MXPA98000794A - Process for the co-production of ammonia ymeta - Google Patents

Abstract

A process for the co-production of ammonia and methanol in a plant comprising a first primary conversion section (11) and a secondary conversion section (12) arranged in series, an ammonia synthesis section (13) a section of synthesis of methanol (22), is distinguished by the fact that ammonia and methanol are produced in independent synthesis processes where the heat required for the conversion reaction in the methanol process is advantageously produced by using the high heat content present in the gas flow coming from the secondary conversion section (12) of the ammonia process

Description

PROCESS FOR THE CO-PRODUCTION OF AMMONIA AND METHANOL FIELD OF THE INVENTION The present invention relates to a process for the co-production of ammonia and methanol in a plant comprising a first primary conversion section and a secondary conversion section serially arranged in an ammonia synthesis section and a cross section. of methanol synthesis, the process comprising the steps of: - feeding methane and steam to the first primary conversion section; - reacting methane and steam in the first primary conversion section and successively in the secondary conversion section to obtain a first gas phase comprising CO, CO? and H2. In the description given below and in the following claims, the term "in situ" modernization is understood to mean the on-site modification of a pre-existing reactor in order to improve its performance and obtain, for example, greater capacity for production and / or higher conversion production and / or reduction in energy consumption. In the description given below and in the following claims, the term "synthesis section" is understood to mean in general all P1GW8MX that part of the plant related to the production of ammonia and methanol located operationally downstream of the conversion sections. In the description given below and in the following claims, the term "methane" is understood to mean in general a source of hydrogen and carbon raw material, such as, for example, methane itself or a mixture of liquid hydrocarbons and / or gaseous such as natural gas and naphtha. The present invention also relates to a plant for the co-production of ammonia and methanol to carry out the aforementioned process, as well as a modernization method for an ammonia synthesis plant and a modernization method for a cogeneration plant. -production of ammonia and methanol. As is known, there is an ever increasing requirement in the field of co-production of ammonia and methanol to provide easy-to-implement synthesis processes, which allow the achievement of ever greater production capacities at low operating and investment costs and at a low level energy consumption.

PREVIOUS TECHNIQUE For the purpose of satisfying the aforementioned requirement, it has recently been proposed in P1050 / 9TMX the field synthesis processes for the co-production of ammonia and methanol where a gas flow rich in CO, C02 and H2 coming from the secondary conversion section of the ammonia synthesis plant, is diverted to a synthesis section for the production of methanol. The unreacted gas subsequently re-enters the synthesis section of the ammonia plant. Although in some advantageous ways, the processes described above exhibit a number of disadvantages, the first of which is that the ammonia and methanol production capacity are strictly correlated and depend mainly on the methane and steam load that can be achieved. feed the conversion sections. In other words, since the total production capacity of the co-production plant operating in accordance with these processes is determined substantially by the load capacity of the conversion sections, in a full-capacity operating situation, an increase in the production of methanol inevitably causes an approximately equivalent reduction in the production of ammonia, and vice versa. This means that, if you want to obtain high production capacity of both ammonia and methanol, if necessary, according to the processes of the technique P1050 / 98MX above, to make a certain size of the conversion sections correspondingly so that they are capable of supporting a reagent load that allows the achievement of the desired production capacity. further, the ammonia and methanol synthesis sections must also be overdesign to meet any of the load increases caused by changes in methanol and ammonia production. Consequently, if a high production capacity of both ammonia and methanol is required, the co-production plant that must be provided for the implementation of the aforementioned processes exhibits considerable structural complexity, high investment and operating costs, and high energy consumption. Due to these disadvantages, the ammonia and methanol coproduction processes of the prior art have found little application to date despite the increasing demand in the industry.

