Showing posts with label Cooling towers. Show all posts

Wednesday, 27 November 2013

Cooling Tower:TYPED BY METHOD OF HEAT TRANSFER

TYPED BY METHOD OF HEAT TRANSFER

All of the cooling towers described here are evaporative type towers, in that they derive their primary cooling effect from the evaporation that takes place when air and water are brought into the direct contact. At the other end os the spectrum is the Dry tower, where by full utilization of dry surface coil sections, no direct contact (and no evaporation) occurs between air and water. Hence sensible heat transfer cools the water totally.
IN between these extremes are the plume abatement and water conservation towers, wherein progressively greater portions of dry surface coil sections are introduced into the overall heat transfer system to alleviate specific problems or to accomplish specific requirements

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Cooling Tower:TYPES BY SHAPE

TYPES BY SHAPE

There are two different types:
RECTILINEAR:
These towers are constructed in cellular fashion, increasing linearly to the length and numbers of cells necessary to accomplish a special thermal performance.

ROUND MECHANICAL DRAFT:

Are towers as the name implies, are essentially round in plan configuration, with fans clustered as close practicable around the center point of the tower. Multi-faceted towers, such as the octagonal mechanical draft (OMD) also fall in the general classification of “round” towers.

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Cooling Tower:SPRAY – FILLED

SPRAY – FILLED

This kind of towers has not a heat transfer surface, depending only upon the water break-up af-forded by the distribution system to promote maximum water-to-air

characterization by construction

we can see two different kinds of cooling towers by construction:

Field-erected
Factory-assembled

Field-erected:
The field-erected cooling towers are those on which the primary construction activity takes place at the site of ultimate use. All large towers, and many of the smaller towers, are prefabricated, piece-market and shipped to the site for the cooling towers manufacturer usually provides final assembly.
FACTORY-ASSEMBLED:
The factory-assembled cooling towers undergo virtually complete assembly at their point of manufacture, whereupon there are shipped to the site in as a few sections as mode of transportation will permit.

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Cooling Tower:CHARACTERIZATION BY AIR FLOW

CHARACTERIZATION BY AIR FLOW
The cooling towers by the relative flow are divided in several groups :
COUNTERFLOW:
IN the counterflow towers, the air moves vertically upward through the fill, counter to the downward fall of water. Because of the need for extended intake and discharge plenums; the use of high pressure spray systems; and the typically higher air pressure losses, some of the smaller counter flow towers are physically higher; require more pump head; and utilize more fan power than their cross flow counterparts. In a larger counter flow towers, however, the us of low pressure grativity-related distribution systems, plus the availability of generous intake areas and plenum spaces for the air management, is tending to equalize, or even reverse, this situation. The enclosed nature of a counterflow tower also restricts exposure of the water to direct sunlight, thereby retarding the growth of the algae.

CROSSFLOW:
The crossflow towers have a fill configuration throught, which the air flows horizontally, across the downward fall of water. Water to be cooled is delivered to hot water inlet basins located atop the fill areas, and is distributed to the fill by gravity throught metering orifices in the floor of those basins.

The crossflow towers can be divided in:

DOUBLE-FLOW:

In this kind of towers the fan is inducting air through two inlets and across two banks of fill.

SINGLE-FLOW:
This kind of towers only has one air inlet and one fill bank, the remaining three sides of the towers being cased. Single-flow towers are customarily used in locations where are unrestricted air path to the tower is available from only one direction.

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Cooling Tower:HYBRID DRAFT

HYBRID DRAFT
Tgey are equiped with mechanical draft fans to augment airflow. Consequenly, they are also referred to us fan-assisted natural draft towers. The intent of their desing is to minimize the horsepower required for the air movement, but to do so with the least possible stack cost impact. Properly desogned the fans may need to be operated only during pereiods ao high ambientsand peak loads.

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Cooling Tower:MECHANICAL DRAFT

MECHANICAL DRAFT
Mechanical draft towers uses fans (one or more) to move large quantities of air through the tower. They are two different classes:

Forced draft cooling towers
Induced draft cooling towers

The air flow in either class may be crossflow or counterflow with respect to the falling water. Crossflow indicates that the airflow is horizontal in the filled portion of the tower while counterflow means the air flow is in the opposite direction of the falling water.
The counterflow tower occupies less floor space than a crossflow tower but is taller for a given capacity. The principle advantages of the crossflow tower are the low pressure drop in relation to its capacity and lower fan power requirement leading to lower energy costs.
All mechanical towers must be located so that the discharge air diffuses freely without recirculation through the tower, and so that air intakes are not restricted. Cooling towers should be located as near as possible to the refrigeration systems they serve, but should never be located below them so as to allow the condenser water to drain out of the system through the tower basin when the system is shut down.
FORCED DRAFT
The forced draft tower, shown in the picture, has the fan, basin, and piping located within the tower structure. In this model, the fan is located at the base. There are no louvered exterior walls. Instead, the structural steel or wood framing is covered with paneling made of aluminum, galvanized steel, or asbestos cement boards.

