KR20020009748A - Coating method for retarding coke on the internal wall of hydrocarbon pyrolysis reactor tube - Google Patents
Coating method for retarding coke on the internal wall of hydrocarbon pyrolysis reactor tube Download PDFInfo
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- KR20020009748A KR20020009748A KR1020000043154A KR20000043154A KR20020009748A KR 20020009748 A KR20020009748 A KR 20020009748A KR 1020000043154 A KR1020000043154 A KR 1020000043154A KR 20000043154 A KR20000043154 A KR 20000043154A KR 20020009748 A KR20020009748 A KR 20020009748A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/02—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by baking
- B05D3/0209—Multistage baking
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D1/00—Processes for applying liquids or other fluent materials
- B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
- B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
- B05D7/146—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies to metallic pipes or tubes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
- B05D7/22—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to internal surfaces, e.g. of tubes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D2202/00—Metallic substrate
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D2254/00—Tubes
- B05D2254/04—Applying the material on the interior of the tube
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D2301/00—Inorganic additives or organic salts thereof
Abstract
Description
본 발명은 탄화수소 열분해 반응기 튜브 내벽에 코크 저감을 위한 코팅방법에 관한 것으로, 좀 더 구체적으로는 탄화수소 열분해 반응기 튜브 내벽에 무기화합물을 코팅시켜 코크의 생성 또는 축적을 억제시킬 뿐만 아니라, 금속 침탄 및 침화를 방지하여 반응기 수명을 연장시킬 수 있는 탄화수소 열분해 반응기 튜브 내벽에 코크 저감을 위한 코팅방법에 관한 것이다.The present invention relates to a coating method for reducing the coke on the inner wall of the hydrocarbon pyrolysis reactor tube, and more specifically to coating the inorganic compound on the inner wall of the hydrocarbon pyrolysis reactor tube to suppress the formation or accumulation of coke, as well as metal carburization and sedimentation It relates to a coating method for reducing the coke on the inner wall of the hydrocarbon pyrolysis reactor tube that can prevent the prolonged reactor life.
일반적으로 열분해 반응기는 가열로와 일련의 반응튜브로 구성되어 있으며, 수증기와 탄화수소를 기상으로 800℃ 이상의 고온 반응튜브에 공급함으로써 열분해 반응이 일어나도록 하여 에틸렌, 프로필렌 등의 올레핀 제품을 생산하는 장치이다.상기 열분해 과정에서 튜브 표면에 노출된 니켈, 철 성분의 촉매작용에 의해 탄화수소의 탈수소화로 촉매코크가 생성되며, 다른 한편으로는 아세틸렌 등과 같은 경질 올레핀의 탈수소화에 의한 가스코크, 중질 아로마틱 성분의 탈수소화에 의한 응축코크가 생성된다.In general, a pyrolysis reactor is composed of a heating furnace and a series of reaction tubes. The pyrolysis reactor is a device for producing olefin products such as ethylene and propylene by causing pyrolysis reaction by supplying steam and hydrocarbons to a high temperature reaction tube of 800 ° C. or higher in the gas phase. Catalytic coke is produced by dehydrogenation of hydrocarbons by catalysis of nickel and iron components exposed to the tube surface during the pyrolysis process, and on the other hand, gascoque and heavy aromatic components by dehydrogenation of light olefins such as acetylene. Condensation coke is produced by the dehydrogenation of.
열분해 반응이 진행되면서 이들 코크는 단독 또는 상호 트랩 작용을 통해 튜브 내벽에 코크층을 형성한다. 코크 축적은 유체흐름을 방해하여 튜브 전후단의 압력차를 증가시키고, 튜브벽면을 통한 열전달 효율을 감소시켜 주요 제품의 반응 수율을 감소시키고 에너지 소비를 증가시키는 등 열분해 반응에 악영향으로 작용할 뿐 아니라, 탄소의 금속 침탄작용에 의해 반응기의 수명을 저하시키는 작용을 한다. 따라서 코크 축적량이 일정수준에 이르면 코크를 제거해 주기 위해 운전을 중단해야 하며, 코크 제거 기간 동안의 생산 손실 및 에너지 손실분은 비교적 크므로 코크 생성 저감을 통해 운전주기를 연장하기 위해 수많은 방안이 제시되고 있다.As the pyrolysis reaction proceeds, these cokes form a coke layer on the inner wall of the tube, either alone or through mutual trapping. Coke buildup not only adversely affects the pyrolysis reactions by disturbing fluid flow, increasing the pressure difference between the front and rear ends of the tube, reducing the heat transfer efficiency through the tube wall, reducing the reaction yield of main products and increasing energy consumption. It acts to reduce the lifetime of the reactor by carbon carburization of carbon. Therefore, when coke accumulation reaches a certain level, operation must be stopped to remove coke, and production loss and energy loss during coke removal are relatively large. Therefore, numerous measures are proposed to extend the operation cycle by reducing coke generation. .
