Drainage device and blast furnace granulated slag bottom filter

Abstract

The utility model provides a drainage device and a blast furnace granulated slag bottom filter tank, and relates to the technical field of metal smelting equipment. The drainage device comprises a plurality of drainage assemblies arranged in a filter tank, a water outlet structure arranged on the filter tank, a first communication structure for communicating the water outlet structure with the drainage assemblies, and a second communication structure, and each drainage assembly comprises a drainage main pipe and a plurality of first drainage branch pipes; the first drainage branch pipes are arranged at intervals and communicated with the corresponding drainage main pipes, the drainage main pipes are arranged at intervals, and the adjacent drainage main pipes are communicated through second communication structures. The length of the first drainage branch pipe can be reduced by arranging the multiple drainage assemblies, and the water flow rate and pressure of the tail end of the first drainage branch pipe are improved. And moreover, the adjacent main drainage pipes are communicated through the second communication structures, so that the water pressure in the main drainage pipes can be ensured during back flushing, and the back flushing effect is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of metal smelting equipment, in particular to a drainage device and a blast furnace slag bottom filter tank. Background Art

[0002] High-temperature liquid slag is the main by-product of blast furnace smelting. It has the characteristics of high temperature (1350℃-1500℃) and large output (about 300 million tons), which makes high-temperature liquid slag have extremely high reuse value. At present, the treatment methods of high-temperature slag in steel enterprises mainly include water slag flushing and dry slag. Dry slag refers to the slag after slag and iron separation is drained into the dry slag pit through the slag ditch for natural cooling. Common water slag flushing processes include INBA method, Jiaheng method, Minte method and environmental protection bottom filtration method. Among them, the environmental protection bottom filtration process has the advantages of high safety, low steam emission, good production environment and high degree of automation. The environmentally friendly bottom filtration process refers to the slag being introduced into the granulation pool through the slag ditch. During the slag flow, the granulator installed at the end of the slag ditch sprays high-speed water flow to crush, quench and granulate the slag. The quenched slag-water mixture flows into the working filter pool through the outlet equipment and the slag-flushing ditch, and is filtered in the filter pool. The filtered slag-flushing water passes through the filter layer and the filter pool filter pipe, and is pumped into the cooling tower by the upper tower pump for cooling and circulating slag-flushing. At the same time, the slag-flushing pump regularly pumps the slag-flushing water into the filter pool filter pipe to backwash the filter pipe and the filter layer.

[0003] According to actual production, the filter media in the filter tank will become compacted after the environmentally friendly bottom filtration process has been put into use for a long time. The main reason is that a large number of fine glass fibers are trapped between the small particle filter media in the top layer during the slag-water separation process, reducing the overall porosity of the filter layer. At the same time, alkaline slag water is rich in calcium and magnesium ions, and the low porosity also provides a favorable place for the crystallization of calcium and magnesium ions, further aggravating the compaction between the filter layers. The compaction of filter media in different areas of the same filter tank is different. The water permeability of filter media in severely compacted areas is seriously insufficient, and local "pipe surges" occur during the backwashing process. In addition, in order to ensure the continuity of production, there is often not enough maintenance time to maintain and replace the filter media and filter tubes in the filter tank. Therefore, how to prevent the compaction of filter media in the filter tank to extend the service life of the filter layer has become a technical problem that needs to be solved urgently. Utility Model Content

[0004] In order to overcome the above-mentioned defects of the prior art, the technical problem to be solved by the embodiments of the utility model is to provide a drainage device and a blast furnace slag bottom filter tank, which are used to prevent the filter material in the filter tank from becoming compacted to extend the service life of the filter layer, which has become a technical problem that needs to be solved urgently.

[0005] The above-mentioned purpose of the utility model can be achieved by adopting the following technical scheme. The utility model provides a drainage device for being arranged in a filter tank, including multiple drainage components arranged in the filter tank, a water outlet structure arranged on the filter tank, a first connecting structure connecting the water outlet structure with each of the drainage components, and a second connecting structure. The drainage component includes a drainage main pipe and multiple first drainage branch pipes. The multiple first drainage branch pipes are arranged at intervals and connected to the corresponding drainage main pipes. The drainage main pipes are arranged at intervals, and the adjacent drainage main pipes are connected through the second connecting structure.

