Low-temperature evaporation treatment system for DTRO concentrated solution

Abstract

The invention discloses a DTRO concentrated solution low-temperature evaporation treatment system which comprises a hardness removal unit (a dosing tank), a solid-liquid separation unit (a sedimentation tank and a filter press), a gas-liquid separation unit (an evaporation tower), two-stage condensation units (a first condensation tower and a second condensation tower), heat exchange units (a first heat exchanger and a second heat exchanger) and a concentrated solution collection unit. Raw water enters the solid-liquid separation unit after being treated by the hardness removal unit, separated feed water enters the solid-liquid separation unit, and suspension liquid enters the filter pressing equipment; steam of the gas-liquid separation unit enters the secondary condensation unit, circulating water flows back after passing through the heat exchange unit, and concentrated liquid enters the collection unit; and outlet water of the second-stage condensation unit is circulated after heat exchange, so that heat recovery and condensation are realized. The system is high in adaptability, anti-scaling and stable in operation; waste heat is used as a heat source, two-stage heat exchange step energy is used, and energy conservation and high efficiency are achieved; and the heat exchanger prevents cross contamination, and is safe and easy to maintain.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection, and in particular to a low-temperature evaporation treatment system for DTRO concentrate, and in particular to a system for low-temperature and normal-pressure evaporation and concentration treatment of DTRO concentrate in a waste power plant by utilizing waste heat from boiler cooling water. Background Art

[0002] The highly concentrated wastewater produced by deep treatment of landfill leachate with DTRO membranes is complex, salt-rich, and exhibits significant fluctuations in properties, posing significant challenges to direct treatment. Conventional evaporation treatment relies heavily on steam or thermal oil as a heat source, resulting in high energy consumption and high treatment costs. Furthermore, the process is prone to instability due to fluctuations in the wastewater's properties. Furthermore, waste-to-energy plants generate large amounts of boiler cooling water at temperatures between 80 and 95°C during power generation. This water, which possesses a significant amount of thermal energy, often remains unused and unused, resulting in a waste of valuable energy and contradicting the principle of energy conservation and consumption reduction.

[0003] Patent CN101417209B relates to a vacuum membrane distillation (VMD) device and method capable of effective heat recovery. The device comprises a membrane distillation system, a heat recovery system, heating equipment, a pressure-reducing device, a liquid circulation system, a pretreatment system, and system control and monitoring. The membrane components of this invention are prone to scaling due to the characteristics of the feed liquid, requiring frequent treatment; they rely on specific membrane materials, resulting in high costs; and their efficiency is reduced when treating high-viscosity feed liquids.

[0004] Patent CN101209881B relates to a method and system for treating leachate from a waste incineration plant. The method involves adding a coagulant to the leachate for coagulation and sedimentation pretreatment to remove suspended matter; subjecting the pretreated leachate to evaporation and concentration to obtain condensed water, removing pollutant residues and residual liquid; subjecting the condensed water to ammonia stripping treatment to remove ammonia nitrogen; and post-treating the ammonia stripping water to environmental emission standards. The system comprises a pretreatment system, an evaporation and concentration system, an ammonia stripping system, and a post-treatment system, all connected in sequence. The evaporation and concentration process in this invention is prone to scaling, which affects the equipment lifespan; the ammonia stripping process requires strict temperature and pH control, making the operation complex; and the post-treatment process has limited removal of certain difficult-to-degrade substances. Summary of the Invention

[0005] In response to the shortcomings of the aforementioned prior art, the present invention aims to provide a low-temperature evaporation system for DTRO concentrate. Specifically, it is a highly efficient, energy-efficient, and adaptable low-temperature, atmospheric-pressure evaporation system. This system utilizes boiler cooling water as a heat source while recovering waste heat from the condensation tower, achieving cascaded energy utilization and resolving the challenges of DTRO concentrate treatment. The present invention also provides a method for treating highly concentrated wastewater produced by deep DTRO membrane treatment of landfill leachate, which improves the stability and efficiency of treating wastewater with complex components, achieving energy recycling and low-cost treatment.

[0006] The technical solution of the present invention provides a DTRO concentrate low-temperature evaporation treatment system, the system comprising: Remove hard units; Solid-liquid separation unit, including sedimentation equipment and filter press equipment; Gas-liquid separation unit; Secondary condensing unit: includes a first condensing device and a second condensing device; Heat exchange unit: includes a first heat exchange device and a second heat exchange device; Evaporation concentrate collection unit.

