Negative-pressure ammonia distillation equipment for preparing high-concentration ammonia water by using low-grade heat energy and application method of negative-pressure ammonia distillation equipment

Abstract

The invention belongs to the technical field of coking chemical product recovery production, and particularly relates to negative pressure ammonia distillation equipment for preparing high-concentration ammonia water from low-grade heat energy and an application method. The device comprises a negative-pressure ammonia still, wherein a circulating heating assembly is arranged at the bottom of the negative-pressure ammonia still; the ammonia water storage tank is communicated with a reflux device at the upper part in the negative pressure ammonia still; the top end of the negative-pressure ammonia still is communicated with an ammonia inlet of the ammonia condensation cooler, an ammonia and ammonia water mixing outlet of the ammonia condensation cooler is communicated with an inlet of the vacuum circulation assembly, and an outlet of the vacuum circulation assembly is communicated with the ammonia water storage tank. The invention is used for solving the technical problems that a water ring vacuum unit used in the existing negative pressure ammonia distillation technology is easy to block, an adopted direct cooling tower needs low-temperature water for cooling, the energy consumption and the economic cost are high, and the ammonia water concentration of a product obtained by the existing ammonia distillation technology is lower.

Description

Technical Field

[0001] The invention belongs to the technical field of coking product recovery production, and specifically relates to negative pressure ammonia distillation equipment for preparing high-concentration ammonia water with low-grade thermal energy and an application method thereof. Background Art

[0002] The existing ammonia evaporation technology can be roughly divided into two technical routes, one is atmospheric pressure ammonia evaporation, and the other is negative pressure ammonia evaporation. The technical advantage of negative pressure ammonia evaporation is that its operating temperature is lower, and the corrosiveness of components such as ammonia water will be relatively reduced, so that the equipment can use some relatively cheap materials, such as 304 stainless steel, instead of 316 stainless steel or titanium alloy.

[0003] However, negative pressure ammonia evaporation also has its disadvantages, especially the negative pressure ammonia evaporation equipment using water ring vacuum unit. Because ammonia vapor contains naphthalene, the non-condensable vapor containing naphthalene will enter the water ring vacuum unit, and then condense into solid under low temperature environment, resulting in blockage of the heat exchanger pipeline of the water ring vacuum unit.

[0004] In addition, in the existing negative pressure ammonia evaporation process, some technical solutions use direct cooling towers, which require a large amount of low-temperature water (produced by refrigeration equipment) for multi-stage cooling, rather than general circulating water (natural cooling of cooling towers). The energy consumption and economic cost of low-temperature water are relatively high.

[0005] In addition, the ammonia concentration of the product produced by the current mature ammonia evaporation process is generally 8-12%, and the water content is very high, which has caused many restrictions on subsequent utilization and has low value. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a negative pressure ammonia distillation device and an application method for producing ammonia water with higher concentration using low-grade thermal energy, so as to solve the technical problems that the water ring vacuum unit used in the existing negative pressure ammonia distillation technology is easy to be blocked, the direct cooling tower used requires low-temperature water for cooling, the energy consumption and economic cost are high, and the product ammonia water concentration obtained by the existing ammonia distillation process is low. The technical solution of the present invention to solve the above technical problems is as follows: A negative pressure ammonia distillation device for producing high-concentration ammonia water with low-grade thermal energy comprises: A negative pressure ammonia distillation tower, wherein a circulating heating component is provided at the bottom of the negative pressure ammonia distillation tower; an ammonia water storage tank, the ammonia water storage tank being connected to a reflux device above the negative pressure ammonia distillation tower; The top of the negative pressure ammonia evaporation tower is connected to the ammonia vapor inlet of the ammonia vapor condenser cooler, the ammonia vapor and ammonia water mixed outlet of the ammonia vapor condenser cooler is connected to the inlet of the vacuum circulation component, and the outlet of the vacuum circulation component is connected to the ammonia water storage tank.

