Energy Efficiency Analysis Of Carbon Production Process And Design Of Waste Heat Heat Exchanger

As the current world structure changes,my country's energy supply and demand relationship is also changing.In order to deal with environmental pollution and energy constraints,it is particularly important to implement energy conservation and emission reduction.Under the guidance of my country's energy-saving and emission-reduction energy policy,the production of carbon anodes for aluminum is a high-energy-consuming industry.It is particularly necessary to work on waste heat utilization to improve energy efficiency.This paper analyzes the material flow,energy flow balance and energy efficiency evaluation of the carbon production process from a systematic perspective.Conduct actual research,testing and calculations on the production process of a carbon plant in Shandong Province.The study found that the main heat expenditure items in the production process are:high-temperature calcined coke takes away heat,calcined flue gas takes away heat,and roasted high-temperature solid takes away heat;after exergy balance analysis,the chemical exergy and exergy of finished products that cannot be recovered are removed.For the loss part,the exergy expenditure items of the entire carbon production process are mainly: the heat is taken out by the high-temperature calcined coke,the heat is taken away by the calcining flue gas,and the heat is taken away by the roasting high-temperature solid,which is the same as the result of the thermal balance analysis.According to the characteristics of waste heat and the actual waste heat recovery situation in the plant area,the waste heat recovery method of calcined coke waste heat recovery for winter heating and summer cooling is proposed,and its economic analysis is carried out.In order to more efficiently recover the waste heat of the high-temperature calcined coke and reduce the discharge temperature of the calcined coke,based on the research on the heat transfer performance of the traditional water-cooled jacket,this paper proposes a new type of cage-type high-temperature calcined coke waste heat recovery heat exchange device.Physically model the new and old heat exchangers,and use CFD software to numerically simulate the heat exchange process of the two.The simulated operating conditions are compared with the actual operating conditions of the calcination workshop of the carbon plant.Under the same operating conditions,The new heat exchanger has a lower calcined outlet temperature,a higher cooling water outlet temperature,waste heat recovery efficiency,cooling efficiency,and uniformity of cooling,which are better than cooling water jackets.In order to further explore the operating characteristics of the new heat exchanger,the influence of the changes in the cooling water flow and the calcined coke flow on the remaining heat recovery efficiency and the cooling efficiency of the calcined coke are compared and analyzed.The results show that the cooling efficiency,waste heat recovery efficiency,average heat transfer coefficient and other parameters of the new heat exchanger are higher than those of the traditional water-cooled jacket;as the water flow increases to twice,the cooling efficiency and waste heat recovery efficiency of the new heat exchanger The increase rate is within 1%,so increasing the water flow cannot significantly enhance the heat transfer effect;as the calcined coke flow increases from 110 kg/h to 150 kg/h,the waste heat recovery efficiency increases by 2.5%,and the cooling efficiency decreases by 3.44%.Increasing the calcined coke flow rate will slightly increase the outlet material temperature,but it is still far below its oxidation temperature.On the whole,within the safe temperature range,a larger calcined coke flow rate can be appropriately selected.Finally,it discusses the law that the waste heat recovery effect and cooling effect of the new heat exchanger vary with the structural parameters of tube number,tube diameter,distance between the heat exchange tube and the shell,and the maximum number of tubes for different tube diameters at their optimal distance.The analysis shows that with the increase of tube diameter and number of tubes,the waste heat recovery efficiency and cooling efficiency of the new heat exchanger show an upward trend,and the heat transfer coefficient shows a downward trend;after comprehensive evaluation,the tube diameter is 60 mm and the number of tubes is 60 mm.With 31 heat exchange tubes,when the distance from the shell is 120 mm,the waste heat recovery effect,cooling effect,and heat transfer coefficient of the new heat exchange show the best effect.