Combined Ultra-Efficient Evaporation Device and Process for Wastewater and Second Solution

Abstract

The present invention provides a combined super-efficient evaporation device and process for wastewater and a second solution. On the basis of the super-efficient evaporation device, at least one second solution evaporator is provided at the end of the process, and a second solution outside the process is introduced into the second solution evaporator for evaporation and crystallization. The heat source used in the second solution evaporator is the low-pressure steam at the end of the super-efficient evaporation. The compositions of the second solution and the wastewater can be the same or different. When the compositions are the same, the concentrated liquid after the wastewater undergoes super-efficient evaporation can enter the second solution evaporator and evaporate and crystallize together with the second solution. When the compositions are different, the concentrated liquid after the wastewater undergoes super-efficient evaporation should be discharged from the process, and a solution with a different composition is introduced from outside the process for evaporation and crystallization. The present invention re-uses the low-value steam that has been utilized 7-9 times by the super-efficient evaporation device for the evaporation and crystallization of the second solution, greatly reducing the wastewater recovery cost and the production cost of the second solution.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical evaporation, and in particular to a combined ultra-efficient evaporation device and process for wastewater and a second solution. Background Art

[0002] For the treatment of low-concentration saline wastewater, there are currently membrane technology devices and evaporation concentration crystallization devices. Due to high energy consumption and high treatment costs, large-scale treatment of low-concentration wastewater has not yet started. In evaporation technology treatment, there are flash evaporation devices, multi-effect evaporation devices, and MVR evaporation devices. However, due to the too low concentration of the wastewater and too high treatment costs, they cannot be applied. Summary of the Invention

[0003] According to the above technical problems, a combined ultra-efficient evaporation device and process for wastewater and a second solution are provided. Based on the ultra-efficient evaporation device, at least one second solution evaporator is arranged at the end, and a second solution outside the process is introduced into the second solution evaporator for evaporation or crystallization. The heat source used in the second solution evaporator is the ultra-efficient evaporation device. The low-pressure steam at the end of the process, which has been used 7 - 9 times and has a temperature of only about 50 degrees, is used to evaporate the second solution. The compositions of the second solution and the wastewater can be the same or different. When the compositions are the same, the wastewater enters the (n + 1)-th second solution evaporator for evaporation concentration or crystallization after passing through the n-effect evaporator in the ultra-efficient evaporation device. When the compositions are different, the concentrated wastewater is discharged from the n-effect process of the ultra-efficient evaporation device. The second solution is introduced from outside the process in the (n + 1)-th second solution evaporator, and after evaporation concentration or crystallization, it is discharged from the (n + k)-th second solution evaporator and enters the ultra-efficient evaporation device, which originally has a large number of evaporation effects. After the steam is super-utilized, the steam consumption per ton of evaporation is only 0.15 - 0.085 for 8 - 10-effect evaporation, which is far more advanced than the current 0.42 - 0.25 for 3 - 5-effect evaporation. On the basis of the extremely advanced ultra-efficient evaporation of the present invention, the final remaining value of the low-pressure steam at the end of the ultra-efficient evaporation is utilized to evaporate and crystallize the second solution, enabling the second solution, which was originally too concentrated to be ultra-efficiently evaporated, to also enjoy the resources of ultra-efficient evaporation, achieving ultra-low energy consumption, and complementing the advantages of low-concentration wastewater that can be ultra-efficiently evaporated and high-concentration second solution that can produce products: The second solution enjoys the resources that are almost waste steam, and a large amount of evaporation and crystallization brings benefits. For the evaporation and crystallization of wastewater, which originally had a very high recovery cost, the steam consumption is greatly reduced by using the ultra-efficient evaporation technology, and the steam at its end is used for the evaporation and crystallization of the second solution that could not be ultra-efficiently evaporated originally, obtaining greater benefits. The second solution could originally only perform 4-effect evaporation, with a steam consumption of 0.35 per ton of evaporation. Now, by combining with the wastewater evaporation, the steam-water ratio of the combined evaporation and crystallization of the 10-effect evaporation of wastewater and the second solution is 0.092, and the steam consumption is reduced by 73.7%. Since the second solution obtains significant energy-saving benefits, it can greatly share the cost of wastewater evaporation, which is extremely beneficial to promoting the ultra-efficient combined evaporation technology of wastewater and promoting the development of the environmental protection cause.

[0004] The technical means adopted by the present invention are as follows:

[0005] The combined ultra-efficient evaporation device for wastewater and a second solution includes a 1 - n-stage wastewater preheater, a second solution preheater, a 1 - n-effect wastewater evaporator, and an (n + 1) - (n + k)-effect second solution evaporator; n is a positive integer from 7 to 9, and k is a positive integer from 1 to 3;

[0006] The preheating temperature gradually increases from the n-stage wastewater preheater to the 1-stage wastewater preheater, and the evaporation liquid temperature gradually decreases from the 1-effect wastewater evaporator to the (n + k)-effect second solution evaporator;

[0007] The liquid inlet of the n-stage waste water preheater is connected to the waste water. Taking the flow direction of the waste water as the front, the liquid outlet of the subsequent stage waste water preheater is connected to the liquid inlet of the previous stage waste water preheater; the liquid outlet of the 1-stage waste water preheater is connected to the liquid inlet of the 1-effect waste water evaporator; in the 1st to nth effect waste water evaporators, the liquid outlet of the subsequent effect waste water evaporator is connected to the liquid inlet of the previous effect waste water evaporator; the waste water is preheated successively through the nth to 1st stage waste water preheaters and enters the 1st effect waste water evaporator to the nth effect waste water evaporator for concentration or evaporation crystallization in sequence from the 1st stage preheater.

