CN202417630U - Exhaust hood of small steam turbine - Google Patents

Abstract

The utility model discloses an exhaust hood of a small steam turbine. The exhaust hood of the small steam turbine comprises a volute and a diffuser, wherein the diffuser is composed of an inner guide plate and an outer guide plate, the volute is arranged on the periphery of the diffuser and composed of an upper wall and side walls, the axial width of the volute along the exhaust hood is larger than the width of the diffuser, the outer guide plate is connected with the side walls of the volute, the inner guide plate is arranged in the volute, inner corners at the connection position of the upper wall with the side walls and the connection position of the outer guide plate with the side walls are arc-shaped corners, the side of the inner guide plate is composed of first non-uniform rational splines, and the side of the outer guide plate is composed of second non-uniform rational splines. According to the exhaust hood of the small steam turbine, secondary flow vertex at the inner corners can be prevented, and influences of the secondary flow vertex on steam pressure at a final-stage cascade exit can be eliminated.

Description

A kind of exhaust casing of small steam turbine

Technical field

The utility model relates to the steam turbine equipment technical field, more particularly, relates to a kind of exhaust casing of small steam turbine.

Background technique

The turbine discharge cylinder is the passage that connects outlet of condensing steam turbine final stage leaf grating and vapour condenser, and it mainly acts on is that the leaving velocity kinetic energy that steam turbine mesolow cylinder final stage leaf grating exports is converted into the pressure ability, and the steam discharge of low pressure (LP) cylinder final stage leaf grating is imported vapour condenser.

See also Fig. 1-Fig. 2, existing small steam turbine exhaust casing comprises Diffuser 104 and spiral case 102, wherein, and guide plate 103 and outer guide plate 105 in Diffuser 104 comprises; Spiral case 102 comprises upper wall and sidewall; Spiral case 102 is arranged on the periphery of above-mentioned Diffuser 104, and it is along the width of the axial width of exhaust casing greater than above-mentioned Diffuser 104; Above-mentioned outer guide plate 105 links to each other with above-mentioned sidewall, and interior guide plate 103 is in above-mentioned spiral case 102 inside.The steam discharge in steam turbine last stage leaf grating outlet port has certain circumferential and radial velocity; The steam discharge of upper half part at first gets into exhaust casing along annular steam passage; Upper half part steam discharge overturning in Diffuser 104 to direction radially along the axial of exhaust casing subsequently; Interior guide plate 103 along Diffuser 104 carries out inner arc shunting back entering exhaust casing lower half portion, flows into vapour condenser at last; The steam discharge of lower half portion overturns the back directly along interior guide plate 103 back of the body arcs entering vapour condenser in Diffuser 104.

At first, under the given condition of condenser vacuum, the static pressure that reduces place, steam turbine last stage leaf grating outlet can increase the usable enthalpy drop of steam turbine; Improve the output power of steam turbine, still, in the existing exhaust casing; Each wall angle is rectangular-shaped; And steam flow by exhaust casing axially to exhaust casing upset radially can cause exhaust casing upper half part and lower half portion radially with bigger pressure gradient circumferentially all appears, stronger vortex secondary flow can appear in above-mentioned rectangular-shaped wall angle place, the vortex secondary flow raises its near zone pressure; And further have influence on final stage leaf grating outlet port; Thereby make final stage leaf grating outlet port vapor pressure raise, cause the final stage enthalpy drop to reduce, weakened the acting ability of steam turbine.

Secondly, the outlet pressure of exhaust casing is confirmed, and existing exhaust casing inside is provided with the stiffening rib of circumferentially evenly arranging 101 and reinforcing prop 201; Stiffening rib 101 improves with the vapor pressure that reinforcing prop 201 is located over against the side of flow of steam direction, and the vapor pressure at place, another side reduces, and steam is through above-mentioned stiffening rib 101 and reinforcing prop 201 time; The secondary flow vortex system can occur, above-mentioned secondary flow vortex system is moved in company with main flow, and in flowing, runs into other stiffening rib 101 and reinforcing prop 201; And then be split into much more complicated vortex systems; The exhaust casing pressure inside is had a negative impact, make inner mobile the becoming of exhaust casing move, promptly make the steam turbine last stage outlet pressure be higher than the outlet pressure of exhaust casing along baric flow; Cause small steam turbine final stage enthalpy drop to reduce; Final stage acting ability reduces, and small steam turbine complete machine output power reduces, and aeroperformance is poor.

