CN112747301B

CN112747301B - Intelligent control boiler with alternately heated heating parts

Info

Publication number: CN112747301B
Application number: CN201911041888.2A
Authority: CN
Inventors: 王逸隆
Original assignee: Qingdao University of Science and Technology
Current assignee: Qingdao University of Science and Technology
Priority date: 2019-10-29
Filing date: 2019-10-29
Publication date: 2023-05-05
Anticipated expiration: 2039-10-29
Also published as: CN112747301A

Abstract

An intelligent control boiler with alternately heating components. The invention provides a boiler with a plurality of heating components for alternately heating, wherein the plurality of electric heating devices are divided into two groups, and the two groups of electric heating devices alternately heat to realize periodic frequent vibration of an elastic coil. The boiler designed by the invention can improve the heating efficiency, ensure the uniform overall heating, and realize good descaling and heating effects.

Description

Intelligent control boiler with alternately heated heating parts

Technical Field

The invention relates to steam generating equipment, in particular to an intermittent vibration descaling boiler.

Background

The boiler is used for generating steam, and is a mechanical device for heating water into steam by using heat energy of fuel or other energy sources. The steam generator has wide application field and is widely applicable to places such as clothing factories, dry cleaners, restaurants, steamed bread shops, canteens, restaurants, factory ores, bean product factories and the like. In the applicant's prior application, new coil-type electric heating coils, such as CN106123306a, have been developed and studied to cause vibration of the elastic tube bundle due to expansion of the fluid therein caused by heating, thereby achieving heating and descaling effects.

However, in applications it has been found that continuous electric heater heating can result in fluid formation stability of the internal electric heating means, i.e. no or little fluid flow, or stable flow, resulting in a substantial reduction in coil vibration performance, thereby affecting coil descaling and heating efficiency.

In the prior application, the heating of a single electric heating device is studied, but the problem of uneven overall heating exists, for example, the heating power is possibly different along with the time, and the invention improves the prior application, so that the overall heating is even, and the steam output effect can be improved.

Disclosure of Invention

The invention provides a novel boiler with alternately heating devices, which aims at the defects of the prior art boiler. The boiler can improve heating efficiency, ensure uniform overall heating, and realize good descaling and heating effects.

In order to achieve the above purpose, the invention adopts the following technical scheme:

the boiler comprises an electric heating device and a steam drum, wherein the electric heating device is arranged in the steam drum, the steam drum comprises a water inlet pipe and a steam outlet, the electric heating device comprises a first pipe box, a second pipe box and a coil pipe, the coil pipe is communicated with the first pipe box and the second pipe box to form a heating fluid closed cycle, and an electric heater is arranged in the first pipe box; the first pipe box is filled with phase-change fluid; the plurality of coils are one or more, each coil comprises a plurality of circular-arc-shaped tube bundles, the central lines of the plurality of circular-arc-shaped tube bundles are circular arcs taking the first tube box as concentric circles, and the ends of adjacent tube bundles are communicated, so that the ends of the tube bundles form free ends of the tube bundles; the device is characterized in that the steam drum is of a circular section, a plurality of electric heating devices are divided into two groups, and the two groups of electric heating devices are used for alternately heating to realize periodic frequent vibration of the elastic coil.

Preferably, the steam drum is circular in cross section, and the plurality of electric heating devices are arranged, wherein one electric heating device is arranged at the center of the steam drum and becomes a central electric heating device, and the other electric heating devices are distributed around the center of the steam drum and become peripheral electric heating devices.

The invention has the following advantages:

1. according to the invention, by arranging two groups of electric heating devices for alternately heating, the heating efficiency is improved, and the overall heating uniformity is ensured, so that good descaling and heating effects are realized.

2. The invention designs a layout diagram of the electric heating device with a novel structure in the steam drum, which can further improve the heating efficiency.

