INTELLIGENT CONTROL METHOD FOR DRY DENSE MEDIUM FLUIDIZED BED SEPARATOR

Abstract

An intelligent control method for a dry dense medium fluidized bed separator includes supplying air to fluidize a bed; estimating an initial bed density according to a washability curve of a raw coal; detecting a magnetic material content in the bed to obtain a real-time bed density, and adjusting the real-time bed density according to a result from an analysis on a deviation from the initial bed density; during separation, adjusting a medium addition amount and a scraper discharge speed to maintain a stability of a bed height; separating the raw coal in the dry dense medium fluidized bed separator to obtain a clean coal product; and detecting a product ash content of the clean coal product, comparing the product ash content with a target ash content, and if a difference between the product ash content and the target ash content exceeds an expectation, adjusting the initial bed density.

Claims

1. An intelligent control method for a dry dense medium fluidized bed separator, comprising the following steps: step 1: controlling a fan to blow an air flow into a bed body to fluidize a bed, when a fluctuation of a pressure drop of the bed becomes stable, controlling an air pressure and an air volume to maintain stability; and estimating an initial bed density ρ.sub.e.sup.0 according to a washability curve of a selected raw coal; step 2: detecting a magnetic material content in the bed, calculating a real-time bed density ρ.sub.e.sup.t, comparing the real-time bed density ρ.sub.e.sup.t with the initial bed density ρ.sub.e.sup.0, adjusting a medium addition valve according to a result from the comparing, and adding a medium to the dry dense medium fluidized bed separator; calculating a deviation D.sub.1=|ρ.sub.e.sup.t−ρ.sub.e.sup.0| of the real-time bed density ρ.sub.e.sup.t from the initial) bed density ρ.sub.e.sup.0, wherein if D.sub.1≤A.sub.1, it indicates that the deviation meets an expectation, the real-time bed density is not adjusted, wherein A.sub.1 is a density deviation threshold; if D.sub.1>A.sub.1 and ρ.sub.e.sup.t>ρ.sub.e.sup.0, a circulating medium is added to the dry dense medium fluidized bed separator to reduce the real-time bed density; if D.sub.1>A.sub.1 and ρ.sub.e.sup.t<ρ.sub.e.sup.0, a magnetite powder is added to the dry dense medium fluidized bed separator to increase the real-time bed density; and the circulating medium is a magnetite powder mixture containing a fine-grained coal slime, which is discharged with a separation product and has not been magnetically separated; step 3: controlling and adjusting a scraper discharge speed and a medium addition amount to maintain a stability of a bed height; and separating the selected raw coal in the dry dense medium fluidized bed separator to obtain a clean coal product; acquiring a real-time bed height H.sub.t, and calculating a deviation D.sub.2=|H.sub.t−H.sub.0| of the real-time bed height H.sub.t from a set height H.sub.0, wherein if D.sub.2≤A.sub.2, it indicates that the deviation meets an expectation, the bed height is not adjusted, wherein A.sub.2 is a height deviation threshold; if D.sub.2>A.sub.2 and H.sub.t>H.sub.0, the scraper discharge speed is increased and meanwhile the medium addition amount is reduced to reduce the bed height; and if D.sub.2>A.sub.2 and H.sub.t<H.sub.0, the scraper discharge speed is reduced and meanwhile the medium addition amount is increased to increase the bed height; and step 4: detecting, in real time, a product ash content of the clean coal product obtained by the separating, and comparing the product ash content with a target ash content of the clean coal product; and if a difference between the product ash content and the target ash content exceeds an expectation, adjusting the initial bed density; calculating a deviation D.sub.3=|Ad.sub.t−Ad.sub.0| of the product ash content Ad.sub.t detected in real time from the target ash content Ad.sub.0 of the clean coal product, wherein if D.sub.3≤A.sub.3, it indicates that the deviation meets the expectation, the initial bed density is not adjusted, wherein A.sub.3 is an ash content deviation threshold; if D.sub.3>A.sub.3 and Ad.sub.t>Ad.sub.0, and the initial bed density is reduced, that is, an amount of a circulating medium added is increased and an amount of a magnetite powder added is reduced; if D.sub.3>A.sub.3 and Ad.sub.t<Ad.sub.0, and the initial bed density is increased, that is, the amount of the magnetite powder added is increased and the amount of the circulating medium added is reduced; and the circulating medium is a magnetite powder mixture containing a fine-grained coal slime, which is discharged with a separation product and has not been magnetically separated.

