JP2014172997A - Coke oven gas recovery method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coke oven gas recovery method capable of removing sludge accumulated in a dry main without requiring any considerable renewal even in a coke oven of an existing facility.SOLUTION: In a coke oven 1 that recovers coke oven gas generated during dry distillation of coal, a flow rate of gas in the terminal of a dry main 4 is 1 m/sec or more. Therefore, steam having a temperature of 100-180°C may be injected into the dry main 4.

Description

  The present invention relates to a method for recovering coke oven gas in a coke oven.

  In the coke oven, coal is charged into the carbonization chamber, and in the process of dry distillation of the coal by the combustion heat of the gas in the combustion chamber adjacent to the carbonization chamber, coke oven gas mainly composed of volatile components and pyrolysis gas in the coal is Occur.

  The coke oven gas is recovered from a riser pipe installed at the upper part of each coking chamber of the coke oven to a dry main (coke oven gas recovery main pipe). Aqueous water is sprayed from the upper part of the dry main body, and the coke oven gas is cooled to about 90 ° C. to obtain gas, coal tar, and aqueous gas solution. This gas liquid passes through the suction main (main pipe for suction) from the off-take main (connection pipe) connected to the dry main, and is purified by a purification device (for example, an electric dust collector or gas purification device that removes dust). The coal powder contained in the gas liquid and the sludge during dry distillation are refined, and tar and light oil separated from the gas liquid are sent to a by-product processing facility.

  The dry main structure of the coke oven is horizontally attached to the upper part of the backstay etc. with the same cross-sectional shape as the inner shape. For this reason, sludge and the like gradually accumulate and adhere to the bottom of the dry main. When fixed, the deposit further increases, obstructing the flow of the aqueous solution, reducing the gas flow cross section, causing a drift, and eventually clogging and delaying the recovery of the coke oven gas. Conventionally, as a method for removing deposits, a method has generally been adopted in which aqueous water is introduced from the end of the dry main body to be dissolved, or vapor is jetted vertically from an inspection port to be melted.

  As a sludge removal technique, for example, as a method for treating sludge in a crude oil tank, a method of dissolving a sludge by supplying a solution containing hydrocarbon oil has been proposed. (See Patent Document 1)

  Further, as a method for coping with deposits such as sludge in the dry main of the coke oven, a method has been proposed in which an inclined plate is provided in advance at the bottom of the dry main to facilitate the flow of gas liquid and sludge. (See Patent Document 2)

JP-A-2005-349240 JP 2009-249438 A

  As a countermeasure against sludge in the dry main of a coke oven, as described in Patent Document 1, when a hydrocarbon or a solution or chemical equivalent thereto is administered, sludge may be surely removed. The possibility of affecting components such as light oil and tar recovered in In addition, when applied to existing facilities, it is necessary to construct a new drug administration device, which is very expensive.

  Further, as described in Patent Document 2, the method of providing an inclined plate in a dry main may be effective when a new dry main is renewed, but for a dry main that has already been deposited. It is impossible to install an inclined plate.

  In view of the above circumstances, an object of the present invention is to provide a coke oven gas recovery method that enables removal of sludge accumulated in a dry main without requiring significant renewal even in a coke oven of existing equipment. To do.

  The present inventors examined the cause of deposits of sludge and the like on the bottom of the dry main body. As a result, there was an actual situation that clogging tends to occur as the distance from the off-take main located at the center of the dry main body increases. Therefore, as a result of comprehensive evaluation from the viewpoint of equipment and operation, the amount of generated gas is smaller and the flow rate of gas is slower at the end of the dry main (the farthest from the off-take main), so the suspended dust in the generated gas It came to a conclusion that sedimentation of dry mains occurred. Therefore, the present invention has found that the above-mentioned problems can be solved by increasing the gas flow rate at the end of the dry main body to a flow rate in the vicinity of an offtake main without clogging, and has completed the present invention.

