CN214115234U - Desalting system for salt-containing organic wastewater - Google Patents
Desalting system for salt-containing organic wastewater Download PDFInfo
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- CN214115234U CN214115234U CN202023113900.7U CN202023113900U CN214115234U CN 214115234 U CN214115234 U CN 214115234U CN 202023113900 U CN202023113900 U CN 202023113900U CN 214115234 U CN214115234 U CN 214115234U
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Abstract
The utility model provides a desalination system who contains salt organic waste water, the desalination system is including the circulation route that flash vessel, circulating pump, heater and flash valve that establish ties in proper order are constituteed, wherein, the liquid phase export of flash vessel links to each other with the entry of circulating pump, the heater export links to each other with the flash valve entry, the export of flash valve links to each other with the entry of flash vessel. The utility model provides a desalination system who contains salt organic waste water adopts circulation flash distillation and the principle that the effect combined together is analysed to mellow wine, carries out the separation of salt and other components through solid-liquid separation and vapour-liquid separation two-step method, effectively guarantees the separation effect, prevents pipeline, valve and equipment jam simultaneously. The desalting system has simple device, low cost and good adjustability, and can adapt to different heat source temperatures by adjusting the circulation ratio for heat sources with different tastes; and the desalting system has good adaptability.
Description
Technical Field
The utility model relates to a chemical industry pretreatment of water technical field especially relates to a desalination system who contains salt organic waste water.
Background
In the chemical production process, after a series of unit operations such as raw material pretreatment, reaction, refining and the like, organic wastewater containing salt is often generated, if the organic wastewater is not treated, the salt is discharged into a sewage treatment plant along with the organic wastewater, on one hand, the activity of flora in activated sludge of the sewage treatment plant is influenced, and on the other hand, the salt is discharged into the environment along with the sewage to cause environmental pollution and pollute water and soil. It is therefore necessary to separate the salts from the waste water. Meanwhile, the salt is removed from the wastewater, so that organic matters can be recovered from the organic wastewater and recovered as byproducts or raw materials to be returned to an upstream process. Organic matters with higher economic value or higher environmental hazard and toxicity are more necessary to be recycled, so that the economic value and the environmental protection value can be realized.
In general, salt is separated from wastewater before organic matters, otherwise, salt participates in the separation and refining process of the organic matters, so that the separation and refining system is possibly blocked, and meanwhile, the requirement of the separation system on the material is increased due to the existence of the salt, so that the separation cost is increased. It is therefore necessary to separate the salts beforehand. Salt is usually removed from organic wastewater in a solid form, and the existence of the solid causes the salt removal system to be easily blocked and hardened, so that the long-term stable operation of the system is not facilitated. In addition, if the desalination is not thorough, a small amount of salt can be accumulated after entering a downstream system, and after the system operates for a certain time, the problems of packing blockage of the rectifying tower, corrosion of equipment and pipelines and the like can be caused, so that the downstream system cannot operate stably for a long time.
Disclosure of Invention
In view of the problem that exists among the above-mentioned prior art, the utility model aims to provide a desalination system who contains salt organic waste water, desalination system utilizes the principle that circulation flash distillation and alchol analysis effect combined together, adopts gas-liquid separation and solid-liquid separation two-step method, realizes the thorough separation of organic waste water and salinity to effectively solve the easy problem of blockking up of system.
The utility model aims at providing a desalination system that contains salt organic waste water, including heater, flash valve, flash vessel and the circulating pump that connects gradually, wherein, the liquid phase export of flash vessel links to each other with the entry of circulating pump, the export of heater links to each other with the entry of flash valve, the export of flash valve links to each other with the entry of flash vessel; the solid-liquid separation device is connected with the circulating pump in series or in parallel.
In some preferred embodiments of the desalination system according to the invention, it is preferred that the solid-liquid separation device is located downstream of a mixing point of the salt-containing organic waste water and the circulation liquid of the desalination system.
According to some preferred embodiments of desalination system in, when solid-liquid separation equipment and circulating pump are parallelly connected, heater, flash valve, flash vessel and circulating pump are established ties and are constituted circulation path, a branch road of circulating pump export loop through contain salt organic waste water entry and solid-liquid separation equipment with the entry of flash vessel links to each other.
