CN1419952A

CN1419952A - Double alkali wet desulfurizing dust-removing system

Info

Publication number: CN1419952A
Application number: CN 01130426
Authority: CN
Inventors: 陈鸣楼
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-11-15
Filing date: 2001-11-15
Publication date: 2003-05-28

Abstract

A dual-alkali wet desulfurizing-dusting system for the SO2-containing waste gas exhausted by fuel combustion and industrial production is composed of smoke inlet tube, Venturi tube, drop-capturing separator, fume outlet tube, draught fan, chimney and dual-alkali wet-method water circulation system. Its advantages are high efficiency, no scaling, no blocking, no dust deposit and low cost.

Description

Double-alkali wet desulphurization and dust removal system

The equipment belongs to environment-friendly equipment. In particular to the treatment of SO-containing emissions from fuel combustion and industrial processes₂A set of system equipment for waste gas.

At present, many flue gas desulfurization and dust removal methods are researched by various countries, and at least the methods are less than five hundred. Some of them are subjected to intermediate tests, and some of them are still in the laboratory research stage, and only more than two and thirty varieties can be really applied to industrial production.

The currently applied methods for removing sulfur and dust from flue gas can be roughly divided into two categories, namely dry-method desulfurization and dust removal and wet-method desulfurization and dust removal.

Dry desulfurization and dust removal: the desulfurization is carried out by removing SO from the exhaust gas with powdery or granular absorbent, adsorbent or catalyst₂(ii) a And the dust removal is mostly finished by a bag type, a multi-pipe or an electrostatic dust collector. The dry desulfurization and dust removal method has the greatest advantages that no waste water and waste acid are discharged during treatment, and secondary pollution is reduced; the disadvantages are low desulfurization efficiency, large equipment and high operation requirement.

Wet desulfurization and dust removal: the desulfurization is carried out by washing SO-containing gas with a liquid absorbent such as water or an aqueous alkali₂By absorbing SO from the flue gas₂Meanwhile, the washing liquid has the function of dust removal, namely, desulfurization and dust removal are carried out synchronously. The wet desulfurization and dust removal method has the advantages of simpler equipment, easy operation and higher desulfurization efficiency. The disadvantages are that the flue gas temperature after desulfurization is lower, and the flue gas is not easy to diffuse in a chimney; on the other hand, the most difficult point to overcome by wet desulphurization and dust removal is that the system is easy to scale, which causes the blockage of absorption equipment.

The desulfurization and dust removal system has the advantages that the desulfurization and dust removal efficiency is high, the equipment occupies a relatively moderate area, the operation requirement is simpler, the temperature drop is not necessarily large, the equipment is not scaled and blocked, and the moisture content of the discharged smoke meets the requirement of a draught fan. After continuous research and research, the invention finally discloses a double-alkali wet desulphurization and dust removal system. The system device well solves the various defects and difficulties described above.

The double alkali wet desulphurization and dust removal system mainly comprises a smoke inlet pipe, a Venturi tube, a drop-catching separator (internally provided with a spiral cyclone device), a smoke outlet pipe, a draught fan, a chimney, a double alkali wet circulating water system and the like. After the dust-containing gas enters the double-alkali wet desulphurization and dust removal equipment from the smoke inlet pipe, when the airflow passes through the Venturi tube at a high speed, the smoke meets the atomized liquid containing alkaline substances, and the gas, the liquid and the solid are in mutual collision contact and are fully mixed. The small droplets trap the small dust particles and agglomerate into large particles to form dust droplets. The mixed flue gas flow is thrown into a spiral cyclone device and a multi-stage mixing separator along the direction of a spiral line and flows along the cycloneThe plate spirals up between the centrifuge columns. At the moment, a water film body formed in the overflow device descends along a gap line from the inner wall of the drop catching separator, the mixed flue gas flow and the water film body form convection, dust particles and sewage drops are separated outwards under the action of inertia force, gravity and centrifugal force, the ash water drops are thrown into a gap of a rotational flow plate along with the flow direction when encountering a water film and are intercepted and caught, and the ash water drops are settled to a water seal and discharged. Thereby achieving the purposes of gas-liquid separation and further dust removal. In the above process, the absorption of SO is accompanied by the absorption of alkali liquor₂The reaction process of (1). The purified flue gas is led to a chimney through a draught fan to be discharged, and the flue gas is purifiedThe sewage containing the sediment is recycled after being treated by a double-alkali water circulation system.

