US2239595A - Humidifying apparatus - Google Patents

Description

April 22, 1941.

w. w. CUMMINGS, JR

HUMIDIFYING APPARATUS Filed Jan. 11, 1940 In (2612 for.

m eamq Patented Apr. 22,1941

. UNITED STATES PATENT OFFICE HUMIDIFYING APPARATUS William Warren Cummings, Jr., Marshfleld, Mass. Application January 11, 1940, Serial No. 313,387 7 Claims. (01. 261-15) This invention relates to a novel apparatus for humidifying dry air in an enclosed space.

- It is the primary aim and object of the present invention to devise an apparatus for humidifying dry air in an enclosed space without requiring the elaborate and expensive duct systems and the. large volumes of air circulation which are so essential in the conventional humidifiers to prevent condensation of the added water vapor in the air and secure its distribution.

- It is also among the objects of the present invention to provide a humidifying apparatus which is readily assembled into a self-contained unit of relatively small dimensions and lends itself to ready installation at'most anyplace,

Before explaining in detail the present invention it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawing, since the invention is capable of other embodiments and of being practiced or carried out in various ways.

Also it is to, be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation, and it is not intended to limit the invention claimed herein beyond the requirements of the prior art.

In the drawing the figure is a longitudinal section through a humidifier which embodies the present invention.

A In the drawing, the reference numeral l designates a suitably constructed container which is closed except for an air inlet l2 and an air outlet l4. The container is preferably placed in the enclosed space whose air is to be humidified. Suitably mounted in the container at the inlet l2 thereof'is a conventional shell and tube type heat exchanger 16 through which air must pass in order to enter the container in the manner indicated by the arrows I8. Also provided in the container l0 by transverse partitions 20, 22 is a reservoir 24 which contains water. Water from any suitable source is admitted to the reservoir 24 through a valve 26, having a conventional airfilled float 28 for controlling the valve so that the water level remains substantially constant. A suitable pump 30, driven by an electric motor 32, has its intake side in permanent communication with the water supply in the reservoir through a conduit 34, while its discharge side communicates through a conduit 36 with the intake end of any suitable heater coil '38 in a shell 40 whose bottom end is open to admit the heat from a gas burner 42 and whose top end communicates with a flue (not shown) for the escape of the products of combustion. The gas which. ignites the burner when gas from any suitable source is admitted through a conduit 44. To this end, a normally closed gas valve 46 in the conduit 44 is opened when a solenoid 48 is energized. The discharge end of the heater coil 3! communicates through a conduit 50 with the water-intake end of the heat exchanger it through which water flows counter to and sepa rated from the flowing air therein and in heatexchange relation with the latter. The water discharge end of the heat exchanger 66 is connected through a conduit 52 with a spray nozzle 54 which is adapted to spray hot water through the flowing heated air in the container andinto the reservoir 26. Suitable transverse baffles 565 and 58in the container cause the heated air to flow counter to water spray from the nozzle "at as indicated by the arrows 59. A horizontal partition 60 in the container together with the previously mentioned partition 22 therein forninot only a separate chamber 62, in which the motor driven pump 30 and the water heater 3&3, til and 42 are housed, but also an air duct (it from the inlet l2 to the reservoir 26. Provided on the earlier mentioned bafiie 5t and partition 22 and on an intermediate partition t6 are eliminator plates 68 past which'the heated and sprayed air fiows in the manner indicated by the arrows iii. These eliminator plates remove any moisture in suspension from the air stream. Suitably mounted in the container it as on the pedestal it, for instance, is a motor-driven ian t i whose discharge end communicates with the outlet it. The fan 14. when operating, draws air into the container through the inlet i2 and causes it to flow therein in the manner indicated by the arrows I8, 59 and I0 before being expelled through the outlet it.