예를 들어, 특수 합금을 반응튜브 재질로 사용하여 촉매코크의 생성을 줄이는 방법, 원료에 황성분, 알칼리금속염, 알칼리토금속염, 인화합물, 붕소화합물, 세륨화합물, 란타늄 화합물, 몰리브데늄 등의 화합물을 연속주입하는 방법(미국특허 제5,358,626호, 제4,889,614호, 제5,000,836호, 제4,962,264호, 제4,680,421호, 제5,128,023호, 제5,330,970호 및 제4,542,253호), 주석 및 실리콘 화합물, 알루미늄 화합물, 인화합물로 반응튜브 내표면을 전처리하는 방법(미국특허 제5,446,229호, 제5,565,087호, 제5,616,236호 및 제5,656,150호), 알칼리 토금속 화합물을 코팅시켜 세라믹막을 형성시키는 방법(미국특허 제5,807,616호 및 제5,833,838호),실리콘 세라믹 물질로 화학증착시키는 방법(미국특허 제5,413,813호) 등이 있다.For example, using a special alloy as a reaction tube material to reduce the production of catalyst coke, raw materials sulfur compounds, alkali metal salts, alkaline earth metal salts, phosphorus compounds, boron compounds, cerium compounds, lanthanum compounds, molybdenum, etc. Continuous injection method (US Pat. Nos. 5,358,626, 4,889,614, 5,000,836, 4,962,264, 4,680,421, 5,128,023, 5,330,970 and 4,542,253), tin and silicon compounds, aluminum compounds, phosphorus A method of pretreating the surface of a reaction tube with a compound (US Pat. Nos. 5,446,229, 5,565,087, 5,616,236 and 5,656,150), and a method of coating an alkaline earth metal compound to form a ceramic film (US Pat. No. 5, US Pat. No. 5,413,813 and the like.
특히, 상기 미국특허 제5,807,616호에서는 튜브내벽에 유리 세라믹막을 형성시켜 코크를 저감시키는 방법을 제공하고 있다. 상기 방법에 따르면, SiO2, B2O3, Al2O3, BaO, MgO, CaO, ZnO, ZrO2, MnO, SrO 및 NiO를 분말상태로 하여 바인더와 함께 슬러리상을 만들고, 이를 금속시편에 분사한 후 유동화 온도 1150℃에서 열처리하여 37.5∼250㎛ 두께의 유리 세라믹막을 만든 다음, 이를 850℃에서 에탄 열분해를 실시한 결과 95∼99% 코크 저감 효과를 나타낸다고 기재하고 있다. 그러나, 이 방법은 슬러리상을 사용하기 때문에 공정중 직접 코팅이 불가능하고, 튜브를 공정 외에서 코팅한 다음, 용접하여 사용해야 하므로 1회성 코팅으로 밖에 사용할 수 없다. 그리고 슬러리내 분말이 유리 세라믹막을 형성하기 위해서는 유동화 온도 이상 승온해야 하고, 이를 다시 감온하여 결정화함으로써 코팅막을 형성해야 하므로 열분해 사용온도는 슬러리의 유동화 온도 이하이어야 한다. 실제 공정에서 튜브의 사용온도범위가 운전주기의 임계값으로 작용하는 경우가 많으며, 이런 경우 운전온도가 슬러리의 유동화 온도를 초과하므로 적용이 불가능하다. 또한, 슬러리상으로 코팅시키기 때문에 균일한 분포 및 얇은막 형성이 어렵다는 단점이 있다.In particular, US Patent No. 5,807,616 provides a method of reducing coke by forming a glass ceramic film on the inner wall of the tube. According to the above method, a slurry is formed with a binder by using SiO 2 , B 2 O 3 , Al 2 O 3 , BaO, MgO, CaO, ZnO, ZrO 2 , MnO, SrO and NiO in powder form, and the metal specimen After spraying on, it is heat-treated at a fluidization temperature of 1150 ° C. to produce a glass ceramic film having a thickness of 37.5 to 250 μm, and then ethane pyrolysis at 850 ° C. shows 95 to 99% coke reduction effect. However, this method cannot be directly coated during the process because of the use of slurry phase, and can only be used as a one-time coating because the tube must be coated outside the process and then used by welding. In order to form a glass ceramic film, the powder in the slurry must be heated above the fluidization temperature, and the temperature of the pyrolysis should be below the fluidization temperature of the slurry because the coating film must be formed by reducing the temperature and crystallizing it again. In the actual process, the operating temperature range of the tube often acts as a threshold of the operation cycle, and in this case, the operation temperature exceeds the fluidization temperature of the slurry, and thus cannot be applied. In addition, there is a disadvantage in that it is difficult to uniformly distribute and form a thin film because the coating in the slurry phase.