[0007] The connection relationship between the units is as follows: The inlet of the hardness removal unit is connected to the raw water, and the effluent after hardness removal treatment is connected to the solid-liquid separation unit for sedimentation separation; the feed water separated by the solid-liquid separation unit is transported to the gas-liquid separation unit, and the separated suspension enters the filter press equipment in the unit for treatment; the steam generated by the gas-liquid separation unit is passed into the secondary condensation unit, and its circulating water first enters the heat exchange unit to complete heat exchange and then flows back to itself, and the concentrated liquid is sent to the evaporation concentrated liquid collection unit; in the secondary condensation unit, the effluent of the first condensation equipment is connected to the heat exchange unit, and enters the second condensation equipment after heat exchange, and part of the effluent of the second condensation equipment flows back to the first condensation equipment to form a cycle, realizing heat recovery and steam condensation.

[0008] Furthermore, each unit includes the following components: Hardness removal unit: dosing tank; Solid-liquid separation unit: the sedimentation equipment is a sedimentation tank, and the filter pressing equipment is a filter press; Gas-liquid separation unit: evaporation tower; Secondary condensing unit: the first condensing equipment is the first condensing tower, and the second condensing equipment is the second condensing tower; Heat exchange unit: the first heat exchange device is a first heat exchanger, and the second heat exchange device is a second heat exchanger; Evaporation concentrate collection unit: concentrate tank.

[0009] Furthermore, the dosing tank is provided with a dosing tank inlet and a dosing tank outlet. The sedimentation tank is provided with a sedimentation tank inlet, a sedimentation tank liquid outlet, and a sedimentation tank sediment outlet. The evaporation tower is provided with a pretreated water inlet, an evaporation circulating water outlet, a concentrate outlet, a heating water inlet, and a first steam outlet. The first condensation tower is provided with a first steam inlet, a first recycled water outlet, a first recycled water inlet, and a second steam outlet. The second condensation tower is provided with a second steam inlet, a second recycled water outlet, a second recycled water inlet, an exhaust gas outlet, and an evaporation water outlet.

[0010] Furthermore, the inlet of the dosing tank is connected to the raw water through a pipeline, and the raw water is pretreated in the dosing tank to obtain pretreated water; the pretreated water flows out from the outlet of the dosing tank, and the outlet of the dosing tank is connected to the inlet of the sedimentation tank through a pipeline. The raw water is DTRO concentrate; the pretreatment is to remove the scaling ions Ca 2+ Mg 2+ .

[0011] Furthermore, the pretreated water is subjected to sedimentation treatment in a sedimentation tank to obtain feed water and suspension; Furthermore, the feed water leaves the liquid outlet of the sedimentation tank and is transported to the pretreatment water inlet through a pipeline. The pretreatment water inlet is arranged at the bottom of the evaporation tower. After a certain amount of water is stored in the tower body, the excess part is pumped into the first heat exchanger through the evaporation circulating water outlet through the pump body, and the recycled water flowing out of the first condensation tower and the second condensation tower is heated, and then passes through the second heat exchanger and is heated again by the heat source. After heating is completed, it flows back to the heating water inlet.

[0012] Furthermore, the suspension is discharged into the filter press through the sedimentation outlet of the sedimentation tank via a pipeline. Under the action of pressure, the liquid passes through the filter cloth (for example, in a plate and frame filter press, it enters the filter plate groove and is then discharged through the liquid outlet) to form a filtrate; the solid particles are retained by the filter cloth and gradually accumulate in the filter frame to form a filter cake; when the filter frame is full of filter cake, the filter plate and filter frame are loosened, and the filter cake is taken out, completing a filtration cycle.

[0013] Furthermore, a fan (F) is provided in the evaporation tower, and the fan (F) blows away a portion of the steam, which leaves the evaporation tower from the steam outlet and flows to the first steam inlet through the pipeline.

[0014] Furthermore, in the first condensing tower, steam fully contacts the packing layer with cold water that enters the tower top through the first recycled water inlet and is sprayed down. The steam releases heat and is discharged from the steam outlet at the top of the tower. The heated water collects at the bottom of the tower and flows out of the first recycled water outlet as recycled water. This recycled water is connected to the second heat exchange channel of the first heat exchanger via a pipeline, where it heats the feed water in the first heat exchange channel. After heat exchange, the recycled water flows to the second recycled water inlet.

[0015] Furthermore, the steam leaving the steam outlet flows to the second steam inlet through the pipeline, and after releasing the heat, it is discharged from the tail gas outlet on the top of the tower. A part of the heated water is collected at the bottom of the tower and flows from the second recycled water outlet to the first recycled water inlet through the pipeline, and the remaining heated water is discharged through the evaporation water outlet (for example, discharged to the biochemical treatment pool for further treatment and then discharged).

