順丁烯二酸酐（Maleic Anhydride，MA）簡稱順酐，又名 2,5—呋喃二酮、馬來酸酐、 失水蘋果酸酐，是目前世界上僅次于苯酐和醋酐的第三大酸酐，常溫下為無色針狀結晶 體，有刺激性氣味與酸味，熔點 52.8℃，沸點 202℃，易升華易燃，升華，易溶于水， 生成順丁烯二酸（馬來酸），也溶于苯及丙酮、乙醇等有機溶劑，是一種常用的重要有機 化工原料。下游應用領域廣泛，包括不飽和聚酯樹脂（UPR）、油漆、涂料、固化劑、有 機酸、染料、水處理劑、潤滑油添加劑、松香等數十個行業(yè)。
Maleic anhydride (MA), also known as 2,5-furanedione, maleic anhydride and dehydrated malic anhydride, is the third largest anhydride in the world after phthalic anhydride and acetic anhydride. It is a colorless acicular crystal at room temperature, with an irritating smell and sour taste. Its melting point is 52.8 ℃, and its boiling point is 202 ℃. It is easily sublimated, flammable, sublimated, and soluble in water to generate maleic acid (maleic acid), which is also soluble in benzene, acetone Ethanol and other organic solvents are commonly used as important organic chemical raw materials. The downstream application fields are extensive, including dozens of industries such as unsaturated polyester resin (UPR), paint, coating, curing agent, organic acid, dye, water treatment agent, lubricating oil additive, rosin, etc.
目前可降解塑料根據原料主要分為PLA、PBS、PCL、PHA、PHB等，其中PBS（聚丁二酸丁二醇酯）以低廉、力學性能優(yōu)異、加工耐熱性能好等特點成為目前具有產業(yè)化前景的通用型生物可降解塑料之一，PBS主要原料丁二酸的基礎原料是順酐。
At present, degradable plastics are mainly divided into PLA, PBS, PCL, PHA, PHB, etc. According to raw materials, PBS (polybutylene succinate) has become one of the universal biodegradable plastics with industrialization prospects because of its low price, excellent mechanical properties, and good processing heat resistance. The basic raw material for producing succinic acid, the main raw material of PBS, is maleic anhydride.
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雖然國內順酐起步于上世紀90年代，因順酐項目建設伊始是由苯法工藝興起的，主要得益于國內焦化苯資源豐富，以及下游產業(yè)發(fā)展緩慢，但是隨著苯法項目的不斷上新，迅速導致順酐產能過剩。2000年前后因素影響苯法順酐工藝發(fā)展，尤其是焦化苯快速被加氫苯所取代，苯法成本較大幅度提升，加速了苯法工藝的衰退。而2012年前后開始齊翔騰達，江寧化工等丁烷法項目陸續(xù)投產，因其產能較大，快速搶占了市場份額，在2015年前后，丁烷法與苯法工藝完成了“交接”，目前順酐市場流通貨源76%以上為丁烷法工藝,其主要流程如下所示：
Although domestic maleic anhydride started in the 1990s, because the construction of maleic anhydride project was started by benzene process, mainly due to the rich coking benzene resources in China and the slow development of downstream industries, the continuous upgrading of benzene process projects quickly led to overcapacity of maleic anhydride. Environmental protection factors affected the development of benzene maleic anhydride process around 2000, especially coking benzene was rapidly replaced by hydrogenated benzene, which greatly increased the production cost of benzene process and accelerated the decline of benzene process. Qixiang Tengda started around 2012, and Jiangning Chemical and other butane process projects were put into production successively. Because of their large capacity, they quickly seized the market share. Around 2015, the butane process and benzene process completed the "handover". At present, more than 76% of the circulating goods in the maleic anhydride market are butane process, and the main processes are as follows:
化工行業(yè)之順酐產業(yè)研究：邊際需求爆發(fā)，行業(yè)格局重塑
Research on Maleic Anhydride Industry in Chemical Industry: Outburst of Marginal Demand, Reshaping of Industry Pattern
①進料及反應工序
① Feeding and reaction process
常溫、常壓下的空氣經空氣過濾器過濾后，由電動鼓風機組、蒸汽透平機驅動的鼓風機組壓縮，再經空氣加熱器加熱一定溫度。正丁烷液體經輸送泵加壓后送入到正丁烷蒸發(fā)罐，然后使用正丁烷蒸發(fā)器使其汽化，再經正丁烷過熱器加熱一定溫度。過熱的正丁烷氣與空氣混合成一定濃度反應氣體進入立式管/殼型反應器中，在反應器殼程中采用熔鹽混合物通過熔鹽泵往復循環(huán)用作冷卻介質；反應氣體進入管程在催化劑的作用下進行氧化反應，反應過程中加入助催化劑。反應熱通過熔鹽移走，部分熔鹽經過熔鹽冷卻器的殼程，通過與熔鹽冷卻器管的鍋爐水換熱產生蒸汽并使其冷卻。反應器溫度靠控制流經熔鹽冷卻器的熔鹽流量進行控制。反應后的熱反應氣體經氣體冷卻器和切換冷卻器管程冷卻之后送吸收工序。氣體冷卻器和切換冷卻器殼程中的鍋爐水被加熱并部分氣化，和熔鹽冷卻器中產生的蒸汽在蒸汽包中分離出來或過熱后供裝置內蒸汽透平機及其它用戶做為熱源使用。
