Up-down tangential throttling steam distribution structure and transformation method thereof

Abstract

The invention belongs to the field of thermal power generation, particularly discloses an up-and-down tangential throttling steam distribution structure and a transformation method thereof, and aims to solve the problem that the investment cost is high when a four-corner nozzle steam distribution unit is transformed into throttling steam distribution of which a valve is directly connected with a steam cylinder in order to overcome the defect that the regulation stage efficiency of nozzle steam distribution restricts the efficiency improvement of a high-pressure cylinder. The steam distribution structure comprises a high-pressure main steam valve, a high-pressure adjusting valve, a high-pressure main steam pipe, a high-pressure outer cylinder, a high-pressure inner cylinder and a high-pressure steam inlet insertion pipe. A high-pressure main steam adjusting valve set is designed to be of a one-main one-adjusting structure, under the condition that the position of an original valve and a valve support are not transformed, a valve steam inlet connector is matched with an original main steam pipeline, arrangement of the high-pressure main steam pipeline and a cylinder structure are locally optimized, and steam inlet pressure loss is reduced by adopting an up-down tangential throttling steam distribution scheme; the efficiency of the unit high-pressure cylinder is improved, the unit transformation economy is improved to the maximum extent, and the transformation investment cost of a power plant can be reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of thermal power generation, and particularly relates to an up-down tangential throttling steam distribution structure and a reforming method thereof. BACKGROUND

[0002] Domestic chemical, petroleum and other enterprises have high-temperature and high-pressure units that have been put into operation for many years, most of which adopt four-corner steam injection nozzles for steam distribution, two high-pressure main steam regulating groups are arranged on both sides of the operation platform, and are supported by rigid supports, each high-pressure main steam regulating valve group is composed of a high-pressure main steam valve and two regulating valves, the main steam valve shell and the regulating valve shell are welded into one body, and the two high-pressure main steam regulating valve groups are independent of each other. Four regulating valves are connected with four steam inlets symmetrically distributed on the upper and lower surfaces of the high-pressure outer cylinder through four high-pressure main steam pipes, and the main steam enters the independent nozzle chamber through the corresponding high-pressure main steam pipe. The nozzle steam distribution is generally divided into four groups, each nozzle group corresponds to one regulating valve, the steam flow is adjusted by controlling the area of the nozzle group, which has good regulating performance and high part-load cycle efficiency, but the low regulating stage efficiency restricts the improvement of the high-pressure cylinder efficiency. For self-provided power plants with more than 75% load all the year round and long operation hours, the economy of the nozzle steam distribution is worse than that of the throttling steam distribution, and the throttling steam distribution scheme is suitable.

[0003] At present, the tangential throttling steam distribution technology scheme of valve and cylinder direct connection is generally adopted in newly-built units, but for the unit with four-corner nozzle steam distribution, the throttling steam distribution of valve and cylinder direct connection often needs to reform the foundation of the operation platform to meet the arrangement requirements of the valve, which increases the investment cost of the power plant reform, the reform economic recovery period is long, and it does not have universal applicability. SUMMARY

[0004] In order to solve the above technical problems, the present application provides an up-down tangential throttling steam distribution structure and a reforming method thereof. The nozzle steam distribution is reformed into up-down tangential throttling steam distribution, specifically, the one-main-two-regulating structure of the high-pressure main steam regulating valve group is reformed into one-main-one-regulating structure, the valve is arranged at the original valve position, the valve support is not reformed, the valve steam inlet interface is matched with the original main steam pipeline, the high-pressure main steam pipeline arrangement and the cylinder structure are locally optimized, the up-down tangential throttling steam distribution scheme is adopted to reduce the steam inlet pressure loss, and the high-pressure cylinder efficiency of the unit is improved.

[0005] In order to achieve the purpose of the present application, the technical scheme adopted is: An up-down tangential throttling steam distribution structure, comprising two high-pressure main steam regulating valve groups, a high-pressure main steam pipe 3, a high-pressure outer cylinder 4, a high-pressure inner cylinder 5 and a high-pressure steam inlet plug pipe 6; wherein the high-pressure main steam regulating valve group comprises a high-pressure main steam valve 1 and a high-pressure regulating valve 2; wherein the high-pressure main steam valve 1 is connected with the main steam inlet pipeline in front of the valve, and the steam outlet behind the high-pressure regulating valve 2 is connected with the high-pressure steam inlet plug pipe 6 installed on the cylinder through the high-pressure main steam pipe 3.