SUMMARY OF THE INVENTION The problem underlying the present invention is to provide a process for the co-production of ammonia and methanol that is simple to carry out and allows achievement of the high conversion capacity of both ammonia and methanol with low investment costs and P1050 / O8MX operation and low power consumption. This problem is solved according to the present invention by a process for the co-production of ammonia and methanol of the aforementioned type, characterized in that it comprises the steps of: feeding methane and steam to a defined reaction zone in a second primary conversion section of the "exchanger" type; - feeding the first gaseous phase externally to the reaction zone in the second primary conversion section; - reacting the methane and the vapor in the reaction zone by the indirect heat exchange with the first gas phase to obtain a second gas phase comprising CO, CO ?. and H ?; - feeding the first gaseous phase that comes from the second primary conversion section to the ammonia synthesis section; - feeding the second gaseous phase that comes from the second primary conversion section to the methanol synthesis section. In the description given below and in the following claims, the term "prime conversion section of the" exchanger "type" is understood to mean a primary conversion section for the P1050 / 9BMX production of CO, C02 and H2, in which the heat of the reaction, instead of being supplied by combustion of a fuel (for example, natural gas or naphtha), is supplied by indirect heat exchange with a feed of hot gas flow to this section. In this specific case, the flow of hot gas is represented by the first gas phase that comes from the secondary conversion section. Conversion apparatuses of the "exchanger" type are generally known in the state of the art and are usually used in the processes of ammonia synthesis in the replacement of the primary conversion apparatus. These conversion apparatuses define within them a reaction zone through which the gaseous reactants pass. The conversion reaction is made possible by the heat transmitted by a hot gas flowing externally to the reaction zone. Conversion apparatuses of this type consist, for example, of a plurality of tubes filled with catalyst, out of which (shell side), a hot gas is produced which produces the heat of reaction from the indirect heat exchange to a gas cooler flowing in the tubes (side of the tubes) reacting. The conversion device of the type P1050 / n8MX "exchanger" can also be provided, by means of a plurality of contiguous chambers alternately filled with catalyst where the hot gas and the cold gas are flowed in empty chambers and in the filled chambers, respectively. In this case, the cameras are made, for example, of mutually parallel walls or concentric cylinders. Advantageously, thanks to the process according to the present invention, it is possible to achieve an independent production of ammonia and methanol, which allows to obtain high conversion capacities in a simple way, with low investment and operation costs and with low energy consumption. In fact, according to the present invention, the high heat content in the first gas phase coming from the secondary conversion section, is advantageously used as the heat of reaction to produce a second gas phase in a second primary conversion section. which comprises CO, C02 and H? for the methanol synthesis process. In this way, the production of synthesis gas for ammonia and methanol does not take place any longer in the common conversion sections, with all the disadvantages thereof with reference to the co-production processes of the prior art. The agreement process P1050 / 98MX with the present invention requires the production of methanol synthesis gas in a second, independent, primary conversion section. Advantageously, this second primary conversion section is fed with methane and steam which react by indirect heat exchange with a gaseous phase that comes from the secondary conversion section of the ammonia process, with the recovery of the heat contained in the gas phase while the use of energy sources external to the co-production process such as fuels used in general in the conversion sections is avoided. Preferably, the temperature of the first gas phase coming from the secondary conversion section and the feed to the second primary conversion section is between 900 ° C and 1100 ° C, to supply heat which ensures almost complete conversion of methane and steam administration to the second primary conversion section. Preferably, the process according to the present invention comprises the additional steps of: taking at least part of the second gaseous phase coming from the second primary conversion section; - feed this at least this part of the second gas phase to the first conversion section P1050 / 98MX primary. Thanks to this particular embodiment of the present invention, it is possible to control the amount of gas to be sent to the methanol synthesis section according to the amount of methanol that it is desired to produce. In addition to this way it is also possible to satisfy a situation in which methanol production is temporarily not required for reasons of market demand or for the maintenance of the synthesis section. Excess gas produced in the second primary conversion section comprising CO, C02 and H2, not sent to the methanol synthesis section is advantageously recycled to the first primary conversion section to reduce the methane and vapor load that is going to feed the first primary conversion section and consequently also the heat consumption of this section. Advantageously, the co-production process according to the present invention also comprises the additional steps of: taking a gaseous purge flow comprising CO, C02 and H2 that comes from the methane synthesis section !; - feed this gaseous purge flow to the first primary conversion section. In this way, the purge gas coming from the methanol synthesis section and rich in CO, C02 and H- is P1050 / 98MX can advantageously recover and recycle to the first primary conversion section to also achieve in this step a reduction in the load of methane and steam to be fed to the first primary conversion section and consequently of the heat consumption of this section and the total energy consumption of the co-production plant. To implement the aforementioned process, the present invention advantageously makes available a plant for the co-production of ammonia and methanol comprising: a first primary conversion section and a secondary conversion section arranged in series to obtain a first gas phase which comprises CO, C02 and H2; - Means for feeding methane and steam to the first primary conversion section; - a section of ammonia synthesis; - a methanol synthesis section; characterized in that it comprises: - a second primary conversion section of the "exchanger" type to obtain a second gaseous phase comprising CO, C02 and H2; - means for feeding methane and steam to a reaction zone defined in the second primary conversion section; P1050 / 98MX connection means between the secondary conversion section and the second primary conversion section for feeding the first gas phase externally to the reaction zone; - means for exchanging heat indirectly between the first gas phase and methane and steam in the second primary conversion section; - connection means between the second primary conversion section and the methanol synthesis section for feeding a second gas phase comprising CO, C02 and H2; - connecting means between the second primary conversion section and the ammonia synthesis section for feeding the latter the first gas phase. According to another aspect of the present invention, a method is also possible for modernizing an ammonia synthesis plant of the type comprising a first primary conversion section and a secondary conversion section arranged in series to obtain a first gas phase which comprises CO, C02 and H2, a medium for feeding methane and steam to the first primary conversion section, an ammonia synthesis section, the method comprising the steps of: P1050 / 98MX providing a methanol synthesis section; provide a second primary conversion section of the "exchanger" type; - providing a means for feeding methane and steam to a defined reaction zone the second primary conversion section; providing connection means between the secondary conversion section and the second primary conversion section for feeding the first gas phase externally to the reaction zone; - providing means for indirect heat exchange between the first gas phase and methane and steam in the second primary conversion section; provide connection means between the second primary conversion section and the methanol synthesis section to feed the latter a second gas phase comprising CO, CO? and H2; - providing connection means between the second primary conversion section and the ammonia synthesis section for the feed to the latter of the first gas phase. In accordance with another aspect of the present invention a method for modernizing is also possible.

