Patent GB-1067017-A (GB)
Title: Improvements in or relating to a controlled atmosphere generator
IPC: A23L3/3409
Filed: 1964-11-05
Abstract: <FORM:1067017/C1/1> An atmosphere having a controlled composition is produced in a receiver by utilizing an apparatus comprising a source of mixed gases, an absorber for removing undesirable amounts of preselected constituents including CO2 from the mixed gases, and control apparatus including means for controlling the flow of mixed gases from the source through the absorber into the receiver for a first preselected period of time, an adjustable timer, and means operable by the timer for directing the gases for a second preselected period of time directly from the source of mixed gases into the receiver thus maintaining a desired level of CO2 in the receiver.  The apparatus preferably also includes a source of air and an exhaust, the control apparatus including means for controlling the flow of air into said absorber from said air source to remove and dispose of said preselected constituents to exhaust, at least a portion of the air being retained in the absorber; means controlled by the timer for directing the mixed gases through the absorber to exhaust for a third preselected period of time to remove a preselected amount of air from the absorber and means controlled by the timer whereby the gas stream is subsequently directed through the absorber to the receiver to transfer the remaining amount of air in the absorber to the receiver to maintain a level of oxygen in the receiver.  In a preferred embodiment, illustrated in Fig. 1, two absorbers 70 and 71 are used, one of which is on stream to the flow of mixed gases whilst the other is being regenerated by passing air through it, the functions of the absorbers being reversed at the end of a cycle.  All the damper valves in the Figure are shown in the deactivated or spring-loaded position.  The source of mixed gases is a catalytic furnace 10, in which a gaseous hydrocarbon from pipe 11 is burnt in air from blower 13 to produce a gas stream in manifold 25 which, after condensation of condensable impurities in condenser 26 passes via pipe 44 into the arrangement of conduits and valves necessary to achieve the desired gas flow in the apparatus of the invention.  The operation of the apparatus is as follows:  when the furnace is first switched on the valve 45 is activated so that the initial combustion products pass directly to exhaust 49.  After this initial period valve 45 is deactivated and valve motors 59, 77 and 84 are energized via a cycle timer (not shown) so that absorber 70 is placed in circuit from condenser 26, and absorber 71 is placed so that it is regenerated by the air stream from blower 79.  Valve motor 67 is momentarily energized with the cycle timer, but the motion induced in damper 83 by motor 84 causes an air pulse to activate air switch 85 so as to activate a first variable timer (not shown) which immediately deactivates motor 67.  At this point gases from 26 flow through absorber 70, then through valve 65 to exhaust.  The time occupied by this flow to exhaust (the third preselected period mentioned above) is set on the first variable timer, viz. the oxygen timer.  At the end of this period, this timer activates the second variable timer, viz. the CO2 timer, and also motor 67 so as to move damper 66. The activation of the CO2 timer activates motor 53 to move damper 52, and as a result of the above, gas now passes from condenser 26 via valves 45, 51 and 65 directly to receiver 69. When the period set by the CO2 timer (second preselected period mentioned above) is over, motor 53 is deactivated, damper 52 returns to its original position, and the combustion gases now pass through the absorber 70 into the chamber 69.  The end of this period (first preselected period mentioned above) is achieved by the cycle timer which deactivates motors 59, 77 and 84, and energizes motors 61 and 89 to place the absorber 71 in circuit with the condenser 26, and absorber 70 on the air regeneration system.  The motion of damper 82 pulses air switch 85 again so as to activate the oxygen and CO2 timers for the next cycle. The apparatus is used for the production of desirable atmospheres in storage chambers for foodstuffs. The Specification contains details of the switch means and the circuitry necessary to control the time sequence; contains details of the construction of a preferred type of absorber, and also contains details of the preferred construction of the catalytic furnace.