Application Practice of Melting Furnace Control Technology in Melting Furnace

Fujian Province, a smelting enterprises 200kg melting furnace 1 set, the main melting gold, silver material. Melting furnace smelting open feeding and discharging, the amount of flue gas generated is large when feeding; the furnace body should be dumped when discharging, the flue gas is difficult to collect; the temperature of the flue gas changes greatly during the smelting process, the discharge rate is large, and the flue gas contains The dust concentration is high, and the pollution hazard is serious, which affects the physical and mental health of the operators.

To this end, the production practice has successfully applied the “integrated rectangular umbrella-shaped smoking cover, a smashing foam washing, and an efficient defogging purification technology, so that all the flue gas source flue gas enters the processing system. After treatment, it meets the standard discharge, ensuring good performance. Operating environment.

Basic data:

Flue gas dust concentration: 850rrg / Nm ;

Treatment of flue gas volume: 13000m / h ;

Flue gas change temperature: 1000 °C furnace mouth , into the dust cover ≤ 75 °C;

Soot particle size: a 600 mesh accounted for 85 . 45 %;. 325 mesh to +600 mesh accounted for 5 . 75 %; from 160 mesh to +325 mesh 1.1 %; +160 mesh 7.7 %;

Smoke source area: length × width = 1.6m × 1.05m .

feature:

The melting furnace has a high concentration of dust;

The smoke source is open, the temperature of the flue gas changes greatly, and a large amount of cold air is inhaled;

The dust particle size is small.

Through research and comparison, the scheme for the flue gas treatment of the melting furnace was determined , and the advanced high-efficiency buffer washing process was adopted to treat the flue gas of the melting furnace .

Washing scrubber principle:

The barrel type scrubber is a combination of the principle of using the buffer tower and the impact washer. The working principle is that the gas phase and the liquid phase collide with each other at a relatively high speed. The nozzle generates a large number of rotating liquid beads due to the liquid on the impact layer. The collision between the beads and the shearing force of the gas on the liquid bead, the original liquid bead is broken again, thereby increasing the mass transfer area and promoting the surface renewal of the bead; and the interface update due to the deformation, shearing force and surface tension of the bead And the inner circulation of the liquid bead; and the momentum inertia of the material, the substances in the gas phase that need to be adsorbed penetrate into the liquid phase by impact, and rapidly diffuse.

The gas phase energy and liquid phase energy are effectively utilized in the buffering process to prolong the contact time of the gas and liquid phases; the buffer zone contacts the gas with an extremely large and rapidly renewed liquid surface to complete efficient dust removal absorption and heat transfer. Mass transfer process.

  Flue gas treatment process:

Smoke coming from the melting furnace 75 deg.] C, dried air suction hood, flue punch into the turbulent efficient reverse jet scrubber tower through the nozzle washing process, the flue gas entering the spray tower from the top of the reverse, by the inverse of the spray tower and The circulating pump sends a washing liquid from the washing liquid in the buffer tank, and the flue gas is dedusted and cooled here, and is in countercurrent contact with the bottom-up washing liquid, and the gas and liquid momentum are relatively balanced to form a stable period. In the foam layer, after the gas and liquid are fully contacted, 90 % of the dust is removed, and the temperature of the flue gas is lowered to about 45 ° C. The flue gas after washing is separated from the gas in the liquid collecting tower, and the flue gas after washing is further From the flue to the secondary spray to purify and remove dust and defoam, the flue gas contains up to N-<50mg / Nm3 and is discharged by the chimney.

The process flow is summarized as follows:

Melting furnace smelting smoke - hood - flue gas conduit - a secondary spray purification dust - - Efficient demister - efflux efficiently passing a turbulent red scrubber scrubbers.

The technical reform of the flue gas dedusting system of the melting furnace adopts the domestic advanced high-efficiency buffer scrubber as the main equipment to purify the flue gas produced by the melting furnace , and fully combines the production status of the enterprise, and adds secondary spray to purify and remove dust and high-efficiency defoaming. Thereby achieving the effect of dust removal. This technology has the following characteristics:

1 system configuration process, compact equipment, tower trough integration, dust removal integrated design; has a small footprint, stable and reliable operation, low maintenance and operation costs. 2 Due to the use of buffer washing, it is a coarse spray washing, does not produce fine acid mist, which is good for improving the efficiency of the defoaming device; the supporting herringbone efficient deaerator effectively improves the operating environment of the equipment.

  Melting furnace flue gas dust removal system on January 17, 2012 were start trial run, during commissioning, flue gas resulting from the smelting furnace capable of melting all out. The following problems still exist during the test run:

(1) The dust removal efficiency of the system does not reach more than 90 %;

(2) the system is running, the system has serious problems running water, the red level turbulent scrubber reduced cylinder height of 10cm (about 200 kilograms of water per hour with a scrubber) per hour, resulting in the amount of mist vent fumes Large, bringing out a lot of dust.

In order to solve the problems in the debugging of the system, the system was optimized and modified: a high-level detonation device for human figures was added in the cylinder of the buffer washing tower and the secondary purification tower. After optimization, the dust removal rate is greatly improved, and the running water problem in the trial operation is solved. The dust removal efficiency detection situation is shown in Table 2 :

    Melting furnace practice effect

(1) The operating environment of the melting process of the melting furnace is improved , and all the flue gas generated in the melting process of the melting furnace can be completely extracted, which is greatly improved than the operating environment before the technical transformation, and the operating environment of the employees is obviously improved.

(2) It can be seen from Table 2 that the dust concentration of the flue gas at the outlet is up to the national standard and is superior to the national standard. The dust concentration of the flue gas at the outer discharge is reduced by 21.5mg / Nm , reaching the expected target of 50mg / Nm .

Because the flue gas of the melting furnace contains dust and the fluctuation range of impurities is relatively high, combined with the actual situation of the enterprise, the “bubble foam washing and high efficiency demisting purification technology is adopted to achieve the flue gas purification index. The results show that the dust concentration of the flue gas can be reduced to 21 after treatment. . 5 ~ 42.1mg / Nm3. the technology is simple equipment, easy operation, stable operation, significant economic benefits, etc., to provide technical support for corporate environmental, sustainability, governance of the industry has a more variety of kiln dust Good promotion and applicability.