According to some preferred embodiments of desalination system in, when solid-liquid separation equipment establishes ties with the circulating pump, the export of circulating pump loops through the entry that contains salt organic waste water entry and solid-liquid separation equipment and heater and links to each other, constitutes circulation path.
In some preferred embodiments of the desalination system according to the invention, the solid-liquid separation device is selected from one or more of a filter, a centrifuge and a filter press.
In some preferred embodiments of the desalination system according to the invention, the lower head of the flash evaporator is conical, elliptical or spherical, preferably conical.
The method for removing the salt in the salt-containing organic wastewater by using the desalting system comprises the following steps:
s1, padding materials in a desalting system to a certain liquid level, starting a circulating pump, and establishing circulation;
s2, introducing a heat source into the heater, heating the circulating liquid by the heater, and then introducing the circulating liquid into a flash evaporator through a flash valve for flash evaporation, wherein a vapor-phase substance obtained by flash evaporation is discharged from the top of the flash evaporator out of a desalination system, and a liquid-phase substance obtained by flash evaporation is discharged from a liquid-phase outlet of the flash evaporator and continuously participates in circulation in a circulation passage; the circulating liquid contains at least one A alcohol;
s3, continuously introducing fresh salt-containing organic wastewater into the flash evaporator to supplement system material loss caused by vapor phase discharge in the flash evaporation process, and optionally continuously introducing alcohol A into the flash evaporator;
s4, introducing a mixed solution of fresh salt-containing organic wastewater and a circulating liquid into a solid-liquid separator, and when the concentration of alcohol A in the circulating liquid in the system is high enough, analyzing out salt in the organic wastewater, and separating from the system through a solid-liquid separation process;
s5, repeating the steps S1-S4 until the desalting system stably operates, so that the feeding amount of the fresh salt-containing organic wastewater, the feeding amount of the alcohol A, the discharging amount of separated salt, the discharging amount of vapor-phase substances obtained by flash evaporation and the discharging composition tend to be stable;
the alcohol A is an alcohol or mixture of alcohols that contains at least one alcohol that has a boiling point higher than the boiling point of water at the same operating pressure and does not form a low azeotrope with water. On the basis of meeting the condition, the catalyst also can contain low-boiling-point alcohols, the boiling point of the low-boiling-point alcohols is lower than that of water under the same operation pressure, or the low-boiling-point alcohols and water form low azeotrope, such as methanol, ethanol and the like.
The circulating liquid has the capacity of alcohol precipitation, and salt in fresh saline organic wastewater from upstream can be forced to be precipitated in a solid form. And during normal continuous and stable operation, the fresh salt-containing organic wastewater from the upstream enters a desalting system and is immediately mixed with the circulating liquid, and alcohol precipitation is carried out to separate out solid salt. And when the continuous and stable operation is normal, the solid salt is separated out and then sent to a solid-liquid separator for separation.
In some preferred embodiments of the desalination system of the invention, the alcohol a is at least one of ethylene glycol or butylene glycol.
In some preferred embodiments of the desalination system according to the utility model, the salt-containing organic wastewater comprises a alcohol, wherein the concentration of the a alcohol is 1-20 wt%;
in some preferred embodiments of the desalination system according to the utility model, the salt-containing organic wastewater does not contain a alcohol, and before step S1, the desalination system further comprises a pretreatment operation of the salt-containing organic wastewater, wherein an amount of a alcohol is added into the salt-containing organic wastewater, and the amount of a alcohol is preferably added so that the concentration of the a alcohol is 1-20 wt% of the concentration of the mixed solution of the salt-containing organic wastewater and the a alcohol.
According to some preferred embodiments of the desalination system of the utility model, when the desalination system is operated continuously and stably, the salt-containing organic wastewater can be subjected to a circulation flash process to prepare an alcohol-rich circulating liquid with stable alcohol precipitation capacity.
