Study On Collaborative Working Mechanism Of Steel Tower Framed Suspended Tube Chimney With Wet Desulfurization

Steel tower framed suspended tube chimney is made up of two kinds of structure units which are external steel tower frame and internal smoke exhaust pipes to form stable system.The external steel tower frame bears the weight of the smoke exhaust pipe as well as the horizontal loads which are transferred from the tube,So the tower frame is the primary mechanical structure.The internal tube is mainly to satisfy the function of the stack gas emission after the wet desulfurization and it is integrally or segmentally suspended on the external steel tower frame.The cylinder is connected with the several layers of the external frame through some slide-way typed anti-sway points,so that the horizontal forces can be transferred to the steel tower frame.Now in the thermal power plants,reinforced concrete outer tube suspended steel inner tube chimney is widely used,while the Application and research of steel structure tower suspended steel inner tube chimney is relatively few.With the development of the national economy,industrialization is accelerating,and the use of the steel tower framed suspended tube chimney is increasing.But this kind of chimneys are always designed with conventional method,in which the steel tower and the exhaust pipe are modeled and calculated separately.So that the stiffness contribution of the stack is neglected and the joint working effect of the two units is not considered.The paper mainly aims at the steel tower frame and exhaust pipe’s collaborative mechanism of this kind of chimneys.In this paper,the main types and flue gas characteristics of the chimneys in thermal power plants were summarized.The key points of design such as the structure and materials selection,the structural characteristics,main loads and calculation methods were discussed.The paper also analyzed the common anticorrosion methods of the flue pipe of wet desulfurization chimney,and suggested that the desulfurization process should be considered so that the anticorrosion scheme could be well-targeted.Combined with background engineering,separated models of the steel tower frame and exhaust pipe and the overall model of steel tower framed suspended tube chimney based on the cooperative mechanism were respectively established,and the finite element calculation was carried out.The calculation results of the model were compared and analyzed,mainly about the differences between them in the dynamic characteristics,such as natural vibration periods and vibration modes and the responses under the wind loads and the seismic loads.The results show that The mechanical characteristics and control loads are similar,but the design method of the structure based on cooperative mechanism is more realistic and the calculation result is more accurate and the material is more economical.The finite element analysis of suspension joints considering vertical seismic effect is carried out and the reliability of the connected node is verified.Relying on the overall finite element model,the article analyzed the mechanical characteristics of this kind of chimneys by parameterization.The parameters,such as the hanging way and thickness of the tube and the ratio of the width to the height of the outer steel frame were focused on.The results show that the structural stiffness when the exhaust pipe is suspended as a whole is greater than it is suspended separated.The smoke stack has minimum stress when it is statically determinated.The thickness of the exhaust tube has little effect on the stiffness of the structure while the ratio of width to height at the bottom of the tower has a greater influence on the structural stiffness.The non-linear analysis of the chimney under the action of strong winds or earthquakes was carried out by using the method of increasing coefficient.The results show that the calculation no longer converges when the wind load coefficient reached 2.8 or the peak acceleration under the earthquake action reached 1100cm/s~2.54m~74m layers in the lower parts of the steel tower structure and the beams of 144m~154m below the suspension truss are the key and weak parts of the structure.The maximum stress of the cylinder is at the 74m sway point connected with the tower under two kinds of load and the maximum stress of smoke stack is generally smaller than the maximum stress of tower member.The above weak parts should be strengthened properly in the design.In conclusion,Selection of anti-corrosion materials for exhaust pipe in the thermal power plants showed be combined with desulfurization process.The control load of steel tower framed suspended tube chimney is wind load.The sensitive force parameters of the structure and important connected nodes should be focused on.It is suggested that analysis and calculation are carried out according to the design method of considering the collaborative working mechanism of steel tower and smoke stack two structural units.The key and weak parts of the structure should be strengthened during the design process.