[0007] The present invention generates negative pressure on the ammonia vapor condensing cooler through a vacuum circulation component, sucks ammonia vapor at the top of the negative pressure ammonia evaporation tower, and the ammonia vapor after passing through the ammonia vapor condensing cooler circulates in the vacuum circulation component to obtain ammonia water, which is then sent to the top of the negative pressure ammonia evaporation tower for reflux spraying. If the cycle is repeated, the concentration of the obtained ammonia water is greatly improved to meet the use requirements.

[0008] Further: the vacuum cycle component comprises: A venturi ejector, the venturi ejector comprising a first concentrated ammonia water inlet, a first concentrated ammonia water outlet and a side port for ammonia vapor and ammonia water mixed suction; A vacuum cooler, the vacuum cooler comprising a second concentrated ammonia water inlet, a second concentrated ammonia water outlet, a low-temperature water inlet and a low-temperature water outlet; A vacuum circulation tank, wherein the vacuum circulation tank comprises a third concentrated ammonia water inlet, a third concentrated ammonia water outlet and a fourth concentrated ammonia water outlet; The second concentrated ammonia water outlet is connected to the first concentrated ammonia water inlet, the first concentrated ammonia water outlet is connected to the third concentrated ammonia water inlet, and the third concentrated ammonia water outlet is connected to the second concentrated ammonia water inlet; The concentrated ammonia fourth outlet is connected to the ammonia storage tank; The ammonia vapor and ammonia water mixing outlet of the ammonia vapor condensing cooler is communicated with the ammonia vapor and ammonia water mixing suction side interface.

[0009] The beneficial effect of adopting this step is as follows: the high-pressure concentrated ammonia water delivered by the vacuum circulation pump becomes a high-speed jet after passing through the injection port inside the ejector, forming a strong negative pressure area near the side interface of the ejector, and the ammonia vapor and ammonia water mixture from the ammonia vapor condensation cooler is sucked in from the ammonia vapor and ammonia water mixed suction side interface, recirculated to the vacuum circulation tank, and then enters the vacuum cooler from the vacuum circulation tank for cooling.

[0010] Furthermore: the ammonia vapor condensing cooler is a shell and tube heat exchanger, and the shell and tube heat exchanger is provided with a circulating water inlet and a circulating water outlet, as well as the ammonia vapor inlet and the ammonia vapor and ammonia water mixed outlet.

[0011] The beneficial effect of adopting this step is that the ammonia vapor is allowed to exchange heat with the circulating water once through the shell and tube heat exchanger, and then can enter the vacuum circulation component for subsequent purification.

[0012] Further: the circulating heating component includes: At least one circulating ammonia water heat exchanger, wherein the circulating ammonia water heat exchanger is provided with a circulating ammonia water pipeline and an ammonia distillation wastewater pipeline; The circulating ammonia water pipeline is externally connected to the cooling drum and flows to the coke oven; The inlet of the ammonia evaporation wastewater pipeline is connected to the bottom of the negative pressure ammonia evaporation tower, and the outlet of the ammonia evaporation wastewater pipeline is divided into two paths, one of which is refluxed to the negative pressure ammonia evaporation tower, and the other is discharged to the wastewater biochemical treatment system after being cooled.

[0013] Further: the circulating heating component includes: At least one group of upper heating sections of the gas horizontal tube primary cooler, wherein the upper heating section of the horizontal tube primary cooler is provided with an ammonia evaporation wastewater pipeline, and the gas at 75-82°C flows out of the ammonia evaporation wastewater pipeline; The inlet of the ammonia evaporation wastewater pipeline is connected to the bottom of the negative pressure ammonia evaporation tower, and the outlet of the ammonia evaporation wastewater pipeline is divided into two paths, one of which is refluxed to the negative pressure ammonia evaporation tower, and the other is discharged to the wastewater biochemical treatment system after being cooled.

