R@E;<K8@CT T :c\XeZiXebZXj\m\ek`cXk`fe @E;<K8@C R 8LK?FIJ1 G\iC]_fcd#J\e`fi;\m\cfgd\ek<e^`e\\i#Nikj`cGfn\iGcXekj# ;XeG\kk\ijjfe#DXeX^\i#DXib\k`e^DXk\i`Xcj#Nikj`cJ\im`Z\j# Af_XeeXM\jk\i^i[#8ggc`ZXk`fe<e^`e\\i#Nikj`cJ_`gGfn\i 8cci\Z`gifZXk`e^\e^`e\je\\[ to oil pollution in the close vicinity of device, Wärtsilä’s service interval ZiXebZXj\m\ek`cXk`fe%K_`j`jY\ZXlj\ the crankcase ventilation outlet and to requirement would be a minimum of f]k_\_`^_^Xjgi\jjli\`ek_\ increased lube oil consumption. 8000 hours and preferably 16,000 hours. ZfdYljk`feZ_XdY\i#n_`Z_ZXeefk During this time there should be no need Y\kfkXccpj\Xc\[f]]% :iXebZXj\\d`jj`fejc\^`jcXk`fe to change any filter insert, or for any For Wärtsilä, environmental solutions are maintenance. always the priority. The main source of Because the combustion chamber cannot emissions from a diesel or gas engine is Efficiency be completely sealed, a small amount of still the exhaust gas. However, as engines A droplet removal efficiency of more than gas escapes as “blow-by”, via the piston/ become cleaner and more efficient, and 95% is required. cylinder liner gap and the piston rings, into equipped with emission abatement the crankcase. In turbo-charged engines, systems, the relative impact of the Little or no consumables there is also blow-by gas entering through crankcase emissions increases. Wärtsilä’s environmental policy is to the shaft sealing in the turbocharger into Increasingly, new legislation such as clean minimize all kinds of waste filter inserts. the crankcase. Since the crankcase is air acts and environmental regulations, not designed for high pressures, it requires aim to limit or entirely prohibit crankcase Design a ventilation pipe to prevent pressure from emissions from reciprocating engines. This The device should not interfere with the building up inside. is already happening in certain segments operation of the engine, nor should it have Because the gas pressure is very high of industry, and it will also affect stationary any negative effect on its performance. during piston blow-by, it violently tears power generation and the shipping the lube oil from the walls, breaking it into industry in the near future. <mXclXk`fef][`]]\i\ekjfclk`fej very small oil droplets to form a fine oil mist. Based on the listed requirements, Wärtsilä These small oil droplets escape the crankcase Jpjk\di\hl`i\d\ekj has tested and evaluated many different via the ventilation pipe. This, in turn, leads Dealing with crankcase emissions might, filter products. Most of them have failed at first, seem like an easy task. The first to live up to their promises. However, one thing that usually comes to mind is to solution based on centrifugal separation, install some kind of filter to prevent the provided by Alfa Laval® showed very oil mist from escaping. As straightforward promising results, though it had to be as this sounds, there are a couple of adapted for the bigger Wärtsilä engines. facts that make filtering difficult. It was therefore decided to start a development project, and to scale-up this Maximum allowed crankcase pressure solution in co-operation with Alfa Laval. The crankcase has a large volume and a lot As a result of this development project, the of seals. Therefore, the maximum allowed PureVent™ oil mist separator was born. gauge pressure (over pressure) in the crankcase is 3 mbar. Most conventional K_\f`cd`jkj\gXiXkfi types of filter are not able to function The basic function of the oil mist separator properly with such a low pressure drop, is very simple (see Figure 2). Oily gas especially for longer periods of time. enters at the bottom of the separator. Because of the centrifugal forces, the air is Oil droplets size driven to the periphery of the disc stack The oil droplets are extremely small, most separating the heavier oil droplets from the of them being in the range of 0.2-2 μm. lighter gases by centrifugal separation. Their small size, in combination with the The cleaned gas, which is very clean since low crankcase gauge pressure, creates the process abates odour and smoke a challenge to filtering. emissions as well, exits the separator from the upper pipe connection. =`^%(ÆK_\f`cd`jkj\gXiXkfile`k Long service interval The separated oil is collected using a gfn\igcXekXggc`ZXk`fe % For any crankcase emission abatement specially designed and tested draining / `e[\kX`c MuHJI?BuJ;9>D?97B@EKHD7B&'$(&&/ (% :iXebZXj\^Xj]ifdk_\\e^`e\% , )%:iXebZXj\^Xj\ek\ijk_\j\gXiXkfi% *%?