Steam separator
By designing the structure of the steam separator body and the steam discharge pipeline with step flow area changes, the problems of poor steam separation effect and high fiber quantity in the prior art are solved, and more efficient steam and fiber separation is achieved.
Patent Information
- Application Number
- CN202411150115.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-08-23
- Filing Date
- 2024-08-21
- Publication Date
- 2025-02-25
AI Technical Summary
When the existing steam separator separates the flow of steam and cellulose materials, the separation effect is poor, and the amount of fiber in the separated steam is relatively high, which affects the process efficiency.
A steam separator is designed including a body and at least one steam discharge pipe, the body consists of the first, second and third parts, the flow area changes step by step between different parts, and the inlet of the steam discharge pipe is located in the first part The outer side of the second part is connected to the upstream end.
The "retreating step" flow caused by the rapid increase in the flow area reduces the amount of fiber entering the steam discharge pipeline and improves the separation effect of steam and fibers.
Smart Images
Figure CN119499763A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of pulp production from cellulosic material and more particularly to a steam separator by means of which steam can be separated from a flow of fluid and cellulosic material. Background Art
[0002] Pulp production processes typically include a steam separation step, in which a fluid, such as steam, is separated from a stream comprising the fluid and cellulosic material, such as wood chips / fibers, which is conveyed in a conduit, such as a blowpipe.
[0003] SE544371C2 discloses a steam separator for pulp production process, which comprises a first flow tube and a second flow tube, wherein the first flow tube is inserted into the second flow tube by a certain distance, so that a gap is provided between the outer periphery of the first flow tube and the inner periphery of the second flow tube, and wherein at least one steam delivery tube has a steam inlet opening, which is arranged as a through hole through the wall of the second flow tube. Summary of the invention
[0004] The object of the present invention is to provide a steam separator which has further improved properties with regard to improving the separation effect and reducing the amount of fibers in the separation steam.
[0005] These and other objects are achieved by the invention by means of a steam separator according to the independent claims.
[0006] According to the present invention, a steam separator is provided for separating steam from a flow comprising steam and cellulosic material (such as cellulose or wood fiber). The steam separator comprises a substantially tubular or hollow body and at least one steam discharge conduit, through which the flow is conveyed in a longitudinal flow direction, the body comprising a first longitudinal continuous portion, a second longitudinal continuous portion and a third longitudinal continuous portion. The downstream end (facing the second portion) of the first portion has a first flow area, which is smaller than the second flow area of the upstream end (facing the first portion) of the second portion. The downstream end (facing the third portion) of the second portion has a third flow area, which is smaller than the fourth flow area of the upstream end (facing the second portion) of the third portion. At least a portion of at least one steam discharge conduit is radially / transversely arranged outside the first portion, each steam discharge conduit being provided with its inlet, which is connected to the upstream end of the second portion to receive steam therefrom.
[0007] In other words, the steam separator includes a body, which can be substantially tubular or hollow and can be described as a pipe. The body includes a first part, a second part and a third part arranged continuously in the order described. The steam separator also includes at least one steam discharge pipe for discharging separated steam from the flow / main stream flowing through the steam separator body. At the downstream end of the first part / the upstream end of the second part, the (first) flow area of the first part is smaller than the (second) flow area of the second part, so that the flow area increases at the transition from the first part to the second part. At the downstream end of the second part / the upstream end of the third part, the (third) flow area of the second part is smaller than the (fourth) flow area of the third part, so that the flow area increases at the transition from the second part to the third part. At least one steam discharge pipe is each radially / transversely provided with an inlet connected to the second part outside the first part at the downstream end of the first part / the upstream end of the second part. At least one steam discharge pipe and / or its inlet can be guided substantially longitudinally. The body can be substantially cylindrical, but can also have a cross-section of other shapes, such as square or elliptical.
[0008] The invention is based on the recognition that a rapid increase / step in flow area downstream of the inlet of the steam exhaust duct(s) results in a "backstep" flow (comprising steam and fibers) that circulates locally at the step that will follow the main flow in the downstream direction. This can reduce the amount of fibers that follow the steam flow into the steam exhaust duct(s).
