CN104548652A - Continuous evaporative crystallization system - Google Patents
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- 238000002425 crystallisation Methods 0.000 title claims abstract description 57
- 230000008025 crystallization Effects 0.000 title claims abstract description 53
- 239000007788 liquid Substances 0.000 claims abstract description 101
- 230000009194 climbing Effects 0.000 claims abstract description 54
- 239000000498 cooling water Substances 0.000 claims abstract description 50
- 239000013078 crystal Substances 0.000 claims abstract description 22
- 239000002994 raw material Substances 0.000 claims abstract description 15
- 239000000463 material Substances 0.000 claims description 76
- 230000006835 compression Effects 0.000 claims description 23
- 238000007906 compression Methods 0.000 claims description 23
- 238000010438 heat treatment Methods 0.000 claims description 18
- 230000003020 moisturizing effect Effects 0.000 claims description 13
- 230000000694 effects Effects 0.000 abstract description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 18
- 238000001704 evaporation Methods 0.000 description 24
- 230000008020 evaporation Effects 0.000 description 23
- 238000004134 energy conservation Methods 0.000 description 18
- 238000000034 method Methods 0.000 description 15
- 238000005516 engineering process Methods 0.000 description 12
- 230000008569 process Effects 0.000 description 8
- 238000005265 energy consumption Methods 0.000 description 6
- 230000008901 benefit Effects 0.000 description 5
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 4
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- 239000002699 waste material Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
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- 239000000203 mixture Substances 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 description 2
- 230000003044 adaptive effect Effects 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
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Abstract
The invention relates to a continuous evaporative crystallization system comprising a raw material inlet, a water replenishing inlet, a preheater, a climbing film evaporator, a gas-liquid separator, a compressor, a pipeline heater, a crystal separator and a PLC (programmable logic controller) automatic control system, wherein an inlet, a first outlet, a second outlet and a third outlet are formed in the gas-liquid separator; the preheater is connected with the climbing film evaporator by virtue of a pipeline, and the climbing film evaporator is connected with the inlet of the gas-liquid separator; the compressor is connected between the gas-liquid separator and the climbing film evaporator by virtue of a stem conveying pipeline; a circulating evaporator is connected between the second outlet and the inlet by virtue of a pipeline; the cooling water after heat exchange of the climbing film evaporator and the cooling water after heat exchange of the circulating evaporator are used as hot sources of the preheater; a cooling water output end of the preheater and the water replenishing inlet are used for replenishing water for the system; the crystal separator is connected with the third outlet of the gas-liquid separator; and the PLC automatic control system is arranged in the continuous evaporative crystallization system to ensure that the continuous evaporative crystallization system has optimized and stable parameters, can save energy and raw materials, and is good in crystallization effect.
Description
Technical field
The invention belongs to evaporation and crystallization system, particularly relate to a kind of with energy-conservation and continuous evaporative crystallization system that is water-saving result.
Background technology
At present, function of mechanical steam recompression Mechanical Vapor Recompression technology is a kind of high-efficient energy-saving environment friendly technology, is called for short MVR.Although disclose a lot of continuous evaporative crystallization system adopting mechanical vapor recompression technology in prior art, but unreasonable due to technological design, a lot of function of mechanical steam recompression continuous evaporative crystallization system generally only has single-stage vapor compression machine to the heat supply of evaporimeter, in crystallizer part, material does not still carry out a large amount of heat supplies, cause the crystallization effect of existing function of mechanical steam recompression continuous evaporative crystallization system bad, the problem such as grain size number is tiny as occurred.Certainly, also part producer is had can to increase jet chimney with supplementary crystalline portion heat supply, but considerably increase the complexity of MVR continuous evaporative crystallization system, and rely on steam boiler, make MVR system without its original significant advantage-break away from dependence to steam boiler.
For these problems, publication number is disclose a kind of function of mechanical steam recompression continuous evaporative crystallization system of solving the problem and method in CN103203116A Chinese invention patent application prospectus, this function of mechanical steam recompression continuous evaporative crystallization system have employed two Mechanical Vapor Compression, and two compressors are respectively to evaporimeter and crystallizer heat supply, also one-level recovery has been carried out to cooling water sensible heat, for preheating, but this continuous evaporative crystallization system have employed two Mechanical Vapor Compression, the equipment cost buying two Mechanical Vapor Compression is very high, and do not have rational structure to be heated to bubble point temperature to material in advance, the energy consumption of therefore starting two compressors is also very high, structure is numerous and diverse, cause energy-saving effect also unsatisfactory, input cost is still unreasonable with the ratio of the income saved, also MVR continuous evaporative crystallization system is caused to be difficult to promote in China.
