Research On The Mechanism Of Hard-Particle-Slurry Based Pipeline Cleaning Method

Heat exchangers are essential for industrial production,and their prolonged operation presents the risk of impurity deposition.Heat exchanger pipelines require regular cleaning to ensure their normal operation.The existing chemical and mechanical cleaning methods display various limitations,such as environmental pollution and low cleaning efficiency.Therefore,this paper proposed a new pipeline cleaning technique using a slurry composed of hard particles.Polypropylene presents various advantages,such as a density close to water,no damage to equipment,water-insolubility,the absence of chemical reactions,and cost-efficiency.Consequently,this work selected a slurry consisting of polypropylene particles and water while investigating some key technologies related to this method.The specific content of this paper includes the following:(1)The mixing state and pressure loss of the slurry in the pipeline were investigated using a numerical simulation method to establish a three-dimensional,horizontal pipeline,CFD-DEM numerical simulation model,and analyze the trajectory of the pipeline particles in the pipeline.In addition,the influence of flow velocity,particle diameter,particle mass fraction,and pipeline diameter on the mixing state and pressure loss of the slurry was assessed by examining the particle distribution in different regions of the pipe and the pressure loss of the slurry at different calculated parameters.(2)The experimental device was built and consisted of a horizontal acrylic transparent pipe with a diameter of 30 mm.The slurry mixing state and pressure loss values were obtained at different experimental parameters using a data acquisition system based on virtual instrumentation and a high-speed camera on the exterior of the pipe.The influence of fluid flow velocity,particle concentration,and particle diameter was analyzed,while the accuracy of the numerical simulation calculation was verified by comparing the simulation and experimental results.(3)The particle removal mechanism in the fouling samples were investigated by experimental method.The calcium sulfate scale inside the heat exchanger was selected to prepare the scale cleaning samples for the experiments.The experimental results were analyzed at different angles to reveal the mechanism underlying the removal of the pollutants.Furthermore,the influence of the hardness,impact velocity,concentrations,and sizes of the polypropylene particles on the removal process was investigated by analyzing the size of the impact pits on the surfaces of the fouling samples and the mass pollutant removal by the particles.(4)An experimental slurry cleaning device was built,and a validation cleaning experiment was performed on the contaminated samples.The cleaning experiments were used to preliminarily verify the ability of the slurry to remove calcium sulfate scale and analyze the effect of the polypropylene particle hardness,fluid velocity,particle diameter,and particle concentration.