蜂窝煤成型机设计【工业型煤成型机的设计】
蜂窝煤成型机设计【工业型煤成型机的设计】,工业型煤成型机的设计,蜂窝煤成型机设计【工业型煤成型机的设计】,蜂窝煤,成型,设计,工业
本科毕业设计姓 名: 学 号: 学 院: 应用技术学院 专 业: 机械工程及自动化 论文题目: 蜂窝煤成型机设计成型机 专 题: 指导教师: XXX 职 称: XXX大学毕业论文任务书学院 专业年级 学生姓名 任务下达日期:XXX 年 1 月11 日毕业论文日期: XXX年 3 月 25 日至 XXX年 6月20 日毕业论文题目: 蜂窝煤成型机设计成型机毕业论文主要内容和要求:结合毕业实习,采用蜂窝煤成型机设计成型技术原理;利用自重加料方式,设计一台工业型煤成型机。辊子转速:8-10转/分(辊子圆周速度0.4-0.5米/秒);成型压力:15-30kn/cm;小时产量: 30-35吨;型球尺寸:mm;采用液压加载;铰接式框架结构:采用同步式齿轮箱传动。1、 明确该装置的工作原理及相关的受力分析,参考设计参数确定电动机功率,完成该装置的总体设计。2、 利用三维辅助设计,完成同步式齿轮箱设计。3、 同步齿轮传动箱组件设计、零件图工作图设计。4、 编写完成整机设计计算说明书。院长签字: 指导教师签字:xx大学毕业论文指导教师评阅书指导教师评语(基础理论及基本技能的掌握;独立解决实际问题的能力;研究内容的理论依据和技术方法;取得的主要成果及创新点;工作态度及工作量;总体评价及建议成绩;存在问题;是否同意答辩等):成 绩: 指导教师签字: 年 月 日XXX大学毕业论文评阅教师评阅书评阅教师评语(选题的意义;基础理论及基本技能的掌握;综合运用所学知识解决实际问题的能力;工作量的大小;取得的主要成果及创新点;写作的规范程度;总体评价及建议成绩;存在问题;是否同意答辩等):成 绩: 评阅教师签字: 年 月 日XXX大学毕业论文答辩及综合成绩答 辩 情 况提 出 问 题回 答 问 题正 确基本正确有一般性错误有原则性错误没有回答答辩委员会评语及建议成绩:答辩委员会主任签字: 年 月 日学院领导小组综合评定成绩:学院领导小组负责人: 年 月 日目 录绪论11.电机选型及传动比计算21.1选择电动机21.1.1选择电动机的类型和结构形式21.1.2选择电动机的容量21.2计算传动装置的总传动比并分配各级传动比31.2.1传动装置的总传动比31.2.2分配各级传动比32.V带设计计算421确定计算功率422选择带型423确定带轮基准直径424验算带的速度525初定中心距526确定基准长度527确定实际轴间距628验算小带轮包角629单根V带的基本额定功率6210单根V带的功率增量6211V带的根数6212单根V带的预紧力72.13带轮的结构72.13.1小带轮的结构73基本参数计算8各轴的转速、传递功率、转矩84同步齿轮减速箱齿轮的设计计算94.1I轴齿轮设计计算94.1.1选择齿轮材料94.1.2初定齿轮主要参数94.1.3校核齿面接触疲劳强度124.2轴齿轮设计计算144.2.1选择齿轮材料144.2.2初定齿轮主要参数144.2.3校核齿面接触疲劳强度174.3轴齿轮设计计算194.3.1选择齿轮材料194.3.2初定齿轮主要参数194.3.3校核齿面接触疲劳强度224.4轴齿轮设计计算244.4.1选择齿轮材料245同步齿轮减速箱轴的设计计算295.1轴的设计计算295.1.1选择轴的材料295.1.2初步估算轴的的直径295.1.3轴上零部件的选择和轴的结构设计295.1.4轴的受力分析305.1.5轴的强度计算325.2轴的设计计算335.2.1选择轴的材料335.2.2初步估算轴的的直径335.2.3轴上零部件的选择和轴的结构设计335.2.4轴的受力分析345.2.5轴的强度计算375.3轴的设计计算385.3.1选择轴的材料385.3.2初步估算轴的的直径385.3.3轴上零部件的选择和轴的结构设计395.3.4轴的受力分析395.3.5轴的强度计算445.4轴的设计计算445.4.1选择轴的材料445.4.2初步估算轴的的直径445.4.3轴上零部件的选择和轴的结构设计455.4.4轴的受力分析455.5.5轴的强度计算536.同步齿轮减速箱轴承的校核546.1I轴轴承的校核546.1.1计算轴承支反力546.1.2轴承的派生轴向力546.1.3轴承所受的轴向载荷546.1.4轴承的当量动载荷556.1.5轴承寿命556.2II轴轴承的校核556.2.1计算轴承支反力566.2.2轴承的派生轴向力566.2.3轴承所受的轴向载荷566.2.4轴承的当量动载荷566.2.5轴承寿命576.3III轴轴承的校核576.3.1计算轴承支反力576.3.2轴承的派生轴向力576.3.3轴承所受的轴向载荷576.3.4轴承的当量动载荷586.3.5轴承寿命586.4IV轴轴承的校核586.4.1计算轴承支反力596.4.2轴承的派生轴向力596.4.3轴承所受的轴向载荷596.4.4轴承的当量动载荷596.4.5轴承寿命606.5V轴轴承的校核606.5.1计算轴承支反力606.5.2轴承的派生轴向力606.5.3轴承所受的轴向载荷606.5.4轴承的当量动载荷616.5.5轴承寿命617.同步齿轮减速箱键的校核617.1I轴键的校核617.2II轴健的校核627.3III轴健的校核627.4IV轴健的校核627.5V轴键的校核638.同步齿轮减速箱箱体及附件设计计算638.1箱体设计638.1.1箱体结构设计638.2减速器附件638.2.1检查孔及其盖板638.2.2通气器638.2.3轴承盖和密封装置638.2.4定位销648.2.5油面指示器648.2.6放油开关648.2.7起吊装置649机架及成型装置的设计计算649.1型辊轴的设计649.1.1选择轴的材料649.1.2初步估算轴的的直径649.1.3轴上零部件的选择和轴的结构设计649.2辊心的设计659.2.1选择辊心的材料659.2.2辊心结构设计659.3型板的设计6610 液压加载装置的选型66结论67参考文献68 第70页 绪论1.型煤概况 随着机械化采煤程度的提高,产生了大量的粉煤。粉煤的市场价值很低,造成大量的积压。市场对型煤的需求量较大,型煤技术有很大的市场空间。同时生产型煤的原料煤的质地不受限制。2.成型设备概况 成型设备是型煤生产中的关键设备,选择成型设备应以原煤的特性,型煤的用途及成时压力等诸多因素为基础。目前工业上应用最广的是对辊式成型机。另外,还有冲压式成型机,环式成型机和螺旋式成型机等3.对辊成型机概况对辊成型机可用于成型、压块和颗粒的高压破碎,它的给料系统和辊面的设计要根据使用要求来设计。下面就对辊成型机在成型方面的应用进行描述。对辊成型机主要包括以下几个主要部件:3.1同步齿轮传动系统对辊成型机的同步齿轮传动系统由包括两个同步齿轮在内的减速器,安全联轴器等组成。安全联轴器是一个能自动复位的机构,它可以在正常工作时驱动转距的1.71.9倍范围内调整。最主要的是,同步齿轮和齿轮联轴器的连接保证了提供给型辊完全均匀的线速度。3.2成型系统对辊成型机的最主要部分是型辊。由于成型压力大,直径大,所以采用八块型板拼装的方式,辊芯由铸钢材料铸造而成,型板由强度高的耐磨材料制造。3.3液压加载系统液压加载系统用于提供压力迫使浮辊向被压实的物料和固定辊靠近。为满足特殊的工作需要,压力的高低和大小可以自由调整。压力的梯度随间距的变化而升高,通过改变液压储能器中氮的分压可以在很大范围内调整压力的梯度。在其他尖硬物料被压入压辊的间隙时液压系统也用作安全装置。1.电机选型及传动比计算1.1选择电动机1.1.1选择电动机的类型和结构形式按工作条件和要求,选用一般用途的Y系列三相异步电动机,为卧式封闭结构。1.1.2选择电动机的容量辊子转速:n=810r/min辊子圆周速度:v=0.40.5m/s=n/30 v=r初计算型辊半径 = 型球体积 每块型煤质量 型辊周向上分布型窝个数 (个)型辊轴向上分布型窝数 取整 型辊长度 取整B=630 mm辊上合力 KN阻力矩 工作机所需的功率:P=式中 =93000Nm n=10 r/min 代入上式得 P=KW电动机所需功率:P=P/从电动机到辊轮主轴之间的传动装置的总效率:=式中 =0.95 V带传动效率 =0.98 联轴器效率 =0.99 轴承效率 =0.97 齿轮传动效率代入上式得 =0.950.980.990.97 =0.6777 =P/=97.4/0.6777=143.2 KW选择电动机额定功率PP,根据传动系统图和推荐的传动比合理范围V带传动的传动比 2-4 ;单级圆柱齿轮传动比 3-6 。所以选择Y315L1-4电动机,额定功率160kw,满载转速1480 r/min 。1.2计算传动装置的总传动比并分配各级传动比1.2.1传动装置的总传动比=1481.2.2分配各级传动比该传动装置中使用的是三级圆柱齿轮减速器,考虑到以下原则:1)使各级传动的承载能力大致等(齿面接触强度大致相等)2)使减速器能获得最小外形尺寸和重量3)使各级传动中大齿轮的浸油深度大致相等,润滑最为简便分配各级齿轮传动比为=4。25 =4 =1.8辊轮的直径为956mm,两辊轮这间的间隙取1mm,所以两辊轮的中心距为957mm。由此调节可初定同步齿轮的传动比为2.4 。则V带传动的传动比为2。2.V带设计计算 21确定计算功率 根据工作情况 查表12-12选择工况系数 设计功率 22选择带型 根据和 选择25N窄V带(有效宽度制)23确定带轮基准直径 小带轮的基准直径 参考表12-19和图12-4取 传动比 取弹性滑动系数 大带轮基准准直径 取标准值 实际转速 实际传动比 24验算带的速度 25初定中心距 取26确定基准长度 由表12-10选取相应基准长度 27确定实际轴间距 安装时所需最小轴间距 张紧或补偿伸长所需最大轴间距 28验算小带轮包角 29单根V带的基本额定功率 根据和 由表12-17n查得25N型窄V带 210单根V带的功率增量考虑传动比的影响,额定功率的增量由表12-17n查得211V带的根数 由表12-13查得 由表12-16查得 根 取7根212单根V带的预紧力 由表12-142.13带轮的结构2.13.1小带轮的结构 小带轮采用实心轮结构。 