US2223407A - Heating method and apparatus - Google Patents

Description

Dec. 3, 1940.

D. K, DEAN HEATING METHOD AND APPARATUS COM/919555 me Filed July 2, 1938 CoA/DE/VSATE EETl/E/V INVENTOR ATTORNEY Patented Dec. 3, 1940 UNITED v STATES HEATING METHOD AND arrmarus Dion K. Dean, Railway, N. ,L, assigno'r to Foster Wheeler Corporation, New York, N. Y., a corporation of New York Application July 2, 1938, Serial No. 217,133

9Claims.

My invention relates to high temperature heating systems of the type in which vapor of a hi boiling point liquid such as diphenol, diphenol oxide, Dowtherm," or other suitable substance,

is used as a heating medium in industrialprocesses, such as the deodorization of animal or vegetable oils and the like. In such systems, the vapor is ordinarily generated in a boiler or similar heating device and then conducted directly to a point of use where it is brought in heat exchange relationship with the material to be heated, the condensed vapor thereafter being returned to the boiler for reheating. Although this practice is satisfactory when the required vapor temperatures are such that none of the material is heated above the chemical breakdown point, it is not satisfactory when the required vapor temperatures are at such level that some portion of the material is heated above the chemical breakdown point. This is so, for the reason that in vapor generating apparatus, such as boilers or the like, some of the fluid being heated, particularly the fluid which is directly in contact with the heating surface, will be elevated to a temperature higher than that of the vapors generated in the apparatus, the degree of such higher 1 temperature over that of the vapors generated depending ordinarily upon the particular generating apparatus used. Accordingly, it is quite 80 possible that in delivering vapors of a given temperature from fluid heating apparatus, some parts of the fluid, may be heated to a temperature so high that chemical decomposition may take place.

35 It is the object of my invention to provide a method of, and means for, heating with vapors by employing vapors which have been raised in temperature beyond a pointat which chemical decomposition would take place in fluid heating 4o apparatus by such means that the chemical composition of the heating material is not injuriously afiected, whereby the temperature range of the vapors as heat transfer agents is materially extended; This is accomplished, generally 45 stated, by applying a relatively small amount of heat in the form of mechanical energy to the vapors which will make available a large amount of latent heat at a temperature level above the temperature at which it can safely be delivered 50 by fluid heating equipment without subjecting the heating material, or any portion thereof, to the deleterious eifects of overheating. For a better understanding'of the particular features that characterise my invention, refer- 56 ence may be had to the following description considered in connection with the accompanying drawing in which the single figure is a generally diagrammatic view of a high temperature heating system embodying my invention.

Referring to the drawing, reference character 5 l0 designates a boiler or vapor generator to which an initial charge or "make up of the desired liquid or material may be supplied by any suitable means, not shown, and wherein the vapor will ordinarily be generated at the maximum 10 temperature possible short of the chemical breakdown point of any portion of the liquid, although it may be heated to temperatures lower than said maximum temperature, if desired. The vapors produced in the boiler are conducted 15 through a line H, to a compressor l2 which may be a direct acting or centrifugal compressor, by means of which the vapor is compressed, and the pressure and corresponding temperature thereof is increased to the desired level without 20 overheating and consequent chemical breakdown of any portion ofthe material in the circuit. From the compressor, vapor line l3 conducts the high temperature vapor to a point of use, which as shown consists of a coil it through which 2 the vapor from line l3 flows, and which is submerged in a shell or tank l5 containing the material to be heated by indirect contact with said vapor. A trap l6 provided with a float valve I'l receives the cooled or condensed vapors from the coil ll. When the body of condensate in trap it reaches a; sufficient height, the float valve I] will open and discharge the condensate through line [8 toa flash chamber I9 which has its upper portion connected by line 20 to the inlet or suction side of the compressor. A condensate return'line 2l connects the bottom of the flash chamber I9 with the boiler l0. Since the pressure on the condensate within the flash chamber will be approximately that of the boiler, 40 .vapors will be flashed off therein and will be returned to the suction side of the compressor, while the remaining condensate in the flash chamber will be returned to the boiler through line 2 I, thus completing the cycle.

In the event superheating takes place during compression of the vapors, this may be prevented by mixing some of the condensate of the vapor with the vapor to-be compressed. One means for accomplishing thispurpose comprises a line 22 between the trap l6 and the suction of the compressor, (connecting with line H and by means of a valve 23 in line 22, a governed quantity of condensate may be returned through this line to the suction of the compressor. The

condensate would enter the compressor preterably in the tom 01' mist and thus prevent overheating of the vapor during the compression step.

, It will thus be perceived that by employing the present invention, vapors may be utilized for heating purposes which are higher in temperature than vapors which can ordinarily be obtained from vapor generating equipment without chemical breakdown of the material or any portion thereof. The invention is capable of general application and is not limited in its use to the specific materials mentioned herein.

