US3806426A - Gas flow through horizontal coke oven regenerator sections - Google Patents

Abstract

Improved gas flow through horizontal coke oven regenerator sections and improved regenerator design for providing such gas flow. Lean gas and air flow through an oven regenerator section in a substantially uniform fashion during upflow and the waste gas flows through a regenerator section in non-uniform fashion during downflow. Specifically waste gas flows through a regenerator section in a manner that is greater than average downflow of waste gas is provided at both end portions of the regenerator to provide effective end flue heating and counteract heat losses at the regenerator ends due to radiation and to atmospheric air infiltration. A plurality of Venturi like sole flue ports having varying cross-sectional configurations are provided for regulating gas flow through the regenerator.

Description

April 23, 1974 E. J E E'TAL GAS FLOW THROUGH HORIZONTAL COKE OVEN REGENERATOR SECTIONS Filed Aug. 10, 1971 5 Sheets-Sheet 1 Z 2 2 2 2 2 2 2 Q i Q Q 3 Sheets-Sheet 2 J. HELM ETAL April 23, 1974 GAS FLOW THROUGH HORIZONTAL COKE OVEN REGENERATOR SECTIONS Filed Aug. 10, 1971 GAS PLOW THROUGH HORIZONTAL COKE OVEN REGENERA'IOR SECTIONS Filed Aug. 10, 1971 5 Sheets-Sheet 3 United States Patent 3,806,426 GAS FLOW THROUGH HORIZONTAL COKE OVEN REGENERATOR SECTIONS Edward J. Helm and James M. Airgood, Pittsburgh, Pa., assignors to Koppers Company, Inc. Filed Aug. 10, 1971, Ser. No. 170,492 Int. Cl. Cb 1/06, 5/14 US. Cl. 202-141 6 Claims ABSTRACT OF THE DISCLOSURE Improved gas flow through horizontal coke oven regenerator sections and improved regenerator design for providing such gas flow. Lean gas and air flow through an oven regenerator section in a substantially uniform fashion during upflow and the waste gas flows through a regenerator section in non-uniform fashion during downflow. Specifically waste gas flows through a regenerator section in a manner that a greater than average downflow of waste gas is provided at both end portions of the regenerator to provide effective end flue heating and counteract heat losses at the regenerator ends due to radiation and to atmospheric air infiltration. A plurality of Venturi like sole flue ports having varying cross-sectional configurations are provided for regulating gas flow through the regenerator.

BACKGROUND OF THE INVENTION (1) Field of the invention This invention relates to the heating of regenerative horizontal coke ovens, and more particularly to an improved gas flow pattern through the regenerator sections of such coke ovens.

(2) Description of the prior art Gas flow patterns in regenerative horizontal coking retort ovens have long been a matter of primary concern in the coke oven art, because efficient heat exchange and uniform heating of a coking chamber is one of the essential prerequisites in producing a quality metallurgical coke. It was thought that a uniform gas flow pattern of upflow and downflow of gases around a coking chamber and through a regenerator in an oven would provide an optimum thermal efficiency. U .8. Pat. 2,334,612 provides a coke oven structure and regenerator design therefor which permits of substantially uniform flow throughout the oven regenerator during both upflow and downflow periods whereby maximum regenerator efliciency might result. There a plurality of regenerator ports are provided for connecting a regenerator sole flue with a regenerator. The regenerator ports may have varying cross section for compensating for pressure variations in the sole flue whereby uniform flow through the regenerator during both upflow and downflow periods is obtained. The pressure conditions within the sole flue are such that the pressure differential between the sole flue and the bottom of the regenerator on upflow gradually increases from the inlet end of the sole flue toward the closed end, and on downflow the pressure differential gradually decreases from the open end toward the closed end of the sole flue. The Venturi type ports with graduated top and bottom diameters compensate for these differences in pressure differential. An article entitled The Flow of Air and gas in Vertical Flue Coke Ovens by the patentee of the aforementioned patent, published in Blast Furnace and Steel Plant, May 1945 provides a similar means for promoting a more uniform distribution of air or lean gas from sole flues into the regenerator compartments thereabove, and at the same time obtaining more uniform downflow in the same regenerators and sole flue ports for waste gas on the next reverse of the gas flow through the regenerator. It has now been found that, even though 3,806,426 Patented Apr. 23, 1974 ice substantially uniform gas flow through the regenerator section of a coke oven theoretically may provide optimum thermal efliciency, whether the regenerators be of the compartment type or whether they be a single regenerator section extending the length of a coke oven battery, such uniform flow may result in poor end heating of the battery. More particularly, poor end flue heating at the coke and pusher ends of a coking chamber within a battery may result. It is believed that the poor end flue heating may be caused by heat lost near the ends of the oven regenerators caused both by radiation losses to the atmosphere at the regenerators ends and by infiltration of excess cold air from the atmosphere. It is further believed that excess air infiltration occurs primarily on the downflow cycle within a downflow regenerator since a substantially higher suction exists within a downflow regenerator than within an upflow regenerator. Therefore the heat loss occurring at the regenerator end sections can prevent a satisfactory preheat of combustion air in the end flues on the upflow cycle. Lack of sufiicient preheat in the air is believed to result in insufiicient heating of an end flue, and is more pronounced where compartment-type regenerators are employed in a coke oven to prevent mixing of air throughout the length of an oven regenerator section.

