Catalytic method for the production of ammonia from synthesis gas

 

Ammonia is produced from synthesis gas containing nitrogen and hydrogen, at a granular catalyst in at least one reactor under a pressure in the range from 50 to 300 bar and at a temperature in the range from 100 to 600°C. the Mixture of products containing pairs of NH3divert from the reactor, cooled, ammonia is condensed and separated it, while the recirculated gas, which is mixed with fresh synthesis gas, return to the reactor as of synthesis gas, and unreacted synthesis gas is passed through the first layer of catalyst-free cooling tube, and then as the partially reacted synthesis gas with a content of NH3from 5 to 20 vol.% passed through the heat exchanger as a heating fluid. Partially reacted synthesis gas is passed through at least one of the next layer of catalyst that is filled cooling tubes, and unreacted synthesis gas is passed in as a cooling gas through the cooling pipes of the next layer of catalyst and heated to 300 to 500°With the cooling gas is sent to the first catalyst bed and through the cooling tubes and the following layers of the catalyst gas is flowed forward. The method allows to adjust the temperature , the reactor exit. 4 C.p. f-crystals, 1 tab., 3 Il.

The invention relates to a method for producing ammonia from a synthesis gas containing nitrogen and hydrogen, at a granular catalyst in at least one reactor under a pressure in the range from 50 to 300 bar and at a temperature in the range from 100 to 600°C; and from the reactor the mixture of products containing pairs of NH3divert, cooled, and the ammonia condenses and is separated with the formation of the recirculation gas, which is mixed with fresh synthesis gas and return the recirculated gas as synthesis gas in the reactor.

The basis of the invention lies in the task of ensuring the possibility to adjust the temperature of the synthesis gas passing through several layers of catalyst so that the mixture of products was probably a higher concentration of NH3. This is achieved according to the invention due to the fact that unreacted synthesis gas, which serves as a cooling gas is passed through free cooling tube first catalyst bed and then passed as a partially reacted synthesis gas with a content of NH3from 5 to 20 vol.% as a heating fluid through talabor, through which the cooling tubes, unreacted synthesis gas as a cooling gas is passed through the cooling pipes of the next layer of catalyst and heated to a temperature of from 300 to 500°With the cooling gas is sent to the first catalyst bed and through the cooling tube and the next layer of the catalyst is co-current.

At the specified method, it is important to unreacted synthesis gas is passed first through the first layer of the catalyst not containing cooling tube; moreover, the formation of NH3vigorously and usually lead to the rise in temperature of 80-200°C. In the heat exchanger partially reacted synthesis gas is again cooled, and the reduction of temperature regulate. Usually in the specified heat-exchanger temperature is reduced from 50 to 150°C. In another layer of the catalyst containing the cooling pipes, the reaction continues in a controlled way before the formation of the desired mixture of products. Other layers of catalyst supplied with cooling tubes is mainly 1-4 layer. In each of these cooling layers can be desirable to choose the number of cooling tubes, and thereby the intensity of the cooling. In the heat exchanger can podavavshii synthesis gas. Partially reacted synthesis gas is usually cooled in a heat exchanger for 30-180°C. the Method according to the invention allows to achieve the cooled catalyst temperature profile, which is closest to the optimal temperature curve. This reach very high concentrations of NH3in a mixture of products.

One of the variants of the proposed method is that coming out of the heat exchanger heats the liquid is removed from the reactor and serves to separate the tubular reactor in which the catalyst is placed in the tubes, indirectly cooled recirculating coolant. Of the tubular reactor are selected partially reacted synthesis gas containing NH3from 15 to 30 vol.% and a temperature of from 250 to 500°C and then passed through one or more layers of the catalyst cooling tubes. Typically, the pressure on the outside of the tubes of a tubular reactor containing the catalyst, is 30-290 bar lower than inside the tubes. Suitable partially reacted synthesis gas containing NH3from 5 to 15 vol.% serve in a separate tubular reactor so that the main part of the reaction could be specified in a separate reactor.

Suppose the least two additional catalyst layer, which is supplied with cooling tubes. Taken from the last of these layers of the catalyst mixture product leaves the reactor and is cooled from the outside to the condensation of ammonia. The cooling gas flowing from the heat exchanger, it is advisable to pass first through the cooling tubes of the last layer of the catalyst, and then through the cooling pipes of the penultimate layer of the catalyst. In this case, there is possibility in the heat exchanger as a cooling means to use unreacted synthesis gas, which is then served on the cooling tube catalyst layer.

