Log in

Login to your account

Username *
Password *
Remember Me

Becht Engineering Blog

In this section of the site contributing authors submit interesting articles relating to the various services, industries and research & development efforts of Becht Engineering.

Cooling Towers: Benefits of a Cold Eyes Review

oil-gas-cooling-towers-engineer
One key decision that often needs to be made is repair vs. replace. When has a cooling tower arrived at the point where a new tower should be considered? Maintenance costs, overall tower condition, environmental constraints, and performance optimization are all factors that need to be evaluated. If a new cooling tower is justified, how are the specifications for performance selected? What range, fan horsepower, approach to wet bulb, and water flow rate should be specified to best match plant requirements? The range is the difference between the hot water (return) temperature and the cold water (supply) temperature. The approach to wet bulb is due to the fact that, if the cooling tower were infinite in size, the cold water temperature would be at the wet bulb temperature. However, just like a shell and tube heat exchanger with a temperature difference between two streams, a finite cooling tower results in some...
Continue reading
3
  150 Hits
  0 Comments
150 Hits
0 Comments

Fluid Catalytic Cracking (FCC) Transfer Line Flexibility - Analysis and Design Considerations

fcc-3images-ppt
FCC’s are complex units - and the design of their transfer lines has some unique considerations.   While many of the lines are refractory lined to permit construction with carbon steel piping, some sections are hot walled, at temperatures well into the creep range, for the purpose of balancing thermal expansion or, in the case of piping between the final catalyst separations device and flue gas expanders, to prevent dislodged chunks of refractory from being drawn into and damaging the expander.  Below are some critical considerations: The stiffness of the piping and resultant loads on equipment are affected by the presence of internal refractory . The composite action of the steel pipe and refractory needs to be considered.  Note that this is not simply including the refractory as a monolithic element, since the refractory will have shrinkage cracks.  There is a paper by T Chadda on an approach that can be...
Continue reading
4
  1339 Hits
  0 Comments
1339 Hits
0 Comments

“Speed Kills” – An Empirical Association of Antifriction Bearing Behavior When Things Go From Bad to Worse

“Speed Kills” – An Empirical Association of  Antifriction Bearing Behavior When Things Go From Bad to Worse
Machinery and reliability people have for a long time observed that when it comes to long life and high reliability, operating at higher speeds compares poorly to operation at lower speeds. One of the primary reasons for having high-speed devices is economics. With high speed you can have smaller equipment sizes with fewer stages. While capacity and pressures developed do improve, this often occurs at the cost of increased wear, vibration, noise and maintenance. There are some limits as to how fast and large we can practically go. At some point even the required lubrication systems become very complex. While smaller equipment can use antifriction/rolling element bearings, their application is typically limited by manufactures to a certain speed. When combined with the bearing size, this limit becomes known as a DN number limit, a product of the mean bearing diameter (ID+OD in mm divided by 2) and the RPM. This DN...
Continue reading
1
  2258 Hits
  0 Comments
2258 Hits
0 Comments

Tornado Design For Nuclear Power Plants: A Brief History

Tornado Design For Nuclear Power Plants:  A Brief History
Nuclear power plants are designed to be capable of a safe shut-down in case of a large design-basis tornado or hurricane. The magnitude of the postulated design-basis tornado or hurricane is such that there is less than 1 in 10 million chance (1E-7) per year and per reactor that it would be exceeded. This probability governs the wind speeds, pressures, and missiles generated by the tornado and provide the engineers a basis for design of the plant structures, systems, and components. This paper consists of two parts. First, Part 1, is a quick overview of the NRC regulations which govern tornado and hurricane design for nuclear power plants.   Part 2 is a timeline of key developments in tornado design for nuclear power plants over the last 70 years. For it is important that engineers understand not only what they are to do, but also why and how we got where...
Continue reading
1
  2819 Hits
  0 Comments
Tags:
2819 Hits
0 Comments