Secondly; the technique of existing MVR continuous evaporative crystallization system is not only immature; and due to MVR continuous evaporative crystallization system complexity; often can be subject to interference miscellaneous; lack adaptive FEEDBACK CONTROL; parameter once instability easily cause crystallization effect difference or crystalline rate low, be equally also increase actual consumption factor.
Except energy-conservation, the also few of existing MVR continuous evaporative crystallization system considers recycling of water route, cause existing MVR continuous evaporative crystallization system continuous flow procedure can discharge many cooling waters, not only rationally do not recycle the heat energy of cooling water, prevent the pollution of cooling water, and need steam new in a large number to fill into, waste water resource.
Summary of the invention
Goal of the invention of the present invention is to provide a kind of continuous evaporative crystallization system adopting MVR technology, this continuous evaporative crystallization system process is reasonable, cost is low, raw material is without waste, technological parameter controls automatically and continuity is good, adopts this continuous evaporative crystallization system also with fine crystalline rate and energy-saving effect.
In order to realize foregoing invention object, present invention employs following technical scheme:
A kind of continuous evaporative crystallization system, described system comprises feed(raw material)inlet, preheater, climbing film evaporator, gas-liquid separator, function of mechanical steam recompression machine, forced-circulation evaporator, crystal separator and a PLC automatic control system;
Described preheater, climbing film evaporator and forced-circulation evaporator are all heat exchange units; Its include be connected material input, material output and the thermal source input be connected, cooling water output;
Described gas-liquid separator comprise entrance for sending into gas-liquid mixed material, for export steam the first outlet, for feed liquid forced circulation the second outlet and send the 3rd outlet of crystallization for feed liquid;
Described feed(raw material)inlet connects the material input of preheater by pipeline, and the material output of preheater connects the material input of climbing film evaporator by pipeline, the material output of climbing film evaporator connects the entrance of gas-liquid separator;
Described function of mechanical steam recompression machine is connected between the first outlet of gas-liquid separator and the thermal source input of climbing film evaporator by steam conveying pipe, vapour pressure in order to be exported by described gas-liquid separator shortens superheated steam into and sends into climbing film evaporator, rises film heat to realize material;
The material input of described forced-circulation evaporator connects the second outlet of gas-liquid separator, and the material output of forced-circulation evaporator is linked back the entrance of gas-liquid separator; The thermal source input of forced-circulation evaporator directly connects the compressed steam output of function of mechanical steam recompression machine compression;
The cooling water output of described climbing film evaporator and forced-circulation evaporator is connected by pipeline and cooling water is sent into the thermal source input of preheater, in order to the material supplementary heating flowed through in preheater;
Described crystal separator connects the 3rd outlet on described gas-liquid separator;
It is following three control loops of controller that described PLC automatic control system at least comprises with PLC:
I feeding temperature control loop comprises:
-electric heater between feed(raw material)inlet and preheater;
-first flow control valve between feed(raw material)inlet and electric heater; With
-the first temperature measuring unit between preheater and climbing film evaporator;
Described first temperature measuring unit signal connects PLC, PLC output and divides level signal to connect electric heater and first flow control valve;
Ii compressed steam control loop comprises:
-be positioned at function of mechanical steam recompression machine after, the second temperature measuring unit before climbing film evaporator thermal source input; And
-frequency converter
Described second temperature measuring unit signal connects PLC; PLC connects function of mechanical steam recompression machine, to control the compression horsepower of function of mechanical steam recompression machine by frequency converter;
Iii gas-liquid separator liquid level control loop comprises:
-be arranged on liquid level gauge on gas-liquid separator; With
-be arranged on gas-liquid separator second to export the 4th flow control valve between forced-circulation evaporator material input;
Described liquid level gauge signal connects PLC, PLC signal and connects and control the 4th flow control valve.
As preferred version of the present invention:
Described system also comprises moisturizing entrance and pipeline heater;
The cooling water output of described preheater and moisturizing entrance remittance merga pass pipeline heater are connected into the compressed steam pipeline after function of mechanical steam recompression machine output;
Described PLC automatic control system also comprises the 4th following control loop:
Iiii fills into automatic steam control loop and comprises:
-be arranged on the second control valve of moisturizing entrance output;
-be installed on pipeline heater after, the 3rd temperature measuring unit before being connected into compressed steam pipeline;
-be installed on the 3rd temperature measuring unit after, the 3rd flow control valve before being connected into compressed steam pipeline; And
-be installed on the 4th temperature measuring unit of climbing film evaporator material output;
Described 3rd temperature measuring unit, the 4th temperature measuring unit divide level signal to connect the input of PLC; The output of described PLC connects and control valve channel heater, second control valve and the 3rd flow control valve respectively.
State on the invention in the system of preferred version, the cooling water of finally discharging in preheater is continuously evaporated again crystal system and supplements as a water resource of moisturizing porch, thus the heat of farthest reuse cooling water, and also save water resource.