由Y280M-4电动机可知,其轴伸直径,长度,小带轮轴孔直径应取,毂长应小于. 由表12-22查得,小带轮结构为实心轮 由V带的实际传动比,对减速器的传动比进行重新分配。 传动装置总传动比 V带传动传动比 同步齿轮的传动比 则三级减速器的传动比为 ,以达到传动比的调节。则 3基本参数计算各轴的转速、传递功率、转矩轴 = =轴 轴 轴 轴 4同步齿轮减速箱齿轮的设计计算4.1I轴齿轮设计计算4.1.1选择齿轮材料小齿轮 20CrMnTi 渗碳淬火 HRC 5662大齿轮 20CrMnTi 渗碳淬火 HRC 5662 齿轮的疲劳极限应力按中等质量(MQ)要求从图14-32和图14-24中查得 参考我国试验数据(表14-45)后,将适当降低:4.1.2初定齿轮主要参数初定齿轮主要参数 考虑载荷有轻微冲击、非对称轴承布置,取载荷系数K=2 按齿根弯曲疲劳强度估算齿轮尺寸,计算模数: 按表14-34,并考虑传动比,选用小齿轮齿数=24, 大齿轮齿数 取 = 102 按表14-33,选齿宽系数由图14-14查得大小齿轮的复合齿形系数(时) 由于轮齿单向受力,齿轮的许用弯曲应力 由于,故按小齿轮的抗弯强度计算模数 采用斜齿轮,按表14-2,取标准模数。初取=13(表14-33),则齿轮中心距 由于单件生产,不必取标准中心距,取。准确的螺旋角 齿轮分度圆直径 工作齿宽 为了保证,取。齿轮圆周速度 按此速度查表14-78,齿轮精度选用8级即可,齿轮精度8-7-7(GB10095-1988)校核重合度纵向重合度 (图14-8) 端面重合度 (图14-3) 总重合度 4.1.3校核齿面接触疲劳强度 分度圆上的切向力 由表14-39查得使用系数 动载荷系数式中 (表14-40)齿数比 将有关数据代入计算式 齿向载荷分布系数 齿向载荷分配系数,根据 查表14-43 得 节点区域系数,按和查图14-11 得材料弹性系数查表14-44 得重合度系数 查图14-12 得螺旋角系数 查图14-13 得 由于可取 计算接触强度强度安全系数 式中各系数的确定计算齿面应力循环数 按齿面不允许出现点蚀,查图14-37 得寿命系数 润滑油膜影响系数 查表14-47 得 齿面工作硬化系数 按图14-39 查得尺寸系数 按,查图14-40 得将以上数据代入计算式 由表14-49,按一般可靠度要求,选用最小安全系数。和均大于,故安全。4.2轴齿轮设计计算4.2.1选择齿轮材料小齿轮 20CrMnTi 渗碳淬火 HRC 5662大齿轮 20CrMnTi 渗碳淬火 HRC 5662 齿轮的疲劳极限应力按中等质量(MQ)要求从图14-32和图14-24中得 参考我国试验数据(表14-45)后,将适当降低:4.2.2初定齿轮主要参数按齿根弯曲疲劳强度估算齿轮尺寸,计算模数 按表14-34,并考虑传动比,选用小齿轮齿数=26, 大齿轮齿数 取整 =102 按表14-33,选齿宽系数由图14-14查得大小齿轮的复合齿形系数(时) 由于轮齿单向受力,齿轮的许用弯曲应力 由于,故按小齿轮的抗弯强度计算模数 采用斜齿轮,按表14-2,取标准模数。初取=13(表14-33),则齿轮中心距 由于单件生产,不必取标准中心距,取。准确的螺旋角 齿轮分度圆直径 工作齿宽 为了保证,取。齿轮圆周速度 按此速度查表14-78,齿轮精度选用8级即可,齿轮精度8-7-7(GB10095-1988)校核重合度纵向重合度 (图14-8) 端面重合度 (图14-3) 总重合度 4.2.3校核齿面接触疲劳强度 分度圆上的切向力 由表14-39查得使用系数 动载荷系数式中 (表14-40)齿数比将有关数据代入计算式 齿向载荷分布系数 齿向载荷分配系数,根据 查表14-43 得节点区域系数,按和查图14-11 得材料弹性系数查表14-44 得重合度系数 查图14-12 得螺旋角系数 查图14-13 得 由于可取 计算接触强度强度安全系数 式中各系数的确定计算齿面应力循环数 按齿面不允许出现点蚀,查图14-37 得寿命系数 润滑油膜影响系数 查表14-47 得 齿面工作硬化系数 按图14-39 查得尺寸系数 按,查图14-40 得将以上数据代入计算式 由表14-49,按一般可靠度要求,选用最小安全系数。和均大于,故安全。4.3轴齿轮设计计算4.3.1选择齿轮材料小齿轮 20CrMnTi 渗碳淬火 HRC 5662大齿轮 20CrMnTi 渗碳淬火 HRC 5662 齿轮的疲劳极限应力按中等质量(MQ)要求得 参考我国试验数据(表14-45)后,将适当降低:4.3.2初定齿轮主要参数 按齿根弯曲疲劳强度估算齿轮尺寸,计算模数 按表14-34,并考虑传动比,选用小齿轮齿数=40, 大齿轮齿数 取72 按表14-33,选齿宽系数由图14-14查得大小齿轮的复合齿形系数(时) 由于轮齿单向受力,齿轮的许用弯曲应力 由于,故按小齿轮的抗弯强度计算模数 采用斜齿轮,按表14-2,取标准模数。初取=13(表14-33),则齿轮中心距 由于单件生产,不必取标准中心距,取。准确的螺旋角 齿轮分度圆直径 工作齿宽 为了保证,取。齿轮圆周速度 按此速度查表14-78,齿轮精度选用8级即可,齿轮精度8-7-7(GB10095-1988)校核重合度纵向重合度 (图14-8) 端面重合度 (图14-3) 总重合度 4.3.3校核齿面接触疲劳强度 分度圆上的切向力 由表14-39查得使用系数 动载荷系数式中 (表14-40)齿数比将有关数据代入计算式 齿向载荷分布系数 齿向载荷分配系数,根据 查表14-43 得节点区域系数,按和查图14-11 得材料弹性系数查表14-44 得重合度系数 查图14-12 得螺旋角系数 查图14-13 得 由于可取 计算接触强度强度安全系数 式中各系数的确定计算齿面应力循环数 按齿面不允许出现点蚀,查图14-37 得寿命系数 润滑油膜影响系数 查表14-47 得 齿面工作硬化系数 按图14-39 查得尺寸系数 按,查图14-40 得将以上数据代入计算式 由表14-49,按一般可靠度要求,选用最小安全系数。和均大于,故安全。4.4轴齿轮设计计算4.4.1选择齿轮材料小齿轮 20CrMnTi 渗碳淬火 HRC 5662大齿轮 20CrMnTi 渗碳淬火 HRC 5662 齿轮的疲劳极限应力按中等质量(MQ)要求得 参考我国试验数据后,将适当降低:4.4.2初定齿轮主要参数按齿根弯曲疲劳强度估算齿轮尺寸,计算模数 按表14-34,并考虑传动比,选用小齿轮齿数=24, 大齿轮齿数 取58 按表14-33,选齿宽系数由图14-14查得大小齿轮的复合齿形系数(时) 由于轮齿单向受力,齿轮的许用弯曲应力 由于,故按小齿轮的抗弯强度计算模数 采用斜齿轮,按表14-2,取标准模数。初取=13(表14-33),则齿轮中心距 由于单件生产,不必取标准中心距,取。准确的螺旋角 齿轮分度圆直径 工作齿宽 为了保证,取。齿轮圆周速度 按此速度查表14-78,齿轮精度选用8级即可,齿轮精度8-7-7(GB10095-1988)校核重合度纵向重合度 (图14-8) 端面重合度 (图14-3) 总重合度 4.4.3校核齿面接触疲劳强度 分度圆上的切向力 由表14-39查得使用系数 动载荷系数式中 (表14-40)齿数比将有关数据代入计算式 齿向载荷分布系数 齿向载荷分配系数,根据 查表14-43 得节点区域系数,按和查图14-11 得材料弹性系数查表14-44 得重合度系数 查图14-12 得螺旋角系数 查图14-13 得 由于可取 计算接触强度强度安全系数 式中各系数的确定计算齿面应力循环数 按齿面不允许出现点蚀,查图14-37 得寿命系数 润滑油膜影响系数 查表14-47 得 齿面工作硬化系数 按图14-39 查得尺寸系数 按,查图14-40 得将以上数据代入计算式 由表14-49,按一般可靠度要求,选用最小安全系数。和均大于,故安全。5同步齿轮减速箱轴的设计计算5.1轴的设计计算5.1.1选择轴的材料该轴上的齿轮的分度圆直径和轴径相差不大,故做成齿轮轴,选用45号钢,调质处理,其力学性能 5.1.2初步估算轴的的直径 取轴径为70mm5.1.3轴上零部件的选择和轴的结构设计5.1.3.1初步选择滚动轴承根据轴的受力,选取30000型圆锥滚子轴承,为了便于轴承的装配,取装轴承处的直径。初选滚动轴承为33015型,其尺寸为,定位轴肩高度5.1.3.2根据轴向定位的要求确定轴的各段直径和长度轴段为圆柱形轴伸,查表21-9,的轴伸长。轴段直径为,根据减速器与轴承端盖的结构,确定端盖总宽度为,考虑端盖与带轮间隙,。轴段安装轴承,由于圆柱形轴伸的原因,采用双列轴承,取,。轴段轴肩长度,按齿轮距箱体内壁这距离取,考虑到箱体的铸造误差,滚动轴承应距箱体内壁,取,从各轴的结构选,。轴安装轴承,5.1.4轴的受力分析5.1.4.1作出轴的计算简图 5.1.4.2轴受外力的计算轴传递的转矩 齿轮的圆周力 齿轮的径向力 齿轮的轴向力 5.1.4.3求支反力在水平面内的支反力 由得 由得 弯矩图 在垂直面内的支反力由得 由得 弯矩图 扭矩图 5.1.5轴的强度计算按弯扭合成强度条件计算由于齿轮作用力在D截面的最大合成弯矩 D截面的当量弯矩 安全 5.2轴的设计计算5.2.1选择轴的材料选用45号钢,调质处理。 5.2.2初步估算轴的的直径 取轴径为110mm5.2.3轴上零部件的选择和轴的结构设计5.2.3.1初步选择滚动轴承根据轴的受力,选取30000型圆锥滚子轴承,为了便于轴承的装配,取装轴承处的直径。初选滚动轴承为30222型,其尺寸为。5.2.3.2根据轴向定位的要求确定轴的各段直径和长度轴段安装轴承,取,。轴段安装齿轮,齿轮左端采用套筒定位,右端使用轴肩定位。取轴段直径,齿轮宽度为110mm,为了全套筒端面可靠地压紧齿轮,轴段长度应略短于齿轮轮毂宽度取。轴段轴环,。轴段为齿轮轴宽度取。