Multi-effect evaporative crystallization system and method coupled with low heat source waste heat

Abstract

The invention provides a multi-effect evaporation structure system and method for coupling low heat source waste heat, and the system comprises a heat exchange tube which is vertically arranged; low-heat-source waste heat passes through the heat exchanger, and to-be-treated water flows from top to bottom along the outer wall of the heat exchanger to form a water film; the water collecting tank is arranged below the heat exchange pipe and is used for collecting the to-be-treated water flowing down from the outer wall of the heat exchange pipe; the water tank is connected with the water collecting tank and used for storing water to be treated, and the water tank, the outer wall of the heat exchange pipe and the water collecting tank form a loop; and the pump is used for pumping the to-be-treated water in the water tank to the upper end of the heat exchange pipe. According to the technical scheme, low heat source waste heat recycling is combined with a to-be-treated water concentration structure, and the effects of reducing heat waste, saving energy and reducing emission are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of low-temperature multi-effect evaporation crystallization, and in particular to a multi-effect evaporation crystallization system and method coupled with waste heat from a low heat source. Background Art

[0002] When using the reverse osmosis process to treat wastewater, the reverse osmosis membrane has a good interception effect on various organic matter and inorganic salts in the wastewater, so while producing clean water, about 25% of concentrated water will be produced. The reverse osmosis concentrated water contains various inorganic and organic pollutants with high concentrations. Increasingly high environmental protection requirements, water resource shortages, and the need for zero emissions have made it extremely important to rationally treat and resource-utilize concentrated brine. The thermal concentration method of reverse osmosis concentrated water is widely used, but it consumes a lot of heat energy. Regardless of the technology, a lot of energy consumption is required, which is also a factor restricting the development of thermal concentration. In practical applications, economic benefits must be considered, and high energy consumption will inevitably lead to a decline in economic benefits.

[0003] Therefore, there is an urgent need to provide an energy-saving multi-effect crystallization evaporation scheme. Summary of the invention

[0004] The present invention provides a multi-effect evaporation crystallization system and method coupled with waste heat from a low heat source, so as to solve the problem of high energy consumption of heat concentration in the prior art.

[0005] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0006] According to a first aspect of the present invention, there is provided a multi-effect evaporation crystallization system coupled with waste heat from a low heat source, comprising:

[0007] The heat exchange tube is arranged upright; the heat exchange tube is used for the waste heat of the low heat source to pass through it, and is also used for the water to be treated to flow from top to bottom along its outer wall to form a water film;

[0008] A water collecting tank is arranged below the heat exchange tube, and is used to collect the water to be treated flowing down from the outer wall of the heat exchange tube;

[0009] A water tank connected to the water collecting tank and used to store the water to be treated, wherein the water tank, the outer wall of the heat exchange tube and the water collecting tank form a loop;

[0010] A pump is used to pump the water to be treated in the water tank to the upper end of the heat exchange tube.

[0011] Optionally, it also includes: a water distributor, which is arranged at the upper end of the heat exchange tube; the water distributor is used to distribute the water to be treated to the outer wall of the heat exchange tube through the water distributor.

[0012] Optionally, the water distributor is a cylindrical water distributor, which is sleeved on the upper end of the heat exchange tube;

[0013] An annular gap is provided between the lower end of the water distributor and the heat exchange tube, so as to allow the water to be treated to be distributed to the outer wall of the heat exchange tube through the annular gap.

[0014] Optionally, the water distributor is an inverted cone-shaped water distributor, which is sleeved on the upper end of the heat exchange tube;

[0015] An annular gap is provided between the lower end of the water distributor and the heat exchange tube, so as to allow the water to be treated to be distributed to the outer wall of the heat exchange tube through the annular gap.

[0016] Optionally, the water distributor is an inverted cone-shaped water distributor, which is sleeved on the upper end of the heat exchange tube;

[0017] The water distributor is used to allow the water to be treated to overflow through its upper end, and then flow from top to bottom along its outer wall to the outer wall of the heat exchange tube.