[0009] In various embodiments, the second portion at least partially tapers toward the third portion. The second portion may include an upstream portion that tapers toward the third portion and a downstream portion having a substantially constant flow area. Such embodiments may be advantageous in steam separation because the tapered shape may increase flow to the steam exhaust conduit(s).
[0010] In various embodiments, the ratio between the first flow area and the third flow area is in the range of 0.8-1.2, such as 0.9-1.1. The first flow area and the third flow area can be substantially equal. Embodiments in which the first flow area and the third flow area are substantially equal or in the above range are advantageously combined with the above embodiments comprising a tapered second portion. This combination of embodiments can provide advantageous separation performance and / or a reduced level of fibers in the separation steam.
[0011] In various embodiments, the ratio between the fourth flow area and the second flow area is in the range of 0.8-1.2, such as 0.9-1.1. The fourth flow area and the second flow area may be substantially equal.
[0012] In various embodiments, the first portion and at least one steam discharge conduit are formed by concentric / coaxial inner and outer tubes. The inner and outer tubes may only partially overlap (as seen in the longitudinal direction). A gap is formed between the outer periphery of the inner tube and the inner periphery of the outer tube, in which the steam may flow in an upstream direction (i.e., flow in the opposite direction compared to the mainstream in the inner tube). Therefore, at least one steam discharge conduit is formed by the gap / space between the inner and outer tubes. The inner and outer tubes may be referred to as inner and outer tubes. The inner and outer tubes or the inner and outer tubes may have a substantially circular cross section.
[0013] In an embodiment, at least one steam discharge conduit may be formed only along the corresponding portion of the periphery of the inner tube / outer tube. In other words, (one or more) steam discharge conduits do not necessarily need to be formed by the entire space between the inner tube and the outer tube. For example, the steam separator may include two steam discharge conduits, each of which has an angle extension of 60-170 degrees. Such an embodiment allows structural reinforcement between the inner tube and the outer tube.
[0014] In various embodiments, at least one steam discharge conduit each comprises an outlet formed as a through hole through the outer tube, and wherein a corresponding steam delivery conduit is connected to each outlet. In embodiments comprising more than one steam delivery conduit, such as at least two steam delivery conduits, the steam delivery conduits are preferably merged or linked together to form a common steam manifold that can direct the separated steam to a suitable receiving device, such as a tablet box.
[0015] In various embodiments, the third portion is integrally formed with the outer tube. In such embodiments, the second portion may be integrally formed with the inner tube as an insert arranged within the outer tube. Such embodiments are advantageous because a simple and easy to assemble construction is provided.
[0016] In various embodiments, the first portion is provided with a throttling device, for example by tapering along at least a portion of the longitudinal length of the first portion toward the second portion. For example, the inner tube may have a tapering shape in a direction toward the second portion. This embodiment is advantageously combined with the above-mentioned embodiment comprising a concentric inner tube and an outer tube. In such a combined embodiment, wherein the outer tube is cylindrical or at least tapers at a slower rate than the inner tube, at least one steam exhaust conduit expands toward the second portion, which may result in an increase in the steam flow rate entering the steam exhaust passage and / or an increase in separation. Further, the throttling effect itself may provide an enhanced separation effect.
[0017] The features of the above-described embodiments may be combined in any practicable way to form an embodiment having a combination of those features. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The above and other aspects of the present invention will now be described in more detail using the accompanying drawings, which show currently preferred embodiments of the present invention, in which:
[0019] Figure 1 A schematic perspective view of an embodiment of a steam separator according to the present invention is shown;
[0020] Figure 2 Shows Figure 1 A cross-sectional view of a portion of a steam separator in the embodiment of the present invention, the cross-sectional view being taken at a horizontal plane passing through a steam separator body and a steam delivery conduit;
[0021] Figure 3 Shown with Figure 2 The same cross-sectional view, but with schematic flow arrows, and
[0022] Figure 4 Shown with Figure 1-3 A cross-sectional view of an alternative embodiment similar to the embodiment in FIG. DETAILED DESCRIPTION
[0023] Figure 1 A schematic perspective view of an embodiment of a steam separator according to the invention is shown. The steam separator 1 comprises a tubular / hollow body 2 through which the steam is conveyed in the longitudinal flow direction (right side in the figure). The body comprises a first longitudinal continuous section 3, a second longitudinal continuous section 4 and a third longitudinal continuous section 5 (each section having a circular cross section) and at least one steam discharge conduit (reference numeral 6, see Figure 2 ).exist Figure 1 In the figure, the right side shows the further downstream part (the tapered part and the cylindrical part) of the body 2 and the flanges at the opposite ends of the steam separator for connecting the steam separator to, for example, a pipeline. The corresponding steam delivery pipelines 9a, 9b are connected to the steam discharge pipeline.
