斗式提升机外文翻译.doc

斗式提升机的泄爆排气
摘要
This paper is a report of an experimental programme on the explosion protection of bucket elevators by venting. The project was a collaborative effort with funding by the Health and Safety Executive and manufacturers and users of bucket elevators through the British Materials Handling Board. Two bucket elevators were used in the project—a single leg elevator and a twin-leg elevator. Four dusts were used with KSt values up to 211 bar m s−1 and dust clouds were produced by dust injection and by normal operation. Reduced explosion pressures were measured and guidance has been derived from the results. This guidance is in terms of vent spacing as a function of the KSt value of the dust.
本文介绍附在斗式提升机上的防爆装置的泄爆实验。该项目是由卫生安全部门以及制造商和用户委托英国材料处理部门执行。两斗式提升机中使用了一个单腿电梯和一双腿电梯。测量了爆炸压力和已经衍生出的结果。本指南是根据排气间距为尘埃中的值函数。
Keywords
关键词：粉尘爆炸；发泄；斗式提升机
Bucket elevators are widely used in the handling of large quantities of bulk powders and are normally the preferred means of conveying where long vertical lifts are required for free flowing powders/granular products. As such they are to be found in nearly all animal feed mills, bulk grain stores and many of the larger installations handling powders in the food industry. Powder or granular products inevitably spill from the buckets during operation and fall down the upleg of the elevator. The finer material is likely to remain in suspension while the coarser material falls back to the boot. At the top of the elevator most of the powder will discharge down the off-take chute, but some will normally be carried over into the downleg of the elevator. Thus both legs are likely to contain a dust cloud of unknown concentration, constantly agitated by the moving buckets, all the time the elevator is in operation. Various sources of ignition are foreseeable in such units and explosion incidents have been reported.

斗式提升机广泛应用于处理大批量散装粉末，是自由流动的粉末或颗粒长距离垂直输送优先选择。正是因为这样他们可以在几乎所有的动物饲料以及散装谷物的商店和许多大型设备在食品工业中用于处理粉末。粉末或颗粒状产品在操作中不可避免地溢出。较细的物料可能会保持在悬浮液中而较粗的物料落回地面。在斗提机顶部的大多数粉末会从出料口流出，但有一些粉末通常会被带到斗提机的下部。因此，在斗提机运行的整个过程中两条输送带可能含有未知浓度的粉尘云，不断的被搅动着。各种可预见的火灾和爆炸事件纷纷报道出来。
Explosion venting is one method for explosion protection of bucket elevators. The current Institution of Chemical Engineers guidance requires that the vents—equal in cross sectional area to the limb—are positioned according to the guidance for ducting. Alternatively, a spacing of 6 m between vents is used. The guidance also requires that the top casing and the boot must be explosion relieved (Lunn, 1992).
泄爆是斗式提升机的防爆方法之一。当前的化学工程师建议，距通风口相等的横截面面积的位置安装管道。另外，每隔6米设置一个通风口。该建议还要求机壳顶部和尾部都要具有爆炸缓冲作用（伦恩，1992）。除了德国似乎没有其他欧洲国家给出建议，但是美国消防协会NFPA文件—91：在预防火灾和在农业粮食粉尘爆炸设施给出更为详细指导但仍建议排气口的间距为6米。
There appears to be no guidance from other European organisations such as the German VDI, but the USA National Fire Protection Association document NFPA-91: Fires and dust explosions in agricultural and food products facilities gives guidance in somewhat more detail than Lunn (1992) but still recommends a vent spacing of approximately 6 m.
然而，没有任何证据表明当前使用的通风方法是最佳通风要求，也很少有人发表斗提机爆炸实验的文章。吉利斯和费世科（1982）进行排气和抑制实验对双通道斗提机提供了一些指导意见。
This paper describes an experimental programme, a collaborative effort by the Health and Safety Executive and manufacturers and users of bucket elevators under the British Materials Handling Board, in which explosion venting of bucket elevators was studied using a single leg elevator and a twin leg elevator with a number of flammable dusts. Reduced explosion pressures have been measured and the results used by the Health and Safety Executive to develop guidance for practical use.
本文描述了一个实验方案，由卫生和安全执行局和制造商和斗式提升机用户英国材料进行试验，在斗式提升机的泄爆通风的研究中使用一个单通道斗提机和产生大量的可燃粉尘的双通道斗提机为研究对象。减爆炸压力测式给卫生安全执行局提供了一些使用的指导意见。
1. Experimental

1.实验
Two bucket elevators have been used in this programme: a single leg elevator and a double leg elevator. Both elevators were mounted in a tower with access levels at 2.7 m intervals.