This invention provides an improved gas flow pattern through a regenerative coke oven whereby excessive cooling effect in the regenerator end portions thereof due to radiation heat losses and cold air infiltration into the heating system is counteracted. Additionally, the invention provides a gas-distributing means in a coke oven whereby combustion gases formed in a heating flue may pass into an oven regenerator section in a manner whereby the end portions thereof are adequately and efliciently heated. Other advantages of the invention will become apparent as this specification proceeds.

SUMMARY OF THE INVENTION Improved gas flow through the regenerator sections of a horizontal regenerative coke oven is provided along with improved regenerator sole flue port design whereby lean gas and air may flow through an oven upflow regenerator section in a substantially uniform fashion and wherein, during the following reversal, hot waste gas flows downward through the same regenerator in nonuniform fashion in a manner whereby a greater than average downflow of waste gas is provided at both end portions of the downflow regenerator. With this arrangement effective end flue heating may be obtained and heat losses at the regenerator end portions due to radiation and to excess atmospheric air infiltration is substantially counteracted.

An array of sole flue rider tile is provided disposed between the regenerator base portions and a sole flue carrying lean gas or air to the coke oven battery through which gases may pass into and out from a regenerator in the manner described hereabove. Most preferably the array of sole flue rider tile so disposed comprises a plurality of Venturi type sole flue ports having varying cross-sectional configurations, whereby such sole flue ports may be disposed lengthwise of a regenerator for controlling gas flow therethrough at pre-selected rates due to the carefully graduated top and bottom openings of the ports. The array of Venturi type sole flue ports may be formed by first selecting a given set of desired flow conditions and flow patterns for gases passing through a regenerator section, and thereafter calculating pressure conditions from port to port within a sole flue which may yield the desired flow pattern, both on upflow and downflow, and finally providing Venturi type sole flue ports which provide the preselected and predetermined desired flow pattern. In that fashion, an array of sole flue ports may be provided for obtaining the desired uniform upflow of lean gas and air through an upfiow regenerator and non-uniform downflow of waste gas through a cooperating downflow regenerator.

Other advantages and details of the invention will become apparent by reference to the appended drawings and as the following more detailed description thereof proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic vertical section taken transversely of a coke oven battery of the well-known Koppers- Becker crossover type coke oven wherein there is additionally embodied the features of the invention. The partial section AA thereof is taken longitudinally through a heating wall and a regenerator chamber, While section BB thereof is taken through a coking chamber and a regenerator chamber, along line BB of FIG. 2.

FIG. 2 is a section taken along the line IIII of FIG. 1.

FIG. 3 is a section taken along the line III-III of FIG. 2 illustrating in top plan a sole flue port assembly useful in the invention.

FIGS. 4, 5 and 6 each represent sole flue ports of varying cross section employed in a sole flue port array according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS. 1 and 2, a coke oven battery 10 is illustrated and comprises in general a plurality of coking chambers 11 and heating walls 12 that are disposed in alternation, progressing in the lengthwise direction of battery 10. Heating walls 12 are made up of a series of vertical flues 13, which generally comprises individual heating chambers, disposed in side-by-side relationship extending crosswise of battery 10. In the flues 13 a combustible gas is burned to provide heat along heating walls 12.

