在海上生產(chǎn)平臺(tái)上使用滾動(dòng)壓縮技術(shù)回收儲(chǔ)存罐內(nèi)閃發(fā)氣體[中文3850字] 【中英文WORD】
在海上生產(chǎn)平臺(tái)上使用滾動(dòng)壓縮技術(shù)回收儲(chǔ)存罐內(nèi)閃發(fā)氣體[中文3850字] 【中英文WORD】,中文3850字,中英文WORD,在海上生產(chǎn)平臺(tái)上使用滾動(dòng)壓縮技術(shù)回收儲(chǔ)存罐內(nèi)閃發(fā)氣體[中文3850字],【中英文WORD】,海上,生產(chǎn),平臺(tái),使用,滾動(dòng),壓縮,技術(shù),回收,儲(chǔ)存,罐內(nèi)閃發(fā),氣體,中文,3850
[中文3850字].
在海上生產(chǎn)平臺(tái)上使用滾動(dòng)壓縮技術(shù)回收儲(chǔ)存罐內(nèi)閃發(fā)氣體
G.B.（比爾）施耐德，SPE, 布萊恩E. 博耶，SPE，馬克A.古德伊爾，商科工程
摘要
位于墨西哥灣外大陸架的一個(gè)獨(dú)立的石油天然氣生產(chǎn)操作遭到颶風(fēng)艾克的襲擊并損壞了一些設(shè)施。作為重建的一部分，其中一個(gè)海上平臺(tái)被翻新了。翻新包括濃縮產(chǎn)品系列控制來(lái)自附近生產(chǎn)平臺(tái)的額外油氣產(chǎn)品。平臺(tái)的額外產(chǎn)品需要一個(gè)蒸發(fā)回收系統(tǒng)來(lái)回收設(shè)備的閃蒸汽。項(xiàng)目小組選擇渦旋壓縮機(jī)蒸發(fā)回收裝置（VRU）來(lái)回收和重新壓縮閃蒸汽。該項(xiàng)目是在近海環(huán)境渦旋壓縮蒸汽回收技術(shù)的首次應(yīng)用。
生產(chǎn)者為了使設(shè)施能夠回收石油儲(chǔ)存罐中的閃發(fā)蒸汽和裝置中的過(guò)剩的未使用的閃發(fā)蒸汽而安裝了蒸汽回收裝置。在項(xiàng)目的初始階段回收的平均量是大約每天58,000標(biāo)準(zhǔn)立方英尺天然氣?；厥盏奶烊粴庵屑淄楹空伎傤~的69%。每天甲烷的回收量估計(jì)為0.84噸，溫室氣體回收量估計(jì)為17.6噸二氧化碳。揮發(fā)性有機(jī)化合物（VOC）每天回收量為1.0噸。渦旋壓縮機(jī)蒸汽回收裝置滿足了美國(guó)礦產(chǎn)管理局的放空燃燒和法規(guī)的監(jiān)督要求。該項(xiàng)目預(yù)計(jì)時(shí)間為15個(gè)月（基本支出）。
該項(xiàng)目的重要意義有：1、首次在離岸申請(qǐng)中使用渦旋壓縮技術(shù)。
2、裝置占地面積小對(duì)于近海有限操作空間的重要性。
3、渦旋技術(shù)比典型的機(jī)械壓縮機(jī)所需的維修少。
4、低成本和低消耗加快經(jīng)濟(jì)恢復(fù)。
5、回收的閃發(fā)蒸汽含有揮發(fā)性有機(jī)化合物（VOCs）和甲烷以及溫室氣體。
引言
在墨西哥灣外大陸架上的許多石油天然氣生產(chǎn)平臺(tái)和管道遭到2008年11月颶風(fēng)艾克的破壞。在墨西哥灣當(dāng)?shù)氐囊粋€(gè)主要的獨(dú)立石油天然氣生產(chǎn)商有一些設(shè)施被暴風(fēng)雨毀壞。作為重建的一部分，其中一個(gè)近海平臺(tái)被翻新。平臺(tái)的翻新包括濃縮和改進(jìn)產(chǎn)品系列控制來(lái)自附近生產(chǎn)平臺(tái)的額外油氣產(chǎn)品，由于颶風(fēng)艾克的影響附近的生產(chǎn)平臺(tái)不能輸送其產(chǎn)品到集合管道中。平臺(tái)的額外產(chǎn)品需要一個(gè)蒸發(fā)回收系統(tǒng)來(lái)回收儲(chǔ)存罐中的閃蒸汽。生產(chǎn)商的工程小組決定利用渦旋壓縮機(jī)來(lái)回收和重新壓縮來(lái)自儲(chǔ)存罐和石油設(shè)備中的閃發(fā)蒸汽。
石油儲(chǔ)存罐中的天然氣蒸汽資源包含閃發(fā)損失、工作損失和呼吸損失。對(duì)于壓力容器（如分離器、加熱器）或油罐當(dāng)原油或凝析油中溶解氣從高壓向低壓移動(dòng)時(shí)發(fā)生閃發(fā)。隨著油壓的下降油中未溶解的輕組分被釋放或“一閃而過(guò)”。工作損失歸因于儲(chǔ)存罐壓縮空間內(nèi)的天然氣壓縮量作為一個(gè)罐已經(jīng)滿了。呼吸損失歸因于每天儲(chǔ)存罐壓縮空間內(nèi)的天然氣壓縮量隨著罐內(nèi)溫度和壓力變化而改變。對(duì)于本文，我們將油罐的排出氣體統(tǒng)稱為閃蒸汽。
