How a Multiport Valve Operates - Step by Step

How a Multiport Valve Operates

Step 1

There are five ports into and out of a typical multiport valve. Three are shown in this picture. The top left port, labeled "PUMP", brings unfiltered water in from the pump. The middle left port, labeled "RETURN", sends filtered water back to the pool. The middle right port, labeled "WASTE", sends water to an external drain hose.

Step 2

The other two ports control flow though the filter. This picture shows the valve as it is connected to the inside piping of the filter. At the bottom of the valve, a pipe port connects to the collection tubes (laterals) on the bottom of the filter. The area around the pipe on the bottom side of the valve directs water to the top of the filter. This picture shows water flow for a "FILTER" setting. Water will flow in the opposite direction with a "BACKWASH" setting. The next series of steps explains how each of the valve setting directs water though these ports. CAUTION. When selecting a valve setting, make sure that the pump has been TURNED OFF and always depress the handle before turning.

Step 3

FILTER. This is the normal setting for filtering your pool water and for regular vacuuming. Water from the pool is pumped into the "PUMP" port to the top of the filter. Contaminates are removed as the water makes it way to the bottom to be pushed back up through a central pipe to the "RETURN" port and back to the pool.

Step 4

BACKWASH. After a period of time, the contaminates start to clog the sand to the point where water flow is significantly diminished and the pressure gauge rises 8 to 10 psi above normal operation readings. To clean out the contaminates, you have to backwash the sand. In the backwash setting water flow is reversed though the filter. Water comes from the "PUMP" port down the filter through the central pipe, then back up through the sand to flow out the top exit of the filter and out the "WASTE" port to an external drain. As the water flows up though the sand, the sand is lifted about 7 inches above its normal height releasing the trapped contaminates to be purged out in the waste water.

Step 5

RINSE. After backwashing, the sand is loose and needs to be reset. Also any dirty water from backwashing has to be rinsed out of the filter to waste to prevent it from returning to the pool. With the valve in rinse mode, water is directed from the "PUMP" port to the top of the tank to compress the sand. As in the filter setting, the water flows down though the sand and back up though the central pipe but instead of going out the "RETURN" port to the pool, the water is diverted out the "WASTE" port.

Step 6

WASTE. This setting is used to bypass the filter when you want to vacuum the pool after an algae treatment or to lower the pool level. The water enters the valve though the "PUMP" port and exits though the "WASTE" port.

Step 7

CLOSED. This setting is used for shutting off all flow to the filter and pool. Water flow is stopped at the "PUMP" port.

Step 8

RECIRCULATE. This setting is used to bypass the filter during certain pool cleanups and chemical treatments when you don't want the water contaminating the sand. Water enters the valve through the "PUMP" port and exits back to the pool through the "RETURN" port.

Step 9

WINTER. Use this setting when you are closing down the pool for the winter. This will allow water to drain from the valve.

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Fire-tube and Water-tube Boilers

Fire-tube Boilers

In fire-tube boilers, combustion gases pass through the inside of the tubes with water surrounding the outside of the tubes. The advantages of a fire-tube boiler are its simple construction and less rigid water treatment requirements.

The disadvantages are the excessive weight-per-pound of steam generated, excessive time required to raise steam pressure because of the relatively large volume of water, and inability to respond quickly to load changes, again, due to the large water volume.

The most common fire-tube boilers used in facility heating applications are often referred to as ''scotch'' or ''scotch marine'' boilers, as this boiler type was commonly used for marine service because of its compact size (fire-box integral with boiler section).

The name "fire-tube" is very descriptive. The fire, or hot flue gases from the burner, is channeled through tubes ('''Figure 2''') that are surrounded by the fluid to be heated. The body of the boiler is the pressure vessel and contains the fluid. In most cases, this fluid is water that will be circulated for heating purposes or converted to steam for process use.

Fire-tube Boiler Gas Flow

Every set of tubes that the flue gas travels through, before it makes a turn, is considered a "pass." So, a three-pass boiler will have three sets of tubes with the stack outlet located on the rear of the boiler. A four-pass boiler will have four sets and the stack outlet at the front.

Fire-tube boilers are:

• Relatively inexpensive
• Easy to clean
• Compact in size
• Available in sizes from 600,000 btu/hr to 50,000,000 btu/hr
• Easy to replace tubes
• Well suited for space heating and industrial process applications

Disadvantages of fire-tube boilers include:

• Not suitable for high pressure applications 250 psig and above
• Limitation for high capacity steam generation

Water-tube Boilers

In a water-tube boiler ('''Figure 3'''), the water is inside the tubes and combustion gases pass around the outside of the tubes. The advantages of a water-tube boiler are a lower unit weight-per-pound of steam generated, less time required to raise steam pressure, a greater flexibility for responding to load changes, and a greater ability to operate at high rates of steam generation.