[0014] The beneficial effects of adopting this step are: two different implementation methods of the circulating heating components; the temperature inside the negative pressure ammonia distillation tower is maintained by the circulating heating component to ensure the evaporation effect of the ammonia vapor.

[0015] Furthermore: a vacuum circulation pump is provided in the pipeline connecting the third ammonia vapor outlet and the second ammonia vapor inlet, and the lift range of the vacuum circulation pump is 75m-135m.

[0016] The beneficial effects of adopting this step are as follows: the vacuum circulation pump has a higher head, and the fluid it delivers has a higher pressure, which produces two effects. First, the higher-pressure fluid has the effect of flushing the pipe wall when passing through the pipeline, vacuum cooler and Venturi ejector, etc., to avoid blockage. Second, after the higher-pressure fluid passes through the injection port of the Venturi ejector, it can generate a larger negative pressure at the side interface where the ammonia vapor and ammonia water are mixed and inhaled, so that it has a strong vacuum extraction ability.

[0017] Furthermore: a group of parallel filters is provided in the pipeline connecting the second concentrated ammonia water outlet and the first concentrated ammonia water inlet.

[0018] The beneficial effect of adopting this step is that the filter is used to filter impurities in the fluid, such as condensed naphthalene.

[0019] Furthermore: the negative pressure ammonia distillation tower is a packed tower or a plate tower, and the packed tower or the plate tower includes a rectifying section and a stripping section.

[0020] The present invention also provides an application method of a negative pressure ammonia distillation device for producing ammonia water with higher concentration by using low-grade thermal energy, comprising the following steps: S1, injecting ammonia-containing wastewater into a negative pressure ammonia distillation tower, and supplying heat to the negative pressure ammonia distillation tower through a circulating heating component; S2, the vacuum circulation component works to draw the negative pressure ammonia evaporation tower and the ammonia vapor condensation cooler into a partial vacuum state, and the ammonia vapor condensation cooler draws mixed gas from the top of the negative pressure ammonia evaporation tower, and the mixed gas includes ammonia, water vapor and non-condensable steam; S3, the mixed gas is partially liquefied into a mixed liquid in the ammonia vapor condensing cooler; S4, the mixed liquid is circulated and cooled in the vacuum circulation component to form ammonia water, which flows into the ammonia water storage tank; S5. The ammonia water in the ammonia water storage tank is sent to the reflux device at the top of the negative pressure ammonia distillation tower, and the reflux ratio is 1.5-4.

[0021] Further: in S1, the ammonia-containing wastewater needs to be firstly added with a certain proportion of NaOH solution through a reaction tank or a pipeline mixer, mixed evenly, and then filtered, and then sent to the upper part of the negative pressure ammonia distillation tower; The concentration of the NaOH solution is 30-40%.

[0022] The vacuum circulation component is used to ensure that the negative pressure ammonia evaporation tower and the ammonia vapor condenser cooler are in a negative pressure state, so that the concentrated ammonia water is at a lower temperature, and the vacuum circulation component circulates and cools the extracted ammonia vapor and ammonia water mixture into ammonia water, which flows into the ammonia water storage tank. The ammonia water in the ammonia water storage tank is then sent to the top of the negative pressure ammonia evaporation tower for spraying and reflux concentration. After such a cycle, the ammonia water concentration in the ammonia water storage tank finally meets the design requirements.