通常情況下，來(lái)自近海生產(chǎn)平臺(tái)的閃發(fā)蒸汽要么直接排放到大氣中要么燒毀。歷史上蒸發(fā)回收裝置被用于當(dāng)投資量大并且要滿足排放標(biāo)準(zhǔn)的情況下回收閃發(fā)蒸汽。用于排出閃發(fā)蒸汽的典型蒸發(fā)回收壓縮機(jī)是天然氣驅(qū)動(dòng)的螺桿壓縮機(jī)和旋轉(zhuǎn)葉壓氣機(jī)。
美國(guó)礦產(chǎn)管理局（MMS）是擁有在墨西哥灣中部和西部地區(qū)天然氣放空管轄權(quán)的管理機(jī)構(gòu)。美國(guó)礦產(chǎn)管理局規(guī)定需要一個(gè)設(shè)施每天回收天然氣量大于50,000標(biāo)準(zhǔn)立方英尺，而不是直接排放到大氣中或者焚燒。對(duì)于近海生產(chǎn)平臺(tái)，甲板空間需求是蒸發(fā)回收裝置的重要考慮因素。為了適應(yīng)這一限制條件，渦動(dòng)壓縮機(jī)機(jī)組的占地面積是傳統(tǒng)蒸發(fā)回收裝置的三分之一。另外，降低總體維修成本是決定使用渦旋壓縮機(jī)技術(shù)的一個(gè)重要因素。相對(duì)于典型機(jī)械壓縮機(jī)每季度換油，渦旋壓縮機(jī)只需要每年更換一次。在近海環(huán)境使用的機(jī)器要求資金提高到典型的陸上壓縮機(jī)組程度，原因是海水腐蝕環(huán)境和近海操作的額外安全控制的要求。對(duì)于這個(gè)項(xiàng)目陸上蒸發(fā)回收裝置的標(biāo)準(zhǔn)已經(jīng)達(dá)到近海條件和管理的規(guī)格。
設(shè)備和流程的描述和應(yīng)用
渦旋壓縮技術(shù)
渦旋壓縮機(jī)是一種容積式機(jī)器，使用兩個(gè)交錯(cuò)的螺旋形渦旋盤來(lái)壓縮天然氣。渦旋壓縮技術(shù)中，一個(gè)渦旋盤是固定的，另一個(gè)做離心運(yùn)動(dòng)，從而在連續(xù)的小滾動(dòng)空間“泡”間抽動(dòng)壓縮氣體，直到在中心處達(dá)到最大壓力值。在中心處，氣體被釋放到固定渦旋盤上的一個(gè)排放點(diǎn)。壓縮在滾動(dòng)軌道上是連續(xù)的，大量氣泡被同時(shí)壓縮。
壓縮機(jī)的驅(qū)動(dòng)裝置是電動(dòng)馬達(dá)。渦旋壓縮機(jī)是一種設(shè)計(jì)使用高壓制冷劑的密閉壓縮機(jī)。它有一個(gè)寬松的運(yùn)行范圍并且本質(zhì)上是無(wú)泄漏的。渦旋壓縮機(jī)技術(shù)已被廣泛用于制冷系統(tǒng)。
渦旋壓縮機(jī)蒸發(fā)回收裝置采用了臥式設(shè)計(jì)，并且滴糙度、低噪音、低振動(dòng)，使用變速控制電機(jī)。根據(jù)不同情況蒸發(fā)回收裝置的進(jìn)氣壓力范圍為-10.4-101.3磅每平方英寸，排氣壓力范圍為43.5-363磅每平方英寸。壓縮比為3-15。
自2004年渦旋壓縮技術(shù)就被用于石油天然氣蒸發(fā)回收應(yīng)用中。
渦旋技術(shù)的應(yīng)用
在2009年5月，聯(lián)邦和生產(chǎn)商開(kāi)始聯(lián)合共同修改一個(gè)典型陸上渦旋壓縮機(jī)蒸發(fā)回收裝置，這個(gè)裝置用于被毀壞翻新的生產(chǎn)平臺(tái)上。
這個(gè)渦旋壓縮機(jī)蒸發(fā)回收裝置包含兩個(gè)堆疊的模塊，每個(gè)模塊是8英尺長(zhǎng)4英尺寬4英尺高的剛撬，每個(gè)剛撬含有一個(gè)進(jìn)氣洗滌器。每個(gè)模塊包含兩個(gè)15馬力的渦旋壓縮機(jī)和冷卻器。每個(gè)模塊還包含一個(gè)可編程邏輯控制（PLC）和變頻驅(qū)動(dòng)器（VFD）的控制面板。這個(gè)雙模塊機(jī)組的設(shè)計(jì)回收能力是每天200,000標(biāo)準(zhǔn)立方英尺。
一條連接油罐通用出口和石油處理機(jī)（例如加熱處理器）出口的進(jìn)氣管線被安裝在渦旋壓縮機(jī)蒸發(fā)回收裝置的進(jìn)氣洗滌器上。連接石油處理機(jī)的進(jìn)氣管線用來(lái)收集處理機(jī)內(nèi)的額外天然氣，這些天然氣是在平臺(tái)上未使用的燃料天然氣。在渦旋壓縮機(jī)蒸發(fā)回收裝置前端的進(jìn)氣管線上安裝了一個(gè)流量計(jì)，用來(lái)計(jì)量被回收的天然氣量。渦旋壓縮機(jī)組的排放被輸送到現(xiàn)場(chǎng)主壓縮機(jī)的進(jìn)氣分離器/洗滌器中。這個(gè)主壓縮機(jī)壓縮的天然氣最終輸送到銷售管線中。
