英文原文文献Automatic Control of the Level of Boiler BubbleWANG Zhi(Luoyang Petrochemical Engineering Co., Luo yang 471003, China)Abstract:The paper introduced the dynamic characteristics of the level of boiler bubble. The characteristics of automatic control schemes with one variable or two variables or three variables were discussed, as well as some problems concerned in engi-neering. The automatic control scheme of boiler bubble with three variables was recommended specially.Keywords: the level of boiler bubble; dynamic characteristics; automatic control schemes; one variable; two variables; three variables.INTRODUCTIONBoiler drum water level is the major indicators, is a very heavy to the accused variables to maintain the water level in a certain range is to ensure that the boiler The first condition for the entire operation, it is because: (1) high water level will be affect steam Package separator, saturated with water opour too much water, superheated steam temperature In sharp decline. The superheated steam turbine as a driving force, it would Turbine Blade damaged, affecting the safety and economy. (2) water bit too low, the less water in the drum, and when the load is higher, as the water Vaporization of speed, drum changes in the water level has also added speed.Fast, if not promptly adjust, it will cause the drum all vaporization of the water, resulting in Burning furnace tube, or even cause an explosion. Therefore, the boiler drum water level must be strict Canadian control.2 Several Boiler water level control program.2.1-Impulse Control SystemImpulse-control system (the term refers to the impulse is variable, namely single impulse Drum Level) are in direct control of drum water level control valve (Figure 4 below), the drum is the most simple level control of the most basic A form is a typical value for single-loop control system. The system guitar Simple configuration to- 1 -achieve low investment and easy for small low-pressure boiler. Boiler steam because this load is relatively stable, and the relative volume Drum The requirements of users of steam often not very strict, if the control system some alarm interlock devices, but also to meet production requirements. Figure 4 single impulse control system block diagram stay in a relatively short time, large load changes, we can not single.Figure 4 single impulse control system blockImpulse Level Control System. This is because: (1) when the load changes 21.2003 in the first eight chemical technology market "false Level" will reverse regulator dislocation movement, the increase of load - close down small water control valve, when the dust has settled flash evaporation, the water level will decline, a sharp fluctuations in the dynamic regulation poor quality. (2) changes from the decline in the water level to load changes and to control valve movements. Long lag time, if the water level in a small time constant process, the error bound very significant. (3) water supply system disturbances, as changes to the pump pressure, in water immediately, and that an accurate assessment of the water level so that when the control valve dynamic for the same lack of a timely manner.2.2 Pairs of Impulse Control SystemDrum in the water level control, the disturbance is the most important variable load . Then the introduction of steam flow to correction, it can not only compensation- 2 -"false solution "Caused by operation, and the water control valve movements timely, his constitutes a double impulse control systems. In essence, the Doubly-Impulse Control System is a system of feed-forward (steam flow FTS) plus single-loop feedback control the system of composite control system. Adder output = Pc ±λS Ps + Initial deviation. If the high-pressure steam supply steam turbine compressor, for the protection of equipment, to use gas valve to open (FC) valve, when the increased steam flow, water supply also to a corresponding increase in traffic, then use a gas valve, the output should be additive which is λS, should take. If steam as a heat source in the production process, for the protection of equipment. To use gas valve to the Commissioner (FO) valve, when the increased steam flow, water supply also to a corresponding increase in traffic, then use gas valve clearance, the output should be additive Reduce that λS should take dashes. In order to balance these two requirements, with the election to secure his position device (FL) .To the valve, the valve that stops accidents in the state in situ. Initial deviation settings the objectives are: normal load, the regulator and processing implements output can have a relatively moderate value, the best in the normal load with the initial error (steam flow FTS) λS Ps of exactly off Figure 5 pairs of impulse control system block diagramFigure 5 pairs of impulse control system block diagram- 3 -2.3 three impulse control program – feed forward Ⅰ(steam flow) plusFeedback (Level, water flow) Control System .The system can be seen as a comprehensive three-volume signal as a variable charged Single-Loop control system, put into operation and setting single-loop control systems, However, if the system parameters can not be set up to ensure that the material balance, variable load And when the water level will be more than poor. On the coefficient λS λW and the role and settings: (1) to ensure that the material balance That is, △W = a △D under the conditions of steam flow signal λS △Ps Water flow and signal λW /△PW should be the same, based on this principle, Identify and λW /λS ratio. (2) to determine the role of strength feed forward From (1) material balance know λW /λS and the ratio should be the size Determine the basis of the process, the greater its λS feed forward role as strong, a disturbance At present, the control valve opening of the changes also greater. Figure 6 three-block diagram of control program .Figure 6 three-block diagram of control program2.3.1 three impulse control program Ⅱ- steam flow feed forward --Cascade water flow control system and Ⅱprogram similar program, but only the adder position from regulation the former regulator moved after. The program- 4 -regardless of λW /λS and how to set up, When the load changes, the level can be maintained without poor, in order to improve the load disturbance2.3.2 three impulse control program Ⅲ- steam flow feed forward - liquidThe regulation of quality. Figure 7 three-block diagram of control program ⅡAdder output = ±Pc ±λS PS ±λWPW FCCU capacity steam boiler drum and Ms Guan used gas (FO) - 22 CHEMICAL TECHNOLOGY MARKET 2003 section 8 of the valve of the capital, when the increased steam flow, the water has to flow accordingly Increased gas use this valve clearance, boosting the output should be reduced, which should λSad mission minus. When the water flow increases, then choose gas valve clearance, Adder output should be increased, for instance, is λW,. When a heightened level(Regulator positive role), corresponding to water flow also decreased at this time selection Commissioner gas valve, boosting the output should be increased, for instance, is that of Pc.Figure 7 three-block diagram of control program Ⅱ4 ConclusionThis method successfully developed a new compound ammonium bicarbonate anti-caking agent can Crystal size increased ammonium bicarbonate, and has a good- 5 -anti-caking performance, stability good. This product has achieved industrial production was more than ammonium bicarbonate Health Industrial production plant application, the use of a ton of ammonium bicarbonate 0.45 ~ 0.5 kg, Lower production costs, good effect. Received date :2003-03-24 About the author: Chen Yu Long (1964 -) M, Associate Professor, Master, engaged in physical chemistry Teaching and fine chemical development.References[1] Chen yu long. Surfactant inorganic anti-caking agent in the application of daily chemical workers Industry, 2002,32 (4) :48-49[2] Song Xiang, Sun Bao ping, RU-ling were. Anti-caking agent and progress in research methods, chemicals Progress, 2001, (6) :50-52 (Then No. 23)[3] Jiang Wei Sun, Jin-Shou Yu. "Process control engineering." Beijing: hydrocarbon processing Press.[4] Jin-hui. "Process control." Beijing: Tsinghua University Press.[5] Lu Man. "Petroleum and Chemical Control Design Manual." Beijing: the chemical industry She version. 19.2003 in the first eight chemical technology market- 6 -附录B对应的中文翻译锅炉汽包水位的自动控制王智(洛阳石油化工程公司仪电室,河南洛阳471003)摘要:本文介绍了锅炉汽包水位的动态特性,单冲量、双冲量、三冲量控制方案的特点及工程中需注意的问题,着重介绍了汽包三冲量控制方案。
