计算综合4.如图所示为聚合釜温度控制系统。（1）请指出这是什么类型的控制系统？画出系统方块图。（2）如果聚合釜的温度不允许过高，否则易发生事故，试确定控制阀的气开、气关形式，说明理由。请指出主、副被控变量是什么？

<p class="MsoNormal"><span style="mso-spacerun:\'yes\';font-family:宋体;font-size:12.0000pt;mso-font-kerning:1.0000pt;"><font face="宋体">（</font></span><span style="mso-spacerun:\'yes\';font-family:宋体;font-size:12.0000pt;mso-font-kerning:1.0000pt;">1</span><span style="mso-spacerun:\'yes\';font-family:宋体;font-size:12.0000pt;mso-font-kerning:1.0000pt;"><font face="宋体">）串级控制系统。</font></span></p><p class="MsoNormal"><span style="mso-spacerun:\'yes\';font-family:宋体;font-size:12.0000pt;mso-font-kerning:1.0000pt;"><font face="宋体"><img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/examination/imgUplod/1497337548357ebf2d185ddce4fab9558a18b1feb7d5a.png" alt="上传图片"><br></font></span></p><p class="MsoNormal" style="line-height:150%;"><span style="mso-spacerun:\'yes\';font-family:宋体;line-height:150%;font-size:12.0000pt;mso-font-kerning:1.0000pt;"><font face="宋体">（</font></span><span style="mso-spacerun:\'yes\';font-family:宋体;line-height:150%;font-size:12.0000pt;mso-font-kerning:1.0000pt;">2</span><span style="mso-spacerun:\'yes\';font-family:宋体;line-height:150%;font-size:12.0000pt;mso-font-kerning:1.0000pt;"><font face="宋体">）气关式。事故状态下，应使控制阀全开，保证聚合釜温度不过高。</font></span><span style="mso-spacerun:\'yes\';font-family:宋体;line-height:150%;font-size:12.0000pt;mso-font-kerning:1.0000pt;"><o:p></o:p></span></p><p class="MsoNormal" style="line-height:150%;"><span style="mso-spacerun:\'yes\';font-family:宋体;line-height:150%;font-size:12.0000pt;mso-font-kerning:1.0000pt;">（</span><span style="mso-spacerun:\'yes\';font-family:宋体;line-height:150%;font-size:12.0000pt;mso-font-kerning:1.0000pt;">3</span><span style="mso-spacerun:\'yes\';font-family:宋体;line-height:150%;font-size:12.0000pt;mso-font-kerning:1.0000pt;">）主变量为反应温度，副变量为冷却水流量。</span><span style="mso-spacerun:\'yes\';font-family:宋体;line-height:150%;font-size:12.0000pt;mso-font-kerning:1.0000pt;"><o:p></o:p></span></p><p class="MsoNormal" style="line-height:150%;"><span style="mso-spacerun:\'yes\';font-family:宋体;line-height:150%;font-size:12.0000pt;mso-font-kerning:1.0000pt;"><img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/examination/imgUplod/14973375813153d460e35c1424754b500c4f5024a615d.png" alt="上传图片"><br></span></p>
（1）串级控制系统。（2）气关式。事故状态下，应使控制阀全开，保证聚合釜温度不过高。（3）主变量为反应温度，副变量为冷却水流量。