The air under normal temperature and pressure is filtered by air filter, compressed by electric blower unit and blower unit driven by steam turbine, and then heated to a certain temperature by air heater. The n-butane liquid is pressurized by the delivery pump and sent to the n-butane evaporation tank, then vaporized by the n-butane evaporator, and heated to a certain temperature by the n-butane superheater. The superheated n-butane gas is mixed with air to form a reaction gas with a certain concentration and enters the vertical tube/shell reactor. In the shell side of the reactor, molten salt mixture is used for reciprocating circulation through the molten salt pump as the cooling medium; The reaction gas enters the tube side to conduct oxidation reaction under the action of catalyst, and cocatalyst is added in the reaction process. The reaction heat is removed through molten salt, and part of the molten salt passes through the shell side of the molten salt cooler to generate steam and cool it by exchanging heat with the boiler water of the molten salt cooler tube. The reactor temperature is controlled by controlling the molten salt flow through the molten salt cooler. The thermal reaction gas after reaction is sent to the absorption process after being cooled by the gas cooler and switching cooler tube side. The boiler water in the shell side of the gas cooler and switching cooler is heated and partially gasified, and the steam generated in the molten salt cooler is separated from the steam package or superheated for the steam turbine and other users in the device to use as the heat source.
在反應器進料系統(tǒng)中設有增濕系統(tǒng)和助劑添加系統(tǒng)以保證催化劑的更佳轉化率和選擇性。增濕系統(tǒng)是通過調節(jié)低壓蒸汽加入量以達到工藝要求；助劑添加是通過氮氣鼓泡方法加入到過熱正丁烷氣體中。
A humidification system and a promoter adding system are set in the reactor feed system to ensure better conversion and selectivity of the catalyst. The humidification system achieves the process requirements by adjusting the amount of low-pressure steam added; The additive is added to the superheated n-butane gas by nitrogen bubbling.
②吸收、解吸、精制
② Absorption, desorption and refining
在吸收系統(tǒng)，被貧溶劑（DIBE）從切換冷卻器排出的順酐富氣中的順酐被貧溶劑（DIBE）吸收出來。之后，在解吸段，順酐通過真空蒸餾從富溶劑中解吸出來，含有少量有機物的尾氣送到尾氣處理系統(tǒng)。
In the absorption system, maleic anhydride in the rich gas of maleic anhydride discharged from the switching cooler by the lean solvent (DIBE) is absorbed by the lean solvent (DIBE). Then, in the desorption section, maleic anhydride is desorbed from the rich solvent through vacuum distillation, and the tail gas containing a small amount of organic matter is sent to the tail gas treatment system.
由于順酐吸收過程和冷凝過程在同一時間發(fā)生，在氣相流股被冷卻時，順酐絕大部分被從氣體中移走。為了使這一過程的熱量被全部移出同時維持一個較低的貧溶劑流量，吸收塔下部塔盤在一個帶冷卻循環(huán)回路的直聯(lián)式冷卻器條件下操作。從塔下部上升的氣體被冷卻后在塔內部塔盤得到吸收，在吸收塔內，富氣從塔底進入并上升，同時貧溶劑從塔頂進入，富溶劑用吸收塔循環(huán)泵一部分輸送到吸收塔循環(huán)，另一部分輸送到富溶劑貯罐，吸收塔頂排出的尾氣送到尾氣處理系統(tǒng)。
Since the absorption and condensation of maleic anhydride occur at the same time, most of the maleic anhydride is removed from the gas when the gas stream is cooled. In order to remove all the heat in this process and maintain a low lean solvent flow, the lower tray of the absorption tower is operated under the condition of a direct cooler with a cooling circulation loop. The gas rising from the lower part of the tower is absorbed in the tray inside the tower after being cooled. In the absorption tower, rich gas enters and rises from the bottom of the tower, while lean solvent enters from the top of the tower. The rich solvent is transported to the absorption tower for circulation by the circulating pump of the absorption tower, and the other part is transported to the rich solvent storage tank. The tail gas discharged from the top of the absorption tower is sent to the tail gas treatment system.
