Abstract:
A method of making carbon black. A method of making carbon black is described including combusting feedstock with plasma in an apparatus having a series of unit operations with individual capacities. The individual capacities of the unit operations are substantially balanced by replacing at least part of the feedstock with a feedstock having a molecular weight heavier than methane. This results, among other things, in increased utilization of the individual capacities of the unit operations and increased overall throughput.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/933,488 filed Jan. 30, 2014, the disclosure of which is expressly incorporated by reference herein in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The field of art to which this invention generally pertains is methods for making use of electrical energy to effect chemical changes. 
       BACKGROUND 
       [0003]    No matter how unique the product or process is, over time, all manufacturing processes look for ways to become more efficient and more effective. This can take the form of raw material costs, energy costs, or simple improvements in process efficiencies, among other things. In general, raw material costs and energy resources, which are a substantial part of the cost of most if not all manufacturing processes, tend to actually increase over time, because of scale up and increased volumes if for no other reasons. For these, and other reasons, there is a constant search in this area for ways to not only improve the processes and products being produced, but to produce them in more efficient and effective ways as well. 
         [0004]    The systems described herein meet the challenges described above while accomplishing additional advances as well. 
       BRIEF SUMMARY 
       [0005]    A method of making carbon black is described including cracking feedstock with plasma in an apparatus having a series of unit operations with individual capacities, wherein the individual capacities of the unit operations are substantially balanced by replacing at least part of the feedstock with a feedstock having a molecular weight heavier than methane, resulting in increased utilization of the individual capacities of the unit operations and increased overall throughput. 
         [0006]    Additional embodiments include: the method described above the heavier feedstock is at least one gas; the method described above where the heavier feedstock contains a carbon content higher than methane; the method described above where up to 100% of the feedstock is replaced with the heavier feedstock; the method described above where the unit operations include at least one reactor unit, and/or at least one heat exchanger unit, and/or at least one filter unit; the method described above where the unit operations include at least one dryer unit; the method described above where the unit operations include at least one pelletizer unit; the method described above where the heavier feedstock is one or more of ethane, propane, butane, acetylene, ethylene, butane, carbon black oil, coal tar, crude coal tar, diesel oil, benzene, and methyl naphthalene; the method described above where the heavier feedstock contains one or more additional polycyclic aromatic hydrocarbons. 
         [0007]    These and additional embodiments, will be apparent from the following descriptions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The FIGURE shows a schematic representation of one typical system as described herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    The particulars shown herein are by way of example and for purposes of illustrative discussion of the various embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. 
         [0010]    The present invention will now be described by reference to more detailed embodiments. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
         [0011]    Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for describing particular embodiments only and is not intended to be limiting of the invention. As used in the description of the invention and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. All publications, patent applications, patents, and other references mentioned herein are expressly incorporated by reference in their entirety. 
         [0012]    Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the number of significant digits and ordinary rounding approaches. 
         [0013]    Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Every numerical range given throughout this specification will include every narrower numerical range that falls within such broader numerical range, as if such narrower numerical ranges were all expressly written herein. 
         [0014]    Additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. 
         [0015]    As described herein, the use of ethane or heavier feedstock gases to reduce costs and balance reactor capacity in a plasma reactor is described. Ethane and/or other heavier than methane hydrocarbons can be used in place of part or all of the methane as the process&#39; feedstock. The use of feedstock heavier than methane in the plasma process reduces the required energy per unit of production. Use of heavier feedstocks can therefore result in lower raw material costs and higher energy efficiencies. However, by replacing a portion or all of the methane/natural gas as feedstock with the heavier feedstock, if done properly this also can allow for better (or ideally full) utilization of the front and back end individual unit capacities and so reduce overall costs or increase profitability, even when the heavier feedstock costs more than the lighter feedstock, by spreading fixed costs over a higher amount of product produced per unit of time, or simply by generating additional product to sell. Use of heavier feedstocks may also improve product quality (lower grit and/or extract from forming product faster, higher structure/CDBP (crushed dibutyl phthlate number) or DBP (dibutyl phthlate number), higher surface area). 