L represents line wires from which branch leads l6 and '18 that complete the circuit for the pump motor 32 ii a switch in the lead It is closed. This switch 80 is so operatively associated with a humidostat H in the space whose air is to be humidified that said humidostat closes the switch when the humidity in said space is below a predetermined minimum, and opens said switch when the humidity is above said minimum. Parallel with the pump motor circuit is the energizing circuit for the gas valve solenoid 48 which consists of leads 82 and 84 that branch oil the leads I6 and I8, and any suitable limit switch 86 which is normally closed and is opened in response to a predetermined high water temthe circuit for the pump motor 32 may be closed by the action of the humidostat H, the energizing circuit for the gas-valve solenoid ll will be opened as soon as the water temperature in the conduit II reaches said predetermined high value at which the limit switch 88 will be opened. Also branching of! the leads I. and 18 are two leads 88 and Oil which complete a parallel circuit for the fan motor when any suitable thermostatic switch 82 in the lead 88 is closed. This happens when the temperature of the heated and sprayed air is sufllciently high to close the thermostatic switch 88.

In operation, the pump 3| starts to operate when the humidostat H closes the switch ll, with the result that water from the reservoir 24 is forced through the heater coil and the heat exchanger l6 from where it passes to the spray nozzle 54 and thence back into the reservoir, with the exception of whatever moisture has been absorbed by the air contacted by the water spray. The closing of the pump motor circuit results in immediate closing of the parallel cir- 'cuit for the gas valvesolenoid II, with the result that gas is admitted to the burner 42 and the gas is ignited by the automatic pilot. The temperature of the water flowing through the exchanger l6 and the spray nozzle 54 is thus raised until the water temperature in the conduit 5| becomes sufilciently high to cause opening of the limit switch as. When this takes place, the burner 42 becomes extinguished until the water temperature in the conduit 50 drops sumcienltly to cause re-closing of the limit switch It. The fan will not operate until the temperature of the sprayed air is sufiiciently high to close the thermostatic switch 92, thus avoiding the discharge of air whose temperature is so low that the water vapor carried thereby would condense at the temperature in the space. Actual tests have shown that diflerent moisture contents in contacting air masses will almost instantaneously have a common vapor pressure. Thus, where in a small part of a room a high temperature and a high relative humidity at a high vapor pressure is maintained and the rest of the room is at a lower temperature and a lower relative humidity at a lower vapor pressure, the moisture contained in the air in said small part of the room will flow, without necessitating any air motion, to the air in the rest of the room, i. e., to the lower vapor pressure. This phenomenon is used with great advantage in the present humidiiying apparatus, and the end iought is to obtain in the air which is expelled from the container 9. very high vapor pressure. In order to accomplish this, the air expelled from the container must have the high temperature at which such a high vapor pressure is possible. As the vaporization of the added moisture will entail heat losses, heat has tobe furnished in excess of that requii ed to bring the air which is to carry the added moisture to said high temperature. The spray water as well as the flowing air in the ontainer are accordingly heated by the water water 38, 42 and by the heat-exchange between be heated water and the indrawn air in the xchanger 16. Furthermore, the relative humidty of the expelled air must be sufliciently low to revent condensation of the water vapor therein iefore vapor transfer has taken place.

As a practical example, a heated room has been maintained at a temperature of 80 F. and per cent relative humidity (.44 inch oi mercury .perature in the conduit 5i. Thus, even though vapor pressure) by heating the spray water in the heater coil 38 to approximately 180 F., while the indrawn air was heated in the exchanser It and bythe water spray from the nozzle 54 to an approximate temperature of 150 F. Due to the heat losses on account of the evaporization oi the moisture, the temperature of the air expelled from the container had dropped to approximately 104 F. and its relative humidity was around per cent, corresponding to a watervapor pressure of 1.4 inches of mercury. Hence the vapor pressure differential at the outlet of the container and the rest of the room was 1.4-.-i4=.96 inch of mercury column, with the result that the vapor flowed immediately from the higher pressure to the lower pressure.

With the present method of moisture injection, only a very small amount of .air circulation is necessary, and that only within the container of the humidifier unit. Previously essential, expensive and bulky duct work for the equal distribution of the moisture about the space to be humidified is unnecessary and entirely eliminated, and condensation around the unit cannot take place at the high temperature maintained in the expelled air. Larger amounts of moisture may be injected faster than-with the customary humidifiers and at less cost as well as with less equipment. The humidifier itself is much smaller than present-day equipment for the same capacity, and the various controllers assure proper operation of the apparatus at all times.