\Xm`\if`c[ifgc\kjXi\j\gXiXk\[]ifdk_\c`^_k\i ^Xj\jYpZ\eki`]l^Xcj\gXiXk`fe`ek_\[`jZjkXZb% +%;iX`ef`cflkc\k% , ,%:c\Xe\[X`i&^Xjkffg\eX`i% -%I\jki`Zk`fe&k_ifkkc\mXcm\% * .% 9XcXeZ`e^g`g\% . * K_\ZfekifcZXY`e\kefkj_fne`ek_\`ccljkiXk`fe ZXeY\dflek\[fek_\df[lc\fi\cj\n_\i\% ) + + - ( =`^%)Æ=leZk`feXcgi`eZ`gc\% ) system. This system prevents the separated F`cd`jkj\gXiXkfidf[lc\j oil from re-entering the clean gas outlet. The fl exible mounted separator, the throttle The drained oil is taken back to the engine valves, and a safety switch are mounted on oil sump, thereby further minimizing a steel frame module. Since the processed lube oil consumption. gas may be explosive, all components inside The main benefi ts with the oil mist the separator are made of spark-proof material. separator are: The oil mist separator module can be ■ Very high and stable effi ciency: both manually or automatically operated. A stable separating effi ciency of above In auto mode the separator is started/stopped 98% has been repeatedly measured on automatically when the engine starts/stops. the Wärtsilä 20V34SG engine. Proven There are also running status indicators on features, such as the separating disc the module and output signals that can be design and the high rotational speed, connected to the plant or ship automation originate from Alfa Laval’s mineral system. oil separator technology. The disc Wärtsilä has plug-and-run oil mist stack speed is boosted by a frequency separator modules in various sizes for all converter to 7200 rpm for maximum Wärtsilä marine and power plant engines centrifugal force and optimal effi ciency. (see Figure 3). The modules fi t both new ■ No infl uence on the crankcase pressure: and retrofi t installations. There is also a There is no pressure drop over the UL-listed version for the US market. separator. In fact, it slightly decreases the crankcase pressure, which is then Gas engines neutralized by a restriction valve and For gas engines, the system can also be a balancing pipe. This gives a stable confi gured as a closed crankcase ventilation crankcase pressure and reliable system. This will reduce all crankcase operation of the engine. emissions to zero because they are ■ Long service intervals: The electric re-circulated into the air inlet of the motor and discs are specially designed turbocharger. for the high rotational speed, and have a service interval of 16,000 hours. Installation ■ Low power consumption: Installation is a straightforward procedure The electrical consumption of the oil for all engine types. For engines up to 12 MW, mist separator is 0.3 to 1.5 kW, one separator per engine is suffi cient. For depending on engine size. For an engine bigger engines, two separators in parallel with an output of 9000 kW, the mounted in a common module are used. electrical consumption is around 0.5 kW. ■ Robust, non-interference, design: I\]\i\eZ\j The system is of the add-on type and is, Today all new engineering, procurement as such, suitable for most engine types. and construction (EPC) power plants It is designed for a stable crankcase include the oil mist separator as standard. pressure and even in the rare event of Also, most equipment deliveries include =`^%*ÆJ\gXiXkfidf[\cjXe[k_\`i Xggc`ZXk`fej%KfgkfYfkkfd1 a failed separator, the engine can be oil mist separators. They have also Æ Le`k]fidXi`e\Xggc`ZXk`fej% run normally, thanks to the balancing been installed on a number of sea- Æ ?`^_ZXgXZ`kple`kn`k_[lXc pipe used as an automatic by-pass line. going vessels, both as new and as retrofi t j\gXiXkfij% ■ Lower lube oil consumption: installations. In the beginning of 2009 Æ Le`kdflek\[fek_\\o_Xljk^Xj The captured oil is re-circulated back there were approx. 400 oil mist separators df[lc\]fiNikj`c+-&,';= to the engine oil sump. installed or on order worldwide. \e^`e\j% `e[\kX`c 0.