valve is installed behind the manual drain door, and the check valve is directly connected to the door rod steam leakage main pipe, so that the exhaust steam heat is recovered through the shaft seal heater, and the drain is recovered to the exhaust device.

[0052] The technical solution of this embodiment reasonably optimizes the operating state of the low-pressure shaft seal of the turbine, maintains high sealing performance on both sides of the low-pressure cylinder, improves the vacuum state of the turbine and recovers related heat and working fluid to improve economic benefits without increasing investment.

[0053] Figure 3 FIG. 2 shows a schematic diagram of a system 200 for improving the vacuum tightness of a low-pressure cylinder of a steam turbine according to an embodiment of the present invention. Figure 3 As shown, the system 200 includes: a first optimization module 210 and a second optimization module 220;

[0054] The first optimization module 210 is used to: open the manual drain door of the steam turbine; the manual drain door is connected to the steam supply adjustment door at the shaft seals on both sides of the low-pressure cylinder of the steam turbine;

[0055] The second optimization module 220 is used to adjust the steam supply adjustment valve until the steam emission at the shaft seals on both sides of the low-pressure cylinder reaches the national standard requirement for the vacuum tightness of the low-pressure cylinder.

[0056] In an optional manner, the number of the manual drain doors is two, and the steam supply adjustment door at the shaft seal on each side of the low-pressure cylinder is respectively connected to a filter screen and a manual drain door.

[0057] In an optional manner, the first optimization module 210 is specifically configured to:

[0058] The opening of the steam turbine manual drain door is adjusted to a target opening; the target opening is: 5%-10% of the maximum opening of the steam turbine manual drain door.

[0059] In an optional manner, the method further includes: a third optimization module; the third optimization module is used to:

[0060] A safety valve bypass is arranged on the steam supply pipeline corresponding to the low-pressure cylinder; wherein the number of the safety valve bypass is at least one.

[0061] In an optional manner, the manual drain door is also connected to a check valve, and the other end of the check valve is connected to the main pipe between the steam leakage from the door rod to the shaft seal heater to recover the working fluid and heat.

[0062] The technical solution of this embodiment reasonably optimizes the operating state of the low-pressure shaft seal of the turbine, maintains high sealing performance on both sides of the low-pressure cylinder, improves the vacuum state of the turbine and recovers related heat and working fluid to improve economic benefits without increasing investment.

[0063] The steam turbine provided in an embodiment of the present invention is improved by a method for improving the vacuum tightness of the low-pressure cylinder of a steam turbine as in this embodiment. For details, please refer to the parameters and steps in the embodiment of a method for improving the vacuum tightness of the low-pressure cylinder of a steam turbine mentioned above, which will not be elaborated here.

[0064] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. Similarly, in order to simplify the present invention and help understand one or more of the various inventive aspects, in the above description of exemplary embodiments of the present invention, the various features of the embodiments of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. Wherein, the claims that follow the specific embodiment are hereby expressly incorporated into the specific embodiment, wherein each claim itself is a separate embodiment of the present invention.

[0065] It should be noted that the above embodiments illustrate the present invention rather than limit it, and that those skilled in the art may devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbol between brackets shall not be construed as a limitation on the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "one" or "an" preceding an element does not exclude the presence of a plurality of such elements. The present invention may be implemented by means of hardware comprising a number of different elements and by means of a suitably programmed computer. In a unit claim enumerating a number of devices, several of these devices may be embodied by the same hardware item. The use of the words first, second, and third, etc. does not indicate any order. These words may be interpreted as names. The steps in the above embodiments, unless otherwise specified, should not be understood as limitations on the order of execution.

Claims

1. A method for improving the vacuum tightness of a low-pressure cylinder of a steam turbine, characterized in that: include: Open the manual drain door of the steam turbine; the manual drain door is connected to the steam supply adjustment door at the shaft seals on both sides of the low-pressure cylinder of the steam turbine; The steam supply adjustment valve is adjusted until the steam emission at the shaft seals on both sides of the low-pressure cylinder reaches the national standard requirement for the vacuum tightness of the low-pressure cylinder.

2. The method for improving the vacuum tightness of a low-pressure cylinder of a steam turbine according to claim 1, characterized in that: The number of the manual drain doors is two, and the steam supply adjustment door at the shaft seal on each side of the low-pressure cylinder is respectively connected to a filter screen and a manual drain door.

3. The method for improving the vacuum tightness of a low-pressure cylinder of a steam turbine according to claim 1, characterized in that: The steps for opening the manual drain door of the steam turbine include: The opening of the steam turbine manual drain door is adjusted to a target opening; the target opening is: 5%-10% of the maximum opening of the steam turbine manual drain door.

4. The method for improving the vacuum tightness of a low-pressure cylinder of a steam turbine according to any one of claims 1 to 3, characterized in that: Also includes: A safety valve bypass is arranged on the steam supply pipeline corresponding to the low-pressure cylinder; wherein the number of the safety valve bypass is at least one.

5. The method for improving the vacuum tightness of a low-pressure cylinder of a steam turbine according to any one of claims 1 to 3, characterized in that: Also includes: The manual drain door is also connected to a check valve, and the other end of the check valve is connected to the main pipe between the steam leakage from the door rod and the shaft seal heater to recover the working fluid and heat.

6. A system for improving the vacuum tightness of a low-pressure cylinder of a steam turbine, characterized in that: include: A first optimization module and a second optimization module; The first optimization module is used to: open the manual drain door of the steam turbine; the manual drain door is connected to the steam supply adjustment door at the shaft seals on both sides of the low-pressure cylinder of the steam turbine; The second optimization module is used to adjust the steam supply adjustment valve until the steam emission at the shaft seals on both sides of the low-pressure cylinder reaches the national standard requirement for the vacuum tightness of the low-pressure cylinder.

7. The system for improving the vacuum tightness of the low-pressure cylinder of a steam turbine according to claim 6, characterized in that: The number of the manual drain doors is two, and the steam supply adjustment door at the shaft seal on each side of the low-pressure cylinder is respectively connected to a filter screen and a manual drain door.

8. The system for improving the vacuum tightness of the low-pressure cylinder of a steam turbine according to claim 7, characterized in that: The first optimization module is specifically used for: The opening of the steam turbine manual drain door is adjusted to a target opening; the target opening is: 5%-10% of the maximum opening of the steam turbine manual drain door.

9. The system for improving the vacuum tightness of the low-pressure cylinder of a steam turbine according to any one of claims 6 to 8, characterized in that: Also includes: The third optimization module; the third optimization module is used for: A safety valve bypass is arranged on the steam supply pipeline corresponding to the low-pressure cylinder; wherein the number of the safety valve bypass is at least one.

10. A steam turbine, characterized in that: The method for improving the vacuum tightness of the low-pressure cylinder of a steam turbine is improved by using the method as described in any one of claims 1 to 5.

Images