轴段安装轴承,5.2.4轴的受力分析5.2.4.1作出轴的计算简图 5.2.4.2轴受外力的计算轴传递的转矩 大齿轮的圆周力 大齿轮的径向力 大齿轮的轴向力 小齿轮的圆周力 齿轮的径向力 齿轮的轴向力 5.2.4.3求支反力在水平面内的支反力由得 由得 弯矩图 在垂直面内的支反力由得 由得 弯矩图 扭矩图 5.2.5轴的强度计算由于齿轮作用力在D截面的最大合成弯矩 D截面的当量弯矩 由于齿轮作用力在E截面的最大合成弯矩 E截面的当量弯矩 安全 5.3轴的设计计算5.3.1选择轴的材料选用45号钢,调质处理,其力学性能 5.3.2初步估算轴的的直径 取轴径为170mm5.3.3轴上零部件的选择和轴的结构设计5.3.3.1初步选择滚动轴承根据轴的受力,选取30000型圆锥滚子轴承,取装轴承处的直径。初选滚动轴承为32034型,其尺寸为。5.3.3.2根据轴向定位的要求确定轴的各段直径和长度轴段安装轴承,取,。轴段安装齿轮,齿轮左端采用套筒定位,右端使用轴肩定位。取轴段直径,齿轮宽度为230mm,为了套筒端面可靠地压紧齿轮,轴段长度应略短于齿轮轮毂宽度取。轴段轴肩高度,取,为。5.3.4轴的受力分析5.3.4.1作出轴的计算简图 5.3.4.2轴受外力的计算轴传递的转矩 大齿轮的圆周力 大齿轮的径向力 大齿轮的轴向力 小齿轮的圆周力 小齿轮的径向力 小齿轮的轴向力 5.3.4.3求支反力在水平面内的支反力 由得 得 弯矩图 在垂直面内的支反力由得 由得 弯矩图 扭矩图 5.3.5轴的强度计算按弯扭合成强度条件计算由于齿轮作用力在D截面的最大合成弯矩 D截面的当量弯矩 5.4轴的设计计算5.4.1选择轴的材料选用45号钢,调质处理,其力学性能由表21-1查得 5.4.2初步估算轴的的直径 取轴径为170mm5.4.3轴上零部件的选择和轴的结构设计5.4.3.1初步选择滚动轴承根据轴的受力,选取30000型圆锥滚子轴承,为了便于轴承的装配,取装轴承处的直径。初选滚动轴承为32034型,其尺寸为。5.4.3.2根据轴向定位的要求确定轴的各段直径和长度轴段安装轴承,取,。轴段安装齿轮,齿轮左端采用套筒定位,右端使用轴肩定位。取轴段直径,齿轮宽度为130mm,为了全套筒端面可靠地压紧齿轮,轴段长度应略短于齿轮轮毂宽度取。轴段轴肩高度,取,。轴环宽度,取,则。轴段为中间段, ,。轴段为轴肩,。VI轴段安装齿轮,齿轮右端采用套筒定位,左端使用轴肩定位。取轴段直径,。II轴段安装轴承,。5.4.4轴的受力分析5.4.4.1作出轴的计算简图 5.4.4.2轴受外力的计算轴传递的转矩 大齿轮的圆周力 大齿轮的径向力 大齿轮的轴向力 小齿轮的圆周力 齿轮的径向力 齿轮的轴向力 5.4.4.3求支反力在水平面内的支反力由得 由得 弯矩图 在垂直面内的支反力 由得 由得 弯矩图 扭矩图 5.4.5轴的强度计算按弯扭合成强度条件计算由于齿轮作用力在D截面的最大合成弯矩 D截面的当量弯矩 5.5轴的设计计算5.5.1选择轴的材料选用45号钢,调质处理。 5.5.2初步估算轴的的直径 取轴径为220mm5.5.3轴上零部件的选择和轴的结构设计5.5.3.1初步选择滚动轴承根据轴的受力,选取20000型调心滚子轴承,为了便于轴承的装配,取装轴承处的直径。初选滚动轴承为23072型,其尺寸为。5.5.3.2根据轴向定位的要求确定轴的各段直径和长度轴段安装轴承,取,。轴段安装齿轮,齿轮左端采用套筒定位,右端使用轴肩定位。取轴段直径,齿轮宽度为300mm,取。轴段轴肩高度,取,。轴环宽度,取,则。I轴段安装轴承,。V轴段伸出轴,联接联轴器,取,。5.5.4轴的受力分析5.5.4.1作出轴的计算简图 5.5.4.2轴受外力的计算轴传递的转矩 齿轮的圆周力 齿轮的径向力 齿轮的轴向力 5.5.4.3求支反力在水平面内的支反力由得 得 弯矩图 在垂直面内的支反力由得 得 弯矩图 扭矩图 5.5.5轴的强度计算按弯扭合成强度条件计算由于齿轮作用力在D截面的最大合成弯矩 D截面的当量弯矩 6.同步齿轮减速箱轴承的校核6.1I轴轴承的校核初选滚动轴承为32215型,其尺寸为基本额定载荷Cr: 170kN6.1.1计算轴承支反力合成支反力 6.1.2轴承的派生轴向力 6.1.3轴承所受的轴向载荷因 6.1.4轴承的当量动载荷 , , 6.1.5轴承寿命 因,故按计算 查得, 6.2II轴轴承的校核初选滚动轴承为32317型,尺寸为。基本额定载荷Cr: 180kNe=0.29 Y=2.16.2.1计算轴承支反力合成支反力 6.2.2轴承的派生轴向力 6.2.3轴承所受的轴向载荷因 6.2.4轴承的当量动载荷 , , 6.2.5轴承寿命因,故按计算查得, 6.3III轴轴承的校核初选滚动轴承为32022型,其尺寸为。e=0.43 Y=1.4基本额定载荷Cr: 245kN6.3.1计算轴承支反力合成支反力 6.3.2轴承的派生轴向力 6.3.3轴承所受的轴向载荷因 6.3.4轴承的当量动载荷 , , 6.3.5轴承寿命因,故按计算 查得, 6.4IV轴轴承的校核初选滚动轴承为32034型,其尺寸为。e=0.44 Y=1.4基本额定载荷Cr: 520kN6.4.1计算轴承支反力合成支反力 6.4.2轴承的派生轴向力 6.4.3轴承所受的轴向载荷因 6.4.4轴承的当量动载荷 , , 6.4.5轴承寿命因,故按计算 查得, 6.5V轴轴承的校核初选滚动轴承为23044型,其尺寸为。基本额定载荷Cr: 760kN6.5.1计算轴承支反力合成支反力 6.5.2轴承的派生轴向力 6.5.3轴承所受的轴向载荷因 6.5.4轴承的当量动载荷 , , 6.5.5轴承寿命因,故按计算 查得, 7.同步齿轮减速箱键的校核7.1I轴键的校核I轴的伸出轴,选用圆头普通平键(C型),b=18mm,h=11mm,L=125mm,I轴传递的扭矩T=676940Nmm.当键用45钢制造时,主要失效形式为压溃,通常只进行挤压强度计算., 合格7.2II轴健的校核II轴的键用于齿轮和轴的联接,轴径为,选用选用圆头普通平键(C型),b=25mm,h=14mm,L=90mm,II轴传递的扭矩T=2509780Nmm.7.3III轴健的校核III轴的键用于齿轮和轴的联接,轴径为,选用选用圆头普通平键(C型),b=32mm,h=18mm,L=125mm,II轴传递的扭矩T=8072570Nmm.采用双键联接。成对称布置,考虑到制造误差使键上载荷分布不均,按1.5个键计算。合格7.4IV轴健的校核IV轴的键用于齿轮和轴的联接,键1轴径为,选用普通平键(B型),b=45mm,h=25mm,L=160mm,II轴传递的扭矩T=28054080Nmm.采用双键联接。成对称布置,考虑到制造误差使键上载荷分布不均,按1.5个键计算。合格键2轴径为,选用选用圆头普通平键(C型),b=45mm,h=25mm,L=250mm,II轴传递的扭矩T=28054080Nmm.采用双键联接。成对称布置,考虑到制造误差使键上载荷分布不均,按1.5个键计算。合格7.5V轴键的校核V轴的键用于齿轮和轴的联接,轴径为,选用选用普通平键(B型),b=50mm,h=28mm,L=250mm,II轴传递的扭矩T=66668550Nmm.采用双键联接。成对称布置,考虑到制造误差使键上载荷分布不均,按1.5个键计算。合格8.同步齿轮减速箱箱体及附件设计计算8.1箱体设计8.1.1箱体结构设计箱体是减速器的重要组成部件。它是传动零件的基座,应具有足够的强度和刚度。由于本设计中冲击载荷不大,箱体采用灰铸铁铸造箱体。为了便于轴系零件的安装和拆卸,箱体制成沿轴心线水平剖分式。上箱盖和下箱座用普通螺栓联接成一整体。轴承座的联接螺栓应尽量靠近轴承座孔,座旁的凸台应有足够的承托面,并保证旋紧螺栓时需要的扳手空间。为了保证箱体有足够的刚度,在轴承座附近加支承肋。为了保证减速器安置在基座的稳定性,并尽可能减少箱体底座平面的机械加工面积。8.2减速器附件为了保证减速器的正常工作,除了对齿轮、轴、轴承组合和箱体的结构设计应予足够的重视外,还应考虑到为减速器润滑油池油池注油、排油、检查油面高度、检修折装时的上下箱的精确定位、吊运等辅助零部件的合理选择和设计。8.2.1检查孔及其盖板为了检查传动零件的啮合情况、接触斑点、侧隙,并向箱体内注入润滑油,应在箱体的适当位置设置检查孔。其大小应允许将手伸入箱内,以便检查齿轮啮合情况。8.2.2通气器减速器工作时,箱体内温度升高,气体膨胀,压力增大,为使箱内受热膨胀的空气自由排出,以保证箱体内外压力平衡,通常在箱体顶部装设通气器。设计中采用的通气器结构有滤网,用于工作环境多尘的场合,防尘效果较好。8.2.3轴承盖和密封装置为了固定轴系部件的轴向位置并承受轴向载荷,轴承座孔两端轴承盖封闭。轴承盖有凸缘式和嵌入式两种。设计中采用凸缘式轴承盖,优点是拆装、调整轴承比较方便。在轴伸处的轴承盖是透盖,透盖中装有密封装置。8.2.4定位销 为了精确地加工轴承座孔,并保证每次拆装后轴承座的上下半孔始终保持加工时的位置精度,应在精加工轴承座孔前,在上箱盖和下箱座的联接凸缘上配装定位销,并呈对称布置以加强定位效果。8.2.5油面指示器为了检查减速器内油池油面的高度,以便经常保证油池内有适当的油量一般在箱体便于观察、油面较稳定的部位,装设油面指示器。设计中采用油标尺。8.2.6放油开关换油时,为了排出污油和清洗剂,应在箱体底部、油池的最低位置处开设放油孔,平时放油孔有带有管螺纹的龙头堵住。8.2.7起吊装置当减速器的质量超过25KG时,为了便于搬运,常需在箱体上设置起吊装置。设计中上箱盖设有两个吊耳,下箱座焊接有六个吊钩。9机架及成型装置的设计计算9.1型辊轴的设计9.1.1选择轴的材料 选用45号钢,调质处理。9.1.2初步估算轴的的直径 取轴径为280mm9.1.3轴上零部件的选择和轴的结构设计9131初步选择滚动轴承根据轴的受力,选取20000型调心滚子轴承,为了便于轴承的装配,取装轴承处的直径。初选滚动轴承为23072型,其尺寸为。9132根据轴向定位的要求确定轴的各段直径和长度轴段安装联轴器,取,。轴段安装轴承盖。取轴段直径, 。轴段加工螺纹M340,长度23mm.IV轴段安装轴承,取轴段直径,V段安装轴承内端盖,取轴段直径,。VI,VII段安装辊心,便于结构考虑,VI段轴径略大于VII段,取轴段直径, , , 。VIII段安装轴承内端盖,取轴段直径,。IX轴段安装轴承,取轴段直径,。9.2辊心的设计9.2.1选择辊心的材料选用碳素铸钢材料,强度和加工性良好。