200811402 九、發明說明： 【發明所屬之技術領域】 本發明係有關於火焰方式之加熱器，及其煙氣通道輸 送管系統。 【先前技術】 氫氣重組器單元被普遍地使用在石化工業中，以便可 從甲烷及水蒸汽中產生氫氣。一常用之氫氣重組程序運用 一如第1及2圖所示類型之習知重組器的加熱器2。此習知 ^ 加熱器2包括：一方形或矩形之輻射燃燒室4 ;複數列6 之處理管8，其延伸穿過輻射燃燒室4，並被塡充以催化 劑；一收集歧管系統1 0，其接收來自諸處理管8下端部處 ^ 之熱的製程產物；複數列向下點火燃燒器1 2，其被安裝在 ' 位於諸列6之管8間的輻射燃燒室4之頂部中；複數個煙 氣通道14，其被建構於燃燒室4內，並沿著燃燒室4之底 板1 6延伸於各相鄰對之管列6之間，及於最外側管列6及 0 燃燒室4之諸側壁之間；複數個入口孔1 8，其穿過諸通道 14之垂直側壁20，以便連續地接收在燃燒室4中所產生之 煙氣；一外部對流區段22，其可從熱煙氣回收熱；及若干 外部煙氣導管24,其可將熱煙氣從煙氣通道14之諸縱向排 放端部26輸送至此對流區段22。 在習知之頂部燃燒加熱器2中，諸煙氣通道14被定位 成完全地位於輻射燃燒室4之內，且通常從燃燒室底板1 6 處向上延伸至一達7呎或更高之高度。習知之煙氣通道14 必須被建構在燃燒室4之內，且具有一矩形截面之形狀。 -5- 200811402 習知通道1 4之側壁2 0係由耐火磚所建成，且此諸通道1 4 之平坦頂部2 8係由連接於諸側壁2 0上端部之間的楣石或 瓷磚所構成。爲可促進煙氣在燃燒室4內之均勻流動’且 可協助在諸通道Μ中沿其全長獲得一更均勻之煙氣收 集，被設置在諸通道14之垂直側壁20中之諸煙氣孔18在 與諸通道1 4之排放端部26相鄰處.係爲最小，並在大小（亦 即截面面積）上朝向諸通道1 4之相對縱向端部3 0逐漸增 •大。 • 不幸地，直至今日尙在使用中之諸煙氣通道系統具有 若干顯著缺失，且安裝、維護及修理之費用昂貴並耗費時 間。當建構習知加熱器2時，需有多位經驗老到之泥水匠 在燃燒室4內砌起諸垂直通道側壁20。此外，由於位於諸 管列6間的燃燒室4內之極爲有限的空間與機動性，使得 建造程序非常費時且困難。再者，當暴露在燃燒室內之極 端溫度狀況下一段時間時，習知通道1 4之平坦楣石或瓷磚 蓋體28會產生顯著之疲勞且有造成斷裂之傾向。此導致在 ® 諸蓋體28中產生裂痕及孔，其進一步地降低燃燒室4內及 諸通道1 4內之煙氣的流量分佈與均勻性。再者，將諸通道 1 4設於諸管列6間之受限空間內，使得爲可進行燃燒爐 12、管8及加熱器2之其他內部組件的檢查及修理，而在 燃燒室4內搭建鷹架及將材料運入或運出燃燒室4之工作 變得非常困難。 【發明内容】 本發明可滿足各項需求並解決上述之問題。本發明可 -6- 200811402 適用於新的及許多現存之頂部燃燒重組器加熱器中，以及 任何其他類型之燃燒加熱器中，不論是頂部點火型、側邊 點火型、底部點火型，或其他型式者（其均使用一煙氣通 道系統）均可。 在一態樣中’本發明提供一針對一種類型之燃燒加熱 器的改良，而此類型之點火加熱器包括：一具有一內部底 板之輻射燃燒室、複數列位於此燃燒室中之處理管、及至 少一與此諸處理管列中之至少一列相鄰而延伸之煙氣通 ® 道’且此煙氣通道具有複數個用於收納來自輻射燃燒室之 煙氣的入口孔。上述之改良包括：煙氣通道被安裝成可使 煙氣通道之至少大部分側向截面位於內部底板之下方。 ^ 在本發明之另一態樣中，其改良較佳亦包括：（a)煙 ' 氣通道具有一縱向頂蓋，及（b)煙氣通道之諸入口孔被設 置成穿過縱向頂蓋。此外，縱向頂蓋較佳地包括一系列位 在燃燒室之底板中之側向磚砌拱形部，並使得諸入口孔較 佳地係爲若干位於相鄰對之側向磚砌拱形部間之縱向頂蓋 ® 中的的側向延伸間隙。諸側向狹長孔較佳爲以一角度穿過 縱向頂蓋而延伸向煙氣通道之一煙氣出口端部。 在另一態樣中，其改良較佳另包括··煙氣通道具有一 第一縱向端部及一與第一縱向端部相對向之第二縱向端 部；此第二縱向端部係一煙氣通道的排放端部；且此煙氣 通道之側向截面在尺寸上係從第一縱向端部增加至第二縱 向端部。 本發明相對於本技藝中迄今尙被使用之煙氣通道提供 -7- 200811402 了多項之利益及優點。由本發明所提供之利益及優點之例 子包括：消除習知通道在輻射燃燒室內建造垂直的磚砌側 壁之必需性；可在非現場處建造諸煙氣通道，並在運送前 先在其內安裝耐火襯裡；顯著地減少諸煙氣通道之重量； 可增設方便工人及材料通往燃燒室之通道門；減少在燃燒 室內搭建檢查及修理用鷹架所需之時間；大大地增加燃燒 室內之可用工作空間及機動性；顯著地降低結構支撐之要 求與加熱器之成本；及顯著地改良在燃燒室內及諸煙氣通 道內之煙氣流量分佈及均勻性。 本發明之其他態樣、特徵及優點，對於熟習本技藝之 人士而言’在參照附圖並閱讀諸較佳實施例之下列詳細說 明之後立即可明白無誤。 【實施方式】 第3至6圖中顯示一種改良加熱器50，其運用由本發 明所提供之煙氣通道系統。改良加熱器50大致上相同於上 述之習知加熱器2，除了習知加熱器2之煙氣通道14已被 本發明之煙氣通道52所取代之外，而本發明之煙氣通道 52則被安裝在燃燒室56之內部底板54中，並延伸於其下 方。本發明之煙氣通道5 2沿著燃燒室底板5 4而與燃燒室 56中之諸列58之管60相鄰延伸。雖然第3及4圖中所示 之諸管列5 8構成若干由多個垂直管60所組成之水平列， 但可理解的是此諸管列或可爲由多個水平管所組成之垂直 列、可爲由多個水平管所組成之向上傾斜列，或任何其他 被用於本技藝中之管列配置。 -8- 200811402 對照於習知煙氣通道1 4，本發明之諸煙氣通道5 2中之 每一者較佳地包括··一金屬外殼62，其被連接至燃燒室56 之底部’並包含若干向下延伸之側壁64與一底部66 ; 一 層耐火絕緣體68，其被鋪在金屬外殼62之諸側壁與底部 上；一耐火材料製內部覆蓋物（例如耐火塊）70，其被安 裝在此絕緣體層68上方；一縱向頂蓋72，其被安裝在燃 燒器底板5 4中；及複數個入口孔7 4，其可收納來自燃燒 器56之煙氣。結果，本發明之煙氣通道52之至少大部分 側向截面5 5係位於燃燒器5 6之內部底板5 4下方。 諸煙氣入口孔74可爲任何想要之類型或形狀，且可被 設置成穿過此位於燃燒器56中之本發明通道的任何所要 部分。諸孔74較佳地被設置成穿過縱向頂蓋72，且最佳 地係爲諸被設置在頂蓋72中之狹長孔，如第3至6圖中所 示且如下文中所述。 本發明之煙氣通道52的縱向頂蓋72可爲一由楣石、 瓷磚或其他材料所構成之平坦蓋體，而較佳地係成一如第 4至6圖中所示之側面成拱形之蓋體。頂蓋72最佳地將由 \ 一系列呈側向起拱之耐火磚砌拱形部75。 如果頂蓋72之全部面積均敞開以供煙氣流動，則被運 用在本發明煙氣通道52之頂蓋72中的諸狹長孔或其他孔 較佳地具有從大約5%至大約50%之充分大小與數目，且更 佳地係從大約10%至大約35%。頂蓋72中之諸煙氣入口孔 74較佳地係若干成側向延伸之狹長孔。此諸側向延伸狹長 孔74較佳地藉由設置若干間隙而被構成，而此諸間隙係在 -9- 200811402 相鄰對之側向磚砌拱形部75間並沿著縱向頂蓋72之長度 而位於所要之位置處。狹長孔74之寬度較佳地係在大約.1 英寸至大約8英寸（in)之範圍中。狹長孔74之寬度更佳 地係在大約1.5in至大約6in之範圍中，且最佳地係在大約 2in至大約4in之範圍中。此外，諸側向煙氣入口狹長孔74 可垂直延伸穿過縱向頂蓋72,或者以一角度延伸穿過縱向 頂蓋72，並伸向通道52之排放端部76，如下文中將說明 的。 ® 第7至9圖中顯示另一種運用本發明煙氣通道系統之 第二實施例的改良加熱器80。此改良加熱器80係大致上 相同於改良加熱器50，除了每一個運用改良加熱器80之 . 