Automatic cleaning mechanism for iron core plastic spiral twisted belt

文档序号:1336011 发布日期:2020-07-17 浏览:34次 中文

阅读说明:本技术 一种铁芯塑料螺旋扭带自动清洗机构 (Automatic cleaning mechanism for iron core plastic spiral twisted belt ) 是由 俞天翔 俞天兰 彭雪松 金俊杰 彭德其 俞秀民 冯修燕 张治坤 吴金香 于 2020-04-05 设计创作,主要内容包括:一种铁芯塑料螺旋扭带自动清洗机构,有中孔塑料螺旋扭带、塑料轴承、钢丝钩头轴组成。主要适用于中低流速的卧式换热器管内硬垢的自动清洗和对流传热强化。显著特点是中孔塑料螺旋纽带的横截面积比较大,使换热管内的流速有较大幅度的增大;制造中孔塑料螺旋纽带的塑料选用硬度显著大于被清洗的硬垢,并且密度尽可能大的添加剂,而且在塑料包芯管内填装铁芯加重,生产运行时螺旋片对硬垢有比较大的自重压力。这种自动清洗机构结构简单,制造成本较低,硬垢自动清洗效果好,对流传热强化,能够成倍提高该侧的传热系数。(An automatic cleaning mechanism for the plastic spiral twisted band of iron core is composed of central hole plastic spiral twisted band, plastic bearing and steel wire hook. The device is mainly suitable for automatic cleaning and convection heat transfer enhancement of hard scale in the horizontal heat exchanger tube with medium and low flow velocity. The heat exchange tube is characterized in that the cross-sectional area of the middle-hole plastic spiral band is larger, so that the flow velocity in the heat exchange tube is greatly increased; the plastic used for making the middle-hole plastic spiral band is made of additive whose hardness is obviously greater than that of the hard scale to be cleaned and whose density is as high as possible, and the core tube is filled with iron core to increase weight, so that the spiral sheet has relatively high dead weight pressure to the hard scale during production. The automatic cleaning mechanism has the advantages of simple structure, lower manufacturing cost, good automatic cleaning effect of hard scale, enhanced convection heat transfer and capability of improving the heat transfer coefficient of the side by times.)

1. The utility model provides an iron core plastics spiral twisted strip self-cleaning mechanism, mainly has mesopore plastics spiral twisted strip (3), plastic bearing (1), steel wire gib head axle (2) to constitute characterized by: the device is mainly suitable for automatic cleaning and convection heat transfer enhancement of hard scale in the horizontal heat exchanger tube with medium and low flow velocity; the middle-hole plastic spiral twisted belt (3) is hung on a plastic bearing (1) through a steel wire hook head shaft (2), and the plastic bearing (1) is fixedly arranged at the inlet end of the heat exchange pipe (6); the middle-hole plastic spiral band (3) consists of a plastic spiral sheet (7), an iron core (4), a plastic core-wrapping pipe (5), a locking steel wire (9) and a locking hole (8); the plastic spiral piece (7) is a structural component for directly scraping and washing hard scales, the thickness is 0.8-3 mm, the size of a gap between the plastic spiral piece and the inner wall of the heat exchange tube (6) is 2-8 mm, and the thickness and the gap are larger as the inner diameter of the heat exchange tube (6) is larger; the pitch is 2-6 times of the inner diameter of the heat exchange tube (6), and the larger the inner diameter of the heat exchange tube (6), the smaller the value of the multiple; the outer diameter of the plastic core-wrapping tube (5) is determined according to the increase of the flow rate of the hollow tube without the mesoporous plastic spiral band (3), and then the cross-sectional area of the mesoporous plastic spiral band (3) is calculated; the wall thickness of the plastic core-wrapped pipe (5) is 0.8-2.0 mm; a filling gap of more than 1.0mm is required between the plastic core-wrapped tube (5) and the thickest iron core (4) designed to be filled; the middle-hole plastic spiral tie (3) is made of corrosion-resistant, temperature-resistant and wear-resistant plastic, and has two special requirements on the selection of plastic additives, wherein the first requirement is that the hardness is obviously higher than the hard scale to be cleaned, and the second requirement is that the density is as large as possible, so that the cleaning pressure of the self weight of the middle-hole plastic spiral tie (3) on the hard scale is increased; the iron core (4) has the function of increasing the pressure required by the plastic spiral sheet (7) to rotate the scraped hard scale and improving the cleaning strength of the hard scale, the iron core (4) generally adopts a segmented iron wire (12) structure, the outer diameter of the segmented iron wire (12) is selected according to the strength requirement of automatic cleaning of the hard scale in the heat exchange tube (6), the length of the segmented iron wire (12) is 100-1000 mm, and the principle is that the larger the diameter of the segmented iron wire (12) is, the shorter the length value is; the locking steel wire (9) has the function of preventing the mutual serial position of the iron core (4) in the plastic core-wrapping pipe (5); the hook head shaft (2) is made of stainless steel wires with the diameter of 1.5-3.0 mm.