[0023] The beneficial effects of the present invention are: 1. The present application re-injects the prepared ammonia water into the top of the negative pressure ammonia distillation tower for spray reflux, which can effectively improve the ammonia distillation effect, increase the product ammonia water concentration to more than 16%, and increase its value; 2. The vacuum circulation component uses a Venturi ejector instead of a water ring pump group to form a negative pressure environment. Not only can the Venturi ejector avoid being blocked by impurities such as naphthalene, but it can also effectively extend the stable operation time of the entire ammonia-containing wastewater treatment system. In addition, the negative pressure environment can also ensure that the entire system is in a low temperature state, which reduces the material requirements for the entire system and saves costs. 3. Using a shell and tube heat exchanger as an ammonia vapor condenser cooler, the ammonia vapor only needs to be cooled once, which reduces the temperature difference between the ammonia vapor in the negative pressure ammonia evaporation tower and the vacuum circulation component. Only the vacuum cooler in the vacuum circulation component uses a small amount of low-temperature water. This equipment uses cheap and easily available circulating water as the main refrigerant, reducing the use of high-value and high-energy-consuming low-temperature water as a refrigerant. 4. In terms of energy consumption, first of all, low-grade and low-exergy thermal energy will replace low-pressure steam, which can be circulating ammonia water or the thermal energy contained in the upper section of the coal gas in the cross-tube primary cooler; when using circulating ammonia water as a heat source, the existing circulating ammonia water pump in the cold drum process of the chemical product recovery workshop can be directly used as the circulating power source, and no new circulating pump is required, which further saves energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A schematic structural diagram of a negative pressure ammonia distillation device provided by the present invention; Figure 2 for Figure 1 Schematic diagram of the structure of the ammonia vapor condensing cooler and vacuum circulation components; Figure 3 for Figure 1 Schematic diagram of the structure of the medium-circulation heating component.

[0026] Reference numerals: 1-negative pressure ammonia evaporation tower; 2-ammonia water storage tank; 3-ammonia vapor condenser cooler; 4-Venturi ejector; 5-vacuum cooler; 6-vacuum circulation tank; 7-vacuum circulation pump; 8-filter; 9-circulating ammonia water heat exchanger; 11-Raw ammonia water inlet; 12-Steam inlet; 13-Reflux spray pipe; 31-Ammonia vapor inlet; 32-Ammonia water and ammonia vapor mixed outlet; 41-First concentrated ammonia water inlet; 42-First concentrated ammonia water outlet; 43-Ammonia vapor and ammonia water mixed suction side port; 51-Second concentrated ammonia water inlet; 52-Second concentrated ammonia water outlet; 53-Low-temperature water inlet; 54-Low-temperature water outlet; 61-Third concentrated ammonia water inlet; 62-Third concentrated ammonia water outlet; 63-Non-condensable steam breathing valve; 64-Fourth concentrated ammonia water outlet; A-circulating ammonia water; B-circulating water; C-low-temperature water; D-industrial water; E-low-pressure steam; F-evaporated ammonia wastewater; G-drainage outlet; H-tar; J-finished ammonia water discharge; K-non-condensable steam discharge to the exhaust gas system; L-wastewater biochemical treatment system. DETAILED DESCRIPTION

[0027] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention. It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0028] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0029] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the present invention, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0030] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0032] Example like Figure 1 As shown, the negative pressure ammonia distillation equipment provided by the present invention comprises: A negative pressure ammonia distillation tower 1, wherein a circulating heating component is provided at the bottom of the negative pressure ammonia distillation tower 1, and a raw ammonia water inlet 11 and a steam inlet 12 are provided on the tower body of the negative pressure ammonia distillation tower 1. The raw ammonia water evaporates in the negative pressure ammonia distillation tower 1, and the tar H generated at the bottom of the negative pressure ammonia distillation tower 1 is collected and sent to a coal yard or a tar tank; An ammonia water storage tank 2, wherein the ammonia water storage tank 2 is connected to a reflux device located above the negative pressure ammonia distillation tower 1, wherein the reflux device is a spray pipe 13, and the ammonia water storage tank 2 is also provided with an outlet to discharge the finished ammonia water J; The top of the negative pressure ammonia evaporation tower 1 is connected to the ammonia vapor inlet 31 of the ammonia vapor condensation cooler 3, the ammonia vapor and ammonia water mixed outlet 32 ​​of the ammonia vapor condensation cooler 3 is connected to the inlet of the vacuum circulation component, and the outlet of the vacuum circulation component is connected to the ammonia water storage tank 2.

