DE102018117654A1 - Apparatus with a steam reformer, method using the apparatus and a corresponding use of the apparatus - Google Patents

Abstract

The present invention relates to a device comprising a steam reformer and a heat exchanger system for controlling the temperature of a gas flow which is upstream of the steam reformer and which comprises at least a first heat exchanger element and at least one second heat exchanger element, wherein the first heat exchanger element and the second heat exchanger element are designed and set up, tempering the gas stream, and wherein the heat exchanger system is designed and arranged so that only the first heat exchanger element, only the second heat exchanger element or both heat exchanger elements are activated simultaneously, and a method using the device and a use of the device.

Description

State of the art

The present invention relates to a device with a steam reformer. The invention further relates to a method for controlling the temperature of a gas stream for a steam reformer using the device according to the invention. Finally, the invention relates to a use of the device described.

For the production of ammonia is usually in a device for the production of ammonia (= ammonia plant), a synthesis gas, which usually contains in addition to hydrogen and nitrogen additional inert gases such as methane or noble gas, in the presence of a suitable catalyst. For this purpose, the synthesis gas is fed into the device and passed through at least one catalyst-filled reactor in which ammonia is then produced. Conventional devices for the production of ammonia are well known in the art and in about the DE 10 2015 210 801 A1 . DE 100 57 863 A1 or DD 225 029 A3 described. The synthesis gas is mostly generated in a steam reforming process. For this purpose, a steam reformer (= Steam Reformer) combustion air is supplied. If necessary, an air preheater is connected upstream of the steam reformer.

The generation of hydrogen is usually carried out in a plant (hydrogen plant), in which the hydrogen is obtained by steam reforming of natural gas. During reforming hydrocarbons are converted into hydrogen. By-products are carbon monoxide and carbon dioxide. The steam reforming takes place in a steam reformer by an endothermic reaction. The product gas is cooled and purified in a pressure swing adsorber to produce as pure as possible hydrogen. Such a procedure is approximately from the DE 10 2016 103 321 A1 known.

In known from the prior art devices with a steam reformer is heated to heat the combustion air before entering the air preheater and / or the steam reformer by means of a heat exchanger (= Calorifier). For this purpose, the use of simple conventional heat exchangers is provided in the prior art. For the devices known from the prior art, however, this results in a disadvantage when the devices are used in environments, ie in particular in geographical regions, which are exposed to large temperature fluctuations. In particular, in the event that the ammonia plant is used in a region in which the temperatures between summer and winter fluctuations of at least 30 ° C, the problem may occur that the combustion air heated by the calorifier has an unsuitable for the further reaction temperature , If the Calorifier is not heated enough at low ambient temperatures, the dew point may drop below the minimum, especially in the air preheater. If the Calorifier however, designed for high ambient temperature such that large amounts of heat to be provided, this can lead to excessively high temperatures of the combustion gas and _x concentrations in the exhaust lead to undesired side reactions, for example increasing NO.

Disclosure of the invention

The present invention is therefore based on the object to provide a device with a steam reformer, which overcomes the disadvantages of the prior art, in particular inlet temperature fluctuations of the combustion air, such as in the gas flow or air preheater or the steam reformer, to avoid in strongly varying ambient temperature.

This object is achieved by a device comprising a first line for a gas stream, a steam reformer and a heat exchanger system for controlling the temperature of the gas stream upstream of the steam reformer and comprising at least a first heat exchanger element and at least a second heat exchanger element, wherein the first heat exchanger element and the second heat exchanger element are designed and set up to temper the gas stream which can be supplied via the first line, and wherein the heat exchanger system is designed and set up so that only the first heat exchanger element, only the second heat exchanger element or both heat exchanger elements can be activated simultaneously or used for temperature control of the gas flow ,

A steam reformer in the context of the invention is used to produce hydrogen from carbonaceous energy sources, in particular natural gas, and water or water vapor.

According to the invention, it can be provided that the device with a steam reformer is an ammonia plant or a hydrogen plant.

