CN118001768A - Ammonia distillation rectification system capable of improving liquid ammonia content and control method thereof - Google Patents
Ammonia distillation rectification system capable of improving liquid ammonia content and control method thereof Download PDFInfo
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- CN118001768A CN118001768A CN202410255492.2A CN202410255492A CN118001768A CN 118001768 A CN118001768 A CN 118001768A CN 202410255492 A CN202410255492 A CN 202410255492A CN 118001768 A CN118001768 A CN 118001768A
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- falling film
- film heat
- heat exchanger
- ammonia
- liquid
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 title claims abstract description 196
- 229910021529 ammonia Inorganic materials 0.000 title claims abstract description 86
- 238000000034 method Methods 0.000 title claims abstract description 21
- 238000004821 distillation Methods 0.000 title claims abstract description 20
- 239000011552 falling film Substances 0.000 claims abstract description 169
- 238000001704 evaporation Methods 0.000 claims abstract description 74
- 230000008020 evaporation Effects 0.000 claims abstract description 74
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 56
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims abstract description 28
- 235000011114 ammonium hydroxide Nutrition 0.000 claims abstract description 26
- 239000000463 material Substances 0.000 claims abstract description 18
- 238000010521 absorption reaction Methods 0.000 claims abstract description 12
- 239000012267 brine Substances 0.000 claims abstract description 10
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims abstract description 10
- 239000007788 liquid Substances 0.000 claims description 66
- 238000007906 compression Methods 0.000 claims description 45
- 230000006835 compression Effects 0.000 claims description 45
- 239000002994 raw material Substances 0.000 claims description 20
- 238000000926 separation method Methods 0.000 claims description 9
- 238000005086 pumping Methods 0.000 claims description 4
- 239000000243 solution Substances 0.000 claims description 4
- 238000004064 recycling Methods 0.000 claims description 3
- 238000003889 chemical engineering Methods 0.000 abstract description 2
- 239000012847 fine chemical Substances 0.000 abstract description 2
- 238000009834 vaporization Methods 0.000 abstract 1
- 230000008016 vaporization Effects 0.000 abstract 1
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 4
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 235000019738 Limestone Nutrition 0.000 description 1
- 238000009621 Solvay process Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000009615 deamination Effects 0.000 description 1
- 238000006481 deamination reaction Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000012452 mother liquor Substances 0.000 description 1
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 1
- 238000011112 process operation Methods 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
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- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
Abstract
The invention relates to the technical field of fine chemical engineering, in particular to an ammonia distillation rectification system capable of improving the content of liquid ammonia and a control method thereof. The system comprises a rectifying tower, a first falling film heat exchange system and a second falling film heat exchange system which are connected in sequence; the feed inlet of the rectifying tower is communicated with external material conveying equipment; the first falling film heat exchange system comprises a first falling film heat exchanger, a first evaporation chamber and a first MVR evaporation system, wherein the first evaporation chamber is communicated with the tube side of the first falling film heat exchanger, and the first MVR evaporation system is arranged at the output end of the first evaporation chamber; and is communicated with an air inlet of the rectifying tower; the second falling film heat exchange system comprises a second falling film heat exchanger, a second evaporation chamber and a second MVR evaporation system, wherein the second evaporation chamber is communicated with the tube side of the second falling film heat exchanger, and the second MVR evaporation system is arranged at the output end of the second evaporation chamber; and communicates with the first MVR vaporization system; the ammonia-containing steam sequentially flows through the shell passes of the first falling film heat exchanger and the second falling film heat exchanger from the top flow of the rectifying tower, exchanges heat with condensed water added in the tube pass of the first falling film heat exchanger and the second falling film heat exchanger, and separates condensed ammonia water to obtain high-concentration ammonia-containing steam which can flow to the brine absorption tower.
Description
Technical Field
The invention relates to the technical field of fine chemical engineering, in particular to an ammonia distillation rectification system capable of improving the content of liquid ammonia and a control method thereof.
Background
The ammonia-soda process for producing sodium carbonate uses limestone and salt as main raw materials, and ammonia is used as intermediate medium for cyclic use. The ammonia can be recycled in the production system by means of rectification of the hot mother liquor.