[0018] Optionally, the inner wall of the water distributor is provided with a water-absorbing layer;

[0019] The inner wall of the water distributor is provided with at least one layer of grid structure.

[0020] Optionally, the waste heat from the low heat source passes through the heat exchange tube from bottom to top.

[0021] Optionally, it also includes: ventilation equipment for renewing the air around the heat exchange tube.

[0022] Optionally, the heat exchange tube is a vertical light tube;

[0023] The outer wall of the heat exchange tube is provided with a hydrophilic coating.

[0024] Optionally, there are multiple heat exchange tubes.

[0025] Optionally, it also includes: a low heat source waste heat collection device; a loop is formed between the low heat source waste heat collection device and the heat exchange tube.

[0026] According to a second aspect of the present invention, there is provided a multi-effect evaporation crystallization method coupled with waste heat from a low heat source, comprising:

[0027] The waste heat from the low heat source passes through the heat exchange tubes;

[0028] The water to be treated forms a water film on the outer wall of the heat exchange tube.

[0029] The multi-effect evaporation crystallization system and method coupled with low heat source waste heat provided by the present invention transfers heat by passing low heat source waste heat through the heat exchange tubes, and forms a water film on the outer wall for evaporation and crystallization, thereby combining waste heat recovery and concentration crystallization, realizing the recovery and utilization of low heat source waste heat resources of different types in different units, giving full play to the potential of low heat sources, not only saving energy consumption for heat concentration, but also reducing the emission of low-temperature waste heat, achieving the effect of energy saving and emission reduction; in addition, by laying a film on the outside of the heat exchange tubes, heat transfer is effectively enhanced, heat utilization rate is high, and crystallization effect is good.

[0030] In an optional solution of the present invention, the water to be treated is distributed to the outer wall of the heat exchange tube by a water distributor, the water film is relatively uniform, and the phenomenon of dry tubes in some positions of the tubes is avoided, thereby effectively maintaining the heat transfer area.

[0031] In an optional solution of the present invention, the transmission direction of the waste heat of the low heat source in the heat exchange tube is from bottom to top, which is opposite to the flow direction of the water to be treated on the outer wall of the heat exchange tube, and the heat exchange effect is better.

[0032] In an optional scheme of the present invention, the air around the heat exchange tube is renewed by ventilation equipment, so that the air with relatively saturated humidity can be extracted in time, ensuring that the relatively dry air around it sweeps over the surface of the water film, which can take away more moisture, enhance the evaporation effect of the water film, and improve the crystallization rate; and ventilation can increase the irregular movement of water molecules, so that the mass transfer surface between the water film and the air is continuously renewed, reducing the mass transfer film thickness and membrane resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0034] Figure 1 A schematic diagram of a multi-effect evaporation crystallization system coupled with waste heat from a low heat source according to an embodiment of the present invention;

[0035] Figure 2 A schematic diagram of a multiple-effect evaporation crystallization system coupled with waste heat from a low heat source according to a preferred embodiment of the present invention;

[0036] Figure 3 A schematic diagram of a water distributor of a multiple-effect evaporation crystallization system coupled with waste heat from a low heat source according to another preferred embodiment of the present invention;

[0037] Figure 4 A schematic diagram of a water distributor of a multiple-effect evaporation crystallization system coupled with waste heat from a low heat source according to another preferred embodiment of the present invention;

[0038] Figure 5 A flow chart of a multi-effect evaporation crystallization method coupled with waste heat from a low heat source according to an embodiment of the present invention;

[0039] Description of reference numerals:

[0040] 1-Heat exchange tube;

[0041] 2-collection pool;

[0042] 3- Water tank;

[0043] 4- Pump;

[0044] 5- Water film;

[0045] 6- Water distributor. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] In the description of the specification of the present invention, it is necessary to understand that the orientation or position relationship indicated by the terms "upper part", "lower part", "upper end", "lower end", "lower surface", "upper surface", etc. is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0048] In the description of the present specification, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0049] In the description of the present invention, "plurality" means a plurality, such as two, three, four, etc., unless otherwise clearly and specifically defined.