Absorption of SO by the lye as described above₂The reaction process of (2) is a sodium-alkali double-alkali absorption desulfurization process. The principle of the process is roughly divided into two major parts, absorption reaction and regeneration reaction. For the sake of illustration, the following description will be made with Na alone₂CO₃The desulfurization part of the double-alkali wet desulfurization dust removal system is illustrated as an example of the initial absorbent, and the concrete steps are as follows:

by using Na₂CO₃Desulfurization reaction of sodium alkali method as initial absorbent in reaction with SO₂During the contact of the gases, the following chemical reactions occur approximately:

A. absorption reaction

(1)

(2)

(3)

At the beginning of absorption, Na is formed mainly according to the above three reactions₂SO₃，Na₂SO₃Has the function of absorbing SO₂Ability to continue to absorb SO from the gas₂：

(4)

NaHSO₃No longer has the functionof absorbing SO₂Thus (4) is the main absorption reaction, while the actual absorbent is Na₂SO₃. In the process, sodium alkali is used as the absorption liquid, so that no precipitate is generated in an absorption system.

The main side reactions of the absorption process are oxidation reactions:

(5)

from the above reaction, it is found that Na is the main component in the circulating absorbent₂SO₃、NaHSO₃And a small amount of Na₂SO₄。

B. Regeneration reaction

Regenerating the absorption liquid by using lime slurry:

(6)

(7)

(8)

as can be readily seen from the above analysis, the initial absorbent for desulfurization, despite the use of the relatively expensive Na₂CO₃However, the whole system adopts a double alkali method process, so that cheap CaO is added in the subsequent fixation of sulfur. The addition of CaO not only plays a role in sulfur fixation, but also plays a role in Na₂CO₃It also has regeneration effect. Therefore, the medicament mainly consumed in the practical application is CaO, namely the lime, which is cheap and easy to obtain. This greatly reduces the operating cost of the system, i.e. improves the utility of the system.

The present invention will be described in more detail with reference to the accompanying drawings and the following detailed description.

The figure is a systematic process flow diagram of one embodiment of the invention.

As shown in the attached drawing, the double-alkali wet desulphurization and dust removal system comprises a smoke inlet pipe 3, a water inlet pipeline 4, a Venturi tube 6, a drop catching separator 9, a smoke outlet pipe 10, an induced draft fan 11, a chimney 12, slurry pumps 13 and 24 of a double-alkali circulating water system, an ash residue filtering device 15, a lime slurry device 16, a sewage pump 20, a soda tank 23, an alkali-resistant pump 25, a dirt remover 26, a sedimentation tank 27, a clear liquid tank 28 and the like.

The operation process is as follows: the discharged flue gas 2 from a boiler room (or a kiln) 1 enters a Venturi tube 6 at a high speed through a smoke inlet tube 3, meets a circulating alkaline water atomization curtain sprayed by a splash cone type nozzle at the throat part of the Venturi tube, and gas and liquid are in collision contact with each other, so that turbulent flow is generated at a venturi diffusion section and are fully mixed. The small droplets are collected to form dust drops accompanied with SO, and the dust drops are condensed into large particles₂Absorption of (2). CaSO formed₄The sediment is discharged through water seal along with the sewage and enters a water circulation system. The gas, liquid and solid mixed flue gas flow formed by the turbulent flow enters the drop catching separator 9 along the spiral line direction under the action of the forced pulling force of the induced draft fan 11.

Most of dust particles and SO are generated by the action of the Venturi tube 6₂The dust particles which are not collected and have smaller particle sizes enter the drop collecting separator 9 along the spiral line direction along the gas-liquid mixed flue gas flow and spirally rise between the centrifugal cylinder and the gall bladder column along the rotational flow plate. The upper line of each partition plate in the cyclone device has the functions of separating liquid and intercepting mixture under the state that the flue gas moves along with the spiral centrifugal force, the intercepted dirt slag steps into the lower line of the gap of the partition plate to collide with the flue gas flow to form strong atomized gas-liquid mixing action, and sulfur components are separated and mixed by gas-liquid strong rotation after being repeatedly separated and absorbed. At this time, the liquid film formed from the overflow means descends from the inner wall of the drip catcher along the gap line, and the air current and the liquid film form a convection current, which containsThe sulfur dust particles are separated outwards along with the mixed sewage drops under the action of inertia force, gravity and centrifugal force, and the ash water drops are thrown into the gap of the rotational flow plate along with the flow direction when meeting the liquid film, are intercepted, trapped and dropped to a water seal for discharge. Thereby achieving the gas-liquid separation and further absorbing SO₂And for dust removal purposes. The purified flue gas is led to a chimney 12 through an induced draft fan 11 to be discharged, and the sewage containing the sediments is recycled after being treated by a water circulation treatment system.

The slag flushing water 5 discharged from the boiler room 1 and the sewage 7 discharged after the desulfurization and dust removal of the dust removal equipment are led to the sedimentation tank 27 through the sewage drain 8 for treatment and recycling. In the double alkali method circulating water treatment part, ash 14 filtered by an ash filtering device 15 is generally transported and treated; the water source for the lime slurrifier 16 to lime 18 consists of two parts: namely, make-up water 17 and slurried water 19 pumped up by a sewage pump 20 from the rear section of the sedimentation tank 27; the sodium hydroxide tank 23 is the make-up water 21 for the sodium hydroxide 22.