Also have; Existing exhaust casing inside is provided with and is straight tabular interior guide plate 103 and outer guide plate 105, under big volume flow operating mode, because the above-mentioned straight tabular interior guide plate 103 and the restriction of outer guide plate 105; Steam must could pass through exhaust casing with higher pressure; Cause outer guide plate 105 sharply to expand near the steam at the place, end of spiral case 102, and under the effect of exhaust casing end wall, form strong swirl flow, this swirl flow is with the main flow flow of steam; Make the vortex system in the exhaust casing complicated more, aggravated adverse effect the exhaust casing internal pressure.

The model utility content

In view of this, the utility model provides a kind of exhaust casing of small steam turbine, can prevent that its wall angle place from the whirlpool secondary flow taking place, and eliminates the influence of above-mentioned whirlpool secondary flow to steam turbine last stage leaf grating outlet port vapor pressure.

For realizing above-mentioned purpose, the utility model provides following technological scheme:

A kind of exhaust casing of small steam turbine comprises:

Spiral case; With

The Diffuser that is connected with said spiral case, wherein, guide plate and outer guide plate in said Diffuser comprises; Said spiral case is arranged on the periphery of said Diffuser, comprises upper wall and sidewall; The axial width of the said exhaust casing in said spiral case edge is greater than the width of said Diffuser; Said outer guide plate links to each other with said sidewall, and said interior guide plate is in said spiral case; The wall angle of the joint of said upper wall and said sidewall and said outer guide plate and said sidewall joint is circular-arc wall angle.

Preferably, in the exhaust casing of above-mentioned small steam turbine, the upside and the downside of said spiral case are respectively equipped with stiffening rib; The middle part of said spiral case is provided with reinforcing prop.

Preferably, in the exhaust casing of above-mentioned small steam turbine, said stiffening rib and said reinforcing prop are symmetrical along the vertical straight line at the center of crossing said spiral case respectively; The number of said stiffening rib is 4, and the number of said reinforcing prop is 2.

Preferably, in the exhaust casing of above-mentioned small steam turbine, the outer wall angle of the joint of the joint of said upper wall and said sidewall and said outer guide plate and said spiral case is circular-arc wall angle.

Preferably, in the exhaust casing of above-mentioned small steam turbine, the side that the side of said interior guide plate is made up of the first non-uniform rational b spline curve; The side that the side of said outer guide plate is made up of the second non-uniform rational b spline curve.

Preferably, in the exhaust casing of above-mentioned small steam turbine, the vector rational polynominal function p (u) of said first non-uniform rational b spline curve and the said second non-uniform rational b spline curve is:

$p\left(u\right)=\frac{\underset{i=0}{\overset{n}{\mathrm{\Σ}}}{B}_{i,k}\left(u\right)W_i{V}_i}{\underset{i=0}{\overset{n}{\mathrm{\Σ}}}{B}_{i,k}\left(u\right)W_i}$

Wherein, V _iBe control vertex, W _iBe weight factor, B _{I, k}(u) be k non-uniform rational b spline basic function, function B _{I, k}(u) satisfy:

$B_{i,k}\left(u\right)=\left\{\begin{array}{cc}{B}_{i,0}\left(u\right)=\left\{\begin{array}{cc}1& u_i\&le;u\&le;u_{i+1}\\ 0& u<u_i\\ 0& u>u_{i+1}\end{array}\right.& k=0\\ B_{i,k}\left(u\right)=\frac{{u-u}_i}{u_{i+k}-u_i}{B}_{i,k-1}\left(u\right)+\frac{u_{i+k+1}-u}{u_{i+k+1}-u_{i+1}}{B}_{i+1,k-1}\left(u\right)& k\&GreaterEqual;1\end{array}\right.$

Wherein, u _i(i=0,1 ..., m) be node, and each node is arranged successively to the direction of said spiral case along said Diffuser; The shape of the said first non-uniform rational b spline curve is confirmed by 6 nodes; The said second non-uniform rational b spline curve is confirmed by 9 nodes.

