A blog specializing in pressure, temperature, level and flow instrumentation, control valves, process analyzers, and all other areas of process measurement. Courtesy of Miller Energy, a New Jersey, New York, Pennsylvania, and Ohio process instrumentation Rep and Distributor.
Process Refractometers for Water Treatment Chemical Concentration Monitoring
INTRODUCTION
Pure water treatment removes undesirable chemicals, biological contaminants, suspended solids, and gases from raw water. Water purification aims to produce water for a specific purpose, such as human consumption and medical or industrial use.
Polyaluminium coagulants are increasing use in potable water treatment plants, particularly for soft, colored surface waters. Polyaluminium chloride (PACl) is gradually replacing Alum (aluminum sulfate), a commonly used coagulant in water treatment plants. Alum coagulates at a limited pH range (between 5.5 and 6.5) and often requires alkali to the raw water to achieve the optimum coagulation pH. Furthermore, the alum floc produced is particularly fragile, which is vital if a coagulant is required to maximize color removal in a microfiltration-based water treatment process.
APPLICATION
Water treatment by chemical precipitation is a complex process. It starts with adding flocculants, specifically, Polyaluminium Chloride (PACl) and Sodium Hydroxide (NaOH). PACl is a synthetic polymer dissolved in water. It precipitates in big volumetric flocs, which absorb suspended pollutants in the raw water. The turbidity of the raw water defines Polyaluminium Chloride quantity. PACl concentration must be higher than 10 % To keep the flocculation process smooth. Polyaluminium Chloride is stable in the storage tank; however, it tends to crystallize after some time. Vaisala K-PATENTS® refractometer monitors the concentration of PACl to inform about the need for tank or pipe cleaning, thus preventing blockage caused by the PACl crystals.
NaOH regulates pH level, increases alkalinity, and neutralizes acids in the water. In alkaline water, the coagulation and flocculation processes work more effectively. Moreover, sufficient alkalinity prevents dissolving the lead from pipes and pipe fittings and reduces the corrosive effect of the water to iron pipes.
Further, particles suspended in water start to precipitate and agglomerate to form larger particles, known as flocs. The flocs are then settled at the bottom, forming sludge, and then removed from the process. After separating most of the floc, the remaining suspended particles and unsettled floc get filtered to remove water.
In the filtration phase, the water goes through the layers of anthracite, sand, and gravel. As a result, organic compounds contributing to taste and odor get removed. Other remaining particles get trapped by adhering to the sand and gravel particles.
After harmful micro-organisms get removed through filtering, it is necessary to add disinfecting chemicals to the water to inactivate any remaining pathogens and potentially harmful micro-organisms. One of the disinfecting chemicals used is Sodium Hypochlorite (NaOCl). When dissolved in water, this chemical releases chlorine, which is an efficient and safe disinfectant if added in a sufficient amount. Apart from sodium hypochlorite, liquid chlorine and chlorine dioxide are also choices as disinfectants.
Fluoride may also be added to the water to reduce tooth decay and prevent chronic diseases. However, fluoride in the water must not exceed recommended levels. Excessive levels of fluoride can be toxic or cause undesirable cosmetic effects such as staining of teeth.
Sodium Hypochlorite is unstable and quickly decomposes. The stability of NaOCl solution is dependent on the following factors:
- Hypochlorite concentration
- The temperature of the solution
- PH value of the solution
- The concentration of the impurities during catalyzing decomposition
- Exposure to light
With the process refractometer, it is possible to monitor NaOCl concentration and control the disinfection conditions.
The water purification disinfection stage happens in the disinfectant basin. Then, corrosion control assures the high quality of the purified water. Finally, the pure water gets stored for further consumption.
INSTRUMENTATION AND INSTALLATION
Vaisala K-PATENTS® Teflon Body Refractometer PR-23-M provides in-line measurements of Polyaluminium Chloride and Sodium Hydroxide at the initial stage of purification, ensuring the efficient flocculation of undesired particles. In addition, through the measurement of Sodium Hypochlorite and Fluoride at the water disinfection stage, high-quality purified water at the outlet is assured.
Refractometer installations happen in three different points in a by-pass loop between each chemical tank pump outlet and the treatment point. The refractometer allows monitoring the chemicals concentration at the exit from the storage tank to the pipe treatment point.
Typical measurement ranges are:
- PACl is ca. 10-11 %
- NaOH is ca. 40-45 %
- NaOCl is ca. 8-12 %
https://millerenergy.com
800-631-5454
How Does a 250:1 Turndown Improve Your Bioprocess Performance?
How Proper Level Instrumentation Can Alleviate Foam Headaches
Foam is at times present in liquid tanks used in the chemical, manufacturing, food and beverage, life sciences, and other process industries. Because of foam's fluid nature, there is no such thing as a "one-size-fits-all" level measurement solution. It's essential to understand the foam's characteristics and understand what form of measurement is needed. The foam may develop in a tank for several reasons, such as introducing air or gas into the liquid or the activity of agitators/mixing blades. Regardless of the source, caution is required when selecting a level measurement technology to avoid potentially costly errors.
Magnetrol, a world-leading manufacturer of level instrumentation, authored a white paper that aims to go through the challenges that foam presents and overcome them by recommending proper instrumentation.
In New York Metro and Northern NJPhone: 800-631-5454
In Eastern Pennsylvania and Delaware:
Phone: 610-363-6200
https://millerenergy.com
Cashco Sanitary / Hygienic Regulators and Control Valves
Sanitary Reducing Regulators
Sanitary Back Pressure Regulators
Sanitary Control Valves
Controllers
Sanitary Blanketing Valve
United Electric Controls 12 Series Pressure and Temperature Switches
SIL 2 Certified, vibration-resistant, 316 stainless steel pressure, differential pressure and temperature switches.
The United Electric Controls 12 Series hazardous location switches are suitable for challenging applications where space is limited. Snap-action Belleville spring assemblies provide vibration resistance and extended switching life. The 316 stainless steel enclosure and the hermetically sealed switch provide robust environmental protection. Approved for use in hazardous environments, the 12 Series outperforms the competition in applications ranging from refineries to chemical plants, rotating machinery, and more.Phone: 800-631-5454
In Eastern Pennsylvania and Delaware:
Phone: 610-363-6200
https://millerenergy.com
The Thermo Scientific™ AquaPro™ Multi-Input Process Analyzer
Thermo Scientific™ AquaPro™ provides accurate, user-friendly in-line monitoring of process applications — from power generation to municipal water and wastewater.
The AquaPro™ is an on-line liquid analytical measurement platform that supports up to four sensors in an outdoor rated enclosure. The enclosure can be mounted in a ½ DIN panel, U-bolted to a pipe or mounted on a wall. The large color graphics display makes it easy to view measurements over a wide range of environmental conditions. There is a USB data port that is accessible from the front panel to transfer data, auto-configure the system setup or to upgrade the operating software with new features.
The Thermo Scientific™ AquaPro™ Multi-Input Intelligent Process Analyzer provides accurate, user-friendly in-line monitoring of process applications — from power generation to municipal water and wastewater.
The AquaPro™ Multi-Input Intelligent Process Analyzer is far more than a 4-wire multi-input meter. It is a sophisticated and highly flexible analysis platform for a wide range of process applications.
To download the AquaPro™ brochure, click this link. For more immediate information, contact Miller Energy:
In New York Metro and Northern NJ
Phone: 800-631-5454
In Eastern Pennsylvania and Delaware:
Phone: 610-363-6200
In Western Pennsylvania:
Phone: 412-257-0200
In Ohio:
Phone: 440-735-0100