DE402274C - Process for the recovery of exhaust gas heat from boiler systems and the like like - Google Patents

Description

Process for the recovery of exhaust gas heat from boiler furnaces The invention has the purpose of recovery in boilers and the like to allow the heat still present in the exhaust gases to a greater extent than is the case with the usual operating procedures, e.g. B. with normal flue gas preheaters, is possible.

This purpose is achieved according to the invention in that the smoke gases Water vapor or water supplied to saturation and the water vapors through subsequent Subcooling of the flue gases can be suppressed by removing the flue gases either via cooling elements, e.g. B. flue gas preheater through which cold water flows accordingly or by a cold water mist or the like injected into the trains.

The advantages achieved by this process are substantial the following: First one comes as a result of the much greater thermal conductivity of the saturated Flue gases compared to the unsaturated with a much smaller heating surface from and As a result, the exhaust gas heat can be reduced in a much more economical manner than before recover completely. Second, you can do this by the strong cooling of the smoke gases also the heat of the natural or possibly contained in the combustion air free of charge in the same, e.g. B. by spraying hot ash or slag or the like., recover the water or water vapor brought in, as well as the heat, which in the incineration in the from the moisture or water vapor content the vapors created by the fuel passes over. Finally, there is another benefit in that by draining off the resulting condensation an accumulation of combustion residues in the trains can be prevented and that the acid that forms only in strong can occur in a diluted state.

When carrying out the process, one can do it in various ways proceed. One can, for example, the normal smoke gases as long as their temperature is high, initially in the usual way heat to a certain extent with a normal preheater, low-pressure steam generator or the like then saturate the fumes by injecting water or steam to them then via a second preheater with correspondingly cold fresh water to conduct and * them largely the heat by precipitation of the water vapor, d. H. up to almost the initial temperature of the fish water fed to the second preheater, to withdraw. The fresh water supplied to the second flue gas preheater can, there sweating of the preheater need not be prevented, at a much lower level Temperature are supplied than before during normal operation, so that the heat almost can be recovered completely. You can of course instead of double Preheater also use a single preheater to which only supply cold water is, the water vapor being fed to the flue gases upstream of this preheater got to. Instead of adding water vapor to the flue gases, one can also do this from the outset the combustion air to be fed to the furnace with such large amounts of water vapor enrich so that these are sufficient to saturate the smoke gases. The combustion air is preheated accordingly in one or more stages for this purpose.

The undercooling of the saturated smoke gases and the precipitation of the water As said, they can also be brought about by the fact that one continues to supply cold water to the flue gases beyond the degree of saturation, which z. B. is injected into the channels in the form of a mist, so that the flue gases create the cold water mist have to go through.

It goes without saying that a result of the undercooling of the flue gases Inadequate draft caused by the chimney can be replaced by artificial induced draft must, the arrangement of the fan made at any suitable point can be. If there are several preheaters or the like connected in series, it will It is advantageous to install it between the normal heater and the heater used for cooling will. If to precipitate the heat cooling elements, so z. B. preheater used are, these are also made according to the invention from a material that is very resistant to the effects of acids, e.g. B. made of lead, if necessary these cooling elements also only have a coating of acid-resistant material (Lead, enamel).

Claims (2)

PATENT CLAIMS: i. A method for recovering the exhaust gas heat from boiler furnaces and the like., Characterized in that the flue gases are supplied with water vapor or water until they are saturated B. flue gas preheater through which cold water flows or through a cold water mist o. The like injected into the trains. 2. Procedure according to claim i, characterized in that the enrichment of the flue gases with Water or steam after removing part of the high-quality heat a normal preheater, low-pressure steam generator or the like. By injecting Water or steam occurs. Method according to claim i, characterized in that that the amount of water vapor in the combustion air required to saturate the flue gases before they enter the furnace, the combustion air preheated beforehand in one or more stages to a correspondingly high temperature will. q .. device for performing the method according to claim i to d., characterized characterized in that the cooling elements used for subcooling the saturated flue gases (Flue gas preheater) consist of acid-resistant material or with a coating this material provided sin- !.