Design and Production Practice of the New Designed Multi-tube Film Sulfonation Reactor Huiben Zhang (Nanjing Kani Co. Ltd)

I.ForewordAt present, most of the multi-tube film sulfonation reactors in use nationally were designed by Ballestra Societ Per Azioni, or are replicas manufactured by this company. After many years of practice, we found some disadvantages of the design per se1.The organic flow in each reaction tube is adjusted by gasket, which will result in low adjustment accuracy and long adjustment time. As the flow in reaction tubes increases, the adjustment becomes harder and harder. When the reaction tubes are corroded after prolonged use, they cannot even be adjusted properly.2.Also, the organic flow cannot be controlled; thus, it might affect the product quality. Decision on whether the errors fall within the acceptable range can be made only if each organic flow is demarcated. Failure to do so will adversely affect the manufacturing procedure. Lock ring is used as the seal between the sulfonation reactors organic raw material feed chamber and the cooling water jacket. The jacket cannot withstand high water pressure and thus requires the cooling water to go back to its normal condition. However, even though the above condition is met, the cooling water may still leak to the organic raw material feed chamber and result in emulsification of raw materials which cannot be sulfonated anymore.3.When SO3 enters into the sulfonation, it will contact and corrode the sulfonation reactor heads gland nuts, gaskets, nozzles, and other parts. It is difficult to uninstall, assemble, or adjust when the thread of gland nuts was corroded. Recognizing the above problems with Ballestras sulfonation reactors, we, a team of experts at Kani Chemical Co. Ltd., designed a new type of multi-tubes sulfonation reactor, which is more reasonable for its structure, convenience in use, and better product quality. Additionally, the way it is designed makes it robust enough to withstand reaction with various raw materials for sulfonation or sulfation, even after prolonged use.

II.The Design IdeasThe SO3 sulfonation and sulfation is a diffusion-based extremely fast reaction, which will produce huge heat, while the product has a high thermo-sensitivity. Therefore, the film sulfonation reactor is required to effectively control the diffusion rate of SO3. At the beginning of sulfonation reaction (about 0 ~ 1.5meters), the unit conversion rate of organic materials should have a large cooling area, so that the Moore ratio between SO3 and organic material can be accurately controlled. The organic material flow should be accurately controlled in each tube so that the error of organic materials among tubes can be less than 1.5%. The thickness of the organic film around the reaction tube should be consistent, for example, for a reaction tube with which inner diameter of 25mm and length of 6 meters, the deviation between the upper and lower concentricity should be less than 2mm, while any length of each reaction tube should be vertical. It is required that the cooling heat transfer coefficient is improved, so that the reaction temperature can be effectively controlled. According to the requirements above, we designed a new type of multi-tube film sulfonation reactor, which works effectively in practice.

III.The Feature of the New Multi-tube Film Sulfonation Reactor1.The organic feed of each tube needs to be controlled by high-precision rotameter, with 1.5% control accuracy regardless of the changes of tube numbers. The high-precision rotameter needs to be easy to adjust. With the increase of number of the tubes, this advantage is more obvious. Meanwhile, in the process of production, the organic flow can be observed anytime, which indirectly helps understand whether there is any coking phenomenon in any of the reaction tube.2.The sulfonation reactor utilizes the balance wind, which can be adjusted by the external piping and valves, or by changing the diameters of each SO3 nozzles (this method is limited to the process which can offer high gas concentration, such as liquid SO3 evaporation process) to reduce the diameters of the SO3 nozzles, so that the input air gap area increases between the SO3 nozzle diameter and nozzle. As a result, the ratio between SO3 and balance wind decreases. The SO3 nozzle plugs into the organic film directly from the head of sulfonation reactor. SO3 and the balance wind pass the concentric circle together through organic film (The channel of balance wind is cyclic because the structure needs to ensure a consistent concentricity between the concentric circle.) and eject out together.Utilizing the balance wind can help increase SO3 concentration. At the beginning of the reaction, given the same conversion ratio, there is a longer reaction interval by using balance wind than that of not using it. Therefore, given the same reaction heat, using the balance wind can help increase the cooling area and better control the peak value of reaction temperature. This was approved in practice.In addition, SO3 nozzle directly plugs into the organic film, which avoids the contact with the nut, washer and nozzles; meanwhile, the balance wind also isolates the SO3 when it goes through pressed nuts and nozzles, so that corrosion is prevented. Without corrosion, it is very easy to uninstall and assemble. Due to the use of balance wind, which improves the SO3 gas concentration at the entrance, it is more productive when LABSA is produced. For example, given the standard condition, LAB is fed into the reaction tube, to reach 0.58kg/mm, it costs 1450M3 dry air to produce one ton of LABSA. However, if our sulfonation reactor is used, 19ton/day of SA can be produced, with Roots wind of 19.3m3/min. With the increase of production in each single tube, the pressure in sulfonation reactor also increases, which reach 0.0350.04mp, compared to Ballestras reactor which can reach 0.0250.03mp.3.In order to strengthen the cooling effect, instead of using the baffle with a 1/4 gap (such kind of baffle can cause death of flow rate, which in turn will affect the cooling effect), we adopted the circle baffle. The baffle hole is greater than the reaction tube diameter; if a three-clawed or four-clawed plate is set in the between of reaction tube and baffle, it will improve the heat transfer coefficients, the cooling effect, as well as the impact of water flow towards the reaction tube.4.Since organic raw material is fed individually into each reaction tube, it remains completely isolated with the cooling water system. Therefore, the possibility of cooling water leaking into organic raw materials is greatly minimized. The cooling water at the head of sulfonation reactor can go back with pressure, which can go directly to the cooling water system of the sulfonation plant.

