CN111992016A

CN111992016A - Biomass boiler denitration system

Info

Publication number: CN111992016A
Application number: CN202010758178.8A
Authority: CN
Inventors: 吕薇; 李雪松; 陶立
Original assignee: Harbin University of Science and Technology
Current assignee: Harbin University of Science and Technology
Priority date: 2020-07-31
Filing date: 2020-07-31
Publication date: 2020-11-27

Abstract

The invention relates to a novel integrated system for flue gas desulfurization and denitration of a biomass boiler. Specifically, the flue gas desulfurization and denitrification reaction part of the system comprises a reactor, a blower, a water tank, a water feeding pump and a quick lime storage tank which are connected in parallel; the circulating operation of the system depends on the monitoring of a Ca (OH)2 concentration meter, a water flow meter, an air flow meter, a thermometer and a NOx concentration meter in the reactor to set a proper alternate operation period, and the reactor which is suspended from operation after the completion period separates, recycles and reuses substances after reaction through a solid-liquid separation device, so that the operation life of a unit is prolonged, and the economic cost is reduced. The system is supplemented with a waste heat recovery device, so that the heat of the purified low-temperature flue gas is further utilized to improve the economic benefit of the equipment, and a good reference is provided for the research and application of the environment-friendly and efficient biomass boiler flue gas purification treatment equipment.

Description

Biomass boiler denitration system

Technical Field

The invention relates to a novel desulfurization and denitrification system of a biomass boiler.

Background

Now that the utilization of biomass energy has become a research hotspot, heat utilization equipment such as biomass boilers and biomass gasification furnaces is increasingly popularized, and fuels of the biomass energy are mainly agricultural and forestry wastes (such as straws, sawdust, bagasse, rice chaff and the like) and are mainly different from fossil fuels. The biomass fuel is directly combusted, a large amount of harmful flue gas is inevitably generated, the sulfur oxide and the nitrogen oxide containing equivalent components pollute the atmospheric environment, the desulfurization and denitrification treatment of the boiler flue gas is significant from the viewpoint of environmental protection, and the flue gas desulfurization and denitrification treatment of the biomass boiler by adopting a new idea is just produced.

The desulfurization and denitrification of boiler flue gas cause the emission of nitrogen oxides NOx and sulfur oxides SOx to be unsatisfactory due to the limitation of low-nitrogen combustion technology in the boiler, and in order to further reduce the emission of the nitrogen oxides NOx and the sulfur oxides SOx, the flue gas after combustion must be subjected to desulfurization and denitrification treatment. The nitrogen oxides in the flue gas are often difficult to be directly dissolved in water and cannot be effectively absorbed and removed in the wet desulphurization link, so that a higher-level technology is required for ideal denitration treatment. SOx in flue gases is substantially acidic and can be removed from flue gases by reaction with suitable alkaline substances. The most commonly used alkaline materials for flue gas removal are limestone (calcium carbonate), quicklime (calcium oxide) and slaked lime (calcium hydroxide). The reaction between SOx and the alkaline substance takes place either in an alkaline solution (wet flue gas desulfurization technique) or on a wet surface of a solid alkaline substance (dry or semi-dry flue gas desulfurization technique). The flue gas denitration belongs to one of denitration modes after combustion, and the mainstream technology at present mainly comprises a selective catalytic reduction denitration (SCR) technology, a selective non-catalytic reduction denitration (SNCR) technology, an SNCR/SCR combined flue gas denitration technology developed on the basis of the selective catalytic reduction denitration (SCR) technology and the SNCR/SCR combined flue gas denitration technology, and also comprises an activated carbon adsorption treatment mode and the like. The SCR technology depends on expensive catalysts, so that the denitration efficiency is high but difficult to be widely applied, the SNCR is economical, but the denitration efficiency is greatly reduced, and the increasingly strict environmental protection requirement of industrial equipment cannot be met.

The invention selects Ca (OH)2 as a desulfurization and denitrification reactant, adopts quicklime as a raw material, is a common industrial product and has very wide application. It is an alkaline oxide, readily soluble in water to react with NOx and SOx, but its aqueous solution is strongly alkaline and corrosive. Therefore, the reactivity is particularly problematic in a high-temperature environment or after the concentration is increased.