9.2.2辊心结构设计 辊心铸成六边形结构,便于型板的安装和更换。9.3型板的设计9.3.1型板材料的选择由于成型压力大,球窝的接触线磨损大,选用15Cr3Mo材料。持久强度较高。9.3.2型板结构的设计辊轮的辊面分成六块型板,每一块用螺钉固定在辊心上,由于球窝的接触线磨损较大,所以球窝交错排列。这样有利于提高辊面的利用率,并且可以减少物料在辊面上非工作“突台区”产生的峰压。由前计算可得:辊子沿周向布排球窝数:=54辊子沿宽度方向可布排球窝:=10.01 圆整取10排辊子宽度:55.59+50+70+10=630mm单块型板的球窝布排沿周向是9个,布10排。10 液压加载装置的选型选用UZ系列微型液压泵站,油箱容积20L,最大压力200MPa。结论此次毕业设计历时近三个多月的时间,设计的主要内容是工业对辊成型机的整机设计。GD1146/90型对辊成型机,基本上可以满足年产10万吨的要求。该机型具有刚性好、效率高、操作灵活等特点。此次设计对辊成型机,主要有以下几方面的优点:1由于采用了安全联轴器,可以避免成型机在工作时由于物料(粉煤)带有的小件铁器等坚硬物进入辊轮啮合区而阻止辊轮的转动。所以设计的联轴器具有退让和安全保护的功能。2采用方形轴承座。对于固定对辊组件,其轴承座由定位平衡固定在机架的上、下端架之间;对于活动对辊组件,其轴承座可以沿上、下端架上的导向平键平移。在活动对辊组件有液压加载装置,可以提高成型力,并且在有较硬的铁器物质或其他物质进入辊轮间时可以避让,以免损坏对辊组件。3本成型机采用自重加料装置。在指导老师的悉心指导下,我不仅完成了设计任务,对成型机的成型原理有了更深的了解,而且还学到了很多书本上没有的知识,拓宽了自己的知识面。另外还提高了综合运用知识的能力,为将来工作打下了扎实的基础。参考文献1.吴宗泽 机械设计手册上册 北京:机械工业出版社 2002.12.吴宗泽 机械设计手册下册 北京:机械工业出版社 2002.13.王洪欣 机械设计工程学I 徐州:中国矿业大学出版社 2001.1 4.唐大放 机械设计工程学 徐州:中国矿业大学出版社 2001.15.蔡春源 新编机械设计手册 辽宁:科学技术出版社 1993.16.黎启柏 液压元件手册北京:冶金工业出版社机械工业出版社1999.127.张展 机械设计通用手册 北京:中国劳动出版社 1994.18.王旭 机械设计课程设计 北京:机械工业出版社 2003.89.孙德志机械设计基础课程设计北京:科学出版社200610.机械工程手册电机工程手册编辑委员会机械工程手册(专用机械卷)北京:机械工业出版社1997.911.机械工程手册电机工程手册编辑委员会机械工程手册(机械零部件设计)北京:机械工业出版社1997.912.成大先机械设计手册(润滑与密封)北京:化学工业出版社2004.113.张利平液压站设计与使用北京:海洋出版社200414.成大先机械设计手册(减速器、电机与电器)北京:化学工业出版社2004.115.成大先机械设计手册(液压传动)北京:化学工业出版社2004.116范祖尧现代机械设备设计手册北京:机械工业出版社,199617.梁庚煌输送机械手册(第2册) 北京:化学工业出版社,198318.中国农业机械化科学研究院实用机械设计手册北京:中国农业机械出版社,198519.Bergendshl.H.-G:Kugellager-Zeitschrift.Nr.199020.Rieschel.H.:ZechK:Phosphorus & Potassium.Sept./OK1.198121.Pietsch.W:International Fertilizer Development Center. Workshop Proceedings. Cuatemala City.OK1.1989致谢此次毕业设计忙碌了三个多月的时间。在此期间,指导老师不辞辛劳为我们悉心指导,使我学到了很多知识。在此,我非常感谢指导老师。 这次的毕业设计,既锻炼了我综合运用所学专业知识的能力,也让我学到了很多书本上学不到的知识。此外,我也十分感谢中国矿业大学以及各位老师四年对我的悉心栽培。使我在毕业后走向社会能成为一名真正对社会有用之人。附 录一英文资料及中文翻译The outline of coal preparation and Economics of Coal CleaningAbstractCoal preparation, simply put, is the conversion of run-of-mine (ROM) coal (or coal as it leaves the mine complete with impurities and prior to any processing) into a marketable product. Originally, coal preparation began as a line of equipment-crushers, feeders, screens, etc.-to control the size of the mined coal. Perhaps the easiest way to understand the evolution of coal cleaning and to understand the evolution of coal cleaning and to understand the variations found within the industry is to become familiar with the levels of coal preparation.Level 0 processing is the mining and shipping of ROM coal.The product of Level 1 processing is commonly termed raw coal.Level 2 processing involves the cleaning of the coarser sizes of raw coal (or coal which is larger than 1/2”).The coal finer than 1/2” would be added to the cleaned coal (the plus 1/2mm coal) or sent elsewhere.Level 3 processing extends the cleaning of the raw coal to the intermediate size raw coal-1/2” by 1/2mm.The minus 1/2mm material is added to the cleaned coal (the plus 1/2mm coal) or sent elsewhere.Level 4 processing extends the cleaning to include the minus 1/2mm raw coal.The feed to the coal preparation plant is then raw coal from Level 1 processing. Coals impurities are numerous, but by far the largest have specific weights greater than coal. The raw coal is thus characterized by partitioning the very heterogeneous coal into relatively homogeneous subpopulations on the basis of size and specific gravity.The separation unit operations normally process water/raw coal slurries, thus the term Coal Washing. Coal preparation is the quality control arm of the coal industry. It is an integral part of the coal business. 2. The Cumulative Float Curve-a plot of the cumulative float weight percent versus the cumulative float ash percent.The outline of coal preparationCoal preparation, simply put, is the conversion of run-of-mine (ROM) coal (or coal as it leaves the mine complete with impurities and prior to any processing) into a marketable product. (A quality-controlled substance whose composition meets the ever-increasing specifications required for its use whether its combustion, liquefaction, gasification or carbonization.)The coal we mine today represents the deposition of phytogenic material 50 to 350 million years ago. The resulting horizontal strata, what we call coal seams, will vary in thickness from several inches to several hundred feet. They are usually separated by varying thicknesses of sedimentary rocks such as shales, clays, sandstones and, sometimes, even limestone, OR-when combined with coal-what are known as impurities in terms of preparation.Originally, coal preparation began as a line of equipment-crushers, feeders, screens, etc.