US2207610A - Method of disposing of refinery wastes - Google Patents

Description

y 1940. M. CHAPPELL 2,207,610

METHOD OF DISPOSING 0F REFINERY WASTES Filed May 13, 1938 Gas Sludge or Acid Tar INVENTOR ATTORNEY Patented July 9, 1940 UNITED STATES METHOD ormsrosme or REFINERY wasrns Marvin L. Chappell, Berkeley, Calif., assignor to Standard Oil Company, of California, San Francisco, Calif., a corporation of Delaware,

Application May 13, 1938, Serial No. 207,764

3 Claims.

This invention relates to an improved method for disposing of waste-products resulting from refining petroleum oil or other organic products with sulphuric acid, in which various acid sludges, sulphur bearing tarry residues, various mercaptan bearing gases and malodorous vapors are encountered, which must be disposed of in such a manner that the surrounding atmosphere will not be polluted or contaminated with poison ous irritants or malodorous refinery aerosols.

The conventional method for the ultimate disposal of all acid sludges or odorous compounds occurring in the refinery is high temperature oxidation, in which the combustible products are burned to carbon dioxide, water vapor, sulphur dioxide and sulphuric acid mist, and are then discharged from high stacks into the atmosphere. I

However, much trouble is experienced by these known methods after the combustion operation due to the formation of sulphur trioxide, which unites with some of the water present in the products of combustion, forming what is known as sulphuric acid mist, a heavy white irritant gas which rapidly settles to the ground and is detrimental to vegetation, animal and human habitation.

The formation of sulphuric acid mist usually takes place after the combustion operation, and is principally due to contact of the heated sulphur dioxide bearing gases, which may contain from approximately 5 to 17 per cent by volume excess oxygen, with the heated brick work forming the stack, at temperatures between 900 and 1650 F.

The formation of sulphuric acid mist will not take place to any appreciable extent below 900 F. At temperatures above 1650 F. sulphuric acidmist is decomposed into sulphur dioxide and oxygen.

This application is an improvement on the method of disposing of refinery wastes, as (18-- scribed in United States Patent No. 1,929,675, patented October 10, 1933, by Marvin L. Chappell et al., which embodies burning refinery sulphur-bearing waste products. to convert such products by combustion into carbon dioxide, water vapor, sulphur dioxide, at temperatures above 1650 F. and then quickly cooling'the combustion products with sprays of water to approximately 900 F. or lower as they enter the stack to prevent formation of sulphuric acid mist.

By this Chappell et a1. method the combustion heat is absorbed to a high extent by the intro- 1 duced sprays of water and therefore is not com-- merciallyavailame for heating purposes, such as for oil distillations or the production of steam in steam boilers.

Now, I have discovered improvements thereon in which the heat generated by the combustions of refinery waste products without the formation of sulphuric acid mist may be commercially utilized to a high extent for the production of pressure steam in steamboilers, oil distillations or other known operations embodying heat transfer.

Briefly stated, my invention comprises burning refinery wasteproducts employing excess quantities of air in any knowntype furnace used for such purpose, either alone or in conjunction with other hydrocarbons, mixing a gaseous combustible reducing agent with the heated products of combustion before the temperature of the combustion productsis reduced below 1650 F., in quantities suflicientto combine with and reduce the free oxygencontent of said combustion products "to less than 5 per centby volume, thereby substantially preventing sulphur trioxide or sulphuric acid mist formation during passage thereafter through heat transfer equipment and conduit into the atmosphere. 7 v

The reducing agent may be any volatile hydrocarbon, nat'ural gas or mixtures of methane with hydrogen and'other hydrocarbon gases, or water gas consisting of hydrogenand carbon monoxide, and/or producer'gas comprising carbon monoxide and nitrogen, and the like.

' An object of the invention is to dispose of refinery Waste products by combustion with excess quantities of air at 'high temperature, utilizing a partof the heat'for generating pressure steam or oil heating purposes, withoutthe formation of appreciableamountsofisulphuric acid mist, and then discharging the products of combustion thorugh high stacks into the atmosphere.

AnotherIobject of the invention is to utilize acid sludges and "and tars derived from refining hydrocarbons with sulphuric acid, by combustion from for commercial heating purposes without the formation of sulphuric acid mist.

Various other objects and advantages of the present invention will be apparent from the description of the preferred method or example embodying the invention, which will now be more fully explained by reference to the accompanying diagrammatic drawing.

In the drawing pipe I, controlled by valve 2, connects burner 4 to a supply of refinery waste products, such as acid sludge or tar, malodorous gases, or refinery aerosols. Pipe I2, controlled .by

valve 3, connects burner 4 to a steam supply.

Pipe I0, controlled by valve II, connects burner 6 to a supply of hydrocarbon gas or oil. Burner 4 is provided with air inlet passages 5. 9 represents a conduit or stack connected to furnace 6, through which the combustion products pass and are discharged into the atmosphere, at the required elevation. Pipe 8, controlled by valve I3, is connected with a source of a hydrocarbon gas, Water gas, or producer gas, terminating Within the furnace and provided therein with spray nozzles I5 for introducing the required amounts of said gases. I4 is a water or oil heater coil through which water or oil is continuously passed and heated for the production of steam for distillation purposes, said coil It being connected to steam boiler equipment and/or oil evaporation and fractionation equipment not shown.