As preferred version of the present invention:
Described crystal separator comprises the 3rd entrance exported, crystallize out delivery outlet and the feed liquid delivery outlet that connect on described gas-liquid separator, and described feed liquid delivery outlet is connected into the material input of described forced-circulation evaporator.
Scheme as a further improvement on the present invention:
Also comprise surge tank and cooling water conveying pump; Surge tank and cooling water conveying pump are located on the pipeline before the thermal source input of preheater successively; Described climbing film evaporator is connected preheater by surge tank with cooling water conveying pump all successively with the cooling water output of forced-circulation evaporator.
As further improvement project of the present invention:
Pipeline between second outlet of described gas-liquid separator and the material input of forced-circulation evaporator is provided with forced circulation pump.Further, the feed liquid delivery outlet of described crystal separator is connected into the material input of forced-circulation evaporator by forced circulation pump; Described 4th flow control valve is between forced circulation pump and forced-circulation evaporator material input.
Have employed the continuous evaporative crystallization system of technique scheme, there is following beneficial effect:
One, this system only adopts single Mechanical Vapor Compression, with more existing adopt compared with the continuous evaporative crystallization device of mechanical vapor recompression technology, the Mechanical Vapor Compression of its default unit price costliness, cost is low.
Two, this system only continuous evaporative crystallization system of setting up of single Mechanical Vapor Compression, also multistage recovery indirect steam being carried out to energy can be achieved, the sensible heat of final withdrawal indirect steam and latent heat, and gas-liquid separator is entered to material and crystal separator carries out level forced circulation, also the heat of indirect steam is taken full advantage of in forced circulation, very energy-conservation, and it utilizes forced circulation to gas-liquid separator even crystal separator Feedback heat, make up the short slab that crystal separator lacks heating, thus improve crystalline rate and effect.
Three, of the present inventionly the central controlled multi-point automatic control system of PLC is established, thus control the key parameter of whole system, so, this system is not only farthest made to make energy saving optimizing, stable state is entered fast when this continuous evaporative crystallization system can also be allowed just to start, therefore interval shutdown process energy loss is few, thus crystalline quality is able to stability contorting.In addition, the foundation of automatic control system also makes technique suddenly change can self-adaptative adjustment, and process disturbance is few, thus makes continuous evaporative crystallization system continuity of the present invention good, more energy-conservation.
In sum, continuous evaporative crystallization system provided by the invention not only rational technology, and it is cheap to build the equipment cost religion that this continuous evaporative crystallization system adopts, realizes material and heat energy without waste, automatic control, process stabilizing, interference is few, is beneficial to consecutive production, continuous crystallisation quality control is out consistent, reach good energy-saving effect, and pollutant emission is few, may be only water simultaneously.
Accompanying drawing explanation
Fig. 1: the process flow diagram of continuous evaporative crystallization system in the embodiment of the present invention.
Detailed description of the invention
Below in conjunction with accompanying drawing, the present invention is described further.
Embodiment 1:
A kind of continuous evaporative crystallization system as shown in Figure 1, this system is primarily of feed(raw material)inlet 1a, moisturizing entrance 1b, preheater 2, climbing film evaporator 3, gas-liquid separator 4, function of mechanical steam recompression machine 5, forced-circulation evaporator 7, pipeline heater 12, crystal separator 6, surge tank 13, forced circulation pump 10, cooling water conveying pump and a PLC automatic control system.PLC automatic control system comprises again four control loops.Four automatic control loops are feeding temperature control loop respectively, compressed steam control loop, fill into automatic steam control loop and gas-liquid separator liquid level control loop.
Above-mentioned band preheater 2, climbing film evaporator 3 and forced-circulation evaporator 7 mainly through heat exchange mode to the heating material flow in it, therefore, its structure is heat exchange unit, and it all has the material input flowed into for material, flows through in it material output having flowed out heating or evaporation; Also there is the thermal source input and cooling water output, totally four ports that flow into thermal source.As in Fig. 1, Reference numeral is specific as follows: the material input 20 of preheater, the material output 21 of preheater, the thermal source input 22 of preheater and the cooling water output 23 of preheater; The material input 30 of climbing film evaporator, the material output 31 of climbing film evaporator, the thermal source input 32 of climbing film evaporator and the cooling water output 33 of climbing film evaporator; The cooling water output 73 of the material input 70 of forced-circulation evaporator, the material output 71 of forced-circulation evaporator, forced-circulation evaporator thermal source input 72 and forced-circulation evaporator.
