Replacenode oxide catalytic element for the conversion of ammonia

 

(57) Abstract:

The invention relates to a cellular replacenode oxide catalytic elements for the conversion of ammonia and can be used mainly in the production of nitrogen and hydrocyanic acid, and has synthesis, for example, as the catalyst of the second stage located behind the catalyst for the first stage (along the strip), made in the form of package the platinum mesh. A catalytic element for the conversion of ammonia is made in the form of a layer of the individual prisms are equipped with cellular channels, each of which has an equivalent diameter of its base and height, respectively 4100 and 275 equivalent diameters cellular channel, in which the prisms are set relative to each other with clearances, components from 0.20 to 0.55 equivalent diameters cell channel. As a result of use of the invention ensures longer service life and efficiency of the catalytic element. 3 C.p. f-crystals, 8 ill.

The technical field to which the invention relates

The invention relates to a cellular replacenode oxide catalytic elements for the conversion of ammonia and can be used mainly in proizvoditeli, located behind the catalyst for the first stage (along the strip), made in the form of package the platinum mesh.

Art

Known replacenode oxide catalytic element for the conversion of ammonia in the form of a layer of the individual prisms having cell channels which are connected side edges without gaps (EP 0260704, 1988). /Prism - a polyhedron, two faces (bases) - equal polygons located in parallel planes, and the other face (side) - parallelograms - Soviet encyclopedic dictionary, M.: Soviet encyclopedia, 1987, S. 1059/. The disadvantage of this catalytic element is small thermal durability and service life.

The closest in technical essence to the present invention is replacenode oxide catalytic element for the conversion of ammonia in the form of a layer of the individual prisms are equipped with cellular channels and connected side edges without gaps. Each of the prisms has an equivalent diameter of its base and height, respectively 4-100 and 2-75 equivalent diameters cell channel (EN, 2128081, 1999). /Equivalent diameter is a well - known concept in hydrodynamics, it is four squares perpendicular to behold eskay technology", M.: Chemistry, 1973, S. 37/.

The main drawback of the catalytic element closest analogue is a low life and a lack of efficiency. This disadvantage is due to the fact that at the starts and stops of the reactor ammonia conversion is sudden heating or cooling of the walls of the reactor and catalytic prisms, causing changes of their sizes. Placing prisms in the layer without gaps between their side faces is the reason that when the cell catalyst causes "swelling" of the layer of prisms and their partial destruction. "Swelling" of the layer of prisms catalytic element for ammonia conversion of the second stage can lead to the emergence of free volume between the catalytic element and the catalyst of the first stage in the form of package the platinum mesh. This fact and the partial destruction of the prisms replacenode oxide catalytic element lead to lower degree of conversion of ammonia to the target product (NO in the production of nitric acid and has synthesis and HCN in the production of hydrocyanic acid).

The invention

The technical problem to be solved by the present invention is directed, is to create life and work efficiency.

This technical problem is achieved by the fact that in replacenode oxide catalytic element for the conversion of ammonia in the form of a layer of the individual prisms are equipped with cellular channels, each of which has an equivalent diameter of its base and height, respectively 4-100 and 2-75 equivalent diameters cell channel, adjacent prisms mounted relative to each other with gaps between the side faces components from 0.20 to 0.55 equivalent diameters cell channel. The base of the prism has the shape of three-, or four-, or hexagon. The quadrilateral can be a rectangle or square. In the case where the prisms have a Foundation in the form of rectangles, including squares, prisms are placed in such a way that they form parallel rows in mutually perpendicular directions.

The main distinguishing features of the cell replacenode oxide catalytic element for the conversion of ammonia in accordance with the present invention consist in the fact that neighboring prisms mounted relative to each other with gaps between the side faces components from 0,20 0,55 equivalent diameters cell channel.

Additional distinctive PR is astipalea, and rectangles, including squares, and created from them parallel rows formed in two mutually perpendicular directions.

In Fig.1 is placed in the reactor vessel replacenode oxide catalytic element for the conversion of ammonia, a side view, in longitudinal section; Fig.2A is depicted in the top on this catalytic element made of prisms, with the base, respectively, three-, or four-, or hexagon, Fig.3A-depicts a perspective view of three separate prisms, having a basis of three-, or four, or hexagon, Fig.4 practically repeats Fig.1 with the difference that the catalytic element is depicted package the platinum catalytic nets, which is the catalyst for the first stage.

