1

Types of Pneumatic Conveying

Systems气力输送系统的种类  

1 INTRODUCTION导言

Pneumatic conveying systems are basically quite simple and are eminently suitable

for the transport of powdered and granular materials in factory, site and plant

situations. The system requirements are a source of compressed gas, usually air, a

feed device, a conveying pipeline and a receiver to disengage the conveyed material

and carrier gas. The system is totally enclosed, and if it is required, the system

can operate entirely without moving parts coming into contact with the conveyed

material.气力输送系统组成简单，非常适合工厂、工地的粉体和颗粒料的输送。系统要求有一个通常是空气压缩气体源、一个喂料设备、输送管道和一个分离输送物料和输送气体接收器。该系统是完全封闭的，必要情况下，该系统可以完全没有运动部件接触到输送物料。

High, low or negative pressures can be used to convey materials. For

hygroscopic materials dry air can be used, and for potentially explosive materials

an inert gas such as nitrogen can be employed. A particular advantage is that

materials can be fed into reception vessels maintained at a high pressure if required.可以使用高压、低压或负压来输送物料。输送易吸水受潮物料时要采用干燥的空气，输送易爆性物料可使用惰性气体如氮气。有需要的时候，物料也可以被输送到一个有较高压力的接受容器中。

1.1 System Flexibility系统灵活性

With a suitable choice and arrangement of equipment, materials can be conveyed

from a hopper or silo in one location to another location some distance away. Considerable

flexibility in both plant layout and operation are possible, such that multiple

point feeding can be made into a common line, and a single line can be discharged

into a number of receiving hoppers. With vacuum systems, materials can

be picked up from open storage or stockpiles, and they are ideal for clearing dust

accumulations and spillages. Pipelines can run horizontally, as well as vertically

up and down, and with bends in the pipeline any combination of orientations can

be accommodated in a single pipeline run. Material flow rates can be controlled

easily and monitored to continuously check input and output, and most systems

can be arranged for completely automatic operation. 使用合适的的设备，物料可以从一个料斗、料仓输送到远处的另一个料仓。布置灵活，操作方便，例如，可以多点喂料进一条管道，输送到多个料仓。真空吸料系统可以从敞开的存放点吸料并输送，并可以减少粉尘泄漏。输送管道可方便的水平或垂直布置。管道可以向上、向下甚至向任何方向弯曲。可方便地监测物料的进料量和出料量，并对物料输送量进行控制，在大多数的系统中这些操作都是自动进行。

 Pneumatic conveying systems are particularly versatile. A very wide range of

materials can be handled and they are totally enclosed by the system and pipeline.

This means that potentially hazardous materials can be conveyed quite safely.

There is minimal risk of dust generation and so these systems generally meet the

requirements of any local Health and Safety legislation with little or no difficulty.气力输送系统适应性强。很大一部分物料都可以在密闭的系统和管道中进行输送。这意味着有潜在危险的物料相当安全的运送，将粉尘泄漏的危险降到最低限度，这些系统一般都满足任何地方卫生和安全方面的要求。Pneumatic conveying plants take up little floor space and the pipeline can be

easily routed up walls, across roofs or even underground to avoid any existing

equipment or structures. Pipe bends in the conveying line provide this flexibility,

but they will add to the overall resistance of the pipeline. Bends can also add to

problems of particle degradation if the conveyed material is friable, and suffer from

erosive wear if the material is abrasive.气力输送系统占地小，管道可方便的沿墙壁，屋顶布置，甚至整个的穿行在地下，以避开任何现有设备或建筑物。管道通过弯曲转向提供这种灵活性，但这将增加管道总的阻力。易碎物料也将因为弯头的增加，产生更多破碎而降级。并且磨削性物料会在弯头处产生冲蚀磨损。

1.2 Industries and Materials工业和物料

A wide variety of materials are handled in powdered and granular form, and a

large number of different industries have processes that involve their transfer and

storage. Some of the industries in which bulk materials are conveyed include agriculture,

mining, chemical, Pharmaceuticals, paint manufacture, and metal refining

and processing. In agriculture very large tonnages of harvested materials such as

grain and rice are handled, as well as processed materials such as animal feed pellets.

Fertilizers represent a large allied industry with a wide variety of materials.大量不同行业都涉及以粉体和颗粒料的形式存在的多种物料的运送和存储。一些行业，包括农业、采矿、化工、制药、油漆制造、金属冶炼和处理等，其中大部分原料或产品为散料。在农业方面有非常大吨位的收获材料，如谷物和大米的处理，以及动物颗粒饲料的处理。 化肥工业中更有各种各样的物料。

A vast range of food products from flour to sugar and tea to coffee are

conveyed pneumatically in numerous manufacturing processes. Confectionery is an

industry in which many of these materials are handled. In the oil industry fine

powders such as barite, cement and bentonite are used for drilling purposes. In

mining and quarrying, lump coal and crushed ores and minerals are conveyed.

Pulverized coal and ash are both handled in very large quantities in thermal power

plants for the generation of electricity.食品行业，食糖、面粉，咖啡，茶等物料的转运需要气力输送。在石油精炼工业中，如重晶石粉，水泥，膨润土等粉体用于钻井。采矿业中，块煤和粉碎矿石和矿物需要运送。

In the chemical industries materials include soda ash, polyethylene, PVC and

polypropylene in a wide variety of forms from fine powders to pellets. Sand is used

in foundries and glass manufacture, and cement and alumina are other materials

that are conveyed pneumatically in large tonnages in a number of different

industries.热电厂产生的大量煤粉灰需要运送。化学工业的材料包括纯碱，聚乙烯，聚氯乙烯和聚丙烯等粉体和颗粒料。铸造与玻璃制造行业，需要用到砂、水泥、氧化铝及其他材料。以上这些都是气力输送在不同行业中的应用。

1.3 Mode of Conveying输送方式

Much confusion exists over how materials are conveyed through a pipeline and to

the terminology given to the mode of flow. First it must be recognized that materials

can either be conveyed in batches through a pipeline, or they can be conveyed

on a continuous basis, 24 hours a day if necessary. In batch conveying the material

may be conveyed as a single plug if the batch size is relatively small.关于物料在管道中输送的流动模式的描述很混乱。首先必须承认，物料可以分批次的间歇输送，必要时也可以一天24小时连续不断的输送。分批输送物料时，如果一次输送的物料量较少，可以以一个料栓的形式进行输送。

1.3.1 Dilute Phase稀相

For continuous conveying, and batch conveying if the batch size is large, two

modes of conveying are recognized. If the material is conveyed in suspension in

the air through the pipeline it is referred to as dilute phase conveying. If the material

is conveyed at low velocity in a non-suspension mode, through all or part of

the pipeline, it is referred to as dense phase conveying. Almost any material can be

conveyed in dilute phase, suspension flow through a pipeline, regardless of the

particle size, shape or density.连续输送,或批次输送量较大，有两种输送模式。如果物料在管道中以悬浮态输送为稀相输送。如果材料在全部或部分管道中以低速、非悬浮态的方式进行输送，为浓相输送。几乎任何材料，无论颗粒大小，形状或密度，可以以稀相，悬浮流的形式进行输送。

1.3.2 Dense Phase密相

In dense phase conveying two modes of flow are recognized. One is moving bed

flow, in which the material is conveyed in dunes on the bottom of the pipeline, or

as a pulsatile moving bed. The other mode is slug or plug type flow, in which the

material is conveyed as full bore plugs separated by air gaps. Moving bed flow is

only possible in a conventional conveying system if the material to be conveyed

has good air retention characteristics. Plug type flow is only possible in a conventional

conveying system if the material has good permeability.密相输送有两种模式。一种是移动床流，物料在管道底部形成沙丘状移动，或作为一个脉动移动床移动。另外一种是栓柱流，物料在管道中形成充满整个管道截面的料栓与气栓相间的形态。只有在被输送物料有良好的存气性，才可以以移动床形态流动。只有在被输送物料有良好的透气性，才可以以栓柱流形态流动。

1.3.3 Conveying Air Velocity输送气速

For dilute phase conveying a relatively high value of conveying air velocity must

be maintained. This is typically in the region of 2400 ft/min for a very fine powder,

to 3200 ft/min for a fine granular material, and beyond for larger particles and

higher density materials. For dense phase conveying, air velocities can be down to

600 ft/min, and lower in certain circumstances. Because of the fine particle size

required to provide the necessary air retention, particle density does not have such

a significant effect on the minimum value of conveying air velocity in moving bed

type dense phase conveying.稀相输送必须有较高的输送空气流速。输送非常细的粉末的气速为二四〇 〇英尺/分（注：12米/秒）左右，细颗粒状物料为3200英尺/分钟（16米/秒），输送大颗粒和高密度的物料需要更高气速。浓相输送，气速可降至六○○英尺/分（3米/秒），某些情况下更低。由于细颗粒大小需提供必要的空气保留，在移动床型浓相输送中，粒子密度对最小输送空气流速没有很大影响。

1.3.4 Solids Loading Ratio固体负荷率

The solids loading ratio, or phase density, is a useful parameter in helping to visualize

the flow. This is the ratio of the mass flow rate of the material conveyed divided

by the mass flow rate of the air used to convey the material. It is expressed

in a dimensionless form. For dilute phase, maximum values that can be achieved

are typically of the order of 15, although this can be higher if the conveying distance

is short and the conveying line pressure drop is high.固体负荷率，或相密度（注：固气比、混合比，以下叫混合比），是一种有用的参数，利于更直观看待流动模式。它是物料质量流量与气体质量流量的比值，是一个无量纲量。稀相一般最大到15 ，如果输送距离短和输送压降高，混合比可以更高。

For moving bed flows, solids loading ratios of well over 100 can be achieved

if materials are conveyed with pressure gradients of the order of 10 lbf/in2 per 100

foot of horizontal pipeline. For plug type flows the use of solids loading ratio is not

so appropriate, for as the materials have to be very permeable, maximum values are

only of the order of about 30. Despite the low value of solids loading ratio,

materials can be reliably conveyed at velocities of 600 ft/min and below in plug

type flow.移动床流动中如果被输送物料在水平管道中的压力梯度达到每100英尺有10 lbf/in2（注：相当于每100米223kPa），其混合比可以远大于100。栓流使用混合比不是太合适，因为物料必须有很好的透气性，最高值只有约30 。尽管混合比低， 物料可以600英尺/分钟（3米/秒）或更低速度可靠的流动。

2 SYSTEM TYPES系统类型

A wide range of pneumatic conveying systems are available, and they are all generally

suitable for the conveying of dry bulk particulate materials. The majority of

systems are conventional, continuously operating, open systems, in a fixed location.