In some preferred embodiments of the desalination system according to the invention, the bedding material is selected from fresh salt-containing organic waste water containing a alcohol or a alcohol at an initial start-up stage. When fresh salt-containing organic wastewater is used as padding, the system needs to operate for a period of time and form stable alcohol-rich circulating liquid through circulating flash evaporation and concentration, so that the alcohol precipitation capacity is realized; the fresh A alcohol is used, so that the circulating liquid can have alcohol precipitation capacity without a circulating flash evaporation concentration stage.
According to some preferred embodiments of desalination system, in normal continuous steady operation, circulation liquid obtains for containing salt organic waste water through the circulation heating flash distillation, because high boiling point material can be enriched in the liquid phase, contains salt organic waste water forms stable rich alcohol liquid that has the alcohol analysis ability through the circulation heating flash distillation, meets the fresh containing salt organic waste water that comes from the upper reaches and can force wherein salinity to appear with solid form, and then can carry out solid-liquid separation, with salinity with its separation from the system in solid form.
In some preferred embodiments of the desalination system according to the invention, the circulation ratio in the circulation path is such that at this circulation ratio the concentration of alcohol species in the saturated liquid phase in vapor-liquid equilibrium with the saturated organic wastewater vapor exiting the desalination system is sufficiently high for the circulating liquid to have an alcohol precipitation capacity. Preferably, the circulation ratio is 0 to 100, more preferably 20 to 80, and still more preferably 30 to 80.
In some preferred embodiments of the desalination system according to the invention, the circulation ratio can be enumerated by 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 and any value therebetween.
In some preferred embodiments of the desalination system according to the utility model, in the salt-containing organic wastewater, the salt is discharged in the form of solid in the desalination system, and all the other materials are discharged in the form of steam in the desalination system, so as to realize the thorough desalination of the latter and avoid the latter to entrain the solid salt to enter the downstream device.
In some preferred embodiments of the desalination system according to the invention, the operating state of the circulation path is continuous operation. The liquid phase substance in the circulation path is always in a continuous circulation flowing state, so that on one hand, the deposition of solid salt can be prevented, and the system is blocked, on the other hand, if the solid-liquid separation is not thorough, the solid salt leaks into the liquid phase, the solid-liquid separation can be repeatedly carried out on the liquid phase, the accumulation of the solid is prevented, and the solid salt enters the discharge of flash steam, so that the discharge of the flash steam carries the solid salt.
According to the utility model discloses a some preferred embodiments of desalination system, under appointed flash distillation vapour pressure, the alcohol concentration in the rich alcohol circulating liquid is changed to the accessible adjustment circulation ratio, and then adjusts the flash distillation temperature to adapt to the heat source of different grades.
In some preferred embodiments of the desalination system according to the invention, the flash steam pressure can be adjusted to accommodate different refining separation methods in downstream equipment.
In the present invention, the term "azeotrope" refers to a homogeneous solution of two or more different components which, when mixed in a specific ratio, has only one boiling point at a fixed pressure, and this mixture is called azeotrope. When an azeotrope reaches its azeotropic point, the boiling of the azeotrope produces a fraction of the gas that is exactly the same as the fraction of the liquid.
In the present invention, the term "low azeotrope" refers to an azeotrope whose azeotropic point is at a temperature lower than the boiling point of the pure components that make up the azeotrope at the same operating pressure.
In the present invention, the term "high boiling point alcohol" refers to an alcohol substance having a boiling point higher than that of water under the same operating pressure and not forming a low azeotrope with water, such as ethylene glycol, butylene glycol, etc.
In the present invention, the term "low boiling point alcohol" refers to an alcohol substance having a boiling point lower than that of water under the same operating pressure or forming a low azeotrope with water, such as methanol, ethanol, etc.
The utility model discloses in, the term "circulation ratio" is the ratio of the commodity circulation mass flow through the circulating pump and the system contains salt organic waste water feeding mass flow.
The beneficial effects of the utility model reside in following several aspects at least:
one of which, contain salt organic waste water's desalination system adopts solid-liquid separation and vapour-liquid separation two-step method to realize the thorough separation of salinity and other components, and circulation loop's existence makes can relapse solid-liquid separation to the solid salinity that leaks to the liquid phase, effectively avoids the salinity to be smugglied secretly and gets into low reaches device.