[0016] Furthermore, pumps (P) are respectively provided on the pipeline from the sedimentation tank liquid outlet to the pretreatment water inlet, the pipeline from the concentrate outlet to the concentrate tank, the pipeline from the evaporation circulating water outlet to the first heat exchanger, the pipeline from the first recycled water outlet to the first heat exchanger, the pipeline from the second recycled water outlet to the first recycled water inlet, and the pipeline for the evaporation water outlet.

[0017] Furthermore, the pump (P) is selected from a centrifugal pump or a screw pump; the centrifugal pump is suitable for ordinary and conventional processing processes; the high viscosity concentrate can be replaced by a screw pump.

[0018] Furthermore, the pipeline material is selected from PP or 304 stainless steel. For high-salt, highly corrosive concentrates, it can be replaced with 316L stainless steel piping, FRP (glass reinforced plastic) piping, or PTFE (polytetrafluoroethylene) lined piping to improve corrosion resistance.

[0019] Furthermore, as the water vapor in the evaporation tower gradually evaporates, the concentration of the liquid in the tower becomes higher and higher. When the liquid reaches saturation, the concentrate outlet at the bottom of the tower is opened and the concentrate is discharged to the concentrate tank through a pump (P) and pipeline.

[0020] Furthermore, the evaporation tower is selected from any one of an atmospheric-pressure forced-air evaporation tower, a reduced-pressure evaporation tower, or a plate-type evaporation tower. The atmospheric-pressure forced-air evaporation tower has the advantages of a simple structure, convenient operation and maintenance, and is suitable for low-energy consumption scenarios (it can utilize waste heat for heating). It also offers high safety during atmospheric-pressure operation and lower requirements for equipment materials. The reduced-pressure evaporation tower lowers the boiling point of water under negative pressure, making it suitable for low-temperature heat source scenarios and achieving greater energy savings. The plate-type evaporation tower has a compact design and is suitable for installation in small spaces.

[0021] Furthermore, the first condensation tower and the second condensation tower are selected from any one of a packed condensation tower, a shell-and-tube condenser, or an evaporative condenser. Advantages of the packed condensation tower include a large gas-liquid contact area, high condensation efficiency, a compact structure, low pressure drop, high operational flexibility, and easy maintenance, making it suitable for a variety of operating conditions. Shell-and-tube condensers are suitable for high steam volume scenarios and offer higher condensation efficiency. Evaporative condensers utilize the latent heat of evaporation between air and water for cooling, reducing cooling water usage.

[0022] Furthermore, the first and second heat exchangers are selected from either a plate heat exchanger or a tubular heat exchanger. The plate heat exchanger offers high heat transfer efficiency, a compact structure, easy disassembly and cleaning, and strong adaptability, making it suitable for heat exchange with low- to medium-volume, low-viscosity fluids. The tubular heat exchanger is resistant to high pressure and high temperature, has a large processing capacity, is suitable for high-viscosity / particulate-laden fluids, has a stable structure, and offers low maintenance costs.

[0023] Furthermore, the filter press is selected from either a plate and frame filter press or a belt filter press. The advantages of the plate and frame filter press include high filtration precision, deep dehydration capabilities, strong adaptability, ability to process high-concentration sludge, low filter cake moisture content, and stable and reliable operation. The belt filter press operates continuously and is suitable for large-scale sludge treatment. The filter press can also be replaced with a screw press or a vacuum filter. The screw press occupies a small footprint and is suitable for low-concentration sludge. The vacuum filter is suitable for viscous sludge and has a high degree of automation.

[0024] Furthermore, the heat source of the second heat exchanger is selected from any one of: boiler cooling water of a waste incineration plant (80~95℃), a solar collector (suitable for areas with sufficient sunlight to reduce energy consumption), industrial waste heat steam (such as low-pressure steam discharged from other equipment in the factory) or an air source heat pump (suitable for scenarios with a lack of waste heat and high flexibility); preferably, boiler cooling water of a waste incineration plant.

[0025] The technical solution of the present invention further provides an application of the above-mentioned DTRO concentrate low-temperature evaporation treatment system. In such an application, the raw water hardness is approximately 2000-2800 mg / L, the influent conductivity is approximately 27000-76000 μS / cm, and the influent ammonia nitrogen is approximately 9-94 mg / L.