And the top of above-mentioned gas-liquid separator 4 is provided with the entrance 40 for sending into gas-liquid mixture and the first outlet 41 for exporting steam, the bottom of gas-liquid separator 4 be provided with for feed liquid forced circulation the second outlet 42 and send the 3rd outlet 43 of crystallization for feed liquid, air filter formula screen pack 44 is provided with on the entrance 40 of gas-liquid separator 4 and on the gas-liquid separator 4 of the upper/lower positions of the first outlet 41, air filter formula screen pack 44 is that a stratum reticulare is high between 80-150mm, the silk screen of order number between 300-500 order, and air filter formula screen pack 44 outward flange is connected with gas-liquid separator 4 inner wall sealing, upper and lower two chambers will be divided in gas-liquid separator 4.
After describing above-mentioned several equipment, we describe the continuous evaporative crystallization system without building automatic control loop, and concrete system syndeton is as follows:
As shown in Figure 1, above-mentioned raw materials entrance 1a connects the material input 20 of preheater 2 by pipeline, pipeline drives its feeding preheater 2 by feeding engine 9, material output 21 pipeline of preheater 2 connects the material input 30 bottom climbing film evaporator 3, material carries out climbing-film evaporation after flowing to climbing film evaporator 3, spray from the material output 31 of climbing film evaporator 3, climbing film evaporator 3 material output 31 connects the entrance 40 on above-mentioned gas-liquid separator 4 again.Then, the feed liquid of sending of gas-liquid separator 4 connects the entrance 60 of crystal separator 6 for the 3rd outlet 43 of crystallization by pipeline, crystal separator 6 is also provided with crystallize out delivery outlet 61 and feed liquid delivery outlet 62, the crystallize out delivery outlet 61 of crystal separator 6 connects the holding tank 8 below it.
As shown in Figure 1, on the other hand, above-mentioned gas-liquid separator 4 pairs of materials have carried out gas-liquid separation, for exporting the input of the first outlet 41 by steam conveying pipe connection Mechanical Vapor Compression 5 of steam in gas-liquid separator 4.The output of Mechanical Vapor Compression 5 is connected into the thermal source input 32 of climbing film evaporator 3 by steam conveying pipe, the superheated steam shortened in order to the vapour pressure first of gas-liquid separator the outlet 41 exported also sends into climbing film evaporator 3, become hot water by steam-condensation and hot water cooling method release latent heat and sensible heat again, in climbing film evaporator 3, rise film heat to realize material.
In addition, system of the present invention also has two-stage forced circulation, as shown in Figure 1, above-mentioned forced-circulation evaporator 7 is connected between the second outlet 42 of gas-liquid separator 4 and the entrance 40 of gas-liquid separator by pipeline, specifically the material input 70 of forced-circulation evaporator 7 exports 42 with second of gas-liquid separator 4 and is connected, the material output 71 of forced-circulation evaporator 7 is linked back by pipeline the entrance 40 of gas-liquid separator, above-mentioned forced circulation pump 10 is located on the pipeline between the second outlet 42 of gas-liquid separator and the material input 70 of forced-circulation evaporator 7, this is forced-circulation evaporator 7 pairs of gas-liquid separator first order forced circulation.The feed liquid delivery outlet 62 of crystal separator 6 is also connected into the material input 70 of forced-circulation evaporator 7 by forced circulation pump 10, this is the second level forced circulation of forced-circulation evaporator 7 pairs of crystal separators 6.And the thermal source input 72 of forced-circulation evaporator 7 connects the superheated steam output directly connecting function of mechanical steam recompression machine 5 and compress.
Most importantly, the present invention also uses the hot water of climbing film evaporator 4 cooling water output 33 and the output of forced-circulation evaporator 7 cooling water output 73, utilize the obvious of these hot water further, namely the thermal source input 22 of preheater 2 is connected by pipeline, in order to the material supplementary heating flowed through in preheater 2, thus energy-conservation further.Particularly, in order to prevent, hot water is excessive to be poured, and above-mentioned surge tank 13 and cooling water conveying pump are located on the pipeline before the thermal source input 22 of preheater 2 successively.Therefore, the cooling water output 33 of climbing film evaporator is connected preheater 2 by surge tank 13 with cooling water conveying pump in fact all successively with the cooling water output 73 of forced-circulation evaporator.
Finally, as shown in Figure 1, the cooling water output 23 of above-mentioned preheater 2 and moisturizing entrance 1b are connected into the compressed steam pipeline after function of mechanical steam recompression machine 5 output by pipeline heater 12.
In fact, the power dissipation ratio that every platform Mechanical Vapor Compression 5 uses is larger, if material is not heated to bubble point temperature in preheater 2, finally can affect rear film of continuing rising heat and compressor to the total power consumption of the recompression process of steam, the total energy consumption of whole continuous crystallisation device can be increased, but in order to ensure good energy saving technology effect, depend merely on the preheater 2 sometimes pre-heating temperature elevation deficiency of cooling water as thermal source, therefore in order to control the temperature of charge of the present invention at preheater 2 output, the present invention has set up above-mentioned feeding temperature control loop herein, one ensures that the temperature of charge of preheater 2 output is able to constant.