两中斗提机已经用这一方案：单通道和双通道斗提机安装在一个车间内，2.7米的间隔。
1.1. Single leg elevator
1.1.单腿电梯
A schematic diagram of the elevator is shown in Fig. 1. The single leg steel casing is rectangular in shape, with a cross section of 1.22 m×0.945 m, in which the chain linked buckets of nominal dimensions 540 mm wide×280 mm×390 mm, with a spacing of approximately 450 mm, run up and down. It has a fixed speed drive mounted at the head of the elevator powered by an 11 kW motor and gearbox that drives the buckets at a speed of approximately 35 m/min. The drive pulley and a deflector pulley are mounted within the head of the elevator and a return pulley is mounted at the boot of the elevator.
电梯的示意图如图1所示。单通道斗提机的形状是矩形的，1.22米的×0.945米的横截面，其中链条连接料斗的实际尺寸540毫米，宽280毫米，长390毫米，间距约450毫米，上下运行。斗提机顶部安装一个提供恒转速功率11千瓦的电机和变速箱带动料斗的速度约35米/分钟。驱动滚筒和偏道滚筒固定在斗提机头部滚筒安装在斗提机尾部。
泄爆口分别安装在每节机壳上，包括电梯的顶面，尺寸等于标称截面的电梯机壳尺寸（1.22毫米×0.945米）

除了第8级，因为支撑钢构件的限制：一个轻微小型的孔（0.945米×0.7米）常闭式塑料通风面板用于大多数测试中。不锈钢孔板也被用在一些测试中。
Dust injection cylinders were located at each of the nine levels at intervals of 2.7 m. Their position at each level alternated from side to side. Distribution of the dust injection points along the elevator enabled a well-dispersed dust cloud to be produced throughout the elevator casing. An ignition source could be fitted at level 1, level 5 or level 9 (see Fig. 1). Pressures were measured at up to nine positions along the full height of the elevator.
灰尘注射缸分别位于九个机壳，间隔为2.7米。他们的位置在每节机壳从一侧到另一侧交替。使灰尘在机壳内良好的分散。点火源可以安装在1级，5级或9级（参见图1）。测量压力点从上到下分布在九级机壳上。
1.2. Twin leg elevator
1.2 双腿电梯
The twin leg elevator (Fig. 2) was supplied by Carier Bulk Materials Handling Ltd and represents a typical elevator used in the bulk handling industry. The casing was designed to a stronger specification than normal to enable it to withstand the explosion pressures developed in the tests. The elevator head, boot and a 1.5 m long leg section were each hydrostatically tested to 1.5 bar g. The overall height from the base of the boot to the top of the head section was 17.75 m.
双腿电梯（图2）是由载体散装物料搬运公司提供的，一种典型的用于处理散装物料工业斗提机。在试验中机壳设计一个强大的规格比正常机壳承受爆炸压力。电梯的头部，机壳和一条1.5米长的腿部分别进行水压试验1.5bar g.底部到顶部总高度是17.75米。
料斗的最大尺寸308毫米宽，175毫米深×130毫米高，用螺栓固定在320毫米宽的胶带上。皮带是由直径为0.6米的冠头轮驱动，速度为3米/秒。一般情况下，当料斗满载，将携带约1.7公斤的玉米粉或1.3公斤牛奶粉。利用离心作用当料斗绕过主动滚筒时物料卸载。
The design clearances are, approximately: between the tip of the buckets and the front of the casing: 70 mm, between the sides of the buckets and casing: 41 mm, and between the rear of the belt and the casing: 55 mm.
设计间隙约：料斗的顶端和壳体的前端之间：70毫米，料斗的两侧和机壳之间：41毫米，以及带后端与外壳之间：55毫米。
Explosion relief vent openings were installed at approximately 3 m intervals on both legs and measured 305 mm wide×457 mm high (0.139 m2). The bottom edge of the first relief panel was 2.875 m from the base. A single explosion vent was located at the side of the head. Either aluminium foil or proprietary stainless steel panels with a nominal burst pressure of 100 mbar were used as the vent closures. The cleaning door at the boot was modified to incorporate a safety panel designed to protect the boot in the event of excessive pressure. This was covered with a strong burst panel with a bursting pressure in excess of 400 mbar.
防爆泄压排气口安装在两条通道约3米的间隔以及排气孔的尺寸305毫米宽，457毫米高×（0.139平方米）。第一个排气板底部边缘距离地面2.875米。一个单一的爆炸通风口位于头部的侧面。无论是铝箔或者专有的不锈钢板与标称的100毫巴的爆破压力为排气塞。清洗门在引导气流改变运动方向，在压力过大时安全面板保护壳体。这是覆盖一个爆裂压力在400毫巴超额突发性强的面板。
Dust could be dispersed into the elevator using a pressure injection system or by a recirculation system. Dust was injected into each leg at each level simultaneously via nozzles located flush with the inside of the casing. Pairs of nozzles were positioned at each level. Seven injector assemblies were fitted to the elevator, one at each floor level.