[0026] Compared with the prior art, the present invention has at least the following improvements and beneficial effects: (1) Strong adaptability: It has good processing ability for high hardness and high volatility DTRO concentrate, strong anti-scaling performance and stable operation; (2) Energy saving and high efficiency: waste heat boiler cooling water or secondary heat in other factories is used as heat source to reduce energy consumption and operating costs; (3) Energy cascade utilization: Through the two-stage heat exchange system, the condensed water is first used for preheating, and then the boiler cooling water is used for further heating, maximizing the thermal energy utilization efficiency; (4) System safety: operating at normal pressure and low temperature, no high-pressure steam system, simple structure and easy maintenance; (5) All heat exchange processes in the system use high-efficiency heat exchangers to ensure that the heat source and the heated medium are not in direct contact to avoid cross contamination. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A process flow chart provided by the present invention; Figure 2 A diagram of the device provided by the present invention; Reference numerals: 1 dosing tank, 1-1 dosing tank inlet, 1-2 dosing tank outlet; 2 sedimentation tanks, 2-1 sedimentation tank inlet, 2-2 sedimentation tank liquid outlet, 2-3 sedimentation tank sedimentation outlet; 3 evaporation tower, 3-1 pre-treated water inlet, 3-2 evaporation circulating water outlet, 3-3 concentrate outlet, 3-4 heating water inlet, 3-5 first steam outlet; 4 first condensing tower, 4-1 first steam inlet, 4-2 first recycled water outlet, 4-3 first recycled water inlet, 4-4 second steam outlet; 5 second condensing tower, 5-1 second steam inlet, 5-2 second recycled water outlet, 5-3 second recycled water inlet, 5-4 tail gas discharge outlet, 5-5 evaporated water outlet; 6. First heat exchanger, 7. Second heat exchanger, 8. Filter press; 9. Concentrate tank. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below with reference to specific embodiments. It should be noted that the following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0029] Unless otherwise specified, all raw materials in the present invention are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

[0030] Example 1 A DTRO concentrate low-temperature evaporation treatment system like Figure 1 Flowchart and Figure 2 As shown in the device diagram, this embodiment provides a DTRO concentrate low-temperature evaporation treatment system, which includes: a dosing tank 1, an inclined tube sedimentation tank 2, an evaporation tower 3, a first condensation tower 4, a second condensation tower 5, a first heat exchanger 6, a second heat exchanger 7, a plate and frame filter press 8, and a concentrate tank 9.

[0031] The dosing tank 1 serves as an integrated hardness removal unit to pre-treat the DTRO concentrate. The evaporation tower 3 serves as a gas-liquid separation unit, spraying the heated liquid through a top water distributor to form droplets, which are then blown off by air at normal pressure to separate the water vapor and carry the water into the condensation tower. The first condensation tower 4 and the second condensation tower 5 form a secondary condensation unit to cool and recover the evaporated water vapor, and the condensed water enters the biochemical treatment system. The first heat exchanger 6 and the second heat exchanger 7 serve as heat exchange units, respectively using the heat of the condensed water in the secondary condensation unit and the heat of the boiler cooling water to perform primary preheating (to 40-50°C) and secondary preheating (to 75-80°C) of the feed water. The inclined tube sedimentation tank 2 and the plate and frame filter press 8 constitute a solid-liquid separation unit, and the precipitated sludge is filtered by the plate and frame filter press 8 into a mud cake for external transportation. The concentrated liquid tank 9 serves as a collection unit for the evaporated concentrated liquid, and the concentrated liquid can be directly fed into the boiler of the waste incineration plant for combustion. Evaporation and concentration not only reduces the incineration processing capacity, but also increases the calorific value of the mother liquor, thereby reducing energy consumption.

[0032] The dosing tank 1 is provided with a dosing tank inlet 1-1 and a dosing tank outlet 1-2. The inclined tube sedimentation tank 2 is provided with an inclined tube sedimentation tank inlet 2-1, an inclined tube sedimentation tank liquid outlet 2-2 and an inclined tube sedimentation tank sedimentation outlet 2-3. The evaporation tower 3 is provided with a pre-treated water inlet 3-1, an evaporation circulating water outlet 3-2, a concentrate outlet 3-3, a heating water inlet 3-4 and a first steam outlet 3-5. The first condensation tower 4 is provided with a first steam inlet 4-1, a first recycled water outlet 4-2, a first recycled water inlet 4-3 and a second steam outlet 4-4. The second condensation tower 5 is provided with a second steam inlet 5-1, a second recycled water outlet 5-2, a second recycled water inlet 5-3, an exhaust gas discharge outlet 5-4 and an evaporation water outlet 5-5.

[0033] The inlet of the dosing tank 1-1 is connected to the raw water through a pipeline. The raw water is DTRO concentrate. The raw water is pretreated in the dosing tank 1 to remove the scaling ions Ca 2+ Mg 2+ , obtaining pretreated water; the pretreated water flows out from the dosing tank outlet 1-2, the dosing tank outlet 1-2 is connected to the inclined tube sedimentation tank inlet 2-1 through a pipeline.