富溶劑從富溶劑貯罐經閃蒸塔進行閃蒸后進入到解吸塔中部,蒸汽噴射系統(tǒng)（順酐真空系統(tǒng)）保持了塔內真空，解吸塔底部以再沸器加熱，頂部出口氣回到解吸塔。
The rich solvent enters the middle of the desorption tower after flashing from the rich solvent storage tank through the flash tower. The steam injection system (maleic anhydride vacuum system) maintains the vacuum in the tower. The bottom of the desorption tower is heated by a reboiler, and the top outlet gas returns to the desorption tower.
解吸塔底部解吸后的貧溶劑經與解吸塔進料換熱后返回吸收塔。解吸后的貧溶劑經過與解吸塔進料換熱后返回吸收塔。解吸塔頂部導出的粗順酐氣體經冷凝后進入到精制部分。
The lean solvent desorbed at the bottom of the desorber returns to the absorber after heat exchange with the desorber feed. The desorbed lean solvent returns to the absorption tower after heat exchange with the desorber feed. The crude maleic anhydride gas from the top of the desorption tower enters the refining section after condensation.
在精制部分粗順酐進入到脫輕組分塔，輕組分塔頂導出的輕組分經冷凝后一部分回流到塔頂；一部分輸送焚燒爐。塔底排出的粗酐進入到成品塔，成品塔頂導出的順酐氣體經冷凝后輸出成品中間罐；塔底含有順酐的重組分輸送到解吸塔。
The crude maleic anhydride in the refining section enters the light component removal tower, and part of the light components from the top of the light component tower will flow back to the tower top after condensation; Some of them are delivered to incinerator. The crude anhydride discharged from the bottom of the tower enters the finished tower, and the maleic anhydride gas from the top of the finished tower is condensed and then output to the finished intermediate tank; The heavy fraction containing maleic anhydride at the tower bottom is delivered to the desorption tower.
③溶劑貯存
③ Solvent storage
a、溶劑貯存
a. Solvent storage
溶劑貯存系統(tǒng)的目的是冷卻和貯存貧溶劑，并將其提供給吸收塔、尾氣洗滌塔。貧溶劑儲存在貧溶劑儲罐中，并以貧溶劑進料泵送入裝置中。因在裝置有少量損失, 新鮮的貧溶劑須不斷與外界定期性的補充到裝置中。
The purpose of solvent storage system is to cool and store lean solvent and provide it to absorption tower and tail gas scrubber. The lean solvent is stored in the lean solvent storage tank and pumped into the unit by the lean solvent feed pump. As there is a small amount of loss in the unit, fresh lean solvent must be regularly added to the unit with the outside world.
b、溶劑處理系統(tǒng)
b. Solvent treatment system
貧溶劑中含有的未被處理的富馬酸酐等雜質，通過堿洗和水洗溶劑來實現從裝置中除去，貧溶劑和水持續(xù)不斷的加到攪拌預混罐中，之后進入多級堿洗和水洗傾析器，溶劑相之后進入貧溶劑緩沖罐，水相回用于洗釜。
Impurities such as untreated fumaric anhydride contained in the lean solvent can be removed from the unit through alkali washing and water washing solvent. The lean solvent and water are continuously added to the stirred premix tank, and then enter the multi-stage alkali washing and water washing decanter. The solvent phase then enters the lean solvent buffer tank, and the water phase is used for kettle washing.
④結片成型系統(tǒng)
④ Patch forming system
由順酐成品罐來的精制后的熔融順酐，用順酐輸送泵送到順酐中間罐中。用結片進料泵送到液酐冷卻器冷卻后，送結片機中。液態(tài)順酐在結片機轉鼓表面被轉鼓內的冷水冷卻結晶并被刮刀切下，片狀順酐由重力經中間漏斗后，加定量包裝機中稱重包裝。
The refined molten maleic anhydride from the finished maleic anhydride tank is sent to the maleic anhydride intermediate tank by the maleic anhydride delivery pump. The flake feed pump is used to send the liquid anhydride cooler to the flaker for cooling. The liquid maleic anhydride is cooled and crystallized on the surface of the flaker drum by the cold water in the drum and cut off by the scraper. The flake maleic anhydride is added to the quantitative packaging machine for weighing and packaging after passing through the middle funnel by gravity.
來自循環(huán)水罐的溫水用于冷卻順酐和進料管、結片機的夾套保溫。結片機裝有排風系統(tǒng)，以防止順酐升華氣體的外漏。引風機排出的氣體經尾氣洗滌塔循環(huán)的工藝水洗滌后排入大氣，洗滌液經泵輸送工藝水罐。
Warm water from circulating water tank is used to cool maleic anhydride and jacket insulation of feed pipe and flaker. The flaker is equipped with an exhaust system to prevent the leakage of maleic anhydride sublimation gas. The gas discharged from the induced draft fan is washed by the process water circulating in the tail gas scrubber and then discharged into the atmosphere. The washing solution is pumped to the process water tank.
