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1、Mine scraper conveyor soft-start modeof selection and application High yield and high efficiency in the coal mine fully mechanized coal face of the building, to face big-long, large to support the requirements of the power of Shearer and scraper conveyor. Ordinary fully mechanized coal face of the l
2、ong-general in about 150 m, scraper conveyor transport capacity of 500 t / h around high yield and high efficiency and fully mechanized coal face of the long-General to 180 300 m, scraper conveyor transport capacity of 800 t / h and above, therefore, conveyor power greater growth. Pingdingshan Coal
3、Mining Group Company to as an example, the scraper conveyor of power in most 400 (2 200) kW and above, the largest for the 750 (2 375) kW. Scraper conveyor to the start-up launched mainly two-speed, limited by a small number of filling hydraulic coupler, which started two kinds of ways, not only ope
4、rating costs, and it stands high. Therefore, the need to seek new technology and equipment to meet the requirements of high yield and high efficiency. 一、current situation and existing problems (一) limit filling hydraulic coupler in the high-power, big load, its size, when it with the motor and reduc
5、er connection, the greater the share of space. Limited space in the work of the occasion, too much volume will scraper conveyor layout difficult. Coupled with increased hydraulic transmission distance and high-speed rotating state and easy to have a greater impact on the radial dynamic load, and the
6、 slowdown caused by electrical installations damaged. Coupled with the input and output speed than the speed of usually no more than 97 percent, that is impossible to achieve input shaft and output shaft of sync, which must exist greater power loss, reducing the efficiency of the transmission system
7、. (二) two-speed motor drive system is currently in Chinas mining scraper conveyor in common. Under normal circumstances, the rated speed motor to start the half, corresponding to start motor power is also rated power of the half. To low-speed motor launch, when the completion of the process initiate
8、d after the switch to high-speed operation, from start to the normal operation of sub-levels, in part, reduce the impact of the launch. In this way to use the special two-motor winding, two-and two-speed cable root switch. Two-speed motor complex structure, high cost, power supply system equivalent
9、to two Motors, low-speed switching not effectively controlled, the point of failure, equipment cables, at the same time, the fault lines will be doubled the increase. 二、soft-start several advanced methods of comparison (一) thyristor surge soft-start mode. Start the process launched at the slope, pul
10、se conflict jump start, speed up the slope, fast slope. Pulse conflict way can jump start the biggest short-term output of over 95 per cent of the rated voltage, to impose a short-time great starting torque (equivalent to 90 per cent of direct starting torque), to overcome the static friction and th
11、e inertia of the transmission system. This soft-start approach and broad prospects for application. (二) viscous liquid transmission soft-start mode. Dodge is a typical U.S. company CST (consecutive start transmission) soft-start devices. CST soft-start devices currently relies mainly on imports, hig
