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Evaporation Systems-101

Evaporation Systems

Evaporation Systems

35

Evaporation of waste wash water occurs during normal operation of the pressure, steam or automatic vehicle wash sys-

tem. It is generally assumed that 10-30% of wash water is lost to evaporation. Accelerated evaporation can be used to

dispose of excessive wastewater, highly contaminated wastewater, or to remove recycled water with high dissolved solid

(TDS) build up.

General Definitions

Evaporation

The process in which a liquid dissipates or emits vapor, fumes, or invisible minute particles.

Distillation

A process that consists of driving gas or vapor from liquids or solids by heating and condensing to liquid products

once again.

BTU’s (British Thermal Unit)

Amount of energy required to raise a 1 lb. mass of water 1°F @ 1 atmosphere.

VOC’s (Volatile Organic Compound)

Organic compound which readily dissipates into the air at room temperature, i.e., benzene, gasoline.

TDS (Total Dissolved Solids)

The amount of ionic matter dissolved in a fluid and can be measured by electric current.

Thermal Oxidation

High temperature breakdown of contaminants to carbon dioxide and water.

TSS (Total Suspended Solids)

Substances suspended in a fluid large enough to be visible by the human eye and small enough to be kept in sus-

pension by the movement of the fluid molecules.

Condenser

An apparatus in which gas or vapor is condensed to a liquid form.

Efficiency

Water evaporation efficiency is based on some basic laws of physics:

It takes 9,274 BTU to evaporate 1 gal. of water from 70

F.

o

Natural gas has an approximate heating value of 1,000 BTU

f t

3

1 Therm = 100,000 BTU

Approximate cost of natural gas is $0.50 per Therm

Heat Transfer Equation -

Q = UA(  T)

Where“Q” = amount of heat transferred

“U” = heat transfer coefficient

“A” = area of heat transfer surface

“  T” =difference in temperature between heated surface of exposed material to be evaporated

and heating environment.

Cost Calculation Example:

Evaporators have a thermal efficiency of 60-80% (average of 70%). For calculations we’ll use 70% efficiency or 14,000

BTU to evaporate one gal of wastewater at sea level.

1000 gal. of wastewater x 14,000 BTU per gal. = 14,000,000 BTU, $0.90/Therm = $70 =

$0.09 cents per gal. evap.

Note: An efficiency factor is present with all evaporators and must be calculated separately.

Page 1

Evaporation Systems

Evaporation Systems

Methods

Natural Evaporation Ponds

Rely on the combination of solar heat and wind to naturally evaporate water. This method

requires a great deal of area, is slow, and is subject to the weather.

Problems:

- Very slow

- Requires large land mass and pond liner

Forced Air Evaporators

Utilize blowers to force air in a counter current to a spray of water pumped to the top of a column

and free falling downward. The evaporation rate is largely dependent on the water temperature

and the dew point. This method is cost effective and highly efficient when the waste stream to be

evaporated is preheated by another process, and the wastewater does not contain volatile com-

pounds (VOC’s) that would be readily transferred to the air, and thereby create air pollution. Not

recommended for water high in dissolved or suspended solids as they will deposit on the inter-

nals and block the water air flow. This design has no method of removing dried solids. Cost esti-

mates depend on the temperature of the waste stream.

Problems:

- Source water should be preheated by process generating waste.

- Efficiency is dependent on the relative humidity and water temperature.

- Air permitting may be required

Boiling Water Evaporators

Basically heating the water to its boiling point 212°F and exhausting the steam via an exhaust

pipe. This method has no way to remove dried solids other than baking the tank contents down to

a cake, which insulates the heat and holds it into the steel causing early tank failure. Efficiency is

usually 65-75% depending on design. With the addition of a condenser, you can distill the water

for reuse.

Problems:

- Acids and salts will attack the steel

Steam Tube with Water Exhaust Evaporator

Basically the same concept as a Boiling Water Evaporator. However, the hot exhaust gases are

bubbled through the wastewater to improve heat transfer efficiency. VOC’s will be vaporized and

air pollution will result. Dissolved and suspended solids removed periodically by draining a slurry.

Efficiency is 75-85%.