Preferably, in the exhaust casing of above-mentioned small steam turbine, the said first non-uniform rational b spline curve near the tangent direction at place, the end of said spiral case perpendicular to said exhaust casing axially; The said second non-uniform rational b spline curve near the tangent direction at place, the end of said spiral case perpendicular to said exhaust casing axially, the tangent direction at place, the other end is axially identical with said exhaust casing.

Preferably, in the exhaust casing of above-mentioned small steam turbine, the inlet of the said Diffuser in Flow area edge that said interior guide plate and said outer guide plate are formed enlarges to the direction of its outlet gradually.

At first; Than the rectangular-shaped wall angle that has now in the exhaust casing, in the exhaust casing of the small steam turbine that the utility model provides, the wall angle of the joint of the upper wall of spiral case and sidewall joint and spiral case and outer guide plate is circular-arc wall angle; Steam can steadily turn at this wall angle place; Avoided the appearance of whirlpool secondary flow, made this regional pressure normal, eliminated influence small steam turbine final stage outlet port vapor pressure; Avoid the final stage enthalpy drop to reduce, eliminate influence small steam turbine workmanship ability.

Secondly; Than having circumferentially even stiffening rib and the reinforcing prop of arranging in the edge as shown in Figure 2 that rule of thumb is provided with in the exhaust casing now, in the exhaust casing that the utility model provides, analysis is provided with the stiffening rib at spiral case upside and downside as shown in Figure 4 according to three-dimensional stability; And the reinforcing prop in the middle part of spiral case; Wherein, the number of stiffening rib is 4, and the number of reinforcing prop is 2.In the exhaust casing that the utility model provides stiffening rib and reinforcing prop quantity all significantly reduce; Reduced the quantity of secondary vortex system; Alleviated influence to flow stability; Make that inner the flowing of exhaust casing is that contrary baric flow is moving, eliminates the influence to the steam turbine last stage enthalpy drop, and makes steam evenly flow into vapour condenser.Simultaneously, in the exhaust casing that the utility model provides, the joint of upper wall and sidewall and outer guide plate are circular-arc wall angle with the outer wall angle of the joint of spiral case, can avoid stress concentrated, have guaranteed the stablizing of structure of whole exhaust casing.

Also have; The side is a guide plate and straight tabular outer guide plate in plane straight tabular in existing technology, and the interior guide plate that the utility model provides and the side of outer guide plate are respectively the face of the first non-uniform rational b spline curve and second non-uniform rational b spline curve composition.The interior guide plate that the utility model provides can cooperate with the mobile phase of steam with the shape of outer guide plate better, avoids the steam generation flow separation, avoids the formation of swirl flow; Eliminated influence to the exhaust casing internal vapor pressure; Avoid small steam turbine final stage enthalpy drop to reduce, eliminate influence, simultaneously small steam turbine workmanship ability; Make steam evenly flow into vapour condenser, alleviate change impacts bank of condenser pipes.

Have again; In the exhaust casing that the utility model provides; Interior guide plate arrives the direction flaring of outlet with the runner that outer guide plate is formed along the inlet of Diffuser; Make the final stage steam discharge of small steam turbine get into can to form significantly behind the exhaust casing that diffusion flows, promptly streamwise speed reduces, pressure raises.

Description of drawings

In order to be illustrated more clearly in the utility model embodiment or technological scheme of the prior art; To do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art below; Obviously, the accompanying drawing in describing below only is some embodiments of the utility model, for those of ordinary skills; Under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.

Fig. 1 is the side-looking structural representation of the exhaust casing of existing small steam turbine;

Fig. 2 is the main TV structure schematic representation of the exhaust casing of existing small steam turbine;

The side-looking structural representation of the exhaust casing of the small steam turbine that Fig. 3 provides for the utility model embodiment;

The main TV structure schematic representation of the exhaust casing of the small steam turbine that Fig. 4 provides for the utility model embodiment;

Wherein, among Fig. 3-Fig. 4:

Stiffening rib 101; Spiral case 102; Interior guide plate 103; Diffuser 104; Outer guide plate 105; Reinforcing prop 201.

