Abstract:
An incinerator for waste liquid comprises a container, a burner and an atomizer. An incineration chamber is defined inside the container. The incineration chamber has upper and lower sections, and the container has a vent adjacent to the upper section of the chamber. The burner is connected to the container near the lower section to jet flame into the chamber. The atomizer is connected to the container near the lower section to shoot atomized waste liquid upwardly into the chamber such that waste liquid shot out of the atomizer is directed toward the upper section. 
     A method of incinerating waste liquid comprises the steps of jetting flame into the lower section of an incineration chamber having a vent adjacent to the upper section thereof, and shooting an atomized waste liquid upwardly into the lower section so that the atomized waste liquid is directed toward the upper section.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to a device for incinerating waste water or waste solution (which water or solution will hereinafter be referred to as “waste liquid”), and more particularly to a waste liquid incinerator capable of efficiently incinerating both waste liquid and waste gas or waste air at the same time. The invention also relates to a method of incinerating waste liquid. A typical waste liquid useful in the invention contains a gas such as ethylene oxide. A typical waste gas useful in the invention is ethylene oxide. Waste air useful in the invention is that containing a malodorous substance such as an unsaturated organic compound. 
     A great amount of ethylene oxide has been used for the disinfection and sterilization of medical equipment. Used ethylene oxide is treated typically as a waste gas and thus is incinerated. Beside this, ethylene oxide, as being water soluble, tends to be present in a dissolved form in the water within transportation means such as a water seal pump. It is common that such water with dissolved ethylene oxide is stored and eventually incinerated as a waste liquid. Known as devices for incinerating waste liquid are vertical and horizontal incinerators. 
     A typical horizontal incinerator has a container including a horizontal tubular side wall and a pair of opposing end walls closing the opposite ends of the side wall. One of the end walls is provided with a burner, and the other end wall is with an inlet for waste liquid. The burner flame is jetted horizontally into the container toward the other end wall while waste liquid is sprayed downwardly from the inlet, which allows the sprayed waste liquid to be incinerated. In this type of incinerator, however, waste liquid is sprayed exclusively over the area remote from the burner flame in order to avoid the flame extinction due to the sprayed waste liquid. 
     Because of the above arrangement, the horizontal incinerators have the following drawbacks: (1) the internal temperature of the container tends to decrease to the extent that it is hard to carry out the complete incineration; (2) it is difficult to design a small-sized container; (3) a large installation space is required; (4) the equipment cost is high; (5) the heat efficiency is low which results in high energy consumption; and (6) a large amount of nitrogen oxide tends to be generated due to a high flame temperature, which may be a cause of photochemical smog, an environmental pollutant, when released into the atmosphere. 
     A typical vertical incinerator has a container including an upright tubular side wall and top and bottom opposed walls closing the upper and lower ends of the side wall. The side wall is provided at its midriff with a burner, and the top wall is with a waste liquid inlet. This arrangement is disclosed, for example, in Japanese Patent Application Laid-Open No. 4-283309. The burner flame is jetted horizontally into the container while waste liquid is sprayed downwardly from the inlet, resulting in the incineration of the sprayed waste liquid. In this incinerator, waste liquid is again sprayed over the area remote from the burner flame to avoid the extinction of the flame. Because of the arrangement similar to the horizontal incinerators, the vertical incinerators cannot be free of those similar to the above drawbacks (1)-(6). 
     What is needed, therefore, are an improved incinerator for waste liquid and an improved method of incinerating waste liquid. Such an incinerator and a method should provide better heat efficiency to allow the design of a small-sized incineration container, allow quick heating and rapid vaporization of waste liquid to encourage the complete incineration of the waste liquid, enable the incineration of a large amount of waste liquid in its smallsized container so that a less installation space is required, reduce the equipment cost, reduce the energy consumption while providing dependable heat efficiency and assure a low flame temperature to inhibit formation of nitrogen oxide. 
     SUMMARY OF THE INVENTION 
     According to the invention in one form, a waste liquid-incinerating device is provided. The device includes a container defining an incineration chamber, a burner for jetting flame into the chamber, and an atomizer for shooting atomized waste liquid upwardly into the chamber. Both the burner and the atomizer are connected to the container near the lower section of the chamber. The container has a vent adjacent to the upper section of the chamber. The waste liquid sprayed by the atomizer is directed toward the upper section. 
