CN101006019A

CN101006019A - Water catalytic decarbonation appliance

Info

Publication number: CN101006019A
Application number: CNA2005800281061A
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: 2007-07-25
Anticipated expiration: 2025-08-08
Also published as: TW200607767A; CN100518919C; TWI373455B; FR2874375A1

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 dissolved mineral substance that has the alterable height ratio in a large number.Some mineral substance wherein are present in various types of water with sizable concentration usually, and other mineral substance then only exists with the form of trace.The present invention only relates to first kind of mineral substance.

These dissolved substances comprise:

-negatively charged ion: carbonate and bicarbonate radical, sulfate radical, chlorine root and nitrate radical, silicon-dioxide;

-and positively charged ion: calcium, magnesium and basic metal (mainly being sodium).

For the conformance with standard 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, dissolved salt is dissociated into HCO fully ₃ ^-Or CO ₃ ^2-, SO ₄ ^2-Or Cl ^-Negatively charged ion and Ca ²⁺, Mg ²⁺, Na ⁺Therefore Deng positively charged ion, 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 positively charged ion and negatively charged ion during with insoluble form precipitation, positively charged ion just combines with negatively charged ion.

When desalt reaction beginning, they are complete free, and only are in order to meet conventional custom, just adopt molecular form 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 hydrogen carbonate

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

Be the primitive reaction of applied decarburization in this case, it is based on the big poor solubility between Calcium hydrogen carbonate and the carbon neutral hydrochlorate:

CaCO ₃Solubleness with and with free CO ₂Or " half bonded " CO ₂Balance become the theme of numerous studies.The various researchs of quoting among M é mentoTechnique de l ' the Eau Degr é mont by the Cinquantenaire publication in 1988 define water and CaCO ₃Sedimentary equilibrium conditions.The variation of the solubleness of lime 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 dissolved lime carbonate.This amount is usually corresponding to 0.2-0.3 milliequivalent TA/ liter (TA: supercarbonate 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 radical, 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 hydrogen carbonate 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 lime 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 colour-change 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 contents+Mg content),

-TA=supercarbonate 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 ₃Solubleness.

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

If add excessive lime, then cause following secondary reaction:

" ou " expression " perhaps " in following formula.

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

Except the exception of water with very high selenium content, it is solvable that this calcium keeps, and the solubleness 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 solubleness of magnesium oxide in water (be about 0.1 milliequivalent/liter), PA and TA slightly increase, and keep substantially constant, need only magnesium oxide and not exclusively precipitate.When best purifying, small-amount free magnesium oxide will be present in the water, make PA bigger slightly than TA/2.

Sodium hydroxide is to the effect of Calcium hydrogen carbonate

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 sodium hydroxide 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 contents 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 (2 TA-C.Ca) value of unboiled water and become bigger.

But, be acceptable (for example in the processing of tap water) if certain density supercarbonate is stayed in the water, then this method remains favourable, but the dosage of sodium hydroxide 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 supercarbonate content reduces, and condition is that the sodium hydroxide dosage of adding is no more than half of unboiled water calcium contents.

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 sodium hydroxide dosage must be revised, this can cause because the additive decrementation of the sodium hydroxide that following reaction caused:

2NaOH+CO ₂—→Na ₂CO ₃+H ₂O (6)

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 precipitating action decarburization, used or used three class devices:

-" slowly " reactor (for example, conventional settler, it is transformed into provides decarbonizing tower, and comprises only mixing section, then is to be used for settled space); The feature of these reactors is low-down velocity of flow (and therefore needing big space), the residence time by the very slow kinetics of precipitation of calcium carbonate set (only with lime or sodium hydroxide when finishing in 20-30 hour after water to be processed mixes, just reach the sedimentation equilibrium under the envrionment 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 lime 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 reaction kinetics has greatly been quickened in this operation; This be because, in this case, can think decarburizing reaction with several minutes duration of contact (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 sodium hydroxide) 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 separation 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 lime carbonate gradually, and play the effect of crystal seed subsequently, this can quicken (or " catalysis ") decarburizing reaction.It is very compact that these decanting vessels 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 lime carbonate covers, but has got rid of the water clarification that comprises " gently " throw out 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 recirculation unit.And in the Sludge Bed of aforementioned means, single crystalline 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 lift velocity.

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 close 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 pressurized water, and its strainer 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 recirculation 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 stabilization, drainage material etc.

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

Since when the lime carbonate hypertrophy total reaction table area become inadequately, and reaction becomes not exclusively, so be coated with the dimensional change of the sand grains of lime 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 Mg content.Particularly, the back one situation under, magnesium oxide precipitates, this magnesium oxide 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 control of precipitation seed then needs regularly to monitor catalyst body, and need be designed for effectively and remove the system of " macrobead " that the outside is coated with the sand of lime carbonate, and the minimizing of checked 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 researchs and to the various tests of industrial equipments.

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 lime carbonate of size greater than the 1.2mm hydraulic diameter.