A spiral rotational flow device is arranged in a drop catching separator 9 of the double-alkali wet desulphurization and dust removal system, and the upper line of a multilayer rotational flow plate of the device has the intercepting function of separating liquid and solid and the lower line of the multilayer rotational flow plate has the atomization gas-liquid mixing function under the dynamic condition. The device greatly enhances the centrifugal force action of the grey water drops and precipitates, and improves the interception and trapping capacity of the rotational flow to the grey water drops and solids, thereby achieving more effective gas-liquid separation and dehydration effects.

In addition, the overflow water supply system of the drip catcher 9 is provided with a splash plate type overflow device which adopts a fully closed structure to prevent the equipment from generating splash due to the fact that air is sucked into the equipment under the condition of negative pressure operation to damage an overflow film. In addition, the device also has the advantages of scale prevention, easy maintenance and the like.

A splash cone nozzle is provided in the water supply system of the venturi tube 6. The nozzle has uniform water curtain, and can be adjusted according to water pressure and flow rate for optimum air turbulence and SO generation of Venturi tube 6₂And dust particle absorption and mixing effects, and the scale formation and abrasion can be prevented in the operation of a water supply system, thetwo technologies in the water supply system are not blocked and scaled, the flexibility of use and adjustment is strong, and the water supply system can be maintained and replaced at any time after the operation exceeds the age limit.

Finally, a deslagging box is arranged in front of the smoke outlet pipe 10 of the device, and when the smoke passes through the deslagging box, the last closing process ensures that the wet particulate dust left in the smoke is intercepted, so that the smoke can be discharged according to the optimal requirement.

The slag flushing water 5 of the boiler (or kiln) 1 and the dust-containing sewage 7 discharged by the equipment enter an ash multistage sedimentation tank 27 from a sewage discharge ditch 8, the sediments are pumped out to an ash filtering device 15 by a slurry pump 13 at the bottom of the tank for water filtering treatment, the filtered water returns to the sedimentation tank 27, flows to a clean water tank 28 at the tail of the sedimentation tank through multistage sedimentation, and then is pumped into a lime slurrying device 16 arranged above the middle section of the sedimentation tank 27 by a sewage pump 20, lime 18 is conveyed into the lime slurrying device 16 by a lime conveyor, and is converted into slurry together with make-up water 17 by the lime slurrying device 16, and the slurry enters the middle section of the sedimentation tank 27 under the control of a flow valve, so as to ensure that the pH value of the circulating water meets the requirement. The alkali-resistant pump 25 pumps the mixed alkaline liquid in the clear liquid pool back to the system for recycling through a water feeding pipeline. The water consumed during the operation can be supplemented by the water source at any time.

Practice proves that the equipment has ideal desulfurization and dust removal efficiency, can not cause the unfavorable phenomena of equipment scaling,blockage, water carrying of a draught fan, dust deposition and the like, and simultaneously, the low-cost running cost of the system equipment can create a wide space for popularization and application.

Of course, the desulfurization of the double-alkali wet desulfurization dust removal system can also adopt an alkaline aluminum sulfate-gypsum method or a CAL method. (for example, Na can be used as the first absorbent in the case of sodium-alkali double alkali method₂CO₃、Na₂SO₃Isobasic substance)

Claims

1. The invention relates to a double-alkali wet desulphurization and dust removal system, which comprises a smoke inlet pipe (3), a Venturi pipe (6), a drop catching separator (9), a smoke outlet pipe (10), an induced draft fan (11), a chimney (12), a double-alkali wet circulating water system and the like, and is characterized in that the double-alkali wet circulating water system comprises slurry pumps (13) and (24), an ash residue filtering device (15), a liming slurry device (16), a sewage pump (20), a sodium-alkali tank (23), an alkali-resistant pump (25), a dirt remover (26), a sedimentation tank (27), a clear liquid tank (28) and the like.

2. The double-alkali wet desulphurization and dust removal system according to claim 1, characterized in that: the drop catching separator (9) is internally provided with a spiral cyclone device.

3. The double-alkali wet desulphurization and dust removal system according to claim 1, characterized in that: a splash plate type overflow device is arranged on the drip catching separator (9).

4. The double-alkali wet desulphurization and dust removal system according to any one of claims 1 to 3, characterized in that: a splash cone type nozzle is arranged in the Venturi tube (6).

5. The double-alkali wet desulphurization and dust removal system according to any one of claims 1 to 4, characterized in that: the desulfurization process of the system can be a sodium-alkali double-alkali method (for example, the first absorbent can be NaOH or Na by adopting the sodium-alkali double-alkali method)₂CO₃、Na₂SO₃Etc.) or an alkaline aluminum sulfate-gypsum method, CAL method, etc.