Melamine crystallization apparatus and the equipment for using the deviceTechnical field
The present invention relates to a kind of crystallization apparatus for Melamine Production equipment and a kind of using the three of the crystallization apparatusPoly cyanamid production equipment.
Background technology
Currently, without using catalyst high pressure method and using catalyst with low pressure sideThe Melamine Production equipment of method operation provides the melamine purification step in water-soluble liquid phase, high-purity the purpose is to obtainSpend melamine.
After the purification step, it is necessary to melamine is detached from the mother liquor containing melamine.The operation is usually logicalCrystallization and subsequent solid/liquid separation (such as by centrifuging or filtering) are crossed to carry out.
It is well known that crystallization should in the best way carry out near specific saturation temperature.This temperature can be by notWith system realize, wherein the system that at most uses is to reduce by evaporation of the solvent, by temperature or grasped by hybrid systemThe system of work.
Logical overcooled crystallization is happened in the referred to as suitable device of " crystallizer ", the crystallizer generally include ontology andHeat exchanger, in the body, the suspension of melamine is placed in saturation mother liquor and crystal growth occurs in the body, and moltenLiquid is also referred to as the cooling of " refrigerant " and occurs in a heat exchanger.
The ontology for placing suspension is connected with heat exchanger typically via pipe, and ensures melamine by circulating pumpSuspension via heat exchanger cycle.
Crystallization is usually carried out by cooling melamine solution, which, which comes from, is located at crystallization apparatus upstreamProduction equipment a part.
This solution is supplied into the melamine suspension recycled in a heat exchanger.
Side (being usually pipe side) melamine suspension cycle to be cooled in a heat exchanger, and in the other side(being usually skirt section side) is usually recycled by the coolant liquid that recirculated water (tower water) forms.
It is completely dissolved the crystal shape that solution state in the liquid phase is converted to solid to be dispersed in saturation liquid phase from solidSuspended state existing for formula is occurred by forming embryo, and embryo is grown by with other embryos and crystal accumulation.EmbryoIt is formed and is preferably carried out at most cold spot faster reaching saturation, the inner surface of the pipe of this usual most cold spot and heat exchanger (withSolution itself contacts) it is consistent.
It is tended to adhere to due to the embryo of melamine on the cold surface that they are formed wherein, the heat contacted with solutionThe crystal layer that the surface of exchanger tube is gradually attached to thereon is covered, this effectively lowers its heat-exchange capacity until needingClean the degree of crystallizer.
Therefore, it is necessary to periodic cleaning crystallizers, and this requires Melamine Production equipment to be equipped with multiple crystallizers, to carry outOffline cleaning, and continuous operation equipment simultaneously.
This cleaning is carried out by 90 DEG C of hot water circuit, is related to multiple operations, wherein mainly having：
A) increase new crystallizer and remove production line to production line, and by the crystallizer being finished；
B) by discharging melamine suspension wherein included, the crystallizer being finished is emptied in specific tank；
C the crystallizer being finished) is filled with the softened water equal with the volume of the suspension of discharge；
D heat exchanger is isolated with cooling circuit), discharge cooling water contained therein and is connected to heating circuit；
E it) cyclic softening water and is heated until 90 DEG C；
F cycle) is maintained 12 hours；
G heat exchanger is isolated with heating circuit) and is connected to cooling circuit；
H) 60 DEG C will be water-cooled in crystallizer；
I) crystallizer is emptied by being drained in specific collecting tank.The water of discharge contains molten from fouling in the solutionSolution and in step B) in the melamine that may not be completely exhausted out；
J) crystallizer is filled with the melamine suspension being previously discharged.
During between cleaning in primary cleaning and next time, in the method, it is necessary to recycling be useful for it is cleaning,The water of melamine rich in dissolving.
In specific Melamine Production equipment, the water for cleaning is by supplying it in recycling water back and forthIt receives.
It should be noted that in order to limit the time and the amount that use water, in step B) in, crystallization apparatus is usually only arrangedWater, and do not flow into and completely remove the especially melamine slurry present in the ontology for placing suspension (with softeningBefore water cleaning).
Then, after cleaning, the melamine of Shuifu County used containing dissolving has higher concentration compared with such as mother liquorPercentage.
