CN100518919C

CN100518919C - Water catalytic decarbonation appliance

Info

Publication number: CN100518919C
Application number: CNB2005800281061A
Authority: CN
Inventors: C·巴拉克
Original assignee: DEGEMONT
Current assignee: DEGEMONT
Priority date: 2004-08-19
Filing date: 2005-08-08
Publication date: 2009-07-29
Anticipated expiration: 2025-08-08
Also published as: TWI373455B; CN101006019A; FR2874375A1; TW200607767A

Abstract

The invention aims at enabling, in a catalytic decarbonation apparatus, inert particles coated with calcium carbonate to be constantly and systematically extracted from the reactor, with no risk of clogging the discharge pipes. Therefor, said pipes (7'a, 7'b) have an inside diameter ranging between 40 and 60 mm and they have a downward incline up to their connection to an outside discharge conduit (8'), except, possibly, a horizontal portion starting from the orifice through which they emerge into the reactor (1').

Description

Water catalytic decarbonation appliance

Technical field

The present invention relates to the decarburization (d é carbonatation) of water.Theme of the present invention is more specifically to improvement of so-called " catalytic decarbonation " equipment and uses thereof.

Background technology

Basic decarburizing reaction

Known natural water comprises the mineral matter that heavily has the dissolving of alterable height ratio greatly.Some mineral matters wherein are present in various types of water with sizable concentration usually, and other mineral matter then only exists with the form of trace.The present invention only relates to first kind of mineral matter.

These dissolved substances comprise:

-anion: carbonate and bicarbonate radical, sulfate radical, chlorine root and nitrate anion, silica;

-and cation: calcium, magnesium and alkali metal (mainly being sodium).

In order to meet normal usage, hereinafter, ion will be mentioned with their form of salt, but should not forget that in fact under the common concentration of natural water, the salt of dissolving is dissociated into HCO fully ₃ ^-Or CO ₃ ^2-, SO ₄ ^2-Or Cl ^-Anion and Ca ²⁺, Mg ²⁺, Na ⁺Therefore Deng cation, and highly simplifiedly with they any reorganization, for example recombinate by systematically sodium and chlorine root being made up or calcium and bicarbonate radical being made up.In fact, according to the Berthollet law, have only when cation and anion during with insoluble form precipitation, cation just combines with anion.

When desalt reaction beginning, they are free fully, and only are in order to meet conventional custom, just adopt molecular forms rather than ionic species to write these reactions.

Look back these reactions well known in the art below.

Lime is to the effect of calcium bicarbonate

1) only comprises the situation of the water of calcium salt

Be the fundamental reaction of applied decarburization in this case, it is based on the big poor solubility between calcium bicarbonate and the carbon neutral hydrochlorate:

CaCO ₃Solubility with and with free CO ₂Or " half hitch closes " CO ₂Balance become the theme of numerous studies.The various researchs of quoting among M é mentoTechnique de 1 ' the Eau Degr é mont by the Cinquantenaire publication in 1988 define water and CaCO ₃The equilibrium condition of precipitation.The variation of the solubility of calcium carbonate with many factors instructed in the research of Pourbaix, and when the dosage of used lime is stoichiometry just, the then measurable theoretical amount that remains the calcium carbonate of dissolving.This amount is usually corresponding to 0.2-0.3 milliequivalent TA/ liter (TA: bicarbonate content; See below) value, but seldom reach this value in practice.

What be typically expressed as the water permanent hardness remains the form of solution natively with reinforcing yin essence ion sulfate radical, chlorine root and the corresponding calcium of nitrate anion, under the common concentration of unboiled water, lime can not with these various reactant salts.

If in the consideration treated water in solution remaining basicity, under the situation of pure calcareous unboiled water, can be contemplated to three kinds of situations:

1. the quantity not sufficient of lime: a part of calcium bicarbonate remains the form of solution, thereby Ca is (HCO ₃) ₂And CaCO ₃(being in the latter's solubility limit) is present in the water simultaneously.

2. dosage is correct: only keep CaCO ₃Part soluble in water.

3. lime is excessive: excessive free lime and the calcium carbonate coexistence that is in solubility limit.