Problems:

- You still have a highly concentrated liquid water slurry to dispose of

- VOC’s will be exhausted as air pollution

- Acids and salts will attack the steel, shortened vessel, and steam tube life

- Air pollution permitting concerns

Heat Exchanger Evaporators

Heat a coil filled with a high temperature oil, which is pumped to another coil inside a tank contain-

ing the waste. The advantage to this system is that the tank can be made of non-corrosive

polypropylene with no direct flame contact. The vapor can be distilled, efficiency is 70-80%.

Problems:

- Air permitting may be required

- Coil failure

Page 2

Evaporation Systems

Evaporation Systems

Boiler Blow-Off Evaporators

Can evaporate large volumes (2-4 gpm) at a low cost and are effective on pretreated waste

streams. Have no method of collecting or removing of suspended solids. Most of the dissolved

solids are vaporized in the steam at 212°F and blown off into the atmosphere. VOC will be vapor-

ized and will create air pollution. Therefore, all VOC’s and solids must be removed from this sys-

tem. Efficiency is 70-85%.

Problems:

- No method of collecting solids, droplet carryover.

- VOC’s will vaporize and could create air pollution

- Not suitable for distillation for water reuse

Steam Tube Evaporators

Utilize a hot tube as a heat source. The flame is directed inside a steel tube thereby saving the

tank from flame impingement and early failure. The tube will fail. However, it is easily replaceable

and considerably less expensive than the tank. Efficiency is 70-80%. The water is heated to

212°F. The vapor can be distilled and reused.

Problems:

- VOC will be vaporized and will create air pollution

- Dissolved solids and suspended solids are periodically drained off in a slurry solution

and this highly concentrated liquid waste must be disposed of

- Acids and salts will attack steel vessel

- Low tube life expectancy

Liquid Thermal Oxidation

A method of liquid destruction. Through Flash Evaporation the liquid waste is atomized and

sprayed under pressure near a flame. At 1250°F all VOC’s and organics are oxidized, and dis-

solved and suspended solids are thermally oxidized to ash. Efficiency is 70-85%. Solid contami-

nants are reduced to a powdered inorganic ash.

Problems:

- Air permits may be required

Add-On Systems

Vapor Destruction System

Utilize ozone to oxidize remaining exhausting volatile organics followed by activated carbon to neu-

tralize the ozone.

Condensers

A heat exchanger that converts the vapor back to pure distilled water.

Page 3

Evaporation Systems

Evaporation Systems

RGF Thermo Oxidizer

Wastewater Advantages

The Thermo Oxidizer System completely oxidizes water borne waste streams, leaving only a dry powder as the residual

waste material. Unlike evaporators, the Thermo Oxidizer completely eliminates the water content of the liquid waste. The

unit eliminates the typical evaporator problems of corrosion, foaming, residual slurry, V.O.C. emissions, and difficult to clean

evaporator chambers.

THE CONCEPT

The

is designed to completely oxidize liquid waste, leaving only a dry ash residue. By automati-

Thermo Oxidizer

RGF

cally controlling the fuel modulation and the waste flow, maximum efficiency is achieved resulting in a fuel cost as low as

$0.10 per gallon.

utilizes a cast ceramic refractory for all interior combustion surfaces to eliminate corrosion and

RGF

metal failure. By utilizing an optional waste oil burner, the system can eliminate both waste oil and wastewater.

ADVANTAGES OF THERMO OXIDIZER FLASH EVAPORATION

Lower Cost Of Fuel

No Residual Slurry

Traditional evaporators utilize a wastewater reservoir of 50-

Traditional evaporators require a periodic removal of the con-

200 gallons, which must be heated and maintained to 212° F,

centrated slurry, which can consist of highly concentrated haz-

requiring a lot of wasted energy.

Flash Evaporator

RGF’s

ardous wastes presenting a disposal problem.

Flash

RGF’s

Process sprays a high pressure controlled atomized flow

Evaporator Process

directly into the flame, thereby eliminating the 50-200 gallon

totally oxidizes the

heated water mass, which results in a cost as low as $0.10 per

waste to ash, which

gallon. With the waste oil burner option, fuel cost is reduced.

may be disposed of as

Additional savings can be realized with the complete elimina-

non-hazardous. In

tion of both waste oil and water.

cases of highly con-

Reduced Air Emissions

taminated waste

Traditional evaporators simply heat water to 212° F, or boiling

streams, the oxidizer

Residue from 2,000 gal. of

point, which produces steam to evaporate the waste away.

is set for 1,400° F,

parts washer waste

However, V.O.C. - Volatile Organic Compounds are also driv-

which will render almost

en off with the steam producing air pollution problems that

any waste harmless.

could far exceed your wastewater problems.