     In a preferred embodiment, the container comprises an upright tubular side wall having a cylindrical inside surface defining the incineration chamber. In this embodiment, the burner is held by the side wall and is disposed such that flame is jetted out of the burner in the direction along a horizontal line tangent to the inside surface of the side wall. The burner may comprise a tubular burner nozzle which is directed such that the tube axis of the burner nozzle is disposed substantially horizontally and out of alignment with any radial line of the cylindrical inside surface. The container may further comprise a bottom wall at the lower end of the side wall, and the atomizer may comprise an upwardly directed spray nozzle held by the bottom wall. Such a spray nozzle may be directed such that the tube axis of the spray nozzle is disposed substantially vertically and in general alignment with the cylinder axis defined by said cylindrical inside surface. The container may further comprise a top wall at the upper end of the side wall, and the vent may be defined in the top wall. 
     In another preferred embodiment, the device further comprises a first source for supplying a combustion-improving gas to the burner, a second source for supplying a waste liquid to the atomizer and a third source for supplying combustion air to the burner. 
     In a further preferred embodiment, the device further comprises a fourth source for supplying a waste gas or waste air to the device. 
     In a further preferred embodiment, the device further comprises a temperature sensor for detecting the temperature of the chamber. A suitable control device may be used in the incinerating device to control the intensity of the burner flame in response to the temperature information provided by the temperature sensor. 
     According to the invention in another form, a incinerating device is provided which comprises a container, burner means and atomizing means. The container includes an upright tubular side wall having a cylindrical inside surface and top and bottom walls. The upper wall is provided with a vent. The burner means is held by the side wall to jet flame into the container in the direction along a horizontal line tangent to the inside surface of the side wall. The atomizing means is held by the bottom wall to shoot atomized waste liquid upwardly into the container. 
     In a preferred embodiment of the second form, the burner means comprises a tubular burner nozzle. The burner nozzle is directed such that the tube axis of the burner nozzle is disposed substantially horizontally and out of alignment with any radial line of the cylindrical inside surface. 
     In another preferred embodiment, the atomizing means comprises an upwardly directed tubular spray nozzle. The spray nozzle is positioned such that the tube axis of the spray nozzle is disposed substantially vertically and in general alignment with the cylinder axis defined by the cylindrical inside surface. 
     The present invention further provides a method of incinerating waste liquid. The method comprises the steps of jetting flame into the lower section of an incineration chamber having a vent adjacent to the upper section thereof, and shooting an atomized waste liquid upwardly into the lower section so that the jetted atomized waste liquid is directed toward the upper section. 
     In a preferred embodiment, the chamber is defined by an upright cylindrical inside surface of a container, and the jetting step comprises jetting the flame in the direction along a horizontal line tangent to the inside surface. The method may further comprises the step of guiding the jetted flame along the inside surface of the container so that the flame surrounds the cylinder axis of the cylindrical inside surface. The shooting step may comprise directing at least some of the atomized waste liquid upwardly along the cylinder axis so that some of the atomized waste liquid drives through the surrounding flame. The guiding step may comprise guiding the flame circumferentially along the inside surface while attracting the flame toward the vent so that the flame climbs the container along a helical path on the inside surface and forms within the chamber a vortex of flame around a vertical axis. The vertical axis of the vortex may be generally coincidental with the cylinder axis, and the shooting step comprises directing at least some of the atomized waste liquid upwardly along the cylinder axis so that some of the atomized waste liquid drives through the center of the vortex. 
     In another preferred embodiment, the jetting step comprises mixing a waste gas with a combustion-improving gas and burning the mixed gas to form the flame. A preferred waste gas is ethylene oxide; however, other waste gas may be used with the invention. A preferred combustion-improving gas is a self-sustained combustion gas such as propane or other town gas. The waste liquid useful with the invention may be any liquid that can be incinerated and it includes, but not limited to, water containing ethylene oxide having been used for the disinfection and sterilization of medical equipment. 
