US1686186A - Furnace efficiency meter - Google Patents

Description

Oct. 2, 19,28.` Ll

J. M. sPiTzGLAssg FURNACE EFFIC' ENGY METER Filed dan. 12, 1927 if IN VEN TOR.

A TTORNEYJ laten'ted Oct. 2, 1928.;

UNITED STATES PATENT OFFICE- JACOB M. SPITZGLASS, OF CIIICAGO, ILLINOIS, ASSIGNOR TO REPUBLIC FLOW METERS COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

FURNACE EFFICIENCY METER.

Original application led May 1, 1926, Serial No, 105,957. Divided and this application led January 12,

1927. Serial No. 160,721.

This application is a division of my pending 'application Serial #105.957, filed May lst, 1926, and relates especially to the apparatus shown vin said pending application. One object of the present invention is to provide means by which the operator may at all itimes be appraised of the conditions existing in the apparatus so that if he observes that any of them are at varia-nce with those which have been predetermined as being most advantageous, they may be corrected, thus causing the apparatus always to function with maximum leli'iciency even though the capacities at which it is operating change from time to time. For illustration, taken the case of i a steam generating plant in which fuel is Q employed to generate the heat, Ordinarily upon the amount of power required, or in the case of a heating plant. on the amount of heat which must be supplied. This factor of steam How, therefore, while vaniable, is not, practi-` cally speaking, under the control of the man in charge ofthe boiler room but is'dependent upon exigencies beyond his control, such as power or heat requirements. Consequently, the steam iiow or boiler capacity isl the given or predetermined factor.- and one purpose of i the invention is to provide a method and means for keeping the operator advised as to the capacity at which the boiler is operating and also keep him advised as to other lcorrelative conditions or factors so that he may be able to modify them in such manner as to obtain maximum eiiiciency. Another object of the invention is to provide means by which the operator may readily compute the eiiiciency at which the boiler is operating at any given moment. Another object is 'to provide means by which a permanent record of the various conditions or factors may he made and the efficiency computed. f

Boiler eliciency is obtained in practice'by determining the loss of heat due to improper combustion of fuel in the furnace and improper absorption of heat in the boiler.

In ordinary boiler room operation most of the loss is the heat carried away through the stack by the heated gases. Improper comn -cative of the total loss of heat through the Let L signify the percent loss in the boiler, and W and T the weight and temperature lof the escaping gases respectively.

Then

` L=K`WT (l) K being a constant determined by the conditions of each given case.

Of the twoy variables involved in the heat loss, T can be obtained directly by measuring the temperature of the gases. Properly speaking, the temperature that should be oonsidered is the diiference between the roomyroom temperature and T will therefore be understood as representing the diiference in temperature or the rise above room temperature. 1

- The value of W cannot be obtained directly but it has been found by experience based on.I

numerous tests and experiments that the per? cent of carbon dioxide in the. flue lgases isaidirect index of the'amount of air used [for y. the combustion of the fuel l (it heilig under- -stood of course7 that in the practical operation of a steam boiler a greater amount'ofair than that theoretically required for complete combustion is always supplied., such excess resulting in the proportionate reduction of the CO2 contents in the flue gases). Consequentl the amount of CO2 in the gases indicates t e weight ofthe gases passing through the stack per pound of fuel. Hence We may Write W=f/P ci simplified by substituting for KW, this substitution being close enough for practical purposes although in the actual construction of my apparatus the scale may be made according to the more accurate y determined relation of W to P. j

Making the substitution in Equation (l) we have L=Kf (e) To illustrate the application of this equation; let it be assumed that a. given fuel, say western bituminous screenings, having a heat value of 11,000 B. t. u. per pounds, re'quires a. minimum Weight of 8.4 pounds of air per pound of fuel for perfect combustion result ingl in a maximum of 18.4 per cent of-COz.

