US2680429A - Vertical indirect water heater - Google Patents

Description

June 8, 1954 o. M. OLSEN VERTICAL INDIRECT WATER HEATER 2 Sheets-Sheet 1 Filed June 23, 1950 8 v J2? venfoi" Oae J16 0256)? June 8, 1954 o. M. OLSEN VERTICAL INDIRECT WATER HEATER 2 Sheets-Sheet 2 Filed June 23, 1950 "Pate nted June 8, 1954 2,680,429 7 VERTICAL INDIRECT WATER HEATER Ove M. Olsen, Evanston, Engineering Company,

ration of Illinois 11]., assignor to Sellers Chicago, 111., a corpo- Application June 23, 1950, Serial No. 169,796

My invention relates to an improvement in water heaters, and has for one purpose to provide a heater adapted to heat water in large volume, for general commercial and industrial use.

Another purpose is to provide such a heater in which water is indirectly heated, for example by means of a copper tube heat exchanger located in an auxiliary tank, with the water being heated in contact only with the copper and not drawn directly from the heater proper.

Another purpose is to provide a heating apparatus and method to permit the heating of corrosive waters without rapid corrosion and destruction of the heater.

Another purpose is to provide such a heater in which water softened by Zeolite or other forms of water softeners can be heated without active corrosion or destruction of the heater.

Another purpose is to provide a heater adapted to deliver water in substantial quantities at at least two different temperatures.

Another purpose is to provide an improved heat exchanger assembly in combination with a water heater.

Another purpose is to provide a heating apparatus and method in which a fly wheel eflect is employed through the use of heat exchangers of materials the heat-absorbing capacity of which is substantially greater than would be required to absorb the heat provided by the burner used with the heater. 7

Other purposes will appear from time to time in the course of the specification and claim.

I illustrate the invention more or less diagrammatically in the accompanying drawings Wherein:

Figure 1 is a side elevation of the device;

Figure 2 is a section taken on the line 2-2 of Figure 1 on an enlarged scale; and

Figure 3 is a vertical cross section taken on the line 3-3 of Figure 2.

Like parts are indicated by like symbols throughout the specification and drawings.

Referring to the drawings, I generally indicates a hot water boiler or heater, herein shown as vertical, and normally filled with water. The Water in the heater surrounds a group or battery of firing tubes 2 in communication with a lower burner-receiving space 3 and an upper discharge space 4. 5 diagrammatically indicates any suitable burner. For convenience, I have illustrated a gas burner the details of which form no part of the present invention but it will be understood that any suitable burner may be employed,

1 Claim. 01. 122-32) and any suitable fuel. Under some circumstances,

an electric heater may be provided, but I find a gas burner practical. The ducts or firing tubes 2 carry the hot gases to the upper space 4, from which they are exhausted through any suitable flue or outlet 6 at the top of the heater.

Located adjacent the main burner or tank I is a storage tank or element 1. I illustrate the units I and 'i as of substantially the same size and vertical extension, arranged with parallel upright axes on a common base 8, on spaced ground or floor engaging supports 8a. The tanks are shown as connected or surrounded by any suitable housing element 9. 9a indicates an access door to the space between the tanks, and 9b an access door for the burner space 3. It will be understood, that the details and proportions of the above-described elements may be widely varied.

The space within the tank or heater I, which surrounds the firing tubes 2, is connected at top and bottom with the interior of the storage tank 7. I illustrate, for example, a top duct or pipe l0 and a bottom duct or pipe II, which are located adjacent the horizontal top partition l2 and the horizontal bottom partition I3, respectively. The space between the partitions I2 and I3, and surrounding the fire tubes 2, is thus put in communication with the space within the storage tank I, both spaces being normally filled with a suitable heat storage liquid, such as Water. As will later appear, this water is not exhausted for use but serves as a heating and heat storage medium for the below described heat exchange elements within the storage tank 1. I4 indicates any suitable cold water inlet for admitting water to the interior of the boiler or heater I. It will be understood, of course, that any suitable means, passages or connections, may be employed for from the interior of each tank.

It will be understood that as the liquid in the heater I increases in temperature, due to the action of whatever burner is employed, a rapid circulation of water is thereby set up between the interiors of the heater I and of the storage tank 1. The storage water moves rapidly upwardly in the tank I, and rapidly downwardly in tank I, with what approximates a piston action. This continues until the contents are at approximately the same temperature. thermostatic means may be employed for cutting off the main burner 5 when the temperature of the common body of storage water reaches a predetermined maximum. I illustrate the bulb 5a:

admitting or removing water Any suitable r which may be appropriately connected to the burner 5. For example, it may be set at or about, or between 210 degrees to 220 degrees Fahrenheit.