The rectification is a method for separating two substances by utilizing the difference of boiling points of the two substances and taking energy as a process driving force to perform partial condensation of mixed steam and partial evaporation of mixed liquid for a plurality of times, and the method can obtain a high-purity product by only providing energy and a cooling agent, is simple and mature in operation and is an effective means for separating various organic mixtures. In the prior art, mixed steam of ammonia and part of water in an ammonia distillation rectifying tower forms ammonia vapor which is stripped out from the top or the middle upper part side of the rectifying tower, and then enters a vapor compressor, and flows back to the rectifying tower after being pressurized and heated, so that the waste of ammonia is avoided, but part of ammonia still cannot be stripped out due to the reaction balance relation, and the circulation of the ammonia is limited to a certain extent.
In general rectifying operation, the condenser is arranged at the top of the tower to condense the steam at the top of the tower and then partially reflux the steam to be discharged out of the system, so that cooling water is needed as a cold source, and heat of the steam at the top of the tower is wasted. Because of the lower temperature and pressure of the overhead vapor, it is generally no longer possible to continue use as a heat source. This makes the whole rectification system energy-consuming.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is known to a person skilled in the art.
Disclosure of Invention
The technical problems to be solved by the invention are as follows: the ammonia distillation rectification system can improve the content of liquid ammonia, improve the concentration of output ammonia and avoid heat waste.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
An ammonia distillation rectification system capable of improving the content of liquid ammonia,
The system comprises a rectifying tower, a first falling film heat exchange system and a second falling film heat exchange system which are connected in sequence;
the feed inlet of the rectifying tower is communicated with external material conveying equipment;
the first falling film heat exchange system comprises a first falling film heat exchanger and a first MVR evaporation system, the first MVR evaporation system comprises a first evaporation chamber and a first vapor compression device, one end of the first falling film heat exchanger is provided with a condensed water inlet pipeline communicated with the tube side of the first falling film heat exchanger, an air outlet of the rectifying tower is communicated with the shell side of the first falling film heat exchanger, the first evaporation chamber is communicated with the tube side of the first falling film heat exchanger, and the first vapor compression device is arranged at the output end of the first evaporation chamber; and is communicated with an air inlet of the rectifying tower;
The second falling film heat exchange system comprises a second falling film heat exchanger and a second MVR evaporation system, the second MVR evaporation system comprises a second evaporation chamber and a second vapor compression device, one end of the second falling film heat exchanger is provided with a condensed water inlet pipeline communicated with the tube side of the second falling film heat exchanger, an air outlet of the shell side of the first falling film heat exchanger is communicated with the shell side of the second falling film heat exchanger, the second evaporation chamber is communicated with the tube side of the second falling film heat exchanger, and the second vapor compression device is arranged at the output end of the second evaporation chamber; and communicates with the first vapor compression device;
The ammonia-containing steam sequentially flows through the shell passes of the first falling film heat exchanger and the second falling film heat exchanger from the top flow of the rectifying tower, exchanges heat with condensed water added in the tube pass of the first falling film heat exchanger and the second falling film heat exchanger, and separates condensed ammonia water to obtain high-concentration ammonia-containing steam which can flow to the brine absorption tower.
Further, an ammonia water tank is communicated between the feed inlet of the rectifying tower and the shell side liquid outlet of the first falling film heat exchanger, and the shell side liquid outlet of the second falling film heat exchanger is communicated with the ammonia water tank.
Further, two ends of the tube side of the first falling film heat exchanger are communicated through a pipeline and are provided with a first circulating conveying pump for circulating and conveying liquid in the tube side;
The two ends of the tube side of the second falling film heat exchanger are communicated through a pipeline and are provided with a second circulating conveying pump for circulating and conveying liquid in the tube side.
Further, the first vapor compression device comprises a first vapor compressor A and a first vapor compressor B, the air outlet of the first evaporation chamber is communicated with the air inlet of the first vapor compressor A, the air outlet of the first vapor compressor A is communicated with the air inlet of the first vapor compressor B, the air outlet of the first vapor compressor B is communicated with the air inlet of the rectifying tower, and the technological process of primary falling film two-stage compression is realized in the first falling film heat exchange system.
Further, the second vapor compression device comprises a second vapor compressor, an air outlet of the second evaporation chamber is communicated with an air inlet of the second vapor compressor, an air outlet of the second vapor compressor is communicated with an air inlet of the first vapor compressor A, and a process flow of the second falling film three-stage compression is realized in the second falling film heat exchange system.