[0050] In the description of the present invention, unless otherwise clearly specified and limited, the term "connection" and other terms should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] The technical solution of the present invention is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0052] Energy conservation and emission reduction mainly rely on the industrial field, and the utilization of industrial waste heat is an important part. According to statistics, about 50% of my country's industrial energy consumption comes from direct waste heat in various forms. Especially in the energy industry, the waste heat utilization rate is very low, and there will be a large amount of waste heat loss. This part of the wasted energy has huge room for utilization. Waste resources with high waste heat and large residual pressure capacity are relatively convenient to use. Existing technologies can achieve their recycling and utilization in a relatively economical and limited manner. However, there is no mature and economical utilization method for some waste heat with smaller heat. Using this part of waste heat for thermal concentration of reverse osmosis concentrated water is a "killing two birds with one stone" solution.

[0053] In view of this, the present invention provides a multi-effect evaporation crystallization system coupled with low heat source waste heat, which includes: a heat exchange tube 1, a water collection tank 2, a water tank 3, and a pump 4. Please refer to Figure 1 . Among them, the heat exchange tube 1 is arranged upright, which is used for the waste heat of the low heat source to pass through it, and is also used for the water to be treated to flow from top to bottom along its outer wall to form a water film 5 (the dotted arrow in the figure shows the flow direction of the water to be treated). The collecting tank 2 is arranged below the heat exchange tube 1, and is used to collect the water to be treated flowing down from the outer wall of the heat exchange tube 1. The water tank 3 is connected to the collecting tank 2, and is used to store the water to be treated. A loop is formed between the water tank, the outer wall of the heat exchange tube, and the collecting tank, so that repeated treatment of the water to be treated can be achieved. A pump is used to pump the water to be treated in the water tank 3 to the upper end of the heat exchange tube 1.

[0054] The working principle of the multi-effect evaporation crystallization system is: the waste heat from the low heat source passes through the heat exchange tube to transfer heat, forming a water film on the outer wall of the heat exchange tube to absorb heat and evaporate and crystallize, completing the treatment of the water to be treated. This process can be repeated many times until the desired concentration is reached.

[0055] The water to be treated may be reverse osmosis concentrated water.

[0056] In one embodiment, the waste heat from the low heat source passes through the heat exchange tube from bottom to top, such as Figure 1The solid arrow in the middle shows the flow direction of the low heat source waste heat. The flow direction of the low heat source waste heat is opposite to the flow direction of the water to be treated, and the heat exchange effect is better.

[0057] In one embodiment, the pump can also adjust the flow rate of the treated water according to the film distribution conditions, such as: when the water film is relatively thin or there is a dry pipe phenomenon in part of the heat exchange tube, the flow rate of the treated water is increased; when the water film is relatively thick, the flow rate of the treated water is reduced.

[0058] In one embodiment, the multi-effect evaporation crystallization system further includes: a water distributor 6, please refer to Figure 2 The water distributor 6 is disposed at the upper end of the heat exchange tube 1 to distribute the water to be treated to the outer wall of the heat exchange tube through the water distributor.

[0059] Practically, the water distributor is an annular water distributor, which can make the water film around the outer wall of the heat exchange tube more uniform, so that the outer wall of the heat exchange tube is fully utilized and the heat transfer area is effectively increased.

[0060] As an implementation method, the water distributor may be a cylindrical water distributor, please refer to Figure 3 There is an annular gap between the lower end of the cylindrical water distributor and the heat exchange tube, which is used to distribute the water to be treated to the outer wall of the heat exchange tube through the annular gap.

[0061] As another embodiment, the water distributor can be an inverted cone water distributor, please refer to Figure 4 The water to be treated can be distributed to the outer wall of the heat exchange tube through the lower end of the inverted cone water distributor. Specifically, there is an annular gap between the lower end of the inverted cone water distributor and the heat exchange tube, and the water to be treated is distributed to the outer wall of the heat exchange tube through the annular gap. The water to be treated can also overflow from the upper end of the inverted cone water distributor, and then flow along the outer wall of the inverted cone water distributor from top to bottom to the outer wall of the heat exchange tube. At this time, there is no need for a gap between the lower end of the inverted cone water distributor and the heat exchange tube.

