JPS6241701A - Pressure swing type gas separator in methanol decomposition apparatus - Google Patents

Abstract

PURPOSE:To contrive to improve the gas separation capacity and gas purity, by exchanging the heat of a regenerated gas with waste gas using a heater provided in the course of a regenerated gas conduit and completing the regeneration of adsorption columns of a gas separator. CONSTITUTION:A raw material methanol 1 and pure water 2 are heated in a preheater 3 and fed to a reactor 7. A heating medium heated in a heating furnace 16 is fed to the reactor 7 to heat a catalyst layer in the reactor 7. The methanol 1, etc., are passed through the catalyst layer and decomposed. The resultant decomposed gas 11 is fed to a separation unit 13 to separate hydrogen and/or carbon monoxide. In the process, a purified hydrogen conduit 14 for purified hydrogen discharged from the adsorption column 22 in the pressurized adsorption step is connected to the adsorption column 22 in the decompressed desorption step with a regenerated gas conduit 27 to carry out the heat exchange of the waste gas from the heating furnace 16 with the regenerated gas in a regenerated gas heater 25.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is a methanol decomposition device that decomposes methanol to produce hydrogen gas, carbon monoxide gas, or a mixed gas of 49 gases. This invention relates to a pressure swing type gas separator used for carbon separation.

[Conventional technology]

There is no need to overstate the importance of hydrogen in modern industry.

In other words, from low-concentration, large-volume consumption types such as ammonia synthesis, methanol synthesis, and oil refining industries to high-concentration and small-volume consumption types such as semiconductor industry and space inspection, organic and inorganic chemical industries, food, metallurgy, and electricity. It has been a long time since hydrogen has become unpopular in a wide range of fields, such as nuclear energy, and calls for an inexpensive hydrogen production method have been made.

However, the development of new technology for inexpensive hydrogen production is not easy, and hydrogen is produced by electrolysis of water in the case of small amounts of hydrogen, and by catalytic reforming of hydrocarbons such as butane and naphtha in the case of large amounts. .

- Carbon monoxide is used in carbonylation reactions and oxo reactions in the organic chemical industry, as well as in the production of acetic acid and ethylene glycol, and has recently attracted particular attention as a raw material for Al chemistry. However, it is difficult to produce carbon monoxide at a low cost, and it can be produced through partial oxidation reactions of hydrocarbons such as butane or heavy oil, or by recovery from gases containing carbon monoxide such as steel plant waste gas. However, the process is complicated, making it a more expensive gas than hydrogen.

Furthermore, it is often necessary to mix hydrogen and carbon monoxide in various ratios, but in this case too, it is produced by partial oxidation of heavy oil, coal, etc., and this is also expensive.

As an alternative to such conventional methods for producing gold using hydrogen, carbon monoxide, or a mixture thereof, methanol reforming or decomposition reactions can be used. This reaction step is as follows.

That is, when hydrogen is obtained as a product, the following equation proceeds by the steam reforming reaction of methanol.

0H30H+H20→3 Fi2 + 002...
- (1) Also, when obtaining a mixed gas of hydrogen and carbon monoxide as a product, the following equation proceeds in the decomposition reaction of methanol.

C! EI, OH → 2H2 + OO... (2) This O Both reactions are reactions under a catalyst, and the reaction temperature is 300-4
It is an endothermic reaction at 00°C, and in equation (1), 1t s x
caL/-v: #methanol, 21.4 in formula (2)
Requires reaction heat of Kcal and I'E nyl methanol.

A conventional technique is shown in FIG. 4, and its contents will be briefly explained.

Methanol and water adjusted to a predetermined flow rate ratio are supplied from the methanol supply line 1 and the pure water supply line 2, and after exchanging heat with the outlet gas from the reactor 7 in the raw material preheater 3, they are transferred to the evaporation heater. In Step 4, the temperature is raised to the reactor inlet temperature, and the mixture is supplied to the reactor 7. The reactor 7 is generally of the tubular type, and methanol is passed through a bed filled with catalyst within the reaction tube.