Embodiment

To combine the accompanying drawing among the utility model embodiment below, the technological scheme among the utility model embodiment is carried out clear, intactly description, obviously, described embodiment only is the utility model part embodiment, rather than whole embodiments.Based on the embodiment in the utility model, those of ordinary skills are not making the every other embodiment who is obtained under the creative work prerequisite, all belong to the scope of the utility model protection.

The utility model embodiment discloses a kind of exhaust casing of small steam turbine, can prevent that rectangular-shaped wall angle place from the whirlpool secondary flow taking place, and eliminates the influence of above-mentioned whirlpool secondary flow to steam turbine last stage leaf grating outlet port vapor pressure.

See also Fig. 3-Fig. 4, the exhaust casing of the small steam turbine that the utility model embodiment provides comprises spiral case 102 and Diffuser 104, and wherein, spiral case 102 is arranged on the periphery of Diffuser 104; Spiral case 102 comprises upper wall and sidewall; Guide plate 103 and outer guide plate 105 in Diffuser 104 comprises; Spiral case 102 is along the axial width of the exhaust casing width greater than Diffuser 104; Above-mentioned outer guide plate 105 links to each other with above-mentioned sidewall, and above-mentioned interior guide plate 103 is in the inside of above-mentioned spiral case 102; The joint of above-mentioned upper wall and above-mentioned sidewall, and the wall angle of the joint of above-mentioned outer guide plate 105 and above-mentioned sidewall is circular-arc wall angle.

Than the rectangular-shaped wall angle that has now in the exhaust casing; In the exhaust casing of the small steam turbine that the utility model embodiment provides; The upper wall of spiral case 102 and sidewall joint and spiral case 102 are circular-arc wall angle with the wall angle of the joint of outer guide plate 105, and steam can steadily turn at this wall angle place, has avoided the appearance of whirlpool secondary flow; Make this regional pressure normal; Elimination avoids the final stage enthalpy drop to reduce to the influence of small steam turbine final stage outlet port vapor pressure, eliminates the influence to small steam turbine workmanship ability.

In the foregoing description, the upside of spiral case 102 and downside are respectively equipped with stiffening rib 101, and the both sides at the middle part of spiral case 102 are respectively equipped with reinforcing prop 201, and are as shown in Figure 4, concrete, and the number of stiffening rib 101 is 4, and the number of reinforcing prop 201 is two.Preferably, above-mentioned stiffening rib 101 is symmetrical along the vertical straight line at the center of crossing spiral case 102 respectively with above-mentioned reinforcing prop 201.

In the foregoing description, the joint of upper wall and sidewall, and the outer wall angle of the joint of outer guide plate 105 and spiral case 102 is circular-arc wall angle.

Than having circumferentially even stiffening rib and the reinforcing prop of arranging in the edge as shown in Figure 2 that rule of thumb is provided with in the exhaust casing now; In the exhaust casing that the utility model embodiment provides; Analysis is provided with the stiffening rib 101 at spiral case upside and downside as shown in Figure 4 according to three-dimensional stability, and the reinforcing prop 201 in the middle part of spiral case, wherein; The number of stiffening rib is 4, and the number of reinforcing prop is 2.The quantity of stiffening rib 101 and reinforcing prop 201 all significantly reduces in the exhaust casing that the utility model embodiment provides; Reduced the quantity of secondary vortex system; Alleviated influence to flow stability; Make that inner the flowing of exhaust casing is that contrary baric flow is moving, eliminates the influence to the steam turbine last stage enthalpy drop, and makes steam evenly flow into vapour condenser.Simultaneously, in the exhaust casing that the utility model embodiment provides, the joint of upper wall and sidewall and outer guide plate are circular-arc wall angle with the outer wall angle of the joint of spiral case, can avoid stress concentrated, have guaranteed the stablizing of structure of whole exhaust casing.

