Exergy Analysis And Optimization Of Paper Machine Dryer Section System

Presently, energy consumption of paper making in our country is larger than that of foreign, it’s a long and difficult way to go. Drying section is one of components of paper making energy consumption, steam drying section as a common section in paper machine is the key to energy saving technology research, which is lack of scientific and reasonable analysis method.Based on energy quality, exergy analysis can label the weight of different kinds of energy to make up disadvantages of energy analysis which is always focus on the quantity of energy not the quality. Exergy analysis has already been used in the industry, and in the paper making, several scholars have been applied exergy analysis in paper technology or single facility like steam-driven jet ejector, but dryer system exergy analysis model haven’t been researched.Concentrating on dryer system of paper machine, based on exergy analysis, dryer system and its facilities universal exergy analysis model is been established:with the data collection, drying section thermodynamic system is been checked. And by control variate method and orthogonal method, different dryer systems’exergy performance are been analyzed and compared, to optimize the working conditions of the best system. The direction of energy saving technology is been proposed.DSJ system components of dryer cylinder, steam separate and steam-driven jet ejector has the best exergy performance—high exergy efficiency and low steam consumption, the optimization working conditions are when ΔP=0.02MPa and δ=0.15, exergy efficiency is equal to52%. DFJ system components of dryer cylinder, flash tank and steam-driven jet ejector is high economic efficiency (without consideration of different price between different quality steam). Theoretically, DFJ system can be normal work without supple steam, only depend on steam-driven jet ejector working steam.The optimization working conditions of facilities in DSJ system are when ΔP=0.07MPa (δ=0.27), and in consideration of total steam consumption, exergy consumption and system exergy efficiency, ΔP=0.02MPa (δ=0.16) is the optimization working conditions and under this working conditions, system exergy efficiency is52%.The most serious exergy loss facility is dryer cylinder which is the key resource of system exergy loss and exergy loss coefficient is almost0.5, exergy loss ratio is over0.86; When v=lm/s and t=80℃, dryer cylinder exergy efficiency is maximize, about70%; When v=1m/s and t=50℃, dryer cylinder thermal efficiency is maximize, over86%. Dryer cylinder exergy efficiency can be improved obviously by hot wind blowing dryer cylinder. Steam-driven jet ejector exergy efficiency is low, about40%, it can saving steam, but can’t saving exergy. this is a method that using a small amount of high quality steam in exchange for a moderate amount of low quality steam. So, dryer cylinder and steam-driven jet ejector are all the key to improve system exergy efficiency.