The basicity titration that should be mentioned that water comprises two kinds of measuring methods:

-permanent alkalinity (P-basicity) or PA, it obtains by the analysis that utilizes the diluted acid volumetric soiutions, the phenolphthalein of variable color when color change indicator is pH=8.2/8.3;

-total alkalinity (M-basicity) or TA, it defines by the analysis that utilizes same solution, but utilizes the change color of methyl orange indicator when pH=3.5/4.5.

The situation that comprises the water of calcium and magnesium:

This situation runs into usually, and lime-secreting water makes an exception.

In this case, water is then by characterizing with undefined content (concentration):

-TH (total hardness)=C.Ca+C.Mg (calcium content+content of magnesium),

-TA=bicarbonate content (temporary hardness of water).

The difference of TH-TA represents because reinforcing yin essence ion (SO ₄ ^2-+ Cl ^-+ NO ₃ ^2-) the total hardness (permanent hardness of water) that causes of salt.

In this case, lime causes CaCO ₃Formation, up to the calcium of TA part purifying fully, this part is reduced to CaCO under cool condition ₃Solubility.

Water comprises the summation of C.Mg and C.Ca so, and described C.Ca equals the milliequivalent that initial C.Ca deducts the TA that precipitates with the carbonate state.

If add excessive lime, then cause following secondary reaction:

" ou " expression " perhaps " in following formula.

Insoluble magnesia precipitates, and calcium becomes the form of solution, and it substitutes magnesium fully and simply.

Except the exception of water with very high Se content, it is solvable that this calcium keeps, and the solubility of calcium sulfate in cold water is about 2g/l, and this value is much larger than the value that is obtained by above-mentioned reaction (2).

In fact, this interpolation can not change total TH of purified water; Because the solubility of magnesia in water (be about 0.1 milliequivalent/liter), PA and TA slightly increase, and keep substantial constant, need only magnesia and not exclusively precipitate.When best purifying, small-amount free magnesia will be present in the water, make PA bigger slightly than TA/2.

NaOH is to the effect of calcium bicarbonate

This method is the above-mentioned variant that utilizes the method that lime handles, when the expectation decarburization with make the water softening of processing, perhaps when use caustic soda, from logic or economically, all the method than lime is more favourable for it.

1. in the first step, following reaction (3) takes place:

2. if after this precipitation, also have enough calcium ions that combines with sulfate radical or chlorine root, following reaction just take place:

This reaction is for example as follows:

The NaOH role resembles 2NaOH replacement 1Ca (OH) so ₂And 1NaCO ₃, but this is only just like this when unboiled water comprises the enough calcium (permanent hardness) that is attached to sulfate radical or chlorine root, thus calcium is by Na ₂CO ₃In sodium exchange.

Have only all Na that produce when reaction (3) ₂CO ₃Combine with enough calcium so that calcium with CaCO ₃In form when precipitation, that is to say, when the calcium content C.Ca of unboiled water is equal to or greater than 2TA, TA can be reduced to less than 0.6 milliequivalent/liter.

If C.Ca is less than 2TA, and if the dosage of NaOH calculate then excessive free Na according to this TA ₂CO ₃To stay in the water, this will make the PA of water and TA increase along with (2TA-C.Ca) value of unboiled water and become bigger.

But, be acceptable (for example in the processing of drinking water) if certain density bicarbonate is stayed in the water, then this method remains favourable, but the dosage of NaOH must be reduced to the chemical dose equivalent of C.Ca/2 then.

In a word, can reduce the total hardness of water by using caustic soda, and without any risk, and purifying is with the same complete with lime; The reduction of this TH will equal the twice that bicarbonate content reduces, and condition is that the NaOH dosage of adding is no more than half of unboiled water calcium content.

Then the same low during the lime of PA and TA and the suitable dosage of use.

But should be pointed out that if unboiled water comprises free carbonic acid then the calculating of NaOH dosage must be revised, this can cause because the additive decrementation of the NaOH that following reaction caused:

The device that adopts

The feature of obtainable device is the speed of water treatment in this area, and this speed is represented in the following manner: 1 meter/hour speed is corresponding to every square meter of reactor surface area and per hour handle 1 cubic metre water, i.e. 1m ³/ m ²/ h.