In addition, if in view of introduced in Melamine Production equipment the equipment arbitrary water should from being wherein discharged,It so must be then discharged from the equipment itself and be equal to the water for cleaning crystallizer for introducing the equipment.
In specific Melamine Production equipment, it converts the water of all introducings to mother liquor, the mother liquor is in addition to dissolvingHave outside melamine, other by-products that also containing cannot recycle gather to avoid it.The increase of this by-product concentration withAnd the purity of the latter can be then damaged with melamine coprecipitation.
Therefore, usual mother liquor causes melamine and by-product to be converted into ammonia and dioxy by resolution process, this decompositionChange carbon, or make melamine in solution and the insoluble reagent of by-product alternatively by being added, to make it be separated intoWaste.
Invention content
Therefore, applicants have discovered that problem, in both cases, equal to the water that supply to equipment is used to clean crystallizerThe melamine loss contained in the mother liquor amount of amount.
Therefore applicant considers how to reduce the amount of the melamine lost when each cleaning, give the target of setting themselvesIt is to provide logical overcooled crystallization apparatus, so as to realize such result.
Applicant also feels to need to provide a kind of mould assembly, which can be in terms of losing melamineAnd obtain cost savings in terms of the investment of device itself and production cost.
Therefore, root problem of the invention is to provide a kind of crystallization apparatus, which cleans every time in reductionWater and while thus reduce the melamine amount of loss, can be effectively cleaned.
As a part for this problem, it is an object of the invention to design a kind of crystallization apparatus, which canTo obtain cost savings in terms of losing melamine and in terms of the investment of device itself and production cost.
According to the first aspect of the invention, present invention is accordingly directed to a kind of melamine crystallization apparatus, the melamine knotsBrilliant device includes the ontology for placing suspension and at least one heat exchanger, the ontology and described at least one for placing suspensionA heat exchanger is connected with each other by pipe, and at least one circulating pump is arranged along the pipe, and it is characterized in that：In the placementAt least one hydraulic pressure bypass circuit is inserted between the ontology of suspension and at least one heat exchanger, the hydraulic pressure bypass is returnedAt least one heat exchanger is connected to being suitably selected for property of road the ontology for placing suspension or at least one heat exchangeAt least one recurrent canal of the hydraulic pressure scavenger circuit of device.
By a series of specific inspections and monitoring, applicant have surprisingly discovered that, the sheet of the placement suspension of crystallization apparatusBody actually non flouling behaviour in operation.
Applicant is therefore it has been confirmed that this phenomenon substantially only influences relative heat exchanger.
Therefore, applicants have recognized that implement geometry optimization possibility, it is hereby achieved that device itself investment andThe saving of production cost, while minimizing the water needed for cleaning device, to reduce loss melamine amount, show simultaneouslyIt writes energy saving.
In fact, applicant have verified that, by using the liquid that can bypass the ontology for placing suspension during cleaningBypass loop is pressed, the cleaning of heat exchanger can be individually carried out, the ontology to place suspension is isolated from scavenger circuit.
It is therefore advantageous that the same ontology of the placement suspension can continue on for the crystallization of melamine, with differenceHeat exchanger work in combination.
In addition, the ontology for not cleaning placement suspension advantageously causes required cleaning discharge reduction about 70%, prevent simultaneouslyThe corresponding loss of melamine is stopped, which is currently being discharged from equipment or is being recycled as ejected wash waterPre-treatment mother liquor during be decomposed.
According to second aspect, the present invention relates to a kind of Melamine Production equipment including melamine crystallization apparatus,It is characterized in that, implements the crystallization apparatus as described above.
Advantageously, Melamine Production equipment according to the present invention realizes above-mentioned about melamine according to the present inventionThe technique effect of crystallization apparatus.
The present invention at least in one of above-mentioned aspect can have at least one of following preferred feature；After especiallyPerson can be combined with each other as needed to meet specific application demand.
Preferably, crystallization apparatus includes at least two heat exchangers, and it is outstanding that at least one hydraulic pressure bypass circuit is inserted in placementBetween the ontology of supernatant liquid and each heat exchanger.
It is highly preferred that corresponding hydraulic pressure bypass circuit is inserted between each heat exchanger and the ontology for placing suspension.