灰尘可以使用高压喷射系统或循环系统分散到斗提机内部。灰尘被注入到每个通道以及每个壳级，同时通过位于该壳体内部冲洗喷嘴。双喷嘴被放置在每个壳级。七个喷油器组件被安装到斗提机每个壳级。
In the recirculation system, dust is initially loaded into the elevator via a chute at the bottom of the up-leg and conveyed to the head where it is discharged into a recycle leg. The discharged dust falls under gravity through the leg to the elevator inlet and is reconveyed back up the elevator. The recycle leg has a square cross section measuring 250 mm×250 mm and incorporates an intermediate 2 m3 capacity holding bin. The bin and the leg are protected by explosion relief panels. The bin is fitted with two explosion relief panels on the top face and the recycle leg has four explosion panels. Removal of dust from the elevator is achieved by directing the dust, as it flows from the bin, to a discharge duct by the operation of a diverter valve. The diverter valve is located 3 m below the bin.
在再循环系统，粉尘最初通过上上升通道从底部输送到头部的地方加载到斗提机内部然后进入循环系统。排出的灰尘落在重力作用下，通过斗提机下降通道，又回到了电梯。回收站具有方形截面的测量250毫米×250毫米，包括中间2立方米的容量。箱子和通道是由防爆缓冲板保护。箱子顶端安装两个专门设计泄爆板顶面，回收的通道有四个专用防爆板。The ignition source was installed in the elevator casing at either level 1 upleg (close to the boot), level 7 (close to the head of the elevator) or at an intermediate point in the leg (see Fig. 2). Explosion pressures were measured at 14 points, located in both legs at 3 m intervals.

点火源安装在机壳，其他地方在上升通道第一壳级（接近地面），7级（靠近电梯的头部）或在通道中间部位（见图2）。有14个爆炸压力测量点，位于两条通道间隔3米。
1.3 粉尘
Four dusts were used in the tests:
四粉尘进行测试：
milk powder: KSt=86 bar m s−1, Pmax=7.4 bar g;
奶粉：KST = 86barms
，Pmax = 7.4 G；
cornflour A: KSt=147 bar m s−1, Pmax=7.9 bar g;
玉米：KST = 147barms，Pmax = 7.9 G；
cornflour B: KSt=211 bar m s−1, Pmax=8.0 bar g;
玉米B：KST = 21barms ，Pmax = 8 G；
cornflour C: KSt=180 bar m s−1, Pmax=8.7 bar g.
玉米C：KST = 180barms ，Pmax = 8.7 G.
2. Experimental results
2 实验结果
2.1. Single leg elevator
2.1 单腿电梯
A series of tests was performed to determine the optimum conditions of injection pressure, dust concentration and ignition delay that produced the highest explosion pressures. The optimum conditions were used throughout the main test programme.
进行了一系列试验，确定注射压力的最佳条件下，粉尘浓度、点火，产生的最大爆炸压力延迟。整个主测试计划使用最佳实验条件。
2.2. Effect of ignition position
2.2 点火位置效应
Three ignition positions have been used in the complete series of explosion tests—top (level 9), middle (level 5) and bottom (level 1) of the elevator. The results show that any one position is not significantly more hazardous than the others. There was a tendency, where the ignition source was located at level 1 or level 9, for the peak pressure to be measured at level 9. The likely cause of this is the congestion in the elevator head, with buckets, drive and deflection pulley wheels all mounted in close proximity—these obstacles would tend to produce enhanced turbulence and act to restrict the venting of the explosion.
三点火位置已被应用于整个爆炸试验—他们分别是斗提机的高（9级），中（5级）和底部（1级）。结果表明，每一个位置都没有显著地威胁。有一种倾向，在点火源位于1级或9级，、峰值压力出现在在9级的测量点。在斗提机内部，由于料斗，驱动滚筒和偏转滑轮安装比较密集。这些障碍往往会产生较强的涡流以及限制通风。
When the igniter was located at level 5 the explosion propagated towards the head and the boot and resulted in peak pressures at a range of locations. Although there was no definite pattern to the location of the peak pressure, its most frequent location was at level 9.
当点火器位于5级时爆炸朝向头部和尾部传播，导致压力峰值在一个范围内出现。虽然没有明确的峰值压力的位置，但其最常见的位置是在9级。
2.3. Effect of moving buckets
2.3 移动料斗效应
The results showed that operation of the buckets had no significant effect on the reduced explosion pressure compared to when the buckets were stationary.
