JP2900033B2 - Method for injecting a metered amount of powder material into a chamber under variable pressure by pneumatic means - Google Patents

Description

The present invention relates to a method for injecting a metered amount of powdered material into a chamber under variable pressure by means of pneumatic means at various points, wherein the powdered material having a high content in the propellant gas is Is formed in a single metering device and this mixture is propelled through a common primary conduit to a distribution head, where the mixture is split into secondary streams, each secondary stream being passed through a secondary conduit. To one of the injection points. The present invention will be described in detail with respect to preferred applications, but is not limited to such preferred applications, including solid combustible materials,
In particular, pouring coal into an industrial furnace, such as a blast furnace. Known methods and equipment for injecting solid combustible materials into a blast furnace fall into two main types. The first works with a relatively "lean" air stream, while in the second the air stream has a relatively high concentration of pulverized coal. In the first type of installation, using a dilute stream, the pulverized coal is released under pressure and enters a series of metering devices from a distribution hopper,
Here, a mixture of pulverized coal and propellant gas is formed, and the mixture thus formed is conveyed to an injection point in the blast furnace.
In these installations, one metering device is generally used for each pipe or pair of pipes, so that the amount injected through the pipes is individually metered. The weighing device used is of a known type and is described in European Patent Application 0,12.
A metering device with a slotted device or an alveolar rotor as proposed in US Pat. No. 6,917. These installations have the disadvantage of requiring a number of relatively long conduits between the distribution hopper and the blast furnace. Also, metering becomes difficult due to various variable parameters such as fluctuations in furnace pressure. In a second type of installation that employs a concentrated air flow, a single metering device is used in or downstream of the distribution hopper. In this metering device, the total flow of the powdered coal is adjusted so that a predetermined amount of the powdered coal is injected per unit time. These installations employ the method described at the outset, i.e., the division of a metered stream containing the required amount of coal into equal secondary streams in a distribution head. These arrangements have the advantage that the split head is located close to the furnace, thus reducing the length of the secondary conduit and thus also the congestion around the furnace. These installations are provided with a throttle section in the secondary conduit or distribution head, where the pressure drop required to accelerate the air flow to sonic speed is created. By accelerating the air flow to sonic speed, the advantage is that the flow conditions upstream of the location where the supercritical velocity occurs are no longer affected by the flow conditions downstream of this location. Of course, this has the advantage that the pressure inside the chamber into which the powder material is injected and other variable parameters no longer need to be taken into account. Compared to the first type of equipment, equipment working with concentrated streams of the above type has the disadvantage that the flow of each pipe can no longer be regulated individually. The object of the present invention combines the advantages of two known methods,
It is to provide a new method of the type described at the outset. To this end, the present invention provides a method of the type described at the outset, which is mainly characterized by regulating the flow rate of the air flow in each secondary conduit. The adjustment is preferably made in a variable throttle section where acceleration of the flow to supercritical speed occurs. Adjustments can be made automatically or manually under the control of a flow detector on each secondary conduit. The preferred embodiment will be described with reference to the accompanying drawings. This figure schematically shows a circuit for pneumatic injection of combustible material into a blast furnace. An air mixture consisting of powdered coal and a propellant gas, the flow of which corresponds to the amount of coal per unit time required by the blast furnace, is formed in the primary conduit 10 with the aid of a metering device 12, which is It can be a metering device of the type with movable slots, or it can be an air metering or other type of hopper. In this metering device 12, an air mixture with a high concentration of coal is formed, which can be diluted, if necessary, by the addition of a variable amount of inert gas injected through a conduit 14 upstream of the distributor. This air mixture is applied to a dispensing head 16 of the type recommended in Luxembourg patent 86,034.
Sent to In this distribution head 16, the primary air stream is split into secondary streams, each stream being sent through a secondary conduit to one of the pipes 22 of a blast furnace (not shown). The number of secondary conduits 18 corresponds, for example, to the number of pipes, or half of the number of pipes. According to the present invention, each secondary conduit 18 is provided with a variable section restriction 20. The throttle 18 is preferably constituted by a valve of the type recommended in Luxembourg patent application 86,311 in which a passage is formed by the rotation of a movable socket in a fixed socket, and a large or large Openings and slots are provided that can partially overlap to provide a small passage. Acceleration of the secondary air flow is preferably performed at the throttle 20. Thus, the method according to the invention has all the advantages of a system for injection at the speed of sound. That is, the secondary conduit can be made as short as possible to reduce congestion around the furnace. Furthermore, the metering conditions in the metering device 12 are not affected by fluctuations in the pressure downstream of the throttle 20, especially in the blast furnace. Valve 20 can be manually adjusted to take into account conditions in the furnace. Thus, the flow rate through the various secondary derivations is established as a function of the opening of the restrictor 20, and the total amount of coal injected per unit time is determined by the metering device 12. Thus, the function of the distributor 16 is described in Luxembourg patent application 86,0.
Differs from the function of the distributor proposed in No. 34. However, in the latter, the distributor actually has the function of distribution, which is a uniform distribution, with the same coal flow passing through each secondary conduit. In contrast, in the method according to the invention, the distributor 16 stands alone to split the primary stream into secondary streams, the flow rate of the secondary stream varying as a function of the variable cross section of the restriction 20. The coal flow rate in each secondary conduit 18 can be measured and the passage cross-section of the valve 20 can be automatically adjusted so that a defined injection flow rate is present in each pipe 22. This automatic adjustment can compensate or eliminate interfering factors such as partial blockage of the secondary conduit 18 or the passage of the distributor 16.

BRIEF DESCRIPTION OF THE DRAWINGS The figure schematically shows a circuit for pneumatic injection of combustible material into a blast furnace. 10… Primary conduit, 12… Measuring device, 14… Conduit, 16…
Dispensing head, 20 ... throttle, 22 ... pipe.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hans-Klaus-Scott, Germany Day 4220, Deinslaken, Beethoven Shuttle 3a (56) References JP-A-60-97121 (JP, A) Shokai 61-157533 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B65G 53/56 B65G 53/66

Claims (1)

(57) [Claims] A method of injecting a metered amount of powdered material into a chamber under variable pressure at various points by pneumatic means, wherein a single mixture of an air mixture containing a relatively high content of powdered material in the propellant gas is obtained. Formed in the apparatus, this mixture is propelled through a common primary conduit to a dispensing head, where the mixture is split into secondary streams, each secondary stream being passed through a secondary conduit to one of the injection points. Accelerating the air flow to a critical speed in the variable throttle section in a manner wherein the flow rate of the air flow is adjusted in each secondary pipe by a throttle having a variable throttle section in each secondary conduit. Method. 2. 2. The method according to claim 1, wherein the adjustment of the variable throttle section is performed manually. 3. 3. The method according to claim 1, wherein the adjustment of the variable throttle section is performed automatically under the control of a flow detector provided in each secondary conduit.