A large flow steam supplement device for steam turbine

Abstract

The present invention provides a large flow rate supplementary steam device for a steam turbine, comprising: a main steam flow moving along a feed direction in a main flow channel; an annular supplementary steam flow chamber is arranged on the outside of the main flow channel, and the inside of the annular supplementary steam flow chamber is connected to the main flow channel through a throat; a supplementary steam flow pipeline is arranged on one side of the annular supplementary steam flow chamber; the supplementary steam flow enters the annular supplementary steam flow chamber from the supplementary steam flow pipeline, and then enters the main flow channel from the annular supplementary steam flow chamber; the throat and the main flow channel gradually become parallel, so that the supplementary steam flow and the main steam flow gradually become parallel and flow in the feed direction; the ratio of the cross section occupied by the supplementary steam flow to the cross section occupied by the main steam flow is equal to the ratio of the supplementary steam flow rate to the main steam flow rate. The present invention controls the flow direction of the supplementary steam flow through the first and fifth profiles, and controls the flow direction of the main steam flow through the fourth and third profiles, so that the main steam flow and the supplementary steam flow are smoothly mixed.

Description

Technical Field

[0001] The invention relates to the field of thermal power steam turbines, and in particular to a large-flow steam supplement device for steam turbines. Background Art

[0002] With the development of my country's industrial level and scale, the demand for industrial energy is increasing. However, my country's energy reserves are relatively tight, and the implementation of energy conservation and consumption reduction and efficient energy utilization measures is in line with my country's basic national policy of sustainable development at this stage. As one of the main energy conversion equipment in my country, the optimization of steam turbine performance is also one of the important tasks of steam turbine design.

[0003] With the maturity of steam turbine technology, the parameters of steam are divided more finely, and steam of different qualities needs to be introduced into different pressure sections to improve the efficiency of the steam turbine. However, industrial steam turbines are usually small in size and compact in structure, and their high, medium and low pressure rigid bodies are usually cast as a whole. Therefore, a layout scheme for supplementary steam flow steam turbines is proposed, that is, different quality steam is graded and supplemented into different pressure sections. The advantages of this design are its simple structure and compact size, which is suitable for the overall layout of industrial small machines. When this type of unit is operating normally, the supplementary steam valve is fully open, the throttling loss of the valve is reduced, and the economy of the unit is improved. Therefore, compared with the traditional nozzle steam supply or throttling steam supply steam turbine, the steam turbine with supplementary steam valve has obvious competitive advantages; however, the steam quality of the steam turbine with supplementary steam valve after the mainstream and the supplementary steam flow are mixed is difficult to control, which causes a large throttling energy loss to the steam, not only the supplementary steam efficiency is low, but also the pressure of the supplementary steam point is uncontrollable. Especially when the supplementary steam volume is large, even exceeding the mainstream steam volume, the supplementary steam flow will seriously disturb the mainstream steam and even form a large number of flow dead zones, which is counterproductive to the purpose of supplementary steam.

[0004] Specifically, as shown in patent CN109653807A, Figure 1 As shown in the figure, when the supplementary steam flow a entering from the supplementary steam inlet is large, the supplementary steam flow a impacts the main steam flow b, generating high-intensity vortex flow c, which seriously deteriorates the flow field quality. When the supplementary steam volume is large or even exceeds the main flow rate, the supplementary steam flow is likely to cut off the main steam flow, impact the main flow wall, and even form a flow dead zone. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a large-flow supplementary steam device for a steam turbine, which is used to solve the problems in the prior art of excessive supplementary steam flow, such as reduced flow field quality of the main steam flow and the supplementary steam flow after mixing, throttling energy loss, and flow dead zone.