Flash

RGF’s

No Corrosion

Evaporator Process will combust V.O.C. as the waste stream

Traditional Evaporators utilize a waste stream reservoir where

is atomized and sprayed under pressure into the chamber not

the water is heated to 212° F, or boiling, to produce steam

into the flame. A high fire setting is available with secondary

which is vented off as air emissions. The problem is heat,

chamber temperature of 1,400-1,600° F., 1,250° F is general-

water and steel do not mix well and, when added to the water

ly accepted as a total oxidation temperature for hydrocarbons.

chlorides and sodium, create a real corrosion problem. Even

expensive stainless steel will develop stress corrosion, crack-

ing, carbide precipitation, and inter granular corrosion, result-

ing in early failure.

, therefore, developed a high temper-

RGF

ature ceramic liner for the wet combustion chamber thereby

eliminating corrosion problems.

Page 4

Evaporation Systems

Evaporation Systems

RGF Thermo Oxidizer

Applications

RGF Thermo Oxidizer Flash Evaporator

The Thermo Oxidizer was designed by RGF to completely oxidize liquid waste, leaving only ash to dispose. The unit

meets NFPA86 Fire Safety Code requirements.

Unlike a stainless steel evaporator, the Thermo Oxidizer is not subject to chloride stress crack corrosion. It is easily

cleaned and requires little maintenance. The biggest difference is the total removal of water content by the Thermo

Oxidizer. The wastewater does not accumulate, making it impossible for the wastewater to concentrate. This is an

operational asset in that the emissions are not permitted to worsen with time, as they are with an evaporator.

Typical temperature settings range from 800 to 1,400oF. Incinerators operate between 1,800 and 3,000oF. The Thermo

Oxidizer works to thermally decompose chemicals within the wastes to their primary combustion products of CO2, H2O,

and simple compounds. At temperatures of 700oC, most chemicals are broken down into smaller molecular weight con-

stituents, and at temperatures of 1000oC, the majority of wastes are reduced to ash.

So what types of waste streams are applicable for treatment by the Thermo Oxidizer?

Petroleum Hydrocarbon Waste

RO, NF, UF Concentrators

Floor Scrubber Waste

·

·

·

Die Casting

Tumbling Solutions

Plating Solutions

·

·

·

Alkaline Cleaners

Waste Haulers

Textiles

·

·

·

Machinery Coolants

Process Wastewater

Heavy Equipment

·

·

·

Compressor Wastes

Printed Circuit Board Waste

Food Processing

·

·

·

Ink and Paint Waste

Tanker Cleaning

Manufacturing Processes

·

·

·

Electro Polishing Rinse Waters

Diesel Injector Cleaning

Oil Field Tool Cleaning

·

·

·

Thermally Oxidized

Combustion Gases

and Water Vapor

Hot Gases

Thermal

Oxidation

Chamber

Wastewater

Atomizer

Ceramic Liner

Dry Chamber

Dry Ash

Flash

Containing

Evaporator

Contaminants

Page 5

Evaporation Systems

Evaporation Systems

RGF Thermo Oxidizer Flash Evaporator

Model TO-30 (30 gph)

Specifications

F

u

e

l

:

N

G

o

r

L

P

Dimensions:

5’-2"W X 7’-2”D X 7’-10”H (w/o stack)

Electrical Requirements:

110VAC - 20 Amp - 1 Phase

Disposal Rate:

Up to 30 Gallons per hour, clean water

Construction:

Steel Plate / Ceramic Lined / S.S. Door

Air Supply Requirements:

12 SCFM @ 100 PSI

Typ. Temperature Settings:

800-1,400 F

Burner Safeguard Control:

UL,CSA Listed, FM And IRI Approved

Flame Monitor:

Flame Rod

Exterior Finish:

High Temp. Two-Part Polyurethane

Stack Height from Floor:

18’-6”

Other power available

US Patent #: 6546883

Description

Item #

Waste Evaporation Rate

Ship Weight

RGF Thermo Oxidizer TO-30 Wastewater Evaporator

TO-30-Y

Up to 30 gph

9,000 Lbs.