[0008] The steam source is connected to the steam inlet of the 1st effect waste water evaporator to supply heat to the 1st effect waste water evaporator. The secondary steam outlet of the subsequent effect waste water evaporator is respectively connected to the steam inlet of the previous effect waste water evaporator and the steam inlet of the waste water preheater with the same serial number as the previous effect waste water evaporator until the secondary steam outlet of the (n - 1)th effect waste water evaporator is connected to the steam inlet of the nth effect waste water evaporator and the steam inlet of the nth stage waste water preheater; preferably, the steam source is connected to the 1st effect waste water evaporator through a steam jet ejector. The steam outlet end of the steam jet ejector is connected to the steam inlet of the 1st effect waste water evaporator. The steam extraction end of the steam jet ejector is connected to the secondary steam outlet of the 3rd effect waste water evaporator. The steam inlet end of the steam jet ejector is connected to the steam source.

[0009] The condensate inlet of the 1st stage waste water preheater is connected to the condensate outlet of the heater of the 1st effect waste water evaporator; the condensate outlet of the 1st stage waste water preheater is connected to the flashing condensate inlet of the heater of the 2nd effect waste water evaporator. The condensate outlet of the nth stage waste water preheater, the condensate outlet of the heater of the nth effect waste water evaporator are connected to the flashing condensate inlet of the heater of the (n + 1)th second solution evaporator; the condensate outlet of the heater of the subsequent effect waste water evaporator and the condensate outlet of the waste water preheater with the same serial number as the subsequent effect waste water evaporator are respectively connected to the flashing condensate inlet of the heater of the previous effect waste water evaporator.

[0010] The liquid inlet of the second solution preheater is connected to the second solution outside the process. The liquid outlet of the second solution preheater is connected to the liquid inlet of the (n + 1)th effect second solution evaporator; in the nth to (n + 1)th effect second solution evaporators, the liquid outlet of the subsequent effect second solution preheater is connected to the liquid inlet of the previous effect second solution evaporator; the second solution is preheated through the second solution preheater and is concentrated or crystallized successively through the (n + 1)th to (n + k)th effect evaporators; the liquid outlet of the (n + k)th effect second solution evaporator is connected to the liquid inlet of the concentrate or crystal suspension heater through an atmospheric leg. The concentrate or crystal suspension discharged from the (n + k)th effect second solution evaporator enters the concentrate or crystal suspension heater through the atmospheric leg and is discharged by a discharge pump.

[0011] The secondary steam outlet of the n-effect wastewater evaporator is connected to the steam inlets of the (n + 1)-effect second solution evaporator and the second preheater. The secondary steam outlet of the subsequent-effect second solution evaporator is connected to the steam inlet of the previous-effect second solution evaporator. The secondary steam outlet of the (n + k)-effect second solution evaporator is connected to the steam inlet of the shell-and-tube condenser.

[0012] Among the (n + 1) to (n + k)-effect second solution evaporators, the condensate outlet of the heater of the subsequent-effect second solution evaporator is connected to the flashing condensate inlet of the heater of the previous-effect second solution evaporator. The condensate outlets of the heaters of the (n + k)-effect second solution evaporator and the second solution preheater are respectively connected to the condensate inlets of the concentrate or crystal suspension heater.

[0013] Preferably, the 1 - n-effect wastewater evaporators are falling-film evaporators, and the length of the heating tubes of the falling-film evaporators does not exceed 5 - 6 m. The (n + 1) to (n + k)-effect second solution evaporators are forced outer circulation evaporators (when the second solution needs to be evaporated and crystallized), and the length of the heating tubes of the forced outer circulation evaporators does not exceed 3 - 4 m.

[0014] Preferably, the condensate of the 1st-stage wastewater preheater has the same temperature and pressure as the condensate of the 2-effect wastewater evaporator after passing through the 1st-stage wastewater preheater, and then they enter the heater of the 3-effect wastewater evaporator together for flashing.

[0015] Preferably, the non-condensable gas exhaust ports of the 1 - n-stage wastewater preheaters, the second solution preheater, the 1 - n-effect wastewater evaporators, and the (n + 1) to (n + k)-effect second solution evaporators are connected to the non-condensable gas inlet pipe of the shell-and-tube condenser. The non-condensable gas outlet pipe of the shell-and-tube condenser is connected to the inlet of the vacuum pump, and the outlet of the vacuum pump is connected to the atmosphere.

[0016] Preferably, both the 1 - n-effect wastewater evaporators and the (n + 1) to (n + k)-effect second solution evaporators include: an evaporation chamber, a heater, a circulation pump, and connecting pipes. The wastewater or the second solution circulates in the evaporation chamber and the heater under the action of the circulation pump. The liquid inlets, liquid outlets, and secondary steam outlets of the wastewater evaporator and the second solution evaporator are arranged on the evaporation chamber. The steam inlets, flashing condensate inlets, condensate outlets, and non-condensable gas discharge ports of the wastewater evaporator and the second solution evaporator are arranged on the heater.

[0017] Preferably, the wastewater and the second solution have the same composition, but the concentration of the second solution is higher than that of the wastewater, and the liquid outlet of the n-effect wastewater evaporator is connected to the liquid inlet of the (n + 1)-effect second solution evaporator.

[0018] Or the components of the wastewater and the second solution are different, and the liquid outlet of the n-effect wastewater evaporator is connected to the drain pipe outside the evaporation liquid flow.

[0019] Preferably, the evaporation temperatures of the first-effect wastewater evaporator to the (n + k)-effect second-solution evaporator gradually decrease, and the heat transfer temperature difference of each effect is 5 - 10°C.