The preferred process as carried out in the apparatus just described is as follows:

Furnace 6 is first heated to a temperature in excess of 1650 F., preferably between 2000 and 2500 F., by the introduction and combustion of a hydrocarbon oil or gas with air. The hydrocarbon oil or gas is introduced into furnace 6 through burner 4 from pipe I0 controlledby valve I I. The air to maintain combustion passes through inlet passageway 5 surrounding burner 4 and controlled by shutters or other mechanical means. I

When furnace 6 has been heated to a temperature in excess of 1650 F., the flow of hydrocarbon oil or gas into furnace 6 is reduced or discontinued by closing, or partially closing, valve II in pipe I 0. Then refinery sulphur bearing Waste products either alone or mixed with hydrocarbon oil are caused to pass from their source of production or from storage through pipe I and into burner 4, the flow being controlled by operation of valve 2. At the same time a regulated flow of steam from pipe I2, controlled by valve 3, is introduced into burner 4, which sprays the waste products into furnace 6 in a finely divided condition, wherein they are commingled with air coming through air inlet passages 5. in an amount suflicient to completely consume or burn the spray of waste products with the formation of carbon dioxide, water vapor, and sulphur dioxide gases.

The quantity of air introduced into furnace 8 through air inlet passages 5 is regulated so as to maintain an excess volume of free oxygen in the combustion gases of not less than 5 per cent as they pass over the top of bridge wall I. The quantity of excess air introduced into-furnace 6 depends upon the hydrocarbon content of the waste product being burned.

For refinery waste products containing a high percentage of sulphuric acid, the percentage of air introduced into furnace 6 may be such that the excess free oxygen content in the combustion gases may be approximately 10 to 17 per cent by volume, although preferably this percentage of free oxygen in the combustion gases is maintained between 5 and 10 per cent. 7

In general, the quantity of air and quantity of hydrocarbon oil or gas introduced into furnace 6 along with waste products is governed by the temperature of the products of combustion passing over bridge wall I, such temperature preferably being maintained between 2000 and 2500 F. The completely oxidized products of combustion at a temperature of approximately 2000 to 2500-F., having a free oxygen content ranging from 5 to 17 per cent by volume, after passing over bridge wall I, are mixed with a suflicient quantity of a gaseous reducing agent from pipe 8 regulated by valve I3, which combines with and reduces the free oxygen content of the combustion gases to less than 5 per cent by volume, preferably ranging between and 1 per cent. In case the combustion gases passing over bridge wall I contain 10 per cent by volume free oxygen, ap-

proximately 5 volumes of natural gas, and/orabout 10 volumes of water gas (CO and H2), and/or about 25 to 30 volumes of producer gas would be introduced for each 100 volumes of com-- ing agent being increased until white fumes-no.

longer appear in the discharged stack gases.

After reduction of the free oxygen content to 1 per cent or less the said hot combustion gases at temperatures ranging from about 2000lto 2500 F. are passed in heat exchange relation ship to water or oil flowing through heater coil I I and'then into stack 9 which discharges the gases at temperatures ranging from about 800 to,

950 F., into the atmosphere without appreciable amounts of sulphuric acid mist therein.

While the process herein described is well adapted for carrying out the objects of the present invention, various modifications may be made,"

such for example as the use of standard boiler tube equipment in place of heater coil I4, and the invention includes all such modifications as: come within the scope of the appended claims;

I claim: 1. Process of burning sulfur-bearing petroleum waste products with substantially no formation of sulfur trioxide in the final combustion prod-" ucts, which comprises burning said waste "pr'od-- ucts in a combustion zone in the presence of an excess volume of oxygen of from about 5% to about 17% to effect substantially complete combustion at a temperature at least as high as that as. which sulfur trioxide'decomposes to formsulfur dioxide and oxygen so that substantiallyno sulfur trioxide is formed, substantially reducing the proportion of excess oxygen in the products of. combustion with substantially no loss of heat therefrom'by introducing into said products: of combustion in a second zone a sufiicient quantity of gaseous reducing agent to reduce the-- excess volume of oxygen therein to below about 1%, subsequently cooling said'products of com-.'

bustion to Within that temperature rangewatf which the equilibrium with respect to sulfur ell-{1 75.,

oxide, oxygen, and sulfur trioxide favors the formation of sulfur trioxide with substantially no formation of sulfur trioxide in. said products of combustion.

2. Process of disposing of oil refinery sulfurbearing petroleum waste products, resulting from the treatment of petroleum products with sulfuric acid, by combustion with substantially no formation of sulfur trioxide in the final combustion products and with the utilization of the heat content resulting from the combustion, which comprises burning said waste products in acombustion zone in the presence of an excess volume of oxygen of from about'5% to about 17% at a temperature between about 2000 to about 2500" F., passing the resulting products of combustion containing the excess oxygen to a second zone and therein reducing the volume of said free oxygen below about 1% with substantially no loss of heat from said combustion products,

by introducing into the resulting combustion products in said second zone a suflicient quantity of gaseous reducing agent to combine with the free oxygen and thereby reduce the excess volume thereof, contacting said hot products of combustion in heat exchange with an object to be heated and thereby cooling said products of combustion to a temperature below about 1650 F. and within the temperature range of 900-1650 F Within which sulfur dioxide tends to react with oxygen to form sulfur trioxide but with substantiallyno formation of sulfur trioxide in said products of combustion, and then discharging the final products of combustion substantially free from sulfur trioxide into the atmosphere.

3. Process of burning acid sludge, resulting from the treatment of petroleum products with sulfuric acid, with substantially no formation of sulfur trioxide in the final combustion products and with the utilization of the heat content resulting from the combustion, which comprises burning said acid sludge in a combustion zone -in the presence of an excess volume of oxygen greater than about 5% at a temperature above about 1650" F., so that substantially no sulfur trioxide'is formed, reducing the volume of excess free oxygen in the resulting combustion products to below about 1% with substantially no loss of heat from said combustion products by introducing into the resulting combustion products a sufficient quantity of gaseous reducing agent which combines with the free oxygen and thereby reduces the excess volume thereof, contacting said hot products in a second zone of combustion

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