JPS62148593A - Method for operating carbon dioxide converter - Google Patents

Abstract

PURPOSE:To make temperature an optimum state readily to give high conversion ratio, to prolong a catalytic life and to make to possible to carry out rapid, proper treatment on extraordinary high temperature of catalytic layer, by adding methanol to a gas to be converted at an inlet side of a reactor. CONSTITUTION:A gas to be converted is introduced from a feed pipe 3 to a carbon monoxide converting reactor 1, methanol is fed from a piping 5 to the upper steam of a catalytic layer while controlling it by a valve 6 manually or automatically and added to the gas to be converted. EFFECT:Concentration of hydrogen gas as a product is raised and this process can be effected simply by setting a piping of methanol to an established facility.

Description

DETAILED DESCRIPTION OF THE INVENTION fal INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to a method of operating a carbon monoxide shift converter.

(b) Prior Art A carbon monoxide shift converter is a reactor for converting carbon monoxide in gas into hydrogen and carbon dioxide gas using water vapor, mainly according to the following reaction formula.

CO+H20-+ Co2+) (2 This carbon monoxide shift converter is used in hydrogen plants, ammonia plants, city gas production equipment, and other devices that require removal of carbon monoxide from produced gas.

This is because when producing hydrogen etc., petroleum etc. are decomposed and at the same time carbon monoxide is produced. and,
This carbon monoxide is an impurity that must be removed. Further, carbon dioxide is easier to remove than carbon monoxide, and has less reactivity and less harmful effects. moreover,
One of the reasons is that since hydrogen is usually the product in the above-mentioned devices, it is preferable to increase the amount of hydrogen.

Of course, the allowable residual concentration of carbon monoxide varies depending on the type of equipment. For example, in the case of city gas, toxicity to the human body is a major concern, so a concentration of several percent is acceptable, but in ammonia plants and equipment that require high concentration hydrogen, a concentration of 1% or less is required. However, if a PPM unit is required, an adsorption method must be used instead of this method.

This carbon monoxide modification reaction is an exothermic reaction (9.8K
cal/mol), it is advantageous for the equilibrium constant of the reaction to be at a low temperature. However, due to reaction speed issues, gas is usually introduced at 350° C. for high-temperature carbon monoxide shift converters and around 200° C. for low-temperature ones. This will leave the reactor at a temperature of several tens of degrees due to the metamorphosis reaction.

When the temperature rises in the reactor, not only does the equilibrium value worsen and the conversion rate worsens, but the catalyst itself is extremely sensitive to temperature, which causes destruction, collapse, and decreased activity. Therefore, in this carbon monoxide shift converter, the catalyst layer is separated into multiple stages, and cooling steam is introduced between the stages.

From the above, it can be seen that temperature control is a very important issue when operating this carbon monoxide shift converter.

fc) Problems to be Solved by the Invention However, in the past, this temperature control was hardly performed, and the temperature rise was only suppressed to a certain extent by the amount of steam. In this case, as described above, the temperatures near the entrance of the carbon monoxide transformer and near the exit of the carbon monoxide transformer are different, making it impossible to carry out the shift at a constant temperature. In other words, it goes without saying that it is most desirable for a chemical reaction to be carried out under constant optimal conditions while passing through a reactor, but this was not possible in this carbon monoxide shift converter.

Furthermore, in abnormal situations, such as when the carbon monoxide concentration in the introduced gas suddenly increases or the total gas volume increases, heat generation in the carbon monoxide shift converter increases, causing abnormally high temperatures in the catalyst layer. do. Conventionally, there was no way to suppress this problem other than introducing steam; in other words, we were only hoping for the negative effect of removing heat by steam.

In this case, it was not possible to immediately lower the temperature in the event of an abnormality, and in most cases, the rN fM of the catalyst was caused.

Therefore, those skilled in the art who use carbon monoxide shift converters strongly desire an operating method that allows the reactor to be operated at as constant a temperature as possible throughout the entire reactor, and that can quickly respond to abnormalities.

fdi Means to Solve the Problems In view of the above circumstances, the inventor of the present invention believes that the carbon monoxide modification reaction is an exothermic reaction, and in order to suppress this heat generation, an endothermic reaction or an endothermic reaction must be performed simultaneously in the same container. The present invention was completed by focusing on the point that it is sufficient to carry out a reaction that does not adversely affect the carbon monoxide transformation reaction and does not affect the product gas to be produced, and its characteristics are as follows: The point is that methanol is introduced on the inlet side of the carbon monoxide transformer.