Water-tube Boiler

A water-tube design is the exact opposite of a fire-tube. Here, the water flows through the tubes and is encased in a furnace in which the burner fires. These tubes are connected to a steam drum and a mud drum. The water is heated and steam is produced in the upper drum.

Large steam users are better suited for the water-tube design. The industrial water-tube boiler typically produces steam or hot water primarily for industrial process applications, and is used less frequently for heating applications. The best gauge of which design to consider can be found in the duty in which the boiler is to perform.

Water-tube boilers:

Are available in sizes far greater than a fire-tube design, up to several million pounds-per-hour of steam Are able to handle higher pressures up to 5,000 psig Recover faster than their fire-tube cousin Have the ability to reach very high temperatures Disadvantages of the water-tube design include: High initial capital cost Cleaning is more difficult due to the design No commonality between tubes Physical size may be an issue

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Cyclone Separators Design Calculation

Cyclone Separators Design Calculation

Cyclone Separators: The most widely used type of dustcollection equipment is the cyclone, in which dust-laden gas enters a cylindrical or conical chamber tangentially at one or more points and leaves through a central opening. The dust particles, by virtue of their inertia, will tend to move toward the outside separator wall, from which they are led into a receiver. A cyclone is essentially a settling chamber in which gravitational acceleration is replaced by centrifugal acceleration. At operating conditions commonly employed, the centrifugal separating force or acceleration may range from 5 times gravity in very large diameter, low-resistance cyclones, to 2500 times gravity in very small, high-resistance units. The immediate entrance to a cyclone is usually rectangular.

Fields of Application: Within the range of their performance capabilities, cyclone collectors offer one of the least expensive means of dust collection from the standpoint of both investment and operation. Their major limitation is that unless very small units are used, their efficiency is low for collection of particles smaller than 5 mm. Although cyclones may be used to collect particles larger than 200 mm, gravity settling chambers or simple inertial separators (such as gas-reversal chambers) are usually satisfactory and less subject to abrasion. In special cases in which the dust is highly flocculated or high dust concentrations (over 230 g/m3, or 100 gr/ft3) are encountered, cyclones will remove dusts having small particle sizes. In certain instances efficiencies as high as 98 percent have been attained on dusts having ultimate particle sizes of 0.1 to 2.0 mm because of the

predominant effect of flocculation. Cyclones are used to remove both solids and liquids from gases and have been operated at temperatures as high as 1000°C and pressures as high as 50,700 kPa (500 atm).

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Steam Trap

Since the 1970’s with the introduction of “Energy Conservation” steam traps have been elevated in prominence as a good way to conserve energy in steam systems.

So what is a steam trap and how does it work?

Basically a steam trap is a HOLE. In the early days of steam systems a maintenance worker would every once in a while open a valve up to allow the condensate (water resulting from steam giving up its latent heat) to flow out of the piping system. Since steam will not penetrate water, if the water/condensate was allowed to build up in the piping system the water/condensate would cool the entire system down effectively shutting the steam systems heating abilities down.

Steam traps come in a variety of configurations today but in reality the basic functions of a steam trap over the years have not changed. The steam trap has three (3) main functions: Allow condensate to flow to a collection system: vent air and other gases to maintain steam temperature and reduce corrosion: prevent the escape of system steam. A steam trap must be able to distinguish steam from condensate and non-condensable gases, discharge the condensate, and close to prevent the loss of steam. Steam traps are divided into four types based on how they distinguish  steam from condensate. The float type trap will sense the density difference between steam and condensate, the thermostatic trap will sense the temperature drop between the condensate out of contact with the steam and the steam itself, the thermodynamic trap will sense the difference in velocity and therefore static pressure between water and flow through a restriction, and the fixed orifice trap does its job by allowing more water to discharge than steam.

The most common steam traps on today’s market are the Float and Thermostatic steam trap and the Inverted Bucket steam trap.