结果表明，料斗在运动和静止爆炸压力没有显著地变化。
2.4. Measurements of reduced explosion pressure
2.4 降低爆炸压力测量
A series of experiments was performed with milk powder, cornflour ‘A’ and cornflour ‘B’, using vent closures with various opening pressures. The opening pressure of a vent closure was measured during each test so that an indication could be obtained of the overpressure at which the venting process began. Initially, tests were done with all vents acting as explosion relief; as the programme proceeded vents were progressively blanked off to decrease the available venting area.
一系列的实验是用奶粉，玉米粉A和玉米粉B然后使用排气孔调解不同的压力。一个通风口关闭开启压力的测定在每个测试这样的指示可以得到超压，排气过程开始。最初，测试完成与所有通风孔作为泄爆口；作为计划的进行逐渐关闭以减少可用的排气孔面积。
The overpressure that develops at different points in the bucket elevator depends on the ignition position and the number of vent openings. Some examples of the pressure variation along the elevator during an explosion are given in Table 1. Numbers 1–9 in Table 1 are cornflour ‘A’ tests; 10–13 are cornflour ‘B’ tests. Variations in the dust dispersion, explosion propagation and pressures at which vents open lead to a spread of maximum reduced explosion pressures for nominally identical experiments.
斗式提升机在不同地点的超压的发展取决于点火位置和排气口的数量。爆炸压力沿斗提机变化的一些例子在表1中给出了。数字1–9是玉米粉A试验；10–13玉米粉B试验。由于粉尘分散度的变化，爆炸传播和通风口的打开从而导致传播的最大爆炸压力值降低。
通过绘制最大爆炸压力测量值，对结果进行预测分析，对试验过程中测得的排气口的压力。
2.4.1. Cornflour ‘B’
2.4.1 玉米粉“B”
Fig. 3 shows all relevant test results using Cornflour ‘B’, for various explosion-venting arrangements.
图3显示了所有的玉米粉B，不同泄爆测试结果，。
2.4.2 玉米粉“A”
Fig. 4 shows all the relevant test results using cornflour ‘A’.
图4显示了所有玉米粉“A”的测试结果。
Fig. 4.
2.4.3. Milk powder
2.4.3 奶粉
Explosions of milk powder generated very low pressures, and, often, pressures were not sufficient to burst any of the vent covers. In the explosion tests that did burst the vent covers, pressures did not rise beyond the bursting pressure of the cover.
奶粉爆炸产生非常低的压力，通常压力不足以破坏任何排气罩。在爆炸试验中，被破坏的排气罩，压力并没有超越排气罩破裂压力。
2.5. Analysis of the results
2.5 结果分析
In order to produce a worst-case analysis of the results, the points for different total vent areas have been enveloped by straight lines. From each of these lines, an upper value of the reduced explosion pressure at Pstat values of 0.1 bar and 0.05 bar has been estimated. These pressures are plotted against the total vent area in Fig. 5 and Fig. 6, respectively. The total vent areas necessary to limit the reduced explosion pressure to either 0.5 bar g or 1 bar g have been marked on Fig. 5 and Fig. 6. The results for milk powder have been included on Fig. 5. The lines for KSt=175 bar m s−1 have been obtained by linear interpolation.
为了得到结果的最坏情况下的分析结果，该点不同的通风领域已经由直线包络。所有的线，降低爆炸压力值0.1bar和0.05bar上限值已被估计。这些压力值与总排气孔面积分别如图5和图6。总排气孔面积必须限制降低爆炸压力为0.5bar g或1bar g已经在图5和图6标出。奶粉结果已包括在图5，对KST = 175bar毫秒已得到线性差值。

2.6 双通道斗式提升机
Because there is a relatively large space around the buckets in a single leg elevator, it is generally easy to propagate a flame through the entire casing. In a twin leg elevator, however, the space around and between the buckets is limited and it is unclear, at first sight, whether the buckets either act as turbulence inducers in the flow ahead of the flame and thus cause the explosion to accelerate, or act as obstacles to flame propagation and so decrease the explosion velocity or prevent its propagation altogether.
因为在单通道斗提机有一个比较大的空间，它通常是很容易把火焰传播到过整个壳体。然而在双通道斗提机中，料斗周围的空间是有限的，目前还不清楚，乍一看，无论是作为诱导剂诱发火焰产生，从而提高爆炸速度，或者作为火焰传播障碍降低爆炸速度。
In order to answer this question, explosion tests were done in which all buckets were removed from the elevator and then replaced in stages until a full complement was re-fitted. The guidanc