In the foregoing description, interior guide plate 103 is bigger than the length of existing guide plate, the side that its side is made up of the first non-uniform rational b spline curve; The side that the side of outer guide plate 105 is made up of the second non-uniform rational b spline curve.The vector rational polynominal p (u) of the first non-uniform rational b spline curve and the second non-uniform rational b spline curve is:

$p\left(u\right)=\frac{\underset{i=0}{\overset{n}{\mathrm{\&Sigma;}}}{B}_{i,k}\left(u\right)W_i{V}_i}{\underset{i=0}{\overset{n}{\mathrm{\&Sigma;}}}{B}_{i,k}\left(u\right)W_i}$

Wherein, V _iBe control vertex, W _iBe weight factor, B _{I, k}(u) be k non-uniform rational b spline basic function, function B _{I, k}(u) satisfy:

$B_{i,k}\left(u\right)=\left\{\begin{array}{cc}{B}_{i,0}\left(u\right)=\left\{\begin{array}{cc}1& u_i\&le;u\&le;u_{i+1}\\ 0& u<u_i\\ 0& u>u_{i+1}\end{array}\right.& k=0\\ B_{i,k}\left(u\right)=\frac{{u-u}_i}{u_{i+k}-u_i}{B}_{i,k-1}\left(u\right)+\frac{u_{i+k+1}-u}{u_{i+k+1}-u_{i+1}}{B}_{i+1,k-1}\left(u\right)& k\&GreaterEqual;1\end{array}\right.$

Wherein, u _i(i=0,1 ..., m) be node, and each node along Diffuser 104 to spiral case 102 direction arrange successively.Wherein, the shape of the first non-uniform rational b spline curve is confirmed that by 6 nodes the second non-uniform rational b spline curve is confirmed by nine nodes; For radially, the tangent direction that the other end is located is identical with the steam flow dispersal direction near place, the end of spiral case tangent direction for the first non-uniform rational b spline curve; For radially, the tangent direction that the other end is located is axially identical with exhaust casing near the tangent direction at place, the end of spiral case for the second non-uniform rational b spline curve.

The side is the straight tabular interior guide plate and straight tabular outer guide plate on plane in the existing technology; The interior guide plate 103 that the utility model embodiment provides and the side of outer guide plate 105 are respectively the face of the first non-uniform rational b spline curve and second non-uniform rational b spline curve composition, and the length of the interior guide plate 103 that extended.The interior guide plate 103 that the utility model embodiment provides and the shape of outer guide plate 105 can cooperate with the mobile phase of steam with size better, avoid the steam generation flow separation, avoid the formation of swirl flow; Eliminated influence to the exhaust casing internal vapor pressure; Avoid small steam turbine final stage enthalpy drop to reduce, eliminate influence, simultaneously small steam turbine workmanship ability; Make steam evenly flow into vapour condenser, alleviate change impacts bank of condenser pipes.

In the foregoing description; Interior guide plate 103 arrives the direction flaring of its outlet with the runner that outer guide plate 105 is formed along the inlet of Diffuser 104; Make the final stage steam discharge of small steam turbine get into can to form significantly behind the exhaust casing that diffusion flows, promptly streamwise speed reduces, pressure raises.

In sum, in whole steam turbine operating mode scopes, the exhaust casing that the utility model embodiment provides can keep higher aeroperformance, and the pitot loss coefficient is significantly reduced; Under the constant condition of other structure and steam parameter, can make the steam turbine output power improve 1%～3%, can make pitot loss coefficient decreased value in the scope of 40%-42%.Simultaneously, the Conncetion cimension of exhaust casing that the utility model embodiment provides and steam turbine and vapour condenser does not change, highly versatile.

Each embodiment adopts the mode of going forward one by one to describe in this specification, and what each embodiment stressed all is and other embodiments' difference that identical similar part is mutually referring to getting final product between each embodiment.

To the above-mentioned explanation of the disclosed embodiments, make related domain professional and technical personnel can realize or use the utility model.Multiple modification to these embodiments will be conspicuous concerning those skilled in the art, and defined General Principle can realize under the situation of spirit that does not break away from the utility model or scope in other embodiments among this paper.Therefore, the utility model will can not be restricted to these embodiments shown in this paper, but will meet and principle disclosed herein and features of novelty the wideest corresponding to scope.