[0006] To achieve the above-mentioned and other related purposes, the present invention provides a large flow steam supplement device for a steam turbine, comprising:

[0007] a main flow channel, wherein a main steam flow moving along a feed direction is present in the main flow channel;

[0008] an annular supplementary steam flow chamber, the annular supplementary steam flow chamber is annularly arranged outside the main flow passage, the inner side of the annular supplementary steam flow chamber is connected to the main flow passage through a throat; a supplementary steam flow pipeline is arranged on one side of the annular supplementary steam flow chamber; supplementary steam flows enter the annular supplementary steam flow chamber from the supplementary steam flow pipeline, and then enter the main flow passage from the annular supplementary steam flow chamber;

[0009] The throat and the mainstream passage are gradually parallel to each other, so that the supplementary steam flow and the main steam flow gradually become parallel to each other and flow in a feeding direction; the ratio of the cross-section occupied by the supplementary steam flow to the cross-section occupied by the main steam flow is equal to the ratio of the supplementary steam flow rate to the main steam flow flow rate.

[0010] Preferably, the throat includes a first profile located on one side of the feeding direction and a second profile and a fifth profile located on the other side of the feeding direction; the mainstream channel includes a fourth profile located on the inner side and a third profile located on the outer side; the second profile is connected to the fifth profile.

[0011] Preferably, the distance between the first profile line and the second profile line gradually decreases from the outside to the inside, and the slope of the second profile line gradually decreases from the outside to the inside; the axial length (L 31 ) to throat width (L): 0.6~1.6.

[0012] Preferably, a transition arc is provided between the second profile line and the fifth profile line; the ratio of the radius of the transition arc (B) to the throat width (L) is 0.15 to 0.55.

[0013] Preferably, the axial length (L 33 ) to throat width (L): 0.6~1.6.

[0014] Preferably, the supplementary steam flow velocity of the supplementary steam flow pipeline is less than 50 m / s, and the flow velocity in the annular supplementary steam flow chamber is less than 20 m / s.

[0015] Preferably, the distance between the first profile line and the fifth profile line gradually decreases, so as to increase the flow rate of the supplementary steam flow to be consistent with the flow rate of the main steam flow.

[0016] As described above, the large flow steam supplement device for a steam turbine of the present invention has the following beneficial effects:

[0017] The present invention arranges the first profile and the fifth profile so that the flow direction of the supplementary steam flow is controlled; similarly, the present invention arranges the fourth profile and the third profile of the mainstream channel so that the flow direction and flow velocity of the main steam flow are controlled, so that the main steam flow and the supplementary steam flow flow in parallel in the mainstream channel, thereby achieving smooth mixing; in addition, the present invention controls the ratio of the cross section where the supplementary steam flow is located to the cross section where the main steam flow is located, thereby achieving control of the flow velocities of the two, thereby avoiding mixing flow losses caused at the dividing line; thereby, the steam flow distribution after mixing is more uniform, the total pressure loss can be effectively reduced, and the aerodynamic performance and flow field quality of the steam after the supplementary steam flow are effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Shown is a schematic diagram of an air replenishing device in the prior art.

[0019] Figure 2 A perspective view of a large flow steam supplement device for a steam turbine according to the present invention is shown;

[0020] Figure 3 A cross-sectional view showing a large flow rate steam supplement device for a steam turbine according to the present invention;

[0021] Figure 4 Display as Figure 3 Schematic diagram of adjustment of the first and third profiles at the throat;

[0022] Figure 5 Display as Figure 3 Schematic diagram of the mixing of supplementary steam flow and main steam flow at the throat;

[0023] Figure 6 Display as Figure 3 Schematic diagram of the first profile line at the throat being lowered to produce airflow and flow separation;

[0024] Figure 7 Display as Figure 3 Schematic diagram of the third profile line at the throat causing airflow and flow separation;

[0025] Figure 8 Display as Figure 3 Schematic diagram of the second and fifth type lines at the throat of the device generating airflow and flow separation under the condition of large air supply;

[0026] Fig. 9 Display as Figure 3 Schematic diagram of airflow generated by setting transition arcs on the second profile line and the fifth profile line at the throat.

