Abstract:
An energy efficient natural gas additive is provided with 10-80 wt % C 1 -C 9  alcohol, and 20-90 wt % C 6 -C 11  hydrocarbon. It is corrosion free. The additive can be completely dissolved in natural gas. It can save energy and is chemically stable and reliable. It can be used for metal cutting and welding.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to metal cutting and more particularly to an energy efficient natural gas additive and its applications. 
         [0003]    2. Description of Related Art 
         [0004]    With the rapid development of China&#39;s industry, the demand for gas for cutting metal is growing. Currently, oxygen and acetylene are widely used in oxy-fuel cutting. For torch with acetylene as heating source, it has the benefits of high flame temperature and significant thermal processing effect. Thus, it is widely used in metal cutting, metal welding, deformation correction, etc. However, acetylene is disadvantageous due to poor security, high energy consumption, high price, environmental pollution, etc. In recent years, metal cutting industry is looking for alternatives such as propane, natural gas, LPG (liquefied petroleum gas), etc. Natural gas has features of high explosion limit, easy to propagate after leaking and is safer than propane and LPG. Natural gas can be safely used in a closed room in shipbuilding industry and has a lower price than propane. However, natural gas for cutting metal has disadvantages of long time to warm for piercing, slow cutting speed, low flame temperature, poor performance, and high energy consumption. It is often that additives are added to natural gas. However, most additives are corrosive and these additives are hydrogen peroxide, potassium permanganate, water, potassium hydroxide, hydrofluoric acid, perchloric acid, and hydrochloric acid. In long-term use, it will corrode cylinders, pipe walls and thus there is a great security risk. Some additives are viscous liquid, gum, or solid such as nano-alumina, iron oxide nanoparticles, naphthenate (manganese, cerium, cobalt, zirconium, copper, 
         [0005]    Lanthanum, etc.), alkyl sulfonate, methenamine and Tween-80, etc. They cannot be completely dissolved in natural gas. Gas with liquid may damage rubber membranes of pressure reduction valves in pipes. Thus, additives containing viscous liquid or gum that is insoluble in liquid are not appropriate for long-term use. Ferrocene is also used as additive. Ferrocene is a solid. Ferrocene is required to dissolve in solvent prior to be used as additive. This additive is added to natural gas pipes and ferrocene becomes solid particles floating in natural gas after a period of time. The solid ferrocene particles may clog a torch nozpreferred embodimente, make cutting torch instable, and even cut off the torch. Further, conventional additives have poor performance. After adding to natural gas, the generated torch only reaches propane flame temperature (≦2700° C.) and cannot reach acetylene flame temperature (3100° C.). Thus, it is disadvantageous in many applications due to high energy consumption. 
       SUMMARY OF THE INVENTION 
       [0006]    It is therefore one object of the invention to provide an energy efficient natural gas additive which is non-corrosive, can be completely dissolved in natural gas, and is a good synergistic to achieve energy saving and increase safety. 
         [0007]    Another object of the invention is to provide an energy efficient natural gas additive which can be used in metal cutting. 
         [0008]    Still another object of the invention is to provide an energy efficient natural gas additive which can be used in heating. 
         [0009]    In one aspect of the invention, there is provided a natural gas additive comprising 10-80 wt % C 1 -C 9  alcohol, and 20-90 wt % C 6 -C 11  hydrocarbon. 
         [0010]    Preferably, the natural gas additive comprises 30-60 wt % C 1 -C 9  alcohol, and 30-70 wt % C 6 -C 11  hydrocarbon. 
         [0011]    Preferably, the natural gas additive comprises 45-50 wt % C 1 -C 9  alcohol, and 40-60 wt % C 6 -C 11  hydrocarbon. 
         [0012]    Preferably, the alcohol is one of methanol, ethanol, isopropanol, C 4 -C 9  high alcohol, and a combination thereof; and the C 6 -C 11  hydrocarbon is one of toluene, xylene, trimethylbenzene, and a combination thereof. 
         [0013]    Preferably, the natural gas additive comprises 70 wt % methanol, 20 wt % xylene, 5 wt % high alcohol, and 5 wt % C 9 -C 11  hydrocarbon. 
         [0014]    Preferably, the natural gas additive comprises 85 wt % n-hexane, 5 wt % ethanol, 5 wt % isopropanol, and 5 wt % C 9 -C 11  hydrocarbon. 
         [0015]    By utilizing the invention the following advantages are obtained: 
         [0016]    In accordance with GB/T5096, the natural gas additive of the invention has copper corrosion grade I after being tested. This means that the natural gas additive does not corrode steel and can be used for a long time. The additive of the invention can be added to the pipes for conveying natural gas and natural gas cylinders, and can be added to pipes for conveying liquefied natural gas which is used for cutting or welding. 