[0006] In a preferred embodiment of the present invention, the bottom of the filter tank is divided into a plurality of relatively independent drainage partitions along the width direction of the filter tank, and each of the drainage partitions is provided with a drainage component.

[0007] In a preferred embodiment of the present utility model, the water outlet structure includes a water outlet arranged on the pool wall of the filter pool, and the water outlet is connected to each of the drainage main pipes through the first connecting structure.

[0008] In a preferred embodiment of the present invention, the first communication structure includes a communication joint, and the communication joint is provided with a first port connected to the water outlet and a plurality of second ports connected to each of the drainage main pipes.

[0009] In a preferred embodiment of the present invention, the drainage main pipe is detachably connected to the corresponding second port.

[0010] In a preferred embodiment of the present invention, the main drainage pipe is arranged along the length direction of the filter tank, and a plurality of the first drainage branches are arranged along the width direction of the filter tank and are connected to the corresponding main drainage pipes.

[0011] In a preferred embodiment of the present invention, at least one flow hole is provided on the first drainage branch pipe, and a branch pipe end plugging plate is provided at the end of the first drainage branch pipe away from the drainage main pipe.

[0012] In a preferred embodiment of the present invention, a main pipe end plugging plate is provided at one end of the drainage main pipe away from the water outlet structure.

[0013] In a preferred embodiment of the present invention, the second connecting structure is arranged at an end of the drainage component away from the water outlet structure, and the second connecting structure includes at least one second drainage branch pipe connected to the adjacent drainage main pipe.

[0014] The utility model also provides a blast furnace slag bottom filter tank, comprising a filter tank and the aforementioned drainage device, wherein a filter layer is provided in the filter tank, and a drainage component of the drainage device is arranged between the bottom of the filter tank and the filter layer.

[0015] In a preferred embodiment of the present invention, the filter layer includes a plurality of filter layers laid in the filter tank, and each of the filter layers contains a granular filter body.

[0016] In a preferred embodiment of the present invention, the particle size of the filter body gradually increases from top to bottom.

[0017] The technical solution of the utility model has the following significant beneficial effects:

[0018] When the drainage device of the utility model is used, the drainage device can be set in the filter tank, so that the drainage component is located between the bottom of the filter tank and the filter layer, so that the slag water in the blast furnace slag bottom filter tank is filtered by the filter layer and then enters the drainage component for discharge. In addition, when the blast furnace slag bottom filter tank is used for a long time, the drainage component can be used for backwashing, so as to clean the tiny glass fibers remaining in the filter layer, thereby reducing the compaction rate of the filter layer and playing a role in extending the service life of the filter layer.

[0019] Among them, multiple groups of drainage components are arranged in parallel in the filter tank, and multiple groups of drainage components can cover the filter tank more comprehensively, reduce or eliminate drainage or backwashing dead corners, and improve drainage and backwashing effects. In addition, by setting up multiple groups of drainage components, each drainage component can be repaired in groups, which is conducive to improving maintenance efficiency and the convenience of equipment replacement. In addition, by setting up multiple groups of drainage components, the length of the first drainage branch pipe can be reduced, thereby improving the water flow rate and pressure at the end of the first drainage branch pipe, ensuring that the fine glass fibers in the filter layer can be effectively cleaned during backwashing.

[0020] Furthermore, by utilizing the second connecting structure to connect the adjacent drainage main pipes, it is helpful to ensure the water pressure in the drainage main pipes during backwashing, thereby improving the backwashing effect. This is because: when the drainage main pipe is set separately, during the backwashing process, the backwashing water flow is continuously discharged along the drainage main pipe, causing the water pressure downstream of the drainage main pipe to continuously decrease, thereby affecting the backwashing effect. When the adjacent drainage main pipes are connected through the second connecting structure, an annular structure is formed between the adjacent drainage main pipes, and the water pressure in the annular structure can be kept consistent, thereby avoiding the pressure drop problem caused by the continuous outflow of water during backwashing. At the same time, multiple sets of drainage components effectively improve the convenience of maintenance and replacement of the drainage device. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0022] The drawings described herein are only for explanation purposes and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only for illustration purposes to help understand the present invention, and are not intended to specifically limit the shapes and proportional dimensions of the components of the present invention. Under the guidance of the present invention, those skilled in the art can select various possible shapes and proportional dimensions to implement the present invention according to specific circumstances.