A heating medium heated by burning fuel from a fuel supply line 20 is passed through a heating medium heating furnace 16 on this shell side, and the reaction tube is heated from the outside to supply all the heat necessary for methanol decomposition. A part of the heat medium from the heat medium heating furnace is also supplied to the evaporative heater 4, and after cooling down, returns to the heat medium circulation pump 18i/ (through the heat medium heating furnace. Methanol is decomposed in the reactor 7, and hydrogen gas is generated. Alternatively, a mixed gas of hydrogen and carbon monoxide is generated,
After this high-temperature gas gives heat to the raw material in the raw material preheater 3, it is further cooled to around room temperature in the cooler 9, and the condensate containing all unreacted methanol is separated in the gas-liquid separator 10, and only the gas component is separated. The gas is supplied from the gas line 11 to the gas separation unit 15. In the gas separation unit 13, after removing impurities and adjusting the hydrogen/carbon monoxide ratio 11c or gas ratio, the product gas gold is taken out from the product gas take-out lines 14 and 15. The condensed bottom in the gas-liquid separator 1o is connected to the circulation line 1
2 to pure water supply line 2 or return to methanol supply line 1.

5 in the figure is a raw material preheater used at startup.

The gas separation unit 13 in FIG. 4 normally uses a pressure swing method to separate hydrogen gas and carbon monoxide gas.

That is, as shown in FIG. 5, a plurality of adsorption towers 22fc filled with an adsorbent such as zeolite are subjected to pressure swing operation in a time cycle, and gas is fed into the tower from the mixed gas supply line 21 during pressurization. All hydrogen gas is taken out from the product gas line 2S by selectively adsorbing carbon monoxide onto an adsorbent. After a certain time, when the amount of adsorption reaches saturation, line 2
1. Close the valve of line 23 and purge gas line 24.
is opened to vent the pressurized gas in the adsorption tower 22, and in this process, carbon monoxide adsorbed by the adsorbent is desorbed and recovered.

The problem here is that carbon monoxide has less adsorption:lii than other gases, such as carbon dioxide. For this reason, the amount of gas that can be treated by simply repeating nine pressure swings as in the conventional method is small, and the purity of each of hydrogen and carbon monoxide is also low. On the other hand, as a method to increase the purity of hydrogen gas, sometimes a method is used to wash the adsorption tower with a part of the product gas after the desorption operation and exhaust the carbon monoxide contained in the layer. If this is the case, the amount of hydrogen gas product will decrease, and a large amount of hydrogen will be mixed into the fermented carbon gas, which is undesirable.

[Problem that the invention seeks to solve]

The present invention solves the shortcomings of the pressure swing type gas separator of the conventional methanol cracking equipment, seeks heat sources and gas sources within the cracker, and more completely regenerates the adsorption tower of the gas separator, increasing the separation capacity. The present invention aims to provide a pressure swing type gas separator that enables dramatic improvements in gas purification and purified gas purity.

[Means for solving problems]

The present invention is a pressure swing type gas separator for a methanol decomposition device that decomposes methanol under a catalyst to produce hydrogen gas, carbon monoxide gas, or a mixture thereof. A regeneration gas conduit is provided to connect the purified hydrogen conduit and the adsorption tower in the vacuum desorption step, and a regeneration gas heater is provided to exchange heat between the regeneration gas and the exhaust gas of the boiler that heats the heating medium supplied to the methanol decomposition reactor. This is a pressure swing type gas separator for a methanol decomposition apparatus, characterized in that it is installed in the middle of the regeneration gas conduit.

[Effect]

Figure 6 shows the carbon monoxide adsorption characteristics of the adsorbent.

As is clear from this figure, the adsorption amount changes depending on the partial pressure of carbon monoxide in the gas, but it also changes significantly depending on the temperature. That is, at the same pressure, the amount of adsorption increases as the temperature increases, and decreases as the temperature increases. Utilizing this phenomenon, in the present invention, in addition to the conventional pressure swing, the temperature of the adsorption tower is increased during desorption to desorb more of the adsorbed carbon monoxide than in the case of pressure swing alone. As a heat source for heating the adsorption tower, the heat of the exhaust gas from the boiler for heating the heating medium is effectively utilized. After the adsorption tower has completed the adsorption operation under pressure, it is desorbed under reduced pressure at the same temperature. A small portion of the product hydrogen gas is heated by exchanging heat with the exhaust gas of the total heat medium heating boiler, and then supplied to the adsorption tower, where it is adsorbed. The agent is heated to further desorb carbon monoxide. This increases the amount of carbon monoxide adsorbed in the next cycle of adsorption operation, thus increasing the gas throughput and improving the purity of hydrogen gas. Multiple adsorption towers are used, and each adsorption tower performs adsorption and desorption in batches, with the entire device continuously separating hydrogen and carbon monoxide in the same manner as in the past.

The present invention will be described below based on embodiments shown in the drawings.

FIG. 1 shows the entire methanol decomposition apparatus according to the present invention,
Figure 2 shows details of the gas separation unit 15. show. In these figures, the configurations characteristic of the present invention are as follows:
heat exchanger 25, boiler exhaust gas line 26 for heating medium,
They are a purge hydrogen line 27 and a purge gas supply line 28.