During operation, the fan forces air at a low velocity horizontally through the packing and then vertically against the downward flow of the water that occurs on either side of the fan. The drift eliminators located at the top of the tower remove water entrained in the air. Vibration and noise are minimal since the rotating equipment is built on a solid foundation. The fans handle mostly dry air, greatly reducing erosion and water condensation problems.
INDUCED DRAFT
The induced draft tower show in the following picture has one or more fans, located at the top of the tower, that draw air upwards against the downward flow of water passing around the wooden decking or packing. Since the airflow is counter to the water flow, the coolest water at the bottom is in contact with the driest air while the warmest water at the top is in contact with the moist air, resulting in increased heat transfer efficiency.

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Cooling Tower: ATMOSPHERIC

ATMOSPHERIC
The atmospheric cooling towers utilize no mechanical fan to create air flow through the tower, its air is derived from a natural induction flow provided by a pressure spray.
We can see it in the following picture:

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TYPES OF COOLING TOWERS

TYPES OF COOLING TOWERS
Cooling towers are designed and manufactured in several types:

ATMOSPHERIC
MECHANICAL DRAFT

a. FORCED DRAFT
b. INDUCED DRAFT

HYBRID DRAFT
TYPED BY AIR FLOW

a. COUNTERFLOW
b. CROSSFLOW
a.1 DOUBLE-FLOW
a.2 SINGLE-FLOW
c. SPRAY-FILLED

TYPED BY CONSTRUCTION

a. FIELD-ERECTED
b. FACTORY-ASSEMBLED

TYPED BY SHAPE

a. RECTILINEAR
b. ROUND MECHANICAL DRAFT (RMD)

TYPED BY METHOD OF HEAT TRANSFER

a. EVAPORATIVE
b. DRY TOWER
c. PLUME ABATEMENT
d. WATER CONSERVATION

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COOLING TOWERS

COOLING TOWERS

The machines and processes of industry, as well as those devoted to human comfort and well being generated tremendous amounts of heat, which must be continuously, dissipated if those machines and processes are to continue to operate efficiency. Although this heat is usually transferred to a cool, flowing volume of water, final rejection is always to the atmosphere and, invariably, is accomplished by some form of heat exchanger.
The natural process of evaporation makes them very effective heat transfer mediums, although somewhat inefficient due to their limited surface area and their total dependence upon random winds.

Thursday, 21 November 2013

Thermic Fluid Heater

Thermic Fluid Heater

In recent times, thermic fluid heaters have found wide application for indirect process heating. Employing petroleum - based fluids as the heat transfer medium, these heaters provide constantly maintainable temperatures for the user equipment. The combustion system comprises of a fixed grate with mechanical draft arrangements.

The modern oil fired thermic fluid heater consists of a double coil, three pass construction and fitted with modulated pressure jet system. The thermic fluid, which acts as a heat carrier, is heated up in the heater and circulated through the user equipment. There it transfers heat for the process through a heat exchanger and the fluid is then returned to the heater. The flow of thermic fluid at the user end is controlled by a pneumatically operated control valve, based on the operating temperature. The heater operates on low or high fire depending on the return oil temperature, which varies with the system load

The advantages of these heaters are:

Closed cycle operation with minimum losses as compared to steam boilers.
Non-Pressurized system operation even for temperatures around 250 0c as against 40 kg/cm2 steam pressure requirement in a similar steam system.
Automatic control settings, which offer operational flexibility.
Good thermal efficiencies as losses due to blow down, condensate drain and flash steam do not exist in a thermic fluid heater system.

The overall economics of the thermic fluid heater will depend upon the specific application and reference basis. Coal fired thermic fluid heaters with a thermal efficiency range of 55-65% may compare favorably with most boilers. Incorporation of heat recovery devices in the flue gas path enhances the thermal efficiency levels further.

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Packaged Boiler

Packaged Boiler

The packaged boiler is so called because it comes as a complete package. Once delivered to site, it requires only the steam, water pipe work, fuel supply and electrical connections to be made for it to become operational. Package boilers are generally of shell type with fire tube design so as to achieve high heat transfer rates by both radiation and convection.

The features of package boilers are:

Small combustion space and high heat release rate resulting in faster evaporation.
Large number of small diameter tubes leading to good convective heat transfer.
Forced or induced draft systems resulting in good combustion efficiency.
Number of passes resulting in better overall heat transfer.
Higher thermal efficiency levels compared with other boilers.