It is two, contain salt organic waste water's desalination system, the existence scope of solid in desalination system is very little, and the solid-liquid system is in the state that the circulation flows always, avoids appearing the solid and subsides, piles up, the condition such as harden, has effectively reduced the risk of jam, improves the stability of device.
Thirdly, the desalting system for the salt-containing organic wastewater of the utility model reduces the temperature rise of the system due to the existence of the circulating flash evaporation, and can use a low-grade heat source for heat supply; for heat sources with different tastes, the circulation ratio can be adjusted to adapt to different heat source temperatures.
And fourthly, contain the desalination system of salt organic waste water, the almost whole vaporization that is used for organic waste water of the heat that the desalination system consumed of utilization, this heat can further be utilized in low reaches organic matter recovery unit, reduces the waste of energy, improves whole energy utilization.
Fifthly, the desalting system for the salt-containing organic wastewater of the utility model has the advantages of simple device, low cost and good adjustability; and the desalting system has good adaptability, and downstream operation such as pressurization rectification, vacuum rectification or atmospheric rectification can be performed.
Drawings
FIG. 1 is a flow chart of the desalting system for salt-containing organic wastewater according to examples 1-11; wherein, 1-a flash evaporator; 2-a circulating pump; 3-a heater; 4-a flash valve; 5-a centrifuge;
FIG. 2 is a flow chart of the desalting system for salt-containing organic wastewater according to example 12; wherein, 1-a flash evaporator; 2-a circulating pump; 3 a-a filter; 3 b-a filter; 4-a heater; 5-flash valve.
Detailed Description
The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited to the following description.
The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The equipment, instruments, valves, reagents or instruments used are conventional products which are commercially available, and manufacturers are not indicated.
In the following embodiments, the desalting procedures of examples 1-11 are shown in FIG. 1. The adopted system comprises a circulation passage consisting of a flash evaporator 1, a circulating pump 2, a heater 3 and a flash valve 4 which are sequentially connected in series, wherein a liquid phase outlet of the flash evaporator 1 is connected with an inlet of the circulating pump 2, an outlet of the flash valve 5 is connected with an inlet of the flash evaporator 1, a centrifugal machine 5 is used as a solid-liquid separator, and the flash valve 4 is used for reducing pressure. One branch of the outlet of the circulating pump 2 is connected with the inlet of the flash evaporator 1 through a centrifugal machine 5, and clear liquid obtained from the outlet of the centrifugal machine 5 is sent back to the flash evaporator 1. A salt-containing organic wastewater inlet is arranged between the circulating pump 2 and the centrifuge 5. Fresh organic wastewater is also sent to a centrifuge, organic wastewater vapor is extracted from the top of the flash evaporator 1, and salt is discharged from the centrifuge 5.
Example 1
The desalination process according to this example is shown in FIG. 1.
The flow rate of the salt-containing organic wastewater to be treated is 2150kg/h, the temperature is 50 ℃, and the pressure is 0.5 MPaG. The salt-containing organic wastewater comprises the following components: water, 83.72 wt%; ethylene glycol, 13.95 wt%; sodium chloride, 2.33 wt%. Wherein the normal boiling point of the ethylene glycol is 193.2 ℃ and is higher than the normal boiling point of water, and the ethylene glycol can be used for forming the alcohol-rich circulating liquid.