[0020] The combined super-effect evaporation process for wastewater and the second solution includes a material flow process, a steam flow process, and a condensate flow process;

[0021] The material flow process includes: wastewater enters the n-stage wastewater preheater from outside the process, and then flows countercurrently through all wastewater preheaters until it reaches the first-stage wastewater preheater; the wastewater in the first-stage wastewater preheater flows sequentially into the first-effect wastewater evaporator to the n-effect wastewater evaporator for concentration or crystallization; the second solution enters the second-solution preheater from outside the process for preheating and then enters the (n + 1)-effect second-solution evaporator, and then sequentially passes through all second-solution evaporators until the (n + k)-effect second-solution evaporator for evaporation and crystallization. The concentrated liquid or crystal suspension discharged from the (n + k)-effect second-solution evaporator enters the concentrated liquid or crystal suspension heater through an atmospheric leg;

[0022] The steam flow process includes: the steam source enters the first-effect wastewater evaporator to supply heat to the first-effect wastewater evaporator. The secondary steam discharged from the first-effect wastewater evaporator supplies heat to the second-effect wastewater evaporator and the second-stage wastewater preheater, and so on, until the secondary steam discharged from the (n - 1)-effect wastewater evaporator supplies heat to the n-effect wastewater evaporator and the n-stage wastewater preheater. The secondary steam discharged from the n-effect wastewater evaporator supplies heat to the (n + 1)-effect second-solution evaporator and the second-solution preheater. The secondary steam discharged from the (n + 1)-effect second-solution evaporator supplies heat to the (n + 2)-effect second-solution evaporator, and so on, until the secondary steam discharged from the (n + k - 1)-effect second-solution evaporator supplies heat to the (n + k)-effect second-solution evaporator. The secondary steam discharged from the (n + k)-effect second-solution evaporator enters the shell-and-tube condenser for condensation;

[0023] The condensate water process includes: The condensate water of the heater of the 1st effect wastewater evaporator enters the 1st stage wastewater preheater, supplies heat to the 1st stage wastewater preheater and then has the same temperature and pressure as the condensate water of the heater of the 2nd effect wastewater evaporator. Together with the condensate water of the heater of the 2nd effect wastewater evaporator and the condensate water of the 2nd stage wastewater preheater, they enter the heater of the 3rd effect wastewater evaporator for flashing; The condensate water of the heater of the 3rd effect wastewater evaporator and the condensate water of the 3rd stage wastewater preheater enter the heater of the 4th effect wastewater evaporator for flashing, and so on. The condensate water of the nth effect wastewater evaporator enters the heater of the (n + 1)th effect second solution evaporator for flashing; The condensate water of the (n + 1)th effect second solution evaporator enters the heater of the (n + 2)th effect second solution evaporator for flashing, and so on, until the condensate water in the (n + k - 1)th effect second solution evaporator enters the heater of the (n + k)th effect second solution evaporator for flashing. The condensate water in the (n + k)th effect second solution evaporator enters the concentrate or crystal suspension heater to supply heat, and the condensate water of the second solution preheater also enters the concentrate or crystal suspension heater to supply heat. After the condensate water in the concentrate or crystal suspension heater enters the condensate water tank, it is discharged by the condensate water pump.

[0024] Preferably, it further includes a non-condensable gas process;

[0025] The non-condensable gas process includes: The non-condensable gases of the 1st to nth stage wastewater preheaters, the second solution preheater, the 1st to nth effect wastewater evaporators, and the (n + 1)th to (n + k)th effect second solution evaporators are all discharged into the shell-and-tube condenser and then pumped out by a vacuum pump.

[0026] Preferably, when the second solution is a high-concentration solution with the same components as the wastewater components, the second solution will become a carrier to help the crystallization of a certain compound composition in the wastewater. At this time, in the material process: After the wastewater is concentrated by the nth effect wastewater evaporator, it enters the (n + 1)th effect second solution evaporator and performs evaporation crystallization together with the high-concentration second solution as the carrier. The second solution helps the compounds with the same components in the wastewater to precipitate, achieving the full recovery and zero discharge of the wastewater components in terms of total quantity balance.

[0027] When the wastewater and the second solution have different components, at this time in the material process: The wastewater is directly discharged from the process after passing through the nth effect wastewater evaporator.

[0028] Preferably, in the steam process: The steam source together with the secondary steam in the 3rd effect wastewater evaporator aspirated by the steam jet ejector enters the heater of the 1st effect wastewater evaporator as heating steam.

[0029] Typical multiple-effect evaporation is 3 - 5 effects, and the present invention can be designed to 8 - 12 effects of evaporation crystallization:

[0030] First of all, hyper-efficient evaporation can only be applied to low-concentration wastewater with a very low boiling point elevation. For general evaporation crystallization solutions, the boiling point elevation during concentration is generally 3-5 degrees, and the boiling point elevation of the saturated solution reaches 8 degrees. For example, the boiling point elevation of a saturated sodium sulfate solution is 3 degrees, that of a saturated sodium chloride solution is 8 degrees, and that of a saturated acid bath is 8 degrees. The boiling point elevation of a few hydrated crystal solutions reaches dozens of degrees. However, the boiling point elevation of most low-concentration inorganic salt wastewater is only 0.1-0.5 degrees. As the concentration increases, in the later stage of evaporation and concentration, it will reach 3-5 degrees, and finally reach about 8 degrees when saturated. Therefore, in the range of about 85% of the evaporation volume, it is in a situation of very low boiling point elevation. Only in the final evaporation crystallization stage does the boiling point rise significantly. Therefore, in the early stage of low-concentration wastewater recovery, the characteristic of very low boiling point elevation can be utilized to significantly increase the number of effects and achieve hyper-efficient evaporation. However, to achieve hyper-efficient evaporation, in addition to the necessary condition of very low boiling point elevation, innovation is also required in the design of the evaporation device:

[0031] In the present invention, in order to achieve hyper-efficient evaporation of low-concentration wastewater, 5 "innovations" have been realized in the device design:

[0032] (1) Breaking through the design convention of multi-effect evaporation, conducting a pilot test on small-temperature-difference heat transfer, testing the heat transfer coefficients of small-temperature-difference under different media, different flow rates, and different liquid temperatures, so that small-temperature-difference heat transfer has a reliable practical basis. Reducing the design heat transfer temperature difference of traditional multi-effect evaporation from 12-25 degrees to 5-10 degrees.

