pH and ORP Analyzers

what-is-ph-orpObtaining accurate pH and ORP measurements from your analyzer and interpreting this data correctly is critical to ensuring product quality and making accurate predictions of sensor lifetime.

Yokogawa’s pH and ORP measurement solutions include 2-wire and 4-wire analyzers featuring real-time online sensor diagnostics to provide reliable results. Our pH and ORP analyzers use the latest analyzer sensor technology to improve predictive maintenance and reduce the time and costs associated with sensor maintenance and replacement, optimizing your OPEX.

 

 

  FLXA202/21 PH450
 

Area Classification General Purpose
Class I Div I
Class I Div II
General Purpose
Class I Div II
Power Supply 24VDC loop-powered
(2-wire)
110VAC, 24VDC
(4-wire)
Communication 4-20mA, HART, FF and PA* 4-20mA, HART
Contacts and Relays None 4 SPDT relays

*FF (FOUNDATION Fieldbus) and PA (Profibus) communication only available in FLXA21

  • The FLEXA™ series analyzers are used for continuous on-line measurements in industrial installations. With an option for single or dual sensor measurement, they are the most flexible two-wire analyzer available.

  • The PH450 pH and ORP analyzer is a multivariable analyzer that combines pH with temperature and ORP (Redox) measurement, which can be utilized through different output functions: two mA current outputs, four independent SPDT contact outputs and HART. 

  •  

    For industrial applications and particularly for automatic process measurements it is of the greatest importance that the sensistive part of a glass electrode and the diaphragm of areference electrode are kept clean.

  • The PH71/PH72 pH and/or ORP meter is a Compact, Easy-to-use, Drip proof – Ideal for Field Use. Features "One-Touch Calibration" and Temperature Compensation. Laboratory-Grade Intelligent pH Meters – Sized and Priced to Fit in Your Pocket

Optimize and eliminate surprise field maintenance, calibration and system configuration by utilizing real-time sensor diagnostic and predictive maintenance features built into Yokogawa pH and ORP analyzers.

Pure Water and Ultrapure Water

Purified water has very low conductivity, which means it is high in resistance because all the conductive components have been removed. In low conductive solutions combined with its susceptibility to contamination and temperature effects, makes accurate pH measurement very difficult. Pure water and ultrapure water is used in a variety of industrial processes such as semiconductor, power, water and pharmaceutical industries.

Achieving accurate and reliable readings using a traditional pH analyzer is challenging, however with the right equipment stable and accurate pure water pH measurements can be accomplished. 

Water and Wastewater

Water quality is crucial in all areas of life to process industrial automation. Applications such as aquaculture and chromium wastewater treatment rely on accurate pH and ORP measurements to ensure safe pH levels or proper control of chromium reduction processes.

Yokogawa's 4-wire and 2-wire pH analyzer solutions with suitable immersion fitting and sensors are ideal for measuring these crucial pH and ORP measurements.

Pulp and Paper

The demanding applications and severe process conditions in pulp mills pose challenges for accurate, repeatable and reliable liquid analysis measurements. Treating wastewater from pulp and paper plants requires maintaining proper pH levels, which can be controlled by referring to a pH analyzer.

Yokogawa pH and ORP analyzers include real-time sensor diagnostic and predictive maintenance features to continuously and stably measure pH levels, eliminate the need for frequent manual cleaning, and enable efficient use of flocculating agents.

Chemical

The chemical industry presents multiple challenges such as chemical attacks, maintenance, safety, consistency and reliability to any liquid analysis measurement. In flue gas desulfurization systems that use magnesium hydroxide (Mg(OH)2 ) slurry, the consumption of the desulfurization agent (Mg(OH)2 ) is controlled using online pH analyzers.

Yokogawa’s pH measurement solutions ensure stable, continuous pH measurement over long periods, reduce operating costs, and eliminate manual cleaning.

Noty aplikacyjne
Przegląd:

The term "cooling tower" is used to describe both direct (open circuit) and indirect (closed circuit) heat rejection equipment. Cooling towers are heat-transfer units, used to remove heat from any water-cooled system. The cooled water is then re-circulated (and thus, recycled) back into the system. Since the process water is re-circulated, the mineral concentration increases as a result of the evaporation.

Industry:Refining, Food and Beverage, Power, Oil and Gas, Pulp and Paper, Chemical

Przemysł:
Przegląd:

The proliferation of microorganisms and the resultant formation of slime is a problem which commonly occurs in aqueous systems. Problematic slime producing microbes may include bacteria, fungi and/or algae. Slime deposits typically occur in many industrial aqueous systems including cooling water systems, pulp and paper mill systems, petroleum operations, clay and pigment slurries, recreational water systems, air washer systems, decorative fountains, food, beverage, and industrial process pasteurizers, sweetwater systems, gas scrubber systems, latex systems, industrial lubricants, cutting fluids, etc.

Industry:Refining, Food and beverage, Power, Oil and Gas, Pulp and Paper, Chemical

Przemysł:
Przegląd:

There are a number of suppliers of oil and fat products used for edible purposes. These products include, but are not limited to olive oil, peanut oil, soybean oil, sunflower oil, lard, shortening, butter, and margarine. The raw materials for these products include animal by-products, fleshy fruits (palm and olive), and oilseeds. 

Industry:Food and Beverage

Przegląd:

One of the primary applications for high purity water is for boiler feed water. The measurement of pure water pH can be one of the quickest indicators of process contamination in the production or distribution of pure water. Effective chemical treatment of the feed water is vital in maintaining the useful operating life and minimizing maintenance costs of the boiler.

Industry:Power, Pharmaceutical, Common

Przemysł:
Przegląd:

Control of sodium chloride (NaCl) concentration at a salt dissolver where solid salt is dissolved in water, is highly important because of the electrolysis efficiency. A conventional way of measuring the concentration of supersaturated NaCl solution had been performed by using non-contact type sensors (e.g., γ-ray density meter) since NaCl, impurities, and precipitates are in the solution.

Przegląd:

Most zinc are produced at hydrometallurgically, where a high-grade zinc product can be obtained and valuable metals mixed in the raw material can be recovered. In the hydrometallurgy, the raw material of zinc concentrate is roasted and then dissolved in sulfuric acid to remove impurities. The process called leaching and pH control of the leachate is important.

Industry:Chemical, Power

Przegląd:

The control of the world's water resource is arguably one of the most important issues. Water demand from industry and domestic users is set to rise throughout the industrialized world. Yokogawa has been applying minimized maintenance measurement systems.

Przegląd:

In the manufacturing process of Pharmaceutical, Chemical and Food & Beverage industries, the cleaning and sterilization of tanks and piping are done with various cleaning solutions, fresh or hot water and steam after manufacturing products. Clean-In-Place (CIP) is the system designed for automatic cleaning and disinfecting.

Przegląd:

Problems at the wet end of a paper machine can rarely be corrected down stream. That is why monitoring and controlling pH in pulp stock is critical to the paper making process. Essentially, at every stage in the manufacture of paper, correct pH values play a vital role. Variations in the pH value at the head box have a negative effect on the quality of the paper produced.