P1050 / 98MX a co-production plant of ammonia and methanol of the type comprising a first primary conversion section and a secondary conversion section arranged in series to obtain a first gas phase comprising CO, C02 and H2, a medium for feeding methane and steam to the first primary conversion section an ammonia synthesis section, methanol synthesis section, and method comprising the steps of: providing a second primary conversion section of the "exchanger" type; - providing means for feeding methane and steam to a defined reaction zone the second primary conversion section; - providing connection means between the secondary conversion section and the second primary conversion section for feeding the first gas phase externally to the reaction zone; - providing means for indirect heat exchange between the first gas phase and methane and steam in the second primary conversion section; - providing connection means between the second primary conversion section and the methanol synthesis section to feed the latter a second gas phase comprising CO, C02 and H; P1050 / O8MX provide connection means between the second primary conversion section and the ammonia synthesis section for the feed to the latter of the first gas phase. Thanks to the modernization methods mentioned above for an existing plant, it is possible to obtain a simple ammonia and methanol co-production process capable of achieving high production capacities of both ammonia and methanol at low operating costs. and investment and with low energy consumption. The features and advantages of the present invention are set forth in the description of a modality thereof given below, by way of non-limiting example with reference to the appended figure.

BRIEF DESCRIPTION OF THE FIGURE Figure 1 shows a block diagram of the co-production process of ammonia and methanol according to the present invention.

DESCRIPTION OF A PREFERRED MODALITY Figure 1 shows a block diagram illustrating the steps of the co-production process of ammonia and methanol according to the present invention.