The gist of the present invention is as follows.
(1) A method for recovering coke oven gas, wherein a coke oven gas that recovers coke oven gas generated during coal carbonization has a gas flow rate of 1 m / sec or more at a dry main end.
(2) The method for recovering coke oven gas as described in (1) above, wherein steam having a temperature of 100 ° C. to 180 ° C. is introduced into the dry main.
(3) The method for recovering coke oven gas as described in (2) above, wherein steam is injected from the bottom of the dry main body in a range of 1/2 to 1/10 of the inner diameter of the dry main.
(4) The method for recovering coke oven gas as described in (2) or (3) above, wherein the diameter of the steam nozzle is 1/120 to 1/30 of the inner diameter of the dry main.

  According to the present invention, the gravity flow of suspended dust is eliminated by increasing the gas flow rate, and the sludge clogging of the dry main body is eliminated, so that no manual cleaning work is required when clogged. In addition, there is no decrease in the amount of gas recovered due to dry main clogging, and stable operation is possible.

It is a model top view of the gas recovery equipment which collects a coke oven and coke oven gas. It is a schematic diagram explaining the dry main peripheral equipment.

Embodiments according to the present invention will be described below with reference to the drawings.
Referring to FIG. 1, the coke oven 1 is provided with a large number of carbonization chambers of about 50 kilns, and coal is carbonized in the carbonization chamber. After that, it is recovered by the dry main 4. A water-free nozzle 7 (FIG. 2) is installed at the upper part of the bend pipe 3, and the coke oven gas is cooled to about 90 ° C. by spraying the high-pressure or low-pressure water on the coke oven gas. The coke oven gas becomes a gas liquid of coal, coal tar, and water.

An off-take main 5 is connected to the lower center of the dry main 4, and the gas, coal tar, and water solution recovered from the dry main 4 flow to the central portion of the dry main 4 and are taken off. 5 is sent to the by-product processing facility via the suction main 6. Generation of coke oven gas depending on the volume of the processing time and the coking chamber is 200Nm ³ / h~400Nm ³ / h approximately per kiln. The coke oven gas is sucked at a pressure of about −1000 Pa by a pump (not shown) installed in the by-product processing facility, and the damper inside (not shown) installed in the off take main 5 The positive pressure is maintained at about + 100Pa. The diameter of the dry main 4 is about 2000mm, though it depends on the factory.

When the gas flow rate in the dry main of the coke oven gas in such a case is calculated, for example, when the gas amount is 300 Nm ³ / h, the gas temperature is 90 ° C., and the diameter of the dry main 4 is 1800 mm, the gas flow rate is 0.06 m / sec. And most of the suspended dust settles down by gravity and accumulates at the bottom of the dry main. And as the amount of gas increases as the distance to the offtake main 5 approaches, the gas flow rate gradually increases. Therefore, sludge is deposited almost linearly with a constant slope from the end of the dry main to the center of the dry main.

  At this time, by adjusting the suction pressure of the by-product processing facility or adjusting the opening of the damper installed in the off-take main 5, the gas suction amount is increased and the gas flow rate inside the dry main body is increased to increase the floating dust. By suppressing the gravity sedimentation, sludge accumulation can be suppressed. The gas flow rate should be 1 m / sec or more at the end of the dry main.

  However, if the gas flow rate is increased and the pressure inside the dry main body is lowered too much, air may enter the dry main body and the calorific value of the coke oven gas, which is a by-product, is reduced, which may adversely affect the operation. Therefore, although the upper limit of the gas flow rate is not particularly defined in the present invention, the actual gas flow rate when the present invention is applied should be determined in consideration of this fact.

  As a method of increasing the gas flow rate without reducing the pressure inside the dry main, there is a method of introducing a fluid from the outside. In this case, the fluid used is preferably steam. Although it is possible with hot water or cold water, the vapor condenses at 100 ° C or lower to become a liquid, so that an increase in the amount of suction gas can be suppressed. Air and nitrogen are not preferred because they reduce the amount of heat of the gas.