S1, introducing the salt-containing organic wastewater into a desalting system until the liquid level of a flash evaporator 1 reaches 50%, starting a circulating pump 2, and establishing circulation;
s2, introducing a heat source into the heater 3, heating the circulating liquid, and allowing the heated circulating liquid to enter a flash evaporator 1 through a flash valve 4 for flash evaporation, wherein steam obtained by flash evaporation is discharged from the top of the flash evaporator 1 to a desalination system, and a liquid-phase substance obtained by flash evaporation is discharged from the bottom of the flash evaporator 1 and continuously participates in circulation in the circulating passage; at the moment, the concentration of the ethylene glycol in the circulating liquid is gradually increased along with the progress of the circulating flash evaporation;
s3, a flow of circulating liquid is separated from an outlet of the circulating pump 2, the circulating liquid is converged with fresh organic wastewater from upstream, the mixed liquid is introduced into a centrifuge 5, and then the liquid discharged from the centrifuge 5 is sent back to the flash evaporator 1; the flow rate of the fresh salt-containing organic wastewater is to maintain the liquid level of the flash evaporator 1 at a constant value, and the liquid level is used for supplementing materials discharged in a steam form after flash evaporation;
s4, along with the flash evaporation, the concentration of the ethylene glycol in the circulating liquid is gradually increased, the moisture content is gradually reduced, salt is separated out from the circulating liquid, and then the salt is gradually and completely separated out in a centrifugal machine 5; on the other hand, after the newly added salt-containing organic wastewater is mixed with the alcohol-rich circulating liquid, salt is continuously separated out due to the alcohol precipitation effect, and the salt is continuously separated out in the centrifuge 5 immediately after the salt is separated out;
s5, repeating the steps S1-S4 until the desalting system runs stably and runs continuously.
Continuously feeding fresh salt-containing organic wastewater, continuously discharging salt and flash steam, wherein the composition and flow of the flash steam are close to those of the wastewater except the salt, and the rich alcohol circulating liquid and the flash steam at the moment form a steam-liquid equilibrium state. At the moment, the concentration of the ethylene glycol in the circulating liquid is increased to a stable value capable of generating alcohol analysis, salt is separated out by the alcohol analysis with the continuously fed fresh wastewater, and the salt is separated out in a centrifugal machine once being separated out; other components are heated and flashed along with the circulating liquid, are continuously flashed into steam in the flash evaporator, and continuously leave the system in a gas form, so that complete desalting is realized.
When the device runs stably, the circulation ratio is 20.44, the operating temperature of the flash evaporator 1 is 129.9 ℃, and the operating pressure is 5 kPaG; the outlet temperature of the heater 3 was 147.8 ℃.
The circulating liquid comprises the following relevant components: 17.14 wt% of water; ethylene glycol, 82.86 wt%; the related components in the flash steam are as follows: water, 86.37 wt%; ethylene glycol, 13.63 wt%, and the circulating liquid and flash steam form vapor-liquid equilibrium. After the cyclic flash evaporation, glycol as a heavy component is effectively enriched in the cyclic liquid, the concentration is obviously improved, and the cyclic flash evaporation method can be used for alcohol precipitation to force the salt in the saline organic wastewater to be separated.
In this example, the salt leaves the system as a solid, and the water and glycol are recycled, pressurized, heated, flashed at reduced pressure, and then leave the system as flash vapor. Because the physical properties of the flash steam and the solid are greatly different, compared with the condition of liquid-solid entrainment which is easy to occur, the flash steam is difficult to entrain the solid to enter a downstream device. The salt is separated out and then subjected to solid-liquid separation, the circulating liquid is subjected to vapor-liquid separation after flash evaporation, the separation of the salt and other components is finally realized by adopting a two-step separation method of solid-liquid separation and vapor-liquid separation, vapor and solid are not in direct contact, and the possibility that the solid salt carried by the flash evaporation vapor enters a downstream device can be effectively reduced even if the liquid and solid carry or the vapor and liquid carry.
And after the salt is separated from the liquid, immediately entering liquid-solid separation equipment for separation, removing the solid from the system, and continuously participating in circulating flash evaporation of the obtained clear liquid. After the device stably operates, the range of the solid existing in the system is compressed to a tiny area, and the solid is immediately removed once being separated out, so that the risk of blockage of parts such as pipelines, valves, heat exchange pipes and the like is effectively reduced.
For a solid-liquid system, a part with low flow velocity or static state in the system is not required to be generated, and various situations such as sedimentation, accumulation, stacking, hardening, blockage and the like of the solid are avoided. Since the liquid in the desalting system is always in a circulating flow state, the condition is difficult to occur. And for the solid generated in the starting stage or the solid leaked to the liquid phase due to incomplete solid-liquid separation, the solid-liquid separation can be carried out along with the circulating liquid repeatedly entering the solid-liquid separator, so that the solid-liquid separation effect is ensured, and the risk of system blockage is effectively reduced.
