冷却塔全接触

McQuayBy

Nick

Chan(陈万里)中国Cooling

TowerTrainingPrepared

By：Nick

Chan

（陈万里）By

Nick

Chan(陈万里)

Cooling

tower

冷却塔AgendaTraining

Agenda:

Cooling

TowersIntroduction

简介Types

of

cooling

towers

类型

Assessment

ofcoolingtowers评估

Energy

efficiency

opportunities

节能方案Introduction

冷却塔简介Main

Features

of

Cooling

Towers整体结构IntroductionComponents

of

a

cooling

tower冷却塔组成部分Frame

and

casing:supportexteriorenclosures

支架和塔体:外部支撑Fill:

facilitate

heat

transfer

by

maximizingwater

/

aircontact填料：为水和空气提供尽可能大的换热面积IntroductionSplash

fill

–

droplets

of

water

splash

over,

preventfouling喷淋式—将水呈水雾状喷出，这样的方式可以避免塔内结垢。Film

fill

–

layers

of

water

fall

over

(more

efficient),

butmore

expensive水膜式—水呈膜状顺填料表面流下，效率较高但是成本高昂。Cold

water

basin:

receives

water

at

bottomof

tower冷却水槽：位于冷却塔底部，接收冷却水MS1幻灯片6MS1需要定期放水，防止水槽内部运行时间太长，内部产生杂质和菌类MC

SYSTEM,

2009/4/22Introduction喷淋式水膜式Introductioncapture

droplets

in

air

stream回收空气流带走的水滴Air

inlet

进风口：entrypoint

of

air

冷却塔空气入口Louvers冷却塔百叶窗：equalize

air

flow

into

the

fill

and

retain

water

within

tower平均进气气流；保留塔内水分Components

of

a

cooling

tower冷却塔组件Drift

eliminators

收水器:IntroductionNozzles

淋水装置：spray

water

to

wet

the

fill将冷却水喷出Fans

风机：deliver

air

flow

in

the

tower向冷却塔内送风Propeller

fans

used

in

induced

draft

towers轴流风扇用于诱导通风冷却塔Propeller

&

centrifugal

fans

used

in

forced

draft

towers轴流/离心风扇用于强制通风冷却塔Training

Agenda:

Cooling

TowersIntroduction

简介Types

of

cooling

towers

类型

Assessment

ofcoolingtowers评估

Energy

efficiency

opportunities

节能方案Types

of

Cooling

Towers

冷却塔种类Natural

Draft

Cooling

Towers自然通风冷却塔Hot

air

moves

through

tower密度较小的热空气自冷却塔顶部流出Fresh

coolairisdrawnintothetowerfrombottom密度较大的冷空气自塔底部进入冷却塔填补Types

of

Cooling

Towers

冷却塔种类Natural

Draft

Cooling

Towers

自然冷却塔No

fan

required不需风机Concrete

tower

<200m混凝土塔<200

mUsed

for

large

heat

duties用于大热量的冷却Types

of

Cooling

Towers

冷却塔种类Natural

Draft

Cooling

Towers

自然冷却塔横流对流Types

of

Cooling

Towers

冷却塔类型两种冷却塔横流对流Large

fanstoforceair

throughcirculatedwater大功率风机强制空气与循环水的换热Water

falls

over

fill

surfaces:

maximum

heattransfer填料表面的水膜可以最大限度地与空气进行换热Types

of

Cooling

Towers

冷却塔种类Mechanical

Draft

Cooling

Towers机械通风冷却塔Types

of

Cooling

Towers

冷却塔种类Cooling

rates

depend

on

many

parameters冷却效率的决定因素有很多Large

range

ofcapacities多种冷却能力备选Canbe

grouped,

e.g.

