US2641234A - Heater - Google Patents

Description

June 9, 1953 v. MEKLER ETAL HEATER Filed Jan. 25,` 194s Q11; ci@ Cf O Q10 4 Mmgrswm DS/QI.

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Patented June 9, 1.953

UNITED STATES PATENT OFFICE HEATER Application January 23, 1948, Serial No. 3,848

Claims.

This invention relates to improvements in heaters of the tubular type for the carrying out of chemical reactions by pyrolysis.

The particular object of our invention is to provide a tubular heater having relatively high heat input rates in the reaction zone which are substantially uniform throughout 360 of the tube cross section as well as along the length of a tube section.

Another object of our invention is to provide an improved baffle tile and tube construction which Will provide for a high degree of reradiation of heat to the tube units.

A further object of our invention is to provide a tubular heater having independently fired and controlled reaction sections and preheater sections in which the relatively cooled products of combustion from the reaction section are passed through balile iioor tile into the preheater section lwherein they are further heated by additional hot products of combustion generated in the preheating section for the desired heat transfer to the tubes therein.

A still further object of the invention is to provide an improved method for the pyrolytic treatment of light hydrocarbons or organic compounds in which improved control is provided for the rate of heat input and particularly of the residence time so that optimum yields of desired products may be obtained.

Further objects and advantages of our invention will appear from the following description vof a preferred form of embodiment thereof and in which:

Figure l is a substantially central vertical secg:

tion through one unit of a multiple tubular heater.

Figure 2 is a detailed and enlarged vertical cross section showing the bailie tile and tube construction.

The heater or furnace contemplated is a sub- .stantially rectangular chamber construction having side walls ID, end walls l2, a floor I4 and a closed roof or top wall I6. The heating tubes I8 are generally disposed within the furnace chamber delineated by these Walls and suitable heating means such as gas or oil or similar burners 2U -are placed in the floor, and as particularly contemplated herein, are also mounted at 22 in the end walls.

It is well known that heaters of this type may be suitably supported by columns 24 and a rain shed 26 is also provided. The furnace walls may .be provided with suitable insulating fire brick indicated at 28 and, if desired, the walls may be of separate panel unit construction such as described in the Reed et al. Patent 2,147,609. The products of combustion pass to a stack (not shown) interconnected With the gas discharge outlet 3U in a Well-known manner. While the unit shown is complete, it may be one unit of a multiple chamber heater where added chambers are found preferable to the construction of larger chambers.

Our invention is primarily concerned with a heating tube arrangement whereby most effective pyrolysis can be obtained. In designing heaters for preheating or cracking hydrocarbons especially for cracking gases at high temperatures, it is important to have uniform heat transfer rates about the entire circumference of the tube surface. This is particularly true in the Zones where the reaction or conversion takes place and it has been customary in the past to use molten metal baths which, of course, have many operating objections.

In the usual types of tubular heaters, especially in the petroleum cracking field, it is found that one side of the tube is relatively colder than the other. With gas cracking, some coke formation is likely to occur on the colder surface of the tube. Furthermore, where the tube skin temperatures vary around the entire periphery of the tube, there is often degradation and decomposition of the heated medium on the side of the tube where the temperature is considerably above the average. If the temperature is below average, then there is a reduction in conversion yields.

Unequal rates of heat transfer on the circumference of the tube also have the undesirable effect of increasing the tube stresses on the hot side particularly when the heat rates at operating temperature levels are of a high order of magnitude.

A further factor enters into the cracking of light hydrocarbons for the production of oleiins such as ethylene, propylene, butylene, or in cracking or pyrolysis of organic compounds for production of raw materials for chemicals and that is the control of the residence time at specified temperatur'e and pressure conditions. It is essential that provision be made for the variation of the residence time for different stocks for it is essential that the heaters be arranged to provide optimum residence time and heat rate inputs for the specied product as Well as for different charge materials.

In our construction, we provide independently red reaction and'preheater sections so arranged as to give such flexibility of operating conditions that the shape of the temperature curve and the We claim:

1. `A duid heater comprising a housing, vertically spaced, horizontally extending partitions dividing the interior of said housing into superposed chambers including an upper chamber, an intermediate chamber and a lower chamber, each of said partitions forming the roof of the chamber therebelow and the floor of the chamber thereabove and having gas exit apertures distributed over the area lthereof, burner means to conduct combustion in said lower chamber, burner means to conduct combustion in said intermediate chamber, and rows of fluid heating roof tubes within the lower and intermediate chambers respectively, beneath the respective partitions and distributed across the area thereof, said tubes being exposed for radiant heating by said combustion within the respective chambers and having inlet and outlet means and being connected for flow of a fluid to be heated rst through the tubes of one of the chambers and subsequently through the tubes of the other chamber, said gas exit apertures enabling diffused flow of combustion gas from the lower chamber through the other chambers in succession said partitions being formed of rows of tiles, said gas exit apertures being formed by spaces between the tiles, and the tiles of the partition which forms the roof of the intermediate chamber being supported on the adjacent roof tubes.