2. The automatic cleaning mechanism for iron core plastic spiral twisted belt of claim 1, characterized by: the wear allowance height H1 of the plastic bearing (1) is designed once by replacing in 2-3 years, and the area of the inflow window (11) of the plastic bearing (1) is required to be significantly larger than the flow area in the heat exchange tube (6).

Technical Field

The invention relates to an automatic cleaning mechanism for an iron core plastic spiral twisted belt in a heat exchange tube. It is mainly suitable for automatic cleaning and convection heat transfer enhancement of hard scale in the pipe of a horizontal heat exchanger (such as a heat exchanger, a condenser, a variable temperature crystallization heat exchanger and the like) with medium and low flow velocity. For example, organic product condensers with heat transfer coefficients not too high outside pipes in the petrochemical industry and the organic synthesis industry, temperature-changing crystallization process heat exchangers with crystallization speeds not too high, and water coolers with calcium-magnesium hard scales inside pipes for high-temperature cooling outside pipes. The invention can also be applied to the conveying pipeline which can be subjected to hard scale formation in long-term operation.

Background

The high-efficiency heat transfer equipment of the autorotation plastic twisted belt (Chinese patent Z L95110822.8) is characterized in that the heat transfer and flow characteristics in a pipe with a built-in special-shaped equidistant twisted belt (thermal power engineering, 2017,32(2):11-16) are compared, the research and application of the spiral belt device in a condenser of a 300MW unit (Shenyang institute of engineering science (Nature science edition), 2015,11(3):236 and 240) are reported to have good effects in the automatic cleaning application of soft scale of a plurality of horizontal water cooling equipment, and the plastic twisted belt is found to be essentially ineffective in cleaning calcium-magnesium hard scale and concentrated crystallized or evaporated salt hard scale formed in a water cooler with higher temperature.

In addition, the plastic spiral band in the prior art has high requirement on the flow velocity in the heat exchange tube, generally needs more than 1.0m/s, and many process heat exchangers which can crystallize and salt out cannot meet the high flow velocity requirement, for example, preheaters in front of evaporators are generally difficult to achieve, so the engineering application range is greatly influenced.

Disclosure of Invention

The invention mainly aims at two problems that the plastic spiral twisted belt in the prior art has no automatic hard scale cleaning capability and has higher flow speed requirement, and provides an automatic cleaning mechanism for the iron core plastic spiral twisted belt, wherein the self weight of an iron core filled in a plastic core-wrapped pipe is utilized, so that a plastic spiral sheet which is automatically cleaned obtains the pressure required by cleaning the hard scale in the pipe, and the automatic hard scale cleaning capability is greatly enhanced; meanwhile, the cross section of the plastic core-wrapped pipe is utilized to reduce the actual flow area in the heat exchange pipe, so that the flow velocity of liquid can be greatly increased, the convection heat transfer can be obviously enhanced, the dynamic moment of automatic cleaning can be effectively increased, and the flow velocity requirement in the heat exchange pipe is reduced. The automatic cleaning mechanism for the iron core spiral twisted belt can well keep the advantages of simple structure and low manufacturing cost of the existing automatic cleaning technology for the autorotation plastic twisted belt, and also expand the new market of automatic cleaning of hard scale in the heat exchange tube with medium and low flow velocity.

