鍋爐汽包水位的自動(dòng)控制畢業(yè)論文外文翻譯

1、英文原文文獻(xiàn)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

2、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; thre

3、e variables.introduction boiler 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 packag

4、e 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,

5、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

6、control. 2 several boiler water level control program.2.1-impulse control system impulse-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 o

7、f the most basic a form is a typical value for single-loop control system. the system guitar simple configuration to 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 oft

8、en 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 block impulse level co

9、ntrol 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 decli

10、ne, 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,

11、 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 system drum in the water level control, the disturbance is the most important variable l

12、oad . then the introduction of steam flow to correction, it can not only compensation 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 f

13、low fts) plus single-loop feedback control the system of composite control system. adder output = pc s 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

14、 also to a corresponding increase in traffic, then use a gas valve, the output should be additive which is s, 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 suppl

15、y also to a corresponding increase in traffic, then use gas valve clearance, the output should be additive reduce that s 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

16、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) s ps of exactly off figure 5 pairs of impulse control system block diagram figure

17、 5 pairs of impulse control system block diagram 2.3 three impulse control program feed forward (steam flow) plus feedback (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 settin

18、g 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 s w and the role and settings: (1) to ensure that the material balance that is, w = a d under the

19、conditions of steam flow signal s ps water flow and signal w /pw should be the same, based on this principle, identify and w /s ratio. (2) to determine the role of strength feed forward from (1) material balance know w /s and the ratio should be the size determine the basis of the process, the great

20、er its s 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 program 2.3.1 three impulse control program - steam flow feed forward - cascade water flow

21、control system and program similar program, but only the adder position from regulation the former regulator moved after. the program regardless of w /s and how to set up, when the load changes, the level can be maintained without poor, in order to improve the load disturbance 2.3.2 three impulse co

22、ntrol program - steam flow feed forward - liquid the regulation of quality. figure 7 three-block diagram of control program adder output = pc s ps wpw 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 increa

23、sed steam flow, the water has to flow accordingly increased gas use this valve clearance, boosting the output should be reduced, which should sad mission minus. when the water flow increases, then choose gas valve clearance, adder output should be increased, for instance, is w,. when a heightened le

24、vel (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 4 conclusion this method successfully developed a new compoun

25、d ammonium bicarbonate anti-caking agent can crystal size increased ammonium bicarbonate, and has a good 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 amm

26、onium 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 agen

27、t 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

28、 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附錄b對(duì)應(yīng)的中文翻譯鍋爐汽包水位的自動(dòng)控制王智(洛陽石油化工程公司儀電室,河南洛陽471003)摘要:本文介紹了鍋爐汽包水位的動(dòng)

29、態(tài)特性,單沖量、雙沖量、三沖量控制方案的特點(diǎn)及工程中需注意的問題,著重介紹了汽包三沖量控制方案。關(guān)鍵詞:汽包水位;動(dòng)態(tài)特性;控制方案;單沖量;雙沖量;三沖量中圖分類號(hào):tq054文獻(xiàn)標(biāo)識(shí)碼:b文章編號(hào):1009-4725(2003)08-0020-04引言汽包水位是鍋爐運(yùn)行的主要指標(biāo),是一個(gè)非常重要的被控變量,維持水位在一定范圍內(nèi)是保證鍋爐安全運(yùn)行的首要條件,這是因?yàn)?(1)水位過高會(huì)影響汽包內(nèi)汽水分離,飽和水蒸過時(shí)過熱蒸汽溫度急劇下降。該過熱蒸汽作為汽輪機(jī)動(dòng)力的話,將會(huì)損壞汽輪機(jī)葉片,影響運(yùn)行的安全性與經(jīng)濟(jì)性。(2)水低,說明汽包內(nèi)的水量較少,而當(dāng)負(fù)荷很大時(shí),水的汽化速度加快,則汽包內(nèi)的水位