Vertical flues 13 are arranged in groups of several heat ing flues 13, each group having a common crossover duct 14 whereby combustion products of each flue 13 flow upward and through a common horizontal flue 16 for each group of flues, through crossover duct 14, over the top of a coking chamber 11 and down into a corresponding group of flues 13 on the other side of a coking chamber 11. Thus, each crossover duct 14 can be considered as connecting to flow groups of flues 13, one of each such pair of connected flow groups receiving for a period of time the waste combustion gases from the burning operation being conducted in the other group of the pair. At the end of a period of time, the system is reversed and thereby the relative functions of these flow groups is alternated.

Beneath each coking chamber 11 in the oven there are provided a series of cross-regenerators 17 extending in a parallel direction to the series of vertical flame flues 13 in each heating wall 12 and communicating directly therewith. The flame flues 13 and cross-regenerators 17 are connected by suitable means such as a regenerator port and duct assemblies 18. Each heating flue 13 is individually so connected with two cross-regenerators 17 therebeneath, each such regenerator 17 being arranged to preheat combustion air at such times as the heating flues are being under-fired with rich fuel gas as, for example, obtains when the oven of the battery is under-fired with coke oven gas. One of the regenerators 17 of a pair of regenerators with which each flue 13 is connected is likewise adapted to preheat a lean fuel gas delivered thereto from a lean-fuel-gas main flow box (not shown) in a conventional manner to an inlet 19 (FIG. 1) to a sole flue 20 for that regenerator. The provision of lean gas to a regenerator through a sole flue therefor is well known, for example, in those instances where an oven is operated as a gas oven and is therefore under-fired with an extraneously derived lean gas, such as blast furnace or producer gas. The invention herein is especially useful in such ovens as well be more fully explained hereafter.

Each regenerator 17 contains checker brick 22 and the regenerators in general are divided, in a manner well known in the art, into two sets which, as mentioned hereinabove, operate in alternation. In FIG. 1 gas flow is shown through the regenerator section 17a (upfiow) at section A-A for preheating while at the same time a second regenerator section 17b (downflow) in section BB is receiving and discharging hot combustion products leaving the off set of flame flues 13 to thereby impart heat to the checker brick therein for preheating air or lean gas on the next reversal of oven operation. Preheated lean gas or air leaving upfiow regenerator section passes into flues 13 and is there burned for heating a wall 12 in contact with the burning or on flues. Burners and the like are not here described by may be of conventional or known type such as described in Becker Pats. Nos. 3,222,260 and 2,100,762.

As best shown in FIG. 1, an array of sole flue rider tile 31 are provided disposed between regenerator sole flue 20 and the base of a rengerator 18. Each of the sole flue rider tile 31 has a port 30 or passageway therethrough through which gases may pass from sole flue 20 to regenerator 17, both of which are provided with appropriate entryways for gases located in line with the channels in sole flue rider tile. Each of sole flue rider tile 31 may comprise a conventional refractory composition stable under coke oven conditions. The array of sole flue rider tile and ports 30 extends the length of a regenerator 17 and comprises a plurality of sole flue ports 30 having varying cross sectional configurations. Preferably each sole flue port 30 is a Venturi type port having top and bottom diameter portion openings, as at 32 and 34 respectively (FIGS. 4, 5 and 6) which may be graduated in size for providing a predetermined, desired air, lean gas or waste gas distribution from end to end of the regenerator 17 despite the difference in pressure differential along the length of the sole flue 20. Accurate graduation of the top and bottom diameters of the sole flue ports 30 Will pro duce a corresponding regulation of flow rate through the Venturi type ports.