The purpose of the invention is realized by the following technical scheme:

an automatic cleaning mechanism for an iron core plastic spiral twisted belt mainly aims at automatic cleaning and convection heat transfer enhancement of hard scale in a horizontal heat exchanger pipe with medium and low flow velocity. The automatic cleaning mechanism for the iron core plastic spiral twisted belt mainly comprises a middle-hole plastic spiral twisted belt, a plastic bearing and a steel wire hook head shaft. The middle-hole plastic spiral twisted belt is hung on a plastic bearing through a steel wire hook head shaft, and the plastic bearing is fixedly arranged at the inlet end of the heat exchange tube.

The automatic cleaning mechanism for the iron core plastic spiral twisted belt can also be applied to automatic cleaning and anti-blocking of a conveying pipeline. The difference is that the plastic bearing is generally installed and fixed at the turning part of the conveying pipeline.

The middle hole plastic spiral band is composed of a plastic spiral sheet, an iron core, a plastic core-wrapping tube, a locking steel wire and a locking hole.

The plastic spiral blade is a structural component for directly scraping and washing hard dirt. The thickness of the plastic spiral sheet is 0.8-3 mm, the higher the strength requirement of automatically cleaning hard scale is, and the larger the thickness value is; the larger the inner diameter of the heat exchange tube is, the larger the value of the thickness is. The size of a gap between the plastic spiral sheet and the inner wall of the heat exchange tube is 2-8 mm, and the value of the gap is consistent with the size of the inner diameter of the heat exchange tube and the length of the heat exchange tube; the pitch of the plastic spiral sheet is 2-6 times of the inner diameter of the heat exchange tube, and the larger the inner diameter of the heat exchange tube is, the smaller the value of the multiple is.

The outer diameter of the plastic core-wrapping tube is calculated according to the required increase amplitude of the flow rate of the hollow tube without the middle-hole plastic spiral band, and then the required sectional area of the middle-hole plastic spiral band is calculated. The wall thickness of the plastic core-wrapping pipe is 0.8-2.0 mm, the larger the inner diameter of the heat exchange pipe is, the longer the length of a single plastic spiral band is, and the larger the thickness value is. The inner diameter of the plastic core-spun pipe is determined by the maximum diameter of the iron core to be filled. A filling gap of more than 1.0mm is required between the plastic core-wrapped tube and the thickest iron core.

The middle-hole plastic spiral tie is made of corrosion-resistant, temperature-resistant and wear-resistant plastics, and has two special requirements on the selection of plastic additives, wherein the first requirement is that the hardness is obviously higher than the hard scale to be cleaned, and the second requirement is that the density is as large as possible, so that the cleaning pressure of the self weight of the middle-hole plastic spiral tie on the hard scale is increased.

The iron core has the functions of increasing the pressure of the plastic spiral sheet on the hard scale for rotary scraping and cleaning the hard scale and improving the cleaning strength of the hard scale. The core is typically constructed of segmented wire, but may also be heavy, such as metal balls. The inner diameter of the plastic core tube is determined by the thickest sectional wire which is allowed to be filled, so that the sectional wires corresponding to different hard scale cleaning dead weight pressures are selected to be filled. The series of diameters of the sectional iron wire is commonly 1.5 mm, 1.8 mm, 2.0mm, 2.5 mm, 3.0mm and 3.5mm, and the corresponding dead weight pressures are respectively 0.11 mm, 0.20 mm, 0.32 mm, 0.46 mm and 0.63 mm (N/m). The diameter of the sectional iron wire is selected by the method that the higher the requirement on the automatic cleaning strength of the hard scale is, the larger the required value of dead weight pressure (effective after deducting the buoyancy of the solution) is. The illustrated design reference test curves were obtained under such heavily fouled test conditions: when the heat exchange tube is not automatically cleaned by using the middle-hole plastic spiral band, the growth speed of the cooling crystallization salt scale from salt scale-free is 3.5mm per hour. Therefore, the effective dead-weight pressure of the plastic helical torsion strip of the iron core is generally selected as follows: calcium magnesium scale is about 0.15(N/m), circulating evaporation concentration crystallization salt scale is about 0.28(N/m), and cooling or heating crystallization salt scale is about 0.45 (N/m). The length of the segmented iron wire is 100-1000 mm, and the length of the segmented iron wire is shorter as the diameter of the segmented iron wire is larger, so that the flexibility of the middle-hole plastic spiral twisted belt is prevented from being influenced, and the strength and uniformity of automatic cleaning are guaranteed.

