Modem Packaging

All modem, packaged horizontal FT boilers are basically descended from the SM internally fired, FT boiler design. They became immensely popular during the early 1960s because of their versatility, cost-effectiveness, and relative efficiency (this last factor became very important following the fuel price crises of the early to mid-1970s). 

Modem, packaged vertical boiler designs are also very popular and are widely used for smaller or specialist applications. Today s vertical boilers are the product of over 50 years of continuous development. 

In modem, packaged horizontal FT boilers, the furnace is the most important heat-transfer component, typically providing 50 to 60% of the total heat transfer from only 30% or so of the total available heating surfaces. This level of heat transfer, coupled with the additional heat extraction obtained by the various multiple-pass designs (four passes is a practical maximum) provide efficiencies of 80 to 83% GCV. As a result, there generally is little additional benefit to be obtained from the use of economizers or air heaters, especially when using oil-fired boilers, which can operate at up to a 3% or so higher efficiency level compared to gas-fired units. 

Although the great majority of modem, packaged boilers are of horizontal FT design, packaged vertical boilers also are available, and a schematic, cross-sectional drawing of a modern vertical boiler is shown in Figure 2.3. 

This derivative of natural rubber produced by the action of hydrogen chloride (liquid or gaseous) found application as a transparent food packaging film, but has now been superseded by modem packaging materials such as PET. 

The modem packaging industry can be traced back as far as 1810 when the French pharmacist Nicolas Appert invented the canning process. Modem civilisation requires a continuous and reliable supply of safe and high-quality food. Since unprotected food is liable to deteriorate rapidly, it is necessary to provide appropriate protection and, although many other protective methodologies are currently in use, a prime feature of modem food protection is packaging. 

A tremendous range and variety of chemicals are used to make modem packaging materials. The European inventory list of chemicals used to make plastics intended for food contact numbered more than 1500 listed substances and inventory lists of a similar length exist for chemicals used to make paper, can coatings, inks and adhesives. The chemicals on the plastics inventory list mn literally from A (acetic acid) to X (xylene) with more than 1500 chemicals in between. Substances needed to make effective plastics packaging materials include ... 

The latter equation is easier for repetitive computations because the term at the bottom needs to be calculated only once, and such shortcuts were helpful prior to the computer age. However, using modem packages, it is not difficult to use the first equation, which will be employed in this text. It is important, though, always to understand and check different methods. In most cases there is little difference between the two calculations. 

A complication of modem packaging is the need for the application of security seals to protect against deliberate adulteration and maintain consumer confidence. The active products used must also be stability tested in the proposed packaging material. 

R. J. Lodge, Casein adhesives, Modem Packaging—Encyclopedia Issue (1959). 

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