[0033] The present invention generates negative pressure on the ammonia vapor condenser cooler 3 through a vacuum circulation component, sucks in ammonia vapor at the top of the negative pressure ammonia evaporation tower 1, and the ammonia vapor after passing through the ammonia vapor condenser cooler 3 circulates in the vacuum circulation component to obtain finished ammonia water, and then the finished ammonia water is sent to the top of the negative pressure ammonia evaporation tower 1 for spraying. If the cycle is repeated, the concentration of the obtained ammonia water is greatly improved and can meet the use requirements.

[0034] On the basis of the above technical solution, the vacuum cycle component comprises: A venturi ejector 4, the venturi ejector 4 comprising a concentrated ammonia first inlet 41, a concentrated ammonia first outlet 42 and a mixed ammonia vapor and ammonia aqueous solution inhalation side port 43; The vacuum cooler 5 comprises a concentrated ammonia water second inlet 51, a concentrated ammonia water second outlet 52, a low-temperature water inlet 53 and a low-temperature water outlet 54. The low-temperature water C enters the vacuum cooler 5 to reduce the temperature of the concentrated ammonia water inside to 18-26° C., so as to reduce the evaporation amount of the high-speed jet when evacuating the vacuum, and at the same time cool and condense the ammonia water and ammonia vapor from the ammonia vapor condensation cooler, reduce the volume of non-condensable vapor, and thus ensure that the vacuum degree of the system meets the standard; The vacuum circulation tank 6 includes a third concentrated ammonia water inlet 61, a third concentrated ammonia water outlet 62 and a fourth concentrated ammonia water outlet 64; the vacuum circulation tank 6 is also provided with a non-condensable steam breathing valve 63, and the non-condensable steam is discharged to the exhaust system K; The concentrated ammonia water second outlet 52 is connected to the concentrated ammonia water first inlet 41, the concentrated ammonia water first outlet 42 is connected to the concentrated ammonia water third inlet 61, and the concentrated ammonia water third outlet 62 is connected to the concentrated ammonia water second inlet 51. In the process of entering the vacuum cooler 5 from the vacuum circulation tank 6, when the system is started and debugged or when the liquid level in the circulation tank is low, industrial water D can also be connected to supplement water; The concentrated ammonia fourth outlet 64 is connected to the ammonia storage tank 2; The ammonia vapor and ammonia water mixing outlet 32 ​​of the ammonia vapor condensation cooler 3 is communicated with the ammonia vapor and ammonia water mixing suction bypass port 43 .

[0035] Ammonia gas is sucked from the ammonia gas and ammonia water mixed suction side port 43 of the venturi ejector 4, and driven by the internal jet flow, circulates to the vacuum circulation tank 6, and then enters the vacuum cooler 5 from the vacuum circulation tank 6 for cooling.

[0036] On the basis of the above technical solution, the ammonia vapor condensing cooler 3 is a shell and tube heat exchanger, which is provided with a circulating water inlet and a circulating water outlet, the circulating water B flows in from the circulating water inlet and flows out from the circulating water outlet, as well as the ammonia vapor inlet 31 and the ammonia vapor and ammonia water mixed outlet 32.

[0037] The ammonia vapor is allowed to exchange heat with circulating water through a shell and tube heat exchanger, and then enters the vacuum circulation component for subsequent purification.

[0038] On the basis of the above technical solution, the circulating heating component comprises: At least one circulating ammonia water heat exchanger 9 (in this case, only circulating ammonia water is used as the heat source for ammonia evaporation), wherein the circulating ammonia water heat exchanger 9 is provided with a circulating ammonia water pipeline and an ammonia evaporation wastewater pipeline; The circulating ammonia water pipeline is externally connected to the cold drum, and the circulating ammonia water A flows out of the cold drum and then flows to the coke oven; The inlet of the ammonia evaporation wastewater pipeline is connected to the bottom of the negative pressure ammonia evaporation tower 1, and the ammonia evaporation wastewater F enters the circulating ammonia water heat exchanger 9 and then flows out from the circulating ammonia water heat exchanger 9. The outlet of the ammonia evaporation wastewater pipeline is divided into two paths, one of which flows back to the negative pressure ammonia evaporation tower 1, and the other is sent to the wastewater biochemical treatment system L after cooling.