P1050 / TMX This process allows the simultaneous achievement of high ammonia production capacity (for example, between 1000 and 2500 metric tons per day) and methanol (for example, between 700 and 1700 metric tons per day). The reference number 10 indicates in general a portion the block diagram illustrating the steps of the ammonia production process. In this portion 10, the blocks 11, 12 and 13 respectively indicate a first primary conversion section, a secondary conversion section and an ammonia synthesis section. The latter includes, in addition to the real synthesis section, the high and low temperature CO conversion sections, the C02 separation section and the metanation section. The primary and secondary conversion sections mentioned above are catalytic. The reference number 20 generally indicates a portion of the block diagram illustrating the steps of the methanol production process. In this portion 20, blocks 21 and 22 respectively indicate a second primary conversion section and a methanol synthesis section. The latter also includes, in addition to the actual synthesis section, the separation and condensation section of H20 and the methanol purification section.

P1050 / 98MX Advantageously, the second primary conversion section indicated by block 21 is of the type "exchanger", and preferably of the type equipped with a plurality of tubes filled with catalyst in which the conversion reaction takes place. To the first primary conversion section indicated by block 11, flow line 1 is fed, which represents a first gas flow comprising methane and steam. The temperature of this first gaseous flow is the conventional temperature for an ammonia plant, for example 300-650 ° C. Step through the first primary conversion section and the secondary conversion section (blocks 11 and 12), the methane and vapor contained in the first gas stream react to have a first gas phase comprising CO, C02 and H ?. The flow line 2 represents this first gaseous phase coming from the secondary conversion section indicated by block 12. The temperature of the gas flow 2 is between 980 ° C and 1050 ° C. Advantageously, the flow line 2 crosses on the shell side the second primary conversion section represented by the block 21 where it is cooled downward by the indirect heat exchange with a gaseous flow comprising methane and the side of the P1050 / 98MX steam delivery pipe to block 21, and indicated by flow line 3. At the outlet of the second primary conversion section (block 21) gas flow 2 feeds the ammonia synthesis section (block 3) at a temperature of 30 ° C and 600 ° C. At the outlet of block 13, flow 2 comprises mainly ammonia. The gas flow represented by the flow line 3 feeds the second primary conversion section (block 21) at a temperature between 200 ° C and 600 ° C. Here the gas flow 3 reacts advantageously by heat exchange, indirectly with the gas flow indicated by the flow line 2, to obtain a second gas phase comprising CO, C02 and H2. The flow line 4 indicates this second gaseous phase that comes from the second primary conversion section (block 21). The temperature of the gas flow 4 is generally between 700 ° C and 1000 ° C. The gas flow 4 is fed into the methanol synthesis section represented by block 22. At the outlet of block 22, flow 4 contains mainly methane. The operating conditions of the synthesis sections for the production of ammonia or methanol (blocks P1050 / 98MX 13 or 22 respectively), as well as the reaction types that take place therein, are the conventional ones of a methanol and ammonia plant, respectively, known to those skilled in the art and therefore are not described in more detail. The pressure of the gas flow from 1 to 4 is preferably between 1 bar and 60 bar. According to the co-production process according to the present invention a first flow of methane and steam is fed to a first primary conversion section (block 11) and reacted in this conversion section and subsequently in a section of secondary conversion (blocks 11 and 12) to obtain a first gas phase comprising CO, -C02 and H ?. Advantageously, in accordance with further steps of the present invention, a methane and vapor flow is fed to a defined reaction zone in a second primary conversion section (block 21). At the same time, the first gas phase is fed externally to the reaction zone of the second primary conversion section. Within this reaction zone, methane and steam are reacted by indirect heat exchange with the first gas phase to obtain a second gas phase comprising CO, C02 and H2. The first gas phase that comes from the second conversion section Primary P1050 / 98MX is then fed to an ammonia synthesis section (block 13), while the second gas phase is fed to a methanol synthesis section (block 22). In this way, ammonia and methanol are produced in independent synthesis processes, where the heat required for the methane conversion reaction in the methanol process is advantageously obtained by using the high heat content in the gas flow that comes of the secondary heat section of the ammonia process. According to another particularly advantageous embodiment of the present invention, but not shown, the co-production process comprising the additional step of cooling the second gas phase (flow line 4) that comes from the second primary conversion section ( block 21) by the indirect heat exchange with the cooling water, to obtain high pressure steam and temperature for example between 5 bar and 130 bar and between 150 ° C and 550 ° C respectively. By doing so, the heat of the gas phase coming from the second primary conversion section is advantageously recovered for the production of steam with a high level of heat, which can be used depending on the requirements, for example, in the other sections of the co-production plant of ammonia and methanol.