         [0016]    The use of ethane to substitute a portion of the methane in a way to increase, e.g., conventional reactor and/or heat exchanger and/or filter capacity so that it matches the available downstream capacity, e.g., conventional heat exchanger/product cooler, filter, pelletisation and/or dryer capacity (often the dryer being the limit to production) can be extremely advantageous. For example, this balancing of capacity can result in higher profitability from increased sales on reactor or heat exchanger or filter limited grades even when the raw material cost, or even the total cost, of the product increases due to the potentially higher cost of ethane or heavier feedstocks. As described herein, the use of the heavier feedstock enriches the feedstock used and so increases the utilization of the back end of the plasma unit, which can result in enabling higher sales and profitability, or just to satisfy customer demands for additional more expensive to make product. 
         [0017]    While heavier does refer to relative molecular weights, i.e., grams per mole (gm/mol), it is the carbon content of the feedstock (% carbon by weight) that best represents the potential for improvement, with the increasing presence of unsaturated bonds within the feedstock that can also have a positive effect on the process, for example, the use of ethylene in place of or in addition to ethane. It should also be noted that while the gas form of the feedstock is typically used, while it can be more expensive, liquid forms of the feedstocks described herein can also be employed. 
         [0018]    If the hydrocarbon feedstock is represented by the chemical formula C n H (2n+2) , the results described herein can improve with increase in “n”. However, with unsaturated and/or cyclical compounds, the +2 actually changes to a smaller or negative number, for example, carbon black feedstock in a furnace process is typically C n H n , and coal tar actually C n H n/2 . 
         [0019]    The use of the heavier feedstocks as described herein results in the ability to balance or match the capacities of each unit of operation. Production from the full set of equipment is restricted to the lowest individual unit capacity step, with those capacity limits often determined by such things as the grade of production and the feedstock used. Often reactor limits match filter limits, but heat exchanger limits can represent a different limit for the process. For example, furnace processes typically couples the reactor and heat exchanger limits. There is also typically a given evaporation rate in the dyer. Changing the dryer is expensive, and so it typically represents the limit of the unit, but not always. Thus using the full dryer capacity all the time by using heavier feedstocks when the reactor, heat exchanger, filter or other unit operation that benefits from heavier feedstocks is unable to provide enough product when using methane or light feedstocks to use all of the dryer capacity can increase a production train&#39;s profitability. 
         [0020]    The amount of methane replaced can be meaningful at any level, e.g., even as little as 1% by weight or volume, 2%, 3%, etc. up to 100%. And once 100% of the methane is replaced with ethane, for example, additional capacity benefits can be achieved by replacing the ethane with a heavier feedstock such as propane, for example, and so forth, on up to heavier and higher molecular weight gases and liquids. 
         [0021]    While relative cost is of course a consideration which needs to be factored into the selection, in addition to ethane, any additional gases or liquids which are operable in conventional carbon black producing processes may be selected, including, for example, propane, butane, acetylene, ethylene, butane, carbon black oil, coal tar, crude coal tar, diesel oil, benzene, methyl naphthalene, etc. 
       Example 1 
       [0022]    While useful with any conventional unit operation containing carbon black generating systems typically used to generate carbon black products, one system is shown schematically in the FIGURE, including a plasma generator ( 10 ) generates plasma to which the feedstock gas ( 11 ) (typically methane) is added. The mixed gases enter into a reactor ( 12 ) where the carbon black is generated followed by a heat exchanger ( 13 ). The carbon black is then filtered ( 14 ), pelletized in a pelletizer ( 15 ) and dried in a dryer ( 16 ). By replacing the methane gas with ethane gas, as stated above, the heavier feedstock enriches the feedstock used and increases the production rate of a reactor, heat exchanger and/or filter limited grade so that it more fully utilizes the capacity of downstream equipment, potentially enabling higher sales and profitability. Other conventional unit operations may exist, for example, between the filter and pelletizer units shown, or elsewhere as desired or appropriate. They may include hydrogen/tail gas removal units, conveying units, process filter units, classification units, grit reduction mill units, purge filter units (filters black out of steam vented from dryer, for example), dust filter units (collects dust from other equipment, for example), off quality product blending units, etc., as may be typically found in carbon black production systems. And of course, these unit operations could and be subjected to the balancing and enhanced utilization as described herein as well. As further demonstrated in the Table 1 below, for the same power (kilowatts=kW), a carbon black production unit would typically make the same amount of N326 as N330 grade carbon black (CB). However, N330 has a higher OAN (oil absorption number) and so needs more water per kilogram produced to pelletize, which would also dictate the need for a larger dryer. If a unit had such a larger dryer, then using ethane to make N326 would increase the production rate to 168 kilograms(kg)/hour(hr) and still leave some dryer capacity unutilized. Similarly, for the filter, using ethane reduces the required filter size. The replacement of methane with ethane could reduce the required filter area, e.g., should some of the filter capacity get damaged, or a difficult-to-filter grade be manufactured on the same unit. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 1* 
               