Using multiple heat exchangers (each heat exchanger is associated with hydraulic pressure bypass circuit), advantageously allow for implementing to crystallizeDevice be can continuous work, while cyclically executing cleaning operation.
In fact, bypass loop allows primary selectively one heat exchanger of exclusion, to which the heat exchanger will be subjected toCleaning, and crystallization apparatus can be continuing with one or more of remaining heat exchanger to run.
The sizable optimization for also obtaining the global geometric shape of relevant device in this way need not be everyA heat exchanger provides the ontology for placing suspension.
Accordingly, it is considered to the ontology for placing suspension and the thus associated tank with relevant instrument and equipment is not present,Pump, pipe and accessory, realize considerable saving in terms of installation volume and cost, and suspension is placed referring for example to using threeThe equipment of ontology, the saving may also reach up the 21% of crystalline portion cost of investment.
Preferably, at least one hydraulic pressure bypass circuit includes multiple closing devices, and the closing device is suitably selected forProperty by least one heat exchanger with the ontology for placing suspension or with described in the scavenger circuit at least oneA recurrent canal connection.
It is highly preferred that the closing device in hydraulic pressure bypass circuit includes the inlet tube for being arranged in the ontology for placing suspensionOn the first shut-off valve, be arranged in it is described place suspension ontology outlet on the second shut-off valve, and along it is described extremelyAt least one third shut-off valve of few recurrent canal arrangement, at least one recurrent canal enter described in the heat exchangerExtend between mouth pipe and the outlet.
Alternatively, the closing device in hydraulic pressure bypass circuit includes being arranged on the inlet tube of at least one heat exchangerFirst shut-off valve, be arranged in place suspension ontology outlet on the second shut-off valve and along at least one recurrent canal arrangeAt least one third shut-off valve, outlet and at least one heat of at least one recurrent canal at least one heat exchangerExtend between the inlet tube of exchanger.
Preferably, the closing device in hydraulic pressure bypass circuit includes a pair of of third along at least one recurrent canal arrangementValve.
It is highly preferred that the inlet tube that the first valve in the pair of third valve is arranged in the ontology for placing suspension is attachedClosely, i.e., near the outlet of described at least one heat exchanger.
It is highly preferred that the outlet that the second valve in the pair of third valve is disposed in the ontology for placing suspension is attachedClosely, i.e., near the inlet tube at least one heat exchanger.
Advantageously, along a pair of of third valve of at least one recurrent canal arrangement this arrangement ensures that working as the heat exchangeThe stagnation of slurry is reduced in recurrent canal when device is connected to the ontology for placing suspension, to reduce the pipe fouling and/or blockingRisk.
Even further preferably, recurrent canal includes the outlet for being inserted into a pair of third valve.
It is expedient to when heat exchanger is connected to the ontology for placing suspension, outlet allows to empty recurrent canal, toCompletely eliminate the risk of the pipe fouling and/or filling.
Preferably, hydraulic pressure scavenger circuit further includes at least one for introducing the first entrance pipe of ejected wash water and for dischargingSecond delivery pipe of ejected wash water.
Preferably, the skirt section side of at least one heat exchanger is connected to thermal conditioning circuit, the thermal conditioning circuit packetAt least first pipe and the second pipe are included, first pipe is alternatively used for introducing cooling water and/or discharges condensate, and described secondPipe is alternatively used for introducing steam and/or discharges cooling water.
Preferably, the crystallization apparatus includes at least one entrance for introducing pending solution, described at least oneEntrance includes closing device, and the opening and closing for closing device are by the control device based on melamine purification pressure operationControl.
It is highly preferred that being placed on multiple crystallization apparatus by the same control device for purifying pressure to control opening and closingThe closing device on each entrance for introducing pending solution.
The configuration advantageouslys allow for keeping identical generic calibration for each closing device.
Preferably, each entrance of multiple crystallization apparatus includes the closing device according to the their own of purification pressure control.
Easily, which allows the maintenance for being consecutively carried out shut-off valve, without arrestment.
Optionally, single closing device can be set, which is arranged to be controlled according to purification pressure, and is sharedGround is arranged between the entrance of multiple crystallization apparatus.
The configuration advantageouslys allow for executing equipment optimization, because it needs to install lesser amount of component.
Description of the drawings
Refer to the attached drawing, by following to some detailed description of preferred embodiment, other features and advantages of the present invention willIt is clearer.