Further, the first MVR evaporation system further comprises a condenser and a condensate tank, a liquid outlet of the first vapor compressor B is communicated with a liquid inlet of the condenser, and a liquid outlet of the condenser is communicated with the condensate tank.
Further, a plate type preheater is arranged on the connecting pipeline of the rectifying tower and the equipment for conveying materials from outside, and comprises a raw material input port, a material output port, a steam input port, a steam output port and a condensate water output port; the equipment of outside transport material is connected with the raw materials input port, and the feed inlet and the material delivery outlet of rectifying column are connected, and on the connecting line of the liquid outlet of first vapor compressor B and the liquid outlet of condenser, the steam input port and the steam delivery outlet of flow through plate heater preheat the raw materials, and the comdenstion water delivery outlet sets up on the connecting line of the liquid outlet of condenser and condensate tank.
The second technical problem to be solved by the invention is as follows: the control method of the ammonia distillation rectification system can improve the content of liquid ammonia, improve the concentration of output ammonia and avoid heat waste.
A control method of an ammonia distillation rectification system capable of improving the content of liquid ammonia comprises the following steps:
s1, pumping a raw material solution into a rectifying tower; simultaneously, delivering primary fresh steam to a rectifying tower, separating gas from liquid by the rectifying tower after heat exchange, and enabling the tower top ammonia-containing steam to enter a shell side of a first falling film heat exchanger;
S2, delivering condensed water with the temperature of more than 75 ℃ to a tube side of the first falling film heat exchanger, exchanging heat with ammonia-containing steam in a shell side of the first falling film heat exchanger, introducing liquid generated in the shell side after heat exchange into an ammonia water tank through the bottom of the first falling film heat exchanger, and allowing the rest ammonia-containing steam to enter the shell side of the second falling film heat exchanger; part of liquid in the tube pass enters a first evaporation chamber to be heated and evaporated, the evaporated steam enters a first steam compression device, and the steam is subjected to primary falling film secondary compression to raise the temperature of the steam to 106 ℃ and then enters a rectifying tower as fresh steam;
S3, delivering condensed water with the temperature of more than 70 ℃ to a tube side of the second falling film heat exchanger, exchanging heat with ammonia-containing steam in a shell side of the second falling film heat exchanger, introducing liquid generated in the shell side after heat exchange into an ammonia water tank through the bottom of the second falling film heat exchanger, and introducing the rest high-concentration ammonia-containing steam into a salt water absorption tower; and part of liquid in the tube pass enters a second evaporation chamber to be heated and evaporated, the evaporated steam enters a second vapor compression device, the temperature of the steam is increased to 106 ℃ through the second-stage falling film three-stage compression, and the steam is mixed with gas compressed by a first vapor compressor and enters a rectifying tower as fresh steam.
Further, the ammonia water tank conveys the liquid into a feed inlet of the rectifying tower for recycling separation again.
Further, in step S2, the heat exchange time is controlled by controlling the flow of the condensed water, so that the ammonia-containing steam in the shell side after heat exchange is reserved for a long enough time in the first falling film heat exchanger.
Further, the condensed water after the gas-liquid separation of the first evaporation chamber is conveyed to the tube side of the first falling film heat exchanger, and then the condensed water is circularly conveyed in the first falling film heat exchanger by the first circulating conveying pump;
And the condensed water after the gas-liquid separation of the second evaporation chamber is conveyed to the tube side of the second falling film heat exchanger, and the condensed water is circularly conveyed in the second falling film heat exchanger by a second circulating conveying pump.
The beneficial effects of the invention are as follows:
According to the invention, the first falling film heat exchange system and the second falling film heat exchange system are sequentially connected with the rectifying tower, so that the ammonia-containing steam sequentially exchanges heat between the shell passes of the first falling film heat exchanger and the second falling film heat exchanger and condensed water introduced into the tube passes, and the condensed ammonia water is separated to obtain high-concentration ammonia-containing steam which can flow to the brine absorption tower. Meanwhile, the first MVR evaporation system and the second MVR evaporation system are used for compressing the water with higher temperature in the tube pass of the first falling film heat exchanger and the second falling film heat exchanger to 106 ℃ and then introducing the water into the rectifying tower, so that heat is recovered on the basis of improving the concentration of ammonia-containing steam, and the production cost can be greatly reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present invention, and other drawings may be obtained according to the drawings without inventive effort to those skilled in the art.