As shown in Figure 1, the feeding temperature control loop of above-mentioned PLC automatic control system specifically comprises electric heater 11, first flow control valve 90 and the first temperature measuring unit 101; Wherein the first temperature measuring unit 101 is arranged on the material pipe between preheater 2 and climbing film evaporator 3, is namely arranged on preheater 2 output or its material pipe extension to climbing film evaporator 3 material input 30.Electric heater 11 is arranged on the material pipe between feed(raw material)inlet 1a and preheater 2, preferably after feeding engine 9.First flow control valve 90 is arranged on the material pipe between feeding engine 9 and preheater 2.First temperature measuring unit 101 signal connects PLC109, and the first temperature measuring unit 101 inputs PLC109 and is analyzed, and PLC109 output divides level signal to connect electric heater 11 and first flow control valve 90.Here, when system starts, general first flow control valve 90 standard-sized sheet, preferentially carrys out the temperature that FEEDBACK CONTROL first temperature measuring unit 101 detects reach setting value bubble point temperature by controlling electric heater 11.During system stalls, general first closedown function of mechanical steam recompression machine 5, now the heating efficiency of preheater 2 is corresponding weakens, and PLC109 controls mass flow by priority acccess control first flow control valve 90, thus ensure system stalls time last batch of crystalline quality.To this, PLC109 need only the priority of automatic spacing setting in advance.
In order to control crystalline quality well, ensureing the parameter stability of each heat exchange unit in whole system, controlling the temperature and pressure of compressed steam well, just must control function of mechanical steam recompression machine 5 power.Therefore, above-mentioned compressed steam control loop is introduced in PLC automatic control system, this control loop specifically comprises the second temperature measuring unit 102 and frequency converter 1021, after wherein the second temperature measuring unit 102 is installed on function of mechanical steam recompression machine 5, on the compressed steam pipeline before climbing film evaporator 3 thermal source input 32.Second temperature measuring unit 102 signal connects PLC109, and the temperature signal collected sends into PLC109, analyzes to make comparisons with optimized setting value; PLC109 connects function of mechanical steam recompression machine 5 by frequency converter 1021, is changed the size of function of mechanical steam recompression machine 5 input voltage or electric current by frequency converter 1021, to control the compression horsepower of function of mechanical steam recompression machine 5.
System of the present invention, except fully reclaiming the heat energy produced in evaporation and crystal process, also fully takes into account the present invention in system links likely loss water resource, and therefore, system of the present invention needs very long moisturizing or steam course in operation early stage.Consider in present invention process, need most and the direct steam of compressed steam pipeline is supplied, fill into automatic steam control loop to introducing between compressed steam pipeline in PLC automatic control system in the cooling water output reuse of preheater 2 in the present invention, it specifically comprises second control valve 1032, the 3rd temperature measuring unit 103, the 3rd flow control valve 1033 and the 4th temperature measuring unit 104; Wherein, second control valve 1032 is arranged on moisturizing entrance 1b output.3rd temperature measuring unit 103 is installed on the pipeline after pipeline heater 12, and be connected into the node of compressed steam pipeline at this pipeline before.After 3rd flow control valve 1033 is installed on the 3rd temperature measuring unit 103, before above-mentioned node.4th temperature measuring unit 104 is installed on the actual controller becoming two cover control loops of climbing film evaporator 3 material output 31, PLC109 here.On physical couplings, the 3rd temperature measuring unit 103, the 4th temperature measuring unit 104 points of level signals connect the input of PLC109.The output of PLC109 connects and control valve channel heater 12, second control valve 1032 and the 3rd flow control valve 1033 respectively.PLC109 needs according to the 3rd temperature measuring unit 103, guarantees that the water in pipeline is heated into steam, and inputs the heating power that PLC109 carrys out control valve channel heater 12.On tangible, only maximum heating power still can not meet temperature that the 3rd temperature measuring unit 103 surveys reach setting value time, PLC109 just enters second priority level to control second control valve 1032, reduces the water yield.And from the 4th temperature measuring unit 104 collection signal input PLC109, then control the 3rd flow control valve 1033 and carry out feedback regulation, be only a shared PLC between this loop and the above-mentioned another set of loop of this PLC109, there is no priority relationship.