As described above, the different characteristic in single configuration can be combined with each other as needed, to utilize from specificThe advantages of combining the ad hoc fashion obtained.
In these figures,
- Fig. 1 is the schematic side elevation of the first preferred embodiment of melamine crystallization apparatus according to the present invention；
- Fig. 2 is the schematic side elevation of the second preferred embodiment of melamine crystallization apparatus according to the present invention；
- Fig. 3 is the schematic plan view of the third preferred embodiment of melamine crystallization apparatus according to the present invention；
- Fig. 4 is the schematic plan view of the 4th preferred embodiment of melamine crystallization apparatus according to the present invention.
Specific implementation mode
In the following description, identical reference numeral is used for the explanation of attached drawing, to indicate construction with the same functionElement.In addition, in order to illustrate it is clear, some reference numerals may not repeat in all the appended drawings.
With reference to figure 1, shows the first embodiment of melamine crystallization apparatus according to the present invention, integrally use reference numeral10 indicate.
Crystallization apparatus 10 includes the ontology 11 for the placement suspension that heat exchanger 12 is connected to by circulating pump 13.
The skirt section of heat exchanger 12 is connected to thermal conditioning circuit 14,15, which includes selectively usingIn the first pipe 14 for introducing cooling water and discharge condensate and it is alternatively used for introducing steam and discharging the second of cooling water managing15。
Additionally provide the hydraulic pressure scavenger circuit 21,26,27 of device 10 comprising Duo Geguan, multiple pipe include for drawingEnter ejected wash water and the first entrance pipe 27 equipped with corresponding inlet shut-off device 27a, for ejected wash water to be discharged and equipped with correspondingThe second discharge pipe 26 of port closing device 26a and for the return of scavenger circuit and the third pipe 21 of closing.
Crystallization apparatus 10 further includes the entrance 16 of pending melamine solution and including melamine crystals and waterThe outlet 17 of slurry.
The opening and closing of entrance 16 are controlled by the control device 18 of the purification pressure of control the first closing device 19.It is specialNot, entrance 16 is arranged on the outlet line 23a of the exchanger of the upstreams shut-off valve 22a.
Slurry outlet 17 is formed directly on the ontology 11 for placing suspension.
Crystallization apparatus 10 also includes the normal operating and control for device itself in a manner well known in the artMultiple other pipelines, valve and instrument are not shown here for more clearly indicating for the present invention.
According to the present invention, hydraulic pressure bypass circuit 20 is inserted between the ontology 11 and heat exchanger 12 for placing suspension, packetIt includes multiple second and closes device 22a, 22b, 22c, they are cleaned by heat exchanger with the ontology 11 for placing suspension or with hydraulic pressureThe recurrent canal 21 in circuit 21,26,27 is selectively connected.
Bypass circulation 20 is consequently adapted to that the ontology 11 for placing suspension is isolated with heat exchanger 12 during cleaning.ThisSample, only heat exchanger 12 are washed.
Particularly in Fig. 1, it includes being arranged in placement to hang that the second of hydraulic pressure bypass circuit 20, which closes device 22a, 22b, 22c,The first shut-off valve 22a on the inlet tube 23 of the ontology 11 of supernatant liquid, it is arranged on the outlet 24 for the ontology 11 for placing suspensionThe second shut-off valve 22b and along recurrent canal 21 arrange a pair of of third shut-off valve 22c.The recurrent canal 21 is in heat exchanger 12Outlet 23a and inlet tube 24a between extend.
With reference to Fig. 2, the second embodiment of crystallization apparatus according to the present invention is shown, it is whole to be indicated with reference numeral 10'.
In a second embodiment, it shows and is returned shown in the first embodiment during hydraulic pressure bypass circuit 20 substitutes referring to Fig.1Road.
Particularly, it includes being arranged in heat exchange that second of the hydraulic pressure bypass circuit 20 in Fig. 2, which closes device 22a, 22b, 22c,The first shut-off valve 22a on the outlet 23a of device 12, second section be arranged on the outlet 24 for the ontology 11 for placing suspensionOnly valve 22b and a pair of of the third shut-off valve 22c arranged along recurrent canal 21.And in this case, which existsExtend between the outlet 23a of heat exchanger 12 and the inlet tube 24a of heat exchanger 12.In this case, entrance 16 is arrangedThe downstream of shut-off valve 22a on the suction line 23 of ontology 11 for placing suspension.
