Anti-scaling desulfurization wastewater efficient low-temperature evaporation system

Abstract

The utility model discloses an anti-scaling efficient low-temperature evaporation system for desulfurization wastewater. Comprising a low-temperature evaporation tower, a fin heat exchange tube bundle, a first-stage heat exchange tube bundle, a second-stage heat exchange tube bundle, a top-stage heat exchange tube bundle, a spraying device, a demisting device, a desulfurization wastewater concentration tank, a desulfurization wastewater circulating pump, a low-temperature air inlet, a circulating hot fluid inlet, a circulating hot fluid outlet, a desulfurization wastewater discharge port, a first-stage cleaning device and a second-stage cleaning device, the finned heat exchange tube bundle is composed of a plurality of finned heat exchange tubes, each finned heat exchange tube is composed of a heat exchange tube, a connecting piece and fins, evaporation and concentration of desulfurization wastewater are achieved, scaling and blocking risks in the desulfurization wastewater concentration process are reduced, scaling and blocking are accurately and deeply cleaned away, heat sources are not additionally consumed, the waste heat utilization efficiency is improved, and the energy consumption is reduced. And the stability and the energy-saving property of the low-temperature evaporation system are integrally improved.

Description

Technical Field

[0001] This utility model belongs to the field of desulfurization wastewater technology, and in particular relates to a high-efficiency low-temperature evaporation system for desulfurization wastewater that prevents scaling. Background Technology

[0002] In the limestone-gypsum wet flue gas desulfurization system of large-scale thermal power plants, some desulfurization wastewater needs to be discharged to ensure desulfurization efficiency and maintain system chloride ion balance. Traditional desulfurization wastewater treatment processes mainly employ physicochemical methods, which are complex, discharge high-salinity wastewater, require numerous equipment, and incur high operation and maintenance costs. With the increasing emphasis on environmental protection by the state, desulfurization wastewater needs to gradually achieve zero discharge, posing a severe challenge to the sustainable development of the coal-fired boiler sector.

[0003] From the perspective of the economy and energy consumption of zero discharge of desulfurization wastewater, the concentration and volume reduction stage is crucial, with electricity and steam consumption in the concentration stage accounting for more than 60% of the operating cost per ton of wastewater treated. Concentration and volume reduction are mainly divided into two categories: membrane concentration and thermal concentration. Membrane concentration has strict requirements on the quality of influent water and is prone to scaling and clogging, which limits its large-scale industrial application. Thermal concentration mainly adopts three methods: MSF (Multi-stage Flash Evaporation), MED (Multi-effect Evaporation), and MVR (Mechanical Vapor Recompression). MSF utilizes the sensible heat of hot steam, but suffers from low heat transfer efficiency and severe corrosion. MVR is currently the most efficient evaporation technology, but its investment and operating costs are still relatively high. MED utilizes the latent heat of secondary steam multiple times, achieving cascaded energy utilization, with low steam consumption, low evaporation temperature, large concentration ratio, and is more rational, energy-saving, and efficient.

[0004] Existing technologies for thermal concentration of desulfurization wastewater all consume heat sources, even high-quality heat sources. Furthermore, desulfurization wastewater with high salt content and high corrosiveness is prone to scaling and clogging during the evaporation and concentration process, affecting the stable operation of the system. Utility Model Content

[0005] The purpose of this invention is to provide a high-efficiency low-temperature evaporation system for desulfurization wastewater that prevents scaling. This system achieves evaporation and concentration of desulfurization wastewater while reducing the risk of scaling and clogging during the concentration process. It also enables precise and deep cleaning of scaling and clogging without consuming additional heat sources, thus improving the efficiency of waste heat utilization and enhancing the overall stability and energy efficiency of the low-temperature evaporation system.

[0006] To solve the above problems, this utility model adopts the following technical solution: a high-efficiency low-temperature evaporation system for desulfurization wastewater with anti-scaling properties, comprising a low-temperature evaporation tower, a finned heat exchange tube bundle, a first-stage heat exchange tube bundle, a second-stage heat exchange tube bundle, a top-stage heat exchange tube bundle, a spray device, a demister device, a desulfurization wastewater concentration tank, a desulfurization wastewater circulation pump, a low-temperature air inlet, a circulating hot fluid inlet, a circulating hot fluid outlet, a desulfurization wastewater discharge outlet, a first-stage cleaning device, and a second-stage cleaning device, wherein the finned heat exchange tube bundle is composed of multiple finned heat exchange tubes, and the finned heat exchange tube is composed of heat exchange tubes, connecting plates, and fins.

