EP4368933A1 - Control device for controlling the temperature of a process gas and heat exchanger with a control device - Google Patents

Abstract

The invention relates to a control device for controlling the temperature of a process gas and to a heat exchanger having such a control device. The control device has an outer housing with an inflow and outflow chamber. Cooled process gas can flow into the inflow chamber, while temperature-controlled process gas can flow out of the control device via the outflow chamber. An inner housing, which is fluidically connected to a hot gas line, extends from the inflow chamber through an element that mechanically separates the chambers into the outflow chamber. An axially movable and flow-through piston is arranged within the inner housing. The inner housing and the piston have openings that enable fluidic connections to the hot gas line, the inflow chamber and the outflow chamber. The axial mobility of the piston allows the size of an opening in the piston to be changed, through which cooled process gas can flow into the interior of the piston. This allows the proportions of hot and cooled process gas mixed in the interior of the piston to be changed, thereby achieving control of the process gas temperature.

Description

Technical field of the invention

The invention relates to a control device for controlling the temperature of a process gas, in particular for controlling the temperature of a process gas in a heat exchanger. The invention further relates to a heat exchanger which comprises a control device according to the invention.

State of the art

Heat exchangers for cooling hot process gases, for example from petrochemical plants such as steam reformers, are well known in the art. Such heat exchangers are often designed as tube bundle heat exchangers, which comprise a bundle of indirectly cooled heat exchanger tubes that carry process gas and a bypass tube that is often arranged in the middle and also carries process gas. In the heat exchanger tubes, the hot process gas is cooled by a cooling medium that is guided in a jacket space of the heat exchanger. The process gas guided in the bypass tube is not cooled or is only cooled insignificantly because the bypass tube has a much larger diameter than the heat exchanger tubes. Alternatively, the bypass tube can also be guided outside the jacket of the heat exchanger, so that the portion of the process gas that flows through the bypass tube is not cooled at all.

The cooling medium used, usually water, is converted into steam and can be used elsewhere as heating steam or process steam. Heat exchangers of this type are often also referred to as waste heat boilers.

The temperature of the process gas at the outlet of the heat exchanger is controlled by the amount of process gas that passes through the heat exchanger tubes or the bypass tube. Often, the sole control is the flow rate through the bypass tube, with corresponding control devices arranged within the bypass tube being considered as temperature control devices.

Another solution known from the state of the art is from the EP 0 617 230 B1 Here, the heat exchanger comprises at least two tube bundles, each of which is provided with a dedicated gas flow control device, wherein the flow distribution and the flow rate between the different tube bundles are controlled in order to control the temperature of the process gas at the heat exchanger outlet.

The temperature control devices commonly used in industry and based on flaps regularly do not allow the maximum possible control range to be used, i.e. from no flow through the bypass to full flow through the bypass. This may be due to the fact that the control with flaps creates a pressure drop that shifts the flow from the main cooling surface of the heat exchanger to the bypass (and vice versa). The main cooling surface is defined by the heat exchanger tubes of the heat exchanger, which are indirectly cooled by the cooling medium.

Undesirable (leakage) flows often occur within the heat exchanger itself if the corresponding temperature control device does not seal completely. This is particularly the case with flap-based systems.

In known industrially applied solutions, a complete closure of the bypass pipe (no flow through the bypass pipe) is therefore not easily possible. This limitation of the control range means that the main cooling surface has to be designed larger than actually necessary in order to compensate for this constantly present hot process gas flow through the bypass pipe.

Also, fully opening the bypass pipe while simultaneously interrupting the flow coming from the main cooling surface is not easily possible in known industrially applied solutions. This limitation can limit the overall capacity of the plant for operation at low load, since the required minimum outlet temperature of the process gas from the heat exchanger can only be achieved above a certain (higher) plant load.

In view of the possible failure of the temperature control device and its actuator, which can lead to an undesirable complete opening of the bypass pipe, the maximum opening rate of the bypass pipe should be mechanically limited for the most unfavorable critical design case. This design case is typically defined by the fact that the system in question is operated at full load and, in particular, the heat exchanger pipes have a maximum degree of contamination on the inside. The heat transfer to the process gas is therefore significantly worse than with uncontaminated heat exchanger pipes and the temperature of the cooled process gas is correspondingly higher.

A temperature control device which, in the event of a fault, closes with spring support, for example, and thus reduces the flow through the bypass pipe to zero, is not desirable, since uncontrolled closing of the bypass can reduce the outlet temperature of the process gas (a mixture of uncooled and cooled process gas) below a defined minimum temperature, which is required for the safe operation of downstream system components.

EP1 498 678 discloses a heat exchanger with a bypass pipe which is tightly connected to a guide pipe, wherein a piston designed as a closure member is arranged in the guide pipe so as to be axially displaceable. The piston is double-walled, and cooling channels through which a coolant flows are arranged in the double wall of the piston.

EN 10 2012 007 721 A1 discloses a process gas cooler with lever-controlled process gas cooler flaps. A flap shaft is provided which is connected to a drive body by means of levers and connecting rods in such a way that the gas passage speed and quantity of the process gas through the process gas cooler flaps can be controlled from the outside with the aid of the drive body.

EP 3 159 646 A1 discloses a heat exchanger with a control device which comprises a throttle valve connected to a drive for setting a gas outlet temperature of the heat exchanger to a specific temperature range. An outlet speed and an outlet quantity of the uncooled exhaust gas flow from the bypass pipe can be controlled by a throttle valve arranged at the outlet end of a bypass pipe and adjustable by means of the drive of the control device, wherein the throttle valve is made of a material resistant to high-temperature corrosion in a temperature range sensitive to high-temperature corrosion.

Description of the invention

An object of the present invention is to at least partially overcome the disadvantages of the prior art.

In particular, an object of the present invention is to provide a control device for controlling the temperature of a process gas, which enables the largest possible control range with respect to the process gas temperature to be set.