이에 본 발명에서는 반응튜브 내벽을 코팅하여 니켈, 철 등의 금속과 탄화수소간의 촉매작용을 차단함으로써 촉매코크 생성을 억제할 뿐 아니라 가스코크 및 응축코크의 트랩역할을 제거함으로써 코크축적을 저감하고자 하며, 또한 차단막에의한 금속침탄 및 침화를 억제하는 기능을 부여하고자 하였다. 본 발명에 있어서, 금속산화 및 코크 생성의 촉매작용을 차단하기 위해 균일한 코팅막의 형성은 중요한 기술요소이며, 형성된 막이 유체흐름의 침식과정에서 기계적 강도를 유지해야 하며, 고온에서 열화되지 않고 안정성을 확보해야 하는 것이 관건이다. 이를 위해 코팅제를 수용액상으로 사용하여 튜브를 분리하지 않고 공정중 직접 적용이 가능하도록 하였으며, 막의 두께 및 형상 조절이 용이하도록 하였고, 코팅제로는 운전온도 및 튜브를 사용하기에 가능한 온도범위내에서 열처리를 완성하므로 사용상의 제약이 없고 열처리후 기계적 강도 및 열적 안정성을 확보할 수 있도록 선정하였다.Therefore, the present invention is to reduce the coke accumulation by coating the inner wall of the reaction tube to inhibit the catalytic coke production by blocking the catalytic action between metals such as nickel, iron, and hydrocarbons, as well as by removing the trap role of gas coke and condensation coke, In addition, it was intended to provide a function of suppressing metal carburization and infiltration by the barrier film. In the present invention, the formation of a uniform coating film is an important technical element in order to block the catalysis of metal oxidation and coke formation, and the formed film must maintain mechanical strength during the erosion of the fluid flow, and does not deteriorate at high temperatures and maintains stability. The key is to secure it. For this purpose, the coating agent is used as an aqueous solution, so that it can be directly applied during the process without separating the tube, and the thickness and shape of the membrane can be easily adjusted. It is selected to ensure mechanical strength and thermal stability after heat treatment because there is no restriction on use.
따라서, 본 발명의 목적은 금속산화 및 코크 생성의 촉매작용을 차단하기 위해 균일한 코팅막을 형성할 수 있고, 형성된 막이 유체흐름의 침식과정에서 기계적 강도를 유지할 수 있으며, 고온에서 열화되지 않고 안정성을 확보할 수 있는 탄화수소 열분해 반응기 튜브 내벽에 코크 저감을 위한 코팅방법을 제공하는데 있다.Therefore, an object of the present invention can form a uniform coating film to block the catalysis of metal oxidation and coke formation, the formed film can maintain the mechanical strength during the erosion of the fluid flow, stability without high temperature degradation To provide a coating method for reducing the coke on the inner wall of the hydrocarbon pyrolysis reactor tube that can be secured.
상기 목적을 달성하기 위한 본 발명의 코팅방법은 알칼리금속/토금속 실리케이트 단독 또는 무기화합물과의 혼합물을 수용액상으로 제조하여 탄화수소 열분해 반응튜브 내벽에 상온 내지 100℃에서 도포하고, 이를 80∼120℃로 유지시켜 건조한 다음, 시간당 50∼300℃로 승온시켜 400∼600℃에서 열처리하여 코팅막을 형성시키는 것으로 구성된다.The coating method of the present invention for achieving the above object is to prepare an alkali metal / earth metal silicate alone or a mixture with an inorganic compound in an aqueous solution and to apply to the inner wall of the hydrocarbon pyrolysis reaction tube at room temperature to 100 ℃, this is to 80 ~ 120 ℃ It is then maintained, dried, and then heated to 50 to 300 ° C. per hour to heat treatment at 400 to 600 ° C. to form a coating film.