[0039] The temperature at the bottom of the negative pressure ammonia distillation tower 1 is maintained by a circulating heating component to ensure the evaporation effect of the ammonia vapor.

[0040] In addition, the circulating ammonia water A can also enter the ammonia vapor condenser cooler 3 as hot flushing water, and be discharged into the sewage outlet G after use; low-pressure steam E can also be connected to this hot flushing pipeline, and low-pressure steam can be used to clean each pipeline during shutdown.

[0041] In this embodiment, another embodiment of a circulating heating component is provided, wherein the circulating heating component comprises: At least one group of upper heating sections of the gas horizontal tube primary cooler, wherein the upper heating section of the horizontal tube primary cooler is provided with an ammonia evaporation wastewater pipeline, and the gas at 75-82°C flows out of the ammonia evaporation wastewater pipeline; The inlet of the ammonia evaporation wastewater pipeline is connected to the bottom of the negative pressure ammonia evaporation tower, and the outlet of the ammonia evaporation wastewater pipeline is divided into two paths, one of which is refluxed to the negative pressure ammonia evaporation tower, and the other is discharged to the wastewater biochemical treatment system L after being cooled.

[0042] On the basis of the above technical solution, a vacuum circulation pump 7 is provided in the pipeline connecting the third concentrated ammonia water outlet 62 and the second concentrated ammonia water inlet 51, and the head of the vacuum circulation pump 7 ranges from 75m to 135m. The vacuum circulation pump 7 has a relatively high head, and the fluid it delivers has a relatively high pressure, which produces two effects. First, the relatively high-pressure fluid has the effect of flushing the pipe wall when passing through the pipeline, vacuum cooler 5 and venturi ejector 4, etc., to avoid blockage. Second, when the relatively high-pressure fluid passes through the venturi ejector 4, it can generate a relatively large negative pressure at the ammonia vapor and ammonia water mixed suction side interface 43, so that it has a strong vacuum extraction ability.

[0043] On the basis of the above technical solution, a set of parallel filters 8 is provided in the pipeline connecting the concentrated ammonia water second outlet 52 and the concentrated ammonia water first inlet 41, including at least two sets of filters 8, one for use and one for backup.

[0044] The filter 8 is used to filter impurities in the fluid, such as desublimated naphthalene.

[0045] On the basis of the above technical solution, the negative pressure ammonia distillation tower is a packed tower or a plate tower, and the packed tower or the plate tower includes a rectifying section and a stripping section.