               
                   
               
               
                 Feedstock 
                 Methane 
                 Methane 
                 Ethane 
                 Ethane 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Grade 
                   
                 N326 
                 N330 
                 N326 
                 N330 
               
               
                 OAN 
                   
                 72 
                 102 
                 72 
                 102 
               
               
                 Torch Power 
                 kW 
                 750 
                 750 
                 750 
                 750 
               
               
                 Reactor Temp 
                 ° C. 
                 1400 
                 1400 
                 1400 
                 1400 
               
               
                 CB Production 
                 kg/hr 
                 128 
                 128 
                 168 
                 168 
               
               
                 Filtration Rate 
                 Nm 3 /hr 
                 1353 
                 1353 
                 1423 
                 1423 
               
               
                 Sp. Filter Rate 
                 Nm 3 /kg 
                 11 
                 11 
                 8 
                 8 
               
               
                 Dryer Evap. 
                 kgH 2 O/hr 
                 101 
                 143 
                 133 
                 189 
               
               
                   
               
               
                 *C = centigrade; Temp = temperature; Sp. = specific; Evap. = evaporation; Nm 3  = normal meter, i.e., cubic meter of gas at normal conditions, i.e. 0° C., and 1 atmosphere of pressure. 
               
             
          
         
       
     
       Example 2 
       [0023]    A unit fully utilized making N330 also needs to make N234. This grade requires more energy per kilo of black, but does not have a sufficiently large power supply. By adding ethane the unit can make more N234, and so satisfy customer demands that the equipment could not when using Methane. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 Feedstock 
                 Methane 
                 Methane 
                 Ethane 
                 Ethane 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Grade 
                   
                 N234 
                 N330 
                 N234 
                 N330 
               
               
                 OAN 
                   
                 125 
                 102 
                 125 
                 102 
               
               
                 Torch Power 
                 kW 
                 750 
                 750 
                 750 
                 750 
               
               
                 Reactor Temp 
                 ° C. 
                 1925 
                 1400 
                 1925 
                 1400 
               
               
                 CB Production 
                 kg/hr 
                 85 
                 128 
                 110 
                 168 
               
               
                 Filtration Rate 
                 Nm 3 /hr 
                 1513 
                 1353 
                 1552 
                 1423 
               
               
                 Sp. Filter Rate 
                 Nm 3 /kg 
                 19 
                 11 
                 14.5 
                 8 
               
               
                 Dryer Evap. 
                 kgH 2 O/hr 
                 117 
                 143 
                 151 
                 189 
               
               
                   
               
             
          
         
       
     
         [0024]    Thus, the scope of the invention shall include all modifications and variations that may fall within the scope of the attached claims. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.