[0006] Further, the high-pressure main steam valve 1 and the high-pressure regulating valve 2 in the high-pressure main steam regulating valve group are welded together.

[0007] Further, the high-pressure inlet pipe 6 is combined with the high-pressure outer cylinder 4.

[0008] Further, the high-pressure inlet pipe 6 is connected with the inlet of the high-pressure inner cylinder 5.

[0009] Further, the two high-pressure regulating valves are of the same size.

[0010] Further, the two high-pressure main steam regulating valve groups are arranged on the steam turbine operation platforms on the two sides of the steam turbine.

[0011] The application provides a reforming method of an up-down tangential throttling steam distribution structure, which is used for reforming of original nozzle steam distribution, and specific reforming method steps are as follows: (1) The two high-pressure main steam regulating valve groups (MSV-1 and CV-1, MSV-2 and CV-2) are arranged at the original installation positions of the operation platforms on the two sides of the steam turbine, and under the premise that the valve inlet center line, the valve support and the foundation are not changed, the high-pressure regulating valve in each high-pressure main steam regulating valve group is combined with the high-pressure main steam valve to form a one-main-one-regulating structure form by reducing two to one; the steam outlet center line of the high-pressure regulating valve CV-1 and CV-2 after reforming is consistent with the outlet center line of the original valve group high-pressure regulating valve CV-3 and CV-4; (2) From the steam turbine to the generator, the left high-pressure regulating valve outlet is connected with the high-pressure inlet pipe on the left side of the lower part of the high-pressure cylinder through the left high-pressure main steam pipe from the original middle layer position to enter the high-pressure inlet chamber, the right regulating valve outlet is connected with the high-pressure inlet pipe on the right side of the upper part of the high-pressure cylinder through the right high-pressure main steam pipe from the original middle layer position to avoid the high-pressure cylinder, the foundation and the high-pressure inlet chamber, and the original main steam pipe and the inlet position of the high-pressure main steam valve are aligned and welded together; (3) The high-pressure inlet pipe is combined with the high-pressure outer cylinder, the high-pressure inlet pipe is connected with the inlet of the high-pressure inner cylinder, the high-pressure inner cylinder and the inlet chamber are optimized as a whole, the high-pressure inlet chamber of the high-pressure inner cylinder is optimized from four inlet chambers to two tangential inlet chambers, and the independent nozzle chamber and the regulating stage are cancelled; (4) The high-pressure main steam pipe is changed from four to two to match the up-down tangential inlet mode, the pipe diameter is increased, and the pipe flow rate is ensured to be within the design specification to prevent the pipe from vibrating due to overspeed.

[0012] The above technical scheme has the following beneficial effects: 1. The up-down tangential throttling steam distribution structure and its reforming method can complete the reforming of the nozzle steam distribution into up-down tangential throttling steam distribution operation under the condition of limited reforming boundary, without reforming the valve support and foundation, only need to optimize the high-pressure main steam regulating valve, high-pressure inner and outer cylinder structure and high-pressure main steam pipeline arrangement, the weight of each component after the reforming is equivalent to the weight of the original unit, has no influence on the load distribution and structural strength of the original unit foundation, can reduce the investment cost of power plant reforming, basically has no safety operation risk, and maximum reforming benefit is obtained.

[0013] 2. The reforming of the up-down tangential throttling steam distribution reduces the high-pressure inlet steam pressure loss, is helpful to the improvement of the high-pressure efficiency, and further improves the economy of the unit and reduces the operation heat consumption rate of the unit. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 it is the arrangement drawing of the up-down tangential throttling steam distribution structure of the present application; Figure 2 it is the structure change comparison drawing of the high-pressure main steam regulating valve group before and after the reforming of the present application; Figure 3 it is the arrangement schematic drawing of the high-pressure main steam regulating valve, pipeline and cylinder of the present application; Figure 4 it is the high-pressure inner and outer cylinder, inlet steam plug-in pipe assembly and inlet steam chamber schematic drawing of the present application; Figure 5 it is the high-pressure main steam pipe structure change comparison drawing before and after the reforming of the present application.

