EP2310747B1 - Method for continuously conditioning gas, preferably natural gas - Google Patents

Description

The invention relates to a method for the continuous conditioning of gas, preferably natural gas, before it is fed into a pipeline, in particular a pipeline network for supplying consumers, in which the pressurized gas removed from a memory, and before and after its relaxation is heated to a predetermined temperature by a diverted partial flow of the gas stored is mixed with oxygen and the fuel gas thus formed is burned and in which the accumulated heat energy, the stored gas is heated.

Ergas must be heated during its withdrawal from underground storage to compensate for the Joule-Thomson effect before the pressure reduction. One possibility is a method of the aforementioned type, which in the EP 0 920 578 is described. The heat required for heating is provided by catalytic "combustion" of a portion of the Ausspeicherstroms in a reactor. In the known method by the catalytic reaction of oxygen with fuel gas, for. As natural gas L, achieved in the strong substoichiometric mixing range at the catalyst directly in the gas stream temperatures of up to 400 ° C. The heat is used by mixing the hot combustion gases as a partial gas stream in the main gas stream behind the reactor. The end The gas discharged from the storage tank has a pressure of 70 - 150 bar at a temperature of 5 - 30 ° C.

Catalytic "combustion" in the reactor requires an activation temperature of at least 180 ° C - 250 ° C. In order to reach the temperature, the diverted partial flow of the gas stored is mixed with oxygen and is catalytically burned. The heat released in this case can then in turn be used to heat the stored gas to a temperature which is suitable for compensating for the Joule-Thomson effect which occurs during the expansion and the associated cooling.

In the known method, there is always a risk that the reactor in which the catalytic conversion of the fuel gas proceeds with the release of heat, is cold blown by the low temperatures of the stored natural gas, so that the oxygen remains in the fuel gas, without being reacted. This can be excluded in principle by the fact that the fuel gas-oxygen mixture is heated to the catalyst activation temperature of 180 - 250 ° C prior to relaxation. Without this preheating the known process gets out of balance after a short time, because the activation temperature in the reactor is exceeded. On the other hand, the ignition in a process of metering oxygen into fuel gases, here natural gas, never be completely excluded. This risk becomes even higher if the oxygen remains in the fuel gas when it falls below the activation temperature of the reactor, because it was not reacted. The oxygen concentration increases and thus the risk of auto-ignition at the high pressures occurring here. A safe execution of the known method is not guaranteed.

After EP 0 529 474 It is also known to cool the exhaust gases of the catalytic combustion and to return a portion of the cooled exhaust gases via a return line to a fuel gas / Abgasmischen, whereby the Selbstzündgefahr should be reduced.

The invention has for its object to improve the known method so that a safe operation for conditioning is possible.

This object is achieved by the features of claim 1. Further developments and advantageous embodiments will become apparent from the claims 2 to 9.

The constructive implementation of the process technology according to the invention, using the cooling of natural gas during expansion, in the design of the inlets of the expansion valves for cooling and mixing the gas streams before and after the second container (reactor), coupled with dew point measurements at the inlet and outlet of the natural gas in the system provided for carrying out the method allow a targeted procedure for the separation of water from the natural gas and thus the gas conditioning with respect to the Wasserdampftaupunkt or the drying of the natural gas.

This process is further coupled with special separator stages with multicyclones and filter elements as well as with condensate discharges for optimal and safe operation and reduction and contamination of condensate (water) precipitated from natural gas with higher hydrocarbon chains.

This represents a significant economic advantage over the known technology for gas conditioning or conditioning. The resulting condensates are easily separated by a downstream filter of hydrocarbons and are easy and inexpensive to dispose of.

The user of the method according to the invention also benefits from the compact design of a system designed for its implementation in terms of space and plant costs, since all the essential parts of a Ausspeicheranlage consisting of separators, preheating, gas pressure reduction and measurement, gas drying and filtering already in the process engineering integrated, which can be constructively unite in a device.

The absence of moving parts, pumps and similar equipment reduces the operating and maintenance costs of performing the process. The combination of the catalytic conversion of oxygen and hydrocarbons to the catalyst of the reactor vessel, with the expansion directly into the mixing space and / or tangential to the cooling at the inlet around the second vessel, the reactor, effect the optimum precipitation of the condensates and the condensation of the water vapor from the catalytic conversion, without local generation of exhaust gases, with a computational efficiency of <1.1, using the condensation and separation of water vapor, as well as the heat of condensation.

The method advantageously takes advantage of the high inlet pressures of the natural gas and the usable cooling caused by the expansion to supply line pressure to separate the condensates from the natural gas. The method according to the invention is supported by the direct preheating in the first container and in the region of the supply lines into the second container, through which immediate dissolution or suppression of the gas hydrate formation can be utilized. If the use of the pressure gradient is not sufficient to achieve complete condensation, then an absorbent for binding the water vapor in the natural gas stream can be injected into the inlet of the main gas stream into the second tank. The absorbent, z. As triethylene glycol is discharged together with the condensate from the conditioning process and can, like the condensate, collected and then processed, so it is reusable.

In terms of process technology, the control of the conditioning process takes place dewpoint-controlled via the inlet and outlet of the natural gas in the am Entry and exit of the natural gas in a device provided for carrying out the method according to the invention installed dew point measurements by selective variation of the oxygen addition and variation of the flow control over the control valves of the main gas flow to the tangential inlet via the supply lines and to the reactor or the addition directly into the mixing zone or the mixing space between the second container and a downstream separator. Thus, the method is particularly safe, especially since the addition of oxygen in the mixing container can still be assigned a safety device with nitrogen extinguishing.

An embodiment of the method according to the invention, from which further inventive features arise, is shown schematically in the drawing in the form of a flow chart.

