Useful Documents Related to Cooling Tower

Cooling Tower is widely used in Refinery and PetroChemical Industry to remove heat from process system and rejected heat into atmospheric which act as natural heat sink. There are many useful articles related to Cooling Tower and tabulated below for access.

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Cooling Tower Performance Basic Theory and Practice (New)

SPX Cooling Technologies

A cooling tower is a specialized heat exchanger in which two fluids (air and water) are brought into direct contact with each other to affect the transfer of heat.

ClearSky™ Plume Abatement Brochure (New)
Marley ClearSky™ Plume Abatement System is a ground-breaking approach to the reduction of cooling plumes. Employing leading-edge technology, not only does ClearSky provide the proven performance you need—including design flexibility—but it can also lower installation and operating costs. In fact ClearSky has simply the best value proposition in plume abatement—it can even be installed into existing cooling tower applications, negating the need for complete system replacement.

Cooling Tower Thermal Design Manual
Daeil Aqua

If you are professional engineer, fresh engineer or student and working or interested in COOLING TOWER thermal design, "Cooling Tower Thermal Design Manual" one of the FREE e-manual that you shall not miss. It available FREE for browsing and provided by Daeil Aqua, a specialist company in cooling tower design.

Cooling Tower Fundamentals
SPX Cooling Technologies

Cooling Tower Fundamentals is devoted to the implementation of water cooling systems which satisfy design and environmental requirements with sound engineering and responsible cost.

Wet Cooling Tower : Rule-of-Thumbs, Design & Simulation
U.S Dept. of Energy

A survey of wet cooling tower literature was performed to develop a simplified method of cooling tower design and simulation for use in power plant cycle optimization. In the report the theory of heat exchange in wet cooling towers is briefly summarized. The Merkel equation (the fundamental equation of heat transfer in wet cooling towers) is presented and discussed. The cooling tower fill constant (Ka) is defined and values derived. A rule-of-thumb design information useful in power plant cycle optimization, including tower dimensions, water consumption rate, exit air temperature, power requirements and construction cost. In addition, a method for simulation of cooling tower performance at various operating conditions is presented. This information is also useful in power plant cycle evaluation. Using the information presented in this report, it will be possible to incorporate wet cooling tower design and simulation into a procedure to evaluate and optimize power plant cycles.

Cooling Tower Basic Control System Manual (Updated)
SPX Cooling Technologies
Factory Installation, Field Connection, Operation, Parts List, Maintenance, and Troubleshooting Manual

Cooling Tower Energy and Its Management
SPX Cooling Technologies
Because of the fuel shortages which began to manifest themselves in the early 1970s, the cost of energy began its asymptotic rise. Current general awareness of the energy problem has made the quest for improved energy efficiency seem to be an effort that is in its infancy.

Cooling Towers and Salt Water
SPX Cooling Technologies
For cooling tower service, any circulating water with more than 750 parts per million chloride expressed as NaCl is generally considered as salt water. However, the effects of chlorides will be much less severe at 750 ppm than they will at higher concentrations.

Corrosion Protection for Cooling Towers
SPX Cooling Technologies
The forces of corrosion (as the term is being used in this paper) are those elements or compounds whose natural tendency is to chemically or electrolytically react with a metal, given the opportunity and a proper set of circumstances.

How to Keep Cooling Towers Running Strong
SPX Cooling Technologies
Part one of a guide to cooling tower maintenance, focuses on the mechanical aspects of cooling towers. Written by Ken Mortensen, SPX Cooling Technologies. RSES Journal, April 2003.

How to Manage Cooling Tower Water Quality
SPX Cooling Technologies
Part two of a series on cooling towers, reviews the importance of water management, treatment and system monitoring for peak performance. Written by Ken Mortensen, SPX Cooling Technologies. RSES Journal, May 2003.

A Comprehensive Approach to the Analysis of Cooling Tower Performance
SPX Cooling Technologies
The generally accepted concept of cooling tower performance was developed by Merkel in 1925. The Merkel Equation combines the sensible and latent heat transfer into an overall process based on enthalpy potential as the driving force.

Application of Cooling Towers for Free Cooling
SPX Cooling Technologies
The use of Marley towers in free cooling applications extends back at least 30 years, during which time Marley-manufactured crossflow, counterflow, induced draft, and forced draft towers were so applied.

