Purification technologies in the water industry are "modified" chemical manufacturing technologies in which various physical, physical-chemical, chemical processes take place in extremely dilute concentrations.
The application possibilities can be presented, partly following the path of the water to be purified, as mixing to meet the needs of production technology, and partly as an essential auxiliary process (e.g. solution preparation).
1.1.1 Pre-technological homogenisation of incoming waters from different sources
Where two, three or more liquids of different qualities are mixed prior to a particular process or series of processes, such as.
- industrial effluents of different origins (quality, temperature) meet upstream of the treatment plant,
- different qualities of well water meeting in a collection pipe upstream treatment technology,
- Receiving two different qualities of water upstream a freshwater pool/tank (possibly with a chlorination requirement),
- it is essential to ensure a homogeneous mixture before sampling.
A sufficient homogeneity is the guarantee that the intervention, i.e. the purification technology, determined on the basis of the analysis of the sample taken, will be effective.
With TETRAMIX static mixers, total homogeneity over the entire cross-section of the pipe is guaranteed at any time, even in laminar flow.
1.1.2 Preparing a chemical solution, maintaining the homogeneity of the solution, dilution, suspension
When preparing solutions, the most important thing is to know the solubility and the the required mixing time, since depending on this, the static mixer must be placed in a continuous or a circular cycle solvent system.
Dilution, suspension (emulsion) preparation
Tasks may include:
- concentrated hydrochloric acid, concentrated sulphuric acid, alkaline, ...etc., or
- dilution of the basic detergent solution (in the daily tank), (first figure),
- preparation of carbon powder, micro-sand suspensions by direct dosing (second figure).
Solution preparation, exploration
For substances that dissolve slowly and are difficult to dissolve, it is advisable to use the following solution to maintain solution homogeneity.
The dissolution circle can be 1-2 centrally or 1-3 tangentially restored circular cycles for highly soluble materials, and may be in the 1-4 configuration for dissolving crystalline materials. The pump must be insensitive to the abrasive effect of crystalline materials.
It is easier to maintain the homogeneity of the case solution as shown in the two figures below.
It is easier to maintain the homogeneity of the case solution as shown in the two figures below.
The positioning of TETRAMIX static mixers on the suction side of the pump is made possible by the the mixer's low pressure drop.
For well-mixable materials, the use of a suction-side mixer can be avoided by using the TETRAMIX static mixer in the tank (right figure).
1.1.3 Mixing after chemical dosing
The most common, widespread type of task.
The default situation is that the required cleaning technology aid is ready to dispense (in solution).
In water or wastewater treatment, these auxiliary substances, for specific technological purposes
- pre-oxidising agents,
- pH adjusters,
- auxiliary agents,
- intermediate oxidants,
- various disinfectants,...etc.
The TETRAMIX static mixers in the process flow diagram of a surface water treatment plant are shown in the figure below.
22.214.171.124 Oxidising agents
Chlorine -, potassium- permanganate oxidation, air oxidation ...etc.
A reaction process, such as oxidation, is not always carried out instantaneously. In order to increase the effectiveness, the task is to bring the elementary volume particles of the water and oxidising agent into close contact with each other as quickly as possible, so that the reaction processes can take place as intensively as possible over a large surface area.
Special emphasis should be given to the inefficiency of chemical mixing due to laminar or near laminar flow in small diameter pipes (DN 25-65) and the so-called tunnel effect in large diameter pipes (DN 400 and above).
By using the TETRAMIX static mixer, not only the efficiency of the mixing is increased, but also, as in an ideal tube reactor, the conditions for other sub-processes are created.
Typical purification technologies where optimal conditions for reaction processes can be properly ensured with TETRAMIX static mixer:
- surface water treatment, pre-oxidation (Cl2, KMnO4),
- chlorine and potassium permanganate oxidation iron and manganese removal,
- air oxidation de-ironing,
- ammonia removal by breakpoint chlorination...etc.
126.96.36.199 PH setting
Good production, proper reaction processes and good product quality are only possible for many process steps within the prescribed, stable, defined pH range.
Maintaining a stable condition level is possible with a well-constructed control circuit with a small time constant. This differentiation-based regulation, assumes that the samples are – constant in time and space – taken from a homogeneous environment, which can usually only be ensured by using static mixers.