[0023] Figure 1 It is a schematic diagram of the top view of an embodiment of the drainage device of the utility model;

[0024] Figure 2 It is a schematic diagram of the top structure of an embodiment of the drainage component of the utility model.

[0025] Reference numerals in the above drawings:

[0026] 10. Filter tank; 11. Drainage partition;

[0027] 100, drainage assembly; 110, drainage main pipe; 111, main pipe end plugging plate; 120, first drainage branch pipe; 121, branch pipe end plugging plate;

[0028] 200. Water outlet structure;

[0029] 300, first communication structure; 310, flange structure;

[0030] 400, second connecting structure; 410, second drainage branch pipe. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0032] Implementation Method 1

[0033] Please refer to Figure 1 and Figure 2In an embodiment of the utility model, a drainage device is provided, which is used to be arranged in a filter tank 10. The drainage device includes a plurality of drainage components 100 arranged in the filter tank 10, a water outlet structure 200 arranged on the filter tank 10, a first connecting structure 300 connecting the water outlet structure 200 and each drainage component 100, and a second connecting structure 400. The drainage component 100 includes a drainage main pipe 110 and a plurality of first drainage branch pipes 120. The plurality of first drainage branch pipes 120 are arranged at intervals and connected to the corresponding drainage main pipes 110. The drainage main pipes 110 are arranged at intervals, and adjacent drainage main pipes 110 are connected through the second connecting structure 400.

[0034] On the whole, when the drainage device is in use, the drainage device can be set in the filter tank 10, so that the drainage component 100 is located between the bottom of the filter tank 10 and the filter layer, so that the slag flushing water in the blast furnace slag bottom filter tank 10 is filtered through the filter layer and then enters the drainage component 100 for discharge.

[0035] Furthermore, after the blast furnace slag bottom filter 10 has been used for a long time, the drainage assembly 100 can be used for backwashing to clean the tiny glass fibers remaining in the filter layer, thereby reducing the compaction rate of the filter layer and extending the service life of the filter layer.

[0036] Among them, multiple groups of drainage components 100 are arranged in parallel in the filter tank 10, and multiple groups of drainage components 100 can more comprehensively cover the filter tank 10, reduce or eliminate drainage or backwashing dead corners, and improve drainage and backwashing effects. In addition, by setting multiple groups of drainage components 100, each drainage component 100 can be repaired in groups, which is conducive to improving maintenance efficiency and convenience of equipment replacement.

[0037] Furthermore, by providing multiple sets of drainage components 100, the length of the first drainage branch pipe 120 can be reduced, thereby improving the water flow rate and pressure at the end of the first drainage branch pipe 120, ensuring that the fine glass fibers in the filter layer can be effectively cleaned during backwashing.

[0038] Furthermore, by using the second connecting structure 400 to connect the adjacent drainage main pipes 110 , it is helpful to ensure the water pressure in the drainage main pipes 110 during backwashing, thereby improving the backwashing effect.

[0039] This is because: when the drainage pipe 110 is provided separately, during the backwashing process, the backwashing water flow is continuously discharged along the drainage pipe 110, resulting in a continuous decrease in the water pressure downstream of the drainage pipe 110, thereby affecting the backwashing effect. When adjacent drainage pipes 110 are connected through the second connecting structure 400, an annular structure is formed between the adjacent drainage pipes 110, and the water pressure in the annular structure can be kept consistent, thereby avoiding the pressure drop problem caused by the continuous outflow of water during backwashing.

[0040] In the implementation of the present utility model, the designer can adjust the specific number and arrangement of the first drainage branch pipes 120 according to the use requirements, and no specific limitation is made here. Preferably, the plurality of first drainage branch pipes 120 are evenly spaced and arranged along the corresponding drainage main pipe 110 .

