Summary of the invention
The object of the present invention is to provide the epoxy propane waste water treatment process that a kind of technology is simple, cost is low, can reclaim the calcium chloride in the waste water.
Another object of the present invention is to provide a kind of multi-effect evaporating device, can the calcium chloride in the waste water be reclaimed.
A kind of production of propylene oxide method of wastewater treatment may further comprise the steps:
(1) at first, waste water is carried out multiple-effect evaporation handle, thereby obtain the waste water concentrated solution;
(2) then, the waste water concentrated solution is carried out crystallization, obtain the calcium chloride crystal.
In a preferred embodiment of the present invention, described method of wastewater treatment further comprises step (3), is about to the calcium chloride crystal and separates from the waste water concentrated solution; Step (4), i.e. waste steam is reclaimed in condensation.Wherein, can adopt in the described step (3) that any one is separated the calcium chloride crystal in centrifugal separation, falling temperature method or the flash method from the waste water concentrated solution.
Described method of wastewater treatment can comprise also before in step (1) waste water is carried out pretreated step that described pretreated step comprises regulates the temperature of waste water and pH value.In another embodiment of the present invention, the temperature of waste water is adjusted to 75 ℃-85 ℃ in the described pre-treatment step, and the pH value is adjusted to 6.0-7.0.
Described multiple-effect evaporation is handled and can be carried out in the multi-effect evaporating device of 2 to 5 effects.In one embodiment of the invention, described multi-effect evaporating device is that cross-current type five is imitated evaporation unit.
The present invention also provides a kind of multi-effect evaporating device that is used for the production of propylene oxide method of wastewater treatment, described multi-effect evaporating device comprises several effects, crystallizer, preheater, phlegma basin, condenser, cooling basin, moisture separator, water ring vacuum pump and a series of pipeline, between each is imitated, be connected by pipeline between effect and the crystallizer, crystallizer and centrifuge separator are positioned at after each effect successively, and the phlegma basin is positioned at after last effect.Wherein, described effect further comprises heating unit and separator, and heating unit is connected by pipeline with separator.
Production of propylene oxide method of wastewater treatment of the present invention, adopt multiple-effect evaporation, for example five imitate evaporation, the first, the 4th, the 5th imitate,, adopt falling film evaporator because feed concentration is lower, second imitates the outer heating of employing natural-circulation evaporator, because the triple effect feed concentration is higher, adopt outer heating forced circulation evaporation crystallizer, prevent the formation of dirt.Like this, improved heat transfer efficiency, velocity of evaporation is fast, and heated time is short, and vaporization temperature is low, is difficult for coking, is convenient to clean.Multiple-effect evaporation step process epoxy propane waste water not only can be with wastewater treatment, and has reclaimed calcium chloride a large amount of in the waste water by condensing crystal, has reduced the toxicity of waste water, has reclaimed useful industrial chemicals again, kills two birds with one stone.Recycling economy thinking in line with refuse reclamation, calcium chloride is considered as valuable source to be recycled, not only successful solution puzzlement always produce the waste water control problem of propylene oxide enterprise, simultaneously also for enterprise creates the profit growth point that makes new advances, one action doulbe-sides' victory.
Embodiment
A kind of production of propylene oxide method of wastewater treatment of the present invention, this method may further comprise the steps:
(1) at first, waste water is carried out multiple-effect evaporation handle, thereby obtain the waste water concentrated solution;
(2) then, the waste water concentrated solution is carried out crystallization, obtain the calcium chloride crystal.
In the present invention, the multi-effect evaporating device that aforesaid method adopts carries out wastewater treatment, below simply introduces this multi-effect evaporating device.
With reference to shown in Figure 1, in one embodiment of the invention, described multi-effect evaporating device can be quintuple effect evaporator, and described quintuple effect evaporator mainly comprises five effects, a crystallizer 9 and a series of pipeline.
Wherein, imitate the district that is meant the multi-effect evaporating device that heats by steam (being generally water vapor), and also steam is discharged in the district subsequently, be used for the vaporization heat that supply section needs in this district, promptly imitating residual liquid (bottom) product that comes from one is next (denseer) liquid starting material of imitating.Each effect comprises vapour outlet and liquid exit, and the equipment that the evaporation heating is provided.Wherein, the heat supply of heating installation is to be provided by the steam from last effect, and imitate for first of multi-effect evaporating device, its heat supply generally both can be provided by fresh water steam, also can provide the logistics of proper temperature heat to provide by another kind.This heating installation can reboiler arranged in form in liquid (i.e. bottom) part of this effect, heating installation can also be the form of the heating surface of similar pipe or plate.
In the present embodiment, each effect comprises vaporizer and separator, vaporizer and separator are interconnected, vaporizer can be by vaporizer transport gas or the liquid stream of pipeline to separator or another effect, separator also can be by pipeline to next vaporizer or separator transport gas or liquid stream, make logistics in the vaporizer of a plurality of effects and separator, circulate, constantly reduce boiling temperature.Wherein, vaporizer can be pump feed evaporator, short tube vertical evaporator, long tube vertical evaporator, horizontal tube evaporator and sweeps and chooses any one kind of them in wall film (wipedfilm) vaporizer or multiple.