Obtaining synthesis gas, which contains hydrogen and nitrogen in a molar ratio of about 3:1, is known and described, for example, in patent EP 307983. Used catalysts are conventional and as active components include, for example, Fe, and oxides of K, CA, Al (as, for example, the catalyst FNMS Montecatini-Edison).

Design features of the method are explained using the drawings.

They are:

Fig.1 - the first version of the synthesis reactor in longitudinal section in a schematic diagram;

Fig.2 - reactor in longitudinal section for the second variant of the method;

Fig.3 is a chart of the optimal reaction.

With the th plate (3) and the inner lining (4). The synthesis gas passes first through a pipeline (7) allocator (8), which is connected to the cooling tubes (9). The cooling tube (9) are found in the layer (10) of the catalyst and is connected at its outlet end with a collection of (11) through which the heated synthesis gas passes into the pipe (12) and then into the distribution chamber (13) of the first layer (14) of the catalyst. Tube (9) can be curved, spiral and straight.

Unreacted synthesis gas is supplied from the distribution chamber (13) in the first layer (14) of the catalyst, where intensive formation of NH3. Belonging to the first layer (14) of the catalyst of the exhaust chamber (15) is partially reacted synthesis gas containing NH3from 5 to 20 vol.% and passes through the hole (6) in the wall of the heat exchanger (5), not containing catalyst. There is a partially reacted synthesis gas is indirectly cooled by cooling means serves in the pipeline (5A) and absorbed in the pipeline (5b). The cooled partially reacted synthesis gas is sent then through the next hole (16) in the wall of the first distribution chamber (17) related to the cooled layer (10) of the catalyst. In the specified layer of the catalyst reaction protector (2) through release (19).

The mixture of products passes through the pipe (20) to the indirect cooler (21), which can be set are indicated by dashes cooler (21A), and then in a known manner still further cooled in several stages, and NH3condensed. Simplified the drawing shows a heat exchanger (22), from which the condensed ammonia is taken through line (23). The remaining recycle gas passes through line (24) into the compressor (25), through line (26) mixed with fresh synthesis gas. The recirculated gas is heated in the heat exchanger (21) through line (1) return to the reactor (2).

You can, as you know, unreacted synthesis gas and, for example, recirculating gas from the pipeline (1) first put in the intermediate chamber (3A) between the outer plate (3) and the inner lining (4), so that by cooling to protect the plates from overheating. Specified unreacted synthesis gas is then sent first, for example, in the cooling tube (9) chilled layer (10) of the catalyst, where it acts as a cooling gas.

For the variant of the method according to Fig.2 includes a reactor (2A), which is connected to a separate tubular reactor (30). Submitted recircularisation synthesis gas, through holes (6) in the wall enters the heat exchanger (5). Partially heated cooling gas passes downward flow through the pipe (31) of the heat exchanger (5) and enters the distributor (32), the cooling tube (9) which are in the last layer (33) of the catalyst. Pipe (31) is a vertical Central tube (29), the inner region which is free of catalyst.

The cooling tube (9) of the last layer (33) of the catalyst overlook a collection of (34), which is connected to the outlet (35), leading to the manifold (36). Connected to the distributor (36) cooling tube (9) are in the next layer (38) of the catalyst, and the cooling gas passes from the tube (9) to the next collection (39) and then through the outlet (40) to the third valve (41), which refers to the next layer (42) of the catalyst. The exhaust from the valve (41) cooling tube (9) appear in the collection (43), which is connected to the outlet (44), a conductive heated unreacted synthesis gas distribution chamber (13) of the first layer (14) of the catalyst. This first layer (14) of the catalyst is free from the cooling tube. Partially reacted synthesis gas is fed first into the reservoir (15) and then cooled in a gas-gas those who Chala through the release of (46) and then through the pipe (47) in a separate tubular reactor (30), which is granular catalyst in tubes (50). From the distribution chamber (48) to the tube (50), surrounded by a cooling medium, comes partially reacted synthesis gas. The cooling fluid serves to recycling in a known manner through an external cooler (51). And in the case of the cooling medium we are talking about, for example, diphenyl or salt melt.

Synthesis gas containing NH3from 15 to 30 vol.% and a temperature of from 250 to 500°With leaves filled with catalyst tube (50) comes first in the reservoir (52) and then passes through the pipe (53) in the control pipe (54) and then through the distribution chamber (42A) in the layer (42) of the catalyst.