[0027] Component number description

[0028] 1 Mainstream channel

[0029] 11 Inner tube

[0030] 12 Outer tube

[0031] 2 Annular Admission Steam Chamber

[0032] 21 Supplementary steam flow pipeline

[0033] 22 Throat

[0034] 31 First Type Line

[0035] 32 Second type line

[0036] 33 Third Type Line

[0037] 34 Fourth Line

[0038] 35 Fifth Line

[0039] A Flow separation

[0040] B Transition arc DETAILED DESCRIPTION

[0041] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0042] See also Figures 1 to 9 . It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0043] The outer side, namely the main flow channel 1 , faces the outer tube 12 , and the inner side, namely the main flow channel 1 , faces the inner tube 11 .

[0044] like Figure 2 As shown, the present invention provides a large flow steam supplement device for a steam turbine, comprising:

[0045] The mainstream channel 1 has a main steam flow moving along the feed direction. For ease of understanding, the mainstream channel 1 is actually composed of an inner tube 11 and an outer tube 12. The inner tube 11 is located inside the outer tube 12. The main steam flows in the interlayer between the inner tube 11 and the outer tube 12.

[0046] An annular supplementary steam flow chamber 2 is annularly arranged outside the main flow passage 1, and the inner side of the annular supplementary steam flow chamber 2 is connected to the main flow passage 1 through a throat 22; a supplementary steam flow pipeline 21 is arranged on one side of the annular supplementary steam flow chamber 2; the supplementary steam flow enters the annular supplementary steam flow chamber 2 through the supplementary steam flow pipeline 21, and then enters the main flow passage 1 through the annular supplementary steam flow chamber 2;

[0047] like Figure 4 As shown, the throat 22 and the main flow channel 1 gradually become parallel, so that the supplementary steam flow and the main steam flow gradually become parallel and flow in the feed direction; the ratio of the cross section occupied by the supplementary steam flow to the cross section occupied by the main steam flow is equal to the ratio of the supplementary steam flow rate to the main steam flow rate.

[0048] The throat 22 includes a first profile 31 on one side of the feeding direction and a second profile 32 and a fifth profile 35 on the other side of the feeding direction; the main flow channel 1 includes a fourth profile 34 on the inside and a third profile 33 on the outside; the second profile 32 is connected to the fifth profile 35 below.

[0049] The present invention arranges the first profile 31 and the second profile 32 of the annular supplementary steam flow chamber 2 so that the annular supplementary steam flow chamber 2 can accommodate a large flow of supplementary steam flow. Meanwhile, the arrangement of the first profile 31 and the fifth profile 35 controls the flow direction of the supplementary steam flow. Similarly, the present invention arranges the fourth profile 34 and the third profile 33 of the main flow channel 1 so that the flow direction of the main steam flow can be controlled, so that the flow directions of the main steam flow and the supplementary steam flow are parallel to each other after mixing in the main flow channel, thereby reducing the mixing flow loss caused at the boundary line of the two air flows (main steam flow and supplementary steam flow) and avoiding the flow dead zone caused by the supplementary steam flow cutting off the main steam flow.

[0050] Since the speed of the supplementary steam flow is lower than that of the main steam flow, in order to increase the speed of the supplementary steam flow, the throat 22 from the annular supplementary chamber 2 to the main flow channel 1 is reduced, thereby increasing the flow speed of the supplementary steam flow; specifically, the distance between the first profile 31 and the fifth profile 35 is gradually reduced, so that the flow speed of the supplementary steam flow is equal to the flow speed of the main steam flow as much as possible.

