化工原理英文教材固体干燥过程Drying of Solids
化工单元过程及操作中干燥流程工艺原理
英文回答：The drying process in the chemical unit is the process by which wet raw materials are reduced to the required water content by certain means。
Usually the drying process involves the exposure of wet raw materials to higher temperatures， the evaporation or volatilization of their internal water through heat winds or other heating media for drying purposes。
Depending on the process requirements and feedstock characteristics，there are many methods used for drying in chemical production，including but not limited to heating air drying， vacuum drying，spray drying， roller drying， etc。
The different drying methods differ from process to process， but the water within the feedstock is converted from liquid or adsorbent to vapourby heat transfer and then removed by dry media flow or exhaust。
化工单元中的干燥过程是将湿润的原料通过一定的方法使其含水量降低到符合要求的工艺过程。
大学化学《化工原理-干燥DRY3》课件
p-X图
T ?
p
0
X
四种水
平衡水 Ps p
结合水 0
T
自由水
非结合水 X
四种水的定义
• 平衡水: 用此种空气无法再去除的水; • 自由水: • 非结合水: 机械地附着在物料表面, 产生
的蒸汽压与纯水无异; • 结合水: 与物料之间有物理化学作用, 因
而产生的蒸汽压低于同温度下纯水的饱 和蒸汽压.
作业
• 1. 如果让你选择的话, 你会选择哪种作为 干燥介质?
• 2. 想一想, 为什么要混起来呢?
第四章 干燥(DRYING)
第一节 概述 第二节 湿空气的性质 第三节 干燥的平衡关系 第四节 干燥过程的动力学 第五节 干燥设备 第六节 干燥过程和设备的设计计算 讨论课 小结
X-图
• 是什么?
X*
0
X-图
• 为什么?
– 如何从p-X图得到 X-图? – 有何区别?(T) – 有何好处?(不同温度下曲线变化幅度很小,
便于估算)
X-图
•
四
X*
种
水
如
何Hale Waihona Puke 表示0?
第三节 干燥的平衡关系
1. 气体的组成 2. 固体的组成 3. 平衡关系图 4. 几个定义和为什么
– 平衡水, 自由水等 – 为什么用X-相对湿度图?
第三节 干燥的平衡关系
1. 气体的组成 2. 固体的组成 3. 平衡关系图 4. 几个定义和为什么
– 平衡水, 自由水等 – 为什么用X-相对湿度图?
水在气体和固体中组成之间的 关系
1. 气体的组成: pw,H…. 2. 固体的组成:
X(干基含水量, kg水/kg绝干物料) w(湿基含水量, kg水/kg湿物料)
第十四章--固体干燥(化工原理)
tas
t
ras c pH
(H as
H)
tw
t
rw 1.09
(Hw
H)
t
ras c pH
(Has
H)
tas
14.2.2 湿空气状态的变化过程
补充说明：
1）对于一定t、H的空气tas为一定值，故tas是 空气的状态函数。
2）对于空气－水系统，对照tw的定义式 α/kH≈1.09≈cpH，而ras ≈rw，故tas =tw
（1）物料的去湿方法
①机械去湿
物料带水较多时，可先用离心过滤等机械分离方法
以除去大量的水。
②吸附去湿
用某种平衡水汽分压很低的干燥剂（如CaCl2、硅胶
等）与湿物料并存，使物料中的水分相继经气相而转入
干燥剂内。
③供热干燥
向物料供热以汽化其中的水分。供热方式又有多种。
※去湿方法中较为常用的方法是供热干燥。
保持湿润，这支温度计为湿球温度计。
22
14.2.1 湿空气的状态参数
5）湿球温度tw
(t tw ) kH (Hw H )rw
空气传给水的显热 水汽化带走的潜热
湿球温度tw计算公式（推导过程见P221）:
式中：
tw
t
k H rw
(H w
H)
：空气至湿纱布的对流传热系数，W/m2 •℃；
=1，空气饱和，tw = t
②tw虽测的是湿纱布的温度，但它是由空气的H和 t 决定。即tw是空气的状态参数。
tw= f (H,t)，可由测定 tw后，由上式计算空气的H。
14.2.1 湿空气的状态参数
（2）与过程计算有关的参数 上述参数尚不足以满足干燥过程的计算
化工原理 第四章-干燥DRY6(续).
