RU2142333C1 - Reactor for liquid phase catalytic hydrogenation of vegetable oils and fats - Google Patents

Abstract

FIELD: modification of reactors in food-processing industry. SUBSTANCE: reactor includes closed remote loop consisting of uptake and downtake lines (pipes, columns). Uptake line has spiral built in it. Lower part of loop has pipe unions for inlet of raw material, catalyst and gas. Pipe union is used for partial or full discharge of catalyst when its activity is lost. Line is connected tangentially with separator having taper bottom which changes to downtake line. Settler located inside separator has pipe union in its upper portion for escape of finished product and holes for communication of settler with separator. Excessive gas is discharge to atmosphere through reflux condenser and pipe union; it may be returned to process at replenishment of fresh gas. EFFECT: increased productivity and enhanced efficiency due to smooth distribution of concentration of catalyst and high-dispersed reaction mass over entire height and volume of reaction zone; reduced consumption of catalyst and hydrogen; enhanced selectivity of process; increased yield of commodity product; reduced power requirements and metal usage; simplified construction due to introducing spiral in uptake line. 2 cl, 1 dwg, 1 tbl, 9 ex

Description

 The invention relates to the improvement of reactors for carrying out processes of continuous and periodic liquid-phase catalytic hydrogenation of vegetable oils and fats in the food industry.

 Liquid phase hydrogenation is carried out by sparging hydrogen through a liquid reaction mass. The catalyst, crushed to a certain size, is suspended in the reaction mass, separated from the hydrogenate during subsequent filtration.

It is known that the hydrogenation of fats can be carried out in periodically operating autoclaves or in a continuously operating system consisting of a cascade including at least three autoclaves with a volume of more than 12 m ³ each [1,3-5]. The principle of their work is the same. With continuous mechanical stirring, an operational amount of fat brought to a temperature of 180-260 ^° C. and a catalyst suspension are loaded or continuously dosed. Hydrogen is supplied from below through bubblers with a large excess. Typically, these reactors operate in full mixing mode. The completion of the process is judged by the analysis of the reaction mass. The spent catalyst is filtered off on filter presses with the breakthrough of the smallest particles into a marketable product.

 These schemes have a number of drawbacks: a very low and heterogeneous degree and intensity of mixing of the reaction masses, low selectivities, yields on target products, productivity; low removal of marketable product per unit volume of the autoclave; cumbersome equipment and high energy consumption lead not only to significant economic costs, but also the complexity of their operation.

Similar schemes for the hydrogenation of vegetable oils to salomas are currently working at Moscow World Combine OJSC [2] and other domestic enterprises. At the same time, the main technological equipment used is autoclaves of imported production (Blau-Knox, USA). The cascade includes four autoclaves, each with a volume of 12 m ³ . Mechanical stirring - turbine mixers. The process temperature of 200-260 ^o C is supported by the supply of high pressure steam to the coils built into the autoclave’s bottom (bottom). Pressure - not more than 3 kgf / cm ² , the feed rate of the oil catalytic suspension 3-5 t / h during hydrogenation of sunflower oil. The concentration of the catalyst at the indicated costs is 0.5%. Through the bubblers located at the bottom of the autoclave, the hydrogen flow rate is 600-1000 m ³ / h (stoichiometry 55 m ³ / t salomas). Consumption of nickel on kieselguhr catalyst (nickel content less than its 45%) - 0.8 kg / 1 tonne salomas hydrogen 78 m ³ / t 1 salomas. Often the process leaves the regime, which leads to significant deviations from the requirements of the technical specifications for the quality of edible salomas, as well as low selectivity and yields for the target products.

 Due to ineffective hydrodynamic conditions, heterogeneity of the catalyst distribution over the height and volume of autoclaves, all of the above disadvantages are also inherent in these schemes.

Close to the proposed invention in technical essence is the well-known technology for the production of technical salomas with a high titer, in particular for the production of stearin. Hydrogenation of oil is carried out under higher pressure (25 atm) in the apparatus of columned mud [1]. The hydrogenation plant consists of four series-connected columns (ascending lines) mounted at the same level. The upper part of the previous column is connected to the lower part of the next using an overflow pipe. The top of the last column is connected to the separator. The height of each column is 10 m, the inner diameter is 0.4 m, the volume of each column is 1.2 m ³ . The lower part of each column is equipped with internal coils for heating with 30 atm steam, a bubbler for supplying hydrogen and pipes for connecting overflow pipes.

