JPS6086194A - Apparatus for purifying coke oven gas - Google Patents

Abstract

PURPOSE:To miniaturize a prefilter and remove the necessity for regeneration of an adsorbent, by packing silica gel, molecular sieves having a specific diameter, activated carbon and molecular sieves having a specific diameter in the order mentioned from the upstream side of a gas stream in an adsorption column. CONSTITUTION:Silica gel, molecular sieves having 10Angstrom diameter, activated carbon and molecular sieves having 5Angstrom diameter are packed in the order mentioned from the upstream side of a gas stream of a raw material coke oven gas in an adsorption column of a main purification apparatus operating by changing over the adsorption-regeneration steps with pressure change. EFFECT:Equipment and operating costs can be reduced, and the main purification apparatus itself can be compacted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coke oven gas (hereinafter referred to as COG) purification apparatus that operates by switching between adsorption and regeneration steps based on pressure changes.

As a method for recovering hydrogen contained in a large amount from COG, there is a method using a purification device that is operated by switching between adsorption and regeneration steps based on pressure changes. This method first uses COG
is introduced into a tar remover to remove tar. Then, it is pressurized to 8 to 15 Jt/crA with a compressor, and after removing the drain, it is introduced into the pre-filter. The prefilter is filled with carbon-based adsorbents such as activated carbon and semi-formed coke, and removes high-boiling hydrocarbons such as tar, naphthalene, and BTX, and sulfur compounds such as hydrogen sulfide in COG. Next, the COG that has exited the pre-filter is passed through one of the main purifiers, which consists of multiple adsorption cylinders filled with adsorbents such as activated carbon and molecular sieves, and is operated by switching between pressurized adsorption and low-pressure regeneration depending on pressure changes. The hydrogen is fed under pressure into an adsorption column, where residual moisture, light hydrocarbons, carbon dioxide, carbon oxide, nitrogen, etc. are adsorbed and removed to recover hydrogen.

By the way, when refining COG using this method, high-boiling hydrocarbons and sulfur compounds are removed using a pre-filter, which places a heavy load on the pre-filter, requiring a large amount of adsorbent, and the pre-filter itself. becomes very large. Furthermore, the amount of adsorbent consumed is large, which is a factor in increasing the cost of producing hydrogen. Furthermore, when the adsorbent in the prefilter is regenerated by a heating regeneration method, additional equipment such as a water vapor generator is required, and the operation is troublesome.

This invention was made in view of the above circumstances, and allows the pre-filter to be made smaller, eliminates the need to regenerate its adsorbent, reduces installation and operating costs, and makes the main purification device itself compact. The object of the present invention is to provide a COG purification device that can perform the following steps.

Hereinafter, the present invention will be described in detail with reference to the drawings.

The feature of the present invention is that four adsorbents are filled in the adsorption column of the main refining device in a specific stacking order.

FIG. 2 shows the stacking order of the four types of adsorbents in the adsorption column 1, where 2 indicates the inlet of the COG and 3 indicates the outlet. Then, from the inlet 2 side to the outlet 3 of this adsorption cylinder 1, silica gel SG, 10A diameter molecular sieves 1O
AMS1 activated carbon AC.

Filled with prescribed weathering. The above-mentioned 10A diameter molecular sieves and 5A diameter molecular sieves are zeolite-based molecular sieves. In this way, two or more adsorption columns 1 filled with 4 utf of II-R agent in a specific stacking order are provided as the main purification device, and these adsorption columns 1 are sequentially used for adsorption and regeneration. Each process is switched and operated.

Next, a method for recovering hydrogen from COG using this main purification device and prefilter will be explained with reference to FIG. 2.

First, the raw material COG is introduced with tar removal n 4 vc,
After the tar is removed, compressor 5
It is compressed to about kgf/cd, cooled in a cooler 6, and drained. Then the drained CO
G is introduced into the prefilter 7. This pre-filter 7
The inlet side of the COG is filled with alumina gel or silica gel, and the outlet side is filled with activated carbon. This pre-filter 7 adsorbs and removes moisture, ammonia, high boiling point hydrocarbons such as naphthalene, etc. in the COG. The pre-filter 7 has its adsorbent replaced after a certain period of use.The role of the pre-filter 7 is mainly to remove naphthalene, tar, etc., and even if water, ammonia, etc. break through, the adsorbent is replaced. There is no need to replace the activated carbon, and the time to replace it is determined by detecting the breakthrough of high boiling point hydrocarbons. Therefore, the alumina gel or silica gel in the pre-filter 7 has the role of preventing activated carbon from becoming excessively depleted by moisture. . Alternatively, depending on the composition of the raw material COG, the cooler 6 may not be used.

The COG that has come out of the pre-filter 7 is introduced into the charging tube 1 in the adsorption process of the raw rice 1w device 8. The COG introduced into the adsorption column 1 is first subjected to removal of silica gel S Qic water on the inlet 2 side, moisture, ammonia, and BTX@ hydrocarbons. BTX is generally activated carbon, 1
Although it is often adsorbed and removed by 0A diameter molecular sieves, it cannot be regenerated sufficiently by a non-thermal regeneration method such as an adsorption-regeneration method using pressure changes. On the other hand, although silica gel has a smaller capacity than activated carbon, it can be sufficiently regenerated by a regeneration method using pressure changes, and as a result, the amount of VC adsorbed becomes large.