[0034] After pretreated water undergoes sedimentation in inclined tube sedimentation tank 2, feed water and a suspension are obtained. The suspension is discharged through the inclined tube sedimentation tank's sedimentation outlet 2-3 via a pipeline to a plate and frame filter press 8. Under pressure, the liquid passes through the filter cloth and enters the grooves of the filter plates, then exits through the liquid outlet to form filtrate. Solid particles are trapped by the filter cloth and gradually accumulate in the filter frame to form a filter cake. When the filter frame is full of filter cake, the filter plates and filter frame are loosened and the filter cake is removed, completing one filtration cycle.

[0035] The feed water exits the inclined tube sedimentation tank's liquid outlet 2-2 and is piped to the pre-treated water inlet 3-1, located at the bottom of the evaporation tower 3. After a certain amount of water is stored in the tower, the excess is pumped through the evaporation circulating water outlet 3-2 and pumped into the first heat exchanger 6. The recycled water flowing out of the first and second condensation towers 4 and 5 is then heated. The recycled water then passes through the second heat exchanger 7 and is further heated by the waste incineration plant's boiler cooling water. After heating, the recycled water flows back to the heating water inlet 3-4. A fan F is installed in the evaporation tower 3 to remove some of the steam, which then leaves the evaporation tower 3 through the steam outlet 3-5 and flows through a pipeline to the first steam inlet 4-1. As the water vapor in the evaporation tower 3 gradually evaporates, the concentration of the liquid in the tower increases. When the liquid reaches saturation, the concentrate outlet 3-3 at the bottom of the tower is opened, and the concentrate is discharged to the concentrate tank 9 via a pump P and pipelines.

[0036] In first condensing tower 4, steam fully contacts the packing layer with cold water that enters the tower top through first recycled water inlet 4-3 and is sprayed down. The steam releases heat and is discharged through steam outlet 4-4 at the top of the tower. The heated water collects at the bottom of the tower and flows out of first recycled water outlet 4-2 as recycled water. This recycled water is piped to the second heat exchange channel of first heat exchanger 6, where it heats the feed water in the first heat exchange channel. After heat exchange, the recycled water flows to second recycled water inlet 5-3.

[0037] Steam exiting steam outlet 4-4 flows through a pipeline to second steam inlet 5-1. The steam is treated in second condensation tower 5 in a manner similar to that in first condensation tower 4. A portion of the heated water collects at the bottom of the tower and flows through second recycled water outlet 5-2 through a pipeline to first recycled water inlet 4-3. The remaining heated water is discharged through evaporation water outlet 5-5 (for example, to a biochemical treatment tank for further treatment before discharge). The cooled steam is discharged through exhaust outlet 5-4.

[0038] In the second heat exchanger 7, the first heat exchange channel is filled with feed water, and the second heat exchange channel is filled with external hot water (boiler cooling water), which is intended to further heat the feed water after the first heating.

[0039] In addition, pumps P are respectively provided on the pipeline from the liquid outlet 2-2 of the inclined tube sedimentation tank to the pretreated water inlet 3-1, the pipeline from the concentrated liquid outlet 3-3 to the concentrated liquid tank 9, the pipeline from the evaporation circulating water outlet 3-2 to the first heat exchanger 6, the pipeline from the first recycled water outlet 4-2 to the first heat exchanger 6, the pipeline from the second recycled water outlet 5-2 to the first recycled water inlet 4-3, and the pipeline discharged from the evaporation water outlet 5-5.

[0040] Principle of the core device: Evaporation tower 3 utilizes forced air convection to vaporize and separate the solvent in the solution, achieving solution concentration or solute crystallization. The solution to be treated is heated to a high temperature by a heat exchanger and then fed into heated water inlets 3-4 at the top of the evaporation tower via a feed pump P. The solution is then evenly sprayed onto heat transfer surfaces within the tower (such as the evaporation tube bundle and packing layer) via a distributor. This increases the contact area between the solution and the heat source, creating convection with the air from the blower, removing moisture from the spray liquid and achieving evaporation. As the solvent continues to vaporize, the solute concentration in the solution at the bottom of the tower gradually increases, reaching a predetermined concentration before being discharged as concentrated liquid.