According to the invention, it is provided that the device for the production of ammonia, in addition to the specified components essential for the invention, comprises further typical constituents which are known and necessary for devices according to the invention, for example ammonia plants or hydrogen plants.

Surprisingly, it has been found by the inventors that can be reduced by the inventive device inlet temperature fluctuations of the combustion air at varying outside temperature.

The heat exchanger system according to the invention can, in addition to the first heat exchanger element and the second heat exchanger element, receive further means for activating the heat exchanger elements. Activation of the respective heat exchanger element should be understood here to mean the startup, that is to say, in particular, the heating of the corresponding heat exchanger element, in order to trigger the release of heat through the heat exchanger element. Accordingly, activated, i. actually used heat exchanger elements for controlling the temperature of the gas stream used. In an embodiment it can be provided that the heat exchanger system comprises exactly one first heat exchanger element and exactly one second heat exchanger element. The heat exchanger elements can in this case be arranged both in a common housing and in each case in separate housings.

It is ensured that the first heat exchanger element and the second heat exchanger element in each case activated individually, so can be controlled individually. This also includes a partial activation, in particular of the second heat exchanger, so as to obtain a flexible temperature control. In this way, a flexible heating of a gas, which is performed by the heat exchanger system, allows. If only one of the heat exchanger elements, ie either the first heat exchanger element or the second heat exchanger element is activated, a gas conducted through the two heat exchanger elements is heated to a lesser extent than if both heat exchanger elements are activated. In this way, it is possible to respond flexibly to the ambient temperature. At low ambient temperature, both heat exchanger elements are activated so as to achieve greater heating of the gas. At higher ambient temperature, only one of the two heat exchanger elements is activated so as to avoid overheating. In order to enable more differentiated heating processes, more than two heat exchanger elements can be provided.

As a heat exchanger element (also heat exchanger, heat exchanger or heat exchanger) according to the invention, any apparatus should be understood that can transfer thermal energy from one stream to another. Conventional heat exchanger elements are known from the prior art.

In one embodiment it can be provided that the first heat exchanger element and / or the second heat exchanger element comprise or constitute a heat exchanger bundle. A heat exchanger bundle consists of a bundle of parallel tubes in which a first exchange fluid circulates and means for sequentially sequentially flowing a second exchange fluid through regions of the bundle successively closer to the entrance of the first fluid. Likewise it can be provided that at least one of the heat exchanger elements is a plate heat exchanger. Both by the use of heat exchanger bundles and plate heat exchangers as a heat exchanger element, a particularly efficient transmission of thermal energy can be achieved.

In a further embodiment it can be provided that the apparatus further comprises a first connecting line, by means of the process condensate, boiler feed water and / or steam, in particular process condensate, boiler feed water and steam, can be fed into the first heat exchanger element, a second connecting line, which starts from the first heat exchanger element and opens into the second heat exchanger element and by means of the first heat exchanger element entstammendes process condensate, boiler feed water and / or steam, in particular process condensate, boiler feed water and steam, the second heat exchanger element can be supplied, and a third connecting line, which emanates from the second heat exchanger element and on the second heat exchanger element entstammendes Process condensate, boiler feed water and / or steam, in particular process condensate, boiler feed water and steam, can be discharged.

The device according to the invention also comprises, in a further embodiment, another part of this device which is provided for the production or presence of process condensate, boiler feed water and / or steam, in particular process condensate, boiler feed water and steam, and via the first connection line to the first heat exchanger element connected or connectable.

Furthermore, it is provided in an advantageous embodiment of the device according to the invention, that the first heat exchanger element is connected upstream of the second heat exchanger element. Alternatively, and in particular additionally, it can be provided that the gas stream can be forwarded from the first heat exchanger element to the second heat exchanger element via a second line.

In a particularly advantageous embodiment of the device according to the invention, this further comprises a bypass line for the transport of process condensate, boiler feed water and / or steam, in particular process condensate, boiler feed water and steam, which branches off from the second connection line and which opens into the third connection line.