[0033] (2) Breaking the convention of evaporating low-concentration water mixed with the solution together, separating the low-concentration wastewater and the solution for evaporation. The low-concentration wastewater enters from one end and gradually becomes concentrated: designing an evaporation process of "countercurrent preheating of wastewater, feeding water into the first effect, evaporating in a cocurrent manner, and crystallizing in the last effect", minimizing the temperature difference loss caused by the increase in the concentration of the solution in each effect and resulting in a boiling point elevation;

[0034] (3) Reducing the normal design flow velocity value in the pipeline by another 20%, minimizing the temperature difference loss caused by the resistance of the secondary steam pipeline, and controlling the temperature difference loss caused by the resistance of the secondary steam pipeline within a cumulative 2 degrees;

[0035] (4) Shortening the length of the falling film heating tube from 6-8 meters to 5-6 meters, reducing the temperature difference loss caused by the increase in the boiling point of the solution due to the flow resistance of the secondary steam in the tube;

[0036] (5) Shortening the length of the heating tube of the last-effect crystallization evaporator, designing the usually 5-6-meter-long heating tube to 3-4 meters, expanding the crystallization circulation volume, reducing the heating temperature rise flowing through the heater from the usual 4-5 degrees to 1-2 degrees, and reducing the temperature difference loss caused by the heating tube temperature rise;

[0037] Enabling the 3-5 effects of the usual multi-effect evaporation to break through to 6-12 effects of the hyper-efficient evaporation of the present invention.

[0038] Taking n as 8 and k as 2 as an example: Based on the ultra-efficient evaporation crystallization of low-concentration wastewater, a second solution is introduced from outside the process at the 9th effect to implement a combined evaporation crystallization process. The secondary steam from the 8th effect of the ultra-efficient evaporation of low-concentration wastewater is used for the evaporation crystallization of the second solution.

[0039] Taking the second solution introduced from outside the process having the same components as the wastewater as an example, assuming the wastewater is low-concentration acidic wastewater, according to the proportion of the evaporation water volume required between the acidic water and the acid bath, it is tentatively set to use a combined evaporation crystallization device with a 9+1 process, that is, 9 acidic water concentration evaporators and 1 forced external circulation evaporator. The acid bath is introduced from outside the process for 10-effect evaporation crystallization.

[0040] Calculation of the crystallization evaporation amount in the 10-effect combined evaporation:

[0041] Flow rate of the acidic water concentrated liquid discharged from the 9-effect evaporator: L1 = L0 - W 1-9

[0042] In the formula: L0 is the flow rate of the low-concentration acidic water entering the process

[0043] W 1-9 is the cumulative evaporation amount from the 1st effect to the 9th effect, which can be obtained through heat balance calculation or process measurement.

[0044] Flow rate of the acid bath introduced from outside the process for the 10-effect evaporator: L2

[0045] Total amount of concentrated liquid + acid bath entering the 10th effect: L1 + L2

[0046] Saturated evaporation amount of the acid bath entering the 10th effect: W B = L1β1 + L2β2

[0047] β1 and β2 are the saturated evaporation rates of the concentrated liquid and the acid bath entering the 10th effect respectively, and the chart is consulted according to the specific gravity of the acid bath.

[0048] Crystallization evaporation amount in the 10th effect: W J = W 10 - W B

[0049] W 10 Obtained from heat balance calculation, or can be measured during production.

[0050] Crystallization evaporation rate in the 10th effect: W J / (L1 + L 2- W B ) should be controlled between 0.15 - 0.2

[0051] Amount of sodium sulfate crystallized in the 10th effect: G = W J *0.453

[0052] For example, if the wastewater is acidic water and the second solution is an acid bath. The introduced 4-effect evaporation equipment for the acid bath has a steam-water ratio of 0.35. The wastewater can be subjected to 10-effect evaporation, and the steam-water ratio of the 10-effect evaporation of the wastewater can be 0.092. After implementing combined evaporation, the first 9 effects of the 10 effects are designed for the concentration evaporation of acidic water, and the 10th effect is designed for evaporation crystallization. Since the concentrated liquid entering from the 9th effect is too little and not enough for evaporation crystallization, an acid bath is introduced from outside the process into the 10th effect, and together with the concentrated liquid entering from the 9th effect, evaporation crystallization is carried out in the 10th effect. The common steam-water ratio is 0.092, enabling the acid bath evaporation that could originally only achieve 4-effect evaporation heat economy to also achieve the heat economy of super-effect evaporation: the steam-water ratio is 0.092. For each ton of evaporated water, 0.35 - 0.092 = 0.258 tons of boiler steam is saved, saving 73.7% of steam. Therefore, combined super-effect evaporation maximally utilizes the reasonable use of steam energy.

[0053] When the components of the second solution and the wastewater are different, the steam of the n+1 to n+k effects of the wastewater is used to heat the second solution to achieve the evaporation crystallization of the second solution, reasonably utilizing the heat of the low-pressure steam at the last few effects of super-effect evaporation, which is of great significance for wastewater treatment. Because the biggest obstacle to wastewater treatment is the high treatment cost and loss. Some enterprises that generate a large amount of wastewater are unable to treat the wastewater. However, the present invention regards wastewater treatment as a linkage industry that can utilize its cheap heat source, and uses the low-pressure steam that has been utilized n times (n is 7 - 9) generated during wastewater treatment for the evaporation concentration crystallization of the second solution. The second solution can be the evaporation crystallization of solutions in chemical engineering, alkali making, pharmaceutical manufacturing, sugar making, salt making processes; it can be fruit juice concentration, condensed milk concentration, and can be heating for heating...; all products that require heat supply and all heat supply needs can be combined with the super-effect evaporation recovery of wastewater or combined heat supply to achieve the lowest energy consumption, the lowest cost, and the lowest expenses. This will be greatly beneficial to the wastewater treatment cause and contribute to the development of combined heat supply enterprises.

[0054] Based on the above reasons, the present invention can be widely promoted in the fields of wastewater treatment and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0056] Figure 1 It is a schematic structural diagram of the combined super-effect evaporation device for wastewater and the second solution in Embodiment 1 of the present invention.

[0057] Figure 2This is a schematic structural diagram of the combined super-efficient evaporation device for wastewater and the second solution in Embodiment 2 of the present invention.