8-cell

tower可以多冷却塔同时工作，例如8塔联控。MS2幻灯片16MS2湿球温度，填料，风扇MC

SYSTEM,

2009/4/22Forced

draft强制通风冷却塔Induced

draft

cross

flow诱导通风横流冷却塔Induced

draft

counterflow诱导通风逆流冷却塔Types

of

Cooling

Towers

冷却塔种类

Mechanical

Draft

Cooling

TowersThree

types

机械通风冷却塔分为三类：Types

of

Cooling

TowersForced

Draft

Cooling

TowersAir

blown

through

tower

bycentrifugal

fan

at

air

inlet空气由离心风扇吹入通风口Advantages:

suited

for

highair

resistance

&

fans

arerelatively

quiet优势：适用于气流阻力较大的塔体；离心风扇噪声相对较小Disadvantages:

recirculation

due

to

high

air-entry

and

lowair-exit

velocities劣势：由于进气流速高于排气流速，会出现回流。19Cooling

Tower

BasicsForced Draft

强制通风Counter

flow

Tower

逆流冷却塔Water

is

sprayed

on

to

the

fill

andfalls

to

the

tower

basin.冷却水被喷淋在填料上，向下流入冷却水槽Air

is

blown

up

through

the

fill

andevaporates

some

of

the

water

andreduces

the

water

temperature.空气从底部强制吹入，在填料内与水接触蒸发部分冷却水，从而降低水温Types

of

Cooling

TowersInduced

Draft

Cooling

Towers诱导通风冷却塔Two

types诱导通风冷却塔分两类：Cross

flow

横流式诱导通风冷却塔Counter

flow

逆流式诱导通风冷却塔Types

of

Cooling

TowersAdvantage:

less

recirculation

than

forceddraft

towers

&

lower

motor

running

cost优势：回流程度低于强制通风冷却塔；风机运 行费用小于强制通风冷却塔。Disadvantage:

fans

and

motor

drivemechanism

require

weather-proofing劣势：风扇与电机的机械传动需要防水设计Hot

water

enters

at

the

top

热水从顶部进入冷却塔Air

enters

at

bottom

and

exits

at

top空气通过风扇强制诱导，从底部进入冷却塔Uses

induced

draft

fans

使用强制诱导风扇Types

of

Cooling

TowersInduced

Draft

Counter

Flow

CT23Cooling

Tower

BasicsInduced

Draft

诱导通风Counter

flow

Tower

逆流式Water

is

sprayed

on

to

theFill

and

falls

to

the

towerBasin冷却水从顶部喷入，流经填料层进入冷却水槽Air

is

drawn

through

theFill

and

evaporates

someOf

the

water

and

reducesThe

remaining

watertemperature.空气由诱导风机引入冷却塔从底部，在填料内与水接触蒸发部分冷却水，从而降低水温Due

to

their

pressurized

spray

water

distributionsystem

因为此类冷却塔内的加压配水喷淋装置：Advantages

优势: Increased

tower

height

accommodates

longer

ranges

and

closerapproaches通过增加塔的高度来获得更长的换热流程与更小的冷幅More

efficient

use

of

air

due

to

finer

droplet

size

from

pressuresprays由于加压喷淋装置可以喷出更小的水滴，因此换热效率较高Cooling

Tower

BasicsInduced

draft

–

counter

flow逆流式诱导通风冷却塔Cooling

Tower

BasicsDisadvantages

劣势：Increased

system

pumping

head

requirements系统水泵压头增加Increased

energy

consumption

and

operating

costs能量需求增大，运行费用增加Distribution

nozzles

difficult

to

inspect

and

clean冷却水喷头不易维护和清洁Requires

extra

distributor

and

external

piping

costs需要配水系统以及相关管路，因此初投资增加Water

enters

top

and

passes

over

fill

冷却水从顶部进入，流经填料层Air

enters

on

one

side

or

opposite

sides

空气从一侧或两侧进入Induced

draft

fan

draws

air

across

fill

诱导风机使空气横向流过填料层Types

of

Cooling

TowersInduced

Draft

Cross

Flow

CT横流式诱导通风冷却塔27Cooling

Tower

BasicsInduced

DraftCross

Flow

TowerWater

is

sprayed

on

to

theFill

and

falls

to

the

towerBasin.