30、變化速度亦隨之加快,如不及時(shí)調(diào)節(jié),就會(huì)使汽包內(nèi)的水全部汽化,導(dǎo)致爐管燒壞,甚至引起爆炸。因此,鍋爐汽包水位必須嚴(yán)控制。2.1單沖量控制系統(tǒng)單沖量控制系統(tǒng)(沖量一詞指的是變量,單沖量即汽包液位)是采用汽包液位直接控制給水調(diào)節(jié)閥(如圖4所示),它是汽包液位自動(dòng)控制中最簡(jiǎn)單 最基本的一種形式,是典型的單回路定值控制系統(tǒng)。該系統(tǒng)結(jié)構(gòu)簡(jiǎn)單 投資少 容易實(shí)現(xiàn),用于小型 低壓鍋爐。因?yàn)檫@種鍋爐的蒸汽負(fù)荷比較穩(wěn)定,汽包的相對(duì)容積大,用戶對(duì)蒸汽的要求往往不十分嚴(yán)格,該控制系統(tǒng)若再配上一些報(bào)警聯(lián)鎖裝置,也可以滿足生產(chǎn)要求。在停留時(shí)間較短,負(fù)荷變化較大時(shí),就不能采用單沖量液位控制系統(tǒng)。這是因?yàn)?(1)負(fù)荷變化時(shí)產(chǎn)生

31、的212003年第8期化工科技市場(chǎng)“虛假液位”將使調(diào)節(jié)器反向錯(cuò)位動(dòng)作,負(fù)荷增大時(shí)反而關(guān)小給水調(diào)節(jié)閥,當(dāng)閃急汽化平息下來時(shí),會(huì)使水位嚴(yán)重下降,產(chǎn)生劇烈波動(dòng),調(diào)節(jié)的動(dòng)態(tài)品質(zhì)很差。(2)負(fù)荷變化時(shí),從負(fù)荷變化到水位下降再到調(diào)節(jié)閥動(dòng)作,滯后時(shí)間太長(zhǎng),如果水位過程時(shí)間常數(shù)很小,偏差必然很顯著。(3)給水系統(tǒng)擾動(dòng)時(shí),例如給水泵壓力變化,進(jìn)水量立即變化,而到水位產(chǎn)生偏差時(shí)才使調(diào)節(jié)閥動(dòng)作,同樣不夠及時(shí)。2.2雙沖量控制系統(tǒng)在汽包的水位控制中,最主要的擾動(dòng)是負(fù)荷的變化,那么引入蒸汽流量來校正,不僅可以補(bǔ)償“虛位”所引起的誤動(dòng)作,而且使給水調(diào)節(jié)閥的動(dòng)作及時(shí),這就構(gòu)成了雙沖量控制系統(tǒng)。從本質(zhì)上看,雙沖量控制系統(tǒng)是一

32、個(gè)前饋(蒸汽流量fts)加單回路反饋控制系統(tǒng)構(gòu)成的復(fù)合控制系統(tǒng)。加法器的輸出=pcs ps+初始偏差。如果高壓蒸汽供給蒸汽透平壓縮機(jī),為保護(hù)設(shè)備,給水閥宜選用氣開(f.c)閥,當(dāng)蒸汽流量加大時(shí),給水流量亦要相應(yīng)增加,此時(shí)選用氣開閥,加法器的輸出應(yīng)增加,即s應(yīng)該取正號(hào)。如果蒸汽作為工藝生產(chǎn)中的熱源時(shí),為保護(hù)設(shè)備,給水閥宜選用氣關(guān)(f.o)閥,當(dāng)蒸汽流量加大時(shí),給流量亦要相應(yīng)增加,此時(shí)選用氣關(guān)閥,加法器的輸出減小,即s應(yīng)該取減號(hào)。為了兼顧上述兩種要求,宜選帶保位裝置(f.l)的水閥,即事故狀態(tài)該閥停在原位。初始偏差設(shè)置的目的是:正常負(fù)荷下,調(diào)節(jié)器和加法器的輸出都能有一個(gè)比較適中的數(shù)值,最好在正常負(fù)荷下初始偏差與前饋(蒸汽流量fts)s ps項(xiàng)恰好抵消。 圖4單沖量控制系統(tǒng)方框圖 圖5雙沖量