By the arrangement provided in this embodiment, it is possible in a very efficient way to heat through the bypass in the heat exchanger system (Calorifier) either one or both heat exchanger elements with a resulting during the manufacturing process process condensate or boiler feed water or steam and in this way by To temper the / the heat exchanger elements conducted gas stream. As a result, an energy and cost-reduced process management regularly succeeds.

For this purpose, e.g. be provided in one embodiment, that the second connecting line between the branch of the bypass line and the second heat exchanger element comprises a first closing valve and / or, and preferably, that the third connecting line between the second heat exchanger element and the mouth of the bypass line, a second closing valve and / or, preferably, and that the bypass line between the branch from the second connecting line and the junction in the third connecting line comprises a third closing valve.

In a further embodiment it can be provided that the device further comprises a gas flow or air preheater upstream of the steam reformer and / or connected downstream of the heat exchanger system.

In this case, the heat exchanger system can be arranged directly in front of the gas flow or air preheater and / or directly in front of the steam reformer. By this arrangement, the temperature within the gas flow or air preheater and / or the steam reformer can be controlled in a simple manner and optimally adjusted to the ambient temperature.

It has proved to be expedient that the device according to the invention also has a third line, via which the gas flow from the second heat exchanger element to the steam reformer can be forwarded. Accordingly, the transport of the gas stream is preferably carried out via the first, second and third line in the context of the invention, while for the transport of process condensate, boiler feed water and / or steam expediently recourse to the first, second and third connection line according to the invention. In addition, the object is achieved by a method comprising a) providing a device according to the invention; b.1) activating the first heat exchanger element or the second heat exchanger element to obtain a first mode of operation, or b.2) activating the first heat exchanger element and the second heat exchanger element to obtain a second mode of operation; and c) contacting a gas flow with the first heat exchanger element and the second heat exchanger element.

In an embodiment it can be provided that the gas stream is a stream of combustion air. In this way, a resource-saving process management is made possible.

It can also be provided that the method according to the invention comprises a further step a ', between the steps a and b, of determining the ambient temperature, wherein following step a', step b.1 is performed when the ambient temperature in a first Temperature range is or step b.2 is performed when the ambient temperature is in a second temperature range, wherein the first temperature range is below the second temperature range. It is provided here that the temperatures of the first temperature range are lower than the temperatures of the second temperature range measured in degrees C. In this way, a targeted process management is made possible, which allows to tune the operation of the system exactly to specific environmental conditions.

In particular, it can be provided that the first temperature range from -50 ° C to + 5 ° C. As a result, an adaptation of the method according to the invention to usual ambient conditions is possible.

Furthermore, it can be provided that the second temperature range is more than + 5 ° C to + 50 ° C. As a result, an adaptation of the method according to the invention to usual ambient conditions is possible.

Finally, the object of the invention is achieved by the use of a device according to the invention in an environment which is exposed to temperature fluctuations of at least 30 ° C. Such an environment (with temperature variations of 30 ° C or more) may be, in particular, a geographical location where the installation is constructed, where the average temperature during the summer months is at least 30 ° C higher than during the winter months. Likewise, said environment may be a geographic region in the daytime temperature differs from the nighttime temperature by at least 30 ° C. In such an environment, the advantages of the device according to the invention shown below are particularly pronounced.

Surprisingly, it has been found by the inventors that the device according to the invention, the method according to the invention and the use according to the invention are based on the object underlying the invention by avoiding problems caused by fluctuations in the ambient temperature, in particular inlet temperature fluctuations of combustion air into a gas flow or air preheater or a steam reformer could be avoided at strongly varying ambient temperature. In particular, at very low temperatures, a drop below the dew point in the gas stream or air preheater can be avoided. Likewise, a strong increase in the preheating temperature at high ambient temperatures can be avoided.

The features described in connection with the various embodiments have been found in this context to be particularly suitable.

In the following, the invention will be explained in detail with reference to the figures, wherein in the figures, various process guides are shown.

