Tuesday, March 7, 2017

Plate and Shell Heat Exchanger

Plate and shell heat exchanger combines plate heat exchanger with shell and tube heat exchanger technologies. The heart of the heat exchanger contains a fully welded circular plate pack made by pressing and cutting round plates and welding them together. Nozzles carry flow in and out of the platepack (the 'Plate side' flowpath). The fully welded platepack is assembled into an outer shell that creates a second flowpath ( the 'Shell side'). Plate and shell technology offers high heat transfer, high pressure, high operating temperature, uling and close approach temperature. In particular, it does completely without gaskets, which provides security against leakage at high pressures and temperatures.

Sunday, March 5, 2017

Plate Heat Exchanger Applications

Key Industries for Plate and Frame Heat Exchangers

Food and Beverage
Plate and frame heat exchangers serve many different purposes and are used in multiple industries. Within the food and beverage industry, the exchangers play a role in dairy production, as they are used in milk and cream pasteurization, milk reception, and ultra-high temperature sterilization (UHT). In regards to pasteurization, it is a process that involves heating certain food items to a specific temperature for a set period of time. The goal of this process is to kill microorganisms that could foster disease, spoil food, or lead to undesired fermentation. PHEs not only play a role in milk and cream pasteurization, but they also help purify many other products, too.
A second area of the food and beverage industry in which these specific exchangers operate is brewing, where they are used for wort boiling and cooling, as well as beer cooling. The third area they are used is in the production of soft drinks. The exchangers serve the purposes of water heating, energy drink pasteurization, sugar dissolving, and syrup pasteurization. And finally, within this industry, plate and frame heat exchangers play a part in fruit and juice processing.
Ethanol and Corn Processing
Another major area where plate and frame heat exchangers operate is the ethanol and corn processing industry. Particularly wide gap heat exchangers are used in mash cooling, beer/mash or beer/stillage interchange, fermenter cooling, and yeast propagation cooling. In addition, if the fluid being heated is weighed down by solids (e.g., beer), these specific exchangers can serve as vapor condensers.
Industrial Energy and Power Plants

Within power plants, proper safety relies on the cooling of oils, bearings, and rotor blades of diesel or gas motors; these same parts in steam or gas turbines need to be cooled, as well. A wide range of plate heat exchangers are produced in order to fuel this cooling. The exchangers also help make power generation more efficient.
Free Cooling/HVAC
Plate and frame heat exchangers also play a major role in ventilation. PHE’s take advantage of free cooling or chiller bypass. In turn, this means that water from cooling towers is able to bypass the chiller and flow directly into the heat exchanger. As a result, the number of hours the mechanical chiller operates decreases. This is beneficial in that some buildings, such as hospitals and skyscrapers, need cooling all year around regardless of the weather.
Marine
The marine industry relies heavily on plate and frame heat exchangers, as PHEs help maintain the primary engine oil cooler and the freshwater cooler. These exchangers serve other purposes on ships, too, as they help with tap-water production systems and HVAC systems. The main reasons PHEs are chosen over shell-and-tube exchangers is that they are much more efficient and compact, making them more suitable for the marine industry.

Plate and Frame Heat Exchanger Market is expected to drive product significance over the forecast period