Przegląd:

Cyanide-bearing wastewater from mining and electroplating facilities and certain types of chemical plants is toxic and must be treated by oxidation with chlorine or chloride to bring the cyanide concentration within regulatory limits.

Industry:Electrical and Electronics

Przegląd:

The treatment of wastewater from pulp and paper plants is a serious environmental concern. Yokogawa's submersion holder with an ultrasonic+air-jet cleaner (customized product) can reduce the manual cleaning frequency to just once every one or two months.

Industry:Pulp & Paper

Przegląd:

Continuous technology improvement is ongoing in the pulp & paper industry to obtain the best possible performance. Problems at the wet end (stock preparation) can rarely be corrected downstream. That is why monitoring and controlling pH in pulp stock is critical to the paper making process. Essentially, at every stage in the manufacture of paper, correct pH values play a vital role.

Przegląd:

Reverse osmosis (RO) is a separation process that uses pressure to force a solution through a membrane that retains the solute on one side and allows the pure solvent to pass to the other side. More formally, it is the process of forcing a solvent from a region of high solute concentration through a membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure.

Przegląd:

Sour Water is the wastewater that is produced from atmospheric and vacuum crude columns at refineries. Hydrogen sulfide and ammonia are typical components in sour water that need to be removed before the water can be reused elsewhere in the plant. Removal of these components is done by sending the sour water from the process to a stripping tower where heat, in the form of steam, is applied.

Przegląd:

Power plant boiler houses designed to burn coal or high sulfur oil are required by Federal and State pollution regulations to "scrub" (remove) sulfur dioxide from flue gasses to meet emission limits. SO2 in flue gasses is known to be harmful to the environment, as it is one contributor to the formation of acid rain. pH control is critical for the proper functioning of the scrubber system.

Przemysł:
Noty aplikacyjne
Przegląd:

For control of batch neutralization, a pH measurement coupled with a timer-controlled chemical feed scheme provides very satisfactory results.

This system can be adapted for either acid waste or alkaline waste neutralization.

Przegląd:

Wet scrubbers are used in utilities, paper mills, and chemical plants to remove sulfur dioxide (SO2) and other pollutants from gas streams. Undesirable pollutants are removed by contacting the gases with an aqueous solution or slurry containing a sorbent. The most common sorbents are lime, Ca(OH)2, and limestone, CaCO3

Przemysł:
Noty aplikacyjne
Przegląd:

Introduction

an1Diazonium Coupling (Diazo Coupling, Azo Coupling):

Due to their positive charge, diazonium cations, which are generated by treatment of aromatic amines with nitrous acid and a stronger mineral acid, may participate in an electrophilic aromatic substitution as an electrophile. The electrophilic reaction center is the terminal nitrogen of the - N=N group. As a result, two aromatic compounds are coupled by a -N=Ngroup. This is known as the azo group (diazo group).


The corresponding reaction is called diazonium coupling (diazo coupling, azo coupling). However, the electrophilicity of diazonium ions is only relatively weak, as their positive charge is delocalized.an2 The unsubstituted benzenediazonium cation may react only with strongly activated aromatic compounds, such as phenolates and amines.

Azo coupling is the most widely used industrial reaction in the production of dyes, lakes and pigments. Aromatic diazonium ions acts as electrophiles in coupling reactions with activated aromatics such as anilines or phenols.


The substitution normally occurs at the para position, except when this position is already occupied, in which case ortho position is favoured. The pH of solution is quite important; it must be mildly acidic or neutral, since no reaction takes place if the pH is too low.


 

Application Information

Typical process details:

  • Chemical Composition - Coupler + Diazo Coupler – 48 % caustic + Nepthol + Water Diazo -36% HCL + Diecloro Anelene + Water Operating Temperature – 55°C
  • Operating Pressure – 4 kg/cm2

Typical problems:

Limited life of sensor

Summary

The process is indeed quite aggressive so Glass is best material.

Sensor Selection:

Sensor Option #1: SC21C-AGC55 would be best, if it is possible to pressurize the electrolyte to 5 bar (72PSI).

Features for type SC21C-AGC55

  • Heavy duty pH sensitive glass.
  • Flowing reference system for pollution resistance, 
and highly stable reference potential.
  • Use in combination with the presurisable electrolyte 
reservoir to obtain a positive flow towards the process (K1500YA)

Sensor Option #2: SC24V is possible if the cation (salt) content is stable during the pH control step.

Features

The SC24V is a differential pH sensor. This means that the reference is not a (liquid) junction but a glass sensor which does not respond to pH changes (within the applicable range of the sensor). Therefore the sensor is truly maintenance free and the output voltage of the sensor depends only on the salt concentration of the process.

The sensor responds to pH changes rather than analyses the accurate pH value. In that sense it is best to describe the sensor as pH control sensor rather than pH measuring sensor. 
A pH sensor measures the voltage that the pH membrane measures as function of the pH value of the process sample. This voltage is then compared with the mV output of a reference cell that is independent on the pH value of the sensor.


In most pH control applications the salt concentration is rather constant, so the output of the SC24V differential sensor is only dependent on the pH of the process. 
A rule of thumb is that a change in salt concentration of +/- 25% has an effect of less than 0.1pH on the pH reading.

Przegląd:

Removal of free oil and grease from a wastewater stream reduces the potential for equipment problems to occur further downstream. There are three forms of oil encountered in wastewater treatment at a refinery. 

Noty aplikacyjne
Przegląd:

Wastes have been considered to be a serious worldwide environmental problem in recent years. Because of increasing pollution, these wastes should be treated. However, industrial wastes can contain a number of valuable organic components. Recovery of these components is important economically. Using conventional distillation techniques, the separation of acetic acid and water is both impractical and uneconomical, because it often requires large number of trays and a high reflux ratio. In practice special techniques are used depending on the concentration of acetic acid. 

Noty aplikacyjne
Przegląd:

Introduction

Two types of polymerization reaction are used to produce styrene-butadiene copolymers, the emulsion type and the solution type. This section addresses volatile organic compound (VOC) emissions from the manufacture of copolymers of styrene and butadiene made by emulsion polymerization processes. The emulsion products can be sold in either a granular solid form, known as crumb, or in a liquid form, known as latex.

Copolymers of styrene and butadiene can be made with properties ranging from those of a rubbery material to those of a very resilient plastic. Copolymers containing less than 45 weight percent styrene are known as styrene-butadiene rubber (SBR). As the styrene content is increased over
45 weight percent, the product becomes increasingly more plastic.

As shown in below figure, fresh styrene and butadiene are piped separately to the manufacturing plant from the storage area. Polymerization of styrene and butadiene proceeds continuously through a train of reactors, with a residence time in each reactor of approximately 1 hour. The reaction product formed in the emulsion phase of the reaction mixture is a milky white emulsion called latex. The overall polymerization reaction ordinarily is not carried out beyond a 60 percent conversion of monomers to polymer, because the reaction rate falls off considerably beyond this point and product quality begins to deteriorate.

crumb1

Because recovery of the unreacted monomers and their subsequent purification are essential to economical operation, unreacted butadiene and styrene from the emulsion crumb polymerization process normally are recovered. The latex emulsion is introduced to flash tanks where, using vacuum flashing, the unreacted butadiene is removed. The butadiene is then compressed, condensed, and pumped back to the tank farm storage area for subsequent reuse. The condenser tail gases and
 noncondensables pass through a butadiene adsorber/desorber unit, where more butadiene is recovered.