– 不能估算临界含水量
3. 干燥条件的确定
• 给定的条件
– Gc, X1, T1’ – X2, T2’ – To, H1 (当时当地, 废气循环)
• 需要确定的参数
– – – – L(H2), T1, T2 任意给定两个, 其余两个随之确定 eg1 T1, T2 >> H2 >>L eg2 L, T1 >> H2 >> T2
2.2 热量计算
QL L To L T1 L T2
Io Ho
QP
I1 H1 Gc X2
T2’ Gc X1 T1’
I2 H2 QD
• • • •
QD+LI1+GcI1’= QL + LI2+GcI2’ 其中, 物料的焓的基准为0°C绝干物料. I1’= GcCsT1’+ GcX1CwT1’ I2’= GcCsT2’+ GcX1CwT2’
• 影响产品质量吗?
湿焓图
I1 I2 I 1 T1 1
0
100％
To
0
Io H
H0 (H1)
H2
2.3 干燥时间
• 根据干燥实验确定. • 理论计算:
– 可以通过传热方程估算Uc Nr=Q=(T-Tw) 恒定干燥条件的假设 – 不能估计降速阶段的速度(或者说太难了)
• 气相中热质同时传递 • 固体中热质同时传递 • 蒸发面积连续发生变化
参数计算与设备之间的关系
• t(干燥时间) • ……长度(连续干燥时) • L(所用空气量) • ……直径 • Q(所需热量) • ……换热器的面积
作业
1. 试作等焓干燥时的操作线, 操作线该如何 定义? 2. 热效率 3. 预习 下周的作业1（下次讨论） (单号按并流考虑; 双号按逆流考虑)
化工原理第十三章干燥
第十三章 干燥 Drying
13.2.1 湿空气的性质
13.2.2 湿度图及其应用
第二节 湿空气的性质和湿度图
2024/2/8
13.2.1 湿空气的性质
1、湿含量H（ humidity）
单位质量干空气中所含水汽的质量 ，又称湿含量。
湿空气中水汽的质量 H 湿空气中绝干空气的质量
气中汽化
温增湿
焓 不 变
tas
饱和
一般情况下，绝热增湿过程可看视为等焓过程，即 空气释放的显热与水分汽化带回的潜热相等：
cH (t tas ) (Has H )ras
Has H cH 1.011.88H
tas t
ras
ras
Has、ras是tas的函数，cH是H的函数
2024/2/8
不饱和空气：t tas(t ) td
饱和空气： t tas (t ) td
2024/2/8
13.2.2 湿度图及其应用
1、H-t图
•F=2-1+2=3,总压P一定，则F=2.
•6条线
-等t线 –等H线 –等相对湿度线 –等CH线 –VH线 – tas线
2024/2/8
2、湿度图的应用
1）由测出的参数确定湿空气的状态 a）水与空气系统，已知空气的干球温度t和湿球温度tw，确 定该空气的状态点A(t,H)。 b）水与空气系统中，已知t和td，求原始状态点A(t,H)。 c）水与空气系统中，已知t和φ，求原始状态点A的位置 2）已知湿空气某两个可确定状态的独立变量，求该湿空气 的其他参数和性质
tM1)
qL
cwtM1
物料升温所需热量
2024/2/8
l
(I2
工艺流程图题干燥方法英语
工艺流程图题干燥方法英语Drying Methods.Drying is a process of removing moisture from a solid, liquid, or gas. It is used in a wide variety of industrial and commercial applications, including food processing, pharmaceutical manufacturing, and chemical processing.There are many different methods of drying, each with its own advantages and disadvantages. The most common methods include:Convection drying: This method uses hot air or other gases to evaporate moisture from the surface of the material being dried. Convection drying is a relatively simple and inexpensive method, but it can be slow and inefficient.Conduction drying: This method uses heated surfaces to transfer heat to the material being dried. Conductiondrying is a more efficient method than convection drying, but it can be more expensive and complex.Radiation drying: This method uses electromagnetic radiation to heat the material being dried. Radiation drying is a very fast and efficient method, but it can be expensive and requires specialized equipment.Freeze drying: This method involves freezing the material to be dried and then subliming the ice directly to a vapor. Freeze drying is a very gentle method that preserves the quality of the material being dried, but it is also expensive and time-consuming.The choice of drying method depends on a number of factors, including the type of material being dried, the desired moisture content, and the available budget.Convection Drying.Convection drying is the most common method of drying. It is used in a wide variety of applications, includingfood processing, pharmaceutical manufacturing, and chemical processing.In convection drying, hot air or other gases are passed over the surface of the material being dried. The heat from the air or gases evaporates the moisture from the surface of the material, and the evaporated moisture is carried away by the air or gases.Convection drying is a relatively simple and inexpensive method, but it can be slow and inefficient. The rate of drying depends on the temperature of the air or gases, the velocity of the air or gases, and the relative humidity of the air or gases.Conduction Drying.Conduction drying is a more efficient method of drying than convection drying. In conduction drying, heated surfaces are used to