CN116407856A - A three-dimensional moving spiral automatic cleaning falling film evaporator - Google Patents

Abstract

The automatic cleaning spiral falling film evaporator with three-dimensional motion has the advantages that a hook head shaft section of the automatic cleaning spiral in a heating pipe is directly hung on an end surface track of the three-dimensional motion machine, and the automatic cleaning spiral can stably ascend and descend along the end surface track under the action of the actual high-speed falling film flow impulse, so that the rotation moment is large, and the upward and downward reciprocating motion is realized; meanwhile, hundreds of random radial vibration in each minute occurs, and slow rotation under 100 rotations per minute controlled by rising is avoided, so that the possibility of abrasion between the self-cleaning screw and the inner wall of the heating pipe is completely eradicated. The structural design of the three-dimensional motion body tube can ensure that the feed liquid flowing into each heating tube is quite uniform. The combined action of the three functions of automatic cleaning and scale prevention of an automatic cleaning screw, convection heat transfer enhancement and circumferential film distribution of a full tube side is ideal, and the long-term stable continuous and efficient production of the falling film evaporator is realized.

Description

A three-dimensional moving spiral automatic cleaning falling film evaporator

technical field

The invention relates to a three-dimensional moving spiral automatic cleaning falling film evaporator, which mainly relates to the automatic cleaning and heat transfer enhancement of the dirt in the tubes of the tube falling film evaporator and heat exchanger.

Background technique

Existing evaporators face the problem of fouling in the heating pipes, most of which do not have automatic cleaning technology, and almost all of them adopt the method of periodic parking and cleaning. The cycle average heat transfer coefficient is generally only 1/3-2/3 of the time without scale, and both capacity loss and energy loss are very large.

For the evaporation of this easy-to-scaling solution, the forced circulation evaporator is a more widely used option, but the price paid is too high. For example, a domestic MVR heat pump tube evaporator for high-salt wastewater, a 220KW heat pump, needs to be equipped with a 110KW forced circulation pump to make the average flow rate in the heating tube as high as 1.8m/s, and use its suspended salt crystals to achieve fluidized flushing To produce, delay fouling and prolong production operation time, not only greatly reduce the energy saving efficiency of the heat pump evaporation device, but also the heat transfer coefficient is still very low, only 350 (w/m ² .℃), and it needs to be stopped every two weeks for cleaning once.

Falling film automatic cleaning technology patents published in recent years, for example, ZL201110038777.3, an in-tube automatic cleaning anti-scaling falling film evaporator; ZL201711042017.3, wave flow valve automatic cleaning vertical pipe falling film evaporator. In addition to the automatic cleaning screw, it also needs a membrane distributor, a reciprocating power spring, and a frame for installing a fixed power spring. The height of the upper tube box is required to be high, and the installation technical requirements are relatively high. The overall structure is too complicated, which is not conducive to the high reliability required by the project. .

Contents of the invention

A three-dimensional moving spiral automatic cleaning falling film evaporator proposed by the present invention greatly simplifies the overall scheme of its automatic cleaning mechanism through the ingenious structural design of the three-dimensional moving machine, improves reliability, facilitates installation, and well retains the existing It has the technical advantages of three-dimensional motion automatic cleaning function, full tube swirl film distribution and enhanced convective heat transfer in the heat exchange tube.

Technical scheme of the present invention is:

A three-dimensional moving spiral automatic cleaning falling film evaporator, the main components include an upper tube box, a three-dimensional moving machine, a heating chamber, a heating pipe, an automatic cleaning spiral, a separation chamber, and a circulating pump.

An automatic cleaning spiral is arranged in the heating tube. The linear shaft section on the upper part of the automatic cleaning screw passes through the shaft hole of the three-dimensional kinematic machine, and the hook head shaft section is suspended on the end track of the three-dimensional kinematic machine.

The three-dimensional motion machine has a three-dimensional motion body tube, an end track, a bearing hub, a shaft hole, a balance hole, a cross holder, and a helical tooth. The three-dimensional motion fuselage tube is fixedly installed on the inlet section of the heating tube by means of a cross bracket and a helical tooth. The width dimension B of the cross holder is required to be more than 1 mm larger than the center distance between the heating tubes, and the cross holders of adjacent heating tubes are bound to be locked when they rotate, so that the possibility of rotation can be avoided very reliably.