FIG. 1 is a schematic diagram of an ammonia distillation rectification system capable of increasing the liquid ammonia content in an embodiment of the invention;
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments.
It will be understood that when an element is referred to as being "fixed to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
An ammonia distillation rectification system capable of improving the content of liquid ammonia as shown in fig. 1 comprises a rectification tower 10, a first falling film heat exchange system 20 and a second falling film heat exchange system 30 which are connected in sequence; the invention adopts the first falling film heat exchange system 20 and the second falling film heat exchange system 30 to recycle the heat at the top of the tower, the material liquid at the bottom of the tower is subjected to 2 times of flash evaporation to recycle the heat by the original device, the ammonia-containing and carbon dioxide vapor enters the absorption tower of the original device to recycle, and the ammonia content after deamination is not higher than the level of the original device.
The feed inlet of the rectifying tower 10 is communicated with an external material conveying device 001;
the first falling film heat exchange system 20 comprises a first falling film heat exchanger 21 and a first MVR evaporation system, the first MVR evaporation system comprises a first evaporation chamber 22 and a first vapor compression device 23, one end of the first falling film heat exchanger 21 is provided with a condensed water inlet pipeline 002 communicated with the tube side of the first falling film heat exchanger, an air outlet of the rectifying tower 10 is communicated with the shell side of the first falling film heat exchanger 21, the first evaporation chamber 22 is communicated with the tube side of the first falling film heat exchanger 21, and the first vapor compression device 23 is arranged at the output end of the first evaporation chamber 22; and is communicated with an air inlet of the rectifying tower 10;
The second falling film heat exchange system 30 comprises a second falling film heat exchanger 31 and a second MVR evaporation system, the second MVR evaporation system comprises a second evaporation chamber 32 and a second vapor compression device 33, one end of the second falling film heat exchanger 31 is provided with a condensed water inlet pipeline 003 communicated with the tube side of the second falling film heat exchanger, an air outlet of the shell side of the first falling film heat exchanger 21 is communicated with the shell side of the second falling film heat exchanger 31, the second evaporation chamber 32 is communicated with the tube side of the second falling film heat exchanger 31, and the second vapor compression device 33 is arranged at the output end of the second evaporation chamber 32; and communicates with the first vapor compression device 23;
The ammonia-containing steam sequentially flows through the shell passes of the first falling film heat exchanger 21 and the second falling film heat exchanger 31 from the top flow of the rectifying tower 10, exchanges heat with condensed water added in the tube pass of the falling film heat exchanger, and separates condensed ammonia water to obtain high-concentration ammonia-containing steam which can flow to the brine absorption tower. In addition, in order to facilitate the actual process operation requirement and realize the switching of working procedure operations such as rectification, falling film heat exchange, mechanical compression and the like, control valves are arranged on pipelines in the system by default.
In specific use, the external material conveying equipment preheats raw materials with ammonia content of about 7.3% to 101 ℃ through the plate type preheater 26, then conveys the raw materials into the rectifying tower 10 through the feeding port, meanwhile, fresh steam with the temperature of 106 ℃ is conveyed into the rectifying tower 10 through the air inlet by the external equipment, the fresh steam exchanges heat with the raw materials, ammonia is separated into steam and conveyed into the shell side of the first falling film heat exchanger 21, condensed water with the temperature of more than 76 ℃ is added into the tube side of the first falling film heat exchanger 21, liquid is circularly conveyed in the first falling film heat exchanger 21 through the first circulating conveying pump 211, the temperature of the ammonia-containing steam at the air outlet of the rectifying tower 10 is 84 ℃, heat exchange is carried out on the ammonia-containing steam with the liquid with the temperature of 76 ℃ circularly conveyed in the shell side, and the ammonia-containing steam with the temperature of 84 ℃ is condensed, and meanwhile, 76 ℃ hot water is converted into 76 ℃ saturated water steam. The cold and hot fluid has a temperature difference of 8 ℃, ammonia-containing steam with the concentration of 41.2% and the temperature of 76 ℃ is obtained, the ammonia-containing steam is then introduced into the shell side of the second falling film heat exchanger 31, condensed water with the temperature of more than 70 ℃ is added into the tube side of the second falling film heat exchanger 31, the liquid is circularly conveyed in the second falling film heat exchanger 31 through the second circulating conveying pump 311, heat exchange is carried out between the liquid and the ammonia-containing steam with the temperature of 76 ℃ and the concentration of 41.2%, and meanwhile, the ammonia-containing steam with the temperature of 76 ℃ is converted into 70 ℃ saturated water steam. The cold and hot fluid has a temperature difference of 6 ℃ to obtain ammonia-containing steam with the concentration of 49.9% and the temperature of 70 ℃, and then the ammonia-containing steam is conveyed to a brine absorption tower by a pipeline. According to the invention, through the simultaneous action of the first falling film heat exchanger 21 and the second falling film heat exchanger 31, less ammonia is condensed into ammonia solution, and the ammonia solution enters the ammonia water tank 40 through the liquid outlet at the bottom of the shell side on the first falling film heat exchanger 21 or the second falling film heat exchanger 31, so that the ammonia content of ammonia-containing steam entering the brine absorption tower is improved. At this time, the ammonia water tank 40 again feeds the ammonia-containing liquid into the feed port of the rectifying column 10 and separates the ammonia-containing liquid.
