Intelligent control method for dry dense medium fluidized bed separator

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 ρe0 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 ρet, comparing the real-time bed density ρet with the initial bed density ρe0, 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 D1=|ρet−ρe0| of the real-time bed density ρet from the initial) bed density ρe0,
• wherein if D1≤A1, it indicates that the deviation meets an expectation, the real-time bed density is not adjusted, wherein A1 is a density deviation threshold;
• if D1>A1 and ρet>ρe0, a circulating medium is added to the dry dense medium fluidized bed separator to reduce the real-time bed density;
• if D1>A1 and ρet<ρe0, 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 Ht, and calculating a deviation D2=|Ht−H0| of the real-time bed height Ht from a set height H0,
• wherein if D2≤A2, it indicates that the deviation meets an expectation, the bed height is not adjusted, wherein A2 is a height deviation threshold;
• if D2>A2 and Ht>H0, the scraper discharge speed is increased and meanwhile the medium addition amount is reduced to reduce the bed height;
• and
• if D2>A2 and Ht<H0, 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 D3=|Adt−Ad0| of the product ash content Adt detected in real time from the target ash content Ad0 of the clean coal product,
• wherein if D3≤A3, it indicates that the deviation meets the expectation, the initial bed density is not adjusted, wherein A3 is an ash content deviation threshold;
• if D3>A3 and Adt>Ad0, 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 D3>A3 and Adt<Ad0, 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.