[0041] The designer can adjust the specific shape of the filter tank 10 according to the use requirements, and no specific limitation is made here. Preferably, the filter tank 10 is set to be a rectangular parallelepiped.

[0042] In the implementation mode of the present utility model, Figure 1 and Figure 2 In the illustrated embodiment, the bottom of the filter tank 10 is divided into a plurality of relatively independent drainage partitions 11 along the width direction of the filter tank 10 , and each drainage partition 11 is provided with a drainage assembly 100 .

[0043] By dividing the filter tank 10 into a plurality of drainage partitions 11 and providing a drainage component 100 in each drainage partition 11, each drainage component 100 can more comprehensively cover the filter tank 10, reducing or eliminating drainage or backwashing dead corners, which is beneficial to improving subsequent drainage and backwashing effects.

[0044] The designer can adjust the number and size of the drainage partitions 11 according to the use requirements, and no specific restrictions are made here. For example, the drainage partitions 11 can be set to two, three, four or more. Preferably, there are three drainage partitions 11, and the three drainage partitions 11 can be set to be roughly the same size.

[0045] In the implementation mode of the present utility model, Figure 1 and Figure 2 In the illustrated embodiment, the water outlet structure 200 includes a water outlet disposed on the wall of the filter tank 10 , and the water outlet is connected to each drainage main pipe 110 through a first connecting structure 300 .

[0046] The water outlet is connected to each drainage main pipe 110 through the first communication structure 300, so that the water in each drainage main pipe 110 can be discharged along the water outlet, with good discharge efficiency.

[0047] When backwashing is required, the water outlet can be used as a water inlet for backwashing, and the backwashing water flows in the reverse direction along the water outlet into the drainage main pipe 110 for backwashing operation.

[0048] The designer can adjust the specific structure of the water outlet according to the use requirements, and no specific restrictions are made here. For example, a water outlet pipe is arranged on the pool wall of the filter tank 10, and the inner cavity of the water outlet pipe forms the water outlet.

[0049] In the implementation mode of the present utility model, Figure 1and Figure 2 In the illustrated embodiment, the first communication structure 300 includes a communication joint, on which a first port connected to the water outlet and a plurality of second ports connected to each of the drainage main pipes 110 are provided.

[0050] The water outlet and each drainage pipe 110 can be quickly connected through the connecting joint, which improves the installation efficiency. The designer can adjust the specific shape and structure of the connecting joint according to the number of drainage pipes 110, and no specific limitation is made here.

[0051] For example, when three main drainage pipes 110 are provided, the connecting joint is provided as a four-way joint to connect the water outlets with the main drainage pipes 110 respectively.

[0052] Furthermore, the drainage main pipe 110 is detachably connected to the corresponding second port. By making the drainage main pipe 110 detachably connected to the corresponding second port, the convenience of disassembly and assembly of the drainage main pipe 110 is improved, which is conducive to improving the subsequent maintenance efficiency. Among them, the port connection must ensure good sealing in a weakly alkaline environment to ensure that the drainage device does not release pressure during drainage and backwashing.

[0053] Preferably, the drainage main pipe 110 and the second port are detachably connected via a flange structure 310. In addition, in order to ensure the sealing between the drainage main pipe 110 and the second port, a sealing structure may be provided between the drainage main pipe 110 and the second port, which is not specifically limited here.

[0054] In an embodiment of the present utility model, the main drainage pipe 110 is disposed along the length direction of the filter tank 10 , and the plurality of first branch drainage pipes 120 are disposed along the width direction of the filter tank 10 and communicated with the corresponding main drainage pipes 110 .

[0055] By arranging the drainage main pipe 110 along the length direction of the filter tank 10 and arranging each first drainage branch pipe 120 along the width direction of the filter tank 10, the drainage main pipe 110 and each first drainage branch pipe 120 can cooperate to fully cover the drainage partition 11, avoiding drainage or backwashing dead corners, and improving the drainage and backwashing effects.

[0056] Of course, in other feasible embodiments, designers can adjust the arrangement of the main drainage pipe 110 and each first drainage branch pipe 120 according to usage requirements, and no specific limitation is made here.