P1050 / 98MX The gas flow temperature 4 which is subjected to the cooling step mentioned above is between 30 ° C and 300 ° C. The heat in the gas flow 4 coming from the block 21 can alternatively be recovered to preheat by indirect heat exchange the methane or gaseous flow comprising methane and steam to be fed to the second primary conversion section. According to an alternative embodiment of the process according to the present invention, part of the second gaseous phase (flow line 4) coming from the block 21 can be advantageously diverted to the first primary conversion section (block 11) of the process of ammonia. This allows the adaptation of the production capacity of the methanol process depending on the desired amount of methanol and at the same time reduce the methane load that is going to be fed to the ammonia process which results in savings of raw materials and energy. In Figure 1, this mode is shown in dashed lines by the flow line 5. In the case that only the production of ammonia is required, then the entire second gas phase coming from the block 21 is advantageously sent (flow line 5). ) to the first primary conversion section (block 11) of the P1050 / 98MX ammonia process as shown in figure 1, or directly to the secondary conversion section (block 12). In another alternative and particularly advantageous embodiment of the process according to the present invention, a purge gas stream comprising CO, C02 and H2 which comes from the methanol synthesis section (block 22), to the first primary conversion section (block 11) of the ammonia process to obtain an additional lightening of the methane load to be fed to this conversion section. The pressure and the temperature of the feed of the purge gaseous flow to the first primary conversion section are generally between 1 bar and 60 bar and between 30 ° C and 600 ° C respectively. In Figure 1, this embodiment is shown in dashed lines by the flow line 6. The ammonia and methanol co-production plant according to the present invention includes the sections represented by blocks 11-13 and 21-22 of Figure 1. At the entrance and the sections constituting the aforementioned plant are provided suitable feeding and connecting means, respectively of the types known in the industry, for example ducts, pipes and the like represented schematically by the P1 50 / c'8MX flow lines 1-6 of Figure 1. Within the second primary conversion section, represented by block 21, suitable means are provided for the indirect heat exchange between gas flows 2 and 3. These means may comprise one or more heat exchangers. Advantageously, the plant according to the present invention also provides a cooling section (not shown) for cooling the gas flow 4 coming from the block 21 by the indirect heat exchange with the cooling water. A cooling section of this type may, for example, comprise a boiler for the production of steam. In order to increase methanol production, a gas flow comprising CO? Is advantageously added. (not shown) to flow line 3 or 4, preferably to flow line 4. In fact, since the gas flowing through line 4 is generally very rich in H-, the above addition allows a improvement in the stoichiometric ratio of C0; / Hz which results in an improvement of the methanol synthesis conditions. According to the present invention, the method for modernizing an existing co-production plant of ammonia and methanol comprising a first section of P1050 / 98MX primary conversion and a secondary conversion section (blocks 11 and 12) arranged in mutual series, an ammonia synthesis section (block 13) and a methanol synthesis section (block 22), advantageously provides the steps of providing a second primary conversion section (block 21) of the "exchanger" type comprising a suitable medium for indirect heat exchange, and for the provision of suitable means for feeding to the second conversion section. primary (block 21) and the connection between the secondary conversion section and the second primary conversion section (blocks 12 and 21) as between the second primary conversion section and the ammonia and methanol synthesis sections (blocks 21, 13 and 22). The method for the modernization of an ammonia synthesis plant, existing in accordance with the present invention provides the additional step of also providing a methanol synthesis section (block 22), in addition to the second primary conversion section. Advantageously, in an alternative embodiment of the above modernization methods, not shown, a cooling section for cooling the gas flow 4 by the indirect heat exchange with cooling water for the production of steam at a high heat level, is provides between blocks 21 and 22.