本發明煙氣通道84的截面流動面積在大小上將朝向通道 84之煙氣排放端部86而增加。在截面流動面積上朝向排 放端部86之增加將運·作以便可沿著通道84之長度而提供 一更爲均勻（較佳係相當恆定）之煙氣流動速度。 在本發明之通道84的截面流動面積上之增加將較佳 ^ 地使通道84之截面流動面積在任何指定點處可至少相等 於（更佳爲超過）所有頂部入口孔85及/或其他在通道84 中向上通向該點之諸孔的總面積。在截面流動面積上之增 加將亦較佳地在通道84之第一端部88至通道排放端部86 間保持大致恆定不變之狀態。另外，雖然可使用任何想要 之形狀，但本發明之煙氣通道84將較佳地具有一不變之寬 度，且具有一向下地朝向排放端部8 6而傾斜之底部9 0。 典型地，本發明之煙氣通道84的底部90將以一在從大約 -10- 200811402 2。至大約10°之範圍中的不變角度向下地朝向通道排放端 部86而傾斜。 本發明之通道84的諸側向煙氣入口狹長孔或其他孔 85可垂直延伸（亦即直接向下）穿過縱向頂蓋92，而更佳 地朝向通道排放端部86係成角度。諸煙氣入口狹長孔85 之角度較佳地係在與水平面成大約20°至大約70°之範圍 中。諸煙氣入口狹長孔85之角度更佳地係在與水平面成大 約30°至大約60°之範圍中，且最佳地係與水平.面成大約 鲁 · 45 °。如本技藝中之人士可理解的，被用以形成通道蓋體 92之側向磚砌拱形部94的耐火磚端部可依需要被切割， 以便可提供任何所要之入口狹長孔角度。 對於本發明之上述煙氣通道系統中之任一者，將亦可 被理解的是：（a )通道之截面形狀可部分地成圓形，或可 爲任何其他想要之形狀，（b )諸煙氣入口孔可爲孔（hole)， 或其他任何類型之隙孔（aperture)，（ c)本發明之通道的上 部或可部分地延伸在燃燒室之內部底板上方，（d )如果使 ^ 用除了側向狹長孔外之諸煙氣入口孔，則此諸孔亦可垂直 或以一角度延伸穿過頂蓋，及（e )雖然整·個加熱器較佳地 係使用本發明之通道，但本發明之通道或可組合其他類型 之通道而被使用（例如與一或多個習知通道1 4相組合）。 範例 模擬係藉由利用下列之電腦模式予以進行：（a ) 一頂 部燃燒重組器加熱器，其利用如第1及2圖中所示之習知 煙氣通道系統，及（b ) —頂部燃燒重組器加熱器，其運用 •11- 200811402 如第7至9圖中所示之本發明煙氣通道系統。此諸模擬運 用：一標準之高雷諾數紊流模式；一用於計算熱輻射熱傳 遞之離散縱標（縱座標組S4 )法；及灰氣體加權總數法， 以便可計算出假設在10%過量空氣下之自然氣體燃燒的氣 體吸收係數。篩網係利用Prostar 3.26之高級網篩模組所製 備。諸模擬各使用110萬至180萬間之單元數，並各需超 過60個CPU小時之處理時間。 諸模型模擬煙氣流動、從煙氣至諸加熱器線圈之對流 ® 熱傳遞、及從煙氣與耐火表面至諸線圈之輻射熱傳遞。此 煙氣流動被指定爲每秒6呎，並係在2350°F下位於輻射室 之底板上方25呎處。管金屬溫度被指定爲1 500°F，且諸管 之發射率被指定爲0.85 (此係氧化鋼之典型數値）。諸耐火 . 表面被指定爲絕熱的，並被指定爲具有0.65之發射率。理 想氣體定律被用於確定煙氣密度。 在習知加熱器之模式中，位於燃燒室內之諸煙氣通道 在各側上具有五個孔，其被塑造爲若千穿過諸側壁之矩形 0 切口。諸孔在大小上係從通道之出口端部處朝向此通道之 相對端部處增大。然而，雖然與此通道出口相鄰接之孔係 顯著較小於朝向此通道之相對端部處之孔，但第1 〇圖顯示 經由位於通道出口端部附近之較小孔所收納之煙氣量仍顯 著較大於經由位在較靠近此通道之相對端部或中間處之較 大孔所收納之煙氣量。此顯示了習知系統內之煙氣流動與 其他狀況存在顯著程度之不均勻。 被用於此模擬中之本發明煙氣通道在其頂部中具有兩 -12- 200811402 個與水平面成45。角傾斜之1英寸長入口狹長孔，且其等 中心對中心係相隔20英寸。本發明之通道具有傾斜的底 部，其沿著各通道長度朝向其排放端部提供一大致成恆定 之煙氣速度。各通道包括總計3 1個成角度傾斜之頂孔，並 沿著通道長度提供一顯然更均勻之改良煙氣入口流量分 佈，如第1 1圖所示。 此模擬之結果進一步顯示：相對照於使用習知通道之 加熱器所吸收之58.9 MMBtu/hr，在利用本發明通道之改良 ® 加熱器的各列諸管中則將可吸收60.2 MMBtu/hr。再者，相 對於習知系統之1 740°F煙氣排放溫度，針對本發明系統所 計算出之煙氣排放溫度係1727°F。 ^ 因此，本發明相當適於實現諸項目的並達成上述以及 - 其固有之目標與優勢。雖然已爲揭示之目的而敘述了若干 目前較佳之實施例，但許多變更及修改對熟習本技藝之人 士而言均是顯而可知的。此諸變更及修改均被涵蓋於由申 請專利範圍所界定之本發明精神內。 0 【目式簡單說明】 第1圖係習知重組器加熱器2之部分剖面側視圖。 第2圖係習知重組器加熱器2之內部立體圖。 第3圖係本發明所提供之改良燃燒加熱器實施例5 〇之 部分剖面側視圖，其中利用了 一具有恆定截面流動面積之 煙氣通道實施例52。 第4圖係本發明之燃燒加熱器5 0的內部立體圖。 第5圖係被運用於燃燒火加熱器5 〇中之本發明煙氣通 -13- 200811402 道52之剖面前視圖。 第6圖係本發明煙氣通道52之剖面側視圖。 第7圖係利用本發明煙氣通道實施例84之改良燃燒加 熱器實施例80的部分剖面側視圖。此通道84之截面面積 朝向排放端部8 6而增大，以致可沿著通道84之長度而提 供一更恆定之流動速度。 第8圖係從第7圖中所示之8-8線所觀看到之本發明 煙氣通道84之剖面前視圖。 • 第9圖係本發明煙氣通道84之一片段的剖面側視圖。 第1 0圖係以圖表顯示被運用在習知加熱器2中之煙氣 通道1 4之側壁孔的煙氣入口流量之分佈。 . 第1 1圖係以圖表顯示本發明燃燒加熱器8 0之本發明 , 煙氣通道84之頂孔的煙氣入口流量之分佈。 【主要元件符號說明】 2 加熱器 4 輻射燃燒室 6 列 8 處理管 10 收集歧管系統 12 點火燃燒器 14 煙氣通道 16 底板 18 入口孔 20 側壁 -14- 200811402 22 對流區段 24 煙氣導管 26 排放端部 28 頂部 5 0 加熱器 52 煙氣通道 54 內部底板 55 側向截面 ® 56燃燒室 58 管列 60 管 / 62 金屬外殼 - 64 側壁 66 底部 68 絕緣體 7 0 內部覆蓋物 ® 72縱向頂蓋 7 4 入口孔 75 拱形部 76 排放端部 80 加熱器 84 煙氣通道 85 入口孔 86 排放端部 -15- 200811402 88 第一端部 90 底部 92 蓋體 94 磚砌拱形部200811402 IX. DESCRIPTION OF THE INVENTION: TECHNICAL FIELD OF THE INVENTION The present invention relates to a flame type heater and a flue gas passage conveying pipe system therefor. [Prior Art] Hydrogen recombiner units are commonly used in the petrochemical industry to generate hydrogen from methane and water vapor. A commonly used hydrogen recombination procedure utilizes a heater 2 of a conventional recombiner of the type shown in Figures 1 and 2. The conventional