[0041] Example 2: Method / Process of Using the Device This embodiment, based on the treatment system described in Example 1, provides a low-temperature evaporation treatment method for DTRO concentrate using boiler cooling water as a heat source. The specific steps are as follows: S1. Pretreatment to remove hardness The DTRO concentrate (raw water) is transported to the dosing tank inlet 1-1 of the dosing tank 1 through a pipeline, and a hardness removal agent (such as caustic soda / soda ash and flocculant, etc.) is added to the dosing tank to remove Ca in the concentrate. 2+ Mg 2+ The scaling ions are removed to form precipitates and flocs, and pretreated water is obtained. The pretreated water is discharged from the dosing tank outlet 1-2 and enters the inclined tube sedimentation tank 2.

[0042] S2. Solid-liquid separation The pretreated water enters the inclined tube sedimentation tank 2 through the inclined tube sedimentation tank inlet 2-1, completes sedimentation separation under the action of gravity, and the upper clear liquid is discharged from the inclined tube sedimentation tank liquid outlet 2-2 as feed water; the lower suspension is transported to the plate and frame filter press 8 through the inclined tube sedimentation tank sedimentation outlet 2-3, and forms filter cake (transported for external disposal) and filtrate after filtration.

[0043] S3. Feed water preheating and circulating heating The feed water is transported through a pipeline to the pre-treated water inlet 3-1 at the bottom of the evaporation tower 3. When the liquid level in the tower reaches a preset value, the excess feed water is transported by pump P to the first heat exchanger 6 through the evaporation circulating water outlet 3-2. The water is preheated to 40-50°C using the heat of the recycled water discharged from the first condensation tower 4 and the second condensation tower 5. The water then enters the second heat exchanger 7 and is preheated to 75-80°C using the boiler cooling water (80-95°C) of the waste incineration plant. The heated water is then returned to the top of the evaporation tower 3 through the heated water inlet 3-4.

[0044] S4. Evaporation separation Preheated water is sprayed through a water distributor at the top of evaporation tower 3, forming droplets that countercurrent with the air blown in by fan F inside the tower. Under normal pressure, the water in the droplets is vaporized by the hot air, and the resulting water vapor is discharged through first steam outlet 3-5. As the water evaporates, the concentration of the solution at the bottom of the tower gradually increases. When saturation is reached, the concentrated liquid is pumped by pump P through concentrated liquid outlet 3-3 to concentrated liquid tank 9, ultimately fed into the waste incineration plant's boiler for combustion.

[0045] S5. Steam condensation and heat recovery The water vapor discharged from the evaporation tower enters the first condensation tower 4 through the first steam inlet 4-1, contacts the water sprayed from the first recycled water inlet 4-3 in the packing layer, and the steam condenses to release heat. The heated water is discharged from the first recycled water outlet 4-2 and enters the first heat exchanger 6 as recycled water to preheat the feed water; the steam that is not completely condensed enters the second condensation tower 5 from the second steam outlet 4-4.

[0046] The steam enters the second condensation tower 5 through the second steam inlet 5-1, and is condensed after further heat exchange with the cold water of the second reuse water inlet 5-3. Part of the heated water flows back from the second reuse water outlet 5-2 to the first reuse water inlet 4-3 of the first condensation tower 4 for recycling. The remaining condensed water is discharged to the biochemical system through the evaporation water outlet 5-5 for treatment; the uncondensed exhaust gas is discharged from the exhaust gas discharge outlet 5-4 (after purification in the biochemical treatment system, it meets the discharge standards).

[0047] Circulation and control in the system: Pumps P in each pipeline maintain material delivery pressure, and real-time monitoring of the evaporation tower liquid level, preheating temperature, and concentrate concentration ensures stable system operation. After completing heat exchange in the second heat exchanger 7, the boiler cooling water can be returned to the power plant's circulation system for reuse.

[0048] Example 3 The device provided in Example 1 was used in the evaporation treatment of mixed water of primary DTRO concentrate and organic wastewater in a waste incineration plant and was operated continuously for half a year, achieving good results.

[0049] The device processes approximately 10 tons of water daily. The raw water hardness is approximately 2,000-2,800 mg / L, the inlet water conductivity is approximately 27,000-76,000 μS / cm, and the inlet ammonia nitrogen concentration is approximately 9-94 mg / L. After hardness removal and precipitation treatment by the device, the hardness of the solution entering the evaporator is less than 300 mg / L. After evaporation, the average inlet water volume reduction is approximately 8.57 times. The evaporation-generated water has a conductivity removal rate of >99%, an ammonia nitrogen removal rate of >60%, and an outlet total nitrogen content of <10 mg / L. The evaporation-generated water meets standards and is directly discharged into the plant's vegetation maintenance water system. Due to the device's small processing capacity, the sediment in the inclined tube sedimentation tank is periodically treated every 15 days, with approximately 4.5 tons of filter cake processed each time. The mother liquor from the filter press is collected and directly incinerated or recycled back to the device for treatment.

