US2192011A - Apparatus for preventing condensation in gas mains - Google Patents

Description

Feb. 27, 1940. KOLLE'R 2,192,011

APPARATUS FOR PREVENTING; CONDENSATION IN GAS MAINS Filed June 30. 1937 EUKNEE I .WST SEPHPAWZ INVENTOR KARL KOLL ER Patented Feb. 27, 1940 UNITED STATES APPARATUS FOR PREVENTING OONDENSA- TION IN GAS MAINS Karl Keller, Budapest, Hungary Application June 30, 1937, Serial No. 151,255

2 Claims.

This invention relates to the distribution of combustible gas containing condensable materials, particularly producer, gas made in a producer employing bituminous coal as the fuel.

In many plants, combustible gas containing tarry matter including tar acids and other condensable constituents, e. g., producer gas generated by blowing. air through a bituminous coal fuel bed, is cleaned by passage through one or .more washing and grid chambers or other cleaning equipment and the resultant cleaned gas distributed through a piping system to furnaces or other appliances where it is burned. In such plants, reduction of the temperature of the gas between the cleaning equipment and the point of consumption causes condensation of condensable constituents such as tarry matter in the lines leading to the burners, requiring frequent interruption of plant operations to clean the gas distribution conduits, meters, etc. Such interruptions, it will be appreciated, result in loss of time and labor in cleaning the distribution system and result in the formation of objectionable, dense clouds of smoke when the deposits of condensed material are burned to effect their removal. Moreover, in many plants where producer and other combustible gas is employed, the washing or scrubbing liquor from the gas washers contains tar acids, including phenols, and, therefore, cannot be discharged into streams. In many localities municipal ordinances prohibit the discharge of such waste liquors into streams and waterways. Hence, such waste liquors or ei'fluent present a difficult disposal problem.

It is an object of this invention to feed or distribute combustible gas containing condensable constituents such as producer gas made from bituminous coal in such manner that condensation of tarry material in the gas line is-minimized or substantially completelyeliminated.

It is a further object to distribute combustible gas such as producer gas as generated and without subjecting the same to water washing through the usual distribution systems in industrial plants so as to avoid objectionable deposits in such systems.

Other objects and advantages of the invention will appear from the following description:

In accordance with the invention, I. introduce into the distribution system hot gases atatemperature and in amount such that the combustible gas reaches the gas consuming appliances at a temperature above the dew point of the condensable materials therein. Preferably the combustible gas is superheated to a temperature such that it reaches the appliances at a temperature equal to or above the temperature of the gas entering the mains by burning a portion of the gas and conducting the hot products of combustion into the distribution system where it mixes with the combustible gas. Thus heat losses from the system as the gas flows therethrough are compensated by the hot gases added to the system, thereby preventing cooling of the gas to a point where substantial condensation of the condensable'materials will occur. Accordingly,- in plants where the waste liquors present the hereinabove mentioned disposal problem, water washing of the gas may be eliminated and condensation of tarry and other condensable constituents within the distribution system prevented by the practice of this invention.

The invention also comprehends apparatus for preventing condensation of condensable materials in a gas distribution system involving burners having combustion chambers communicating with the system, lines for supplying air to the burners, lines for supplying combustible gas to the burners and mechanism for automatically terminating flow of gas and air to the burners when the gas pressure in the system falls below a predetermined minimum.

A preferred embodiment of the invention is shown for purposes of exemplification in the accompanying drawing, wherein Fig. 1 is a view, somewhat diagrammatic in character of a gas distribution system equipped in accordance with the invention,

, Fig. 2 is a'view illustrating on an enlarged scale a portion of the apparatus of Fig. 1, and

Fig. 3 is a sectional view through a gas distribution main equipped in accordance with the invention.

Referring more particularly to the drawing, reference'numeral 8 indicates generally apparatus for producing combustible gas which may include a producer containing an incandescent bed of bituminous coal through which air is blown upwardly, the resultant producer gas passing off from the top of the producer through gas offtake l I. As is well known in the art, gas such as producer gas made from bituminous coal contains objectionable impurities and is ordinarily subjected to cleaning operations such as scrubbing in washing and grid chambers which result in partial cleaning of the gas. The eilluent liquor from the scrubbers contains tar acids including phenols and hence present a difficult disposal problem.

In the embodiment of the invention shown in Fig. l, the gas from the producer is passed not through scrubbers where it would be contacted with water or other liquid, but through a mechanical dust collector such as a cyclone separator l2. From this dust collector the gas is introduced into distribution main i6 equipped with branches l8 and 28 leading to burners 22 and 24 of furnaces 26 and 28 respectively. The burners 22 and 24 are ordinarily located some distance from the dust collector, as indicated by the broken mains connecting line l6 with furnaces 26 and 28, so that the gas is subject to substantial reduction in temperature due to heat losses between the dust collector and the furnaces. In order to avoid condensation of the tarry materials in the distribution mains, particularly the branch mains leading to the burners, thereby clogging the mains, meters, etc. and necessitat ing frequent shutdowns to clean out the mains, l have equipped the distribution mains for the gas at suitable points with burners, designated generally by reference numerals 38 and 32 in Fig. 1 and shown in detail in Fig. 3.