     Other objects and advantages of the present invention will be apparent from the following description, the accompanying drawings and the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, 
     FIG. 1 is a schematic vertical cross section of a waste liquid incinerating device according to the present invention; 
     FIG. 2 is a view taken along the line II—II in FIG. 1; 
     FIG. 3 is a schematic system diagram of the device in FIG. 1, showing the supply lines for and the flow directions of the waste liquid, the gases and the combustion air, fed from the respective supply sources; 
     FIG. 4 is a schematic vertical cross section of a second embodiment of the present invention; and 
     FIG. 5 is a schematic system diagram of the device in FIG. 4, showing the supply lines for and the flow directions of the waste liquid, the gas, the combustion air and the waste air, fed from the respective supply sources. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 and 2 illustrate a vertical incinerator according to the invention. The incinerator, designated by reference numeral  12 , is designed for incinerating a waste liquid such as a water solution of a combustible gas as well as for incinerating a combustible waste gas. The incinerator  12  has a vertically elongate container  14  including an upright tubular side wall  16 , a top wall  18  and a bottom wall  20 . The top wall  18  is joined to the upper end of the side wall  16  to partially close the upper end while the bottom wall  18  is joined to the lower end of the side wall  16  to close the lower end. The side wall  16  has an upright cylindrical inside surface  19 . Defined by the walls  16 ,  18  and  20  is an incineration chamber  21  where the waste liquid is incinerated. 
     A burner  22  is connected to the container  14  to shoot flame into the lower/combustion section of the chamber  21 . The burner  22  includes a nozzle  24  passing through the side wall  16  near the bottom wall  20  and held by the same. The nozzle  24  is directed inwardly of the container  14  such that the tube axis X—X (shown in FIG. 2) of the nozzle  24  is disposed generally horizontally and out of alignment with any radial line, such as at reference numeral  27 , of the side wall  16 . Stated differently, the tube axis X—X is parallel to a horizontal line  25  (shown in FIG. 2) tangent to that portion of the inside surface  19  adjacent to the nozzle  24 . The top wall  18  is provided with a vent pipe  36 . Thus, the flame jetted out of the nozzle  24  is attracted toward the vent pipe  36  while guided by and extending circumferentially along the cylindrical inside surface  19 . This causes the flame to climb the side wall  16  along a helical path on the inside surface  19 , which results in formation, within the chamber  21 , of a vortex of flame around a vertical axis that is generally coincidental with the cylinder axis Y—Y (shown in FIG. 1) of the side wall  16 . 
     The burner  22  has a fuel inlet tube  26  as well as a combustion air inlet  28 . The inlet tube  26  is formed with both a waste gas inlet  26   a  and a combustion-improving gas inlet  26   b . As shown in FIG. 3, the burner  22  is connected to a waste gas supply source  84 , a combustion-improving gas supply source  86  and a combustion air supply source  72  through supply lines P 2 , P 3  and P 4  respectively so that the inlets  26   a ,  26   b  and  28  are in fluid communication respectively with the supply sources  84 ,  86  and  72 . 
     An atomizer pipe  30  is connected to the container  14  to shoot a waste liquid into the chamber  21 . As best shown in FIG. 1, the atomizer pipe  30  has an upwardly directed spray nozzle  32  passing through the center of the bottom wall  20  and held by the same. The tube axis of the spray nozzle  32  is disposed substantially vertically and in general alignment with the cylinder axis Y—Y. Thus, at least some of the waste liquid jetted out of the spray nozzle  32  is directed upwardly along the cylinder axis Y—Y so that it drives through the vortex of flame formed within the chamber  21 . 
     As best shown in FIG. 2, a protection air supply pipe  34  is disposed alongside the atomizer pipe  30 . The forward end of the supply pipe  34  extends inwardly of the container  14  through the bottom wall  20  and is directed to the spray nozzle  32 . This allows the air from the supply pipe  34  to blow on the spray nozzle  32  so that the spray nozzle  32  is cooled and thereby prevented from being excessively heated. A door  35  is movably connected to the side wall  16  to cover a manhole in the side wall  16 . Such a manhole is used for the inspection of the chamber  21 . A muffler  38  is provided at the middle of the vent pipe  36 . Reference numeral  39  designate support legs of the container  14 . 
     A temperature sensor  40  (shown in FIG. 1) is secured to the top wall  18  to detect the internal temperature of the container  14 . A suitable control device (not shown) is used to control the amount of the fuel (i.e., the combustion-improving gas) supplied to the burner  22  in response to the temperature information provided by the temperature sensor  40 . This assures that the minimum amount of fuel required to operate the incinerator is supplied. 