當(dāng)儲(chǔ)存罐內(nèi)閃發(fā)蒸汽壓力較低時(shí)，在渦旋壓縮機(jī)蒸發(fā)回收裝置安裝一個(gè)洗氣系統(tǒng)用來(lái)回收氣體。該洗氣系統(tǒng)的作用是保持蒸發(fā)回收裝置的運(yùn)行能夠維持渦旋壓縮機(jī)的油溫在最低值華氏235度。當(dāng)保持油溫等于或高于華氏235度時(shí)，閃發(fā)蒸汽能夠維持氣相狀態(tài)。
為安全起見(jiàn)，在油罐上安裝填充氣系統(tǒng)來(lái)維持罐上每平方英寸約有0.5盎司壓力，從而阻止氧氣進(jìn)入罐內(nèi)。、
圖1是一個(gè)包含蒸發(fā)回收裝置的簡(jiǎn)化流程。
變頻驅(qū)動(dòng)器的控制面板安裝在馬達(dá)控制中心（MCC）里，其線路系統(tǒng)也接到位于生產(chǎn)平臺(tái)下層的渦旋壓縮機(jī)蒸發(fā)回收裝置中。
在功能上，渦旋壓縮機(jī)在回收模式正常運(yùn)行時(shí)能達(dá)到每分鐘2400轉(zhuǎn)（rpm）。當(dāng)罐內(nèi)產(chǎn)生壓力時(shí)，壓力變送器會(huì)發(fā)出信號(hào)使壓縮機(jī)的轉(zhuǎn)速提高到4800rpms，同時(shí)閃發(fā)蒸汽也被回收并壓縮。一旦罐內(nèi)的閃發(fā)蒸汽被回收并且罐內(nèi)壓力下降，那么變頻驅(qū)動(dòng)器使壓縮機(jī)轉(zhuǎn)速降到2400rpms。然后蒸發(fā)回收裝置重新回到回收模式。
氣體洗滌器回收的任何氣體都被用泵輸送回儲(chǔ)油罐。
蒸發(fā)回收裝置機(jī)組的改進(jìn)
為了滿足近海要求，渦旋壓縮機(jī)組的結(jié)構(gòu)部分已經(jīng)經(jīng)過(guò)熱鍍鋅處理并適合近海安裝，但是其他組件需要修補(bǔ)以抵抗海水的腐蝕環(huán)境。壓縮機(jī)和一些其他組件已從模塊中移除，特別添加了一個(gè)三層環(huán)氧樹脂涂料的圖層來(lái)抵抗腐蝕環(huán)境。
除了近海環(huán)境所需的特種涂料外，還有大量的安全系統(tǒng)需要修改以使渦旋壓縮機(jī)蒸發(fā)回收裝置遵從美國(guó)礦產(chǎn)管理局（MMS）的規(guī)定。近海經(jīng)營(yíng)商需要遵守美國(guó)石油學(xué)會(huì)（API）建議措施14C（RP14C）。美國(guó)石油學(xué)會(huì)建議措施14C包括近海平臺(tái)安全系統(tǒng)的設(shè)計(jì)，安裝和測(cè)試標(biāo)準(zhǔn)。它確定了每個(gè)不良事件可能影響一個(gè)流程的要素，并討論了每種要素類型的安全裝置選擇標(biāo)準(zhǔn)。如果不能符合建議措施14C的要求會(huì)導(dǎo)致對(duì)生產(chǎn)商罰款，在其他情況下，需要中斷生產(chǎn)直到遵守規(guī)定，這可能導(dǎo)致生產(chǎn)商的收入損失。
具體來(lái)說(shuō)，應(yīng)對(duì)建議措施14C的修改有：
1、為氣體洗滌器的高液位報(bào)警/關(guān)機(jī)月檢安裝測(cè)試線路。
2、為壓縮機(jī)排氣線的高排氣壓力報(bào)警/關(guān)機(jī)月檢安裝測(cè)試線路。
3、為儲(chǔ)油罐的低壓報(bào)警/關(guān)機(jī)月檢安裝測(cè)試線路。
4、添加冗余的油罐壓力變送器。為油罐的高壓報(bào)警/關(guān)機(jī)月檢安裝測(cè)試線路。
此外，生產(chǎn)商的近海規(guī)格要求一些閥門更換到鋼結(jié)構(gòu)，而不是黃銅。
2009年7月渦旋壓縮機(jī)蒸發(fā)回收裝置被運(yùn)到操作平臺(tái)上。2009年8月渦旋壓縮機(jī)蒸發(fā)回收裝置的互聯(lián)管道已經(jīng)完工。一旦安裝完成并且平臺(tái)投入運(yùn)行，渦旋壓縮機(jī)蒸發(fā)回收裝置也就投入運(yùn)行了。
數(shù)據(jù)和結(jié)果的介紹
投入的美元值：
標(biāo)準(zhǔn)雙蒸發(fā)回收裝置機(jī)組費(fèi) 135,000
海水環(huán)境修改費(fèi) 15,000
美國(guó)礦產(chǎn)管理局的相應(yīng)修改費(fèi) 5,000
安裝費(fèi) 40,000
啟動(dòng)/調(diào)試費(fèi) 6,000
總投入 201,000
這樣安裝之后，渦旋壓縮機(jī)蒸發(fā)回收裝置平均回收的罐內(nèi)閃發(fā)蒸汽量高于初試運(yùn)營(yíng)期的每天58,000標(biāo)準(zhǔn)立方英尺?；厥盏姆逯盗髁坑涗洖槊刻?15,000標(biāo)準(zhǔn)立方英尺。
