Ammonium nitrate (NH4NO3) is a versatile salt composed of ammonium ions (NH4+) and nitrate ions (NO3-). It plays a crucial role in the explosives and fertilizers industries and is also used in the treatment of titanium ores.

The Ammonium Nitrate Production Process

Ammonium nitrate is produced by reacting nitric acid with ammonia. The resulting solution is concentrated to 97.5-98% in a final concentrator. This concentrated solution, along with quality additives, is then fed into a prilling tower where small pellets of ammonium nitrate are formed. Some of the concentrated solution is also gravity-fed into a slurry tank.

In the slurry tank, the filler is dispersed, and the oversize and small fines are melted. The 97.5% ammonium nitrate solution from the concentrator is discharged, and the moisture content of the mixture is adjusted by adding scrubbing liquor. The slurry is then conveyed through a hot air atomizing system to form tiny droplets, which are sprayed onto a curtain of falling granules from the prilling tower.

Ammonium Nitrate Application & End Products

The primary end products of ammonium nitrate production are fertilizers and explosives. The production process involves several stages, including the formation of pellets in the prilling tower, classification into fractions, and cooling in a fluidized bed cooler. The cooled ammonium nitrate is treated to prevent caking during storage, typically by spraying a liquid coating agent made of oil and amine in a rotary drum.

Process Refractometer Instrumentation & Installation

The Vaisala Polaris® Process Refractometer PR53GP is essential for continuous monitoring of the ammonium nitrate process. It is installed on the concentrator and slurry tank outflows to ensure a uniform prill and prevent the need for reprocessing. Traditional methods of calculating concentration based on nuclear density and paper charts are often confusing and time-consuming. In contrast, the refractometer provides a direct measurement of ammonium nitrate concentration, which can be sent to the control room via Ethernet or 4-20 mA output signals. This real-time data allows operators to make immediate adjustments to the process.

Refractive Index Measurement Range and Accuracy

The refractometer measures the refractive index (nD) in the range of 1.3200 – 1.5300, corresponding to 0-100% by weight. The concentration of the outflow NH4NO3 solution is typically 90-98%, with process temperatures ranging from 160-180ºC (320-356ºF). In the slurry tank, the NH4NO3 solution concentration is also 90-98%, with temperatures between 150-160ºC (302-320ºF). The typical measurement range is 60-100% NH4NO3, with an accuracy of 0.2% NH4NO3. An automatic prism wash with steam may be required for this application, and appropriate equipment with hazardous and intrinsic safety approvals is available when needed.

Optimizing ammonium nitrate production processes with refractive index technology ensures high-quality end products and efficient operations. The Vaisala Polaris® Process Refractometer PR53GP provides reliable, real-time measurements that are crucial for maintaining the desired concentration levels and making necessary adjustments promptly.
For more information, please contact us.

 

Ethylene Glycol, with the chemical formula (CH2OH)2, is a versatile compound used in various industries. Its typical end products include synthetic fibers, thermoforming applications, engineering resins, and PET bottles.

The Importance of Polyethylene Terephthalate (PET)

Polyethylene Terephthalate (PET) plastic is a crucial material used to produce fibers and yarn, engineering plastics, photo and packing film, and beverage and food containers. The majority of the world’s PET production is for synthetic fibers (over 60%), with bottle production accounting for around 30% of global demand. In textile applications, PET is generally referred to as polyester, while in packaging, it is known as PET.

PET Production Processes

The production of PET involves reacting the monomers Terephthalic Acid (TPA) and Ethylene Glycol (EG) in the presence of a catalyst. However, not all the EG reacts during this process. The excess EG, along with other minor reaction products like Propylene Glycol (PG) and Triethylene Glycol (TEG), are recovered and recycled back into the reactor feed.

Measuring Process EG Concentration

Accurate measurement of EG concentration in the recycling line is essential to maintain the desired reactor feed level. The concentration of the EG feed significantly affects the quality and opacity of the polymer product.

Process Refractometer Instrumentation & Installation

The Vaisala Polaris™ PR53GP Process Refractometer is used to measure the concentration of Ethylene Glycol in the recycle stream. This measurement helps adjust the feed ratio of fresh EG to ensure the correct quantity is fed to the reactor. 

The typical measurement range is from 90% to 100%, with process temperatures ranging from 20ºC (68ºF) to 30ºC (86ºF). An automatic prism wash with steam is recommended for this application. Hazardous and intrinsic safety approvals are available when required.

With a robust, non-welded body construction suitable for demanding applications, the Polaris PR53GP Process Refractometer also supports an optional flange-mounted pipe flow cell  accessory for secure installation in various pipe sizes. Additionally, Vaisala Polaris process refractometers are Indigo compatible, offering expanded features such as data logging, wash control, settings adjustments, measurement parameters, diagnostics, and service updates.