In practice. it is first necessary to obtain the characteristics of the particular boiler for which the instrument is to he used and for this purpose a test is run on the performance of the boiler. Let is be vassumed that the test shows 'that when T is equal to 500 de-V grees F., and P is equal to 1Q percent CO2, the

. boiler has an overall eiiiciencyof 64 percent.

Subtractin this eiciency from 100 ercent` it is found; that L, the loss, isequa to 36 percent.

With a knowledge of these conditions solve for the value of K from "riiquationv 3),.A

For convenience we let T represent units of temperature, 100 degrees F. each. Then Thus the loss may be'computed at any' time by observing the temperature and the percent of CO2 and this formula will hold substantially 'true for various capacities or rates of steam iiow of the particular installation under observation.

To give a concrete illustration of the method and operation of the apparatus, reference may be had to the accompanying diagram in which a record strip a is caused to travel beneath styli b, e, and d. In the present case, the strip is assumed to travel downward and as mechanism for causing record strips to travel are Well known such mechanism need not be described here. The sheet has cross rulings e which indicate the various hours of the day, these hours being denoted by appropriate markings f here shown in a column at the left margin of the strip. The strip is divided into three sections arranged side by side, the section o at the left representing steam iloiv, the section h at the middle representing' the percent of CO2 and the section j at the right representing the stack temperature, or more properly speaking, the differ Yence ,between the stack temperature and the temperature of the boiler room. l The steam ow section g has vertical rulngs'or ordinates 7c spaced equally and'repre-` senting units of steam flow.. "These units are indicated .by a row'of numerals m which in the present illust-ration progress from left to rightl in increments of ten. These units are selected arbitrarily and thel operator may, if he wishes, translate these units into actual pounds of steam generated per hour.

The C()2 section iz, has vertical rulings or ordinates n spaced equally and representing the percentage of CO2. These percentages are indicated by a row of'numerals pwhich in the present .illustration progress from left to right in increments of two.

The stack temperature section y' at the right `has vertical rulings r that are spaced equally and represent stack temperatures.. These temperatures are indicated by a row of numerals 8j which progress from left'to right in increments of'one hundred. 'u Said roWsm,-p and s of numerals may be 4'printed directly upon the record strip at intervals orthey may marked on a stationary portion of the apparatus in such position that the vertical lines or ordinates 7c, n, r will pass under them in juxtaposition thereto.

Thestyli b, c, d may besupported and operated by any appropriate type oflmechanism so long as they are movedin accord.

ance with the variation of the factors which they re resent. In the present case, which is large y diagrammatic, the styli are sup.- ported'upon rods t slidable upon a guide bar u and controlled by rodsa', y, e which are moved by suitable devices in accordance with the variable factors of steam flow, percentage .of COzfand stack temperature. For .example', the'rcd a: may be operated by a steam lovvnieter, which is a known instrument` and the rod g/ may be operated by agas analyzer I. it

ficiency greatest in proportion as the graph` C moves toward the right and the graph D moves toward the left. Thus :by merely noting the positions of the graphs or Styli 4 with respect to the line of reference R, which igor other transparent material, although this is at the 'right end of scale p and the left end of scale a, an approximate idea of the loss may be obtained. In other words, as the right end of scale p and the lett end of scale s are coincident, an approximation mayf be obtained by noting-the dist-ance between p times ofthe actual conditions of operation,

the two graphs. I

But my device in its developed forni goes further than this and is so constructed thatthe observer may vby making a simple multi plication of two numerals calculate the eftr,`l

cieney at which the boiler is operating. The

mechanism `more intimately concerned with` `this characteristic will now be described; lThe bridge 'v is -mounted in front of the ."record strip and held stationary by screws c" `0r other suitable fastening means. In the -form illustrated it consists of g1ass,eelluloid .'f 'fis not essential. On this bridge in juxtaposif'ftration vrun from() to 9, progress from left t0 right, and eachunit represents 100 degrees bistack temperature. This scale represents the 'temperature factor-T of VEquation No.

