SU997786A1 - Ammonia synthesis reactor - Google Patents

Description

The invention relates to chemical engineering 6blast, and in particular to devices for conducting chemical processes, and can be used in the refining and petrochemical industry for conducting the synthesis of ammonia, methanol and other similar processes, where chemical transformation takes place with the release or absorption of tegsha.

A high pressure reactor is known, consisting of a main vessel,. heat exchanger and. a catalyst box inside the catalyst, through which the double pipes are cooled, the end of each inner pipe located opposite the inlet, is open; In the walls of each inner pipe, holes are made at some distance from the entrance, the outer pipes are open at the ends opposite the inlet holes of the inner pipes, the other ends of the outer pipes are closed til.

Such a reactor design provides a satisfactory temperature in the chemical reaction zone under optimal process conditions. However, it does not allow to maintain the optimum temperature in the entire chemical reaction zone when these conditions change. which leads to a decrease in the yield of the target product .;

The closest in technical essence to the proposed device is a reactor for an AmAtk plant, comprising a housing, a heat exchanger accommodated in it, an ejection cell

10 a box with groups of concentrically mounted tubes, the inner ones of which are of variable diameter in height, and a manifold for supplying gas. Raw material entering

15 internal tubes, passes successively along them and along the annular channel between the G2 tubes.

The disadvantage of this reactor is the low yield of the target product.

20 due to the impossibility of ensuring the optimum temperature in the entire chemical reaction zone under various conditions of the process, since the reactor is designed to create the optimum

25 temperature conditions along the length of the chemical reaction zone only at the nominal values of the process conditions. In this reactor, it is not possible to change the temperature at one of the sites of the chemical reaction zone without changing the temperature at other sites, although such a need arises when changing the conditions of the process. The aim of the invention is to increase the yield of the target product under favorable process conditions. The goal is set to those in the reactor for the synthesis of ammonia, comprising a housing placed in a non-heat exchanger, a catalyst box with groups of concentric tubes, internal of which are of variable diameter in height, and a collector for supplying gas, the inner tube is made variable to increase in the course of gas from the bottom up, and the collector is provided with transverse deaf partitions that form annular channels, to each of which groups of tubes of the same length are connected. The execution of the open tubes and at both ends and the shortening of each subsequent concentric tube with respect to the previous one ensures the formation of annular concentric channels of different lengths along the chemical reaction zone. The change in the rate of movement of the raw material in concentric channels provides for the regulation of the intensity of heat exchange over the regions of the chemical reaction zone, which makes it possible to create optimal temperatures throughout the zone and increase the yield of the target product. The supply of each group of tubes of the same length with a common input of raw materials will allow the raw materials to be adjusted, and hence its speed, in the annular channels independently of each other. This provides the possibility of independent regulation of the heat exchange rate in certain parts of the chemical reaction zone when the conditions of the process change, and, consequently, contributes to an increase in the yield of the target product. The drawing shows the proposed reactor, a longitudinal section. The ammonia synthesis reactor contains a cylindrical body 1 in which catalyst box 2 and heat exchanger 3 are installed. In catalyst bed 4, located in box 2, groups of concentric tubes 5-7 are placed. Outer tubes 5 designed to remove heat from the catalyst bed 4, i.e. from the chemical reaction zone, are open from both stations. In tubes 5, inner tubes 6 and 7 of smaller diameter are concentrically placed, also open at both ends. Moreover, the inner tube 6 is made shorter than the outer tube 5, and the tube .7 is shorter than the tube b. external to it. Tubes 5-7 form the central and annular channels. The inner tubes b are made of variable diameter. All tubes 6 are fixed in tube plate 8 and have a common inlet 9, and tubes 7 are fixed in a tube plate 10 and have a common inlet 11. Inputs 9 and 11 serve for introducing into the reactor the flow of raw materials controlling the intensity of heat exchange between the main flow of raw material and zone of chemical reaction in the catalyst bed 4. Input 12 is designed for supplying the main flow of raw materials in the reactor through the annular space of heat exchanger 3, and Input 13 is for supplying additional cold raw material, mine heat exchanger 3, the so-called cold bypass, output 14 for withdrawal Started product. In the zone of chemical reaction, due to the difference in the length of the tubes 5-7, areas 15-17 of independent control of the heat exchange rate are formed. In practice, the number of internal tubes and, therefore, the number of annular channels may be different and is determined by the number of areas where independent control of intensity is required. Heat exchange. The reactor for the synthesis of, for example, ammonia, works as follows. The main feed stream enters the ammonia synthesis reactor through inlet 12, moves downward along the gap between the wall of the casing 1 and the catalyst box 2, then passes the annular space of the heat exchanger 3, where it is heated by the heat of the reaction products, mixed with the cold bypass flow input 13, and enters the group of concentric tubes 5-7. Moving further along these tubes, the feedstock enters the catalyst bed 4 where it undergoes chemical transformations leading to the formation of ammonia. The reaction of ammonia formation proceeds with the release of a large amount of heat. Excess heat from the chemical reaction zone is removed by heat exchange between the raw materials passing through the groups of concentric tubes 5-7 and the chemical reaction zone. To do this, it is necessary to regulate the flow rate of the cold bypass through the input 13.) Changing this flow entails a change in the temperature of the raw material entering the groups of tubes 5-7, which in turn regulates the temperature in the chemical reaction zone. However, in order to ensure maximum ammonia yield when changing conditions of management.

process, for example when changing the composition of raw materials, catalyst activity, etc. Neither 6 or 40 poddderzhivat optimum temperature in some parts of the zone x and the natural reaction.

When the process conditions change, the amount of heat released in one or another area changes, which makes it necessary to change the intensity of heat removal in certain areas of the chemical reaction zone.

The intensity of heat transfer is controlled by changing the flow rate of the controlling flow of raw materials through the annular channels formed by concentric tubes 5-7.

For example, an increase in the flow rate through the annular channel causes an increase in the rate of movement of the raw material in it, and consequently, it intensifies the heat exchange between the surfaces separated by the annular channel.

The change in heat transfer intensity in section 15 is achieved by changing the flow rate of the cold bypass through input 13, and in sections 16 and 17 by changing the flow of control flows, respectively, through inputs 9 and 11. Thus, changing the consumption of raw materials through input 11 will result in changes in heat transfer through the annular channel formed by tubes 6 and 7, and therefore to a change in the intensity of heat exchange between the main flow of raw materials in the central channel and section 17 of the reaction zone.

In this area, the annular channel is very narrow just by pipes 5 and 6, therefore the speed of movement of the raw material through it at any flow rate is large and does not have a significant effect on heat transfer.

A change in the flow rate of the controlled flow through the inlet 9 leads to a change in the rate of movement of the raw material in the annular channel formed by tubes 5 and 6. Due to the change in the thermal conductivity of this channel, the intensity of heat exchange in section 16 also changes.

Due to the fact that the inner tubes 6 have a variable diameter, the speed of movement in the annular channels varies along the length of these tubes and at a constant flow through the ports 9 and 11, which also affects the intensity of heat exchange.

The proposed reactor apparatus for ammonia synthesis allows the temperature in the chemical reaction zone to vary in certain areas almost independently of each other, which ensures an optimum value.

5 temperatures in the reaction zone throughout its duration under various process conditions, thereby increasing the yield of ammonia by 1%.

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Claims (2)

1. The patent of Germany 1542215, CL. 12 q, 4/02, 1965. 2. The patent of France 9 2141488, CL. On 01.J. 8/04, 1971. Jl