Risk management methodologies for control of legionella in cooling towers Australian Institute of Refrigeration Air Conditioning
Cooling towers have been refined to be highly efficient at heat rejection. They are widely used throughout the world from tropical to temperate climates wherever a source of water is available. Installations range in size from units at shops, restaurants and offices to large power generating stations. As with all mechanical devices, cooling towers require routine servicing of the moving parts, regular cleaning and close monitoring if they are to operate satisfactorily. Regulatory authorities recognise that cooling towers, if not operated and maintained correctly, present a Legionnaires’ disease hazard. The risk of disease has been listed under five critical risk categories:

* Stagnant water
* Nutrient availability
* Poor water quality
* Deficiencies in the cooling water system
* Location and access of the cooling tower

A Universal Engineering Model For Cooling Towers
NTU
This paper presents a universal engineering model, which can be used to formulate both counterflow and crossflow cooling towers. By using fundamental laws of mass and energy balance, the effectiveness of heat exchange is approximated by a second order polynomial equation. Gauss-Newton and Levenberg-Marquardt methods are then used to determine the coefficients from manufactures data. Compared with the existing models, the new model has two main advantages: (1) As the engineering model is derived from engineering perspective, it involves fewer input variables and has better description of the cooling tower operation; (2) There is no iterative computation required, this feature is very important for online optimization of cooling tower performance. Although the model is simple, the results are very accurate. Application examples are given to compare the proposed model with commonly used models.

Improving Cooling Tower Performance for Sustainable Refrigeration
The Chartered Institution of Building Services Engineers
This paper describes the system advantages of rejecting low grade condenser heat through latent means both in capital and energy terms. It also describes how tower packings may be evaluated for optimum behaviour in terms of heat transfer achieved and energy wasted. Experimental investigations are described which have led to new correlation techniques allowing packings to be modelled mathematically. The techniques described will allow building services engineers to analyse and design more sustainable systems for heat rejection.

Cooling tower Wastewater Management and Disposal
Dept of Water, Wertern Australia
This note provides a general guide on issues of environmental concern and offers potential solutions based on professional judgment and precedent.
This note applies to the management and discharge of cooling-tower wastewater from refrigerated or evaporative air-conditioning systems. It has particular relevance to office cooling-tower systems.

Best practice guidelines for cooling towers in commercial buildings
Sydney water
This guideline is mean for commercial building. However, the guideline presented here may be adopted in Oil and gas.
In implementing these Guidelines it would be advisable to consult with your maintenance personnel and water treatment specialist to help ensure a co-ordinated approach to achieving optimum savings in the water used in your cooling towers.

If you aware of any others, share with us here (click).

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Understand Meaning of "Pump Head"

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This is another simple and useful article shared by Larry Bachus (Feb 2008). Understanding of "pump head" would leads you converse easily with pump manufacturer.

Cheat Sheets: 2.31 or .433?
The Numbers May Be Different, But the Result Is the Same

No, it’s not a new song by the band Chicago. (Remember “25 or 6 2 4”?) These numbers are the conversion factors that relate pump head with pressure. As established in my previous column (“Pump Secrets Lost in Time,” Jan. ’08), head is a measure of energy. The units of energy are expressed in feet or meters. Pressure is a force applied to a unit of area, such as a pound of force applied to a square inch of area, or PSI. For water, we can say that had in feet divided by 2.31 is pressure in PSI, and pressure in PSI multiplied by 2.31 is head in feet. Stated mathematically:

Head (ft.)/2.31 = PSI and PSI x 2.31 = Head (feet)

It is equally correct to convert head into pressure and vice versa with the factor .433. Head in feet multiplied by .433 is pressure in PSI, and pressure divided by .433 is head in feet. Mathematically:

Head (feet) x .433 = PSI and PSI/.433 = Head (feet)

Math-challenged people may find it easier to divide by 2.31, rather than multiplying by a decimal, but the result is the same.

Where does the conversion number 2.31 come from? A cubic foot of ambient water weighs 62.4 pounds. A square foot of area contains 144 in2. If we divide one by the other, we get our conversion number 2.31 (i.e., 144/62.4 = 2.31) (Figure 1). Remember, some people prefer .433, the other conversion: 62.4/144 = .433. Here is another way to understand the same concept. If I poured one pound of ambient water into a long, narrow receptacle that measures one in2, the water would fill that receptacle to a height of 2.31 feet (See above figure).