For the next reaction of the partially reacted synthesis gas in the drawing goes down first through the chilled layer (42) of the catalyst, and then through the chilled layer (38) of the catalyst and, finally, through the chilled layer (33) of the catalyst in the exhaust chamber (33a) and then as a mixture of products for release (19) from the reactor. Further processing of the mixture of products, in particular, the cooling, the Department of NH3the fresh synthesis gas and return to the pipeline (1) are the same as described for Fig.1.

In the method according to Fig.2 significant aspect is used for cooling in the last layer (33) of the catalyst, before him as a cooling gas is passed through the penultimate layer (38) of the catalyst.

In Fig.3 shows a graph of the dependence of the reaction temperature T and the fraction of NH3(in mol.%) in the synthesis gas. Line (G) gives the equilibrium condition, the line (A) optimum temperature for the reaction rate. The plot is related to the following example, the principle of operation layer (38), the temperature curve specified line (A1), (K) represents the corresponding average cooling temperature. In the example, the temperature in the tubular reactor (30) and the layer (42) and (33) close to the optimal temperature curve.

Example.

The example refers to the carrying out of the method according to Fig.2, and the day got 1000 tonnes of ammonia. The synthesis gas after washing with liquid nitrogen and did not include any CH4or argon.

Quantitative data, the values of pressures, temperatures and compositions calculated for the parts listed in the table. The catalyst is above FNMS.

Data layer (38) and (42) whenever relate to the issue of the layer. Under optimal temperature conditions in this example, at the outlet of the reactor (19) reach very high concentrations of NH3equal wego nitrogen and hydrogen, on granular catalyst in at least one reactor under a pressure in the range of 50 to 300 bar and at a temperature in the range of 100-600°C, and from the reactor the mixture of products containing pairs of NH3divert, cool, ammonia condenses and is separated with the formation of the recirculation gas, which is mixed with fresh synthesis gas and recycle gas is returned to the reactor as of synthesis gas, with unreacted synthesis gas is passed through the first layer of the catalyst not containing cooling tube, and then as the partially reacted synthesis gas with a content of NH35-20 vol.% passed as a heating fluid through the heat exchanger, characterized in that the partially reacted synthesis gas is passed through at least two catalyst layer, through which the cooling pipes, with unreacted synthesis gas is passed through the cooling pipes of the following layers of the catalyst as a cooling gas and heated to 300 to 500°With the cooling gas is sent to the first catalyst bed and through the cooling tube and following the catalyst layers is parallel, the cooling gas is first passed through the cooling pipes after the .1, characterized in that coming from the heat exchanger heats the liquid away from the reactor and sent to a separate tubular reactor in which the catalyst is located in the tubes, cooled recirculating the cooling fluid from the tubular reactor are selected partially reacted synthesis gas containing NH315-30 vol.% and a temperature of 250 to 500°C and put it through a layer of the catalyst cooling tubes.

3. The method according to p. 2, characterized in that the pressure outside the tubes of a tubular reactor containing the catalyst, 30-290 bar lower than inside the tubes.

4. The method according to p. 1 or one of the subsequent paragraphs, characterized in that the heat exchanger, in which the partially reacted synthesis gas as a heating fluid is passed unreacted synthesis gas as a coolant and then direct it to the cooling tube catalyst layer.

5. The method according to one of paragraphs.2-4, characterized in that the partially reacted synthesis gas containing NH35-15 vol.% send in a separate tubular reactor.



 

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Reactor // 2246345

FIELD: chemical industry, catalytic processes.

SUBSTANCE: the invention presents a reactor for catalytic processes and is dealt with the field of chemical industry and may be used for catalytic processes. The reactor contains: a body; units of input and output for a reaction mixture and products of reactions; units of loading and unloading of a catalyst; a catalyst layer with the groups of the parallel hollow gas-permeable chambers located on it in height in one or several horizontal planes and each of the chambers has a perforated gas-distributing pipe with impenetrable butt connected to the group collector and used for input of additional amount of the reaction mixture. Each of perforated gas-permeable chambers is supplied with the second gas-distributing pipe with impenetrable butt. At that the impenetrable butts of the pipes are located on the opposite sides. The given engineering solution provides uniformity and entirety of agitation of the reaction mixtures.

EFFECT: the invention provides uniformity and entirety of agitation of the reaction mixtures.

5 cl, 4 dwg

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