In a chemical environment, pH adjustment cannot exist without the use of a static mixer, just as good chlorine or chlorine dioxide levels cannot do without vibration-free, low time-inertia control.
|Schematic diagram of the pH adjustment control loop
with TETRAMIX static mixer
188.8.131.52 Dosing of flocculants / coagulants
One of the most important and most commonly used chemicals in the drinking water, industrial and waste water treatment sectors, they are the so-called flaking or coagulating agents, i.e. various iron salts, aluminium sulphate, poly-aluminium chloride (PAC).
Separation, contact separation or rapid coagulation filtration and flocculation are purification technology stages that cannot do without the use of coagulants.
The mixing should be carried out at the same speed as the reaction processes, in the order of a second, making sure that the dispersed systems of the microflakes and the contaminant collide as often as possible.
Depending on the flow conditions, the task can ideally be performed with a standard 2-4 element TETRAMIX or an 8-12 element polymix TETRAMIXPK static mixer, while ensuring the required speed gradient and energy dissipation and optimum chemical consumption. vegyszerfelhasználás biztosítása mellett.
184.108.40.206 Dosing of polimers
Adjuvant diluents, also known as polymers, require much "softer" mixing than basic diluents.
Sometimes it is sufficient to use a TETRAMIX static mixer with a stretched design, L/D=1-1.5, single element standard or curved design, placed directly in front of a labyrinth tank, basin or flocculator device for slow, turbulent mixing.
It is important to avoid strong shearing forces, which could lead to the collapse of the larger flakes that have already formed. The static mixer is a good guarantee that not only a so-called polyelectrolyte float, but also a perfectly mixed mixture enters the flocculator through the entire cross-section of the inlet pipe.
220.127.116.11 Intermediate oxidation, post disinfection
Even the most professionally designed artwork (freshwater pools) can contain blind spaces.
It is very difficult for the oxidant to reach this locations, often only by diffusion, especially if the inlet cross-section is not homogeneous.
If the static mixer is used to ensure the conditions for maximum disinfection efficiency - close contact across the entire cross-section - before the solution/water entering the pool or storage tank, the poor mixing efficiency of the medium becomes secondary. Basin mire vonatozott? Nem teljesen értem ezt a mondatot.
Advantages of TETRAMIX static mixers for mixing chloroforms:
- Perfect mixing in the entire volume of water.
- Provide immediate contact time. (Particularly important for intermediate chlorination of water distribution systems where customers are relatively close.)
- Blind-free mixing, i.e. all elementary volume components are degerminated.
- Fluctuation-free chlorine concentration at sampling.
- Optimises control, minimises chlorine usage.
- Homogeneity reduces the likelihood of formation of harmful chlorination products.
- It also prevents the formation of long-lasting concentrated sludge and thus the formation of various chlorides, the high chlorine concentrations not consumed, which have a strong corrosive effect on the structural materials of pipes, fittings and pumps.
1.1.4 Sludge treatment, drainage
Here, the chemical pre-treatment of sludges from various origins and their preparation for dewatering should be highlighted. It is also true for the task that the optimal mechanism of the different agents is only ensured if their close contact is guaranteed by proper mixing. Operational aspects may also justify the need for good mixing, such as in sludge conditioning with lime solution. Here, the static mixer also minimises the tendency of the lime solution to precipitate (especially in laminar and near laminar ranges) by forming the ideal mixing mixture, reduces the clogging tendency of the pipeline section.
Mechanical drainage of physically, chemically or biologically conditioned sludges, such as.
- vacuum drum filter,
- filter press
- press tape filter
- can no longer exist without the use of advanced polymers.
However, the effectiveness of these polymers depends on how well, how intensively and for how long they are mixed in.
The most practical application of the static mixer is shown in the figure below (vertical installation), where the possibility of backwashing the equipment as required has been built in.
1.1.5 Pulsation smoothing
This is an extremely useful and practical feature of some specific types of TETRAMIX static mixers.
It expresses the ability to make the intermittent dosing mode and flow caused by diaphragm and/or piston dosing pumps - beyond perfect mixing - continuous, as shown in the schematic below.
Ensuring continuous chemical application, combined with good mixing, guarantees optimal chemical use. Pulse smoothing can greatly improve cleaning processes in all the applications listed so far.
The two differently coloured "concentrated chemical plugs" shown in the picture, spaced about 1 metre apart, are diluted during the mixing of the static mixer and continue their journey as a homogeneous mixture, in close succession. So continuous chemical treatment is guaranteed.