P1050 / 98MX In addition, according to another embodiment of the modernization methods according to the present invention, suitable connection means are advantageously provided between the first and second primary conversion sections (blocks 21 and 11) and between the synthesis section of methanol and the first primary conversion section (block 11). In this way it is possible to recover the CO, C02 and H2 in excess of the methanol synthesis process and send it to the ammonia synthesis process to lighten the methane load that is going to be sent to the conversion sections of the ammonia plant and in this way achieve a reduction in energy and consumption of raw materials. In the special situation in which only ammonia is proposed to be produced, then the above modernization methods advantageously allow an increase in the production of the conversion sections with respect to a pre-existing ammonia synthesis plant, thanks to the provision of the second section of primary conversion. From the foregoing, the numerous advantages achieved by the present invention are clear. In particular, a process of ammonia and methanol co-production simple to implement, capable of achieving high production capacities for both ammonia and methanol is provided P1050 / 98MX with low operating and investment costs and low power consumption. Additionally, in the case of the modernization of an ammonia synthesis plant or a co-production plant of ammonia and methanol it is possible to achieve a high methanol production capacity while maintaining the ammonia production capacity without change.

P1050 / 9TMX

Claims (14)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. Process for the co-production of ammonia and methanol in a plant comprising a first primary conversion section and secondary conversion section arranged in series, an ammonia synthesis section and a methanol synthesis section, the process comprising the steps of: - feeding methane and steam to the first primary conversion section; - reacting methane and steam in the first primary conversion section and successively in the secondary conversion section to obtain a first gas phase comprising CO, C02 and H2. characterized in that it comprises the steps of: - feeding methane and steam to a defined reaction zone in a second primary conversion section of the "exchanger" type; - feeding the first gaseous phase externally to the reaction zone in the second primary conversion section; - reacting methane and steam in the P1050 / 9TMX reaction zone by the indirect heat exchange with the first gas phase to obtain a second gas phase comprising CO, C02 and H2; - feeding the first gaseous phase that comes from the second primary conversion section to the ammonia synthesis section; - feeding the second gaseous phase that comes from the second primary conversion section to the methanol synthesis section.
2. 2. The process according to claim 1, characterized in that the temperature of the feed of the first gas phase to the second primary conversion section is between 900 and 1100 ° C.
3. The process according to claim 1, characterized in that it comprises an additional step of cooling the second gas phase coming from the second primary conversion section by indirect heat exchange with the cooling water to obtain high pressure steam and temperature.
4. The process according to claim 1, characterized in that it comprises the additional steps of: - taking at least part of the second gaseous phase coming from the second primary conversion section; and - feed this at least this part of P1'J50 / O8MX the second gaseous phase to the first primary conversion section.
5. The process according to claim 1, characterized in that it comprises the additional steps of: - taking a gaseous purge flow comprising CO, C02 and H2 which comes from the methanol synthesis section; - feeding this gaseous purge flow to the first primary conversion section.
6. 6. Plant for the co-production of ammonia and methanol comprising: - a first primary conversion section (11) and a secondary conversion section (12) arranged in series to obtain a first gas phase comprising CO, C02 and H2; - means (1) for feeding methane and steam to the first primary conversion section (11); - an ammonia synthesis section (13); - a methanol synthesis section (22); characterized in that it comprises: - a second primary conversion section (21) of the "exchanger" type to obtain a second gaseous phase comprising CO, C02 and H2; - means (3) to feed methane and steam to a P1050 / 98MX reaction zone defined in the second primary conversion section (21); - connecting means (2) between the secondary conversion section (12) and the second primary conversion section (21) for externally feeding the first gas phase to the reaction zone; - means for the indirect heat exchange between the first gas phase and the methane and steam in the second primary conversion section (21); connecting means (4) between the second primary conversion section (21) and the methanol synthesis section (22) to feed the latter a second gas phase comprising CO, C02 and H2; and - connecting means (4) between the second primary conversion section (21) and the ammonia synthesis section (13) to feed the latter a first gas phase.