     Referring to FIG. 3, a waste liquid supply line P 1  connects between the atomizer pipe  30  and a waste liquid tank  42  to supply a waste liquid “W” in the tank  42  to the pipe  30 . A pump  44  is provided to drive the waste liquid “W” through the supply line P 1 . Reference numeral  45  denotes a pressure gauge connected to the supply line P 1 , reference numeral  46  designates a solenoid valve, reference numeral  48  designates a strainer for removing foreign substance from the waste liquid “W”, reference numeral  50  designates a flowmeter for measuring the flow rate of the waste liquid “W”, and reference numerals  51   a  and  51   b  denote valves. 
     The waste gas supply line P 2  connects between the burner  22  and the waste gas supply source  84  to supply a waste gas “EO” such as ethylene oxide or other waste gas from the waste gas supply source  84  to the burner  22  through the waste gas inlet  26   a . Reference numeral  52  designates a pressure gauge for measuring the pressure of the waste gas, reference numeral  53  designates a union joint, reference numerals  54  and  56  denote solenoid valves, reference numeral  57  denotes a check valve, and reference numeral  58  designates a flashback arrester for arresting backfire. 
     The combustion-improving gas supply line P 3  connects between the burner  22  and the combustion-improving gas supply source  86  to supply a combustion-improving gas “PG” such as propane or other combustible or self-sustained combustion gas from the combustion-improving gas supply source  86  to the burner  22  through the combustion-improving gas inlet  26   b . Reference numeral  60  denotes a gas pressure switch for sensing the pressure of the combustion-improving gas “PG”, reference numeral  62  denotes a pressure gauge for measuring the pressure of the combustion-improving gas “PG”, the reference numeral  63  designates a union joint, reference numerals  64  and  66  denote solenoid valves, reference numeral  68  denotes a control valve for regulating the flow rate of the combustion-improving gas, reference numeral  70  designates a motor for driving the control valve  68 , and reference numerals  71   a ,  71   b  and  71   c  designate valves. 
     The air supply line P 4  connects between the burner  22  and the air supply source  72  such as a blower to supply combustion air “A” to the burner  22  through the combustion air inlet  28 . Reference numeral  74  denotes an air pressure switch for sensing the air pressure, and reference numeral  76  denotes a damper for regulating the flow rate of the combustion air “A”. 
     A gas branch line P 5  diverges from the combustion-improving gas supply line P 3  and meets at a gas mixer  78  a first air branch line P 6  that branches from the air supply line P 4 . The combustion air “A” and the combustion-improving gas “PG” are mixed together at the pilot mixer  78 , and then the mixed gas “PA” is supplied to a pilot burner  23  within the burner  22  to feed the pilot flame. Reference numeral  80  designates a solenoid valve connected to the gas branch line P 5 , and reference numeral  81  denotes a valve. 
     A second air branch line P 7  diverges also from the air supply line P 4  to supply the combustion air “A” to the protection air supply pipe  34 . Reference numeral  82  is a valve connected to the second air branch line P 7 . 
     The waste gas “EO”, the combustion-improving gas “PG” and the combustion air “A” are supplied to the burner  22  through the respective supply lines P 2 , P 3  and P 4 , mixed together, lighted and jetted out in the form of flame. The flame jetted out of the burner  22  climbs the side wall  16  along a helical path on the inside surface  19  and forms a vortex of flame within the incineration chamber  21 . 
     The waste liquid “W” is supplied to the atomizer pipe  30  through the waste liquid supply line P 1  and sprayed into the chamber  21  through the spray nozzle  32  so that at least some of, and preferably most of, the sprayed waste liquid is jetted upwardly into the center of the vortex of flame. Meanwhile the air “A” supplied to the protection air supply pipe  34  through the second air branch line P 7  blows on the spray nozzle  32  so that the spray nozzle  32  is cooled and thereby prevented from being excessively heated. 