Each burner includes a valved air inlet 34 connected to an air supply line 35 equipped with a water seal 31 and combustible gas inlet 38 connected to gas supply line 4| equipped with water seal 43, refractory lined combustion chamber 45, electric heating element 41 and perforated flame spreader or distributor 48. The open end 6| of the combustion chamber projects into the gas distribution main, any suitable joint 63 being employed to form a gas tight connection between the main and exterior of the burner. The water seals 31 and 43 prevent back flow of air and gas through the lines supplying 86 and 4| respectively.

Gas supplied to the burners through supply line 4| may be clean gas available at the plant or may be bled off from the distribution system. For the latter purpose line 4| may be connected, e. g., to distribution main l6 at any suitable point.

In Fig. 2 I have illustrated somewhat diagrammatically an automatic mechanism for terminating the flow of air and gas to the burners in event the supply of combustible gas through the distribution main I6 is shut off or the pressure in the system for any reason falls below a predetermined minimum. The cutofl mechanism involves an air valve 68 in each of the air inlet conduits 34 and a gas valve 62 in each of the gas inlet conduits 39 to the burners. The gas and air valves for each burner are joined for simultaneous operation by connection 64 and each pair of valves 68, 62 is equipped with an operating lever 66 connected to cable 68 through branch cables 18; cables 68, 18 nm over pulleys 12. Cable 68 is connected at one end to a counter-weight 14 preferably constructed as a piston and sliding in cylinder 16 provided with an adjustable port 18. The piston and cylinder form in effect a dash pot to cushion the fall of the piston counter-weight upon release of the cable. 68 in a manner hereinafter described. The other end of cable 68 is wound on drum 88 equipped with ratchet 82 and manually operated handle 84. Detent 86 is rigidly connected at one end to lever 88 and the other end of the detent cooperates with ratchet 82. Lever 88 is pivotally mounted at 88 and equipped at one end with an adjustable weight 82. The other end of the lever is connected to bell 84 partially submerged in a body of liquid in bell tank 86. An extension 98 of gas line 4| terminates in and discharges gas into the space beneath bell 34 so that the pressure beneath the bell corresponds to the pressure in the gas line and distribution system.

The operation of the device is as follows:

When gas is passing through the mains 6, 8 and 28 to burners 22, 24, electric current is sup plied to heating element 41 to heat it to incandescence and levers 62 are manually lowered to permit flow of gas and air to the burners 38, 32; the incandescent heating element ignites the mixture of gas and air. The amount of gas and air fed to the burners may be controlled by adjustment of valves 68, 62 and is preferably such that the products of combustion from the burners impart to the gas flowing through the distribution system superheat in amount suflicient to prevent the temperature of the gas from falling below its dew point prior to reaching the burners. Upon drop of pressure in the distribution system, the pressure in line 4| and extension 88 also fails thus causing a drop in pressure beneath the bell 84. Air pressure forces the bell down causing rotation of lever 88 in clockwise direction about its pivot and raising of detent 86. When the pressure beneath the bell fails a predetermined amount, detent 86 is disengaged from ratchet 82 permitting weight 14 to unwind cable 68 from drum 88 and close air and gas valves 68, 62 by raising levers 66. When it is desired to again start the burners in operation, cable 68 is wound on drum 88 by turning handle 84, detent 86 engaged with the ratchet 82 and valves 62, 68 set to permit flow of the desired amount of gas and air to the burners.

Preferably the burners are located in the gas distribution system at points at which objectionable condensation begins to occur. The location of the burners may be influenced by many factors such as the length of the distribution system, the rate of heat loss from the gas flowing through the system, etc. While I have illustrated in Fig. 3 burners located in the branch distribution mains leading from main l6 to the burners, it will be appreciated that if objectionable condensation occurs in main l6, this main may be equipped with one or more burners at points where condensation begins to occur.

It will be noted this invention provides a process and apparatus for preventing condensation of tarry matter from combustible gases, in gas distribution systems, containing such matter by introducing into the mains at suitable points hot gases in amount and at a temperature sumcient to prevent lowering of the temperature of the gas below its dew point prior to reaching the burners. In accordance with my invention the gas as generated need not be washed and hence waste liquors which would present a dimcult disposal problem are not formed; and atof combustion into said main in amount and at a temperature suflicient to prevent the temperature of said combustible gas from falling below its dew point during flow through said main to its destination, means for feeding air to said burner, means for withdrawing a portion of the gas from said main and feeding, it to said burner, and means responsive to pressure conditions within said main for preventing flow of air and gas to said burner when the pressure within the main falls below a predetermined minimum.

2. Apparatus comprising in combination gas consuming appliances and a gas distribution system including a gas main and branch lines for feeding combustible gas containing condensable tarry constituents from said main to said consuming appliances, means for preventing deposition of said constituents in said system comprising a burner communicating with each of said branch lines for producing hot products of combustion, means for mixing said products of combustion'with the gas flowing through said lines in amount and at a temperature to compensate for heat losses from said combustible gas during its flow through said distribution system to said appliances, means including a valved conduit for supplying air to the burner, means including a valved conduit for withdrawing a portion of the combustible gas from said system and supplying it to the burner, and means responsive to pressure conditions in said system for automatically closing said gas and air valves when the pressure in said system falls below a predetermined minimum.

KARL KOLLER.

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