In particular, it is an object of the present invention to provide a control device for controlling the temperature of a process gas, which comprises the control of the entire temperature range from maximally cooled process gas to uncooled process gas.

Another object of the present invention is to provide a control device for controlling the temperature of a process gas, which minimizes the occurrence of leakage flows with respect to the process gas flow.

A further object of the present invention is to provide a control device for controlling the temperature of a process gas, which, in the event of a technical failure of the control device, does not lead to a state in which a maximum permissible outlet temperature of the process gas can be exceeded.

A further object of the present invention is to provide a heat exchanger with a control device for controlling the temperature of a process gas, which at least partially solves at least one of the aforementioned objects.

A contribution to at least partially fulfilling at least one of the above objects is made by the independent claims. The dependent claims provide preferred embodiments that contribute to at least partially fulfilling at least one of the objects. Preferred embodiments of components of one category according to the invention are, where applicable, also preferred for components of the same name or corresponding components of another category according to the invention.

The expressions "having", "comprising" or "containing" etc. do not exclude that further elements, ingredients etc. may be included. The indefinite article "a" does not exclude that a plural may be present.

• ein Außengehäuse;
• einen innerhalb des Außengehäuses angeordneten Einströmraum für gekühltes Prozessgas, wobei der Einströmraum mit zumindest einer Kaltgasleitung zum Führen des gekühlten Prozessgases fluidisch verbunden ist;
• einen innerhalb des Außengehäuses angeordneten Ausströmraum für temperaturgeregeltes Prozessgas;
• einen Austrittstutzen, welcher sich im Bereich des Ausströmraums durch das Außengehäuse hindurch erstreckt, wobei der Austrittsstutzen zum Ausleiten des temperaturgeregelten Prozessgases aus dem Außengehäuse konfiguriert ist;
• ein mechanisches Trennelement, welches den Einströmraum und den Ausströmraum räumlich voneinander trennt;
• ein Innengehäuse mit einem Innenraum, wobei der Innenraum mit zumindest einer Heißgasleitung zum Führen von heißem Prozessgas fluidisch verbunden ist, wobei
  • sich das Innengehäuse innerhalb des Einströmraums und durch das mechanische Trennelement hindurch in den Ausströmraum erstreckt, wobei
  • das Innengehäuse eine erste Gehäuseeintrittsöffnung umfasst welche so angeordnet ist, dass das heiße Prozessgas in den Innenraum des Innengehäuses einströmbar ist, und wobei
  • das Innengehäuse eine zweite Gehäuseeintrittsöffnung umfasst welche so angeordnet ist, dass gekühltes Prozessgas in den Innenraum des Innengehäuses einströmbar ist, und wobei
  • das Innengehäuse eine Gehäuseaustrittsöffnung umfasst welche so angeordnet ist, dass temperaturgeregeltes Prozessgas aus dem Innenraum
  • des Innengehäuses in den Ausströmraum ausströmbar ist;
• ein durchströmbarer und als Hohlkörper ausgestalteter Kolben mit einem Kolbeninnenraum, wobei der Kolben über einen Stellantrieb innerhalb des Innengehäuses in axialer Richtung verschiebbar ist, wobei der Kolben eine erste Kolbeneintrittsöffnung umfasst welche so angeordnet ist, dass heißes Prozessgas in den Kolbeninnenraum einströmbar ist, und wobei
  • der Kolben eine zweite Kolbeneintrittsöffnung umfasst welche so angeordnet ist, dass gekühltes Prozessgas in den Kolbeninnenraum einströmbar ist, und wobei
  • der Kolben eine Kolbenaustrittsöffnung umfasst welche so angeordnet ist, dass temperaturgeregeltes Prozessgas aus dem Kolbeninnenraum in
  • den Innenraum des Innengehäuses ausströmbar ist, wobei
• die zweite Gehäuseeintrittsöffnung des Innengehäuses und die zweite Kolbeneintrittsöffnung so zueinander angeordnet sind, dass eine frei durchströmbare Querschnittsfläche der zweiten Kolbeneintrittsöffnung durch das Verschieben des Kolbens in axialer Richtung veränderbar ist, wodurch eine Menge an gekühltem Prozessgas regelbar ist, welche über die zweite Gehäuseeintrittsöffnung des Innengehäuses und über die zweite Kolbeneintrittsöffnung in den Kolbeninnenraum einströmbar ist.

According to one aspect of the present invention, a control device for controlling the temperature of a process gas is proposed, comprising

• an outer casing;
• an inflow chamber for cooled process gas arranged within the outer housing, wherein the inflow chamber is fluidically connected to at least one cold gas line for guiding the cooled process gas;
• an outflow chamber for temperature-controlled process gas arranged within the outer housing;
• an outlet nozzle which extends through the outer housing in the region of the outflow space, wherein the outlet nozzle is configured to discharge the temperature-controlled process gas from the outer housing;
• a mechanical separating element which spatially separates the inflow space and the outflow space;
• an inner housing with an interior, wherein the interior is fluidically connected to at least one hot gas line for conducting hot process gas, wherein
  • the inner housing extends within the inflow space and through the mechanical separating element into the outflow space, whereby
  • the inner housing comprises a first housing inlet opening which is arranged such that the hot process gas can flow into the interior of the inner housing, and wherein
  • the inner housing comprises a second housing inlet opening which is arranged so that cooled process gas can flow into the interior of the inner housing, and wherein
  • the inner housing comprises a housing outlet opening which is arranged so that temperature-controlled process gas from the interior
  • of the inner housing into the outflow chamber;
• a piston through which flow can pass and which is designed as a hollow body and has a piston interior, wherein the piston can be displaced in the axial direction within the inner housing via an actuator, wherein the piston comprises a first piston inlet opening which is arranged such that hot process gas can flow into the piston interior, and wherein
  • the piston comprises a second piston inlet opening which is arranged so that cooled process gas can flow into the piston interior, and wherein
  • the piston comprises a piston outlet opening which is arranged so that temperature-controlled process gas from the piston interior into
  • the interior of the inner housing can be flowed out, whereby
• the second housing inlet opening of the inner housing and the second piston inlet opening are arranged relative to one another in such a way that a freely flowable cross-sectional area of the second piston inlet opening can be changed by displacing the piston in the axial direction, whereby an amount of cooled process gas can be regulated, which can flow into the piston interior via the second housing inlet opening of the inner housing and via the second piston inlet opening.