Replacenode catalytic element in accordance with the present invention placed in the reactor vessel 1 on the supporting device 2 and is made in the form of a layer 3 of spaced parallel rows of prisms or 4 or 5 or 6, which are mounted relative to each other with gaps . Prism provided through mobile channels 7 and can be the basis of any triangle prism 4 or quadrilateral (primogel, the particular squares 5 created from them parallel rows formed in two mutually perpendicular directions (Fig.2B). The equivalent diameter of the base of the prism Di (where i=3, 4, 6), its height H and the gap between the prisms, respectively 4-100, 2-75, and 0.20-55 equivalent diameters cell channel 7, which is calculated by the following formula, namely: d = 4S/P, where S and P - area and perimeter of the cross section of the cellular channel. In the case of replacenode oxide catalytic element as a catalyst for the conversion of ammonia to the second stage on top of it is the platinum package nets 8 (see Fig.4), which is the catalyst for the first stage.

Replacenode oxide catalytic element for the conversion of ammonia works as follows. A gas mixture containing ammonia and oxygen-containing gas enters the reactor vessel 1 and moving it downwards (see arrow in Fig.1), passes through cell channels 7 prisms or 4 or 5 or 6 catalytic element 3. On the inner surfaces of the cell channels 7 is the catalytic conversion of ammonia to the target product.

The target products are as follows: in the production of nitric acid and hydroxylamine, containing the target product, through supporting device 2 out of the reactor 1. If the catalytic element is used as a catalyst for the conversion of ammonia to the second stage, i.e. when the first step along the gas mixture is package the platinum catalytic nets, the catalytic element works as described above but with the difference that the source gas mixture passes through the platinum package nets 8 (see Fig.4).

The test results replacenode oxide catalytic element for the conversion of ammonia according to the present invention, as well as other catalytic elements, in particular the catalytic element closest analogue is presented below.

Example 1 (catalytic element according to the present invention). Tests replacenode oxide catalytic element for the conversion of ammonia is carried out in a domestic installation for the production of nitric acid with a capacity of 355 t NGO3/day, with the reactor conversion of ammonia with a working diameter 1650 mm On the supporting device of the reactor placed replacenode oxide catalytic element in the form of a layer from the 401 individual prisms with quadrivalent the cell diameter of the channel 5 mm wall Thickness between adjacent cell channels - 2 mm, the height of the prism is 50 mm, the composition of the cell replacenode oxide catalyst, wt.%: Fe2ABOUT375; Al2ABOUT320; aluminosilicates 5. Prism is installed in parallel rows in two mutually perpendicular directions and positioned relative to each other with gaps equal to 0.20, the equivalent diameter of the cell channel. Replacenode oxide catalytic element is a catalyst for the conversion of ammonia in the second step (in the direction of gas flow). On this layer is the catalyst for ammonia conversion the first step is made in the form of a package of eight woven platinum mesh composition, wt.%: Pt 81; Pd 15; Rh 3,5; EN 0,5. The thickness of the wire in the grid - 0,092 mm, number of holes 1 cm2- 1024. Produce a reactor startup to work with the following stationary process parameters:

the flow rate of the ammonia-air mixture (ABC) in the reactor 64000 nm3/h;

the concentration of ammonia in the mixture to 10.0 vol.%;

- temperature of the ABC and nitrous gas, formed in a two-stage catalyst, respectively 200 and 900oC. the Period of operation of the two-stage catalyst amounted to 3000 hours During this period, the average conversion of NH3to NO Yeni installed, that none of all prisms cell replacenode oxide catalyst is not destroyed. The warranty on the catalytic prisms without destroying 1 year.

Example 2 (catalytic element according to the present invention). Everything is the same as in example 1 with the following differences. 382 Individual prisms are placed relative to each other with gaps equal to 0.55 equivalent diameters cell channel. For the period of operation of the two-stage catalyst, the average conversion of NH3to NO accounted for 93.4%. After a period of operation found that none of the prisms cell replacenode oxide catalyst is not destroyed. The warranty on the catalytic prisms without destroying 1 year.

