The drop entrainment for moving with high velocity gases and re-heating gas scrubbing

 

(57) Abstract:

Usage: the invention relates to systems on the basis of limestone for wet gas purification by countercurrent contacting flue gases in open towers with nozzles for adsorption of SOxfrom flue gases. Essence: in the application described a method of removing sulfur oxides (SOxfrom the exhaust flow of the flue gas water limestone slurries with high efficiency thanks to the use of advanced drop entrainment. In a preferred embodiment, the one-way flow of wet limestone scrubber for cleaning gases (preferably with a spray zone of contact of less than 6 m tall), working at the speed of the main mass flow of gases over 4.5 m/s, the vertical flow of the flue gas released from a significant portion of the droplets of the slurry and is waived for effective separation of fog in tomboulides with good drainage for horizontal flows. The drop entrainment is a single device with a single shoulder blades, oriented to work effectively reduced when the degree of collision of droplets from the upper walls (nadroga horizontal shaft rotary heat exchanger and significantly reduced space requirements and the system of connecting channels. The invention allows to reduce the height of the tower and provide the additional advantage of ease of use vertically oriented rotary gas-gas heat exchanger. 4 C. and 22 C.p. f-crystals, 4 Il.

The technical field to which the invention relates

The invention relates to improvements associated with the separation of liquid droplets from gas streams, with a high degree of efficiency and reliability, and in the preferred embodiment, with the removal of sulfur oxides (SOx) from flue gases. The present invention is intended in particular for use in systems based on limestone for wet gas cleaning, employ open tower with nozzles for countercurrent contact for absorption SOxfrom flue gases, primarily in open towers with nozzles that operate at very high reduced velocities of the gases to increase the efficiency of the contact.

A number of industrial processes based on contacting your high-speed gas flow with liquid droplets with subsequent separation of gas and liquid. These include various washing processes gases, such as Prov is containing a series of sulfur (for example, fuel, such as meteoblue and coal), form different oxides of sulfur, which belong to the group of SOx. Legislation the need to reduce emissions of SOx. One of the most effective methods of processing waste streams of flue gases to reduce the content of SOxis based on the use of limestone wet scrubbing gases. Technology on a limestone wet scrubbing using a well developed and effective, but it is related with needs very cumbersome equipment and proportional costs. For several reasons, which are listed in conjunction pending application for U.S. patent 08/257160, the rights to which are transferred to the ordinary procedure filed on behalf of G. E. Bresowar, J. Klingspor and E. Bakke June 9, 1994 (registration number patent attorney 1930-R), it is useful to be able to use the high speed gases.

Unfortunately, the use of high velocity gas in counterflow installations of gas-liquid contact, such as open tower with nozzles, an inherent tendency to increase the difficulty of the technological procedure when removing captured by the flow of liquid droplets and exacerbating problems associated with maintaining purity humanitarnim tomboulides in such processes there is a tendency to clogging, because polluting liquid supersaturated with calcium sulfate. Covered deposits walls, roof and other equipment can increase the pressure drop on the way through this equipment and periodically lead to the breaking off of large pieces of sediment solid material and damage another important technological equipment, such as spray headers, nozzles, fasteners, etc. Besides, the fall in liquid or slurry technological system can get solid materials that can clog nozzles and, therefore, result in lower system reliability. Thus, there is a need for an improved device for removing the captured liquid droplets (e.g., sludge for washing gases) from a rapidly moving gas streams (for example, the exhaust flow of flue gases).

Effective for this purpose separators to carry out liquid should cause a collision of liquid droplets from one or more surfaces, which leads to the loss of liquid from the gas stream. These surfaces must be easy drainage and ease of washing. In addition, they should not Sukarno installed humaniatarian, but it is impractical, if the vertical direction of gas flow must be changed due to its occurrence in contact with the channel walls. The results would be the formation of deposits and related problems.

Wet gas cleaning and other techniques that depend on the gas-liquid contact with the destruction of the captured fluid flow of the flue gas, it is advisable to improve through better carry out removal of liquid droplets in combination with high performance, low pressure drop and a weak tendency to the formation of deposits or layers of solid materials contained in the liquid.