Here is a practical example. The waterfall is at the eastern escarpment in South Africa. Some Tarzan movies were filmed here. Tarzan would jump off the waterfall to the river below and wrestle a rubber crocodile, while Cheeta the chimp danced and did back flips on the shore.

These falls drop 213 feet to the river below. What is the pressure of the falling water column as it strikes the surface of the river below?

213 feet/2.31 = 92 PSI or 213 feet x .433 = 92 PSI.

The falling water column strikes the river down below at 92 PSI. (You’d have to make a small correction for the acceleration and the wind resistance, so it isn’t precisely 92 PSI.)

With pumps, a standard water pump developing 70 feet of head would exhibit 30 PSI of differential pressure across the pump (i.e., 70 feet/2.31 = 30 PSI.

The term “head” is the constant for the pump manufacturer. A pump that develops or generates 70 feet of head can elevate any liquid 70 feet. If you think of the pump’s performance in head, it doesn’t matter what the liquid is. It could be any liquid from liquid propane to liquid mercury.

For ambient water, divide feet of head by 2.31 (or multiply by .433). If the liquid is not water, then you must factor the specific gravity of the liquid.

Specific gravity is the relative density of a liquid compared to water. We say that ambient water (at sea level) has a specific gravity of 1.0. Another liquid might be denser (heavier) or less dense than water. For example, sulfuric acid is twice as dense as ambient water; it has a specific gravity of 2.0.

Returning to the pump that develops 70 feet of head — if pumping sulfuric acid, the pump will exhibit 60 PSI across the pump (i.e., 70 feet/2.31 x sp. gr.(2) = 60 PSI).

Gasoline has a specific gravity of 0.75. This means an equal volume of gasoline would weigh ¾ or 75 percent the weight of water.

Returning to that same pump that develops 70 feet of head — if gasoline is the liquid, the differential pressure across the pump will be 23 PSI (i.e., 70 feet/2.31 x sp. gr. (0.75) = 23 PSI.

It’s easier in the metric system.

Meters of head x 10 = kilopascals of pressure.

The maintenance engineer or mechanic must understand head to converse with the pump manufacturer. The maintenance engineer must also know how to relate head (on the pump curve) to the pressure in the pipes.

Rip these pages, copy them and share them, or store this edition of Flow Control in a safe place for future reference. This is your CHEAT SHEET of useful pump information.

Larry Bachus (a.k.a. "Pump Guy")
Larry Bachus, founder of pump services firm Bachus Company Inc., is a regular contributor to Flow Control magazine. He is a pump consultant, lecturer, and inventor based in Nashville, Tenn. Mr. Bachus is a member of ASME and lectures in both English and Spanish. He can be reached at larry@bachusinc.com or 615 361-7295.

Related Post

• Pump Pressure Versus Head
• Why Centrifugal pump NPSH required increases with flow ?
• Tips for Centrifugal Pump
• Rule-of-thumb For Minimum Flow Recycle
• Consider energy saving by optimizing the pump control
• Do not under estimate pump energy cost and FREE Optimization tool for better Life cycle cost
• Hydraulic Design Of Liquid with Pump Circuit - A revision kit...
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Why Redundant NRV in Series within a Line ?

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One of my blog reader, DV post a simple question to me recently.

"There are two non return valves (NRVs) in an oil transfer line. 1st NRV on transfer pump discharge and 2nd NRV located some distance away before it tie in to another oil pipeline. Why two NRVs in a single line ?"

Quick response on this question is

NRV internal e.g. flapper, piston, etc is prompt to failed and damage cause by corrosion, erosion, etc. Thus, to increase reliability and reduce probability of reverse flow, redundant NRV is provided on same lime. This is pretty inline with API Std 521 recommendation. In additional, API Std 521 allow credit (reduction) on flowrate in back flow and minimize relief load. This commonly apply in compressor discharge Non-Return Valves (NRV).

Thus provision of additional NRV :

• Redundant NRV increases reliability and reduce probability of back flow
• Credit on flow reduction in back flow

Do you aware of any other purpose ? Share with us (click here).

Will discuss further of "Potential Problem associate with Redundant NRV in Series within a Line"

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• Why Centrifugal pump NPSH required increases with flow ?
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• Restrcition Orifice Used in Many Applications in Different Manners

Pump Pressure Versus Head

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I found this article written by Larry Bachus recently (Jan 2008) and find it is pretty simple but useful. It gives us a simple idea the difference between pump pressure and head.