The array of sole flue rider tile 31 extending the length of a regenerator 17, and disposed between that regenerator and a sole flue 20 therefor, is provided with a plurality of Venturi type sole flue ports 30 having varying cross sectional configurations whereby flow is regulated through the sole flue ports in a desired fashion. More particularly, according to the invention, flow of lean gas or air through a regenerator 17 during upfiow cycle is regulated whereby lean gas or air flows through a regenerator 17 in a substantially uniform. fashion for providing optimum regenerator efliciency and permitting the desired distribution through regenerator ports 18 into flame flues 13. At the same time hot combustion gases formed in flame flues 13 may pass through horizontal flue 16 and crossover duct 14 into an oif set of flues 13 and finally into a corresponding downflow regenerator 17. The flow of hot combustion gases, or waste gas, through downflow regenerator 17 is controlled so that both ends of the regenerator section receive a volume of waste gas in excess of the volume passing through the center portion of the regenerator. For that reason, the end portions of the downflow regenerator 17 are efliciently and effectively heated by the waste gas in a manner whereby the cooling effect heretofore known due to radiation losses and cold air infiltration at the regenerator end sections is substantially counteracted. Thus, the end portions of the downflow regenerator are sufficiently preheated whereby lean gas or air entering the regenerator on the next reversal for preheating prior to entering a flame flue 13 above the regenerator is sufliciently preheated, and consequently, poor end flue heating is avoided.

For providing the improved gas flow pattern as described hereabove, the Venturi like sole flue port array is appropriately sized for yielding that desired gas flow.

In FIG. 3 a top plan view of a sole flue port assembly including two Venturi like sole flue ports 30 is shown in top plan taken along the line III-III of FIG. 2. Each sole flue port pair is formed of a pair of refractory sole flue rider tiles 31 each having been appropriately formed for providing a pair of identical Venturi forms of desired cross sectional configuration. Rider tiles 31 are adapted to be fitted together face to face, and may be aligned and held in place by means of a key-style lock formed of an outwardly extending refractory portion, or key, 33 extending into an appropriate opening, or keyway, 35 provided in respective matching pairs of rider tiles 31. The Venturi like sole flue ports 30 formed of a pair of tiles 31 have varying cross sectional configurations and are spaced apart along the length of a regenerator 17. In FIG. 4 a rider tile 31 is shown including a Venturi like shape therein having a wider top opening or top diameter portion 32 than bottom diameter portion 34. In FIG. 5 a tile 31 has a Venturi form having nearly identical top and bottom diameter portions 32 and 34 respectively. In FIG. 6 a rider tile 31 has a Venturi shape therein having a top diameter 32 smaller than its bottom diameter 34. Each of the foregoing Venturi like configurations will, of course, permit of fluid flow at differing rates therethrough.

It will be appreciated here that providing an appropriate array of sole flue ports 30 of the type described will permit of the improved oven gas flow pattern according to the invention. Specifically, an improved method of heating a coke oven is provided wherein end portions of the oven are effectively heated. By way of example, it has been found that for a coke oven battery comprising eighty-one coking chambers, each approximately 15 ft. high and 50 ft. long, with a single waste heat flue, that an array of seventy-nine Venturi like sole flue pairs extending lengthwise along the base of a regenerator, disposed between the regenerator and a sole flue for that regenerator, as described hereinabove, the sole flue port configuration as listed in Table I hereafter was suitable.

TABLE I.SOLE FLUE PORT SIZES Port Port number Bottom Top number Bottom Top (2 ports/ diameter, diameter, (2 ports/ diameter, diameter,

number) inches inches number) inches inches 1 Open end (air feed): 3 Closed end.

Each of the sole flue port pairs listed in the foregoing table was formed of pairs of rider tiles 31 having appropriate Venturi forms formed therein each tile being 7 inches wide and 7 inches thick. Each had an overall length of about 13 inches. The top and bottom openings in each port therein were well rounded and had a radius of not less than about inch, for providing an effective port length of about 6% inches. The foregoing array of tiles provided substantially uniform flow of air through the entire array of ports across the lengths of the regenerator sole flue during upflow. At the same time waste gas flowing through a downflow regenerator flowed through the first three port pairs on each end of the regenerator at about 1.36 times the average volume flow, through the next four port pairs on each end at about 1.19 times the average flow, through the next three port pairs at about 1.02 times the average flow and through the remaining ports at about 0.94 times the average flow. In that fashion the end portions of the regenerator are effectively and efliciently heated by the high volume of waste gas passing therethrough, and good end flue heating was obtained.