[0046] The present invention also provides an application method of the negative pressure ammonia distillation equipment, comprising the following steps: S1, injecting raw materials, i.e., ammonia-containing wastewater, into the negative pressure ammonia distillation tower 1. The ammonia-containing wastewater needs to be firstly added with a certain proportion of 30-40% NaOH solution through a reaction tank or a pipeline mixer, mixed evenly, and then filtered, and then sent to the upper middle part of the negative pressure ammonia distillation tower, and heat is supplied to the negative pressure ammonia distillation tower 1 through a circulating heating component; S2, the vacuum circulation component works to draw the negative pressure ammonia evaporation tower 1 and the ammonia vapor condensation cooler 3 into a vacuum state, and the ammonia vapor condensation cooler 3 draws mixed gas from the top of the negative pressure ammonia evaporation tower 1, and the mixed gas includes ammonia, water vapor and non-condensable steam; S3, the mixed gas is partially liquefied into a mixed liquid in the ammonia vapor condensing cooler 3; S4, the mixed liquid is circulated and cooled in the vacuum circulation component, most of which forms ammonia water and flows into the ammonia water storage tank 2, and a small part is non-condensable steam; S5, the ammonia water in the ammonia water storage tank 2 is sent to the top of the negative pressure ammonia evaporation tower 1 for spray reflux, and the reflux ratio is 1.5-4, that is, the ratio of the concentrated ammonia water refluxed from the ammonia water storage tank 2 to the spray pipe 13 to the ammonia vapor at the top of the negative pressure ammonia evaporation tower 1 is 1.5-4, so as to increase the concentration of the product ammonia water; S6, most of the ammonia evaporation wastewater is used for circulating heat exchange to provide heat source for the ammonia evaporation system, and a small part is discharged to the biochemical wastewater treatment system after cooling; S7, the non-condensable steam is sent to the tail gas treatment system; S8. The ammonia nitrogen in the ammonia-containing wastewater treated by the method can be reduced to below 200 mg / L, and the concentration of the product concentrated ammonia water can reach more than 16%.

[0047] The vacuum circulation component is used to ensure that the negative pressure ammonia evaporation tower 1 and the ammonia vapor condenser cooler 3 are in a negative pressure state, so that the ammonia vapor is at a lower temperature, and the vacuum circulation component circulates and cools the extracted ammonia vapor to become ammonia water, which flows into the ammonia water storage tank 2. The ammonia water in the ammonia water storage tank 2 is then sent to the top of the negative pressure ammonia evaporation tower 1 for reflux spraying. After such a cycle, the ammonia water concentration in the ammonia water storage tank 2 finally meets the design requirements.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. Negative pressure ammonia distillation equipment for producing high concentration ammonia water with low-grade thermal energy, characterized in that: include: A negative pressure ammonia distillation tower, wherein a circulating heating component is provided at the bottom of the negative pressure ammonia distillation tower; an ammonia water storage tank, the ammonia water storage tank being connected to a reflux device above the negative pressure ammonia distillation tower; The top of the negative pressure ammonia evaporation tower is connected to the ammonia vapor inlet of the ammonia vapor condenser cooler, the ammonia vapor and ammonia water mixed outlet of the ammonia vapor condenser cooler is connected to the inlet of the vacuum circulation component, and the outlet of the vacuum circulation component is connected to the ammonia water storage tank.

2. The negative pressure ammonia distillation equipment for producing high concentration ammonia water with low-grade thermal energy according to claim 1 is characterized in that: The vacuum cycle assembly comprises: A venturi ejector, the venturi ejector comprising a first concentrated ammonia water inlet, a first concentrated ammonia water outlet and a side port for ammonia vapor and ammonia water mixed suction; A vacuum cooler, the vacuum cooler comprising a second concentrated ammonia water inlet, a second concentrated ammonia water outlet, a low-temperature water inlet and a low-temperature water outlet; A vacuum circulation tank, the vacuum circulation tank comprising a third concentrated ammonia water inlet, a third concentrated ammonia water outlet, and a fourth concentrated ammonia water outlet; The second concentrated ammonia water outlet is connected to the first concentrated ammonia water inlet, the first concentrated ammonia water outlet is connected to the third concentrated ammonia water inlet, and the third concentrated ammonia water outlet is connected to the second concentrated ammonia water inlet; The concentrated ammonia fourth outlet is connected to the ammonia storage tank; The ammonia vapor and ammonia water mixing outlet of the ammonia vapor condensing cooler is communicated with the ammonia vapor and ammonia water mixing suction side interface.

3. The negative pressure ammonia distillation equipment for producing high concentration ammonia water with low-grade thermal energy according to claim 1 or 2, characterized in that: The ammonia vapor condensing cooler is a shell and tube heat exchanger, and the shell and tube heat exchanger is provided with a circulating water inlet and a circulating water outlet, as well as the ammonia vapor inlet and the ammonia vapor and ammonia water mixed outlet.

