Maxi Therm steam heat exchangers

The Maxi-Therm system is a new, patented form of instantaneous steam to water heater. Conventional piping components are utilized in every critical valve or pump. A facility can even specify pumps and valves for which they already stock parts.

Energy conservation is unparalleled. There is no unit on the market more energy efficient than a Maxi-Therm for steam to water heating. It squeezes every practical BTU out of the steam and condensate.

Normally when a system is energy efficient, it’s not the lowest cost to install. The Maxi-Therm is different. It does not require a pressure reducing valve station, or a dedicated condensate pump. This can save up to 40% of the installed cost on a new job.

To explain how the dramatic energy conservation and cost savings are possible, let’s start at the beginning, with water…



Steam fundamentals

When make-up water enters the boiler room or power plant, its first stop after treatment is the deaerator. Here it is sprayed over heated trays to drive out dissolved gases. The water is usually heated from 40F to 205F by adding sensible heat. It takes about 1 BTU to raise a pound (or pint) of water by 1F. These BTU’s are supplied by steam in the trays.

Smaller package boilers might not utilize a deaerator, in which case, the boiler provides this same sensible heat demand.Image1

Here is one place where the Maxi-Therm system makes a difference. Why is make-up water needed in the first place? Some losses are due to boiler blow-down and some to make up for leaks. The other loss is from “flash steam”. That’s the steam puffing out of vent pipes all around the condensate return system.

The steam boiler takes water from the deaerator, heats it to the boiling point by adding more sensible heat, and then adds latent heat to vaporize the water into steam. How much sensible and latent heat are needed? That depends on the steam pressure desired.

A sophisticated system for a university, food processor, or chemical plant will generate steam at 600 psig or higher, because steam is used to generate power before distribution. The steam is normally distributed at 100 or 150 psig. Some industrial plants (usually with turbine drives) will distribute steam up to 600 psig.

Systems are designed around higher pressure distribution because of the steam volume.

High pressure distribution is used to minimize pipe sizes, and reduce the drop in pressure experienced by flowing steam. Intermediate pressure steam is normally 60 or 80 psig. It is used for sterilizers, autoclaves, wash mixers, and pumping stations. This steam is usually generated from distribution pressure by a pressure reducing station.

Low pressure steam is normally 10 to 15 psig. It is used for heating air and water. The water heating systems are either “service” or “domestic”. Domestic water is for the hot side of sinks and showers. Service water is first heated by the steam, then it circulates through coils and baseboard to heat air. It’s usually mixed with glycol to avoid freezing.

Between service and domestic, most facilities use at least 50% of their steam

for heating water. Condensate system pressure is normally 0 psig. Industrial process dryers sometimes use intermediate 30 to 60 psig return systems, which then “cascade” down into a 0 psig system.