Four-tube-pass U-shaped tube type heat exchanger

Abstract

The utility model relates to the technical field of heat exchangers, in particular to a four-tube-pass U-shaped tube type heat exchanger which comprises a tube box, a barrel, a tube plate and a plurality of U-shaped heat exchange tubes, the tube plate is located at the joint of the tube box and the barrel, a cross partition plate groove is formed in the tube plate, a group of cross partition plates are arranged in a cavity of the tube box, and the U-shaped heat exchange tubes are arranged in the tube box. The shape of the end face of the cross-shaped partition plate is matched with the shape of the cross-shaped partition plate groove, a cavity in the tube box is divided into an upper material inlet cavity, a lower material outlet cavity, a left transition cavity and a right transition cavity by the cross-shaped partition plate, the U-shaped heat exchange tubes are divided into four sets, and each set of U-shaped heat exchange tubes are arranged on the cross-shaped partition plate groove of the tube plate in a straddling mode. Wherein the two ends of the upper two groups of U-shaped heat exchange tubes are respectively communicated with the material inlet cavity and the transition cavity on the same side, and the two ends of the lower two groups of U-shaped heat exchange tubes are respectively communicated with the material outlet cavity and the transition cavity on the same side; according to the four-tube-pass U-shaped tube type heat exchanger with the structure, the heat exchange efficiency can be improved when tube pass materials are steam or gas condensation working conditions.

Description

Technical Field

[0001] The utility model relates to the technical field of heat exchangers, in particular to a four-pass U-tube heat exchanger. Background Art

[0002] Tubular heat exchanger is a common heat exchange equipment, widely used in chemical, petroleum, food, pharmaceutical and other industries. It achieves the purpose of heating or cooling by exchanging heat between two fluids of different temperatures flowing inside or outside the tube.

[0003] The shell and tube heat exchanger is composed of a shell, a tube bundle, a tube sheet, a head and other components. There are many structural forms of shell and tube heat exchangers. Among them, the heat exchange tube of the U-tube heat exchanger is bent into a U shape, and both ends are fixed on the same tube sheet. It is suitable for occasions with large temperature differences, high pressure in the tube path, or vibration.

[0004] There is at least one partition in the tube box of the U-tube heat exchanger, which separates the two ends of the U-shaped heat exchange tube, which are the inlet and outlet ends of the tube side materials. When the tube side materials pass through a U-shaped heat exchange tube, they move back and forth along the axis of the cylinder, which belongs to two tube passes. When the diameter of the U-tube heat exchanger is large, in order to improve the heat exchange efficiency, the heat exchanger is usually set to a four-tube pass structure, with two partitions in the tube box, and the two partitions are generally arranged in a T-shape.

[0005] In a conventional four-pass U-tube heat exchanger, when the tube-pass material is steam or gas condensation, in order to ensure that the condensate in the heat exchange tube can be discharged smoothly from the material outlet, the plane where the U-shaped heat exchange tube is located must be in a horizontal state. However, when the condensate flows through the horizontal heat exchange tube, the material that has been condensed into liquid will block the channel in the heat exchange tube, affecting the uncondensed steam or gas from quickly entering the heat exchange tube for heat exchange, thereby reducing the heat exchange efficiency of the heat exchanger.

[0006] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or any form of implication that the information constitutes the prior art known to those skilled in the art. Utility Model Content

[0007] The technical problem to be solved by the utility model is to provide a four-pass U-tube heat exchanger to improve the heat exchange efficiency of the heat exchanger when the tube-pass material is steam or gas condensation working condition.