The control device according to the invention has an inner housing which extends from an inflow space of the control device through a mechanical separating element into an outflow space, and a piston designed as a hollow body which is arranged within the inner housing and can be moved in the axial direction within the inner housing. The inner housing has openings through which hot process gas can flow into the inner housing via the first housing inlet opening and cooled process gas can flow into the inner housing via the second housing inlet opening. The inner housing also has at least one further opening, here a housing outlet opening, through which temperature-controlled process gas can flow out of the interior of the inner housing into the outflow space.

The piston, which is designed as a hollow body and through which flow can pass, has corresponding openings. Hot process gas can flow into the piston interior via a first piston inlet opening, in particular after it has passed through the first housing inlet opening of the inner housing, via the first piston inlet opening. Cooled process gas can flow into the piston interior via the second piston inlet opening, in particular after it has passed through the second housing inlet opening of the inner housing. The hot process gas and the cooled process gas are mixed in the piston interior. The temperature-controlled process gas is available through this mixture. This can then first pass through the piston outlet opening, can thereby flow into the interior of the inner housing, and can then pass through the housing outlet opening of the inner housing in particular. The temperature-controlled process gas can then flow out into the outflow chamber, since the inner housing extends through the mechanical separating element into the outflow chamber and the housing outlet opening is arranged in such a way that temperature-controlled process gas can flow out of the interior of the inner housing into the outflow chamber. The temperature-controlled process gas can then flow out of the control device via the outlet nozzle.

The inner housing comprises a first housing inlet opening, which is arranged such that hot process gas can flow into the interior of the inner housing, in particular from the at least one hot gas line into the interior of the inner housing.

The inner housing comprises a second housing inlet opening, which is arranged such that cooled process gas can flow into the interior of the inner housing, in particular from the inflow space into the interior of the inner housing.

The interior of the inner housing is fluidically connected to at least one hot gas line for conducting hot process gas, in particular fluidically connected to the at least one hot gas line via the first housing inlet opening. In addition, the interior of the inner housing is fluidically connected to the inflow space, in particular fluidically connected to the inflow space via the second housing inlet opening. In addition, the interior of the inner housing is fluidically connected to the outflow space, in particular fluidically connected to the outflow space via the housing outlet opening.

The piston comprises a first piston inlet opening, which is arranged such that hot process gas can flow into the piston interior, in particular from the interior of the inner housing into the piston interior.

The piston comprises a second piston inlet opening, which is arranged such that cooled process gas can flow into the piston interior, in particular from the inflow space into the piston interior.

The piston comprises a piston outlet opening which is arranged such that temperature-controlled process gas can flow out of the piston interior, in particular from the piston interior into the interior of the inner housing.

According to one embodiment, the housing outlet opening of the inner housing is arranged adjacent to the outflow space. According to one embodiment, the first housing inlet opening of the inner housing is arranged adjacent to the hot gas line. According to one embodiment, the second housing inlet opening of the inner housing is arranged adjacent to the inflow space.

The piston can be moved in the axial direction within the inner housing. This means that the freely flowable cross-sectional area defined by the second piston inlet opening can be changed. This is the case because the second housing inlet opening and the second piston inlet opening are arranged in such a way that the freely flowable cross-sectional area of the second piston inlet opening can be increased or decreased by axially moving the piston within the interior of the inner housing, or in extreme cases can be closed.

The wall of the inner housing and the second housing inlet opening arranged within the wall of the inner housing make it possible to vary, i.e. change, the freely flowable cross-sectional area of the second piston inlet opening by moving the piston in the axial direction. Accordingly, depending on the degree of opening of the second piston inlet opening and the freely flowable cross-sectional area defined thereby, a lot or little, or no cooled process gas flows into the piston interior. This achieves appropriate temperature control of the process gas.

According to one embodiment, the outside of the jacket-side wall of the piston is in surface contact with the inside of the jacket-side wall of the inner housing. Appropriate seals can be provided to minimize leakage currents between the piston and the inner housing. In principle, the design of the control device with a piston and the defined openings offers the advantage that leakage currents can be largely or completely avoided, which is not the case with devices based on flap systems, for example.

The piston is displaceable in the axial direction via an actuator. In other words, the piston is displaceable along its physical or imaginary longitudinal axis.

According to one embodiment, the first housing inlet opening is arranged in the region of a front wall of the inner housing, in particular a first front wall of the inner housing.

According to one embodiment, the second housing inlet opening is arranged in the region of a shell-side wall of the inner housing.

According to one embodiment, the housing outlet opening is arranged in the region of a further front wall of the inner housing, in particular in the region of a second front wall of the inner housing.

According to one embodiment, the first front wall of the inner housing adjoins the hot gas line. According to one embodiment, the second front wall of the inner housing adjoins the outflow chamber. According to one embodiment, the shell-side wall of the inner housing adjoins the inflow chamber and the outflow chamber.

According to one embodiment, the first piston inlet opening is arranged in the region of a front wall of the piston, in particular a first front wall of the piston.

According to one embodiment, the second piston inlet opening is arranged in the region of a jacket-side wall of the piston.

According to one embodiment, the piston outlet opening is arranged in the region of a front wall of the piston, in particular in the region of a second front wall of the piston.

A "shell-side wall" is understood to mean, regardless of the geometric design of the piston or the inner housing, a wall which runs around the piston and/or the inner housing parallel or substantially parallel to a physical or imaginary longitudinal axis of the piston and/or the inner housing.

A "front wall" is understood to mean a wall, regardless of the geometric design of the piston or the inner housing, which is arranged perpendicular or substantially perpendicular to a physical or imaginary longitudinal axis of the piston and/or the inner housing.