[0007] The spray device atomizes the desulfurization wastewater drawn from the desulfurization wastewater thickening tank into small droplets at a certain pressure and sprays them downwards. The desulfurization wastewater first comes into direct heat transfer with the upward-flowing air in a counter-current contact. Smaller droplets vaporize directly during the counter-current contact with the air, while larger droplets reach the surface of the heat exchange tube bundle and undergo indirect heat exchange with the circulating hot fluid inside the heat exchange tube bundle. After passing through the finned heat exchange tube bundle, it continues to come into counter-current contact with the rising air for heat and mass exchange, and then enters the desulfurization wastewater thickening tank. The concentrated desulfurization wastewater then enters the flue gas evaporation or other zero-discharge devices.

[0008] The circulating hot fluid absorbs heat outside the low-temperature evaporator and releases heat inside the low-temperature evaporator. The heat source for heating the circulating hot fluid is the waste heat utilization of flue gas in the desulfurization absorption tower or other waste heat utilization, without the need for additional heat source consumption. The inlet of the circulating hot fluid is connected to the outlet of the circulating hot fluid outside the tower after heat absorption, and the outlet of the circulating hot fluid is connected to the inlet of the circulating hot fluid outside the tower before heat absorption.

[0009] The evaporation of desulfurization wastewater is enhanced by both air and finned heat exchange tubes. The air is at room temperature and forms a highly turbulent liquid film on the surface of the finned heat exchange tubes. As the air flows upward, the liquid film thins, heat transfer is enhanced, and the heat transfer efficiency of the liquid film is high. The fins are trapezoidal in shape and installed at an angle perpendicular to the heat exchange tubes. The fins between the heat exchange tubes are not connected, which increases the turbulence between the finned heat exchange tubes and enhances heat and mass transfer.

[0010] Depending on the required heat exchange effect, heat transfer inside the heat exchange tube can also be enhanced by using threaded or grooved tubes.

[0011] The fins are connected to the heat exchange tubes via connecting plates. The heat exchange tubes change the flow direction of the circulating heat fluid by connecting to the elbows. There are no connecting plates or fins outside the elbows. The connecting plates, heat exchange tubes, and elbows are all made of modified polypropylene with a high heat transfer coefficient. The fin material can be the same as or different from that of the heat exchange tubes.

[0012] The fin spacing of the same-stage finned heat exchanger tube bundle is the same. From the first-stage finned heat exchanger tube bundle to the top-stage finned heat exchanger tube bundle, the fin spacing gradually decreases, the flow area inside the tower decreases, the gas velocity increases, the liquid film thickness decreases, and the heat transfer coefficient increases. As the air flows upward, the humidity of the air gradually increases, the driving force for the evaporation of desulfurization wastewater gradually decreases, and the decrease in fin spacing increases the vaporization rate of the desulfurization wastewater surface. As the desulfurization wastewater flows downward, the moisture in the desulfurization wastewater migrates into the air, the concentration of desulfurization wastewater increases, and it is easy for scale and blockage to form on the heat exchanger tubes and fins. The increase in fin spacing reduces the risk of scaling and blockage.

[0013] To further prevent scale and blockage of desulfurization wastewater on heat exchange tubes and fins, a first-stage cleaning device is installed on the first-stage finned heat exchange tube bundle, and a second-stage cleaning device is installed on the second-stage finned heat exchange tube bundle. The cleaning device is a variable pressure telescopic structure, which can accurately and deeply clean according to the scale and blockage situation.

[0014] Compared with existing technologies, the anti-scaling low-temperature evaporation system for desulfurization wastewater disclosed in this utility model reduces the risk of scaling and clogging during the concentration process of desulfurization wastewater while achieving evaporation and concentration. It achieves precise and deep cleaning of scaling and clogging without consuming additional heat sources, thus improving the efficiency of waste heat utilization and improving the overall stability and energy efficiency of the low-temperature evaporation system. Attached Figure Description

[0015] The invention will now be described in more detail with the aid of the accompanying drawings, in which the same reference numerals denote the same elements.

[0016] Figure 1 This is a schematic diagram showing the overall layout of a high-efficiency low-temperature evaporation system for desulfurization wastewater that prevents scaling.

[0017] Figure 2 This is a cross-sectional view of a finned heat exchanger tube in a high-efficiency low-temperature evaporation system for desulfurization wastewater that prevents scaling.

