CN110975312B - MVR evaporation device and evaporation method for efficient energy recovery - Google Patents
MVR evaporation device and evaporation method for efficient energy recovery Download PDFInfo
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- CN110975312B CN110975312B CN201911212966.0A CN201911212966A CN110975312B CN 110975312 B CN110975312 B CN 110975312B CN 201911212966 A CN201911212966 A CN 201911212966A CN 110975312 B CN110975312 B CN 110975312B
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Abstract
The invention discloses an MVR evaporation device and an evaporation method for efficient energy recovery, which comprises a vapor compressor, an evaporation heat exchanger, a separator and a distilled water tank, wherein the separator is communicated with the evaporation heat exchanger to form a feed liquid circulation loop for feed liquid to be circularly evaporated, the separator is communicated with the vapor compressor so that vapor generated by the evaporation of the feed liquid in the separator enters the vapor compressor to be compressed into high-temperature high-pressure vapor, the vapor compressor is communicated with the distilled water tank so that the high-temperature high-pressure vapor enters a distilled water pipe, the distilled water tank is communicated with the evaporation heat exchanger to form a vapor-liquid circulation loop for the heat exchange between the vapor and the feed liquid, so that the high-temperature high-pressure vapor enters the evaporation heat exchanger to carry out heat exchange heating on the feed liquid in the feed liquid circulation loop, and distilled water generated after the condensation of the high-temperature high-pressure vapor enters the distilled water tank again to carry out the heat exchange with superheated vapor in the distilled water tank, thereby lowering the temperature of the superheated steam and boiling the distilled water in the distilled water tank to produce saturated steam.
Description
Technical Field
The invention relates to the technical field of circulating evaporation, in particular to an MVR evaporation device and an evaporation method for efficient energy recovery.
Background
Mechanical Vapor Recompression (MVR) is an energy-saving technology that utilizes the Vapor and energy thereof generated by an evaporation system to improve the Mechanical work of low-quality Vapor into a high-quality Vapor source through a compressor, so as to circularly provide heat energy for the evaporation system and reduce the demand on external energy. The method has the advantages of good energy-saving effect, short retention time of products, high automation degree, simple process, small engineering investment and the like, and is widely applied to the aspects of zero discharge of chemical wastewater, organic concentration of sugar alcohol, concentration of pharmaceutical intermediates, utilization of rectification exhaust steam and the like. The existing MVR evaporation device utilizes a vapor compressor to compress vapor generated by a separator for evaporation, the pressure and the temperature of the vapor are improved, the vapor with improved heat energy is driven into an evaporation heat exchanger, feed liquid is heated again in the evaporation heat exchanger, the heated feed liquid is continuously flashed in the separator to generate the vapor, so that a continuous evaporation state is realized, the generated vapor enters the vapor compressor for pressurization and temperature rise, enters the evaporation heat exchanger for reheating the feed liquid, and circulates in sequence. The steam generated by the evaporation of the separator enters a steam compressor to be heated and pressurized, and the generated steam can be overheated to different degrees, and the larger the compression range is, the higher the overheating degree is. When the wall temperature of the evaporation heat exchanger is higher than the temperature of saturated steam, the phenomenon of condensation of superheated steam on the wall surface of the evaporation heat exchanger cannot occur, the steam and the wall surface of the evaporation heat exchanger only supply heat in a convection mode, the heat supply coefficient of steam condensation is far greater than that of convection heat supply, the heat exchange efficiency of the evaporation heat exchanger is low, the steam cannot be condensed and is directly discharged as non-condensable gas, the water yield is reduced, spray water is often sprayed into an inlet pipeline or an outlet pipeline of a steam compressor to convert the superheated steam into the saturated steam, however, a spray water source and a pump water system are additionally arranged in the scheme, the amount of the spray water needs to be continuously adjusted according to the actual situation, the energy of water resources and the energy of the steam are wasted, and the complexity of the evaporation system is increased.
Disclosure of Invention
The invention provides an MVR evaporation device and an evaporation method for efficient energy recovery, and aims to solve the technical problems that an evaporation heat exchanger in the existing MVR evaporation device is low in heat exchange efficiency and low in utilization rate of steam energy.
