CN1883771A

CN1883771A - Process for removing oxide containing carbon and the others from coal-burning boiler flue gas and preparing compound fertilizer and device therefor

Info

Publication number: CN1883771A
Application number: CNA2006100109211A
Authority: CN
Inventors: 张光太; 张严匀
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-05-26
Filing date: 2006-05-26
Publication date: 2006-12-27
Anticipated expiration: 2026-05-26
Also published as: CN100363090C

Abstract

The invention relates to a one-step production process for removing CO, NO, and SO2 in fuel coal flue gas and directly preparing composite fertilizer and device therefore, wherein, oxysulfide, nitric oxide, and oxycarbide in flue gas can be simultaneously removed efficiently. The process is characterized in that oxidation reaction zone, replacement reaction zone, and neutralization reaction zone are arranged in contact precedence order of flue gas in flue gas passage of fuel coal boiler; and the device is characterized in that oxidant liquid sprinkling zone, decomposition material liquid sprinkling zone, and alkali material liquid sprinkling zone are arranged in the flow direction of flue gas between the flue gas outlet and flue gas inlet in flue gas passage of fuel coal boiler, wherein each sprinkling zone has material liquid feeding pipe and sprinkling head which communicates with the feeding pipe.

Description

Process and equipment for preparing compound fertilizer and oxides by decarbonizingsmoke of coal-fired boiler

Technical Field

The invention relates to a process for removing carbon, nitrogen, sulfur and other oxides in coal-fired boiler flue gas, in particular to a process for removing CO, NO and SO from coal-fired flue gas₂And directly prepare the compound fertilizer.

Background

Coal burningRemoving sulfur, nitrogen and other oxides (such as SO) from flue gas₂NOx) are reported, and related production facilities are also disclosed. Some processes and equipment are to SO₂The removal rate can reach more than 90 percent, and the technology capable of simultaneously removing NOx is mature day by day. However, in the production process, the flue gas of the coal-fired boiler can be effectively removed of CO while the flue gas is subjected to sulfur, nitrogen and other oxides removal treatment, and the process research of enabling the oxygen content of the exhaust gas treated by the removal process to be similar to the atmosphere has not been substantially developed, not to mention the production process and equipment for forming. The emission of CO in the flue gas of coal-fired boilers in the global range is one of the main reasons for damaging the atmospheric ozone layer and causing the ozone layer to be hollow. Therefore, under the condition that the flue gas purification process and equipment for removing sulfur, nitrogen and other oxides in the flue gas of the coal-fired boiler tend to be perfect, the development of the process capable of effectively removing CO in the flue gas at the same time is added in the corresponding production process, and the design realization of matched equipment is proposed to be an outstanding position.

Disclosure of Invention

The invention aims to disclose a process and a device for preparing oxides such as decarbonization of coal-fired boiler flue gas and compound fertilizer.

The process is characterized in that three reaction zones of oxidation, double decomposition and neutralization are respectively arranged in a flue gas flow passage of the coal-fired boiler according to the sequence of flue gas contact, in the process of removing oxides from the entering flue gas, the flue gas is firstly oxidized with an oxidant in the oxidation reaction zone, then double decomposition reaction is carried out on a double decomposition reaction agent in the double decomposition reaction zone and gas from the oxidation reaction zone, and finally a neutralizing agent in the neutralization reaction zone and the gas from the double decomposition reaction zone are subjected to neutralization reaction;

the equipment for implementing said invented process is equipped with flue gas inlet and gas outlet, and is characterized by that the equipment is positioned in the flue gas flow channel of coal-fired boiler, and the flue gas of coal-fired boiler can be flowed into tail section of flue gas flow channel only by means of internal cavity of the equipment, the described flue gas inlet is faced with flue gas incoming flow direction, and the gas outlet is communicated with tail section of gas flow channel, and between the flue gas inlet and gas outlet in the equipment an oxidant material liquid spraying zone, decomposed material liquid spraying zone and alkaline material liquid spraying zone are arranged along the flue gas flow direction, and in every spraying zone a material liquid feeding pipe and a fog spraying head communicated with them are set, and the lower portions of decomposed material liquid spraying zone and alkaline material liquid spraying zone are respectively equipped.

