The implementation of BS-IV norms from the year 2010 brought in its wake a switchover to using the selective catalytic reduction (SCR) system which further brought into use a product called AdBlue®. The following article highlights the salient features of this compound.
From April 1, 2010, BS-IV norms were introduced in 13 cities, namely, Delhi (NCR), Mumbai, Chennai, Kolkata, Bengaluru, Hyderabad, Pune, Ahmedabad, Surat, Kanpur, Agra, Lucknow and Solapur. From October 1, 2015 other States were brought into the fold, including Jammu and Kashmir (except Leh and Kargil), Punjab, Haryana, Himachal Pradesh, Uttarakhand and certain districts of Uttar Pradesh and Rajasthan. Further, from April 1, 2016, those included were Goa, Kerala, Karnataka, Telangana, Odisha, Union Territories of Daman and Diu, Dadra and Nagar Haveli, Andaman and Nicobar Islands and certain districts of Maharashtra and Gujarat.
Finally, from April 1, 2017 all new on-road vehicles have mandatorily switched to BS-IV technology. By 2020, there is a plan announced by the government for nationwide implementation of BS-VI. In this regard, EGR (exhaust gas recirculation) and SCR (selective catalytic reduction) are the technologies available to meet BS-IV emission norms. EGR works by re-circulating a portion of an engine’s exhaust gas back to the engine cylinders to reduce NOx. SCR is also an emission control technology to clean NOx from the exhaust gases. In 2006, the European heavy-duty diesel market implemented SCR technology to enable trucks to meet the Euro IV and V limits.
An SCR system uses AdBlue®, a synthetically produced solution, to reduce NOx to water vapour and atmospheric nitrogen. It is more fuel-efficient than EGR technology to the tune of 3-5%. It is an after-treatment technology that treats exhaust gas downstream of the engine. The main purpose is to reduce the level of NOx emitted from the engines. Small quantities of AdBlue are injected into exhaust upstream of a catalyst, where it vaporises and decomposes to form ammonia and carbon dioxide. Ammonia (NH3) is the desired product which, in conjunction with the SCR catalyst, converts NOx to harmless nitrogen (N2) and water (H2O).
About AdBlue®
AdBlue is a registered trademark for AUS32 or aqueous urea solution, ISO 22241 certified and owned by the German Association of the Automotive Industry (VDA). The right to use the name AdBlue can only be acquired by a license. It is a non-toxic, crystal-clear and synthetically produced solution used in a SCR system to reduce oxides of nitrogen (NOx) emissions from exhaust of diesel vehicles. It is carried in an additional tank that is fitted by the vehicle manufacturer. VDA QMC is a certifying body which audits the plants of suppliers and certifies them to use the AdBlue brand name. For using the trademark, an AdBlue supplier should hold a VDA license.
SCR and AdBlue
SCR technology allows much greater NOx conversion efficiency, thereby allowing the engine to be fully optimised, which also contributes to fuel economy improvement. Heavy duty engines utilising SCR provide substantial fuel economy improvement, estimated at 3-5%. Another benefit to the improved fuel efficiency is less frequent diesel particulate filter (DPF) cleanout, thereby further reducing costs. AdBlue should be procured from a licensed VDA manufacturer only. Vehicles that use AdBlue have indicators on the dashboard that alert the driver of the quantity of this solution on board. A gauge similar to a fuel gauge indicates the level at all times. If a vehicle is operated such that one would run completely out of AdBlue, vehicle power gets reduced, thus making it compulsory for the driver to refill the tank.
Consumption
AdBlue consumption is expected to be approximately 4-6% of fuel consumption. It may vary depending on vehicle operation, duty cycle, geography, load ratings, etc. Normally the AdBlue tank capacities are 28-55 litres. Depending on the consumers’ requirement it is supplied in various pack sizes such as 20, 26, 210 and 1,000 litres. Bulk supplies are available for large consumers. Since it is corrosive in nature it cannot be stored in materials like copper, nickel, zinc, mild iron or aluminium. Old diesel or oil containers should not be used to transfer AdBlue into the tank. Dedicated equipment should be used to handle it as even a small contamination of fuel, oil or lubricant can damage the SCR system of the vehicle. If by mistake AdBlue is filled into the diesel tank or diesel is filled into the AdBlue tank, it is advisable not to start or move the vehicle. The tank will first need to be totally drained in such a situation.
Storage and usage
AdBlue manufacturing has strict requirements and the purity of ingredients is critical to the proper functioning and longevity of the SCR system. A wrong solution could damage the SCR system and cause issues in its functioning. Hence, it is advised to buy AdBlue from a certified manufacturer. If foreign particles accidentally enter the AdBlue tank the SCR system will recognise solutions other than AdBlue and an indicator light will notify the driver. Depending on the level of contamination in the tank, the vehicle may require servicing. AdBlue needs to be stored in a dry, well-ventilated, properly covered area without direct exposure to sunlight. The optimum storage temperature is 25 degrees Celsius. Temporary exposure to higher temperature has little to no impact.
Being a corrosive liquid, it should only be stored in approved materials like high-density polyethylene (HDPE) or stainless steel. AdBlue should not be packed in plastic with additives or nonferrous metals and its alloys and carbon steel. The recommended storage temperature for the solution is between -11 degrees Celsius to 30 degrees Celsius. At constant temperatures of up to 30 degrees Celsius, the product will last for a minimum of 12 months while this would be reduced to six months if stored at 35 degrees Celsius. At locations with higher ambient temperature, AdBlue tanks should be insulated or stored under shade with proper ventilation.
Multiple solutions are available for dispensing AdBlue from packing material or storage tank to the AdBlue tank in a vehicle. A small plastic spout is available with Velvex AdBlue® buckets, thus making it easy to dispense the solution to the tank. A specially designed motorised pump helps provide speed to refill the AdBlue tank. Just like oil pumps, the manufacturer provides hand rotary pumps of stainless steel or PP for dispensing AdBlue from a barrel to its tank. Being a pioneer in providing AdBlue in India, NPL BlueSky is also able to provide tailor-made solutions for large customers suitable to their requirement.