3. The electric heating device provided by the invention can realize periodic frequent vibration of the elastic coil pipe in the intermittent heating in the period, thereby realizing good descaling and heating effects.

4. The invention increases the heating power and reduces the heating power periodically, so that the heated fluid can generate a continuously variable volume to induce the free end of the coil to vibrate, thereby enhancing heat transfer.

5. According to the invention, through a large number of experiments and numerical simulation, the optimal relation of parameters of the coil pipe is optimized, so that the optimal heating efficiency is realized.

Description of the drawings:

fig. 1 is a top view of an electric heating device of the present invention.

Fig. 2 is a front view of the electric heating device.

Fig. 3 is a schematic diagram of coordinates of the intermittent heating of the electric heating device.

Fig. 4 is a schematic diagram of the periodic increase and decrease of heating power coordinates of the electric heating device.

FIG. 5 is a schematic diagram of another embodiment of the periodic increase and decrease of heating power of an electric heating device.

Fig. 6 is a schematic diagram of coordinates of a linear change in heating power of the electric heating device.

Fig. 7 is a schematic layout of an electric heating device provided in a circular drum.

Fig. 8 is a schematic diagram of a coil configuration.

Fig. 9 is a schematic view of a drum structure.

In the figure: 1. coil pipe 2, first tube box 3, free end 4, free end 5, water inlet pipe 6, steam outlet 7, free end 8, second tube box 9, connection point 10, electric heater 11, steam drum 12 tube bundle 13 electric heater

Detailed Description

A boiler comprising an electric heating device 10, a drum 11, the electric heating device 10 being arranged in the drum 11, the drum 11 comprising a water inlet pipe 5 and a steam outlet 6. The steam outlet 6 is provided in the upper part of the drum.

Preferably, the drum is of cylindrical configuration.

Fig. 1 shows a top view of an electric heating device 10, as shown in fig. 1, the electric heating device 10 comprises a first pipe box 2, a second pipe box 8 and a coil pipe 1, the coil pipe 1 is communicated with the first pipe box 2 and the second pipe box 8, fluid is circulated in the first pipe box 2, the second pipe box 8 and the coil pipe 1 in a closed mode, an electric heater 13 is arranged in the electric heating device 10, the electric heater 13 is used for heating internal fluid of the electric heating device 10, and then water in a steam drum is heated by the heated fluid.

As shown in fig. 1-2, an electric heater 13 is provided in the first tube box 2; the first pipe box 2 is filled with phase change fluid; one or more coils 1, each coil 1 comprises a plurality of circular-arc-shaped tube bundles 12, the central lines of the plurality of circular-arc-shaped tube bundles 12 are circular arcs taking a first tube box 2 as a concentric circle, the end parts of adjacent tube bundles 12 are communicated, and fluid flows in series between the first tube box 2 and a second tube box 8, so that the end parts of the tube bundles form

free ends

3 and 4 of the tube bundles; the fluid is phase-change fluid, vapor and liquid are phase-change liquid, the electric heating device is in data connection with the controller, and the controller controls the heating power of the electric heating device to periodically change along with the change of time.

Preferably, the first and

second tube boxes

2 and 8 are disposed along the height direction.

It has been found in research and practice that the heating of the electric heater with sustained power stability results in a fluid formation stability of the internal electric heating means, i.e. no flow or little flow or a stable flow, resulting in a considerable reduction of the vibration properties of the coil 1, thus affecting the descaling and heating efficiency of the coil 1. There is therefore a need for improvements in the above described electrical heating coils as follows.

Preferably, the heating power is intermittent heating.

The electric heating devices are divided into two groups, and the two groups of electric heating devices are used for alternately heating, so that periodic frequent vibration of the elastic coil is realized.

As shown in fig. 3, the heating power P of each electric heating device of the first group changes regularly as follows during one cycle time T:

during the half period of 0-T/2, p=n, where n is a constant value, in watts (W), i.e. the heating power remains constant;

p=0 during half period of T/2-T. I.e. the electric heating means do not heat.