Crystallizer 9 can carry out crystallization treatment to the logistics concentrated solution, and the material that zero pour is lower is separated from concentrated solution.In the present embodiment, described crystallizer 9 communicates with triple effect, and triple effect is handled the logistics that obtains and entered crystallizer generation concentrated solution, obtains crystal at last.
Multi-effect evaporating device of the present invention further comprises preheater, phlegma basin 15, condenser 16, cooling basin 17, moisture separator 18 and water ring vacuum pump 19.Wherein, preheater is used for thermal pretreatment is carried out in logistics, adjusts the temperature before logistics enters effect.In the present embodiment, three preheaters are preheater 1, preheater 22 and preheater 3 20.Phlegma basin 15 and condenser 16 all communicate in last effect, and phlegma basin 15 is used to collect last and imitates the part steam of discharging.Condenser 16 carries out condensation to the steam of the discharge of last effect, generates water of condensation, and by cooling basin 17 with its recovery.Moisture separator 18 and water ring vacuum pump 19 are communicated with condenser 16, discharge after moisture separator 18 and water ring vacuum pump 19 processing from the steam that condenser 16 is discharged.
Below method of wastewater treatment of the present invention is further specified.
In the step of above-mentioned wastewater treatment, more preferably, carry out pretreated step at the preceding waste water that increases propylene oxide of step (1), be mainly used in the temperature and the pH value of regulating waste water.In the present embodiment, described pre-treatment can be carried out like this: at first, through screen filtration, the aperture of screen cloth is about 60 orders, removes the bigger impurity of particle in the waste water with waste water; Then, the temperature of regulating waste water is 75 ℃-85 ℃, and waste water is added acid system automatically through ORP, and adding hydrochloric acid accent waste water ph is 6.0-7.0, thereby make lime carbonate and high boiling insoluble organism produce precipitation, by sludge drainage system the organism precipitation is removed again; At last, will place the regulating tank of insulation to store through pretreated waste water, and regulate water quality.
In the step (1), multiple-effect evaporation is handled and is made the logistics of wanting processed carry out a series of evaporation process in the mode that reduces pressure gradually in imitating one by one, owing to the pressure gradient that exists between imitating one by one, boiling temperature in causing imitating continuously reduces gradually, the condensed steam of coming out through an effect can be used as next heating medium of imitating, and the vaporization heat that provides next liquid material of imitating to handle, reach the purpose of separating the different material of boiling point gradually.
In conjunction with reference to figure 1 and Fig. 2, in one embodiment of the invention, adopt quintuple effect evaporator that waste water is carried out the cross-current type evaporation process.To send in the quintuple effect evaporator through pretreated waste water by fresh feed pump P01, and adopt the mode of forward feeding to operate.The waste water feed liquid is imported preheater 1, heat through the water of condensation of second single-effect evaporator 5 and third effect evaporator generation, temperature is elevated to 100-110 ℃ by 80 ℃; Import preheater 22 then, the water of condensation that produces through first single-effect evaporator 3 heats, temperature is elevated to 130-140 ℃ by 100-110 ℃, enter an effect then, after an effect is handled, be divided into two-way after promptly the first effect separator 4 is discharged, one the tunnel enters quadruple effect, five effects, preheater 3 20 successively, another road generates concentrated solution through two effects, triple effect, crystallizer 9, centrifuge separator 10 in crystallizer 9, by centrifuge separator 10 the crystallized product calcium chloride crystal separation that generates is come out again.Wherein, one tunnel feed liquid enters the steam that quadruple effect produces and enters five effects; After heating through preheater 3 20, five steam of imitating generation enter two effects; Two imitate the steam that evaporate generation enters triple effect, and two product liquids of imitating generation are imitated separator 6 discharges through second, get back to second single-effect evaporator 5 and follow back heating, enter quadruple effect, five effects more in regular turn.Another road feed liquid, five effect generation water of condensation are imitated the feed liquid of coming out with one and are followed back heating through two effects, triple effect, the steam that triple effect produces enters quadruple effect, water of condensation enters crystallizer and centrifuge separator concentrates condensation, the steam that quadruple effect produces enters five effects, enters condenser 16 condensations by five steam of imitating the evaporation generation at last, and condensed water of condensation enters cooling basin 17 again, carry out gas-liquid separation and part steam enters moisture separator 18, enter water ring vacuum pump 19 at last; The phlegma that reaches certain temperature directly enters phlegma basin 15.The flow direction of further setting forth feed liquid of the present invention below in conjunction with accompanying drawing is specific as follows.
In conjunction with reference to figure 1 and Fig. 2, wherein, when described production of propylene oxide waste water feed liquid enters first effect, it enters first single-effect evaporator 3 through the preheater one 1 heating backs mode parallel with giving birth to vapour stream, one secondary steam of imitating the evaporation generation enters first and imitates separator 4, and a partial condensation water of imitating generation is heated as 22 pairs of feed liquids of thermal source importing preheater, partial condensation water flows back to the feed liquid pond by first single-effect evaporator 3, secondary steam is imitated separator 4 through first and is carried out gas-liquid separation, wherein, secondary steam enters second single-effect evaporator 5 as thermal source, and water of condensation enters quadruple effect.Two imitate steam enters the second effect separator 6 through second single-effect evaporator, 5 heating generation triple effect steam, and the two partial condensation water of imitating generation are heated as one 1 pairs of feed liquids of thermal source importing preheater, partial condensation water flows back to the feed liquid pond by second single-effect evaporator 5, three steam are imitated separator 6 through second and are carried out gas-liquid separation, wherein, triple effect steam and water of condensation all enter third effect evaporator 1 and third effect evaporator 28 as thermal source.Triple effect steam generates quadruple effect steam and enters crystallizer 9 after third effect evaporator 1 and third effect evaporator 28 heating, third effect evaporator 1 is interconnected with third effect evaporator 28, the partial condensation water that generates through third effect evaporator 28 enters third effect evaporator 1 as thermal source, and the partial condensation water that triple-effect evaporator produces is heated as one 1 pairs of feed liquids of thermal source importing preheater, and quadruple effect steam enters and generates concentrated solutions in the crystallizer 9.The water of condensation of the first effect separator 4 and the quadruple effect steam that crystallizer 9 comes out enter quadruple effect respectively as thermal source, the five effect vapor portions that generate through fourth evaporator 11 directly enter phlegma basin 15, part enters quadruple effect separator 12 and carries out gas-liquid separation, and the partial condensation water that quadruple effect generates imports five effects as thermal source, and partial condensation water flows back to the feed liquid pond by fourth evaporator 11.Five water of condensation of imitating steam and quadruple effect separator 12 import five and imitate, the six effect vapor portions that generate through quintuple effect evaporator 13 enter phlegma basin 15, part enters the 5th effect separator 14 and carries out gas-liquid separation, then, imitate six of separator 14 through the 5th and imitate steam importing condenser 16, obtain water of condensation and flow back to cooling basin 17, imitating steam without refrigerative six can discharge after moisture separator 18 and water ring vacuum pump 19 processing, and enter two effects once more through the 5th phlegma of imitating after separator 14 is handled, repeat above-mentioned flow process.The repeatedly cross-flow of waste water feed liquid can obtain water of condensation at phlegma basin and cooling basin behind the multiple-effect evaporation, can directly carry out a biological disposal upon to water of condensation.
In step (2), the concentration of calcium chloride in the waste water feed liquid is concentrated to about 80~90% after, concentrated solution carries out crystallization in crystallizer 9, generate the calcium chloride crystal.
Method of wastewater treatment further comprises step (3), promptly the calcium chloride crystal is carried out centrifugation, and calcium chloride crystal separation and Extraction from waste water is come out; Step (4), i.e. waste steam is reclaimed in condensation.In the present invention, can adopt in centrifugal separation, falling temperature method or the flash method any one method that the calcium chloride crystal is separated from concentrated solution in the described step (3), wherein, comparatively preferred separation method is a centrifugal separation, by separating centrifuge the calcium chloride crystal is separated then, granular calcium chloride is delivered to the rewinding automatic packaging system and is packed outward transport, and the calcium chloride saturated solution returns crystallizer 9 and carries out recrystallization.Simultaneously, waste liquid is imitated the cross-current type processing through five, and condensation is reclaimed and obtained the waste water steam.
This step adopts five to imitate evaporation, and the first, the 4th, the 5th imitates, because feed concentration is lower, adopt falling film evaporator, second imitates the outer heating of employing natural-circulation evaporator, because the triple effect feed concentration is higher, adopt outer heating forced circulation evaporation crystallizer, prevent the formation of dirt.Like this, improved heat transfer efficiency, velocity of evaporation is fast, and heated time is short, and vaporization temperature is low, is difficult for coking, is convenient to clean.
In the present invention, described waste water is produced the process of propylene oxide from chlorohydrination.Described multiple-effect evaporation is handled and is not limited to the cross-current type quintuple effect evaporator, and it also can carry out in other multi-effect evaporating devices of 2 to 5 effects.Through evidence, the COD of the water of condensation after cross-current type quintuple effect evaporator of the present invention is handled satisfies the wastewater treatment requirement less than 100mg/l, and wherein, described chemical oxygen demand (COD) (COD) is the amount of oxygen that all an oxidisable substances need in the oxidation sample.
Above disclosed only is preferred embodiment of the present invention, can not limit the present invention's interest field certainly with this, and therefore the equivalent variations of being done according to the present patent application claim still belongs to the scope that the present invention is contained.