도 1은 본 발명에 따른 코팅절차를 개략적으로 나타낸 블럭도이다.1 is a block diagram schematically showing a coating procedure according to the present invention.
도 2는 종래의 튜브와 본 발명에 따라 코팅된 튜브에 대한 코크 생성 정도를 평가하기 위한 열분해 반응 모사 실험 장치의 개략도이다.2 is a schematic diagram of a pyrolysis reaction simulation apparatus for evaluating the degree of coke formation for conventional tubes and tubes coated according to the present invention.
이하 본 발명을 좀 더 구체적으로 살펴보면 다음과 같다.Looking at the present invention in more detail as follows.
본 발명은 알칼리금속/토금속 실리케이트 단독 사용하거나, 알루미나, 실리카, 실리카알루미나, 포타슘, 칼슘, 마그네슘, 붕소 및 리튬 화합물로 이루어진 군으로부터 하나 또는 그 이상 선택된 무기화합물과의 혼합물을 수용액 상태로 제조하여 반응기 튜브내벽에 분사 또는 충진후 배출하여 수용액층을 형성한 후 이를 400∼600℃에서 열처리를 완료함으로써 코크의 생성/축적 및 금속 침탄/침화를 방지할 수 있는 견고한 코팅막을 형성시키는 방법에 관한 것이다.The present invention uses an alkali metal / earth metal silicate alone, or a mixture of one or more inorganic compounds selected from the group consisting of alumina, silica, silica alumina, potassium, calcium, magnesium, boron and lithium compounds in an aqueous solution state to prepare a reactor The present invention relates to a method of forming a solid coating film which can prevent generation / accumulation of coke and metal carburization / precipitation by forming an aqueous solution layer by spraying or filling the inner wall of the tube and then discharging the same to form an aqueous solution.
본 발명의 코팅방법에 따르면, 코팅하고자 하는 물질의 수용액을 제조하여 열분해 튜브를 상온 내지 100℃로 식힌 후 코팅수용액을 튜브 내부에 분사 또는 채워서 수분간 정치한 다음 용액을 배출한다. 이때, 튜브의 온도가 100℃를 초과하면 튜브 내벽에서 기화가 일어나므로 수용액 층이 균일하게 도포되지 않는 경향이 있다. 코팅제의 점성에 의해 얇은 수용액층이 튜브 내벽에 형성되어 있는 상태에서, 반응기의 온도를 80∼120℃ 정도로 수시간 유지하여 수분을 충분히 제거한다. 이때 불활성 가스를 흘려 주면 건조에 유리하다. 코팅층에 포함된 수분을 건조하는 과정은 코팅막 형성에 중요한 역할을 한다. 용액 배출 후 잔여 수용액이 고여 있지 않도록 주의해야 하며, 수용액이 고여 있을 경우 건조하는데에 시간이 오래 걸리고, 만약 건조가 불완전할 경우 고온 가열시 코팅막 내부에서 스팀이 형성되어 코팅막에 기포가 형성되면서 부풀어 오르는 현상이 발생한다. 건조가 끝나면 서서히 시간당 50∼300℃로 승온하여 열처리를 실시하고, 400∼600℃에서 결정수가 완전히 제거되면서 금속튜브와 막간 접착력이 강화된 견고한 막을 형성시킨다. 상기 승온온도가 50℃ 미만이면 열처리에 불필요하게 과도한 시간이 소요되고, 300℃를 초과하면 과도한 기화에 의해 막의 결함을 유발하는 경향이 있다.According to the coating method of the present invention, after preparing an aqueous solution of the material to be coated, the pyrolysis tube is cooled to room temperature to 100 ° C, and then the coating aqueous solution is sprayed or filled into the tube to stand for several minutes, and then the solution is discharged. At this time, if the temperature of the tube exceeds 100 ℃ vaporization occurs in the inner wall of the tube tends not to uniformly apply the aqueous solution layer. In a state where a thin aqueous solution layer is formed on the inner wall of the tube by the viscosity of the coating agent, the temperature of the reactor is maintained at about 80 to 120 ° C. for several hours to sufficiently remove moisture. At this time, flowing an inert gas is advantageous for drying. The process of drying the moisture contained in the coating layer plays an important role in forming the coating film. After discharging the solution, care should be taken not to accumulate the remaining aqueous solution.If the aqueous solution is accumulated, it takes a long time to dry. If the drying is incomplete, steam is formed inside the coating film during the high temperature heating and bubbles are formed in the coating film. Phenomenon occurs. After drying, the temperature is gradually increased to 50 to 300 ° C. per hour, followed by heat treatment. The crystal water is completely removed at 400 to 600 ° C. to form a strong film having enhanced adhesion between the metal tube and the film. If the elevated temperature is less than 50 ℃ unnecessarily excessive time is required for the heat treatment, if it exceeds 300 ℃ tends to cause a defect of the film by excessive vaporization.
