CN115259261A

CN115259261A - System and method for multiple effect evaporation

Info

Publication number: CN115259261A
Application number: CN202210866067.8A
Authority: CN
Inventors: 孟兵华; 邓海; 刘小红; 李国欢; 肖应东
Original assignee: Dongguan Dongyuan Environmental Technology Co ltd
Current assignee: Dongguan Dongyuan Environmental Technology Co ltd
Priority date: 2022-07-22
Filing date: 2022-07-22
Publication date: 2022-11-01

Abstract

The application discloses a system and a method for multi-effect evaporation, which relate to the technical field of water treatment, wherein the system comprises a three-stage evaporation assembly, a recovery assembly for recovering the output of the three-stage evaporation assembly and a vacuum piece for enabling the three-stage evaporation assembly to be in a negative pressure state, and a first-effect assembly, a second-effect assembly and a third-effect assembly of the three-stage evaporation assembly respectively comprise an evaporator, a separator and a first preheater; the first preheaters and the evaporators are all arranged in series; a first liquid inlet pipeline is arranged between the first preheater of the first effect component and the corresponding evaporator; each evaporator is communicated with a corresponding separator through a second liquid inlet pipeline; first steam transmission pipelines are arranged between the separator of the first-effect component and the evaporator of the second-effect component and between the separator of the second-effect component and the evaporator of the third-effect component; each evaporator is communicated with the corresponding first preheater through a second steam transmission pipeline. By applying the system, the system and the method of the embodiment of the application can balance energy consumption cost and equipment cost.

Description

System and method for multiple effect evaporation

Technical Field

The application relates to the technical field of water treatment, in particular to a multi-effect evaporation system and method.

Background

In the existing high-salt wastewater treatment process, the stock solution is generally treated by multiple-effect evaporators in sequence, although in the multiple-effect evaporators, the secondary steam generated in the evaporation process can be recycled, but in order to achieve a better evaporation effect, the effect number of the evaporators is often set to more than three effects, the cost of equipment is increased, and when the effect number is reduced, the same evaporation effect is realized, more tons of water vapor energy consumption are needed, the energy consumption is increased, and the energy consumption cost is increased.

Disclosure of Invention

The present application is directed to solving at least one of the problems in the prior art. Therefore, a system and a method for multi-effect evaporation are provided, which can balance energy consumption cost and equipment cost.

In a first aspect, a system for multiple effect evaporation according to embodiments of the present application, the system comprising:

the three-stage evaporation assembly comprises a first-effect assembly, a second-effect assembly and a third-effect assembly, and the first-effect assembly, the second-effect assembly and the third-effect assembly respectively comprise an evaporator, a first preheater and a separator; a plurality of the first preheaters and a plurality of the evaporators are all arranged in series; a first liquid inlet pipeline is arranged between the first preheater of the primary effect component and the corresponding evaporator; a second liquid inlet pipeline is arranged between each evaporator and the corresponding separator; first steam transmission pipelines are arranged between the separator of the first-effect component and the evaporator of the second-effect component and between the separator of the second-effect component and the evaporator of the third-effect component; a second steam transmission pipeline is arranged between each evaporator and the corresponding first preheater;

a recovery assembly for recovering the output of the tertiary evaporation assembly;

and the vacuum piece is used for enabling the tertiary evaporation assembly to be in a preset negative pressure state.

In a second aspect, a method of multiple-effect evaporation is provided according to an embodiment of the present application, and a system of multiple-effect evaporation according to any one of the first aspect is applied, the method of multiple-effect evaporation includes:

carrying out vacuum treatment on the three-stage evaporation assembly through a vacuum piece, so that the three-stage evaporation assembly is in a preset negative pressure state;

under the negative pressure state, respectively preheating stock solution by a first preheater of the three-effect component, a first preheater of the two-effect component and a first preheater of the first-effect component;

the stock solution heated in the first preheater of the first-effect component sequentially passes through the evaporator and the separator of the first-effect component, the evaporator and the separator of the second-effect component and the evaporator and the separator of the third-effect component;

the first secondary steam separated from the separator of the first-effect component sequentially passes through the evaporator of the second-effect component and the first preheater of the second-effect component, so that the first secondary steam is used for assisting in preheating a next stock solution to be preheated in the first preheater of the second-effect component, and the first secondary steam exchanges heat in the evaporator of the second-effect component;

the second secondary steam separated from the separator of the second-effect component sequentially passes through the evaporator of the third-effect component and the first preheater of the third-effect component, so that the second secondary steam is used for assisting in preheating the next stock solution to be preheated in the first preheater of the third-effect component, and the second secondary steam is used for exchanging heat in the evaporator of the third-effect component;

and recovering and treating the third secondary steam, the concentrated solution, the condensed water after the heat exchange of the first secondary steam and the second secondary steam by a recovery assembly, wherein the third secondary steam is the steam separated in the separation of the triple-effect assembly.

