| The bag filter has been gradually promoted from the terminal treatment application to an important purification process equipment in the multi-pollutant compound treatment system.During running process,it is necessary to ensure corresponding synchronous productivity and efficient,stable and reliable operation performance.The pulse bag filter is a part of the flue gas cleaning system in the plant,in which the life guarantee of the filter bag is a key step to maintain the stable operation of the system.Aiming at the aerodynamic damage caused by some factors such as the oncoming air scouring,pulsed air injection deflection and the cleaning airflow that has a high dust concentration,the paper combined different cases and numerical simulation methods to execute the fault deduction and process analysis.On the basis of the conclusions,the corresponding fault diagnosis procedures were summarized.The main conclusions can be drawn as follows:（1）The location and cause of the filter bag damage in a steel plant were determined by the numerical simulation method of local accurate modeling in a single box.Because the distance between the channel steel and filter bags is too close,the flow velocity increases on the surface of these bags,and the local scouring action of the dusty flow causes the outside wear and accelerates the damage of the filter bags.At the same time,non-uniformity of the ascending air velocity increases on the windward side of the filter bag,and the filter bags near the central partition are mostly affected by the scouring.（2）Through the single-bag dust removal numerical simulation method,the development trend of the jet airflow deflection was determined.The peak pressure on the wall of the filter bag fluctuates significantly within 1 m from the bag’s mouth.In the case of large airflow deflection angle,the core area of the jet will deviate from the bag mouth,resulting in a decrease in the peak pressure of the filter bag wall;the pressure and velocity on the wall of the front flow surface are higher than on that of the other side.The additional venturi tube at the mouth of the bag can increase the peak pressure of the filter bag wall,but the airflow correction effect is limited.（3）The fault location,fault causes and development trend of filter bag damage in a coal-fired thermal power plant were determined by combining with gas-solid two-phase flow numerical simulation and detection results on filter bags.The dust deposited on the tube sheet in the upper box was not cleaned up in time,which resulted in increased dust concentration of cleaning airflow and the dust accumulation inside the filter bag.And the dust at the bottom of the bag was disturbed by the dust removal airflow,which caused wear on the inner surface of the filter bag.If the filter bags near the wall of the box were damaged,the dust concentration of the upper box will increase,and the particles will deposit on the tube sheet.The 22%of the total cleaning airflow is the induced airflow,and its velocity above the bag mouth is close to 7 m·s-1.Therefore,suspended particles in the upper box and even particles deposited around the mouth of the bag will be inducted into the filter bag by the cleaning airflow and gradually accumulate in the bag.Moreover,the particles that were disturbed by the cleaning airflow above the surface of the dust column will repeatedly wear out the inner surface of the filter bag above the deposition layer.And the abrasion position of the inner surface is related to the height of the dust accumulation in the bag,which is located within 50 mm above the deposition surface of the ash column in the bag. |