2-4. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 is a flowchart of intelligent control of a dry dense medium fluidized bed separator.

DESCRIPTION OF THE EMBODIMENTS

[0030] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] The process of an intelligent control method for a dry dense medium fluidized bed separator according to the present invention is shown in FIG. 1, including the following steps.

[0032] In step 1, a fan is controlled to blow an air flow into a bed body to fluidize the bed, when a fluctuation of a pressure drop of the bed becomes stable, an air pressure and an air volume are controlled to maintain stability, and a separation density, i.e., an initial bed density D.sub.e.sup.0, is estimated according to a washability curve of a selected raw coal.

[0033] In step 2, a magnetic material content in the bed is measured through a magnetic material content detector, a real-time bed density D.sub.e.sup.t is calculated and compared with the initial bed density D.sub.e.sup.0, a medium addition valve is adjusted according to a result from the comparing, and a medium is added to the separator so that a deviation of the real-time bed density from the initial bed density meets an expectation. Details are described as follows.

[0034] A deviation D.sub.1=|ρ.sub.e.sup.t−ρ.sub.e.sup.0| of the real-time bed density P: from the initial bed density ρ.sub.e.sup.0 is calculated, wherein if D.sub.1≤A.sub.1, it indicates that the deviation meets an expectation, the bed density is not adjusted, and A.sub.1 is a density deviation threshold; if D.sub.1>A.sub.1 and ρ.sub.e.sup.t>ρ.sub.e.sup.0, a circulating medium is added to the separator to reduce the bed density; if D.sub.1>A.sub.1 and ρ.sub.e.sup.t<ρ.sub.e.sup.0, magnetite powder is added to the separator to increase the bed density; and the circulating medium is a magnetite powder mixture containing fine-grained coal slime which is discharged with a separation product and has not been magnetically separated, and since the fine-grained coal slime is mixed therein, the circulating medium has a low density and can be used to adjust the bed density.

[0035] In step 3, during the separation, accumulation of coal slime content will reduce the bed density, and therefore, high-density magnetite powder may be added to the separator. After the magnetite powder is added, a bed height is changed, a scraper discharge speed and a medium addition amount are controlled and adjusted to maintain the stability of the bed height. The raw coal is separated in the separator to obtain a clean coal product. Details are described as follows.

[0036] A real-time bed height H.sub.t is acquired, and a deviation D.sub.2=|H.sub.t−H.sub.0< of the bed height H.sub.t from a set height H.sub.0 is calculated, wherein if D.sub.2≤A.sub.2, it indicates that the deviation meets an expectation, the bed height is not adjusted, and A.sub.2 is a height deviation threshold; if D.sub.2>A.sub.2 and H.sub.t>H.sub.0, the scraper discharge speed is increased and the medium addition amount is reduced at the same time to reduce the bed height; and if D.sub.2>A.sub.2 and H.sub.t<H.sub.0, the scraper discharge speed is reduced and the medium addition amount is increased at the same time to increase the bed height.

[0037] In step 4, a product ash content of the clean coal product obtained by the separation is detected in real time through an online ash content tester on a clean coal conveying belt, and compared with a target ash content of the clean coal product. If a difference between the product ash content and the target ash content exceeds an expectation, the initial bed density is adjusted. Details are described as follows.

[0038] A deviation D.sub.3=|Ad.sub.t−Ad.sub.0| of the real-time clean coal product ash content Ad.sub.t from the target ash content Ad.sub.0 of the clean coal product is calculated, wherein if D.sub.3≤A.sub.3 it indicates that the deviation meets an expectation, the initial bed density is not adjusted, and A.sub.3 is an ash content deviation threshold; if D.sub.3>A.sub.3 and Ad.sub.t>Ad.sub.0, the initial bed density is reduced, that is, the addition amount of the circulating medium is increased and the addition amount of the magnetite powder is reduced; and if D.sub.3>A.sub.3 and Ad.sub.t<Ad.sub.0, the initial bed density is increased, that is, the addition amount of the magnetite powder is increased and the addition amount of the circulating medium is reduced.

[0039] The above are the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should be regarded as the protection scope of the present invention.