The most simple design and work are the single open tower system in which to interact with SOxuse calcium carbonate. These systems are often preferred because they can operate with very low pressure drop and have a low tendency to form deposits or clogging. However, their inherent simplicity and reliability in some cases are reduced to nothing because of their large size, which is due to the reactivity of the used slurry of calcium carbonate. So, e.g. plates or nozzles, the height of the towers, as a rule, it is, therefore, to ensure good communication apply multiple levels of spray nozzles. In addition, the ability of a liquid for washing the gases to absorb SOxof the gas depends on the availability contained in the liquid Foundation, but with increasing alkalinity solubility of calcium carbonate decreases, therefore, to promote good absorption SOxeven under conditions of high content continue to construct the highest tower.

Wet scavenging of gases in one-way open towers, where for processing flue gases containing SOxuse calcium carbonate, it is advisable to improve by increasing the linear speed of the exhaust flow in the tower from the bottom up and by reducing the height of the tower to reduce the necessary working space and provide the additional advantage of ease of use vertically oriented rotary gas-gas heat exchanger.

Background of the invention

Technology wet cleaning of flue gases to remove SOxprovides the contacting gas with liquid in a number of different ustanavochny, employ nozzles or plates. In a huge variety of such constructions gas expires vertically upward, and the liquid under the action of gravity expire from top to bottom. It was suggested to use different reagents, but the most preferred are those that can be purchased at a low price and to store and transport with a minimum of manipulation. Therefore, as a reagent was selected calcium carbonate (commercially available in several varieties, including limestone), because it satisfies such criteria, and with the right process produces by-products that can be easily disposed of as waste in landfills or sold as gypsum.

Design and operation of single counterflow towers with nozzles with the use of limestone described Rader and Bakke in the work of Incorporating Full-Scale Experience Into Advanced Limestone Wet FGD Designs presented on IGCI Forum '91, September 12, 1991, Washington, DC. Open tower with nozzles (i.e., those with missing nozzles, plates or other means of contributing to the contacting gas with liquid) represented as simple in construction and highly reliable in the flue gas desulfurization (EDC). S="ptx2">

Known and commercially available tomanually described Jones, McIntush, Lundeen, Rhudy and Bowen in the work of the Mist Elimination System Design and Specificatoin for FGD Systems, presented on 16 August 1993, The 1993 SO2Control Symposium, Boston, PCs Minnesota. Through extensive testing on a special test rig, the authors show that a high speed (i.e., those that exceed approximately 4.5 meters per second) vertical ascending gas flow in the spray zone create difficulties for the effective tomanually because of this phenomenon, which is known as "breakthrough". Breakthrough occurs when humaniatarian actually flooded with liquid due to inadequate drainage. Depending on the specific design of such a breakthrough at different speeds gases demonstrate tomanually different designs. However, in General after a vertical upward gas stream at a rate of more than 4.5 meters per second satisfactory results does not show any humaniatarian, and for all of them characterized by the risk of leakage.

You must ensure that humaniatarian, which would be effective at even higher gas velocities of 4.5 meters per second, about katoh threads have design tomboulides, demonstrated suitability for the velocities of the gas streams in the zone of atomization than 4.5 meters per second. Often this design describe how tomanually system with the plant N. V. Provinciale Zeeuwse Energie-Maatschappij, setting 12, located in the Netherlands, Borselli, which presents as quite satisfactory in Rosenberg and Koch in the message Stack Gas Emissions Control Coordination Center Group of Battelle July 10, 1989, At the heart of this construction is that humaniatarian for horizontal flow, situated in a circle near and above the spray zone for vertical flow. Carry out of the spray zone, the sludge should move up, and then outwardly radial turn and pass through humaniatarian. This humaniatarian operates at a given surface speed that is much lower than the velocity in the spray zone of the tower, actually 20% lower than the gas velocity in the spray zone. Moreover, the upper part of tomboulides used below its potential, whereas the lower part, which are closest to the spray zone, operate with the majority of the flue gas and carry out the sludge. This setup, as used in Borssele, costly when made, what you can and should expect education on the roof of large quantities of layers due to collision with moving it from the spray zone drops vertically, the direction in which tomboulides would not change. Thus, although it is recognized and it is common practice to work tomanually in EDC systems on the basis of the limestone at the speed horizontal flow of 4.5-6.0 meters per second, borzelleca design inoperative under such conditions because of the dangers of education on the roof of the deposits.