According to one aspect of the invention, an MVR evaporation device for efficient energy recovery is provided, which comprises a vapor compressor, an evaporation heat exchanger, a separator and a distilled water tank, wherein the separator is communicated with the evaporation heat exchanger to form a feed liquid circulation loop for feed liquid to circularly evaporate, the separator is communicated with the vapor compressor to enable vapor generated by the evaporation of the feed liquid in the separator to enter the vapor compressor to be compressed into high-temperature high-pressure vapor, the vapor compressor is communicated with the distilled water tank to enable the high-temperature high-pressure vapor to enter a distilled water pipe, the distilled water tank is communicated with the evaporation heat exchanger to form a vapor-liquid circulation loop for the heat exchange between the vapor and the feed liquid, the high-temperature high-pressure vapor enters the evaporation heat exchanger to carry out heat exchange heating on the feed liquid in the feed liquid circulation loop, and distilled water generated after the condensation of the high-temperature high-pressure vapor enters the distilled water tank again to carry out heat exchange with superheated vapor in the distilled water tank, thereby lowering the temperature of the superheated steam and boiling the distilled water in the distilled water tank to produce saturated steam.
Furthermore, the evaporation heat exchanger is provided with a first steam inlet for steam to enter and a first distilled water outlet for distilled water to be discharged after steam condensation, a heat exchange cavity for heat exchange between high-temperature and high-pressure steam and distilled water is arranged in the distilled water tank, the heat exchange cavity is provided with a second steam inlet communicated with the output end of the steam compressor, a steam outlet communicated with the first steam inlet of the evaporation heat exchanger and a distilled water inlet connected with the first distilled water outlet of the evaporation heat exchanger, the steam inlet and the steam outlet of the heat exchange cavity are both positioned at the top of the heat exchange cavity, the distilled water inlet of the heat exchange cavity is positioned in the middle of the heat exchange cavity, so that the distilled water output by the evaporation heat exchanger flows into the bottom of the heat exchange cavity and prevents the distilled water from reversely flowing, and the steam inlet is provided with a steam inlet pipe which extends inwards to the bottom of the heat exchange cavity and is used for guiding the high-temperature and high-pressure steam to enter the bottom of the heat exchange cavity, so that the high-temperature high-pressure steam is fully contacted with the distilled water at the bottom of the heat exchange cavity.
Furthermore, the output end of the steam inlet pipe is provided with a steam nozzle for uniformly spraying high-temperature and high-pressure steam into the heat exchange cavity, and the steam nozzles are respectively positioned at different positions at the bottom of the heat exchange cavity so that the high-temperature and high-pressure steam sprayed by the steam nozzle and the distilled water at the bottom of the heat exchange cavity can be subjected to heat exchange fully.
Furthermore, a water outlet cavity communicated with the heat exchange cavity is further arranged in the distilled water tank, so that part of high-temperature distilled water generated by heat exchange in the heat exchange cavity flows into the water outlet cavity, the MVR evaporation device further comprises a preheating heat exchanger, a material liquid input end of the preheating heat exchanger is connected with a material liquid supply system, a material liquid output end of the preheating heat exchanger is communicated with a material liquid circulation loop, a distilled water input end of the preheating heat exchanger is communicated with the water outlet cavity, and therefore material liquid input by the material liquid supply system is preheated by the high-temperature distilled water output by the distilled water tank and the preheated material liquid is conveyed into the material liquid circulation loop.
Furthermore, the inner cavity of the distilled water tank is divided into a heat exchange cavity and a water outlet cavity by a partition board fixed on the bottom wall surface of the inner cavity, and the top parts of the heat exchange cavity and the water outlet cavity are communicated, so that part of high-temperature distilled water generated by heat exchange in the heat exchange cavity flows into the water outlet cavity from a channel between the heat exchange cavity and the water outlet cavity.
Furthermore, a distilled water pump for pumping distilled water into the preheating heat exchanger and a control valve for controlling the discharge amount of the distilled water are arranged on a distilled water discharge pipeline between the water outlet cavity and the preheating heat exchanger.
Furthermore, the vapor-liquid circulation loop comprises a vapor pipeline connecting a vapor outlet of the heat exchange cavity and a first vapor inlet of the evaporation heat exchanger and a distilled water pipeline connecting a first distilled water outlet of the evaporation heat exchanger and a distilled water inlet of the heat exchange cavity, and the distilled water pipeline is provided with a noncondensable gas separator for separating and removing noncondensable gas in the distilled water.