Sherry James

The global plate and frame heat exchanger market is expected to reach USD 5.99 billion by 2022, according to a new report by Grand View Research, Inc. Growing awareness towards energy efficiency coupled with construction space constraints is expected to drive the market over the forecast period. Surging demand for thermal management in district heating applications is expected to drive product significance in commercial and residential sectors over the long term.
Technological advancements along with surging requirement for heat recovery utilities in chemical, food & beverage and HVAC sectors is expected to steer plate and frame heat exchangers market growth. Growing energy efficient utilities need along with expanding power generation infrastructure in economies including India, Vietnam, China and Thailand is anticipated to drive market growth.
Welded systems emerged as the leading product segment and accounted for over 20% of total market revenue in 2014. Owing to its widespread use in oil & gas, automobile, pharmaceuticals, petrochemicals and paper manufacturing industries, the segment is expected to gain share over other counterparts over the next seven years. This product segment is anticipated to increase penetration in oil & gas industry owing to reduced chance of leakage and enhanced corrosion resistance.
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Further key findings from the study suggest:
  • Global plate & frame heat exchanger market was worth USD 3.41 billion in 2014 and is expected to reach USD 5.99 billion by 2022, at a CAGR of 7.3% from 2015 to 2022
  • Chemicals emerged as the leading end-use industry with demand share estimated at 23.9% in 2014. Growing chemical & petrochemical industry particularly in the U.S., Germany and China is anticipated to impact plate & frame heat exchangers demand positively over the next seven years. HVAC & refrigeration is expected to witness the highest growth of 8.0% from 2015 to 2022.
  • Europe was the leading regional market and accounted for 37.5% of global revenue in 2014. Increasing product use across refineries and chemical industries owing to stringent government regulations have been the major factor contributing for high penetration.
  • Asia Pacific is expected to witness the highest gains in its market size over the forecast period. The region is expected to grow at an estimated CAGR of 8.4% from 2015 to 2022.
  • The global industry is moderately fragmented with presence of large number participants across the globe. Major companies involved in manufacturing & distribution of plate heat exchangers include AIC S.A., API Heat Transfer, Danfoss, Fischer Maschinen-und Apparatebau AG, Kelvion, Guntner, Hisaka Works, Alfa Laval, Kaori Heat Treatment and SWEP International.

Saturday, March 4, 2017

How to do Maintenance of Marine Heat Exchangers on Ships?

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Marine heat exchangers play an important role of removing the heat produced by a running machinery to ensure smooth functioning of the equipment. It is also necessary to enhance the heat exchanging ability which would reduce after certain amount of time of operation.
The cooling medium used in the heat exchangers depends on the medium used, including other factors.
Along with mediums such as fresh water, air and oil, sea water is also used abundantly in marine heat exchangers as an important cooling source. However, because of the presence of dissolved salts in sea water, corrosion and scale deposits is a common condition in heat exchangers. Maintenance of marine heat exchangers is therefore necessary at regular intervals of time to prevent reduction of heat transfer or failure of equipment.
The method of maintenance used depends on the type of heat exchanger and type of deposits, but the general aim of every heat exchanger maintenance procedure remains the same – cleaning of heat transfer surfaces to prevent any kind of obstruction in the flow process.
The main reason for fouling of heat exchanger surface is the increase in temperature difference between the two fluids and change in pressure. But it is the sea water side of the heat exchanger which suffers the most as a result of corrosion and scale deposits.
Methods of marine heat exchanger maintenance
Note: Prior to Maintenance, isolate the heat exchanger by shutting off the line valves for both medium and media; and drain the remaining liquid using the drain cock. The Vent must be open to ensure everything is drained from the heat exchanger.
  • If the deposits on the heat exchanger are not so hard, then they can be removed using a wire brush.
  • If the deposits are stubborn, chemical cleaning should be used by emersion of the part in chemical solution.
  • Depending on the type of the heat exchanger, there are tools provided by the manufacturers for the cleaning purpose. For e.g. there are special tools for cleaning shell and tube type heat exchangers.
  • Once the cleaning is done, the heat exchanger must be flushed with fresh water to remove any remaining chemical or dirt from the surface.
  • In sea water cooled heat exchanger, anodes are fitted on the cover to prevent it from galvanic corrosion. Anodes must be checked and changed if required.
  • Always renew the cover gasket if it is damaged during opening of heat exchanger.
  • In oil coolers and heaters, fouling can take place on the outside of the tubes as well. This can be removed by chemical flushing.
In plate type heat exchangers, the stack of plates is removed to expose the surface. The plate surface is then cleaned with brush or by the methods suggested by the manufacturer. (Sharp tools should be avoided). Cleaning should be done in such a way that it does not damage the plate seals. However, if a replacement of the seal is necessary, it must be done before putting the plates back.
While tightening the plates together, care must be taken for even tightening of all the exchanger studs and bolts or else leak will occur.
Excessive corrosion of the heat exchanger surface can also lead to perforation of the surface, resulting in mixing of one liquid with another. Minor leakage detection is not easy especially when the header tanks are automatically toped or if there is no proper manual record maintained. However, major leakages can be easily detected as a result of sudden loss of lubricating oil or jacket water. Low level alarms are also useful in detecting major leaks.
Another way to prevent mixing of two liquids because of perforation is by keeping the sea water at a pressure lower than the jacket water or any other liquid used. This reduces the risk of sea water entering into other mediums.