[0008] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a four-pass U-shaped tube heat exchanger, comprising: a tube box, a cylinder, a tube sheet and a plurality of U-shaped heat exchange tubes, the center line of the cylinder is arranged in the horizontal direction, the tube box and the cylinder are connected to form a closed cavity, the tube sheet is located at the connection between the tube box and the cylinder, and the plurality of U-shaped heat exchange tubes are arranged inside the cylinder, and the ends thereof pass through the tube sheet and communicate with the tube box;

[0009] Wherein, a cross partition groove is arranged on the tube sheet, a group of cross partitions are arranged in the cavity of the tube box, and the shape of the end face of the cross partition matches the cross partition groove on the tube sheet, an inclined angle is formed between the cross partition groove and the horizontal center line of the tube sheet, and the end face of the cross partition is embedded in the cross partition groove;

[0010] The cavity in the tube box is divided by the cross partition to form four cavities, which are a material inlet cavity located at the upper part of the cross partition, a material outlet cavity located at the lower part of the cross partition, and two transition cavities located on the left and right sides of the cross partition. A plurality of U-shaped heat exchange tubes are divided into four groups, and each group of U-shaped heat exchange tubes is arranged astride the cross partition groove of the tube sheet. Two ends of the two groups of U-shaped heat exchange tubes located in the upper area of ​​the cylinder are respectively connected to the material inlet cavity and the transition cavity on the same side, and two ends of the two groups of U-shaped heat exchange tubes located in the lower area of ​​the cylinder are respectively connected to the material outlet cavity and the transition cavity on the same side.

[0011] Furthermore, the pipe box is provided with a pipe-side material inlet and a pipe-side material outlet, and the pipe-side material inlet is communicated with the material inlet cavity, and the pipe-side material outlet is communicated with the material outlet cavity.

[0012] Furthermore, a group of the cross partitions is composed of two partitions arranged crosswise, wherein one partition is broken at the intersection to form two halves.

[0013] Furthermore, the intersection of the cross partition is located on the horizontal center line of the tube sheet, so that the material inlet cavity, the material outlet cavity and the two transition cavities separated by the cross partition are of the same size, and the number of U-shaped heat exchange tubes in each group is the same.

[0014] Furthermore, the intersection of the cross baffle groove on the tube sheet is located below the horizontal center line of the tube sheet, so that the area above the cross baffle groove is larger than the area below; and the number of the two groups of U-shaped heat exchange tubes located in the upper area of ​​the cylinder is greater than the number of the two groups of U-shaped heat exchange tubes located in the lower area of ​​the cylinder.

[0015] Furthermore, the diameters of the two groups of U-shaped heat exchange tubes located in the upper area of ​​the cylinder are larger than the diameters of the two groups of U-shaped heat exchange tubes located in the lower area of ​​the cylinder, and the diameters of the tube holes on the tube sheet through which the U-shaped heat exchange tubes pass match the diameters of the corresponding U-shaped heat exchange tubes.

[0016] Furthermore, a first flange is provided on the outer side surface of the pipe box facing one end of the cylinder, and a second flange is provided on the outer side surface of the cylinder facing one end of the pipe box. Both end surfaces of the tube sheet are respectively fitted with the first flange and the second flange, and a plurality of bolt holes of matching specifications are provided near the outer edges of the tube sheet, the first flange and the second flange. Connecting bolts pass through the bolt holes on the first flange, the tube sheet and the second flange to fix the pipe box, the tube sheet and the cylinder.

[0017] Furthermore, a plurality of baffles are arranged inside the cylinder, and the notches of the baffles are arranged at intervals and staggered along the length direction of the cylinder, and the U-shaped heat exchange tube passes through the tube holes on the baffles and is connected to the tube sheet.

[0018] Furthermore, the cylinder is provided with a shell-side material inlet and a shell-side material outlet which are communicated with the interior of the cylinder.

[0019] Furthermore, two supports are arranged at the bottom of the cylinder.