heater 2 comprises: a square or rectangular radiating combustion chamber 4; a plurality of rows 6 of processing tubes 8 extending through the radiating combustion chamber 4 and being filled with a catalyst; a collecting manifold system 10 a process product that receives heat from the lower ends of the process tubes 8; a plurality of columns of down-fired burners 12 that are mounted in the top of the radiant combustion chamber 4 between the tubes 8 of the columns 6; A plurality of flue gas passages 14 are constructed in the combustion chamber 4 and extend along the bottom plate 16 of the combustion chamber 4 between the adjacent pairs of tubes 6 and in the outermost tube rows 6 and 0. 4 between the side walls; a plurality of inlet holes 18, which pass through the vertical side walls 20 of the channels 14 to continuously receive the fumes generated in the combustion chamber 4; an external convection section 22 which is The hot flue gas recovers heat; and a plurality of external flue gas ducts 24 that transport hot flue gas from the longitudinal discharge ends 26 of the flue gas passages 14 to the convection section 22. In the conventional top combustion heater 2, the flue gas passages 14 are positioned completely within the radiant combustion chamber 4 and generally extend upwardly from the combustion chamber floor 16 to a height of 7 Torr or higher. The conventional flue gas passage 14 must be constructed within the combustion chamber 4 and have a rectangular cross-sectional shape. -5- 200811402 The side wall 20 of the conventional channel 14 is constructed of refractory bricks, and the flat tops 28 of the channels 14 are composed of vermiculite or ceramic tiles connected between the upper ends of the side walls 20 . In order to promote uniform flow of flue gas within the combustion chamber 4 and to assist in obtaining a more uniform flue gas collection along the entire length of the passages, the flue holes 18 are provided in the vertical side walls 20 of the passages 14. Adjacent to the discharge end 26 of the passages 14 is minimal and increases in size (i.e., cross-sectional area) toward the opposite longitudinal ends 30 of the passages 14. • Unfortunately, there are several significant deficiencies in the flue gas path systems that are in use today, and installation, maintenance and repair are expensive and time consuming. When constructing the conventional heater 2, a plurality of experienced plasterers are required to build the vertical passage side walls 20 in the combustion chamber 4. Moreover, the construction process is very time consuming and difficult due to the extremely limited space and maneuverability within the combustion chamber 4 between the rows of tubes 6. Moreover, the flat vermiculite or tile cover 28 of the conventional channel 14 will experience significant fatigue and a tendency to break when exposed to extreme temperatures in the combustion chamber for a period of time. This results in cracks and holes in the cover 28 which further reduce the flow distribution and uniformity of the fumes within the combustion chamber 4 and within the passages 14. Furthermore, the channels 14 are disposed in the confined spaces between the rows of tubes 6 so that inspection and repair of the internal components of the furnace 12, the