본 발명이 기존 방법과 다른 것은 코팅물질을 수용액 상태로 사용하고, 400∼600℃에서 열처리가 완료된다는 것이다. 이때, 상기 열처리 온도가 400℃ 미만이면 결정수가 완전히 제거되지 않으며, 600℃를 초과하면 과도한 기화에 의해 막에 결함을 유발하는 경향이 있다.The present invention is different from the existing method is that the coating material is used in an aqueous state, and the heat treatment is completed at 400 ~ 600 ℃. At this time, when the heat treatment temperature is less than 400 ° C, the crystal water is not completely removed, and when the heat treatment temperature exceeds 600 ° C, there is a tendency to cause defects in the film due to excessive vaporization.
본 발명에 있어서, 수용액을 사용하기 때문에 다루기가 수월하여 공정중 튜브를 상온 내지 100℃로 식힌후 직접 적용할 수 있으므로 1회성이 아닌 반복코팅이 가능하고, 운전전에 반응 튜브 영역만을 코팅 대상으로 하기 때문에 후단 공정에 전혀 영향을 미치지 않는다. 또한, 수용액 상태로 사용하기 때문에 균일한 코팅막을 형성하기에 용이하며, 코팅용액의 농도 조절에 의해 막두께 조절이 가능하고, 박막으로 코팅하기 때문에 코팅막과 튜브간의 열팽창 차이에 의한 코팅막 균열 현상이 발생할 가능성이 적다.In the present invention, since the aqueous solution is used, it is easy to handle and can be directly applied after the tube is cooled to room temperature to 100 ° C. in the process, so that it is possible to repeat coating, not one-time, and to apply only the reaction tube region to the coating target before operation. Therefore, it does not affect the post process at all. In addition, since it is used in an aqueous state, it is easy to form a uniform coating film, and the film thickness can be controlled by adjusting the concentration of the coating solution, and since coating with a thin film, a coating film crack phenomenon may occur due to a difference in thermal expansion between the coating film and the tube. Less likely
아울러, 열처리 완성 온도가 400∼600℃ 정도이므로 운전온도 및 튜브 사용온도범위의 제약을 받지 않을 뿐 아니라, 열처리에 의해 코팅층의 견고성 및 금속기질과 막사이의 접착성을 증대시키기 때문에 기계적 강도를 충분히 확보할 수 있다.In addition, since the completion of the heat treatment temperature is about 400 ~ 600 ℃ not only is not limited by the operating temperature and tube operating temperature range, but also the mechanical strength is sufficiently increased because the heat treatment increases the firmness of the coating layer and the adhesion between the metal substrate and the film. It can be secured.
본 발명에 따르면, 알칼리금속/토금속 실리케이트을 단독물질로 하여 코팅시킬 경우, 일정온도까지 열적 안정성을 가질 수 있고, 그 이상의 고온 안정성을 확보하기 위해 무기화합물을 첨가한 혼합용액을 이용할 수 있으며, 이로 인해 열적 안정성을 보완할 수 있을 뿐 아니라, 알칼리금속/토금속 성분에 의한 코크 가스화 촉매기능을 제공할 수 있다. 본 발명에 바람직한 알칼리금속/토금속 실리케이트로는 포타슘실리케이트 또는 소디움실리케이트 등을 사용할 수 있다.According to the present invention, when the alkali metal / earth metal silicate is coated with a single substance, it may have thermal stability up to a certain temperature, and a mixed solution containing an inorganic compound may be used to secure higher temperature stability. In addition to complementing the thermal stability, it is possible to provide a coke gasification catalyst function by alkali / earth metal components. As the alkali metal / earth metal silicate preferred in the present invention, potassium silicate or sodium silicate can be used.