How leaks are detected?

Shell and tube type heat exchangers
If it's a shell and tube type heat exchanger, leaks can be detected by following the procedure below:
Isolating the heat exchanger from the system and draining the sea water
Removing the end covers or headers to expose the tubes or plates
If the surface is clean and dry, inspection of the liquid flow is made from around the tube ends and through the perforations. However, in large coolers it is difficult to get the coolers extremely dry to visualize any perforation. In such cases special fluorescent dye is added to the shell side of the cooler. The dye glows when an ultraviolet light is shone on the tube, revealing the tube leaks.
Plate Type Heat Exchangers
Similarly in plate type heat exchangers, visual inspection or fluorescent dye penetrate is used to find any defeats. (Dye penetrate is used on one side, followed by ultraviolet rays on the other side)
Air coolers
When it comes to air coolers, leakages can be dangerous as they allow sea water to pass through to the engine cylinder. This can lead to formation of scales on air inlet valves’ spindle.
In such cases, location of the leaks can be detected by allowing low air pressure on the air side and checking the flooded sea water side for air bubbles. For better results, soapy water can be used for sea water side flooding.
Apart from the above mentioned methods, there are other ways as well to carry of marine heat exchanger maintenance. However, these are the most commonly used ones.
Do you know any other ways?

Seeking the optimal design of a typical plate heat exchanger (PHE)

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Auther: A.G. Kanaris, A.A. Mouza and S.V. Paras

The need for designing process equipment that complies with the principles of economic and ecological sustainability acted as a driving force towards the evolution in the design of plate heat exchangers (PHE). Because of their compactness, close temperature approach and ease on inspection and cleaning (Shah & Wanniarachchi, 1991), PHEs are used in process and power industries for a wide range of temperatures. The plates of these PHE comprise some form of nearsinusoidal corrugations in a herringbone pattern (Fig. 1). When two of these plates are arranged and placed abutting, a channel with complicated passages is formed. As expected, the fluid flow inside a passage of this channel undergoes a series of periodic changes in flow direction, a kind of flow that augments heat transfer, while on the other hand it induces a significant resistance to the flow.

Previous work conducted in this Laboratory (Kanaris et al., 2006) has proved that CFD is a reliable tool for simulating the operation of a commercial PHE. Thus, in place of expensive and time consuming laboratory experiments, CFD simulations can be effectively used for predicting the performance of this type of equipment, which is strongly affected by the geometry of the conduit. Thus, the geometrical parameters of the conduit (Fig. 2) are used for creating a series of computational domains, based on a design-of-experiments (DOE) method, to optimize the PHE performance.