According to the above embodiment of the present application, at least the following advantages are provided: through setting up the one-effect subassembly, the one-level evaporation treatment to the stoste is realized respectively to two-effect subassembly and three-effect subassembly, two-pole evaporation treatment and tertiary evaporation treatment, it sets up the multistage preheating before realizing one-level evaporation treatment to establish ties through three first pre-heaters, and through passing through the second steam transmission pipeline with the evaporimeter of one-level, make the last one-level evaporation treatment export the secondary steam can carry out the heat transfer treatment to the stoste in the corresponding evaporimeter after carrying out the auxiliary heating to this level of first pre-heater, realize the multistage evaporation treatment of continuous feeding ejection of compact in succession, and make tertiary evaporation subassembly be in predetermined negative pressure state through the vacuum piece before the evaporation treatment, at this moment, the boiling point temperature that each level of evaporation treatment all differs and compares corresponding reduction with the boiling point under the normal pressure, compare with relevant technique, only need input the live steam in the one-effect subassembly to carry out the heat transfer, remaining second grade evaporation treatment, tertiary evaporation treatment all adopts the secondary steam to carry out the heat transfer and the temperature that the stoste required when the evaporation treatment all has fallen, and the secondary steam still is used for the auxiliary heating of first grade, therefore, this application embodiment can reduce the energy consumption of evaporation system, and the cost of the triple-effect subassembly of triple-effect subassembly, and the cost of this multiple-effect system, and its multiple-effect system more than the cost balance cost, and its multiple-effect system, thus the multiple-effect system cost balance cost can be lower.

Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.

Drawings

The above and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a system frame schematic of a system for multi-effect evaporation according to an embodiment of the present application;

FIG. 2 is a system detail schematic of a system for multi-effect evaporation according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a first effect assembly of a system for multi-effect evaporation according to an embodiment of the present application;

FIG. 4 is a schematic diagram of a two-effect assembly of a system for multi-effect evaporation according to an embodiment of the present application;

FIG. 5 is a schematic diagram of a three-effect module of a system for multi-effect evaporation according to an embodiment of the present application;

FIG. 6 is a schematic diagram of a recovery assembly of a system for multi-effect evaporation according to an embodiment of the present application;

fig. 7 is a schematic flow diagram of a method of multiple effect evaporation in an embodiment of the present application.

Reference numerals:

three-stage evaporation assembly 100, one-effect assembly 110, two-effect assembly 120, three-effect assembly 130,

An evaporator 210, a first preheater 220, a separator 230, a first liquid inlet pipeline 240, a second liquid inlet pipeline 250, a first steam transmission pipeline 260, a second steam transmission pipeline 270, a crystallizer 280,

A recovery component 300, a second preheater 310, a condenser 320, a water storage tank 330, a cyclone thickener 340, a centrifuge 350, a first water outlet pipeline 360, a second water outlet pipeline 370,

A vacuum member 400,

A water diversion tank 510, a third liquid inlet pipeline 520,

A coagulating sedimentation tank 610, a reclaimed water intermediate tank 620 and a quenching tower 630.

Detailed Description

Reference will now be made in detail to the embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary only for the purpose of explaining the present application and are not to be construed as limiting the present application.

In the description of the present application, it is to be understood that the positional descriptions, such as the directions of up, down, front, rear, left, right, etc., referred to herein are based on the directions or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, and do not indicate or imply that the referred device or element must have a specific direction, be constructed and operated in a specific direction, and thus, should not be construed as limiting the present application. If any, the first and second are described only for the purpose of distinguishing technical features, and are not to be understood as indicating or indicating relative importance in time or implicitly indicating the number of indicated counting features or implicitly indicating the precedence of the indicated technical features.

In the description of the present application, unless otherwise expressly limited, terms such as set, mounted, connected and the like should be construed broadly, and those skilled in the art can reasonably determine the specific meaning of the terms in the present application by combining the detailed contents of the technical solutions.

The following is an explanation of the terms used in this application:

thickeners, i.e. thickeners, settlers used to concentrate solid particles in suspension. And have a conical, cylindrical, square, etc. form. For certain needs, it is also designed to be multi-layered. The large thickener is mostly a cylinder with a conical bottom, suspension flows in from a central liquid feeding groove, and clear liquid overflows from the periphery and is discharged from an outflow groove. The rakes moving slowly are arranged in the device, so that sediments or sediments are collected to the center of the bottom of the device and are discharged through the discharge conduit after being collected.

In a first aspect, embodiments of the present application propose a system for multiple-effect evaporation, and referring to the embodiments shown in fig. 1 to 6, the system for multiple-effect evaporation includes:

the three-stage evaporation assembly 100, the three-stage evaporation assembly 100 includes a first-effect assembly 110, a second-effect assembly 120 and a third-effect assembly 130, and the first-effect assembly 110, the second-effect assembly 120 and the third-effect assembly 130 each include an evaporator 210, a first preheater 220 and a separator 230; the plurality of first preheaters 220 and the plurality of evaporators 210 are all arranged in series; a first liquid inlet pipeline 240 is arranged between the first preheater 220 of the first effect component 110 and the corresponding evaporator 210; a second liquid inlet pipeline 250 is arranged between each evaporator 210 and the corresponding separator 230; a first steam transmission pipeline 260 is arranged between the separator 230 of the first-effect component 110 and the evaporator 210 of the second-effect component 120, and between the separator 230 of the second-effect component 120 and the evaporator 210 of the third-effect component 130; a second steam transmission pipeline 270 is arranged between each evaporator 210 and the corresponding first preheater 220;

a recovery assembly 300, the recovery assembly 300 being for recovering the output of the three-stage evaporation assembly 100;

and a vacuum member 400, wherein the vacuum member 400 is used for enabling the tertiary evaporation assembly 100 to be in a preset negative pressure state.