To suit the material being conveyed, or the process, however, innovatory,

batch operating and closed systems are commonly used. Many of these systems

can be either positive or negative pressure in operation, or a combination of the

two. In this review some of the more common systems are presented.各种各样的气力输送系统都有效，并普遍适合输送干的散装物料。大多数系统都是常规的，连续运行，开放系统，处在一个固定的位置上。 以适应物料运送或处理，或这个过程中，但是，批次输送和封闭的系统被经常用到。这些系统可以是正压或负压的，或者正-负压的。在这次综述中介绍一些较常见的系统。

The problem of system selection is illustrated in Figure 1.1. This shows the

combinations that are possible for conventional pneumatic conveying systems with

a single air source. Only system types are presented in detail, with positive

pressure, vacuum, and combined positive and negative pressure systems

considered, in relation to both open and closed systems.图1.1阐明了系统的选择问题，描述常规的，具有单一的空气源的气力输送系统可能的组合，详细介绍了系统类型，包括正压，真空，正-负系统，以及相关的开放和封闭系统。

With such a wide range and choice of system types, a useful starting point is

to consider the alternatives in pair groupings:如此范围广泛系统类型，如何进行选择，一个有用的出发点是从两个备选方案中进行选择：

□Open and closed systems Open systems are the norm for pneumatic

conveying, particularly when conveying with air. Closed systems would

only be employed for very specific circumstances, such as with highly

toxic and potentially explosive materials.

□开放与封闭系统 开放式系统是通常的选择，特别是当使用空气进行输送时。只有在特殊环境下，如输送高度有毒和具有潜在爆炸性的物料时，才采用封闭的系统。

□Positive pressure and negative pressure systems Materials can be

sucked as well as blown and so either pressure or vacuum can be employed

for pneumatic conveying. This is often a matter of company or personal

preference.

□正压与负压系统 物料可以采用负压吸送，也可采用正压吹送，如何选择通常是公司或个人的偏好。

□Fixed and mobile systems The majority of pneumatic conveying systems

are in fixed locations and so this is not identified as a particular case.

A variety of mobile systems are available for specific duties.

□固定和可移动系统 大多数的气力输送系统都放在固定位置，这并不意味着是一定的。 各种移动系统，可用于特定的职责。

Figure 1.1 Diagram to illustrate the wide range of conveying systems available for

conventional systems operating with a single air source.具有单一空气源输送系统的各种类型

□High and low pressure systems In pneumatic conveying, high pressure

typically means any pressure above about 15 lbf/in2 gauge. For systems

delivering materials to reception points at atmospheric pressure, 100

lbf/in gauge is typically the upper limit, due to the problems of air expansion.

Very much higher pressures (typically 300 to 400 lbf/in2) can be employed

if delivering materials to reception points maintained at pressure,

such as chemical reactors and fluidized bed combustion systems.

□高压和低压系统 气力输送中的高压通常是指高约15 lbf/in2（注：103kPa）的压力。系统受料点的为一个大气压，最大一般不超过100 lbf/in2（注：690kPa）为了保持受料点的压力，可采用非常高的压力（通常为300至400 lbf/in2 注：2.06至2.76Mpa）来输送物料，如化学反应器和流化床燃烧系统。

□Conventional and innovatory systems Conventional systems are

those in which the material is simply fed into a pipeline and either blown

or sucked, and so this is not identified as a particular case since this is the

norm. Innovatory systems are those in which the material to be conveyed

is conditioned in some way, either at the feed point or along the length of

the pipeline, generally in order to convey the material at low velocity and

hence in dense phase, if the material has no natural capability for low velocity

conveying.

□常规与创新系统 常规系统将物料喂入管道，然后或吹送或吸送，这是通常做法。创新系统是将没有低速输送可能的物料，在喂料点及整个管道中，以低速密相的方式输送。

□Batch and continuously operating systems Both of these types of

conveying are common in industry.

□批次与连续输送系统 这两种形式的输送在工业中都很常见。

□Single and multiple systems The majority of conveying systems are

single units. It is possible, however, to combine units for certain duties.

□单个或多个系统 大多数输送系统都是独立单元。但也可能为了特定目的，将多个系统组合起来。

□Dilute and dense phase systems Dilute and dense phase conveying do

not relate to any particular type of system. Any bulk particulate material

can be conveyed in dilute phase. It is primarily the properties of the material

that determine whether the material can be conveyed in dense phase,

particularly in conventional conveying systems.

□稀相与密相系统 稀相和密相输送并不和任何特定类型的系统有什么关联。任何散料都可以稀相输送。但物料的物性决定了物料是否可以密相输送，特别是在传统的输送系统中。

□Pipeline and channel flow systems In the vast majority of pneumatic

conveying systems the material is conveyed through pipelines. Fluidized

motion conveying systems generally employ channels having a porous

base, through which air is introduced, and they are very limited with regard

to vertical conveying.

□管道与渠道流系统 绝大多数的气力输送系统中的物料是通过管道输送的。流化床输送系统通常使用多孔板来引入空气进行输送，它们局限于垂直的输送。

3 CLOSED SYSTEMS封闭系统

For certain conveying duties it is necessary to convey the material in a controlled

environment. If a dust cloud of the material is potentially explosive, nitrogen or

some other gas can be used to convey the material. In an open system such

environmental control can be very expensive, but in a closed system the gas can be

re-circulated and so the operating costs, in terms of inert gas, are significantly reduced.某些物料的输送要在一个可控环境中进行。氮气或其他一些惰性气体用来输送具有爆炸性粉尘的物料，对一个开放的系统，环境控制就会非常昂贵，但在一个封闭的系统中，气体循环利用，所以生产惰性气体方面的运营成本，大大减少。

If the material to be handled is toxic or radioactive, it may be possible to use

air for conveying, but very strict control would have to be maintained. A closed

system would be essential in this case. Continuous conveying systems are probably

the easiest to arrange in the form of a closed loop. A typical system is shown in

Figure 1.2.如果要处理有毒或放射性的物料，有可能使用空气输送，但要有非常严格的管制，封闭系统在这种情况下可起到非常重要的作用。闭路循环中，连续输送系统可能是最简单形式。Figure 1.2显示了一个典型的封闭系统。

Figure 1.2 A closed loop pneumatic conveying system.闭路循环系统

A null point needs to be established in the system where the pressure is effectively

atmospheric and provision for make up of conveying gas can be established

there. If this is positioned after the blower the conveying system can operate

entirely under vacuum. If the null point is located before the blower it will operate

as a positive pressure system.系统中存在一个压力为大气压的零点，输送空气从零点补充进系统。如果零点在风机后面，那么。如果零点位于风机前，那么输送系统为正压系统。

A back-up filter would always be recommended, because positive displacement

blowers and compressors are very vulnerable to damage by dust. This is

simply a precaution against an element in the filter unit failing. There will generally

be an increase in temperature across an air mover and so in a closed loop system

it may be necessary to include a heat exchanger, otherwise there could be a

gradual build up in temperature. The heat exchanger can be placed either before or

after the air mover, depending upon the material being conveyed.因为容积式鼓风机和压缩机非常容易因为灰尘受到损害。为了防范过滤单元失效，建议需有后备过滤器。因为空气加压后温度会上升，在封闭系统中必须有热交换器，否则温度会逐渐上升。换热器也可以放在空气加压前或之后，这取决于物料的输送方式。

4 OPEN SYSTEMS开放系统

Where strict environmental control is not necessary an open system is generally

preferred, since the capital cost of the plant will be less, the operational complexity

will be reduced, and a much wider range of systems will be available. Most pneumatic

conveying systems can ensure totally enclosed material conveying, and so

with suitable gas-solid separation and venting, the vast majority of materials can

be handled quite safely in an open system. Many potentially combustible materials

are conveyed in open systems by incorporating necessary safety features.如果没有严格的环境控制要求，一般首选开放的系统。工厂的投资减少，系统更简单，有更多种类的系统可供选择。大多数气力输送系统能够确保物料完全密闭的输送，配合合适的气固分离和通风系统，绝大多数的物料通过开放的系统安全输送，许多潜在的可燃物料配以必要的安全措施后也可采用开放的系统。