In by the field of precipitation decarburization, used or used three class devices:

-" slowly " reactor (for example, conventional clarifier, it is transformed into provides decarbonizing tower, and comprises only mixing chamber, then is the space that is used for sedimentation); The feature of these reactors is low-down flowing velocity (and therefore needing big space), the time of staying by the very slow dynamics of precipitation of calcium carbonate set (only with lime or NaOH when finishing in 20-30 hour after water to be processed mixes, just reach the sedimentation equilibrium under the environment temperature).As indication, the possible processing speed of this reactor is approximately several centimetres/hours, to avoid any risk of a large amount of foulings of downstream filter.

-mud recirculation reactor, the part of the calcium carbonate mud that produces in the decarburizing reaction process is reinjected in this reactor in the upstream of reactor, and this can cause " inoculation " of water to be processed, and kinetics has greatly been quickened in this operation; This be because, in this case, can think decarburizing reaction with time of contact a few minutes (2-3 minute normally enough) of mud in reach its balance.These reactors comprise two very different zones: one has the volume of restriction and the unusual condition of turbulence, and the contact of water+reactant to be processed (lime or NaOH) can be provided, and another provides the separation of water/mud and thereby makes clarification of water.In this case, processing speed significantly improves, and depends on that device comprises or does not comprise the stratiform piece-rate system, and this processing speed is several meters/hours to tens meters/hour.

-be " catalysis " decarbonizing tower at last, this is the particular case of previous reaction device, wherein use the inert mineral plastid of sand or another kind of particle form, it is used for inoculating in reactor, sand grains becomes and is covered by calcium carbonate gradually, and play the effect of crystal seed subsequently, this can quicken (or " catalysis ") decarburizing reaction.It is very compact that these decanters are compared with said apparatus, because they in fact only are included in described conversion zone under the mud recirculation reactor situation; Processing speed in this device can reach 70 meters/hour, at the best of times even reach 100 meters/hour.The character that reaches this speed has limited the situation that this class reactor is applied to " the heavy mud " used fully by the sand that calcium carbonate covers, but has got rid of the water clarification that comprises " gently " sediment such as magnesium hydroxide or organic-flocculation thing fully.

The decarbonization device of " catalysis " type

Be systematically to use big crystal seed with the basic difference of above-mentioned mud EGR.And in the Sludge Bed of aforementioned means, single crystal is of a size of about 1/100mm, and the crystal grain of catalytic decarbonation tower (also being known as the particle reactor) is generally 0.2-1mm, and can reach several millimeters sometimes.

This result who causes is, they flock together with the form of condensation product easily, and the upwards diafiltration of unboiled water in cone-shaped apparatus makes it possible to obtain reaction and sedimentary appropriate separation the completely, and the size of equipment greatly reduces and has a very high rate of climb.

Reactant and water at full speed join in the reactor simultaneously, thereby cause the motion of the crystal grain that is positioned at bottom of device, and prevent their cakings.

But these crystal grain have the trend of indeterminate growth, and this is owing to always at first contacting unboiled water by identical crystal grain and reactant causes, therefore must systematically removing them and periodically introduce fine grain again.

This system has two specific advantages, i.e. its low floor space and the therefore possibility of this device of use under pressure.Therefore can when decarburization, handle pressure (hydraulic) water, and its filter by sealing is turned back in the loop.

And, the very thin carbonate mud (crystal grain of 10-30 micron) that takes out from the mud recirculating system is replaced by the bead of diameter by about 1-2mm herein, this bead is very rapidly discharged, and it can be transported to burying of permission with not carrying out extra process and fill out the field, perhaps scheme as an alternative can be reused as ballast aggregate, the basic road that is used for the road stabilisation, adrainage material etc.

On the other hand, this technique table reveals some shortcoming, and wherein most important shortcoming is as follows:

Since when the calcium carbonate undue growth total reaction table area become inadequately, and reaction becomes not exclusively, so be coated with the change in size of the sand grains of calcium carbonate outside must carefully monitoring.

2. this device is operated under the situation greater than the water of TH-TA at water that is rich in organic colloid and content of magnesium.Particularly, the back one situation under, magnesia precipitates, this magnesia not with CaCO ₃Cocrystallization, and hinder rapid subsidence, and do not have this rapid subsidence, system just can not use.

Since when flow velocity slows down material bodies stop fluidisation and observe the formation of privileged way that (this is reflected as the water of discharging the difference quality, even be reflected as crystal caking), so this device only can be operated in the flow rates that is rather narrow (being generally the variation of one times difference).

