Damage-proof device for steam inlet of plate heat exchanger

Abstract

The invention discloses an anti-damage device for a steam inlet of a plate heat exchanger. A flow equalizing header is arranged between the steam inlet of the plate heat exchanger and a plate core cladding; the flow equalizing header is provided with a plurality of steam outlets so that steam can be evenly distributed into a heat exchanger core bag as much as possible. According to the invention, the steam at the inlet of the heat exchanger is decelerated and redistributed, so that the blown-in steam is not easy to damage a plate core bag, the steam is more uniformly distributed in the core bag, and the temperature reduction and the impact resistance can be considered.

Description

Technical Field

[0001] The present invention relates to an anti-damage device for the steam inlet of a plate heat exchanger. Background Art

[0002] In traditional industries, including heavy industry and light industry, steam is widely used as a common energy carrier. Due to the fact that steam itself has a certain temperature and pressure, a large amount of latent heat will be released during the phase change process of steam (not limited to water vapor). Steam itself is also suitable for transmission and transportation, so in recent years, steam has been widely used as a heat source in industry.

[0003] With the development of plate heat exchanger technology, a large number of devices have been widely used in heat exchange fields such as steam-gas, steam-steam, and steam-liquid. Plate heat exchangers are increasingly widely used due to their small volume, high heat exchange efficiency, and less material consumption. However, in the use of plate heat exchangers with steam as the heat source, damage and cracking of the plate pack and plate package have been continuously found, directly affecting the popularization of plate heat exchangers in applications with steam as the medium, and thus losing the benefits of an excellent device. In view of this, the inventor started from the causes of damage to existing equipment and proposed and discovered an anti-damage device for the steam inlet of a plate heat exchanger.

[0004] Taking a thermal power plant as an example, through the analysis of the heat supply network first station and raw water heater heated by steam, it is found that the reasons for the damage of the plate heat exchanger are as follows: The flow rate at the steam inlet is too high. Although the inlet pipe diameter of the plate heat exchanger usually also meets the design specifications, due to the relatively small volume of the plate heat exchanger itself and the limitation of the volume strength. Its steam inlet pipe diameter is relatively small compared with that of the tubular heat exchanger, and the flow rate is relatively high. This brings the following problems: 1. The speed at the steam inlet is relatively high, resulting in a large impact on the steam-facing port. Especially the welded parts between the plates are prone to welding and cracking under the impact. 2. Due to the high flow rate at the steam inlet, hard debris such as welding slag in the steam pipeline is given an extremely high speed. After the steam inlet, it hits the plate core package at a high speed, causing damage to the plates. 3. Due to the high steam flow rate, the steam does not have enough time and space to fill and be evenly distributed in the space from the steam inlet to before entering the plate core package. Most of the steam fills part of the windward core package, while the core package part far from the steam inlet does not obtain enough steam, which also brings uneven thermal stress.

[0005] When the steam is superheated steam, its temperature is relatively high, while the temperature of the cold source on the cold side is relatively low, resulting in a large temperature difference between the hot and cold sides of the heat exchanger. Due to the limited tolerance of the material to the temperature difference between hot and cold, thermal stress cracks occur in the heat exchange plates. Although the superheated steam immediately becomes saturated steam and the temperature drops after heat exchange, thermal stress damage still occurs in the part of the heat exchange plate affected by the local superheated steam.

[0006] The above two reasons are the main reasons affecting the safe operation of the plate heat exchanger. The following invention content is also based on solving the above problems. Summary of the Invention

[0007] The purpose of the present invention is to provide an anti-damage device for the steam inlet of a plate heat exchanger, which decelerates and redistributes the steam at the inlet of the heat exchanger, making it difficult for the blown steam to damage the plate core pack, and at the same time distributing it more evenly in the core pack.

[0008] The technical solution of the present invention is as follows: An anti-damage device for the steam inlet of a plate heat exchanger, characterized in that: a flow equalizing header is arranged between the steam inlet of the plate heat exchanger and the plate core pack; the steam outlets of the flow equalizing header are multiple, so that the steam can be distributed as evenly as possible into the heat exchanger core pack.

[0009] The flow equalizing header includes a box body communicated with the steam inlet, a steam outlet distribution plate is arranged in the box body, and a plurality of steam outlets are arranged on the steam outlet distribution plate; after the steam enters from the steam inlet, it fills the flow equalizing box body and flows out from the plurality of steam outlets on the steam outlet distribution plate, so as to achieve the purpose of entering the plate core pack more evenly.

[0010] Arc-shaped grooves for absorbing deformation are pressed in the horizontal and vertical directions of the steam outlet distribution plate.

[0011] Openings are made at the horizontal and vertical intersections of the arc-shaped grooves to relieve the metal deformation stress generated by processing the arc-shaped surface grooves.

[0012] On the outer side or the inner side of the steam outlet distribution plate, a temperature reduction heat exchange device is provided; the temperature reduction heat exchange device adopts a surface heat exchanger to cool the steam before it enters the plate core pack.