         [0017]    The additive of the invention has no solid particles in room temperature and can be dissolved in natural gas. It does not damage rubber membranes of pressure reduction valves in pipes. It is stable in nature. 
         [0018]    The natural gas additive of the invention can increase flame temperature to 3150-3450° C. in cutting operation. It greatly improves the performance. Its preheat piercing time is short, its cutting speed is quick, and its uses are wide. 
         [0019]    The natural gas additive of the invention can be widely used for cutting steel plate such as Q235B, D36, AH32, Q345B, or Q235A, and steel plates for shipbuilding. It can be safely used in a closed room in shipbuilding industry and is safer than propane and liquefied gas. 
         [0020]    The natural gas additive of the invention can is cost effective. It can save energy. 1 ton of the natural gas additive of the invention is equivalent to about at least 2 ton of the conventional propane. It can save at least 50% fuel in comparison with the conventional propane. 
         [0021]    The above and other objects, features and advantages of the invention will become apparent from the following detailed description taken with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is a table of comparing conventional propane with natural gas additive of a first preferred embodiment of the invention in terms of cutting length, cutting speed, consumed gas, consumed oxygen, and consumed gas per meter cutting; 
           [0023]      FIG. 2  is a table of comparing conventional liquefied gas with natural gas additive of a second preferred embodiment of the invention in terms of cutting length, cutting speed, consumed gas, consumed oxygen, and consumed gas per meter cutting; 
           [0024]      FIG. 3  is a table of comparing another conventional propane with natural gas additive of a third preferred embodiment of the invention in terms of cutting length, cutting speed, consumed gas, consumed oxygen, and consumed gas per meter cutting; 
           [0025]      FIG. 4  is a table of comparing further conventional propane with natural gas additive of a fourth preferred embodiment of the invention in terms of cutting length, cutting speed, consumed gas, consumed oxygen, and consumed gas per meter cutting; 
           [0026]      FIG. 5  is a table of comparing conventional natural gas with natural gas additive of a fifth preferred embodiment of the invention in terms of cutting length, cutting speed, consumed gas, and consumed gas per meter cutting; 
           [0027]      FIG. 6  is a table of comparing another conventional natural gas with natural gas additive of a sixth preferred embodiment of the invention in terms of cutting length, cutting speed, consumed gas, and consumed gas per meter cutting; 
           [0028]      FIG. 7  is a table of comparing further conventional natural gas with natural gas additive of a seventh preferred embodiment of the invention in terms of cutting length, cutting speed, consumed gas, consumed oxygen, and consumed gas per meter cutting; 
           [0029]      FIG. 8  is a table of comparing conventional propane-oxygen flame method and acetylene-oxygen flame method with the natural gas additive of the second preferred embodiment of the invention-oxygen flame method and the natural gas additive of the seventh preferred embodiment of the invention-oxygen flame method in terms of preheat piercing time; and 
           [0030]      FIG. 9  is a table of comparing conventional pure natural gas-oxygen flame, propane-oxygen flame, and acetylene-oxygen flame with the natural gas additive of the second preferred embodiment of the invention-oxygen flame and the natural gas additive of the seventh preferred embodiment of the invention-oxygen flame in terms of flame temperature. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    Referring to  FIG. 1 , an energy efficient natural gas additive in accordance with a first preferred embodiment of the invention is discussed in detail below. The energy efficient natural gas additive comprises 20 wt (weight) % methanol, 20 wt % ethanol, and 30 wt % toluene, and 30 wt % xylene. 
         [0032]    In accordance with GB/T5096, the natural gas additive of the invention has copper corrosion grade I after being tested. This means that the natural gas additive does not corrode steel. 
         [0033]    The additive of the invention can be added to the pipes for conveying natural gas and natural gas cylinders, and can be added to pipes for conveying liquefied natural gas which is used for cutting or welding. 
         [0034]    For verifying effects of the first preferred embodiment of the invention, the following test is conducted: Workpiece to be cut is 6 mm Q235B steel plate. Gas for cutting is conventional propane and natural gas additive according to the first preferred embodiment of the invention. Test results are shown in  FIG. 1 . 1 ton of the natural gas additive according to the first preferred embodiment of the invention is equivalent to about 2.2 ton of the conventional propane. It is concluded that the natural gas additive according to the first preferred embodiment of the invention can save about 54.8% fuel in comparison with the conventional propane. 
