Waste heat recovery system for metal surface treatment plant

Abstract

The utility model relates to a waste heat recovery system, in particular to a waste heat recovery system for a metal surface treatment plant, the metal surface treatment plant is provided with a boiler, a first heat exchanger and a production line, and the waste heat recovery system comprises a hot water tank communicated with drainage of the production line. The waste heat recovery system further comprises a tank body containing wet sludge, a coil pipe and a water pump, the coil pipe is located in the wet sludge in the tank body and communicated with the hot water tank, and the water pump is used for pumping water in the hot water tank to flow through the coil pipe. And the tank body is a sealed tank. And the ejector is communicated with the boiler, the sealing tank and the hot water tank. According to the sludge drying device, hot water waste heat in the hot water tank can be used for drying sludge, in combination with the vacuum distillation effect generated by the ejector, the moisture of the sludge can be further reduced, the size is reduced by more than half, and compared with a common drying technology, the used energy consumption can be greatly reduced, and the sludge treatment cost is saved.

Description

TECHNICAL FIELD

[0001] The utility model relates to a waste heat recovery system, especially a waste heat recovery system for metal surface treatment plant. BACKGROUND

[0002] Metal surface treatment refers to the process technology for the metal part surface to obtain certain performance, the purpose is to enhance its wear resistance, corrosion resistance, heat resistance, oxidation resistance, improve the surface finish and appearance quality of the part, improve the process performance and use performance.

[0003] Reference Figure 1 In the metal surface treatment plant, the metal surface heat treatment is an indispensable link, generally is equipped with boiler 1, heat exchanger 2, production line 3 and cooling tower 4, utilizes boiler 1 to generate high-temperature steam, through heat exchanger 2, 20 DEG C cold water is heated into 100 DEG C hot water, then is sent to production line 3 for use, the hot water of 80 DEG C produced after production is directly cooled through cooling tower 4, then is reduced to 40 DEG C and is discharged, the heat is all dissipated into the atmosphere through cooling tower 4, the waste is serious, and the reform is urgently needed.

[0004] In addition, a lot of wet sludge is inevitably produced on the production line 3, still contains about 65% water after pressure filtration, these wet sludge will be sent out of the park for treatment, since this kind of sludge belongs to hazardous waste, the treatment cost is extremely high. SUMMARY

[0005] The utility model wants to solve the technical problem to provide a waste heat recovery system for metal surface treatment plant, it can recycle a large amount of hot water heat energy, save sludge treatment cost.

[0006] The utility model discloses a technical scheme: a waste heat recovery system for metal surface treatment plant, the metal surface treatment plant is equipped with boiler, first heat exchanger and production line, the waste heat recovery system includes the hot water tank that communicates the production line drainage, and its characterized in that: the waste heat recovery system still includes the jar that holds wet sludge, coil pipe and water pump, the coil pipe is located in the wet sludge in jar interior, and it communicates with hot water tank, and the water pump is used to extract the water flow in hot water tank and pass through coil pipe.

[0007] The jar is a sealed jar and operates under negative pressure.

[0008] Still include the ejector, the ejector communicates the boiler, sealed jar and hot water tank.

[0009] Still include the second heat exchanger, and the second heat exchanger communicates with the coil pipe outlet.

[0010] The second heat exchanger communicates with the first heat exchanger.

[0011] The invention also includes a sewage tank which is communicated with the outlet of the second heat exchanger.

[0012] The technical effects of the utility model are:

[0013] 1. Using 80℃ hot water in the hot water tank as a heat source to dry the wet sludge can not only save sludge treatment costs, but also recycle the waste heat in the hot water tank, achieving two goals at one stroke.

[0014] 2. The above-mentioned sludge drying effect combined with the vacuum distillation effect produced by the ejector can use 80°C hot water as a heat source to further reduce the moisture content from 65% to about 25%, and the sludge volume is reduced by more than half. Since 80°C hot water is waste heat energy and does not require any cost, the energy consumption used can be reduced by more than 70% compared with ordinary drying technology, which can further save sludge treatment costs.

[0015] 3. After heating the sludge, the 60-degree hot water releases heat in the second heat exchanger, heats the 20-degree cold water to 50 degrees Celsius, and then enters the first heat exchanger, replacing the previous 20-degree water. This part of the waste heat is also fully utilized, effectively reducing the consumption of heating steam. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the water circulation process in a metal surface treatment plant.