[0020] The beneficial effects of the utility model are as follows: the utility model arranges the U-shaped heat exchange tube astride the cross partition groove so that the plane where each U-shaped heat exchange tube is located is in an inclined state. After the tube-side material steam or gas enters the material inlet chamber of the tube box, due to the separation effect of the cross partition, it can be divided into left and right paths and pass through the U-shaped heat exchange tube twice for heat exchange, that is, through four tube passes, and all flows are from top to bottom. The condensate formed by the cooling and heat release of the steam or gas can pass through the U-shaped heat exchange tube smoothly without blocking the internal channel of the U-shaped heat exchange tube, thereby greatly improving the heat exchange efficiency of the heat exchanger. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 This is a front view of a four-pass U-tube heat exchanger in Embodiment 1 of the present utility model;

[0023] Figure 2It is a top view of a four-pass U-tube heat exchanger in Embodiment 1 of the present utility model;

[0024] Figure 3 for Figure 2 Sectional view at AA in the middle;

[0025] Figure 4 for Figure 3 The 3-turn cross-sectional view at the middle BB;

[0026] Figure 5 It is a side view of the tube sheet in the first embodiment of the utility model;

[0027] Figure 6 The four-pass U-tube heat exchanger in the second embodiment of the utility model corresponds to Figure 2 Sectional view at AA in the middle;

[0028] Figure 7 It is a side view of the tube plate in the second embodiment of the present utility model.

[0029] Figure numerals: 1. pipe box; 1a. material inlet chamber; 1b. material outlet chamber; 1c. transition chamber; 2. cylinder; 3. tube sheet; 3a. cross partition groove; 3b. channel; 3c. bolt hole; 4. U-shaped heat exchange tube; 5. cross partition; 6. tube side material inlet; 7. tube side material outlet; 8. first flange; 9. second flange; 10. baffle; 11. shell side material inlet; 12. shell side material outlet; 13. support. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0031] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0033] Embodiment 1

[0034] like Figures 1 to 5 The four-pass U-shaped tube heat exchanger shown comprises: a tube box 1, a cylinder 2, a tube sheet 3 and a plurality of U-shaped heat exchange tubes 4. The center line of the cylinder 2 is arranged in the horizontal direction. The tube box 1 and the cylinder 2 are connected to form a closed cavity. The tube sheet 3 is located at the connection between the tube box 1 and the cylinder 2. The plurality of U-shaped heat exchange tubes 4 are arranged inside the cylinder 2, and the ends thereof pass through the tube sheet 3 and are connected with the tube box 1.

[0035] The tube sheet 3 is provided with a cross partition groove 3a, and a group of cross partitions 5 are provided in the cavity of the tube box 1, and the end surface of the cross partition 5 matches the cross partition groove 3a on the tube sheet 3, and an inclined angle is formed between the cross partition groove 3a and the horizontal center line of the tube sheet 3, and the end surface of the cross partition 5 is embedded in the cross partition groove 3a;

[0036] The cavity in the tube box 1 is divided by a cross partition 5 to form four cavities, namely a material inlet cavity 1a located at the upper part of the cross partition groove 3a, a material outlet cavity 1b located at the lower part of the cross partition groove 3a, and two transition cavities 1c located on the left and right sides of the cross partition groove 3a. A plurality of U-shaped heat exchange tubes 4 are divided into four groups, and each group of U-shaped heat exchange tubes 4 is arranged astride the cross partition groove 3a of the tube sheet 3. The two groups of U-shaped heat exchange tubes 4 located in the upper area of ​​the cylinder 2 are connected at both ends to the material inlet cavity 1a and the transition cavity 1c on the same side, and the two groups of U-shaped heat exchange tubes 4 located in the lower area of ​​the cylinder 2 are connected at both ends to the material outlet cavity 1b and the transition cavity 1c on the same side.

[0037] The utility model arranges the U-shaped heat exchange tube 4 astride the cross partition groove 3a so that the plane where each U-shaped heat exchange tube 4 is located is in an inclined state. After the tube-side material steam or gas enters the material inlet chamber 1a of the tube box 1, due to the separation effect of the cross partition 5, it can be divided into left and right paths and pass through the U-shaped heat exchange tube 4 twice for heat exchange, that is, through four tube passes, and all flows are from top to bottom. The condensate formed by the cooling and heat release of the steam or gas can pass through the U-shaped heat exchange tube 4 smoothly, and will not block the internal channel 3b of the U-shaped heat exchange tube 4, thereby greatly improving the heat exchange efficiency of the heat exchanger.