transfer heat to the material being dried. The heat from the heated surfaces evaporates the moisture from the surface of the material, and theevaporated moisture diffuses through the material to the surface.Conduction drying is a more efficient method than convection drying because the heat is transferred directly to the material being dried. This reduces the amount of time required to dry the material.Conduction drying is used in a variety of applications, including food processing, pharmaceutical manufacturing, and chemical processing. It is particularly well-suited for drying materials that are sensitive to heat or that have a high moisture content.Radiation Drying.Radiation drying is a very fast and efficient method of drying. In radiation drying, electromagnetic radiation is used to heat the material being dried. The heat from the radiation evaporates the moisture from the surface of the material, and the evaporated moisture is carried away by the air or gases.Radiation drying is a very fast and efficient method, but it can be expensive and requires specialized equipment. It is used in a variety of applications, including food processing, pharmaceutical manufacturing, and chemical processing. It is particularly well-suited for drying materials that are sensitive to heat or that have a high moisture content.Freeze Drying.Freeze drying is a very gentle method of drying. It is used to dry materials that are sensitive to heat or that have a high moisture content.In freeze drying, the material to be dried is frozen and then placed in a vacuum chamber. The vacuum chamber is then heated, and the ice in the material sublimes directly to a vapor. The vapor is then condensed and collected.Freeze drying is a very gentle method, but it is also expensive and time-consuming. It is used in a variety ofapplications, including food processing, pharmaceutical manufacturing, and chemical processing.。
Solids Mixing and Drying
课后翻译P127制药081班寇芸芸080203122Solids Mixing and Drying混合和干燥的固体Mixing混合The theory of solids mixing has not advanced much beyond the most elementary of concepts and , consequently , is far behind that which has been developed for fluids. 混合固体的理论已经不先进，远远超出最初级的概念，因此，远远落后于已开发流体。
This lag can be attributed primarily to an incomplete understanding of the ways in which particulate variables influence such systems and to the complexity of the problem itself.这种滞后主要可以归因于对微粒的变数影响这些系统和问题复杂性的本身的不完整的理解的方式。
When viewed superficially ,such multiparticulate（多粒子）solids as pharmaceutical bulk powders or tablet granulation are seen to behave somewhat like fluids.当从表面上看，作为制药原料粉末或片剂造粒等多粒子固体看到的行为有点像流体。
That is ,to the casual observer ,they appear to exhibit fluid-like flow when they are poured from one container to another and seem to occupy a more or less constant bulk volume.也就是说，不经意的观察，他们似乎表现出流体状流，即当他们从一个容器倒入另一个似乎占据了更多或更少恒定的总体积。
化工原理课程(全英文)教学课件 11
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Power Requirement & Motor Efficiency
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Date: April 9, 2015
Chapter 2 Transportation of Fluids
Pipe, Fittings, and Valves (pp. 82-88)
Fluid-Moving Machinery (流体输送机械)
− Pumps (pp. 88-93)
− Positive-Displacement Pumps (pp.93-95)
7
© 2015 Yanwei Wang
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2.4 Hvv
t
2vvvH7H2vv37vH3(H0(.10711v78.72.gv071g2123.PH2241v.14Hv4.H02v54)v[4tmtH2237)27237w373ta321te.720r31713P3.v01a101p53P.o0r1k13Pg051w[0ma5 te3水 r v汽apkogr]水
nv pv p ng pg P p H 0.622 p (5 2) H=f（P，p）
P p
p=pv—partial pressure of water vapor in moist air, N/m2; pg—partial pressure of dry air in moist air; P—total pressure of moist air, N/m2.