The tooth height of the helical teeth is 2-6mm. The design principle is that the greater the design flow velocity in the heating tube, the greater the value. The number of teeth of the helical teeth is 2 to 4, and the larger the inner diameter of the heating tube is, the more the number of helical teeth is designed. The tooth top circle of the helical tooth and the inner wall of the heating tube are fixed by an interference fit less than 0.15mm. The range of the helix angle γ of the helical teeth is 20° to 35°, the larger the inner diameter of the heating tube, the smaller the value of the helix angle γ.

The axial height change of the end track is that the slope angle α increases and the slope angle β decreases. The rising section of the end track generally takes a larger half of the circle, and usually takes 200-280°, the purpose is to strive for a relatively large up and down reciprocating stroke. The greater the self-rotation moment of the self-cleaning screw, the greater the slope angle α of the end track design of the ascending section.

The diameter of the shaft hole is 2-3 mm, which is 0.05-0.20 mm larger than the outer diameter of the steel wire used to manufacture the self-cleaning spiral. The thickness of the bearing hub is 2-4mm.

加热管内径愈大，平衡孔直径取值也愈大。平衡孔距离加热管管口的高度H₂，要求比平稳运行操作的积液层H₁深度大30mm以上。The function of the balance hole is to maintain a basic balance between the secondary steam in the heating tube and the steam pressure in the upper tube box, so as to ensure that the liquid in the accumulation layer can pass through the flow channel between the spiral teeth stably and smoothly, and there is still a certain speed to flow to the Heating the inner wall of the tube to form a uniform film. Balance hole diameter

The larger the inner diameter of the heating tube, the larger the value of the balance hole diameter. The height H ₂ of the balance hole from the nozzle of the heating tube is required to be more than 30mm greater than the depth of the effusion layer H ₁ for smooth operation.

The depth of effusion layer _H1 for smooth running operation ranges from 50 to 100mm. The design principle is mainly to consider that the larger the heating temperature difference of the evaporator, the larger the value; the second is that the larger the diameter of the upper tube box and the larger the design flow rate, the larger the value also needs to be.

The self-cleaning spiral is made of stainless steel wire with a diameter of 1.5-2.2mm. The gap between the outer diameter of the self-cleaning spiral and the inner wall of the heating tube is 3-7mm. The larger the diameter of the heating tube and the larger the design flow rate, the larger the value. The pitch of the self-cleaning spiral is (1.3-1.9) times the inner diameter of the heating tube. The design values of the diameter and pitch of the stainless steel wire are based on the inner diameter and flow velocity of the heating tube, and are consistent with the inner diameter and flow velocity of the heating tube. The length of the self-cleaning spiral is 100-400mm shorter than the heating tube.

When the evaporator is running, the circulating feed liquid enters the upper tube box from the liquid inlet pipe, and then enters the liquid accumulation layer of the upper tube box evenly through the uniformly distributed ring gear 360°. Use the 50-100mm effusion layer at the depth _H1 to ensure that the flow rate flowing into each heating tube is basically uniform. As for the actual flow velocity of the falling film flow in the heating tube, the actual measurement results of the simulated test repeated over a hundred times all consistently show that it is as high as 1.3-2.2m/s. Under the impact of such a high-velocity liquid film, the automatic cleaning screw not only generates hundreds of radial random vibrations per minute, knocking the dirt on the inner wall of the heating tube to realize automatic cleaning; but also the automatic cleaning screw guides the falling film flow The effect makes the liquid film on the inner wall of the whole heating tube change into a helical flow, which not only produces convective heat transfer enhancement, but more importantly, it can effectively ensure a strong circumferential uniform film distribution function from top to bottom , from the new mechanism to avoid local dry wall and rapid scaling.