Here, methanol, of course, does not need to be 100% pure, and may be of an appropriate concentration.

However, it goes without saying that about 90% or more is preferable. Furthermore, there is no problem even if a small amount is mixed in as long as the component does not poison the carbon monoxide shift converter catalyst and does not affect the product gas.

Any method of introduction may be used, and even after gasification, it may be injected as a liquid.

The actual location does not matter as long as the introduction is on the inlet side of the carbon monoxide transformer. However, it will normally be introduced into the carbon monoxide transformer inlet separately from the gas inlet pipe.

Furthermore, it may also be introduced into every intermediate portion of the catalyst layer. This is the middle part of a multi-stage catalyst layer, and by doing so, it is possible to more quickly prevent a temperature rise in the event of an abnormality. Of course, it is also possible to introduce it only to the middle part, but it seems that the effect will be small.

This introduction of methanol does not need to be carried out all the time, and may be carried out only in emergencies.

The carbon monoxide shift converter referred to in the present invention may be from any plant, and includes any plant that performs a so-called shift reaction that converts carbon monoxide and water vapor into hydrogen and carbon dioxide gas. .

(el action) The reaction in the carbon monoxide shift converter when methanol is introduced as described above will be explained.

Methanol undergoes the following reaction using a carbon monoxide conversion catalyst.

CH30H+ H2O→ C○2+3H2 This reaction is endothermic (11,8 Kcal/mol). This reaction and the carbon monoxide modification reaction described above occur simultaneously. However, neither of them has any adverse effects on others, nor do they produce any components that should not be mixed in. The amount of heat required for this reaction is obtained from what is produced by the metamorphic reaction. In other words, the excess heat generated by the modification reaction is consumed by the methanol decomposition reaction, thereby preventing a rise in temperature.

Therefore, by adjusting the amount of methanol mixed in, it is possible to make the inlet and outlet sides of the carbon monoxide shift converter have exactly the same temperature. This method is relatively simple, can be calculated easily, and can be adjusted during actual operation.

However, such strict control is usually not necessary, and the drawbacks of the conventional technology can be greatly alleviated by introducing it to a certain extent.

(') Embodiment Next, an example of an apparatus for carrying out the method of the present invention will be described based on an embodiment shown in the drawings.

Figure 1 shows the case where the present invention is applied to a carbon monoxide shift converter in city gas production equipment, in which a catalyst layer (2) of a reactor (1) is provided, and the gas to be converted is supplied to an inlet pipe (3). ), reacts on the catalyst layer, and is discharged from the discharge pipe (4). Here, methanol is supplied from the methanol pipe (5)
is introduced into the upstream part of the catalyst layer. The amount is controlled manually or automatically by a valve (6).

(gl Effects of the Invention According to the present invention described in detail above, there are the following effects.

(1) The temperature inside the carbon monoxide shift converter can be easily set to an optimum value, and the best shift conversion rate can be ensured.

(2) There is little change in catalyst temperature, extending the life of the catalyst.

(3) Abnormal high temperatures in the catalyst layer can be treated quickly and appropriately, and various accidents can be prevented.

(4) The concentration of hydrogen gas, which is a product, increases.

(5) The present invention can be easily implemented in existing equipment by simply installing methanol piping. This has a great advantage compared to the method of rebuilding a new device to prevent the conventional drawbacks.

As explained above, the present invention is very useful because the equipment is simple and it has great effects.

[Brief explanation of drawings]

FIG. 1 is a schematic flow sheet illustrating an embodiment of the present invention. 1... Reactor 2... Catalyst layer 3... Inlet pipe 4... Discharge pipe 5... Methanol piping 6... Valve C1

Claims (1)

[Claims] 1. A method for operating a carbon monoxide shift converter, characterized in that methanol is mixed into the gas to be converted on the inlet side of the reactor. 2. The method of operating a carbon monoxide shift converter according to claim 1, wherein the carbon monoxide shift converter is for low temperature use using a copper-based catalyst. 3. The method of operating a carbon monoxide shift converter according to claim 1, wherein the amount of methanol mixed is controlled by the gas temperature on the outlet side of the reactor. 4. The method of operating a carbon monoxide shift converter according to claim 2, wherein methanol is also introduced into an intermediate portion of the carbon monoxide shift converter. 5. The method of operating a carbon monoxide shift converter according to claim 1, wherein methanol is mixed only when the carbon monoxide shift converter reaches an abnormally high temperature.