  The number of the steam nozzles to be inserted is arbitrary, but it is preferable to insert at least one at or near the dry main end in order to set the gas flow rate at the dry main end to 1 m / sec or more. As the steam flows toward the off take main, it condenses and becomes a liquid. Therefore, it is also preferable to replenish the steam by inserting a steam nozzle at a location on the way to the off take main. Generally, it is sufficient to insert one by one in increments of 3 to 5 kilns. For example, in the case of a coke oven 1 having a scale of about 50 half furnace groups and an offtake main 5 at a position corresponding to the 25th center portion, the 1st, 6th, 11th, and 16th ovens It is more effective to insert 5 in total at the positions corresponding to the eyes and 21st kiln. However, if the amount of steam that can be used is limited, an effect can be expected even with three steamers at positions corresponding to the 1st, 6th, and 11th kilns. If you want to concentrate on the area where the sludge accumulation risk at the end is high, you may install it at the position corresponding to the 1st kiln, 4th kiln, 7th kiln.

  When sludge is deposited almost linearly with a constant slope from the end of the dry main to the center of the dry main, when sludge at the end is concentrated, the sludge dissolved in the water gradually flows downstream. . However, in actuality, sludge has some unevenness in the dry main, and it stays in the uneven part or is dammed up. In such a case, by concentrating the steam on the downstream side, there is no accumulation on the downstream side, and the flow of the safe water becomes smooth.

  The temperature of the steam used is preferably 100 ° C to 180 ° C. The internal temperature of the dry main body is approximately 80 ° C. to 90 ° C., and if high-temperature steam is used, it does not condense and flows to the off-take main 5 as a gas, so that the gas volume increases and obstructs the suction of the coke oven gas. As a result of investigations by the inventors, it was found that the vapor temperature of 180 ° C. is the critical temperature for condensation in the dry main in an environment where the dry main internal temperature is 90 ° C. The steam temperature is preferably 100 ° C to 150 ° C, more preferably 100 ° C to 120 ° C. As described above, the steam temperature control is important, but the coke oven gas inside the dry main also needs to be controlled so as not to exceed 90 ° C., that is, the water spray control.

  The vapor injection position inside the dry main may be injected from a range of 1/2 to 1/10 of the dry main inner diameter from the bottom of the dry main. When steam is injected above the position of 1/2, a reverse flow is caused toward the ascending pipe 2 through the bend pipe 3, which adversely affects gas recovery. On the other hand, if the steam is injected at a position lower than the 1/10 position, it interferes with the water that flows through the bottom of the dry main body, so the effect of the steam is reduced. The vapor injection position is preferably in the range of 1/4 to 1/10 of the dry main inner diameter from the dry main bottom, and more preferably in the range of 1/7 to 1/10.

In addition, when implementing this invention in the dry main which has already accumulated sludge, it is good to inject in the position of 50 mm-200 mm right above sludge. Sludge accumulates with a linear slope when viewed macroscopically, but it has irregularities depending on the location, and when steam is injected from a concave region to a convex portion, it collides with the sludge and produces a vortex. If the distance from the top of the sludge to the steam nozzle is more than 200mm, the effect of the steam will be reduced due to the influence of the vortex.
In addition, by setting the steam injection position directly above the sludge, the steam injection energy serves to help water-relief that plays the role of flowing not only suspended dust but also the already accumulated sludge.

  The diameter of the nozzle that injects the steam is preferably 1/120 to 1/30 of the inner diameter of the dry main. If the diameter is smaller than 1/120, the pressure loss increases, and the range of the vapor spread becomes narrow, so the effect of increasing the gas flow velocity of the vapor is diminished. On the other hand, if it is larger than 1/30, a large amount of steam is required to secure the flow velocity of the injection, and a negative pressure is generated upstream due to the ejector effect of the steam, and the pressure inside the dry main body is reduced. This is because harmful effects such as intrusion occur. The diameter of the steam injection nozzle is preferably 1/120 to 1/60 of the dry main body inner diameter, more preferably 1/120 to 1/70.