[0062] In a preferred embodiment, a water-absorbing layer may be provided on the inner wall of the water distributor to reduce uneven water distribution in the water distributor.

[0063] In a preferred embodiment, the inner wall of the water distributor may be provided with at least one layer of grid structure, which can disperse the water flow into fine water droplets of different particles, avoid the water flow from being concentrated, and achieve a better evaporation and crystallization effect.

[0064] In one embodiment, the multi-effect evaporation crystallization system further includes: ventilation equipment for updating the air around the heat exchange tube. The air with relatively high humidity is extracted in time to ensure that the relatively dry air sweeps the surface of the water film, which can take away more moisture and improve the evaporation crystallization rate; in addition, ventilation can increase the irregular movement of water molecules, so that the mass transfer surface between the water film and the air is continuously updated, the mass transfer film thickness and membrane resistance are reduced, and the evaporation crystallization effect is better.

[0065] In one embodiment, the ventilation equipment can also automatically adjust the ventilation volume according to different weather changes and temperature changes to achieve faster and more efficient evaporation and crystallization.

[0066] In one embodiment, the multi-effect evaporation crystallization system further includes: a low heat source waste heat collection device, which collects the low heat source waste heat of a single system or multiple systems and outputs it to the heat exchange tube; the multiple systems can be different types of systems of different units.

[0067] Preferably, a loop is formed between the low-heat source waste heat collection device and the heat exchange tube, so that the low-heat source waste heat after heat transfer is not directly discharged but recycled, which has a better energy-saving and emission reduction effect.

[0068] In different embodiments, the low heat source waste heat may not be collected by the low heat source waste heat collection device, and the low heat source waste heat device may directly transmit the energy to the heat exchange tube. The low heat source waste heat may not be reused, and may be discharged after being used once.

[0069] It can be implemented that the low heat source waste heat device may include: circulating cooling water of the gas turbine, cooling water in the condenser, etc.

[0070] In one embodiment, the heat exchange tube may be a vertical light tube, which makes it more convenient and simple to form a water film, and the water film effect is also better.

[0071] In a preferred embodiment, a hydrophilic coating may be provided on the outer wall of the heat exchange tube, so that the expansion area of ​​the water film is larger and the adhesion is stronger, thereby increasing the residence time of the water film, improving the evaporation amount, and achieving higher evaporation concentration efficiency.

[0072] In one embodiment, there may be multiple heat exchange tubes, and the multiple heat exchange tubes can exchange heat and crystallize at the same time, thereby improving the processing efficiency.

[0073] It is feasible that multiple heat exchange tubes can be grouped in pairs, please refer to Figure 1 Of course, in different embodiments, it is not limited to this, and there may be no grouping, or a group may include three or more.

[0074] In one embodiment, the heat exchange tube can be a stainless steel heat exchange tube, which has good corrosion resistance and good heat conduction effect.

[0075] Preferably, the connecting pipe between the water collection pool and the water tank can be arranged at the bottom of the water collection pool, and the collection of the water to be treated in the water collection pool can be automatically completed without the need for a power system, so that the system is simpler and more energy-efficient.

[0076] In a preferred embodiment, the connecting pipeline between the water collection pool and the water tank, as well as the pumping pipeline can be made of stainless steel or steel-based materials, which have better corrosion resistance.

[0077] In a preferred embodiment, a dissolved oxygen reducing device may be provided to reduce the dissolved oxygen content in the connecting pipes between the water collection pool and the water tank, as well as in the water in the pumping pipes, thereby reducing scaling on the inner walls of the pipes.

[0078] In a preferred embodiment, a corrosion inhibitor may be added to the water to be treated to reduce scaling on the inner wall of the pipeline.