The function of locking the steel wire is to prevent mutual serial position of the iron core in the plastic core-spun tube, keep the uniformity of axial arrangement and prevent the iron core from running out from the tail end of the plastic spiral tie in the middle hole.

The wear allowance height H1 of the plastic bearing is designed to be replaced once according to 2-3 years of operation. The area of the inflow window of the plastic bearing must be significantly larger than the flow area inside the heat exchanger tube. The hook head shaft is made of stainless steel wires with the diameter of 1.5-3.0 mm.

An automatic cleaning mechanism for the plastic spiral twisted band of iron core is installed in horizontal tubular heat exchanger, and features that the central hole plastic spiral band occupies part of the cross-section area of heat exchange tube, resulting in greatly increased flow speed in heat exchange tube, increased liquid flow to drive the plastic spiral plate and increased self-rotation torque of central hole plastic spiral band. Therefore, the requirement of the rotation on the nominal flow velocity of the empty pipe can be greatly reduced. Under the self-weight pressurization of the iron core, the plastic spiral sheet can effectively scrape and wash hard scales on the inner wall of the heat exchange tube. When the heat exchange tube is automatically cleaned, the convection heat transfer process is more effectively enhanced due to the increase of the liquid flow speed in the heat exchange tube and the disturbance of the plastic spiral sheet.

Drawings

Fig. 1 is a scheme diagram of an automatic cleaning mechanism for an iron core plastic spiral twisted belt.

Fig. 2 is an enlarged view of a portion of fig. 1A.

Fig. 3 is an enlarged view of a portion B of fig. 1.

FIG. 4 is a test curve of the change of the total heat transfer coefficient caused by the cleaning effect of the hard scale of the plastic spiral sheet influenced by the effective weight pressure of the iron core

Detailed Description

The present invention will be described in further detail with reference to fig. 1, 2 and 3.

In the figure, 1a plastic bearing 2, a steel wire hook shaft 3, a middle hole plastic spiral tie 4, an iron core 5, a plastic core-wrapping tube 6, a heat exchange tube 7, a plastic spiral sheet 8, a locking hole 9, a locking steel wire 10, a tube plate 11, an inflow window 12 and a sectional iron wire are arranged in a heat exchange tube 7, a plastic spiral sheet 8, a locking steel wire 10

An automatic cleaning mechanism for an iron core plastic spiral twisted belt mainly aims at automatic cleaning and convection heat transfer enhancement of hard scale in a horizontal heat exchanger pipe with medium and low flow velocity. An automatic cleaning mechanism for a plastic spiral twisted belt of an iron core mainly comprises a middle-hole plastic spiral twisted belt 3, a plastic bearing 1 and a steel wire hook head shaft 2. The middle-hole plastic spiral twisted belt 3 is hung on the plastic bearing 1 through the steel wire hook head shaft 2, and the plastic bearing 1 is fixedly arranged at the inlet end of the heat exchange tube 6.

The automatic cleaning mechanism for the iron core plastic spiral twisted belt can also be applied to automatic cleaning and anti-blocking of a conveying pipeline. The difference is that the plastic bearing is generally installed and fixed at the turning part of the conveying pipeline.

The middle-hole plastic spiral band 3 consists of a plastic spiral sheet 7, an iron core 4, a plastic core-wrapping tube 5, a locking steel wire 9 and a locking hole 8.

The plastic spiral blade 7 is a structural component for directly scraping and washing hard dirt. The thickness of the plastic spiral sheet 7 is 0.8-3 mm, the higher the strength requirement of automatically cleaning hard scale is, and the larger the thickness value is; the larger the inner diameter of the heat exchange tube 6 is, the larger the thickness value is. The size of a gap between the plastic spiral sheet 3 and the inner wall of the heat exchange tube 6 is 2-8 mm, and the value is in consistent relation with the size of the inner diameter of the heat exchange tube 6 and the length of the heat exchange tube 6; the pitch of the plastic spiral sheet 7 is 2-6 times of the inner diameter of the heat exchange tube 6, and the larger the inner diameter of the heat exchange tube 6 is, the smaller the value of the multiple is.