[0024] Figure 2 Shows Figure 1 sectional view of a portion of the steam separator in FIG. 1 , the sectional view is taken in a horizontal plane through the steam separator body 2 and the steam delivery pipes 9a, 9b (from Figure 1 ). Figure 2 In the figure, the flange and the above-mentioned downstream part of the body 2 are not shown. Figure 2It can be seen that the downstream end 3b of the first portion 3 facing the second portion 4 has a first flow area A1 that is smaller than a second flow area A2 of the second portion 4 facing the upstream end 4a of the first portion 3. The downstream end 4b of the second portion 4 faces the third portion 5 and has a third flow area A3 that is smaller than a fourth flow area A4 of the third portion 5 facing the upstream end 5a of the second portion 4. Therefore, a sudden increase ("step") in flow area is formed at 3b, 4a and 4b, 5a.
[0025] The first flow area A1 is substantially equal to the third flow area A3, ie, the diameters D1 and D3 are substantially equal.
[0026] The third portion 5 is formed as part of an outer tube 8 and the inner wall of the second portion is formed as an insert in the outer tube.The fourth flow area A4 and the second flow area A2 are substantially equal, ie the diameters D4 and D2 are substantially equal.
[0027] Two steam exhaust ducts 6a, 6b are arranged radially outside the first portion 3, each of which is provided with its inlet 6a', 6b' connected to the upstream end 4a of the second portion 4 to receive steam therefrom.
[0028] The first part 3 and the two steam exhaust ducts 6a, 6b are formed by (partially concentric) inner and outer tubes / tubes 7, 8. The steam exhaust ducts 6a, 6b are formed by the gap between the outer periphery of the inner tube 7 and the inner periphery of the outer tube 8. However, the two steam exhaust ducts are separated from each other by having a limited angular extension. The steam exhaust ducts each include an outlet 6a", 6b", which are formed as through holes through the outer tube 8. Steam delivery ducts 9a, 9b are connected to the respective outlets. As shown in FIG. Figure 1 As can be seen, the steam delivery conduits 9a, 9b are linked together to form a common steam manifold which can direct the separated steam to a suitable receiving device, such as a tablet box.
[0029] The portion of the inner tube 7 extending into the outer tube 8 tapers towards the second portion 4 so that a throttling effect is achieved in the first portion 3. The second portion 4 comprises an upstream portion 4' tapering towards the third portion 5 and a downstream portion 4" having a constant diameter / flow area.
[0030] Figure 3 Shown with Figure 2 Same cross-section view, but with schematic flow stream arrows.
[0031] During operation, the flow including steam and cellulosic material (fibers) enters the first part 3 (inner tube 7) on the left side of the figure of the body and leaves the first part at its downstream end 3b and enters the second part 4. At this location, the flow area / diameter of the upstream end 4a of the second part is larger than the flow area / diameter of the downstream end 3b of the first part, which means that the flow can expand radially, and since steam is compressible, it will expand rapidly. In this rapid expansion and redirection of the flow, heavier particles such as cellulosic fibers will flow mainly in the main direction of the tube flow due to momentum.
[0032] Therefore, at the upstream end 4a of the second part, the flow mainly includes steam, which can travel backward through the steam discharge pipe (e.g., 6a) and then enter the steam delivery pipe 9a, 9b to transport the steam away. The flow of this steam is shown by the topmost flow arrow F1 entering 6a. The closer to the center of the steam separator, the less the flow is affected by the step increase in diameter at 3b, 4a, and the flow of steam and fiber will flow as shown in the second flow arrow F2. When the flow leaves the second part 4 at its downstream end 4b and enters the third part 5, the flow area / diameter of the upstream end 5a of the third part is greater than the flow area / diameter of the downstream end 4b of the second part. A local recirculation "backflow" F3 of steam and fiber will be formed, which will follow the mainstream in the downstream direction.