Furthermore, a first discharge hole for discharging the feed liquid after cyclic evaporation concentration, a second discharge hole for discharging the cyclic feed liquid and a first feeding hole for feeding the cyclic feed liquid are sequentially distributed from the bottom to the top of the separator, a discharge pipeline is arranged at the first discharge hole, and a discharge pump is arranged on the discharge pipeline; the feed liquid circulation loop comprises a circulation discharge pipeline and a circulation return pipeline, the circulation discharge pipeline is connected with the second discharge port and the feed port of the evaporation heat exchanger, the circulation return pipeline is connected with the first feed port and the discharge port of the evaporation heat exchanger, and a forced circulation pump is arranged on the circulation discharge pipeline.
According to another aspect of the present invention, there is also provided an evaporation method of an MVR evaporation apparatus with high energy recovery, comprising the following steps: the feed liquid is conveyed into the separator through the feed liquid supply system, the feed liquid is circulated in the feed liquid circulation loop, and the feed liquid in the separator is heated to the boiling temperature through an external heating mode, so that the feed liquid in the separator is boiled and steam is generated; starting a steam compressor, and enabling steam generated by the separator to enter the steam compressor so as to form negative pressure in the separator, so that the boiling point of the feed liquid in the separator is reduced and then the feed liquid is further boiled to generate steam; high-temperature high-pressure steam compressed by a steam compressor enters an evaporation heat exchanger through a distilled water tank, the steam exchanges heat with feed liquid in the evaporation heat exchanger and is condensed into distilled water, the distilled water is discharged from the evaporation heat exchanger and then enters the distilled water tank again, so that a steam circulation loop is formed between the distilled water tank and the evaporation heat exchanger, the high-temperature high-pressure steam in the distilled water tank exchanges heat with the distilled water, the distilled water boils again to generate steam, and meanwhile, the temperature of the superheated high-temperature high-pressure steam is reduced; and discharging the concentrated feed liquid from the separator when the feed liquid is circularly evaporated to a specified concentration in the feed liquid circulating loop.
Further, the method also comprises the following steps: the feed liquid is conveyed to the preheating heat exchanger through the feed liquid supply system, and simultaneously, high-temperature distilled water obtained after heat exchange between part of the distilled water tank and high-temperature high-pressure steam is discharged into the preheating heat exchanger, so that the feed liquid is preheated through the high-temperature distilled water, and the preheated feed liquid is conveyed to the feed liquid circulation loop for feed liquid circulation.
The invention has the following beneficial effects:
the MVR evaporation device with high-efficiency energy recovery comprises a separator, an evaporation heat exchanger, a steam compressor, a distillation water tank, a steam liquid circulation loop and a steam liquid circulation loop, wherein the separator is communicated with the evaporation heat exchanger to form a feed liquid circulation loop, the steam liquid circulation loop is formed by the steam liquid circulation loop and the evaporation heat exchanger, the distillation water tank is communicated with the evaporation heat exchanger to heat the feed liquid after the high-temperature high-pressure steam passes through the distillation water tank, the distillation water after the steam is condensed enters the distillation water tank again to exchange heat with the superheated steam in the distillation water tank, the temperature of the superheated steam is reduced, the distillation water in the distillation water tank is boiled to generate saturated steam, and the saturated steam enters the evaporation heat exchanger to be condensed to supply heat to the wall surface of the evaporation heat exchanger, thereby heating the feed liquid and improving the heat exchange efficiency of the evaporation heat exchanger and the energy utilization rate of the steam.
In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic diagram of the high efficiency energy recovery MVR evaporation apparatus according to the preferred embodiment of the present invention;
fig. 2 is a schematic view showing the construction of a distilled water tank according to a preferred embodiment of the present invention.
Illustration of the drawings:
1. a vapor compressor; 2. an evaporative heat exchanger; 3. a separator; 4. a distilled water tank; 41. a heat exchange cavity; 411. a steam inlet pipe; 412. a steam spray head; 42. a partition plate; 43. a water outlet cavity; 5. preheating a heat exchanger; 6. a distilled water pump; 7. a forced circulation pump; 8. a discharge pump; 9. and no condensed gas separator.
Detailed Description
The embodiments of the invention will be described in detail below with reference to the accompanying drawings, but the invention can be embodied in many different forms, which are defined and covered by the following description.
FIG. 1 is a schematic diagram of the high efficiency energy recovery MVR evaporation apparatus according to the preferred embodiment of the present invention; fig. 2 is a schematic view showing the construction of a distilled water tank according to a preferred embodiment of the present invention.