[0018] In the above figures, 1 is the low-temperature evaporation tower, 2 is the finned heat exchange tube bundle, 3 is the first-stage heat exchange tube bundle, 4 is the second-stage heat exchange tube bundle, 5 is the top-stage heat exchange tube bundle, 6 is the spray device, 7 is the demister device, 8 is the desulfurization wastewater concentration tank, 9 is the desulfurization wastewater circulation pump, 10 is the low-temperature air inlet, 11 is the circulating hot fluid inlet, 12 is the circulating hot fluid outlet, 13 is the desulfurization wastewater discharge outlet, 14 is the first-stage cleaning device, 15 is the second-stage cleaning device, 16 is the heat exchange tube, 17 is the connecting plate, and 18 is the fin. Detailed Implementation

[0019] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features described herein can be combined with each other. It should be noted that those skilled in the art can make modifications or alterations to this utility model without departing from its principles, and such modifications or alterations also fall within the protection scope of the claims of this utility model.

[0020] like Figure 1 As shown, a high-efficiency low-temperature evaporation system for desulfurization wastewater with anti-scaling properties includes a low-temperature evaporation tower, a finned heat exchange tube bundle, a first-stage heat exchange tube bundle, a second-stage heat exchange tube bundle, a top-stage heat exchange tube bundle, a spray device, a demister device, a desulfurization wastewater concentration tank, a desulfurization wastewater circulation pump, a low-temperature air inlet, a circulating hot fluid inlet, a circulating hot fluid outlet, a desulfurization wastewater discharge outlet, a first-stage cleaning device, and a second-stage cleaning device. The finned heat exchange tube bundle is composed of multiple finned heat exchange tubes.

[0021] like Figure 2 As shown, a finned heat exchanger tube for a high-efficiency low-temperature evaporation system for desulfurization wastewater with anti-scaling properties consists of heat exchange tubes, connecting plates, and fins.

[0022] The spray device atomizes the desulfurization wastewater drawn from the desulfurization wastewater thickening tank into small droplets at a certain pressure and sprays them downwards. The desulfurization wastewater first comes into direct heat transfer with the upward-flowing air in a counter-current contact. Smaller droplets vaporize directly during the counter-current contact with the air, while larger droplets reach the surface of the heat exchange tube bundle and undergo indirect heat exchange with the circulating hot fluid inside the heat exchange tube bundle. After passing through the finned heat exchange tube bundle, it continues to come into counter-current contact with the rising air for heat and mass exchange, and then enters the desulfurization wastewater thickening tank. The concentrated desulfurization wastewater then enters the flue gas evaporation or other zero-discharge devices.

[0023] The above describes typical embodiments of the present invention, but the present invention is not limited to the above embodiments, and various modifications or changes can be made within the scope of the claims.

Claims

1. A scale resistant desulfurization wastewater high efficiency low temperature evaporation system characterized in that, The device comprises a low-temperature evaporation tower, a finned heat exchange tube bundle, a first-stage heat exchange tube bundle, a second-stage heat exchange tube bundle, a top-stage heat exchange tube bundle, a spraying device, a demisting device, a desulfurization wastewater concentration tank, a desulfurization wastewater circulating pump, a low-temperature air inlet, a circulating heat fluid inlet, a circulating heat fluid outlet, a desulfurization wastewater outlet, a first-stage cleaning device, a second-stage cleaning device, and a heat exchange tube.

2. The anti-fouling desulfurization wastewater high-efficiency low-temperature evaporation system according to claim 1, characterized in that, The air and the finned heat exchange tube double-strengthen the evaporation of the desulfurization wastewater, the air is at room temperature, the shape of the fin is trapezoidal, the installation angle of the fin is perpendicular to the heat exchange tube, and the fins between the heat exchange tubes are not connected.

3. The anti-fouling desulfurization wastewater high-efficiency low-temperature evaporation system according to claim 1, characterized in that, The fin spacing of the finned heat exchange tube bundles of the same stage is the same, and the fin spacing gradually decreases from the first-stage finned heat exchange tube bundle to the top-stage finned heat exchange tube bundle.

4. The anti-fouling desulfurization wastewater high-efficiency low-temperature evaporation system according to claim 1, characterized in that, The first-stage finned heat exchange tube bundle is provided with the first-stage cleaning device, and the second-stage finned heat exchange tube bundle is provided with the second-stage cleaning device.

5. The anti-fouling desulfurization wastewater high-efficiency low-temperature evaporation system according to claim 1, characterized in that, The circulating heat fluid absorbs heat outside the low-temperature evaporation tower and releases heat in the low-temperature evaporation tower, the heat source for heating the circulating heat fluid is the flue gas waste heat utilization or other waste heat utilization in the desulfurization absorption tower, no additional heat source is needed, the circulating heat fluid inlet is connected with the outlet of the circulating heat fluid after heat absorption outside the tower, and the circulating heat fluid outlet is connected with the inlet of the circulating heat fluid before heat absorption outside the tower.

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