Fill

is

deeper

largerSurface

area.冷却水喷淋至填料层，从顶部流至底部的冷却水槽Air

is

drawn

through

theFill

and

evaporates

someOf

the

water

and

reducesThe

watertemperature.Less

airrequired空气由诱导风机引入冷却塔侧面，在填料内横向流动与水接触蒸发部分冷却水，从而降低水温Due

to

their

gravity

flow

hot

water

distribution

system由于此类冷却塔的水属于自然流配水系统：Advantages

优势：Low

pumping

head低水泵压头Lower

first

cost

pumping

systems较低的水泵初投资Lower

annual

energy

consumption

and

operating

costs较低的年运行能耗和费用Accepts

larger

variation

in

water

flow

without

adverse

effect

on

the

waterdistribution

pattern流量变化较大时不会对配水系统造成不利的影响Cooling

Tower

BasicsInduced

draft

–

cross

flow横流式诱导通风冷却塔Cooling

Tower

BasicsDisadvantages

劣势：Low

pressure

head

on

the

distribution

pan

may

encourage

orificeclogging

and

less

water

breakup

at

spray

nozzle低压头会导致喷头易于堵塞以及冷却水喷出时不能很好的分散成细密水雾Exposure

to

air

in

the

hot

water

basin

may

accelerate

algae

growth热水水槽直接暴露于空气中会导致藻类的滋生Larger

footprint占地面积较大Training

Agenda:

Cooling

TowersIntroduction

简介Types

of

cooling

towers

类型

Assessment

ofcoolingtowers评估

Energy

efficiency

opportunities

节能方案Assessment

of

Cooling

TowersMeasured

Parameters

应测量的参数Wet

bulb

temperature

of

air

空气湿球温度Dry

bulb

temperature

of

air

空气干球温度Cooling

tower

inlet

water

temperature

冷却塔进水温度Cooling

tower

outlet

water

temperature

冷却塔出水温度Electrical

readings

of

pump

and

fan

motors水泵和电机运行参数Water

flow

rate

水流速度Air

flow

rate

空气流速运行参数Range

冷却水温差Approach

冷幅Effectiveness

效率Cooling

capacity

冷却塔容量Evaporation

loss

蒸发损失Cycles

of

concentration

浓缩倍数Blow

down

losses

排污损失Liquid/Gas

ratio

液体/气体比Assessment

of

Cooling

TowersPerformance

Parameters1.Range

冷却水温差Difference

betweencooling

water

inlet

andoutlet

temperature:冷却水进出水温差：Range

(°C)

=

CW

inlettemp

–

CW

outlet

tempHigh

range

=

goodperformance大温差=高性能冷却水温差冷幅冷却水温度(进水)冷却水温度(出水)湿球温度(进水)进冷却塔(出水)出冷却塔Assessment

of

Cooling

Towers2.Approach

冷幅Difference

between

coolingtower

outlet

cold

watertemperature

and

ambientwet

bulb

temperature:冷却塔出水温度与入口空气湿球温度的差值：Approach

(°C)

=CW

outlet

temp

–

Wet

bulbtempLow

approach

=

goodperformance小冷幅=高性能冷却水温差冷幅Hot

Water

Temperature

(In)Cold

Water

Temperature

(Out)Wet

Bulb

Temperature

(Ambient)(In)

to

the

Tower(Out)

from

theTowerAssessment

of

Cooling

Towers3.Effectiveness

效率Effectiveness

in

%=

Range

/

(Range

+

Approach)效率=冷却水温差/（冷却水温差+冷幅）High

effectiveness

=

goodperformance高效率=高性能Assessment

of

Cooling

Towers冷却水温差冷幅冷却水温度(进水)冷却水温度(出水)湿球温度(进水)进冷却塔(出水)出冷却塔4.Cooling

Capacity

冷却塔容量Heat

rejected

in

kCal/hr

or

tonsof

refrigeration

(TR)=

mass

flow

rate

of

water

Xspecific

heat

X

temperaturedifference冷却塔容量单位为“千卡每小时”或者“冷吨”冷却塔容量=冷却水质量流量X水的比热容X温差High

cooling

capacity

=

goodperformance大容量=高性能Assessment

of

Cooling

Towers冷却水温差冷幅冷却水温度(进水)冷却水温度(出水)湿球温度(进水)进冷却塔(出水)出冷却塔5.Evaporation

Loss

蒸发损失Water

quantity

(m3/hr)evaporated

for

cooling

duty蒸发损失的单位为(m3/hr)，表示每小时因为冷却而损失的水量=

theoretically,

1.8

m3

for

every10,000,000

kCal

heat

rejected理论上蒸发损失为1.8立方米/1千万千卡=0.00085x1.8x流量(m3/hr)x冷却水温差Assessment

of

Cooling

Towers冷却水温差冷幅冷却水温度(进水)冷却水温度(出水)湿球温度(进水)进冷却塔(出水)出冷却塔Assessment

of

Cooling

TowersEvaporation

Loss

蒸发损失CoolingTowerIndustry(CTI)RatesTowers

At

ARICondenserWater

工业冷却塔的ARI工况：Water

flow

rate

across

cooling

tower

=

0.054

(L/s)