[0057] In the embodiment of the present utility model, at least one flow hole is provided on the first drainage branch pipe 120 , and a branch pipe end plugging plate 121 is provided at the end of the first drainage branch pipe 120 away from the drainage main pipe 110 .

[0058] The end of the first drainage branch pipe 120 away from the drainage main pipe 110 can be sealed by the branch pipe end plugging plate 121, so that water can only enter and exit the first drainage branch pipe 120 along the flow hole.

[0059] The designer can adjust the specific structure, number and arrangement of the flow holes on the first drainage branch pipe 120 according to the use requirements, and no specific limitation is made here. Preferably, the flow holes are long holes arranged on the first drainage branch pipe 120.

[0060] Furthermore, a main pipe end plugging plate 111 is provided at one end of the drainage main pipe 110 away from the water outlet structure 200. The main pipe end plugging plate 111 can seal the end of the drainage main pipe 110 away from the water outlet structure 200, thereby preventing water from being discharged along the end of the drainage main pipe 110 away from the water outlet structure 200 and reducing the water pressure in the drainage main pipe 110.

[0061] Designers can adjust the shape and structure of the branch pipe end plugging plate 121 and the main pipe end plugging plate 111 according to usage requirements, and no specific restrictions are made here.

[0062] In an embodiment of the present invention, the second connecting structure 400 is disposed at one end of the drain assembly 100 away from the water outlet structure 200 , and the second connecting structure 400 includes at least one second drain branch pipe 410 connected to adjacent drain main pipes 110 .

[0063] By providing the second drainage branch pipe 410, the adjacent drainage main pipes 110 can be connected, so that an annular structure is formed between the adjacent drainage main pipes 110, which is conducive to ensuring the water pressure in the drainage main pipe 110 during backwashing and improving the backwashing effect. This is because: when the drainage main pipe 110 is provided separately, during the backwashing process, the backwashing water flow is continuously discharged along the drainage main pipe 110, which causes the water pressure downstream of the drainage main pipe 110 to continuously decrease, thereby affecting the backwashing effect. When the adjacent drainage main pipes 110 are connected through the second connecting structure 400, an annular structure is formed between the adjacent drainage main pipes 110, and the water pressure in the annular structure can be kept consistent, thereby avoiding the pressure drop problem caused by the continuous outflow of water during backwashing.

[0064] Designers can adjust the specific structure and number of the second drainage branch pipe 410 according to usage requirements, and no specific restrictions are made here.

[0065] Preferably, a plurality of second drainage branch pipes 410 are provided, and the plurality of second drainage branch pipes 410 are arranged at intervals and connected to adjacent drainage main pipes 110 , which is beneficial for improving the flow effect.

[0066] Implementation Method 2

[0067] Please refer to Figure 1As shown, a blast furnace slag bottom filter tank 10 is also provided in the embodiment of the utility model, and the blast furnace slag bottom filter tank 10 includes a filter tank 10 and the drainage device described in the first embodiment, a filter layer is provided in the filter tank 10, and the drainage component 100 of the drainage device is arranged between the bottom of the filter tank 10 and the filter layer.

[0068] The specific structure, working principle and beneficial effects of the drainage device are the same as those described in the first embodiment, and will not be described in detail here. The blast furnace slag bottom filter 10 can use the drainage assembly 100 to backwash the blast furnace slag bottom filter 10 after long-term use by using the drainage device in the first embodiment, thereby cleaning the tiny glass fibers remaining in the filter layer, reducing the compaction rate of the filter layer, and playing a role in extending the service life of the filter material.

[0069] In the embodiment of the present utility model, the filter layer includes a plurality of filter layers laid in the filter tank 10, and each filter layer contains a granular filter body.

[0070] The designer can adjust the number and specific composition of the filter layers according to the use requirements, and no specific restrictions are made here. For example, the filter body is a particle. Preferably, the filter body is a pebble particle.

[0071] In an embodiment of the present invention, the particle size of the filter body gradually increases from top to bottom.