[0058] In the figure: V1 to V8 are the evaporation chambers of the 1st to 8th effect wastewater evaporators; H1 to H8 are the heaters of the 1st to 8th effect wastewater evaporators; XB1 to XB8 are the circulation pumps of the 1st to 8th effect wastewater evaporators; Q1 to Q8 are the 1st to 8th stage wastewater preheaters; QB is the second solution preheater; V9 to V10 are the evaporation chambers of the 9th to 10th effect second solution evaporators; H9 to H10 are the heaters of the 9th to 10th effect second solution evaporators; XB9 to XB10 are the circulation pumps of the 9th to 10th effect second solution evaporators; ZP is a steam jet ejector; QX is a concentrate or crystal suspension heater; N is a shell-and-tube condenser; NG is a condensate water tank; ZK is a vacuum pump; PB is a discharge pump; NB is a condensate water pump. Detailed implementation manners

[0059] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0060] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The description of at least one exemplary embodiment below is actually only illustrative and in no way restrictive of the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts, such as only increasing or decreasing the number of n or k, fall within the scope of protection of the present invention.

[0061] Embodiment 1

[0062] As Figure 1 shown, the combined super-efficient evaporation device for wastewater and the second solution includes 1st to 8th stage wastewater preheaters (Q1 to Q8), the second solution preheater QB, 1st to 8th effect wastewater evaporators, and 9th to 10th effect second solution evaporators;

[0063] The 1st to 8th effect wastewater evaporators and the 9th to 10th effect second solution evaporators each include: an evaporation chamber (V1 to V10), a heater (H1 to H10), a circulation pump (XB1 to XB10), and a connecting pipe. The wastewater or the second solution circulates in the evaporation chamber (V1 to V10) and the heater (H1 to H10) under the action of the circulation pump (XB1 to XB10).

[0064] The preheating temperature gradually increases from the 8th-stage wastewater preheater to the 1st-stage wastewater preheater, while the evaporation liquid temperature gradually decreases from the 1st-effect wastewater evaporator to the 10th-effect second solution evaporator;

[0065] The liquid inlet of the 8th-stage wastewater preheater Q8 is connected to the wastewater pipe entering the process. Taking the flow direction of the wastewater as the front, the liquid outlet of the subsequent-stage wastewater preheater is connected to the liquid inlet of the previous-stage wastewater preheater (for example, the liquid outlet of the 7th-stage wastewater preheater Q7 is connected to the liquid inlet of the 6th-stage wastewater preheater Q6); the liquid outlet of the 1st-stage wastewater preheater Q1 is connected to the liquid inlet of the evaporation chamber V1 of the 1st-effect wastewater evaporator; in the evaporation chambers of the 1st to 8th-effect wastewater evaporators, the liquid outlet of the evaporation chamber of the subsequent-effect wastewater evaporator is connected to the liquid inlet of the evaporation chamber of the previous-effect wastewater evaporator (for example, the liquid outlet of the evaporation chamber V5 of the 5th-effect wastewater evaporator is connected to the liquid inlet of the evaporation chamber V6 of the 6th-effect wastewater evaporator); the liquid inlet of the second solution preheater QB is connected to the second solution pipe introduced from outside the process. The second solution is a high-concentration acid bath with the same components as the wastewater. The liquid outlet of the second solution preheater QB is connected to the liquid inlet of the evaporation chamber V9 of the 9th-effect second solution evaporator; the wastewater concentrate discharged from the evaporation chamber V8 of the 8th-effect wastewater evaporator enters the evaporation chamber V9 of the 9th-effect second solution evaporator. The liquid outlet of the evaporation chamber V9 of the 9th-effect second solution evaporator is connected to the liquid inlet of the evaporation chamber V10 of the 10th-effect second solution evaporator; the liquid outlet of the evaporation chamber V10 of the 10th-effect second solution evaporator is connected to the liquid inlet of the concentrate or crystal suspension heater QX through an air leg and is discharged by the discharge pump PB;

[0066] That is, the material flow process includes: wastewater enters the 8th-stage wastewater preheater Q8 from outside the process and then flows countercurrently through all wastewater preheaters until it reaches the 1st-stage wastewater preheater Q1; the wastewater in the 1st-stage wastewater preheater flows sequentially into the evaporation chamber V1 of the 1st-effect wastewater evaporator to the evaporation chamber V10 of the 10th-effect second solution evaporator; the second solution enters the second solution preheater QB from outside the process for preheating and then enters the evaporation chamber V9 of the 9th-effect second solution evaporator, and then enters the evaporation chamber V10 of the 10th-effect second solution evaporator. The crystal suspension discharged from the evaporation chamber V10 of the 10th-effect second solution evaporator enters the concentrate or crystal suspension heater QX through an air leg;

[0067] The steam source is communicated with the steam inlet end of the steam jet ejector ZP. The steam outlet end of the steam jet ejector ZP is communicated with the steam inlet of the heater H1 of the first-effect wastewater evaporator. The steam extraction end of the steam jet ejector ZP is communicated with the secondary steam outlet of the evaporation chamber V3 of the third-effect wastewater evaporator. The steam inlet end of the steam jet ejector ZP is communicated with the steam source. The secondary steam outlet of the evaporation chamber of the subsequent-effect wastewater evaporator is communicated with the steam inlet of the heater of the previous-effect wastewater evaporator and the steam inlet of the wastewater preheater with the same serial number as the previous-effect wastewater evaporator (for example, the secondary steam outlet of the evaporation chamber V2 of the second-effect wastewater evaporator is communicated with the steam inlet of the heater H3 of the third-effect wastewater evaporator and the steam inlet of the third-stage preheater Q3), until the secondary steam outlet of the evaporation chamber V7 of the seventh-effect wastewater evaporator is communicated with the steam inlet of the heater H8 of the eighth-effect wastewater evaporator and the steam inlet of the eighth-stage wastewater preheater Q8; the secondary steam outlet of the evaporation chamber V8 of the eighth-effect wastewater evaporator is communicated with the steam inlets of the heater H9 of the ninth-effect second solution evaporator and the second preheater QB. The secondary steam outlet of the evaporation chamber V9 of the ninth-effect second solution evaporator is communicated with the steam inlet of the heater H10 of the tenth-effect second solution evaporator. The secondary steam outlet of the evaporation chamber V10 of the tenth-effect second solution evaporator is communicated with the steam inlet of the partition condenser N;