[0038] The four-pass design increases the number and heat exchange area of ​​the U-shaped heat exchange tubes 4, allowing the fluid to flow multiple times inside the heat exchanger, increasing the contact time and area between the fluid and the U-shaped heat exchange tubes 4, thereby improving the overall heat exchange efficiency and effect; and the material inlet chamber 1a, the material outlet chamber 1b and the transition chamber 1c are formed by the cross partition 5 to control the inlet and outlet and flow path of the fluid, thereby improving the heat exchange efficiency of the heat exchanger when the tube-pass material is steam or gas condensation condition; and the embedded matching structure between the cross partition 5 and the cross partition groove 3a facilitates installation and disassembly, which is beneficial to the maintenance and cleaning of the heat exchanger.

[0039] On the basis of the above embodiment, a tube-side material inlet 6 and a tube-side material outlet 7 are provided on the tube box 1, and the tube-side material inlet 6 is connected with the material inlet cavity 1a, and the tube-side material outlet 7 is connected with the material outlet cavity 1b; it is ensured that the tube-side material entering the tube box 1 can pass through the U-shaped heat exchange tube 4 twice, so as to realize the uniform distribution of the tube-side material in the heat exchanger, prevent the occurrence of uneven flow problems, thereby improving the utilization rate of the heat exchange tube and improving the overall heat exchange efficiency.

[0040] On the basis of the above-mentioned embodiment, a group of cross partitions 5 is composed of two partitions arranged crosswise, one of which is broken at the intersection to form two halves; the cross arrangement of the cross partitions 5, on the one hand, helps to guide the tube-side material and reduce the flow resistance of the tube-side material inside the U-shaped heat exchange tube 4, and on the other hand, increases the structural stability, so that the cross partitions 5 maintain the stability of the connection under the flow of tube-side material and pressure changes.

[0041] On the basis of the above embodiment, the intersection of the cross partition 5 is located on the horizontal center line of the tube sheet 3, so that the material inlet cavity 1a, the material outlet cavity 1b and the two transition cavities 1c separated by the cross partition 5 have the same space size, and the number of roots of each group of U-shaped heat exchange tubes 4 is the same; it helps to achieve balanced heat exchange efficiency in each area; and the symmetrical design simplifies the manufacturing and assembly process of the heat exchanger, facilitating standardized production.

[0042] On the basis of the above embodiment, a first flange 8 is provided on the outer side surface of the tube box 1 facing one end of the cylinder 2, and a second flange 9 is provided on the outer side surface of the cylinder 2 facing one end of the tube box 1. The two end surfaces of the tube sheet 3 are respectively fitted with the first flange 8 and the second flange 9, and the tube sheet 3, the first flange 8 and the second flange 9 are provided with a plurality of bolt holes 3c of matching specifications near the outer edges. The connecting bolts pass through the bolt holes on the first flange 8, the tube sheet 3 and the second flange 9 to fix the tube box 1, the tube sheet 3 and the cylinder 2. By using the first flange 8, the second flange 9 and the connecting bolts, the alignment and connection of the tube sheet 3 with the tube box 1 and the cylinder 2 are more convenient, and better sealing performance is achieved to prevent fluid leakage. At the same time, it is also convenient for future disassembly and maintenance, and the stability and rigidity of the entire heat exchanger structure are improved.

[0043] On the basis of the above-mentioned embodiment, a plurality of baffles 10 are arranged inside the cylinder 2, and the notches of the baffles 10 are arranged at intervals and staggered along the length direction of the cylinder 2, and the U-shaped heat exchange tube 4 passes through the tube holes on the baffles 10 and is connected to the tube sheet 3; the fixed connection between the baffle 10 and the inner wall of the cylinder 2 increases the structural stability of the entire heat exchanger; the setting of the baffle 10 can change the flow direction of the shell-side material in the cylinder 2, change the flow rate of the shell-side material, and also reduce the formation of temperature difference, thereby improving the heat exchange efficiency; the tube holes on the baffle 10 allow the U-shaped heat exchange tube 4 to pass through and be connected to the tube sheet 3, while avoiding the direct impact of the fluid on the heat exchange tube and reducing wear.