Examples 2 to 6
The desalination process according to this example is shown in FIG. 1.
The flow rate of the salt-containing organic wastewater to be treated is 5600kg/h, the temperature is 74.5 ℃, and the pressure is 0.1 MPaG. The salt-containing organic wastewater comprises the following components: water, 89.29 wt%; 1, 4-butanediol, 8.93 wt%; sodium chloride, 1.79 wt%. Wherein the normal boiling point of the 1, 4-butanediol is 228 ℃ and is higher than the normal boiling point of water, and can be used for forming the alcohol-rich circulating liquid.
The procedure was essentially the same as in example 1, except that a different recycle ratio was used.
When the circulation ratio of the device is changed, the temperature of the circulating liquid required to be reached before flash evaporation is changed, and the requirement on the grade of a heat source of the heater is also changed. Considering that saturated steam is the most common heat source in an actual production device, when the saturated steam is used as a heat source and the heat transfer temperature difference of the process side outlet of the heat exchanger is specified to be 20 ℃, the change of the temperature required by flash evaporation, the temperature of the heat source and the pressure of the heat source under different circulation ratios is shown in the following table 1.
TABLE 1
As can be seen from Table 1, when the circulation flash evaporation is not adopted, the organic wastewater needs to be heated to 215.7 ℃ to be vaporized, and at the moment, saturated steam with the pressure as high as 3.0MPaG is used as a heat source to ensure that the outlet of the heater has the heat transfer temperature difference of 20 ℃. When the circulation ratio is 28.2, the saturation vapor pressure is required to be 0.94 MPaG; after the circulation ratio is gradually increased to 82.8, the pressure of the saturated steam is required to be gradually reduced to 0.54 MPaG.
Thus, the greater the recycle ratio, the lower the temperature required at the flash valve inlet, i.e., the heater outlet, and the lower the heat source temperature requirement. When saturated steam is used as the heat source, the lower the requirement for saturated steam pressure. The circulating flash evaporation process can produce the alcohol-rich liquid, reduce the requirement on the grade of a heat source, use low-pressure steam with lower price, reduce the wall thickness of equipment such as a heater and the like and reduce the initial investment. If the plant only has a low-pressure steam pipe network and does not have a high-pressure steam pipe network, the system can use the low-pressure steam as a heat source to get rid of the dependence on the high-pressure steam.
Increasing the recycle ratio reduces the heat source grade requirements of the system, but the higher the recycle ratio, the higher the pump load, and not the better the recycle ratio. In actual production, the circulation ratio matched with the steam specification of the plant can be calculated according to the steam specification of the plant, and then a proper desalting system is designed, or the system is enabled to operate at a reasonable operating point, so that the system also has the characteristic of strong adaptability.
In addition, the reduction of the inlet temperature of the flash valve is also helpful for inhibiting the self-polymerization of the butanediol, reducing the loss of the butanediol and avoiding the interference of self-polymerization products on the system, such as scaling, raising the saturation temperature and viscosity of the system and the like. If a thermolytic heat-sensitive material is present in the system, lowering the temperature also helps to inhibit its decomposition, and is therefore equally applicable to salt-containing wastewater containing heat-sensitive materials.
Examples 7 to 11
The desalination process according to this example is shown in FIG. 1.
The flow rate of the organic wastewater to be treated was 1090kg/h, the temperature was 50 ℃ and the pressure was 0.5 MPaG. The salt-containing organic wastewater comprises the following components: water, 86.54 wt%; ethylene glycol, 4.81 wt%; ethanol, 4.81 wt%; sodium chloride, 3.84 wt%. Wherein the ethylene glycol has a normal boiling point of 193.2 ℃ and is higher than the normal boiling point of water, and is the main component in the alcohol-rich circulating liquid; ethanol has a normal boiling point of 78 ℃ lower than the normal boiling point of water and forms a low azeotrope with water.
The procedure was essentially the same as in example 1 except that the flashing of the desalination system was carried out at a different pressure to accommodate the use of a different separation method downstream. Because the gas is difficult to compress, the steam discharged by the flash evaporator is usually directly fed into a downstream rectifying device for refining, and the pressure of the flash steam is only slightly higher than the operating pressure of the downstream rectifying device and is used for overcoming the on-way resistance.
