JPS58120692A - Steam reforming apparatus - Google Patents

Abstract

PURPOSE:A steam reforming apparatus for hydrocarbons, having an emergency shut-off valve just before a reactor in an inlet line for the reactor, a pressure control line through a pressure control valve on the upstream side of the emergency shut-off valve, and capable of achieving the temporary stopping and restarting of the apparatus easily in a short time. CONSTITUTION:In a steam reforming apparatus for hydrocarbons, the hydrocarbons, e.g. naphtha, are fed from a raw material feed line 1, and steam is fed from a steam line 2 and mixed with the hydrocarbons. The resultant mixture is then heated in a heating furnace 5, passed through an inlet line 7 for a reactor 8 and reacted in the reactor 8. the resultant reaction product gas is then taken out of a line 9 provided with a cooler 10 and a separator 11 to give the aimed product. In case the apparatus is stopped, an emergency shut-off valve 13 provided just before the reactor 8 is closed, and a fuel valve 6 is closed to extinguish the fire. A pressure control valve 15 in a pressure control line 14 provided on the upstream side of the emergency shut-off valve 13 is operated to suppress the pressure increase. The mixed gas in the upper part of the reactor 8 is discharged to a vent line 16 through a vent valve 17 provided between the emergency shut-off valve 13 and the reactor 8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steam reforming apparatus that can temporarily stop and restart the apparatus in a short time and easily in the event of an unexpected accident such as the above or due to demand for reformed gas.

Several methods have been proposed as methods for reforming hydrocarbons. Usually, the raw material hydrocarbon is charged into a reactor together with steam after impurities such as sulfur are removed. In this reactor, a reforming reaction between hydrocarbons and water occurs and a reaction product gas containing methane, hydrogen, and carbon dioxide as main components is obtained.In order to carry out this steam reforming reaction continuously, 3.50 Temperatures of ~550°C must be maintained and water vapor ratios must be maintained within appropriate ranges.
Not only will the product properties change, but it will also harm the catalyst. Therefore, during operation, the temperature and water vapor ratio are carefully controlled.

Conventionally, when the equipment is temporarily stopped due to problems such as a drop in the steam/carbine ratio or a sudden change in reaction temperature, or due to a power outage, the hydrocarbon raw material valve is first closed, and then a time delay is established. The steam valve was closed and the reaction gas was supplied with steam gas.

In this method, if the inside of the reactor is in a steam atmosphere, the catalyst will be oxidized, so it is necessary to introduce nitrogen gas to oxidize the steam. Moreover, since the heating furnace fire is extinguished when the apparatus is at rest, the temperature of the catalyst layer decreases when the above operation is performed, so it is necessary to immediately relight the catalyst layer after the apparatus is shut down to minimize the temperature drop. When the cause of temporary shutdown of the equipment is resolved and the equipment is restarted to restart the steam reforming reaction, the hydrocarbon raw material is delivered immediately after the steam is delivered. If hydrocarbons are introduced during or before this operation when the temperature of the catalyst layer of the reactor is below the limit temperature, carbonaceous matter will adhere to the catalyst and the catalytic activity will decrease, so hydrogen gas should be introduced in advance. It is necessary to restart the reaction after entering the tank and raising the temperature. Furthermore, an electric heater is installed in the reactor to maintain the temperature in order to prevent the temperature of the catalyst layer from decreasing when the reactor is not in use.

In this way, in order to temporarily stop the equipment, then release the stoppage and restart the equipment, various operations must be performed, nitrogen gas and hydrogen gas are also required, and it takes time to restart the reaction. This method has disadvantages in that it is expensive and the equipment is complicated. Particularly when this reformed gas is used as a city gas source for general consumers, the time loss from shutdown to restart has a significant negative impact on the overall supply plan.

The present invention has been made to solve these problems, and it is possible to perform emergency stop and restart of a steam reformer in order to protect the catalyst, protect the equipment, and protect the equipment in an extremely short time and without complicated operations. The purpose of the present invention is to provide a steam reforming device that does not require any equipment, and is particularly suitable for use as a low-temperature steam reforming device for producing city gas.

As a result of intensive research, the inventor of the present invention found that an emergency shutoff valve is provided in the steam reforming reactor inlet line, and a pressure control line is further provided upstream of the emergency shutoff valve via a pressure control valve, and if necessary, The inventors have discovered that the above object can be achieved by providing a reactor gas vent line downstream of the emergency shutoff valve via a reactor gas vent valve, and have arrived at the present invention.