[0072] Specifically, the filter bodies in the uppermost filter layer can be slag particles after granulation of blast furnace molten slag or stone particles with the same diameter as the slag particles. In addition, the diameter of the filter body gradually increases from top to bottom. This gradient configuration makes the filter body stable, and the small-diameter filter bodies in the upper layer will not be carried away by the filtered water, ensuring the filtering stability of the filter layer.

[0073] All articles and references disclosed, including patent applications and publications, are incorporated herein by reference for various purposes. The term "consisting essentially of ... " describing a combination should include determined elements, ingredients, parts or steps and other elements, ingredients, parts or steps that do not substantially affect the basic novel features of the combination. The use of the terms "comprising" or "including" to describe the combination of elements, ingredients, parts or steps here also contemplates the implementation method consisting essentially of these elements, ingredients, parts or steps. Here, by using the term "may", it is intended to illustrate that any attribute described that "may" includes is optional. Multiple elements, ingredients, parts or steps can be provided by a single integrated element, ingredient, part or step. Alternatively, a single integrated element, ingredient, part or step can be divided into separate multiple elements, ingredients, parts or steps. The disclosure "one" or "one" used to describe an element, ingredient, part or step is not said to exclude other elements, ingredients, parts or steps.

[0074] Each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. The above embodiments are only for illustrating the technical concept and features of the utility model, and their purpose is to enable people familiar with this technology to understand the content of the utility model and implement it accordingly, and cannot be used to limit the protection scope of the utility model. Any equivalent changes or modifications made according to the spirit of the utility model should be included in the protection scope of the utility model.

Claims

1. A drainage device, used in a filter tank, characterized in that: The invention comprises a plurality of drainage components arranged in the filter tank, a water outlet structure arranged on the filter tank, a first connecting structure connecting the water outlet structure with each of the drainage components, and a second connecting structure. The drainage components comprise a drainage main pipe and a plurality of first drainage branch pipes. The plurality of first drainage branch pipes are arranged at intervals and connected with the corresponding drainage main pipes. The drainage main pipes are arranged at intervals, and adjacent drainage main pipes are connected via the second connecting structure.

2. The drainage device according to claim 1, characterized in that: Along the width direction of the filter tank, the bottom of the filter tank is divided into a plurality of relatively independent drainage partitions, and each of the drainage partitions is provided with a drainage component.

3. The drainage device according to claim 2, characterized in that: The water outlet structure includes a water outlet arranged on the pool wall of the filter pool, and the water outlet is connected to each of the drainage main pipes through the first connecting structure.

4. The drainage device according to claim 3, characterized in that: The first communication structure includes a communication joint, and the communication joint is provided with a first port connected to the water outlet and a plurality of second ports connected to each of the drainage main pipes.

5. The drainage device according to claim 4, characterized in that: The drainage main pipe is detachably connected to the corresponding second port.

6. The drainage device according to claim 1, characterized in that: The main drainage pipe is arranged along the length direction of the filter tank, and the plurality of first drainage branch pipes are arranged along the width direction of the filter tank and are connected with the corresponding main drainage pipes.

7. The drainage device according to claim 1, characterized in that: The first drainage branch pipe is provided with at least one flow hole, and the end of the first drainage branch pipe away from the drainage main pipe is provided with a branch pipe end plugging plate.

8. The drainage device according to claim 1, characterized in that: A main pipe end plugging plate is provided at one end of the drainage main pipe away from the water outlet structure.

9. The drainage device according to claim 1, characterized in that: The second communication structure is arranged at one end of the drainage component away from the water outlet structure, and the second communication structure includes at least one second drainage branch pipe connected with the adjacent drainage main pipes.

10. A blast furnace slag bottom filter, characterized in that: It comprises a filter tank and a drainage device as claimed in any one of claims 1 to 9, wherein a filter layer is provided in the filter tank, and a drainage component of the drainage device is arranged between the bottom of the filter tank and the filter layer.

11. The blast furnace slag bottom filter tank according to claim 10, characterized in that: The filter layer comprises a plurality of filter layers laid in the filter tank, and each of the filter layers contains a granular filter body.

12. The blast furnace slag bottom filter tank according to claim 11, characterized in that: From top to bottom, the particle size of the filter body gradually increases.

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