US1761975A - Preheater apparatus for oil burners - Google Patents

Description

Patented June 3, 1930 UNITED STATES ARTHUR J. BAIRD, OF PORTLAND, OREGON PREHEATER APPARATUS FOR OIL BURNEES Application filed December 10, 1928.

This invention relates to improvements in apparatus for preheating fuel oil for maintaining combustion in oil-burning furnaces, and particularly of the type of apparatus described and claimed in my prior patent application Serial No. 229,145), filed October 27, 1927.

The principal object of my invention is to provide simple and self-regulatory apparatus tor heating fuel oil preparatory to its injection into a furnace and to maintain the temperature of the oil above a predetermined minimum whereat the oil atomization is productive oi most eflicient results in combustion.

A further object or" the invention is the provision in preheating apparatus for oil burners 0t steam-heating and electric heating elements in operative conjunction and whereby the electric heating devices may be utilized prior to the raising of sufiicient steam for heating purposes or when the steam heat fails for any reason, said auxiliary electric heating devices being constantly available automatically under effective thermostatic controls. v

w A still further object of my invention is the provision in a preheater for oil burners of a venting device communicatively connecting the heating chamber wherein the oil is warmer. for delivery to the burner and the passage for the cold oil into such chamber whereby gases generated in the heating chamber may be withdrawn from the chamher to he mingled with and absorbed by the incoming oil and thus avoiding the danger of accumulation of gases in the chamber.

Other objects and advantages residing in my invention and objects relating to details of construction and relative arrangements of parts thereof will be readily apparent in the course of the detailed description to follow.

The accompanying drawings illustrate by 'ay or' example a preferred term of my invention, in which:

Figure l is a View substantially in medial vertical section of an embodiment of my invention with accessory parts thereof shown in side elevation.

Fig. 2 is a top plan view of the main body Serial. No. 324,902.

of my improved preheater as on line 22 of Fig. 1.

Fig. 3 is a view in side elevation of the invention with the thermal control apparatus removed, and with the lower portion of the preheater shown in section.

Fig. 4 is a view in horizontal section on line st of Fig. l.

i-leterring to said views, the reference numeral 1 indicates a casing having a substantially cylindrical heating chamber 2 which is closedat its bottom by a plate 3.

At the upper end the casing is formed with a laterally directed L-eXtension 5 having a discharge chamber 6 therein open to its full extent from the heating chamber. A discharge-pipe '2' for the heater oil extends through the bottom wall of the extension to near the top thereof where its opening 8 for the ingress of the oil is in close proximity to the top of the chamber 6 so that only the warmest oil in the heating and discharge chambers will be withdrawn. The discharge pipe is communicatively connected to a burner of any type.

Upon the opposite side of the casing a pipe 10 leads from a source of oil supply under pressure and is communicatively connected with a vertically disposed passage 11 formed in the casing wall. The pressure upon said oil supply may be applied by means of a gravitational system or through a pump, not shown. The oil issuing through the passage 11 takes a vertically upward course and passes through a cell 12 formed in the casing whence the oil flows downwardly through a passage and inlet port 15 into the heating chamber adjacent its bottom.

A steam-coil 16 is connected at one end centrally of said bottom plate with a pipe 17 through which the condensations are earried to a steam-trap 18. The opposite end of said coil extends through the upper wall of the casing where it is connected to a feed-pipe 19 extending from a boiler for generating steam, not sh( vn, to which the apparatus pertains-4.

The numeral 20 indicates an. electric heating element of the immersion type extending, preferably, through the upper wall of the casing and into the chamber 2 centrally of the steam-coil spirals.

At the upper end of the heating chamber 2 atube 21 extends through the interior wall 22 separating the chamber from the cell 12 and communicatively connects said chamber and cell through its bore 23. The tube is of relatively small bore and extends to within close proximity of the opposite side wall of the cell and beyond the upper end of the passage 11 so that oil flowing through the passages and cell cannot readily pass by way of the tube into the heating chamber. A screw-plug 25 is screwed into the easing-wall opposite the tube 21 through which the tube may be cleaned it it should become clogged for any reason. Said plug may be formed with a recess 26 on its inner side into which the tube may extend.

A thermally cont-rolled switch housed in the box 27 is rigidly mounted on the casing through having;- its ther iostatic element 28 extender. horizontally into the discharge chamber 6 along the lower portion thereof and spaced below the opening 8 of the discharge pipe. Said switch is adapted to make and break a circuit formed by wires 30 and including the heating element 20 whereby current is supplied to the element as a heating agency for the oil in the heating chamber (hiring such times as the temperature Oi the oil therein remains below a predetermined degree of heat for which the switch is set to break the circuit and as actuated by the thermostat Such temperature atwhieh the switch is open ated to break the circuit is desirably set at a degree of heat somewhat less than the heat of the steam supplied to the coil 16 or at about 1. 10 degrees Fahrenheit at which tem 'ierature he oil. is tound to atomize at high el'liciency.

A thermometer 31 may be likewise mounted upon the casing and extended therethrough in a. heat-responsive element 32 into the discharge chamber 6.