/

Kw冷却塔流量=0.054

(L/s)/KwCooling

tower

capacity=3500kW

冷却塔容量=3500kW29.4℃Leaving

Fluid

出水温度29.4

℃35℃Entering

Fluid

进水温度35

℃Use

the

formula

from

previous

page

应用前一页的公式:=0.00085

x

1.8

x

流量(m3/hr)x

冷却水温差=

0.00085

x

1.8

x

680.4

x

(35

–

29.4)=

5.82

m3/hrA

3500

kW

Tower

Can

Consume

5820

Liters

Per

Hour

of

Make

up

Water

Due

ToEvaporation

一个3500kW冷却塔的冷却水蒸发量为5820升每小时Assessment

of

Cooling

TowersCycles

of

concentration

浓缩倍数Ratio

of

dissolved

solids

in

circulating

water

to

the

dissolvedsolids

inmake

upwater

循环水中固态溶解物含量与补充水中固态溶解物的含量之比Increase

this

to

reduce

water

loss增加此比例可减小蒸发损失Blow-down排污量Depend

on

cycles

of

concentration

and

the

evaporation

losses决定于循环水浓度与蒸发损失Blow-down

=

circulating

water

removed

amount

to

maintain

theamount

of

dissolved

solids

and

other

impurities

at

an

acceptablelevel

=

Evaporation

Loss

/

(C.O.C.

–

1)排污量=为将固态溶解物和其他杂质浓度维持在可接受范围内而排出的循环水量=蒸发损失/（

C.O.C.–1）8.Liquid

Gas

(L/G)Ratio

液气比Ratio

between

water

and

air

mass

flow

rates水与空气的质量流量之比Heat

removed

from

the

water

must

be

equal

to

theheat

absorbed

by

the

surrounding

air冷却水散发的热量等于空气吸收的热量L(T1

–

T2)

=

G(h2

–

h1)L/G

=

(h2

–

h1)

/

(T1

–

T2)T1=hot

water

temp

(oC)热水温度（冷却塔进水）T2=cold

water

temp

(oC)冷水温度（冷却塔出水）Enthalpy

of

air

water

vapor

mixture

at

inlet

wet

bulb

temp

(h1)andoutlet

wet

bulb

temp

(h2)冷却塔进口（空气与水蒸气混合）温度对应的焓值(h1)与出口温度（湿球温度）的焓值(h2)Assessment

of

Cooling

Towers41Cooling

Tower

Process

冷却塔工作流程354555758595115103.9kJ/kg78.5kJ/kg6580%60%40%20%10%30%Air

Enters

at35

℃

DB26

℃

WB空气35℃DB

26℃WBAir

Leaves

Saturatedat30.8

℃2.

30.8℃饱和空气离开冷却塔3.

Entering

Air

Enthalpyis

78.5

kJ/kg3.

进口空气的焓值是78.5kJ/kg4.

Leaving

AirEnthalpyis

103.9

kJ/kg出口空气的焓值是103.9kJ/kg5.Water

VaporizedLatent

Heat

is

2430

kJ/kg11

g

water

absorbs

26.7kJ

heat

duringevaporating5.

蒸汽的潜伏热值是2430kJ/kg，11g的水吸取

26.7kJ的热量6.

Air

Sensible

heatis26.7

–

25.4

=

1.3

kJ6.