4.1 Positive Pressure Systems正压系统

Although positive pressure conveying systems discharging to a reception point at

atmospheric pressure are probably the most common of all pneumatic conveying

systems, the feeding of a material into a pipeline in which there is air at a positive

pressure does present a number of problems. A wide range of material feeding

devices, however, are available that can be used with this type of system, from

verturis and rotary valves to screws and blow tanks, and these are considered in

detail in Chapter 2. A typical low positive pressure pneumatic conveying system is

shown in Figure 1.3.虽然正压输送系统中受料点通常都是大气压，但把如何物料喂入有正压的管道中是个问题。有各种各样的喂料设备可用于这种类型的系统，在第2章中将详细介绍verturis、旋转阀、螺旋输送机和仓泵等喂料装置。图1.3显示了一个典型的低正压气力输送系统。

With the use of diverter valves, multiple delivery to a number of reception

points can be arranged very easily with positive pressure systems. Although multiple

point feeding into a common line can also be arranged, care must be taken,

particularly in the case of rotary valve feeding of the pipeline, since air leakage

through a number of such valves can be quite significant in relation to the total air

requirements for conveying.正压系统中可以使用换向阀将物料输送到多个料仓。虽然也多点进料到一条管线，但必须引起注意的是，特别是旋转阀喂料进管道，多个喂料装置的漏风量要计入总的输送风量中。

4.2 Negative Pressure (Vacuum) Systems负压（真空）系统

Negative pressure systems are commonly used for drawing materials from multiple

sources to a single point. There is little or no pressure difference across the

feeding device and so multiple point feeding into a common line presents few

problems. As a result the rotary valve and screw can also be a much cheaper item

for feeding a pipeline in a negative pressure system than in a positive pressure

system. The filtration plant, however, has to be much larger as a higher volume of

air has to be filtered under vacuum conditions. Particular care, therefore, must be

taken when specifying these particular components. A typical system is shown in

Figure 1.4.负压系统通常用于从多点到一点的输送。喂料设备很少或完全没有压力损失，因此从多点喂料进一条管道没有太大问题。也因此对旋转阀和螺旋机耐压的要求在负压系统中比正压系统要低。过滤装置，然而，真空条件下过滤设备要处理更大的空气量。因此在定这些设备的时候要特别引起注意。图1.4显示一个典型的负压系统。

Figure 1.3 A typical positive pressure conveying system.一个典型的正压输送系统

Figure 1.4 A typical negative pressure conveying system.一个典型的负压输送系统

Negative pressure systems are also widely used for drawing materials from

open storage, where the top surface of the material is accessible. This is achieved

by means of suction nozzles. Vacuum systems, therefore, can be used most effectively

for off-loading ships. They are also particularly useful for cleaning processes,

such as the removal of material spillages and dust accumulations. Another

application is in venting dust extraction hoods.l负压系统也广泛用从露天存放点吸取顶部的物料。通过吸嘴来实现这一点。真空系统，用来卸船是最有效的。他们还特别适用于清洁处理， 比如把泄漏的物料和堆积的灰尘吸走。另外也应用在通风除尘罩上。

If a very high vacuum is used for the conveying of a material, consideration

should be given to the stepping of the pipeline part way along its length. Air is

compressible and the rate of change of volume increases considerably with decrease

in pressure. If the pipeline is not stepped, extremely high values of conveying

air velocity can occur towards the end of the pipeline. The situation is the same

for very high pressure positive pressure conveying systems. These issues are considered

in detail in Chapters 5 and 9.如果用非常高的真空来输送物料，应当考虑沿管长扩管。可压缩的空气随压力的降低，其体积会膨胀，。如果不扩管，管道末端的空气流速会非常高。非常高压力的正压输送系统中也有同样的现象。这些问题会在第5章和第9章中详细论述。

Vacuum systems have the particular advantage that all gas leakage is inward,

so that the injection of dust into the atmosphere is virtually eliminated. This is

particularly important for the handling of toxic and explosive materials, or any

material where environmental considerations have to be taken into account. It is not

always necessary to employ a closed system with these materials, therefore,

provided that adequate safety measures are taken, particularly with regard to

exhaust venting.真空系统特别的优势在于，所有气体是向内泄漏的。 这样，不太会有粉尘泄漏到大气中去。在处理有毒和爆炸物料，或必须考虑对环境影响的任何物料时，这一点尤其重要。在这种情况下，可以用负压系统取代封闭系统，而不用考虑特别的通风除尘措施。

As a result of the conveying air being drawn through the air mover, it is essential

that the exhauster should be protected from the possibility of the failure of

one or more of the filter elements in the gas-solids separation system. This can be

achieved by incorporating a back-up filter, as shown in Figure 1.2 for the closed

loop system. A negative pressure conveying system operating with a vacuum nozzle

is shown in Figure 1.5.为了保护处在输送末端的空气动力机械，必须有可靠的气-固分离系统。为防止过滤器失效，有时会有备用的过滤器。图1.2所示的封闭闭环系统中有一个备用的过滤器。图1.5所示为一个有真空吸嘴的负压输送系统。

Figure 1.5 Vacuum conveying from open storage.从露天存储点吸料的负压系统

4.3 Combined Negative and Positive Pressure Systems负压-正压组合系统

Protection has to be provided for the exhauster/blower from the possible ingress of

material, as with negative pressure and closed loop systems. It should be noted

that the available power for the system has to be shared between the two sections,

and that the pipelines for the two parts of the system have to be carefully sized to

take account of different operating pressures.在负压和闭环系统中，要防止物料可能进入排风机/鼓风机而造成损害。应当指出，系统同时为负压段和正压段提供动力，而且系统中的两个部分必须认真考虑到不同的工作压力。

Some air movers, such as positive displacement blowers, operate on a given

pressure ratio, and this will mean that the machine will not be capable of operating

over the same pressure range with the combined duty as compared with their individual

operation. This will mean that the system capability is limited in terms of

both tonnage and distance. Although there is only one air mover, two filter units

will be required. A typical system is shown in Figure 1.6.一些空气动力机械，如容积式鼓风机，以一个特定的压力比率工作，这将意味着，和该机器执行单一任务相比，在组合系统它不能提供同样的压力。也就是说，组合系统的输送量和输送距离都受到限制。虽然只有一个空气动力，但有两个过滤器单元。一个典型的系统如图1.6所示 。

Figure 1.6 Combined negative and positive pressure system.负压-正压组合系统

4.4 Dual Vacuum and Positive Pressure Systems双真空正压系统

If the conveying potential of a system requiring the vacuum pick-up of a material

needs to be improved beyond that capable with a combined negative and positive

pressure system, whether in terms of conveying distance or material conveying

rate, then a dual system should be considered. In this combination the two conveying

elements are separated and two air movers are provided.t如果有一个需要真空上料的系统，而负压-正压组合系统又达不到其输送量或输送距离，这时可以考虑采用双真空正压系统。双真空正压系统的真空上料和正压输送两部分是分开的，并由两个空气动力机械分别提供输送动力。

A typical system is shown in Figure 1.7. It should be noted that as there are

two separate systems, two gas-solid separation devices also have to be provided.

Filters and valves have been omitted from the sketch of the system for clarity.一个典型的系统如图1.7所示。应当指出的是，因为有两个独立的系统，两个气固分离装置也必须提供。 简图中没有画出过滤器和阀门。As two air movers are provided this means that the most suitable exhauster

can be dedicated to the vacuum system and the most appropriate positive pressure

system can be used for the onward transfer of material. If the vacuum off-loading

section is only a short distance, it is possible that the material could be conveyed in

dense phase over the entire conveying distance. It is simply a matter of pressure

gradient for materials that have good air retention properties, as considered in

Chapters 4 and 7.真空和正压部分各有一个空气动力机械，这样可以选择最合适的排风机和鼓风机来适配系统能力。可以同时进行近距离的真空上料，和远距离的密相输送。

The system shown in Figure 1.7 is typical of a ship off-loading system. With

a high vacuum exhauster a material such as cement could be off-loaded at a rate of

about 900 to 1000 ton/h through a single pipeline. Twin vessels on the quayside

would allow continuous conveying to shore based reception vessels, which could

be some 2000 ft distant if a high pressure compressor was to be used. For the onward

conveying two pipelines would probably need to be used to achieve the 1000

ton/h.图1.7是典型的船舶卸货系统。配置高真空排气机械的水泥的卸船装置，只用一个管道可达约900至1000吨/小时的卸船量。码头上双仓泵卸船机可连续输送散料到岸上的料仓，使用高压压缩机输送距离可达到约2000英尺（注：大约600m）。必要时采用两条管线输送，可实现1000 吨/小时的卸船量。

Figure 1.7 Typical dual vacuum and positive pressure system.典型的双真空正压系统

5 BATCH CONVEYING批次输送

The systems considered so far have all been capable of continuous conveying. In

many processes, however, it may be more convenient to convey one batch at a

time. An additional classification of conveying systems, as indicated on Figure

1.1, is based on mode of operation. Conveying can either be carried out on a continuous

basis or in a sequence of isolated batches.前面所提到的系统都是连续输送的。但在很多场合，需要批次输送。额外的分类输送系统，如在图1.1所示的输送系统种类中，有可以连续进行输送的系统，也可以一批批的输送的系统。

Although a batch conveying system may be chosen for a specific process

need, the mode of conveying is, to a large extent dictated by the choice of pipeline

feeding device. The majority of batch conveying systems are based on blow tanks,

and blow tanks are chosen either because of their high pressure conveying capability,

or because of the abrasive nature of the material.虽然可能是为了特定的目的选用了批次输送系统，但这种输送模式，在很大程度上取决于喂料装置的选择。大多数的批次输送系统是基于发送罐的，选择发送罐，有可能是因为它能高压输送，也可能是因为输送的物料具有磨削性。