In particular, the inner housing and the piston each have two end walls (a first and a second end wall), and the respective shell-side wall extends between these two end walls.

By moving the piston in the axial direction, not only the freely flowable cross-sectional area of the second piston inlet opening, in particular its size, can be changed. Rather, by moving the piston in the axial direction, the distance between in particular a first front wall of the piston and a first front wall of the inner housing, and thus the distance between the first housing inlet opening and the first piston inlet opening, can also be changed.

The change in the freely flowable cross-sectional area of the second piston inlet opening and the resulting change in the volume flow of cooled process gas flowing into the piston interior results in a corresponding pressure drop, which in turn leads to different pressure levels in the inflow space and the outflow space. In the attempt of the fluidically connected spaces and the flows prevailing therein to compensate for this different pressure level, the volume flow of the hot process gas, which can flow into the piston interior via the first housing inlet opening and the first piston inlet opening, changes accordingly. This also regulates the volume flow of the hot process gas.

The hot process gas emerging from the at least one hot gas line and flowing into the piston interior via the first housing inlet opening and the first piston inlet opening can also be referred to as uncooled process gas or essentially uncooled process gas. The (at least one) hot gas line can also be referred to as a bypass line. This means that the hot gas line in question is not cooled or is only insignificantly cooled, i.e. its cooling is bypassed. This can be due to the fact that the hot process gas in the hot gas line is not cooled by indirect cooling with the aid of a cooling medium, or the hot gas line has such a large diameter that no cooling or only insignificant cooling occurs through indirect cooling via a cooling medium flowing around the hot gas line.

The interior of the inner housing is fluidically connected to the at least one hot gas line. The interior of the inner housing can be connected to the hot gas line directly or, for example, via one or more transition pieces. The control device can also comprise several hot gas lines, for which the same configuration applies. This means that the interior of the inner housing is then fluidically connected to this plurality of hot gas lines, so that the total amount of hot process gas from these hot gas lines can flow into the interior of the inner housing.

The inflow space is fluidically connected to at least one cold gas line, but usually to a plurality of cold gas lines. The cold gas line or the plurality of cold gas lines form/form the main cooling surface of the device for providing the cooled process gas. The cold gas line or the plurality of cold gas lines is/are in particular surrounded by a cooling medium which cools the process gas and thus provides cooled process gas. The cold gas line(s) accordingly carry the cooled process gas.

The term "temperature-controlled process gas" refers in particular to the process gas which can be generated by mixing the hot process gas and the cooled process gas in the piston interior and which, after flowing out of the piston interior into the interior of the inner housing and then flowing out into the outflow space, can be discharged from the device via the outlet nozzle, i.e. can flow out.

Since the device according to the invention advantageously allows the second piston inlet opening to be completely closed so that the freely flowable cross-sectional area of the second piston inlet opening is zero, the "temperature-controlled process gas" for this extreme case can also be a process gas which has the same or substantially the same temperature as the hot process gas.

The device according to the invention also advantageously allows the first piston inlet opening to be completely closed, the control device being configured such that the first piston inlet opening is simultaneously open, according to one embodiment, is completely open. In this extreme case, the "temperature-controlled process gas" can be a process gas that has the same or essentially the same temperature as the cooled process gas.

An embodiment of the control device is characterized in that the first housing inlet opening of the inner housing is arranged within a first front wall of the inner housing, and the first piston inlet opening is arranged within a first front wall of the piston, wherein said openings are arranged relative to one another in such a way that the first housing inlet opening of the inner housing and the first piston inlet opening cannot be flowed through by the hot process gas when there is surface contact between said front walls.

This allows the control device to be operated in such a way that no hot process gas passes through the inner housing in the direction of the outflow chamber. According to a preferred embodiment, the second piston inlet opening is simultaneously fully open.

The first housing inlet opening and the first piston inlet opening can be arranged offset from one another in such a way that the hot process gas cannot flow through these openings when there is surface contact between the said front walls. In other words, these openings are arranged in such a way that they do not overlap when there is surface contact between the said front walls, so that no flow through these openings is possible.

By axially moving the piston, the second piston inlet opening can be completely closed so that only hot process gas passes through the device. The aforementioned embodiment can therefore realize the other extreme case, namely that only hot process gas passes through the device.

The control device thus makes it possible to control the temperature of the process gas over the entire temperature range of the two process gas types, cooled and hot process gas.

According to one embodiment, the second housing inlet opening and the second piston inlet opening are therefore arranged in such a way, in particular the second housing inlet opening in the region of the jacket-side wall of the inner housing and the second piston inlet opening in the region of the jacket-side wall of the piston, that when the first front wall of the inner housing and the first front wall of the piston are in surface contact, the freely flowable cross-sectional area of the second piston inlet opening corresponds to the maximum opening area of the second piston inlet opening.

A preferred embodiment of the control device is characterized in that the first housing inlet opening of the inner housing and/or the first piston inlet opening are/is designed as an annular gap.

A preferred embodiment of the control device is characterized in that the first front wall of the piston has a sealing element mechanically connected to this front wall.

This allows leakage currents on the hot gas line side to be reduced to a minimum.

An embodiment of the control device is characterized in that the piston is mechanically connected to the actuator via a shaft.

• im Innenraum des Innengehäuses und außerhalb des Kolbens angeordnet ist, oder
• innerhalb des Ausströmraums und außerhalb des Innengehäuses angeordnet ist,

und dabei so angeordnet ist, dass ein vollständiges Verschließen der Öffnung, welche über die frei durchströmbare Querschnittsfläche der zweiten Kolbeneintrittsöffnung definiert ist, verhinderbar ist.A preferred embodiment of the control device is characterized in that the piston is mechanically connected to the actuator via a shaft, and the shaft has a mechanical stop element firmly connected to it, wherein the stop element

• is arranged in the interior of the inner housing and outside the piston, or
• is arranged inside the outflow chamber and outside the inner housing,

and is arranged in such a way that a complete closure of the opening, which is defined by the freely flowable cross-sectional area of the second piston inlet opening, can be prevented.

