Design and Production Practice of the New Designed Multi-tube Film Sulfonation Reactor

I. Foreword

At present, most of the multi-tube film sulfonation reactors in use nationally were designed by Ballestra Società Per Azioni, or are replicas manufactured by this company. After many years of practice, we found some disadvantages of the design per se：

1. The sulfonation reactor's organic material flow rate in each reaction tube is adjusted with gaskets, the adjustment accuracy is not high, and the adjustment takes a long time; with the increase of the number of sulfonation reactors, the adjustment is particularly difficult. After a long period of use of the sulphonation reactor, even flow cannot be adjusted. During use, due to the inability to understand the organic flux of

each tube, product quality issues arise. Only after standardizing the flow of organic matter in each tube, can we determine whether the error exists within the allowable range, otherwise it will often affect production.

2. Lock ring is used as the seal between the sulfonation reactor’s 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 head’s 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 Ballestra’s sulfonation reactors, we, a team of experts at Qino A.C.E 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 Ideas

The 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 ф25mm 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 Reactor

1. 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 Root’s wind of 19.3m3 /min.

With the increase of production in each single tube, the pressure in sulfonation reactor also increases, which reach 0.035～0.04mp, compared to Ballestra’s reactor which can reach 0.025～0.03mp.

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 Parameters

1. The reaction tube internal diameter is ф25mm, outer diameter is ф29mm, internal diameter deviation is ф25mm±0.05, internal diameter ovality < 0.01mm. The finish of the inner tube of the reactor is greater than V8，the length of the tube is ≤6m，material：316L. The internal diameter of Ballestra is ф25.4mm.

2. The designed tube air speed is 43m/s, mass transfer coefficient: kg=1.3×10-1 m/s

3. 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 Practice

The 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: actives≥96.5% (i.e.: Jiale Nanjing Co., Ltd.)

Free oil≤1.2%

Inorganic acid≤1.2%

Color≤20klett

If 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 powder

The index is: Actives≥94%（i.e.: Jinling Nanjing Co., Ltd.）

Inorganic salts≤1.2%

No sulfonate≤1.0%

Color≤10klett

In the sulfonation of the fatty acid methyl ester, the Moore rate between SO3 and the fatty acids methyl ester is 1.15 ~ 1.2:1, the temperature at the exit of the sulfonation reactor is 60℃, aging temperature is between 85～ 90℃, the conversion rate of fatty acid methyl ester is greater than 96%.

VI. Conclusion

1. 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 reactor，the more tube number, the better the quantity.

3. 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%.