As shown in fig. 1, the MVR evaporation apparatus for efficient energy recovery of this embodiment includes a vapor compressor 1, an evaporation heat exchanger 2, a separator 3 and a distilled water tank 4, the separator 3 is communicated with the evaporation heat exchanger 2 to form a feed liquid circulation loop for feed liquid to perform circulation evaporation, the separator 3 is communicated with the vapor compressor 1 to make vapor generated by evaporation of the feed liquid in the separator 3 enter the vapor compressor 1 to be compressed into high-temperature and high-pressure vapor, the vapor compressor 1 is communicated with the distilled water tank 4 to make the high-temperature and high-pressure vapor enter a distilled water pipe, the distilled water tank 4 is communicated with the evaporation heat exchanger 2 to form a vapor-liquid circulation loop for heat exchange between the vapor and the feed liquid, so that the high-temperature and high-pressure vapor enters the evaporation heat exchanger 2 to perform heat exchange heating on the feed liquid in the feed liquid circulation loop, and make distilled water generated by condensation of the high-temperature and high-pressure vapor reenter the distilled water tank 4 to perform heat exchange with superheated vapor in the distilled water tank 4, thereby lowering the temperature of the superheated steam and boiling the distilled water in the distilled water tank 4 to generate saturated steam. The MVR evaporation device for high-efficiency energy recovery comprises a separator 3 and an evaporation heat exchanger 2 which are communicated to form a feed liquid circulation loop, wherein the separator 3 is communicated with a vapor compressor 1, vapor generated by evaporation of the feed liquid in the separator 3 enters the vapor compressor 1 to be compressed into high-temperature high-pressure vapor, a distilled water tank 4 is additionally arranged between the vapor compressor 1 and the evaporation heat exchanger 2, the high-temperature high-pressure vapor firstly enters the distilled water tank 4 and then enters and communicates the distilled water tank 4 with the evaporation heat exchanger 2 to form a vapor-liquid circulation loop, the high-temperature high-pressure vapor enters the evaporation heat exchanger 2 to heat the feed liquid after passing through the distilled water tank 4, and the distilled water after vapor condensation enters the distilled water tank 4 again to exchange heat with superheated vapor in the distilled water tank 4, so that the temperature of the superheated vapor is reduced and the distilled water in the distilled water tank 4 is boiled to generate saturated vapor, and then the saturated steam enters the evaporation heat exchanger 2 and condenses with the wall surface of the evaporation heat exchanger 2 to supply heat, thereby heating the feed liquid, and improving the heat exchange efficiency of the evaporation heat exchanger 2 and the energy utilization rate of the steam.
The evaporation heat exchanger 2 is provided with a first steam inlet for steam to enter and a first distilled water outlet for distilled water to be discharged after steam condensation, a heat exchange cavity 41 for heat exchange between high-temperature high-pressure steam and distilled water is arranged in the distilled water tank 4, the heat exchange cavity 41 is provided with a second steam inlet communicated with the output end of the steam compressor 1, a steam outlet communicated with the first steam inlet of the evaporation heat exchanger 2 and a distilled water inlet connected with the first distilled water outlet of the evaporation heat exchanger 2, the steam inlet and the steam outlet of the heat exchange cavity 41 are both positioned at the top of the heat exchange cavity 41, the distilled water inlet of the heat exchange cavity 41 is positioned in the middle of the heat exchange cavity 41, so that the distilled water output by the evaporation heat exchanger 2 flows into the bottom of the heat exchange cavity 41 and prevents the distilled water from flowing reversely, and the steam inlet is provided with a steam inlet pipe 411 extending to the bottom of the heat exchange cavity 41 and used for guiding the high-temperature high-pressure steam to enter the bottom of the heat exchange cavity 41, so that the high-temperature and high-pressure steam is sufficiently contacted with the distilled water at the bottom of the heat exchange cavity 41. The high-temperature and high-pressure steam output by the steam compressor 1 enters the bottom of the heat exchange cavity 41 along the steam inlet pipe 411 to exchange heat with the distilled water in the heat exchange cavity 41, so that the temperature of the superheated steam is reduced and the distilled water is boiled to generate saturated steam.
The output end of the steam inlet pipe 411 is provided with a steam nozzle 412412 for uniformly spraying high-temperature and high-pressure steam into the heat exchange cavity 41, and the plurality of steam nozzles 412412 are respectively located at different positions of the bottom of the heat exchange cavity 41, so that the high-temperature and high-pressure steam sprayed by the steam nozzles 412412 and distilled water at the bottom of the heat exchange cavity 41 can be subjected to heat exchange sufficiently. The contact area of the steam and the distilled water is increased, and the heat exchange rate of the steam and the distilled water is improved.
