Operation Analysis And Economic Research On Blending Combustion With Coal Slime In Circulating Fluidized Bed Boiler

Coal slime is the by-product of coal washing process,which can reduce the cost of power generation and bring huge economic benefits for power plant.But due to its characteristics,operation instability and other factors,mix-burning with coal slime may cause some problems,such as main parameters fluctuations,combustion instability,efficiency reduction,etc.In order to overcome the above problems,fully tap the advantages and potential of coal slime,according to the engineering project of 2# unit in Linhuan Zhongli power plant,the economic problem of the CFB unit is deeply studied in this paper.The main research contents include the following aspects:The factors which influence economic performances of CFB units with coal slime are analyzed from two viewpoints:(1)The viewpoint of operation.By using the anti-balance method,the key parameters which affect the primary economic index(coal consumption rate)of the unit are obtained.In order to study the effect of slime on the main parameters and ensure the parameter values in a safe and reasonable range,the tests of blending combustion with coal slime were carried out.Through the analysis of the results,the conclusion is drawn as follows: under the premise of ensuring the stability of boiler combustion and the safe operation of the unit,the greater the amount of coal slime,the more power generation cost is saved.According to the actual situation of power plant,the maximum amount of coal slime is 50m3/h.(2)The viewpoint of control.The prominent control problem of the power plant is energy fluctuation,which caused by the instability of coal slime system.In order to effectively control the fluctuation of energy,two strategies are proposed in this paper.One is to find the relationship between the carbon burning and the heat of the furnace by the soft sensing method.Through optimizing the model of the ratio of wind and coal,the furnace combustion monitoring is strengthened and the stability of combustion is ensured.The other is to make full use of the advantages in energy storage of CFB units.By optimizing the changing process of energy,the ratio of coal slime is further increased.Based on the theoretical analysis,by adding former feedback,such as carbon burning thermal dynamic compensation signal,air-wind ratio correction signal and calorific value correction signal,the original control strategy of power plant are improved and the amount of coal slime is increased by 36% than before.Finally,the theoretical results are applied to the actual operation of the power plant.What can be seen from the statistical results of the economic indicators is that the main parameters of the unit are more stable after optimization and the coal consumption rate of the unit is greatly reduced.During the main operating conditions(180MW~260MW),the coal consumption is reduced by 3.184 ~ 5.188 g /k Wh.And the higher the load,the more economic benefits are obtained.In accordance with the optimization plan of this paper,the annual savings of fuel costs for the plant can be over 6.37 million yuan.