Equipment and Design
Ueteber 1956
New opportunities for both interesting and profit-
able public service are corning to the gas industry bg ChUPb8 Owen I ~ O W U
is lese seneitive to booms and depressions than many other chemical activities. We have been wrong about the amount of natural gaa available. Now we readily admit there is an abundance of natural gas. However, the price has more than doubled in the past few yeam, and a very large part of the country cannot be served with this wonderful natural resource of the Gulf and Midwestern states. Pipe lines extend the area served east, north, and west every year. However, a modern pipe line has limits,which gives basis to the claim that town gas plank are and will be necessary for most efficientand economical production of gas. A modern pipe line is a plant in every sense, and a splendid piece of chemical engineering design development. The gas is compressed to high pressures at carefully specified intervals, then cooIed, liquefying several hydrocarbons which are eeparated, forming the basis of an important organic chemical business. These pipe lines cost very large sums of money and are correlated to other plants with large investments, so that the system must operate continuously at full capacity. The domestic gas heating load is seasonable, creating a problem for the pipe lines in the spring, summer, and fall and a difliculty in the winter. Storage of large amounts of gas is both very W c u l t and costly. Two methods are employed: The gas is liquefied and stored in metal spheres at low temperature, or is pumped back into underground rock formations under high pressure, from which it is withdrawn during the winter months of heavy demand. The first method is very expensive, involving complicated engineering, and has led to some tragedies. The second method is limited by lack of suitable exhausted gas fields properly located to furnish an adequate supply. Therefore, the local gas plant still has an important industry to serve, in which it cannot easily be replaced. At the moment, the process is wrong-not the economics, or the policy of making gas in the community which it serves. The process must be changed, and all the old equipment must be written off and a new start made. Growtng w k e t for gas Gas is now made from coke, a high-cost material that must be replaced with coal. Coal can be stored and new processes There are some bright spots. The market for domestic gasify it completely, producing a gas of nearly the desired and fuel gas is growing at an accelerated rate, so that the basic composition, heating value, and viscosity in one operation. economy is good. Gaa is nearest to an ideal fuel of all the The same chemical reaction is used as in the present water gas fuels we use. There are sound theory and data to show that process. (Arbon and steam react to form equal volumes of nothing burns but gas. Fuel oil, even the best refined domescarbon monoxide and hydrogen. The new part is that, in the tic grades, is no competitor for gas in convenience, cleanlipresent process, the heat required for this endothermic reacness, or efficiency. A very large number of homes heated with tion is supplied intermittently by burning part of the carbon oil at present would change to gas if it were available. The with air, which stores heat in the carbon bed. This stored heat price of oil is risimg more rapidly than that of gas, and shortis then used for the next “make” cyele, reacting steam and ages of supply, with labor trouble on deliveries, make gas carbon to make water gas until the temperature of the bed preferable for domestic heating. The consumption of gas for falls to the lower limit. The new technique preheats the domwtic space heating would keble if the supply permitted. steam which reacts with the (Continued on page 68 A ) The manufacture of town gas is not a dying industry, end S? A
W
I BEILIEIVEhundreds of chemical engineers are about to
find n6w careers in the manufactured gas industry because a revolutionary change is taking plge. This is not written hastily. We appreciate fully the many obstacles to new employment in this old, enfranchised, satisfied industry. If the pment equipment and processas could prsduce sufficient gaa to fill the essential demand, new opportunities in this field could not be expected. Fortunately, however, two lusty procsse industries, synthetic ammonia and liquid fuels, have developed proved and seasoned new processes for the production of fuel gas. The fuel gas industry has only to adopt them, and we believe a change is in the makwg now, involving new plants with new equipment. The fuel and domestic gas industries must spend $2.1 billion in the next 3 years and probably should spend more. This ia more than the wartime cost of the atomic bomb. There are undeniably many obstacles to be by-passed before new employment in the gas industry is readily available. New methods for supplying gas stillleave the overhead on the present gas plant and equipment to be met. Interest on company bonds, which in some cases were unwisely issued for equipment long since lost to the scrap pile, must be paid. These chargee hang like a millstone on the new process. There is, unfortunately, a certain ponderousness about employment in a public utility for a keen thinking, creative, and research-minded chemical engineer. This is the fault of management to a limited extent only, because the industry is completely regulated. Politically minded commiaaions, two and sometimes three in direct sequence, impose fived regulations. Operating companies are not only constantly ordered to reduce the price of gas, but are also compelled to spend certain sums for maintenance, regardless of the plant condition, and to pay certain rates for labor. For many years city gas companies have been squeezed between a ceiling over the price of their product and ft floor under wages, which has made effective progressive management all but impossible. Local, town, county, state, and federal taxing bodies have bled the utilities to a point where we must not criticize too much the lack of incentive and progressiveness.
Equipment and Design carbon 80 highly in excess of the reaction temperature that the contained heat continuoursly supplies the endothermic requir+menb of the reaction. Superheating steam to 4000" F. has not yet been accomplished in commercial equipment. It ia an achievement, however, that 3500" haa been reached and ia believed to be oommercial, but 3200' or 3300" F. is now a commercial pmsibility in equipment of a practical type and deaign. With this amnunt of auperheat in the steam, it can be contacted with heated coke, forming a regular blue water gas, of about 45% carbon monoxide and 50% hydrogen. Blue water gss alone is not suited, without enrichment, for distribution to city consumers. it k suitable for space heating of domestic homes, but gas from the manufacturing plant must travel through the same pipe linea and distribution system with gas wed for other purpws, which must have a heat content of around 550 B.t.u. Therefore, blue water gaa must be adjusted, which is accomplished in this new technique by using finely pulverized coal gasified in suspension. Solid beds of carbon are replaced in making gas under this system by the "fluidized" type of equipment. Before the finely pulverized coal is introduced into the gasification chamber, it is preheated, giving off coal gas very readily from the fine particleti in suspension. This coal gas is separated from the coke particles and diverted to enrich the fmal blue water gas, while the coke is blown into a reaction chamber with highly heated walls, where it contacts the highly heated steam with great turbulence. These new plants, in common with most chemical plants, work more efficiently and can be built a t somewhat lower cost in very large sizes. However, we predict that deaign of these plants will shortly be so highly developed that very good efficiencies will be realized in reltdively small rrisen. Each plant consistp of two preheating stoves working alternately on steam, a precoking chamber operating continuously, and a conical gasification chamber. Plain blue gas only is used to heat the stoves, and all the coal gas is mixed only with the blue gas distributed. There are splendid opportunities in thw new equipment for the chemist and chemical engineer. The gas Companies can locate several of thecre plants on the edge or ou'dying rim of their total distribution area with a reasonable investment cost. These plants will then feed gas back from the end of the distribution lines toward the center, thuu loading the entire system 88 heavily aa the trunk lines in the center near the present gas plant. Use of the present installed underground lines is essential became of the invest ment, which has bothered the gas industry when generating the complete requirements for gas from one plant, perhaps now improperly located. The central trunk lines aimply will not carry sufficient gas to the outlying edge of the diatrict. The new method and the new equipment and process for producing gas will overcome this difficulty to a very large extent. The chemical engineering features of thm new process are more intricate th&n the processes used at present, although the plant as a whole is less complicated. Chemical engineers will find a challenge in this new technique for their designing and creative abilities. We also believe that the supply of gas for domwtic house heating can be increased by these new processes and plants based on coal, to satiafy the demand at prices below the price of natural gas, after reforming and distribution by a utility which purchased the gas from a pipe line several thousand milea long. 58A