12、h prices, the general mine unbearable. CST-mechanical, hydraulic, electronic control, cooling, materials for integrated, manufacturing, high-precision control, supply of spare parts in particular inconvenience. Scraper conveyor is moving equipment, changing work environment, the extremely bad condit
13、ions, equipment failure rate correspondingly increased, the greater difficulty of maintaining the higher operating costs and narrow work space constraints of the CST in China mine AFC Machine applications. (三) Frequency soft-start mode. Scraper conveyor used, its performance advantages not play; exp
14、ensive, the general mine unbearable; components used its power IGBT modules, high-voltage IGBT module of the international embargo on China, so its difficult to voltage levels To 1140 V, to its coal mine conveyor on the application has brought great difficulties. (四) SRM-driven approach. SRM is a ne
15、w driver, in other sectors (such as the textile industry, machinery manufacturing, washing machines, etc.) have a very wide range of applications. The main feature is activated when the current low torque, speed performance, and easy to use pure electric control to achieve stepless speed regulation,
16、 and long run. Motor exclusive use of SRM, but flow, not burning motor, with good prospects for development. Components used for power IGBT module, it is very difficult to achieve voltage 1140 V. The current high-power explosion SRM is still in the development stage, the bulk smaller, higher cost, n
17、ot suitable for the underground mine scraper conveyor application. (五) soft-start mode. Taiyuan, the company developed the Whitby soft start-FM-speed technology, speed regulator technology, vacuum technology for magnetic start one, start with the characteristics of analog FM. The surge started with
18、the way the soft start-voltage slope start, current feedback sudden jump start and start compared to the initial start more torque, can achieve the low-speed torque activated to ensure that equipment from the take-up, by Static to dynamic start running, you can solve the problem of overloading diffi
19、cult start. 三、application Pingdingshan Coal Mining Group after analysis and comparison, in October 2004 quoted a 2-QJT250/1140 (660) soft start, and Zhangjiakou Coal Factory production SGZ-764/400-scraper conveyor support, instead of the original The restrictions start filling hydraulic coupler, in
20、a small mining 6-31080 fully mechanized coal face applications, is now running for six months, and its soft-start control of the scraper conveyor incident does not appear, better-performing. The starter the following key features: and hydraulic coupler, compared with two-speed motor, scraper conveyo
21、r drive system and power supply system to maximize the simplified, the reliability of the system significantly increased. start the process of, 5 s power to block protection. start the process of automatic measurement load, automatically determine sudden jump start, the commencement of the biggest o
22、bstacles, the largest motor torque, the buck started to overcome the shortcomings. the starter all-digital control circuit, is set up to facilitate the actual starting current can be accurately controlled in the following 4 Ie, the current small motor launch, reduce the impact of the power grid. scr
23、aper conveyor loaded with empty and a smooth start to maximize the Elimination of Transmission of the fixed-load, effectively preventing the Duanlian, breakpoints, roller key transmission components, such as damage to the accident. VVVF soft start with a fuzzy control technology, based on load autom