-to control the size of the mined coal. Among the product line was the conveying picking table which was used to visually inspect the ROM coal so that obvious impurities could be removed manually. Thousands of men, women and children performed this unfulfilling work until mechanization replaced it withmore modern coal cleaning equipment.Generally speaking, this coal cleaning equipment was developed for British and European mines because their coal was of much greater value per ton than in the U.S. Its value reflected its cost of mining-which was high because the seams were more difficult to mine compared with American coal seams.However, although U.S. seams are among the easiest in the world to mine, preparation took on a new significance with the unionization of mines during the New Deal. A rapidly rising demand for machines to mine coal both underground and above ground was created; machines which were not and are not selective and which mine whole seams, including partings and some roof and floor mater ials.Mechanical mining meant mechanical cleaning.Perhaps the easiest way to understand the evolution of coal cleaning and to understand the evolution of coal cleaning and to understand the variations found within the industry is to become familiar with the levels of coal preparation.Each level is indicative of the intensity of the work performed on run-of-mine coal and each is an extension of the previous level.Level 0 processing is the mining and shipping of ROM coal.Level 1 processing combines top-size control by crushing, with some removal of undesirable constituents such as tramp iron, timber and perhaps strong rocks. The product of Level 1 processing is commonly termed raw coal.Level 2 processing involves the cleaning of the coarser sizes of raw coal (or coal which is larger than 1/2”).The coal finer than 1/2” would be added to the cleaned coal (the plus 1/2mm coal) or sent elsewhere.Level 3 processing extends the cleaning of the raw coal to the intermediate size raw coal-1/2” by 1/2mm.The minus 1/2mm material is added to the cleaned coal (the plus 1/2mm coal) or sent elsewhere.Level 4 processing extends the cleaning to include the minus 1/2mm raw coal.Developing the appropriate circuitry for processing raw coals at Levels 2,3 and 4 involves four areas-characterization, liberation, separation and disposition.Characterization is the systematic examination of the ROM coal in order to determine the make up of the feed to the coal preparation plant. A coal processing engineer will develop a flowsheet of the unit operations required to achieve the desired preparation level.Liberation is the creation of individual particles whose composition are predominantly coal or refuse. This is achieved by size reduction or the crushing of the justmined coal to a particular top size as determined by the characterization study. The feed to the coal preparation plant is then raw coal from Level 1 processing. Unfortunately, particles containing both coal and refuseknown as middlings-are also createdSeparation is, simply, the dividing of the particles into their appropriate groups-coal, refuse and middlings. Coals impurities are numerous, but by far the largest have specific weights greater than coal. The dominant method for separating the liberated coal is by gravity concentration which relies on two physical property differences-size and specific gravity. The raw coal is thus characterized by partitioning the very heterogeneous coal into relatively homogeneous subpopulations on the basis of size and specific gravity.Disposition is the cleaning up of the various streams.The separation unit operations normally process water/raw coal slurries, thus the term Coal Washing. The predominant disposition operation is the dewatering (separating the liquid and the solis ) of the various atre ams after the separations have been made. The second most important disposition operation is refuse disposal, followed by other environmental