US1921602A - Process for heating oil - Google Patents

Description

Aug. 8, 1933.

B. N.v BRoxDo PROCESS FOR HEATING OIL Filed oct. 23, 192s 2 Asheets-sheet 1 EENMM/A/A/eo/DO INVENTOR-` QE w@ BY l' A TTORNE Y.

Aug. 8, 1933. B. N. BRolDo PROCESS FOR HEATING OIL 1926 '2 Sheets-Sheet 2 Filed 0012. 23

.BEM/AMW /1/ SPO/p0 v INVENTOR.

'ax/ met ATTORNEY.

Patented Aug. 8, 1933 PROCESS FOR HEATING OIL Benjamin N. Broido, New York, N. Y., assigner to l y The Superheater Company, New York, N. Y., ya Corporation of Delaware Application otoberzs, 1926. Aswarm. 143,115 `2 claims. `(C1. leef-116) This invention relates to a continuous oil heating and cracking process. .l

The principal object of the invention is` to Y provide process of this :character of marked 5 simplicity, high thermal eiciency of voperation and by means of which a greater yield of the lighter hydrocarbons may be obtained from any given crude oil.

The invention depends in a great measure 10 upon the following principles: In the operation of-'oil stills it has been found that the temperature of the furnace gases which sweep over the still tubes vshould notexceed`1500 or 1600 de\ grees, because if higher temperatures are' permitted, such high temperatures causeu the oil in the tubes to be converted to'carbon, thus not only clogging the tubes, butin addition, re-V ducing the yield of commercially valuable constituents obtained from the distillation process. 20 As the temperature of the furnace gases ordi narily would reach va much higher degree than the gure abovestated, it has heretoforebeen the practice, in order to prevent such higher figure from, being reached, to operate the still with a very highpercentage of excess air for the purpose 'of cooling the furnace gases'. Such a procedure is wasteful and as a result the thermal efliciency of a still so operated is comparatively low. `It has further been found that if steam is caused to bubble through atank `containing oil, hydrocarbons are evaporated and liberated at a temperatureV lower thanQtheir boiling point. The reason for this phenomenon is not entirely clear but it is believed that the light hydrocarbons evaporate at a pressure lower than normal because of the reducedupartial pressure of the oil in the mixed bo'dy of oil and steam: L l Y Briefly stated, the present Vinvention contem-` plates heating the oil in atube or pipe still to a cracking' temperature and temporarily main-A taining. the oil so heatedv under suflicient pressure to prevent evaporation ofthe lighter hydrocarbons. The heated oil under such pressure is passed through a heat exchanger in counterflow relation with the` cold incoming oil, thus servingr to preheat the incoming oil and to cool the heated oil below a temperature at which V,the

50 lighter fractions will vaporize,` The cracked oilis then passed through al pressure reducing deviceland into a vaporizer wherein it is heated by steam supplied from any suitable source and preferably from a water screen or coil inter- 5 posed between the first oil containing tubes of the tube or pipe still and the furnace, a conside erable portion of the steam so suppliedrbeing permitted to bubble through the oil to heat the oil and to secure the liberation of the llighter (.60 hydrocarbons, as described above. Due to the reduction of the pressure inrthis vaporizer, and

the reheating offthe oil thereingthe light4 hydro carbons formed' by the cracking process Vare evaporated, and the vapors therefore liberated.. After being liberated in the vaporizer, the light' er hydrocarbons are passed throughv a fractionating tower and condenser and to a collecting tank in the usual manner. By using aw'ater screen or coil betweenth'e furnace andthe oil tubes of the pipe stillQfI Asecure' the important advantage of cooling, `the 'PATENT OFFICE? furnace gases before they reach the oil'v ltubes,

thereby Snot only protecting the oil tubes, but alsol preventing the formation or'baking of exi cessive carbon'in these tubes. In addition, the i use ofthe water screen avoids the necessityfor the introduction of excessive air into the still for cooling the furnace gases. Furthermore, by employingjthe water screen to .generate steam, which is used later on in the process to heat the cracked oil in the vaporizer, a very-high thermal `eiiciency of the entirefapparatus and process, is securedg' I l ,y

I am aware that` it i's not ,broadly new to heat the oil in a pipe still to the cracking temperature andv to maintain" it 'under `sufficient pressure in its passage through a heat exchanger.

linrwhich the temperature ofthe oil is reduced tota degree below which thelighterhydrocarbons will vaporize, and then to'reduce the Dressure to-slightlyabove. atmospheric and reheat the oil i tor liberate the lighter hydrocarbon formed at. the cracking temperature, as disclosed, f or example, in the patent to Richey et al. #1,530,091, granted March 1'7, 1925.]In the Richey process, the reheating `of the oil, `after itspressure is reduced, is done` by means ofthe hot oil which passes fromthe pipe still, and-as a result, it is necessary to employ aplurality rof vaporizers which are-maintained at different temperatures to producea fractional`distillation, this being necessary in the process of the patent in order to Vavoidherating .the lighterhydrocarbon to the same ternpe'rature` as'ithe heavier ones. In addition, in theprocessofthe patent, the pipe still employed is the usual one in which it is necessary to introduce an excess of air to prevent the temperature of the. furnace` gases from exceeding a degreeabove Vwhich/carbon would beformed in the oil inthe pipe still tubes. A suitable' constructional example' of anv apparatus embodying the 'principles of the Apresent inventionis shown in the accompanying drawings, in which Fig. 1 is a somewhat diagramjmatic side elevation kof `a complete installation, Y

parts. ofV ywhich are shown in section;A lFig. K2 'is a planview of the installation shown` in Fig.' 1v and also showing parts of the apparatus inl section, Vand Fig. 3 is a'longitudinal section of one portion of the apparatus.