It should be noted here that sole flue port sizes in the array as set forth in the example above are made with the aid of an electronic computer program for calculating the pressure conditions from port to port and through each port within a sole flue array, both on upflow and downflow, while making appropriate allowances for friction losses within the sole flue, changes in the velocity pressure along the length of the sole flue, and for friction losses through the multiplicity of sole flue port openings. Additionally, such factors as sole flue roughness, changes in air and waste gas temperature, density, viscosities, and the like are also accounted for in the calculation. Thus the sole flue port sizes and configuration may be formulated for the desired gas flow pattern according to the invention. It may also be noted that the particular gas flow distribution attained in the foregoing example is not necessarily a limiting distribution, but is illustrative of that useful in the particular coke oven battery there described. It should be appreciated that optimum gas flow patterns according to the invention will vary with such factors as oven height and oven length, waste gas collection systems, height and width of the regenerators, and the like. It is believed that a flow ratio of between about 1.2 to 1.4 of waste gas volume to the end portions of a regenerator to the average overall waste gas flowing through an entire oven regenerator section should be, in most cases, sufiicient to attain eflicient end flue heating. By using the techniques described and an array of sole flue ports in a regenerator section according to the invention, there may be provided in substantially any case a gas flow pattern for yielding substantially uni form upflow of air or lean gas through an upflow regenerator, and additionally, for yielding desired increased flow of waste gas through the end portions of a particular regenerator section. Thus, suflicient heat may be provided to overcome any heat losses at the oven end portions due, for example, to radiation losses or infiltration of cold air into the oven.

It may be appreciated here that while the foregoing description has been with reference to a Koppers-Becker type crossover regenerative coke oven having an undivided regenerator section with appropriate sole flues therefor, the invention as described is not necessarily limited thereto. For example, in a regenerative coke oven having compartmentalized regenerators, end flue heating is equally important, and such ovens would likewise benefit from the improved gas flow pattern and array of sole flue ports for providing that pattern according to the invention.

According to the provisions of the patent statutes, we have explained the principle, preferred construction and mode of operation of our invention and have illustrated and described what we now consider to represent its best embodiments. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

1. A regenerative coke oven having a regenerator with end portions and an intermediate portion and a sole flue extending beneath the entire length of said regenerator comprising,

a plurality of sole flue rider tile positioned between and separating said regenerator from said sole flue positioned therebelow, said plurality of sole flue rider tile extending lengthwise along the entire length of said regenerator,

a plurality of ports in said plurality of sole flue rider tile vfor the upflow and downflow of gases between said sole flue and said regenerator, said plurality of ports extending along the entire length of said regenerator, and

said plurality of ports having varying cross-sectional configurations to regulate the upflow and downflow of gases between said sole flue and said regenerator so that gases pass upwardly at a substantially uniform rate of flow through said ports into said regenerator along the entire length of said regenerator, and downwardly at a non-uniform rate of flow from said regenerator to said sole flue to provide an increased downflow rate of flow of gases at both ends of said regenerator relative to the downflow rate of flow of said gases through the intermediate section of said regenerator.

2. A regenerative coke oven as set forth in claim 1 in which,

each of said ports has a Venturi like configuration with a top opening and a bottom opening.

3. A regenerative coke oven as set forth in claim 2 in which said sole flue includes,

a first open end portion and a closed end portion, said sole flue open end portion having an opening through which gases are introduced and exhausted from said sole flue, said top openings in said ports having decreasing cross- 5 sectional dimensions from said open end portion to said closed end portion of said sole flue. 4. A regenerative coke oven as set forth in claim 1 in which end of said sole flue rider tile includes,

spaced apart pairs of Venturi like ports, each of said pairs communicating with said regenerator and each of said pairs spaced from an adjacent pair of ports along the length of said regenerator. 5. A regenerative coke oven as set forth in claim 1 in which, 1 v

the rate of flow of downflowing gas at each end portion of said regenerator is a ratio of between about 1.2 and 1.4 to the average rate of flow of said downflowing gas through said regenerator. 6. A regenerative coke oven as set forth in claim 1 in 20 which, 7

said regenerator includes an undivided regenerator section extending along the length of said coke oven.

References Cited UNITED STATES PATENTS NORMAN YUDKOFF, Primary Examiner D. EDWARDS, Assistant Examiner us. c1. X.R.

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