JPS606985B2 - How to keep carbon monoxide converter warm - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a city gas generator equipped with a carbon monoxide shifter (hereinafter referred to as a CO shifter), such as a low-pressure catalytic cracking oil gas generator, etc. The present invention relates to a method for maintaining a CO shift converter at a predetermined temperature during a period when the generator is out of operation.

In the following, light carbon hydrogen is reformed with steam,
Although the explanation will be given using an example of city gas production using a cyclic gasification plant that converts the obtained reformed gas into CO, the method of the present invention is applicable to all gas generators equipped with a CO converter. Needless to say, it will happen.

It is desirable that the concentration of CO in city gas be as low as possible.

Mainly to meet the demand for city gas during peak hours. Cyclic gasification plants that are operated are often operated in batches due to their nature, so once the operation is stopped, the C
The catalyst temperature within the O shift converter gradually decreases. Therefore, it usually takes about 3 to 8 hours for the CO shift converter to return to a steady state after restarting operation. There is a problem that the CO conversion rate is low and the CO concentration in the obtained city gas is high during the time it takes to return to normal operation after restarting the operation. The following methods have been adopted. (1) Cover the outer surface of the CO conversion device with an inorganic heat insulating material.

According to this method, even in winter when the CO shift converter is in use, it is possible to balance the calorific value due to the shift reaction with the sum of the sensible heat difference between the input and output gases of the shift converter (output gas > input gas) and the amount of heat radiation. However, when the operation of the CO shift device is stopped, it is difficult to prevent the catalyst temperature from decreasing due to heat radiation. (D) After restarting operation, the CO shift reaction is promoted by suppressing the temperature and load in the reforming reaction and increasing the steam partial pressure for a while, and the CO shift converter is heated and heated by the obtained reforming gas.

However, this method not only fails to sufficiently reduce the CO concentration in the gas, but also has the disadvantage of not being able to respond quickly to gas demand because it is operated with significantly reduced production capacity. be. (m) Immediately after restarting the operation, gas is produced under normal reforming reaction conditions, and the CO shift converter is heated and heated by the produced reformed gas.

In this method, the CO concentration in the gas is higher than in the case (0) above, and the catalyst layer in the CO metamorphosis phase is locally heated by the reformed gas, so the catalyst life is shortened. There are cases. As a result of various studies in view of the current situation, the present inventor has found that when supplying the space below the catalyst layer filled in a CO shift converter, the catalyst layer is uniform due to the gentle natural convection that occurs. It has been found that the desired high CO conversion can be achieved immediately after the gas is produced again.

The present invention was completed based on such new knowledge. The present invention will be explained in more detail below with reference to the drawings. In the cyclic gasification plant shown in FIG. 1, during steady operation, gas or liquid fuel from line 3 is first mixed with oxygen-containing gas such as air from line 5 and combusted, and then this combustion exhaust gas is After heating the checker bricks in the subheating chamber 7 and further heating the internal reforming catalyst through the line 9 to the sludge reactor 11 to the temperature required for the sludge reaction, the heat is transferred to lines 15 and 8E. It is discharged into the atmosphere via recovery boiler 17, line 19 and stack 31.

Then, the supply of fuel from line 3 and air or other oxygen-containing gas from line 5 is stopped, and water or steam from line 1 is supplied to subheater 7 to heat it to near the pneumatic reaction temperature. This is further fed through line 9 to a pure reactor 11. Light hydrocarbons such as naphtha, LPG, and natural gas are supplied to the waste reactor 11 from a line 13.
Steam reforming is carried out in the presence of a known reforming reaction catalyst such as an N,0-Mg○-based catalyst. The reforming reaction conditions are usually a pressure of 100
0 to 200 water column, liquid space velocity 0.8 to 1. The temperature at the outlet is about 650 to 900 oo. The composition ratio of the reformed gas that is generated varies depending on the type of raw material vertical hydrocarbon, but the main components are CH4, CO, etc.
The CO content is usually about 12 to 20%. When the temperature of the subheater 7 and the political reaction device 11 decreases by continuing the reforming reaction, heating with the combustion exhaust gas is repeated in the same manner as described above. By providing a plurality of sets of the subheater 7 and the polymer reactor 11, the heating process and the gas production process can be appropriately switched to continuously produce the gas. The reformed gas from the reforming reactor 11 enters the scarlet heat recovery boiler 17 via line 15, and after being lowered in temperature,
CQ along with water vapor from line 21 via line 19
Enter Metamorphosis Taka 23. The reaction conditions within the CQ metamorphosis device are also
There is no particular difference from the known method.
The following conditions are adopted: water column of about 0.00 m, temperature of about 28 to 450 cm, and space velocity of about 400 to 800 N/hr. Output gas from the CO converter 23 whose CO content is below a predetermined value (usually about 8% or below) passes through line 25 and enters the scarlet heat recovery boiler 27, where the heat is recovered and then sent through line 20 to the system. taken outside. FIGS. 2, 3, and 4 show in detail a method of keeping a CO conversion apparatus warm according to the method of the present invention.