Some noncondensables and VOC vapors pass to the atmosphere or, at some plants, to a flare system. The latex stream from the butadiene recovery area is then sent to the styrene recovery process, usually taking place in perforated plate steam stripping columns. From the styrene stripper, the latex is stored in blend tanks.

From this point in the manufacturing process, latex is processed continuously. The latex is pumped from the blend tanks to coagulation vessels, where dilute sulfuric acid (H2SO4 of pH 4 to 4.5) and sodium chloride solution are added. The acid and brine mixture causes the emulsion to break, releasing the styrene-butadiene copolymer as crumb product. The coagulation vessels are open to the atmosphere.
Leaving the coagulation process, the crumb and brine acid slurry is separated by screens into solid and liquid. The crumb product is processed in rotary presses that squeeze out most of the entrained water. The liquid (brine/acid) from the screening area and the rotary presses is cycled to the coagulation area for reuse.

Typical Process Details:

crumb2Fluid: Crumb slurry


  1. Fluid composition (normal):
    Water: 95% wt

    Polymer: 4.06% wt

    Fatty acid: 0.2% wt

    Extender oil: 0% wt. (Max. 1.45% wt)
    Rosin acid: 0.078%wt
  2. Acidity (min/orm/Max): 0.0/3.6/14.0
  3. Fluid design conditions P@T: 1.033 Kg/cm2- 
g@115 degC
  4. Boiling point @ operating pressure: 100 degC 

    Dew point @ operating pressure: 100 degC
    Boiling point @ atmospheric pressure: 100 degC

    Dew point @ atmospheric pressure: 100 degC
  5. Density: 980 kg/m3 (Norm)
  6. Fluid able to foul

Max. pressure: 1.033 kgf/cme-g Tempe: 62 degC

Crumb rinsing and dewatering

Typical Problems:

This is indeed a tough application. The rubber tends to stick on the holder. The rubber does not tend to stick on the glass very much.

Remedies:

To mount the holders in such a way that they can swing with the process flow and make them easy to remove for manual cleaning: 0.5 or 1 m immersion fittings hanging on the hoisting cable on a hook.

Solutions:

  • Sensor: SC25V series
  • Features SC25V
  • External titanium Liquid Earth
  • Pt1000 integration in pH compartment giving highly accurate temperature compensation
  • CIP and Steam cleaning possible
Large internal KCl volume giving the sensor a longer life time
  • SC25V-ALP25 for chemically harsh applications and high temperatures

Alternatively, SENCOM sensor can be used. (SC25F)

Sensor Holder:

The FD20-P37 comes with hoisting cable made of SS316. When the holder is mounted this way, just hangs in the vessel, then it can swing with the flow. Otherwise the rubber slurry may damage the sensor if the holder is mounted rigidly. Most probably the sensor protection cage must be removed to prevent the polymer to fill the cage.

Noty aplikacyjne
Przegląd:

Introduction

In Bioscience company's pH is used at various places including glass lined reactor for product efficiency. One of such measurement of pH in reactor as explained below.

Application Information

Typical example of process is:

Reactor used is GLASS LINED REACTOR and length is 1950mm; and flange size 100mm split flange with 8 holes

PCB (fixing hole center to center) 190mm; flange outer to outer 225mm; flange extension pipe (Nozzle) ID 95mm.

Nature of fluid: Aqueous media
Operating temp & pressure: 30°C temp & atmosphere pressure
Area classification - Example Zone 1 / Zone 2
Nozzle ID: 95mm.

glass1

Product Recommendation

Measurement System

Process Liquid Analyzer: 

  • 2-wire FLEXA pH/ORP Analyzer
Features
  • Dual sensor measurement on 2-wire type analyser
  • Indication of sensor wellness

 

  • 4-wire PH450G pH/ORP Analyzer

Features

  • Easy touchscreen operation
  • Trending display up to 2 weeks
  • Advanced Process Temperature Compensation

Sensor Selection:

Hamilton® POLILYTE HTVP

Features:

  • Best measurement accuracy both in high-alkali processes and in samples with very low conductivity.
  • Sterilizable and autoclavable
  • SINGLE PORE‘s for clog-free contact of electrolyte with measurement medium
  • HAMILTON “H” pH glass
  • Serialized with batch number

Sensor Accessories

5mtrs Cable, Model No.: WU10-V-S-05 ,

Immersion sensor fitting (Customised): 1900mm Length, 4" Flange Connection with 8 holes PCB (fixing hole centre to centre) 190mm;  flange outer to outer 225mm; pipe (Nozzle) ID95mm. MOC : PTFE.

Tangible benefit

More reliable and accurate analysis of pH which helps to improve end product quality.

Note: For additional information on this application contact the local Yokogawa Process Liquid Analyzer Department

Noty aplikacyjne
Przegląd:

Introduction 

A process and apparatus for removing SO2 from a gas stream having the steps of scrubbing the SO2 with an ammonia scrubbing solution and removing any aerosols generated by the scrubbing in a wet electrostatic precipitator. The scrubbing solution is maintained at a pH between 6 and 8 to increase the speed of absorption of SO2, to Increase the ratio of sulfite to bisulfite which also facilitates the oxidation of SO2, and to avoid the need to use exotic, corrosion resistant alloys. Ammonium sulfate, a valuable fertilizer, can be withdrawn from the scrubbing solution.

Process background 

Fossil fuels are burned in many industrial processes. Electric power producers, for example, burn large quantities of coal, oil, and natural gas. Sulfur dioxide (“SO2”) is one of the unwanted byproducts of burning any type of fossil fuel. It is known to cause acid rain, and to have serious negative health effects on people, animals, and plants. A great deal of research has been done to find a way to economically remove SO2 from flue gas streams before it enters the atmosphere.

The pH of the ammonium sulfate solution should be kept between about four and six. This range is the result of a compromise between competing factors. On one hand, ammonium sulfate solution is capable of absorbing SO2 more rapidly when its pH is higher. The ability to absorb SO2 better implies that the size of the scrubbing tower can be smaller, thus saving capital costs. In addition, the liquid to gas (“L/G”) ratio can be smaller, meaning less liquid will be required and operating costs will be lower.

On the other hand, higher pH levels are also associated with the release of free ammonia from solution, often termed “ammonia slip.” In addition to incurring an economic loss because of lost ammonia, free ammonia in the scrubbed flue gas reacts with uncaptured sulfur dioxide and trioxide to create an ammonium sulfate/bisulfite aerosol that is visible as a blue or white plume in the stack discharge, leading to secondary pollution problems. Controlling the amount of free ammonia in the desulfurization process is in part a function of the ammonia vapor pressure, which results from a combination of pH and levels of unoxidized ammonium sulfite that remain in the absence of sufficient oxygen. Therefore, high pH values and high levels of unoxidized ammonium sulfite promote ammonia slip.