The mechanical stop element is firmly connected to the shaft, i.e. connected to the shaft in such a way that the position of the stop element cannot be changed during operation of the control device. According to one example, the stop element is connected to the shaft in a force-locking manner, for example via a screw connection or a clamp connection.

The stop element can be arranged in the interior of the inner housing and outside the piston. According to this embodiment, the stop element can, according to one example, strike against a wall of the inner housing during a corresponding stroke of the piston, in particular strike against the inside of the second end wall of the inner housing.

The stop element can be arranged inside the outflow chamber and outside the inner housing. According to this embodiment, the stop element can strike against a wall of the outer housing, in particular strike against an inner side of a wall of the outer housing, in accordance with one example, when the piston is stroked accordingly.

The stop element is arranged in such a way that a complete closure of the opening, which defines the freely flowable cross-sectional area of the second piston inlet opening, can be prevented or is prevented. In other words, the stop element is mechanically connected firmly to the shaft at a defined position, whereby the positioning of the stop element does not allow the second piston inlet opening to be closed, which would mean that cooled process gas from the inflow space would no longer be able to flow through it.

If the control device fails, the stop element prevents the connection between the inflow chamber and the piston interior from closing completely, meaning that only hot process gas from the hot gas line would flow through the control device. This prevents temperatures from becoming too high in the area of the outlet of the control device, particularly in the area of the outlet nozzle. Temperatures that are too high at the outlet of the device can damage devices located downstream of the control device.

A preferred embodiment of the control device is characterized in that the mechanical stop element can be changed in its position along the shaft in the axial direction, in particular its position can be changed depending on the prevailing operating conditions.

According to this embodiment, the mechanical stop element is not connected to the shaft by a material connection, such as a welded connection. Rather, the stop element is connected to the shaft by a detachable connection, for example by a force-fit connection, so that the position of the stop element can be changed, for example during maintenance work on a relevant system.

For example, it may be useful to enlarge the freely flowable cross-sectional area defined by the second piston inlet opening in the event that the stop element stops (if the control device fails) as the cold gas lines become increasingly dirty or corroded. Such progressive contamination or corrosion means that the process gas in question is cooled less, which makes it advantageous to increase the volume flow of the cooled process gas accordingly. Increasing the volume flow through the cold gas lines improves the heat transfer from gas to water (coolant). This compensates for the insulating effect of a layer of dirt that primarily forms on the outside of the cold gas lines, i.e. on the coolant side. Similar considerations must be made with regard to the hot gas line(s) that carry the uncooled process gas.

A preferred embodiment of the control device is therefore characterized in that the mechanical stop element can be changed in its position along the shaft in the axial direction depending on the temperature of the cooled process gas and/or the temperature of the uncooled process gas.

For the above reasons, a preferred embodiment of the control device is advantageously characterized in that the mechanical stop element can be changed in its position along the shaft in the axial direction depending on the degree of contamination of the at least one cold gas line and/or the degree of contamination of the at least one hot gas line.

A preferred embodiment of the control device is characterized in that the piston can be rotated in the radial direction via an actuator, so that the freely flowable cross-sectional area of the second piston inlet opening can be changed by rotating the piston in the radial direction.

According to this embodiment, a further degree of freedom is introduced, which relates to the variability of the freely flowable cross-sectional area defined by the second piston inlet opening.

This allows the shaft to be rotated in a radial direction, for example, when the stop element has reached its end position, i.e. the position of the mechanical stop. This allows the second piston inlet opening to be closed even when the stop is reached, which enables the temperature of the temperature-controlled process gas to be increased to the maximum temperature (corresponding to the temperature of the hot process gas) even at the mechanical stop. This is possible independently of the operation of the actuator, which controls the axial displacement of the piston. This enables the mechanical stop to be adjusted depending on the contamination rate of the cold gas lines and hot gas line(s).

A preferred embodiment of the control device is characterized in that the piston is displaceable in the axial direction via a first actuator and the piston is rotatable in the radial direction via a second actuator.

This means that the axial displacement and the radial displacement can be carried out independently of each other. For example, the radial rotation of the piston by the second actuator is still possible even if the first actuator has failed and the piston is in the position of the mechanical stop.

A preferred embodiment of the control device is characterized in that the piston has the shape of a straight hollow cylinder.

According to this embodiment, the piston has the shape of a straight hollow cylinder, or the shape of a substantially straight hollow cylinder, or substantially the shape of a straight hollow cylinder.

To simplify construction and maintenance, the piston is preferably shaped as a straight hollow cylinder. This geometry enables complete closure of the opening(s) to at least one hot gas line while simultaneously ensuring low leakage rates with respect to the space between the piston and the inside of the inner housing.

Alternatively, the piston has the shape of a hollow truncated cone, with the diameter of the truncated cone decreasing along the flow direction of the gases flowing through the piston interior.

This allows the surface of the piston to be efficiently sealed against the inside of the inner housing, especially at large strokes (distance between the front walls of the inner housing and the piston), which allows lower leakage rates to be achieved than in the case of a straight hollow cylinder design.

At least one of the aforementioned objects is further at least partially achieved by a heat exchanger having a control device according to one of the aforementioned embodiments, wherein the heat exchanger has a plurality of cold gas lines arranged parallel to one another and configured as a tube bundle, which are fluidically connected to the inflow space, and wherein the heat exchanger has a centrally arranged hot gas line which has a larger diameter than the cold gas lines.

The heat exchanger comprises the control device according to the invention, or the control device forms part of the heat exchanger. The heat exchanger is preferably a tube bundle heat exchanger. The heat exchanger has a centrally arranged hot gas line, but according to one embodiment can also comprise several centrally arranged hot gas lines. The hot gas line or hot gas lines and the cold gas lines can be arranged coaxially. The hot gas line can also be referred to as a bypass line. This means that the cooling of the process gas in the hot gas line is either completely or essentially completely bypassed.