24、atically determine the size of start-up time. Load large, extended start-up time, reduce the equipment dynamic impact load hours, because of the dynamic impact of the equipment smaller, the system automatically reduce the start-up time, can reduce the impact of the motor life. Mine transportation eq
25、uipment, long working hours (16 18 h / d), a large number complex system, supporting equipment, supporting links, delivery of materials by block, the impact of waste, launched frequent launch accidents. Fully-face failure in the electrical and mechanical equipment, scraper conveyor failures accounte
26、d for about 40 percent. In light of the above reasons, and because of soft-start the development of fully mechanized coal face scraper conveyor launch control for technical improvements is not only necessary but also feasible. SCR Mine scraper conveyor soft-start is the high yield and high efficienc
27、y fully mechanized coal face of the important technology and equipment, with great application value. The projects successful application to reduce the fully mechanized coal face mechanical and electrical accidents, improve yield and reduce consumption is of great significance.翻译部分矿用刮板输送机软启动方式的选择与应用
28、在煤矿高产高效综采工作面的建设中,以工作面大采长、大走向的要求配套了大功率的采煤机和刮板输送机。普通综采工作面的采长一般在150m左右,刮板输送机的运输能力500t/h左右;而高产高效综采工作面的采长一般达到180300m,刮板输送机的运输能力达800t/h以上,因此,输送机功率增长较大。以平煤集团公司为例,刮板输送机的功率大都在400(2200)kW 以上,最大的为750(2375)kW。刮板输送机的启动以双速启动为主,少数采用限矩型液力耦合器,这2种启动方式,不仅运行费用高,而且停机率高。因此,需寻求新的技术和装备来满足高产高效的要求。一、目前现状及存在的问题(一)限矩型液力耦合器在大功率
29、、大负荷时,本身体积庞大,当它与电动机和减速机联接后,所占空间更大。在工作空间受到限制的场合,过大的体积会使刮板输送机的布置变得困难。液力耦合器增大了传动距离,并且在高速状态旋转,易产生较大的径向动负荷冲击,而造成电动机和减速装置的损坏。耦合器的输出转速与输入转速之比通常不高于97%,即无法实现输入轴和输出轴的同步,因而必然存在较大的功率损失,降低了传动系统的效率。(二)双速电动机驱动系统目前在我国矿用刮板输送机中普遍采用。通常情况下,电动机以额定转速的一半启动,相应地启动功率也是电动机额定功率的一半。电动机以低速启动,当完成启动过程后再切换到高速运转,从启动到正常运转分两级进行,部分地减小了
30、启动冲击。这种方式要使用专门的双绕组电动机、双根电缆和双速开关。双速电动机结构复杂,造价高,供电系统相当于2台电动机,低速切换不易有效控制,故障点多,经常出现启动失败。随着综采工作面的推进,要不断地移动设备和电缆,增大了设备电缆移动的难度,同时,电缆的故障也会成倍的增加。二、几种先进软启动方式的对比(一)晶闸管调压软启动方式。启动过程分斜坡启动、脉冲突跳启动、加速斜坡、快速斜坡。脉冲突跳启动方式可以短时输出最大达95%的额定电压,施加一个短时的大启动力矩(相当于90%直接启动转矩),以克服大的静摩擦力和大的传动系统惯性。这种软启动方式应用前景广阔。(二)液体粘性传动软启动方式。典型的是美国Do
31、dge公司CST(连续启动传动)软启动装置。CST软启动装置目前主要依赖进口,其价格昂贵,一般矿井难以承受。CST集机械、液压、电子控制、冷却、材料为一体,制造、控制精度高,备件供应特别不便。刮板输送机是移动设备,工作环境不断变化,条件极为恶劣,设备故障率相应增大,较大的维护难度、较高的运行成本和狭窄的工作空间限制了CST在我国矿用刮板输送机上的应用。(三)变频软启动方式。应用于刮板输送机上,其性能优势得不到发挥;价格昂贵,一般矿井难以承受;其功率元件采用IGBT模块,高电压等级的IGBT模块在国际上对我国禁运,所以其电压等级很难达到1140V,给其在煤矿井下输送机上的应用带来了很大的困难。(
32、四)开关磁阻电动机驱动方式。开关磁阻电动机是一种新的驱动方式,目前在其他行业(如纺织工业、机械制造业、洗衣机等)有着十分广泛的应用。主要特点是启动时低电流大转矩,调速性能好,容易用纯电气控制实现无级调速,并可长时间运行。电动机采用专用开关磁阻电动机,不过流,不易烧毁电动机,具有良好的发展前景。因功率元件采用IGBT模块,电压等级很难达到1140V。目前大功率防爆开关磁阻电动机尚处于研制阶段,批量较小,成本较高,不适合在煤矿井下刮板输送机上应用。(五)调压调频软启动方式。太原惠特公司研制的调压调频软启动器集调频调速技术、调压调速技术、真空磁力启动器技术为一体,具有模拟调频启动的特点。该启动方式与
33、调压软启动器的电压斜坡启动、电流反馈启动及突跳启动相比,具有更大的初始启动转矩,可实现低速大扭矩启动,确保设备从张紧开始,由静态启动到动态运行,可以解决重载难启动问题。三、应用情况平煤集团经过分析对比,于2004年10月引用了2台QJT250/1140(660)调压调频软启动器,和张家口煤机厂生产的SGZ-764/400型刮板输送机配套,代替原来的限矩型液力耦合器启动方式,在一矿丁6-31080综采工作面应用,现已运行6个月,软启动器及其控制的刮板输送机未出现事故,效果较好。该启动器主要特点如下:与液力耦合器、双速电动机相比,刮板输送机传动系统和供电系统得到最大的简化,系统的可靠性显著提高。启
34、动过程中,5s堵转断电保护。启动过程中,自动测量负载,自动确定突跳启动点,在启动阻力最大时,电动机的扭矩最大,克服了降压启动的缺点。该启动器采用全数字控制电路,功能设定方便,实际启动电流可以精确地控制在4A以下,电动机启动电流小,减少了电网冲击。刮板输送机满载及空载启动平稳,最大限度地消除对传动部分的动冲负载,有效防止了断链、断点、滚键、损坏传动元件等事故。调压调频软启动器采用了模糊控制技术,依据负载的大小自动确定启动时间。负载大时,延长启动时间,减少对设备的动载冲击;负载小时,由于对设备的动载冲击较小,系统自动缩短启动时间,可减少对电动机寿命的影响。矿井运输设备工作时间长(1618h/d),数量多,系统复杂,配套设备多,配套环节多,运送的物料受块度、矸石的影响,启动频繁,启动事故多。综采工作面机电设备故障中,刮板输送机故障占到约40%。鉴于以上原因,又由于软启动技术的发展,对综采工作面刮板输送机启动控制进行技术改进不仅是必要的,而且是可行的。晶闸管调压调频矿用刮板输送机软启动器是高产高效综采工作面的重要技术与装备,具有较大的推广应用价值。该项目的成功应用对减小综采工作面机电事故、提高单产、降低消耗具有重大意义。