Therefore, the primary evaporation treatment, the secondary evaporation treatment and the tertiary evaporation treatment of the raw liquid are respectively realized by arranging the primary assembly 110, the secondary assembly 120 and the tertiary assembly 130, the multi-stage preheating before the primary evaporation treatment is realized by serially connecting the three first preheaters 220, the evaporator 210 of the same stage is connected with the first preheater 220 through the second steam transmission pipeline 270, so that the secondary steam output by the primary evaporation treatment can perform heat exchange treatment on the raw liquid in the evaporator 210 of the same stage after performing auxiliary heating on the first preheater 220, the multi-stage evaporation treatment of continuous feeding and continuous discharging is realized, and the three-stage evaporation assembly 100 is in a preset negative pressure state through the vacuum piece 400 before the evaporation treatment, at the moment, the boiling point temperature of each stage of evaporation treatment is different and is correspondingly reduced compared with the boiling point under normal pressure, compared with the related technology, the raw steam only needs to be input into the primary assembly 110 for heat exchange, the rest of the secondary evaporation treatment, the tertiary evaporation treatment adopts the secondary steam for heat exchange, the temperature required by each stage of the raw liquid is reduced, and the secondary steam is also used for the auxiliary heat exchanger system, therefore, the cost of the multi-effect system is reduced, and the multi-effect system can be used for the multi-effect system.

It should be noted that, three first preheaters 220 are arranged in series, and can carry out multistage heating to the stoste, and transmit the flash evaporation to first preheater 220 through second steam transmission pipeline 270 and assist the heating for the time of preheater heating shortens and reduces the supply of outside heat source, make full use of the flash steam of preceding separator 230 separation, realize continuous feeding and ejection of compact.

It should be noted that three evaporators 210 are arranged in series, so that the stock solution entering the first-effect element 110 passes through the evaporator 210 of the first-effect element 110, the evaporator 210 of the second-effect element 120 and the evaporator 210 of the third-effect element 130 respectively to realize multi-stage evaporation treatment. Referring to fig. 2, pipes are provided at the inlet of the circulation pump P008 and at the outlet of the circulation pump P-001 to serially connect the evaporator 210 of the first-effect module 110 and the evaporator 210 of the second-effect module 120. Similarly, the evaporator 210 of the two-effect module 120 and the evaporator 210 of the three-effect module 130 are connected in series to realize a multi-stage evaporation process.

It should be noted that the vacuum member 400 may be a vacuum pump, and as shown in fig. 2, the vacuum pump P-002 is connected to the three-stage evaporation assembly 100, so that the negative pressure in the pipeline for transporting the secondary steam and the primary liquid passing through each of the evaporators 210 and the separators 230 can be controlled.

It should be noted that, referring to fig. 2, circulating pumps P-001, P-008 and P-007 are further provided in the multi-effect evaporation system, so that the raw liquid circulates in the evaporator 210 and the separator 230 of the same stage and exchanges heat in the evaporator 210, for example, P-001 circulates the raw liquid between the separator 230 of the first-effect assembly 110 and the evaporator 210 of the first-effect assembly 110.

It should be noted that, taking the evaporator 210 and the separator 230 in the single-effect assembly 110 as an example, the evaporator 210 uses a shell-and-tube heat exchanger, and functions that raw steam passes through a shell pass, raw wastewater passes through a tube pass, two media perform heat exchange at this point, the raw steam is condensed into supersaturated water from the supersaturated steam through heat exchange, the waste liquid is changed into a supersaturated state from a solvent (water) in the waste liquid through heat exchange, and the supersaturated water in a closed space cannot be changed into steam. The supersaturated wastewater stock solution enters the separator 230, and the separator 230 has a large space, so that a sudden pressure drop of the supersaturated wastewater stock solution causes water in the stock solution to rapidly vaporize and turn into steam (i.e., secondary steam). When the supersaturated state of the wastewater stock solution is volatilized into steam, so the supersaturated wastewater stock solution becomes saturated waste solution, the saturated waste solution flows into the bottom of the separator 230 and is conveyed to the evaporator 210 through the circulating pump to carry out heat exchange until the preset concentration is met, and then is conveyed to the next evaporator 210, and the secondary steam is used for heating the wastewater by the pressure of the next evaporator 210.