用于化學(xué)分析的回收氣體樣本的分子量是26.6，其中甲烷體積大約占69%。揮發(fā)性有機(jī)化合物（非甲烷烴，非烷烴碳?xì)浠衔铮w積大約占29%。較高的加熱數(shù)值大約是每標(biāo)準(zhǔn)立方英尺1540英熱單位（BTU）。閃發(fā)蒸汽中的硫化氫氣體量被認(rèn)為是基于設(shè)備加工新天然氣的最小含量。
以平均回收量和天然氣價(jià)格每英熱單位5美元為標(biāo)準(zhǔn)計(jì)算的渦旋壓縮機(jī)蒸發(fā)回收裝置基本支出為15個(gè)月。
甲烷排放量估計(jì)回收值為每天0.84美噸，溫室氣體二氧化碳的估計(jì)回收值為每天17.6美噸。揮發(fā)性有機(jī)化合物（VOC）的排放量回收值為每天1.0美噸。
生產(chǎn)商目前正在修改渦旋壓縮機(jī)蒸發(fā)回收裝置的控制系統(tǒng)。這些修改包括安裝一個(gè)單一的可編程邏輯控制器（PLC）來(lái)控制兩個(gè)模塊，更換變送器的壓力開(kāi)關(guān)，以及在蒸發(fā)回收裝置旁邊安裝一個(gè)觸屏的控制面板。這些修改需要符合生產(chǎn)商運(yùn)營(yíng)標(biāo)準(zhǔn)。這些修改的費(fèi)用將導(dǎo)致額外增加8000美元的初始成本。
結(jié)論
渦旋壓縮技術(shù)應(yīng)用于惡劣的海上環(huán)境是一種具有成本效益、最有效的油氣回收解決方案。通過(guò)應(yīng)用渦旋壓縮技術(shù)回收蒸汽，近海生產(chǎn)商能夠滿足監(jiān)管要求，以減少?gòu)U氣排放，提高他們的碳足跡，并能經(jīng)濟(jì)地回收閃發(fā)蒸汽。
致謝
我們衷心感謝威爾士詹姆斯先生和達(dá)姆倫羅恩先生，因?yàn)橛兴麄兊膶I(yè)知識(shí)和辛勤的工作才能取得這個(gè)項(xiàng)目的成功。
參考文獻(xiàn)
1、艾默生環(huán)境優(yōu)化技術(shù)。2008年4月。全封閉渦旋壓縮機(jī)在高溫壓縮氣體中的應(yīng)用
http://www.emersonclimate.com/oil_gas/PDF/HermeticScrollCompressorWhitePaper.pdf.
2、建議措施14C關(guān)于海上生產(chǎn)平臺(tái)基礎(chǔ)表面安全系統(tǒng)的分析、設(shè)計(jì)、安裝和測(cè)試，第六版。1998年3月，華盛頓：美國(guó)石油學(xué)會(huì)。
原文
Recover flash gas in storage tanks on offshore platforms by useing Rolling compression technology
Abstract
A major independent oil and gas producer (Producer) with operations located on the Outer Continental Shelf of the Gulf of Mexico had several facilities damaged by Hurricane Ike. As a part of restoring operations, one of the offshore platforms was refurbished.The refurbishment included upgrading the production train to handle additional oil and gas production from other nearby production platforms. The additional production to the platform required a vapor recovery system to recover facility flash gas.The project team chose the scroll compressor vapor recovery unit (VRU) to recover and recompress the flash gas. The project was the first application of scroll compression technology for vapor recovery in an offshore environment.
