Ultra BlastULTRA BLAST™ SLURRY BLAST With A DifferenceHIGHLIGHTSIn recent years, environmental concerns have lead to the development of various slurry blast systems for surface preparation. Currently there are five different generic systems in use: ULTRABLAST is a UHP assisted Wet Pot Slurry Blast system. ULTRABLAST utilizes water-pressurised pot instead of the conventional air pressurized blast pot. Water and grit is continuously mixed inside the pot to give a homogeneous flow of slurry. The ULTRABLAST also utilizes its uniquely developed air driven UHP pumps to generate pressurized water at 2,000 –3,000 bar. This UHP water is then used in the acceleration chamber. At the end of the blast hose the slurry mixture enters the UHP acceleration chamber where an array of UHP jets fires into the slurry mixture which exits the nozzle and impacts the surface with twice the energy of conventional blasting grit. DETAILSOVERVIEW - DPSB air compressor cost - WPSB air compressors cost (lower CFM than DPSB) - UHP-WPSB all the drawbacks and advantages of WPSB, in addition: - UHP-DPSB all the disadvantages associated with DPSB systems, but additional high cost of a UHP unit - ULTRA BLAST™ all the drawbacks and advantages of WPSB, in addition: In many European and American countries, environmental legislation has more or less forced contractors to introduce wet blast or slurry blast systems or to completely enclose the work area with ‘zero dust emission’ containment structures. Using these old style slurry blast systems for a while, contractors soon realized the additional cost implications and had to adjust their prices accordingly. An additional negative impact is that the oversized dimensions and complexity of these systems tend to make them excessively expensive and difficult to handle. Conventional dry blast systems consisting of a compressor, blast pot and blast hose with nozzle, now had to be expanded with a UHP pump unit with engine, tumble boxes (pressure control device), bulky nozzle arrangements and additional UHP hoses to the nozzle. All this together formed the old style UHP assisted slurry blast systems. Many ship owners refused to accept the resultant cost increase for only little positive effect and are taking their vessels to lower-cost countries for coating repairs. These countries have generally not (yet) adopted stringent environmental legislation and shipyards there continue to offer conventional surface treatment at much lower cost. Euroblast Middle East LLC took up this challenge by developing and introducing an abrasive blasting system that is far smaller in size, much easier to handle, much more cost-effective and environmentally friendly at the same time. Euroblast Middle East LLC chose to first introduced this product into a market which at present is not forced by legislation to adopt (expensive) environmentally friendly systems: Dubai, an emerging and fast growing market in the marine repair industry, was chosen as launch platform and the success here proves that the ULTRA BLAST™ system is economically viable. Typically the ULTRA BLAST™ system saved the contractor US$ 2.00 per square metre. The additional cost of the system above conventional blast pots were recovered within 1450 hours. This cost saving did not take into consideration disposal cost of blast grit. When using only 50 –60 % of the amount associated with dry blasting the additional saving is quite substantial. THE SECRET BEHIND “ULTRA BLAST ™” To understand the benefits we have to start in with the blast pot. A STANDARD DRY BLAST POT is pressurised at the same pressure as the blast air. The main reason why the abrasive flows out of the pot and into the air stream is the pressure differential (venturi effect) caused by the main air flowing through the mixing chamber underneath the abrasive metering valve. The abrasive particles, in extreme cases 560 kg per hour flowing at an right angle into the blast air, have to be accelerated from zero to a mean speed of ± 200 m/sec. 200 m/sec being the theoretical speed of 350 cfm air flowing, regardless of friction or other losses, in a 1 ¼ inch pipeline. This causes the blast air to loose a lot of its momentum and therefore the mixture of abrasive and air will start flowing down the blast line at a reduced speed. The “ULTRA BLAST ™” utilizes a water-pressurised pot with pot pressure 3 bar above blast air pressure. This makes the flow of abrasive and water into the air stream far more uniform and controllable. Secondly, the momentum loss of the air is reduced due to a smaller amount of abrasive that needs to be accelerated, typically 220 kg/hour. To help overcome this loss in momentum a further water jet is utilized to accelerate the abrasive particles from practically zero where it enters the air stream at a right angle to over 350 m/sec. The abrasive speed eventually drops back to an average speed of just under 200 m/sec With a STANDARD DRY BLAST POT the abrasive particles, which travels down the rubber blast hose moves very erratically, colliding against each other and the inner walls of the hose. As the abrasive comes in contact with the rubber hose, it decelerates due to friction and elastic deformation of the hose. The reaction force bounces the abrasive away from the inner wall and back into the main air stream. Further energy is then absorbed every time the abrasive needs to be accelerated and the mean abrasive speed keeps on reducing. The wear of the blast hose is a good practical indication of the amount of energy lost while the abrasive flows down the blast hose. The “ULTRA BLAST ™” system differs in such that the blast hose is lubricated with water clinging to the inside of the hose. Further, this system utilizes less abrasive and the particles are in turn encapsulated in a small water sphere. The water, acting as a lubricant when the abrasive collides with the inner wall of the blast hose, drastically reduces friction and therefore losses in momentum. This is visible as very low wear in the blast hoses. The combined effect of adding water to the abrasive is, that the abrasive arrives at the blast nozzle at a speed closer to the theoretical 200 m/sec. This explains why the WPSB- system is about 35 % more efficient than a conventional pot. By increasing the kinetic energy of an abrasive particle, one theoretically needs less abrasive to blast the same area. .The flow of abrasive down the blast hose is due to the pressure differential at the pot and blast nozzle. The “ULTRA BLAST ™” technology makes also use of UHP water jets, powered by our unique air driven UHP pumps, firing further downstream in the direction of the abrasive flow, which has two effects. Firstly, they induce a low pressure zone upstream from the jets which further increases the air & abrasive speed. Secondly, it accelerates the abrasive particles in its flow path to about 500 m/sec. When these jets are placed strategically before the blast nozzle, the inlet speed to the blast nozzle of the air and abrasive is more than doubled. Higher inlet speed induces higher exit speeds and therefore higher energy. This plus the fact that the venturi of the nozzle is less choked makes for more than a 100 % increase in productivity in some cases. Summarizing, Euroblast Middle East LLC feel confident to introduce the world’s first ever ultra-productive and practically zero-dust emission UHP-assisted abrasive blast system. “ULTRA BLAST ™ – putting “economy” where it counts – at the contractor’s bottom line! |