Hydrogen sulfide, carbonyl sulfide, and water and BTX that were not removed by silica gel SG are removed by XMS. When hydrogen sulfide comes into contact with activated carbon or 5A diameter molecular sieves, it reacts with the enzymes and moisture in COG to produce solid sulfur, which poses a problem with old methods of regeneration using pressure changes. This type of reaction does not occur, and it can be easily regenerated using a regeneration method that uses pressure changes. Also, carbon dioxide gas is 1
It reacts with hydrogen sulfide using oX diameter molecular sieves 10A1'vlS as a catalyst to produce carbonyl sulfide, but
This carbonyl sulfide has a diameter of 10A.
1] Removed with AMS or next activated carbon AC. Therefore, the role of this 10A diameter molecular sieve is to remove hydrogen sulfide so that it does not flow into the next activated carbon layer, or to convert it into carbonyl sulfide.

Next, in activated carbon AC, light hydrocarbons, -carbon oxide,
Carbon dioxide gas etc. are removed, and BT) which could not be removed in the previous stage is also removed. Methane and carbon oxides that cannot be removed by activated carbon AC are adsorbed and removed in the next stage to remove light hydrocarbons, carbon oxides, carbon dioxide gas, etc. Compared to activated carbon, hydrogen for purging during low-pressure regeneration can be removed. The amount of gas increases, making it uneconomical. Therefore, the role of this activated carbon AC is to adsorb light hydrocarbons, carbon dioxide, carbon dioxide, etc., to reduce regeneration costs, and to absorb BTX that could not be adsorbed by the previous adsorbents. and carbonyl sulfide by adsorption and removal.

It mainly adsorbs and removes nitrogen and oxygen, and at the same time removes methane and carbon monoxide that could not be removed by the activated carbon in the previous stage.

In this way, highly pure hydrogen is led out as a product from the outlet 3 of the adsorption fil.

In this way, the adsorbent El(r
By filling silica gel SG 10 in order from the inlet 2 side of the OG, most of the components (impurities) other than hydrogen in the COG can be adsorbed and removed by the adsorption cylinder 1. Therefore, the prefilter 7 Since it is only necessary to remove high-boiling hydrocarbons such as tar and naphthalene, the amount of adsorbent can be reduced, and inexpensive alumina gel, silica gel, and activated carbon are sufficient, and the cost of replacement and disposal is not very high. In addition, since reuse is not performed, additional equipment necessary for regeneration is not required, and operation becomes easy. Furthermore, when replacing the adsorbent in the pre-filter 7, the main purifier 8
Since the N suction cylinder 1 is filled with the same kind of adsorbent as the adsorbent of the prefilter 7, there is no need to use another prefilter for a short time.

In addition, by setting the product R41111:i of the adsorbent in the adsorption column 1 as described above, each adsorbent exhibits unique performance and complements each other's performance. The safety factor only needs to be applied to the molecular sieves with a diameter of 58' and 1OA.On the other hand, if the activated carbon is to a certain extent, it can be reduced to less than the amount required by calculation, and the volume of the entire cylinder 1 can be reduced. Therefore, the cylinder 1 itself can be made smaller while maintaining a high overall safety factor.

In general, during regeneration by low-pressure regeneration, the amount of hydrogen gas for purge regeneration can be reduced. Furthermore, since the Ugt adhesive used is commonly used, it has high 4M reliability and is advantageous in terms of cost.

Hereinafter, a specific explanation will be given by showing examples.

〔Example〕

Raw material COG 30 Nm3/hr is sent to the compressor 5 through the tar remover 4, and '? Compress to atm. This compressed COG is then cooled by a cooler 6 and enters a pre-filter 7 after water and other condensate are separated.

The pre-filter is filled with 7Klli5E silica gel and 10E activated carbon and can withstand one year of use under normal usage conditions. The COG extracted from the prefilter 7 is introduced into the main purifier 81C.

The main purification device 8 is operated by a four-cylinder switching system having four adsorption cylinders 1, and has an internal volume of one cylinder [15075 mm].
Silica gel SG, 10A diameter molecular sieves 5 A M S from inlet 2 to the socket at a volume ratio of 1:
It was filled at a ratio of 3:20:15.

The purity of this raw paddy is 8 to 99.9.
13 Nm1/hr was obtained at 99-99.9%.

At the outlet of the prefilter 7, )3TX, hydrogen sulfide, carbonyl sulfide, ammonia, etc. were detected, but they were not detected at all in the product hydrogen, and most of the impurities in the product hydrogen were oxygen or nitrogen.

As a result, the purity and production amount of product hydrogen are long-term (approximately 3 months)
It was stable across vc, and no performance deterioration was observed.

As explained above, the COG refining device of the present invention is
The adsorbent filled in the adsorption cylinder of the main purification equipment is
Silica gel and molecular sieves are filled in this order from the upstream side of the G flow, so the pre-filter only needs to remove high-boiling hydrocarbons such as tar and naphthalene from the COG, and the amount of adsorbent packed can be extremely reduced. Equipment costs and j! F expenses can be significantly reduced. Also, main emotion g
The adsorption tube itself of the device can also be made smaller while maintaining a high safety factor. Furthermore, since a general-purpose adsorbent is used, reliability is high and it is advantageous in terms of cost. Further, there is an advantage that there is no need to prepare a spare pre-filter for replacing the pre-filter.

[Brief explanation of drawings]

FIG. 81!1 is an explanatory diagram showing an example of the manner in which adsorbent is filled in the adsorption column of the purification apparatus of the present invention, and FIG. 2 is a schematic configuration diagram showing an example of the purification apparatus of the present invention.

Claims (1)

[Scope of Claims] A coke oven gas purification device comprising a pre-filter and a main purification device that operates a plurality of adsorption cylinders filled with adsorbent by switching between adsorption and regeneration steps based on pressure changes, the main purification device comprising: A coke oven gas purification device characterized in that the adsorbents in the adsorption cylinder are filled in the order of silica gel, 10A diameter molecular sieves, activated carbon, and 5A diameter molecular sieves from the upstream side of the flow of raw coke oven gas. .