While the self-cleaning screw transforms the liquid film into a helical flow, according to Newton's third law, the self-cleaning screw also obtains the rotation dynamic torque provided by the reaction of the liquid film. When the self-cleaning screw rotates, under the interaction between the hook head shaft of the top section of the self-cleaning screw and the end track, it continuously rises and falls along the end track, reciprocating. Due to the self-rotation and up-and-down reciprocating motion of the self-cleaning screw, the self-cleaning and anti-scaling ability of the self-cleaning screw is enhanced, and the uniformity of vibrating and knocking cleaning on the inner wall of the heating tube is greatly improved.

Based on the combined effect of the three functions of automatic cleaning and anti-scaling of the automatic cleaning spiral, enhanced convective heat transfer, and circumferential film distribution throughout the tube, it is ideal to achieve the goal of long-term stable continuous high-efficiency production of the falling film evaporator.

Due to the effective deceleration effect of the self-cleaning screw when it rises along the end track, its speed is successfully controlled to no more than 120 revolutions per minute, eliminating the possibility of abrasion between the self-cleaning screw and the inner wall of the heating tube, which is very good Meet the high reliability requirements of the project.

Description of drawings

Fig. 1 is the general diagram of a kind of three-dimensional motion spiral self-cleaning type falling film evaporator of the present invention

Figure 2 is a cross-sectional view of the three-dimensional exercise machine

Figure 3 is a front view of the three-dimensional exercise machine

Figure 4 is a 360° development view of the circumference of the end track height

Detailed ways

01 top view mirror 02 upper tube box 03 liquid level gauge tube 04 evenly distributed gear ring 05 tube plate 06 three-dimensional motion machine 07 heating chamber 08 automatic cleaning screw 09 heating steam inlet distribution chamber 10 heating pipe 11 condensate water pipe 12 secondary Steam outlet pipe 13 Vapor-liquid separation chamber 14 Circulation pump 15 Feeding pipe 16 Non-condensable gas discharge pipe 17 Feed pipe 18 Effusion layer 19 Hook head shaft section 20 End surface rail 21 Bearing hub 22 Shaft hole 23 Balance hole 24 Three-dimensional motion body Pipe 25 cross fixing frame 26 linear shaft section 27 helical teeth

A three-dimensional moving spiral automatic cleaning falling film evaporator, the main components are the upper tube box 02, the three-dimensional moving machine 06, the heating chamber 07, the heating pipe 10, the automatic cleaning screw 08, the vapor-liquid separation chamber 13, and the circulating pump 14.

An automatic cleaning screw 08 is arranged in the heating tube 10 . The linear shaft section 26 on the top of the automatic cleaning screw 08 passes through the shaft hole 22 of the three-dimensional kinematic machine 06, and the hook head shaft section 19 is suspended on the end track 20 of the three-dimensional kinematic machine 06.

Three-dimensional motion machine 06 has three-dimensional motion fuselage pipe 24, end track 20, bearing hub 21, axle hole 22, balance hole 23, cross holder 25, helical tooth 27. The three-dimensional motion fuselage pipe 24 is fixedly installed on the inlet section of the heating pipe 07 by means of a cross holder 25 and a helical tooth 27 . The width dimension B of the cross holder 25 is required to be more than 1mm larger than the center distance between the heating tubes 07, and the cross holders of the adjacent heating pipes 07 are bound to each other when they rotate, so that the possibility of rotation can be avoided very reliably.

The tooth height of the helical teeth 27 is 2-6 mm, and the design principle is that the greater the design flow velocity in the heating tube 07 is, the greater the value will be. The number of teeth of the helical teeth 27 is 2-4, the larger the inner diameter of the heating tube 07 is, the more the number of teeth of the designed helical teeth 27 is. The addendum garden of the helical tooth 27 and the inner wall of the heating tube 07 are fixed by an interference fit less than 0.15mm. The value range of the helix angle γ of the helical teeth 27 is 20°-35°, and the larger the inner diameter of the heating tube 27 is, the smaller the design value of the helix angle γ is.

The axial height change of the end rail 20 is that the slope angle α increases and the slope angle β decreases. The ascending section of the end track 20 generally takes a larger half circle, and usually takes 200-280°, and the purpose is to strive to have a relatively large stroke of reciprocating motion up and down. The bigger the self-rotating moment of the self-cleaning screw 08 is, the bigger the slope angle α of the end track 20 of the ascending section is.