예를 들어, 포타슘실리케이트 수용액 단독으로 코팅하였을 때 결합력이 상당히 강한 박막을 형성하나, 유동점이 890℃이므로 그 이상 온도에서 사용이 불가능하다는 단점이 있으며, 이를 보완하기 위해 알루미나, 실리카, 실리카알루미나, 포타슘, 칼슘, 마그네슘, 붕소, 및/또는 리튬 화합물 등 무기화합물을 혼합하여 내열성을 확보할 수 있다.For example, when coated with potassium silicate solution alone, it forms a thin film having a strong bonding strength, but has a disadvantage in that it cannot be used at a temperature higher than the pour point of 890 ° C. To compensate for this, alumina, silica, silica alumina, potassium Heat resistance can be ensured by mixing inorganic compounds such as calcium, magnesium, boron, and / or lithium compounds.
본 발명에 따르면, 상기 수용액내 알칼리금속/토금속 실리케이트 및 무기화합물의 총 농도는 1∼40중량%가 바람직한데, 1중량% 미만이면 차단막 역할을 할 수 있는 두께의 막을 형성하기에 바람직하지 않으며, 40중량%를 초과하면 점성이 너무 커서 균일한 막을 형성하기 어렵다. 또한, 수용액내 무기화합물의 농도는 알칼리금속/토금속 실리케이트 대비 1∼30중량%가 바람직한데, 1중량% 미만이면 첨가 효과가 미미하고, 30중량%를 초과하면 막의 결합력이 약해지는 단점이 있다.According to the present invention, the total concentration of the alkali metal / earth metal silicate and the inorganic compound in the aqueous solution is preferably 1 to 40% by weight, but less than 1% by weight is not preferable to form a film having a thickness to serve as a barrier film. If it exceeds 40% by weight, the viscosity is so large that it is difficult to form a uniform film. In addition, the concentration of the inorganic compound in the aqueous solution is preferably 1 to 30% by weight compared to the alkali metal / earth metal silicate, if less than 1% by weight is the addition effect is insignificant, if it exceeds 30% by weight has a disadvantage of weakening the bond strength of the membrane.
한편, 본 발명에 따른 코팅에 의해 탄화수소를 원료로 열분해 실험을 해 본 결과 95%의 코크 저감 효과를 확인할 수 있었다.On the other hand, as a result of pyrolysis experiment using hydrocarbon as a raw material by the coating according to the present invention was confirmed that the coke reduction effect of 95%.
이하 실시예를 통하여 본 발명을 좀 더 구체적으로 살펴보지만, 하기 예에 본 발명의 범주가 한정되는 것은 아니다.Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the following examples.
실시예 1Example 1
포타슘실리케이트 수용액의 코팅성능을 확인하기 위해 다음의 실험을 수행하였다. 포타슘실리케이트 농도 10%, 20% 수용액을 각각 제조하여 도 1의 절차에 따라 크롬 25%, 니켈 25%의 합금재질의 금속시편에 코팅을 실시하였다. 금속시편을코팅수용액에 함침하여 10분간 유지한 후, 120℃에서 1시간 건조하고 시간당 200℃로 900℃까지 승온하여 열처리한다. 400∼600℃ 사이에서 결정수 제거에 의한 열처리가 완료된 것을 열중량측정기를 통하여 확인하였다. 서냉후 코팅층의 형상을 전자주사현미경으로 관찰한 결과 균일한 분포를 가지고 접착성이 우수한 막을 형성하였으며, 승온 및 냉각효과에 의한 막의 균열은 없었다. 따라서 포타슘실리케이트 수용액으로 형성한 박막은 기계적강도 및 박막과 금속간 열팽창에 의한 유연성이 충분히 있다는 것을 확인하였다.In order to confirm the coating performance of the potassium silicate aqueous solution, the following experiment was performed. Aqueous solution of potassium silicate concentration of 10% and 20% was prepared, and the coating was applied to a metal specimen of 25% chromium and 25% nickel according to the procedure of FIG. 1. The metal specimen was impregnated with a coating solution and held for 10 minutes, then dried at 120 ° C. for 1 hour and heated to 200 ° C. per hour to 900 ° C. for heat treatment. It was confirmed by thermogravimetry that the heat treatment by the crystal water removal was completed between 400 ~ 600 ℃. After the slow cooling, the shape of the coating layer was observed with an electron scanning microscope. As a result, a film having a uniform distribution and excellent adhesion was formed, and there was no crack in the film due to the temperature rising and cooling effects. Therefore, it was confirmed that the thin film formed from the aqueous solution of potassium silicate had sufficient mechanical strength and flexibility due to thermal expansion between the thin film and the metal.