Gas-liquid separator liquid level control loop, its object arranged is very direct, and exactly in order to control the proportion of forced circulation in gas-liquid separator, therefore, optimization is herein directly involved in the energy consumption of crystalline quality and whole system.Certainly, when forced circulation proportion is very big, the energy consumption of whole system is increase on foot, and crystalline rate is low, but crystalline quality can increase.And forced circulation proportion is when being less than a threshold value, crystalline rate remains on necessarily high constant level, but crystalline quality can reduce.Therefore the liquid level of gas-liquid separator will keep more accurate, a more constant parameter as well.Introduce gas-liquid separator liquid level control loop, it comprises:
-be arranged on liquid level gauge 101L on gas-liquid separator; With
-be arranged on gas-liquid separator second to export the 4th flow control valve 100 between 42 and forced-circulation evaporator material input 70;
Above-mentioned liquid level gauge 101L signal connects PLC109, PLC109 signal and to connect and the aperture controlling the 4th flow control valve the 100, four flow control valve 100 directly affects the entrance 40 of gas-liquid separator 4, thus affects its liquid level.
As fully visible, the present invention adopts a Mechanical Vapor Compression 5 pairs of climbing film evaporators 3 and forced-circulation evaporator 7 together steam heating, respectively climbing film evaporator 3 and forced-circulation evaporator 7 are distinguished to the equipment of heat supply than employing two Mechanical Vapor Compression 5, at least energy-conservation more than 20%.Why adopt a Mechanical Vapor Compression 5 just can realize above-mentioned heat supply, one of reason is also to combine and present invention employs and by the preheater 2 of heating material to bubble point temperature, thus can reduce the operating pressure of single Mechanical Vapor Compression 5.Consider that Mechanical Vapor Compression 5 is expensive, in the continuous evaporative crystallization equipment of existing employing mechanical vapor recompression technology, the price of Mechanical Vapor Compression 5 accounts for complete equipment price 30-50%, therefore taking cost into account, continuous evaporative crystallization device of the present invention has the two-fold advantage that cost is low and energy consumption is low concurrently.
In addition, invention introduces PLC automatic control system, namely excellent control system is established to whole MVR continuous evaporative crystallization system, there is control system, it is constantly got rid of, reduce interference to systematic parameter, optimize whole system parameter, improve the stability of whole system, and further reduce its energy consumption.
The above-mentioned Mechanical Vapor Compression 5 of the present embodiment is Roots Compressor, and above-mentioned climbing film evaporator 3 is pipe heat exchangers.
It should be noted that the present invention to the utilization of cooling water depending on steam loss situation, when complete equipment steam loss situation is comparatively large, the cooling water in the water of moisturizing entrance 1b and the cooling water output 23 of preheater 2 all accesses; When complete equipment steam loss situation is less, the cooling water in the cooling water output of preheater all accesses; When complete equipment steam loss situation is less, also likely part cooling water drainage is bled off, part access.
Following is the method adopting continuous evaporative crystallization system of the present invention to carry out continuous crystallisation, comprises the steps:
A. first, sent into by material feeding to be crystallized in preheater 2, the sensible heat passing through above-mentioned cooling water in preheater, as thermal source, by heating material to its bubble point temperature, but does not produce the hot solution of steam;
B. the hot solution in step a is sent in climbing film evaporator 3, superheated steam after climbing film evaporator 3 is compressed by Mechanical Vapor Compression 5 is as using, heat exchange is carried out to above-mentioned hot solution material, realize rising film heating, and producing a large amount of indirect steams, solution is brought into gas-liquid separator 7 by indirect steam together.
In this step, employing climbing film evaporator 3 is that the advantage of pipe heat exchanger is as follows: first, the expense of pipe heat exchanger unit volume is minimum in current evaporimeter, secondly, compared with other evaporimeters, pipe heat exchanger structure is more simple, and making and installation requires relatively low, finally, in the heat-transfer pipe of pipe heat exchanger, the flow velocity of indirect steam is quite fast, and between usual 20m/s-50m/s, the feed liquid time of staying is short, but total heat exchange system is still larger, generally can reach 1200 ~ 6009w/m
2h DEG C.
The indirect steam that wherein solution is brought into gas-liquid separator 4 process by indirect steam together sprays into speed between 25 ~ 50m/s, in order to prevent indirect steam short circuit, during work, the air filter formula screen pack installed in above-mentioned gas-liquid separator 4 forms one mist eliminating barrier, the liquid foam gear carried secretly by the indirect steam that material evaporation produces goes back, and only has indirect steam to pass through.
Consider that indirect steam sprays into speed between 25 ~ 50m/s, speed quickly, therefore we to have employed stratum reticulare high between 80-150mm, the silk screen of order number between 300-500 is as air filter formula screen pack, silk screen is to the mist of particle diameter >=3 ~ 5um, arresting efficiency reaches 97%-98.9%, and effect is very good.