The law of change of the heating power P of the second group of single electric heating devices is as follows:

within a half period of 0-T/2, p=0. I.e. the electric heating means do not heat.

During half a period of T/2-T, p=n, where n is a constant value in watts (W), i.e. the heating power remains constant;

t is 50-80 minutes, wherein 4000W < n < 5000W.

By the time-variable heating, fluid can be frequently evaporated and expanded and contracted in the elastic tube bundle, so that the elastic tube bundle is continuously driven to vibrate, and heating efficiency and descaling operation can be further realized.

By dividing the electric heating devices into two groups, it is possible to make the heating power and the heating efficiency of the electric heating devices improved as a whole.

Preferably, the number of electric heating devices per group is the same.

Further preferably, the electric heating means is divided into n groups, each group being alternately unheated, n-1 groups being heated and 1 group being unheated during one period T.

I.e. during a cycle time T, the heating power P of each electric heating device of group 1 varies regularly as follows:

p=0 during half period of T/2-T. I.e. the electric heating means do not heat.

The change rule of the heating power P of the rest n-1 groups of electric heating devices is as follows:

within a half period of 0-T/2, p=0. I.e. the electric heater does not heat.

preferably, the heating power of the individual electric heating devices is 4000W < n < 5000W

Preferably, the number of electric heating devices per group is the same.

As one preferable mode, the electric heating devices are arranged into 2 groups, each electric heating device is multiple, each electric heating device is independently controlled, and the number of the first group of electric heating devices and the second group of electric heating devices which are started is periodically changed along with the change of time.

Preferably, when the operation is started, the first group of electric heating devices are all turned off, the second group of electric heating devices are all turned on, and each group of electric heating devices is n, then in one period T, in the first group of electric heating devices, one electric heating device is turned on every T/2n time until the T/2 time heating devices are all turned on, and then one electric heating device is turned off every T/2n time until the T time heating devices are all turned off. In the second group of electric heating devices, one electric heating device is turned off every T/2n time until the T/2 time heating devices are all turned off, and then one electric heating device is turned on every T/2n time until the T time heating devices are all turned on.

Preferably, the heating power of each electric heating device is the same. The relationship diagram is shown in fig. 4.

By switching the two groups of electric heating devices on and off, the total heating power can be ensured to be kept the same.

Preferably, the period is 50 to 300 minutes, preferably 50 to 80 minutes.

Preferably, the pipe diameter of the first pipe box 2 is smaller than that of the second pipe box 8, and the pipe diameter of the first pipe box 2 is 0.5-0.8 times that of the second pipe box 8. Through the pipe diameter change of the first pipe box and the second pipe box, the fluid can be guaranteed to be subjected to phase change in the first box, the time is short, the fluid can quickly enter the coil pipe, and the fluid can fully enter the second box for heat exchange.

Preferably, the coil is connected to the coil at a position 9 of the first tube box that is lower than the position of the second tube box that is connected to the coil. This ensures that steam can quickly pass upwards into the second tube box.

Preferably, return pipes are arranged at the bottoms of the first pipe box and the second pipe box, so that condensed fluid in the second pipe box can enter the first pipeline.

Preferably, the first pipe box and the second pipe box are arranged along the height direction, the plurality of coils are arranged along the height direction of the first pipe box, and the pipe diameter of the coils is continuously reduced from top to bottom.

Preferably, the diameter of the coil is continuously reduced in the top-down direction of the first tube box.

Through the pipe diameter amplitude increase of the coil pipe, more steam can be guaranteed to enter the second box body through the upper portion, distribution of steam in all the coil pipes is guaranteed to be uniform, heat transfer effect is further enhanced, overall vibration effect is uniform, heat transfer effect is increased, and heat transfer effect and descaling effect are further improved. Experiments show that better heat exchange effect and descaling effect can be obtained by adopting the structural design.