The outer diameter of the plastic core-wrapping tube 5 is calculated according to the increase of the flow rate of the hollow tube without the mesoporous plastic spiral tie 3, and then the sectional area of the mesoporous plastic spiral tie 3 is calculated. The wall thickness of the plastic core-wrapping pipe 5 is 0.8-2.0 mm, the larger the inner diameter of the heat exchange pipe 6 is, the longer the length of the single middle-hole plastic spiral band 3 is, and the larger the thickness value is. The inside diameter of the plastic core-tube 5 is determined by the maximum diameter of the core 4 that is designed to be filled. A filling gap of more than 1.0mm is required between the plastic core-wrapped tube 5 and the thickest iron core 4.

The middle-hole plastic spiral tie 3 is made of corrosion-resistant, temperature-resistant and wear-resistant plastics, and has two special requirements on the selection of plastic additives, wherein the first requirement is that the hardness is obviously higher than the hard scale to be cleaned, and the second requirement is that the density is as large as possible, so that the cleaning pressure of the dead weight of the middle-hole plastic spiral tie 3 on the hard scale is increased.

The function of the iron core 4 is to increase the pressure of the plastic spiral sheet 7 required for rotating the scraped hard scale and improve the cleaning strength of the hard scale. The iron core 4 is generally of a segmented iron wire 12 structure. The inside diameter of the plastic core tube 5 allows for the filling of different thicknesses of the segmented wire 12 for the selective filling of different scale cleaning deadweight pressures requiring the corresponding segmented wire 12. The series of diameters of the segmented iron wire 12 are commonly 1.5, 1.8, 2.0, 2.5, 3.0 and 3.5mm, and the corresponding dead weight pressures are respectively 0.11, 0.20, 0.32, 0.46 and 0.63 (N/m). The diameter of the sectional iron wire 12 is selected by the method that the requirement of the automatic cleaning strength of the hard scale is higher, the effective value of the dead weight pressure (after the solution buoyancy is deducted) is larger, and the test condition of the design reference curve shown in the figure is that when the heat exchange tube 6 is not automatically cleaned by using the mesoporous plastic spiral band 3, the growth speed of the cooling crystallization salt scale from the salt scale-free state is 3.5mm per hour. Thus, the effective deadweight pressure of the core plastic helical torsion strip 3 is typically selected as: calcium magnesium scale is about 0.15(N/m), circulating evaporation concentration crystallization salt scale is about 0.28(N/m), and cooling or heating crystallization salt scale is about 0.45 (N/m). The length of the iron core 4 is 100-1000 mm, and the value principle is that the larger the diameter of the iron core 4 is, the shorter the length of the iron core 4 is, so that the flexibility of the mesoporous plastic spiral twisted belt 3 is prevented from being influenced, and the strength and uniformity of automatic cleaning are guaranteed.

The locking steel wire 9 has the functions of preventing the mutual serial position of the iron core 4 in the plastic core-wrapping pipe 5, keeping the uniformity of axial arrangement and preventing the iron core 4 from running out of the tail end of the middle-hole plastic spiral band 3.

The wear allowance height H1 of the plastic bearing 1 is designed to be replaced once in 2-3 years. The area of the inflow window 11 of the plastic bearing 1 must be significantly larger than the flow area inside the heat exchanger tube 6.

The hook head shaft 2 is made of stainless steel wires with the diameter of 1.5-3.0 mm.

An automatic cleaning mechanism for a plastic spiral twisted strip of an iron core is arranged in a horizontal tubular heat exchanger. During production and operation, the mesoporous plastic spiral band 3 occupies a part of the flow cross section in the heat exchange tube 6, so that the flow velocity in the heat exchange tube 6 is greatly increased, the accelerated liquid flow rushes the plastic spiral sheet 7, the self-rotation torque of the mesoporous plastic spiral band 3 is increased, and the requirement of self-rotation cleaning on the nominal flow velocity is reduced. Under the self-weight pressurization of the proper iron core 4, the plastic spiral sheet 7 can effectively scrape and wash hard scale on the inner wall of the heat exchange tube 6. And when the heat exchange pipe is automatically cleaned, the convection heat transfer process is more effectively enhanced due to the acceleration of the liquid flow speed in the heat exchange pipe 6 and the disturbance of the plastic spiral sheet 7.

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