control operations.Coal preparation is the quality control arm of the coal industry. It is an integral part of the coal business. WashabilityWashability studies are conducted primarily to determine how much coal can be produced at a given specific gravity and at what separation difficulty and size. The importance of the size analysis is perhaps more clear if you think of the cleaning process as removing impurities form individual pieces of coal, rather than in terms of tons of coal. As the individual pieces get smaller they become harderand more costlyto clean. Generally , the testing procedures of a washability study begin by obtaining a representative sample of the material already reduced to a designated top size, Next, the sample is sized at several different screen apertures, with each fraction held separately for further evaluation. A typical size analysis for a feed material is shown in Table 1. The table presents the percent of total weight, as well as an analysis of ash, sulfur content and Btu of each fraction, both individually and cumulatively.Then the material of each size fraction undergoes a float-sink test in liquids of pre-selected, carefully controlled specific gravities, beginning with the lowest.The float material from each specific gravity bath is then weighed and sink material is tested in the next heavier bath.The procedure is repeated until the desired number of float-sink result for the fraction in Table1 is given in Table 2.Since wider ranges are treated commercially, composite results are usually made by properly combining the individual size fraction results. A typical composite result of the material (Level 3 processing)in Table 1 is shown in Table3.This type of data is then used to develop washability curves-curves as unique to the coal as fingerprints to a hand-which describe the various characteristics of the coal.For example, Figure 1 shows three curves, generated from the data in Table 3, which are generally employed:1. The Yield Curve-a plot of the cumulative float weight percent versus specific gravity;2. The Cumulative Float Curve-a plot of the cumulative float weight percent versus the cumulative float ash percent;3. The Cumulative Sink Curve-a plot of the cumulative sink weight percent versus the cumulative sink ash percent.The theoretical cleaning capability can be determined from the curves. For example, if it is desired to produce a 28m product of 10% ash, the theoretical product quantity will be 75.8% of the feed. The separation must be made at a specific gravity of 1.665 and the rejects should analyze 82.1% ash.Economics of Coal CleaningAbstractA second stage of evaluation is then based on user costs deriving from coal properties. Losses of yield in cleaning represent the biggest item contributing to total cleaning costs because the size, and hence the capital cost of a cleaning plant, is based on the throughput capacity for raw coal .It is generally accepted that capital costs reduce with increases in plant size, although not all the items comprising a cleaning plant are directly units .For example ,the sizes of raw coal storage and handling units ,and the sizes of cleaned coal bunkers and loading facilities ,are often determined by the needs for strategic stockpiles or the requirements of the transportation system .Economic analysis is also greatly influenced by the relationship of the coal producer to the coal user .At least three different considerations may arise:(1) cleaned coal is produced for sale under comparatively short term contracts (1 to 3 years) in a competitive market, (2) coal is produced on long-term (7years and more) supply contracts, and (3) coal production and cleaning forms part of a totally integrated operation in which coal is mined and used by a single industrial undertaking. The elements of the cost of coal cleaning comprise fixed costs arising from capital charges, and fixed or variable costs arising from plant operation. For a given annual production, capital costs are highly dependent upon raw coal quality as determined by ash content and size consist. The former determines the yield of clean coal, and since plant capacities are dictated by raw coal throughputs, this factor has the major influence on capital requirements. The average yield of current American