For example, referring to fig. 2, the raw liquid passes through the triple-effect module 130 and the first preheater 220 of the double-effect module 120, enters the first preheater 220 of the single-effect module 110 at 70 ℃, and is heated in the first preheater 220 of the single-effect module 110 under the condition of raw steam (the temperature of the raw steam is 107 ℃) sequentially passing through W-001 (the evaporator 210 of the single-effect module 110) and W-007 (the first preheater 220 of the single-effect module 110), so that the raw liquid is heated from 70 ℃ to 88 ℃; the stock solution at the temperature of 88 ℃ enters W-001 (namely the evaporator 210 of the first-effect assembly 110) through a first liquid inlet pipeline 240 and exchanges heat with the raw steam at the temperature of 107 ℃ in the W-001, the heated stock solution is conveyed to K-004 (namely the separator 230 of the first-effect assembly 110) through a second liquid inlet pipeline 250, the secondary steam output by the K-004 flows to W-002 and exchanges heat with the stock solution in the W-002, and similarly, the secondary steam output by the K-005 (namely the separator 230 of the second-effect assembly 120) flows to the stock solutions in the W-003 and the W-003 to exchange heat. Wherein the evaporation capacity of the stock solution in W-001 is 1345kg/h, and the discharge concentration is 16.8%; the evaporation capacity of W-002 is 1194kg/h, and the discharge concentration is 25.9%; the evaporation capacity of the W-003 is 1061kg/h, and the discharge concentration is 50% (about 18% of salt content); the discharge capacity of the whole triple-effect separation assembly is 1136.84kg/h.

It should be noted that, referring to fig. 2, the secondary steam output by K-004 will also flow to W-006, so that the temperature of the stock solution in W-006 rises from 55 ℃ to 70 ℃; the secondary steam output by K-005 will also flow to W-005, causing the temperature of the stock solution in W-005 to rise from 40 ℃ to 55 ℃, and the secondary steam output by K-006 (i.e. separator 230 of three-way component 130) will also flow to W-004, causing the temperature of the stock solution in W-004 to rise from 40 ℃ to 55 ℃.

It should be noted that, in the application process, the following table is referred to perform the energy consumption calculation, specifically, the following table (a) refers to the material preheating state, the temperature-vacuum degree relationship of the table (b) (wherein the table (b) only indicates the vacuum degree requirement at a part of the temperature), the material balance of the table (c), and the heat balance of the table (d):

watch 1

Temperature (. Degree.C.)	Vacuum degree (kpa)	Temperature (. Degree. C.)	Vacuum degree (kpa)	Temperature (. Degree.C.)	Vacuum degree (kpa)
						20	-98.7	27	-97.5	34	-95.8
21	-98.6	28	-97.3	35	-95.5
						22	-98.4	29	-97.1	36	-95.2
23	-98.3	30	-96.8	37	-94.8
						24	-98.1	31	-96.6	38	-94.5
25	-97.9	32	-96.3	39	-94.1
						26	-97.7	33	-96.1	40	-93.7

Watch 2

Watch (III)

Watch (IV)

It should be noted that the principle of setting different evaporation pressures and temperatures for multi-effect evaporation is as follows: when the solution is not pure water but water + solvent, the boiling point of the solution at normal atmospheric pressure is not 100 ℃ and will generally be higher than 100 ℃, for example, 25% saline wastewater will not boil when heated to 100 ℃ at normal atmospheric pressure and must be heated to a higher temperature to boil. The temperature rise at this time is called the boiling point rise. The temperature of the one-effect heating heat source (raw steam) must be higher than the waste water evaporation temperature + the waste liquid boiling point raising temperature in the evaporator 210 of the one-effect component 110, so as to ensure that the one-effect evaporation is smoothly performed. The secondary steam output by the first-effect component 110 must be higher than the waste water evaporation temperature + the waste liquid boiling point raising temperature in the evaporator 210 of the second-effect component 120, so as to ensure that the second-effect evaporation is smoothly performed. For example, the raw steam setting of the one-effect heating is 120 ℃, the boiling point plus boiling point rise value of the one-effect wastewater must be ensured to be less than 120 ℃ to ensure the evaporation. The superheated secondary steam generated by the first-effect evaporator 210 must be less than 120 ℃. Therefore, in order to ensure that the double-effect evaporation is carried out smoothly, the temperature of the double-effect evaporation must be lower than the temperature of the secondary steam after the first-effect heat exchange. Therefore, in order to achieve smooth evaporation, the pressure of the dual-effect evaporator 210 must be reduced, and the boiling point of the solvent must be reduced by controlling the pressure. At this time, the temperature, capacity and vacuum degree of the evaporation process of each stage at a given feed temperature are finally determined by combining the above table and the evaporation state (data of temperature, specific volume, heat of vaporization and the like at different pressures).

It should be noted that when four effects are used, the energy consumption per ton of steam is lower than that of three effects, but the investment in equipment is too large. When the double-effect evaporation is used, the equipment investment cost is reduced, but the energy consumption per ton of water vapor is increased. Therefore, the cost performance of the triple-effect equipment is high compared with the cost performance of ton water vapor energy consumption, the vacuum piece 400 is adopted to carry out negative pressure treatment on the three-stage steam assembly, and secondary steam can be further fully utilized to achieve higher cost performance.