[0068] That is, the steam flow process includes: the steam source together with the secondary steam in the evaporation chamber V3 of the third-effect wastewater evaporator sucked by the steam jet ejector ZP enters the heater H1 of the first-effect wastewater evaporator to supply heat to the first-effect wastewater evaporator. The secondary steam discharged from the evaporation chamber V1 of the first-effect wastewater evaporator supplies heat to the heater H2 of the second-effect wastewater evaporator and the second-stage wastewater preheater Q2, and so on, until the secondary steam discharged from the evaporation chamber V7 of the seventh-effect wastewater evaporator supplies heat to the heater H8 of the eighth-effect wastewater evaporator and the eighth-stage wastewater preheater Q8. The secondary steam discharged from the evaporation chamber V8 of the eighth-effect wastewater evaporator supplies heat to the heater H9 of the ninth-effect second solution evaporator and the second solution preheater QB. The secondary steam discharged from the evaporation chamber V9 of the ninth-effect second solution evaporator supplies heat to the heater H10 of the tenth-effect second solution evaporator. The secondary steam discharged from the evaporation chamber V10 of the tenth-effect second solution evaporator enters the partition condenser N for condensation;

[0069] The condensate inlet of the first-stage wastewater preheater Q1 is connected to the condensate outlet of the heater H1 of the first-effect wastewater evaporator; the condensate outlet of the first-stage wastewater preheater Q1 is connected to the flashing condensate inlet of the heater H2 of the second-effect wastewater evaporator. The condensate outlet of the heater of the subsequent-effect wastewater evaporator and the condensate outlet of the wastewater preheater with the same serial number as the subsequent-effect wastewater evaporator are respectively connected to the flashing condensate inlet of the heater of the previous-effect wastewater evaporator; (for example, the condensate outlet of the third-stage wastewater preheater Q3 and the condensate outlet of the heater H3 of the third-effect wastewater evaporator are respectively connected to the flashing condensate inlet of the heater H4 of the fourth-effect wastewater evaporator); the condensate outlet of the eighth-stage wastewater preheater Q8 and the condensate outlet of the heater H8 of the eighth-effect wastewater evaporator are respectively connected to the flashing condensate inlet of the heater H9 of the ninth-effect second solution evaporator; the condensate outlet of the heater H9 of the ninth-effect second solution evaporator is connected to the flashing condensate inlet of the heater H10 of the tenth-effect second solution evaporator; the condensate outlet of the heater H10 of the tenth-effect second solution evaporator and the condensate outlet of the second solution preheater QB are respectively connected to the flashing condensate inlet of the concentrate or crystal suspension heater QX. The condensate outlet of the concentrate or crystal suspension heater QX is connected to the condensate tank NG, and the condensate in the condensate tank NG is discharged through the condensate pump NB.

[0070] That is, the condensate flow process includes: the condensate of the heater H1 of the first-effect wastewater evaporator enters the first-stage wastewater preheater Q1 for heating, and after supplying heat to the first-stage wastewater preheater Q1, it has the same temperature and pressure as the condensate of the heater H2 of the second-effect wastewater evaporator, and together with the condensate of the heater H2 of the second-effect wastewater evaporator and the condensate of the second-stage wastewater preheater Q2, they enter the heater H3 of the third-effect wastewater evaporator for flashing; the condensate of the heater H3 of the third-effect wastewater evaporator and the condensate of the third-stage wastewater preheater Q3 enter the heater H4 of the fourth-effect wastewater evaporator for flashing, and so on, until the condensate of the heater H7 of the seventh-effect wastewater evaporator and the condensate of the seventh-stage wastewater preheater Q7 enter the heater H8 of the eighth-effect wastewater evaporator for flashing, the condensate of the heater H8 of the eighth-effect wastewater evaporator and the condensate of the eighth-stage wastewater preheater Q8 enter the heater H9 of the ninth-effect second solution evaporator for flashing, the condensate of the heater H9 of the ninth-effect second solution evaporator enters the heater H10 of the tenth-effect second solution evaporator for flashing; the condensate in the heater H10 of the tenth-effect second solution evaporator enters the concentrate or crystal suspension heater QX for heat supply, and the condensate of the second solution preheater QB also enters the concentrate or crystal suspension heater QX for heat supply, and the condensate in the concentrate or crystal suspension heater QX is discharged or discharged after entering the condensate tank NG.

[0071] The non-condensable gas exhaust ports of the 1st to 8th stage waste water preheaters, the second solution preheater, the 1st to 8th effect waste water evaporators, and the 9th to 10th effect second solution evaporators are communicated with the non-condensable gas inlet of the partition wall condenser N, and the non-condensable gas outlet of the partition wall condenser N is discharged through the vacuum pump ZK.

[0072] That is, the non-condensable gas process includes: the non-condensable gases of the 1st to 8th stage waste water preheaters, the second solution preheater, the 1st to 8th effect waste water evaporators, and the 9th to 10th effect second solution evaporators all enter the partition wall condenser N, and then are extracted by the vacuum pump ZK.

[0073] The 1st to 8th effect waste water evaporators are falling film evaporators, and the heating tube length of the falling film evaporator is 5 - 6m. The 9th to 10th effect second solution evaporators are forced outer circulation evaporators, and the heating tube length of the forced outer circulation evaporator is 3 - 4m.

[0074] The evaporation temperatures of the 1st effect waste water evaporator to the 10th effect second solution evaporator gradually decrease, and the heat transfer temperature difference is 5 - 10°C.

[0075] In this embodiment: The acidic waste water and the high-concentration acid bath with the same components are subjected to combined super-effect evaporation crystallization.