  The direction of the nozzle for injecting the steam is preferably directed to the downstream when the direction of the off-take main 5 is downstream and the end of the furnace is upstream. Preferably, the nozzle angle should be parallel to the dry main 4 in order to carry the suspended dust downstream. Moreover, when placing emphasis on flowing sediment sludge, it may be directed slightly downward.

  The vapor pressure should be as high as possible, but it is sufficient that about 50 kPa to 70 kPa can be secured. However, when steam is injected in a region close to the offtake main, for example, when used at a position within a distance corresponding to 5 kilns from the offtake main 5, it is better to reduce it to about 25 kPa. This is because when high-pressure steam is injected in the vicinity of the off-take main, the influence of the steam appears to the facing dry main 4 across the off-take main 5, thereby preventing gas recovery of the facing dry main 4.

  As the material of the steam nozzle, ordinary carbon steel may be used. However, since there is a small amount of hydrogen sulfide and ammonia in the water in the dry main body, it is recommended to use a corrosion resistant material such as corrosion resistant stainless steel.

  In order to confirm the effect of the present invention, the damper installed in the off-take main 5 is opened so that the flow velocity inside the actual dry main (inner diameter 1800 mm) of the existing coke oven (half furnace group 50 kiln) is 1 m / sec. The degree was adjusted. Due to concerns about air contamination, the internal flow velocity in the dry main at the 15th kiln was set to 1 m / sec or more, not at the end with much accumulation. The implementation period was half a month from early March to early April.

  As a result, the spatial level of dry mains (corresponding to the height of the space above the sludge surface) was reduced to 1020 mm (from the start of measurement to 1100 mm (after the end of measurement)).

  Next, steam was allowed to flow into the dry main, and the level change of the deposited sludge was measured. Since there was much sludge accumulation at the end of the dry main, steam nozzles (inner diameter 16mm) were placed in parallel with the dry main at positions corresponding to the 3rd vent pipe of the 2nd, 5th and 8th kilns from the dry main end. It was installed in the direction of the offtake main, and steam with a pressure of 70 kPa and a temperature of 120 ° C was injected from each nozzle at a flow rate of 160 kg / h. Under these conditions, the gas flow rate was set to 1.0 m / sec near the position corresponding to the second kiln from the end of the uppermost dry main. The injection position was 50 mm directly above the sludge at each position. The installation period was one and a half months from the end of April to the beginning of June.

  As a result, the space level of the dry mains (corresponding to the height of the space above the sludge surface) is greatly changed from 460 mm (before the start of measurement) to 470 mm (after the end of measurement) at the nozzle part corresponding to the second kiln. In contrast, the nozzles corresponding to the 5th and 8th kilns were changed from 960mm (before the start of measurement) to 1240mm (after the end of measurement) and from 400mm (before the start of measurement) to 540mm (after the end of measurement). There was a marked decrease in sediment sludge.

DESCRIPTION OF SYMBOLS 1 Coke oven 2 Rising pipe 3 Bend pipe 4 Dry main 5 Off-take main 6 Suction main 7 Water-resistant nozzle

Claims (4)

  A method for recovering coke oven gas, characterized in that, in a coke oven that recovers coke oven gas generated during coal carbonization, the flow rate of gas at the end of the dry main is 1 m / sec or more.   The method for recovering coke oven gas according to claim 1, wherein steam having a temperature of 100 ° C to 180 ° C is introduced into the dry main.   The method for recovering coke oven gas according to claim 2, wherein steam is injected from the bottom of the dry main body in a range of 1/2 to 1/10 of the inner diameter of the dry main body.   4. The method for recovering coke oven gas according to claim 2, wherein the diameter of the steam nozzle is 1/120 to 1/30 of the inner diameter of the dry main.

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