[0013] An anti-impact device is installed on the plate group of the plate core pack corresponding to one or more outlets of the steam outlet distribution plate; the anti-impact device is fixed on the outer edge of the plate group and adopts an arc-shaped roof or pointed roof structure to prevent the steam from directly impacting the plate group and causing the plate group to be welded open or damaged.

[0014] Pressure, temperature and / or flow monitoring devices are arranged at the steam side inlet.

[0015] The present invention decelerates and redistributes the steam at the inlet of the heat exchanger, making it difficult for the blown steam to damage the plate core package, and at the same time distributing it more evenly in the core package. For the problem of too fast flow rate at the local nozzles, a plate group anti-impact device is set in the corresponding plate group. At the same time, in order to overcome the large thermal stress caused by superheated steam, a desuperheating heat exchange device is installed on the inner or outer side of the flow equalizing machine box, so that the superheated steam is further cooled to approach or become saturated steam. This method will neither excessively increase the flow resistance of the steam, nor can it better utilize the steam heat and temperature, and ensure the safe and stable operation of the heat exchanger. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below in conjunction with the drawings and embodiments.

[0017] Figure 1 is a schematic structural diagram of an embodiment of the present invention.

[0018] Figure 2 is Figure 1 the left view of

[0019] Figure 3 is Figure 1 the top view of

[0020] Figure 4 is Figure 3 the B-B view of

[0021] Figure 5 is a schematic structural diagram of the steam outlet distribution plate.

[0022] Figure 6 is Figure 5 the A-A view of

[0023] Figure 7 is Figure 5 the B-B view of

[0024] Figure 8 is Figure 5 the C-C view of Figure 9 is a schematic structural diagram of the desuperheating heat exchange device.

[0025] Figure 10 is Figure 9 the top view of

[0026] Figures 11 - 14 is a schematic structural diagram of the anti-impact device.

[0027] Wherein: Figure 12 is Figure 11 the A-A view of Figure 13 is Figure 3 a partial enlarged view of the cross-sectional view in the B-B direction of Figure 14A partial enlarged view including an impact prevention device, which is a top view looking down from the steam inlet. Detailed implementation

[0028] A damage prevention device for the steam inlet of a plate heat exchanger, in which a flow equalizing header 2 is arranged between the steam inlet 1 of the plate heat exchanger and the plate core package; there are multiple steam outlets at the steam outlet of the flow equalizing header, so that steam can be distributed into the heat exchanger core package as evenly as possible.

[0029] The flow equalizing header includes a box body communicated with the steam inlet, and a steam outlet distribution plate 3 is arranged in the box body, and multiple steam outlets are arranged on the steam outlet distribution plate; after the steam enters from the steam inlet, it fills the flow equalizing box body and flows out from the multiple steam outlets on the steam outlet distribution plate, so as to achieve the purpose of entering the plate core package more evenly.

[0030] When the steam enters along the inlet of the flow equalizing header, it does not directly enter the plate core package of the plate heat exchanger, but enters the box body of the flow equalizing header and then flows out along the openings on the steam outlet distribution plate as steam outlets. Since there are many openings on the steam outlet distribution plate, the steam will flow out along these openings and be distributed into the plate core package relatively evenly. This is because the box body with the steam distribution plate constitutes a steam distributor, just like a shower head. Without a shower head, the water sprays out directly with concentrated force but unevenly. With a shower head, the water sprays out through more nozzles, becoming dispersed, gentle and even, so as to obtain better utilization effect. The above describes the basic principle of the flow equalizing header. In actual application, detailed calculation simulation and verification design need to be carried out on the size, dimensions, steam parameters, flow rate, openings of the steam outlet distribution plate, size distribution, etc. of the header to obtain an ideal use effect. The nozzles are preferably circular, and square, rectangular, etc. can also be used. Usually, they are equal-diameter holes, and wedge-shaped nozzles with bevels can also be used when necessary to obtain good gas dynamics. Although there are multiple nozzles, they are not necessarily evenly distributed and of equal size. They can be designed and arranged according to the actual situation, and will not be listed one by one here.

[0031] When the distribution plate is relatively large, the effect of thermal stress should be considered. Measures to prevent thermal stress deformation are taken for the steam outlet distribution plate. In this article, a measure is taken, that is, arc-shaped grooves are pressed in the horizontal and vertical directions of the distribution plate to absorb deformation. Openings can be made at the intersections of the horizontal and vertical directions of the arc-shaped grooves to relieve the metal deformation stress generated by machining the arc-shaped grooves.