coal cleaning plants is 71%. Economics of Coal CleaningIn recent times modern wash plants in the United States has been standing idle because the premium on price necessary to cover cleaning costs could not be recovered in a slack coal market tend to evaluate their coal purchases by methods that indicate minimum costs in energy terms (i.e., delivered cost per million Btu). A second stage of evaluation is then based on user costs deriving from coal properties. These can be complex and include such items as ash content, ash composition and fusion temperatures, fixed carbon (coke making), sulfur, and crushing and pulverizing characteristics. Considerations of these factors may modify the primary evaluation ,but as a general rule will justify a premium for cleaning only if substantial cost savings in utilization will result .However, calorific value is not a primary control function in coal cleaning .It has an approximately linear relationship to ash and moisture contents. But after gross rock dilution in a raw coal has been removed, the yield in terms of thermal efficiency of recovery with ash content becomes nonlinear and an increasing penalty in thermal recovery for unit decreasing in ash content becomes the rule. Losses of yield in cleaning represent the biggest item contributing to total cleaning costs because the size, and hence the capital cost of a cleaning plant, is based on the throughput capacity for raw coal .It is generally accepted that capital costs reduce with increases in plant size, although not all the items comprising a cleaning plant are directly units .For example ,the sizes of raw coal storage and handling units ,and the sizes of cleaned coal bunkers and loading facilities ,are often determined by the needs for strategic stockpiles or the requirements of the transportation system .Economic analysis is also greatly influenced by the relationship of the coal producer to the coal user .At least three different considerations may arise:(1) cleaned coal is produced for sale under comparatively short term contracts (1 to 3 years) in a competitive market, (2) coal is produced on long-term (7years and more) supply contracts, and (3) coal production and cleaning forms part of a totally integrated operation in which coal is mined and used by a single industrial undertaking. Types (1) and (2) are most representative of past and present practices for metallurgical and thermal coals. Type (3) may apply following the current reorganization and restructuring of the coal industry and the growth of large coal conversion plants and mine-mouth generating stations.Additional complexity arises from tougher environmental regulation in which coal cleaning is only one aspect of control technology available for limited emissions of sulfur oxides and particulates, including hazardous trace elements. It has already been noted that environmental regulation relating to the operation of cleaning plants liquid effluents, fugitive dust, and noisehave resulted in significant increases in capital and operating costs. The future growth of coal cleaning in the United States will be largely determined by the attitude of the electric utilities industry and the extent to which utilities companies enter into full or joint ownership of the means of coal production. This may result in decisive changes in the way in which economic evaluation of new coal projects, including cleaning, are made .The financial yardsticks applied, until very recent times, for determining the economic worth of coal cleaning were relatively simple measures .The quality, tonnage, and expected market price of raw coal were compared with similar parameters for cleaning were then estimated and added to the basic production costs of ROM coal .The difference between anticipated gross productions costs and forecast selling prices because the basic for applying various accounting devices accounting devices to determine the balance of economic advantage .Usually , a discounted cash flow (DCF ) analysis enabled calculation of return on investment (ROI ) over periods of about 10 to 15 years for the different options. This exercise was principally of concern to coal-producing companies because they carried the fiscal responsibility for the decision to clean or not to clean. As a