IV.Design Parameters1.The reaction tube internal diameter is 25mm, outer diameter is 29mm, internal diameter deviation is 25mm0.05, internal diameter ovality < 0.01mm. The finish of the inner tube of the reactor is greater than V8the length of the tube is 6mmaterial316L. The internal diameter of Ballestra is 25.4mm.2.The designed tube air speed is 43m/s, mass transfer coefficient: kg=1.310-1m/s3.The initial film thickness is 0.3mm, exports of the film thickness is 3mm. The residence time is about 35ms.4.The pressure of the entrance of the cooling water tube is 0.3Mp. The heat transfer coefficient is kw20KJ/m2h-.5.Balance wind: SO3 ventilation area equals 0.4:1.

V.Production PracticeThe new multi-tube film sulfonation reactor has been used in many sulfonated field, such as the sulfation of fatty alcohol and ether, the acidification of the fatty acids. In the process of Alkylbenzene sulfonation, it improves the productivity, reduces the energy consumption, as well as improves the product quality.The index is: actives96.5% (i.e.: Jiale Nanjing Co., Ltd.) Free oil1.5% Inorganic acid1.3%Color25klettIf the SO3 filter adopts the provisioning shower defogger, the inorganic acid can be dropped to less than 1%, actives up to more than 97%. Produce K12 powderThe index is: Actives94%i.e.: Jinling Nanjing Co., Ltd. Inorganic salts1.2% No sulfonate1.0% Color10klettIn the sulfonation of the fatty acids to the formic acids, the Moore rate between SO3 and the formic acids is 1.15 ~ 1.2:1, the temperature at the exit of the sulfonation reactor is 60, aging temperature is between 8590, the conversion rate of fatty acids to formic acids is greater than 96%.

VI.Conclusion1.The new multi-tube film sulfonation reactor is improved in many ways. Not only it can meet various requirements for producing sulfonation and sulfation, it can also improve the quantity and quality of the product, and save the costs compared to the already existing sulfonation reactor in the market.2.The new multi-tube sulfonation reactor can be applied to practice effectively. With the increase of the number of tubes, it does not affect the accuracy of raw material quantity, or the product quality. The product quality is better from multi-tube sulfonation reactorthe more tube number, the better the quantity. The new multi-tube sulfonation reactor is easy to use and can provide stable product quality. Compared with other sulfonated reactors, it can improve the product quantity by 45% (limited to LABSA). It can also improve yield of other products like ether and the fat sulfated quantity by 5 to10%.

Auto Control System

Take an example of the configuration of 5 ton/hour sulfonation equipment. Personal Computer (PC) and Programmable Logic Controllers (PLC) based control system consists of two Computer Operator Stations, one set of PLC Controller Station, four MCC control cabinet, and one high-voltage power supply (HVPS) control cabinet, etc. Using SIEMENS Win CC 7.0 (Windows Control Center) as the human-machine interface software, the Computer Operator Station integrating with monitoring software which is developed by our company can display and control the following procedures through computer screen: the sulfonation dynamic process, the input of technology parameters, system status monitoring, error alarm reminding, historic data saving, and report printing, etc. SIEMENS S7-300 being the main system structure, PLC Control Station is responsible for the control of sulfonation equipment. 3152PN/DP being the central processing unit (CPU), it monitors and transmits data through internet. The Computer Operator Station is mainly responsible for monitoring the status of the sulfonation equipment. The main functions of Computer Operation Station are as follows:

1.Display the sulfonation equipment process,2.Display the real-time system pressure, temperature, and density value collected by the instrument,3.Set and adjust parameters of proportional-integral-derivative (PID) control loop,4.Display the running status and alarm status of each motor as well as their start-stop operation,5.Display and record the alarm information in the production process,6.Display and record parameters of running system7.Record, archive, and print the feedback value curve from instrument.

Temperature and pressure parameters of each collected point in the control system are tested and displayed by the instrument utilizing bi-metal thermometers and pressure gauges. Thermal resistance and pressure sensors are used to test temperature and pressure in the testing locations of measuring main temperature, pressure, and high temperature, through cable access PLC control module in the combined MCC cabinet.

The electric control configures four sets of modular MCC cabinets. Each cabinet is configured by using a DS cabinet type, 4,000mm*2,000mm*500mm (width*height*depth), a RAL7035 computer-based white color, and an IP54 protection level. The cabinet is equipped with a filtered ventilation system and light, which can protect the component service life efficiently. The internal of the cabinet integrates PLC control station with sulfonation equipment control unit.In the control loop, Roots Blower adopts soft starter. Frequency Converter adopts VCON NSL series high-performance Frequency Converter from Finland. Control units adopt domestic products with a brand name of CHNT or DELIXI, with reliable quality and performance. The low-capacity motor adopts a new type of NS2 series power machine protection circuit breaker, which can protect the motor reliably and efficiently. The advantages of the above configuration include: operating staff can master the process operation quickly through process images, the system can later gradually increase the automatic control units of sulfonation system as well as extend the control units which is beyond sulfonation board.