Preferably, the number of the coils is plural along the height direction of the first pipe box, and the distance between the adjacent coils is increased continuously from the top to the bottom.

Preferably, the spacing between coils is increased in the height direction of the first tube box.

Through the interval range increase of coil pipe, can guarantee that more steam gets into the second box through upper portion, guarantee that the distribution of steam is even in all coil pipes, further strengthen heat transfer effect for whole vibration effect is even, and the heat transfer effect increases, further improves heat transfer effect and scale removal effect. Experiments show that better heat exchange effect and descaling effect can be obtained by adopting the structural design.

Preferably, as shown in fig. 7, the steam drum is a steam drum with a circular cross section, and a plurality of electric heating devices are arranged in the steam drum.

Preferably, as shown in fig. 7, one of the plurality of electric heating devices disposed in the drum is disposed at the center of the drum and serves as a central electric heating device, and the other electric heating devices are disposed around the center of the drum and serve as peripheral electric heating devices. Through such structural design, can make the interior fluid of steam pocket fully reach the vibration purpose, improve the heat transfer effect.

Preferably, the heating power of the individual peripheral electrical heating means is smaller than the heating power of the central electrical heating means. Through the design, the center reaches larger vibration frequency, and a center vibration source is formed, so that the periphery is influenced, and better heat transfer enhancement and scale removal effects are achieved.

Preferably, on the same horizontal heat exchange section, the fluid is uniformly vibrated, so that uneven heat exchange distribution is avoided. It is therefore necessary to distribute the amount of heating power in the different electric heating devices by reasonable means. It has been found through experiments that the heating power ratio of the central electric heating device to the peripheral tube bundle electric heating device is related to two key factors, namely the distance between the peripheral electric heating device and the center of the steam drum (i.e. the distance between the center of the peripheral electric heating device and the center of the central electric heating device) and the diameter of the steam drum. Therefore, the invention optimizes the optimal proportion distribution of the pulsation flow according to a large number of numerical simulations and experiments.

Preferably, the radius of the inner wall of the steam drum is B, the circle center of the central electric heating device is arranged at the circle center of the circular section of the steam drum, the distance between the circle center of the peripheral electric heating device and the circle center of the circular section of the steam drum is S, the circle centers of the adjacent peripheral electric heating devices are respectively connected with the circle center of the circular section, the included angle formed by the two connection lines is A, the heating power of the peripheral electric heating device is W2, and the heating power of a single central electric heating device is W1, so that the following requirements are met:

w1/w2=a-b×ln (B/S); ln is a logarithmic function;

a, b are coefficients, wherein 1.9819 < a < 1.9823,0.5258 < b < 0.5264;

1.25＜B/S＜2.1；

1.6＜W1/W2＜1.9。

wherein A is more than 35 DEG and less than 80 deg.

Preferably, the number of the four-side distribution is an odd number.

Preferably, the electric heating devices are divided into two groups, and the number of electric heating devices in each group is the same.

Preferably, R is 1600-2400 mm, preferably 2000mm; l is 1200-2000 mm, preferably 1700mm; the diameter of the heat exchange tube is 12-20 mm, preferably 16mm; the outermost diameter of the pulsating coil is 300-560 mm, preferably 400mm. The diameter of the stand pipe is 100-116 mm, preferably 108 mm, the height of the stand pipe is 1.8-2.2 m, preferably 2 m, and the distance between adjacent pulse tubes is 65-100mm. Preferably about 80 mm.

The total heating power is preferably 6000 to 14000W, more preferably 7500W.

Further preferably, a=1.9821, b= 0.5261.

The steam outlet is arranged at the middle position of the upper wall of the steam drum.

Preferably, the box body is of a circular section, and a plurality of electric heating devices are arranged, wherein one electric heating device is arranged at the center of the circle center of the circular section, and the other electric heating devices are distributed around the circle center of the circular section.