The shaft hole 22 has a diameter of 2-3 mm, which is 0.05-0.20 mm larger than the steel wire outer diameter of the automatic cleaning screw 08. The thickness of the bearing hub 21 is 2-4mm.

加热管10内径愈大，平衡孔22直径取值也愈大。平衡孔22距离加热管10管口的高度H₂，要求比平稳运行操作的积液层18的深度H₁大30mm以上。The role of the balance hole 22 is to keep the secondary steam in the heating tube 10 and the steam pressure in the upper tube box 02 in a basic balance, so as to ensure that the liquid in the accumulation layer 18 passes through the flow channel between the spiral teeth 27 stably and smoothly, and has A certain speed flows to the inner wall of the heating tube 10 to form a uniform film. Balance hole 22 diameter

The larger the inner diameter of the heating tube 10 is, the larger the diameter of the balance hole 22 is. The height H ₂ of the balance hole 22 from the nozzle of the heating tube 10 is required to be greater than the depth H ₁ of the liquid accumulation layer 18 for smooth operation by more than 30 mm.

The depth H ₁ of the effusion layer 18 for smooth operation is in the range of 50-100 mm. The design principle is mainly to consider that the larger the heating temperature difference of the evaporator, the larger the value; the second is that the larger the diameter of the upper tube box 02 and the larger the design flow rate, the larger the value also needs to be.

The automatic cleaning spiral 08 is made of stainless steel wire with a diameter of 1.5-2.2mm. The gap between the outer diameter of the self-cleaning screw 08 and the inner wall of the heating tube 10 is 3-7mm, the larger the diameter of the heating tube 10, the larger the design flow rate, and the larger the value. The pitch of the self-cleaning spiral 08 is (1.3-1.9) times of the inner diameter of the heating tube 10 . The design value of the diameter and pitch of the stainless steel wire is based on the inner diameter and flow velocity of the heating tube 10 , and is consistent with the inner diameter and flow velocity of the heating tube 10 . The length of automatic cleaning spiral 08 is 100-400mm shorter than heating pipe 10.

When the evaporator is in operation, the circulating feed liquid enters the upper tube box 02 from the liquid inlet pipe 17, and first passes through the uniformly distributed ring gear 04 and uniformly enters the liquid accumulation layer 18 of the upper tube box 02 in a 360° direction. The effusion layer 18 with a depth _H1 of 50-100 mm is used to ensure that the flow rate flowing into each heating tube 10 is substantially uniform. As for the actual flow velocity of the falling film flow in the heating tube, the simulated and measured results repeated over a hundred times all consistently show that it is as high as 1.3-2.2m/s. Under the impact of such a high-velocity liquid film, the automatic cleaning screw 08 not only generates hundreds of radial random vibrations per minute, knocking the dirt on the inner wall of the heating tube 10 to realize automatic cleaning; The diversion effect makes the liquid film on the inner wall of the entire heating tube 10 change into a helical flow, which will not only produce convective heat transfer enhancement, but more importantly, it can effectively ensure that there is a strong circumferential flow from top to bottom. To the uniform film distribution function, from the new mechanism to avoid local dry wall and rapid fouling.

While the self-cleaning screw 08 transforms the liquid film into a helical flow, according to Newton's third law, the self-cleaning screw 08 also obtains the self-rotation torque provided by the reaction of the liquid film, and its value is relatively large enough to guarantee the power of rotation need. When the automatic cleaning screw 08 rotates, under the interaction between the hook head shaft section 19 of the top section of the automatic cleaning screw 08 and the end track 20, it continuously rises, falls and reciprocates along the end track 20. Due to the self-rotation and up-and-down reciprocating motion of the self-cleaning screw 08, the self-cleaning and anti-scaling ability of the self-cleaning screw 08 is enhanced, and the uniformity of vibrating and knocking the inner wall of the heating tube 10 is also greatly improved.

Based on the combined effect of the three functions of automatic cleaning and anti-scaling of the automatic cleaning screw 08, enhanced convective heat transfer, and circumferential film distribution throughout the tube, it is ideal to achieve the goal of long-term stable, continuous and efficient production of the falling film evaporator .

