Lowering Energy Costs Through Innovation

Improving energy and production efficiencies is key to making manufacturing competitive in a global marketplace.

Textile World Asia Special Report

T he issue of energy savings is currently a big topic worldwide. The discussion is also very much in vogue in the textile industry. The energy cost factor has always played a significant role in the production of textiles. Globalization under fierce competition has resulted in low market prices for yarns, thus lowering margins. By contrast, energy costs have experienced an increase of approximately 50 percent over the past 10 years.

Consequences today: Those who ignore energy-efficient production will not survive in the mass market. Concerning the future, the following applies: Energy costs will continue to climb because fossil fuel quantities are finite. Even though new supplies continue to be discovered, development and extraction are becoming increasingly expensive. Alternative energies, such as sun, wind, water or regenerative sources are not yet competitive without subsidies. Their time will come, at the latest after current energy costs have doubled. Specialists predict such a price level by the year 2020.

Energy = Costs

This simple formula allows an introduction of the topic by means of a cost analysis. When looking at the structure of manufacturing costs for a carded yarn in the spinning mill, it soon becomes obvious that 72 percent of the manufacturing cost is found in the spinning process (See Figure 1). Only 28 percent of the total manufacturing cost is needed for spinning preparation. A breakdown of the cost structures according to resources produced in the blow room and carding, illustrated in the second chart shown  in Figure 1, quickly shows the point at which suitable energy and cost savings are the most efficient.

Particularly in spinning preparation for cotton, the hidden energy waste must be considered in addition to the pure energy costs. Often, part of the waste is refed, creating further energy consumption for waste fibers. Reduced waste quantities increase the output and consequently improve the relationship between energy input and production. Energy savings can be divided into three areas:
•    production increase per production unit;
•    reduction of waste portion without quality loss; and
•    general innovative, energy-saving concepts.

Production Increase Per Production Unit

The simplest formula for saving energy and overall costs is the production increase per production unit. To date, spinning preparation machines work mainly on the basis of mechanically active principles — for example, gravity, friction, positive locking and centrifugal force. Such machines have high idle losses. What are idle losses? When operating a textile machine without production, the average incurred energy costs are already 60 percent, as compared to full production capacity utilization. Increasing production definitely saves energy. For example: On two production units, there is a 2 x 60-kilowatt (kW) no-load output plus a 2 x 40-kW pure production output, which results in 200 kW total consumed output. If production is doubled to 1,000 kg/hr on one unit, there is a 1 x 60-kW no-load output plus a 1 x 80-kW pure production output, for a total consumed output of 140 kW. In this case, energy savings of 30 percent are achieved (See Figure 2). This simple formula is well-known by machinery and textile manufacturers; nevertheless, it is not a great innovation. The enormous challenge lies in the development of methods to increase production without losing quality and energy efficiency.

Reduction Of Waste Portion Without Quality Loss

With regard to the data shown in Figure 1 and the distribution of costs for resources in spinning preparation, it quickly becomes evident that the resource waste becomes more and more important, and thus accounts for a significant share of the manufacturing costs. To prevent a loss of quality, cleaning elements are intensified, particularly by increasing production. Germany-based Trützschler GmbH & Co. KG has applied intelligent solutions to its products to help reduce energy waste while maintaining quality.

Waste control in the blow room: For the roll cleaners CL-C1, CL-C3 and CL-C4, Trützschler offers Wastecontrol for the blow room. A sensor checks the waste quality and automatically decides the setting of the separation point. Depending on material and production size, the amount of separated waste is only as much as necessary for efficient cleaning. In practice, Wastecontrol quickly results in savings of US$50,000 per cleaning unit per year without any loss of quality.

Waste control at the card: The card offers the highest degree of cleaning in the cotton spinning process. Intensive cleaning results in high amounts of wasted energy. Every specialist knows that a decrease in production causes an increase in relative waste (See Figure 3). The reason for this is the approximately constant absolute waste quantity, independent of production. To conserve energy, a large working width is considered critical. If a production gain is achieved corresponding to working width, then the relative waste quantity remains constant. If the production gain is less, more relative waste is separated.


Carding concepts in the market have 1- or 1.5-meter working widths and are operated in spinning mills with similar outputs per production unit. Principally, on a machine with 1-meter width, fewer good fibers are separated because of the higher production ratio per meter; therefore, this concept offers higher resource conservation.

General Innovative, Energy-Saving Concepts

Innovative concepts and intelligent components can reduce energy consumption, independent of production size.

Only as much air as actually needed in the blow room: Trützschler’s Airflow Control is already state-of-the-art. In the bale breaker process, air quantities are kept constant during continuously changing suction lengths, thus lowering the average transport air quantity and reducing the costs for disposal of dust-laden air (See Figure 4).