[0015] In the drawing: 1-high-pressure main steam valve, 2-high-pressure regulating valve, 3-high-pressure main steam pipe, 4-high-pressure outer cylinder, 5-high-pressure inner cylinder, 6-high-pressure inlet steam plug-in pipe. DETAILED DESCRIPTION

[0016] In order to make the above-mentioned purpose, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are further described in detail below with reference to the drawings.

[0017] Example 1 An up-down tangential throttling steam distribution structure, comprising two high-pressure main steam regulating valve groups, a high-pressure main steam pipe 3, a high-pressure outer cylinder 4, a high-pressure inner cylinder 5 and a high-pressure inlet steam plug-in pipe 6; wherein the high-pressure main steam regulating valve group comprises a high-pressure main steam valve 1 and a high-pressure regulating valve 2; wherein the high-pressure main steam valve 1 is connected with the main steam inlet pipeline before the valve, and the steam outlet after the high-pressure regulating valve 2 is connected with the high-pressure inlet steam plug-in pipe 6 installed on the cylinder through the high-pressure main steam pipe 3; the high-pressure main steam valve 1 and the high-pressure regulating valve 2 in the high-pressure main steam regulating valve group are welded together; the high-pressure inlet steam plug-in pipe 6 is combined with the high-pressure outer cylinder 4, and the high-pressure inlet steam plug-in pipe 6 is connected with the inlet port of the high-pressure inner cylinder 5; the two high-pressure main steam regulating valve groups are arranged on the steam turbine operation platform on both sides of the steam turbine respectively.

[0018] Example 2 A certain power plant No. 2 unit is a high-temperature and high-pressure, double-cylinder and double-steam, impulsive, single-shaft direct air-cooled condensing steam turbine unit produced by a certain manufacturing company. The unit type is C125-8.83 / 1.0 steam turbine unit. The unit was put into operation in 2009. After more than ten years of operation, the unit has problems such as high heat consumption, low efficiency, and poor reliability, which affect the economic and safety of the unit operation.

[0019] The unit operation data of a certain power plant were collected. The annual full-load operating hours of No. 2 unit exceeded 8000 hours, and the load was above 105 MW. In view of the long-term high load and high operating hours of the unit, the upper and lower tangential throttling distribution was completed under the premise of limited modification boundary during the unit through-flow modification from 2022 to 2024.

[0020] The modification method is an upper and lower tangential throttling distribution structure, which includes two high-pressure main steam valves, two high-pressure regulating valves, two high-pressure main steam pipes, a high-pressure outer cylinder, a high-pressure inner cylinder, and two high-pressure inlet pipes, as shown in Figure 1 , 3 Compared with the modification before, the valve rigid support remains unchanged, the single-sided high-pressure regulating valve is changed from two to one, and the left and right high-pressure regulating valves are of the same size, as shown in Figure 2 From the perspective of the steam turbine to the generator, the left regulating valve outlet is connected to the high-pressure inlet pipe on the left side of the lower part of the high-pressure outer cylinder through the left high-pressure main steam pipe to enter the high-pressure through-flow, and the right regulating valve outlet is connected to the high-pressure inlet pipe on the right side of the upper part of the high-pressure outer cylinder through the right high-pressure main steam pipe to enter the high-pressure through-flow, as shown in Figure 3 The high-pressure inner and outer cylinder structure is optimized. The high-pressure inner cylinder cancels the independent nozzle chamber and regulating stage. The high-pressure inner cylinder and the inlet chamber are optimized as a whole, which is changed from upper and lower symmetrical four-inlet to upper and lower asymmetrical tangential two-inlet. The high-pressure outer cylinder is connected with the high-pressure inner cylinder through the high-pressure inlet pipe, as shown in Figure 4 After modification, the high-pressure main steam pipe is changed from four to two, and the pipe is changed from φ273x25mm to φ325x25mm, which matches the upper and lower tangential inlet mode, as shown in Figure 5 After modification, the throttling distribution operation mode is adopted. The high-pressure regulating valve is opened or closed to increase or decrease the load, improve the unit load response speed, and meet the requirements of primary frequency modulation and AGC examination of the power grid.

