Manufacturing of Urea: Process, Preparation, & Applications of Urea

Manufacturing Process

The raw products which are utilized in the urea production procedure are ammonia and CO₂ hence normally urea is made in an ammonia plant due to the fact that it yields ammonia as a product and carbon dioxide as a by-product and this CO₂ can be used straight for producing urea. Two reactions are primarily associated with the process:

The reaction of Ammonia and CO₂to form Ammonium Carbamate.

2NH₃ + CO₂ → NH₂COONH₄

Preparation of Urea

Dehydration of ammonium carbamate gives urea.

NH₂COONH₄→ H₂O + NH₂CONH₂ (urea)

Liquid ammonia is pumped and CO₂ is compressed and carried to equipment called a reaction chamber. Given that this is where the reaction takes place, it is the heart of the process. The pressure and temperature level are kept at 14 Mpa and 170-190 ° C for the first reaction to occur. The reaction of ammonia and CO₂ is highly exothermic in nature. The majority of the heat released is used in form of process steam wherever it is needed to process.

The conversion of the reactants to urea can be increased by increasing the amount of CO₂, if CO₂ is present in excess then the conversion can be as high as 85% per pass however enhancing for the proper temperature level, pressure and design is a difficulty in itself thus usually per pass conversion are kept around 50%. The unreacted materials are recycled resulting in a general conversion of over 99%. This minimizes the effects on the environment.

The concentration of Urea Solution

The urea solution is concentrated in an evaporation chamber where water is vaporized by heating with steam under vacuum in two evaporation stages whereby 99.7% urea melt is obtained. It is then pumped into the prilling tower.

Prilling

The molten urea is passed through nozzles inside the prilling tower. Compressed air is passed in the tower so that its flow is counter-current with respect to that of molten urea. The urea gets solidified in the prilling tower and air assists in shaping it in the form of prills or granules. The urea is then kept and ready to be sold and used.

Applications of Urea

• More than 90 percent of world urea production is destined for use as a nitrogen-release fertilizer. Urea has the greatest nitrogen content of all solid nitrogenous fertilizers in common use (46.7%). For that reason, it has the lowest transportation expenses per unit of nitrogen nutrient.
• Urea is a basic material utilized in the manufacture of numerous essential chemicals, such as:

1. Different plastics, especially the Urea-formaldehyde resins.
2. Numerous adhesives, such as Urea-formaldehyde or urea-melamine-formaldehyde utilized in marine plywood.
3. Potassium cyanate, another industrial feedstock.
4. Urea nitrate, a dynamite.

Other commercial uses are:

• A stabilizer in nitrocellulose dynamite.
• A component of animal feed, offering a fairly low-cost source of nitrogen to promote development.
• A flame-proofing agent, commonly utilized in dry chemical fire extinguisher charges such as the urea-potassium bicarbonate mix.
• A component in dish soap.
• Urea is utilized in topical skin-related medicines to promote rehydration of the skin.
• Urea is a safe, non-corrosive fertilizer alternative for de-icing.

Environmental pollution due to urea manufacturing

Urea production might trigger a number of environmental pollution issues. These problems happen due to bad maintenance of the plant, leaking of toxic products to the natural environment, and more.

Ammonia is a very toxic gas. Ammonia gas can be dripped from the urea factory to air or water if the plant is not kept efficiently. It can cause health problems for people and animals. Ammonia can be oxidized to oxides of nitrogen.

If the coral is used to get limestone, it is triggered by coastal disintegration.

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