In the prior art, carry out this removing by metal hose, the upper surface flush of these metal hoses 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 metal hose 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 makes the gained mixture and be used to cause the crystalline crystal seed and contact.This operating of contacts occurs in the fluidized-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 fluidized-bed.These crystal grain can be the crystal grain of crossing filter sand of calcining and washing.

This reactant comprises basic 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 phosphoric acid salt in several 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 outfall pipeline 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 lime carbonate basically.

The present invention relates to the reactor of this identical general type, but it is applied to comprise the catalytic decarbonation of the water of dissolved Calcium hydrogen carbonate, 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 lime carbonate by inert particle.

For this reason, theme of the present invention is the equipment of catalytic decarbonation that is used to comprise the water of dissolved Calcium hydrogen carbonate, this equipment comprises reactor, this reactor comprises the tank-top plate of horizontal placement in its underpart, be used for providing to this reactor the device of pressurized 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 pressurized 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 outfall pipeline that is coated with the inert particle of lime carbonate, the water that this diameter that is coated with the inert particle of lime carbonate equals predetermined size 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 particulate outfall pipeline 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, up to itself and outside drain pipe coupling, exceptionally, randomly be the horizontal component that begins from the aperture, they lead in the reactor by this aperture.

The key parameter of the outfall pipeline of reactor is the internal diameter of these pipelines, because equal the inert particle that is coated with lime 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 these particulate underspeeds clearly, bigger diameter causes the deposition of largest particle in the pipe, this speed is necessary for 1.8-3m/s, preferred 2-2.5m/s.

As mentioned above, the particulate outfall pipeline that is coated with lime 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.Transmit for the ease of particulate, can be to the removing water outside this manifold amount supplied.

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

The curved part of these pipelines preferably has the triple 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 lime carbonate of preset value at least, this system is that index calculates according to the real-time residence time of water in reactor of handling.

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

Can optimize the removing of the largest particle that is coated with lime carbonate by using these different characteristicss, simultaneously the volume of following water that extracts from reactor is minimized, and can remove with respect to the more macrobead of all material body that discharges in each scavenging process 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 per-cent 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 pressurized water by pipeline 2 to this reactor in its underpart, and this pressurized water comprises the dissolved Calcium hydrogen carbonate.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 sodium hydroxide) in the reactor.

Pressurized 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 hydrogen carbonate that exists in the water to be processed reacts, and is converted into lime 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 hydrogen carbonate 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 much bigger particulate trend that is coated with lime carbonate in the top that forms the ratio bed, therefore must periodically or remove the particle that meets or exceeds in these particles more than or equal to the hydraulic diameter of preset value (being typically about 1.2mm) continuously.

For this reason, according to routine techniques, be provided for discharging these oarse-grained metal hoses 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 macrobead is entrained with by the current of following that are derived from reactor.

But these metal hoses 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 macrobeads 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 outfall pipeline 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 curved part preferably has and equals to manage diameter triple larger radius of curvature at least, and for the diameter of 50mm, this radius-of-curvature is about 15cm.

Under these conditions, removing by the water of following that from reactor, takes out that (this speed is 1.8-3m/s under the particulate appropriate speed in these pipelines, 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 lime carbonate than the much higher per-cent of prior art.

Claims

1. be used to comprise the catalytic decarbonation appliance of the water of dissolved Calcium hydrogen carbonate, this equipment comprises reactor (1 '), this reactor comprises base plate (3 ') in its underpart, at least be used for providing pressurized water (2 ' to this reactor at the upper surface of this base plate, 4 ') and the device of decarburizing reaction thing (9 '), the bed (5 ') of inert solid particle such as sand, it is placed on the top of base plate (3 ') in the reactor (1 '), thereby make pressurized 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 outfall pipeline (7 ' that is coated with the inert particle of lime carbonate at least one of reactor (1 ') top a, 7 ' b), the water that this diameter that is coated with the inert particle of lime carbonate equals predetermined size 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 particulate outfall pipeline (7 ' that is capped a, 7 ' b) be rigid line, its internal diameter is 40-60mm, be preferably 45-55mm, and for the risk that guarantees regular pm emission and do not have to stop up, these pipelines have continual downward gradient, are connected with external drain (8 ') up to it, exceptionally, randomly be the horizontal component that begins from the aperture, they lead in the reactor (1 ') by this aperture.

2. equipment as claimed in claim 1 is characterized in that, pipeline (7 ' a, 7 ' b) curved part have the triple radius-of-curvature that equals pipeline diameter at least.

3. the purposes of equipment as claimed in claim 1 or 2 is used for discharging the inert particle that is coated with lime carbonate that hydraulic diameter equals 1.2mm at least from reactor (1 ').

4. purposes as claimed in claim 3 is characterized in that, in pipeline (7 ' a, 7 ' b), is 1.8-3m/s by following current to remove the particulate speed that is coated with lime carbonate, preferred 2-2.5m/s.

5. as claim 3 or 4 described purposes, it is characterized in that the decarburizing reaction thing comprises lime or sodium hydroxide.