Obviously be easy to be overcome with heading 2 and the shortcoming mentioned for 3 times, because they relate to the problem that requires relevant good knowledge with the characteristic of water to be processed and operator's water.All these aspects can and should be by clear and definite in the planning set-up procedure of equipment.

On the other hand, the problem of being brought by the growth of precipitation seed control then needs regularly to monitor caltalyst, and need be designed for the system of " macrobead " of removing the sand that the outside is coated with calcium carbonate effectively, and checks minimizing of operation and maintenance.

The present invention relates to back one problem particularly, and in order to optimize size and to stipulate the purposes of these " catalysis " type decarbonization systems, and applicant company has carried out many dynamics research and to the various tests of industrial equipment.

Summary of the invention

The objective of the invention is to make it possible in catalytic decarbonation appliance, regularly and systematically to remove the sand grains that be coated with calcium carbonate of size greater than the 1.2mm hydraulic diameter.

In the prior art, carry out this removing by flexible pipe, the upper surface flush of these flexible pipes and reactor base plate, and it is equidistant each other, and be connected to the outside drain pipeline, this outside drain pipeline is that it is process below comprising the base plate of nozzle towards the path of device outside, and this nozzle is used to pass the wall of device and supplies unboiled water to reactor.This structure is proved to be and is not suitable for guaranteeing discharging regularly and effectively " macrobead " and only carries secretly minimum than beads simultaneously.

This be because, the flexible pipe that is used for removing these macrobeads that are capped does not occupy the fixed position that is limited with respect to the reactor base plate, like this, although have general directional inclination on the direction of their outside drain pipelines below being positioned at base plate, but they can comprise the part that some is bent upwards partly, this makes the bead of discharging may deposit and accumulate in its underpart, and the result is involved local at least in part obstruction of pipe.

FR 2 426 042 A disclose and have been used for removing phosphatic reactor from water, in this reactor, add at least a reactant in water, this reactant can form the very crystal salt of low solubility, and the gained mixture is contacted with the crystal seed that is used to cause crystallization.This operating of contacts occurs in the fluid bed of the material crystal grain that constitutes crystal seed, and adds one or more reactants, thereby carries out heterogeneous nucleation effect completely basically on the crystal grain of this fluid bed.These crystal grain can be the crystal grain of crossing filter sand of calcining and washing.

This reactant comprises alkaline solution, and it must comprise a kind of or preferably several in the following ion:

-hydroxide ion;

-fluorine radical ion;

-calcium ion.

React very rapid, very high level removed phosphate in a few minutes, and form the insoluble crystalline compounds of calcium and phosphate radical, this compound is deposited on the sand grains.

But, FR 2 426 042 A do not provide the information that is coated with the risk of crystalline phosphate sand grains obstruction about discharge pipe line by the outside, and it points out (the 9th page of 17-19 is capable), can select to be used to implement the condition of this method, so that fully get rid of the formation of calcium carbonate basically.

The present invention relates to the reactor of this identical general type, but it is applied to comprise the catalytic decarbonation of water of the calcium bicarbonate of dissolving, and its purpose more specifically is to eliminate or limit at least the risk that the delivery pipe of this reactor is stopped up as the sand grains that is coated with calcium carbonate by inert particle.

For this reason, theme of the present invention is the equipment of catalytic decarbonation of water that is used to comprise the calcium bicarbonate of dissolving, this equipment comprises reactor, this reactor comprises the inner bottom plating of horizontal placement in its underpart, be used for providing to this reactor the device of pressure (hydraulic) water and decarburizing reaction thing at the upper surface of this base plate, the bed of inert solid particle such as sand, it is placed on the top of base plate in the reactor, thereby make pressure (hydraulic) water and reactant be upward through it from the bottom, the device that is used for the water that emission treatment crosses at least one of reactor top, and the discharge pipe line that is coated with the inert particle of calcium carbonate, the water that this diameter that is coated with the inert particle of calcium carbonate equals preliminary dimension and origin autoreactor is at least carried secretly, the aperture that these pipelines flush by the inner face with base plate or sidewall, basically on the level of base plate, lead in the reactor, and be connected to the external drain that is positioned at the level place lower than base plate

This equipment is characterised in that, the discharge pipe line of the particle that is capped is a rigid line, its internal diameter is 40-60mm, be preferably 45-55mm, and in order to guarantee regular pm emission and do not stop up the risk of these pipelines that these pipelines have continual downward gradient, be connected with external drain up to it, exceptionally, randomly be the horizontal component that begins from the aperture, they lead in the reactor by this aperture.