It should be noted here that the following reactions are involved in the shell side of the falling film heat exchanger:
CO2+H2O→H2CO3 (1)
NH3+H2O→NH3.H2O (2)
H2CO3+2NH3.H2O→(NH4)2CO3 (3)
In the ammonia-containing steam, because the NH4 + and the CO 3 2- are hydrolyzed to form CO 2 and NH 3 mostly, and the CO 2 has larger solubility in ammonia water and does not overflow, a small amount of the ammonia-containing steam is generated (NH 4)2CO3, the temperature of the ammonia-containing steam at the outlet of the rectifying tower 10 is 84 ℃, so that the heat exchange at a higher temperature is required, and the higher temperature is, the more obvious the carbonic acid decomposition is, so that the higher temperature is required to be kept, the less carbonic acid intermediate can be obtained, and therefore, more water can be condensed in the first falling film heat exchange system 20 instead of participating in the reaction.
According to the application, the first falling film heat exchange system 20 and the second falling film heat exchange system 30 are sequentially connected with the rectifying tower 10, so that the ammonia-containing steam sequentially exchanges heat with condensed water introduced into the shell side and the tube side of the first falling film heat exchanger 21 and the second falling film heat exchanger 31, and the condensed ammonia water is separated to obtain high-concentration ammonia-containing steam capable of flowing to the brine absorption tower. Meanwhile, the first MVR evaporation system and the second MVR evaporation system are used for compressing the water with higher temperature in the tube passes of the first falling film heat exchanger 21 and the second falling film heat exchanger 31 to 106 ℃ again, and the water is introduced into the rectifying tower 10, so that the heat is recovered on the basis of improving the concentration of ammonia-containing steam, and the production cost can be greatly reduced. Specifically, the first falling film heat exchanger 21 needs to be supplemented with >75 degrees of condensed water by about 18.73 tons/hour, the second falling film heat exchanger 31 needs to be supplemented with >70 degrees of condensed water by about 7.9 tons/hour, and the first vapor compression device 23 and the second vapor compression device 33 need to be supplemented with condensed water by about 2.5 tons/hour. The average system cost per ton of raw materials is 20.73 yuan/ton calculated by the price of 0.69 yuan/KWh of electricity and 211.47 yuan/ton of steam, and the whole process from feeding to discharging is included. The electricity consumption is less than 9.4KW (-6.49 yuan) for each ton of raw materials, 0.12 ton (-1.2 yuan) of condensed water is added, 0.12T (25.38 yuan) of steam is saved, 17.69 yuan for each ton of raw materials is saved, and the annual income is about 3396 ten thousand.
Specific system design parameters are shown in table 1 below:
| Sequence number | Technical index | Design parameters |
| 1 | Height of the apparatus | Less than or equal to 30 meters |
| 2 | Raw material feed concentration | About 7.1% (based on NH 3 content) |
| 3 | Feed temperature | ≥75℃ |
| 4 | Feed amount | 240T/h |
| 5 | Evaporation capacity | About 26.619T/h |
| 6 | Stripping temperature | 77～106℃ |
And a part of the liquid with the temperature of more than 76 ℃ in the upper tube side of the first falling film heat exchanger 21 enters the first evaporation chamber 22 for heating and evaporation, the evaporated steam enters the first vapor compression device 23 for compressing the steam to the temperature of 106 ℃ and is used as fresh steam to enter the rectifying tower 10 for reuse, a part of the liquid with the temperature of more than 70 ℃ in the upper tube side of the second falling film heat exchanger 31 enters the second evaporation chamber 32 for heating and evaporation, the evaporated steam enters the second vapor compression device 33 for compressing the steam to the temperature of 106 ℃ and is used as fresh steam to enter the rectifying tower 10 for reuse, and redundant water of the first falling film heat exchanger 21 and the second falling film heat exchanger 31 is better utilized through multiple evaporation and compression, so that the usage amount of primary steam is reduced.