Example 3 (catalytic element according to the present invention). Everything is the same as in example 1 with the following differences. 393 Individual prisms are placed relative to each other with gaps equal to 0.36 equivalent diameters cell channel. For the period of operation of the two-stage catalyst, the average conversion of NH3to NO was 93.5%. After a period of operation found that none of all prisms cell replacenode oxide catalyst h is measures 4 (catalytic element with gaps between the prisms below the lower limit in the claims). Everything is the same as in example 1 with the following differences. 402 Individual prisms are placed relative to each other with gaps equal to 0,18 equivalent diameters cell channel. For the period of operation of the two-stage catalyst, the average conversion of NH3to NO amounted to 91.8%. After a period of operation found that 17.7% of prisms cell replacenode oxide catalyst was destroyed.

Example 5 (catalytic element with gaps between the prisms above the upper limit in the claims). Everything is the same as in example 1 with the following differences. 381 Individual prisms are placed relative to each other with gaps equal 0,57 equivalent diameters cell channel. For the period of operation of the two-stage catalyst, the average conversion of NH3to NO was 92.6%. After a period of operation found that none of all prisms cell replacenode oxide catalyst is not destroyed.

Example 6 (catalytic element closest equivalent). Everything is the same as in example 1 with the following differences. 412 Individual prisms are placed relative to each other without gaps between their side faces. Prism laid in parallel rows, respfile of 91.6%. After a period of operation found that 25.7% of prisms cell replacenode oxide catalyst was destroyed.

From the comparison of the results presented in examples 1-3 (catalytic element according to the present invention), with the results in example 6 (catalytic element closest analogue) shows that the proposed replacenode oxide catalytic element provides a guaranteed longer service life up to 1 year (8760 h), i.e 2.92 times and improving the efficiency of operation in the two-stage catalytic system package the platinum mesh as the first stage - the average degree of conversion of NH3to have NO increased to 91.6% in the catalytic element prototype to 93.5 in the proposed catalytic element (an increase of degree of conversion of NH3to NO 1% corresponds to a reduction of specific consumption of NH3in the manufacture of nitric acid to 3 kg NH3/t NGO3).

A comparison of the data of examples 1-3 (catalytic element according to the present invention) with the results in example 4 (catalytic element with gaps between the prisms below the lower limit in the formula of the invention) shows that the lifetime and efficiency of the catalytic Aleph in the two-stage catalytic system, with the proposed oxide replacenode catalytic element according to the present invention. These shortcomings are explained by the reasons described above (see above description of the shortcomings of the catalytic element closest analogue prototype) as the catalytic element in example 4 approaches the catalytic element prototype in example 6.

From the comparison of the results of examples 1-3 (catalytic element according to the present invention) with the data of example 5 (catalytic element with gaps between the prisms above the upper limit in the formula of the invention) shows that, despite preserved after a period of operation of two-stage catalytic system for the conversion of ammonia integrity of the prisms, the efficiency of cellular oxide replacenode catalyst comprising a two-stage catalytic system in example 5 is lower than the efficiency of the catalytic element according to the present invention (examples 1-3). The average conversion of NH3to NO decreased from 93.5 to 92,6%. This decline is due to the limited number of catalytic prisms and significantly increased bypass of the gas mixture through increased gaps between the individual prisms.

Thus, the present and Niley acids, and has synthesis.

1. Replacenode oxide catalytic element for the conversion of ammonia in the form of a layer of the individual prisms are equipped with cellular channels, each of which has an equivalent diameter of its base and height, respectively 4100 and 275 equivalent diameters cell channel, wherein adjacent prisms mounted relative to each other with gaps between the side faces components from 0.20 to 0.55 equivalent diameters cell channel.

2. The catalytic element according to p. 1, characterized in that the base of the prism has the shape of a three - or four-, or hexagon.

3. The catalytic element according to p. 1, characterized in that the base of the prism has the shape of a rectangle in a rectangle or square.

4. The catalytic element according to p. 3, characterized in that the prism is placed with gaps between the side edges so that they form parallel rows in mutually perpendicular directions.

 

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5 cl, 1 dwg

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