The inside of the distilled water tank 4 is also provided with a water outlet cavity 43 communicated with the heat exchange cavity 41, so that part of high-temperature distilled water generated by heat exchange in the heat exchange cavity 41 flows into the water outlet cavity 43, the MVR evaporation device further comprises a preheating heat exchanger 5, the feed liquid input end of the preheating heat exchanger 5 is connected with a feed liquid supply system, the feed liquid output end of the preheating heat exchanger 5 is communicated with a feed liquid circulation loop, the distilled water input end of the preheating heat exchanger 5 is communicated with the water outlet cavity 43, so that feed liquid input by the feed liquid supply system is preheated by the high-temperature distilled water output by the distilled water tank 4, and the preheated feed liquid is conveyed into the feed liquid circulation loop. A part of high-temperature distilled water flows into the water outlet cavity 43, so that the distilled water in the heat exchange cavity 41 is reduced, the problem that the high-temperature high-pressure steam cannot boil the excessive distilled water to generate saturated steam due to the fact that the distilled water in the heat exchange cavity 41 is excessive is avoided, in addition, the water outlet cavity 43 is communicated with the preheating heat exchanger 5, the high-temperature distilled water in the water outlet cavity 43 is utilized to preheat the material liquid, and the energy utilization rate of the whole evaporation system is further improved. In this embodiment, the inner cavity of the distilled water tank 4 is divided into a heat exchange cavity 41 and a water outlet cavity 43 by a partition plate 42 fixed on the bottom wall surface of the inner cavity, and the tops of the heat exchange cavity 41 and the water outlet cavity 43 are communicated, so that a part of high-temperature distilled water generated by heat exchange in the heat exchange cavity 41 flows into the water outlet cavity 43 from a passage between the heat exchange cavity 41 and the water outlet cavity 43. Optionally, the partition plate 42 extends to the top of the inner cavity, and the bottom of the partition plate 42 is provided with a water through hole for communicating the heat exchange cavity 41 and the water outlet cavity 43. A distilled water pump 6 for pumping distilled water into the preheating heat exchanger 5 and a control valve for controlling the discharge amount of the distilled water are arranged on the distilled water discharge pipeline between the water outlet cavity 43 and the preheating heat exchanger 5. The control valve is adjusted to control the water discharge amount of the water outlet cavity 43. By detecting the temperature of the steam in the heat exchange cavity 41, the water discharge amount of the water outlet cavity 43 is controlled according to the temperature of the steam in the heat exchange cavity 41, so that the amount of the distilled water in the heat exchange cavity 41 is controlled, and the higher the temperature of the steam in the heat exchange cavity 41 is, the smaller the water discharge amount of the water outlet cavity 43 is, so that the distilled water in the heat exchange cavity 41 with a sufficient amount can exchange heat with the superheated steam. Optionally, the heat exchange cavity 41 is provided with a water inlet for connecting a water supply pipeline, and if the temperature of the steam in the heat exchange cavity 41 is still very high after the control valve is closed and the first distilled water outlet of the evaporation heat exchanger 2 discharges no distilled water or little distilled water, a certain amount of normal temperature water is supplied to the heat exchange cavity 41 through the water supply pipeline, so that the temperature of the steam in the heat exchange cavity 41 is reduced, and the steam is ensured to enter the evaporation heat exchanger 2 to condense and supply heat to the wall surface of the evaporation heat exchanger 2.
The vapor-liquid circulation loop comprises a vapor pipeline connecting a vapor outlet of the heat exchange cavity 41 and a first vapor inlet of the evaporation heat exchanger 2, and a distilled water pipeline connecting a first distilled water outlet of the evaporation heat exchanger 2 and a distilled water inlet of the heat exchange cavity 41, wherein the distilled water pipeline is provided with a noncondensable gas separator 92 for separating and removing noncondensable gas in the distilled water. Noncondensable gas such as air intruding into the entire evaporation system is removed by the noncondensable gas separator 92 to prevent the noncondensable gas from degrading the heat transfer performance of the evaporation heat exchanger 2. The non-condensable gas may cause the vapor not to contact the wall surface of the evaporating heat exchanger 2, thereby causing a decrease in the heat transfer performance of the evaporating heat exchanger 2. Optionally, a water drainage pipeline is arranged on the distilled water pipeline, and if the temperature of the steam in the heat exchange cavity 41 is low, the water drainage pipeline is opened, so that the distilled water discharged by the evaporation heat exchanger 2 is directly discharged without entering the distilled water tank 4 to exchange heat with the steam.