An ammonia water tank 40 is communicated between the feed inlet of the rectifying tower 10 and the shell side liquid outlet of the first falling film heat exchanger 21, and the shell side liquid outlet of the second falling film heat exchanger 31 is communicated with the ammonia water tank 40. An ammonia water pump 41 is arranged on a connecting pipeline between the ammonia water tank 40 and the rectifying tower 10 and is used for pumping liquid in the ammonia water tank 40 into the rectifying tower 10.
The two ends of the tube side of the first falling film heat exchanger 21 are communicated through a pipeline and are provided with a first circulating and conveying pump 211 for circulating and conveying the liquid in the tube side; the condensed water after gas-liquid separation in the first evaporation chamber 22 is conveyed to the tube side of the first falling film heat exchanger 21, and then the condensed water is circularly conveyed in the first falling film heat exchanger 21 by the first circulating conveying pump 211; two ends of the tube side of the second falling film heat exchanger 31 are communicated through a pipeline and are provided with a second circulating and conveying pump 311 for circulating and conveying liquid in the tube side. The condensed water after the gas-liquid separation in the second evaporation chamber 32 is conveyed to the tube side of the second falling film heat exchanger 31, and the condensed water is circularly conveyed in the second falling film heat exchanger 31 by the second circulating conveying pump 311.
The first vapor compression device 23 comprises a first vapor compressor A231 and a first vapor compressor B232, the air outlet of the first evaporation chamber 22 is communicated with the air inlet of the first vapor compressor A231, the air outlet of the first vapor compressor A231 is communicated with the air inlet of the first vapor compressor B232, the air outlet of the first vapor compressor B232 is communicated with the air inlet of the rectifying tower 10, and the process flow of primary falling film two-stage compression is realized in the first falling film heat exchange system 20.
The second vapor compression device 33 includes a second vapor compressor 331, an air outlet of the second evaporation chamber 32 is communicated with an air inlet of the second vapor compressor 331, an air outlet of the second vapor compressor 331 is communicated with an air inlet of the first vapor compressor a231, and a process flow of the second falling film three-stage compression is realized in the second falling film heat exchange system 30.
The first MVR evaporation system further comprises a condenser 24 and a condensate tank 25, wherein a liquid outlet of the first vapor compressor B232 is communicated with a liquid inlet of the condenser 24, and a liquid outlet of the condenser 24 is communicated with the condensate tank 25.
The connecting pipeline of the rectifying tower 10 and the external material conveying device 001 is also provided with a plate type preheater 26, and the plate type preheater 26 comprises a raw material input port, a material output port, a steam input port, a steam output port and a condensate water output port; the equipment 001 for conveying materials from the outside is connected with a raw material input port, a feed inlet of the rectifying tower 10 is connected with a material output port, a liquid outlet of the first vapor compressor B232 is connected with a liquid outlet of the condenser 24, raw materials are preheated through a vapor input port and a vapor output port of the plate type preheater 26, and a condensed water output port is arranged on a liquid outlet of the condenser 24 and a connecting pipeline of the condensed water tank 25.
A control method of an ammonia distillation rectification system capable of improving the content of liquid ammonia comprises the following steps:
s1, pumping a raw material solution into a rectifying tower 10; simultaneously, fresh steam is conveyed to the rectifying tower 10 once, the rectifying tower 10 separates gas from liquid after heat exchange, and the tower top ammonia-containing steam enters the shell pass of the first falling film heat exchanger 21;
S2, delivering condensed water with the temperature of more than 75 ℃ to a tube side of the first falling film heat exchanger 21, exchanging heat with ammonia-containing steam in a shell side of the first falling film heat exchanger 21, introducing liquid generated in the shell side after heat exchange into an ammonia water tank 40 through the bottom of the first falling film heat exchanger 21, and introducing the rest ammonia-containing steam into the shell side of the second falling film heat exchanger 31; part of liquid in the tube pass enters a first evaporation chamber 22 for heating and evaporation, vaporized steam enters a first vapor compression device 23, and after primary falling film secondary compression, the temperature of the steam is increased to 106 ℃ and then enters a rectifying tower 10 as fresh steam; the heat exchange time is controlled by controlling the flow of the condensed water so that the ammonia-containing steam in the shell side after heat exchange is reserved for a sufficient time in the first falling film heat exchanger 21.