By adopting the process and the equipment of the invention, when the flue gas flow of the coal-fired boiler passes through the oxidation reaction zone, the flue gas flow reacts with the oxidant liquid sprayed out of the oxidation reaction zone, SO that the flue gas flow passes through the oxidation reaction zone and contains SO₂The flue gas of 'acid radical' ions such as NOx and COx is firstly reacted and 'acidified' into sulfuric acid, nitric acid or carbonic acid gas. The 'acidified' gas containing carbonate ions after oxidation enters a double decomposition reaction zone and carries out double decomposition reaction with decomposed feed liquid sprayed from a spray head of the double decomposition reaction zone, in the double decomposition reaction zone, sulfuric acid and nitric acid gases containing sulfuric acid or nitrate ions generate precipitated compound fertilizer under the action of the decomposed feed liquid, and the gas passing through the double decomposition reaction zone does not contain SO₂And NO acid radical ions, the gas entering the neutralization reaction zone will be SO-free₂And NOx ions. In the process, the fog shower head of the neutralization reaction zone sprays alkaline feed liquid, then the alkaline feed liquid makes the carbonic acid gas entering the neutralization reaction zone generate neutralization reaction with the alkaline feed liquid, and precipitates to generate the compound fertilizer containing the carbonic acid ions, and the alkaline feed liquid and the carbonic acid gas react quite thoroughly, namely the arrangement of the neutralization reaction zone and the spraying of the alkaline feed liquid can remove the carbon oxides in the coal-fired flue gas to a considerable degree, and the double decomposition reaction can react with SO in the sulfuric acid and the nitric acid gas₂Good removal effect of NOx acid radical ions, SO that the disclosed process and equipment can effectively remove SO₂And the COx carbonate ions in the flue gas of the coal-fired boiler can be well removed while the NOx carbonate ions are removed. Feed lines to the feed liquid in the "metathesis reaction zone" and the "neutralization reaction zone" are divided intoThe corresponding reaction liquid is provided, so that the double decomposition reaction and the neutralization reaction can directly precipitate the compound fertilizer or the production raw material thereof, and the compound fertilizer or the by-product thereof with good economic value in the form of the production raw material can be directly produced by adopting the disclosed process and equipment.

Drawings

FIG. 1 is a process flow diagram of the present invention.

FIG. 2 is a schematic diagram of the apparatus of the present invention.

In the figure: 1-coal-fired boiler flue gas inlet channel, 2-equipment shell, 2-1-flue gas inlet port, 2-2-gas outlet port, 3-oxidant liquid spraying (oxidation reaction) zone, 4-decomposition liquid spraying (double decomposition reaction) zone, 4-1-double decomposition reaction zone discharge port, 5-alkaline liquid spraying (neutralization reaction) zone, 5-1-neutralization reaction zone discharge port, 6-liquid feed pipe, 6-1-spray shower head and 7-gas flow channel tail section.

Detailed Description

The process and apparatus of the present invention will be further described with reference to the accompanying drawings.

FIG. 1 shows a process flow of the present invention; as shown in fig. 2, the material liquid supply pipes (6) respectively located in the "oxidant", "decomposition" and "alkaline" material liquid spraying zones, that is, the "oxidation reaction zone", the "double decomposition reaction zone" and the "neutralization reaction zone" are all annular rectangles, the spray heads (6-1) communicated with the material liquid supply pipes (6) are arranged along the sides of the rectangles, and a plurality of annular rectangular material liquid supply pipes (6) are arranged from top to bottom in each material liquid spraying (reaction) zone to form a material liquid supply pipe (6) row. These feed liquid feed pipes (6) arranged from top to bottom in the respective reaction zones are arranged in the apparatus so as to be in communication with it for receiving and supplyingThe (a plurality of) spray showering heads (6-1) are provided with a feed pipeline for reaction liquid. The flue gas from a flue gas inlet channel (1) of a coal-fired boiler entering the equipment through a flue gas inlet (2-1) is subjected to SO by the given process and equipment₂When the 'acid radical' ions such as NOx and COx are removed, different sprays and inversions are neededThe corresponding reaction feed liquid is provided by the feed liquid feed pipe (6) in the reaction zone, namely the fog shower head (6-1) positioned in the oxidation reaction zone sprays the oxidant feed liquid, the fog shower head (6-1) positioned in the double decomposition reaction zone sprays the decomposition feed liquid, and the fog shower head (6-1) positioned in the neutralization reaction zone sprays the alkaline feed liquid. In the process of removing harmful flue gas, sulfuric acid, nitric acid and carbonic acid gases generated by acidification under the action of oxidant liquid sprayed by the spray head (6-1) in the oxidation reaction zone are decomposed to precipitate a compound fertilizer containing sulfuric acid and nitrate and neutralized to precipitate a compound fertilizer containing carbonate or a production raw material thereof under the action of decomposed liquid sprayed by the spray head (6-1) in the double decomposition reaction zone and alkaline liquid sprayed by the spray head (6-1) in the neutralization reaction zone respectively. Such as spraying powdered rock phosphate Ca in the double decomposition reaction area₃(PO₄) The reaction chemical formula of the feed liquid, sulfuric acid 2HSO4 and nitric acid HNO gas is as follows:

and: (ii) a The result is calcium superphosphate and calcium sulfate or calcium nitrate precipitate, and it is the double decomposition reaction that makes sulfur and nitrogen oxides in the flue gas of the original coal-fired boiler precipitate into calcium sulfate or calcium nitrate and no longer diffuse into the atmosphere in the form of harmful gas. Such as ammonia NH₃For neutralizing the feed liquid, it is reacted with carbonic acid H in a neutralization reaction zone₂CO₃The chemical reaction formula of the gas is:

and the carbon oxides in the flue gas of the original coal-fired boiler are precipitated into compound fertilizer ammonium bicarbonate through neutralization reaction, and the carbon oxides in the flue gas can not be diffused into the atmosphere in the form of harmful gas, namely the gas finally discharged from the tail section (7) of the gas flow channel through the gas outlet (2-2) of the equipment is the gas which does not contain acid radical ion components such as sulfur, nitrogen, carbon oxides and the like.

The lower part of a decomposition material liquid spraying area (4) of the equipment is provided with a double decomposition reaction discharge port (4-1), the lower part of an alkaline material liquid spraying area (5) is provided with a neutralization reaction discharge port (5-1), and the double decomposition reaction area and the neutralization reaction area can correspondingly react to precipitate a (semifluid) compound fertilizer or a production raw material thereof to be automatically discharged out of the equipment in time.

Claims

1. A process and equipment for preparing oxides and compound fertilizer by decarbonizing smoke of coal-fired boiler are characterized in that:

1) the process comprises the steps that three reaction zones of oxidation, double decomposition and neutralization are respectively arranged in a flue gas flow passage of the coal-fired boiler according to the sequence of flue gas contact, in the process of removing oxides from the entering flue gas, the flue gas is firstly subjected to oxidation reaction with an oxidant in the oxidation reaction zone, then a double decomposition reaction agent in the double decomposition reaction zone is subjected to double decomposition reaction with gas from the oxidation reaction zone, and finally a neutralizing agent in the neutralization reaction zone is subjected to neutralization reaction with the gas from the double decomposition reaction zone;

2) the equipment for implementing the process of the invention is provided with a flue gas inlet (2-1) and a gas outlet (2-2), the equipment is positioned in a flue gas flow channel of a coal-fired boiler, the flue gas inlet (2-1) faces to the direction of flue gas incoming flow, the gas outlet (2-2) is communicated with the tail section (7) of the flow channel, an oxidant liquid spray area (3), a decomposed liquid spray area (4) and an alkaline liquid spray area (5) are arranged between the flue gas inlet (2-1) and the gas outlet (2-2) in the equipment along the direction of flue gas flow, a liquid feed pipe (6) and a spray head (6-1) communicated with the liquid feed pipe are arranged in each spray area, and the lower parts of the decomposed liquid spray area (4) and the alkaline liquid spray area (5) are respectively provided with a discharge port leading to the outside of the.

2. A process and apparatus as claimed in, characterized in that the feed liquid feed pipes (6) in each spraying zone of the apparatus are circular rectangles, the spray headers (6-1) communicating with the feed liquid feed pipes (6) are arranged along the sides of the rectangles, and a plurality of circular rectangles of feed liquid feed pipes (6) in each spraying zone are arranged from top to bottom to form a row of feed liquid feed pipes (6).

3. A process and an apparatus as claimed in claim, characterized in that the apparatus has a metathesis reaction outlet (4-1) at the lower part of the decomposition feed liquid spray zone (4) and a neutralization reaction outlet (5-1) at the lower part of the basic feed liquid spray zone (5).