While in the present instance gas is used for heating the water in the coil 38 and the indrawn air is heated by the heat-exchange between said heated water and air, it is fully within the scope of the present invention to use oil heat or steam in order to heat the water in said coil or the indrawn air in the exchanger It, or both. Thus, if steam is used, the shell 40 serves preferably as a steam jacket to which steam from any suitable source is permanently admitted. This eliminates the limit switch 8 and the solenoid-operated gas valve 46, and the water in the coil 38 is then always sumciently hot so that the thermostatic switch 92 in the fan-motor circuit may also be dispensed with. The thus heated water in the coil 38 may first flow through the heat exchanger IS in heat-exchanger-relation with the air fiowing .therethrough before being conducted to the spray nozzle 54, or said water may directly flow to said spray nozzle without first flowing through the heat exchanger, In the latter case steam from the same source is directly conducted through the heat exchanger IS in heat exchange relation with the indrawn air therein.

I claim: I l

1. A humidifier for a space comprising a container having an inlet and an outlet, first means for drawing air from said space into the container through said inlet and expelling it into said space through said outlet, means for heating the indrawing air, a water reservoir in the container, a water heater, a gas burner therefor with an automatic pilot, a normally closed valve for admitting gas to said burner, a solenoid opening said valve on being energized, a spray nozzle in the container in communication with said heater and adapted to spray hot water through the flowing heated air into said reservoir, an electric pump for forcing water from the reservoir through said heater to said nozzle, and parallel energizing circuits for said solenoid and pump, respectively, and including a common switch for simultaneously opening and closing said circuits.

2. A humidifier as set forth in claim 1, further including in the energizing circuit for said solenoid only a thermostatic switch which is opened when the temperature of the heated water is above a predetermined maximum temperature.

3. A humidifier as set forth in claim 1, in which said first means comprises an electric fan and an energizing circuit therefor including a thermostatic switch in the path of the heated air between the spray nozzle and outlet for closing the latter circuit when the temperature of said air is a-oove a predetermined minimum temperature.

4. A humidifier as set forth in claim 1, in which said first means comprise an electric fan and an energizing circuit therefor including a thermostatic switch in the path of the heated air between the spray nozzle and outlet for closing the iatter circuit when the temperature of said air is above a predetermined minimum temperature, and the energizing circuit for the solenoid includes a thermostatic switch which is opened when the .temperature of the heated water is above a predetermined maximum temperature.

5. A humidifier as set forth in claim 1, further comprising a humidostat in said space so operatively associated with said switch as to close the latter every time the humidity in said space is below a predetermined minimum.

6. A humidifier comprising a casing having an inlet and an outlet in its front and rear wall, respectively; a first partition in the casing dividing the same into two separate chambers and comprising a horizontal wall portion extending from said front wall below the inlet and a continuing vertical wall portion extending to the bottom of the casing at a distance from said rear wall; a second transverse partition in the casing between said vertical wall portion and rear wall and extending from the bottom of the casing into close proximity to the top thereof and defining together with said vertical wall portion a water-holding reservoir in the casing; two spaced transverse walls in the casing between and spaced from said vertical wall portion and second partition and forming a spray chamber above the reservoir, the transverse wall nearest said vertical wall portion extending from the top of the easing into close proximity to the water level in the reservoir and the other transverse wall projecting helow said water level and extending upwardly into close proximity to the top of the casing; a heat exchanger mounted at said inlet; a water heater in the smaller chamber in communication with the intake end of said exchanger; a pump in said smaller chamber having its intake end in communication with the water in the reservoir and its discharge end in communication with said water heater: a spray nozzle in said spray chamber near the top of the casing and communicating with the discharge end of said exchanger; an eliminator between said other wall and second partition; and a fan at said outlet.

'7. A humidifier as set forth in claim 6, in which said eliminator comprises a third transverse partition in the casing between said other wall and second partition and extending from the top of the casing into close proximity to the water level in the reservoir, and eliminator plates on those surfaces of said other wall and second and third partition which face each other.

W. WARREN CUIVINIINGS, JR.

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