[0079] In one embodiment, a multi-effect evaporation crystallization method coupled with waste heat from a low heat source is provided. Figure 5 , which includes:

[0080] S11: The waste heat from the low heat source passes through the heat exchange tube for heat transfer;

[0081] S12: The water to be treated forms a water film on the outer wall of the heat exchange tube, and the water film absorbs heat to evaporate and crystallize.

[0082] In one embodiment, S12 specifically includes: using a water distributor to uniformly form a water film on the outer wall of the heat exchange tube with the water to be treated.

[0083] In one embodiment, the multi-effect evaporation crystallization method further includes: timely updating the relatively saturated air around the heat exchange tubes.

[0084] Practically, the air around the heat exchange tubes can be updated regularly, and the air humidity around the heat exchange tubes can also be collected. When the humidity reaches a preset value, the air is updated.

[0085] In the description of this specification, the description with reference to the terms "an implementation", "an example", "a specific implementation process", "an example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-effect evaporation crystallization system coupled with waste heat from a low heat source, characterized in that: include: The heat exchange tube is arranged upright; the heat exchange tube is used for the waste heat of the low heat source to pass through it, and is also used for the water to be treated to flow from top to bottom along its outer wall to form a water film; A water collecting tank is arranged below the heat exchange tube, and is used to collect the water to be treated flowing down from the outer wall of the heat exchange tube; A water tank connected to the water collecting tank and used to store the water to be treated, wherein the water tank, the outer wall of the heat exchange tube and the water collecting tank form a loop; A pump is used to pump the water to be treated in the water tank to the upper end of the heat exchange tube.

2. The multi-effect evaporation crystallization system coupled with low heat source waste heat according to claim 1 is characterized in that: Also includes: A water distributor is arranged at the upper end of the heat exchange tube; the water distributor is used to distribute the water to be treated to the outer wall of the heat exchange tube through the water distributor.

3. The multi-effect evaporation crystallization system coupled with low heat source waste heat according to claim 2 is characterized in that: The water distributor is a cylindrical water distributor, which is sleeved on the upper end of the heat exchange tube; An annular gap is provided between the lower end of the water distributor and the heat exchange tube, so as to allow the water to be treated to be distributed to the outer wall of the heat exchange tube through the annular gap.

4. The multi-effect evaporation crystallization system coupled with low heat source waste heat according to claim 2, characterized in that: The water distributor is an inverted cone-shaped water distributor, which is sleeved on the upper end of the heat exchange tube; There is an annular gap between the lower end of the water distributor and the heat exchange tube, so that the water to be treated is distributed to the outer wall of the heat exchange tube through the annular gap; or, The water distributor is used to allow the water to be treated to overflow through its upper end, and then flow from top to bottom along its outer wall to the outer wall of the heat exchange tube.

5. The multi-effect evaporation crystallization system coupled with low heat source waste heat according to claim 2, characterized in that: The inner wall of the water distributor is provided with a water-absorbing layer; The inner wall of the water distributor is provided with at least one layer of grid structure.

6. The multi-effect evaporation crystallization system coupled with low heat source waste heat according to claim 1, characterized in that: The waste heat from the low heat source passes through the heat exchange tube from bottom to top.

7. The multi-effect evaporation crystallization system coupled with low heat source waste heat according to claim 1, characterized in that: Also includes: The ventilation equipment is used to renew the air around the heat exchange tube.

8. The multi-effect evaporation crystallization system coupled with low heat source waste heat according to claim 1, characterized in that: The heat exchange tube is a vertical light tube; The outer wall of the heat exchange tube is provided with a hydrophilic coating.

9. The multi-effect evaporation crystallization system coupled with waste heat from a low heat source according to any one of claims 1 to 8, characterized in that: Also includes: A low heat source waste heat collection device; a loop is formed between the low heat source waste heat collection device and the heat exchange tube.

10. A multi-effect evaporation crystallization method coupled with waste heat from a low heat source, characterized in that: include: The waste heat from the low heat source passes through the heat exchange tubes; The water to be treated forms a water film on the outer wall of the heat exchange tube.

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