The Design And Experimental Measurements Of The BOG Adsorption Recovery System For The LNG Insulation Cylinder

Nowadays nature gas has become an alternative choice for gasoline because of its high calorific value and low air pollution.Since new energy,renewable energy and other advanced technologies have not mature yet,vigorously promote the use of nature gas can not only reduce the carbon dioxide emissions,but also reduce the cost.Un till now,the applications of LNG have limited to buses and heavy trucks,because of the boiling off gas(BOG)emission.An absorption storage device for BOG recovery is proposed and designed to meet this problem.The intern volume of the device is 15 L,and it is equipped with finned tubes inside.When the vehicle stops,LNG continuous evaporating,the BOG is absorbed by the device so that insulation cylinder pressure can maintain at a low value.When the vehicle starts,ANG desorbs and burns in the engine.The specific research work of this paper mainly includes the following three aspects:(1)The adsorption tank and its test-bench are designed and constructed.The test bed can simulate the adsorption process of BOG,and through the temperature rise and depressurization process,nature gas desorbed successfully.(2)The physical properties of three adsorbents with different specific surface areas are analyzed,and the most suitable adsorbent is selectedaccording to the operating conditions.The adsorption of natural gas on activated carbon is typical Ⅰ adsorption.The adsorption capacity increases with the decreasing temperature and increases with the increasing pressure.At 1.5MPA,20 ℃,the adsorption capacity can reach 42 V / V.The adsorption capacity at 30 ℃ is 43.5V / V,which is 10% lower than that at10 ℃.The size of the adsorbent bed should be 21.1L in order to meet the application conditions,and this size is feasible for small cars.(3)Constant pressure adsorption characteristics of CL-105 10*26adsorbent are tested and the overall performance of the absorbent bed,including the desorption rate and desorption temperature are analyzed.Fin tube equipped inside the adsorption storage tank can improve the heat transfer performance,and therefore reduce the desorption time.When the recovery system is applied to the LNG vehicle,the BOG in the adsorbent can be desorbed effectively by using the waste heat of the engine,and the energy efficiency of the engine is improved.