Waste suction: When looking at cards and comparing a 20-year-old model to a current model, it becomes evident that between 1988 and 2008, the energy consumption of just the disposal air quantity alone has been reduced by more than 50 percent (See Figure 5). In this case, the customer benefits from the increased productivity as well, though also from intelligent individual measures. All air-carrying elements on a Trützschler machine are optimized (See Figure 6). By adjusting the cross sections of flow by means of finite element calculation for example, it has been possible to reduce the negative suction pressure within the last 20 years from 1,200 to 700 Pascals.


Drive Technology: Direct current technology is definitely a thing of the past for market-leading machine manufacturers. Today, modern machines with speed-constant parts are driven by asynchronous technology; and machines with speed-changing drives, alternately by synchronous servo technology or asynchronous frequency control.


When comparing these technologies in reference to energy consumption, the following must be stated: The supplier’s information concerning energy efficiency of drive systems always is in relation to nominal loads at nominal speeds. When values drop below these levels, each drive system loses efficiency and, in turn, energy efficiency to a greater or lesser extent. This means operating a drive system at full load saves energy. But this also means that the popular approach of integrating safety and power reserves in a drive concept uses only unnecessary energy. The ratio of installed output to actual input, therefore, should be as close as possible. The efficiency of the alternating current drive in particular is on a significant lower level compared to an A/S synchronous drive (See Figure 7).


Thus, for speed-changing drives, Trützschler decided more than 15 years ago in favor of servo technology, which offers good efficiency at varying maximum speeds. Even though today’s developments, for reasons of comfort and control, often use a frequency converter to enable a speed change by means of control input, and not by exchange of a belt pulley, it must be noted that this comfort is at the expense of additional energy. This, among other things, is made clear by the fact that in addition to the actual asynchronous motor, which should be driven in a speed-changing manner, a control unit corresponding to the output must be installed. On this control unit, the additional energy consumption is only noticeable in the form of heat generation.

The future belongs to those textile manufacturers that currently intensively deal with the energy cost factor. The same applies to the machine manufacturer who is expected to develop energy-efficient technologies and make them available to the market.

Editor's Note: This article was written by Armin Leder, Trützschler GmbH & Co. KG.

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Summer 2008

 

通过革新降低能耗

节 能问题无疑是全球关注的焦点问题，与此相关的种种讨论在纺织业界同样风行。能耗因素在纺织生产中始终占有举足轻重的地位。由全球一体化带来的激烈竞争已经造成纱线 市场价格低廉，同时也削薄了利润。与之形成对比的是，在过去十年中，能耗已增长近50%。其影响在今日已经显现：那些忽视节能生产的企业将无法在大市场上生存下去。放眼未来，我们应注意到如下问题：鉴于化石燃料的数量是有限的，能耗必将持续攀升。尽管人们在不断发现新能源，但在开发与提取环节中的费用正日益昂贵起来。诸如太阳能、风能、水能或是可再生资源等替代能源在没有补贴的情况下，竞争力仍有待提升。不过，当目前的能耗翻倍之后，这些新能源的时代必将来临。专家预测，这种价格水平将在2020年左右出现。

能源=消耗

个简单的等式，涉及一个成本分析的概念。在纺纱厂中，注意一下经过梳棉工序纱线的生产成本构成，你会很快发现，其中72%的部分用于纺纱过程中(见表格1)。总成本中，只有28%用于纺纱的准备过程。根据表格1种显示的第二个图表上画出清棉和梳棉过程中产生的资源，成本结构的细目分类明确表示出，在效率最高的时候，可以适当节约能源和成本。特别是在棉花纺纱的准备过程中，在纯粹的能耗之外，我们还必须考虑隐藏的能源浪费。很多时候，废物中的一部分会继续被"喂给"，为废弃纤维制造更多的能量消耗。废品数量的降低可以增大产出，最终优化能源投入与生产之间的关系。节能可以

分为三个领域：
－－每个生产单位的产量增加；
－－在质量不变的情况下减少废品比例；
－－全面的革新与节能理念。

每个生产单位的产量增长

对于节约能源与整体成本而言，最简单的公式就是提高单位产量。到目前为止，纺纱准备机主要以机械基本要素为工作基础 －－ 例如，重力、摩擦和地心引力。这种机器的空转损耗率高。什么是空转损耗?  在不出产品的情况下运转一台纺织机，其平均能耗已达全负荷生产的60%。提高产量必然可以节约能源。举个例子：在两个生产组组件，空载输出率2 x 60-千瓦 (kW)，纯产品输出为 2 x 40-kW，供消耗200kW的能量。如果产量可以增加一倍，达到1000公斤/小时，那么空载输出率为1 x 60-千瓦 (kW)，纯产品输出为2 x80-kW，总耗能输出为140kW。在这个例子中，我们做到了节约30%的能源(见表格2)。这个的公式为机械和纺织生产商所熟知，然而，这并不是一个伟大的创新。当人们在寻求提升产量的同时，不降低质量或影响能源效率，人们会碰到很大的挑战。