These boilers are classified based on the number of passes - the number of times the hot combustion gases pass through the boiler. The combustion chamber is taken, as the first pass after which there may be one, two or three sets of fire-tubes. The most common boiler of this class is a three-pass unit with two sets of fire-tubes and with the exhaust gases exiting through the rear of the boiler.

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Water Tube Boiler

Water Tube Boiler

In water tube boiler, boiler feed water flows through the tubes and enters the boiler drum. The circulated water is heated by the combustion gases and converted into steam at the vapour space in the drum. These boilers are selected when the steam demand as well as steam pressure requirements are high as in the case of process cum power boiler / power boilers.

Most modern water boiler tube designs are within the capacity range 4,500 – 120,000 kg/hour of steam, at very high pressures. Many water tube boilers nowadays are of “packaged” construction if oil and /or gas are to be used as fuel. Solid fuel fired water tube designs are available but packaged designs are less common.

The features of water tube boilers are:

Forced, induced and balanced draft provisions help to improve combustion efficiency.
Less tolerance for water quality calls for water treatment plant.
Higher thermal efficiency levels are possible

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What type of boiler do you need?

When choosing between boilers there are several things to consider. The size of your boiler, the type, construction and energy efficiency will all have an impact on your home and your energy bills. Take some time to consider your options and think carefully about which boiler to choose.

Conventional boilers
Conventional boilers use a storage tank to supply hot water. The water is heated via cast iron heat exchangers and combination boilers can supply gallons of hot water at one time. Once the stored hot water runs out, there may be a delay in supply as the tank refills.
Conventional boilers tend to require more space than combination boilers as the hot water cylinder requires connection with a cold water storage tank that will typically be placed in the loft. This also means that installation is often more complicated than with a combination boiler.
Older models of conventional boilers tended to be less energy efficient, but advances have been made and newer models can be adjusted to match the specific heating requirements of your home.
British Gas offer a range of conventional boilers including compact systems that can easily be fitted into most modern kitchens.

Combination boilers
Combination boilers, or combi boilers, supply water directly from the mains without the need for a storage tank. As a result, combination boilers supply hot water on demand in unlimited supply.
Combination boilers are ideal for smaller properties where space is at a premium.
Combi boilers also provide water at mains pressure, meaning you can enjoy a strong, hot shower without the need for an additional shower pump.
Combination boilers from British Gas include condensing technology and an ECO mode, both of which improve your control over water heating by maintaining boiler temperature whilst in standby mode.

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Boiler

A boiler is a closed vessel in which water or other fluid is heated. The fluid does not necessarily boil. The heated or vaporized fluid exits the boiler for use in various processes or heating applications, including central heating, boiler-based power generation, cooking, and sanitation.

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Disc mill type Pulverizer

Disc mill type Pulverizer- Economic pulverizing of plastic granules
Our pulverizing systems, are high capacity systems for the profitable pulverizing of thermoplastic and other heat sensitive materials such as LDPE, LLDPE, MDPE and HDPE, as well as other heat sensitive thermoplastics such as PP and EVA without the added cooling of nitrogen.

Our pulverizing systems produce quality powders with excellent flow properties and bulk densities nd are mainly used for the following applications:

    Pulverization of rigid PVC (pipe and profile granules)
    Pulverization of PE for Rotomolding
    Pulverization of PE for textile and metal coating
    Pulverization of PP for fiber manufacture
    Pulverization of compounds for floor coverings

This Pulverize machine is simple, clearly arranged and operates with a further developed screening machine. The advantages for the customer are obvious:

    Quality powders with best possible flow properties and high bulk density
    High throughput capacity at low specific power consumption
    Fully automatic, continuous operation

Low demands on operating personnel

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Concept of Rotational Moulding with Pulverizing Machine

Concept of Rotational Moulding with Pulverizing Machine

Rotational Moulding needs resin in pulverized form. The particle size, shape and particle size distribution is measure of powder quality. Powder quality plays a very important role in rotational moulding.

Following are the resultant effects of the good quality powder:

    Optimization of the charge weight to meet rising competition
    Improved finish an color of the product
    Reduced fusion time
    Multi layered and foamed tanks

Realizing the extraordinary needs of the rotational molders engineers at N.A. Group of Companies set out to expand the next generation pulveriser. To attain the above objective pulveriser must have following features.

    Ability and control to give uniform and consistent Powder Quality
    Power required should be low
    Cooling of grinding element must be sufficient and effective
    High out put
    Minimum down time
    Ability to run the machine un attended
    All system protections so that down time is Low

Easy to clean , user friendly operation

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The Plastic Granulator

The Plastic Granulator

The Plastic Granulator is the most universal type of pulverizer used with plastic recycling. It is capable of turning jugs, large bottles, and other plastic products into flakes, which are referred to as granules. These granules are then sold to manufacturers in order to be remolded into new products.