(3) and it will be noted that it progresses in fthesaine direction as the scales and that the 1 tion to scales there is marked a4 scales in` which thenumerals representunits of teun perature. .The ,integers inthe present illus- 'zero point is aline R.

. -On the bridge ein juxtaposition to scale.

p there is marked a. scale p' in which the numerals vprogress -in the opposite direction g ner that the factor W'bears to thefactor P as' hereinabove explained. The scale p -in reality represents the W factor, although as. this is determined according to my method' from tlie'CO2 factor in the flue gases, in thel l the CO2 indicator moves toward the tempera.-

from scalep.- lThese numerals are marked No( `(a)1f-fratethe mit p' betas; manip-ms cal relation tothe scale p in the same manparlance of the boiler room the scale p is more apt to be referred to as the CO2 factor and is .-so marked in the diagram. In the From the foregoing it will be evident that '.'5 the device illustrated'constitutes a boiler eficiency meter and embodies in a single instrument means for indicating "or recording' three variable factors, viz, steam flow,.stack` temperature and percentage of the carbon dioxide in the staekgases, the latter factor 1in my device `being interpretable in 'terms of the weight of iiue gases per pound of fuel. Thus the operator may be appraised at all and he is atforded simple and reliable means by which lie may, by an easy computation, lcalculate the yeiiicieney at which the boiler is operating. i' i v 'According to the arrangement illustrated, 90 the graphs C and D approach each other as the eiiicie-ney inerease'sand recede from each vother 'as it decreasegbutcitfwill be understood, of course,v thatthis arrangement may be reversed without departing from the spirit '95 of the invention, for by reversing the scales p", s andreversingthe movement of the indicators c and Z the eicieney will be greatest when the graphs C, D are farthest apart and `leastwhen they areeclosest together. The A. 'present arrangement, however, lis preferred, L for according-to 'it the, zerolocated ona common line (in t points may be .line R) and theinstrument will present a more graphic and readily understood picture I in the mind 'ofthe operator.

The words stack gases in the specifica-` tion and the claims are intended and will be understood to mean the products of combustion whether before or after they enter the' 110 stack proper.

I claim :M

l. A furnace efficiency meter comprising an u v indicator movable in accordance with the temperatureo'f the stack gasesand an indicator 115 movable in accordance with the percentage l of. carbon dioxide in the stack gases, said in- 1 dica-tors being so .positioned that the temper- `ature indicator moves'away from the CO2 lindicator as t-he temperatures increase and toward it as the temperatures decrease and increase, and means `for indicating the indie'present case vidual distances of said indicators 'from a common reference point located between them. l.

3. AY furnace eliicienc-y meter having indicated thereon a basev point of reference, an indicator movable toward' and from said -base point in proportion to the temperature ofthe stack gases, and a secondindicator movable toward and from said base point in proportion to the Weight of the flue gases per'pound of fuel passing through the stack.

4. A furnace etiiciency meter comprising an indicator movable in proportion to the temperature of the stack gases, an indicator movable in proportion to the percentage of carbon dioxideV in the stack gases, and a scale in juxtaposition to the last mentioned indicator and reversed with respect to the movement thereof whereby the indicator will show an increased value on the scale as the percentage of carbon dioxide decreases and adecreased value as the percentage increases.

5. A furnace efficiency meter comprising an indicator movable in proportion to the percentage of carbon dioxide in the stack gases, and a scale of factors in juxtaposition to said indicator and reversed with respect to the two.scales,-one reading directly in proportion to the temperature of the stack gases, and the other reading inversely proportional to the percentage of carbon dioxide in the flue gases, an indicator co-operating with the temperature scale and movable directly proportional to the temperature ofA the stack gases, and a second indicator co-operating with the second scale and movable in direct proportion to the percentage of carbon dioxide in the flue gases, said scales being in line with each other and coordinated, whereby 'by multiplying the two readings the product will equal the loss of efficiency of operation of the boiler. i

In testimony whereof, I atix my signature.

JACG'B M. SPITZGLASS.

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