[0044] On the basis of the above embodiment, a shell-side material inlet 11 and a shell-side material outlet 12 which are connected to the interior of the cylinder 2 are provided on the cylinder 2; the horizontally arranged cylinder 2 facilitates the control of the inlet and outlet and flow direction of the shell-side material; and the arrangement of the shell-side material inlet 11 and the shell-side material outlet 12 enables the shell-side material to be filled into the complete cavity of the cylinder 2, thereby ensuring the heat exchange efficiency.

[0045] On the basis of the above embodiment, two supports 13 are provided on the cylinder 2 to facilitate the installation and fixing of the heat exchanger on the ground; and the supports 13 can provide additional support, reduce the vibration and displacement of the cylinder 2 under fluid flow and pressure changes, evenly distribute the weight of the cylinder 2 and the fluid load, and reduce local stress.

[0046] Embodiment 2

[0047] like Figure 6 to Figure 7 As shown, this embodiment provides another structural form of the cross partition 5 and the tube sheet 3, and the structural settings of the remaining components such as the cylinder 2, the tube side material inlet 6, the tube side material outlet 7, the shell side material inlet 11, the shell side material outlet 12 and other components are the same as the structural settings in the first embodiment and are not repeated here.

[0048] The intersection of the cross baffle groove 3a on the tube sheet 3 is located below the horizontal center line of the tube sheet 3, so that the area above the cross baffle groove is larger than the area below; and the number of the two groups of U-shaped heat exchange tubes 4 located in the upper area of ​​the cylinder 2 is greater than the number of the two groups of U-shaped heat exchange tubes 4 located in the lower area of ​​the cylinder 2.

[0049] By reasonably allocating the number of U-shaped heat exchange tubes 4 in different areas of the cylinder 2, a higher heat exchange efficiency can be achieved in a limited space; when the tube-side materials such as heating steam enter the tube box 1 from the tube-side material inlet 6, after passing through the two groups of U-shaped heat exchange tubes 4 in the upper area of ​​the cylinder 2 for the first time, a part of the steam has been condensed into water, and the volume flow rate through the two groups of U-shaped tubes in the lower part has been greatly reduced. At this time, the number of U-shaped heat exchange tubes 4 in the lower part can be less, which is beneficial to improving the overall heat exchange efficiency of the heat exchanger. At the same time, reducing the number of U-shaped heat exchange tubes 4 in the lower part can reduce the use of materials and reduce costs.

[0050] On the basis of the above-mentioned embodiment, the diameters of the two groups of U-shaped heat exchange tubes 4 located in the upper area of ​​the cylinder 2 are larger than the diameters of the two groups of U-shaped heat exchange tubes 4 located in the lower area of ​​the cylinder 2, and the diameters of the tube holes 3b on the tube sheet 3 for the U-shaped heat exchange tubes 4 to pass through are matched with the diameters of the corresponding U-shaped heat exchange tubes 4; the diameters of the U-shaped heat exchange tubes 4 connected to the material inlet cavity 1a are larger and can adapt to the initial fluid flow entering the heat exchanger, while the diameters of the U-shaped heat exchange tubes 4 connected to the material outlet cavity 1b are correspondingly reduced due to the reduced flow to adapt to the reduced flow; the diameters of the channels 3b on the tube sheet 3 are matched with the diameters of the U-shaped heat exchange tubes 4, thereby ensuring the consistency and sealing of the structure.