Typical Process Example 

  • Name of Application / Process: Ammonia Scrubbing
  • Location of Sensor mounting (location name): Tail Gas Scrubber Complex
  • Operating Temp / Max.Temp: 75 to 80 deg C
  • Operating Press / Max. Press: 2 to 2.5 Kg/cm2
  • Type of Installation: On Pipe ( Direct mounting ) / Flow through Chamber (By pass mounting ) /
  • Process Composition: Liquid - Scrub Acid,
    • P2O5:105 ppm,
    • AN (Ammonical Nitrogen):1326 ppm,
    • UN(Urea Nitrogen):22 ppm,
    • TN(Total Nitrogen):1348 ppm,
    • Florine:116 ppm.

Typical problems

  • Frequent cleaning, glass can be eaten away as the temperature and chemical attack glass

Remedies

  • Use of high temperature special sensor

Product Recommendation

Measurement System

Process Liquid Analyzer: 

  • 2-wire FLEXA pH/ORP Analyzer

 

Features

  • Dual sensor measurement on 2-wire type analyser
  • Indication of sensor wellness

 

  • 4-wire PH450G pH/ORP Analyzer

Features

  • Easy touchscreen operation
  • Trending display up to 2 weeks
  • Advanced Process Temperature Compensation

Sensor Selection:

SC25 sensor from Yokogawa is the perfect sensor for this application. High temperature sensor SC25 because of its design can serve purpose.

 

 

Features SC25V

  • External titanium Liquid Earth
  • Pt1000 integration in pH compartment giving highly accurate temperature compensation
  • CIP and Steam cleaning possible
  • Large internal KCl volume giving the sensor a longer life time
  • SC25V-ALP25 for chemically harsh applications and high temperatures

Cable:

  • WU10-V-S series

Retractable fitting:

  • PR10 series

On-line measurements always present extra challenges compared to at-line measurements, for example, when maintenance needs to be done. Applications like this where the sensors have to be removed without interruptions or shut-downs the PR10 is especially suitable. Without any special tools the PR10 can be retracted safely from the process up to 5 bar.

For ease of use optional flush ports are available. In the retracted position the sensor can be kept moist, cleaned or even calibrated. This can all be done without process interruption or disassembly of the armature.

Tangible benefit

Better life of sensor, improve end product quality.

Note: For additional information on this application contact the local Yokogawa Process Liquid Analyzer Department

 

 

Przegląd:

Sodium chlorate is an inorganic compound with the chemical formula NaClO3. It is a white crystalline powder that is readily soluble in water. It is hygroscopic. It decomposes above 300 °C to release oxygen and leave sodium chloride. Several hundred million tons are produced annually, mainly for applications in bleaching paper.

Noty aplikacyjne
Przegląd:

Introduction

The Combined Effects of pH and Percent Methanol on the HPLC Separation of Benzoic Acid and Phenol:

Many mobile-phase variables can affect an HPLC (High Performance Liquid Chromatograph) separation. Among these are pH and the percent and type of organic modifier. The pKa of a weak acid is the pH at which the acid is equally distributed between its protonated (uncharged) and unprotonated (charged) forms. This is illustrated by the Henderson–Hasselbalch equation:

pH = pKa + log ([A_]/[HA]

where [A_] is the concentration of the weak acid in its unprotonated form
and [HA] is the concentration of the weak acid in its protonated form.
 

If the weak acid is equally distributed between its two forms, ([A_]/[HA]) = 1, log ([A_]/[HA]) = 0, and pH = pKa. If the weak acid is not equally distributed between its two forms, then the pH will be either less or greater than the pKa of the weak acid.

For example, if [A_] < [HA], ([A_]/[HA]) < 1, log ([A_]/[HA]) < 0, and pH < pKa. Thus, a weak acid exists primarily in its protonated form at a pH below the pKa and therefore has a greater affinity for the nonpolar stationary phase. If [A_] > [HA], ([A_]/[HA]) > 1, log ([A_]/[HA]) > 0, and pH > pKa. Thus, a weak acid exists primarily in its unprotonated form at a pH above the pKa and therefore has a greater affinity for the polar mobile phase.

Fig 1 - full-factorial experimental design

Fig. 1 - A three-level, two-factor
full-factorial experimental design

Organic modifiers also have an effect on the retention of solutes in HPLC. In the reversed-phase mode (polar mobile phase, nonpolar stationary phase), the most polar solute component will elute first. This is because the most polar component interacts least with the nonpolar stationary phase.

As the polarity of the mobile phase is increased, those solute components that were previously highly retained (nonpolar components) will be retained even more.

Two species that are of public interest because of their classification as moderate environmental and health hazards are benzoic acid (pKa = 4.202) and phenol (pKa = 9.98). The purpose of this study is to investigate the combined effects of pH and percent methanol on the reversed-phase HPLC separation of these compounds.

A three-level, two-factor fullfactorial experimental design will be used to specify nine mobile phases for consideration in this study. The levels of pH were chosen to bracket the pKa value of benzoic acid (below, near,
and above 4.202). It was not possible to study a mobile phase with a pH > 7.5 owing to the pH range limit of the column. A methanol/water mobile phase was selected for this study because methanol is readily available in most undergraduate labs and relatively inexpensive. In addition, both solutes elute in a relatively short time, making completion of this lab during one or two lab periods possible.

Table 1. Mobile Phases Specified by the Experimental Design
 
Phase No. Methanol % pH
1 25 3.0
2 25 4.5
3 25 6.0
4 50 3.0
5 50 4.5
6 50 6.0
7 75 3.0
8 75 4.5
9 75 6.0

Major Observation

At low mobile-phase methanol concentration (25%), as pH increases, the retention time of phenol appears to be unaffected, whereas the retention time of benzoic acid decreases significantly. Over the pH range investigated, the mobile-phase pH is below the pKa of phenol. Thus, phenol will remain in its protonated form and should be unaffected by these mobile-phase changes. However, as pH increases, benzoic acid shifts from its protonated to its unprotonated form, decreasing its affinity for the nonpolar stationary phase and decreasing its retention time.

At intermediate (50%) and high (75%) mobile-phase methanol concentrations, as pH increases, the retention time of phenol remains unaffected by increases in pH while the retention time of benzoic acid decreases. This is consistent with the behaviour at low methanol concentration.

At pH 3.0, as percent methanol increases, the retention times of both phenol and benzoic acid decrease significantly. Because both solutes are polar, increasing mobile-phase polarity causes both to be retained less tightly. At pH 4.5 (slightly above the pKa of benzoic acid) and pH 6.0 (well above the pKa of benzoic acid) as percent methanol increases, the retention times of phenol and benzoic acid decrease. This is consistent with the retention behaviour at pH 3.0.