4. The negative pressure ammonia distillation equipment for producing high concentration ammonia water with low-grade thermal energy according to claim 1 is characterized in that: The circulating heating component comprises: At least one circulating ammonia water heat exchanger, wherein the circulating ammonia water heat exchanger is provided with a circulating ammonia water pipeline and an ammonia distillation wastewater pipeline; The circulating ammonia water pipeline is externally connected to the cooling drum and flows to the coke oven; The inlet of the ammonia evaporation wastewater pipeline is connected to the bottom of the negative pressure ammonia evaporation tower, and the outlet of the ammonia evaporation wastewater pipeline is divided into two paths, one of which is refluxed to the negative pressure ammonia evaporation tower, and the other is discharged to the wastewater biochemical treatment system after being cooled.

5. The negative pressure ammonia distillation equipment for producing high concentration ammonia water with low-grade thermal energy according to claim 1 is characterized in that: The circulating heating component comprises: At least one group of upper heating sections of the gas horizontal tube primary cooler, wherein the upper heating section of the horizontal tube primary cooler is provided with an ammonia evaporation wastewater pipeline, and the gas at 75-82°C flows out of the ammonia evaporation wastewater pipeline; The inlet of the ammonia evaporation wastewater pipeline is connected to the bottom of the negative pressure ammonia evaporation tower, and the outlet of the ammonia evaporation wastewater pipeline is divided into two paths, one of which is refluxed to the negative pressure ammonia evaporation tower, and the other is discharged to the wastewater biochemical treatment system after being cooled.

6. The negative pressure ammonia distillation equipment for producing high concentration ammonia water with low-grade thermal energy according to claim 2 is characterized in that: A vacuum circulation pump is arranged in the pipeline connecting the third concentrated ammonia water outlet and the second concentrated ammonia water inlet, and the lift range of the vacuum circulation pump is 75m-135m.

7. The negative pressure ammonia distillation equipment for producing high concentration ammonia water with low-grade thermal energy according to claim 6 is characterized in that: A group of parallel filters is arranged in the pipeline connecting the second ammonia vapor outlet and the first ammonia vapor inlet.

8. The negative pressure ammonia distillation equipment for producing high concentration ammonia water with low-grade thermal energy according to claim 1 is characterized in that: The negative pressure ammonia distillation tower is a packed tower or a plate tower, and the packed tower or the plate tower comprises a rectifying section and a stripping section.

9. The method for applying a negative pressure ammonia distillation equipment to produce ammonia water with high concentration by using low-grade thermal energy is characterized in that: The following steps are involved: S1, injecting ammonia-containing wastewater into a negative pressure ammonia distillation tower, and supplying heat to the negative pressure ammonia distillation tower through a circulating heating component; S2, the vacuum circulation component works to draw the negative pressure ammonia evaporation tower and the ammonia vapor condensation cooler into a partial vacuum state, and the ammonia vapor condensation cooler draws mixed gas from the top of the negative pressure ammonia evaporation tower, and the mixed gas includes ammonia, water vapor and non-condensable steam; S3, the mixed gas is partially liquefied into a mixed liquid in the ammonia vapor condensing cooler; S4, the mixed liquid is circulated and cooled in the vacuum circulation component to form ammonia water, which flows into the ammonia water storage tank; S5. The ammonia water in the ammonia water storage tank is sent to the reflux device at the top of the negative pressure ammonia distillation tower, and the reflux ratio is 1.5-4.

10. The method for applying the negative pressure ammonia distillation equipment for producing high concentration ammonia water with low-grade thermal energy according to claim 9, characterized in that: In S1, the ammonia-containing wastewater needs to be first added with a certain proportion of NaOH solution through a reaction tank or a pipeline mixer, mixed evenly, and then filtered, and then sent to the upper part of the negative pressure ammonia distillation tower; The concentration of the NaOH solution is 30-40%.

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