The key parameter of the discharge pipe line of reactor is the internal diameter of these pipelines, because equal the inert particle that is coated with calcium carbonate of 1.2mm at least for hydraulic diameter, rigid line should preferably have the diameter of 40-60mm, more preferably 45-55mm.

This is because the test that applicant company carries out shows, pipeline than minor diameter be reflected as the rigidity fairlead repeat stop up, and owing to follow current to be coated with the underspeed of these particles clearly, bigger diameter causes the deposition of the largest particles in the pipe, this speed is necessary for 1.8-3m/s, preferred 2-2.5m/s.

As mentioned above, the discharge pipe line that is coated with the particle of calcium carbonate can have horizontal upstream portion, but they must then have continual gradient, until till the exterior tubing that these pipelines are connected to, this exterior tubing constitutes manifold.For the ease of the transmission of particle, can be to the removing water outside this manifold amount supplied.

Preferably, these discharge pipe lines lead in the reactor by the aperture that flushes with base plate, discharge large-sized particle by this position.

The sweep of these pipelines preferably has three times the larger radius of curvature that equals their diameters at least.

To stop up in order can under the situation of outdated obstruction, under high pressure eliminating, even to clean, quick coupled arm can advantageously be provided on each pipeline for adverse current.

Randomly, can be provided for controlling the automatic system of discharging that diameter equals the inert particle that is coated with calcium carbonate of predetermined value at least, this system is that index calculates according to the real-time time of staying of water in reactor of handling.

Should be pointed out that as required used decarburizing reaction thing can be lime Ca (OH) ₂Or NaOH NaOH.

Can optimize the removing of the largest particles that is coated with calcium carbonate by using these different characteristics, simultaneously the volume of following water that extracts from reactor is minimized, and can remove with respect to the more bulky grain of all material body that discharges in each reset procedure with about 20% factor.This is that the 70-85% in the particle of removing is " macrobead " because have been found that the equipment of the application of the invention, and according to prior art, this percentage is no more than 35-45%.

Description of drawings

Below with reference to description of drawings the preferred embodiments of the invention, wherein:

Fig. 1 is the vertical cross-section diagram of prior art equipment;

Fig. 2 is the similar cross-section figure of present device.

At first with reference to figure 1, its expression vertical and cylindrical reactor 1 is supplied to be processed pressure (hydraulic) water by pipeline 2 to this reactor in its underpart, and this pressure (hydraulic) water comprises the calcium bicarbonate of dissolving.Pipeline 2 leads in the reactor 1 below the base plate 3 of horizontal positioned, and water spreads in the reactor by the nozzle 4 that is evenly distributed on base plate 3 upper surfaces under pressure.

Pipeline 9 can be incorporated into decarburizing reaction thing (lime or NaOH) in the reactor.

Pressure (hydraulic) water to be processed is upward through the casting bed 5 that is positioned at base plate 3 tops from the bottom, and treated water is discharged by overflowing in one or more external slots 6 on the top of reactor.

When contacting with the decarburizing reaction thing, the calcium bicarbonate that exists in the water to be processed reacts, and is converted into calcium carbonate CaCO ₃, this tosca is on sand grains, and sand grains constitutes abundant crystalline seed, but this reaction takes place in the bottom of bed 5 basically, is rich in calcium bicarbonate and decarburizing reaction thing more at this place's water.

Such result is, the sand grains that is deposited on bed 5 bottoms has the trend of the particle that is coated with calcium carbonate much bigger in the top that forms than bed, therefore must periodically or remove the particle that meets or exceeds in these particles more than or equal to the hydraulic diameter of predetermined value (being typically about 1.2mm) continuously.

For this reason, according to routine techniques, be provided for discharging these oarse-grained flexible pipes 7, this pipe leads to the upper surface of base plate by the aperture, this aperture and this flush, and these pipes are connected to the manifold 8 that is positioned at the level place lower than bottom 1, and wherein bulky grain is entrained with by the current of following that are derived from reactor.