A preferred embodiment of the heat exchanger is characterized in that the cold gas lines each have an inlet end and an outlet end, and the hot gas line has an inlet end and an outlet end, wherein the outlet ends of the cold gas lines merge into the inflow space and the outlet end of the hot gas line merges into the inner housing, and wherein the inlet ends of the cold gas lines and the inlet end of the hot gas line merge into a process gas inflow space, wherein the process gas inflow space has a process gas inlet nozzle.

Hot process gas can flow into both the hot gas line and the cold gas lines via the process gas inflow chamber. Part of the hot process gas is then cooled in the cold gas lines, part flows through the hot gas line and is not cooled or is essentially not cooled.

At least one of the aforementioned objects is further at least partially achieved by the use of the control device according to one of the aforementioned embodiments of the control device or according to one of the aforementioned embodiments of the heat exchanger for cooling synthesis gas from a steam reformer or an autothermal reformer.

Example

The invention is explained in more detail below by means of exemplary embodiments. In the following detailed description, reference is made to the accompanying drawings, which illustrate specific embodiments of the invention. In this context, direction-specific terminology such as "top", "bottom", "front", "back", etc. is used with reference to the orientation of the figure described. Since components of embodiments can be positioned in a variety of orientations, the direction-specific terminology is for illustrative purposes and is in no way limiting. Those skilled in the art will appreciate that other embodiments may be used and structural or logical changes may be made without departing from the scope of the invention. The following detailed description is therefore not to be understood in a limiting sense, and the scope of the embodiments is defined by the appended claims. The drawings are not to scale unless otherwise stated.

Figur 1

eine seitliche Querschnittansicht einer erfindungsgemäßen Regelvorrichtung bei geschlossener erster Kolbeneintrittsöffnung und vollständig geöffneter zweiter Kolbeneintrittsöffnung,

Figur 2

eine seitliche Querschnittansicht einer erfindungsgemäßen Regelvorrichtung bei geöffneter erster Kolbeneintrittsöffnung und vollständig geschlossener zweiter Kolbeneintrittsöffnung, und

Figur 3

eine seitliche Querschnittansicht einer erfindungsgemäßen Regelvorrichtung mit mechanischem Anschlagelement, bei geöffneter erster Kolbeneintrittsöffnung und teilweise geöffneter zweiter Kolbeneintrittsöffnung.

It shows

Figure 1

a side cross-sectional view of a control device according to the invention with the first piston inlet opening closed and the second piston inlet opening fully open,

Figure 2

a side cross-sectional view of a control device according to the invention with the first piston inlet opening open and the second piston inlet opening completely closed, and

Figure 3

a side cross-sectional view of a control device according to the invention with a mechanical stop element, with the first piston inlet opening open and the second piston inlet opening partially open.

In the Figures 1 to 3 The same elements are each provided with the same reference numbers.

Figure 1 shows a simplified representation of a lateral cross-sectional view of the control device according to the invention with the first piston inlet opening closed and the second piston inlet opening completely open.

The control device 1 has an outer housing 10, which comprises an inflow space 11 and an outflow space 14. The inflow space 11 and the outflow space 14 are spatially separated from one another by a mechanical separating element 17. An inner housing 18 is arranged within the outer housing 10, which extends within the inflow space 11, through the mechanical separating element 17, and within the outflow space 14. The inner housing is fluidically connected to a hot gas line 20, the inflow space 11, and the outflow space 14 via several openings 22, 23, and 24 (opening 24 not shown). The inner housing 18 has an interior space 19. The openings 22, 23 and 24 are located within the wall of the inner housing and thus establish fluidic connections between the interior 19 of the inner housing 18 and the hot gas line 20, the inflow space 11 and the outflow space 14. The control device 1 also has a plurality of cold gas lines 13 which are fluidically connected to the inflow space. While cooled process gas 12 flows through the cold gas lines 13, hot process gas 21 flows through the hot gas line 20. Due to the large diameter of the hot gas line 20 compared to the small diameter of the cold gas lines 13, the hot process gas 21 in the hot gas line 20 is only insignificantly cooled. The outlet ends of the cold gas lines 13 (not shown) and the outlet end of the hot gas line 20 (not shown) are fixed within the holes (not shown) of a perforated plate 37 which extends over the cross-sectional area of the outer housing. A cooling medium flows around the cold gas lines 13 and the hot gas line 20, thereby cooling the process gas flowing in the cold gas lines 13.

The control device 1 can also be understood as part of a tube bundle heat exchanger with a centrally arranged bypass pipe, here the hot gas line 20. As is known to the person skilled in the art, such a heat exchanger has a corresponding inlet connection and an outlet connection for the cooling medium. The connections are not shown in the figures. The cooling medium is in particular cooling water, which is discharged from the heat exchanger as steam by cooling the hot process gas and can then be used as heating steam or process steam.

The hot gas line 20 extends through the perforated plate 37 into the inflow space 11 and is thereby mechanically firmly connected to the inner housing 18. The part of the hot gas line 20 which extends through the inflow space 14 can also be understood not as part of the hot gas line 20, but as a connecting piece or transition piece between the hot gas line 20 and the inner housing 18. The inner housing 18 has a first front wall 31 in which a first housing inlet opening 22 designed as an annular gap is arranged. The hot process gas 21 can flow into the interior 19 of the inner housing 18 through the first housing inlet opening 22 when the opening 22 is open and thus flowable. The inner housing 18 also has a housing outlet opening 24 (opening not shown) which is arranged within a second front wall 32 of the inner housing. A temperature-controlled process gas 15 can flow out of the interior 19 of the inner housing 18 into the outflow chamber 14 via the housing outlet opening 24. The temperature-controlled process gas 15 can then be discharged from the control device 1 via an outlet nozzle 16 from the outflow chamber 14. The inner housing 18 also has a second housing inlet opening 23, which is arranged within the shell-side wall 38 of the inner housing. As shown in the figure, several such openings 23 can be present. A piston 25 is arranged in the interior 19 of the inner housing 18, which is designed as a cylindrical hollow body and is connected to an actuator 27a and a further actuator 27b via a shaft 35. The piston 25 has a piston interior 26. The shaft is mechanically firmly connected to the piston, i.e. the piston 25 and the shaft 35 form a mechanical unit which can be moved via the actuators 27a and 27b.