C. be separated through gas-liquid separator 4, a concentrated solution part exports 42 by gas-liquid separator 4 second and again sends into forced-circulation evaporator 7 heating evaporation, and the gas-liquid mixture of generation returns to gas-liquid separator 4; Another part is from being expelled to crystal separator crystallization 6; In this step, indirect steam is sent gas-liquid separator and is compressed into superheated steam by function of mechanical steam recompression machine, then sends into climbing film evaporator 3 and forced-circulation evaporator 7 as heating energy source; Cooling water is sent into the part heating energy source of preheater 2 as pre-heater by the cooling water output of climbing film evaporator 3 and forced-circulation evaporator 7.Cooling water and the moisturizing entrance 1b of the cooling water output eliminating of preheater collect jointly, and are connected into the compressed steam pipeline after function of mechanical steam recompression machine 5 output by pipeline heater 12.By the multistage recycling of heat energy of this steam and water, adopt the continuous evaporative crystallization method of said system, not only continuous seepage is effective, and waste without raw material, water, cost is low, but also very energy-conservation.
D. in separator crystallization 6, crystallize out is discharged, and residue concentrated solution also delivers to heating evaporation in the forced-circulation evaporator 7 in step c.
Embodiment 2:
Embodiment 2 is with the difference of embodiment 1, and the Mechanical Vapor Compression 5 of the present embodiment is centrifugal compressor, and all the other repeat embodiment 1.
Energy-conservation Experimental comparison's example:
Select sodium carbonate to be material, sodium carbonate is joined respectively in the continuous evaporative crystallization device of embodiment 1 and 2, and adopt the method for embodiment 1 and 2 respectively.
The observable index evaporating the embodiment 1 and 2 of the required raw quantity of steam of 1 ton of steam multiple-effect evaporation and employing mvr technology comparatively, is shown in following form:
Table 1: embodiment 1 compares with multiple-effect evaporation
Table 2: embodiment 2 compares with multiple-effect evaporation
Note: be the standard coal of 0.404kg according to the heat of equal value of 1kWh electricity, the heat of equal value of 1kg saturated vapor is that the standard coal of 0.145kg calculates
Industrial commonly using is evaporated to economic benefits and social benefits, triple effect, four-effect evaporation; Substantially do not have after five effect evaporations.One be because multiple-effect evaporation effect number more costs of equipment are more for huge, two be five effects after not obvious in interpolation effect number effect.
Data from table 1 can show that embodiment 1 adopts MVR technology to have comparatively significantly energy-conservation relative to tradition evaporation.Wherein compared with double-effect evaporation on average energy-conservation 83%, compared with triple effect evaporation on average energy-conservation 76%, compared with four-effect evaporation on average energy-conservation 67%, compared with five effect evaporations on average energy-conservation 64%.
Data from table 2 can show that embodiment 2 adopts MVR technology to have comparatively significantly energy-conservation relative to tradition evaporation.Wherein compared with double-effect evaporation on average energy-conservation 87%, compared with triple effect evaporation on average energy-conservation 81%, compared with four-effect evaporation on average energy-conservation 75%, compared with five effect evaporations on average energy-conservation 72%.
Claims (6)
1. a continuous evaporative crystallization system, is characterized in that:
Described system comprises feed(raw material)inlet (1a), preheater (2), climbing film evaporator (3), gas-liquid separator (4), function of mechanical steam recompression machine (5), forced-circulation evaporator (7), crystal separator (6) and a PLC automatic control system;
Described preheater (2), climbing film evaporator (3) and forced-circulation evaporator (7) are all heat exchange units; Its include be connected material input (20,30,70), material output (21,31,71) and the thermal source input (22,32,72) be connected, cooling water output (23,33,73);
Described gas-liquid separator (4) comprise entrance (40) for sending into gas-liquid mixed material, for export steam the first outlet (41), for feed liquid forced circulation the second outlet (42) and send the 3rd outlet (43) of crystallization for feed liquid;
Described feed(raw material)inlet (1a) connects the material input (20) of preheater (2) by pipeline, the material output (21) of preheater (2) connects the material input (30) of climbing film evaporator (3) by pipeline, the material output (31) of climbing film evaporator (3) connects the entrance (40) of gas-liquid separator;
Described function of mechanical steam recompression machine (5) is connected between the first outlet (41) of gas-liquid separator (4) and the thermal source input (32) of climbing film evaporator by steam conveying pipe, vapour pressure in order to be exported by described gas-liquid separator shortens superheated steam into and sends into climbing film evaporator, rises film heat to realize material;
The material input (70) of described forced-circulation evaporator (7) connects the second outlet (42) of gas-liquid separator, and the material output (71) of forced-circulation evaporator (7) is linked back the entrance (40) of gas-liquid separator; The direct compressed steam output connecting function of mechanical steam recompression machine (5) and compress of the thermal source input (72) of forced-circulation evaporator (7);