The natural gas to be conditioned, before being fed into a pipeline 1 of a pipeline network, not shown, for the supply of consumers, taken from a memory also not shown and flows out of the memory via a main line 2 from. The flow direction is indicated here by arrows.

In the branch point 3 is from the main line 2 from a branch line 4, via which a partial flow of the natural gas stored in a mixing vessel 5 is passed.

Via the line 6 5 gaseous oxygen is passed into the mixing vessel, which mixes in the mixing vessel 5 with the supplied via the branch line 4 natural gas partial stream.

In the mixing vessel 5, a fuel gas is thus formed, which is passed through the fuel gas line 7 into the first container 8 with closed container walls 9. The first container forms the preheating station, which is designed as a jet pump, which has a driver nozzle 10 and a catching nozzle 11 having. About the driver nozzle 10, the supplied from the fuel gas line 7 under relatively high pressure fuel gas is injected into the first container 8, wherein the emerging from the driver nozzle 10 free jet is collected by the catching nozzle 11 and mixed on his way with befindlichem in the container 8 exhaust and heated, which is supplied via the suction line 12 as a partial exhaust stream from a catalytic combustion process.

The heated fuel gas mixture flows via the mixing line 13 into a reactor chamber 14 of a second container 15, which is designed as a housing enclosing the reactor 14, a mixing chamber 17 and a separator 18.

The jet pump located in the first container 8 sucks hot natural gas out of the reactor 14 via the suction line 12 and mixes it with the cold fuel gas which flows in from the mixing container 5.

The entering from the main line 2 by preconcentration of expansion valves via the leads 21 and 22 in the housing of the second container 15 cold natural gas flows around the reactor vessel 14, wherein it around the reactor vessel 14 around with guide elements 23 which are arranged helically arranged on the circumference becomes.

The second vessel 14 contains a reactor bed in the form of a bed of catalytic granules vaporized with palladium and / or platinum.

Preheated fuel gas enters the second container 14 via the preheating line 13. The temperature is adjusted by suitable control technology so that an activation temperature of the reactor bed in the second container 14 of about 180 ° C to 250 ° C is reached.

The fuel gas burns catalytically and the heat released in the process is in part via the outer circumferential surface to the second container 14 flowing around, transferred via the leads 21 and 22 supplied cold natural gas.

Device measures are taken to ensure that the natural gas preheated via the outer jacket surface is mixed with the cold natural gas supplied via the supply line 22.

The catalytically burned fuel gases enter from the second container 14 directly into the mixing chamber 17, where they mix with the flowing through the supply line 22 cold natural gas.

By this cooling, on the one hand on the outer surface of the reactor 14, on the other hand by the passage of the hot fuel gases in the cold natural gas in the mixing chamber 17, immediately hydrate formation with appropriate condensate, which are discharged through the condensate drainages 23 and 24.

The separator 18 is flowed through from the mixing chamber 17 derived, now heated natural gas, which precipitated in the separator 18 more condensate and the natural gas is also filtered.

The separator 18 also has a condensate drain 25.

Denoted by 26 is a device for assisting the deposition of condensate, by means of which an absorbent, for. B. triethylene glycol for binding the water vapor in the gas stream of the supply lines 21 and 22 is injected.

27 denotes a safety device, via which the oxygen supply 6 is controlled and regulated.

Dew point sensors at the entrance and exit of the apparatus for carrying out the method are designated 28 and 29. The links with pressure sensors and temperature sensors are indicated here by dashed lines only.

Claims (9)

1. A method for continuously conditioning gas, preferably natural gas, before it is fed into a pipeline (1), in particular a network of pipelines for supplying consumers, in which the pressurized gas is removed from a storage tank, decompressed and heated to a predetermined temperature either before or after its decompression, in that a diverted partial flow of the natural gas removed from storage is mixed with oxygen and the resulting combustion gas is catalytically combusted and in which the gas removed from storage is heated using the heat energy thereby occurring,
   characterized in
   that a partial flow is diverted from a flow of hot flue gas released during catalytic combustion and
   conducted together with the cold combustion gas into a first container (8),
   that the combustion gas in the first container (8) is mixed with the partial flow of flue gas supplied and thereby heated and
   that the mixture of flue gas and combustion gas from the first container (8) preheated in this manner is diverted into a second container (15) in which it undergoes catalytic combustion, with the heat from which the gas removed from storage which is to be conditioned is heated to the desired temperature in each case.
2. The method according to claim 1, characterized in that the natural gas removed from storage is immediately decompressed before being introduced into the second container (15).
3. The method according to claim 2, characterized in that the decompressed natural gas is divided into partial flows, at least one of which is introduced around a reactor (14) of the second container (15) and at least one further partial flow is introduced into a mixing chamber (17) of the second container (15), wherein a partial flow of heated natural gas leaving the reactor (14) is simultaneously introduced into the mixing chamber (17).
4. The method according to claim 3, characterized in that the gas flow leaving the mixing chamber (17) is conducted through a separator (18).
5. The method according to claim 4, characterized in that the condensates occurring in the reactor (14) of the mixing chamber (17) and also in the separator (18) are diverted into a condensate trap.
6. The method according to claim 5, characterized in that an absorption agent for binding the water vapour is sprayed into the gas flow, in order to assist the condensate separation.
7. The method according to claim 6, characterized in that triethylene glycol is used as the absorption agent.
8. The method according to one of the preceding claims, characterized in that the dew point of the natural gas removed from storage is measured at least before it enters the first container (8) and after it leaves the second container (15), that, depending on the measured dew point values, an oxygen addition and flow control of the flow of natural gas conducted into the second container (15) is varied.
9. The method according to claim 8, characterized in that the variations in oxygen addition and flow control are conducted in a program-controlled manner.

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