Typical Process Details

  • Customer plant: Bulk drug plant
  • Application: This is 4 cycle application. There will 
be a pipe connected to inlet which allows process to flow through the column and the same will be sent out from another pipe at outlet.
  • pH measurement is typically required at both the inlet and outlet. Temp: 30-40°C. pH range shall be 7 to 7.5. Between this range the customer can take necessary action to control his process.
  • Conductivity max. 300 micro siemens/cm.
  • Cycle 1: Process contains 95% liquid methanol, 
2% liquid ammonia, 3% water.
  • Cycle 2: Process contains 30% liquid methanol, 
70% water.
  • Cycle 3: Process contains 90% liquid methanol, 
5% liquid ammonia, 3% water, 2% sugar content.
  • Cycle 4: The column will be cleaned by flushing 
with DM water.
Przegląd:

In flue gas desulfurization systems that use magnesium hydroxide (Mg(OH)2) slurry, the consumption of the desulfurization agent (Mg(OH)2) is controlled by using online pH analyzers. A great concern in the pH measurement is heavy staining of the pH electrodes by the Mg(OH)2 slurry. To ensure accurate measurement, frequent cleaning of the electrodes with an acid is required, adding to both maintenance workload and cost.

Industry:Chemical, Power

Przegląd:

In stable dispersion of fine particles is the pre-requisite for the selective flocculation technique involving separation of ultra-fine valuable particles from the gangue. Among mineral processing techniques selective flocculation technique is known to have outstanding potential of capturing the particles of particular mineral in slurry of mixed mineral system by selective adsorption of water soluble polymers known as flocculants.

Przegląd:

Introduction

Integrated steel plants usually consist of five main units, Viz; Coal washery, Coke oven blast furnace, steel melting shop and rolling mills. In addition to the above the plants may have auxiliary units like oxygen plant and power plant for their own uses.

Application Information

Coal Washer and its Wastewater

The coal needs some processing to make it suitable for use in coke ovens. The main objective of such treatment is the removal of solid foreign matter present in the coal. Generally the process in a coal washer includes crushing, screening and wet washing of coal.  In the wet process the coal is separated from the impurities using the principal of differential settling.  Water used for washing is recycled and reused after sedimentation. But in spite of all care taken to ensure maximum reuse, appreciable quantity of wash water containing coal fines, and other impurities like clay and small amounts of other minerals like calcite, gypsum, pyrite etc, comes out as waste, normally in a thickened form as the under- flow of the sedimentation tank.

Blast Furnace and its Wastewater

Blast furnace is a basic unit in an integrated steel plant. Essentially the blast furnace process consists of charging iron ore and coke as fuel limestone and dolomite as fluxing material into the top of the furnace and blowing heated air (blast) into the bottom. Pig iron is the metallic product of this unit. Appreciable quantity of water is used in blast furnace for the purpose of cooling and gas cleaning operations. However, the cooling water normally remains un-contaminated and is reused after cooling.

The entire quantum of wastewater originates from the gas cleaning operations. The blast furnace gas, which is heavily loaded with flue dust, is cleaned in a three stage process.

The major portion of the flue dust which comes out along with blast furnace gas is recovered by the dry dust catchers. The remaining is removed by washing with water by “Wet Scrubbing”. The portion which escapes wet scrubber may be removed by electrostatic precipitator. In wet scrubber the down flow water sprays clean the dust from the up flowing gases and the wastewater contains 1000-10000 mg/l of suspended solids.

Characteristics of Typical Blast Furnace Waste

Parameter Value
Total Dissolved Solids 346 - 500 mg/l
Total Suspended Solids 1000 - 10500 mg/l
Dissolved Solids 80 - 118 mg/l as CaCO3
Total Hardness 230 mg/l as CaCO3
Total Alkalinty 380 mg/l as CaCO3
Chlorides 210 - 250 mg/l
pH 7.3 - 8.2

Treatment of Blast Furnace Waste

The blast furnace waste contains about 40% of the total dust coming out of the blast furnace along with the flue gas. Iron oxide and silica comprise about 70% and 12% respectively of the flue dust content. The waste can be treated in a clariflocculator even without the addition of coagulant. However the flocculation time can be reduced to a great extent when certain coagulants like alum or lime is added. The efficiency of the clariflocculator can be increased alternatively by a judicious mixing of this waste with the other wastes of the steel plant. The oxygen plant waste containing sodium hydroxide, may be used for this purpose.

Typical Process Details

Process: sticky nature of the slurry.

Slurry quality - Solid blast furnace GCP (Gas Cleaning Plant) containing fine particles of iron oxide, dust, coal dust.

  • Solid density: 1600 kg/m3,
  • Slurry temperature: 65°(Maximum)
  • Density of slurry water: 1-1.2 ton/m3
  • Total suspended solids: 50 – 250 gram/liter

Tentative range of particle size distribution as below:

Particle size (in micron) % by weight
0 - 5 13 - 33
5 - 10 13 - 17
10 - 20 15 - 18
20 - 40 17 - 21
40 - 60 10 - 40
60 - 100 6 - 15
> 100 4 - 10

The slurry has high deposition rate while it is not flowing.

Location

Inlet to pH correction tank

Fluid

GCP Slurry, BF application

Flow in m3 hour

1150

Velocity in m/sec

1.5

Temperature

60 to 70 degC

Inlet pressure in Bar (g)

open to atmosphere

pH value

3.0 to 9.0

Specific gravity of sludge

1-1.5

Bulk density of solid (kg/m3)

 

Suspended solid material

Sinter, ore, flux, coke, coal at difference

Fluid density in kg/m3

990-1078

TSS (ppm)

500 - 30000

Nature

Fluid is very sticky in nature

Typical problems

  • Coating on the sensor.
  • Frequent cleaning

Remedies

  • Coating can be cleaned off by diluted acid
  • Use appropriate sensor with suitable fitting.

Tangible benefit

More reliable and accurate analysis of pH which helps to improve end product quality.

Product Recommendations

Measurement System

Process Liquid Analyzer: 

  • 2-wire FLEXA pH/ORP Analyzer

Features

  • Dual sensor measurement on 2-wire type analyser
  • Indication of sensor wellness
 
  • 4-wire PH450G pH/ORP Analyzer

Features

  • Easy touchscreen operation
  • Trending display up to 2 weeks
  • Advanced Process Temperature Compensation

Sensor Selection:

FU20 all-in-one pH sensor with dome shaped membrane.

Features

  • With the body made of Ryton, a strong engineering plastic, which is comparable to Teflon in terms of corrosion resistance and heat resistance, it allows for a wide range of applications.
  • The integrated-sensor design simplifies calibration with standard solutions and maintenance.
  • Alternatively, SENCOM sensor can be used.  (FU20F)

Note: For additional information on this application contact the local Yokogawa Process Liquid Analyzer Department

Noty aplikacyjne
Przegląd:

Introduction 

During mining and processing, generation of fines and slime typically ~ 35 % and 10-25% of run-of-mines is a great concern to environment and loss of iron value. Iron ore fines and slime contain ~ 58 % Fe, high amount of alumina (> 8 %) and silica (~ 8 %). Statistics showed that the increase in 1% Fe in the concentrate productivity of the hot metal increases by 2 % and thereby coke and limestone requirements reduced by 1.8 % and 0.9 %, respectively. Considering the feed quality for the blast-furnace and the need to conserve the non-renewable resource, beneficiation of iron ore fines and slime is essential so that the Al2O3/Fe and Al2O3/SiO2 ratios are brought down below 0.05 and 1, respectively in the concentrate.