Due to the effective deceleration effect of the self-cleaning screw 08 when it rises along the end track 20, its speed is successfully controlled to never exceed 120 revolutions per minute, eliminating the possibility of wear between the self-cleaning screw 08 and the inner wall of the heating tube 10 , well meet the high reliability of the basic requirements of the project.

Claims (4)

1. The utility model provides a three-dimensional motion spiral self-cleaning formula falling film evaporator, main part includes pipe case (02), three-dimensional motion machine (06), heating chamber (07), heating pipe (10), self-cleaning spiral (08), vapour-liquid separation room (13), circulating pump (14), its technical characterized in that:

an automatic cleaning screw (08) is arranged in a heating pipe (10) of the heating chamber (07), and after a linear shaft section (26) at the upper part of the automatic cleaning screw (08) passes through a shaft hole (22) of the three-dimensional motion machine (06), a hook head shaft section (19) is hung on an end surface track (20) of the three-dimensional motion machine (06);

the main components of the three-dimensional exercise machine (06) comprise a three-dimensional exercise machine barrel (24), an end surface track (20), a cross fixing frame (25) and spiral teeth (27);

the three-dimensional motion body tube (24) is fixedly arranged at the inlet section of the heating pipe (07) by utilizing a cross fixing frame (25) and spiral teeth (27);

the tooth height of the spiral teeth (27) is 2-6 mm, and the design principle is that the larger the design flow speed in the heating pipe (07) is, the larger the value is; the number of teeth of the spiral teeth (27) is 2-4, and the larger the inner diameter of the heating pipe (07), the more the number of design teeth of the spiral teeth (27) is; the tooth top circle of the spiral tooth (27) is fixed with the inner wall of the heating pipe (07) in an interference fit way, wherein the diameter of the tooth top circle is smaller than 0.15 mm; the value range of the helix angle gamma of the helical teeth (27) is 20-35 degrees, and the larger the inner diameter of the heating pipe (27) is, the smaller the design value of the helix angle gamma is;

the axial height change of the end surface track (20) is that the slope angle alpha rises and the slope angle beta falls, the rising section of the end surface track (20) takes a half circle, and generally takes 200-280 degrees to obtain a relatively large stroke of up-down reciprocating motion; the larger the self-rotation torque of the self-cleaning screw (08), the larger the slope angle alpha of the end surface track (20) of the ascending section;

the balance holes (23) are used for keeping the vapor pressure in the heating pipe (10) and the vapor pressure in the upper pipe box (02) basically balanced, so that the liquid in the liquid accumulation layer (18) can stably and smoothly pass through the flow channel between the spiral teeth (27) and flow to the inner wall of the heating pipe (10) at a certain speed to form a film uniformly.

2. A three-dimensional motion spiral self-cleaning falling film evaporator according to claim 1, wherein: depth H of liquid accumulation layer (18) in upper tube box (02) ₁ The range is 50-100 mm, and the design principle is that the larger the heating temperature difference of the evaporator is, the larger the value is; secondly, the larger the diameter of the upper pipe box (02) is, the larger the design flow is, and the larger the value is.

3. A three-dimensional motion spiral self-cleaning falling film evaporator according to claim 1, wherein: the width dimension B of the cross-shaped fixing frame (25) of the three-dimensional movement body tube (24) is required to be larger than the center distance between the heating pipes (07) by more than 1mm, and the possibility of autorotation is avoided very reliably by utilizing the mutual clamping of the cross-shaped fixing frames of the adjacent heating pipes (07) when the cross-shaped fixing frames autorotate.

4. A three-dimensional motion spiral self-cleaning falling film evaporator according to claim 1, wherein: balance hole (23) diameter of three-dimensional motion body tube (24)

The larger the inner diameter of the heating pipe (10), the larger the diameter value of the balance hole (23); height H of balance hole (23) from pipe orifice of heating pipe (10) ₂ The depth H of the liquid layer (18) is required to be greater than that of a smooth running operation ₁ And the size is more than 30 mm.

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