FIG. 3 conceptually shows the superiority of the present invention by comparing the amount of change in adsorption according to the present invention with the amount of change in adsorption due to conventional pressure swing alone.

In FIG. 1 and FIG. 2, a small part of the product hydrogen gas is branched from the purge hydrogen line 27, and the heating medium heating boiler 16
The heated hydrogen gas is exchanged with the exhaust gas 26 in the heat exchanger 25, and the heated hydrogen gas is supplied from the purge gas supply line 28 to the adsorption tower under desorption operation.

In FIG. 3, at a temperature of 25° C. during adsorption, the amount of adsorption at the end of the adsorption operation is indicated by point A, and when this is desorbed under reduced pressure at the same temperature, the amount of adsorption decreases to point B. That is, in the conventional pressure swing, the pressure swing varies between points A and B.

On the other hand, if the method of the present invention is used to purge with heated hydrogen during desorption, the amount of adsorption becomes 0 point, and the change in adsorption due to adsorption and desorption is expanded to point A and 0 point.

[Example 1] At a temperature of 25°C, 65 mol of hydrogen, 30 mol of carbon monoxide,
In addition, when 5 molti of gas was supplied and repeated tests were conducted with adsorption operation at 20 atm and desorption operation at 1.5 atm, the result was that the change in carbon monoxide adsorption was 40 f / 1. On the other hand, by heating the adsorption tower to 50° C. during desorption, the amount of adsorption change was 55 f/9 adsorbents, increasing the amount of adsorption by about 40%.

[Example 2] In a gas separation unit pilot plant having four adsorption towers in which each tower was filled with the same adsorbent as in Example 1 for 950 hours, a gas having the same gas composition as in Example 1 was charged at 40 N/hour.
m' was supplied, and gas separation was performed while changing the six towers over time. In this case, if separation is performed simply by pressure swing, gas with a hydrogen purity of 967 rupees will be produced as a product gas at 15% per hour.
Only 3 L of Nm was obtained, and the other product gas had a monodispersed carbon purity of 50 molty at 23 N/h.

On the other hand, 5% of the product hydrogen gas is heated to 60°C by exchanging heat with boiler exhaust gas for heat medium heating at a temperature of 350°C.
This was used as a system to supply and purge the adsorption tower during desorption operation. As a result, 2ON- per hour was obtained with the hydrogen purity of the product hydrogen gas branch 9x5, and the other carbon monoxide gas had a purity of 6
6% and 18 N/h.

〔Effect of the invention〕

The present invention has the following effects by employing all of the above configurations.

(1) Since the amount of adsorbent adsorbed per unit amount increases, the gas processing capacity improves in an adsorption tower with the same filling amount, and when the amount of gas processed is the same, the equipment scale becomes smaller and the equipment manufacturing cost is reduced. Become.

(2) The amount of hydrogen gas obtained as a product will increase, and the purity of hydrogen will also improve.

(3) Since the purity of carbon monoxide in other product gases is also high, it is extremely advantageous when used as a raw material for producing high-purity fermented carbon.

(4) Since boiler exhaust gas is used as a heating heat source,
No new utilities are required.

[Brief explanation of drawings]

FIG. 1 shows a methanol decomposition apparatus as an embodiment of the present invention, and FIG. 2 shows a gas recruitment unit and a third embodiment of the same embodiment.
The figure is a conceptual diagram showing the difference between the amount of change in adsorption and the conventional method. FIG. 4 shows a methanol decomposition apparatus using a conventional method, FIG. 5 shows a gas separation unit using a conventional method, and FIG. 6 shows an adsorption characteristic diagram of a zeolite adsorbent. Sub-Agents 1) Meifuku Agent Atsushi Hagi - Sub-Agent Atsushi Anzai

Claims (1)

[Claims] In the pressure swing type gas separator of a methanol cracker that produces hydrogen gas, carbon monoxide gas, or a mixture of these gases by cracking methanol under a catalyst, a purified hydrogen conduit discharged from an adsorption tower in a pressurized adsorption process. A regeneration gas conduit is provided to connect the regeneration gas conduit and the adsorption tower of the vacuum desorption process, and a regeneration gas heater for exchanging heat between the regeneration gas and the exhaust gas of the boiler that heats the heating medium supplied to the methanol decomposition reactor is installed in the regeneration gas conduit. A pressure swing type gas separator for a methanol decomposition device, characterized in that it is installed in the middle of a methanol decomposition device.