Vertical kiln and technique for preparing phosphoric acid by vertical kiln method

Abstract

A vertical kiln comprises a kiln body, a heat exchange tube, an air guide tube and a material guide plate, wherein the kiln body is divided from the top down into an oxidation section, a feeding section, a reduction section and a slag storing section in turn; the heat exchange tube is positioned in the oxidation tube, and a plurality of material guide plates are mounted in the reduction section, and the upper end of the air guide tube is connected with the heat exchange tube and the lower end thereof passes through the feeding section and the material guide plates in the reduction section to extend into the slag storage section. A technique for preparing phosphoric acid by vertical kiln method is realized by the vertical kiln and the assorted devices; in the reduction section of the vertical kiln, the raw materials move downwards along the material guide plates, and gas phosphorus and CO produced in the reduction reaction of phosphorite in the reduction section of the vertical kiln flow upward to go into the oxidation section of the vertical kiln to mix and oxidize with air containing oxygen to generate P2O5 and CO2 which are pumped outside from the outlet of the kiln and sent to aphosphorous absorbing device after being purified, and in the phosphorous absorbing device P2O5 is absorbed by water to generate phosphoric acid, and gas exhausted from the phosphorous absorbing device is removed with fog and sent to the heat exchange tube in the oxidation section of the vertical kiln section, so the heat generated by the oxidation reaction is absorbed.

Description

Shaft kiln and the technology of legal production of phosphoric acid in shaft kiln technical field The invention belongs to the field of kiln-process phosphoric acid, and relates to a kiln for producing phosphoric acid and a process for producing phosphoric acid in a kiln process. Background technique Phosphoric acid produced by kiln method can use medium and low-grade phosphate rock to produce high-quality phosphoric acid, which is in line with the characteristics of phosphate rock resources in my country, and can reduce the dependence of phosphoric acid production on sulfur and electricity. The difficulty of the kiln phosphoric acid process is how to effectively isolate the oxidation zone and the reduction zone in the same kiln. To solve this problem, the structure of the kiln is very important. The kilns used in the existing kiln-based phosphoric acid production process mainly include rotary kilns, tunnel kilns, tunnel kilns and ring-bottom kilns. Practice has shown t...

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Problems solved by technology

The kilns used in the existing kiln-based phosphoric acid production process mainly include rotary kilns, tunnel kilns, tunnel kilns and ring-bottom kilns. Practice has shown that none of them effectively isolates the oxidation zone and the reduction zone, and has the following shortcomings: The rotary kiln does not consider the separation of the redox area, and the reduced carbon in the material is easily oxidized to cause early combustion, so the carbon consumption is large, and at the same time affects the reduction of phosphorus; in addition, the ring formation phenomenon in the rotary kiln is serious, which affects the normal operation of the kiln. Difficult to realize industrial production

The shaft kiln with this structure not only has a relatively complex structure, but also has poor heat transfer effect, low heat utilization rate, and the outlet of the reduction chamber is easily blocked.

The inventor of the above patent also invented a combined rectification compound vertical kiln with the patent number ZL200720105028.7. In the upper part of the kiln, the lower part of the kiln is the cooling and slag discharge section. Although the vertical kiln with this structure can improve the heat transfer effect theoretically, it makes the structure of the vertical kiln more complicated, and it is more likely to cause blockage of materials in the kiln, which is difficult Adapt to the needs of industrial production

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