[0050] In summary, the embodiments of the present invention achieve efficient reduction processing and cascade energy utilization of DTRO concentrate by adopting dual heat sources of boiler cooling water and condensed water, in conjunction with a normal-pressure low-temperature evaporation tower and a high-efficiency heat exchange device, and have broad industrial application value.

[0051] Example 4 The device of this embodiment is the same as that of Example 1, and the process is the same as that of Example 2. The difference is that the materials such as caustic soda / soda ash and flocculant in the dosing tank 1 are replaced by ion exchange resin or membrane, which replaces the dosing precipitation. It is suitable for low-hardness concentrates or scenarios that are sensitive to drug residues and can reduce sludge generation.

[0052] Example 5 The apparatus of this embodiment is the same as that of Example 1, and the process is the same as that of Example 2. The difference is that the inclined tube sedimentation tank 2 is replaced by a flotation tank (suitable for low-density suspended particles), or a centrifuge (suitable for high-concentration sludge scenarios, with higher separation efficiency), or a ceramic membrane filter (to achieve efficient solid-liquid separation and higher filtrate clarity).

[0053] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A DTRO concentrate low temperature evaporation treatment system, characterized in that: The system comprises: Hardness removal unit: dosing tank (1); Solid-liquid separation unit, including sedimentation equipment and filter press equipment; Gas-liquid separation unit: evaporation tower (3); Secondary condensation unit: first condensation tower (4) and second condensation tower (5); Heat exchange unit: a first heat exchanger (6) and a second heat exchanger (7); Evaporation concentrate collection unit; The dosing tank inlet (1-1) of the dosing tank (1) is connected to the raw water DTRO concentrate, and the dosing tank outlet (1-2) of the dosing tank (1) is connected to the sedimentation tank (2); the sedimentation tank liquid outlet (2-2) of the sedimentation tank (2) is connected to the pretreated water inlet (3-1) of the evaporation tower (3) through a pipeline, the evaporation tower (3) is provided with a concentrate outlet (3-3) and a first steam outlet (3-5), the concentrate outlet (3-3) is connected to the evaporation concentrate collection unit, the first steam outlet (3-5) is connected to the first steam inlet (4-1) of the first condensation tower (4) through a pipeline, the first condensation tower (4) is provided with a second steam outlet (4-4), the second steam outlet (4-4) is connected to the second steam inlet (5-1) of the second condensation tower (5) through a pipeline, and the second condensation tower (5) is provided with an exhaust gas discharge outlet (5-4) and an evaporation water outlet (5-5); The first heat exchanger (6) and the second heat exchanger (7) are connected between the evaporation tower (3), the first condensation tower (4) and the second condensation tower (5) for heat recycling.

2. A DTRO concentrate low-temperature evaporation treatment system according to claim 1, characterized in that: In the solid-liquid separation unit, the precipitation device is a sedimentation tank (2), and the filter pressing device is a filter press (8); the sedimentation tank (2) is provided with a sedimentation tank inlet (2-1) and a sedimentation tank sedimentation outlet (2-3); the raw water is pretreated in the dosing tank (1) to obtain pretreated water; the pretreated water flows out from the dosing tank outlet (1-2), and the dosing tank outlet (1-2) is connected to the sedimentation tank inlet (2-1) through a pipeline; after the pretreated water is subjected to sedimentation treatment in the sedimentation tank (2), feed water and a suspension are obtained; the suspension is discharged to the filter press (8) through the sedimentation tank sedimentation outlet (2-3) through a pipeline; The pretreatment is to remove the scaling ions Ca 2+ Mg 2+ .

3. A DTRO concentrate low-temperature evaporation treatment system according to claim 2, characterized in that: The evaporation tower (3) is provided with an evaporation circulating water outlet (3-2) and a heating water inlet (3-4); the evaporation circulating water outlet (3-2) of the evaporation tower (3) is connected to the first heat exchanger (6) and the second heat exchanger (7) in sequence through a pump body, and finally connected to the heating water inlet (3-4) of the evaporation tower (3); the first condensation tower (4) and the second condensation tower (5) are both connected to the first heat exchanger (6) through pipelines; the second heat exchanger (7) is connected to an external heat source; The feed water leaves the liquid outlet (2-2) of the sedimentation tank and is transported to the pre-treated water inlet (3-1) through a pipeline. The pre-treated water inlet (3-1) is arranged at the bottom of the evaporation tower (3). After a certain amount of water is stored in the tower body, the excess water is first pumped into the first heat exchanger (6) through the evaporation circulating water outlet (3-2) through the pump body, and then the recycled water flowing out of the first condensation tower (4) and the second condensation tower (5) is heated, and then passes through the second heat exchanger (7) and is heated again by the heat source. After the heating is completed, the recycled water flows back to the heating water inlet (3-4).