Cheat Sheets: Pump Secrets Lost in Time
The Relationship Between Pressure & Head

Early in my career I worked in a steel mill. One day, my boss gave me a purchase chit, put me in a company truck, and told me to go into town and buy a pump for cooling water. He said to get a pump that develops 30 PSI.

At the pump shop, the clerk showed me a pump that develops 70-ft of head. I thought, “Who cares about 70-ft? I need 30 PSI.” I didn’t know the relationship between head and pressure. I’m not alone.

Pump industry people use the term “head”;

maintenance people use the term “pressure”.

What is head? What is pressure?

In simple terms, they are the same. The terms head and pressure are interchanged in conversations regarding pumps. But they are different, with different definitions.

Head is a measure of energy. The units of energy are expressed in feet or meters. The term pressure is a force applied to a unit of area, such as pounds per square inch [lbs/in2 (or PSI)], or kilograms per square centimeter (kgs/cm2).

The term “head” goes back to the beginning of civilization. Ancient civil engineers built giant water troughs (aqueducts) to carry drinking water from mountain streams and lakes, down into the cities below. The water would spout forth at a public fountain. Housewives and servants would carry the water home.

The water’s flow was measured in barrels and jugs. The water’s force (pressure) was a function of gravity, the elevation differential from the source (the mountain lake) to the fountain (along with the water’s velocity and resistance losses).

This force was measured in units or lengths of elevation. Ancient engineers understood the hydraulic laws that govern today’s modern pumps.

Early pump builders (the Archimedes Screw, the Egyptian Noria, the Persian waterwheel) adopted the term head to express the elevation and force of water. And 3,000 years later, today’s modern pump manufacturers rate their pumps in feet or meters of head.

The term head is the constant for the pump manufacturer. And because head is the measure of energy, a pump that generates 90-ft. of head can elevate any liquid to 90-ft. above the surface level of the liquid’s source. As long as I use the word head, it does not matter what the liquid is.

You see, a pump manufacturer will ship some pumps to a distributor. The distributor will sell the pumps to the end-user. The distributor might sell a specific model of a pump to a dairy, a fuel storage company, a paint manufacturer, a chemical plant, and a pharmaceutical company. The pump manufacturer doesn’t know the ultimate service of his pumps. He only knows that his pumps will develop 90-feet of head. His pumps will elevate chocolate milk, kerosene, red paint, acid, caustic soda, and cough syrup 90 feet. The pressures will be different for each liquid, but the heads will all be 90 feet.

For this reason, the engineer, operator, and mechanic must understand head to converse with the pump manufacturer, and to interpret pump and system curves. This is also the reason that too many pumps are sold without adequate gauges. Not understanding head, pressure, and pump curves is the reason too many pumps suffer mysterious vibrations, with rapid bearing and seal failure. We’ll bring head and pressure together in a future cheat sheet.

You now know what Archimedes and Pi (π) had figured out 3,000 years ago. Rip these pages, copy and share them, or store this edition of Flow Control in a safe place for future reference. This is your CHEAT SHEET of useful pump information.

Larry Bachus (a.k.a. "Pump Guy")

Larry Bachus, founder of pump services firm Bachus Company Inc., is a regular contributor to Flow Control magazine. He is a pump consultant, lecturer, and inventor based in Nashville, Tenn. Mr. Bachus is a member of ASME and lectures in both English and Spanish. He can be reached at larry@bachusinc.com or 615 361-7295.

Related Post

• Why Centrifugal pump NPSH required increases with flow ?
• Tips for Centrifugal Pump
• Rule-of-thumb For Minimum Flow Recycle
• Consider energy saving by optimizing the pump control
• Do not under estimate pump energy cost and FREE Optimization tool for better Life cycle cost
• Restrcition Orifice Used in Many Applications in Different Manners
• Hydraulic Design Of Liquid with Pump Circuit - A revision kit...
• Hydraulic Design of Liquid Piping Systems - A revision kit...

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Why Two Rupture Discs in Series ?

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Rupture disc has been used in many application in protecting pressure containing part from overpressure. In some event as discussed in "Tube Rupture : Pressure Relief Valve (PSV) or Rupture Disk (RD) ?" and "Protective Measures against FIRE other than Pressure Relief Device (PRD)" rupture disc (RD) is preferred as compare to pressure relief valve. Nevertheless, in some application, designer would provide two (2) RDs in series with pressure gauge (PG) and pressure transmitter (PT) with high pressure alarm (PAH) and low pressure alarm (LAH) in between the ruptured discs.

