US 11,292,718 B2Granted

Process for preparing sulfur from reduction of sulfate/ nitrate by iron-carbon and recovering desulfurization/ denitration agents

AssigneeShandong University

InventorsChunyuan Ma, Xiao Xia, Lin Cui, Liqiang Zhang, Xiqiang Zhao, Jun Li, Tai Feng, Shizhen Zhang

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Abstract

The present invention discloses a process for preparing sulfur from reduction of sulfate/nitrate by iron-carbon and recovering desulfurization/denitration agents. High-concentration SO2 flue gas produced by calcination of a sulfate and NOx produced by heating decomposition of a nitrate can be directly reduced to elemental sulfur vapor and N2 through reaction with an iron-carbon material at a high temperature. Then, after dust removal, cooling and fine dust removal, sulfur is recovered by a sulfur recovery device, and metal oxides can replace alkaline mineral resources such as limestone as raw materials of desulfurization (denitration) agents. This process can recycle the desulfurization and denitration agents.

Claims10

Dependent claims

A system for preparing sulfur from reduction of sulfate/nitrate by iron-carbon and recovering desulfurization/denitration agents, the system comprising:

a desulfurization tower, a denitration tower, a chimney, a drying device, a roaster for reduction, a first separator, a second separator, a thermal reduction tower using carbon, a third separator, a reheater, a fine dust removing device, a sulfur recovery device, a sulfur storage bin, a concentration device, a pneumatic transporting device, and a nitrate decomposition tower,
wherein a flue gas inlet of the desulfurization tower is connected to a flue gas supply source, a flue gas outlet of the desulfurization tower is connected to a flue gas inlet of the denitration tower, a flue gas outlet of the denitration tower is connected to an inlet of a wet electrostatic precipitator, and an outlet of the wet electrostatic precipitator is connected to an inlet of the chimney;
a tower kettle of the desulfurization tower is connected to an inlet of the drying device, an outlet of the drying device is connected to an inlet of a sulfate bin, the sulfate bin is connected to the roaster for reduction, and the roaster for reduction is also connected to an iron powder supply source and a carbon powder supply source;
a tower kettle of the denitration tower is connected to an inlet of the concentration device, an outlet of the concentration device is connected to an inlet of the nitrate decomposition tower through the pneumatic transporting device, and an outlet of the nitrate decomposition tower is connected to an inlet of the thermal reduction tower using carbon;
an outlet of the roaster for reduction is connected to the first separator, a solid outlet of the first separator is in communication with an interior of the roaster for reduction, a gas outlet of the first separator is connected to an inlet of the second separator, and a solid outlet of the second separator is connected to a filtering device;
a gas outlet of the second separator is connected to the inlet of the thermal reduction tower using carbon, an outlet of the thermal reduction tower using carbon is connected to an inlet of the third separator, a gas outlet of the third separator is connected to the reheater, and the reheater, the fine dust removing device, the sulfur recovery device and the sulfur storage bin are connected in sequence;
and
a solid outlet of the third separator is connected to the thermal reduction tower using carbon.

5 more elements

A process for preparing sulfur from reduction of sulfate/nitrate by iron-carbon and recovering desulfurization/denitration agents, comprising:

subjecting a flue gas to dust removal, ozone oxidation, alkali washing desulfurization, and alkali washing denitration, and then discharging;
drying a sulfate precipitate produced in the alkali washing desulfurization and then transporting the dried sulfate precipitate together with carbon powder and iron powder at a set ratio to a roaster for reduction and conducting roasting reduction at a roasting temperature of 800° C. to 1100° C. for a roasting time of 4 to 200 s;
concentrating and crystallizing a nitrate solution produced in the alkali washing denitration to produce a nitrate powder, decomposing the nitrate powder at a high temperature into a solid metal oxide and a mixed gas, and delivering the mixed gas to the roaster for reduction such that the mixed gas is reduced to nitrogen by roasting;
separating an unroasted sulfate carried in the gas flowing out from an outlet of the roaster for reduction by a first separator, and then returning the separated unroasted sulfate to the roaster for reduction for further reaction;
separating a metal oxide and carbon powder in a gas flow from the first separator by a second separator and feeding into a filtering device, wherein the metal oxide is dissolved in water of the filtering device to form an alkali liquid, and the carbon powder is intercepted by the filtering device and dried for reuse;
subjecting remaining gas from the roaster for reduction to a dust removal by condensing and to a sulfur recovery, and then sequentially introducing the remaining gas back into the alkali washing desulfurization and the alkali washing denitration for treatment, and finally discharging.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 16/618,937Filed 27 Dec 2018
Priority: CN 201811542403.317 Dec 2018
Published: US 2021/0331922 A128 Oct 2021
Granted: 5 Apr 2022
Term ends: Not estimatedThe source records don’t support an estimate.

Classification25 codes

C01B 17/05
From gaseous sulfur compounds including gaseous sulfides: by wet processes
B01D 1/28
Evaporating: with vapour compression
B01D 39/12
Filter screens essentially made of metal: of wire gauze; of knitted wire; of expanded metal
B01D 39/2068
Of inorganic material, e.g. asbestos paper, metallic filtering material of non-woven wires: other inorganic materials, e.g. ceramics