Via the actuator 27a, the piston 25 can be moved in the axial direction, i.e. along its longitudinal axis, which is partially formed by the shaft 35. This type of movement is indicated by the arrow on both sides of the actuator 27a.

The piston 25, designed as a hollow body, has a plurality of openings 28, 29 and 30 through which flow can pass through the piston. A first piston inlet opening 28 is arranged within a first front wall 33 of the piston 25. Hot process gas 21 can flow into the piston interior 26 through the first piston inlet opening 28 after passing through the first housing inlet opening 22 when the piston 25 is in the appropriate position. A second piston inlet opening 29 is arranged within a jacket-side wall 39 of the piston. As shown in the figure, a plurality of such openings 29 can be present. Cooled process gas 12 can flow into the piston interior 25 through the second piston inlet opening 29 after passing through the second housing inlet opening 23 when the piston 25 is in the appropriate position.

By moving the piston 25 in the axial direction by the actuator 27a, the freely flowable cross-sectional area of the second piston inlet opening can be changed. This means that the second housing inlet opening 23 and the second piston inlet opening 29 are arranged in relation to one another in such a way that the size of the second piston inlet opening and thus the amount of the freely flowable cross-sectional area of this opening can be changed.

In the example according to Figure 1 the piston 25 is in a position in which the second piston inlet opening 29 is opened as wide as possible, i.e. the entire opening or the entire cross-sectional area of this opening is available for the cooled process gas 12 to flow through. According to the example of the Figure 1 the second housing inlet opening 23 and the second piston inlet opening 29 are congruently positioned one above the other. The flow-through areas defined by the second housing inlet opening 23 and the second piston inlet opening 29 do not have to be the same size, but can also be different sizes. The only important thing is that both openings are arranged in relation to each other in such a way that the freely flow-through cross-sectional area of the second piston inlet opening 29 can be changed.

In the example according to Figure 1 the piston 25 is also in a position in which access to the hot gas line 20 is closed. This is due to the fact that the first housing inlet opening 22 and the first piston inlet opening 28 are arranged in relation to one another in such a way that the hot process gas 21 cannot flow through them when there is surface contact between the first front wall 31 of the inner housing 18 and the first front wall 33 of the piston 35. This is achieved by the fact that the corresponding openings 22 and 28 are offset from one another and do not overlap when there is surface contact.

Figure 2 shows a side cross-sectional view of a control device according to the invention with the first piston inlet opening open and the second piston inlet opening completely closed.

In the example according to the Figure 2 the control device 1 is shown with a position of the piston 25 in which access to the second piston inlet opening 29 is completely closed. At the same time, access to the hot gas line 20 is completely open, which enables a maximum flow of hot process gas 21. The flow of cooled process gas 12 is thus zero, or limited to negligible leakage flows. If the piston 25 is continuously moved to the left via the actuator 27a, the freely flowable cross-sectional area of the second piston inlet opening 29 is continuously increased and the flow of cooled process gas 12 is therefore also continuously increased. The pressure drop between the inflow space 11 and the outflow space 14 also changes, which also changes the amount of hot process gas 21 that can flow into the piston 25, i.e. the flow of hot process gas 21 is continuously reduced.

The hot process gas 21 and the cooled process gas 12 are mixed in the piston interior, resulting in the temperature-controlled process gas 15. This flows into the outflow chamber via the piston outlet opening 30 and the housing outlet opening 24. As already mentioned above, the term "temperature-controlled process gas" 15 is also used when access to the hot gas line 20 or to the inflow chamber 11 is closed depending on the position of the piston 25.

The control device 1 also has a second actuator 27b, by means of which the piston can be moved in the radial direction, i.e. rotated about its longitudinal axis. This second actuator 27b thus represents a further degree of freedom with regard to the variability of the freely flowable cross-sectional area of the second piston inlet opening 29. If the second piston inlet opening is, for example, a circular opening, this opening 29 can be closed or at least further reduced by the radial movement even if the openings 23 and 29 are located one above the other. The radial movement of the piston 25 via the shaft 35 by means of the second actuator 27b is indicated by the semicircular arrow.

Figure 3 shows a side cross-sectional view of a control device according to the invention with a mechanical stop element, with the first piston inlet opening open and the second piston inlet opening partially open.

Figure 3 shows an example of a control device 2 with an integrated mechanical stop element 36. The stop element 36 is arranged within the inner housing 18, i.e. in the interior 19 of the inner housing 18, and is firmly connected to the shaft 35. This fixed connection can be realized, for example, by a force-locking connection such as a screw connection. The decisive factor is that the connection is a detachable connection. The stop element 36 is therefore preferably not connected to the shaft 35 via a material-locking connection such as a welded connection. A detachable connection enables the position of the stop element 36 to be changed depending on certain prevailing operating parameters, such as the degree of contamination of the hot gas line 20 and the cold gas lines 13. The stop element 36 ensures that the shaft 35 together with the piston 25 cannot be moved so far that the second piston inlet opening 29 is closed, even in the event of a technical failure of the control device 2, in particular of the actuator 27a. This prevents only hot process gas 21 from leaving the control device 2 via the outlet nozzle 16. This may be desirable depending on the respective system, since process gases that are too hot can damage system components arranged downstream. If it is nevertheless desirable to completely close the second piston inlet opening 29 in such a case, this is possible via the second actuator 27b.