general rule of thumb, a decision to proceed with cleaning depended on a DCF-ROI of at least 15%per year, and more commonly, 20%. If the case for cleaning was a foregone necessity, because of the markets requirements, the analysis was used to calculate a selling price that would produce the necessary ROI. These rules had worked well in an industry that, although still important and substantial, had been declining.The utilities employ different accounting principles from the DCF-ROI type of evaluation and they employ different funding methods, particularly as regards debt/equity ratios. Traditionally, their payback periods are substantially longer, 3o to 40 years for fossil-fired plant. These differences can result in substantial changes in the fixed capital largest element in coal cleaning costs, being greater than 50% at all levels of preparation. Although a number of cost studies are in progress, the full impact of these changes and their wider importance for coal cleaning cannot be assessed at the present time.The elements of the cost of coal cleaning comprise fixed costs arising from capital charges, and fixed or variable costs arising from plant operation. Capital charges are determined by the depreciation of costs incurred in land acquisition and preparation; design procurement and construction; provision of utilities and transportation and communications facilities; taxes; working capital; and interest charges. They are a fixed-cost burden unaffected by actual plant throughputs. Operating expenses include salaries, wages, power costs, water costs, and productive supplies, including fuels, refuse, and waste disposal. This category may include fixed costs independent of plant throughput (e. g., salaries) or variable costs tied directly to throughput (e. g., productive supplies).For a given annual production, capital costs are highly dependent upon raw coal quality as determined by ash content and size consist. The former determines the yield of clean coal, and since plant capacities are dictated by raw coal throughputs, this factor has the major influence on capital requirements. The average yield of current American coal cleaning plants is 71%. The most expensive items of capital equipment to provide and operate are required for handling fine and ultrafine coal sizes (i.e., froth flotation vacuum filters, centrifuges, water clarification, and thermal drying). Cleaning costs are therefore highly sensitive to the quantity of sizes smaller than 1/4 in. in the feed.Capital and operating costs are also sensitive to plant utilization and the system of working. Plant practices vary from single-shift, 5-day-week operation to continuous-shift, 7-day operation. The latter normally allows one to three shifts per week downtime planned maintenance. It is clear that, for a given annual production, plant sizes and hence capital costs are related to the working practice adopted.选煤概述和煤的可选性摘要煤炭加工选煤概述简单说来,选煤就是把原煤(即开采后未经加工含有各种杂质的煤)。商品煤是具有一定质量规格的产品,它能满足燃烧,液化气化等方面所不断提高的技术要求。现在开采的煤是五千万到三亿五千万年前的植物沉积而成,所形成的水平层状物称之为煤层,厚度不一,从数英寸到数百英尺。煤层中经常夹杂着厚度不等的页岩,粘土砂岩,有时还夹杂石灰岩等沉积岩。从选煤的角度来说,这些和煤结合在一起的夹杂物称之为杂质。三级加工选别中等粒度(1/2英寸1/2毫米)的原料煤,小于1/2毫米粒级的则归入精煤(大于1/2毫米)或送往他处。原煤可选性的研究主要是为了决定在某一比重下可能获得的产品数量和洗选的难以程度,并确定入洗煤的粒度。如果把选煤看成是从一块块的煤中除区杂质,而不是根据成吨的煤去考虑问题,就能比较清楚的理解粒度分析的重要性。粒度越小,选煤难度越大,成本越高。在可选性研究的试验程序开始之前,通常是先取出经破碎达到规定粒度上限的煤样,然后用各种筛子进行筛分。各粒级产物要分别存放,以便进行可选性评定。表1所示为入料粒度的典型分析。表中列出了各粒级产物的重量百分数灰分硫分和发热量,分本级和累计两项。先配好重液,准确调节其比重,然后对各粒级产物进行浮沉试验,从比重最小的重液开始。每一级重液中的浮起物要称记重量,下沉物移入较高比重的重液,依次进行,直到获得个级比重物为止。表2为表1中产物的浮沉实验结果。由于工业上处理的粒级范围较广,经常把某些粒级浮沉试验结果加以适当组合,形成综合结果。近年来,由于支付选煤成本所需的额外费用不能在萧条的煤炭市场上回收,美国的现代化选煤厂一直处于停产状态。在竞争性的市场上,用户往往首先根据按能量计算最低价格(即每百万英热单位包括交货费用在内的价格)的方法判断他们是否要购买。其次是判断按煤的性质决定的使用价值。煤的性质比较复杂,它包括灰分,灰的组成及熔点,固定碳,硫分,破碎和磨碎特性等各项因素。考虑了这些因素以后,还会改变最初的判断,但按一般规律来说,只有在使用中如能明显地节约费用,才能认为选煤这项额外费用是合算的。然而,热值并不是选煤中应加以控制的主要方面。它与灰分和水分呈近似的线性关系,但是在原煤中大块岩石被拣除后,产率和灰分之间变成非线性关系,一般的规律是降低灰分就要增加热值回收率的损失。选煤中的产率损失是影响选煤总成本的最大项。由于选煤厂的规模乃至基建投资是以处理原煤的能力为基础的,因此产率损失对投资费产生最直接的影响。虽然构成选煤厂的各个项目并非全部都直接涉及选煤设备的处理能力,但通常人们认为随着工厂规模增大,投资费反而减少。按惯例,还本期很长,一个燃煤的厂的还本期为30-40年。关键词:煤炭加工 选煤 原煤可选性简单说来,选煤就是把原煤(即开采后未经加工含有各种杂质的煤)。商品煤是具有一定质量规格的产品,它能满足燃烧,液化气化等方面所不断提高的技术要求。现在开采的煤是五千万到三亿五千万年前的植物沉积而成,所形成的水平层状物称之为煤层,厚度不一,从数英寸到数百英尺。煤层中经常夹杂着厚度不等的页岩,粘土砂岩,有时还夹杂石灰岩等沉积岩。从选煤的角度来说,这些和煤结合在一起的夹杂物称之为
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