Hs
0.622
ps P ps
(5 3)
ps f (t) Hs f (P,t)
Where p=ps=f(t), ps=vapor pressure of water, Hs=f(P, t)
15
•(2)Specific volume of moist air :
Specific volume of dry air:
(2)continuous and batchwise drying processes. (3)According to the heat transfer manners: 1)Indirect dryers/dryers in which heat is transferred to the
solid from an external medium(condensing steam, etc) 2)Convective/direct dryers/Dryers in which the solid is directly
ห้องสมุดไป่ตู้13
1. Moist air properties (1. a).Humidity H [kg water vapor/kg dry air]
H water vapor mass of moist air M vnv 18 nv dry air mass of moist air M gng 29 ng
化工原理 Principles of Chemical Industry
Drying of Solids
Introduction
1.Methods for removing liquid from solid materials (1)Mechanically: By presses or centrifuges, etc. (2)By physical-chemical process: Only small amounts of
liquid removed. (3)Thermally: Liquid is heated and vaporized, and then
removed---Drying. •It is generally cheaper to remove liquid mechanically than thermally, and thus it is advisable to reduce the liquid content as much as practicable before feeding the material to a heated dryer.
3
Introduction
2.Purposes and applications of drying •Purposes: Drying makes materials more convenient in packaging, transporting, preserving, fabricating, and applying; and improves quality of products. •Applications: ….
When p=0,=0，湿空气不含水，为绝干空气。
When p= 力。
ps,=100%,空气中水气已饱和，无干燥能
18
(4)Humid Heat CH： [KJ/（kg dry air·℃）]
CH Cg HCv Cg 1.01[kJ /(kg dry air C)] Cv 1.88[kJ /(kg water vaporC)] CH 1.011.88H (5 7a)
6
4.Drying conditions for convective dryers
Material Liquid Hot air Material Liquid Hot air
Necessary : pw p MateriDalriving force：( pw p) 0
MaterLiiaqluid•Question: Is the drying process LiquiHd ot aaircombination of heat transfer Hot air and mass transfer?Why? What
heat transfer area of heater; (4)Calculation of drying rates and drying time; (5)Equilibrium relationship; (6)Selection of drying equipment; (7)Operation and enhancement of drying
Wet material WasWteet gmasaterial
Dried product
DrySecrhematic diDagrryDainmrgyoefrpcroondvueccttive drying process
Waste gas
Waste gas
Drying product Drying product
Air
Wet pmWreaehtteeraimtaeDlar treyreiral
preheater
DryeWr eDtrymeraWtearisatel ga
Air
WetAimr aterial WastDe Wrygaeasrste Dgraysing p
Schematic
preheater
diaDgrryapemrreohfecaotnervectivDe dryryiWningaDgsrtpyperironocgdeausscsptroduct
2.4 t•vvvvS2vvgvgpv72gHe37c121i1381f921vi18c92g1221v922o..2H0.42l4u2v12vm.23.t4Pt42e227.21o7243t7f037t3w32527[a271t2mt137.e37.0203r313干 17v32P3Pa371空 p111.30o.0005r气51:[1[m3mP31kP33水g.01干 1d汽010r5空 y35kP[g[ma气 m水1i3r3汽]0k干g5]w空 [admrtye气3r干 akirvg空 ]干 ap气 空 or气 kkgg]
equipment.
9
Principal subject matter of this chapter
(1)Properties of Moist air; (2)Phase equilibria of drying process; (3)Drying curve and drying rate curve under
4
Introduction
3.Classification of drying processes (1)Atmospheric and vacuum drying processes.
Question: why no drying process with pressure greater than 1 atm?
exposed to a hot gas
5
Introduction
3)Drying by radiant energy 4)Drying by dielectric/microwave energy 5)Freeze-drying 6)Combining drying •Most common used: Convective/direct dryers •Common used drying medium: air; •Common liquid existing in solids: Water.
constant drying conditions; (4) Material and heat balances, calculation of
drying rates and drying time; (5)Principles and structures of typical drying
：单位质量的绝干空气], where vapor means the gaseous form of the
component that is also present as liquid and gas is the component present only in gaseous form;
(b)A unit mass of bone-dry material[单位质量的 绝干物料.]
12
(1)Moist air can be considered as ideal gas, I.e., mixtures of gas and vapor follow the ideal gas laws.
(2)The usual basis for engineering calculations: (a)A unit mass of vapor-free air/dry air[计算基准
equipment.