[0076] The acidic waste water of an enterprise requires an evaporation capacity of 475.254 t / h and is processed in 8 sets.

[0077] The evaporation capacity of each set of thermal flat evaporation is 62.9 t / h, and the total of 8 sets is 503.2 t / h, exceeding the evaporation capacity required for zero discharge of material balance by 503.2 - 475.25 = 27.95 t / h.

[0078] (1) Evaporation process parameters: Saturated temperature of heating steam 135°C, final effect liquid temperature 44°C, cooling water temperature in summer 32°C

[0079] (2) Process logistics indicators: There are 8 sets in total, and the indicators of each set are as follows:

[0080]

[0081] (3) Economic benefits

[0082] Annual direct cost required for acidic water recovery:

[0083]

[0084] Annual increased income and recovered cost from acidic water recovery: (Unit price provided by the enterprise)

[0085]

[0086] Total annual increased income: 9351.19 - 4208.83 = 5142.36 ten thousand yuan

[0087] Example 2

[0088] As Figure 2 shown, the difference between this embodiment and Embodiment 1 is as follows: After the wastewater is evaporated and concentrated in the 8-effect wastewater evaporator, it directly discharges from the process, and a second solution - such as caustic soda solution, saturated brine, etc. - is introduced from outside the process. The second solution enters the 9-effect and 10-effect second solution evaporators for evaporation and crystallization after passing through the second solution preheater QB, and the crystal suspension is discharged from the process after being heated by the suspension heater.

[0089] Finally, it should be noted that: The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: They can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. The combined super-efficient evaporation device for wastewater and the second solution, characterized in that, It includes a wastewater preheater of levels 1 to n, a second solution preheater, wastewater evaporators of 1 to n effects, and second solution evaporators of n + 1 to n + k effects; n is a positive integer from 7 to 9, and k is a positive integer from 1 to 3; The preheating temperatures of the wastewater preheaters from level n to level 1 gradually increase, and the evaporation temperatures of the wastewater evaporators of 1 effect to the second solution evaporators of n + k effects gradually decrease; The liquid inlet of the wastewater preheater of level n is connected to the wastewater. Taking the flow direction of the wastewater as the front, the liquid outlet of the subsequent wastewater preheater is connected to the liquid inlet of the previous wastewater preheater; the liquid outlet of the wastewater preheater of level 1 is connected to the liquid inlet of the wastewater evaporator of 1 effect; in the wastewater evaporators of 1 to n effects, the liquid outlet of the subsequent wastewater evaporator is connected to the liquid inlet of the previous wastewater evaporator; Live steam passes through the steam pipeline to supply heat to the wastewater evaporator of 1 effect. The secondary steam outlet of the subsequent wastewater evaporator is connected to the steam inlet of the previous wastewater evaporator and the steam inlet of the wastewater preheater with the same position number as the previous wastewater evaporator, until the secondary steam outlet of the wastewater evaporator of n - 1 effect is connected to the steam inlet of the wastewater evaporator of n effect and the steam inlet of the wastewater preheater of level n; The condensate inlet of the wastewater preheater of level 1 is connected to the condensate outlet of the heater of the wastewater evaporator of 1 effect; the condensate outlet of the wastewater preheater of level 1 is connected to the flash condensate inlet of the heater of the wastewater evaporator of 2 effects, and the condensate outlet of the wastewater preheater of level n is connected to the condensate outlet of the heater of the wastewater evaporator of n effect and the flash condensate inlet of the heater of the second solution evaporator of n + 1 effect; the condensate outlets of the heaters of the remaining subsequent wastewater evaporators and the condensate outlets of the wastewater preheaters with the same position numbers as the subsequent wastewater evaporators are respectively connected to the flash condensate inlets of the heaters of the previous wastewater evaporators; The liquid inlet of the second solution preheater is connected to the second solution entering from outside the process. The liquid outlet of the second solution preheater is connected to the liquid inlet of the second solution evaporator of n + 1 effect; in the second solution evaporators of n + 1 to n + k effects, the liquid outlet of the subsequent second solution evaporator is connected to the liquid inlet of the previous second solution evaporator; the liquid outlet of the second solution evaporator of n + k effect is connected to the liquid inlet of the crystal suspension heater through an atmospheric leg. The crystal suspension discharged from the second solution evaporator of n + k effect enters the crystal suspension heater through the atmospheric leg and is discharged by a discharge pump; The secondary steam outlet of the wastewater evaporator of n effect is connected to the steam inlets of the second solution evaporator of n + 1 effect and the second preheater. The secondary steam outlet of the subsequent second solution evaporator is connected to the steam inlet of the previous second solution evaporator. The secondary steam outlet of the second solution evaporator of n + k effect is connected to the steam inlet of the shell-and-tube condenser; In the second solution evaporators of n + 1 to n + k effects, the condensate outlet of the heater of the subsequent second solution evaporator is connected to the flash condensate inlet of the heater of the previous second solution evaporator; the condensate outlets of the heaters of the second solution evaporator of n + k effect and the second solution preheater are respectively connected to the condensate inlets of the crystal suspension heater.

2. The combined super-efficient evaporation device for wastewater and the second solution according to claim 1, characterized in that, The 1st to nth effect wastewater evaporators are falling film evaporators, and the heating tubes of the falling film evaporators have a length of 5 to 6 m. The (n + 1)th to (n + k)th effect second solution evaporators are forced outer circulation evaporators, and the heating tubes of the forced outer circulation evaporators have a length of 3 to 4 m.

3. The combined super-efficient evaporation device for wastewater and the second solution according to claim 1, characterized in that, The steam source is connected to the 1st effect wastewater evaporator through a steam jet ejector. The steam outlet end of the steam jet ejector is connected to the steam inlet of the 1st effect wastewater evaporator. The steam extraction end of the steam jet ejector is connected to the steam outlet of the 3rd effect wastewater evaporator. The steam inlet end of the steam jet ejector is connected to the steam source.