Located within the storage tank 1 I employ 5 one or more heat exchangers of any suitable design and material. I prefer to employ copper, because of the superior heat-trarisfer capacity of that material, but I do not wish to be limited specifically to the employment of copper, since other materials of high heat-transfer capacity may, under some circumstances,advantageously be employed.

Considering the exemplificatio'n of my: inven tlon as shown in the drawings"; I illustrate a? spiral l5- copper tube heat xchanger having an inlet pipe 16 and an outlet pipe ll extending to any suitable water mixer or blender t8, the function of which is below discussed. it indicates a' sec and heat exchanger in the form of a U-shaped 20 tube; one arm of which is' connected, as by-the pipe 20, with the outlet ll of the heat exchanger- IS; The outlet temperature of the water'from the heat exchanger or coil leis controlled by means-of a second water mixer or blender' 2-5. The blendersmay be thermostaticallycontrolled, such controls not of themselvesviorming part of my invention. The water boiler i and storage tank I may be surrounded with any suitable'insulation as indicated at 22.

It will be realized that, whereas, I- have'de scribedand illustrated a practical and operative method and device, nevertheless many change maybe made in the size, shape, number and dis position of parts without departing from the spirit of my invention. I therefore wish my de'-" scription' and drawings to be-taken as in abroad sense illustrative or diagrammatic, rather than as limiting me to my precise showing. For ex-" ample, whereas I illustrate a multiple tank sys- 4O tem, I-do'not wish to be so limited.

Theme and operation of the invention are as follows:-

Let it be assumed as an illustrative example that-a. temperature of from 210 degrees to 226 degrees Fahrenheit is maintained in' the heat storage liquid contained in the heater tank 1 and-inthe storage tank i; The incoming watei entering the heat exchange coils or elements it" and i drapidly becomes heatedby'absorbing' heat from'the liquid in the storage tan 1-. It maybe heated to a temperature somewhat'in excess ofthe desired outlet temperature, but the outlet temperature may be controlled by any suitaole thermostatically controlled mixersor blenders it and 21, which add coldwater from any suitable connections to bring about the desired operating or delivery temperature.

In the embodiment of my invention herein shown I take advantage of the heat-absorbing capacity of the copper tube heat exchangers which is several times greater than wouldbe re quired to absorb the heat provided by the burner andwhich thusproduces what I may call a fly wheel effect. The heat stored in the body oi liquid contained in the two tanks is available for absorption by the heat exchanger coils 15' and 19, in addition to the heat which is currently being put into the water in the tanks by the burner. The user thus has'available the'heat stored in the water contained in the two tanks, and the use of copper tube heat exchangers of sufficient capacity to absorb this stored heat, aswell as the burner delivered heat, increases the eiiiciency of the heater. Ihus;'.-instead of storing 7 5- heated water available for use, I store heat, and make the heat of a liquid heat storage body available to the user. An outstanding advantage of my structure and method rests in the fact that the water being used does not contact the interior of the tank I or of the storage tank 1. On the contrary, it flows only through the coils l5 and G9 which" are resistant to corrosion, and which, after a proper life period, may readily be removed and replaced by removal of the cover elements or closure caps 25 and 26, respectively.

Another highly advantageous feature of my system is that although the second coil or heat exchangemember ie'draws heated water which ha's'already been pre-heated in the coil or heat exchange member i5, it does not normally interfere with or reduce the heat-absorbing capacity of the heat exchange member 15. It is only when ther'e is a demand for the more highly heated water produced by the heat exchange member l9 that it-drawson the coil or heat exchange member l5; Except when there is a call for the more' highly heated water, a static supply ofheated: water is maintained in the heat exchange mom-'- ber 19, with no flow into it or out of it. By ther mostatically controlling the two blenders, and by setting one blender at, for xample, degrees Fahrenheit, and the other at, for example, degrees Fahrenheit; I-maintain-adequate deliveryor" water at two temperatures;

While I do not wish to be limited specificallyto the forms and relationships of tani; shown; I find it highly advantageous to employ a vertical heater with a vertical storage tank mounted-ad--- jacent to it, with the interiors of the tanks'connected'to bring about a rapid'circulation of liquid between the two tanks in response to heating the liquid in one of the tanks,- the two tanksbeing arranged, side by side, and at about thesame level. For convenience of mounting, the tanks may be made of thesame, or substantially the same. size, as well'asshape.