The process of hydrogenation of refined oil to salomas is carried out according to a continuous scheme in the presence of a 5% catalyst suspension under a pressure of up to 25 atm and a temperature of up to 260 ^o C. With metering pumps, the oil and suspension of the catalyst, and hydrogen are supplied to the mixer by a compressor. From the mixer, the reaction mass (oil, catalyst suspension, hydrogen) enters the lower part of the first column through a connecting pipe. Sequentially passes through all four columns and enters the separator, where excess hydrogen is separated, and the salomas are sent for filtration from the catalyst. To mix the reaction mass from below, an additional additional part of hydrogen is constantly supplied via a bubbler to each column.

The temperature and pressure in the columns during the passage of the reaction mass through them is maintained in the following ranges: in the first column 205-220 ^o C (7 atm), in the second 220-230 ^o C (6.5 atm), in the third 230-260 ^o C (6 atm) and in the fourth 235-250 ^o C (5.5 atm).

During the hydrogenation of sunflower oil, the plant capacity is up to 25 tons / day. Catalyst consumption 0.9-1.0 kg / t salomas, average hydrogen consumption 74 m ³ / t salomas (stoichiometry 55 m ³ / t salomas). The acid number of salomas is 2.3-3.1. In the resulting salomas, the content of isooleic acids is reduced, hydrogenation proceeds with a significant deviation from absolute selectivity. Getting food salomas is not possible. Therefore, this installation is used only for the production of technical salomas, mainly intended for the production of technical stearin.

 The disadvantages of this prototype also include a large energy and metal consumption, limited productivity, lack of selectivity, overspending of raw materials.

 The main causes of the disadvantages are: uneven and heterogeneous distribution of the catalyst and reaction mass over the heights and volume of the columns, the length of the reaction mass in the reaction zone, local overheating, low driving force of circulation, low dispersion of hydrogen.

 The purpose of the invention is to increase the productivity and efficiency of the device due to the uniform distribution of the concentration of catalyst and highly dispersed reaction mass over the entire height and volume of the reaction zone, reducing the consumption of catalyst and hydrogen, increasing the selectivity of the process and the yield of commercial food product, reducing the energy and metal consumption of the reactor, simplifying the design .

 This goal is achieved due to the fact that a spiral (coil) is introduced into the ascending line of the reactor [6] on the same axis along the entire height and volume.

 The drawing shows a reactor, General view.

 The reactor has a closed remote loop, consisting of ascending 2 and descending 1 lines (pipes, columns). In this case, a spiral 17 is coaxially integrated into the ascending line. At the bottom of the circuit, fittings 3-5 are placed for introducing raw materials, catalyst, gas. The fitting 6 serves to partially or completely discharge the catalyst in case of loss of its activity. Line 2 is connected tangentially to the separator 8, having a conical bottom 9, passing into a downward line 1. Inside the separator there is a sump 10, in the upper part of which there is a fitting 11 for outputting the finished product, holes 12 for connecting the internal volume of the sump with the separator.

The lower part of the sump ends with the inlet pipe 13 with the end 14, the axis of which is an angle of 45-60 ^o at a distance of 3-5 mm from the conical wall of the bottom of the separator 6.

 The excess gas through the reflux condenser 15 and the nozzle 16 is discharged into the atmosphere and can be returned to the process with the recharge of fresh gas.

 The operation of the reactor.

 With the dosing pumps, the oil enters through the nozzle 4, the oil suspension of the catalyst through the nozzle 3. When a calculated amount of hydrogen (sparging) is supplied through the nozzle 5 in the ascending line, a highly dispersed turbulent-translational movement of the reaction mass in the external circulation loop occurs. The homogeneity of the resulting highly dispersed state of the reaction mass is maintained along the entire height of the ascending line 2 and enters the upper part of the separator 8, where the excess gas is separated from the liquid and removed through the refrigerator 15 and the fitting 16 from the reactor. The main part of the liquid mass through the downward pipe 1 goes to the circulation, and part through the pipe 13 enters the sump 10, where the sediment has passed through the pipe 13 of the catalyst, it is returned to the process and the finished product is taken through the fitting 11.

 Hydrogenation of sunflower oil to edible salomas.