     As described above, the waste liquid “W” is jetted upwardly from the bottom of the container  14  toward the top wall  18 . This allows the atomized waste liquid to be heated by the burner flame during its upward and downward movement. Stated differently, the atomized liquid is heated both ways, i.e., one way on which it drives upwardly and the other way on which it falls downwardly. Thus, in the incinerating chamber  21 , the waste liquid can be heated twice as much efficiently as it would be in a conventional incinerator wherein waste liquid is heated while falling only. Thus, the incinerator  12  requires a less bulky container as compared to such a conventional incinerator. 
     Heated both ways, the atomized liquid vaporizes at a high temperature within the chamber  21 , allowing the complete incineration of the liquid. In this manner, the waste liquid is efficiently incinerated within the container  14  while less energy is consumed, which allows designing of a small-sized device that can perform incineration of a great amount of waste liquid. This results in substantial reduction of the equipment cost and the fuel cost. 
     It should be recognized that nitrogen oxide resulting from the incineration is substantially decreased in amount according to the invention because the burner flame temperature is lowered due to the sprayed waste liquid which drives through the vortex of flame. 
     It should be also recognized that the minimum fuel may be required to operate the incinerator of the invention since the temperature sensor  40  on top of the container  14  detects the internal temperature of the container  14  so that the detected temperature may be used to control the internal temperature. 
     As described above, the device and the method of the invention provide better heat efficiency to allow the design of a small-sized incineration container, allow quick heating and rapid vaporization of a waste liquid to encourage the complete incineration of the waste liquid, enable the incineration of a large amount of waste liquid in the small-sized container so that a less installation space is required, reduce the equipment cost, reduce the energy consumption due to the increase in heat efficiency, and assure a low flame temperature to inhibit formation of nitrogen oxide. 
     FIGS. 4 and 5 show another vertical incinerator according to the invention. The incinerator  112  is designed for incinerating a waste liquid together with waste air having an offensive odor. The incinerator  112  differs from that of the foregoing embodiment in that a waste air supply pipe  142  (shown in FIG. 5) is connected to the container  114  to feed waste air into the lower or combustion section of the incineration chamber  121 . The pipe  142  passes through the lower part  150  of the side wall  116  which defines the combustion section of the incineration chamber  121 . A waste air supply line P 8  connects between the supply pipe  142  and a waste air supply source  144  to supply waste air “WA” to the incineration chamber  121 . Reference numeral  146  denotes an air pressure gauge for measuring the air pressure of the waste air “WA”, and reference numeral  148  denotes a solenoid valve. However, no waste gas supply line is provided for the device of this embodiment to supply a waste gas to the burner  122 . 
     The incinerator  112  further differs from that of the first embodiment in that the atomizer pipe  130  passes through the lower part  150  of the side wall  116  and it is mostly embedded in the bottom wall  120 . The forward end of the atomizer pipe  130  is formed into an upwardly directed spray nozzle  132  projecting upwardly into the chamber  121  so that the tube axis of the nozzle  132  is disposed substantially vertically in general alignment with the cylinder axis of the container  114 . The protection air supply pipe  134  (shown in FIG. 5) may also be embedded in the bottom wall  120  so that it is disposed alongside the atomizer pipe  130 . 
     In addition, the structure of the container is shown in more detail in FIG. 4 than in FIG. 1 although the containers by themselves in FIGS. 1 and 4 in fact have virtually the same structure. The lower part  150  of the side wall  116  has a triple-wall structure consisting of an innermost wall  152  of refractory cement, an intermediate wall  154  of insulating cement and an outermost wall  156  of stainless-clad steel. The bottom wall  120  also has the triple-wall structure. The upper part  160  of the side wall  116  that defines the upper or vaporization section of the chamber  121  has a quadruple-wall structure consisting of an innermost wall  162  of refractory insulating cement, an inner casing  164  of stainless steel, insulating wall  166  of ceramic fiber and an outer casing  168  of stainless-clad steel. The top wall  118  also has the quadruple-wall structure. 
     The other parts of the device of the second embodiment are virtually identical in structure to the first embodiment. Thus, the like reference numerals are used throughout the drawings to designate the corresponding parts, and descriptions of the corresponding parts are omitted in the description of FIGS. 4 and 5. 
     In the above second embodiment, the waste air is supplied to the chamber  121  and thus is incinerated together with the waste liquid. During the incineration, the odorcausing components of the waste air such as unsaturated organic compounds are oxidized and thereby the waste air can be free of the offensive odor before released into the atmosphere.