S3, delivering condensed water with the temperature of more than 70 ℃ to a tube side of the second falling film heat exchanger 31, exchanging heat with ammonia-containing steam in a shell side of the second falling film heat exchanger 31, introducing liquid generated in the shell side after heat exchange into an ammonia water tank 40 through the bottom of the second falling film heat exchanger 31, and introducing the rest high-concentration ammonia-containing steam into a brine absorption tower; part of liquid in the tube pass enters the second evaporation chamber 32 for heating and evaporation, the evaporated steam enters the second vapor compression device 33, the temperature of the steam is increased to 106 ℃ through the second-stage falling film three-stage compression, and the steam is mixed with the gas compressed by the first vapor compressor and enters the rectifying tower 10 as fresh steam. The ammonia water tank 40 conveys the liquid into the feed inlet of the rectifying tower 10 for recycling separation again.
It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (10)
1. Can improve ammonia distillation rectification system of liquid ammonia content, its characterized in that:
the system comprises a rectifying tower, a first falling film heat exchange system and a second falling film heat exchange system which are connected in sequence;
The feed inlet of the rectifying tower is communicated with external material conveying equipment;
The first falling film heat exchange system comprises a first falling film heat exchanger and a first MVR evaporation system, the first MVR evaporation system comprises a first evaporation chamber and a first vapor compression device, one end of the first falling film heat exchanger is provided with a condensed water inlet pipeline communicated with the tube side of the first falling film heat exchanger, an air outlet of the rectifying tower is communicated with the shell side of the first falling film heat exchanger, the first evaporation chamber is communicated with the tube side of the first falling film heat exchanger, and the first vapor compression device is arranged at the output end of the first evaporation chamber; and is communicated with an air inlet of the rectifying tower;
The second falling film heat exchange system comprises a second falling film heat exchanger and a second MVR evaporation system, the second MVR evaporation system comprises a second evaporation chamber and a second vapor compression device, one end of the second falling film heat exchanger is provided with a condensed water inlet pipeline communicated with the tube side of the second falling film heat exchanger, an air outlet of the shell side of the first falling film heat exchanger is communicated with the shell side of the second falling film heat exchanger, the second evaporation chamber is communicated with the tube side of the second falling film heat exchanger, and the second vapor compression device is arranged at the output end of the second evaporation chamber; and communicates with the first vapor compression device;
The ammonia-containing steam sequentially flows through the shell passes of the first falling film heat exchanger and the second falling film heat exchanger from the top flow of the rectifying tower, exchanges heat with condensed water added in the tube pass of the first falling film heat exchanger and the second falling film heat exchanger, and separates condensed ammonia water to obtain high-concentration ammonia-containing steam which can flow to the brine absorption tower.
2. The ammonia distillation and rectification system capable of improving the content of liquid ammonia according to claim 1, wherein an ammonia tank is communicated between a feed inlet of the rectification tower and a shell side liquid outlet of the first falling film heat exchanger, and a shell side liquid outlet of the second falling film heat exchanger is communicated with the ammonia tank.
3. The ammonia distillation and rectification system capable of increasing the content of liquid ammonia according to claim 2, wherein two ends of the tube side of the first falling film heat exchanger are communicated through a pipeline and are provided with a first circulating conveying pump for circulating and conveying the liquid in the tube side;
And two ends of the tube side of the second falling film heat exchanger are communicated through a pipeline and are provided with a second circulating conveying pump for circulating and conveying liquid in the tube side.
4. The ammonia distillation system capable of improving the content of liquid ammonia according to any one of claims 2-3, wherein the first vapor compression device comprises a first vapor compressor A and a first vapor compressor B, an air outlet of the first evaporation chamber is communicated with an air inlet of the first vapor compressor A, an air outlet of the first vapor compressor A is communicated with an air inlet of the first vapor compressor B, an air outlet of the first vapor compressor B is communicated with an air inlet of the rectifying tower, and a process flow of primary falling film two-stage compression is realized in the first falling film heat exchange system.