That is, the present invention provides a steam reformer for hydrocarbons, in which an emergency shutoff valve is provided in the reactor inlet line immediately before the reactor, and a pressure control line is provided upstream of the emergency shutoff valve via a pressure control valve. This steam reforming apparatus is characterized in that a vent line is provided between the emergency shutoff valve and the reactor via a vent valve, if necessary.

The present invention will be specifically described below with reference to the drawings.

FIG. 1 is a process sheet showing one embodiment of the present invention.

In the steam reforming reaction, hydrocarbons such as naphtha and LPG are supplied from a raw material supply line 1, while steam is supplied from a steam line 2, and the amounts of these supplies are controlled by a raw material valve 3 and a steam valve 4, respectively. Ru. This mixed fluid consisting of the raw material and steam is heated to a predetermined temperature in the heating furnace 5, and is led to the reactor 8 via the reactor inlet line 7.

Note that the heating furnace 5 has fuel controlled by a fuel valve 6 to adjust the temperature. A reforming reaction between hydrocarbons and steam occurs in the reactor 8, and a reaction product gas containing methane, hydrogen, and carbon dioxide as main components is obtained.

This reaction product gas passes through a reaction product gas line 9 provided with a cooler 10, a separator 11, and a pressure regulating valve 12, and is turned into a product gas.

In the present invention, when the apparatus is shut down, the emergency shutoff valve 13 provided in the reactor inlet line 7 immediately before the reactor 8 is first closed, and the fuel valve 6 is also closed to extinguish the fire. As a result, the system internal pressure upstream of the emergency shutoff valve 13 increases due to the supply of steam and raw material gas, so the emergency shutoff valve ]3
Pressure control valve 1 of pressure control line 14 provided upstream of
5 is activated, and a mixed gas containing steam and raw material gas is discharged from the pressure control line to the outside of the system. Then, when the temperature at the outlet of the heating furnace 5 decreases, the raw material valve 3 and the steam valve 4
By closing the mixing gas, the release of soot is stopped. On the other hand, since the pressure regulating valve 12 is also closed, the reactor 8 and the reaction product gas line 9 are also kept at a constant pressure.

In addition, in the present invention, when it is desired to release the mixed gas in the upper part of the reactor 8 where the reforming reaction has not yet occurred completely, the vent line 16 is provided between the emergency shutoff-yP13 and the reactor 8, and the vent 9P17 is opened. Therefore, the mixed gas in the upper part of the reactor 8 may be discharged.

When restarting the device, the raw material valve 3 and the steam valve 4 are opened, the raw material and steam are supplied, the heating furnace 5 is ignited, and the pressure of the mixed gas is controlled until the temperature and steam/carbon ratio are adjusted to a predetermined temperature. It is discharged from the system through line 14. When the mixed gas is adjusted to a predetermined temperature and steam/carbon ratio, the emergency shutoff valve 13 is gradually opened and the pressure control valve 15 is closed, and the mixed gas is supplied to the reactor 8.

When the mixed gas is supplied and the internal pressure of the system increases due to the generation of reaction product gas, the pressure control valve 12 opens and product gas is obtained.

In the present invention, the steam/carpin ratio, raw material gas and steam flow rate, and temperature in the system are controlled by detectors and control devices installed on the lines, respectively, and similarly, the steam/carpin ratio and temperature in the system are controlled at a predetermined level. If it goes out of range, an alarm will be issued and six valves, including the emergency shutoff valve, will automatically open and close.
The device goes into emergency shutdown. Furthermore, it can be instrumented so that the six valves automatically open and close to restart the steam reforming reaction even when the device is started.

The present invention as described above has the following effects. (1) When the apparatus is shut down, the emergency shutoff valve stops the flow of the mixed gas into the reactor, so that the mixed gas under different conditions can react. This prevents nitrogen from entering the reactor, and the inside of the reactor remains in a reducing atmosphere, eliminating the need for steam generated by nitrogen gas.

(2) Since the temperature of the catalyst layer in the reactor is less likely to drop while the device is out of service, there is no need for hydrogen to be raised by threshing upon restart, and the startup time is greatly shortened.

(3) When restarting the equipment, the mixed gas can be released from the system through the pressure control line until a mixed gas with constant conditions can be adjusted, and the emergency shutoff valve can be opened when the adjusted mixed gas is obtained. As a result, the reaction starts immediately and the product is obtained. At this time, mixed gases with different conditions do not flow into the reactor, so they do not harm the catalyst.

(4) Since a vent line is provided as necessary, the mixed gas in the upper part of the reactor can be discharged when the equipment is stopped.

