Barreled asphalt is a form of packaging, storage, and transportation of asphalt materials for road use. Asphalt is in a solid state at normal temperature. It should be removed from the barrel during road construction, and heated to 140 ~ 160X: the use temperature, supplied to the mixing equipment, or heated to iio ~ i2 (rc) and then pumped into the storage tank for another heating and use.

      With the wide application of barreled asphalt in road construction, various asphalt decanting equipment with different heating methods have appeared. According to different heat transfer medium and heat transfer methods, it can be divided into steam heating method, open flame barbecue method, heat -conducting oil heating method, and exhaust gas direct heating method. The heating temperature of the steam heating method and the heat-conducting oil heating method are relatively uniform, and the asphalt is not easy to overheat, but both are indirect heating to remove the barrel, the thermal efficiency is low, and the heating equipment has a complicated structure and high cost. When the barrel is removed from the open flame barbecue, not only the heat loss is large, the asphalt temperature is difficult to control, the asphalt is easy to age, and the pollution is serious. Our company uses exhaust gas to directly heat the asphalt decanting equipment, which has high heat transfer efficiency. When the exhaust gas passes through the gas pipe to heat the asphalt, it can effectively use heat, save energy, and ensure the quality of asphalt heating.

Comprehensive heating and heat distribution mode of asphalt decanting equipment

2.1 The main structure of the equipment

      The main body of the equipment is a rectangular hexahedron, and a flat trolley is arranged in the middle of the inner cavity to divide it into upper and lower chambers. The upper chamber is the barrel-removing chamber and the lower chamber is the oil pool. The trolley is driven by a driving device and can run on pre-laid tracks inside and outside the main body. 29 round holes with a diameter slightly smaller than the diameter of the asphalt barrel are processed on the platform of the trolley so that the asphalt barrel with a large opening cover is placed on the trolley and heated in the upper chamber. The lower chamber is equipped with a U-shaped gas pipe whcih indirectly heats the asphalt that has been removed from the barrel. The asbestos board with a thickness of 60mm is used as the heat insulation layer in the interlayer of the outer wall of the equipment.

2.2 Asphalt decanting mechanism

      According to the heat transfer characteristics of asphalt and applying similar theory to simulate the asphalt heating process, the internal temperature response curve after heating the asphalt can be obtained. For example, a cylindrical asphalt with a diameter of 500mm and a height of 900mm, at an initial temperature of 20P, can reach 104°C on the surface after heating with gas at 300°C for 1h, while the temperature at the center remains at the initial state. According to this feature, when the asphalt is removed from the barrel, the barrel mouth is fully opened and placed on the trolley. When the gas with an average temperature of 300C is strongly attracted by the induced draft fan, it passes through the barrel wall at a speed of 1.3m/s and is heated for 20-30 minutes. Later, the asphalt layer attached to the barrel wall melts. Under the action of gravity, all the asphalt fell out of the barrel and fell into the oil pool. This mechanism shows that when the asphalt is removed from the barrel, it is not necessary to heat the entire barrel of asphalt to a certain temperature, but only to heat the bound surface layer in the asphalt barrel to a certain temperature. When the viscosity of the asphalt in the bound surface layer is less than the gravity of the asphalt , decanting is realized.

2.3 Integrated heating and heat distribution mode

      The heating process of asphalt decanting is actually divided into two stages: asphalt decanting and asphalt heating. During the decanting stage of asphalt, due to the poor thermal conductivity of asphalt, its thermal conductivity is only equivalent to that of building bricks. Therefore, the heat transfer during the heating process is slow and the heating is uneven; the average temperature rise of the asphalt after decanting is 20~30C. The average temperature of the asphalt is only 40-50X: analysis and actual measurement prove that the heat consumed at this stage only accounts for 20%-25% of the total heat absorbed by the asphalt, and the use of exhaust gas to dissipate heat can fully meet the heat required for asphalt decanting. In the asphalt heating stage, the barreled asphalt is heated to a storage temperature of 110~120C (or heated to a use temperature of 140~160P), and then pumped to the asphalt insulation tank for later use. The heat required at this stage accounts for 75% to 80% of the total heat, which is provided by gas pipe heating.

      Asphalt circulation system (including asphalt pumps, valves) and external pipelines are insulated with heat-conducting oil heat preservation technology. The heating of heat-conducting oil is provided by electric heat-conducting oil heaters.

      To sum up, the use of exhaust gas to directly decant, gas pipes to indirectly heat asphalt, and electric heat conducting oil heaters to heat the heat conducting oil constitute a comprehensive heating system for asphalt decanting equipment, which can effectively meet the heating requirements for asphalt decanting, heating and transmission. It makes full use of the heat of gas and achieves the purpose of improving productivity and energy saving.