The Producer installed the VRU allowing the facility to recover flash gas from the oil storage tanks and excess unused flash gas from the oil treater. The average volume recovered was approximately 58,000 standard cubic feet of natural gas per day during the initial phase of the project. The methane content of the recovered natural gas was approximately 69 percent by volume. The estimated methane recovered was 0.84 US tons per day and the estimated recovery of greenhouse gases were 17.6 US tons per day CO2e. Volatile organic compounds (VOC) recovered were 1.0 US tons per day. The scroll compressor VRU met the regulatory requirements of the U.S. Minerals Management Service’s flaring and venting regulations. The projected payout was 15 months(simple payout).
The significance of this project includes:
1. First use of scroll compression technology in an offshore application
2. Small physical footprint of unit important to offshore operations with limited space
3. Scroll technology requires less maintenance than typical mechanical compressors
4. Lower initial costs and lower operating costs enhance economics of recovery
5. Recovered flash gas that contained volatile organic compounds (VOCs) and methane, a greenhouse gas
Introduction
Many oil and gas production platforms and pipelines operating in the Outer Continental Shelf of the Gulf of Mexico were damaged by Hurricane Ike in November of 2008. A major independent oil and gas producer (Producer) with operations located on the Gulf of Mexico had several facilities damaged by the storm. As a part of restoring operations, one the offshore platforms was refurbished. The refurbishment of the platform included upgrading and improving the production train to handle additional production from other nearby production platforms that could not send their production to the gathering pipelines due to the effects of Hurricane Ike. The additional production to the platform required the installation of a VRU to recover flash gas from the oil storage tanks. The Producer’s project team decided to utilize scroll compressors to recover and recompress the flash gas from the storage tanks and oil treater.