4. A DTRO concentrate low-temperature evaporation treatment system according to claim 3, characterized in that: A fan (F) is provided in the evaporation tower (3), and the fan (F) blows away a portion of the steam, which leaves the evaporation tower (3) from the first steam outlet (3-5) and flows to the first steam inlet (4-1) through the pipeline.

5. A DTRO concentrate low-temperature evaporation treatment system according to claim 3, characterized in that: The evaporation concentrate collection unit is a concentrate tank (9); as the water vapor in the evaporation tower (3) gradually evaporates, the concentration of the liquid in the tower becomes higher and higher. When the liquid reaches saturation, the concentrate outlet (3-3) at the bottom of the tower is opened, and the concentrate is discharged to the concentrate tank (9) through a pump (P) and a pipeline.

6. A DTRO concentrate low-temperature evaporation treatment system according to claim 3, characterized in that: The first condensation tower (4) is provided with a first recycled water outlet (4-2) and a first recycled water inlet (4-3); the second condensation tower (5) is provided with a second recycled water outlet (5-2) and a second recycled water inlet (5-3); the first recycled water outlet (4-2) is connected to the second heat exchange channel of the first heat exchanger (6) through a pipeline, and further connected to the second recycled water inlet (5-3); the second recycled water outlet (5-2) is connected to the first recycled water inlet (4-3) through a pipeline, forming a heat exchange cycle; In the first condensing tower (4), the steam is fully contacted with the cold water entering the tower top through the first recycled water inlet (4-3) in the packing layer. After releasing the heat, the steam is discharged from the second steam outlet (4-4) at the tower top. The heated water is collected at the bottom of the tower and flows out from the first recycled water outlet (4-2) as recycled water. The recycled water is connected to the second heat exchange channel of the first heat exchanger (6) through a pipeline to heat the feed water in the first heat exchange channel. The recycled water after heat exchange flows to the second recycled water inlet (5-3). The steam leaving from the second steam outlet (4-4) flows to the second steam inlet (5-1) through the pipeline. After releasing the heat, the steam is discharged from the tail gas outlet (5-4) at the top of the tower. A part of the heated water is collected at the bottom of the tower and flows from the second recycled water outlet (5-2) through the pipeline to the first recycled water inlet (4-3). The remaining heated water is discharged through the evaporation water outlet (5-5).

7. A DTRO concentrate low-temperature evaporation treatment system according to any one of claims 1 to 6, characterized in that: A pump (P) is provided on the pipeline from the sedimentation tank liquid outlet (2-2) to the pre-treated water inlet (3-1), the pipeline from the concentrated liquid outlet (3-3) to the concentrated liquid tank (9), the pipeline from the evaporation circulating water outlet (3-2) to the first heat exchanger (6), the pipeline from the first recycled water outlet (4-2) to the first heat exchanger (6), the pipeline from the second recycled water outlet (5-2) to the first recycled water inlet (4-3), and the pipeline discharged from the evaporation produced water outlet (5-5). The pump (P) is selected from either a centrifugal pump or a screw pump.

8. A DTRO concentrate low-temperature evaporation treatment system according to claim 7, characterized in that: The pipeline material is selected from: any one of PP, 304 stainless steel, 316L stainless steel pipeline, glass fiber reinforced plastic pipeline or polytetrafluoroethylene lined pipeline.

9. A DTRO concentrate low-temperature evaporation treatment system according to claim 8, characterized in that: The evaporation tower (3) is selected from any one of: a normal pressure blast evaporation tower, a reduced pressure evaporation tower or a plate evaporation tower; The first condensation tower (4) and the second condensation tower (5) are selected from any one of a packed condensation tower, a shell and tube condenser or an evaporative condenser; The first heat exchanger (6) and the second heat exchanger (7) are selected from: any one of a plate heat exchanger and a tube heat exchanger; The filter press (8) is selected from any one of a plate and frame filter press and a belt filter press; The heat source of the second heat exchanger (7) is selected from any one of: waste incineration plant boiler cooling water, solar collector, industrial waste heat steam or air source heat pump.

10. Use of the DTRO concentrate low-temperature evaporation treatment system according to claim 1, wherein the raw water hardness is about 2000-2800 mg / L, the influent conductivity is about 27000-76000 μS / cm, and the influent ammonia nitrogen is about 9-94 mg / L.

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