Disclosure of Invention

The invention aims to provide a novel desulfurization and denitrification integrated system aiming at the defects of the prior art, and realize high-efficiency flue gas desulfurization and denitrification through a novel reaction device structure. The invention also limits some special conditions of CaO as a desulfurization and denitrification reactant.

The technical problem of the invention is mainly realized by the following technical scheme:

the utility model provides a biomass boiler SOx/NOx control system, contain the parallel reactor that two purpose-made carbon steel that has SiO2 glass fiber coating made, install temperature monitoring device additional in this reactor, Ca (OH)2 concentration monitoring device and NOx monitoring device, the one end of parallel reactor group is connected with a biomass boiler, the waste heat recovery device who installs temperature monitoring device additional is connected to the parallel reactor group other end, a dust collector is connected to waste heat recovery device, a chimney is connected behind the dust collector. The upper ends of the reactor 1 and the reactor 2 are connected with a water tank, a CaO (quick lime) storage device and an air blower, flow meters are additionally arranged on connecting pipelines of the water tank and the air blower and the reactor, the other end of the water tank is connected with a water feeding pump, the lower end of the reactor is connected with a solid-liquid separation and collection device which is provided with a horizontally movable reticular hollowed baffle plate with a SiO2 glass fiber coating at the middle position, the lower end of the solid-liquid separation and collection device is respectively connected with a liquid separation device and a solid separation device, the solid separation device is connected with two separation boxes, and the liquid separation device is connected with the CaO separation box therein.

Drawings

In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings used in the description of the present invention or the prior art will be briefly introduced, and it is understood that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other related structural drawings without creative efforts.

The biomass boiler has the advantages that the biomass boiler is provided with the throttling valves La and Lb, the desulfurization and denitrification reaction unit connected in parallel (the reactor 1 is arranged at the upper part, the reactor 2 is arranged at the lower part), the water flowmeter is provided with the water pump blower, the gas flowmeter is provided with the self-absorption SOx/NOx concentration monitor and the self-absorption Ca (OH)2 concentration meter, the solid-liquid separator is selected from the self-absorption Ca (NO3)2 collecting box, the CaO collecting box ⒄ CaSO3 collecting box and the waste heat recovery device ⒆ dust removal device ⒇ chimney 25

Detailed Description

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more readily understood by those skilled in the art, and the scope of the present invention will be clearly and clearly defined.

As shown in the figure, a biomass boiler desulfurization and denitrification system, contains two purpose-made parallel reactor groups three that have the carbon steel of SiO2 glass fiber coating and make, install thermometer device, Ca (OH)2 concentration monitoring device in this reactor additional has, parallel reactor group three one end and a biomass boiler flue are connected, parallel reactor group other end is connected one and is installed the waste heat recovery device that temperature monitoring device and NOx monitoring device were maked together and the waste heat recovery device that the NOx monitoring device was a dust collector ⒆ is connected in addition, connect a chimney ⒇ behind dust collector ⒆. The reactor 1 and the reactor 2 are connected with a water tank, a CaO (quicklime) storage device and a blower at the upper end, a water flowmeter and a gas flowmeter are additionally arranged on connecting pipelines of the water tank and the blower and the reactor, the other end of the water tank is connected with a water-feeding pump, the lower end of the reactor is connected with a solid-liquid separation and collection device which is provided with a horizontally movable mesh-shaped hollow baffle plate with a SiO2 glass fiber coating at the middle position, the lower end of the solid-liquid separation and collection device is respectively connected with a liquid separation device and a solid separation device, the solid separation device is connected with a CaSO3 separation box ⒄ and a CaO separation box, and one end of the liquid separation device is connected with a Ca (NO3)2 collection box and the other end of the liquid separation device is connected with the CaO separation box of the solid separation device.

The high-temperature flue gas generated by combustion of the biomass boiler is received, the flue gas pipeline is a bidirectional pipeline and is respectively connected with a reactor, a valve La passage is opened firstly during operation, the flue gas flows to the reactor 1 for desulfurization and denitration, the valve La is closed after one period is finished, the valve Lb is opened, and the flue gas flows to the reactor 2, so that desulfurization and denitration are alternately performed. After the low-temperature flue gas subjected to desulfurization and denitrification is subjected to waste heat recovery, the temperature is reduced to 120-150 ℃, and the low-temperature flue gas is filtered by a cloth bag dust removal and electrostatic dust removal device to remove inhalable particulate impurities and then can be discharged into the atmosphere through a chimney.