But these flexible pipes 7 do not occupy the fixed position with respect to base plate, so they in use have the trend that is shifted or is twisted.And they are continuous downward-sloping gradient on the direction of manifold 8 not, so these manage the risk height that 7 bulky grains that taken out stop up from reactor.As shown in Figure 2, reactor of the present invention makes this risk minimization.

In this Fig. 2, the element of having described with reference to Fig. 1 or have similar functions is put in marks with identical label ' expression.

In this embodiment of the present invention, rigid line 7 ' aThe flexible delivery pipe 7 that has replaced prior art, this pipeline 7 ' aOccupy fixed position with respect to base plate 3 ', and downward-sloping continuously according to uninterrupted downward gradient on the direction of manifold 8, thus eliminate or minimize the risk that these pipelines stop up.

Do not depart from scope of the present invention, the rigidity discharge pipe line also can lead in the reactor at place, the bottom of sidewall of reactor, and can comprise the upstream portion of level, its be located substantially on steering reaction device inside base plate face the level place (among Fig. 2 by dotted line with 7 ' bThe situation of the pipeline of expression).

This pipeline has specific diameter, and for example 50mm, and their sweep preferably has the larger radius of curvature that equals to manage three times of diameters at least, and for the diameter of 50mm, this radius of curvature is about 15cm.

Under these conditions, (this speed is 1.8-3m/s under by the appropriate speed of following the particle of water removing in these pipelines of taking out from reactor, preferred 2-2.5m/s), the obstruction risk of pipeline 7 ' reduces greatly, and as mentioned above, the not only required volume of following water minimizes, and can remove the big sand grains that is coated with calcium carbonate than the much higher percentage of prior art.

Claims

1. be used to comprise the catalytic decarbonation appliance of water of the calcium bicarbonate of dissolving, this equipment comprises reactor (1 '), this reactor comprises base plate (3 ') in its underpart, at least be used for providing to this reactor the pipeline (2 ') of pressure (hydraulic) water at the upper surface of this base plate, nozzle (4 ') and the device (9 ') of decarburizing reaction thing is provided, the bed (5 ') of inert solid particle, it is placed on the top of base plate (3 ') in the reactor (1 '), thereby make pressure (hydraulic) water and reactant be upward through it from the bottom, be used for the device (6 ') of the water that emission treatment crosses and the discharge pipe line (7 ' that is coated with the inert particle of calcium carbonate at least one of reactor (1 ') top a, 7 ' b), the water that this diameter that is coated with the inert particle of calcium carbonate equals preliminary dimension and origin autoreactor is at least carried secretly, these pipelines (7 ' a, 7 ' b) by the aperture that the inner face with base plate or sidewall flushes, on the level of base plate (3 '), lead in the reactor basically, and be connected to the external drain (8 ') that is positioned at the level place lower than base plate,

This equipment is characterised in that, the discharge pipe line (7 ' of the particle that is capped a, 7 ' b) be rigid line, its internal diameter is 40-60mm, and for the risk that guarantees regular pm emission and do not have to stop up, these pipelines have continual downward gradient, be connected with external drain (8 ') up to it, the exception part is the horizontal component that begins from the aperture chosen wantonly, and they lead in the reactor (1 ') by this aperture.

2. equipment as claimed in claim 1 is characterized in that, described inert solid particle is a sand.

3. equipment as claimed in claim 1 is characterized in that, described internal diameter is 45-55mm.

4. as the described equipment of one of claim 1-3, it is characterized in that pipeline (7 ' a, 7 ' b) sweep have three times the radius of curvature that equals pipeline diameter at least.

5. as the purposes of the described equipment of one of claim 1 to 4, be used to comprise the catalytic decarbonation of water of the calcium bicarbonate of dissolving, wherein equal the inert particle that is coated with calcium carbonate of 1.2mm at least from reactor (1 ') discharging hydraulic diameter.

6. purposes as claimed in claim 5 is characterized in that, at pipeline (7 ' a, 7 ' b) in, be 1.8-3m/s by the speed of following current to remove the particle that is coated with calcium carbonate.

7. purposes as claimed in claim 6 is characterized in that, described speed is 2-2.5m/s.

8. as the described purposes of one of claim 5 to 7, it is characterized in that the decarburizing reaction thing comprises lime or NaOH.