The separator 3 is sequentially provided with a first discharge hole for discharging the feed liquid after circulating evaporation concentration, a second discharge hole for discharging the circulating feed liquid and a first feeding hole for feeding the circulating feed liquid from the bottom to the top, a discharge pipeline is arranged at the first discharge hole, and a discharge pump 8 is arranged on the discharge pipeline; the feed liquid circulation loop comprises a circulation discharge pipeline and a circulation return pipeline, the circulation discharge pipeline is connected with the second discharge hole and the feed inlet of the evaporation heat exchanger 2, the circulation return pipeline is connected with the first feed inlet and the discharge hole of the evaporation heat exchanger 2, and a forced circulation pump 7 is arranged on the circulation discharge pipeline. The feed liquid from the separator 3 and the feed liquid from the preheat exchanger 5 are pumped to the evaporative heat exchanger 2 by a forced circulation pump 7. Optionally, the total volume of the feed liquid delivered to the whole evaporation system by the feed liquid supply system is determined according to the liquid level of the second discharge port and the concentration requirement of evaporative concentration of the feed liquid, and when the feed liquid is evaporated and concentrated circularly until the liquid level of the feed liquid is lower than the height of the second discharge port, the concentration of the feed liquid reaches the concentration requirement of evaporative concentration, so that the concentrated feed liquid is discharged from the first discharge port.
The evaporation method of the efficient energy recovery MVR evaporation device comprises the following steps: feeding the feed liquid into the separator 3 through a feed liquid supply system, circulating the feed liquid in a feed liquid circulation loop, and heating the feed liquid in the separator 3 to a boiling temperature by an external heating method, so that the feed liquid in the separator 3 is boiled and generates steam; starting the steam compressor 1, and enabling steam generated by the separator 3 to enter the steam compressor 1 so as to form negative pressure in the separator 3, so that the boiling point of the feed liquid in the separator 3 is reduced and then the feed liquid is further boiled to generate steam; high-temperature high-pressure steam compressed by the steam compressor 1 enters the evaporation heat exchanger 2 through the distilled water tank 4, the steam exchanges heat with feed liquid in the evaporation heat exchanger 2 and is condensed into distilled water, the distilled water is discharged from the evaporation heat exchanger 2 and then enters the distilled water tank 4 again, a steam circulation loop is formed between the distilled water tank 4 and the evaporation heat exchanger 2, so that the high-temperature high-pressure steam in the distilled water tank 4 exchanges heat with the distilled water, the distilled water boils again to generate steam, and meanwhile, the temperature of the superheated high-temperature high-pressure steam is reduced; when the feed liquid is circulated and evaporated in the feed liquid circulation circuit to a prescribed concentration, the concentrated feed liquid is discharged from the separator 3.
Further comprising the steps of: the feed liquid is conveyed to the preheating heat exchanger 5 through the feed liquid supply system, and simultaneously, high-temperature distilled water obtained by heat exchange between part of the distilled water tank 4 and high-temperature high-pressure steam is discharged into the preheating heat exchanger 5, so that the feed liquid is preheated through the high-temperature distilled water, and the preheated feed liquid is conveyed to the feed liquid circulation loop for feed liquid circulation.