The source of natural gas vapors from oil storage tanks include flashing losses, working losses and breathing losses. Flashing for a pressure vessel (e.g., separator, heater treater) or oil storage tank occurs when the crude oil or condensate with dissolved gases moves from a higher pressure to a lower pressure. As the pressure of the oil drops some of the lighter components dissolved in the oil are released or “flashed.” Working losses are due to displacement of the natural gas vapors within the storage tank vapor space as a tank is filled. Breathing losses are due to displacement of natural gas vapor within the storage tank vapor space due to changes in the tank temperature and pressure throughout the day. For this paper we refer to the vent gas from the oil storage tanks collectively as flash gas.
Often flash gases from offshore production platforms are either vented directly to the atmosphere or burned by a flare. Historically VRUs have been used to recover flash gas when there is sufficient quantity to justify the investment and to meet air emission standards. The typical type of vapor recovery compressors used for vent flash gas has been natural gas driven rotary screw compressors and rotary vane compressors.
The United States Minerals Management Service (MMS) is the regulatory agency with jurisdiction over venting of natural gas in the central and western areas of the Gulf of Mexico. MMS regulations require a facility to recover natural gas volumes over 50,000 standard cubic feet per day rather than venting directly to the atmosphere or burning in a flare. For offshore production platforms, deck space requirements are a significant consideration for vapor recovery units. To accommodate this limitation, the scroll compressor package has a footprint one-third the size of a traditional VRUs used. In addition, lower overall maintenance costs were a significant factor in the decision to utilize scroll compressor technology. The scroll compressor requires oil changes once per year compared to quarterly for the typical mechanical compressor. Equipment used in the offshore environment required capital upgrades to the typical onshore compression package due to the saltwater corrosive environment and additional safety controls required for operating offshore. For this project the standard onshore VRU was upgraded to meet specifications for the offshore conditions and regulations.
Description and Application of Equipment and Processes
Scroll Compression Technology.
Scroll compression technology is a positive displacement machine that uses two interleaved spiral-shaped scrolls to compress natural gas. With scroll compression technology, one of the scrolls is fixed, while the other orbits eccentrically, thereby trapping and pumping or compressing gas between through successively smaller scroll volume “pockets” until the gas reaches maximum pressure at the center. At the center, the gas is released through a discharge point in the fixed scroll. Compression is continuous since during orbit of the orbiting scroll, multiple gas pockets are compressed simultaneously.
The driver for the compressor is an electric motor. The scroll compressor is a hermetic compressor designed for use with high-pressure refrigerants. It has a broad range of operation and is intrinsically leak free. Scroll compressor technology has been widely used in cooling system applications.
The scroll compressor VRU installed had a horizontal design that has a low profile, low noise, low vibration, and uses variable speed control motors. Depending on the application, the range of inlet pressures of gas to the scroll compressor VRUs may vary from -10.4 to 101.3 pounds per square inch gage and the discharge pressures can range from 43.5 to 363 pounds per square inch gage. The compression ratio ranges from 3 to 15.
Scroll compression technology has been used in oil and gas vapor recovery applications since 2004.
Application of Scroll Technology.
In May of 2009, COMM and the Producer began working together to modify a typical onshore scroll compressor VRU for the platform that was damaged and being refurbished.
The scroll compressor VRU consisted of two stacked modules each 8-foot long by 4-foot wide by 4-foot high steel skids each with an inlet gas scrubber. Each module contained two 15-horsepower scroll compressors and an aftercooler. Each module also included a control panel with Programmable Logic Control (PLC) and variable frequency drive (VFD). The design recovery capacity of this twin module package used was 200,000 standard cubic feet per day.
A suction line connected to the oil storage tanks’ common vent and to the oil treater (i.e., heater treater) vent was installed to the inlet scrubber of the scroll compressor VRU. The suction line to the oil treater was used to collect excess gas from the oil treater that was not used as platform fuel gas. A flow meter was placed on the suction line prior to the inlet of the scroll compressor VRU to measure the amount of natural gas recovered. The discharge of the scroll compressor package was piped to the suction separator/scrubber of the onsite main compressor. This main compressor compresses natural gas for ultimate injection into the sales pipeline.
A purge gas system was installed and used to recycle gas through the scroll compressor VRU when there is insufficient pressure from flash gas in the storage tanks. The purpose of the purge gas system is to keep VRU operating to maintain the scroll compressor’s oil temperature at a minimum of 235 degrees Fahrenheit. By maintaining the oil temperature at or above 235 degrees F, the flash gas will remain in a gas phase.
As a safety measure, a blanket gas system was installed on the storage tanks to maintain approximately 0.5 ounce per square inch of pressure on the tanks to keep oxygen from entering the tanks.
Figure 1 contains a simplified process flow for the VRU.
The control panels with VFD’s were located in the motor control center (MCC) and wiring was run to the scroll compressor VRU which was located on a lower deck of the platform.
Functionally, the scroll compressor operates normally in the recycle mode at 2400 revolutions per minute (rpm). When the pressure builds in the oil storage tanks, a pressure transmitter sends a signal enabling the speed of the compressor to increase to 4800 rpms and the flash gas is recovered and compressed. Once the flash gas from the storage tanks is recovered and the pressure drops in the storage tanks, the VFD ramps the compressor speed down to 2400 rpms. Then the VRU is in recycle mode again.
Any liquids recovered by the gas scrubber are pumped back to the oil storage tanks.
Modifications to VRU Package.
To meet offshore specification, the structural components of the scroll compressor package were already hot dipped galvanized and suitable for offshore installation but other components required refinishing to withstand the corrosive saltwater environment. The compressors and several other components were removed from the modules and specially coated with a three part epoxy coating to withstand the corrosive environment.
In addition to the special coatings needed for offshore, there was a number of safety system modifications needed to make the scroll compressor VRU compliant with the United States Minerals Management Service (MMS) regulations. Offshore operators are required to abide by the American Petroleum Institute (API) Recommended Practices 14C (RP 14C). API RP 14C contains the criteria for designing, installing and testing a safety system on an offshore platform. It identifies each undesirable event that could affect a process component and discusses safety device selection criteria for each component type.Failure to meet RP 14C requirements can result in fines to the operators and in some cases, require an interruption of production which could result in losses of income to the operator until compliance is restored.
Specifically, the modifications in response to RP-14C were:
1. Installation of test circuit for monthly testing of high level alarm/shutdown on the gas scrubber
2. Installation of test circuit for monthly testing of high discharge pressure alarm/shutdown on compressor discharge line
3. Installation of test circuit for monthly testing of low pressure alarm/shutdown on oil storage tanks
4. Addition on redundant oil storage tank pressure transmitter. Installation of test circuit for monthly testing of high pressure alarm/shutdown on oil storage tanks.
Additionally, the Producer’s offshore specifications required the replacement of
several valves to steel construction rather than brass.
The scroll compressor VRU was shipped to the platform in July 2009. The interconnecting piping to and from the scroll compressor VRU was completed in August 2009. Once the installation was completed and the platform was placed into operation, the scroll compressor VRU was brought into operation.
Presentation of Data and Results
For this installation, the scroll compressor VRU had an average recovery of tank flash gas over the initial operating period of 58,000 standard cubic feet per day. The peak flowrate documented was 215,000 standard cubic feet of flash gas per day. A sample of the recovered flash gas that was chemically analyzed had a molecular weight of 26.6 and contained approximately 69 percent by volume of methane. Volatile organic compounds (nonmethane, nonethane hydrocarbons) amounted to approximately 29 percent by volume. The higher heating value was approximately 1540 British Thermal Units (BTU) per standard cubic feet.The hydrogen sulfide content of the flash gas was considered de minimus based on the facility processing sweet natural gas.
The calculated simple payout of this scroll compressor VRU based on the average recovery and gas price of USD 5/MMBTU is 15 months.
The estimated methane emissions recovered were 0.84 US tons per day and the estimated recovery of greenhouse gases were 17.6 US tons per day CO2e. Volatile organic compound (VOC) emissions recovered were 1.0 US tons per day.
The Producer is in the process of modifying the scroll compressor VRU control system. These modifications include the installation of a single programmable logic controller (PLC) to control both modules, replacement of pressure switches with transmitters and the installation of a touch screen control panel next to the VRU. The modifications are needed to meet the Producer’s operating standards. The cost of this modification will result in an extra initial cost of USD 8,000.
Conclusions
The application of scroll based compression technology in the harsh offshore environment is a cost effective and most efficient solution for vapor recovery. By utilizing scroll compression technology for vapor recovery, offshore operators can meet regulatory requirements to reduce emissions, improve their carbon footprint and economically recover flash gas.
Acknowledgments
Our sincerest thanks go to Mr. James Welsh and Mr. Ron Damron for their expertise and diligence in making this project successful.
Reference List
1. Emerson Climate Technologies. April 2008. A Hermetic Scroll Compressor For Application To High Heat-Of-Compression Gases,
http://www.emersonclimate.com/oil_gas/PDF/HermeticScrollCompressorWhitePaper.pdf.
2. RP 14C, Recommended Practice for Analysis, Design, Installation and Testing of Basic Surface Safety Systems on Offshore Production Platforms, sixth edition. March 1998. Washington, DC: API.
第二篇：減輕高壓注氣壓縮機(jī)爆炸風(fēng)險(xiǎn)
摘要
這篇文章闡述了由安可收購(gòu)公司和卡爾加里大學(xué)共同進(jìn)行的一項(xiàng)研究，這是關(guān)于安可公司在蒙大拿州東南部壓縮機(jī)高壓注氣（HPAI）工程的合成潤(rùn)滑油燃燒安全性的研究。擁有超過(guò)每天2,270標(biāo)準(zhǔn)立方米的空氣壓縮能力，而且排氣壓力可達(dá)31.0到34.5兆帕（4500到5000磅/平方英寸），該項(xiàng)目的一個(gè)重要方面就是壓縮機(jī)的安全和不間斷運(yùn)行。安可公司和其他高壓注氣運(yùn)營(yíng)商的經(jīng)驗(yàn)顯示，在高溫級(jí)間結(jié)構(gòu)和排氣區(qū)域即使使用合成酯基潤(rùn)滑油，高壓空氣壓縮機(jī)潤(rùn)滑油也可能是一種麻煩（破壞性超壓）的來(lái)源。
利用加速量熱儀（ARC），使用了合成潤(rùn)滑油的新樣本在空氣中的初始?xì)鈮嚎梢员患訜岬?4.5兆帕（5000磅/平方英寸），自升溫速率和壓力反映也能被測(cè)量出來(lái)。
研究結(jié)果高度強(qiáng)調(diào)了壓力對(duì)自燃溫度的重要影響。更重要的是，酯基潤(rùn)滑油的自燃溫度從制造商所報(bào)告的在標(biāo)準(zhǔn)氣壓測(cè)量的攝氏410度（華氏770度）下降到在氣壓為17.2到34.5兆帕（2500到5000磅/平方英寸）測(cè)量的攝氏180度（華氏365度）。另外，氧化合成潤(rùn)滑油的自燃溫度將進(jìn)一步導(dǎo)致壓縮機(jī)運(yùn)行溫度值的降低。最后，有人指出，不同品牌酯基潤(rùn)滑油的自燃溫度都非常相似。
這項(xiàng)研究的意義不僅僅在于溫度數(shù)據(jù)，更在于其研究結(jié)果即安可公司對(duì)旗下高壓空氣壓縮機(jī)的設(shè)計(jì)和運(yùn)行的一些重要修改的討論。這些信息將有助于未來(lái)設(shè)計(jì)安全和可靠的空氣壓縮系統(tǒng)的高壓注氣運(yùn)營(yíng)商。
引言
通過(guò)高壓注氣（HPAI）改進(jìn)傳統(tǒng)的輕質(zhì)油回收已經(jīng)成為一個(gè)眾所周知的過(guò)程。隨著石油需求的增加以及減少初級(jí)和次級(jí)生產(chǎn)為基礎(chǔ)的儲(chǔ)備更多的生產(chǎn)商對(duì)高壓注氣產(chǎn)生濃厚的興趣。典型例子有2002年安可公司佩內(nèi)爾機(jī)組的八注射器的每標(biāo)準(zhǔn)立方米17e3高壓注氣工程，已經(jīng)擴(kuò)展到每標(biāo)準(zhǔn)立方米1700e3。在洪區(qū)原始部分里連續(xù)四年注入34.5兆帕的空氣。此外，一個(gè)新的每標(biāo)準(zhǔn)立方米566e3的高壓注氣工程在2004年在錫達(dá)河處展開(kāi)，東靠小比弗蒙大拿/北達(dá)科他州的交界處。該項(xiàng)目有18個(gè)注入井，操作壓力為31兆帕。圖1表示的是位于錫達(dá)河背斜[超過(guò)160公里（100英
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