JPS60228598A - Method and device for manufacturing homogeneous mixture by use of air stream mill from coal powder and lime powder or dolomite powder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a pneumatic mill (roll mill), particularly of vertical construction, with a grouped sieve to produce a homogeneous mixture of coal powder and lime or dolomite powder. METHODS AND APPARATUS. As is known, it has been proposed to mix lime powder with coal powder to combine sulfur contained in coal during combustion, that is, to mix coal powder and lime powder. The difficulty with this method is to homogenize both powdered substances. Since the coal powder/lime powder mixture fed to the coal powder combustion plant is not ideally homogeneous, the chemical bonding of the sulfur during the combustion process is not optimal.

The present invention is to eliminate the above-mentioned drawbacks.

The present invention advantageously provides a pneumatic mill of vertical construction (
It consists in the dosing of lime or dolomite using a roll mill) in the charging area of the mill without crushing it. The loading rate of limestone depends on the loading rate of crude coal. In this case, depending on the sulfur content of the raw coal, the loading rate of limestone is proportioned to the raw coal loading rate. The charge mixture thus obtained is loaded into the mill via a suitable transfer device equipped with an air shut-off and is homogeneously ground there. The powder mixture thus obtained, abbreviated as refined pulverized coal, is conveyed out of the mill by means of a stream of air or gas.

During coal comminution in the blower, the "refined pulverized coal" passes directly in the mill's primary air stream to a coal powder combustion device, for example a steam boiler. In central comminution units with intermediate bunkers, the "refined pulverized coal" is separated from the carrier air stream via cyclones and/or filters and accumulated in pulverized coal silos. Removal from the pulverized coal silo and retransfer to the coal powder combustion equipment are performed by known methods.

In both cases, the repellent sulfur oxide of coal powder combustion reacts chemically directly with lime powder or dolomite. In this manner, release of unbound sulfur oxide into the atmosphere is largely avoided.

Simultaneous grinding thus has the significance of optimizing the combustion of coal powder with minimal environmental pollution and of reducing the costs for process-technical equipment.

The latter means that no other grinding equipment is required for lime production and dolomite production. That is, the cost required for equipment investment is significantly reduced.

The invention will be explained below with reference to exemplary embodiments illustrated in the accompanying drawings.

In the drawing, raw coal is removed from a raw coal bunker 1 in the direction of arrow 2 by a raw coal distributor. For example, cutoff slider 4
A trough chain conveyor is provided which allows the raw coal to be separated from the bunker via a trough chain conveyor. The take-out conveyor is driven via a transmission mechanism 5 and a motor 6 whose rotation speed is adjustable.

The limestone or dolomite stone is removed from the storage bunker 7 via a removal mechanism 8. The unloading mechanism includes a drive section 9 equipped with a motor 10 whose rotation speed can be changed. The carried out limestone falls into the chute 16 and falls into the common chute 11 together with the coarse coal. From here, the copper raw material reaches a conveying device - illustrated by screw 12 - which is equipped with a closed constant-speed drive 13 . The raw coal and limestone are conveyed via a conveyor 12 in the direction of arrow 14 into a pneumatic mill 15 with air exclusion.

The entire transport and removal system for the crude coal and limestone basins is illustrated in the drawings. It is important that the removal conveyors 3 and 8 are equipped with a variable-speed drive in order to meter the respective material stream to be removed. What is special is that the speed-variable drives 5 and 9 of both the coarse coal and the limestone or dolomite stone basin are connected to each other via a proportional control mechanism 29. The triangle drawn in the control mechanism symbol with a letter opening means that the rotation speed of the drive unit 9 relative to the limestone metering unit 8 is dependent on the rotation speed of the drive unit 5 relative to the coarse coal metering unit 3. . The rotational speed of the raw coal metering section 30 determines the raw coal charge rate to the mill. Depending on this raw coal loading ratio, a predetermined percentage amount of limestone is added to the metering section 8 via the variable speed drive 9. If the coarse coal flow fluctuates, via the control mechanism 29,
It is ensured that the mixing of raw coal to limestone always takes place in equal percentages.

The raw materials removed in equal proportions in the loading area are simultaneously ground in the mill 15 on the grinding table 17 by the grinding bodies 27 .