The simple plain water washing alone cannot change Al2O3/Fe and Al2O3/SiO2 ratios in the concentrate much from the feed. An alternative approach is to use techno economically cheap and eco-friendly surface-active agent(s) for beneficiation of iron ore fines and slime. In this context several synthetic chemicals are used viz., charged and uncharged polyacrylamide, starch humate and inorganic or organic additives or both. The main objective in these studies was to recover iron value from iron ore fines. The surface-active agents, either simple or complex, adsorb onto hematite surfaces resulting in flocculation of hematite particles and dispersion of gangue minerals rich in alumina.

Fig. A typical snapshot showing (a) dispersed phase (b) flocculation/settling of suspended particles in 1 % DP of slime slurry in the presence of natural hard water and (c) stable dispersed phase of 25 % iron ore fines using water from (b) and 0.05 % humate.

Dewatering and/or recovery of water from waste water/slurry is also an essential step in the iron ore washing. In an iron ore washing plant huge amount of water is required further there is loss of water and fresh water typically ~15 % is added to maintain the total amount of water in the washing circuit. Different kinds of flocculants are used for this purpose. Moreover, natural hard-water can be used as an alternative because it contains different ions, which are effective flocculating agents.

Dewatering and/or recovery of water from waste water/slurry is also an essential step in the iron ore washing. In an iron ore washing plant huge amount of water is required further there is loss of water and fresh water typically ~15 % is added to maintain the total amount of water in the washing circuit. Different kinds of flocculants are used for this purpose. Moreover, natural hard-water can be used as an alternative because it contains different ions, which are effective flocculating agents.

Why pH is required?

The “specific ion effects” in the metal oxide suspension is important to understand the behaviour of ion to modulate the surface charge of the oxide particles and subsequent change of pH of the suspension. It has already been seen that the pH of ferric hydroxide suspension with aging varies differently depending upon its initial value.

Efficacy of surface-active agent

The efficacy of the surface-active agents in removing the gangue minerals in the suspension of iron ore fines is observed at higher scale (500 g iron of fines/2000 mL water) at pH 8. The slurry shall be mixed properly in the container with a stirrer for about 15-20 minutes at a fixed additive dose and pH8. 

Typical process details

  • Plant: Beneficiation plant, pellet plant
  • Application: Iron ore slurry is pumped from beneficiation plant to pellet plant. pH measurement at pellet plant required.
  • Service: Iron slurry
  • Process composition: Iron dust 30%, Balance water
  • Temperature: 40 degC

Typical problems

  • Frequent cleaning required and sensor should be robust.

Remedies

  • Use of specialized cleaning

Product Recommendations

Measurement System

Process Liquid Analyzer: 

  • 2-wire FLEXA pH/ORP Analyzer

Features

  • Dual sensor measurement on 2-wire type analyser
  • Indication of sensor wellness

 

  • 4-wire PH450G pH/ORP Analyzer

Features

  • Easy touchscreen operation
  • Trending display up to 2 weeks
  • Advanced Process Temperature Compensation

Sensor Selection:

Option #1:

Sensor:

  • SC25V sensor series from Yokogawa is the perfect sensor for this application. High temperature sensor SC25 because of its design can serve purpose.

Features SC25V

  • External titanium Liquid Earth
  • Pt1000 integration in pH compartment giving highly accurate temperature compensation
  • CIP and Steam cleaning possible
  • Large internal KCl volume giving the sensor a longer life time
  • SC25V-ALP25 for the harsh applications and high temperatures

Cable:

  • WU10-V-S series

Fitting:

  • RF20H PH REATRACTABLE HOLDER

The retractable holder RF20H is made for installation of Ø12mm sensors on tanks or pipelines where the sensor has to be removed without interruptions or shutdowns and in the hash applications where frequent cleaning is of vital importance for a good pH measurement.

The retractable fittings installed with a suitable process connection to a containers or pipe. In order to adapt to the various process connections, the retractable fitting RF20H is made of high-grade metal or plastic. In addition one can choose between different process- and flush port connectors, sealing materials and sensors

  • RF20M PNEUMATIC CONTROL UNIT

The pneumatic control RF20M is a pneumatic control unit for retractable fittings such as the RF20H.  With this control unit it is possible to drive the retractable fitting into the positions “maintenance” and into the position “Service” and again back. The reached position is acknowledged over pneumatic feedback and show on the cabinet by lamp indicators. With the use of pushbuttons, Pneumatic valves can be opened and close for the control of rinsing solutions and draining. When the pushbutton is activated, pneumatic signals are produced, which opens the rinsing- and drain valve.

Features

  • Robust design
  • "plug and play” installation and connections
  • Up to 2 different cleaning solutions can be controlled
  • Detection of holder position
  • Driven by air at 6 bar
  • No electrical installation necessary

Note: This is a non-standard product.  Please contact your local Yokogawa Process Liquid Analyzer Department for the availability.

Option #2:

(Example of codification mentioned)

Sensor:

  • PH8EFP-05-TN-TT2-N-G*A/PF/HA/TF

PH8EFP standard Ryton pH sensor is solid electrolyte pH sensor. With the body made of Ryton, a strong engineering plastic, which is comparable to Teflon in terms of corrosion resistance and heat resistance, it allows for a wide range of applications. The integrated-sensor design simplifies calibration with standard solutions and maintenance.

Holder:

  • PH8HS3-PP-03-C-YP*C/SC

The EXA AUTO CLEAN chemical cleaning pH measuring system incorporates an intelligent pH converter that provides advanced sensor diagnostic functions. This measuring system features automatic chemical cleaning of the pH sensor as well as highly-reliable pH measurement; thus, it successfully meets an increasing need for accurate, reliable, and maintenance-free measuring systems.

pH level in rivers, and so on. Generally, pH sensors are subject to aging due to contamination and deterioration, and require periodic cleaning to maintain their performance. The EXA AUTO CLEAN chemical cleaning pH measuring system solves this problem, while facilitating labour savings and eliminating dangerous operations at the job site.

Functions: Moves the pH sensor up or down using an air cylinder, and provides facilities for chemical cleaning.

Tangible benefit

Save down time in cleaning, repeated calibration, improve end product quality.

 

Note: For additional information on this application contact the local Yokogawa Process Liquid Analyzer Department

 

Przegląd:

Introduction

cobb1Paper is used in a broad array of products essential for everyday life, from newspapers, books, magazines, printing, writing papers to cardboard boxes and bags, paper napkins, sanitary tissues etc. We are daily surrounded by paper products.

The most important use of paper is writing. The quality of paper used for printing or writing should be good and it depends on many parameters. One of the parameters is Cobb, which needs to be controlled.

What is Cobb Control?