List of reference symbols

1, 2

Control device

10

Outer casing

11

Inflow chamber

12

Cooled process gas

13

Cold gas line

14

Outlet chamber

15

Temperature-controlled process gas

16

Outlet nozzle

17

Mechanical separator

18

Inner casing

19

Interior of the inner housing

20

Hot gas line

21

Uncooled process gas

22

First housing entry opening

23

Second housing entry opening

24

Housing outlet opening

25

Pistons

26

Piston interior

27a

First actuator

27b

Second actuator

28

First piston inlet opening

29

Second piston inlet opening

30

Piston outlet opening

31

First front wall inner housing

32

Second front wall inner housing

33

First front wall piston

34

Second front wall piston

35

Wave

36

Stop element

37

Perforated plate

38

Shell side wall inner casing

39

Shell side wall piston

Claims (15)

Control device (1, 2) for controlling the temperature of a process gas, comprising - an outer casing (10); - an inflow chamber (11) for cooled process gas (12) arranged within the outer housing, wherein the inflow chamber is fluidically connected to at least one cold gas line (13) for guiding the cooled process gas; - an outflow chamber (14) arranged within the outer housing for temperature-controlled process gas (15); - an outlet nozzle (16) which extends through the outer housing in the region of the outflow space, wherein the outlet nozzle is configured to discharge the temperature-controlled process gas from the outer housing; - a mechanical separating element (17) which spatially separates the inflow space and the outflow space from one another; - an inner housing (18) with an interior space (19), wherein the interior space is fluidically connected to at least one hot gas line (20) for guiding hot process gas (21), wherein the inner housing extends within the inflow space and through the mechanical separating element into the outflow space, wherein the inner housing comprises a first housing inlet opening (22) which is arranged such that the hot process gas can flow into the interior space of the inner housing, and wherein the inner housing comprises a second housing inlet opening (23) which is arranged such that cooled process gas can flow into the interior of the inner housing, and wherein the inner housing comprises a housing outlet opening (24) which is arranged such that temperature-controlled process gas can flow out of the interior of the inner housing into the outflow space; - a piston (25) designed as a hollow body through which fluid can flow and with a piston interior (26), wherein the piston can be displaced in the axial direction within the inner housing via an actuator (27a), wherein the piston comprises a first piston inlet opening (28) which is arranged such that hot process gas can flow into the piston interior, and wherein the piston comprises a second piston inlet opening (29) which is arranged such that cooled process gas can flow into the piston interior, and wherein the piston comprises a piston outlet opening (30) which is arranged so that temperature-controlled process gas can flow out of the piston interior into the interior of the inner housing, wherein - the second housing inlet opening of the inner housing and the second piston inlet opening are arranged relative to one another in such a way that a freely flowable cross-sectional area of the second piston inlet opening can be changed by displacing the piston in the axial direction, whereby an amount of cooled process gas can be regulated which can flow into the piston interior via the second housing inlet opening of the inner housing and via the second piston inlet opening. Control device according to claim 1, characterized in that the first housing inlet opening of the inner housing is arranged within a first end wall (31) of the inner housing, and the first piston inlet opening is arranged within a first end wall (33) of the piston, wherein said openings are arranged relative to one another in such a way that the first housing inlet opening of the inner housing and the first piston inlet opening cannot be flowed through by the hot process gas when the said end walls are in surface contact. Control device according to claim 2, characterized in that the first housing inlet opening of the inner housing and/or the first piston inlet opening are/is designed as an annular gap. Control device according to claim 2 or 3, characterized in that the first end wall of the piston has a sealing element mechanically connected to this end wall. Control device according to one of the preceding claims, characterized in that the piston is mechanically connected to the actuator via a shaft (35), and the shaft has a mechanical stop element (36) firmly connected to it, wherein the stop element - is located inside the inner housing and outside the piston, or - is located inside the outflow chamber and outside the inner housing, and is arranged in such a way that a complete closure of the opening, which is defined by the freely flowable cross-sectional area of the second piston inlet opening, can be prevented. Control device according to claim 5, characterized in that the mechanical stop element can be changed in its position along the shaft in the axial direction, in particular its position can be changed depending on the prevailing operating conditions. Control device according to claim 6, characterized in that the mechanical stop element can be changed in its position along the shaft in the axial direction depending on the temperature of the cooled process gas and/or the temperature of the uncooled process gas. Control device according to one of claims 6 or 7, characterized in that the mechanical stop element can be changed in its position along the shaft in the axial direction depending on the degree of contamination of the at least one cold gas line and/or the degree of contamination of the at least one hot gas line. Control device according to one of the preceding claims, characterized in that the piston is rotatable in the radial direction via an actuator (27b), so that the freely flowable cross-sectional area of the second piston inlet opening can be changed by rotating the piston in the radial direction. Control device according to claim 9, characterized in that the piston is displaceable in the axial direction via a first actuator (27a) and the piston is rotatable in the radial direction via a second actuator (27b). Control device according to one of the preceding claims, characterized in that the piston has the shape of a straight hollow cylinder. Control device according to one of claims 1 to 10, characterized in that the piston has the shape of a hollow truncated cone, the diameter of the truncated cone decreasing along the flow direction of the gases flowing through the piston interior. Heat exchanger, comprising a control device (1, 2) according to one of claims 1 to 12, wherein the heat exchanger has a plurality of cold gas lines (13) arranged parallel to one another and configured as a tube bundle, which are fluidically connected to the inflow space, and wherein the heat exchanger has a centrally arranged hot gas line (20) which has a larger diameter than the cold gas lines. Heat exchanger according to claim 13, characterized in that the cold gas lines each have an inlet end and an outlet end, and the hot gas line has an inlet end and an outlet end, wherein the outlet ends of the cold gas lines merge into the inflow space and the outlet end of the hot gas line merges into the inner housing, and wherein the inlet ends of the cold gas lines and the inlet end of the hot gas line merge into a process gas inflow space, wherein the process gas inflow space has a process gas inlet nozzle. Use of the control device according to one of claims 1 to 12 or of the heat exchanger according to one of claims 13 or 14 for cooling synthesis gas from a steam reformer or an autothermal reformer.

Images