What is the purpose of provides these kind of arrangement ?

Two (2) rupture discs (RDs) in series
The reasoning for 2 RDs in series is rather simple. Although RD is preferred in some event, however RD is prompt to fail prematurely and unintended due to corrosion, vibration, transient surge, fatigue, etc. ? In some critical services , designer would provide another RD in series in order to avoid inventory lose or flare gas backflow (during blowdown) to process system.

Pressure Gauge & Pressure Transmitter (with LAH) in between RDs
In the event of RD (1st RD expose to process fluid) is failed or leaked, pressure in between RDs will build quickly. Operator will be able to identify the failed RD during routine checking. Pressure transmitter (with high pressure alarm) would be triggered and initiate alarm in the control panel to alert operator.

Pressure Transmitter (with LAL) in between RDs
In some application, designer may provide low pressure alarm. The main reason is to identify the failure of second RD which expose to flare header. During normal operation, the section between RDs will be pressurized with inert gas to a preset pressure (i.e. 2 barg). In the event the RD (RD facing flare header) failed / leaked, the pressure in the section will lose quickly to flare header and low pressure alarm would be triggered to alert operator the failure of 2nd RD.

Thanks to Steven who has partly (80%) answered above queries.

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Some Comments on Providing External Insulation as Protective Measure against FIRE

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Providing external insulation is one of the effective way to minimize the impact of the fire attack. This is pretty inline with API Std 521 recommendation.

However, there are several problems associated with insulation :

i) The insulation external protection layer shall be able to resist high temperature ( > 900 degC per API) and sustain fire for 2 hours. Involvement of safety engineer and mechanical engineer during early design stage shall be considered for safety and availability compliance.

ii) Corrosion under insulation is a complicated and tricky stuff. It is hard to avoid and corrosion protection layer shall be provided as minimum. As the corrosion protective layer will be covered by insulation layer, any damage to the corrosion protective layer and present of corrosion, operator may not aware of the occurrence of corrosion by visual inspection. A sophisticated assessment and inspection method is required. In the event, corrosion occur, there is potential of the corrosion material accumulated and damage the insulation layer without knowing. Corrosion under insulation may defect the purpose of insulation.

iii) The protection layer and insulation is subject to the risk of external mechanical damage cause by impact of fire water jet, mechanical work during maintenance, inspection, site modification works, etc. Once the layer is damage, it is very difficult to repair and maintain similar level of protection as per original requirement such as fire resistance for 2 hours at > 900 degC.

iv) Galvanic corrosion and mercury embrittlement of aluminum blind rivets may occur (in suitable environment) if aluminum cover sheet is used. Consider sheeting made of galvanized steel or stainless steel and be fastened with stainless steel or galvanized self-tapping screws, not with aluminum blind rivets.

v) Whenever consider use of insulation layer, the fire scenario shall be assessed carefully if jet fire is potential scenario. Jet fire would leads to higher heat flux, jet momentum may mechanically damage the insulation layer, etc.

Other protection measures against FIRE (discussed earlier) shall be considered concurrence with application of external insulation.

Related Post

• Protective Measures against FIRE other than Pressure Relief Device (PRD)
• Design Temperature (Td) versus Maximum Allowable Working Temperature (MAWT)
• PSV for Shell-and-Tube HEX Tube Side Overpressure Protection against External Fire Attack ?
• Steam in FIRE...
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Transient & Slugging

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Earlier posts " Slugging & Slugcatcher" and "Liquid Slug Stabiliser - Another type of slugcatcher" have discussed briefly about slugging, type of slug and type of slugcatcher. The following article is rather detailed discussion related slug...

What type operations caused slugging ?
What are the problem of slug ?
How slug is formed ?
Procedure in predicting slug ?
What are the slugging criteria ?
What is slug frequency and load ?
How composition and geometry affect slug ?
How to mitigate slugging ?

TRANSIENT & SLUGGING
(Click here to read more)

If you are flow assurance engineer, slugcather design engineer, slugcatcher operation engineer, etc. i am strongly encourage you to read this article.

Thanks to Jprocess for sharing this article.

If you have any good article, please share with us here.

Related Post

• Liquid Slug Stabiliser - Another type of slugcatcher
• Slugging & Slugcatcher

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