Two types of system are considered. In one, the batch size is relatively large,

and the material is fed into the pipeline gradually, and so can be considered as a

semi continuous system. In the other, the material is fed into the pipeline as a single

plug. Particular features of blow tanks, as material feeding devices, are considered

in Chapter 2. In this chapter the emphasis is on types of conveying system.批次输送系统有两种类型。一种是，批量相对较大， 物料逐步的喂入管道，可视为间歇系统。另一种是，物料以一个料栓的形式喂入管道。在第2章中讲述发送罐的具体特点。本章的重点是各类输送系统。

5.1 Semi Continuous Systems间歇系统

It should be noted that when batches of material are fed into the pipeline gradually,

there is essentially no difference in the nature of the gas-solids flow in the pipeline

with respect to the mode of conveying through the pipeline. This is certainly the

case during the steady state portion or the conveying cycle, regardless of the value

of solids loading ratio.应当指出的是，当批次的物料被逐步输入管道，其气-固流动性质与是哪种管道气力输送模式无关。不管混合比是多少，在稳定输送期间或在输送周期中都是这样。（注：我的理解是，这段话的意思是，不管是连续还是批次输送，不管混合比多少，物料在管道中流动都遵守气-固两相流的规律。）

The blow tanks used vary in size from a few cubic feet, to 1000 ft3 or more,

generally depending upon the material flow rate required as well as a need to

maintain a reasonable frequency of blow tank cycling. The material can be conveyed

in dilute or dense phase, depending upon the capability of the material, the

pressure available and the conveying distance, as with continuously operating systems.发送罐的容积大小从几立方英尺，到一千立方英尺（注：约28m3）或更大，发送罐的大小通常取决于物料的输送量需要以及合理的循环次数（注：一般认为，单个发送罐合理的循环次数为每小时8~15次）。和连续输送系统一样，物料既可以稀相也可以密相输送，这取决于物性，系统允许的输送压力和物料输送距离。与不断操作系统。

With a single blow tank it is not possible to utilize the pipeline while the

blow tank is being filled with material or when the system is being pressurized.

Since batch conveying is discontinuous, steady state values of material flow rate,

achieved during conveying, have to be higher than those for continuously operating

systems in order to achieve the same time averaged mean value of material

flow rate. This means that air requirements and pipeline sizes have to be based on

the maximum, or steady state, conveying rate. The intermittent nature of the conveying

cycle is illustrated in Figure 1.8. 发送罐进料，或该系统正在加压时，是不能进行输送的。 由于批次输送系统不能连续输送，为了达到和连续输送系统一样的输送量，其出力必须高于连续输送系统。这意味着，空气流量和管道大小必须基于最大的，或稳定输送状态时的输送量。图1.8描述的是间歇性的输送周期。

In comparison with a continuously operating system, therefore, the batch

operating system would appear to be at a disadvantage. Blow tank systems, however,

can operate at very much higher pressures to compensate, and they can be

configured to operate continuously, as will be considered in the next chapter on

pipeline feeding systems.和连续输送系统相比，批次输送系统似乎不占优势。但发送罐可以运行在非常高的压力下，，并可以设计成连续工作，这将在下一章管道喂料系统中讲到。

Figure 1.8 Sketch showing the transient nature of batch conveying.批次输送周期示意图

It should be emphasized that blow tanks can be operated at low as well as

high pressure, depending upon the system needs. If a material needs to be fed into a

chemical reactor or a boiler plant that is maintained at a pressure of 400 Ibf/in , for

example, the blow tank can be designed to operate at 410 Ibf/in2 for the duty. When

delivering material to a reception point at atmospheric pressure, however, air

supply pressures greater than about 100 Ibf/in" are rarely used. This is mainly

because of the problem of air expansion and the need for a stepped pipeline to

prevent excessively high values of conveying air velocity.应该强调指出，发送罐可以工作在低压或者高压下，这取决于系统的需求。譬如，如果物料需要被送进化学反应器或压力有400 Ibf/in（注：约2.76Mpa）的锅炉中，发送罐可以设计成在410 Ibf/in2下工作。当受料点的压力是大气压，很少用到高于100 Ibf/in（注：约0.69Mpa）的输送压力。这主要是因为管道要扩管以避免由于空气的膨胀而导致输送气速过大。

A typical batch conveying system based on a single blow tank is illustrated

in Figure 1.9.图1.9描述了一个典型的单发送罐批次输送系统。

Figure 1.9 Typical single blow tank conveying system.典型单发送罐批次输送系统.

5.2 Single Plug Systems柱塞式系统/单栓流输送系统

In the single plug conveying system the material is effectively extruded into the

pipeline as a single plug, although the material is generally well aerated. It is typically

about 30 ft long. This plug is then blown through the pipeline as a coherent

plug. A certain amount of material will tail off the end of the plug as it is conveyed,

but the front of the plug will sweep up material deposited in the pipeline by

the previous plug. Blow tanks are generally used as the feeding device and a typical

single plug conveying system is shown in Figure 1.10.柱塞式系统中，物料实际上是被挤压进管道形成一个料栓，虽然物料通常有良好的透气性。典型的料栓长约30英尺（注：约9m）。物料以一个紧密的料栓的形态沿管道移动。输送的时候，一定数量的物料从料栓尾部脱离， 但料栓头部会铲起从上一个料栓脱离的物料。发送罐常用于柱塞式系统的喂料，图1.10 所示为一个典型的柱塞式输送系统。

The air pressure has to overcome the frictional resistance of the plug of material

in the pipeline. As a result blow tank sizes are rarely larger than 150 ft3,

unless very large diameter pipelines are employed. In terms of system design, a

cycling frequency is selected to achieve the required material flow rate, which

determines the batch size. The pipe diameter is then selected such that the frictional

resistance of the plug results in a reasonable air supply pressure to propel the

plug at the given velocity.空气压力要克服料栓在管道中的摩擦阻力，因此发送罐很少大于150立方英尺（注：约4m3）， 除非采用非常大的管道。在系统设计时，根据物料输送量和选定的循环次数， 确定了发送罐的容积。然后根据系统提供的空气压力和一定速度下料栓的摩擦阻力来确定管径。

The material will be conveyed at a low velocity, in what may be regarded

as dense phase, but solids loading ratios have no significance here, and steady state

conveying, as depicted on Figure 1.8, does not apply either. Single plug systems

are capable of conveying a wide range of materials, and generally at much lower

velocities than can be achieved in continuously operating systems. Many coarse,

granular materials are either friable or abrasive and can only be conveyed in dilute

phase with conventional conveying systems, and so single plug systems can represent

a viable alternative, although it would always be recommended that tests be

carried out to confirm this.物料以低速输送，可视为密相输送，但混合比在这里没有任何意义，图1.8所描述的稳态输送和这里不一样。大多数的物料都可以柱塞输送，其输送速度通常比连续输送要低的多。许多粗颗粒物料或者易碎的、有磨削性的物料，在通常的输送系统中只能以稀相输送，柱塞式系统可以成为另一个选择，但必须靠测试来确认是否可行。

Figure 1.10 Sketch of a typical single plug conveying system.一个典型的柱塞式输送系统示意图

Material discharge often represents a problem with this type of system. Although

the plugs of material are conveyed at a relatively low velocity, once they

are discharged from the pipeline the high pressure air released behind the plug can

cause severe erosion of the pipeline on venting.这种类型的系统的卸料往往是一个问题，。虽然料栓以相对的低速输送，一旦料栓进入受料仓，料栓后面的高压气体释放会造成对管道出料口的严重侵蚀。

6 INNOVATORY SYSTEMS创新系统

Unless the material to be conveyed has natural bulk characteristics such as good

air retention or permeability, it is unlikely that it will be possible to convey the

material at low velocity, and in dense phase, in a conventional continuous or semi

continuous conveying system such as those described above. Even if a high pressure

system is employed it is unlikely that such a material will convey in dense

phase, unless the pipeline is relatively short. Dense phase conveying is not synonymous

with high pressure, it is material property dependent.对前面所说的传统的连续或间歇输送系统而言，除非物料具有如良好存气性或透气性等自然的散料特性，否则不太可能以密相低速输送。除非输送距离相对较短，即使采用高压系统，密相输送的可能性也不大。密相输送不等于高压力，它取决于输送物料的物性。

For materials that are either abrasive or friable, alternatives to conventional

systems may have to be considered, particularly if the materials are not capable of

being conveyed in a dense phase mode, and hence at low velocity. For friable

materials considerable particle degradation can occur in high velocity suspension

flow, and erosion of bends in the pipeline and other plant surfaces subject to

particle impact will occur if an abrasive material is conveyed in dilute phase

suspension flow.对有磨削性或易破碎的物料，特别是在传统的输送系统无法以低速密相输送时，有必要考虑新型的输送系统。易破碎的物料以悬浮流高速输送会降级，以稀相悬浮流输送磨削性物料，管道弯头或其他设备表面会受到磨损。

