CN1805904B

CN1805904B - Alkylene oxide factory effluent processing method and its multi-effect evaporation apparatus

Info

Publication number: CN1805904B
Application number: CN200580000452.9A
Authority: CN
Inventors: 刘德沛
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-02-03
Filing date: 2005-09-08
Publication date: 2011-01-12
Anticipated expiration: 2025-09-08
Also published as: CN1805904A

Abstract

The present invention relates to a treatment method of industrial waste water for producing alkylene oxides and a multi-effect evaporation equipment. The method comprises the following steps: firstly, treating the waste water by multi-effect evaporation treatment and resulting in the waste water solution with different concentration of calcium chloride. Secondly, said waste solution is evaporatedand condensed to result in the calcium chloride concentrated solution. The concentrated solution is subjected to crystalizing and being dried to result in the calcium chloride solid, and then the waste vapor is condensed and reclaimed. The multi-effect evaporation equipment comprises some sections, concentration part and solid separation equipment. The sections and between the sections, the concentration part and the solid separation equipment are connected with pipes each other. The method and the equipment of the invention are simple, economic and high efficiency.

Description

Alkylene oxides production wastewater treatment method and multi-effect evaporating device thereof

Technical field

The present invention relates to a kind of processing method of industrial waste water and device, refer in particular to the wastewater treatment method that produces in the alkylene oxides production process and the device of use thereof.

Background technology

The present invention is that alleged alkylene oxides mainly comprises propylene oxide, epoxy chloropropane, epoxy hexane, epoxy cyclohexane and oxyethane etc.Be example explanation background technology below with the propylene oxide.

Along with the development of China's fine chemistry industry and polyurethane industrial, product propylene is in the passage of a rising.Because chlorohydrination is produced the alkylene oxides less investment, technology is simple, widespread use at home, but at present the propylene chlorohydrination production technique that adopts of China's production of propylene oxide device produce contain calcium chloride waste water serious environment pollution.

Why domestic propylene oxide by chlorohydrination throughput does not have bigger breakthrough, and key is that waste water, waste residue that its technology produces are difficult for handling the requirement that incompatibility environmental protection aspect is more and more stricter.

The waste water that produces in the propylene oxide by chlorohydrination technology, extremely difficult because of the characteristics with high temperature, high alkalinity, high chemical oxygen demand, the content of the calcium chloride of this waste water reaches 40～60g/L, causes the bacterial classification of biochemical treatment to be difficult to survival.At present domestic how tame production of propylene oxide producer all build the riverine and coastal place in, and it is discharged a large amount of above-mentioned waste water and generally adopts fresh water to dilute, reach the demand of biochemical treatment after, carry out biochemical treatment again.

But the working cost that the method that biochemical treatment is carried out in above-mentioned dilution earlier again need drop into is minimum to be that several units are to dozens of yuan/ton waste water, cost of investment is bigger, and domestic epoxy propane waste water base conditioning is defective, causes the technology of chlorohydrination production propylene oxide on the verge of being replaced; In addition, this treatment process level of automation is low, as adopts full-automatic control, and not only investment is big, and the primary instrument quality neither reach a standard very much, causes automatization to be difficult to realize; Moreover the treating water of this method generally all can't reuse.

Therefore, above-mentioned treatment process has greatly increased production cost, and enterprise generally is difficult to bear.Simultaneously the contradiction in the wastewater treatment causes in the waste water chemical oxygen demand high, thereby increased the weight of sewage pressure, caused the surrounding environment severe contamination, therefore, in the propylene oxide production process, particularly the improvement of the trade effluent of chlorohydrination technology generation is the bottleneck of enterprise development always.

For reducing or eradicate the pollution of production of propylene oxide waste water, waste residue, developed comparatively sophisticated light pollution production of propylene oxide technology in the world, this technology mostly is the indirect oxidation method, i.e. propylene oxide/ethylbenzene method (PO/SM) and propylene oxide/Trimethylmethane method (PO/MTBE).But, indirect oxidation method PO/SM, PO/MTBE route, its shortcoming is the investment cost height, and the market equilibrium of its byproduct directly influences the ordinary production of propylene oxide.And chlorohydrination is produced that the technology of propylene oxide is low with its cost, Processes and apparatus simply in the industry cycle, particularly China is a large amount of uses.Therefore it is extremely urgent to solve the waste water handling problem that produces in the chlorohydrination technology.

In addition, though calcium chloride is " poison " thing in waste water, calcium chloride itself is the important chemical product simultaneously, can be widely used in industry, agricultural, mining, oil drilling, environment protection, food, medicine and other fields.Traditional method of wastewater treatment has been wasted a large amount of calcium chloride.

Therefore, provide in a kind of alkylene oxides production process, particularly method of wastewater treatment and the device thereof that produces in the chlorohydrination technology is very necessary with shortcoming, the redemption propylene oxide by chlorohydrination technology that overcomes prior art.

Summary of the invention

The technical problem to be solved in the present invention is: provide that a kind of technology is simple, cost is low, alkylene oxides production wastewater treatment method efficiently.

Another technical problem that the present invention will solve is: a kind of handle waste water that produces in the alkylene oxides production technique and the multi-effect evaporating device that can recycle waste water are provided.

For solving the problems of the technologies described above, technical scheme of the present invention is: a kind of alkylene oxides production wastewater treatment method, comprise step (1), and waste water is carried out the multiple-effect evaporation processing, thereby obtain containing the solution of different concns calcium chloride in each effect.

This method also comprises step (2), to the solution further evaporation concentration of step (1) after multiple-effect evaporation is handled, obtains the calcium chloride concentrated solution.

Described method of wastewater treatment further comprises step (3), and the calcium chloride concentrated solution of step (2) is carried out crystallization or drying treatment, the calcium chloride solid.

Described method of wastewater treatment further comprises step (4) condensation recovery waste steam.

Also comprise before in step (1) waste water is carried out pretreated step: the temperature of regulating waste water is 75 ℃-85 ℃, it is 6.0-8.0 that waste water is added acid accent waste water ph, thereby make lime carbonate and high boiling insoluble organism produce precipitation, to precipitate removal, will place the regulating tank of insulation to store through pretreated waste water at last.

It can be cross-flow or adverse current that the multiple-effect evaporation of described step (1) is handled, and each of described multiple-effect device imitated and comprised heating and evaporating unit and tripping device, is interconnected between this heating and evaporating unit and the tripping device or is connected with pipeline; Described step (2) is to heat outside that evaporation forms concentrated solution in the pump feed evaporator of forced circulation evaporation crystallizer or heat-conducting oil heating, and described step (3) is to carry out crystallization in crystal separator or flaker, and is dry in baker or drying tower.

The multi-effect evaporating device of described step (1) is five effect evaporation units, when taking cross-flow, the waste water feed liquid is imitated heating evaporation through first, fourth, five successively and is entered second effect, triple effect evaporation again, and step (2) is further to evaporate to form concentrated solution in the crystallizer of triple effect; Step (3) be with crystal separator that described crystallizer and triple effect are communicated with in carry out crystallization and separate; When taking adverse current, the waste water feed liquid is imitated heating evaporation through the 5th, four, three, two, one successively in the step (1), step (2) is that the further evaporation concentration of pump feed evaporator that will import described heat-conducting oil heating through the five waste water feed liquids of imitating processing forms the calcium chloride concentrated solution, and step (3) is concentrated solution to be imported described flaker carry out crystallization and separation; Step (4) all is to utilize condenser, phlegma basin or cooling basin, moisture separator and water ring vacuum pump to carry out condensation to reclaim waste steam.

Another technical scheme of the present invention is: a kind of multi-effect evaporating device that is used for alkylene oxides production wastewater treatment method, mainly comprise several effects, upgrading unit and solid separating device, between each is imitated, be connected by pipeline between effect and upgrading unit and the solid separating device.

Each of described multiple-effect device imitated and to be comprised heating and evaporating unit and tripping device, is interconnected between this heating and evaporating unit and the tripping device or is connected with pipeline; Described upgrading unit is the pump feed evaporator of outer heating forced circulation evaporation crystallizer or heat-conducting oil heating; Described solid separating device is meant crystal separator, flaker or drying plant.

Described multi-effect evaporating device comprises 5 effects, applicable cross-flow or counter-current treatment technology, when taking cross-flow, the first, the 4th, the 5th imitate, adopt falling film evaporator, first imitates to give birth to steam heating, and second imitates the outer heating of employing natural-circulation evaporator, and triple effect adopts outer pump feed evaporator and the described outer heating forced circulation evaporation crystallizer of heating; When taking adverse current, multi-effect evaporating device also comprises the pump feed evaporator of described heat-conducting oil heating, and first imitates the employing pump feed evaporator, and all the other quadruple effects adopt falling-film evaporators, and first imitates to give birth to steam as heating source.

Described multi-effect evaporating device further comprises condenser, cooling basin, moisture separator and water ring vacuum pump; Condenser is imitated the steam of discharging to last and is carried out condensation, generate water of condensation, and by the cooling basin it is reclaimed, moisture separator and water ring vacuum pump are communicated with condenser, and the steam of discharging from condenser directly discharges or sends into the cooling basin after moisture separator and water ring vacuum pump are handled; Described multi-effect evaporating device comprises further that also being used for that thermal pretreatment is carried out in logistics enters the preheater of imitating preceding temperature to adjust logistics, and is used to collect the phlegma basin that each imitates the water of condensation of discharging.

The invention has the beneficial effects as follows: alkylene oxides production wastewater treatment method of the present invention, waste water is carried out multiple-effect evaporation to be handled, thereby obtain containing the different concns calcium chloride solution in each effect, technology is simple, cost is lower, not only wastewater treatment can be reduced the toxicity of waste water, reach emission standard, and the calcium chloride solution of the different concns of gained can directly be packaged into product and sells or use.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 the enterprise of alkylene oxides product, simultaneously also for enterprise creates the profit growth point that makes new advances, one action doulbe-sides' victory.Particularly solve effective handling problem of the waste water that produces in the chlorohydrination production propylene oxide process, the technology that makes chlorohydrination produce propylene oxide is preserved and expanded the scale of production becomes possibility.

And after step (2) and step (3) processing, can obtain greater concn calcium chloride solution or its solid form product, be beneficial to industrial various application need.

The present invention is used for the multi-effect evaporating device of alkylene oxides production wastewater treatment method, and its apparatus structure is simple, not only can be used to handle the alkylene oxides factory effluent effectively, also can reclaim calcium chloride effectively.This device technique mature and reliable, can realize full-automatic control,, can recoup the investment in general one to three year though its equipment one-time investment cost is higher.As calculated, the present invention handles the method for waste water, but about 20 yuans of waste water extra earning per ton (profit that does not contain the water of condensation reuse water).

Description of drawings

Fig. 1 is the synoptic diagram of an embodiment of multi-effect evaporating device of the present invention.

Fig. 2 is the wastewater treatment process figure of Fig. 1 multi-effect evaporating device correspondence.

Fig. 3 is another embodiment synoptic diagram of multi-effect evaporating device of the present invention.

Fig. 4 is the partial enlarged drawing of Fig. 3 III-III left-half along the line.

Fig. 5 is the partial enlarged drawing of Fig. 3 III-III right half part along the line.

Fig. 6 is the wastewater treatment process figure of Fig. 3 multi-effect evaporating device correspondence.

Embodiment

The invention provides a kind of alkylene oxides production wastewater treatment method, this method may further comprise the steps:

(1) at first, the waste water feed liquid is carried out the multiple-effect evaporation processing, thereby obtain the calcium chloride solution of different concns;

(2) then, the waste water solution of step (1) after multiple-effect evaporation is handled proceeded evaporation concentration, get the calcium chloride concentrated solution of high density as 70% above concentration;

(3) concentrated solution with step (2) carries out crystallization or drying treatment and separation, obtains the calcium chloride solid, as calcium chloride powder or Calcium dichloride dihydrate; Wherein the separation method of calcium chloride can be in centrifugal separation or falling temperature method or flash method or the direct drying method and chooses any one kind of them, and used solid separating device can be crystal separator or flaker, and drying plant can be baker or drying tower;

(4) waste steam is reclaimed in condensation.

In the present invention, described alkylene oxides factory effluent for example can be production of propylene oxide waste water, epoxy chloropropane production, epoxy hexane, epoxy cyclohexane factory effluent and ethylene oxide production waste water, and particularly chlorohydrination is produced the waste water that produces in propylene oxide, the epoxy chloropropane technology.

The processing of alkylene oxides factory effluent of the present invention is to carry out in multi-effect evaporating device, 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 (giving birth to 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 abovementioned steps (1) to waste water carry out multiple-effect evaporation handle can adopt adverse current or cross-flow (described adverse current and cross-flow be at the waste water feed liquid between each is imitated flow direction and define) mode, following example one is that cross-flow treatment unit and technology are specifically described, and example two is that counter-current treatment device and technology are specifically described.

Example one

Please specifically see figures.1.and.2.In the present embodiment, each effect comprises at least one 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 (wiped film) vaporizer or multiple.

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 pipelines of imitating and being connected each effect.Triple effect comprises two heating fumigators 8,9, heats forced circulation evaporation crystallizer 10 outward, crystal separator 11, two heating fumigators 8,9 are interconnected, and crystallizer 10 is communicated with two heating fumigators, and crystal separation 11 devices are connected with crystallizer 10.In the present embodiment, the logistics after triple-effect evaporator 8,9 is handled enters crystallizer 10 further heating evaporations and concentrates the generation concentrated solution, obtains crystal at last in crystal separator 11.Crystal separator 11 is used to separate the calcium chloride solid.

Multi-effect evaporating device of the present invention further comprises

preheater

3,2,21, phlegma basin 16, direct condenser 17, cooling basin 18, moisture separator 19 (water ring vacuum pump 20 carries) and water ring vacuum pump 20.Wherein, preheater is used for thermal pretreatment is carried out in logistics, adjusts the temperature before logistics enters effect.Phlegma basin 16 and direct condenser 17 all communicate with last effect, and phlegma basin 16 is used to collect last and imitates the part steam of discharging.Direct condenser 17 carries out condensation to last steam of imitate discharging, and generates water of condensation, and by cooling basin 18 with its recovery.Moisture separator 19 and water ring vacuum pump 20 are communicated with direct condenser 17, discharge after moisture separator 19 and water ring vacuum pump 20 processing from the steam that direct condenser 17 is discharged.

Below method of wastewater treatment of the present invention is further specified.

In the step of above-mentioned wastewater treatment, more preferably, at the preceding waste water that produces during alkylene oxides produced that increases of step (1), for example the waste water that produces in the propylene oxide by chlorohydrination production technique carries out pretreated step, is 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 makes lime carbonate and high boiling insoluble organism produce precipitation, will precipitate removal by sludge drainage system 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 have pressure gradient 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, adopt quintuple effect evaporator that waste water is carried out the cross-current type evaporation process in this example.To send in the quintuple effect evaporator through pretreated waste water feed liquid by fresh feed pump P01.At first waste water feed liquid (starting point concentration of calcium chloride is about 5%) is imported preheater 3, heat through the partial condensation water of second single-effect evaporator 6 and third effect evaporator 8,9 generations, temperature is elevated to 100-110 ℃ by 80 ℃; Import preheater 2 then, the water of condensation that produces through first single-effect evaporator 4 heats, temperature is elevated to 130-140 ℃ by 100-110 ℃, enter an effect, quadruple effect then successively, five imitate, preheater 21 (water of condensation that produces through two effects, triple effect heats), two effects, triple effect, the waste water feed liquid generates concentrated solution at last in triple effect crystallizer 10.

Steam is then imitated via first successively, enters second effect, triple effect, quadruple effect, five effects, carries out condensation process at last.Specifically, directly be delivered to second vaporizer 6 of imitating as thermal source by the steam that produces in first separator 5 of imitating, and the like, second steam of imitating separator 7 generations directly is delivered to the vaporizer 8,9 of triple effect as thermal source.

And the water of condensation part that each single-effect evaporator produces is sent into the feed liquid pond, sends into phlegma basin 16 behind the thermal source of a part as preheater 3,21.And first vaporizer of imitating 4 utilizes and gives birth to steam as heating source, and is pollution-free, its water of condensation as the thermal source of preheater 2 after direct back boiler.

In the step (1), described chlorohydrination is produced the waste water feed liquid that produces in the propylene oxide process and is entered first single-effect evaporator 4 through preheater 3 with the 2 heating backs mode parallel with giving birth to vapour stream, one secondary steam and the feed liquid of imitating the evaporation generation all is conveyed into the first effect separator 5, secondary steam is imitated separator 5 through first and is carried out gas-liquid separation, wherein, secondary steam enters second single-effect evaporator 6 as thermal source, and the feed liquid of separator 5 bottoms is delivered to quadruple effect vaporizer 12 and carries out heating evaporation; Afterwards, the feed liquid of vaporizer 12 and steam import quadruple effect separator 13 and carry out vapor-liquid separation, wherein liquid phase material and steam import quintuple effect evaporator 14 again, and the water of condensation part of fourth evaporator 12 sends that feed liquid pond, a part import quintuple effect evaporator 14, another part directly imports in the phlegma basin 16 back to; Feed liquid and steam is further heating evaporation in quintuple effect evaporator 14, all import then in the 5th effect separator 15 and carry out gas-liquid separation, liquid phase material after the separation imports in second single-effect evaporator 6 after preheater 21 heating, steam then imports in the direct condenser 17 and handles, and the water of condensation part of vaporizer 14 imports in the phlegma basin 16, a part of feed back liquid pool; Enter the further heating evaporation of liquid material of second single-effect evaporator 6, its heating thermal source is to imitate the steam that is directed into vaporizer 6 by first, steam that produces in the vaporizer 6 and liquid material import in the second effect separator 7 again and carry out gas-liquid separation, import third effect evaporator 8,9 again and carry out evaporation concentration, the water of condensation part of vaporizer 6

imports preheater

3,21 successively as thermal source, a part of feed back liquid pool; Liquid phase material is at vaporizer 8, further all be delivered in the triple effect crystallizer 10 with the steam of its generation after the evaporation concentration in 9, obtain concentrated solution, the delivery of steam that produces in the crystallizer 10 to fourth evaporator 12 as thermal source, third effect evaporator 8 is interconnected with third effect evaporator 9, the partial condensation water that generates through third effect evaporator 9 enters third effect evaporator 8 as thermal source, and the water of condensation part that triple-effect evaporator produces imports preheater 3 successively as thermal source and 21 pairs of feed liquids are heated, and finally being delivered to phlegma basin 16, a part is sent the feed liquid pond back to.

The 5th imitates the steam importing direct condenser 17 that separator 15 produces, and obtains water of condensation and flows back to cooling basin 18, and behind circulating condensing, steam is discharged after moisture separator 19 and water ring vacuum pump 20 processing again.

In step (2), the waste water feed liquid is further evaporation concentration in triple effect crystallizer 10, the concentration of calcium chloride is concentrated to about 70～90%, import in the crystal separator 11, step (3) forms calcium chloride crystal (containing crystal water) and separates through cooling process in crystal separator 11 then, 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.Wherein, comparatively preferred separation method is a centrifugal separation, by separating centrifuge the calcium chloride crystal is separated, granular calcium chloride is delivered to the rewinding automatic packaging system and is packed outward transport, and the calcium chloride saturated solution is delivered to and returns triple effect crystallizer 10 and crystal separator 11 after third effect evaporator 8, the 9 further evaporation concentration and carry out revaporization and concentrate and the recrystallization separating treatment.

Can detect up to standard can directly discharging at the water of condensation of phlegma basin 16 and cooling basin 18 acquisitions behind abovementioned steps (4) multiple-effect evaporation, perhaps, send all water of condensation back to workshop and reuse.Below standard can directly carry out a biological disposal upon.Biological treatment is being known in the art and can finding the modular design standard in the standard engineering handbook with reference to wastewater treatment.

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 pump feed evaporator and 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.

With this routine method of wastewater treatment and device the trade effluent of producing propylene oxide from chlorohydrination is handled, the chemical oxygen demand (COD) (COD) of the water of condensation in phlegma basin 16 and cooling basin 18 after the processing is less than 100mg/l, satisfy the wastewater treatment emission request, wherein, described chemical oxygen demand (COD) (COD) is meant under defined terms, make in the water sample amount of the required consumption oxygenant of material oxidation that can be oxidized, show with the milligram numerical table of every premium on currency oxygen consumed.

Example two

Please in conjunction with Fig. 3 to Fig. 6.Multi-effect evaporating device in this example comprises that five imitate 23-27, enrichment effect 28, also comprise respectively with one and imitate the preheater 30-33 that is connected to quadruple effect, imitate the water cooler 29 that is connected with the 5th, water-ring vacuum pump 50 that is connected with water cooler 29 and chilled water tank (not icon), be connected in one-level, secondary, three grades of flash-pot 40-42 between an effect 23 and the enrichment effect 28, store the condensate draining 53,54 of water of condensation, the thickener 22 of pretreated waste water feed liquid, and the flaker (not shown) that forms calcium chloride crystal and isolation of crystalline.Be interconnected with pipeline between each unit, to realize the transmission of vapour, liquid, solid materials.This routine multi-effect evaporating device is used for the processing of the waste water that reverse-flow processing produces from olefin oxide production technology.

In each single-effect evaporator, wherein one of the easiest fouling imitate 23, thermal oil single-effect evaporator (enrichment effects) 28 all adopts pump feed evaporator, all the other quadruple effects employing falling-film evaporators.First imitates 23 to give birth to steam (new water vapor) as heating source.

Also comprise before in abovementioned steps (1) waste water is carried out pretreated step.At first will contain about 5%CaCl ₂Waste water enter the thickener 22 of band mud scraper, this composite waste temperature is about 80 ℃, thickener 22 in is that 11.5～12.0 waste water passes through pH robot control system(RCS) adding hydrochloric acid adjust pH to 7.0～8.0 with pH value, makes CaCO ₃And Ca (OH) ₂Insoluble substance produces precipitation, and the body refuse that precipitates is delivered to lime calcining system in the factory by sludge pump.Waste water is regulated water quality and quantity in the thickener 22 of insulation simultaneously.

In the step (1), pretreated waste water is pumped to quintuple effect evaporator again, and evaporation concentration makes CaCl in the waste water ₂Concentration be concentrated to about 50%, step (2) is the waste water of step (1) to be delivered in the enrichment vaporizer 28 continue to be concentrated into more than 70%, as 75%, when reaching 75%, calcium chloride concentration directly enters flaker, step (3) is carried out crystallization and is produced Calcium dichloride dihydrate, the calcium chloride that flaker gets off advances packaging system, packaging final prod warehouse entry storehouse.

In the step (4), an effect is got back to boiler and is recycled after giving birth to steam condensate employing flash distillation recovery heat energy.Two, three, four, five water of condensation of imitating reach COD _Cr≤ 300mg/L, Cl ^-The target of≤100mg/L can be got back to the production of propylene oxide workshop according to analysis and be used as water of productive use.

Because of the increase with concentration of the boiling point of solution raises, in order to keep the evaporation of calcium chloride solution under the dense state of height, this example adopts resistant to elevated temperatures thermal oil, heats dense calcium chloride solution (concentration 〉=50%) as hot-fluid, the coal gas that thermal oil transforms with coal, the heat energy heating that burning produces.The water of condensation of this effect is also got back to production plant.This steam of imitating generation is directed at and carries out circular treatment in the quintuple effect evaporator 27.

In this example, each is imitated vapo(u)rization system and comprises an evaporator room that is interconnected and separate chamber (not icon), is equipped with Despumation device in this separate chamber, has effectively avoided the secondary steam vapour-liquid to carry secretly, keep the qualified reuse of water of condensation COD, avoid causing the corrosion of subsequent evaporation device, pipeline, pipe fitting simultaneously.

The detailed ginseng of the flow line of steam, material and water of condensation Fig. 3 to Fig. 6 specifically describes as follows.

(1) steam flow

In order to reduce steam consumption quantity as far as possible, save energy reduces processing cost, and this example adopts reverse-flow quintuple effect evaporator structure.Give birth to steam and enter an effect, one imitates evaporation produces secondary steam and imitates in the separate chamber with after feed liquid is separated first, enter 2nd effect evaporator as thermal source, two steam of imitating the evaporation generation enter triple effect, the steam that triple effect evaporation produces enters quadruple effect, and the steam that the quadruple effect evaporation produces enters quintuple effect evaporator as thermal source.Five steam of imitating the evaporation generation enter water cooler 29 (condenser) condensation, water receiving ring type vacuum pump 50 behind the water cooler, and the gained water of condensation is stored by a chilled water tank, and sends into the workshop reuse.The secondary steams that 28 evaporations of enrichment effect produce become liquid water of condensation and are back to use production plant after the water drip cooler cooling.The steam of one-level, secondary, three grades of flash-pot 40,41,42 generations imports respectively in the second effect preheater, 31, the triple effect preheaters, 32, the quadruple effect preheaters 33 and carries out heat treated.

(2) feed liquid flow process

Stock liquid enters 27 dischargings of quintuple effect evaporator 27, five effects through the pump pressurization and enters quadruple effect preheater 33 through pump, enters quadruple effect evaporator 26 behind the prevapourising again.Quadruple effect evaporator 26 dischargings enter triple-effect evaporator 25 after being pumped to triple effect preheater 32, triple effect 25 dischargings are advanced 2nd effect evaporator 24 again after pump advances two effect preheaters, 31 prevapourisings, two imitate 24 dischargings imitates the laggard 1st effective evaporator 23 of preheater 30 prevapourisings through pump to, one imitates 23 dischargings pass through one-level, secondary, three grades of flash-pot 40,41,42 flash distillations successively under pressure promotes after, enter thermal oil single-effect evaporator (also claim enrichment imitate) 28 and continue to be concentrated into calcium chloride concentration and reach 75%, be pumped to flaker by discharging pump.

(3) phlegma flow process

First water of condensation of imitating 23 generations are to form by giving birth to vapor condensation, thereby not comtaminated, get back to boiler and recycle after

condensation water pot

51,52 reclaims heat energy.Second and third, the water of condensation of

quadruple effect

24,25,26 drains into condensation pond 53,54, the condensation pond is divided into two, one is that 53, one of qualified reuse pools are defective pond 54.According to draining water quality, water of condensation enters qualified and defective pond respectively, and qualified water is back to use production plant, and defective water enters existing sewage works.

In order to adapt to the continuous rising of calcium chloride strong solution boiling point, enrichment is imitated in 28 with high temperature heat conductive oil and is concentrated concentration greater than 50% calcium chloride solution, with burning coal gas heating thermal oil, heating back thermal oil returns in the gas furnace and heats once more, recycle, under the promotion of vacuum pump, keep negative pressure in the vaporizer of enrichment effect 28, improve heating efficiency, increase effective temperature difference.Wherein, the gas fired-boiler part at first is converted into coal gas with coal by gas generating station, enters burning heating thermal oil in the gas fired-boiler then.Its technical process is: the circulation oil return is isolated gas through gasoline trap, enters in the roasting kiln through the elimination dregs of fat in the filter again, as thermal barrier, enters thermal oil and imitates the evaporation concentration calcium chloride solution after the burned gas heating.The thermal oil that the subsystem of thermal oil will newly be replenished is delivered to expansion slot through oil pump, establishes vapor pipe on the expansion slot, and the bottom links to each other with gasoline trap and oil return pipeline.Expansion slot is mainly the volume change that prevents that oily cold and hot variation from causing, and influences the normal operation of system, simultaneously the waste gas that produces in the operational process is discharged, and the full cycle heat-conducting oil system is sealed, anti-oxidation.System is provided with a storage tank and stores waste oil.

The flaker packed portion adopts the rotary drum flaker, the calcium chloride solution decrease temperature crystalline with 75%, production sheet Calcium dichloride dihydrate.Flake calcium chloride enters recovering hopper, after row spiral blanking device dominant discharge, carries out finished product packing with manual packaging system.The cooling system of flaker adopts water of condensation by the interchanger of establishing in the flaker high-temp chlorination calcium to be lowered the temperature, and forms the Calcium dichloride dihydrate crystal.

Multiple-effect evaporation of the present invention is handled waster water process and equipment, and technology maturation is reliable, can realize full-automatic control, though its equipment one-time investment cost is higher, can recoup the investment in general one to three year.After treatment, water of condensation can reach emission standard, also reclaim a large amount of calcium chloride solids, solve effective handling problem of the waste water that produces in the chlorohydrination production propylene oxide process, making chlorohydrination production propylene oxide process be preserved and expand the scale of production becomes possibility.Example two reverse-flow multiple-effect evaporation treatment process and equipment particularly can not only efficient recovery Industrial products calcium chloride solid, and all handle products, comprises that water of condensation all can return the production of propylene oxide workshop and use as water of productive use.As calculated, the present invention handles the method for waste water, but the about 20 yuans of profits of the waste water extra earning per ton profit of water of condensation reuse water (and do not contain).

In addition, calcium chloride is not only sold and is used as Industrial products with its solid form, and simultaneously, its solution is that 30～50% solution is also extensively sold and used as Industrial products as concentration, particularly market abroad.In the cross-flow of previous example one and example two and the counter-current treatment technology, the waste water feed liquid is imitated to five effect evaporation concentration through one, the calcium chloride product that each concentrated solution that imitate to form also can be used as different concns directly is packaged into product and uses or sell, and does not form strong solution (crystallisation by cooling forms Calcium dichloride dihydrate solid or the dry calcium chloride powder that forms) processing 70% or more and do not need to imitate further evaporation concentration through crystallizer or enrichment.

Processes and apparatus with example two is that example is made a concrete analysis of, and utilizes technology of the present invention and device to obtain the calcium chloride product of different concns.Because of this technical process with working temperature and pressure as impellent, for keeping the technological process safety and stability, should select suitable temperature and pressure condition, to control the steam output of every effect according to the device security coefficient.Because the raising liquid chamber pressure can reduce the solution boiling point, rising liquid chamber temperature helps evaporation, and the concentration that therefore can obtain calcium chloride solution is as required regulated temperature and the pressure that each is imitated.Following table is a specific examples parameter, counter-current process by example two is handled, the starting point concentration of calcium chloride is 5% in the waste water stoste, because of the 5th effect 27 operating pressure are lower, waste water stoste is evaporated in a large number, is the control steam output, keep the entire equipment steady operation, stoste imitates 27 by part importing the 5th in the thickener 22 after pre-treatment, a part imports quadruple effect 26, and therefore the 5th effect concentration is higher than quadruple effect.Handle processing parameter and result table 1 specific as follows according to the technical process that previous example two is described:

Table 1

Project

Unit

One imitates

Two imitate

Triple effect

Quadruple effect

Five imitate

Enrichment is imitated

The one-level flash-pot

Steam (oil) temperature

℃?

165?

104.5?

90.5?

74.5?

265?

?

Liquid chamber pressure

MPa?

～0.212?

～0.073?

～0.039?

～0.015?

0.121?

～0.121?

～0.073?

～0.039?

Solution temperature

℃?

144?

92.5?

76?

58?

254?

127.5?

113.5?

97.5?

Cacl2 concentration

％?

49.23?

11.41?

8.14?

16.98?

74?

49.51?

49.74?

50.00?

From last table as seen, one to five imitates and one to three grade of flash-pot is handled the calcium chloride solution that produces different concns, can directly be packaged into solution product and use or sell, and the calcium chloride solution that enrichment is imitated forms Calcium dichloride dihydrate after cooling off.Imitate or parameters such as heating-surface area, the steam (oil) of flash-pot are warm, liquid chamber (in the evaporator room) pressure, solution (waste water feed liquid) temperature by regulating each, can obtain the calcium chloride solution of other concentration, to adapt to various different requirements.

Be appreciated that, directly import the calcium chloride solution of the different concns of respectively imitating gained of the multi-effect evaporating device of aforementioned each embodiment in one drying plant, perhaps aforementioned crystal separator 11 or flaker are replaced with a drying plant, directly calcium chloride solution or the calcium chloride concentrated solution to different concns carries out drying treatment, thereby obtains calcium chloride pressed powder product.Wherein said drying plant can be the baker or the drying tower of prior art.

Claims

1. alkylene oxides production wastewater treatment method is characterized in that comprising: step (1), and waste water is carried out multiple-effect evaporation handle, thereby obtain containing the solution of different concns calcium chloride in each effect; Step (2) to the solution further evaporation concentration of step (1) after multiple-effect evaporation is handled, obtains the calcium chloride concentrated solution; Step (3) is carried out crystallization or drying treatment with the calcium chloride concentrated solution of step (2), the calcium chloride solid; Waste steam is reclaimed in step (4) condensation; It is the cross-flow operation mode that the multiple-effect evaporation of described step (1) is handled.

2. alkylene oxides production wastewater treatment method according to claim 1, it is characterized in that: also comprise before in step (1) waste water is carried out pretreated step: the temperature of regulating waste water is 75 ℃-85 ℃, it is 6.0-8.0 that waste water is added acid accent waste water ph, thereby make lime carbonate and high boiling insoluble organism produce precipitation, to precipitate removal, will place the regulating tank of insulation to store through pretreated waste water at last.

3. alkylene oxides production wastewater treatment method according to claim 1 is characterized in that: each of described multiple-effect device imitated and to be comprised heating and evaporating unit and tripping device, is interconnected between this heating and evaporating unit and the tripping device or is connected with pipeline; Described step (2) is to heat outside that evaporation forms concentrated solution in the pump feed evaporator of forced circulation evaporation crystallizer or heat-conducting oil heating, and described step (3) is to carry out crystallization in crystal separator or flaker, and is dry in baker or drying tower.

4. alkylene oxides production wastewater treatment method according to claim 1, it is characterized in that: the multi-effect evaporating device of described step (1) is five effect evaporation units, the waste water feed liquid is imitated heating evaporation through first, fourth, five successively and is entered second effect, triple effect evaporation again, and step (2) is further to evaporate to form concentrated solution in the crystallizer of triple effect; Step (3) be with crystal separator that described crystallizer and triple effect are communicated with in carry out crystallization and separate.

5. multi-effect evaporating device that is used for alkylene oxides production wastewater treatment method, it is characterized in that: described multi-effect evaporating device mainly comprises several effects, upgrading unit and solid separating device, between each is imitated, be connected by pipeline between effect and upgrading unit and the solid separating device, each of described multiple-effect device imitated and to be comprised heating and evaporating unit and tripping device, is interconnected between this heating and evaporating unit and the tripping device or is connected with pipeline; Described upgrading unit is the pump feed evaporator of outer heating forced circulation evaporation crystallizer or heat-conducting oil heating; Described solid separating device is meant crystal separator, flaker or drying plant.

6. multi-effect evaporating device according to claim 5, it is characterized in that: described multi-effect evaporating device comprises 5 effects, be suitable for the cross-flow treatment process, the first, the 4th, the 5th imitate the employing falling film evaporator, first imitates to give birth to steam heating, second imitates the outer heating of employing natural-circulation evaporator, and triple effect adopts outer pump feed evaporator and the described outer heating forced circulation evaporation crystallizer of heating.

7. multi-effect evaporating device according to claim 6 is characterized in that: described multi-effect evaporating device further comprises condenser, cooling basin, moisture separator and water ring vacuum pump; Condenser is imitated the steam of discharging to last and is carried out condensation, generate water of condensation, and by the cooling basin it is reclaimed, moisture separator and water ring vacuum pump are communicated with condenser, and the steam of discharging from condenser directly discharges or sends into the cooling basin after moisture separator and water ring vacuum pump are handled; Described multi-effect evaporating device comprises further that also being used for that thermal pretreatment is carried out in logistics enters the preheater of imitating preceding temperature to adjust logistics, and is used to collect the phlegma basin that each imitates the water of condensation of discharging.