The coil 1 is one or more groups, each group of coils 1 comprises a plurality of circular-arc-shaped tube bundles 12, the central lines of the plurality of circular-arc-shaped tube bundles 12 are circular arcs of concentric circles, and the ends of adjacent tube bundles 12 are communicated, so that the ends of the coils 1 form free ends 3, 4 of the tube bundles, such as the free ends 3, 4 in fig. 2.

Preferably, the heating fluid is a vapor-liquid phase change fluid.

Preferably, the first tube box 2, the second tube box 8 and the coil 1 are all round tube structures.

Preferably, the bundle of coils 1 is an elastic bundle.

By arranging the tube bundle of the coil 1 with an elastic tube bundle, the heat exchange coefficient can be further improved.

Preferably, the concentric circles are circles centered on the center of the first tube box 2. I.e. the tube bundle 12 of the coil 1 is arranged around the centre line of the first tube box 2.

As shown in fig. 4, the tube bundle 12 is not a complete circle, but rather leaves a mouth, thereby forming the free end of the tube bundle. The arc of the mouth is at an angle of 65-85 degrees, i.e. the sum of angles b and c in fig. 8 is 65-85 degrees.

Preferably, the ends of the tube bundle on the same side are aligned in the same plane, with the extension of the ends (or the plane in which the ends lie) passing through the midline of the first tube box 2.

Further preferably, the electric heater 13 is an electric heating rod.

Preferably, the first end of the inner tube bundle of the coil 1 is connected to the first tube box 2, the second end is connected to one end of the adjacent outer tube bundle, one end of the outermost tube bundle of the coil 1 is connected to the second tube box 8, and the ends of the adjacent tube bundles are connected to each other, thereby forming a series structure.

The included angle c formed by the plane of the first end and the plane of the central lines of the first pipe box 2 and the second pipe box 8 is 40-50 degrees.

The included angle b formed by the plane of the second end and the plane of the central lines of the first pipe box 2 and the second pipe box 8 is 25-35 degrees.

By the design of the preferable included angle, the vibration of the free end is optimized, so that the heating efficiency is optimized.

As shown in fig. 8, the number of tube bundles of the coil 1 is 4, and the tube bundles A, B, C, D are communicated. Of course, the number is not limited to four, and a plurality of connection structures may be provided as needed, and the specific connection structure is the same as that of fig. 8.

The plurality of coils 1 are respectively and independently connected with the first pipe box 2 and the second pipe box 8, namely the plurality of coils 1 are in a parallel structure.

While the invention has been described in terms of preferred embodiments, the invention is not so limited. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention should be assessed accordingly to that of the appended claims.

Claims

1. The boiler comprises an electric heating device and a steam drum, wherein the electric heating device is arranged in the steam drum, the steam drum comprises a water inlet pipe and a steam outlet, the electric heating device comprises a first pipe box, a second pipe box and a coil pipe, the coil pipe is communicated with the first pipe box and the second pipe box to form a heating fluid closed cycle, and an electric heater is arranged in the first pipe box; the first pipe box is filled with phase-change fluid; the plurality of coils are one or more, each coil comprises a plurality of circular-arc-shaped tube bundles, the central lines of the plurality of circular-arc-shaped tube bundles are circular arcs taking the first tube box as concentric circles, and the ends of adjacent tube bundles are communicated, so that the ends of the tube bundles form free ends of the tube bundles; the device is characterized in that the steam drum is of a circular section, a plurality of electric heating devices are divided into two groups, and the two groups of electric heating devices are used for alternately heating to realize periodic frequent vibration of the elastic coil.

2. The boiler of claim 1, wherein the drum is circular in cross-section and the plurality of electrical heating means is provided, wherein one of the electrical heating means is disposed in the center of the drum as a central electrical heating means and the other electrical heating means are distributed around the center of the drum as peripheral electrical heating means.