White Engineer:
As for the boiler size, you must contact some boiler manufacturers and you must provide them with the following data (as a minimum):
(1) The complete analysis of your coal supply. It should include the weight percentages of carbon, hydrogen, oxygen, sulfur, nitrogen, ash and water. It should also include the gross heating value of the coal.
(2) The pressure and temperature of the steam you want to generate, including superheat (if any).
(3) The rate of steam generation that you want in pounds per hour or kilograms per hour.
If you want the manufacturers to quote prices for supplying and installing the boiler, then you will also have to provide them with your site location, available water supply (including analysis of the water) and various other site-specific data.
If your site is in the USA, then you also face the problem of obtaining environmental permits to operate a coal-fired boiler.
As for the loss of temperature and pressure in transporting steam in a 4 mile pipeline, that depends upon a host of factors such as:
(1) The rate of steam being transported (pounds per hour or kilograms per hour).
(2) The temperature and pressure of the steam at the pipeline entry.
(3) The diameter of the pipe and the type of insulation it will have.
(4) The winter-time weather conditions along the pipeline route (i.e., primarily the ambient temperature).
Your best approach would be to retain a competent consulting engineer to help you. Don't expect to use any simplistic design methods obtained on any online forum to provide you the know-how to "do it yourself".
Milton Beychok
(Contact me at www.air-dispersion.com)