5. The ammonia distillation system capable of increasing the content of liquid ammonia according to claim 4, wherein the second vapor compression device comprises a second vapor compressor, an air outlet of the second vapor compressor is communicated with an air inlet of the first vapor compressor A, and a process flow of the second falling film three-stage compression is realized in the second falling film heat exchange system.
6. The ammonia still rectification system capable of increasing liquid ammonia content according to claim 5, wherein said first MVR evaporation system further comprises a condenser and a condensate tank, a liquid outlet of said first vapor compressor B is connected to a liquid inlet of said condenser, and a liquid outlet of said condenser is connected to said condensate tank.
7. The ammonia distillation and rectification system capable of increasing the content of liquid ammonia according to claim 6, wherein a plate type preheater is further arranged on a connecting pipeline of the rectification column and an external material conveying device, and comprises a raw material input port, a material output port, a steam input port, a steam output port and a condensate water output port; the equipment of outside transport material with the raw materials input port is connected, the feed inlet of rectifying column with the material delivery outlet is connected, first vapor compressor B's liquid outlet with the connecting line of the liquid outlet of condenser, flow through the steam input port and the steam delivery outlet of plate heater preheat the raw materials, the comdenstion water delivery outlet sets up the liquid outlet of condenser with the connecting line of condensate tank.
8. A control method of an ammonia distillation rectification system capable of improving the content of liquid ammonia is characterized by comprising the following steps:
s1, pumping a raw material solution into a rectifying tower; simultaneously, delivering primary fresh steam to a rectifying tower, separating gas from liquid by the rectifying tower after heat exchange, and enabling the tower top ammonia-containing steam to enter a shell side of a first falling film heat exchanger;
s2, conveying condensed water with the temperature of more than 75 ℃ to a tube side of the first falling film heat exchanger, exchanging heat with ammonia-containing steam in a shell side of the first falling film heat exchanger, introducing liquid generated in the shell side after heat exchange into an ammonia water tank through the bottom of the first falling film heat exchanger, and allowing the rest ammonia-containing steam to enter the shell side of the second falling film heat exchanger; part of liquid in the tube pass enters a first evaporation chamber to be heated and evaporated, the evaporated steam enters a first steam compression device, and the steam is subjected to primary falling film secondary compression to raise the temperature of the steam to 106 ℃ and then enters a rectifying tower as fresh steam;
S3, delivering condensed water with the temperature of more than 70 ℃ to a tube side of the second falling film heat exchanger, exchanging heat with ammonia-containing steam in a shell side of the second falling film heat exchanger, introducing liquid generated in the shell side after heat exchange into an ammonia water tank through the bottom of the second falling film heat exchanger, and enabling the rest high-concentration ammonia-containing steam to enter a brine absorption tower; and part of liquid in the tube pass enters a second evaporation chamber to be heated and evaporated, the evaporated steam enters a second vapor compression device, the temperature of the steam is increased to 106 ℃ through the second-stage falling film three-stage compression, and the steam is mixed with gas compressed by a first vapor compressor and enters a rectifying tower as fresh steam.
9. The method for controlling an ammonia still rectification system capable of increasing liquid ammonia content as recited in claim 8, wherein the ammonia tank conveys liquid into the feed inlet of the rectification column for recycling separation.
10. The control method of an ammonia distillation rectification system capable of increasing the content of liquid ammonia according to claim 8, wherein condensed water after gas-liquid separation in a first evaporation chamber is conveyed to a tube side of the first falling film heat exchanger, and then the condensed water is circularly conveyed in the first falling film heat exchanger by a first circulating conveying pump;
and the condensed water after gas-liquid separation in the second evaporation chamber is conveyed to the tube side of the second falling film heat exchanger, and the condensed water is circularly conveyed in the second falling film heat exchanger by a second circulating conveying pump.
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| CN202410255492.2A CN118001768A (en) | 2024-03-06 | 2024-03-06 | Ammonia distillation rectification system capable of improving liquid ammonia content and control method thereof |
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| CN202410255492.2A CN118001768A (en) | 2024-03-06 | 2024-03-06 | Ammonia distillation rectification system capable of improving liquid ammonia content and control method thereof |
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