2. A fluid heater comprising a housing, vertically spaced, horizontally extending partitions dividing the interior of said housing into superposed chambers including an upper chamber, an intermediate chamber and a lower chamber, each of said partitions forming the roof of the chamber therebelow and the floor of the chamber thereabove, burner means to conduct combustion in said lower chamber, burner means to conduct combustion in said intermediate chamber, rows of uid heating roof tubes within the lower and intermediate chambers respectively, disposed beneath the respective partitions and distributed across the area thereof, and a row of floor tubes within the intermediate chamber, said partitions having gas exit apertures distributed across the area thereof and enabling a diffused flow of combustion gas from the lower chamber through the other chambers in succession, said gas exit apertures being located directly over the respectively adjacent roof tubes and being narrower than the latter to cause the escaping gas to flow around the upper side of the tubes, and said oor tubes being disposed directly over the gas exit apertures respectively of the partition therebeneath, with clearance for iiow of combustion gas around the under side of the tubes from said apertures to the intermediate chamber, the tubes of all of said rows being exposed for radiant heating by said combustion within the respective chambers and having inlet and outlet means and being connected for flow of fluid to be heated through the roof tubes of the intermediate chamber and subsequently through said iioor tubes and the roof tubes of the lower chamber, in succession, whereby the fluid may be preheated by the heat in the intermediate chamber and converted by the heat in the lower chamber.

3. The heater of claim 2 wherein the intermediate chamber has side wall tubes connected to the roof tubes of the intermediate chamber to receive the fluid therefrom and connected to said floor tubes to deliver the fluid thereto.

4. A fluid heater comprising a housing having a lower wall, a vertical dividing wall extending ,6 upward from ythe'lower wall` of said housing, horizontally extending partitions dividing the interior of the housing into la plenum chamber, a preheater chamber directly therebeneath and a pair of reaction chambers directly beneath said preheating chamber at opposite sides of said dividing wall, said wall extending into the preheater chamber and terminating below the top thereof, burner means for conducting combustion at opposite sides of said Wall within the preheater chamber and the reaction chambers, said partitions each forming the roof of the chamber therebeneath and the :door of the chamber thereabove and each having gas exit apertures distributed over its area, roof tubes within each of said reaction chambers and distributed across the roof area and exposed to radiant heating by the combustion within the reaction chambers, two groups of roof tubes in the preheater chamber distributed across different portions of the roof area, tubes at the side walls of the preheater chamber opposed to said dividing wall and exposed to radiant heating by the combustion within the preheater chamber, each of said groups of roof tubes having inlet means for fluid to be heated and the roof tubes of each reaction chamber having outlet means for said fluid, and connections for passing the fluid from one of said groups of tubes through the tubes at one of said side walls and through the tubes of one of the reaction chambers, in succession, and for passing the fluid from the tubes of the other of said groups'through the tubes at the opposite side wall and the tubes of the other reaction chamber, in succession.

5. A uid heater comprising a housing, a horizontally extending partition dividing the interior of said housing into superposed chambers, said partition forming the roof of the chamber thereabove and the floor of the chamber therebelow and having gas exit apertures distributed over the area thereof, a row of fluid heating roof tubes Within the chamber below said partition and distributed across the area of the partition, the tubes of said row being located respectively beneath said gas exit apertures, a row of fluid heating floor tubes within the chamber above the partition and distributed across the area thereof and located respectively over said gas exit apertures, burner means for conducting combustion within the chamber below the partition, burner means for conducting combustion within the chamber above the partition, said tubes being exposed for radiant heating by said combustion within the respective chambers and having inlet and outlet means and being connectedfor flow of a liuid to be heated first through the tubes of one of said chambers and subsequently through the tubes of the other chamber, and combustion gas outlet means for the chamber above the partition, said gas exit apertures being narrower than the tubes thereabove and therebelow and there being spaces between the partition and said tubes for flow of combustion gas around the tubes from the chamber below the partition to the chamber above the partition.

VALENTINE MEKLER. MARCEL J. P. BOGART.

` oTTo c. scHAUBLE.

EDWARD H. PALCHIK.

(References on following page) ,n-Rcfexenees Gitedin the file of ths'l patent r UNITE STATES PATENTS'.

Number Name vDame Stacy Oct, 14, 1914 5 Burroughs Feb. 18, 1930 Spencerv Aug, 2, 1932 `Grrebe et a1. June12, 1934 Schutt et al1 Aug. 17, 1937 Number 8 Name Date Reedy et al. Feb; 14, 1939 Zimmerman Feb. 14, 1939 Melder Aug. 27, 1940 Balcar- Oct. 15, 1940 Wilson June 17, 1941 Barnes `Sept;..28, 1943 Bogk Feb. 1.1, 1947 De Lorenzo July 20, 1948

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