With my structure I easily supply water at two-different temp-eraturss'without the need of using any booster heater. This is of advantage in restaurant installations. where the propor- "io'ns of low and high temperature Water vary continually during the period of use. I-Ii, =;htemperature water may be used in the'rinse spray's of dishwashing machines. Low temperature water may be used for various miscellaneous purposes, such as ore-rinsing dishes before they enter the washing machine, cleaning pots and pans in scullery sinks, and for general use in' lavatcries, etc. When the washing machines are not being used, and there is no call'foi' high temperature water, the entire capacity of the" main heat exchanger is' available for supplying water at the lower temperatures. It is only when higher temperature water is called for that water is drawn through the supplemental or booster coil it. Otherwise, there is no flow of water alongthepipeor connection 28; and the entire delivery of water along the pipe l'i flows through'the main heat exchanger coil 55; A requirement of dishwashing machines is that a high rate of flow of high temperature water necessary for a period of approximately ten secondsout' of every minute of operation. momentary, but high, output may be me volume of from one-half to three gallons of'water. The capacity provided by my temperature coil is such: that all,-or alarge part, ofthe' necessary volume ofhigh temperature water is stored withinthe coil, and-is thus available'forinstant use.- Since the requirement for high temperature water at the high rate is for a period of approximately ten seconds, with a stand-by period of approximately fifty seconds in each cycle of operation, the contents of the coil are brought up to the desired temperature during the stand-by period, and the necessary volume of high temperature water is available when the call for high temerature Water comes.

The equipment shown has the advantage of occupyin a small amount of floor space, due to its compact assembly and arrangement. I employ large-diameter copper tubes in the heat exchangers, which materially reduces the likelihood of scale formation in the tubes when used on hard water. The probability of scale formationis further reduced, as compared with the direct fire instantaneous type of copper water coil heater. In my unit the temperature differential between the water on the outside of the coils I5 and I9 and the water being heated on the inside is very low, approximately 10 degrees to 70 degrees Fahrenheit. In direct-fire instantaneous heaters, on the contrary, the differential may frequently be as high as 2,000 degrees Fahrenheit, due to the high temperature of the gas flame on one side of the coil and the low temperature of the water being heated on the other side or the coil wall. This high differential greatly accelerates the formation or scale inside the coils, a factor which is entirely avoided by my structure.

I diagrammatically illustrate, in Figure 3, a pump 1 la. In most instances, it is not necessary to use such a pump, but, under some circumstances, in order to accumulate a control circulation, such a circulating pump in the line or pipe I lfconnecting the two tanks, is of value. It may serve the dual purpose of maintaining a substantially absolute uniformity of temperature throughout the entire system, and of increasing the heat transfer rate or capacity of any given heat exchanger. For example, velocity of the liquid surrounding a copper coil is an important factor in determining the rate at which heat is transferred through the coil.

I claim:

In a water-heating system, a heat storage unit divided into two generally upright containers, each having a chamber adapted to receive and contain a body of liquid, the chambers being interconnected for liquid transfer generally adjacent their tops and bottoms respectively to form a closed circulating system, a heater for heating the liquid in one of the said containers, generally upright flue elements passing through the chamber in the said one container to facilitate the heating of the liquid in that chamber, and an elongated heat exchange member positioned in the other container and extending into its chamber in the path of the closed circulating system and having a substantial amount of heat exchange area for contact with the liquid, the liquid in the closed circulating system generally flowing upwardly in the chamber of the said one container and downwardly in the chamber of the said other container, the elongated heat exchange member being insertable and withdrawable through the top of the said other container, said elongated heat exchange member having an inlet adapted to be connected to a source of water supply to be heated and an outlet connection for the delivery of heated water, the elongated heat exchange member extending from the top of the chamber of the said other container approximately to the bottom and including two heat exchange elements, one of the elements including the inlet connection adapted to be connected to the source of water to be heated and the outlet connection for the delivery of heated water and the other heat exchange element having an inlet connection from the outlet connection of the said one heating exchange element and a separate outlet connection for the delivery of heated water from the other heat exchange element, the said one heat exchange element having a substantially greater amount of heat exchange area than the other.

References Cited in the file of this patent '7 UNITED STATES PATENTS Number

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