It should be noted that, in some embodiments, the separator 230 of the two-effect module 120 and the separator 230 of the three-effect module 130 are further communicated with a concentrate discharge pump for discharging a concentrate with a concentration meeting a final discharge requirement, for example, referring to fig. 2, a concentrate discharge pump P-005 is provided, and the concentrate discharge pump P-005 is communicated with an outlet of the circulating pump P-008 and a concentrate discharge outlet of the separator 230 of the three-effect module 130 to pump a concentrate meeting a preset concentration to the horizontal decanter centrifuge D-001 for separation.

It should be noted that the condensed water obtained after the heat exchange of the secondary steam in the corresponding evaporator 210 is collected by the recovery assembly 300. The secondary steam from the separator 230 of the triple-effect module 130 may be directly recovered or used to heat the raw liquid at the initial temperature before entering the first preheater 220 of the triple-effect module 130, so that the secondary steam usage rate is maximized.

In some embodiments, referring to fig. 1 and 2, the concentrated solution obtained by the evaporation process of the three-stage evaporation module 100 is subjected to a deputy process by using a solid waste (miscellaneous salt) obtained by separating with a horizontal decanter centrifuge D-001, and the mother solution is returned to the coagulation sedimentation tank 610 (corresponding to K-003 in fig. 2) and recycled. The condensate water evaporated and cooled in the three-stage evaporation assembly 100 is sent to the reclaimed water intermediate pool 620 (corresponding to K-002 in fig. 2) by the reclaimed water pump, and the reclaimed water collected in the reclaimed water intermediate pool 620 is recycled to the quench tower 630.

It is understood that, referring to fig. 6, the recovery assembly 300 includes a second preheater 310, a condenser 320, and a water storage tank 330; the second preheater 310 is arranged in series with the first preheater 220 of the triple-effect component 130, and the second preheater 310 is used for preheating the stock solution; a third steam transmission pipeline is arranged between the second preheater 310 and the separator 230 and the condenser 320 of the three-effect assembly 130, the water outlet of the condenser 320 is communicated with the water storage tank 330, and both the evaporator 210 of the two-effect assembly 120 and the evaporator 210 of the three-effect assembly 130 are communicated with the water storage tank 330.

It should be noted that, by providing the second preheater 310, the stock solution can be preheated before entering the first preheater 220 of the tertiary evaporation assembly 100, so as to further enable the secondary steam to be effectively utilized, and by providing the condenser 320, the secondary steam is directly cooled and then stored in the water storage tank 330.

It should be noted that, since the evaporator 210 of the first-effect module 110 is heated by using the raw steam, in some embodiments, only the cooling water in the evaporator 210 of the second-effect module 120 and the cooling water in the evaporator 210 of the third-effect module 130 are stored in the water storage tank 330, and the cooling water of the raw steam is separately recycled. Illustratively, referring to fig. 2 and 6, a first water outlet pipe 360 is disposed between the evaporator 210 of the two-effect component 120 and the evaporator 210 of the three-effect component 130, and a second water outlet pipe 370 is disposed between the evaporator 210 of the three-effect component 130 and the water storage tank 330, so that the condensed water from the evaporator 210 of the two-effect component 120 is collected into the evaporator 210 of the three-effect component 130 and is transported from the second water outlet pipe 370 to the water storage tank 330.

It is understood that a first water outlet pipe 360 is disposed between the evaporator 210 of the two-effect device 120 and the evaporator 210 of the three-effect device 130, and a second water outlet pipe 370 is disposed between the evaporator 210 of the three-effect device 130 and the water storage tank 330.

It can be understood that, referring to fig. 2, the multi-effect evaporation system further includes a water diversion tank 510, a third liquid inlet pipe 520 is disposed between the water diversion tank 510 and the second preheater 310, the water diversion tank 510 is provided with a raw water inlet, a municipal water inlet, and a chemical liquid inlet, and the water diversion tank 510 is communicated with the plurality of separators 230. Through communicating diversion tank 510 with a plurality of separators 230, when needs wash, can be directly through the liquid medicine import injection liquid medicine at diversion tank 510, then open self-cleaning for the liquid medicine in diversion tank 510 can be distributed to each separator 230 and realize self-cleaning.

It can be understood that, referring to fig. 2 and fig. 6, the recycling assembly 300 comprises a cyclone thickener 340 and a centrifuge 350, a fourth liquid inlet pipeline is arranged between the cyclone thickener 340 and the centrifuge 350, and the cyclone thickener 340 is communicated with a liquid outlet of each separator 230. The separation effect is improved by arranging the cyclone thickener 340 before the centrifuge 350 so that the concentration of the liquid to be separated is increased.