Plastic Granulator is basically a large electric motor with a rotor. The motor rotates the rotor, which contains cutting blades. The motor, the rotor and the blades are all located inside a closed chamber in which the plastic is positioned. The blades and the chambers of plastic granulators are accessible in different sizes and shapes with the purpose of assemble different needs.

There is also a screen situated inside the chamber of plastic granulator. This screen sifts the plastic in order to ensure all of the parts are small enough to be reprocessed, which normally ranges from .125 to .375 inches. If any parts that are too large to in shape through the screen are processed once more within the plastic granulator.

The efficiency of a plastic granulator is based upon how a large amount plastic it can shred in one hour, which is referred to as its pounds per hour rating. For engineering recycling purposes, the plastic granulator needs to be very large to process considerable amounts of plastic. There are, however, smaller plastic granulators available for home utilization. No matter the size, Plastic Granulators can be dangerous. Therefore, it is essential to always follow the manufacturer's instructions when using a plastic granulator.

A plastic granulator also must be kept clean to remain capable. Generally, the screen situated inside the chamber of plastic granulator is cleaned out after each large processing. Otherwise, pieces of plastic can get stuck in the screening and stop other granules from falling through. The blades of the plastic granulator also require being wiped dirt free and oiled to maintain plastic granulator running efficiently.

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Advantages of Plastic Pulveriser

Advantages of Plastic Pulveriser or Pulverizer in engineering reprocessing are as follows:

    Low residence time means lower thermal stress on the process material
    Heavy-duty construction for longevity
    Ease of maintenance
    Ease of operation
    Full inventory of replacement parts
    Can cool the processing of heat- sensitivity materials by water cycle system
    High through put capabilities
    Cost effective operation
    Low specific power consumption
    Powder quality according to specification

The models of pulverizing machine ensure the production of pulverized material from plastic granules for the manufacturing of high quality final products. Our Plastic pulverizer can pulverize LDPE, LLDPE, HDPE and various thermoplastic materials and can offer to develop other kinds of pulverize for different materials on request.

Pulverizers are available in various configurations like single mill, double mill, horizontals mill with various designs, sizes and shapes of pulverizer blades.

The Pulverizer constitutes of high quality, maintenance-free, efficient components, like the Pulverizer Blade. The Pulverizers have very special designs and are being approved by our in-house quality control and testing departments after going through rigorous tests and routine check-up procedures.

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Plastic Pulverizer

Plastic Pulverizer
In plastic reprocessing after the types of plastic separated is a Mechanical processing to run the plastic through the Pulverizer. Pulverizer or Pulveriser crushes the plastic into tiny shreds or granules. Plastic pulverizer is the particular equipment for recycling disused insignificant materials in producing and grinding heat-sensitivity plastic such as PVC.

Pulverizer includes high output units which can be equipped with automatic temperature control. The material to be pulverized is fed centrally between a fixed and a high speed rotating pulveriser disc with centrifugal effect carrying the material through the processing zone before being discharged from the machine pneumatically.

Several different types of pulverizer machines are used to smash down other materials, such as rock, glass, wood, metals, and cement. When it comes to plastic, the three primary types of pulverizers are granulators, shredders, and ring mills.

A granulator operates thousands of evenly spaced blades in order to shred or granule the plastic into finely pulverized objects. After it is pulverized, it can be melted and reformed.

A shredder is similar to a granulator in that it contains evenly spaced blades, though these blades cut the plastic into strips. Some cut both vertically and horizontally in order to produce square shaped plastic pieces.

A ring mill, on the other hand, has a large, steel rolling blade. This blade chops and grinds the plastic that is placed inside the roller. After it has been ground up to the desired size, it falls through the small holes located beneath the rolling blade.Fig shows Ring mill

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Wednesday, 27 November 2013

Cooling Tower:TYPED BY METHOD OF HEAT TRANSFER

Cooling Tower:TYPES BY SHAPE

Cooling Tower:SPRAY – FILLED

Cooling Tower:CHARACTERIZATION BY AIR FLOW

DOUBLE-FLOW:

Cooling Tower:HYBRID DRAFT

Cooling Tower:MECHANICAL DRAFT

Cooling Tower: ATMOSPHERIC

TYPES OF COOLING TOWERS

COOLING TOWERS

Thursday, 21 November 2013

Thermic Fluid Heater

Packaged Boiler

Water Tube Boiler

What type of boiler do you need?

Boiler

Disc mill type Pulverizer

Concept of Rotational Moulding with Pulverizing Machine

The Plastic Granulator

Advantages of Plastic Pulveriser

Plastic Pulverizer

Physics basic inventions and inventors

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