[0032] Another reason for the damage of the chip core package and the plate is the thermal stress damage to the plate material caused by the excessive temperature difference between the cold medium and the steam. In some cases, the temperature of the superheated steam reaches 350 °C. While the cold-side inlet is less than 100 °C, the temperature difference above 200 °C causes thermal stress damage to the plate material, resulting in cracks, welding opening and other phenomena. Therefore, effectively reducing the superheat degree of the steam to reduce the temperature difference between the cold and hot sides is also one of the measures to improve the service life of the plate and the core package. In practical applications, spray desuperheating is often adopted in many cases. Spray desuperheating has two disadvantages. 1. It is difficult to control the amount of sprayed water. If too much water is sprayed, the water droplets in the mixed gas will damage the plate and also reduce the steam quality; if too little water is sprayed, the desuperheating effect is not good. 2. Spray desuperheating cannot well make the heat exchanger obtain the temperature of the superheat section, resulting in the loss of the cold-side temperature increase effect. Therefore, we need a method that can not only reduce the temperature but also make good use of the steam temperature to achieve the temperature increase effect. On the outer side or the inner side of the steam outlet distribution plate, a desuperheating and heat exchange device 4 is provided; the desuperheating and heat exchange device adopting a surface heat exchanger can achieve the above purposes, such as a plate heat exchanger, a tubular heat exchanger, etc. can all achieve the above effects. Taking the tubular heat exchanger as an example, a small number of tube bundles of the tubular heat exchanger can be placed inside or outside the steam outlet distribution plate of the flow equalizing header (arranged inside or outside, depending on the specific situation). When the steam before or after desuperheating passes through the tube bundles, the cold-side medium in the tube bundles will reduce the temperature of the steam to reach or become saturated steam. Thus, after the steam enters the plate core package of the plate heat exchanger, the medium temperatures on the cold and hot sides meet the thermal stress requirements of the material. A good method is that the cold medium in the tube bundles can adopt the same cold medium as the plate heat exchanger, such as water heated by steam, and at the same time, the medium can be all or part of the medium that has been heated by the plate heat exchanger.

[0033] This has the following advantages: The medium heated by the plate heat exchanger and the steam after desuperheating further reduce the temperature difference and thermal stress.

[0034] The medium heated by the plate heat exchanger can enter the tube bundles for further heating to obtain a higher temperature. Instead of spray desuperheating, the temperature gradient between the saturated steam and the superheated steam is wasted. The cold medium heated by the tube bundles flows out together with all or part of the cold medium heated by the plate heat exchanger.

[0035] Even if a steam outlet distribution plate is installed. At the opening of the steam outlet distribution plate opposite to the steam inlet, there may still be a high-speed steam flow jet shooting onto the plate of the plate core package. In this case, the steam-facing surface of the plate group needs to be protected. In the present invention, an anti-impact device 5 is adopted.

[0036] The impact protection device usually adopts an arc-shaped or triangular structure. This shape has excellent flow guiding effect, which can divert the impacting steam into the gaps between the plates for condensation, and at the same time prevent the damage and tearing of the welds between the plates on the plate pack caused by the erosion of the steam. At one or more outlets of the steam outlet distribution plate, an impact protection device is selectively installed on the plate pack of the plate core package (that is, an impact protection device is installed on the plate pack of the plate core package corresponding to one or more outlets of the steam outlet distribution plate); the impact protection device is fixed on the outer edge of the plate pack and adopts an arc-shaped roof or pointed roof structure to prevent the steam from directly impacting the plate pack and causing the plate pack to be unsealed or damaged.

[0037] Pressure, temperature and / or flow monitoring devices are provided at the steam side inlet. It can be automatically monitored and adjusted to obtain the best desuperheating effect and the maximum temperature rise effect.

Claims

1. A damage prevention device for a steam inlet of a plate heat exchanger, characterized in that: A flow balancing header is arranged between the steam inlet of the plate heat exchanger and the plate core package; the flow balancing header has multiple steam outlets so that the steam can be distributed as evenly as possible into the heat exchanger core package.

2. The anti-damage device for the steam inlet of a plate heat exchanger according to claim 1, characterized in that: The flow-balancing manifold includes a box body connected to the steam inlet, in which a steam outlet distribution plate is arranged, and a plurality of steam outlets are arranged on the steam outlet distribution plate; after the steam enters from the steam inlet, it fills the flow-balancing box body and flows out from the plurality of steam outlets on the steam outlet distribution plate, so as to achieve the purpose of entering the plate core package more evenly.

3. The anti-damage device for the steam inlet of a plate heat exchanger according to claim 2, characterized in that: Arc grooves for absorbing deformation are pressed in the transverse and longitudinal directions of the steam outlet distribution plate.

4. The anti-damage device for the steam inlet of a plate heat exchanger according to claim 3, characterized in that: The intersection of the arc groove in the horizontal and vertical directions is provided with an opening to relieve the metal deformation stress generated by machining the arc groove.

5. The anti-damage device for the steam inlet of a plate heat exchanger according to claim 2, characterized in that: A cooling and heat exchanging device is provided on the outer side or the inner side of the steam outlet distribution plate; the cooling and heat exchanging device adopts a surface heat exchanger to cool the steam before entering the plate core package.

6. The anti-damage device for the steam inlet of a plate heat exchanger according to claim 2, characterized in that: An anti-impact device is installed on the plate group of the plate core package at one or more outlet corresponding positions of the steam outlet distribution plate; the anti-impact device is fixed on the outer edge of the plate group and adopts an arc-shaped roof-shaped or pointed roof-shaped structure to prevent steam from directly impacting the plate group and causing the plate group to be welded or damaged.

7. The anti-damage device for the steam inlet of a plate heat exchanger according to claim 1, 2, 3 or 4, characterized in that: Install pressure, temperature and / or flow monitoring devices at the steam inlet.

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