Float and Thermostatic traps are best used in MODULATING steam applications. In other words, where the need for varying steam loads are present within the steam system. A good example for the use for a Float and Thermostatic steam trap would be after a heat exchanger. The Float and Thermostatic steam trap consists of a ball type float attached to the steam traps outlet valve via a linkage and a thermostatic air vent. Air and non-condensable gases are vented out of the steam trap the air vent. The condensate entering the top of the steam trap is directed to the bottom of the steam traps bowl chamber. As the condensate level rises the linkage multiplies the ball float’s buoyancy force enough to slowly open the discharge valve enough for a discharge (condensate) rate equal to the incoming condensate flow. As system needs change so does the amount of condensate flowing through the trap.

Inverted Bucket traps are by far the most used steam trap. The system steam pushes condensate into the Inverted Bucket traps inlet passage. Air and non- condensable gases are vented through the top vent of the upside down bucket as the steam inside the bucket lifts the bucket closing the Inverted Bucket traps main discharge valve closed. As the steam sub-cools the steam is converted to condensate which fills the Inverted Bucket traps main chamber. As the chamber fills with condensate the volume of steam trapped under the upside down bucket is reduced to a point where the weight of the condensate forces the bucket to drop, opening the traps main discharge valve and the condensate is pushed through the valve by the entering steam pressure. This cycle is continuous regardless of any system load changes.

Thermostatic Steam traps by nature open and closes by means of a force developed by a temperature sensitive actuator. These actuators are usually bimetallic elements designed to “warp” open or closed based on usually a 180 degree temperature which would be below the saturation point of the steam. As the temperature drops within the steam trap the bimetallic actuator “warps” causing the outlet valve of the trap to open and remove the condensate. As the condensate is removed the incoming hot steam causes the actuator to “warp” back to a closed position.

Thermodynamic Steam traps work on the higher velocity of hot condensate or steam passing through a narrow gap, as contrasted with the lower velocity of cooler water. The entering steam is at a high enough velocity that it will force the steam traps disc/seat to a closed position. As the steam condenses the velocity of the steam is reduced causing the disc to lift and remove the condensate. As the condensate is removed the velocity of the steam is increased pushing the disc to a closed position.

These are the major player in the steam trap world. There are other types not covered in this article such as the Ball Float trap (works like a ball floating in your bathroom tub) as the condensate level drops so does the ball until it closes the “drain” off and the fixed orifice trap which brings us back to the “HOLE”.

Needless to say the without “working” steam traps a steam system can be a major energy hog causing extremely high costs to your steam plant along with loss in production efficiency. Check the steam traps regularly for proper function. Always check with a knowledgeable person for you steam trap needs as they should be qualified to make proper decisions not only on the sizing of a steam trap but the best type of trap for your needs.

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Strainers

Strainers are extensively used to trap foreign materials from different major rotary equipments mainly like pumps, compressors, fans, blowers etc or it may be used for protection of major instruments like meters, valves, and seals.

These are mainly neglected piece of equipment which are mainly important not only for protection but are MUST for many services and many chemical processes can not run without them. Still we do not focus on use of suitable design of these strainers.

Its a closed housing with cleanable screen element designed to remove & capture foreign particles.

Strainers are called strainers because they are used to strain or filter out debris / particles from liquid streams. They basically have one housing and one filter element nothing more than this. The discharge port is usually the intermittent outlet from it.

The main function of these strainers is to capture all particles above design specs reliably & in an uninterrupted manner with very little maintenance ans spare parts.

Currently the wedge wire construction of filter screen is very effective for all strainer applications. The advantage of wedge wire usage in any filter application is that it is non-clogging in nature as it is hard steel mesh of V-Shape in place of cloth and hence there is no pores choking during any sticky or slimy application.

Now the salient feature of a good strainer is that

1. It should have sufficient operation time before choking or clogging. Use wedge wire mesh for easy online cleaning.
2. Easily back washable. Wedge wire system can be easily washed online (in place with just one back flow). In case of cloth etc it has to be opened and closed after manual cleaning. So it actually becomes CIP filter easily.
3. It should pose minimum pressure drop in the system which is possible with wedge wire very easily.
4. long life span.
5. Wedge wire based Duplex system can be a very good option for continuous operation in non acidic media.
6. The only disadvantage of wedge wire is that currently we don't have any option to have it in nonmetallic MOC. I mean if nonmetallic MOC is required wedge wire is not possible today.

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AIR FLOW DRIER

■ The air flow drier is also called as momentary drier. From 1960s it is applied at pharmaceutical industry. At the beginning of thundation，we began to choose the newest technology both at home and abroad and provide complete equipment with high quality and cheap price to pharmaceutical industry, chemical industry, foodstuff industry and so on. For many years, it has developed 4 series through unceasing improvement and raising:Q series: basic type QG series: fan and distributor type FG series: tail air circle type JG series: reinforce type.