The cooling water output (33,73) of described climbing film evaporator (3) and forced-circulation evaporator (7) is connected by pipeline and cooling water is sent into the thermal source input (22) of preheater (2), in order to the material supplementary heating flowed through in preheater (2);
Described crystal separator (6) connects the 3rd outlet (43) on described gas-liquid separator (4);
It is following three control loops of controller that described PLC automatic control system at least comprises with PLC:
I feeding temperature control loop comprises:
-be positioned at electric heater (11) between feed(raw material)inlet (1a) and preheater (2);
-be positioned at first flow control valve (90) between feed(raw material)inlet (1a) and electric heater (11); With
-be positioned at the first temperature measuring unit (101) between preheater (2) and climbing film evaporator (3);
Described first temperature measuring unit (101) signal connects PLC (109), and PLC (109) output divides level signal to connect electric heater (11) and first flow control valve (90);
Ii compressed steam control loop comprises:
-be positioned at function of mechanical steam recompression machine (5) after, the second temperature measuring unit (102) before climbing film evaporator (3) thermal source input (32); And
-frequency converter (1021)
Described second temperature measuring unit (102) signal connects PLC (109); PLC (109) connects function of mechanical steam recompression machine (5), to control the compression horsepower of function of mechanical steam recompression machine (5) by frequency converter (1021);
Iii gas-liquid separator liquid level control loop comprises:
-be arranged on liquid level gauge (101L) on gas-liquid separator; With
-be arranged on gas-liquid separator second to export the 4th flow control valve (100) between (42) and forced-circulation evaporator material input (70);
Described liquid level gauge (101L) signal connects PLC (109), and PLC (109) signal connects and controls the 4th flow control valve (100).
2. a kind of continuous evaporative crystallization system according to claim 1, is characterized in that:
Described system also comprises moisturizing entrance (1b) and pipeline heater (12);
The cooling water output (23) of described preheater (2) and moisturizing entrance (1b) converge merga pass pipeline heater (12) and are connected into compressed steam pipeline after function of mechanical steam recompression machine (5) output;
Described PLC automatic control system also comprises the 4th following control loop:
Iiii fills into automatic steam control loop and comprises:
-be arranged on the second control valve (1032) of moisturizing entrance (1b) output;
-be installed on pipeline heater (12) after, the 3rd temperature measuring unit (103) before being connected into compressed steam pipeline;
-be installed on the 3rd temperature measuring unit (103) after, the 3rd flow control valve (1033) before being connected into compressed steam pipeline; And
-be installed on the 4th temperature measuring unit (104) of climbing film evaporator (3) material output (31);
Described 3rd temperature measuring unit (103), the 4th temperature measuring unit (104) point level signal connects the input of PLC (109); The output of described PLC (109) connects and control valve channel heater (12), second control valve (1032) and the 3rd flow control valve (1033) respectively.
3. a kind of continuous evaporative crystallization system according to claim 1 and 2, is characterized in that:
Described crystal separator (6) comprises the entrance (60) of the 3rd outlet (43) connected on described gas-liquid separator (4), crystallize out delivery outlet (61) and feed liquid delivery outlet (62), and described feed liquid delivery outlet (62) is connected into the material input (70) of described forced-circulation evaporator (7).
4. a kind of continuous evaporative crystallization system according to claim 1 and 2, is characterized in that:
Also comprise surge tank (13) and cooling water conveying pump; Surge tank (13) and cooling water conveying pump are located on the pipeline before the thermal source input (22) of preheater (2) successively; Described climbing film evaporator (3) is connected preheater (2) by surge tank (13) with cooling water conveying pump all successively with the cooling water output (33,73) of forced-circulation evaporator (7).
5. a kind of continuous evaporative crystallization system according to claim 1 and 2, is characterized in that:
Pipeline between second outlet (42) of described gas-liquid separator and the material input (70) of forced-circulation evaporator (7) is provided with forced circulation pump (10).
6. a kind of continuous evaporative crystallization system according to claim 3, is characterized in that:
Pipeline between second outlet (42) of described gas-liquid separator and the material input (70) of forced-circulation evaporator (7) is provided with forced circulation pump (10), and the feed liquid delivery outlet (62) of described crystal separator (6) is connected into the material input (70) of forced-circulation evaporator (7) by forced circulation pump (10); Described 4th flow control valve (100) is positioned between forced circulation pump (10) and forced-circulation evaporator material input (70).
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| CN107485878A (en) * | 2017-10-17 | 2017-12-19 | 济南大学 | A kind of optimal control method for improving vacuum salt production evaporation efficiency |
| CN111569462A (en) * | 2020-07-06 | 2020-08-25 | 上海济俭工业设备有限公司 | Continuous evaporation concentration crystallization device |
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| CN111569462A (en) * | 2020-07-06 | 2020-08-25 | 上海济俭工业设备有限公司 | Continuous evaporation concentration crystallization device |
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