tubes 8 and the heater 2 can be performed, and in the combustion chamber 4 It is very difficult to build a scaffold and transport materials into or out of the combustion chamber 4. SUMMARY OF THE INVENTION The present invention satisfies various needs and solves the above problems. The invention is applicable to new and many existing top combustion recombiner heaters, as well as any other type of combustion heater, whether it is a top ignition type, a side ignition type, a bottom ignition type, or the like. Types (all of which use a flue gas channel system) are available. In one aspect, the present invention provides an improvement to a type of combustion heater comprising: a radiant combustion chamber having an internal bottom plate, a plurality of processing tubes located in the combustion chamber, And at least one of the flue gas passages extending adjacent to at least one of the plurality of process tubes and having a plurality of inlet passages for receiving flue gas from the radiant combustion chamber. The above improvements include that the flue gas passage is mounted such that at least a majority of the lateral cross section of the flue gas passage is below the inner bottom plate. In another aspect of the invention, the improvement preferably further comprises: (a) the smoke passage has a longitudinal cap, and (b) the inlet passages of the flue gas passage are disposed through the longitudinal cap . In addition, the longitudinal cap preferably includes a series of lateral brick arches located in the floor of the combustion chamber, and such that the inlet apertures are preferably formed in a plurality of laterally facing brick arches adjacent to each other. The lateral extension gap in the longitudinal top cover®. Preferably, the laterally elongated apertures extend through the longitudinal cap at an angle to one of the flue gas outlet ends of the flue gas passage. In another aspect, the improvement preferably further includes: the flue gas passage has a first longitudinal end portion and a second longitudinal end portion opposite to the first longitudinal end portion; the second longitudinal end portion is a a discharge end of the flue gas passage; and a lateral cross section of the flue gas passage is sized to increase from the first longitudinal end to the second longitudinal end. The present invention provides a number of benefits and advantages over the flue gas passages of the prior art that have been used -7-200811402. Examples of benefits and advantages provided by the present invention include the need to eliminate the need for conventional passageways to construct vertical brickwork sidewalls in a radiant combustion chamber; the flue gas passages can be constructed offsite and installed therein prior to shipment. Refractory lining; significantly reduces the weight of the flue gas passages; can add access doors for workers and materials to the combustion chamber; reduce the time required to set up inspection and repair of the scaffold in the combustion chamber; greatly increase the available in the combustion chamber Work space and maneuverability; significantly reduce structural support requirements and heater costs; and significantly improve smoke flow distribution and uniformity in the combustion chamber and in the flue gas channels. Other aspects, features and advantages of the present invention will become apparent to those skilled in the art in the <RTIgt; [Embodiment] Figs. 3 to 6 show an improved heater 50 which utilizes the flue gas passage system provided by the present invention. The modified heater 50 is substantially identical to the conventional heater 2 described above, except that the flue gas passage 14 of the conventional heater 2 has been replaced by the flue gas passage 52 of the present invention, and the flue gas passage 52 of the present invention is It is mounted in the inner bottom plate 54 of the combustion chamber 56 and extends below it. The flue gas passages 52 of the present invention extend adjacent the tubes 60 of the columns 58 in the combustion chamber 56 along the bottom plate 54 of the combustion chamber. Although the rows of tubes 58 shown in Figures 3 and 4 constitute a plurality of horizontal columns of a plurality of vertical tubes 60, it will be understood that the tubes may be vertical from a plurality of horizontal tubes. The column, which may be an upwardly sloping column of a plurality of horizontal tubes, or any other tube configuration used in the art. -8- 200811402 Each of the flue gas passages 5 2 of the present invention preferably includes a metal casing 62 connected to the bottom of the combustion chamber 56, in contrast to the conventional flue gas passages 14 A plurality of downwardly extending side walls 64 and a bottom portion 66 are included; a refractory insulator 68 is laid over the side walls and bottom of the metal outer casing 62; a refractory interior covering (e.g., refractory block) 70 is mounted Above the insulator layer 68; a longitudinal cap 72 that is mounted in the burner floor 54; and a plurality of inlet ports 74 that receive the fumes from the burner 56. As a result, at least a majority of the lateral section 5 of the flue gas passage 52 of the present invention is located below the inner bottom plate 54 of the burner 56. The flue gas inlet apertures 74 can be of any desired type or shape and can be disposed to pass through any desired portion of the passage of the present invention located in the burner 56. The apertures 74 are preferably disposed through the longitudinal cap 72 and are preferably elongated apertures disposed in the top cover 72, as shown in Figures 3 through 6 and as described below. The longitudinal cap 72 of the flue gas passage 52 of the present invention may be a flat cover made of vermiculite, tile or other material, and is preferably arched as shown in Figures 4-6. The cover. The top cover 72 will optimally be a series of refractory brick arches 75 that are laterally arched. If the entire area of the top cover 72 is open for flue gas flow, the elongated holes or other holes used in the top cover 72 of the smoke passage 52 of the present invention preferably have from about 5% to about 50%. Sufficient in size and number, and more preferably from about 10% to about 35%. The flue gas inlet apertures 74 in the top cover 72 are preferably formed as a plurality of elongated apertures extending laterally. The laterally extending elongated apertures 74 are preferably constructed by providing a plurality of gaps between the adjacent pairs of lateral brick arches 75 of the -9-200811402 and along the longitudinal top cover 72. The length is at the desired position. The width of the elongated holes 74 is preferably in the range of about .1 inch to about 8 inches (in). The width of the elongated holes 74 is preferably in the range of from about 1.5 inches to about 6 inches, and most preferably in the range of from about 2 inches to about 4 inches. In addition, the lateral flue gas inlet slits 74 may extend vertically through the longitudinal cap 72 or at an angle through the longitudinal cap 72 and toward the discharge end 76 of the passage 52, as will be described below. ® Figures 7 through 9 show another modified heater 80 using a second embodiment of the flue gas channel system of the present invention. The modified heater 80 is substantially identical to the modified heater 50 except that each of the modified heaters 80 is utilized. The cross-sectional flow area of the inventive flue gas passage 84 will be sized toward the flue gas discharge end 86 of the passage 84. increase. The increase in the cross-sectional flow area toward the discharge end 86 will operate to provide a more uniform (preferably relatively constant) flue gas flow rate along the length of the passage 84. An increase in the cross-sectional flow area of the passage 84 of the present invention will preferably provide the cross-sectional flow area of the passage 84 at least at any given point at least equal to (more preferably exceeding) all of the top inlet apertures 85 and/or other The total area of the holes in channel 84 that open up to that point. The increase in cross-sectional flow area will also preferably remain substantially constant between the first end 88 of the passage 84 and the passage discharge end 86. Additionally, although any desired shape can be used, the flue gas passage 84 of the present invention will preferably have a constant width and have a bottom 90 that slopes downwardly toward the discharge end 86. Typically, the bottom 90 of the flue gas passage 84 of the present invention will be at a level of from about -10- 2008 11402 2 . The constant angle in the range of up to about 10° is inclined downward toward the channel discharge end 86. The lateral flue gas inlet slots or other apertures 85 of the channel 84 of the present invention may extend vertically (i.e., directly downward) through the longitudinal cap 92 and more preferably at an angle toward the channel discharge end 86. The angle of the flue gas inlet slits 85 is preferably in the range of from about 20 to about 70 with respect to the horizontal. The angle of the inlet openings 85 of the flue gas inlets is preferably in the range of from about 30° to about 60° from the horizontal plane, and is preferably about 45° to the level. As will be appreciated by those skilled in the art, the ends of the refractory bricks used to form the lateral brick arches 94 of the channel cover 92 can be cut as desired to provide any desired entrance aperture angle. For any of the above described flue gas channel systems of the present invention, it will also be understood that: (a) the cross-sectional shape of the channel may be partially circular, or may be any other desired shape, (b) The flue gas inlet apertures may be holes, or any other type of aperture, (c) the upper portion of the passage of the invention may extend partially over the inner bottom of the combustion chamber, (d) if ^ using the flue gas inlet holes other than the laterally elongated holes, the holes may also extend vertically or at an angle through the top cover, and (e) although the entire heater preferably uses the present invention Channels, but the channels of the present invention may be used in combination with other types of channels (e.g., in combination with one or more conventional channels 14). The example simulation was performed by using the following computer modes: (a) a top combustion recombiner heater utilizing a conventional flue gas channel system as shown in Figures 1 and 2, and (b) - top combustion Recombiner heater, which utilizes the inventive flue gas channel system as shown in Figures 7 through 9-11. The simulations are used: a standard high Reynolds number turbulence mode; a discrete ordinate (thermal coordinate group S4) method for calculating thermal radiant heat transfer; and a gray gas weighted total method so that the hypothesis can be calculated at 10% excess The gas absorption coefficient of natural gas combustion under air. The screen is made using Prostar 3.26's advanced mesh screen module. Each of the simulations uses between 1.1 million and 1.8 million units, and each requires more than 60 CPU hours of processing time. The models simulate flue gas flow, convection from flue gas to heater coils ® heat transfer, and radiant heat transfer from flue gas and refractory surfaces to coils. This flue gas flow is specified to be 6 Torr per second and is located at 2350 °F at 25 上方 above the floor of the radiant chamber. The tube metal temperature was specified to be 1 500 °F, and the emissivity of the tubes was specified to be 0.85 (the typical number of such oxidized steels). Refractory. The surface was designated as adiabatic and was designated to have an emissivity of 0.65. The ideal gas law is used to determine the smoke density. In the conventional heater mode, the flue gas passages located in the combustion chamber have five holes on each side that are shaped as a rectangular 0 slit through the side walls. The apertures increase in size from the exit end of the passage toward the opposite end of the passage. However, although the apertures adjacent the exit of the channel are significantly smaller than the apertures at the opposite ends of the channel, the first figure shows the smoke contained in the smaller aperture near the end of the exit of the channel. The amount is still significantly greater than the amount of flue gas contained through the larger holes located closer to the opposite ends or intermediate portions of the channel. This shows a significant degree of unevenness in the flow of smoke within the conventional system and other conditions. The flue gas passage of the present invention used in this simulation has two -12-200811402 in its top portion at 45 with the horizontal plane. The 1 inch long inlet slit is angled and its center is 20 inches from the center. The passage of the present invention has a sloped bottom that provides a substantially constant flue gas velocity along its length toward its discharge end. Each channel includes a total of 31 top-angled top holes and provides an apparently more uniform improved flue gas inlet flow distribution along the length of the channel, as shown in Figure 11. The results of this simulation further show that 68.2 MMBtu/hr can be absorbed in each of the tubes of the modified heater using the channel of the present invention, compared to 58.9 MMBtu/hr absorbed by a heater using a conventional channel. Furthermore, the smoke emission temperature calculated for the system of the present invention is 1727 °F relative to the 1740 °F flue gas discharge temperature of the conventional system. Thus, the present invention is quite suitable for implementing the items and achieving the above and - inherent goals and advantages. Although a number of presently preferred embodiments have been described for purposes of illustration, many variations and modifications are apparent to those skilled in the art. Such changes and modifications are encompassed within the spirit of the invention as defined by the scope of the claims. 0 [Brief Description] Fig. 1 is a partial cross-sectional side view of a conventional recombiner heater 2. Figure 2 is an internal perspective view of a conventional recombiner heater 2. Figure 3 is a partial cross-sectional side view of an improved combustion heater embodiment 5 of the present invention utilizing a flue gas passage embodiment 52 having a constant cross-sectional flow area. Fig. 4 is an internal perspective view of the combustion heater 50 of the present invention. Figure 5 is a cross-sectional front view of the flue gas passage -13- 200811402, 52, of the present invention applied to a combustion fire heater. Figure 6 is a cross-sectional side view of the flue gas passage 52 of the present invention. Figure 7 is a partial cross-sectional side view of an embodiment 80 of a modified combustion heater utilizing the flue gas passage embodiment 84 of the present invention. The cross-sectional area of this passage 84 increases toward the discharge end 86 so that a more constant flow velocity can be provided along the length of the passage 84. Figure 8 is a cross-sectional front view of the flue gas passage 84 of the present invention as seen from line 8-8 shown in Figure 7. • Figure 9 is a cross-sectional side view of a fragment of one of the flue gas channels 84 of the present invention. Fig. 10 is a graph showing the distribution of the flue gas inlet flow rate of the side wall holes of the flue gas passages 14 used in the conventional heater 2. Fig. 1 is a graph showing the distribution of the flue gas inlet flow rate of the top hole of the flue gas passage 84 of the present invention. [Main component symbol description] 2 Heater 4 Radiating combustion chamber 6 Column 8 Processing tube 10 Collecting manifold system 12 Ignition burner 14 Flue gas passage 16 Base plate 18 Inlet hole 20 Side wall-14- 200811402 22 Convection section 24 Flue gas duct 26 Discharge end 28 Top 5 0 Heater 52 Flue gas passage 54 Internal bottom plate 55 Lateral section ® 56 Combustion chamber 58 Tube row 60 Tube / 62 Metal enclosure - 64 Side wall 66 Bottom 68 Insulator 7 0 Inner cover ® 72 longitudinal top Cover 7 4 inlet hole 75 arch 76 discharge end 80 heater 84 flue gas passage 85 inlet hole 86 discharge end -15- 200811402 88 first end 90 bottom 92 cover 94 brick arch
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