In the illustrated mill, the grinding table 17 is equipped with a drive section 18, which drives the grinding table 17 at a constant rotational speed. The material to be crushed is crushed by a crushing body (roll) 27 and a crushing table 1.
It is crushed between 7 and 7. The raw materials consisting of coal and limestone are mixed during crushing and are ejected from the crushing table 17 by centrifugal force.

The air or gas flow generated by a blower (not shown) flows into the grinding house according to arrow 19 at the inlet connection. This air or gas stream is accelerated to a high velocity in an annular gap or vane rim 21 surrounding the grinding table 17, and centrifugally releases the disintegrated material from the grinding table 17. It is sent into the upper sieve 22.

The sieve shown has a rotor 23 which is driven via a shaft 24 and is provided with strips 25. The degree of grinding is adjusted according to the rotation speed of the rotor 2S. The material to be crushed that has not been crushed to a fineness suitable for a product is dropped back onto the crushing table 17 for (re) crushing. The material to be ground, which has been ground to the final grinding degree, passes through a sieve and is discharged together with carrier air in the direction of arrow 26.

During the grinding and during the transport with carrier gas or carrier air, mixing and thorough homogenization of the two charges of material to be ground take place. The homogenized powder/air mixture is fed directly or after intermediate storage to a coal powder combustion unit.

The illustrated mill 15 with sieve 22 is only an example. Any other style of airflow mill with combined screens is suitable for uniform grinding, screening and discharge of the two-component charge.

[Brief explanation of the drawing]

The drawing shows an embodiment of the device according to the invention. The symbols in the figure are 1.7... Storage bunker 5.8... Retrieval conveyor 15...
... Mill's agent: Hikaru Esaki Good agent: Hikaru Esaki May 27, 1955 Commissioner of the Patent Office Gakudono Shiga■, Indication of the case Showa β year patent application No. 27 da□/g No. 3 Relationship with the case of the person making the amendment Applicant 4 Agent 5. Date of amendment order: 2, Showa 1. o year
q 10th 0, +c-,,ZT'. 6 Subject of correction. l Mt. Tsugumi Saramu - engraving of the drawings. (No change in content)7.
Details of the amendments are as per the attached sheet.

Claims (1)

[Claims] 1. In a method for producing a homogeneous mixture of coal powder and lime powder or dolomite powder using a pneumatic mill with a vertical deaf structure having a bundled sieve, and loading the pneumatic mill with limestone or dolomite stone in equal proportions into a metering and feeding device in a loading area upstream of the pneumatic mill. 2. The process as claimed in claim 1, wherein the limestone or dolomitic stone is metered in a proportion by weight of the coal necessary to chemically bind the sulfur content of the coal in each case. 4. The method according to claim 1 or 2, wherein limestone or dolomite is added in a weight ratio of 1 to 10 percent of coal. 4. The method of claims 1 to 3, wherein the raw coal and limestone are loaded together into a pneumatic mill for simultaneous crushing and screening.翫 A method for producing a homogeneous mixture of coal powder and lime powder or dolomite powder using a pneumatic mill with a vertical construction style having a grouped sieve, the method comprising:
In an apparatus for carrying out the method described above, in which coarse coal and limestone or dolomite stone are charged into a pneumatic mill in equal proportions by means of a metering and feeding device in the loading area upstream of the pneumatic mill, the respective associated take-off conveyors A separate storage bunker (L17) for coarse coal and a reservoir of limestone or dramite stone is provided, with a diameter of 3°8, and that the removal conveyor (3, 8) itself can be driven at a variable speed. , and behind this take-off conveyor (398) a common mill (15) for simultaneously crushing the raw coal and limestone or dolomite stone.
The above-mentioned device, characterized in that it is connected to. 4. Device according to claim 5, in which the drives (5p9) of the take-off conveyor (318) are coupled to each other via a control mechanism (29). 7. The control mechanism (29) controls the drive part (9) of the take-off conveyor (8) for limestone or dolomite stone depending on the rotation speed of the drive part (5) of the take-off conveyor (3) for coarse coal. 7. The device according to claim 6, wherein the device is a proportional control mechanism. a. Any one of claims 5 to 7 is provided with a device for charging the raw coal together with limestone or dolomitic stone into the mill (15) with air exclusion. The device described in.