         [0035]    Referring to  FIG. 2 , an energy efficient natural gas additive in accordance with a second preferred embodiment of the invention is discussed in detail below. The energy efficient natural gas additive comprises 70 wt % methanol, 20 wt % xylene, 5 wt % high alcohol, and 5 wt % C 9 -C 11  hydrocarbon. 
         [0036]    In accordance with GB/T5096, the natural gas additive of the invention has copper corrosion grade I after being tested. This means that the natural gas additive does not corrode steel. 
         [0037]    The additive of the invention can be added to the pipes for conveying natural gas and natural gas cylinders, and can be added to pipes for conveying liquefied natural gas which is used for cutting or welding. 
         [0038]    For verifying effects of the second preferred embodiment of the invention, the following test is conducted: Workpiece to be cut is 8 mm Q235B steel plate. Gas for cutting is conventional liquefied gas and natural gas additive according to the second preferred embodiment of the invention. Test results are shown in  FIG. 2 . 1 ton of the natural gas additive according to the second preferred embodiment of the invention is equivalent to about 2.32 ton of the conventional liquefied gas. It is concluded that the natural gas additive according to the second preferred embodiment of the invention can save about 56.9% fuel in comparison with the conventional liquefied gas. 
         [0039]    Referring to  FIG. 3 , an energy efficient natural gas additive in accordance with a third preferred embodiment of the invention is discussed in detail below. The energy efficient natural gas additive comprises 20 wt % methanol, 40 wt % high alcohol, 30 wt % n-hexane, and 10 wt % xylene. 
         [0040]    In accordance with GB/T5096, the natural gas additive of the invention has copper corrosion grade I after being tested. This means that the natural gas additive does not corrode steel. 
         [0041]    The additive of the invention can be added to the pipes for conveying natural gas and natural gas cylinders, and can be added to pipes for conveying liquefied natural gas which is used for cutting or welding. 
         [0042]    For verifying effects of the third preferred embodiment of the invention, the following test is conducted: Workpiece to be cut is 13 mm D36 steel plate. Gas for cutting is another conventional propane and natural gas additive according to the third preferred embodiment of the invention. Test results are shown in  FIG. 3 . 1 ton of the natural gas additive according to the third preferred embodiment of the invention is equivalent to about 2.16 ton of the another conventional propane. It is concluded that the natural gas additive according to the third preferred embodiment of the invention can save about 53.7% fuel in comparison with the another conventional propane. 
         [0043]    Referring to  FIG. 4 , an energy efficient natural gas additive in accordance with a fourth preferred embodiment of the invention is discussed in detail below. The energy efficient natural gas additive comprises 10 wt % methanol, 20 wt % ethanol, 20 wt % high alcohol, 10 wt % toluene, and 10 wt % xylene. 
         [0044]    In accordance with GB/T5096, the natural gas additive of the invention has copper corrosion grade I after being tested. This means that the natural gas additive does not corrode steel. 
         [0045]    The additive of the invention can be added to the pipes for conveying natural gas and natural gas cylinders, and can be added to pipes for conveying liquefied natural gas which is used for cutting or welding. 
         [0046]    For verifying effects of the fourth preferred embodiment of the invention, the following test is conducted: Workpiece to be cut is 16 mm AH32 steel plate. Gas for cutting is another conventional propane and natural gas additive according to the fourth preferred embodiment of the invention. Test results are shown in  FIG. 4 . 1 ton of the natural gas additive according to the fourth preferred embodiment of the invention is equivalent to about 2.15 ton of the another conventional propane. It is concluded that the natural gas additive according to the fourth preferred embodiment of the invention can save about 53.5% fuel in comparison with the another conventional propane. 
         [0047]    Referring to  FIG. 5 , an energy efficient natural gas additive in accordance with a fifth preferred embodiment of the invention is discussed in detail below. The energy efficient natural gas additive comprises 20 wt % methanol, 10 wt % ethanol, 10 wt % high alcohol, 10 wt % n-hexane, 20 wt % toluene, and 30 wt % xylene. 
         [0048]    In accordance with GB/T5096, the natural gas additive of the invention has copper corrosion grade I after being tested. This means that the natural gas additive does not corrode steel. 
         [0049]    The additive of the invention can be added to the pipes for conveying natural gas and natural gas cylinders, and can be added to pipes for conveying liquefied natural gas which is used for cutting or welding. 
         [0050]    For verifying effects of the fifth preferred embodiment of the invention, the following test is conducted: Workpiece to be cut is 26 mm steel plate for shipbuilding. Gas for cutting is conventional natural gas and natural gas additive according to the fifth preferred embodiment of the invention. Test results are shown in  FIG. 5 . 1 ton of the natural gas additive according to the fifth preferred embodiment of the invention is equivalent to about 2.03 ton of the conventional natural gas. It is concluded that the natural gas additive according to the fifth preferred embodiment of the invention can save about 50.7% fuel in comparison with the conventional natural gas. 