[0033] In the center of the steam separator, the flow comprising steam and cellulosic material is substantially unaffected by the step-wise increase in diameter at 3b, 4a and 4b, 5a. This is shown by the fourth flow arrow F4. The flow arrows are only shown in the upper part of the steam separator, but it will be understood that the flow is generally symmetrical.
[0034] Figure 4 A cross-sectional view of an alternative embodiment of a steam separator according to the present invention is shown. Figure 2-3 This embodiment corresponds to Figure 1-3 The embodiment of the present invention is different in that the first portion 13 is not tapered and the second portion 14 is tapered along its entire length. Figure 1-3 The remainder of the description (including the operation of the steam separator) also applies to Figure 4 Note that the first flow area is substantially equal to the third flow area, ie, diameters D11 and D13 are substantially equal, and the fourth flow area and the second flow area are also substantially equal, ie, diameters D14 and D12 are substantially equal.
[0035] The above description and accompanying drawings should be regarded as non-limiting examples of the present invention. Those skilled in the art will recognize that several changes and modifications may be made within the scope of the present invention. For example, the steam discharge conduit(s) need not necessarily be formed by concentric tubes, or even integrally formed with the body of the steam separator, but may instead be separate components. Furthermore, the number of steam discharge conduits and steam delivery conduits may vary.
Claims
1. A steam separator (1) for separating steam from a flow comprising steam and cellulosic material, the steam separator comprising: - a substantially tubular body (2) through which the flow is conveyed in a longitudinal flow direction, said body comprising a first longitudinally continuous portion, a second longitudinally continuous portion and a third longitudinally continuous portion (3, 4, 5), and - at least one steam discharge duct (6a, 6b), wherein a downstream end (3b) of the first portion (3) facing the second portion (4) has a first flow area (A1), the first flow area being smaller than a second flow area (A2) of an upstream end (4a) of the second portion (4) facing the first portion (3), wherein the downstream end (4b) of the second portion (4) facing the third portion (5) has a third flow area (A3), the third flow area being smaller than a fourth flow area (A4) of the upstream end (5a) of the third portion (5) facing the second portion (4), and The at least one steam discharge conduit (6a, 6b) is arranged radially outside the first portion (3), each steam discharge conduit (6a, 6b) being provided with its inlet (6a') connected to the upstream end (4a) of the second portion (4) to receive steam therefrom.
2. The steam separator according to claim 1, characterized in that The second portion (4) tapers at least partially towards the third portion.
3. The steam separator according to claim 1, characterized in that The second portion (4) comprises an upstream portion (4') tapering towards the third portion (5) and a downstream portion (4") having a substantially constant flow area.
4. A steam separator according to any one of the preceding claims, characterised in that A ratio between the first flow area (A1) and the third flow area (A3) is in the range of 0.8-1.2, such as 0.9-1.
1.
5. A steam separator according to any one of the preceding claims, characterised in that A ratio between the fourth flow area (A4) and the second flow area (A2) is in the range of 0.8-1.2, such as 0.9-1.
1.
6. A steam separator according to any one of the preceding claims, characterised in that The first portion (3) and the at least one steam exhaust duct (6a, 6b) are formed by concentric inner (7) and outer (8) tubes, the at least one steam exhaust duct (6a, 6b) being formed by the space between the inner and outer tubes.
7. The steam separator according to claim 6, characterized in that The at least one steam discharge conduit (6a, 6b) is formed only along a corresponding portion of the circumference of the inner tube (7).
8. The steam separator according to claim 6 or 7, characterized in that: The at least one steam exhaust conduit (6a, 6b) each comprises an outlet (6a", 6b") formed as a through hole passing through the outer tube (8), and wherein a corresponding steam delivery conduit (9a, 9b) is connected to the outlet.
9. The steam separator according to any one of claims 6 to 8, characterized in that: The third portion (5) is formed integrally with the outer tube (8).
10. A steam separator according to any one of the preceding claims, characterised in that The first portion (3) is provided with a throttling device, for example by tapering along at least a portion of the longitudinal length of the first portion towards the second portion (4).