Further details, features and advantages of the invention will become apparent from the drawings, as well as from the following description of preferred embodiments with reference to the drawings. The drawings illustrate only exemplary embodiments of the invention, which do not limit the inventive concept.

list of figures

• 1 shows a schematic representation of a first embodiment of the inventive apparatus for the production of ammonia.
• 2 shows a schematic representation of a second embodiment of the inventive device for the production of ammonia.

Embodiments of the invention

In the various figures, the same parts are always provided with the same reference numerals and are therefore usually named or mentioned only once in each case.

In the 1 is schematically a part of a device 1 shown. This part of the device 1 includes a gas flow or air preheater 2 , a steam reformer 3 and a heat exchanger system 4 , The heat exchanger system 4 comprises a first heat exchanger element 5 and a second heat exchanger element 6 , In the embodiment shown, the gas flow is by means of a second conduit 10 from the first heat exchanger element 5 to the second heat exchanger element 6 guided. Furthermore, the device comprises a bypass line 11 which will be described in detail below.

The heat exchanger system 4 , the gas flow or air preheater 2 and the steam reformer 3 are in the device 1 arranged such that a gas or a gas mixture, which during operation for the production of ammonia through a first conduit 7 in the part of the device shown 1 is introduced, first the heat exchanger system 4 happens and only then in the gas flow or air preheater 2 and the steam reformer 3 arrives.

According to the invention, it can be provided that the device 1 more than a heat exchanger system 4 includes, for example, another heat exchanger system 4 , between the gas flow and air preheater 2 and the steam reformer 3 is arranged.

The device 1 further comprises means for connecting the first heat exchanger element 5 and the second heat exchanger element 6 can be put into operation separately or used separately. The means for separate startup or use ensures that either the first heat exchanger element 5 or the second heat exchanger element 6 or both heat exchanger elements 5 and 6 can be put into operation at the same time or in operation. For this purpose, in the illustrated embodiment, a bypass line 11 provided with, preferably with the involvement of the first, second and third shut-off valves 14 . 15 and 16 , eg during simultaneous operation of the first heat exchanger element 5 and the second heat exchanger element 6 , a stream containing boiler feed water, steam and / or process condensate, in particular boiler feed water, steam and process condensate, only through the first heat exchanger element 5 but not by the second heat exchanger element 6 is passed through. By passing the stream containing boiler feed water, steam and / or process condensate, in particular boiler feed water, steam and process condensate, through the bypass line 11 to the second heat exchanger element 6 To circumvent, too much heating of this stream can be prevented. This is achieved in the illustrated embodiment in that the bypass line 11 from the second connection line 12 branches off before this in the second Heat exchanger element 6 entry. This bypass line 11 then flows into the third connection line 13 , ie downstream of the second heat exchanger element 6 ,

The in 2 shown part of the device 1 for the production of ammonia comprises the same constituents as already described with reference to 1 described. Furthermore, the embodiment shown comprises a first connection line 8th , by means of the heat exchanger system 4 with another part 9 the device is connected. According to this embodiment it is provided that in said other part 9 the device 1 Boiler feed water and steam accumulate, which are then used to commission the heat exchanger system 4 can be used.

The features of the invention disclosed in the foregoing description, in the claims and in the drawings may be essential both individually and in any combination for the realization of the invention in its various embodiments.

LIST OF REFERENCE NUMBERS

1

Device for the production of ammonia

2

Gas flow or air preheater

3

steam reformer

4

heat exchanger system

5

First heat exchanger element

6

Second heat exchanger element

7

First line for the transport of a gas stream

8th

First connection line

9

Another part of the device in which process condensate, boiler feed water and / or steam are produced

10

Second line for the transport of the gas stream

11

Bypass line

12

Second connection line

13

Third connection line

14

First shut-off valve

15

Second shut-off valve

16

Third shut-off valve

17

Third line for the transport of the gas stream

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102015210801 A1 [0002]
• DE 10057863 A1 [0002]
• DD 225029 A3 [0002]
• DE 102016103321 A1 [0003]