 Example 1

The reactor of the described construction (see drawing) is made of glass. Ascending and descending lines, the separator is heated through the shirt. The process temperature (180-200 ^o C) is maintained by a thermostat. The height of the lines is 3.0 m, the internal diameter of the lines is 0.02 m, the reactor volume is 0.0018 m ³ . No spiral is entered into the ascending line. Pumps dispensers through the nozzles 3, 4 continuously dosed oil and oil suspension of the catalyst (nickel on kieselguhr) with a total flow rate of 4.2 kg / h. The total concentration of catalyst in this solution is 0.5%. The hydrogen supply through nozzle 5 was 2 times higher than the stoichiometric (165 l / h), while the excess hydrogen with the addition of fresh was returned to the process. Atmospheric pressure. The distribution of the highly dispersed reaction mass along the height and volume of the ascending line is uneven (small bubbles from the dispersion nozzle along the height of the reaction zone are rapidly enlarged with transition to jets and hydroblows, the specific surface area decreases sharply).

The quality of the food salomas obtained (in parentheses is the norm according to TU 10-04-02-66-90). Melting point -29.2 (31-36) ^o C; hardness - 90 (160-320) g / cm; acidity - 1.5 (not more than 1.0 mg KOH / g); the selectivity of the process is 75%; the yield of the target product is 60%; hydrogen consumption - 90 l / kg of salomas (stoichiometry of 55 l / kg); catalyst consumption - 0.8 g / kg of salomas.

 Example 2

 It is made analogously to example 1, but a spiral of stainless steel wire with a diameter of 2 mm is introduced coaxially to the entire height in an ascending line. The distribution of the reaction mass is homogeneous (enlargement of the bubbles no more than 5% at the top of the ascending line).

 The quality results of the resulting edible salomas are shown in the table.

 Examples 3-6 are performed similarly to examples 1-2. The height of the spiral (ascending line) and the dosage of oil and catalyst suspension were doubled. Quality results are tabulated.

Examples 7-8 are performed similarly to examples 1-2. The pilot industrial reactor is made of stainless steel and tested under industrial conditions at the Moscow Fat Factory. The height of the ascending line is 18 meters. The inner diameter of 0.1 m, the volume of the reactor is 0.3 m ³ . The temperature was maintained by supplying high pressure steam to the shirts. Hydrogen pressure 0.1-0.2 atm. The dosage of the oil catalytic suspension is 2000 kg / h.

 The results are shown in the table.

 From the results of the above examples, it is easy to see that the introduction of a spiral along the entire height of the ascending line makes it possible to achieve a uniform and homogeneous distribution of the reaction mass, high selectivities and yields for the target products, significantly increase productivity, reduce consumption coefficients for raw materials, and obtain high-quality food salomas with low acidity. The pick-up of the target product per unit volume of the reactor is increased tens of times, and the mass and energy costs in the manufacture and operation of equipment are many times reduced. It is possible to manufacture the reactor on its own mechanical repair base of the enterprise. The proposed reactor design is recommended for implementation.

Literature
1. B.N. Tyutyunnikov and others. "Technology of processing of fats", publishing house "Food Industry", M., 1970, p. 207.

 2. "Permanent technological regulations for the production of salomas." Moscow Fat Factory. Approved Deputy. Chairman of the Board of the Union of Artists "Soyuzmargarinprom" dated June 26, 1991, Moscow.

 3. R. R. Allen "Hydrogenation: principles and catalysts. A short course on the production and quality control of fats and oils in the hydrogenation process." 1966.

 4. R. R. Allen and D.I. Covey "Journal of the American Society of Chemist Wen". J.A.O.M.H., 47, p. 494-496, 1970.

 5. "A comprehensive study on the technology of hydrogenation of salomas for food purposes and the main directions and trends to improve their quality." Cooperative "Maslozhirttehnika", Moscow, Volume 1, 2, 1990.

 6. Copyright certificate 1686746 (USSR), 1989, "Liquid-phase hydrogenation reactor", A.T. Soldatenko and others.

Claims (1)

A liquid-phase catalytic hydrogenation reactor for vegetable oils and fats, containing a closed external circuit, which includes ascending and descending lines, containing pipes, columns, a separator with a conical bottom and a tangential inlet of the reaction mixture, equipped with a sump with a fitting located in its upper part for the outlet of the finished product, and the bottom nozzle to enter the product and fixed at an angle of 45-60 ^o at a distance of 3-5 mm from the bottom wall of the cone, characterized in that coaxially to the entire height of the ascending inii reactor installed spiral.

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