Cobb control is nothing but the control of quality and binding of pulp in such a fashion that whatever is written by any source such as ink, etc on paper it should not spread as well as leave its impression on back side of the paper.

How is Cobb Variation Minimized?

Cobb variation is minimized by maintaining pH of the pulp in the range of 5-6 pH. Before processing, the raw pulp pH is in the range of 7-8. This should be controlled and brought down to acidic range i.e. 5 to 6 pH. This is very essential for following reasons.

  1. This ensures proper binding of the fiber
  2. Cobb is controlled
  3. Further it also helps in maintaining paper 
machine run ability at head box.

How is Cobb Control Done?

Cobb control is done by addition of Alum (which is in the range of 2-3 pH) and rosin to pulp. When alum and rosin are mixed with pulp after a certain distance pH of the mixture is measured and if it is not in the desired range the transmitter will control the Alum dosing via controller so that pH of the pulp is maintained. Rosin on the other side has no such controlled action. It will be getting dosed to the pulp continuously in a specific quantity. It is the Alum whose dosing is controlled depending upon pH variations.

Application Overview

By installing pH loop in paper industry not only the Cobb control is done but also customer can achieve the following:

  1. 20% saving in Alum consumption
  2. Eliminate corrosion problem in approach flow 
pipelines, pumps and other equipment. This is because if alum dosing is not controlled, there are chances that more Alum is dosed and it can lead to corrosion of pipes and components.

Summary

Measurement points:

After Rosin tank:

cobb2

Typical problems: Cleaning of sensor in such installations

Remedies: Using retractable fitting this optimum level of pH can be achieved by using Yokogawa's 4-wire pH Analyser with suitable retractable fitting and sensor. Our manual retractable fitting PR10 with Titanium ball valve is designed for use in pulp industry where frequent
cleaning of the sensor is required. For cleaning one has to take out pH sensor, close the ball valve so that the sample will not come out, clean the sensor, open the ball valve and then put back the cleaned sensor. The pH sensor will be a combination electrode having double junction electrodes, which provide long time stability and a prolonged lifetime. In our 4-wire pH analyser on 2nd mA output we have PI control facility. The speed of the alum dosing pumps can be controlled as per pH variations with the help of this feature.

Noty aplikacyjne
Przegląd:

Brewery is facility to produce beer. Breweries process is the manufacturing process of beer, which is a fermented beverage with low alcohol content made from various types of grain. Wheat, maize and other grains can be used for this. Brewing process starts from malted barley that is to form a mash by milling and mixing with hot water. The malt starches are converted to sugars during this process. This sugar rich water is then strained through the bottom of the mash and will be called as "wort". Then the wort will be brought to boil by bringing to the brew kettle. For bitterness or aroma hops are to be added at different times during the boil. Then the wort is cooled and aerated. And brewers yeast is added for fermentation. From the sweet wort the yeast produces carbon dioxide, alcohol and other byproducts. The GREEN BEER undergoes maturation after fermentation. Filtaration and carbonation are the last steps. Finally the beer will be stay in holding tank until it is bottled or kegged.

Przegląd:

After extraction from sugar cane or sugar beets, juice must be purified to remove the many other organics and minerals that accompany it.
 The processing to accomplish this is heavily dependent on reliable pH measurement and control as illustrated.

Przegląd:

Application Description

Many Ethanol plants running today are using a combination style pH electrode with a non-flowing reference to measure pH in the Mash Slurry transfer line from the Mash slurry mix tank to cook.  The Mash is being pumped out of the Mash Slurry tank is at approximately 82 °C and  2 to 4 bar (180 °F and 40 to 60 psig).

The original pH electrode systems that were installed during plant construction are online retractable assemblies and are mounted in orientations from completely horizontal to completely vertical and everywhere in between.

The Problem

The combination probe that is being used will typically drift out of calibration very quickly.  Also, the probe is damaged sometimes from excessive removal from the process.  The reason this probe drifts out of calibration is due to the fact that the non-flowing reference system plugs and becomes fouled by the mash passing by it.  pH measurements are only as good as the reference required to make this measurement.  If the reference is not doing its job, the measurement electrode will drift.

Process Overview

Product Recommendations

Yokogawa manufactures a multi-probe holder called the FF20 – flow through fitting or the FS20, which is pH chamber assembly with ½” NPT process connections.  With these holders we use a combination electrode, part number:  SC21C-AGC55 for measurement and reference and a separate temperature sensor part number: SM60-T1.  The Yokogawa electrode system works due to the fact that the SC21C-AGC55 combination probe uses a pressurized reference system.  By using plant air regulated to a KCl reservoir, the SC21C-AGC55 utilizes a positive flowing reference that does not foul. 

Plants using this system typically check the pH measurement against a grab sample and only make adjustments if the sample and the online measured values are more than 0.2 pH difference from one another.  Typically, the system will not need daily or weekly calibrations.  Most plants will pull the electrodes once a month for cleaning and calibration in a standard 4 and 7 buffer solutions.

Installation Considerations

The Yokogawa pH system is not retractable from the process.  It is usually best to put the Yokogawa pH electrodes in a by-pass or recirculation line that you can add isolation valves for isolating the probes from the process for maintenance and calibration.  The probe assembly should be mounted downstream of the Slurry Tank transfer pump.  Ideally it will be in a recirculation line going back into the tank or into the suction side of the slurry pump.

The picture below shows an installation that is actually flowing from left to right.  The arrows indicate the direction of the mash flow through the recirculation line and back into the suction side of the pump.  You will get an idea of the installation of the Yokogawa probes and the pressurized reference KCl reservoir from this picture.  The reservoir pressure is typically set 1 to 2 psig above the slurry line pressure.  The KCl reservoir will require refilling every 2-3 months for most applications

Note: For additional information on this application contact the local Yokogawa Process Liquid Analyzer Department

Przegląd:

Wastewater from electroplating facilities and certain types of chemical plants contains toxic forms of hexavalent chromium such as chromate and dichromate. The hexavalent chromium in this wastewater must be reduced before the water can be discharged. This requires a two-step process: hexavalent chromium (CR6) is reduced to trivalent chromium (CR3); and CR3 is precipitated as chromium hydroxide.

Industry:Electrical and Electronics

Przegląd:

 

 

Przegląd:

Introduction

Pigment producer manufacture produces pigments to supply to paints, plastics, inks, construction, textile and cosmetics manufacturers etc. The pigments come under wide range - general purpose grades, high performance, and specialist hard-to make colours and effect pigments.

Pigments and chemicals form an intrinsic part of many industries. They serve as raw materials in the manufacturing of Plastic, Rubber, Paint, Paper, Textile, Tiles, Detergent Powder and Soaps, Inks, and Photo Films etc.

Pigments come in a wide variety of colours and some are water-soluble. For these reasons, many of these compounds have been produced, isolated, and characterized.

Among the most important variables affecting processes, pH and temperature are environmental conditions with a strong effect on the pigments. Thus, it is very important to control them in industrial bioprocesses.