空气的感热为26.7

–

25.4

=

1.3

kJ17.3g105

28.3gL/G

=

(h2

–

h1)

/(T1

–

T2)L/G

=

(103.9

–

78.5)

/

(35

–30.8)L/G

=

25.4

/

11

=6.05(g/g)Training

Agenda:

Cooling

TowersIntroduction

简介Types

of

cooling

towers

类型Assessment

of

coolingtowers

评估Energy

efficiency

opportunities

节能方案Energy

Efficiency

OpportunitiesSelecting

a

cooling

tower选择冷却塔Fills填料Pumps

and

water

distribution水泵与配水设备Fans

andmotors风扇与电机Energy

Efficiency

OpportunitiesSelecting

a

cooling

tower

选择冷却塔Capacity

冷却塔容量Heatdissipation

(kCal/hour)散热量(kCal/hour)Circulatedflowrate(m3/hr)循环水流量(m3/hr)Other

factors其它因素Energy

Efficiency

OpportunitiesSelecting

a

cooling

towerRange

冷却水温差Range

determined

by

process,

not

by

system冷却水温差取决于换热过程而不是设备Approach

冷幅Closer

to

the

wet

bulb

temperature•

=

Bigger

size

cooling

tower•

=

More

expensive越接近湿球温度=更大的冷却塔=更多的投资Energy

Efficiency

Opportunitiesby

the

desiredDetermined

by

process决定于换热过程Required

cooling

is

controlledoperating

temperature合适的工况下才能保证需要的冷量High

heat

load

=

large

size

and

cost

of

coolingtower热负荷大=更大的冷却塔与更多的设备费用1.

Selecting

a

cooling

towerHeat

Load热负荷Energy

Efficiency

OpportunitiesWet

bulb

temperature

–

considerations:关于湿球温度Water

is

cooled

to

temp

higher

than

wet

bulb

temp冷却水出水温度高于空气湿球温度Conditions

at

tower

site冷却塔坐落位置的具体情况Not

to

exceed

5%

of

design

wet

bulb

temp湿球温度不可高于设计湿球温度的5%及以上The

designed

wet

bulb

temp

is

refer

to

ambient

WB

(preferred)orinlet

此湿球温度指的是环境湿球温度（推荐）或者空气入口处湿球温度Can

tower

deal

with

increased

wet

bulb

temp?冷却塔能否适应较高的湿球温度Relationship

range,

flow

and

heat

load温差，流量与热负荷的关系Range

increases

with

increased：以下两项增加的情况下温差会增大：Amount

circulated

water

(flow)

循环水量（流量）Heatload

热负荷Causes

of

range

increase

温差增大的原因如下：Inlet

water

temperature

increases

进水温度升高Exit

water

temperature

decreases

出水温度降低Consequence

=

larger

tower冷却水温差增大=更大的冷却塔Wet

bulb

temperature

influence

on

chillerperformance

湿球温度对机组运行的影响Lowering

condenser

water

impact

onchiller

improvement冷却水温下降对机组性能的影响0.56

Deg

CLowering

condenser

water

impact

oncooling

tower冷却水温下降对机组性能的影响3.9

Deg

CGet

temperature

data

from

customer用户提供的湿球温度变化图1月1日1月15日1月29日2月12日2月26日3月12日3月26日4月9日4月23日5月7日5月21日6月4日6月18日7月2日7月16日7月30日8月13日8月27日9月10日9月24日10月8日10月22日11月5日11月19日12月3日12月17日12月31日湿球温度(℃)湿球温度变化图35302520151050-5-10湿球温度WB

≤

26Deg

C=337

DaysWB

＞

26

DegC

=27

DaysEnergy

Efficiency

OpportunitiesFill

media

填料Hot

water

distributed

over

fill

mediaandcools

down

through

evaporation热水经过配水设备流经填料介质，蒸发降温Fill

media

impacts

electricity

use填料介质影响冷却塔用电量Efficiently

designed

fill

media

reduces

pumping costs

高效填料介质可以节约管路投资Fill

media

influences

heat

exchange:

surface

area, duration

of

contact,turbulence填料介质影响换热效率：表面积，接触时间与湍流Energy

Efficiency

Opportunities喷淋式水膜式低堵塞水膜式L/G1.1

–

1.51.5

–

2.01.4

–

1.8有效换热面积30

–

45

m2/m3150

m2/m385

-

100

m2/m3填料高度5

–

10

m1.2

–

1.5

m1.5

–

1.8

m压头9

–

12

m5

–

8

m6

–

9

m风量需求高很低低2.Fill

media

填料介质Comparing

3

fill

media:

film

fill

m