4. The combined super-efficient evaporation device for wastewater and the second solution according to claim 1, characterized in that, The 1st to nth effect wastewater evaporators and the (n + 1)th to (n + k)th effect second solution evaporators both include: an evaporation chamber, the heater, a circulation pump, and connecting pipes. The wastewater or the second solution circulates in the evaporation chamber and the heater under the action of the circulation pump. The liquid inlet, liquid outlet, and secondary steam outlet of the wastewater evaporator and the second solution evaporator are arranged on the evaporation chamber. The steam inlet, flash condensate inlet, and condensate outlet of the wastewater evaporator and the second solution evaporator are arranged on the heater.

5. The combined super-efficient evaporation device for wastewater and the second solution according to claim 1, characterized in that, The evaporation liquid temperatures of the 1st effect wastewater evaporator to the (n + k)th effect second solution evaporator gradually decrease. The heat transfer temperature difference of each effect is 5 to 10 °C. The flow velocity value of the steam in the pipeline connecting the steam inlet and the secondary steam outlet is 20% lower than the standard flow velocity value in the pipeline design.

6. The combined super-efficient evaporation device for wastewater and the second solution according to any one of claims 1 to 5, characterized in that, The wastewater and the second solution have the same composition, but the concentration of the second solution is higher than that of the wastewater. The liquid outlet of the nth effect wastewater evaporator is connected to the liquid inlet of the (n + 1)th effect second solution evaporator.

7. The combined super-efficient evaporation device for wastewater and the second solution according to any one of claims 1 to 5, characterized in that, The wastewater and the second solution have different compositions. The liquid outlet of the nth effect wastewater evaporator is connected to the wastewater evaporation liquid drain pipe leading to outside the process.

8. The combined super-efficient evaporation process for wastewater and the second solution, implemented based on the combined super-efficient evaporation device for wastewater and the second solution according to any one of claims 1 to 7, characterized in that, It includes a material process technology, a steam process technology, and a condensate process technology; The material process technology includes: The wastewater enters the n-stage wastewater preheater from outside the process, and then flows countercurrently through all the wastewater preheaters until it reaches the 1st stage wastewater preheater; The wastewater in the 1st stage wastewater preheater flows sequentially into the 1st effect wastewater evaporator to the nth effect wastewater evaporator for concentration; The second solution enters the (n + 1)th effect second solution evaporator after being preheated in the second solution preheater, and then passes through all the second solution evaporators until the (n + k)th effect second solution evaporator for evaporation or crystallization. The concentrated liquid or crystal suspension discharged from the (n + k)th effect second solution evaporator enters the concentrated liquid or crystal suspension heater through an atmospheric leg; The concentrated liquid or crystal suspension is discharged from the process through a discharge pump. The steam process includes: The steam source enters the first-effect wastewater evaporator to supply heat to it. The secondary steam discharged from the first-effect wastewater evaporator supplies heat to the second-effect wastewater evaporator and the second-stage wastewater preheater, and so on, until the secondary steam discharged from the (n - 1)-effect wastewater evaporator supplies heat to the n-effect wastewater evaporator and the n-stage wastewater preheater. The secondary steam discharged from the n-effect wastewater evaporator supplies heat to the (n + 1)-effect second-solution evaporator and the second-solution preheater. The secondary steam discharged from the (n + 1)-effect second-solution evaporator supplies heat to the (n + 2)-effect second-solution evaporator, and so on, until the secondary steam discharged from the (n + k - 1)-effect second-solution evaporator supplies heat to the (n + k)-effect second-solution evaporator. The secondary steam discharged from the (n + k)-effect second-solution evaporator enters the shell-and-tube condenser for condensation; The condensate process includes: The condensate of the first-effect wastewater evaporator enters the first-stage wastewater preheater to supply heat to it. After supplying heat to the first-stage wastewater preheater, it has the same temperature and pressure as the condensate of the second-effect wastewater evaporator, and together with the condensate of the second-effect wastewater evaporator and the condensate of the second-stage wastewater preheater, they enter the heater of the third-effect wastewater evaporator for flashing. The condensate of the third-effect wastewater evaporator and the condensate of the third-stage wastewater preheater enter the heater of the fourth-effect wastewater evaporator for flashing, and so on, until the condensate of the n-effect wastewater evaporator and the condensate of the n-stage wastewater preheater enter the heater of the (n + 1)-effect second-solution evaporator for flashing. The condensate of the (n + 1)-effect second-solution evaporator enters the heater of the (n + 2)-effect second-solution evaporator for flashing, and so on, until the condensate in the (n + k - 1)-effect second-solution evaporator enters the heater of the (n + k)-effect second-solution evaporator for flashing. The condensate in the heater of the (n + k)-effect second-solution evaporator enters the concentrate or crystal suspension heater to supply heat, and the condensate of the second-solution preheater also enters the concentrate or crystal suspension heater to supply heat. After the condensate in the concentrate or crystal suspension heater enters the condensate tank, it is discharged from the process through the condensate pump.

9. The combined super-efficient evaporation process for wastewater and the second solution according to claim 8, characterized in that, When the second solution is a high-concentration solution with the same components as the wastewater components, the second solution will become the carrier to help the compounds in the wastewater form crystals and precipitate. At this time, in the material process: After passing through the n-effect wastewater evaporator, the wastewater enters the (n + 1)-effect second-solution evaporator and performs evaporation crystallization together with the high-concentration second solution as the carrier. The second solution helps the compounds with the same components in the wastewater to precipitate, achieving the full recovery and zero discharge of the wastewater components in terms of total quantity balance; When the components of the wastewater and the second solution are different, at this time, in the material process: After passing through the n-effect wastewater evaporator, the wastewater is directly discharged from the process.

10. The combined super-efficient evaporation process for wastewater and the second solution according to claim 8, characterized in that, In the steam process: The steam source, together with the secondary steam in the third-effect wastewater evaporator sucked by the steam jet ejector, enters the heater of the first-effect wastewater evaporator as the heat source.

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