[0051] Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the description are only for explaining the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which are within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A four-pass U-tube heat exchanger, characterized in that: include: A tube box, a cylinder, a tube sheet and a plurality of U-shaped heat exchange tubes, wherein the center line of the cylinder is arranged in the horizontal direction, the tube box and the cylinder are connected to form a closed cavity, the tube sheet is located at the connection between the tube box and the cylinder, and a plurality of U-shaped heat exchange tubes are arranged inside the cylinder, and the ends of the tubes pass through the tube sheet and are connected to the tube box; Wherein, a cross partition groove is arranged on the tube sheet, a group of cross partitions are arranged in the cavity of the tube box, and the shape of the end face of the cross partition matches the cross partition groove on the tube sheet, an inclined angle is formed between the cross partition groove and the horizontal center line of the tube sheet, and the end face of the cross partition is embedded in the cross partition groove; The cavity in the tube box is divided by the cross partition to form four cavities, which are a material inlet cavity located at the upper part of the cross partition, a material outlet cavity located at the lower part of the cross partition, and two transition cavities located on the left and right sides of the cross partition. A plurality of U-shaped heat exchange tubes are divided into four groups, and each group of U-shaped heat exchange tubes is arranged astride the cross partition groove of the tube sheet. Two ends of the two groups of U-shaped heat exchange tubes located in the upper area of ​​the cylinder are respectively connected to the material inlet cavity and the transition cavity on the same side, and two ends of the two groups of U-shaped heat exchange tubes located in the lower area of ​​the cylinder are respectively connected to the material outlet cavity and the transition cavity on the same side.

2. The four-pass U-tube heat exchanger according to claim 1, characterized in that: The pipe box is provided with a pipe-side material inlet and a pipe-side material outlet, and the pipe-side material inlet is communicated with the material inlet cavity, and the pipe-side material outlet is communicated with the material outlet cavity.

3. The four-pass U-tube heat exchanger according to claim 1, characterized in that: A group of cross partitions is composed of two partitions arranged crosswise, wherein one partition is broken at the intersection to form two halves.

4. The four-pass U-tube heat exchanger according to claim 3, characterized in that: The intersection of the cross partition is located on the horizontal center line of the tube sheet, so that the material inlet cavity, the material outlet cavity and the two transition cavities separated by the cross partition are of the same size, and the number of U-shaped heat exchange tubes in each group is the same.

5. The four-pass U-tube heat exchanger according to claim 1, characterized in that: The intersection of the cross baffle groove on the tube sheet is located below the horizontal center line of the tube sheet, so that the area above the cross baffle groove is larger than the area below; and the number of the two groups of U-shaped heat exchange tubes located in the upper area of ​​the cylinder is greater than the number of the two groups of U-shaped heat exchange tubes located in the lower area of ​​the cylinder.

6. The four-pass U-tube heat exchanger according to claim 5, characterized in that: The diameters of the two groups of U-shaped heat exchange tubes located in the upper area of ​​the cylinder are larger than the diameters of the two groups of U-shaped heat exchange tubes located in the lower area of ​​the cylinder, and the diameters of the tube holes on the tube sheet through which the U-shaped heat exchange tubes pass match the diameters of the corresponding U-shaped heat exchange tubes.

7. The four-pass U-tube heat exchanger according to claim 1, characterized in that: A first flange is provided on the outer side surface of the pipe box facing one end of the cylinder, and a second flange is provided on the outer side surface of the cylinder facing one end of the pipe box. Both end surfaces of the tube sheet are respectively fitted with the first flange and the second flange, and a plurality of bolt holes of matching specifications are provided near the outer edges of the tube sheet, the first flange and the second flange. Connecting bolts pass through the bolt holes on the first flange, the tube sheet and the second flange to fix the pipe box, the tube sheet and the cylinder.

8. The four-pass U-tube heat exchanger according to claim 1, characterized in that: A plurality of baffles are arranged inside the cylinder, and the notches of the baffles are arranged at intervals and staggered along the length direction of the cylinder. The U-shaped heat exchange tube passes through the tube holes on the baffles and is connected to the tube sheet.

9. The four-pass U-tube heat exchanger according to claim 1, characterized in that: The cylinder is provided with a shell-side material inlet and a shell-side material outlet which are communicated with the interior of the cylinder.

10. The four-pass U-tube heat exchanger according to claim 1, characterized in that: Two supports are arranged at the bottom of the cylinder.

Images