| Marine supercharged boiler reliability of its work, the vitality, durability and maintainability, and other aspects of good performance, particularly the notable feature of light weight, small size and good mobility is increasingly in favor of marine areas, and becomes the direction of development of modern marine boiler Supercharged boiler uses pressurized combustion system and rely on the turbocharger dedicated to the furnace unit high pressure, high density, high temperature combustion air and combustion chamber can reach the region of the 0.2~0.3MPa pressure gauge, greatly strengthen the combustion and heat transfer. The boiler combustion flue gas through high temperature and high pressure boiler heating surface heat exchanger, the crew entered the pressurized gas turbine acting. The Booster Compressor for power and heating air, flue gas heat recovery. When the gas turbine power surplus, the output power can be external, when gas turbine power shortage, use the auxiliary engine power increase, the general increase in use of auxiliary turbine compressor output. Booster for marine boilers, generally not output external power, gas turbine power exclusively for pressurized air compressor, power surplus, through the emission of hot air methods to maintain a balance. Turbocharging supercharged boiler units in the pivotal position, and turbocharged units is the protection device is pressurized boiler units and for the protection and control devices.This paper pressurized boiler unit control system protection devices for in-depth study its main research and analysis of the performance of its advantages and disadvantages, and the original system to improve research. In a large number of domestic and international inspection system to protect the boiler plant and aerodynamic knowledge relevant information on the basis of outlined the supercharger unit boiler control system protection devices and operating principle, supercharger unit of boiler control system to protect the structure and properties of the analysis, as well as the additional turbine speed limit protection system for key research the establishment of the mathematical model and Matlab/Simulink simulation model Simulation analysis of the system's speed limiter adjustment to the pressure and speed restrictions servo mechanism of displacement curve identify the original system there are some drawbacks, the three links with a two pneumatic proportional valve instead of the regulation speed limiter, using a hydraulic pressure sensors will convert signals, which improve the response speed. Overall, the following aspects :1. Boiler Fan Speed Limit Adjusting Systems AnalysisSpeed limit adjusting system uses a impeller as a sensor, Meanwhile impeller is a slide centrifugal pump. The oil pressure on the exit of impeller and the speed of additional turbine is proportional to the square. When additional turbine's speed reaches to 12050±180r/min, impeller sends the oil pressure to the speed limiter regulation to overcome its spring force. So that the speed limiter regulation's nozzle moves down and opens valve, a compressed air supply for servo speed limit, Speed limit servo machine through linkage to close additional steam turbine control valve. Additional to cut off the steam turbine supply, it reduces speed. When additional turbine speed reduces, the impeller export oil pressure is reduces, adjust the speed limiter nozzle upward movement, release valve, valve mouth closed, cutting off the speed limit to the servo mechanism gas, Servo machine speed limit through its internal reset spring, opens additional steam turbine control valve. Additional Turbine ultimate's speed is limited in the given range. We can see that the speed limit protection system through the impeller pump oil to control the speed limiter adjustment to the opening and closing. Oil pressure reflects the speed of the turbine.2. Establish the Mathematical Model of Boiler Fan Speed LimiterThe mathematical model is a mathematical model for the design of control systems. In the study and analysis of a system before the system must first establish a precise mathematical model. Of this chapter which is the systems theory, establish a speed limiter, Servo machine speed limit of nonlinear mathematical model. The flow of gas because the state is very complicated, in order to simplify the mathematical model, Assuming the use of the system working medium (air) to the ideal gas to meet the ideal gas equation of state. Gas flows through the mouth or other valve throttle the flow of state such as entropy are adiabatic process. The gas cylinder is uniform and each cavity instantaneous point in the same parameters, and with the outside world cylinder cavity between the two leaked, the piston movement, 2 cavity gas processes are adiabatic process, air pressure and atmospheric pressure constant. In the process of dynamic parameters of the change is only a small amount. Based on this model of the system to flow equation, the force balance equation, the pressure equation changes to reflect the characteristics, through the establishment of the mathematical model derived from the system and the transfer function block diagram, a more intuitive understanding of the entire system.3. The Simulation of Boiler Fan Speed Limit Adjusting SystemUsing computer simulation of the control system simulation and analysis, research control system is an important tool. Computer simulation is the process of studying objects according to similar principles, using computer simulation fidelity to the study. In the mathematical model, Matlab/Simulink environment in the structures of the system simulation models, including spool equilibrium module, Valve Cylinder Blocks flow calculation module, the module valve cylinder displacement, cylinder valve cavity pressure module. Based on the simulation-based modules, do the simulation of the system, research system speed limiter regulation changes and the pressure servo speed limit for the displacement changes. The simulation drawings show that the response to a certain delay will affect the work of the turbine, and can not control the speed of turbine in the right time.4. The Experiment Study of Boiler Fan Speed Limit Adjusting SystemExperimental research system is an important means Through building test bed to test the speed limit adjusting system of two key components -- speed control and speed limiter restrictions The servo static characteristics, testing its parameters, and its availability to make a decision. Do the dynamic experimental, find it's output pressure changing curve, analyse it dynamic response characteristic, and compare with simulating curve, to validate veracity of the mathematics model.5. The Improvements of Boiler Fan Speed Limit Adjusting SystemFrom the simulation of speed limit adjusting system, we can see the shortcomings of the original system. In order to improve the performance of the original system , pneumatic proportional valve is used to replace the original speed limiter regulation. In the original system, speed limiter is replaced by a sensor to measure oil pressure through the control signals to the proportional valve. To further study how to improve the performance of the system, a pneumatic proportional valve mathematical model, Combined with the speed limit servo machine model structures improved system simulation model for the simulation study Simulation Analysis of the curve can be seen to improve the system's response rate significantly faster than the original system. This shows that the program improved is feasible and effective.
|
PDF Full Text Request