It is noted that in some embodiments, the recovery assembly 300 includes a secondary preheater 310, a condenser 320, a water storage tank 330, a cyclone thickener 340, and a centrifuge 350; the second preheater 310 is arranged in series with the first preheater 220 of the triple-effect component 130, and the second preheater 310 is used for preheating the stock solution; a third steam transmission pipeline is arranged between the condenser 320 and the separator 230 and the second preheater 310 of the three-effect component 130, the water outlet of the condenser 320 is communicated with the water storage tank 330, and both the evaporator 210 of the two-effect component 120 and the evaporator 210 of the three-effect component 130 are communicated with the water storage tank 330; a fourth liquid inlet pipeline is arranged between the cyclone thickener 340 and the centrifuge 350, and the cyclone thickener 340 is communicated with the liquid outlet of each separator 230.

It is understood that evaporator 210 of first-effect element 110 is a falling film evaporator 210, evaporator 210 of second-effect element 120 and evaporator 210 of third-effect element 130 are all configured as forced circulation evaporators 210.

It can be understood that the separator 230 of the triple-effect assembly 130 is communicated with a crystallizer 280, the crystallizer 280 is detachably provided with washing legs with a conical structure, and the height of the washing legs is more than 600mm.

It should be noted that, at the position of the triple-effect module 130, because the concentration of the waste liquid after evaporation treatment is high and crystallization is relatively easy, a crystallizer 280 is arranged at the position of the separator 230 of the triple-effect module 130, and at this time, the washing leg can ensure good salt collection and cooling effects.

It should be noted that the main functions of the elutriation of the legs are salt collection and cooling. Saturated or supersaturated high salt wastewater, as the temperature is lowered and the concentration is increased, crystals are precipitated. In the multi-stage evaporation system, the concentration of the waste liquid in the separator 230 of the triple effect module 130 is the highest, and the temperature is the lowest in the three-stage evaporation treatment, and crystals are likely to precipitate. The washing legs are arranged to be of a conical structure, crystal blocks are not easy to gather relative to the elliptical seal head and the flat-bottom seal head, and the washing difficulty is reduced. And the washing legs are arranged in a detachable mode, so that the washing machine is easy to clean. Meanwhile, the higher the leg washing is, the larger the cooling effect is, the better the salt collecting effect is, and the more easily the crystal blocks are gathered. If the leg washing is too short, the cooling effect is poor, the salt collecting effect is poor, and the crystal agglomeration risk is small. Therefore, the height of the elutriation legs is empirically determined to be 0.9 times of the effective height of the crystallizer 280, and the shortest effective height is not less than 600mm, and if the salt collecting effect is not good, the height of the elutriation legs needs to be increased.

It will be appreciated that the steam outlet of the separator 230 is provided with a demister.

It should be noted that the high salinity wastewater is alkaline and contains more inorganic substances and active agents, so that the wastewater may have foam in the separator 230, and the foam is the wastewater. Therefore, the secondary steam in the first steam conveying pipe 260 is free from foam by adding a foam removing member at the steam outlet.

It should be noted that, in the embodiment of the present application, the number of the separators 230 is not limited for each stage of evaporation, and when the content of the foam in the separator 230 is large, the secondary separator 230 may be added to perform multiple separations, and the auxiliary demister makes the secondary steam finally sent to the next stage free of foam.

It should be noted that the demister can be a turbofan baffle type or a wire mesh type demister.

It can be understood that the liquid inlets of the

separators

230 and 230 of the first-effect module 110 and the second-effect module 120 are tangential inlets, and the liquid inlet of the separator 230 of the third-effect module 130 is an upward elbow.

It should be noted that the tangential inlet is a cut designed by adopting a tangential line or a tangential line of the volute, and the cut is set as the tangential inlet, so that the gasified secondary steam can be thoroughly separated when the feed liquid enters. For the triple-effect module 130, it is necessary to prevent crystallization, so the elbow-up design is adopted.

It should be noted that, in order to prevent the evaporation capacity from being affected by heat loss, the evaporator 210 needs to be insulated except for the condenser 320, the pump, the valve, and the instrument, and the insulation material is rock wool and is wrapped by stainless steel. And other devices of the three-stage assembly can be subjected to heat preservation treatment in the same way.

It can be understood that, referring to fig. 7, the method for multi-effect evaporation provided according to the embodiment of the present application is applied to the system for multi-effect evaporation, which includes:

step S100, performing vacuum treatment on the tertiary evaporation assembly 100 through the vacuum member 400, so that the tertiary evaporation assembly 100 is in a preset negative pressure state.

It should be noted that the negative pressure state of each device is different in the evaporation process of different levels. It should be noted that, steam, stock solution, etc. are transmitted through a pipeline in the transmission process, and heat exchange is performed between the evaporator 210 and the pipeline through the shell, so in practical application, it is necessary to ensure that the pressure in the pipeline for transmission and the pressure in the shell for heat exchange meet the preset negative pressure requirement, so that the stock solution can be normally evaporated.

In step S200, the stock solution is preheated by the first preheater 220 of the triple-effect module 130, the first preheater 220 of the double-effect module 120, and the first preheater 220 of the single-effect module 110, respectively, under a negative pressure.