For a material that is only slightly hygroscopic, successful conveying may be

achieved if the material is conveyed in dense phase, without the need for air drying

equipment, since air quantities required for conveying can be significantly lower

than those for dilute phase. For food products, that may be subject to a loss in flavor

in contact with air, dense phase conveying might be recommended. If any such

material is not capable of being conveyed in dense phase in conventional systems,

however, alternative systems will also have to be considered.具有轻微吸湿性的物料，可以密相形式进行输送，而不需要空气干燥设备。因为密相输送用气量比稀相要低得多。食品和空气接触会香味流失，建议采用密相输送。如果这类物料不能用常规的密相系统来输送， 要考虑其它系统来替代。

With a need to convey many materials at low velocity, much development

work has been undertaken since the late 1960's to find means of conveying

materials with no natural dense phase conveying capability at low velocity. The

innovatory systems produced as a result of these developments have centered

around some form of conditioning of the conveyed material, either at the feed point

into the pipeline or along the length of the pipeline. Since the modifications are

essentially based on the pipeline, types of conveying system have not changed

significantly.因为有很多物料需要以低速输送，从20世纪60年代末开始的有关输送一些本来不具备密相低速输送条件的物料方面的研究取得了很多的成果，。创新系统的关注点是喂料点及沿整个管长的物料输送工况的调节。实际上是基于输送管线的改进，而输送系统型式并没明显的变化。

6.1 Plug Forming Systems脉冲栓流输送系统

The pulse phase system was developed in the late 1960's. A typical pulse phase

system is shown in Figure 1.11. An air knife, positioned at the start of the pipeline,

intermittently pulses air into the pipeline to divide the discharging material into

discrete short plugs. Blow tanks are commonly used for the feeding of materials in

this type of system also.脉冲输送系统是从20世纪60年代末发展起来的。图1.11是一个典型的脉冲输送系统。脉冲气从管道起始段的气刀进入管道，将管道内物料分割成不连续的短栓。这种类型的输送系统通常用发送罐来喂料。

No further conditioning of the material occurs along the length of the pipeline.

The pulse phase system was initially proposed as a solution to the problem of

conveying cohesive bulk solids, but subsequent developments have shown that a

wider range of materials can be conveyed successfully.沿输送管道没有其它的调节手段。 脉冲系统最初是为了解决粘性物料的输送难题，但随后的发展表明， 有更广泛的物料可采用脉冲系统来输送。

Figure 1.11 Pulse phase conveying system.脉冲栓流输送系统

6.2 By-Pass Systems旁路系统

.The most common by-pass systems employ a small pipe running inside the conveying

line, having fixed ports, or flutes, at regular intervals along its length. This

inner pipe is not supplied with an external source of air, but air within the conveying

line can enter freely through the regular openings provided. In an alternative

design the by-pass pipe runs externally to the pipeline and is interconnected at

regular intervals. By this means pipeline bends can also be conveniently incorporated.最常见的旁路系统是在输送管道内部有一根小管，内管上沿管长有规律地开有固定缺口或沟槽。这个内管不通入外来的空气，但输送管内的空气可以自由地经缺口进出。这种设计取代了输送管道外部的，以一定间隔与输送管道相通的旁路系统。管道弯头也可以用这种方式连接。

If the material is impermeable the air will be forced to flow through the bypass

pipe if the pipeline blocks. Because the by-pass pipe has a much smaller

diameter than the pipeline, the air will be forced back into the pipeline through the

next and subsequent flutes because of the extremely high pressure gradient, and

this will effect a break up of the plug of material causing the blockage.如果管道被料栓堵住，不能透过物料的空气会被迫从旁路管道走。由于旁通管比输送管的直径要小很多，在非常高的阻力下，空气会被迫从相邻的下一个缺口重新进入输送管内，这样就使得堵住输送管的料栓被击溃。

6.3 Air Injection Systems空气喷射系统

A number of systems have been developed that inject air into the pipeline at regular

points along its length, as illustrated in Figure 1.12.一些系统沿管长有规律的通入空气，如图1.12所示 。

Figure 1.12 Various plug control systems/各种控栓（破栓）系统

While by-pass pipe systems artificially create permeability in the bulk material,

air injection will help to maintain a degree of air retention within the material.

Continuous injection of air into the pipeline, however, does mean that conveying

air velocities towards the end of the pipeline will be much higher as a result.旁路管道系统人为的增加了物料的透气性， 喷射入空气将有助于在物料内部保持一定程度的空气。连续喷射空气进入管道，并不意味着管道末端的气速变的很高。

In some systems sensors are positioned between the parallel air line and the

conveying pipeline and air is only injected when required. If a change in pressure

difference between the two lines is detected, which would indicate that a plug is

forming in the conveying pipeline, air is injected close to that point in order to

break up the plug and so facilitate its movement. Various plug control systems,

including both by-pass pipe and air addition methods are shown in Figure 1.12.在某些系统里，在平行的空气管道和输送管道间设有传感器，只是在必要时才注入空气。如果监测两条管线间的压差发生变化，这表明输送管道中的料栓在形成中，在此处附近喷射入空气以击溃料栓，有助于物料输送。图1.12中显示了包括旁路管和补气式的各种控栓系统。

Many of the innovatory systems are capable of being stopped and re-started

during operation. With most conventional systems this is not possible, and would

result in considerable inconvenience in clearing pipelines if a blockage should

occur as a consequence. Since they are capable of conveying materials in dense

phase, operating costs for power are likely to be lower than those for a conventional

dilute phase system. Capital costs for the innovatory systems are likely to be higher,

however, and so an economic assessment of the alternative systems would need to

be carried out.许多创新系统能够在工作中停止输送和重新起动。而大多数传统系统无法做到这一点，可能导致管道堵塞而增加清空管道的麻烦。旁路系统能以密相来输送物料，运营的电力成本很可能会低于常规稀相系统。但创新系统的固定投资很可能会更高些，因而需对两个系统进行经济评估。

7 FLUIDIZED MOTION CONVEYING SYSTEMS流化床运动输送系统（注：从下文上看应是空气斜槽输送）

The categorizing of fluidized motion conveying systems always represents a problem.

They are not generally recognized as pneumatic conveying systems because

they only use very low positive pressure air, the material does not flow through a

pipeline, and they have been limited to flow down gradual inclines only. They are,

however, clearly not in the mechanical conveying group of conveyors. Until recent

years their application was relatively limited because the main driving force was

gravity, and so they would only operate on a downward incline, although at a very

low angle.有关流化床运动输送系统的分类始终是一个问题。 它们不是普遍公认的气力输送系统，因为它们只能使用很低压力的空气，物料也不是通过管道来流动，而且他们局限于向下倾斜流动。但很明显它们也不属于机械输送。直到最近几年它们的应用是相对有限，因为主要的动力是重力，所以只能以一个很小的角度向下倾斜输送。

The material is conveyed along a channel that has a continuous porous base.

Air enters the material through the porous base and fluidizes the material. In this

condition the material will behave like a liquid and flow down an inclined channel.

The channel is generally closed to keep the system dust tight.物料沿有多孔底板的槽体输送。空气通过多孔板进入，对物料进行流化。在此工况下，物料将表现得象液体一样并沿向下倾斜的槽体流动。槽体通常是封闭的以防粉尘外漏。

In early systems the channel ran with the material only partly filling the

channel. The fluidizing air escaped into the space above the flowing material and

was ducted to a filtration plant. In a recent development the channel operates full

of material and is capable of running horizontally. It is possible that the channel

could be made to operate at a higher pressure and so be able to convey material up

an incline. As the channel can run full, negative pressure operation is another possibility.早期的系统中，物料只能部分充满槽体。流化气透过物料进入上层空间并被导入过滤装置。近期发展到物料充满整个槽体，能够进行水平输送。使槽体工作在一个较高压力下，并可能具备向上倾斜输送的能力。当槽体充满物料时，负压输送也是可行的。

7.1 Air-Assisted Gravity Conveyors/空气辅助重力输送机

In situations where the flow of a material can be downwards, the air-assisted gravity

conveyor has a number of advantages over pneumatic conveying systems.

Plant capital costs can be much lower, operating costs are significantly lower, and

a wide range of materials can be conveyed at a very low velocity.在物料能向下流动的情况下，空气辅助重力输送相对气力输送系统，有很多的优势。 投资低得多，经营成本大大降低，种类众多的物料能以非常低的速度进行输送。

Air-assisted gravity conveyors can be regarded as an extreme form of dense

phase conveying. The conveyor consists essentially of a channel, divided longitudinally

by means of a suitable porous membrane on which the material is conveyed.