An initial stage: a part of feed liquid is conveyed into the separator 3 through a feed liquid supply system, a forced circulation pump is started to pump the feed liquid in the separator 3 into the evaporation heat exchanger 2, the feed liquid is circulated in a feed liquid circulation loop, the feed liquid in the separator 3 is heated to the boiling point temperature of the feed liquid through external steam or an external heating device, the feed liquid in the separator 3 is boiled and generates steam, the steam in the separator 3 is pumped out by starting the steam compressor 1, the air pressure in the separator 3 is small, the boiling point of the feed liquid in the separator 3 is reduced, the steam is heated and pressurized by the steam compressor 1 and then enters the distilled water tank 4, the feed liquid is heated in the evaporation heat exchanger 2, and distilled water formed by steam condensation in the evaporation heat exchanger 2 is directly discharged. Because the temperature of the steam and the feed liquid in the initial stage is lower, the distilled water formed by condensing the steam in the evaporation heat exchanger 2 is directly discharged without entering the distilled water tank 4 to exchange heat with the steam. After a period of time, the temperature of the steam in the distilled water tank gradually rises, and the distilled water formed by condensing the steam in the evaporation heat exchanger 2 is conveyed into the heat exchange cavity 41 in the distilled water tank 4, so that the distilled water is boiled to generate steam, and the steam and the distilled water are circulated in the steam-liquid circulation loop. After the steam and the distilled water circulate in the steam-liquid circulation loop for a period of time, the amount of the distilled water in the distilled water tank 4 is gradually increased, then the distilled water in the water outlet cavity 43 in the distilled water tank 4 is discharged into the preheating heat exchanger 5, a part of the feed liquid is conveyed to the preheating heat exchanger 5 through the feed liquid supply system, the feed liquid is discharged by the distilled water from the distilled water tank 4 for preheating, and the preheated feed liquid is pumped into the evaporation heat exchanger 2 through the forced circulation pump 7 for circulation evaporation of the feed liquid. After the circulation evaporation lasts for a period of time, the concentration of the feed liquid in the separator 3 meets the requirement, and the feed liquid in the separator 3 is pumped to the next procedure through the discharge pump 8.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. An MVR evaporation device with high-efficiency energy recovery is characterized in that,
comprises a vapor compressor (1), an evaporation heat exchanger (2), a separator (3) and a distilled water tank (4),
the separator (3) is communicated with the evaporation heat exchanger (2) to form a feed liquid circulation loop for feed liquid to circularly evaporate, the separator (3) is communicated with the vapor compressor (1) so that vapor generated by the evaporation of the feed liquid in the separator (3) enters the vapor compressor (1) to be compressed into high-temperature and high-pressure vapor,
the steam compressor (1) is communicated with the distilled water tank (4) so that high-temperature high-pressure steam enters a distilled water pipe, the distilled water tank (4) is communicated with the evaporation heat exchanger (2) to form a steam-liquid circulation loop for exchanging heat between the steam and feed liquid, so that the high-temperature high-pressure steam enters the evaporation heat exchanger (2) to carry out heat exchange heating on the feed liquid in the feed liquid circulation loop, and distilled water generated after the high-temperature high-pressure steam is condensed enters the distilled water tank (4) again to exchange heat with superheated steam in the distilled water tank (4), so that the temperature of the superheated steam is reduced, and the distilled water in the distilled water tank (4) is boiled to generate saturated steam;
the evaporation heat exchanger (2) is provided with a first steam inlet for steam to enter and a first distilled water outlet for the distilled water after steam condensation to discharge,
a heat exchange cavity (41) for exchanging heat between high-temperature high-pressure steam and distilled water is arranged in the distilled water tank (4), the heat exchange cavity (41) is provided with a second steam inlet communicated with the output end of the steam compressor (1), a steam outlet communicated with the first steam inlet of the evaporation heat exchanger (2) and a distilled water inlet connected with the first distilled water outlet of the evaporation heat exchanger (2),
the steam inlet and the steam outlet of the heat exchange cavity (41) are both positioned at the top of the heat exchange cavity (41), the distilled water inlet of the heat exchange cavity (41) is positioned in the middle of the heat exchange cavity (41), so that the distilled water output by the evaporation heat exchanger (2) flows into the bottom of the heat exchange cavity (41) and is prevented from flowing reversely, and the steam inlet is provided with a steam inlet pipe (411) which extends to the bottom of the heat exchange cavity (41) and is used for guiding high-temperature and high-pressure steam to enter the bottom of the heat exchange cavity (41), so that the high-temperature and high-pressure steam is fully contacted with the distilled water at the bottom of the heat exchange cavity (41).
2. The efficient energy recovery MVR evaporation apparatus of claim 1,
the output end of the steam inlet pipe (411) is provided with steam nozzles (412) for uniformly spraying high-temperature and high-pressure steam into the heat exchange cavity (41), and the steam nozzles (412) are respectively positioned at different positions of the bottom of the heat exchange cavity (41) so that the high-temperature and high-pressure steam sprayed by the steam nozzles (412) and distilled water at the bottom of the heat exchange cavity (41) can fully exchange heat.
3. The efficient energy recovery MVR evaporation apparatus of claim 1,
a water outlet cavity (43) communicated with the heat exchange cavity (41) is also arranged in the distilled water tank (4) so that part of high-temperature distilled water generated by heat exchange in the heat exchange cavity (41) flows into the water outlet cavity (43),
the MVR evaporation device further comprises a preheating heat exchanger (5), a material liquid input end of the preheating heat exchanger (5) is connected with the material liquid supply system, a material liquid output end of the preheating heat exchanger (5) is communicated with the material liquid circulation loop, and a distilled water input end of the preheating heat exchanger (5) is communicated with the water outlet cavity (43), so that material liquid input by the material liquid supply system is preheated by high-temperature distilled water output by the distilled water tank (4) and the preheated material liquid is conveyed to the material liquid circulation loop.