The operation of my improved preheating: apparatus may be briefly described as follows With the apparatus assembled in operative condition as described and illustrated and assuming that the fire is extinguished in the furnace, as in the "case of starting; the heating plant at the beginning of a day. the current is turned through the wires 30 as by a manually operated switch, not shown, wh ch will energize the heating element to heat the oil in the chamber 2 with which it is in Contact. When the oil is warmed it rises and fills the discharge chamber at the top of the casing and when suliiciently warmed as determined by the thermometer 31 the oil pump not shown, or other teed or atomisaing agencies requ red to inject the oil into the furnace are actuated whereupon the oil is forced through the pipe 7 to the oil-burner under pressure while an equal amount on;

ters through the supply pige and circulated through the pan-sages ll and 13 and heated in the chamber 2 where it flows upwardly while being subjected to the heat (it the elecic element.

its soos s steanii is raised sulliciently in the boiler to cute the coil l6 the heat therel'roni jo ns with the electrically generated heat to warm the oil until the latter reaches the predetermined temperature at which the z-iwitch controlled by the thermostat 28 is set to break the electric circuit whereupon the steani-coil is relied upon to furnish the enire amount o'l heal utilized unless the steam h at in the coil shoual be insufficient at any time to maintain the oil circulating through the pr enter at or above the prearranged minimum tempo 'ature at which the switch is set to close the circuit and again energize the heating element. Such utilization. ol: the electric heatingelement as an auxiliary heating agency to the steam-coil as well as a preheater may tilit. place frequently during the daily operation of the furnace and in practice it found that the thermally controlled switch may be relied upon during the hours when the Furnace is not in operation to maintain th oi l in warm condition during such idle p ls and in readiness for operation at any time and with a Very small additional consiniririon of electric current.

It is found tha the Vapors arising from the heated oil. will sometimes accumulate in the heating chamber and force the oil back into the supply pipe unti the heating chamber is more or less emptied of oil. This will happenv principally when the electric heating element is turned on and the burner is not in use, resulting in a serious obstacle to a proper circulation of the oil in the chamber. To guard against such collection o'lf gases I have provided the tube 21 forming: a communication between tl e upper end of the heating chamber 2 and the cell 12 so that any cases formed in the chamber will be carried into the cell. to be absorbed hvthe incoming: cold oil or in case. the low of oil is stopped as by closing down the furnace the gases will escape through the supply pipe without danger of emptyi the heating chamber.

he provision of the discharge chamber as an annex to the heating chamber and the location oi the discharge pipe opcnino' rela tive to the thermostatic element through whose action the automatic switch is regulated whereby the oil at the top of the chamher and which is drawn oft at its highest temperature while the thermostat is situated at a lower elevation and is surrounded by a strata of cooler oil thus promoting eiliciency in ensuring that the oil issuing from the up paratus is always warmed to a si'iitable degree and that the act on of the thermostat is moderated and the actuation of the switch only takes place when there is considerable reserve supply of properly heated oil.

WVhile I have described my invention for convenience and brevity as operative With steam-heating appliances it Will be apparent that the apparatus is equally effective When utilizing hot Water as a source for Warming the oil in the chamber 2 and Which requires only the provision of the usual pipe connections to the boiler in addition to the ap pliances shown in place of the steam-trap 18 to establish a return circulation in a Well understood manner and which is deemed the full equivalent with the employment of steam and is so intended to apply both in the description and the claims relating to my improvement.

Having described my invention, What I claim is:

1. A preheater for fuel-oil, comprising a casing having a heating chamber communicatively connected With a source of oil supply under pressure and a discharge chamber in said casing communicating with the upper end of said heating chamber, a steam-coil in said heating chamber, an electric circuit ineluding a heating element extending int-o said heating chamber, a discharge pipe arranged to Withdraw oil from near the top of said discharge chamber, and a thermostatically controlled switch having a thermostatic element extending into said discharge chamber at an elevation below the opening into said discharge pipe and adapted to make or break said circuit in response to changes in temperature of the oil.

2. A preheater for fuel-oil, comprising a casing having a heating chamber and a discharge chamber opening out of the upper end 'of the heating chamber, an inverted U-shaped supply passage for oil having a ported opening into the heating chamber at the lower end thereof, a vent tube between the upper end of the heating chamber and said passage to ad mit of the escape of gases from the heating chamber, a steam-coil extending into said heating chamber, an electric circuit including a heating element extending into said heating chamber, and an electric circuit breaker included in said circuit thermally controlled by a thermostatic element extending into said discharge chamber.

3. A preheater for fuel-oil, including the apparatus described in claim 2, together With a discharge pipe in the discharge chamber having its Withdrawal opening disposed at a higher elevation than the thermostatic element of the circuit breaker.

i. A preheater for fuel-oil, consisting in a casing having a heating chamber therein, a steam-coil and an auxiliary electric heating element extending into said chamber to heat the oil therein, said heating element being included in an electric circuit, a circuit breaker in said circuit, a thermostatic element extendchamber.

ARTHUR J. BAIRD.

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