Such a system is shown in Figure 1.13.空气辅助重力输送可以被看作是一种超密相输送系统。输送装置主体是一个由多孔板隔开的槽体，物料顺着多孔板表面被输送。 这样一个系统如图1.13所示。

Figure 1.13 Air-assisted gravity conveyor.空气辅助重力输送

If a small quantity of low pressure air is fed through the membrane, the inter-

particle and particle/wall contact forces will be reduced and the material will

behave like a liquid. If a slight slope is imparted to the conveyor, the material will

flow. These conveyors are often referred to as 'air slides'. They have been in use

for over 100 years and are still widely used today for materials such as alumina,

cement and fly ash.如果少量的低压空气通过透气层输入，粒子间和粒子与壁的摩擦力将降低，该物料表现的像液体一样。稍有坡度，材料就会流动起来。这些输送装置经常被叫做“空气斜槽”。他们一直被使用了一百多年，如今仍被广泛用于输送，如氧化铝、 水泥和粉煤灰等物料。

Air-gravity conveyors, ranging in width from 4 in to 2 ft, can convey materials

over distances of up to 300 ft, and are suitable for material flow rates of up to

about 3000 ton/h. In general, most materials in the mean particle size and density

ranges from 40 to 500 micron and 80 to 300 Ib/ft3 are the easiest to convey and

will flow very well down shallow slopes.空气辅助重力输送装置，宽度从2到4英尺不等，输送距离可达300英尺（注：约90m），输送量可达约3000吨/小时，平均粒径为40到500微米，密度为80至300 Ib/ft3（注：约1281~4805kg/m3）的大部分物料并能很容易地沿小角度的下斜坡度被输送。

7.2 Full Channel Conveyors满槽输送装置

Hanrot [1] describes a pressurized horizontal conveying system developed by

Aluminum Pechiney to convey alumina. The alumina was conveyed from a single

supply point to more than one hundred outlets. Electrolysis pots on a modern aluminum

smelter were required to be filled and the distance from the silo to the furthest

outlet was approximately 600 ft. Air at a pressure of about I'A lbf/in2 gauge

is required. A conveying channel is employed, as with the air-assisted gravity conveyor,

but the channel runs full of material. The system is illustrated in Figure 1.14

and this shows the principle of operation.Hanrot [ 1 ]介绍了一种由力拓加铝开发的输送氧化铝的加压水平输送系统。氧化铝从一个供料点输送到超过100个受料点去。现代化铝冶炼厂，从料仓输送氧化铝到最远的电解罐，距离接近600 ft（注：约183m），输送压力约为1.5bf/in2（注：约10.3kPa）。采用空气辅助重力输送机进行输送，物料充满整个槽体。图1.14描述了该系统的工作原理。

Figure 1.14 Principle of potential fluidization ducts.流化床输送原理

Balancing columns are positioned on the conveying duct and are used for

de-dusting. This is not a continuously operating system in the application described.

It is a batch type system and its object is to meet the demands of the intermittent

filling of the pot hoppers. The system, however, is clearly capable of

continuous operation and of significant further development.输送导槽上设置有用于除尘的平衡塔，。在此应用示例中描述的不是一个连续工作系统。这是一个间歇填满料斗的批次输送系统。不过，该系统显然是有连续工作能力的，具有进一步发展的意义。

8 MOBILE SYSTEMS移动系统

All of the systems described so far have been essentially fixed systems. The only

real flexibility in any of the systems has been the capability of moving vacuum

nozzles in negative pressure systems. By the use of flexible hoses these can be

moved, and they find wide application in ship off-loading systems, and the clearing

of material from stockpiles or spillages. Many road sweeping vehicles employ

vacuum conveying for their operation.迄今为止所介绍的全部系统基本上都是固定式系统。所有系统中唯一具有真正灵活性的是负压系统中可移动的真空吸嘴，使用可移动的挠性软管，他们广泛应用于船舶卸货系统、清仓及收集洒落的物料。许多道路清扫车的作业采用的是真空输送。

Many bulk particulate materials are transported from one location to another

by road, rail and sea. Many materials, of course, are transported in a pre-packaged

form, or in bulk containers, and can be transported by road, rail, sea or air, in a

similar manner to any other commodity. Many transport systems, however, are

specifically designed for bulk particulate materials and have a capability of self

loading, self off-loading, or both. These are generally mobile versions of the above

static conveying systems, depending upon the application and duty.许多散装颗粒物料通过公路，铁路和海运来进行运输。和其它产品一样，许多物料是有包装的，或装在散装容器中。然而，许多运输系统是专为运送散装物料设计的，具有自行装载或自行卸货的功能，或两者兼而有之。这些都是不同于固定式输送系统的移动类型，用于特定的应用和职能。

8.1 Road Vehicles公路车辆

Road vehicles are widely used for the transport of a multitude of bulk particulate

materials, such as cement, flour, sugar and polyethylene. Road vehicles often have

their own positive displacement blower mounted behind the cab and so can offload

their materials independently of delivery depot facilities. The material containing

element on the truck can generally be tipped to facilitate discharge, which

can be via a rotary valve, or the container might double as a blow tank which can

be pressurized.公路车辆被广泛用于运输各种散装物料，如水泥，面粉，食糖和聚乙烯。道路车辆常常自带安装在驾驶室后的正压容积式风机，不需使用交货仓库设施来卸货。通常卡车上的物料可能通过一个旋转阀来卸料，或容器本身就是一个类似于发送罐的可加压容器。

8.2 Rail Vehicles铁路车辆

Rail cars or wagons generally rely on delivery depot facilities for off-loading. Because

of their length tilting is not an option and so multiple point off-loading is

often employed. They may be off-loaded by rotary valve, or the rail car may be

capable of being pressurized so that it can be off-loaded as a blow tank.火车车厢或货车一般依靠交货仓库设施卸下。因为不能在一定范围内倾斜，因此经常使用多点卸料。他们通过旋转阀卸料，或像发送罐一样被加压而卸料。

Whereas road vehicles are typically designed to operate with air at 15 Ibf/in2

gauge for this purpose, rail vehicles are generally designed to 30 Ibf/in2 and can

usually be off-loaded in about one hour. The base of the rail car is usually angled

at about five degrees in herringbone fashion around each discharge point and

fluidized to facilitate removal of as much material as possible.鉴于一般公路车辆设计的工作压力为15 Ibf/in2（注：约103kPa），铁路车辆一般工作压力为30 Ibf/in2（注：约206kPa），通常可在约一个小时卸完。铁路车辆每个卸料点处的底板通常呈约5度左右角度的人字状。通过流化尽可能的卸出物料。

8.3 Ships船舶

Large bulk carriers usually rely on port facilities for off-loading and these are generally

similar to that depicted in Figure 1.7. Intermediate bulk carriers, however,

often have on-board facilities for off-loading. Such vessels are often used for the

transfer of materials such as cement to storage depots at ports for local supply, or

to off-shore oil rigs.大型散货船通常依赖于港口设施来卸货，类似于图1.7 中所描述的系统。但中间散装船，往往靠船上的设施来卸货。这类船只通常用于把水泥等物料输送到港口的存储仓库，或送到近海石油钻井平台。

Materials are typically transferred from storage holds in the ship by a

combination of air-assisted gravity conveyors and vacuum conveying systems, into

twin blow tanks. High pressure air is supplied by on-board diesel driven

compressors and materials are conveyed to dock-side storage facilities through

flexible rubber hose, which solves the problems of both location and tidal

movements.物料通常是船上储仓由空气辅助重力输送与真空输送的组合系统提升进到双仓泵。高压空气是由船上的柴油驱动压缩机供给，物料通过橡胶软管输送到码头仓储设施，通过这种方式解决了由潮汐运动引起的距离变化难题。

9 MULTIPLE SYSTEMS/多重系统

Two multiple systems have already been considered. These were the combined

negative and positive pressure system, illustrated in Figure 1.6, and the dual vacuum

and positive pressure system, illustrated in Figure 1.7. A third possibility is

the staging of pneumatic conveying systems, which would be required for very

long distance conveying. Materials are currently conveyed over distances of 5000

ft in a single stage and flow rates of 40 ton/h over this distance are not unusual.前面已经讲到了两个多重系统。这就是，图1.6中描述的负压-正压组合系统 ，以及图1.7中描述的双真空正压系统。第三种是是非常长距离输送要用到的分段气力输送系统。目前物料单级输送，距离超过5000英尺（注：约1500m），输送量达到40吨/小时，并非罕见。

With much higher air supply pressures, conveying over longer distances is

possible, and with larger bore pipelines higher material flow rates can be achieved.

For very much longer distance conveying, however, staging will have to be employed.

A problem with using very high pressure air is that of the expansion of the

air and the need to step the pipeline to a larger bore part way along its length, but

this can be overcome to a large extent by discharging the material at the end of

each stage at a pressure of about 45 lbf/in2 rather than to atmospheric pressure.通过提高输送压力和加大管径，更远的距离，更大的输送量，也是可以实现的，但此时不得不采用分段气力输送。使用非常高的空气压力，由于空气的膨胀需要沿管程对管道进行扩管，每段末端的压力大约是45 lbf/in2（注：约310kPa），而不是一个大气压。

10 SYSTEM REQUIREMENTS系统要求

The uses, applications and requirements of pneumatic conveying systems are

many and varied. A number of system requirements were highlighted at various

points with regard to the systems. Some of the more common requirements of

systems can be identified and are detailed here for easy access and reference, since

these may feature prominently in the choice of a particular system.气力输送系统的使用，应用和要求是多种多样的。一些系统要求在系统的不同点被突出强调。一些较常见的系统要求在这里详细介绍以供参考，当然在特定系统的选择中有一些系统要求要被特别提出。

10.1 Multiple Pick-Up多点拾取

If multiple point feeding into a common line is required, a vacuum system would

generally be recommended. Although positive pressure systems could be used, air

leakage across feeding devices such as rotary valves represents a major problem.

The air leakage from a number of feed points would also result in a significant

energy loss. The air loss could be overcome by adding isolation valves to each

feed point, but this would add to the cost and complexity of the system.如果一根管道要有多点喂料，一般建议采用真空系统。虽然也可使用正压系统，但从喂料装置，比如旋转阀，产生的空气泄漏会成为一个大问题。从一些喂料点漏风引起的能量损失是个显著的数字。在每个喂料点增加隔离阀门可以减少漏风量，但会增加费用和系统的复杂性。

10.2 Multiple Delivery多点受料

Multiple delivery to a number of reception points can easily be arranged with positive

pressure systems. Diverter valves can be used most conveniently for this purpose.