With reference to figure 3, the 3rd embodiment of crystallization apparatus according to the present invention is shown, it is whole to be indicated with reference numeral 10 ".
In the third embodiment, the ontology 11 for individually placing suspension is arranged to be connected to three by corresponding circulating pump 13A heat exchanger 12.
Crystallization apparatus 10 " includes three individual entrances 16 of pending melamine solution, open and close byThe corresponding control device 18 for purifying pressure controls, and the corresponding control device control of the purification pressure is arranged in 20 upstream of bypass loopEach of it is corresponding first close device 19.
The outlet 17 for the slurry for including melamine crystals and water is also formed on the ontology 11 for placing suspension.
According to the present invention, the bypass loop 20 of type described in embodiment referring to Fig.1 is inserted into the ontology 11 for placing suspensionBetween heat exchanger 12, being suitably selected for property by corresponding heat exchanger 12 to place suspension ontology 11 or with it is correspondingThe recurrent canal 21 of hydraulic pressure scavenger circuit 21,26,27 connects.
With reference to Fig. 4, the fourth embodiment of crystallization apparatus according to the present invention is shown, it is whole to use reference numeral 10 " ' tableShow.
In the fourth embodiment, the ontology 11 for individually placing suspension is arranged to be connected to three each by circulating pump 13On heat exchanger 12.
Crystallization apparatus 10 " ' include the single entrance 16 of pending melamine solution, it opens and closes and is pressed by purificationThe single control device 18 of power controls, and the single device 18 of closing of the purification pressure controls the downstream for being arranged in bypass loop 20The corresponding alternating for closing device 19 opens and closes.
The outlet 17 for the slurry for including melamine crystals and water is also formed on the ontology 11 for placing suspension.
According to the present invention, the corresponding bypass loop 20 of the type with reference to described in the embodiment in Fig. 2 is inserted in placement and hangsBetween the ontology 11 and heat exchanger 12 of supernatant liquid, be suitable for by corresponding heat exchanger 12 with place suspension ontology 11 orIt is connected with the recurrent canal of corresponding hydraulic pressure scavenger circuit 21,27,26.
Operation of the melamine crystallization apparatus according to the present invention in cleaning step is as follows.
Once the heat exchanger 12 of crystallization apparatus 10,10', 10 ", 10 " ' is finished and must be subjected to clean, then accordinglyThe ontology 11 that bypass loop 20 is actuated to place suspension is isolated with corresponding scavenger circuit 21,26,27.
Thus, it is only required to which the emptying for the heat exchanger 12 to be cleaned is discharged by will be received in melamine suspension thereinEnter and is carried out in specific tank.
Hereafter, normal cleaning operation is carried out, but this only influences washed heat exchanger 12.Thus, for example filling outIt fills water used in softened water and is substantially less than the prior art, and lesser amount of suspension has been discharged.
It with particular reference to equipment according to prior art, is operated with three crystallization groups, each crystallization group includes its ownPlacement suspension ontology, then in each cleaning, suspension that discharge total volume is 125 cubic metres.
Comparatively, in the equipment of type shown in Fig. 3, it is only 40mc to clean required volume, and being equivalent to reduces motherThe melamine lost in liquid processing procedure, and heat and cool down 68% of the steam and water needed for the substance.
In cleaning process, the ontology 11 of the placement suspension of crystallization apparatus 10,10', 10 ", 10 " ' will not be drained, andAt least one of and if crystallization apparatus 10 ", 10 " ' includes multiple heat exchangers 12, can continue with these heat exchangers 12It operates in association.
The present invention melamine crystallization apparatus and relevant Melamine Production equipment feature as its advantage fromOn description in can clearly be seen that.
Without departing from the teachings of the present invention, other modifications of above-described embodiment are possible.
Finally, it is clear that a variety of change can be carried out to the melamine crystallization apparatus and Melamine Production equipment so conceivedBecome and modification, all these changes and modification are each fallen in the present invention；Moreover, all details can use technically equivalent memberUsually instead of.
In practice, the material and size that modification uses can be required according to technology.