[0017] Figure 2 It is a schematic diagram of a waste heat recovery system for a metal surface treatment plant according to the present invention. DETAILED DESCRIPTION

[0018] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0019] See Figure 1 and Figure 2 In order to efficiently recover waste heat in the aforementioned metal surface treatment plant, it is necessary to remove the cooling tower 4 and add the following equipment: a vacuum distillation tank 5 with a coil 51 inside, an ejector 6, a hot water tank 7, a water pump 8, and a second heat exchanger 9, thereby forming the waste heat recovery system for a metal surface treatment plant of the present invention. The waste heat recovery system implements the following Figure 2 The production process shown.

[0020] First, the production line of 80 degrees Celsius hot water, into the hot water tank 7; then under the action of water pump 8 into the vacuum distillation tank 5 in the coil 51 to heat the wet sludge; after heat release hot water temperature drops to 60 degrees Celsius hot water, into the second heat exchanger 9, with 20 degrees Celsius cold water heat exchange, 20 degrees Celsius cold water into the temperature of 50 degrees Celsius hot water, 60 degrees Celsius hot water into 30 degrees Celsius cold water, then into the sewage pool (not shown in the figure) can; 50 degrees Celsius hot water into the heat exchanger 2, instead of the previous 20 degrees Celsius cold water, heated to 100 degrees Celsius steam supply production line, fully recovered after heating sludge 60 degrees Celsius hot water generated by the waste heat.

[0021] Wherein, the vacuum distillation tank 5 can be simplified as a tank, the tank is provided with an inlet for sludge into and an outlet for sludge to exclude, it internally holds the waste after metal treatment on the production line, namely the wet sludge containing about 65% water, the wet sludge is provided with the coil 51, the wet sludge entering from the inlet, using about 80 degrees Celsius waste hot water as heat source to dry the sludge, which can reduce the water content, and prepare for the next step. Thus, the waste heat of 80 degrees Celsius hot water is fully utilized to heat the wet sludge in the vacuum distillation tank, avoiding the waste heat dissipation through the cooling tower, recovering a large amount of energy, and saving the sludge treatment cost.

[0022] Referring to Figure 2 , the ejector 6 is communicated with the boiler 1, the vacuum distillation tank 5 and the hot water tank 7, the ejector is a device for using a high-speed high-energy flow to inject another low-speed low-energy flow, the present application utilizes the characteristics of the ejector to generate the distillation effect. A small part of high-pressure steam delivered from the boiler 1 directly enters the ejector 6, using the suction of the high-pressure steam, a vacuum is formed in the vacuum distillation tank 5, and the boiling point of water in the vacuum state is only about 50 degrees Celsius, which can greatly improve the evaporation intensity of water in the sludge; the high-pressure steam 2 delivered from the boiler and the steam 1 formed by the evaporation of water in the sludge discharged from the vacuum distillation tank 5 are mixed in the ejector and become low-pressure steam 3, which enters the hot water tank 7 as heat source, ensuring that the temperature of the hot water in the hot water tank is above 80 degrees Celsius. The sludge containing about 65% water is changed into dry sludge containing about 25% water after distillation and drying, which can be discharged from the outlet. Since the waste heat of 80 degrees Celsius hot water is recovered by the present technology, it provides conditions for further turning waste into treasure.

[0023] Since the vacuum distillation method is adopted, there is no heat loss caused by air, and the evaporation drying efficiency is high. Combined with the drying technology, the water content of the sludge is reduced from 65% to about 25%, the sludge volume is reduced by more than 60%, and the sludge treatment cost is greatly reduced. Since the suction of steam is used instead of the traditional electric vacuum pump, the power consumption can be reduced by 70% compared with ordinary drying technology.

[0024] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A waste heat recovery system for a metal surface treatment plant, the plant comprising a boiler, a first heat exchanger, and a production line, the waste heat recovery system including a hot water tank connected to drainage from the production line, characterized in that: The waste heat recovery system also includes a tank containing wet sludge, a coil and a water pump. The coil is located in the wet sludge inside the tank and is connected to a hot water tank. The water pump is used to draw water from the hot water tank to flow through the coil.

2. The waste heat recovery system for a metal surface treatment plant according to claim 1, characterized in that: The tank body is a sealed tank and operates under negative pressure.

3. The waste heat recovery system for a metal surface treatment plant according to claim 2, characterized in that: It also includes an ejector, which is connected to the boiler, the sealed tank and the hot water tank.

4. The waste heat recovery system for a metal surface treatment plant according to any one of claims 1 to 3, characterized in that: The invention also includes a second heat exchanger, which is in communication with the coil outlet.

5. The waste heat recovery system for a metal surface treatment plant according to claim 4, characterized in that: The second heat exchanger is in communication with the first heat exchanger.

6. The waste heat recovery system for a metal surface treatment plant according to claim 5, characterized in that: The invention also includes a sewage tank which is communicated with the outlet of the second heat exchanger.

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