Such a system was illustrated in Figure 1.3. This shows a separate filter unit

mounted on each reception hopper. If the situation allows, a common unit could be

used, but care would have to be taken with the specification and layout.正压输送系统很容易实现送到多个接收点。换向阀可用于最方便地实现这一目的。在图1.3中描述了这样的一个系统。在每个受料斗上设有一个单独的过滤器。如果情况允许，也可采用一个公用的过滤器，但要注意必须采取的规格和设备布置。

The problem with vacuum systems performing this function is equivalent to

the problem of using a positive pressure system for the multiple pick-up of

materials, which is one of multiple point air leakage. In this case, however, it is

ingress of air into the system. Any air leaking into a conveying system pipeline

along its length will by-pass the material feed point and this could result in the

conveying air velocity being too low to convey the material.用真空系统实现一对多的输送产生的问题，相当于用正压输送系统实现多对一的输送，都是存在多点漏风。但在这种情况下，对真空系统是空气漏进到系统内。任何空气从管道上泄漏进输送系统，相当喂料点增加了一路旁路，这可能导致（喂料点）输送空气流速过低。

10.3 Multiple Pick-Up and Delivery多点拾取，多点受料

The suck-blow, or combined vacuum and positive pressure system, illustrated in

Figure 1.6 is ideal for situations where both multiple pick-up and delivery is required.

The pressure drop available for conveying is rather limited with this type

of system and so if it is necessary to convey over a long distance, a dual system

would be more appropriate. In this the vacuum and positive pressure conveying

functions are separated and a high pressure system can be used to achieve the distant

conveying requirement, as shown in Figure 1.7.图1.6显示的吸-送，或负压-正压组合系统，适合于多对多的输送。 这种系统能提供的输送压力是相当有限的，所以对长距离的输送，一个双真空正压系统将更为合适。如图1.7所示的双真空正压系统中，真空和正压系统是相互独立的，因此能提供高的输送压力来达到远距离输送。

10.4 Multiple Material Handling多种物料搬运

If it is required to handle two or more materials with the one system, reference

should be made to the conveying characteristics for each material to be conveyed.

It is quite likely that the air requirements for the materials will differ to a large

extent, and that different flow rates will be achieved for each material, for identical

conveying conditions.如果在同一个系统中需要能输送两个或两个以上的物料，系统要达到每一种物料输送的要求。 很可能在相同输送条件下，每种物料输送所需空气量大不相同，而系统必须实现这种差异。

In this case it will be necessary to base the air requirements, to be specified

for the air mover, on the material requiring the highest conveying line inlet air

velocity. Consideration will then have to be given to a means of controlling the air

flow rate, to lower values, for the other materials, if this should be required. Alternatively

the same air flow rate can be used for each material but different pipeline

bores will have to be used to achieve the conveying air velocity values required.在这种情况下，有必要根据物料所需最大的输送空气入口流速来选定气源机械。有必要时，要考虑采用一种措施来控制空气流量以适应输送其它种类物流时较低的空气量要求。或者，采用同样的空气流量，不同（内径）的输送管道来输送各种材料。

Since it is likely that the flow rate of each material will be different, the

feeding device, or devices, will have to meet the needs of every material, in terms

of flow rate and control. The solutions will also differ between a system in which

there is a change of material to be conveyed, and a system in which different materials

are to be fed from one or a number of different supply hoppers.因为每种物料的输送量会有所不同，喂料设备要满足每种物料在流量方面的控制要求。一个系统中物料以不同输送量来输送，和一个系统中有多种物料从一个或多个不同供料斗中喂料，的解决方案是不同的。

10.5 Multiple Distance Conveying不同距离输送

If it is required to convey a material over a range of distances, such as a road

tanker supplying a number of different installations, or a pipeline supplying a

number of widely spaced reception points, consideration will again have to be

given to differing material flow rates and air requirements. It is possible for both

of these to change if there is a change in conveying distance, for whatever reason.如果物料需要输送不同距离，如槽车要提供给一些不同的设施，或管道输送到一些分布很远的受料点，必须再次考虑到不同的物料输送量和所需空气流量。不管什么原因下的输送距离的变化，都可以引起输送量和空气流量同时改变。

For a given air supply, in terms of delivery pressure and volumetric flow

rate, the material flow rate achieved will decrease with increase in conveying distance.

As a consequence the material feeding device will either need to be controlled

to meet the variation in conveying capability, or the feed rate will have to

be set to the lowest value for the longest distance.对于给定的空气供应，从提供的压力和空气体积流量来看，随输送距离的增加，输送量将减少。因而，喂料装置需要得到控制以满足不同输送能力，或喂料量将被设置为最长距离下的最小喂料量。

For materials capable of being conveyed in dense phase there is the added

problem of the possibility that the air flow rate will also need to be increased if

there is a significant change in conveying distance.材料能够以密相输送有增加问题的可能性，即如果输送距离显著变化，空气流量也将需要增加。（注：存疑。原文：For materials capable of being conveyed in dense phase there is the added

problem of the possibility that the air flow rate will also need to be increased if

there is a significant change in conveying distance.）

10.6 Conveying From Stockpiles从储存点的输送

If the material is to be conveyed from a stockpile, then a vacuum system using

suction nozzles will be ideal. The type of system required will depend upon the

application and conveying distance. For a short distance a vacuum system will

probably meet the demand on its own.如果物料是从储存点来输送，带吸嘴的真空系统是理想选择。该类型的系统需要将取决于应用和输送距离。短距离的输送，真空系统可能满足要求。

Where access is available to a free surface, as in ship off-loading, vacuum

nozzles can transfer material under vacuum to a surge hopper. If this is not the final

destination for the material it could be the intermediate hopper in a combined

positive and negative pressure conveying system, or the supply hopper for the

second part of a dual system, from where the material could be blown onward.凡能获得自由表面的地点，如在船舶卸货，真空喷嘴可在真空下把物料送到一个缓冲料斗。如果这不是物料输送的最后的目的地，它可能是负压-正压组合输送系统的中间料斗，或是双真空正压系统第二部分的供料斗，从那里物料可被正压吹送。For clearing dust accumulations and spillages, and surplus material deposited

in stockpiles, mobile units are particularly useful. These are generally suckblow

systems with a vacuum nozzle. Although they can be small versions of a

continuously operating suck-blow system, they are more usually batch conveying

systems with the transfer hopper acting also as a blow tank. Material is first drawn

into the hopper/blow tank under vacuum, and when it is full it is pressurized and

conveyed on to the reception point.清洁泄漏粉尘和储存点洒落物料，移动单元特别有用。这些一般是有真空喷嘴的吸-吹系统。虽然他们可以是小规模的连续吸-吹系统，他们更可能是有类似发送罐的输送仓的批次输送系统。物料首先真空提升进料斗/发送罐，当料斗装满后就加压输送到受料点。

10.7 Start-Up With Full Pipeline满管启动

If there is likely to be a need to stop and start the conveying system while it is

conveying material, a system capable of doing this will need to be selected. This is

rarely possible in conventional systems, and so consideration will have to be given

to innovatory systems.如果需要在物料输送过程中，停止并启动输送系统，需要选择能做到这一点的输送系统。常规系统很少能做到这一点，因此将不得不考虑创新系统。

Many of these systems are capable of starting with a full pipeline, although

their capabilities on vertical sections may need to be checked, particularly if the

stoppage is for a long period. The possibility of power cuts, from whatever source,

should also be taken into account here.许多这类系统能够在管道充满时启动，虽然它们在垂直段的能力要校核，特别是有很大一段堵住的时候。这里要考虑电力切断的可能性。

11 MATERIAL PROPERTY INFLUENCES物料性能的影响

The properties of the materials to be conveyed feature prominently in the decisions

to be made with regard to the selection of a pneumatic conveying system. As with

'System Requirements', considered above, some of the more common material

properties can be identified and are detailed here for easy access and reference.输送物料的性质对一个气力输送系统的选择有突出的影响。正如 '系统要求'所说 ，考虑上述情况，一些较常见的物料性能在这里列出并详细说明以供参考。

11.1 Cohesive粘性

Problems may be experienced with cohesive materials in hopper discharge, pipeline

feeding and conveying. If there is any difficulty in discharging a cohesive

material from a rotary valve, a blow-through type should be used. If there is any

difficulty in conveying a cohesive material in a conventional system, then an innovatory

system should be considered. The pulse phase system, for example, was

developed for the handling of such fine cohesive powders.有粘性物料在料仓卸料，管道喂料及输送中都会碰到一些问题。如果粘性物料通过一个旋转阀卸料有困难，应该采用直通型旋转阀。如果常规系统输送粘性物料有困难，应该考虑创新系统。比如，脉冲输送系统可用于输送有粘性的细粉料。

11.2 Combustible可燃性

There is a wide range of materials which, in a finely divided state, dispersed in air,

will propagate a flame through the suspension if ignited. These materials include

foodstuffs such as sugar, flour and cocoa, synthetic materials such as plastics,

chemical and pharmaceutical materials, metal powders, and fuels such as wood

and coal. If a closed system is used the oxygen level of the conveying air can be

controlled to an acceptable level, or nitrogen can be used. If an open system is to

be used, then adequate safety devices must be put in place. One possibility is to

use a suppressant system. Another is to employ pressure relief vents and other

safety features.有很多细磨过的物料，分散在空气中时，如果点燃会四处扩散（爆炸）。这些物料包括： 食品，如糖，面粉和可可，合成材料，如塑料， 化工和医药原料，金属粉末，及燃料，如木材和煤。如果是一个封闭式系统，要将输送空气中的氧含量控制到可以接受的水平，或使用氮气。如果是一个开放的系统，要设置适当的安全装置。一种是使用扑灭系统。另一种是采用泄压喷口和其他安全功能。