Balancing the pH

The degree of acidity or alkalinity of a solution, known as pH, is measured from 0 to 14. Acid solutions measure 0 to 7. Alkaline (smells like ammonia) solutions measure 7 to 14. Pure distilled water measures 7. There are instruments to measure pH, or you can rely on sense of smell. The binder should have a slight ammonia odor. We are shooting for a pH range of 8.0 to 8.8. The acrylic polymer used to make paint becomes unstable at a pH below 7.5. Adding a dispersion may lower the pH below the optimum range. Also, adding thickeners will typically lower the pH. If polymer binder starts looking and acting like cottage cheese then chances are pH is too low. Try raising the pH to salvage the batch. Do this with the drop-wise addition of Ammonium Hydroxide (NH4OH) while mixing. If the mixture does not respond to the pH correction, allow it to dry out for disposal.

Controlling Viscosity and Rheology

Thickness or viscosity is generally well understood. Rheology usually bears a bit of explanation. Long rheology refers to a stringy, resinous, quality, like that of honey. Industrial enamels and automotive paints often exemplify these qualities. Short rheology refers to a smoother, less "ropy" paint formulation, typical of what acrylics and oil paints are known to be. To create different rheologies, you can choose the appropriate gel or medium to combine with the dispersion. These are pH sensitive polymers that swell up when the paint's pH is 8.0 - 9.5 (It is critical to keep the paint in this range.)

Ammonia is used to maintain the pH in the acceptable range. Ideally, this is determined with a pH meter, and is characterized by a slight ammonia odor. You will feel the mixture get thicker as you proceed. (If you are getting chunks it may be a result of adding the Thickeners too quickly or insufficient mixing.) Blend until the mixture is smooth and of the desired thickness.

Typical Process details as an example:

Typical problems 

  1. What is the concentration of these chemicals?
    • Customer may say it is difficult to give concentration of these chemicals.
  2. What is the process pressure?
    • Process pressure: atmospheric pressure
  3. Calibration frequency
    • Once in a day. Customer has observed drift of @1 PH every day i.e. why calibration is done daily.
  4. Scaling?
    • Yes scaling shall be observed on electrode
  5. CIP/SIP
    • No.
  6. Typical sensor life @1 1/2 months to max. 2 months
  7. Process temp.
    • varies from -5 to +105 deg C, typical batch process temp. will be 95 degC (changes from manufacturer to manufacturer)

Remedies

  • Use sensor with most chemically resistant Ryton body.

Product Recommendation

Measurement System

Process Liquid Analyzer: 

2-wire FLEXA pH/ORP Analyzer

Features

  • Dual sensor measurement on 2-wire type analyser
  • Indication of sensor wellness

 

  • 4-wire PH450G pH/ORP Analyzer

Features

  • Easy touchscreen operation
  • Trending display up to 2 weeks
  • Advanced Process Temperature Compensation

Sensor Selection:

pH immersion fitting like PH8HS / equivalent with PH8EFP sensor.

Features

  • With the body made of Ryton, a strong engineering plastic, which is comparable to Teflon in terms of corrosion resistance and heat resistance, it allows for a wide range of applications.
  • The integrated-sensor design simplifies calibration with standard solutions and maintenance.
  • The pH glass electrode of a pH sensor, the platinum or gold electrode of a ORP sensor and junction can be individually replaced.

Tangible benefit

More reliable and accurate analysis of pH which helps to improve end product quality and total operation cost is less.

Note: For additional information on this application contact the local Yokogawa Process Liquid Analyzer Department

Przemysł:
Noty aplikacyjne
Przegląd:

Fish perform all their bodily functions in water. Because fish are totally dependent upon water to breathe, feed and grow, excrete wastes, maintain a salt balance, and reproduce, understanding the physical and chemical qualities of water is critical to successful aquaculture. To a great extent water determines the success or failure of an aquaculture operation.

Przegląd:

Background Information

The core of the activated sludge process is primarily dependent on the control of the aeration basin. The most essential component of any activated sludge plant is the biomass, anaerobic and aerobic bacteria, that attaches themselves to the waste, and digest the waste resulting in relatively clean water as the by-product.

There are several types of bugs that are responsible for different duties. There are the carbon eaters (carbonaceous) and chemical eaters like ammonia (nitrogenous). Just like any other living organism they need certain conditions in order to sustain life and reproduce.

basin1

Introduction

Many components in a process must be in balance in order to obtain complete synergy; example biomass blends, air, return activated sludge (RAS), waste activated sludge (WAS) and throughput. The aeration basin is a holding and/or treatment pond that everything cycles through. It is essential to monitor and control several factors that can influence the efficiency of the biological conditions in the basin; for example:

Temperature: Normally the temperature will be between 10- 40°C. Most biomass bugs achieve optimum efficiency in this range. Increasing or decreasing the temperature can result in the increasing or decreasing the rate at which the bugs eat and reproduce. Along with this all chemical reactions that are taking place at the same time are affected by the process temperature as well.

pH: For most systems the pH should be kept between 6.5 to 8.5 pH, when the pH is too high or too low, the biomass losses the ability to convert the food to energy and raw materials. A pH below 6.5 may cause the growth of fungi and fungal bulking, and will have to be adjusted using a caustic, lime or magnesium hydroxide.

Low Nutrients: If nitrogen and phosphorus are not presented in sufficient amount it can limit the growth rate of the biomass. A sign of nutrient deficiency includes foam on the aeration basin.

Dissolved Oxygen: DO is one of the most critical points of measurement; for most processes the target concentration will be between 1-3 mg/L. The concentration amount is an indication of the basin environment; whether it is in denitrification (excess nitrate, NO3) or nitrification (excess ammonium, NH4) environment. Essentially the DO measurement is set to a level to minimize the ammonium breakthrough. It is not uncommon to see NH4 and DO measurements together.

The DO measurement should be maintained at the point of greatest oxygen demand in the system. Normally this is near the intake portion of the aeration basin, because when the process is in the secondary clarifier no oxygen is added and the biomass bugs are starved of oxygen. When the process is returned to the aeration basin via the RAS pumps the biomass is returned to an oxygen rich area and the bug consume vast amounts of oxygen right away.

Septicity/Toxicity: Septic wastes contain elevated amounts of sulfides and organic acids (such as acetic acid).Other organic materials and heavy metals are also toxic to the biomass, reducing their efficiency or even destroying them.

basin2

Summary

Having too much oxygen in the process is not a problem for the biological system; however the cost for generating the oxygen is one of the largest expenses. By obtaining a good representative average of the dissolved oxygen present in the basin could save the plant large amounts of money. For this reason multiple measurements points are sometimes put into place.

Dokumentacja
Przegląd:

To facilitate the accurate measurement of pH, and its presentation as a scale, a range of "standard liquids" or "buffer solutions" are used. These liquids, whose constituents are accurately defined, have known stable values. Although in the preceding text the relationship to hydrogen ions has been made, research has shown, that the activity of hydroxonium ions (H30+) is more relevant.

Przegląd:

The lifetime of a pH sensor has a significant impact on the overall annual costs of a pH measuring loop. Optimizing four key factors will decrease these costs and optimize process control and overall plant efficiency.

Instrukcje

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