By adjusting the pressure of the flash steam, a desalting system adaptive to the downstream pressure can be obtained. When saturated steam is used as a heat source and the heat transfer temperature difference at the process side outlet of the heat exchanger is specified to be 20 ℃, the change of each parameter under different flash evaporation pressures is shown in the following table.
TABLE 2
As can be seen from Table 2, when the atmospheric distillation is performed downstream, the pressure of the flash steam can be set to 5kpa G for overcoming the resistance of downstream pipelines, tower internals and the like, and the temperature of the flash steam is 122.1 ℃ at the moment, and saturated steam of 0.53MPaG is required to be used as a heat source.
When the pressure reduction rectification of-25 kPaG is carried out at the downstream, the flash steam pressure is-20 kPaG, the flash steam temperature is 115.5 ℃, and the saturated steam of 0.22MPaG is required to be used as a heat source.
When the downstream is used for pressurized rectification of 0.3MPaG, the pressure of flash steam is 305kPaG, and the flash steam does not need to be additionally pressurized, so that a complex and expensive gas compression machine is avoided. For the working condition that downstream equipment is pressurized and rectified, the flash evaporation temperature is increased along with the increase of the flash evaporation pressure, so that the requirement on the grade of a heat source is also increased, and 1.46MPaG saturated steam is required to be used as the heat source. If the plant is unable to provide this level of steam, the temperature required for flashing can be reduced by increasing the recycle ratio as well, so that a lower grade heat source is used. When the recycle ratio is increased from 31.3 to 61.2, the pressure of the required saturated steam is reduced from 1.46MPaG to 1.15 MPaG. Therefore, the circulating flash evaporation desalting method has stronger adaptability.
In addition, no matter what rectification method is adopted by the downstream device, the wastewater and the organic matters enter the downstream device in the form of flash steam. Saturated vapor phase feed can reduce the heat duty of the column reboiler compared to liquid phase feed. This means that the heat that the desalination process of circulation flash distillation consumed can also carry out secondary utilization in downstream workshop section, has improved the utilization efficiency of energy.
Example 12
The desalination process according to this example is shown in FIG. 2. The adopted system comprises a circulation passage consisting of a flash evaporator 1, a circulating pump 2, a filter 3a, a filter 3b, a heater 4 and a flash valve 5 which are sequentially connected in series, wherein a liquid phase outlet of the flash evaporator 1 is connected with an inlet of the circulating pump 2, an outlet of the circulating pump 2 is connected with inlets of the filter 3a and the filter 3b, outlets of the filter 3a and the filter 3b are connected with an inlet of the heater 4, and an outlet of the heater 4 is connected with an inlet of the flash valve 5. The solid-liquid separator is constituted by a filter 3a and a filter 3b, and the flash valve 5 is used for reducing the pressure. The flash steam is discharged from a gas phase outlet of the flash evaporator 1; and discharging solid salt from the filter. The filter 3a and the filter 3b are connected in parallel and in a backup relationship with each other, and when one of them is stopped for cleaning, the other one is kept in normal operation. Fresh salt-containing organic wastewater is sent into a pipeline connecting an outlet of the circulating pump 2 with inlets of the filter 3a and the filter 3b from an upstream device, and is sent to the filter after being converged with circulating liquid.
The composition and flow rate of the organic wastewater to be treated were the same as in example 1.
S1, padding with fresh ethylene glycol, adding the ethylene glycol into a flash evaporator 1 from the outside to 50% of liquid level at one time, starting a circulating pump 2, and establishing circulation;
s2, introducing a heat source into a heater 4, heating the circulating liquid, and allowing the heated circulating liquid to enter a flash evaporator 1 through a flash valve 5 for flash evaporation, wherein steam obtained by flash evaporation is discharged from the top of the flash evaporator out of a desalination system, and liquid-phase substances obtained by flash evaporation are discharged from the bottom of the flash evaporator and continuously participate in circulation in the circulation passage;
s3, after flash evaporation is carried out in the step S2, introducing fresh salt-containing organic wastewater into the system, wherein the fresh wastewater is used for supplementing materials discharged from a desalting system by flash evaporation, and maintaining the liquid level of a flash evaporator to be stable;
s4, because the circulating liquid contains a large amount of glycol, salt in the organic wastewater is immediately separated out in a solid form after the organic wastewater meets the circulating liquid and is separated out in a filter, and other components in the organic wastewater discharged from the circulating system are added into the circulating liquid to participate in circulation;
s5, repeating the steps S1-S4 until the desalting system stably operates.