11.3 Damp or Wet潮湿或含水

Materials containing a high level of moisture can generally be conveyed in conventional

systems if they can be fed into the pipeline, and do not contain too many

fines. Most of the handling problems with wet materials occur in trying to discharge

them from hoppers. Fine materials may not discharge satisfactorily from a

conventional rotary valve and so a blow through type should be used.如果不含太多细料的高含水物料能喂进管道，就能通过常规的输送系统来输送。大部分的处理问题发生在含水物料从料斗中卸料时。细料用常规旋转阀卸料不是很令人满意，应该使用直通型的。

Fine materials which are wet will tend to coat the pipeline and bends, and

gradually block the line. Lump coal having a large proportion of fines is a particular

problem in this respect. Single plug blow tank systems and some of the innovatory

systems are capable of handling this type of material. If a conventional system

must be used, the problem can be relieved by heating the conveying air, if the material

is not too wet.含水的细料可能粘附在管道和弯头内壁，并逐步堵住管道。有很大比例细粉的块煤是这方面的一个代表。柱塞式发送罐系统和一些创新系统能够处理这种类型的物料。如果必须使用常规系统，如果材料是不是太潮湿，这个问题可以加热输送空气得到缓解。

11.4 Electrostatic静电

If the build up of electrostatic charge is a problem when conveying a material, the

air can be humidified. This process can be carried out on-line and does not usually

require a closed system. In dense phase the quantity of air which needs to be conditioned

is much less than in dilute phase systems, and so for materials capable of

being conveyed in dense phase, the operating costs for air quality control will be

lower. The entire system and pipe-work network should be earthed.如果输送物料时，静电会累积，可加湿输送空气。这一过程可以在线进行并且通常不需要一个封闭的系统。密相输送系统所需空气量比稀相输送系统要低很多，因此物料密相输送，空气方面的成本将较低（注：这一句好像和本小节内容无关^_^）。整个系统和管网应接地。

11.5 Erosive磨蚀性

If the hardness of the particles to be conveyed is higher than that of the system

components, such as feeders and pipeline bends, then erosive wear will occur at all

surfaces against which the particles impact. Velocity is one of the major parameters

and so the problem will be significantly reduced in a low velocity system. If a

dilute phase system must be used, feeding devices with moving parts, such as rotary

valves and screws, should be avoided, and all pipeline bends should be protected.如果输送颗粒的硬度高于系统组成部分，如喂料器和管道弯头，粒子将对这些表面有冲蚀磨损。速度是其中一个重要参数，所以在低速系统中，这个问题将大大减少。如果必须使用稀相系统，应当避免采用有移动部件的喂料设备，如旋转阀和螺旋机，所有管道弯头也应该得到保护。

11.6 Friable易碎性

If degradation of the conveyed material is to be avoided, a system in which the

material can be conveyed at low velocity should be considered. The magnitude of

particle impacts, particularly against bends in the pipeline, should be reduced as

this is one of the major causes of the problem. Damage caused by attrition as a

consequence of particle to particle and particle to wall surfaces must also be taken

into account. Pipeline feeding devices which can cause particle breakage, such as

screws, should also be avoided.如果要考虑输送物料因破碎而降级，应当考虑低速输送。应减少粒子群的碰撞，特别是对管道弯头的撞击，这是物料破碎产生的主要原因。粒子间及粒子和壁面间的磨损也要计算进去。也应避免使用能引起粒子破碎的管道喂料设备，如螺旋输送机。

11.7 Granular颗粒

Granular materials can be conveyed with few problems in pneumatic conveying

systems provided that they can be fed into the pipeline. Problems with feeding can

occur with top discharge blow tanks and conventional rotary valves. Air will often

permeate through granular materials in top discharge blow tanks and the materials

will not convey, particularly if the blow tank does not have a discharge valve.

Granular materials containing a large percentage of fines, and which are not capable

of dense phase conveying, may block in a top discharge line. In rotary valves,

shearing of granular materials should be avoided, and so a valve with an off-set

inlet should be used.只要颗粒料能喂进管道。就能较容易地进行气力输送。对上引式仓泵和常规旋转阀等喂料装置会有些问题。上引式仓泵中，特别是在没有出料阀门的情况下，空气通常会穿透颗粒料粒状物料，而导致物料不能被输送。含有很大比例细粉的颗粒料不能以密相输送，在上引式管道中会引起管道堵塞。应避免使用可能挤压颗粒料的旋转阀，需选择有偏置入口的旋转阀。

11.8 Hygroscopic吸湿性

If a material is hygroscopic the air used for conveying can be dried to reduce the

moisture level to an acceptable level. This process can be carried out on-line and

does not usually require a closed system. For a material which is only slightly hygroscopic,

successful conveying may be achieved if the material is conveyed in

dense phase, without the need for air drying equipment, since air quantities required

for conveying can be significantly lower than those for dilute phase

conveying.如果物料具有吸湿性，应干燥输送空气使其含水量保持在可接受的水平上。这一过程可以在线进行并且通常并不需要一个封闭的系统。对略有吸湿性的物料，可采用密相输送的形式，因为所需的空气量大大低于稀相输送系统而不需要空气干燥设备。

11.9 Low Melting Point低熔点

The energy from the impact of particles against bends and pipe walls at high velocity

in dilute phase conveying can result in high particle temperatures being generated.

The effect is localized to the small area around the point of contact on the

particle surface, but can result in that part of the particle melting. The problem is

accentuated if the particles slide on the pipe wall and around pipeline bends. Plastic

pellets such as nylon, polyethylene and polyesters are prone to melting when

conveyed in suspension flow.粒子与弯头和管壁高速碰撞产生的热量会使粒子温度升的很高。效果局限在粒子碰撞点附近一小块表面上，但可能会导致该部分粒子融化。如果粒子沿管壁和弯头外侧内壁滑动，那么问题就更大了。塑料丸粒，如尼龙，聚乙烯和聚酯以悬浮流输送时很容易发生融化。

Velocity is a major variable and so the problem will generally be significantly

reduced for most materials in a low velocity, dense phase system. If such

materials have to be conveyed in dilute phase a roughened pipeline surface may

help to reduce the problem considerably as this will prevent the particles from

sliding.速度是一个重要的因素，因此大多数物料而言，低速密相输送时问题程度会明显降低。如果这类物料不得不以稀相来输送，采用表面粗糙的管道可能有助于减少问题，因为这将大大防止颗粒滑动。

11.10 Radioactive放射性

Radioactive materials must be conveyed under conditions of absolute safety, and

so it would be essential to employ a closed system so that strict control of the conveying

environment could be maintained. A vacuum system would also be necessary

to ensure that no conveying air could escape from the system, or material in

the event of a bend eroding, for some of these materials do tend to be rather abrasive.放射性物料必须在绝对安全的条件下输送，并这样就必须采用一个封闭的系统，以便严格控制的输送环境可维持不变。可以采用真空系统以确保没有输送空气外泄，或物料不从磨损的弯头处（泄漏），因为其中一些材料往往是相当粗糙的。

11.11 Toxic有毒

If toxic materials are to be handled, strict control of the working environment must

be maintained. A vacuum system, therefore, would be essential to ensure that there

could be no possibility of material leakage. If the conveying air, after filtration,

could be vented safely to the atmosphere, an open system would be satisfactory. If

not, a closed loop system would have to be used.有毒物质的处理，必须维持严格控制的工作环境。真空系统可以完美的确保有没有任何物料泄漏的可能性。如果过滤后的输送空气，可安全排放到大气，一个开放的系统也可满足条件。如果不能，那么必须采用一个闭环系统。

11.12 Very Fine超细

A problem of pipeline coating can occur with very fine powders in the low micron

and sub-micron range, such as carbon black and titanium dioxide. These materials

tend to adhere to the pipe wall when conveyed in conventional systems. The coating

gradually builds up and can cause a marked reduction in the pipe section area,

and hence a reduction in conveying capacity. Many of the innovatory systems are

capable of handling this type of material successfully.微米和亚微米级的超细粉体用常规输送系统输送时会粘附在管道内壁上形成涂层，如炭黑和二氧化钛。涂层逐步积累，并可能导致管道流通面积明显减少， 从而减少了输送量。有许多创新系统有能力成功地处理这类材料。

If a conventional system is to be used the material should be conveyed

through a flexible pipeline or hose so that the material build-up can be shaken free

on a regular basis. It is quite likely that the natural pulsations that occur within the

system would be sufficient to vibrate the material free to enable it to be reentrained

in the conveying line.如果常规系统是通过挠性管道或软管来输送物料，那么有规律的摇晃会使涂层脱离。就像是发生在系统内的自然脉动将足以震动粘附的物料，使之脱离并被输送走（注：原文用了一个词“reentrained”-重新登上火车，比喻物料加入到输送行列里去。这里不太容易找到合适的语句去表达，所以采用了意译，在前面很多处及以后更多的地方都会采用这种翻译手法，以其在不曲解原意的情况下节省思考的时间^_^）。

引文

1. J-P. Hanrot. Multi-point feeding of hoppers, mounted on aluminum smelter pots, by

means of potential fluidization piping. Proc 115th An Mtg, The Metallurgical Soc of

AIME. pp 103-109. New Orleans. March 1986.