[0051] like Figure 5 In order to make the flow rates of the supplementary steam flow and the main steam flow as close as possible, it is necessary to design the cross-sections occupied by the supplementary steam flow and the main steam flow; specifically, according to the following formulas (1) to (3):

[0052] V 1 is the main steam flow rate, V 2is the flow rate of supplementary steam; m 1 Main steam flow, m 2 is the supplementary steam flow rate; ρ 1 Main steam flow density, ρ 2 Supplementary steam flow density; A 1 is the cross-sectional area occupied by the main steam flow, A 2 is the cross-sectional area occupied by the supplementary steam flow;

[0053]

[0054]

[0055] V 1 =V 2 (3)

[0056] Thus, the relationship between the cross-section occupied by the supplementary steam flow and the main steam flow and the flow rate of the supplementary steam flow and the main steam flow can be obtained (4):

[0057]

[0058] Specifically, due to the main steam flow velocity V 1 It can be determined that the required cross section A for the main steam flow can be obtained 1 ; and because of the quality and density of the supplementary steam flow m 2 and ρ 2 It can be determined that according to formula (4), the required cross-section A of the supplementary steam flow can be obtained: 2 ; Thus, the first line type 31, the second line type 32, the third line type 33, the fourth line type 34 and the fifth line type 35 are designed accordingly to meet A 2 and A 1 , and the boundary line between the main steam flow and the supplementary steam flow is obtained ( Figure 5 ).

[0059] In order to adapt to the situation of large supplementary steam flow, it is necessary to expand the volume of the annular supplementary steam flow chamber 2, so as to reduce the flow velocity and turbulent vortex intensity of a certain supplementary steam flow pipe 21; therefore, the distance between the first profile 31 and the second profile 32 is expanded as much as possible; but since the throat 22 needs to be reduced, the distance between the first profile 31 and the second profile 32 is now set to gradually decrease from the outside to the inside, so as to achieve the purpose of expanding the volume of the annular supplementary steam flow chamber 2 as much as possible. Specifically, the axial length L of the first profile 31 is 31 The ratio to the throat width L is: 0.6~1.6.

[0060] In order to prevent the second profile line 32 from being too linear and causing the inflow flow to be too fast, thereby preventing the inflow flow from interfering at the throat 22 , the slope of the second profile line 32 is gradually reduced from the outside to the inside.

[0061] In order to avoid the flow separation A phenomenon (such as the flow separation A) occurring near the second profile line 32 and the fifth profile line 35 when the supplementary steam flow is large due to the contraction of the supplementary steam flow channel, Figure 8 As shown), the transition arc B between the second profile line 32 and the fifth profile line 35 can be increased to smooth the flow curve and reduce the flow separation A (as shown in FIG. Fig. 9 As shown). However, when the radius of the transition arc B is too large, flow separation A may also occur near the fifth profile line 35; therefore, the radius of the transition arc B can be reasonably selected by combining the flow field structure simulated by CFD. Specifically, the ratio of the radius of the transition arc B to the throat width L is: 0.15 to 0.55.

[0062] In order to avoid flow diversion near each profile, the first profile 31, the second profile 32, the third profile 33, the fourth profile 34 and the fifth profile 35 are all arcs or Bezier curves, so as to avoid the profiles being straight lines, resulting in acceleration of the fitting airflow and flow diversion at the end of each profile.

[0063] In order to avoid flow splitting between the third profile line 33 and the first profile line 31; specifically, as Figure 6 As shown, when the flow separation A is on one side of the main flow channel 1, the third profile 33 can be deflected downward (i.e., V 1 The velocity direction is deflected downward) to reduce the extrusion impact of the main steam flow on the supplementary steam flow, or the first profile 31 is deflected upward (i.e. V 2 The speed direction is deflected upward) to reduce the extrusion impact of the supplementary steam flow on the main steam flow. Figure 7 As shown, when the flow separation A is on the side of the throat 22, the third profile 33 can be deflected upward (i.e., V 1 The speed direction is deflected upward), or the first profile 31 is deflected downward (ie, V 2 Specifically, the axial length L of the third profile 33 is 33 The ratio to the throat width L is: 0.6~1.6.

[0064] In order to improve the working efficiency of the mainstream channel 1, the distance between the fourth profile 34 and the fifth profile 35 is gradually reduced, so that the mainstream channel 1 gradually shrinks the profile at the part where the main steam flow and the supplementary steam flow are mixed, so that the mixed airflow is gradually compressed.