7. 7. The plant according to claim 6, characterized in that it comprises a section in communication for fluids with the methanol synthesis section (22) for cooling the second gas phase coming from the second primary conversion section (21) by the indirect heat exchange with cooling water.
8. The plant according to claim 6, characterized in that it comprises connection means (5) P1050 / 9TMX between the second primary conversion section (21) and the first primary conversion section (11) to feed the latter at least part of the second gas phase coming from the second primary conversion section (21).
9. The plant according to claim 6, characterized in that it comprises connection means (6) between the methanol synthesis section (22) and the first primary conversion section (11) to feed the latter a gaseous purge flow that it comprises CO, C02 and H2 that comes from the methanol synthesis section (22).
10. 10. Method for modernizing an ammonia synthesis plant of the type comprising a first primary conversion section (11) and a secondary conversion section (12) arranged in series to obtain a first gas phase comprising CO, C02 and H2, means (1) for feeding methane and steam to the first primary conversion section (11), an ammonia synthesis section (13) the method comprising the steps of: providing a methanol synthesis section (22); providing a second primary conversion section of the type "exchanger" (21); P1050 / 9SMX - providing a means (3) for feeding methane and steam to a defined reaction zone the second primary conversion section (21); - providing a connection means (2) between the secondary conversion section (12) and the second primary conversion section (21) for externally feeding the first gas phase to the reaction zone; - providing means for the indirect heat exchange between the first gas phase and the methane and the vapor in the second primary conversion section (21); - providing a connection means (4) between the second primary conversion section (21) and the methanol synthesis section (22) to feed the latter a second gas phase comprising CO, C02 and H2; - providing a connection means (2) between the second primary conversion section (21) and the ammonia synthesis section (13) for feeding the first gas phase to the latter.
11. 11. Method for modernizing an ammonia and methanol coproduction plant of the type comprising a first primary conversion section (11) and a secondary conversion section (12) arranged in series for P1050 / 98MX obtain a first gaseous phase comprising CO, C02 and H2, means (1) to feed methane and steam to the first primary conversion section (11), an ammonia synthesis section (13), a synthesis section of methanol (22), and the method comprising the steps of: providing a second primary conversion section of the "exchanger" type (21); - providing a means (3) for feeding methane and steam to a defined reaction zone the second primary conversion section (21); - providing a connection means (2) between the secondary conversion section (12) and the second primary conversion section (21) for externally feeding the first gas phase to the reaction zone; - providing means for the indirect heat exchange between the first gas phase and the methane and the vapor in the second primary conversion section (21); - providing a connection means (4) between the second primary conversion section (21) and the methanol synthesis section (22) to feed the latter a second gas phase comprising CO, C02 and H2; and - providing a connecting means (2) between P1050 / 98MX the second section of primary conversion (21) and the section of synthesis of ammonia (13) for the feed to the latter of first gas phase.
12. The method according to claims 10 and 11, characterized in that it provides a section for cooling the second gas phase coming from the second primary conversion section by the indirect heat exchange with cooling water in communication for fluids with the methanol synthesis section (22).
13. 13. The method according to claims 10 and 11, characterized in that it provides connection means (5) between the second primary conversion section (21) and the first primary conversion section (11) to feed the latter with at least part of the second gas phase. The method according to claims 10 and 11, characterized in that it provides connection means (6) between the methanol synthesis section (22) and the first primary conversion section (11) to feed the latter with a flow gaseous purge comprising CO, C02 and H2 that comes from the methanol synthesis section. P1050 / 98 X