The steam reformer of the present invention, which enables temporary equipment shutdown and restart in a short time and with simple equipment and operation, is particularly useful for low-temperature steam reformers for city gas production. In addition to being suitably used as a methanation device, it can also be applied to a carbon oxide conversion device.

Hereinafter, the present invention will be explained based on examples.

Example 5 y/y of steam was added to the steam reformer shown in Figure 1.
h', LPG 2 ) was heated to 400° C. and supplied to the adiabatic reactor. The reaction pressure of the reactor is 2k.
g/(7)2・G, the reactor outlet temperature was 4
When the temperature reached 35°C, the gas with the composition shown in Table 1 was used as the product gas.
00 Nm3/h.

Table 1 Next, close the emergency shutoff valve and operate the pressure control valve, and LP
A mixed gas of G and steam was released from the pressure control line to the outside of the system. Subsequently, the heating furnace fire was extinguished, and the supply of LPG and steam was stopped. On the other hand, the inside of the reactor was maintained at a -1-reformed gas atmosphere by closing the pressure control valve.

Supply steam again and turn on the heating furnace, then LPG
was supplied, and the mixed gas was discharged from the pressure control line to the outside of the system. After adjusting the flow rate ratio of steam and LPG and the heating temperature and heating to 400° C. at a rate of 2.5 tons of steam/hXLPG 1 ton/h, the emergency shutoff valve was gradually opened.

The pressure control valve closed automatically, and it was confirmed that the pressure control valve operated and product gas was generated.

Next, steam 5 tons/h, LPc 2) tons/h
When the amount was increased to 400°C and the temperature was maintained at 400°C, the outlet temperature was 435°C.
Obtained at 0ONm/h.

The length of the reaction layer was investigated based on the temperature distribution of the catalyst layer, and it was confirmed that there was no difference in catalyst performance at 60 crn both before and after restarting the device.

FIG. 1 is a process sheet showing one embodiment of the present invention.

It can also be applied to methanation equipment and carbon oxide conversion equipment.

Hereinafter, the present invention will be explained based on examples.

Example 5 tons of steam was added to the steam reformer shown in Figure 1.
'h, LPG 2 ) was heated to 400° C. and supplied to the adiabatic reactor. The reaction pressure of the reactor is 12 kg.
/crn2・G, the reactor outlet temperature was 4.
When the temperature reached 35°C, the gas with the composition shown in Table 1 was used as the product gas.
O obtained at 0ONm3/h Table 1 Next, close the emergency shutoff valve and operate the pressure control valve, and LP
A mixed gas of G and steam was released from the pressure control line to the outside of the system. Subsequently, the heating furnace fire was extinguished, and the supply of LPG and steam was stopped. Meanwhile, air was kept inside the reactor.

Supply steam again and turn on the heating furnace, then LPG
was supplied, and the mixed gas was discharged from the pressure control line to the outside of the system. After adjusting the flow rate ratio and heating temperature of steam and LPG and heating to 400°C at a rate of 2.5 tons/h of steam and 1 ton/h of LPG, the emergency shutoff valve was gradually opened. The pressure control valve closed automatically, and it was confirmed that the pressure control valve operated and product gas was generated.

Next, the amount was increased to 5 tons/h of steam and 2 tons/h of LPG, and the temperature was maintained at 400°C, and the outlet temperature was 435°C.
A gas with almost the same gas composition as in Table 1 is 370ONm
/h.

The length of the reaction layer was investigated based on the temperature distribution of the catalyst layer, and it was confirmed that there was no difference in catalyst performance at 60α both before and after restarting the device.

[Brief explanation of the drawing]

FIG. 1 is a process sheet showing one embodiment of the present invention. 1: Raw material line, 2 Nisteam line, 3: Raw material valve, 4
Nisteam valve, 5: Heating furnace, 6: Fuel valve, 7: Reactor inlet line, 8: Reactor, 9: Reaction product gas line, 10
: Cooler, 11: Separator, 12: Pressure control valve, 13;
Emergency shutoff valve, 14: Pressure control line, 15: Pressure control valve, 16 Two vent lines, 17: Vent valve. Patent applicant JGC Corporation Company agent Patent attorney Tatsuo Ito Agent Patent attorney Tetsuya Ito

Claims (1)

[Claims] 1. In a steam reformer for hydrocarbons, an emergency shut-off valve is provided in the reactor inlet line immediately before the reactor, and a pressure control line is provided upstream of the emergency shut-off valve via a pressure control valve, and if necessary, A steam reforming apparatus characterized in that a vent line is provided between the emergency shutoff valve and the reactor via a pent valve.