In the process, the concentration of the glycol in the circulating liquid is gradually reduced along with the continuous addition of the organic wastewater, but the concentration of the glycol is still far higher than that of the glycol in the organic wastewater feed; other components except the salt in the wastewater are flashed in the flash evaporator and leave the system in the form of steam, so that the complete salt removal is realized.
The ethylene glycol is used for replacing fresh organic wastewater to pad before the start and the operation, so that the circulating liquid has the alcohol precipitation capacity in the initial start stage, the condition that salt is precipitated in a flash evaporator in the circulating flash evaporation concentration process in the initial start stage is avoided, and the time consumption in the start stage is reduced. When the system operation reaches the steady state, the relevant operation parameters of each device are the same as those in example 1, and the composition of the circulating liquid is the same as that in example 1.
It should be noted that the above-mentioned embodiments are only used for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. Modifications may be made to the invention as specified within the scope of the claims and modifications may be made without departing from the scope and spirit of the invention. Although the present invention has been described herein with reference to particular means, materials and embodiments, it is not intended to be limited to the particulars disclosed herein, but rather the present invention extends to all other methods and applications having the same functionality.
Claims (6)
1. A desalting system for salt-containing organic wastewater comprises a heater, a flash evaporation valve, a flash evaporator and a circulating pump which are sequentially connected, wherein a liquid phase outlet of the flash evaporator is connected with an inlet of the circulating pump, an outlet of the heater is connected with an inlet of the flash evaporation valve, and an outlet of the flash evaporation valve is connected with an inlet of the flash evaporator; the solid-liquid separation device is connected with the circulating pump in series or in parallel.
2. The system of claim 1 wherein the solid-liquid separation device is located downstream of the point of mixing of the salt-containing organic wastewater with the recycle liquor of the desalination system.
3. The system according to claim 1 or 2, wherein when the solid-liquid separation device is connected with the circulating pump in parallel, the heater, the flash evaporation valve, the flash evaporator and the circulating pump are connected in series to form a circulating passage, and a branch of an outlet of the circulating pump is connected with an inlet of the flash evaporator sequentially through the salt-containing organic wastewater inlet and the solid-liquid separation device.
4. The system according to claim 1 or 2, wherein when the solid-liquid separation device is connected with the circulating pump in series, the outlet of the circulating pump is connected with the inlet of the heater sequentially through the salt-containing organic wastewater inlet and the solid-liquid separation device to form a circulating passage.
5. The system of claim 1, wherein the solid-liquid separation device is selected from one or more of a filter, a centrifuge, and a filter press.
6. The system of claim 1, wherein the lower head of the flash vessel is conical, elliptical, or spherical.
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| CN202023113900.7U CN214115234U (en) | 2020-12-22 | 2020-12-22 | Desalting system for salt-containing organic wastewater |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112499875A (en) * | 2020-12-22 | 2021-03-16 | 中国天辰工程有限公司 | Desalting system and method for salt-containing organic wastewater |
| CN115180672A (en) * | 2022-07-19 | 2022-10-14 | 北京清创晋华科技有限公司 | Boiler system and method for producing steam by using wastewater |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112499875A (en) * | 2020-12-22 | 2021-03-16 | 中国天辰工程有限公司 | Desalting system and method for salt-containing organic wastewater |
| CN115180672A (en) * | 2022-07-19 | 2022-10-14 | 北京清创晋华科技有限公司 | Boiler system and method for producing steam by using wastewater |
| CN115180672B (en) * | 2022-07-19 | 2024-05-17 | 北京清创晋华科技有限公司 | Boiler system and method utilizing waste water vapor |
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