4. The efficient energy recovery MVR evaporation apparatus of claim 3,
the inner cavity of the distilled water tank (4) is divided into a heat exchange cavity (41) and a water outlet cavity (43) by a partition plate (42) fixed on the bottom wall surface of the inner cavity, and the top parts of the heat exchange cavity (41) and the water outlet cavity (43) are communicated, so that part of high-temperature distilled water generated by heat exchange in the heat exchange cavity (41) flows into the water outlet cavity (43) from a channel between the heat exchange cavity (41) and the water outlet cavity (43).
5. The efficient energy recovery MVR evaporation apparatus of claim 3,
a distilled water pump (6) for pumping the distilled water into the preheating heat exchanger (5) and a control valve for controlling the discharge of the distilled water are arranged on a distilled water discharge pipeline between the water outlet cavity (43) and the preheating heat exchanger (5).
6. The efficient energy recovery MVR evaporation apparatus of claim 1,
the vapor-liquid circulation loop comprises a vapor pipeline for connecting a vapor outlet of the heat exchange cavity (41) with a first vapor inlet of the evaporation heat exchanger (2) and a distilled water pipeline for connecting a first distilled water outlet of the evaporation heat exchanger (2) with a distilled water inlet of the heat exchange cavity (41), and a non-condensation gas separator (9) for separating and removing non-condensation gas in the distilled water is arranged on the distilled water pipeline.
7. The efficient energy recovery MVR evaporation apparatus of claim 1,
a first discharge hole for discharging the feed liquid after cyclic evaporation concentration, a second discharge hole for discharging the cyclic feed liquid and a first feeding hole for feeding the cyclic feed liquid are sequentially distributed in the separator (3) from the bottom to the top, a discharge pipeline is arranged at the first discharge hole, and a discharge pump (8) is arranged on the discharge pipeline; the feed liquid circulation loop comprises a circulation discharge pipeline and a circulation return pipeline, the circulation discharge pipeline is connected with the second discharge hole and the feed inlet of the evaporation heat exchanger (2), the circulation return pipeline is connected with the first feed inlet and the discharge hole of the evaporation heat exchanger (2), and a forced circulation pump (7) is arranged on the circulation discharge pipeline.
8. An evaporation method of an MVR evaporation device with efficient energy recovery is characterized by comprising the following steps:
the feed liquid is conveyed into the separator (3) through a feed liquid supply system, the feed liquid is circulated in a feed liquid circulation loop, and the feed liquid in the separator (3) is heated to the boiling temperature through an external heating mode, so that the feed liquid in the separator (3) is boiled and steam is generated;
starting the steam compressor (1), and enabling steam generated by the separator (3) to enter the steam compressor (1) so as to form negative pressure in the separator (3), so that the boiling point of the feed liquid in the separator (3) is reduced and then the feed liquid is further boiled to generate steam;
high-temperature high-pressure steam compressed by the steam compressor (1) enters the evaporation heat exchanger (2) through the distilled water tank (4), the steam exchanges heat with feed liquid in the evaporation heat exchanger (2) and is condensed into distilled water, the distilled water is discharged from the evaporation heat exchanger (2) and then enters the distilled water tank (4) again, a steam circulation loop is formed between the distilled water tank (4) and the evaporation heat exchanger (2), so that the high-temperature high-pressure steam in the distilled water tank (4) exchanges heat with the distilled water, the distilled water boils again and generates steam, and meanwhile, the temperature of the superheated high-temperature high-pressure steam is reduced;
when the feed liquid is circularly evaporated to a specified concentration in the feed liquid circulation loop, the concentrated feed liquid is discharged from the separator (3).
9. The evaporation method of an efficient energy recovery MVR evaporation device of claim 8, further comprising the steps of:
the feed liquid is conveyed to the preheating heat exchanger (5) through the feed liquid supply system, and meanwhile, high-temperature distilled water obtained by heat exchange between part of the distilled water tank (4) and high-temperature high-pressure steam is discharged into the preheating heat exchanger (5), so that the feed liquid is preheated through the high-temperature distilled water, and the preheated feed liquid is conveyed to the feed liquid circulation loop for feed liquid circulation.
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