In the reactor, when the flue gas reacts with enough Ca (OH)2 solution, certain oxygen is needed to participate, the original oxygen in the flue gas is not enough, and a proper amount of air needs to be blown by a blower to promote the forward progress of the reaction. The reactions that mainly occur in the reactor are:

CaO+H2O→Ca(OH)2

NO+NO2+O2+Ca(OH)2→Ca(NO3)2+H2O

SO2+Ca(OH)2→CaS03+H20

CO2+Ca(OH)2→CaC03+H20

with the progress of the reaction, Ca (OH)2 is continuously consumed, which causes the reduction of reaction strength to cause incomplete desulfurization and denitrification, the concentration of Ca (OH)2 needs to be ensured, a thermometer in the reactor is used for monitoring the reaction temperature, and when the temperature is too high, the temperature is matched with a water tank to supply water to stabilize the reaction temperature; when the Ca (OH)2 concentration monitoring device monitors that the reaction reaches a period (the concentration of Ca (OH)2 is lower than a half of the original concentration), the reactor unit is required to alternately operate, the reactor which stops working is required to be timely supplemented to a proper Ca (OH)2 concentration state through feeding of water and quick lime, in the process of desulfurization and denitrification, gas is introduced from the solution end at the lower end and flows out from the gas end at the upper end, and the gas is required to be monitored by a pressure gauge to ensure that the gas has enough pressure so as to prevent backflow and suck-back from occurring. The reaction product and the residual Ca (OH)2 solution flow into a collecting device together, a reticular hollow baffle plate in the collecting device separates solid from liquid, the separated solid is conveyed into a solid separating device by horizontal movement, and the liquid flows into a liquid separating device. The solids separation unit is mainly solid CaS03 and CaC03, and the liquid separation unit is mainly Ca (OH)2 and Ca (NO3)2 solution. After sufficient CO2 was fed to the liquid separation unit, since Ca (NO3)2 was not readily reacted with CO2, the Ca (OH)2 solution was reacted with CO2 to produce CaCO3, and after the resulting CaCO3 was separated from the Ca (NO3)2 solution by a sieve, CaCO3 was fed to the solid separation unit. Two solids in the solid separation device are heated at low temperature due to different temperatures required by thermal decomposition (CaCO3 is easier to pyrolyze), dried CaS03 and CaO solids are obtained for recovery, the recovered CaO is supplemented into a CaO storage device connected with the reactor for recycling, and CaS03 is used as a byproduct for centralized treatment.

The above description is only exemplary of the present invention and should not be taken as limiting the invention, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The utility model provides a novel living beings SOx/NOx control system, inside SOx/NOx control unit who is arranged side by two reactors that is provided with of its characterized in that reaction system, the one end of parallel reactor group is connected with a biomass boiler, the other end of parallel reactor group is connected one and is installed temperature monitoring device's waste heat recovery device additional, a dust collector is connected to waste heat recovery device, a chimney is connected behind the dust collector, a water tank is connected to every reactor upper end, CaO (quick lime) storage device and an air-blower, a water-feeding pump is connected to the water tank other end, a solid-liquid separation collection device is connected to the reactor lower extreme, a liquid separator and a solid-liquid separation device are connected respectively to the solid-liquid separation device, two separator are connected to the solid-liquid separation device, the liquid separator is connected.

2. The reactor of claim 1 having a SiO2 glass fiber coating on the interior and made of carbon steel, and further comprising temperature monitoring means, ca (oh)2 concentration monitoring means, and NOx monitoring means.

3. The process according to claim 1, wherein the flow meter is additionally installed on the connecting pipeline of the water tank connected with the reactor and the blower connected with the reactor, and the mesh-shaped hollowed-out baffle plate which can horizontally move and is provided with the SiO2 glass fiber coating is arranged in the middle of the separation and collection device connected with the lower end of the reactor.