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Processed materials: liquid urea
Dissolution of urea
Our client is company specializing in the transport of raw materials for the energy sector (coal, lime, urea). For several years, it has been delivering liquid urea to power plants. This liquid urea was imported. Our customer approached Palamatic Process to study the feasibility of manufacturing its AdBlue directly on site. The study carried out by Palamatic's engineering team showed that it was ecologically and economically preferable to make this investment.
Liquid urea or AdBlue is used in combustion engines or industrial combustion plants to reduce emissions of nitrogen oxides (NOx). This process is called selective catalytic reduction (SCR) and converts NOx into nitrogen dioxide N2, water and carbon dioxide CO2.
After the Preliminary Project Summary (PPS), it took several months of studies and manufacturing to achieve the FAT in our workshops. After validation of the automatic operation of the process, the Palamatic Process teams went on thier site to install the equipment on site. The Palamatic automation specialists finished commissioning this production unit of AUS 32, AUS 36 and AUS 40 and stayed for a few more hours to validate the fully automated operation of this process.
The 500m² facility consists of the production unit, polypropylene and HDPE storage tanks and storage of solid urea big bags.
The water is treated by an osmosis unit to obtain demineralized water, which is essential for the production of AdBlue. It is then stored to meet process consumption. Heating is carried out by a combination of high-efficiency heat pumps and solar panels. This equipment is specially designed to withstand tropical storms. The hot water storage silo is equipped with an immersion heater to maintain the tank temperature. The piping, entirely in 316L stainless steel, was made by a local partner specializing in food-grade welded piping.
The heart of the process is the dissolution of urea to produce AdBlue and AUS 40:
- Water is injected into the tank. A flowmeter provides real-time information on the quantity of osmosis water injected. Temperature sensors are used to manage the heat of the injected liquid.
- The urea is dosed by a precise and complete system. The operator cracks the carbamide big bags on the big bag emptying station with knives. An IoLink luminous cylinder shows the user the quantity of urea remaining in the buffer hopper. A lump breaker guarantees the absence of lumps in the product. The stainless-steel blades reduce lumps to powder. The feeding of the weighing hoppers is carried out by a cascade of tubular screws and a bucket elevator. This modular conveyor system allows the powder to be transported over a large distance and a great height.
The urea dissolving tanks are fitted with vertical agitators with anti-vortex blades. These urea mixers guarantee very high mixing homogeneity and fast dissolution.
At the end of each dosing operation, clean in place nozzles (CIP) wash these hoppers with hot demineralised water.
The urea dissolving tanks are provided with vertical agitators with anti-vortex blades. These urea mixers guarantee very high mixing homogeneity and fast dissolution.
The mixture is monitored by a urea concentration sensor that indicates the actual mass percentage of urea in the solution. 32.5% urea and the customer gets AdBlue and 40% urea to get AUS40. All sensors are connected to the PLC via a full IoLink system. This system makes it possible to replace huge terminal blocks of several dozen wires with a simple Ethernet cable. The sensors are very easy to configure. This is a real gain for maintenance and day-to-day use.
At the end of the mixing process, a leak-proof, magnetically driven pump empties the mixing tank at high speed. Its high pressure means that the urea can be filtered in a filter skid. The different filtration stages limit the clogging of the filters. The customer has real time access to the clogging level of his liquid filtration system on the supervision.
The entire installation is controlled by PalTouch® technology supervision. Each probe, each pump, the various bulk conveying equipment is controlled on a central console. This system also permits immediate access to the system by Palamatic's after-sales service. The automation engineers can help the customer in the optimization of his process.
After filtration, the urea is stored in two large High-Density Polyethylene (HDPE) tanks awaiting transport to the power plant. Loading is carried out by means of the loading arm of the tanker truck. This loading step is also automated and supervised by the main control screen.