실시예 2Example 2
포타슘실리케이트 수용액으로 만든 코팅막의 코크 저감 성능을 보기 위해 실시예 1과 같은 방법으로 열분해반응 실험장치 튜브 내부에 코팅을 실시하여 열분해반응 실험을 실시하였다. 포타슘실리케이트 농도 20%의 수용액을 이용하여 도 2의 열분해반응 실험장치 튜브 내부에 채우고 10분 후에 배출한 다음, 120℃에서 1시간 건조한 다음, 가열로 온도를 시간당 200℃로 승온하여 열분해 운전온도 884℃까지 도달시켰다. 이후 스팀 및 납사를 공급하여 하기 표 1과 같은 조건에서 2시간 연속 열분해 운전을 실시했으며, 운전을 완료하고 30분간 질소로 공정 중에 있는 탄화수소를 배출한 후 공기 중 산소를 공급하면서 코크를 연소한다. 이때 일산화탄소 및 이산화탄소를 실시간 분석, 적산하여 코크량을 계산한다. 운전주기에 따른 코팅막의 지속 효과를 평가하기 위해 추가 코팅없이 열분해 운전 및 코크 연소를 반복하였다. 실험결과, 하기 표 2와 같이 코크 축적량은 95% 감소한 것을 확인하였으며, 열분해 및 코크연소 주기가 반복되는 동안에도 코크 저감 효과가 유지되는 것을 확인하였다.In order to see the coke reduction performance of the coating film made of an aqueous solution of potassium silicate, the pyrolysis reaction experiment was performed by coating the inside of the pyrolysis test tube in the same manner as in Example 1. Fill the inside of the pyrolysis reactor tube of FIG. 2 with an aqueous solution of potassium silicate concentration of 20%, discharge after 10 minutes, dry at 120 ° C. for 1 hour, and then raise the furnace temperature to 200 ° C. per hour. It was reached to ℃. Thereafter, steam and naphtha were supplied to carry out the pyrolysis operation for 2 hours under the conditions shown in Table 1 below, and after the operation was completed, the hydrocarbons in the process were discharged with nitrogen for 30 minutes, and the coke was supplied while supplying oxygen in the air. At this time, the amount of coke is calculated by analyzing and integrating carbon monoxide and carbon dioxide in real time. The pyrolysis operation and coke combustion were repeated without additional coating to evaluate the sustained effect of the coating over the cycle of operation. As a result, it was confirmed that the coke accumulation amount was reduced by 95% as shown in Table 2 below, and the coke reduction effect was maintained even during repeated pyrolysis and coke combustion cycles.
실시예 3Example 3
포타슘실리케이트 단독 코팅의 경우 문제가 될 수 있는 900℃ 이상 고온 열적 안정성을 확보하기 위해 포타슘실리케이트와 콜로이드실리카를 혼합 코팅하는 실험을 수행하였고, 코크저감 성능을 확인하였다. 포타슘실리케이트 20%의 수용액에 콜로이드실리카(Ludox SK, DUPONT)를 5%, 10% 및 20%씩 혼합하여 상기 실시예 1과 동일한 방법으로 코팅하여 전자주사현미경으로 관찰한 결과, 균일하고 견고한 막이 형성된 것을 확인하였다. 코팅층의 열적 안정성을 검증하기 위해 1000℃에서 60시간 유지한 후 서냉하여 코팅층을 분석한 결과, 실리카층이 잔존하고 있음을 확인하였다.In the case of coating the potassium silicate alone, experiments were performed by mixing and coating the potassium silicate and the colloidal silica in order to secure thermal stability at a temperature higher than 900 ° C., and the coke reduction performance was confirmed. 5%, 10%, and 20% of colloidal silica (Ludox SK, DUPONT) was mixed in 20% aqueous solution of potassium silicate, and coated in the same manner as in Example 1, and observed with an electron scanning microscope. It was confirmed. In order to verify the thermal stability of the coating layer was maintained for 60 hours at 1000 ℃ after slow cooling to analyze the coating layer, it was confirmed that the silica layer remains.