It should be noted that, in some embodiments, the raw liquid passes through the second preheater 310, and then passes through the first preheater 220 of the triple-effect module 130, the first preheater 220 of the double-effect module 120, and the first preheater 220 of the first-effect module 110 for preheating treatment, so as to achieve parallel-flow heating, and the triple-effect module 130 performs discharging (i.e. continuous feeding and discharging), so that the secondary steam in the evaporation process can be used for auxiliary heating of the raw liquid to be evaporated next time, thereby improving the utilization rate of energy.

Step S300, the raw liquid heated in the first preheater 220 of the first-effect component 110 passes through the evaporator 210 and the separator 230 of the first-effect component 110, the evaporator 210 and the separator 230 of the second-effect component 120, and the evaporator 210 and the separator 230 of the third-effect component 130 in sequence.

The stock solution is subjected to multi-stage evaporation treatment, so that the evaporation effect is better.

Step S400, the first secondary steam separated from the separator 230 of the first-effect component 110 sequentially passes through the evaporator 210 of the second-effect component 120 and the first preheater 220 of the second-effect component 120, so that the first secondary steam assists in preheating the next stock solution to be preheated in the first preheater 220 of the second-effect component 120, and the first secondary steam exchanges heat in the evaporator 210 of the second-effect component 120.

It should be noted that the first secondary steam passes through the evaporator 210 of the two-effect module 120 and the first preheater 220 of the two-effect module 120 in sequence through a pipeline, and after being heated in the first preheater 220 of the two-effect module 120 in an auxiliary manner, the first secondary steam is output at the same temperature, and then is subjected to heat exchange in the evaporator 210 of the two-effect module 120. After the heat exchange, the first secondary steam is condensed into water because the temperature of the first secondary steam is lower than the boiling point temperature corresponding to the pressure in the evaporator 210.

Step S500, the second secondary steam separated from the separator 230 of the second-effect component 120 passes through the evaporator 210 of the third-effect component 130 and the first preheater 220 of the third-effect component 130 in sequence, so that the second secondary steam assists in preheating the next stock solution to be preheated in the first preheater 220 of the third-effect component 130, and the second secondary steam exchanges heat in the evaporator 210 of the third-effect component 130.

It should be noted that the second secondary steam passes through the evaporator 210 of the triple-effect module 130 and the first preheater 220 of the triple-effect module 130 in sequence through a pipeline, is heated in the first preheater 220 of the triple-effect module 130 in an auxiliary manner, and then is output at the same temperature, and then is subjected to heat exchange in the evaporator 210 of the triple-effect module 130. After the second heat exchange, the steam is condensed into water because the temperature of the steam is lower than the boiling point temperature corresponding to the pressure in the evaporator 210.

Step S600, the recovery assembly 300 recovers and processes the third secondary steam, the concentrated solution, the condensed water after the heat exchange of the first secondary steam and the second secondary steam, wherein the third secondary steam is the steam separated in the separation of the triple-effect assembly 130.

It should be noted that, in some embodiments, referring to fig. 2, the third secondary steam separated from the triple-effect component 130 may be used to preheat the raw liquid, so that the raw liquid enters the first preheater 220 of the triple-effect component 130 at a predetermined temperature, thereby improving the effective utilization rate of the secondary steam.

The multi-effect evaporation system and method of embodiments of the present application are further described with reference to the multi-effect evaporation systems of fig. 1-7:

the pipelines in the triple-effect evaporation assembly, the second preheater 310 and the condenser 320 are all in a negative pressure state through a vacuum pump P-002, the stock solution at the temperature of 20 ℃ enters the second preheater 310 through a water guide tank 510 under the action of a feed pump P-003 so that the temperature of the stock solution is raised from 20 ℃ to 40 ℃, and then the stock solution at the temperature of 40 ℃ is conveyed to the first preheater 220 of the triple-effect assembly 130 so that the temperature of the stock solution at the temperature of 40 ℃ is raised to 55 ℃; the 55 ℃ stock solution is then transferred to the first preheater 220 of the two-effect module 120 such that the 55 ℃ stock solution is warmed to 70 ℃, and then the 70 ℃ stock solution is transferred to the first preheater 220 of the one-effect module 110. Raw steam circulates in the evaporator 210 and the first preheater 220 of the first-effect component 110, when the temperature of a stock solution at 70 ℃ in the first preheater 220 of the first-effect component 110 rises to 88 ℃, the first preheater 220 of the first-effect component 110 conveys the stock solution into the evaporator 210 of the first-effect component 110 to exchange heat with raw steam to obtain a saturated stock solution, the saturated stock solution enters the separator 230 of the first-effect component 110 through the second liquid inlet pipeline 250 to be subjected to gas-liquid separation to obtain a stock solution with a discharge concentration of 16.8% and first secondary steam, the first secondary steam circulates in the evaporator 210 of the second-effect component 120 and the first preheater 220 of the second-effect component 120 to exchange heat with the stock solution with the discharge concentration of 16.8% in the evaporator 210 of the second-effect component 120 and heats the stock solution with a temperature of 55 ℃ in the first preheater 220 of the second-effect component 120 until the temperature of the stock solution reaches 70 ℃, and the first secondary steam in the first preheater 220 of the second preheater of the second-effect component 120 returns to the evaporator 210 of the second-effect component 120 at the same temperature; correspondingly, in the evaporator 210 of the two-effect component 120, the secondary steam after heat exchange is changed into 65 ℃ secondary steam to be K-002 through flowing water at 65 ℃ under the pressure effect; the evaporator 210 of the two-effect module 120 outputs the raw liquid with the discharging concentration of 25.9% to the evaporator 210 of the three-effect module 130, the separator 230 of the two-effect module 120 transmits the generated second secondary steam to the three-effect module 130, so that the second secondary steam circulates between the first preheater 220 and the evaporator 210 of the three-effect module 130 to assist in heating the raw liquid with the temperature of 40 ℃ by the first preheater 220 of the three-effect module 130, and simultaneously performs heat exchange in the evaporator 210 of the three-effect module 130, accordingly, after heat exchange in the evaporator 210 of the three-effect module 130, the raw liquid with the concentration of 50% is output, and the second secondary steam is condensed into water flow to K-002 under the pressure effect. The third secondary steam output from the separator 230 of the triple-effect assembly 130 enters the second preheater 310 and circulates between the second preheater 310 and the condenser 320, so that the stock solution at 20 ℃ is heated in the second preheater 310. The stock solution with the discharge concentration of 50 percent output by the separator 230 of the triple-effect component 130 is pumped to F-001 (namely the cyclone thickener 340) by the P-005 and treated with solid waste and mother liquor by the treatment from F-001 to D-001, wherein the solid waste (miscellaneous salt, the water content is less than 10 percent) goes to K-003 and then is pumped to the coagulating sedimentation tank 610 by the P-006. The cooling water cooled by the first secondary steam, the second secondary steam and the third secondary steam is converged to K-002 and is pumped to the quenching tower 630 by a pump P-004 for recycling. Meanwhile, the flow velocity of the waste liquid in the heat exchange tube in the evaporator 210 is set to 2m/s, so that scaling and coking can be effectively reduced, and the heat transfer speed is increased. Meanwhile, the thickener and the centrifuge 350 are configured to make zero full use of waste liquid, the multi-effect evaporation mode can effectively reduce the energy consumption, and compared with the existing multi-stage evaporation by adopting raw steam, the energy consumption of the raw steam of the system can reach 0.45 ton of raw steam per ton of waste water.

In the description of the present specification, reference to the description of "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the application, the scope of which is defined by the claims and their equivalents.

The embodiments of the present application have been described in detail with reference to the drawings, but the present application is not limited to the embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present application.

Claims

1. A system for multiple effect evaporation, comprising:

and the vacuum piece is used for enabling the three-stage evaporation assembly to be in a preset negative pressure state.

2. The system of multi-effect evaporation of claim 1, wherein the recovery assembly comprises a second preheater, a condenser, and a water storage tank; the second preheater is connected in series with the first preheater of the triple effect component and is used for preheating stock solution; the second preheater with the separator of triple effect subassembly between the condenser be provided with third steam transmission pipeline, the delivery port of condenser with the aqua storage tank intercommunication, the evaporimeter of double effect subassembly and the evaporimeter of triple effect subassembly all with the aqua storage tank intercommunication.

3. The system of claim 2, wherein a first water outlet pipe is arranged between the evaporator of the two-effect module and the evaporator of the three-effect module, and a second water outlet pipe is arranged between the evaporator of the three-effect module and the water storage tank.

4. The multi-effect evaporation system of claim 2, further comprising a water diversion tank, wherein a third liquid inlet pipeline is arranged between the water diversion tank and the second preheater, the water diversion tank is provided with a raw water inlet, a municipal water inlet and a liquid medicine inlet, and the water diversion tank is communicated with the plurality of separators.

5. The system of multiple effect evaporation of claim 1, wherein the recovery subassembly includes whirl thickener and centrifuge, a fourth inlet pipe is provided between the whirl thickener and the centrifuge, and the whirl thickener is communicated with the outlet of each separator.

6. The system of multi-effect evaporation of claim 1, wherein the evaporator of the first-effect assembly is a falling film evaporator, and the evaporator of the second-effect assembly and the evaporator of the third-effect assembly are both configured as forced circulation evaporators.

7. The system of multi-effect evaporation of claim 1, wherein the separator of the three-effect module is communicated with a crystallizer, the crystallizer is detachably provided with washing legs with a conical structure, and the height of the washing legs is more than 600mm.

8. The system of multiple effect evaporation of claim 1, wherein the steam outlet of the separator is provided with a demister.

9. The system of multi-effect evaporation of claim 1, wherein the liquid inlets of the separators of the first effect assembly and the separators of the second effect assembly are all arranged as tangential inlets, and the liquid inlets of the separators of the third effect assembly are arranged as upward-facing elbow openings.

10. A method of multi-effect evaporation applied to the system of multi-effect evaporation of any one of claims 1 to 9, the method of multi-effect evaporation comprising: