CN101027249B - Manufacture of high-strength, low-salt sodium hypochlorite bleach - Google Patents

Abstract

A process and apparatus for the manufacture of high-strength, low-salt sodium hypochlorite. An aqueous solution that comprises certain weight percentages of sodium hypochlorite and sodium hydroxide and that is essentially free of sodium chloride (salt) crystals, an aqueous solution that comprises a certain weight percentage of sodium hydroxide, and chlorine in gas and/or liquid phase that may or may not include inerts are reacted in a tank. This creates a solution having a precipitation zone where salt crystals are precipitating out of solution and falling downward to form a slurry, some of which is withdrawn, then cooled, and then re-introduced into the precipitation zone. Above the precipitation zone is a crystal-free mother liquor zone consisting essentially of crystal-free mother liquor containing a weight percentage of sodium hypochlorite greater than that of than the lower strength aqueous sodium hypochlorite bleach being reacted.

Description

The manufacturing of high density, less salt hypochlorite bleaching

Technical field

The present invention relates to the manufacturing of hypochlorite bleaching (bleach), especially for making this SYNTHETIC OPTICAL WHITNER, the especially method and apparatus of sodium hypochlorite bleaching agent.

Background technology

SYNTHETIC OPTICAL WHITNER (clorox) is a kind of household chemicals that is used for numerous application.The Essential Chemistry that is used for making SYNTHETIC OPTICAL WHITNER is well-known at chemistry and field of chemical engineering.Make chlorine and sodium hydroxide (caustic alkali) solution reaction in gas and/or the liquid phase, thereby produce aqueous clorox.Although think that this Essential Chemistry is quite elementary, and quite common for all methods that are used for commercial manufacturing SYNTHETIC OPTICAL WHITNER, disclosed concrete grammar is but significantly different in patent documentation.

Known, multiple each of the commercial method of making SYNTHETIC OPTICAL WHITNER of being used for, its feature or be intermittent type (discontinuous) production method perhaps is the continuity production method.The method of each type all has himself special advantage.

Suitably the continuity method of control more may carry out with higher production efficiency than corresponding batch process, therefore, and may be more economical than batch process.But the concrete mode of carrying out continuity method can play an important role to the character and the quality of the SYNTHETIC OPTICAL WHITNER product that produced.

United States Patent(USP) Nos. 4,428,918 and 4,708,303 disclose a kind of method that concentrates (being high density (high strength)) chlorine bleach liquor that is used for making separately.But sodium-chlor (salt) also is the product of this basic reaction, and it both can improve this continuity method from the removal in this moisture clorox product, can improve the product that is produced again.There is not a kind of method can from the product that is produced, remove all these salt in the described method.

United States Patent (USP) 4,428,918 to disclose the product that is produced be the aqueous solution of clorox, and it is regained with the speed of 1775kg (kilogram) per hour, and every kilogram of product, and it contains 257g (gram) clorox and 94g dissolved sodium-chlor.This method of it is said has produced a kind of suspension, and some salt are removed from this suspension by filtration unit, and per hour the cut of this suspension 2051Kg cycles through this filtration unit.The aqueous solution of this clorox takes out from this filtration unit, and it is said that this filtration unit isolates filter cake, and this cake contains by weight 80.1% sodium-chlor and 19.9% clorox.Not mentioned any sodium chlorate or the excessive caustic alkali of in the clorox product that is produced, existing of this patent.

U.S. Patent No. 4,428,918 quantitative salt crystalline sizes in these suspension also, but to observe really that tiny salt crystalline economy removes be very difficult for it.Allegedly can increase the crystalline size by this suspension of heat exchanger recirculation, this suspension of this heat exchanger cooling.Also allegedly finally reach a bit, can not further increase the crystalline size again at this point.According to understanding, this suspension spreads all over whole post and exists, and produces crystallization in this post, therefore will not be substantially free of crystalline mother liquor zone.

U.S. Patent No. 4,708,303 disclose a kind of continuity method, and wherein in the disclosed second stage or crystallizer, salt is crystallization from suspension.The solution that will obtain from the first step, allegedly contain 14.5% clorox and 3.2% sodium hydroxide is incorporated into the second stage, and wherein, thereby it produces aqueous sodium hypochlorite solution with the chlorine reaction, and salt not only exists in solution but also be present in the suspension.In this crystallizer, make described solution stand mechanical stirring, take out this solution from this crystallizer top simultaneously, make it by external heat exchanger recirculation, and it is incorporated into the bottom of crystallizer again.To shift from described heat exchanger from a part of solution that take out at this crystallizer top, thereby form the SYNTHETIC OPTICAL WHITNER product produced, it is said that it contains 25% clorox, 9.5% sodium-chlor and excessive slightly caustic alkali (by weight 0.3%～0.8%).

Allegedly do not have the salt precipitation in the first step, wherein chlorine reacts with caustic solution, thereby produces the solution that is incorporated in the second stage.It is said and continuously or off and on institute's crystalline salt is removed from the second stage, and it is said that its average crystalline size is near 400 microns (approximately 400-500 microns) by precipitation.It is said that excessive slightly caustic alkali avoids forming sodium chlorate (NaClO ₃), but the amount of the sodium chlorate that the unexposed described SYNTHETIC OPTICAL WHITNER product actual capabilities of this patent contain.

Because U.S. Patent No. 4,708,303 need the contained thing in the stirred type crystallizer, thereby promote reaction, so, it should be understood that the solution that takes out from described crystallizer top can the saliferous crystal.

Two patents think that all some batch process can produce aqueous, high density SYNTHETIC OPTICAL WHITNER, and a large amount of salt are removed from described SYNTHETIC OPTICAL WHITNER.Home and overseas patent by reference is with reference to multiple batch process.

It is believed that always can to produce continuity method moisture, the high density SYNTHETIC OPTICAL WHITNER very favourable to industry, described SYNTHETIC OPTICAL WHITNER has the sodium-chlor and the sodium chlorate of low concentration, and has remaining, excessive slightly caustic alkali.With United States Patent(USP) Nos. 4,428, the product of mentioning in 918 and 4,708,303 is compared, and has bigger concentration, less salt and perchlorate concentration's product particularly advantageous more.These interests are the practicality of product and relevant economic factors.

The explanation of brief summary of the invention and the inventive method

The present invention relates to a kind of method, by the equipment of described method production SYNTHETIC OPTICAL WHITNER and the high density that is produced, less salt SYNTHETIC OPTICAL WHITNER product.

Verified when being diluted to general family expenses, when commercial SYNTHETIC OPTICAL WHITNER has the low concentration of comparability, high density, less salt SYNTHETIC OPTICAL WHITNER by the inventive method and device fabrication have stability, therefore when comparing, prolonged the transformation period (half-life) with such SYNTHETIC OPTICAL WHITNER.

One aspect of the invention comprises a kind of by low concentration, high density is made in moisture sodium hypochlorite bleaching agent continuously, less salt, the method of moisture sodium hypochlorite bleaching agent, described low concentration, moisture sodium hypochlorite bleaching agent has some sodium hydroxide, and be substantially free of sodium-chlor (salt) crystal, described method comprises: in still, make 1) low concentration, (it has some sodium hydroxide in moisture sodium hypochlorite bleaching agent, and be substantially free of the salt crystal), 2) (its concentration by weight for aqueous sodium hydroxide solution, in about scope of 45%～about 51%) and 3) chlorine (it can contain or not contain inert fraction) successive reaction in gas phase and/or the liquid phase, thereby produce such solution, it has a) precipitation zone, wherein the salt crystal is precipitated out in solution, and thereby landing forms slurry downwards, some slurry are taken out, cooling then, and then be incorporated into precipitation zone, and b) the not crystalliferous mother liquor zone on this precipitation zone (it is made up of not crystalliferous mother liquor basically, the weight percent of the clorox that this mother liquor contains greater than by reacted, low concentration, the weight percent of moisture sodium hypochlorite bleaching agent.

Another aspect comprises a kind of by low concentration, moisture hypochlorite bleaching is made high density continuously, less salt, the method of moisture hypochlorite bleaching, described low concentration, moisture hypochlorite bleaching has some oxyhydroxide, and be substantially free of muriate (salt) crystal, described method comprises: in still, make 1) low concentration, (it has some oxyhydroxide to moisture hypochlorite bleaching, and be substantially free of the salt crystal), 2) chlorine in gas phase and/or the liquid phase (it contains or do not contain inert fraction) successive reaction hydroxide aqueous solution and 3), thereby produce such solution, it has a) precipitation zone, wherein the salt crystal is precipitated out in solution, and thereby landing forms slurry downwards, some slurry are taken out, cooling then, and then be incorporated into precipitation zone, and b) the not crystalliferous mother liquor zone on this precipitation zone (it is made up of not crystalliferous mother liquor basically, the weight percent of the hypochlorite that this mother liquor contains greater than by reacted, low concentration, the weight percent of moisture hypochlorite bleaching.

Another aspect of the present invention comprises a kind of high density, less salt SYNTHETIC OPTICAL WHITNER product, it contains by weight the aqueous solution greater than the sodium hydroxide (caustic alkali) of 25% clorox and excessive slightly (slight excess), and based on weight percent, when the clorox of 25% weight, the ratio of NaCl (salt) and NaOCl (clorox) is significantly less than (less than substantially) 0.38, and this ratio is increased to more than 25% along with the per-cent of clorox and reduces.

Another aspect of the present invention comprises and is used to make high density, less salt, the equipment of moisture sodium hypochlorite bleaching agent, it comprises: reactor, to wherein introducing and making 1) (it contains by weight water-containing product, clorox at least about 15% and by weight, 4.5% sodium hydroxide, and be substantially free of the salt crystal), 2) (its concentration by weight for aqueous NaOH, in about scope of 45%～about 51%) and 3) chlorine (it can contain or not contain inert fraction) reaction in gas phase and/or the liquid phase, thereby produce a kind of like this solution, it has a) lower region, and (wherein the salt crystal is precipitated out in solution, and thereby landing forms slurry downwards, some slurry are taken out, cooling then, and then be incorporated into the wherein lower region of deposited salt) and (this mother liquor has by weight b) to be substantially free of the upper area of crystalline mother liquor, clorox greater than 25% and by weight, salt less than about 9.5%), the inlet that described still has outlet and is provided with highlyer than this outlet, slurry takes out from lower region in this exit, the slurry that takes out is incorporated in the lower region in this ingress again, be connected the heat exchanger between the entrance and exit, to be used for that heat is delivered to the liquid coolant that flows through this heat exchanger from the slurry that takes out, inner cylindrical wall skirt baffle (internal cylindrical walled baffle skirt), the cylindrical wall synergy of itself and this still, thereby form the stable zone of annular, this zone is at bottom opening and extend upward, thereby is defined for the inner boundary (inner boundary) that enters upper area.

Another aspect comprises and is used to make high density, less salt, the equipment of moisture hypochlorite bleaching, it comprises: reactor, to wherein introducing and making 1) (it contains hypochlorite and oxyhydroxide to water-containing product, and be substantially free of the salt crystal), 2) aqueous hydroxide and the 3) chlorine in gas phase and/or the liquid phase (it can contain or not contain inert fraction) reaction, thereby produce a kind of like this solution, it has a) lower region, and (wherein the salt crystal is precipitated out in solution, and thereby landing forms slurry downwards, some slurry are taken out, cooling then, and then be incorporated into the wherein lower region of deposited salt) and the upper area that b) is substantially free of the crystalline mother liquor, the inlet that described still has outlet and is provided with highlyer than this outlet, slurry takes out from lower region in this exit, the slurry that takes out is incorporated in the lower region in this ingress again, be connected the heat exchanger between the entrance and exit, to be used for that heat is delivered to the liquid coolant that flows through this heat exchanger from the slurry that takes out, the cylindrical wall synergy of inner cylindrical wall skirt baffle itself and this still, thereby form the stable zone of annular, this zone is at bottom opening and extend upward, thereby is defined for the inner boundary that enters upper area.

In brief, a kind of device example of implementing the principle of the invention comprises level, and it comprises still or groove, wherein introduces:

1) aqueous solution, it contains the clorox and the sodium hydroxide of certainweight per-cent, and is substantially free of sodium-chlor (salt) crystal;

2) aqueous solution, it contains the sodium hydroxide of certainweight per-cent; And

3) chlorine in gas phase and/or the liquid phase, it can contain or can not contain inert fraction.

For simplicity, this level can be referred to as crystallizer stage sometimes.

Can any suitable mode at same equipment as in prime, producing above-mentioned clorox and aqueous sodium hydroxide solution, perhaps can other local make this aqueous solution and with this equipment of it charging in.For simplicity, such can be referred to as initial level in prime sometimes.Owing to before crystallizer stage, also this initial level can be referred to as the first step sometimes, in this case, crystallizer stage can be referred to as the second stage sometimes.

The preferred method that is used for this first step comprises a kind of continuity method that produces the aqueous solution, and this aqueous solution contains by weight, the clorox greater than 15%, and the non-sodium chloride precipitation, and contain excessive slightly caustic alkali, by weight, at least 0.5%, preferably higher slightly.Be incorporated into the first step by caustic alkali (sodium hydroxide) and produce this solution chlorine in liquid phase and/or the gas phase (moistening or dry, as to contain or do not contain inert fraction) and enough concentration.The dilute hydrogen sodium oxide will make water if desired.

If the caustic sodium concentration that is incorporated in the first step still is at least 24%, the liquid product of the first step will be for by weight, surpasses 15% clorox (NaOCl) and by weight, 4.5% sodium hydroxide (NaOH).Therefore, although the caustic alkali that the more conventional principle of the present invention needn't need to have high density like this,, for some principle of the invention disclosed herein, being at least 24% caustic alkali at first step working concentration will be highly significant.For example, some are formed with high density of the present invention, less salt SYNTHETIC OPTICAL WHITNER product (will disclose its characteristic below, and it is by the preferred embodiment production of the inventive method) identical SYNTHETIC OPTICAL WHITNER can be such method production, wherein the input concentration of first step caustic alkali is lower than 24% to a certain extent.

High density of the present invention, less salt SYNTHETIC OPTICAL WHITNER product contain by weight, surpass 25% aqueous sodium hypochlorite solution, and based on weight %, NaCl (salt) is significantly less than (lessthan substantially) 0.38 with the ratio of NaOCl (clorox), and contains excessive slightly sodium hydroxide (caustic alkali).After removing solid, by weight, to contain about 30% clorox, NaCl/NaOCl ratio be about 0.21～about 0.25 and contain slightly that the SYNTHETIC OPTICAL WHITNER of excess caustic is an embodiment of high density disclosed herein, of the present invention, less salt SYNTHETIC OPTICAL WHITNER product.

When based on weight percent, first step sodium hydroxide is added in the sodium hydroxide of the second stage, and one-level not in office is when adding chlorine, by weight, the total effective weight per-cent of caustic alkali that is used to produce this SYNTHETIC OPTICAL WHITNER is greater than 33%.If there is not chlorine to add the first step or the second stage to, this is the weight percent of caustic alkali in the solution.If having the method for identical net result can finish in a level, and after chlorination caustic alkali, to from solution, remove all sedimentary salt, when chlorination is arrived by weight, when surpassing 25% clorox and having the terminal point of excess caustic slightly, surpass 33% sodium hydroxide and generation is lower than 9.5% NaCl.Arbitrary grade temperature can be above 30 ℃.But, by partial temperature being controlled to about 30 ℃, will see in a kind of preferred embodiment of the inventive method and can advantageously use cooling tower water that described embodiment is used the heat exchanger of some type.But in another kind of preferred embodiment, the principle of the invention has also been considered use softening water or cold water (tempered or chilled water), to be used for the heat exchanger of some other type.

To be fed in the second stage from the solution in the first step still, caustic solution (by weight, the amount of caustic alkali is in about scope of 45%～about 51%) (preferred 48%～51%) and chlorine, wherein arrange some equipment, thereby form the surface cool crystallizer.The surface cool crystallizer is any system, and it provides enough retention time, chemical process supersaturation and cooling, thereby realizes the crystalline growth.Two kinds of solution are added in the second stage respectively, form hydrate thereby stop.Described chlorine can be liquid and/or gas, moistening or dry, contain or do not contain inert fraction.By commercially available equipment, use suitable measuring method such as redox to measure, control the per-cent of excess caustic in the solution in any suitable manner.

Heat exchanger is an equipment that links to each other with second stage still.By solution recirculation is removed in the solution from the still of the second stage heat of solution and reaction by this heat exchanger.By using high recirculation rate (recycle rate) by this heat exchanger, return temperature between the return port (return) of described still from described still recirculation outlet and recirculation and fall and keep very for a short time making, thereby mode with expectation, in the crystallization of still internal control salt manufacturing, avoid polluting described heat exchanger simultaneously.The use of high recirculation rate is an another aspect of the present invention, and described speed is used for described temperature fallen and keeps very for a short time, thereby forms with particular form control salt crystalline.Typical temperature falls about 1

～about 4 Scope in, most preferred scope is about 1

～about 2

Be controlled in such scope for temperature is fallen, described heat exchanger is such heat exchanger, and is relevant with the flow velocity of each liquid that flows through it, and it has enough heat interchanging areas, and it is very little to flow limitation.By the chemical process in the crystallization control device level aptly, the temperature of those processes can be remained in such scope, as the cooling liqs in some type heat exchanger, this is another aspect of the present invention (being avoided using the needs of more expensive refrigerated water (refrigerated water)) with cooling tower water in its permission.But the principle of the invention is also considered really and is used refrigerated water or cold water, to be used for the heat exchanger of some other type.

Another aspect of the present invention relates to the temperature difference between the cooling liqs of controlling recirculation solution and flowing through heat exchanger.The target zone of avoiding polluting the temperature difference of heat exchanger depends on the design of particular heat exchanger.For board-like or frame heat exchanger, temperature range is about 2 ～about 3 For the shell-and-tube exchanger that other heat exchanger uses together as Swenson surface cool crystallizer, the described temperature difference can have bigger scope, and for example 5

～15

The inventive method forms at the top of next-door neighbour's crystallizer stage tank and is substantially free of the crystalline mother liquor, and forms the salt slurry in its bottom of next-door neighbour.When the fresh solution with SYNTHETIC OPTICAL WHITNER and caustic alkali was continuously fed in the still, the slurry that will be positioned at the bottom pumped continuously, and simultaneously, based on going into still and the total flux and the discharge that go out still, described mother liquor rises.Such level is controlled or is adjusted in the rising of described mother liquor, perhaps allow or do not allow the mother liquor overflow.When allowing described mother liquor overflow, this overflow is collected as high density, less salt SYNTHETIC OPTICAL WHITNER.

Skirt baffle in the cylindrical side wall of described crystallizer stage tank forms cylindrical wall, and it forms the stable zone of annular between skirt baffle and still sidewall.The stable zone of described annular has the not crystalliferous mother liquor upper area and the lower region of salt precipitation and decline wherein.This skirt baffle is around the center inner region.Described annular Anding District, particularly there is not turbulent flow basically at the top.By with suitable speed continuous overflow mother liquor, lower region (in described zone, not having turbulent flow) in deposited salt, land, add in the slurry downwards and make the residual solution supersaturation, thereby in solution, promote crystalline to form and grow.

Because the characteristic of the inventive method, will described mother liquor from upper area take out or overflow to cause the crystallization of salt, still, and mother liquor is taken out so that the residual solution supersaturation is compared, the crystallographic dimension that is produced is less usually.Some the process control condition that is used for the inventive method can produce enough big salt concn, thereby causes crystallization, and does not have the necessity of taking out any mother liquor.

As surface-cooled result (it is provided by crystallizer stage, takes out or do not take out mother liquor), in the crystallizer still, salt continuous crystallisation from solution comes out and landing downwards, thereby continuous supplementation is positioned at the slurry of still bottom.

Carry out described method by this way, thereby make that the surface cool of crystal salt promotes the crystalline growth in the solution.The increase of the crystallographic dimension that is caused helps crystalline to separate, thereby because their landing form the slurry that is positioned at the bottom and afterwards by the solution in the still, in the method, is reclaiming by separating from slurry subsequently.Another aspect of the present invention, in slurry, the distribution of the salt crystallographic dimension that is produced makes them be well suited for finally being recovered as exsiccant solid basically.Use is essentially mechanical process, reclaims by handling the salt slurry in a continuous manner.

To be incorporated into continuously from the slurry of crystallizer stage in the pre-thickened still, wherein or by mixing tank and/or by the air that under pressure, is blown into by it come the described slurry of mechanical stirring.Simultaneously, described slurry is continuously pumped into the curved surface screen cloth (curved screen) of pre-thickened device such as wet cyclone, static thickener or more liquid of removal or filtrate from described pre-thickened still.In described still, this filtrate from pre-thickened device is recycled in the pre-thickened still of baffle plate back, thereby in still, avoids any sizable disturbance of slurry.

Then will be in whizzer from the slurry feeding of pre-thickened device, more abundant multiviscosisty, described whizzer is removed nearly all residual liquid, produces the product of the liquid of about 98% salt and about 2%.

Preferred whizzer is the two-stage centrifugal machine, and it allows the water cleaning products to remove remaining hypochlorite from final product salt.To turn back to from the filtrate of the described whizzer first step in the pre-thickened still.

High density, the less salt SYNTHETIC OPTICAL WHITNER product produced by the inventive method are liquid, and pre-thickened still is overflowed on its top that is close to described pre-thickened still.Because it has with high density, less salt, overflows the substantially the same composition of SYNTHETIC OPTICAL WHITNER product of described pre-thickened still, so can add any mother liquor that overflows from the still of crystallizer stage to this high density, less salt, overflow the SYNTHETIC OPTICAL WHITNER product of described pre-thickened still.Separate by inserting point that inwall or baffle plate (for example will be incorporated into thereafter inwall or baffle plate from the recycled filtrate of pre-thickened device) will overflow in pre-thickened still and the slurry in the still, thereby prevention salt crystal is carried the liquid of overflow secretly.

The high density of producing by the inventive method, the SYNTHETIC OPTICAL WHITNER concentration of less salt SYNTHETIC OPTICAL WHITNER product by weight, greater than 25%.Can limit the concrete concentration of special SYNTHETIC OPTICAL WHITNER by resolution problem during the production process and sedimentary salt crystalline size, the concentration of especially working as SYNTHETIC OPTICAL WHITNER is near prescribing a time limit on it, and is all the more so, in fact, is limited to about 35% on this.

The description of drawings of the inventive method embodiment is described

Fig. 1 illustrative a kind of embodiment of above-mentioned disclosed surface cool crystallizer stage.

Fig. 2 illustrative a kind of embodiment of the processing after crystallizer stage.

With reference to the accompanying drawings, the explanation of the inventive method and equipment

Further specify and described above-mentioned disclosed the inventive method with reference to Fig. 1 and 2.Level shown in Figure 1 comprises surface cool crystallizer 10, and as mentioned above, this crystallizer comprises still 12, and heat exchanger 14 is coupled.This accompanying drawing does not show the aforesaid first step, but described the description of the drawings will be that the hypothesis that exists is carried out according to it, although be to be appreciated that the SYNTHETIC OPTICAL WHITNER (it is introduced in the crystallizer) that can make lower concentration by similar approach elsewhere, and with its shipment to be used in the crystallizer.Still 12 comprises cylindrical side wall 12A, conical lower wall 12B and upper wall 12C.In described still with any suitable mode support cylinder shape wall skirt baffle 16, thereby form outside annular Anding District territory 18 with sidewall 12A synergy, described stable zone is at bottom opening.Skirt baffle 16 is around inside center zone 20.

This crystallizer stage has the entrance and exit of a plurality of turnover stills 12.Recirculation outlet 22 is positioned at or near the lower central point of conical lower wall 12B.Slurry outlet 24 is positioned at any suitable position.Although accompanying drawing shows described position and is positioned at than on the low elevation in regional 18 bottoms that accurate position is not critical usually.Described outlet even can be positioned at cross the still wall or through pipe (this pipe threeway is connected to conduit 33), penetrate and extend to the pipe tail end of still inside.The top of mother liquor or products export 26 immediate area 18, but all be positioned at the elevation that is lower than skirt baffle 16 top.Draft outlet 28 is used to make the chlorine of any remnants and rare gas element to escape into standard commercial chlorine scrubber (specifically not showing).

Two inlets that lead to still 12 are chlorine inlet 30 and recirculation inlet 32.Recirculating pump 34 takes out liquid by outlet 22 and conduit 33 from the bottom of described still, and described conduit leads to the suction side of pump.Described pump arrives heat exchanger 14 by conduit 35 with liquid pumping, and described conduit is drawn from described pump outlet.Between pump 34 and heat exchanger 14, caustic alkali inlet by entering into conduit 35 36 adds fresh caustic to recirculation solution.By entering into the SYNTHETIC OPTICAL WHITNER inlet 38 of conduit 37, add SYNTHETIC OPTICAL WHITNER from present method first step, described conduit extends to recirculation inlet 32 from described heat exchanger 14.Although illustrated equipment shows described still and has an inlet (mixture of SYNTHETIC OPTICAL WHITNER, fresh caustic and recirculation solution is introduced by this inlet), but can use other pipe fitting equipment, thereby allow to introduce respectively, and meet the disturbance of avoiding stable zone at different positions.

As adding the suitable fill-in of fresh caustic and first step SYNTHETIC OPTICAL WHITNER,, the recirculation solution introducing is turned back in the still 12 by recirculation inlet 32 by control.The physical location that recirculation solution is incorporated in the solution in still is positioned at any suitable position, and described position is the tight turbulent flow of giving birth in annular region 18.Described accompanying drawing has shown the position in the interior region 20, preferred its is positioned at the central position on bottom, described zone slightly, wherein said recirculation solution is discharged by the vertical hopper 39 that diameter increases, thereby in described zone, promote the well distributed of recirculation solution, and in zone 18, do not produce turbulent flow.

To be transported to system of distribution 40 through the chlorine of inlet 30, the bottom of the next-door neighbour of described system interior region 20 and being set to directly upwards enters in the liquid in the zone 20 chlorine, thereby at first produces the addition reaction of same solution (described solution is introduced continuously by funnel 39) in zone 20.

Along with having, slurry (being produced by the caustic alkali successive reaction in chlorine and the still 12) makes the density of its maintenance towards the still bottom, and along with crystalline salt drops to downwards in the slurry, the mother liquor (it can or can be not take out from described still by exporting 26) that is arranged in stable regional top has with the present invention of said components and forms identical in fact composition.

Continuity method also relates to by via pump 25, described slurry is pumped, and by export 24 with its from described still, take out be used for according to Fig. 2 in aftertreatment.Although described accompanying drawing shows outlet 24 and is positioned at wall 12B that as mentioned above, described outlet can be positioned at any suitable position (comprising the threeway that is connected to conduit 33).

Speed by the chemical process rejected heat that takes place in crystallizer stage is the function by this crystallizer throughput (throughput).The result, with respect to recirculation rate and the cooling liqs speed of this crystallizer throughput control by described heat exchanger, thereby when described recirculation solution is passed through this heat exchanger, both having kept very little temperature in described recirculation solution falls, keep the temperature difference between described recirculation solution and the cooling liqs again, thereby be suitable for as mentioned above, the heat exchanger of employed specific type.In this article, present method has very high recirculation rate.

Fig. 2 has shown optional equipment, and it comprises pre-thickened still 44, and described pre-thickened still and still 12 are similar, because it has sidewall 44A, lower wall 44B and upper wall 44C.It also has interior panelling 46, and described baffle plate is created in external region 48 between himself and the sidewall 44A and the interior region 50 relative with himself.Baffle plate 46 needn't be full skirt baffle (full skirt).

To be incorporated into from the slurry of still 12 in the zone 50 by slurry inlet 52.For example by using air pressure in zone 50, to carry out the stirring of described slurry.By gas inlet 54 air under the pressure is provided in the system of distribution 56, the bottom of its contiguous interior region 50, and be set to described air is upwards entered in the slurry in the zone 50.Described air and the gas of carrying secretly are arbitrarily discharged by the draft outlet among the upper wall 44C on whole regional 50 58.Alternative or use mechanical stirrer in conjunction with air agitation.

Described slurry tends to fall to the bottom of still, wherein by recirculating pump 62, by slurry outlet 60 it is pumped.The slurry of pumping is transported to the inlet 64 of wet cyclone 66, described separator operation is to remove more liquid from described slurry, increase the concentration through solution the slurry of conduit 67 (from wet cyclone 66 to whizzer 68), described whizzer is used for by making the centrifugal crystalline salt that reclaims of slurry.

Preferred whizzer is the two-stage centrifugal machine, and it allows cleaning products after through the first centrifugal level, makes the product that is cleaned centrifugal in the second stage then.Water is a kind of examples of fluids that can be used for cleaning.Therefore, Fig. 2 has shown rinse water inlet 70 and rinse water outlet 72.Clean described product and can remove hypochlorite from final product salt, at solid outlet 74 places, described product salt is exported from whizzer.By conduit 75, return inlet 76 places first filtrate, will turn back to from the filtrate of whizzer 68 first step in the pre-thickened still 44, and, will return inlet 78 via second filtrate from the filtrate of wet cyclone 66 and return by conduit 69.The top of products export 80 immediate area 48.Basically has identical composition with liquid bleach product (its product) by exporting 80 liquid that take out for from still 12, taking out by outlet 26, this means that it has by weight, clorox greater than 25% and by weight, the salt less than 9.5% (sodium-chlor).The speed of Qu Chuing can be different separately.For example, exporting 80 speed certainly is approximately from the 4-6 that exports 26 speed doubly.Based on retention time, temperature and concentration, described speed can extensively change, as mentioned above, and by exporting 26 even can not have mother liquor to take out.

SYNTHETIC OPTICAL WHITNER product of the present invention will contain a certain amount of clorox.Described amount is the function of temperature of reaction to a certain extent.Usually, low reaction temperatures will cause low perchlorate concentration.The result is in order to make temperature of reaction lower, and is opposite with cooling tower water, and some principles of the inventive method are applicable to the factory that uses refrigerated water.On the other hand, the high density of the SYNTHETIC OPTICAL WHITNER product of producing by the inventive method allows it by adding the water dilution, and simultaneously, this must reduce the concentration of SYNTHETIC OPTICAL WHITNER, and it is also very effective in reducing the perchlorate concentration.

The alternative sodium hydroxide of potassium hydroxide, thus in a similar manner, produce the potassium hypochlorite of greater concn by the potassium hypochlorite of lower concentration.

Although (it has been made has by weight with reference to present method, greater than 15% clorox (NaOCl) and by weight, the liquid bleach product of 4.5% sodium hydroxide (NaOH)) the first step, even but make elsewhere, also can use the general principle of the present invention's (it considers the SYNTHETIC OPTICAL WHITNER of lower concentration, perhaps diluted concentrated bleach).But in factory, have the first step of such manufacturing SYNTHETIC OPTICAL WHITNER (described SYNTHETIC OPTICAL WHITNER is reacted in described crystallizer stage) really, need the temporary close second stage in order to safeguard or the like it, this does not also mean that and must close the described first step.SYNTHETIC OPTICAL WHITNER from the first step has suitable commercial grade, and it can dilute or not dilute, and its other place of exporting and be used for same factory from the second stage perhaps can be shipped to it factory at a distance.

Although illustrated and disclose the preferred embodiments of the invention, be appreciated that the principle of the invention is applicable to that all fall into the embodiment in the following claim scope.

Claims (38)

1. one kind is used for making the method for high density, less salt, moisture sodium hypochlorite bleaching agent continuously by the moisture sodium hypochlorite bleaching agent of low concentration, the moisture sodium hypochlorite bleaching agent of described low concentration has some sodium hydroxide and is substantially free of sodium chloride crystal, and described method comprises:

In still, make

1) the moisture sodium hypochlorite bleaching agent of low concentration, it has some sodium hydroxide and is substantially free of the salt crystal,

2) aqueous sodium hydroxide solution, it has by weight, 45%～51% concentration,

3) chlorine in gas phase and/or the liquid phase, it can contain or can not contain inert fraction

Successive reaction, thus a kind of solution produced, and described solution has

A) precipitation zone, the salt crystal is precipitated out in solution in this zone, thereby and landing downwards form slurry, with some slurry take out, cooling and then be incorporated into precipitation zone then, and

B) the not crystalliferous mother liquor zone on this precipitation zone, it is made up of not crystalliferous mother liquor basically, and the weight percent of the clorox of this mother liquor is greater than weight percent that reacted, low concentration, moisture sodium hypochlorite bleaching agent.

2. the method for claim 1, wherein in still, carry out described reaction with outlet and inlet, in this exit, slurry is taken out from the bottom of precipitation zone, described inlet is arranged on the elevation place higher than described outlet, in described ingress, after cooling, the slurry that takes out is incorporated into again the top of precipitation zone.

3. method as claimed in claim 2, wherein the cooling of the slurry that is taken out comprises and makes described slurry flow over-heat-exchanger.

4. method as claimed in claim 3, wherein said heat exchanger are used for heat is delivered to the liquid coolant that flows through described heat exchanger from the slurry that is taken out.

5. method as claimed in claim 4 wherein will flow through the liquid coolant of pipeline and flow through the scope that the temperature difference between the slurry of described heat exchanger housing is controlled at 5～15.

6. method as claimed in claim 4 wherein will flow through the liquid coolant of pipeline and flow through the scope that the temperature difference between the slurry of described heat exchanger housing is controlled at 2～3.

7. method as claimed in claim 3 wherein is provided by the cooling that is provided by described heat exchanger, thereby the temperature that causes flowing through the slurry of described heat exchanger reduces by 1 °F～4 °F.

8. method as claimed in claim 3 is wherein controlled the temperature of described slurry, thereby allows to use the slurry of cooling tower water cooling taking-up, and described heat exchanger is used for heat is delivered to the cooling tower water that flows through described heat exchanger from the slurry that is taken out.

9. method as claimed in claim 3, wherein said heat exchanger are used for heat is delivered to the refrigerated water that flows through described heat exchanger from the slurry that is taken out.

10. method as claimed in claim 2, wherein said still comprises the inner cylindrical wall skirt baffle, it is with the cylindrical wall synergy of described still, thereby form the stable zone of annular, described stable zone in the bottom to described precipitation zone opening, and extend up to open upper end, define the side in (bounding) described mother liquor zone.

11. method as claimed in claim 10 wherein by adding the fresh reactant agent continuously, causes described mother liquor to overflow continuously from described still by outlet.

12. the method for claim 1, wherein in the crystallizer still, carry out described reaction, thereby from described crystallizer still, take out described slurry and further the processing with its multiviscosisty, also further handle the slurry of institute's multiviscosisty, thereby remove all liquid basically, thereby stay the salt crystal that is substantially free of liquid.

13. method as claimed in claim 12, wherein further handle slurry comprises that processing is taken out from described crystallizer still slurry, thus it is pre-thickened, then mechanical treatment pre-thickened slurry, thereby remove all liquid basically, thereby stay the salt crystal that is substantially free of liquid.

14. method as claimed in claim 13 wherein will be incorporated in the described pre-thickened process by the filtrate that pre-thickened described slurry produces again.

15. method as claimed in claim 14 is wherein carried out the pre-thickened process of part in pre-thickened still, and will be incorporated in the described pre-thickened still by the filtrate that pre-thickened described slurry produces again.

16. method as claimed in claim 15, wherein adding continuously causes the liquid levels in the described pre-thickened still to increase to such elevation from the fresh slurry in the described crystallizer still, at described elevation place, have with described crystallizer still in the liquid of the substantially the same composition of mother liquor overflow described pre-thickened still.

17. method as claimed in claim 16 comprises that the mother liquor that makes from the stable zone of described crystallizer still overflows, and make overflow described crystallizer still mother liquor with the liquid mixing of overflowing described pre-thickened still together.

18. method as claimed in claim 16, wherein limit the elevation that liquid overflows described pre-thickened still by bringing on the baffle plate in the pre-thickened still, described baffle plate is set, thereby stops the remarkable slurry that destroys in the pre-thickened still of the filtrate that is incorporated into again in the described pre-thickened still.

19. method as claimed in claim 13, wherein the mechanical treatment of pre-thickened slurry comprises centrifugally, and it is separated into described slurry salt crystal and the liquid that is substantially free of liquid.

20. method as claimed in claim 19, wherein said centrifugal comprise first and second grades centrifugal, after the first step is centrifugal, thereby the product that cleans centrifugation is removed remaining clorox.

21. the method for claim 1, wherein have some sodium hydroxide, low concentration, moisture sodium hypochlorite bleaching agent comprise by weight, at least 15% clorox, and by weight, 4.5% sodium hydroxide.

22. method as claimed in claim 21 is wherein by making

1) a kind of aqueous solution, it contains clorox, excessive slightly sodium hydroxide, and it is substantially free of sodium chloride crystal,

2) a kind of aqueous solution, it contains by weight, and concentration is basically greater than 24% sodium hydroxide, and

3) chlorine in gas phase and/or the liquid phase, it can contain or can not contain inert fraction

Reaction is made and is contained by weight, at least 15% clorox, and by weight, the aqueous product of 4.5% sodium hydroxide.

23. the method for claim 1, wherein said not crystalliferous mother liquor has by weight, the clorox greater than 25%, and by weight less than 9.5% salt, and have excessive sodium hydrate slightly.

24. method as claimed in claim 3 wherein is provided by the cooling that is provided by described heat exchanger, thereby the temperature that causes flowing through the slurry of described heat exchanger reduces by 1 °F～2 °F.

25. the method manufacturing by claim 23, be substantially free of the crystalline mother liquor.

26. the method manufacturing by claim 1, be substantially free of the crystalline mother liquor.

27. a high density, less salt SYNTHETIC OPTICAL WHITNER product, it comprises the aqueous solution, the described aqueous solution has by weight, clorox greater than 25%, and excessive slightly sodium hydroxide, and based on weight %, when the clorox of 25 weight %, the ratio of NaCl and NaOCl (clorox) is lower than 0.38, and increases to 25% when above when the per-cent of clorox, and described ratio reduces.

28. SYNTHETIC OPTICAL WHITNER product as claimed in claim 27, wherein after removing solid, described product has by weight, 30% clorox, and the ratio of NaCl/NaOCl is 0.21～0.25, and have excessive slightly caustic alkali.

29. be used to make the equipment of high density, less salt, moisture sodium hypochlorite bleaching agent, it comprises:

Reactor will

1) water-containing product, it contains by weight, at least 15% clorox, by weight, the sodium hydroxide of 4.5 %, and be substantially free of the salt crystal,

2) aqueous NaOH, it has by weight, 45%～51% concentration, and

3) chlorine in gas phase and/or the liquid phase, it can contain or can not contain inert fraction,

Be incorporated into described still and reaction,

Thereby produce a kind of like this solution, it has a) lower region, wherein the salt crystal is precipitated out in solution, and thereby landing forms slurry downwards, with some slurry take out, cooling and then be incorporated into the wherein lower region of deposited salt then, and b) be substantially free of the upper area of crystalline mother liquor, this mother liquor has by weight, clorox greater than 25% and by weight is lower than 9.5% salt;

The inlet that described still has outlet and is provided with highlyer than this outlet, slurry takes out from lower region in this exit, and the slurry of taking-up is incorporated in the lower region in this ingress again;

Be connected the heat exchanger between the entrance and exit, to be used for that heat is delivered to the liquid coolant that flows through this heat exchanger from the slurry that takes out; And

The inner cylindrical wall skirt baffle, the cylindrical wall synergy of itself and this still, thus forming the stable zone of annular, this zone is at bottom opening and extend upward, thereby is defined for the inner boundary that enters upper area.

30. equipment as claimed in claim 29, it comprises another outlet, and mother liquor overflows from upper area by this outlet, and it is arranged on the elevation place that is lower than the skirt baffle upper end.

31. equipment as claimed in claim 29, it comprises pre-thickened still and mechanical means, be incorporated into the slurry from reactor in this pre-thickened still and further processing, thereby it is it is pre-thickened, described mechanical means is used to handle pre-thickened slurry, removing all liquid basically, thereby stay the salt crystal that is substantially free of liquid.

32. equipment as claimed in claim 31, it comprises the loop that turns back to pre-thickened still from mechanical means, to be used for and will to be incorporated into pre-thickened still again by the filtrate of using this mechanical means to produce.

33. equipment as claimed in claim 32, wherein said pre-thickened still has outlet at the elevation place, and at this elevation place, the essentially identical liquid of mother liquor in composition and the reactor can overflow described pre-thickened still.

34. equipment as claimed in claim 33, it comprises outlet in reactor, by this outlet, overflow in the mother liquor autoreaction still, and subsequently with described mother liquor with the liquid mixing of overflowing by the outlet of described pre-thickened still together.

35. equipment as claimed in claim 33, wherein limit the outlet elevation that described liquid overflows from described pre-thickened still by bringing on the baffle plate in the pre-thickened still, and described baffle plate is set, thereby stops the remarkable slurry that destroys in the described pre-thickened still of the described filtrate that is incorporated into again in the described pre-thickened still.

36. equipment as claimed in claim 31, wherein said mechanical means comprises the two-stage centrifugal machine, and it is provided with cleaning between two levels.

37. method that is used for making continuously high density, less salt, moisture hypochlorite bleaching by the moisture hypochlorite bleaching of low concentration, the moisture hypochlorite bleaching of described low concentration has some oxyhydroxide and is substantially free of the muriate crystal, and described method comprises:

In still, make

1) the moisture hypochlorite bleaching of low concentration, it has some oxyhydroxide and is substantially free of the salt crystal,

2) hydroxide aqueous solution,

3) chlorine in gas phase and/or the liquid phase, it can contain or can not contain inert fraction

Successive reaction, thus solution produced, and described solution has

A) precipitation zone, wherein the salt crystal is precipitated out in solution, thereby and landing downwards form slurry, with some slurry take out, cooling and then be incorporated into precipitation zone then, and

B) the not crystalliferous mother liquor zone on this precipitation zone, it is made up of not crystalliferous mother liquor basically, the weight percent of the hypochlorite of this mother liquor greater than reacted, the weight percent of low concentration, moisture hypochlorite bleaching.

38. be used to make the equipment of high density, less salt, moisture hypochlorite bleaching, it comprises:

Reactor will

1) water-containing product, it contains hypochlorite and oxyhydroxide, and is substantially free of salt crystal, 2) aqueous hydroxide, and

3) chlorine in gas phase and/or the liquid phase, it can contain or can not contain inert fraction,

Be incorporated into described still and reaction,

Thereby produce following solution like this, described solution has a) lower region, wherein the salt crystal is precipitated out in solution, and thereby landing forms slurry downwards, with some slurry take out, cooling and then be incorporated into the wherein lower region of deposited salt then, and b) be substantially free of the upper area of crystalline mother liquor;

The inlet that described still has outlet and is provided with highlyer than this outlet, slurry takes out from lower region in this exit, and the slurry of taking-up is incorporated in the lower region in this ingress again;

Be connected the heat exchanger between the entrance and exit, to be used for that heat is delivered to the liquid coolant that flows through this heat exchanger from the slurry that takes out; And

The inner cylindrical wall skirt baffle, the cylindrical wall synergy of itself and this still, thus forming the stable zone of annular, this zone is at bottom opening and extend upward, thereby is defined for the inner boundary that enters upper area.

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