포타슘실리케이트 수용액내 콜로이드실리카 20%를 혼합한 수용액으로 코팅한 시편을 에탄을 원료로 하기 표 3의 운전조건으로 열분해 실험한 후 전자주사현미경으로 형상을 관찰한 결과, 코팅하지 않은 시편 위에 코크가 축적된 반면 코팅한 시편 위에는 코크축적이 관찰되지 않았다. 포타슘실리케이트 단독 코팅의 경우 900℃ 이상에서 문제가 될 수 있는 열적 안정성을 콜로이드실리카를 혼합함으로써 코크저감 성능을 유지하면서 보완할 수 있었다.Pyrolysis of the specimen coated with 20% colloidal silica in aqueous solution of potassium silicate was carried out using ethane as a raw material, and the shape was observed under an electron scanning microscope. On the other hand, no coke accumulation was observed on the coated specimens. In the case of potassium silicate coating alone, the thermal stability, which may be a problem at 900 ° C. or more, was compensated by mixing colloidal silica while maintaining the coke reduction performance.
전술한 바와 같이, 본 발명의 코팅방법은 탄화수소 열분해 반응기 튜브 내벽에 금속산화 및 코크 생성의 촉매작용을 차단하기 위해 균일한 코팅막을 형성할 수 있고, 형성된 막이 유체흐름의 침식과정에서 기계적 강도를 유지할 수 있으며, 고온에서 열화되지 않고 안정성을 확보할 수 있는 효과가 있다.As described above, the coating method of the present invention can form a uniform coating film on the inner wall of the hydrocarbon pyrolysis reactor tube to block the catalysis of metal oxidation and coke formation, and the formed film maintains the mechanical strength during the erosion of the fluid flow. It can be, and does not deteriorate at a high temperature has the effect of ensuring the stability.
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| KR100746583B1 (en) * | 2006-09-05 | 2007-08-06 | 엘지석유화학 주식회사 | Coke removal method for reducing cokes generated in the thermal cracking process of hydrocarbon |
| WO2014031520A1 (en) * | 2012-08-21 | 2014-02-27 | Uop Llc | Methane conversion apparatus and process using a supersonic flow reactor |
| US9707530B2 (en) | 2012-08-21 | 2017-07-18 | Uop Llc | Methane conversion apparatus and process using a supersonic flow reactor |
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| JPS57140643A (en) * | 1981-02-25 | 1982-08-31 | Kubota Ltd | Coated pipe for reactor subjected to pyrolysis and reforming of hydrocarbon |
| US5208069A (en) * | 1991-10-28 | 1993-05-04 | Istituto Guido Donegani S.P.A. | Method for passivating the inner surface by deposition of a ceramic coating of an apparatus subject to coking, apparatus prepared thereby, and method of utilizing apparatus prepared thereby |
| US5565087A (en) * | 1995-03-23 | 1996-10-15 | Phillips Petroleum Company | Method for providing a tube having coke formation and carbon monoxide inhibiting properties when used for the thermal cracking of hydrocarbons |
| US5807616A (en) * | 1995-04-24 | 1998-09-15 | Corning Incorporated | Thermal cracking process and furnace elements |
| JP3254122B2 (en) * | 1996-02-08 | 2002-02-04 | 出光石油化学株式会社 | Hydrocarbon pyrolysis tube |
| KR100338361B1 (en) * | 2000-01-28 | 2002-05-30 | 유승렬 | On-line coating method for retarding coke on the internal wall of hydrocarbon pyrolysis reactor tube |
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| KR100746583B1 (en) * | 2006-09-05 | 2007-08-06 | 엘지석유화학 주식회사 | Coke removal method for reducing cokes generated in the thermal cracking process of hydrocarbon |
| WO2014031520A1 (en) * | 2012-08-21 | 2014-02-27 | Uop Llc | Methane conversion apparatus and process using a supersonic flow reactor |
| US9707530B2 (en) | 2012-08-21 | 2017-07-18 | Uop Llc | Methane conversion apparatus and process using a supersonic flow reactor |
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