Skip to main content

How to overcome Thermal Expansion in Heat Exchangers?

So many times industries come across problems associated with thermal expansion in Heat Exchanger, and they have to trade off between four aspects of Heat Exchanger Design..

 1. Allowance for Thermal Expansion

 2. Efficient Heat transfer

 3. Ease of Cleaning

 4. Mechanical Robustness 
As shown in the figure how floating head exchangers are work..
The tube side flow enters from the bottom of the tube head.  Generally we take cold fluid on Tube side and Hot fluid on Shell side. 

 Inside the exchanger we have pass partition plate which forces the total  flow only through bottom half of the tubes. 

 Now if you have noticed that one of the end of heat exhcanger is open. so the question is Why one of the end must be kept open to float?

 so the reason is Thermal expansion, more preciously the differential rate of thermal expansion between tube and shell.

 As higher the temp, and heat transfer takes place between shell and tube side fluid there must be chances for Thermal Expansion. so to avoid thermal expansion we have to place one of the end free so floating head heat exchangers are worked well in these conditions where there is grater chances of thermal expansion.
other way to avoid thermal expansion problem is individual U bands for each tubes, and that acts like mini floating head for each tube. 
Labels:

Comments

  1. Ajay16 October 2017 at 07:33

    Good work done..
    Keep sharing this things..

    ReplyDelete

Post a Comment

Popular posts from this blog

How do refineries calculate Height of Equivalent Theoritical Plate (HETP) for distillation column ?

Typically, refineries don’t calculate it themselves but get the companies selling them the packing to guarantee performance. Prior to that, they or the company contracted to do their construction, would come up with an estimate. There is no simple “grand unifying theory” for HETP. For the design of packed distillation columns it is simpler to treat the separation as a staged process. Use the concept of the height of an equivalent equilibrium stage or HETP (Height Equivalent to theoretical plate) to convert the number of ideal stages required to a height of packing. HETP is the height of packing that will give the same separation as an equilibrium stage. Eckert (1975) has shown that in distillation the HETP for a given type and size of packing is essentially constant , and independent of the system physical properties ; providing good liquid distribution is maintained and the pressure drop is at least above 17 mm water per meter of packing hei...
1 comment
Read more

How will increasing/decreasing the pressure of the distillation tower affect flooding?

Flooding occurs if vaporization rate of reboiler is higher, then liquid partially carryover by the vapors from below tray to above tray, if it is continue then liquid hold up on the above tray increases and causes flooding Naturally we don’t want to over pressure the tower and open the safety valve, Same way if tower pressure goes too low then we could not condense the reflux, then the liquid level in reflux drum would fall and the reflux pump would lose suction. Now Take 1. Raising the tower pressure Higher pressure reduce volumatric flow of vapor, (As the Pressure is inversely proportional to Volume), So increasing the tower pressure does not Causes Flooding but its a one of the option to reduce the effect of Flooding . Now the question is why we are increases the Tower Pressure? so the answer is to permit higher reflux rates. 2. Decreasing the tower pressure Generally Distillation columns are operated at low pressure, Because as the tower pressure will decrease...
Post a Comment
Read more

Overview of Cooling Tower working principle, components and types.

Generally we think that cooling tower is Heat transfer equipment, but the actual thing is cooling tower is work on mass transfer and result is Heat transfer. As we know Cooling towers are a very important part of many chemical plants. The primary task of a cooling tower is to reject heat into the atmosphere. They represent a relatively inexpensive and dependable means of removing low-grade heat from cooling water. Hot water from heat exchangers is sent to the cooling tower. The water exits the cooling tower and is sent back to the exchangers or to other units for further cooling. Some of the Applications are listed below.. Oil refineries, Petrochemical industries Chemical Industries, Thermal Power plans, HVAC system for cooling buildings... Working Principle: Humidification Operation : This operation is concerned with the interphase transfer of mass and of energy which result when a gas is brought into contact with a pure liquid in whic...
2 comments
Read more