Item #

Suggested Accessories

OP-103-30

Spare Parts Kit

OI-058

Waste Oil Burner Option Installed (Does not include Oil Tank) 350,000 BTU

SA-148-2-Y

4’ H TO-30 Stack Section Unported

SA-149-2-Y

4

H

T

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OP-116

200 Micron Prefilter Assembly

RGF Thermo Oxidizer Flash Evaporator

Model TO-60 (60 gph)

Specifications

F

u

e

l

:

NG or LP

Dimensions:

6'-6"W X 6'-0”D X 8’-10”H (w/o stack)

Electrical Requirements:

230VAC - 20 AMP - 1 or 3 Phase

Disposal Rate:

Up to 60 Gallons per hour, clean water

Construction:

Steel Plate / Ceramic Lined / S.S. Door

Air Supply Requirements:

23 SCFM @ 120 PSI

Typ. Temperature Settings:

800-1,400 F

Burner Safeguard Control:

UL, CSA Listed, FM And IRI Approved

Flame Monitor:

Flame Rod

Exterior Finish:

High Temp. Two-Part Polyurethane

Stack Height from Floor:

19’-6”

Other power available

US Patent #: 6546883

Description

Item #

Ship Weight

Waste Evaporation Rate

RGF Thermo Oxidizer TO-60 Wastewater Evaporator

TO-60-Y

11,000 Lbs.

Up to 60 gph

Item #

Suggested Accessories

OP-103-60

Spare Parts Kit

OI-058

Waste Oil Burner Option Installed (Does not include storage tank) 350,000 BTU

SA-148-Y

4’ H TO-60 Stack Section Unported

SA-149-Y

4

H

T

O

-

6

0

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OP-116

200 Micron Prefilter Assembly

Page 6

Evaporation Systems

Evaporation Systems

RGF Thermo Oxidizer

Model TO-150 (150 gph)

Specifications

F

u

e

l

:

N

G

o

r

L

P

D

i

m

e

n

s

i

o

n

s

:

1

0

-

6

L

X

6

D

X

8

-

1

0

H

Electrical Requirements:

120 VAC - 5 A - 1 Phase

460 VAC - 10 A - 3 Phase

Disposal Rate:

Up to 150 Gallons per hour, clean water

C

o

n

s

t

r

u

c

t

i

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n

:

3

/

1

6

S

t

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P

l

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/

C

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L

i

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d

/

S

.

S

.

D

o

o

r

Air Supply Requirements:

43 SCFM @ 100 PSI

Typ. Temperature Settings:

800-1,400 F

Burner Safeguard Control:

UL,CSA Listed, FM And IRI Approved

Flame Monitor:

Flame Rod

Exterior Finish:

High Temp. Two-Part Polyurethane

Stack Height From Floor:

19’-10”

* Other powers available. Contact factory

US Patent #: 6546883

Waste Evaporation Rate

Description

Item #

Ship Weight

Up to 150 gph

23,000 Lbs

RGF Thermo Oxidizer TO-150 Wastewater Evaporator

TO-150-Y

.

Item #

Suggested Accessories

Spare Parts Kit

OP-103-150

Waste Oil Burner Option Installed 350,000 BTU (Does not include storage tank)

OI-058

4’ H TO-150 Stack Section Unported

SA-148-1-Y

4’ H TO-150 Stack Section Ported

SA-149-1-Y

200 Micron Prefilter Assembly

OP-116

Item #

Replacement Parts (All Models)

EL-050

10Amp DPDT Relay

EL-162

Contact Block

EL-167

Contact Block

EL-200

2 Output Temp Controller 120/60

EL-201

High Temp Limit Controller 120/60 AC

EL-202

Type “K” Thermocouple

EL-218

Indicators/Switch Light Bulb

EL-243

Flame Rod

EL-244

Spark Ignitor

EL-263

2 Burner Flame Safeguard Relay

PT-199

Air Regulator

PT-169

Nozzle Fluid Cap Gasket

PU-102-1

Air Service Kit for 1” Diaphragm Pump

PU-102-2

Fluid Service Kit for 1” Diaphragm Pump

VA-086

Solenoid Coil

VA-089

1/4” Solenoid Valve Assembly

VA-100

3/4” 120V Brass Solenoid Valve

All of the Above Replacement Parts Can be ordered in 1 Spare parts Package for the TO-150 Using

Note:

Item # OP-103-1

Page 7

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