By the expression "chemical breakdown point" as'used herein and the expression critical temperature" as used in the claims, is 'meant'that temperature of the vapors of the material'being used as the heating medium, which it generated by the application of heat in a boiler or similar apparatus, and elevated to said temperature, would entail the heating of at least some of the fluid to the temperature of chemical decomposition.

Although I have illustrated and described a preferred form oi. apparatus for carrying out my invention, it is to be understood thatchanges may be made in the specific form and arrangeinent of parts disclosed and in the method and the several steps thereof without departing from the principles of the invention which is not to be limited excepting by the scope of the appended'claims.

What I claim is:

1. The method of heating substances by heat exchange with vapor of a material subject to chemical decomposition when heated by combustion gases beyond a critical temperature which comprises producing vapor of the material by means of combustion gases at temperature levels below said critical temperature, in-

creasing the temperature of the vapor to the desired point above said critical temperature withoutchemical decomposition of any portion of the material, by compressing the vapor, and bringing the compressed vapor into heat exchange relationship with the substance to be heated.

. 2. The method of heating substances by heat exchange with vapor of a material subject to chemical decomposition when heated by combustion gases beyond a critical temperature which comprises producing vapor of the material by means of combustion gases at the maximum temperature below said critical temperature, increasing the temperature of the vapor to the desired point above said critical temperature without chemical decomposition of any portion of the material, by compressing the vapor, and bringing the compressed vapor into heat exchange relationship with the substance to be heated.

3. The method of heating substances by heat exchange with vapor of a material subject to chemical decomposition when heated by combustion gases beyond a critical temperature which comprises producing vapor of the material by means of combustion gases at temperature levels below said critical temperature, increasing the temperature of the vapor to the desired point above said critical temperature without chemical decomposition of any portion of the material, by compressing the vapor, bringing, the compressed vapor into heat exchange relationship with the substance to be heated in a heating zone wherein part at least of the vapor is condensed, and mixing condensate oi the vapor with vapor to be compressed prior to compression to thereby prevent superheating of the vapor upon compression.

4. The method of heating substances by heat exchange with vapor or a material subject to chemical decomposition when heated by combustion gases beyond a critical temperature which comprises producing vapor ot the material by means of combustion gases at tempera-- ture levels below said critical temperature, in-

creasing the temperature of the vapor to the desired point above said critical temperature without chemical decomposition of any portion 01' the material, by compressing the vapor, bringing the compressed vapor into heat exchange relationship with the substance to be heated in a heating zone wherein part at least oi'the vapor is condensed, conducting condensate to a flash zone, conducting vapor evolved in the flash zone to the zone wherein said vapor is compressed, and returning the remaining condensate to the vapor producing zone.

5. The method of heating substances by heat exchange with vapor of a material subject to chemical decomposition when heated by combustion gases beyond a critical temperature which comprises producing vapor oi the material by means of combustion gases at temperature levels below said critical temperature, increasing the temperature of the vapor to the desired point above said critical temperature without chemical decomposition of any portion of the material, by compressing the vapor, bringing the compressed vapor into heat exchange relationship with the substance to ,be heated in a heating zone wherein part at least of the vapor is condensed, mixing condensate of the vapor with vapor to be compressed prior to compression to thereby prevent superheating of the vapor upon compression, conducting condensate to a flash zone, conducting vapor evolved in the flash zone to the zone wherein said vapor is compressed, and returning the remaining condensate to the vapor producing zone.

6. Apparatus for heating substances by heat exchange with vapor of a material subject to chemical decomposition when heated by combustion gases beyond a critical temperature, comprising means for producing vapor oi the material by combustion gases at a temperature level below said critical temperature, compressor means for increasing the temperature of the vapor to the desired point above said critical temperaturewithout chemical decomposition of any portion of the material, means for bringing the compressed vapor into heat exchange rela- .tlonship with the substance to be heated, during which part at least of the vapor is condensed, means for conducting condensate to a flash chamber, means for conducting vapor from the flash chamber to said compressor means, and

means for conducting condensate from the flash perature without chemical decomposition of any portion of the material, means for bringing the compressed vapor into heat exchangerelationship with the substance to be heated, during which part at least of the vapor is condensed,

means for mixing condensate of the vapor with vapor to be compressed to prevent superheating of the vapor upon compression, meam for con-. ductin condensate to a flash chamber, means for conducting vapor from the flash chamber to said compressor means, and means tor conducting condensate from the hash chamber to the vapor producing means.

8. The method of heating substances by heat exchange with vapor of a material subject to chemical decomposition when heated beyond. a critical temperature which comprises producing vapor of the material at temperaturelevels below said critical temperature, increasing the temperature of the vapor to the desired point above said critical temperature without chemical decomposition oi any portion or the material, by compressing the vapor. and brinsin: the

any portion of the material, means for bringing the compressed vapor into heat exchange relationship with the substance to be heated, during which part at least of the vapor is condensed, meansfor conducting condensate to a flash chamber, means for conducting vapor from the flash chamber to said compressor means. and means for conducting condensate from the flash chamber to the vapor producing means.

pron x. DEAN.

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