[0021] After the unit modification, the unit operates in good condition, and the modification effect is better than the design value. The high-pressure cylinder efficiency is improved from 83.54% before modification to 92.98% (design value 91.8%), which greatly improves the unit efficiency, reduces the unit operating heat consumption, and has significant energy-saving and emission-reducing effects.

[0022] It should be noted that the above examples are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced, without departing from the spirit and scope of the technical solutions of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. A vertically tangentially throttling steam distribution structure, characterized in that: It includes two high-pressure main steam regulating valve groups, a high-pressure main steam pipe (3), a high-pressure outer cylinder (4), a high-pressure inner cylinder (5), and a high-pressure steam inlet pipe (6); the high-pressure main steam regulating valve group includes a high-pressure main steam valve (1) and a high-pressure regulating valve (2); the high-pressure main steam valve (1) is connected to the main steam inlet pipe before the valve, and the steam outlet after the high-pressure regulating valve (2) is connected to the high-pressure steam inlet pipe (6) installed on the cylinder through the high-pressure main steam pipe (3).

2. The upper and lower tangential throttling steam distribution structure according to claim 1, characterized in that: The high-pressure main steam valve (1) and the high-pressure regulating valve (2) in the high-pressure main steam regulating valve group are welded together.

3. The upper and lower tangential throttling steam distribution structure according to claim 1, characterized in that: The high-pressure steam inlet pipe (6) is joined together with the high-pressure outer cylinder (4).

4. The upper and lower tangential throttling steam distribution structure according to claim 1, characterized in that: The high-pressure steam inlet pipe (6) is connected to the steam inlet of the high-pressure inner cylinder (5).

5. The upper and lower tangential throttling steam distribution structure according to claim 1, characterized in that: The high-pressure regulating valves in the two high-pressure main steam regulating valve groups are of the same size.

6. The upper and lower tangential throttling steam distribution structure according to claim 1, characterized in that: The two high-pressure main steam regulating valve groups are respectively arranged on the steam turbine operating platform on both sides of the steam turbine.

7. A method for modifying the upper and lower tangential throttling steam distribution structure as described in any one of claims 1-6, characterized in that: The modification method involves transforming the nozzle steam distribution into an upper and lower tangential throttling steam distribution structure, including the following steps: (1) The two high-pressure main steam regulating valve groups are arranged at the original installation positions of the operating platforms on both sides of the steam turbine. Under the premise that the valve inlet center line, valve support and foundation remain unchanged, the high-pressure regulating valve in each high-pressure main steam regulating valve group is reduced from two to one and combined with the high-pressure main steam valve to form a one-main-one-regulating structure. (2) Looking from the turbine to the generator, the outlet of the left high pressure regulating valve passes through the left high pressure main steam pipe from the original middle layer position and connects with the high pressure steam inlet pipe on the lower left side of the high pressure cylinder to enter the high pressure steam inlet chamber. The outlet of the right regulating valve passes through the right high pressure main steam pipe from the original middle layer position and avoids the high pressure cylinder and the pit, and connects with the high pressure steam inlet pipe on the upper right side of the high pressure cylinder to enter the high pressure steam inlet chamber. The original main steam pipe and the inlet position of the high pressure main steam valve are aligned and welded together. (3) The high-pressure steam inlet pipe is combined with the high-pressure outer cylinder, and the high-pressure steam inlet pipe is connected to the high-pressure inner cylinder steam inlet. The high-pressure inner cylinder and the steam inlet chamber are optimized into a whole. The high-pressure inner cylinder steam inlet chamber is optimized from four steam inlets at the top and bottom to two tangential steam inlets at the top and bottom. The independent nozzle chamber and regulating stage are eliminated. (4) The high-pressure main steam pipe was changed from four pipes to two pipes to match the upper and lower tangential steam inlet method, and the pipe diameter was increased to ensure that the pipe flow velocity was within the design specifications to prevent the pipe from vibrating due to overspeed.

8. The method for modifying the upper and lower tangential throttling steam distribution structure according to claim 7, characterized in that: The steam outlet centerline of the modified high-pressure regulating valves CV-1 and CV-2 described in step (1) is consistent with the outlet centerline of the original high-pressure regulating valves CV-3 and CV-4.

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