These conceptual PHEs have been numerically studied (in terms of heat transfer and fluid flow analysis), using a previously validated commercial CFD code (ANSYS CFX® 10) (Kanaris et al., 2006). To quest for the optimal design of the corrugated surface, an objective function is formulated, as a tradeoff between heat transfer and pressure drop, using a weighting factor to account for the relative significance of friction losses to heat recovery (i.e., electric energy vs. thermal energy). Five dimensionless groups are selected as design variables for the simulations, namely:

• the blockage ratio (BR=d/H) that expresses the percentage  of the entrance of the channel 'blocked' with corrugations,
• the channel aspect ratio (ChanAR=H/W); a measure of how narrow the channel is,
• the corrugation aspect ratio (CorAR=d/z); a measure of the obtuseness of the corrugation,
• the sine of twice the angle of attack (sin2θ) and
• the Reynolds number, Re, defined as: = h uD Re ρ μ, where Dh the hydraulic diameter of the conduit and u is the mean entrance velocity.

Box-Behnken design was selected for the design variables in order to construct the response surface. The calculated values of the objective function are used to create a quadratic model to be optimized using response surface methodology (RSM) (Myers & Montgomery, 2002).

A typical plot with results, covering a Re number range from 500 to 6000, is presented in Fig. 3, for a typical weighting factor. Apparently, the objective is to construct flow passages that enhance secondary flow inside the furrows, which in turn augments heat transfer rates. For low values of the weighting factor (i.e. when pumping cost is low), the optimal performance of the PHE is achieved for the shortest distance between the plates and for less obtuse corrugations. As Re increases, the PHE performance can be improved for lower channel aspect ratios (i.e., wider channels) and for higher values of the angle of attack. Nevertheless, if the weighting factor is high, i.e., the pumping cost is high, the optimal design of a PHE, as shown in Fig. 3, dictates greater distances between the plates and less sharp corrugations, as Re increases.

Thursday, March 2, 2017

Tranter PHE Products

Hofmann is serving from design, type selection, construction, manufacture to replacement supplement for all the Tranter plate heat exchangers. Following models list is for your reference.
If any of them you are interested with, please feel free to contact service@hfm-phe.com.
Or visit our product page http://www.hfm-phe.com/product/tranter-gaskets-plates.html for more info.
ModelModelModel
Tranter 11TTranter GX091Tranter HX180
Tranter GCD006Tranter GX100Tranter HX25
Tranter GCD012Tranter GX12Tranter HX50
Tranter GCD030Tranter GX18Tranter HX85
Tranter GCD054Tranter GX26Tranter HXD012
Tranter GCD055Tranter GX42Tranter HXD025
Tranter GCD065Tranter GX51Tranter HXD050
Tranter GCP026Tranter GX64Tranter HXD085
Tranter GCP030Tranter GX85Tranter HXD145
Tranter GCP051Tranter GX91Tranter HXD180
Tranter GCP060Tranter GXD012Tranter HXP050
Tranter GF057Tranter GXD018Tranter S3
Tranter GF097Tranter GXD026Tranter S8
Tranter GF187Tranter GXD037Tranter TW10
Tranter GFP030Tranter GXD042Tranter TW18
Tranter GFP050Tranter GXD051Tranter TW5
Tranter GFP057Tranter GXD060Tranter UX01
Tranter GFP080Tranter GXD064Tranter UX05
Tranter GFP097Tranter GXD085Tranter UX066
Tranter GFP100Tranter GXD091Tranter UX06T
Tranter GFP180Tranter GXD100Tranter UX10
Tranter GFP187Tranter GXD140Tranter UX20
Tranter GLD013Tranter GXD145Tranter UX40
Tranter GLP013Tranter GXD180Tranter UX801
Tranter GM138Tranter GXP018Tranter UX81
Tranter GM257Tranter GXP026Tranter UXP005
Tranter GM276Tranter GXP037Tranter UXP010
Tranter GM56Tranter GXP042Tranter UXP060
Tranter GM59Tranter GXP051Tranter UXP200
Tranter GX012Tranter GXP118Tranter UXP400
Tranter GX018Tranter HX012Tranter UXP801
Tranter GX026Tranter HX025Tranter UXP900
Tranter GX042Tranter HX050
Tranter GX051Tranter HX085
Tranter GX064Tranter HX12