■ The drying strength is large and investment of equipment is saving: the treating amount of pneumatic drier is the largest. The evaporated moisture capacity of equipment manufactured by we will 50-150kg/hr.

The volume of equipment is small and the investment is saving. The advantage can not be compared from other drying equipment.The automatic content is high and the quality of product is good: the raw material to be dried is inside the pipe. The dry time is short(only 0.5-2 seconds).

So that the automatic can be realized. The raw material can not contact with outer substances. So the pollution is small and the quality of product is good.

■ The equipment will be supplied completely and the heat source can be chosen freely: the pneumatic drier will be supplied completely. The basic type consists of filter, heater, feeder, drying pipe, fan and cyclone separator. Customer can install duster and other auxiliary equipment in accordance with practical conditions. On the choice of heating way, pneumatic drier has wide suitability. Customer can choose steam, electricity and air-heated furnace to heat in accordance practical conditions. Meanwhile it should be chosen in accordance with the temperature of raw material to be resisted(or temperature of hot air):if 150℃, choose steam to heat; if <200℃, electric or steam and electric as supplement or heat conduct oil); if ~300℃,coal air-heated furnace; if <600℃, oil air-heated furnace.

■ The damp raw material through conveyer and heated fresh air enter into the drier at the same time. They are mixed fully. Because the area of heat exchange is large, the purpose of evaporation and dry can be realized in a short time. The dried finished product is discharged from cyclone separator. Small parts of powder dust can be recovered and used through cyclone separator or bag duster. Model Q pneumatic drier is operated at negative pressure. The raw material does not pass through fan. Model QG pneumatic drier is operated at positive pressure. The raw material passes though fan with the effect of crushing. Model FG pneumatic drier is tail air circle type. Model JG pneumatic drier is a reinforced type. It integrates flash dry and pneumatic dry in the one body and is also a newest style drier designed and manufactured by we as customer request.

■ Air steam drier is quick, continuous and momentary drying equipment having larger in batch and high in heat efficiency. Even though it can suitable for different raw materials drying, but there exists large difference among raw materials, n order to make customers choose their expected drying equipment, we will provide technical consultation and provide installation and arrangement plan and make test of raw materials free of charge.

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Ribbon Blender - Plastic Process Equipment

RIBBON BLENDER

Scope of Application: 
In the U shape container, there are positive and negative ribbons. Special proportion of the two ribbons can be rectified with the kind of material, quantity and the proportion of body. The ribbon blender has good effect on mixing viscosity or cohesion powder.

Characteristic: 
A, Fast mixing speed can satisfy the rigorous demand of mixing the materials with different physical property.
B, The rotation is under critical speed, which will reduce the effect of fragmentation to the material(e. G. Crystal particle)
C, Lower height of the container is convenient for installation.
D, The positive and negative ribbons are set up at he same level, forming a mixing environment of low power but high efficiency.

Working Principle: 
A, The horizontal axes make the materials move up and down.
B, The outer ribbon gathering the material from sides to center and the inner ribbon pushing the material from center to sides.
C, Every screw makes the materials do axial and radial movement, the materials do relative cyclical movement so to gain the intensive mixings ends.

Seal: 
Our company provides various sealing devices according to difference of materials. The normal sealing structure is stuff seal and also called TEFLON seal. After using for a period, user(s) should fasten and enhance it. However, the dynamic seal has a long-time sealing effect and is especially fit for the powder, liquid.

Feeding inlet on the body cover: 
Two types:
A, used in the whole mixing/ blending process: In order to connect the feeding device, we design the connecting mouth
B, used in the manual feeding: In order to operate and clean inside of the body, we design feeding inlet(s) or door(s).
Discharging:
There is a discharging valve at the bottom of mixer body. When mixing different types of materials, we use flat discharging valve. The operation of the discharging valve should be convenient and there are three types: Manual, air driven and electricity driven. The manual discharging is operated on the valve and the open extent is controlled by hand freely. The air driven discharging valve, assembled with cylinder, work under the air pressure. The electricity driven discharging valve works under control of electricity control box.

Temperature control: 
We can use a jacket when heating, cooling or heat-preservation is needed.
The jacket is filled by circulation and heat conduction medium and can not bear high pressure. There are two kinds of heat conduction medium: Water and oil. The water temperature should be limited in 90 and the oil temperature should be limited in 300. The jacket coordinates the external heating system, the expulsion system, the pipeline to carry on to the material continues and even temperature processing.

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