Claims (15)

Device (1), comprising a first line (7) for a gas stream, a steam reformer (3) and a heat exchanger system (4) for controlling the temperature of the gas stream, which is upstream of the steam reformer (3) and the at least one first heat exchanger element (5). and at least one second heat exchanger element (6), wherein the first heat exchanger element (5) and the second heat exchanger element (6) are designed and configured to temper the gas stream which can be supplied via the first line (7), and wherein the heat exchanger system (4) is designed and is set up that only the first heat exchanger element (5), only the second heat exchanger element (6) or both heat exchanger elements can be activated simultaneously or used for controlling the temperature of the gas stream. Device (1) according to Claim 1 , characterized in that the first heat exchanger element (5) and / or the second heat exchanger element (6) comprise or constitute a heat exchanger bundle. Device (1) according to Claim 1 or 2 , further comprising a gas stream preheater (2) connected upstream of the steam reformer (3) and / or downstream of the heat exchanger system (4). Device (1) according to one of the preceding claims, further comprising a first connecting line (8), by means of the process condensate, boiler feed water and / or steam in the first heat exchanger element (5) can be fed, a second connecting line (12) of the first heat exchanger element ( 5) and opens into the second heat exchanger element (6) and by means of the first heat exchanger element (5) entstammendes process condensate, boiler feed water and / or steam to the second heat exchanger element (6) can be fed, and a third connecting line (13) from the second heat exchanger element (5) and can be discharged via the second heat exchanger element (5) entstammendes process condensate, boiler feed water and / or steam. Device (1) according to Claim 4 , further comprising another part (9) of the device (1), which is provided for the emergence or presence of process condensate, boiler feed water and / or steam and which is connected or connectable to the first heat exchanger element (5) via the first connection line (8) is. Device (1) according to one of the preceding claims, characterized in that the first heat exchanger element (5) is connected upstream of the second heat exchanger element (6) and / or that via a second line (10) of the gas flow from the first heat exchanger element (5) to the second heat exchanger element (6) can be forwarded. Device (1) according to Claim 4 . 5 or 6 , further comprising a bypass line (11) for the transport of process condensate, boiler feed water and / or steam, which branches off from the second connecting line (12) and which opens into the third connecting line (13). Device (1) according to one of Claims 4 to 7 , characterized in that the second connecting line (12) between the branch of the bypass line (11) and the second heat exchanger element (6) has a first closing valve (14) and / or that the third connecting line (13) between the second heat exchanger element ( 6) and the mouth of the bypass line (11) has a second closing valve (15) and / or that the bypass line (11) between the branch of the second connecting line (12) and the junction in the third connecting line (13) a third closure valve (16). Device (1) according to one of the preceding claims, further comprising a third conduit (17) via which the gas flow from the second heat exchanger element (6) to the steam reformer (3) can be forwarded. A method for controlling the temperature of a gas stream for a steam reformer, comprising: a) providing a device (1) according to one of Claims 1 to 9 ; b.1) activating the first heat exchanger element (5) or the second heat exchanger element (6) to obtain a first operating mode, or b.2) activating the first heat exchanger element (5) and the second heat exchanger element (6) to a second operating mode to obtain; and c) contacting a gas flow with the first heat exchanger element (5) and the second heat exchanger element (6). Method according to Claim 10 , characterized in that the gas stream is a stream of combustion air. Method according to Claim 10 or 11 , further comprising a further step a '), between the steps a) and b), of determining the ambient temperature, wherein after the step a') the step b.1) is performed when the ambient temperature is in a first temperature range or step b.2) is performed when the ambient temperature is in a second temperature range, wherein the first temperature range is below the second temperature range. Method according to Claim 12 , characterized in that the first temperature range is from -50 ° C to + 5 ° C. Method according to Claim 12 or 13 , characterized in that the second temperature range is more than + 5 ° C to + 50 ° C. Use of a device (1) according to one of Claims 1 to 9 in an environment exposed to temperature fluctuations of at least 30 ° C.

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