在质量不变的情况下减少废品比例

通过表格1中的数据与纺纱准备中各种资源的成本分布，我们很容易发现，资源废物变得日益重要起来，在生产成本中占有重要地位。为了防止质量下降，清洗元素得到强化，特别是通过增大产量。德国特吕茨勒公司在其产品上使用了智能解决方式，以帮助降低能耗，同保证产品质量。品在清棉间的控制:  对于滚筒清洁机CL-C1、CL-C3和CL-C4，特吕茨勒推出了可以在清
棉机中Wastecontrol废品控制机。一个传感器可以检测废品质量，并且可以自动设定区分点。根据材料和产品型号的不同，分开废品的数量以可以进行有效清洁为准。在实践中，Wastecontrol每年在每一个清洁组件中可以节约5万美元，同时也不会造成质量下降的问题。在梳棉中的废品控制:  梳棉机带来了棉花纺纱过程中最高级别的清洁度。彻底的清洁带来了能源的浪费。每位专家都知道，产量的降低都会引起相关废物量的增加(见表格3)。其中的缘由在于几乎恒定的绝对废品数量是独立于产量的。为了保存能源，较大的工作宽度就显得尤为重要。工作宽度可以带来产品收益，那么相关的废品数量也会保持稳定。如果产品收益下降，那么也会分离出更多的相关废品。市场中的梳棉概念有1或1.5米的工作宽度，两者在纺纱厂的单位组件产品产量几乎相同。大体上讲，在1米宽的机器上，分离出的优质纤维更少，因为每米的产量比率更高；因此，这一理念也就可以保存更多的资源。

全面的革新与节能理念

革新理念与智能部件可以减少能源消耗，这与产品的型号无关。在清棉间，只需输入足够的空气即可:  特吕茨勒公司的Airflow Control 气流控制机已经具备顶尖工艺水平。在开包的过程中，尽管抽空时间长短在不停改变，但气流量可以保持恒定，由此一来，也 就可以降低平均运输空气数量，并减少载尘空气的成本 (见表格4)。物抽气:  当观察梳棉机，并比较二十年历史的老机型和当代机型，人们很容易看到，在1988 年到2008 年间，仅空气排放时的能源消耗就降低了超过50% (见表格5)。在此事例中，客户除得益于智能的个性化手段外，也同样会从增加的产量中获益。在特吕茨勒生的机器中，所有的载气元素均已经过优化 (见表格6)。通过调节气流管道的横截面 －－比如说，可以通过有限的元素计算 －－ 在未来20年内将负面吸气压力从1200 帕斯卡将至700 帕斯卡是完全可能的。机技术:  对市场主流机器生产商而言，直流电技术无疑早已过时。时至今日，配有速率常数组件的现代机器由异步技术驱动；带有变速发动机的机器，可以交替使用同步伺服技术或异步频率控制。当将上述技术联系到能源消耗时，我们可以从这里着手：供应商关于发动机系统能源效率的信息始终与定额速度运转下的定额载负相关。当数值低此水平时，每个驱动系统将处于低效状态，此时的能源使用效率将在过大或过小的范围内。但是，这也意味着，关于将保装置与备用功率统一在一个驱动概念中的流行理念，使用了不必要的能源。由此一来，固定产出与实际投入的比率则应尽可能接近。与A/S同步驱动相比，特别是交流电驱动的效率尤其低(见表格7)。因此，对于变速驱动装置，特吕茨勒公司早在超过15 年前就已经确定了对伺服技术的偏好。它可以在改变最大速度的同时，保持较高的效率。尽管随着今日技术的发展，为了舒适与控制的需要，人们常会选择使用频率转炉，从而通过控制输入，而非转换皮带轮完成速度转换。需要注意的是，这种相对方便的方式是以消耗额外能源为代价的。这 一点与其它问题相同，均通过以下方式显现，那就是：除了应由变速方式驱动的实际异步电动机外，还要安装一个与输出相对应的控制组件。在该组件上，额外的能量消耗只是通过热能排放的方式人们所注意。未来属于那些目前正即重力力量对付能耗问题的纺织品生产者。这也同样适用于被寄予期望，研发高能效技术、并将之推向市场机器生产商们。

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