yAs shown in the drawings, the numeral 10 los " banks of oil tubes ll and 12, the tubes 1l being located in a second gas passgl forming a heating chamber communicating with the stack 14 and the tubes 12 being located in a'rst gas pass 15 situated above the furnace. be treated is pumped from any suitable source of supply by means of the pumpil through the pipe 17 to a heat exchanger 18 fromwhich it passes through the pipe -19 to the second bank of oil`tubes 11 of the pipe still 10 and flows in series through these tubes and thence in series to the bank of tubes 12. YThe oil is heated in the pipe still to a temperature of about 900 F. and then passes through'the pipe line 20 to the kheat exchanger 18.

The temperature to which the oil is heated will Vary with diiferent oils, and the pressure ordinarily of the order of 600 lbs. per square inch will also Vary,'as Whatever pressure necessary to keep the` oil in liquidphase will be em-I ployed and this pressure will be Vdetermined by the character of the oil treated. g .Y

, The heat exchangerr 18 consists of the pipes 21- and22, the latter being arranged concentricallywithin the pipes 21 and the two concentrically arranged pipes forming a tortuousA coil through which the oil passes, the heatedroil kfrom the pipe still flowing counter to the cool oil supplied to the heat exchanger through `the pipe 17. In its passage through the heat exchanger, the cracked oil from the pipe still is cooled toa temperature of about 300, while theV cool oil supplied through 'the pipe 17 is preheated to approximately the same temperature. During its passage through the tubes of the pipe still and thev heat exchanger, the o il is maintained above a pressure suiiicient to keep it in ak liquidv in the oil in the pipe still and is carried over in suspension, is deposited. The lown pressure oil is thencarried by the pipe 26at tov a vaporizer 27 in which the cracked lighter hydrocarbons are vaporized. The vaporizer 27 is provided with a suitable bale 27a which forces the oil entering the vaporizer to follow a tortuous path to the discharge pipe 26h Vwhich 'carries oil* the residuum toany suitable point of storage or disposal.

Interposed between thel furnace of the pipe still 10 and the bank of tubes 12 isa row of water tubes`28, over which the furnace gases sweep beforereaching the oil tubes 12 and`11,

thus cooling the furnacev gases to the desiredV temperature. Steam generated in the water tubes 28 is'led by the pipe 29 to the vaporizer 27,` a considerable portion of the steam being permitted to bubble up through the oil within the yaporizerV from the perforated pipe`2v9ay and another portion of such steam being circulated through a closed coil 30a to heat the loil in the vaporizerto the desired temperature. The closed vcoil is supplied ythrough a pipe 30 which The oil to branches from the pipe 29. Condensate from the vclosed coil. is circulated back to the water tubes 28, by means ofthe pipes 31,`32,and a pump 33. 'Water' to replace that discharged in the form of steam through the pipe 29a is supplied to the system including the Water tubes 28 through the supply line 28a from Yany de-` sired source (not shown) under whatever pressure may be necessary to overcome the pressure existing in the water circulating and .steam generating system. This pressure obviously may Vary indiiTerent cases.

Located above the 'vaporizer 27 is a bubble A drain pipe 42, provided lwith a shutoff valveV 43, is provided for permitting the system .t0 be drained when desired.l l w f The method ofV operation and. vthe proc--` ess performed by lthe apparatus will be readily understood from the above description, as the. functioning of the apparatus has been set forth in connection withthe-V description of thevarious parts ofthe apparatus. It will be seen ythat the, process and apparatus are very simple, that the provision of the water tubes ahead of the oil tubes, in which Water tubes steam is generated, which steam is used for reheating the oil bycausing the steamY to bubble through the oil, results in Vsecuring a process and operatingV and installation cost. Y

While I have Vshown and described an apparatus in Which the steam generated in the water tubes is Aemployed for the'reheating fof the oil in the vaporizer it Will be apparent that the principles of ytheinventionare not limited to the specific apparatus and arrangement shown, the vaporizer shown being merely. an illustrative example of a heating device which could obviousf lybe employed for any purpose or processl Work.

Y I claim: y D 1. Themethod of conserving heat infanfoil crackingfurnace which comprises burning fuel inthe furnace with small excess of air, passing heat-absorbing fluid 4through passages Within the furnace for cooling the gases before they reach the oil to be cracked, theheat absorbing appa'ratus'ofr high thermal eiciency and alow` iiuid being diierent and separate from the oil ing maintained separate from' the oil to be cracked, and allowing the gases to passafter passing said first mentioned passages around passages through Which the oil to be cracked is passing. V 1 f BENJAMIN N; BRQIDQ-`V` ylll() Ill)

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