As shown in FIG. 2, inside the CO converter 23, a saucer 33
A catalyst 35 is filled on top, and a Raschig ring 37 is further placed above it. During steady operation, gas from the reforming reactor enters the CO shift converter 23 from the inlet 39, undergoes CO shift while passing through the catalyst 35, and then passes through the outlet 41.
Exit the device. In the cyclic gasification plant shown in FIG. 1, when gas production is temporarily interrupted due to a decrease in demand for city gas, the heating fluid is wound from the line 43 below the catalyst 35 in FIG. The heat is sent to the pipe line 45 provided, and the radiated heat generates natural convection, thereby heating the catalyst 35.

Heating by natural convection makes the catalyst temperature uniform throughout, thereby preventing localized heat generation immediately after CO conversion is restarted.
The heated fluid exits the CQ converter 23 through line 47. FIG. 3 shows an example of a heating fluid supply method.

When the heating fluid is a liquid such as heating oil,
Heating fluid flowing through line 47 is heated by boiler 49;
It is circulated from the line 43 into the CO converter 23 through the line 51, the cushion tank 53, the line 55, and the booster pump 57. FIG. 4 shows another example of the heating fluid supply method.

For example, when using high-temperature waste gas obtained in a gas generation plant as a heating source, the waste gas from line 59 is sent to pipe 45 via compressor 61 and line 43, and the heated waste gas is Radiant tower 6 via line 47
3 and dissipates into the atmosphere. Alternatively, although not shown, a sheath heater may be wired inside the CO conversion device 23 in place of the line 43, conduit 45, and line 47 shown in FIG. 2, and heating may be performed electrically.

When restarting gas production, stop the heating described above,
The steam reforming of light hydrocarbons and the CO conversion of the reformed gas can be started immediately using the conventional method described above.

The present invention also includes the following cases. That is, this is a method in which a heat source is supplied from outside the CO converter to heat the CO converter, and the desired purpose can also be achieved by this method. The means for supplying the heat source from the outside may be any of a variety of ordinary means, such as providing a jacket and supplying the heat source between the jackets. According to the method of the present invention,
The following remarkable effects are achieved:

{b) Since a sufficient CO transformation rate is achieved at the same time as gas production is restarted, gas with a low CO concentration can be obtained immediately.

Since the catalyst packed in the 'ol CO shift converter can be kept uniformly warm, local heat generation in the catalyst layer immediately after restarting gas production can be prevented.

Therefore, the catalyst life is greatly extended. 1. Unlike the case of the conventional method (0), it is possible to operate at 100% load from the beginning of gas production.

Example 1 In the cyclic gasification plant shown in Fig. 1,
Inner diameter 345 The enemy's CO transformation device 23 has a specific heat of 0.1 c
Fe-based catalyst 58000k9 of al'kg・℃ is packed in four layers (thickness of each layer is 820 ribs, distance between layers is 8
0 Cape).

In the CO converter, the waste gas obtained in the reforming reactor 11 is operated under steady operating conditions of QO/CO=3.4 (molar ratio), SV=750/hr, and outlet temperature of 400°C. When subjected to CO conversion, the results shown in Table 1 are obtained. When the gas production in Table 1 is stopped, the temperature of the catalyst layer in the CO conversion device 23 decreases as shown in Table 2 below.

Note to Table 2: However, the values are measured in winter (outside temperature 2 to 4°C).

In this state, if gas production is restarted after 2 treatment hours at a load of 60% as shown in the conventional method (0) above, it will take about 3 to 5 hours for the CO concentration in the converted gas to decrease to a steady value. .

Therefore, in this example, at the same time as gas production is stopped,
As shown in FIG. 3, a heat medium (trade name Dowsome A, manufactured by Dow Chemical Co., Ltd.) heated to 320° C. by a boiler 49 is circulated and supplied into the CQ shift converter 23 at a rate of about 25k9/hr, and the entire catalyst layer is heated to 320°C. Maintain at 300°C.

When gas production is restarted under such conditions, the Cq temperature in the converted gas exhibits a steady value similar to that shown in Table 1 from the beginning.

[Brief explanation of the drawing]

FIG. 1 is a flowchart for explaining an embodiment of the present invention, and FIGS. 2, 3, and 4 are drawings showing details of a heat retention method for a CO conversion device according to the method of the present invention. . 1...Water or steam supply line, 3...
・Fuel supply line, 5... Oxygen-containing gas supply line such as air, 7... Preheating chamber, 11... Reforming reaction device, 13... Vertical hydrocarbon supply line , 17・
... Scarlet heat recovery boiler, 21 ... Steam supply line, 23 ... ．． CO shift converter, 27...9E heat recovery boiler, 31...Stack, 33...Saucer, 35...CO shift catalyst, 37...Raschig ring, 39...・Gas inlet, 41...Gas outlet, 43...Heating fluid supply line, 47...
... Heating fluid delivery line, 49 ... Boiler, 53 ... Cushion tank, 57 ... Hooster pump, 59 ... Waste gas supply line, 61 ... Compressor, 63 ...Radiation tower. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. In a heat retention method during a gas generation stop period of a carbon monoxide shift device attached to a gas generator that is operated intermittently, heat is supplied to the space below the catalyst layer in the carbon monoxide shift device,
A heat retention method for a carbon monoxide shift equipment characterized by heating a catalyst layer by generated natural convection.