         [0051]    Referring to  FIG. 6 , an energy efficient natural gas additive in accordance with a sixth preferred embodiment of the invention is discussed in detail below. The energy efficient natural gas additive comprises 20 wt % methanol, 10 wt % ethanol, 10 wt % isopropanol, 10 wt % high alcohol, 10 wt % n-hexane, 20 wt % toluene, 10 wt % xylene, and 10 wt % trimethylbenzene. 
         [0052]    In accordance with GB/T5096, the natural gas additive of the invention has copper corrosion grade I after being tested. This means that the natural gas additive does not corrode steel. 
         [0053]    The additive of the invention can be added to the pipes for conveying natural gas and natural gas cylinders, and can be added to pipes for conveying liquefied natural gas which is used for cutting or welding. 
         [0054]    For verifying effects of the sixth preferred embodiment of the invention, the following test is conducted: Workpiece to be cut is 65 mm Q235A steel plate. Gas for cutting is another conventional natural gas and natural gas additive according to the sixth preferred embodiment of the invention. Test results are shown in  FIG. 6 . 1 ton of the natural gas additive according to the sixth preferred embodiment of the invention is equivalent to about 2.34 ton of the another conventional natural gas. It is concluded that the natural gas additive according to the sixth preferred embodiment of the invention can save about 57.3% fuel in comparison with the another conventional natural gas. 
         [0055]    Referring to  FIG. 7 , an energy efficient natural gas additive in accordance with a seventh preferred embodiment of the invention is discussed in detail below. The energy efficient natural gas additive comprises 85 wt % n-hexane, 5 wt % ethanol, 5 wt % isopropanol, and 5 wt % C 9 -C 11  hydrocarbon. 
         [0056]    In accordance with GB/T5096, the natural gas additive of the invention has copper corrosion grade I after being tested. This means that the natural gas additive does not corrode steel. 
         [0057]    The additive of the invention can be added to the pipes for conveying natural gas and natural gas cylinders, and can be added to pipes for conveying liquefied natural gas which is used for cutting or welding. 
         [0058]    For verifying effects of the seventh preferred embodiment of the invention, the following test is conducted: Workpieces to be cut is 8 mm, 10 mm, 12 mm, and 14 mm Q345B steel plate. Gas for cutting is conventional natural gas and natural gas additive according to the seventh preferred embodiment of the invention. Test results are shown in  FIG. 7 . 1 ton of the natural gas additive according to the seventh preferred embodiment of the invention is equivalent to about 2.39 ton of the conventional natural gas. It is concluded that the natural gas additive according to the seventh preferred embodiment of the invention can save about 58.1% fuel in comparison with the conventional natural gas. 
         [0059]    For verifying the preheat piercing effect of the invention, the following test is conducted: Workpiece to be pierced is 40 mm steel plate. Preheat piercing methods to be performed are propane-oxygen flame method, acetylene-oxygen flame method, the natural gas additive of the second preferred embodiment of the invention-oxygen flame method, and the natural gas additive of the seventh preferred embodiment of the invention-oxygen flame method. Test results are shown in  FIG. 8 . 
         [0060]    The above test is conducted under the same weight flow rate with respect to different gases. It is concluded that time for piercing of each of the natural gas additive of the second preferred embodiment of the invention-oxygen flame method and the natural gas additive of the seventh preferred embodiment of the invention-oxygen flame method is much less than that of each conventional method. Thus, the invention has an advantageous effect. 
         [0061]    For verifying the flame temperature increase effect of the invention, the following test is conducted: Flame temperature measurement is Chur Baum-Ferry sodium line reversal method. Flame types to be tested are pure natural gas-oxygen flame, propane-oxygen flame, acetylene-oxygen flame, the natural gas additive of the second preferred embodiment of the invention-oxygen flame, and the natural gas additive of the seventh preferred embodiment of the invention-oxygen flame. Test results are shown in  FIG. 9 . 
         [0062]    It is concluded that flame temperature increase of each of the natural gas additive of the second preferred embodiment of the invention-oxygen flame and the natural gas additive of the seventh preferred embodiment of the invention-oxygen flame is much greater than that of each conventional. Thus, the invention has an advantageous effect. 
         [0063]    While the invention has been described in terms of preferred embodiments, those skilled in the art will recognize that the invention can be practiced with modifications within the spirit and scope of the appended claims.