Claims (8)

1. the exhaust casing of a small steam turbine is characterized in that, comprising:

Spiral case (102); With

The Diffuser (104) that is connected with said spiral case (102), wherein, said Diffuser (104) comprises interior guide plate (103) and outer guide plate (105); Said spiral case (102) is arranged on the periphery of said Diffuser (104), comprises upper wall and sidewall; The axial width of the said exhaust casing in said spiral case (102) edge is greater than the width of said Diffuser (104); Said outer guide plate (105) links to each other with said sidewall, and said interior guide plate (103) is in said spiral case (102); The joint of said upper wall and said sidewall and said outer guide plate (105) are circular-arc wall angle with the wall angle of said sidewall joint.

2. the exhaust casing of small steam turbine according to claim 1 is characterized in that, the upside of said spiral case (102) and downside are respectively equipped with stiffening rib (101); The middle part of said spiral case (102) is provided with reinforcing prop (201).

3. the exhaust casing of small steam turbine according to claim 2 is characterized in that, said stiffening rib (101) and said reinforcing prop (201) are symmetrical along the vertical straight line at the center of crossing said spiral case (102) respectively; The number of said stiffening rib (101) is 4, and the number of said reinforcing prop (201) is 2.

4. the exhaust casing of small steam turbine according to claim 3 is characterized in that, the joint of said upper wall and said sidewall and said outer guide plate (105) are circular-arc wall angle with the outer wall angle of the joint of said spiral case (102).

5. the exhaust casing of small steam turbine according to claim 1 is characterized in that, the side that the side of said interior guide plate (103) is made up of the first non-uniform rational b spline curve; The side that the side of said outer guide plate (105) is made up of the second non-uniform rational b spline curve.

6. the exhaust casing of small steam turbine according to claim 5 is characterized in that, the vector rational polynominal function p (u) of said first non-uniform rational b spline curve and the said second non-uniform rational b spline curve is:

$p\left(u\right)=\frac{\underset{i=0}{\overset{n}{\mathrm{\&Sigma;}}}{B}_{i,k}\left(u\right)W_i{V}_i}{\underset{i=0}{\overset{n}{\mathrm{\&Sigma;}}}{B}_{i,k}\left(u\right)W_i}$

Wherein, V _iBe control vertex, W _iBe weight factor, B _{I, k}(u) be k non-uniform rational b spline basic function, function B _{I, k}(u) satisfy:

$B_{i,k}\left(u\right)=\left\{\begin{array}{cc}{B}_{i,0}\left(u\right)=\left\{\begin{array}{cc}1& u_i\&le;u\&le;u_{i+1}\\ 0& u<u_i\\ 0& u>u_{i+1}\end{array}\right.& k=0\\ B_{i,k}\left(u\right)=\frac{{u-u}_i}{u_{i+k}-u_i}{B}_{i,k-1}\left(u\right)+\frac{u_{i+k+1}-u}{u_{i+k+1}-u_{i+1}}{B}_{i+1,k-1}\left(u\right)& k\&GreaterEqual;1\end{array}\right.$

Wherein, u _i(i=0,1 ..., m) be node, and each node is arranged successively to the direction of said spiral case (102) along said Diffuser (104); The shape of the said first non-uniform rational b spline curve is confirmed by 6 nodes; The said second non-uniform rational b spline curve is confirmed by 9 nodes.

7. the exhaust casing of small steam turbine according to claim 6 is characterized in that, the said first non-uniform rational b spline curve near the tangent direction at place, the end of said spiral case (102) perpendicular to said exhaust casing axially; The said second non-uniform rational b spline curve near the tangent direction at place, the end of said spiral case (102) perpendicular to said exhaust casing axially, the tangent direction at place, the other end is axially identical with said exhaust casing.

8. the exhaust casing of small steam turbine according to claim 7 is characterized in that, the inlet of the Flow area said Diffuser in edge (104) that said interior guide plate (103) and said outer guide plate (105) are formed enlarges to the direction of its outlet gradually.

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