[0065] In order to prevent the supplementary steam flow from being too fast, resulting in a flow dead zone in the main flow channel 1, the speed of the supplementary steam flow pipeline 21 should be limited. Specifically, the supplementary steam flow velocity of the supplementary steam flow pipeline 21 is less than 50m / s, so that the flow velocity of the annular supplementary steam flow chamber 2 can be reduced to less than 20m / s.

[0066] In summary, the present invention controls the flow direction of the supplementary steam flow by setting the first profile 31 and the fifth profile 35 according to actual design requirements when manufacturing the steam turbine supplementary air system; similarly, the present invention fixes the fourth profile 34 and the third profile 33 of the mainstream channel 1, so that the flow direction of the main steam flow is controlled, so that the main steam flow and the supplementary steam flow flow in parallel in the mainstream channel, thereby achieving smooth mixing; in addition, the present invention controls the ratio of the cross section where the supplementary steam flow is located to the cross section where the main steam flow is located, thereby achieving control of the flow velocity difference between the two, thereby avoiding mixing flow loss caused at the dividing line.

[0067] Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0068] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A large flow steam supply device for a steam turbine, It is characterized in that include: A main flow channel (1), wherein a main steam flow moving along a feed direction is present in the main flow channel (1); an annular supplementary steam flow chamber (2), the annular supplementary steam flow chamber (2) being arranged on the outside of the main flow channel (1), the inside of the annular supplementary steam flow chamber (2) being connected to the main flow channel (1) via a throat (22); a supplementary steam flow pipeline (21) is arranged on one side of the annular supplementary steam flow chamber (2); supplementary steam flows into the annular supplementary steam flow chamber (2) from the supplementary steam flow pipeline (21), and then enters the main flow channel (1) from the annular supplementary steam flow chamber (2); The direction of the air flow channel of the throat (22) and the direction of the air flow of the main flow channel (1) are gradually parallel to each other, so that the supplementary steam flow and the main steam flow gradually flow in parallel and in the same direction; in order to make the flow velocities of the supplementary steam flow and the main steam flow as close as possible, the ratio of the cross-section occupied by the supplementary steam flow to the cross-section occupied by the main steam flow is equal to the ratio of the flow rate of the supplementary steam flow to the flow rate of the main steam flow, that is, , where m 1 Main steam flow, m 2 A is the steam supply flow rate; 1 is the cross-sectional area occupied by the main steam flow, A 2 is the cross-sectional area occupied by the supplementary steam flow; The throat (22) comprises a first profile (31) located on one side of the feeding direction and a second profile (32) and a fifth profile (35) located on the other side of the feeding direction; the main flow channel (1) comprises a fourth profile (34) located on the inner side and a third profile (33) located on the outer side; the second profile (32) is connected to the fifth profile (35) below; The distance between the first profile line (31) and the second profile line (32) gradually decreases from the outside to the inside, and the slope of the second profile line (32) gradually decreases from the outside to the inside; the axial length (L) of the first profile line (31) 31 ) to the throat width (L) of the throat opening (22): 0.6-1.6; A transition arc (B) is provided between the second profile line (32) and the fifth profile line (35); the ratio of the radius of the transition arc (B) to the throat width (L) is 0.15-0.55; The distance between the first profile line (31) and the fifth profile line (35) gradually decreases, so as to increase the flow rate of the supplementary steam flow to be consistent with the flow rate of the main steam flow.

2. A large flow steam supplement device for a steam turbine according to claim 1, It is characterized in that The axial length (L 33 ) to throat width (L) is 0.6~1.

6.

3. A large flow steam supplement device for a steam turbine according to claim 1, It is characterized in that The supplementary steam flow velocity of the supplementary steam flow pipeline (21) is less than 50 m / s, and the flow velocity in the annular supplementary steam flow chamber (2) should be less than 20 m / s.

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