The collision of droplets of slurry surfaces both before and after tomanually during the process in EDC systems on the basis of limestone, it is undesirable. After such collisions of the droplets, which are not separated in the form of droplets, i.e., it does not remove or drain under the action of their own weight, as precipitation of dissolved calcium ions together with absorbed by the sulfite is oxidized to sulfate form of film deposition. These gypsum film deposits tend to spontaneous accumulation, with a noticeable speed increase up to, until, under the action of mechanical forces or their total weight is breaking. This situation is the tower with nozzles and other equipment.

In the prior art are not described methods and devices necessary for improvements to carry out removal of liquid droplets from the EDC-scrubbing of gas streams moving vertically with speeds of more than 4.5 meters per second, without the problems of the aforementioned type.

In one-way flow of open scrubbing towers of the type described by Rader and Bakke, liquid for flushing gas on the basis of calcium carbonate expire from top to bottom, while containing SOxthe exhaust flow moves upward. The authors summarize the established empirically the values of several parameters, including the gas flow rate in the absorber (resulting minimum 6 and maximum 15 feet per second, i.e., from about 2 to less than 4.5 meters per second), indicating that the gas flow rate in the absorber has little impact on the ratio between liquid and gas (G/G), which is a key factor for both capital and operating costs. The height of the spray zone of contact in these towers, not shown, but typical values typically range from about 6 to about 15 m, which, based on experience, is considered as an important factor when designing the effe the flue gases.

SOxmainly SO2absorb downward slurry for washing gases and collected in the reaction vessel, in which form calcium sulfite and calcium sulfate. To accelerate the formation of sulfate reaction tank, it is advisable to saturate with oxygen. After growing crystals of sulphate of sufficient size to separate from the slurry discharged from the reaction tank. Such scrubbing tower is relatively cheap, but the size and therefore the cost of the machines can serve as a factor limiting the applicability of the scrubbers of this type on existing power plants.

Heat the incoming flue gas, typically used for reheating sweet flue gas after washing, but before discharge from the chimney. If this is not done, will be visible plume of smoke, and all the unwanted components will not rise up and over as needed. In a typical very high scrubbing towers of known construction rotary gas-gas heat exchangers are often used in a horizontal position - rotation around the vertical axis. Such an installation is placed in a convenient location, and the system configuration channels select the one which requires a complex system of channels, connecting the apparatus for re-heating and scrubbing tower, and because of the corrosive gases, this system of channels is quite expensive in manufacture, and installation.

Article K. R. Hegemann and others, entitled THE BISCHOFF FLUE GAS DESULFURIZATION PROCESS (presented in EPA and EPRI, who were co-sponsors of the First Combined FGD and Dry SO2Control Symposium, 25-28 October 1988 ), is considered scrubbing tower with a horizontally oriented, equipped with a vertical shaft rotary unit for reheating of the type described. Obviously, the setting for reheating placed in this orientation requires expensive system of channels, which corresponds to the large height of the scrubber tower.

In article Hegemann and others also described hydrocyclone circuit, which from the tower for wet gas cleaning allocates gypsum slurry in the form of a stream of coarse particulate material and a stream of finely dispersed solid particles, and this stream of finely dispersed solid particles are returned to the scrubber. In U.S. patent 5215672 Rogers and others describe the same way Hegemann and others, in which as the primary dewatering device used hydrocyclone. In this case, after the Department is aguinaga flow of the fine particles discharged into the waste at least with a part of the deleted stuff. However, none of the descriptions of these technical solutions are not told how the hydrocyclone of this type can be used to reduce the tower height and orientation settings for reheating so that it took up less space and require less complex system of connecting channels.

In the prior art are not described methods and devices necessary for improvement in relation to the size of the tower and spatial solutions installation for re-heating in the case of a single open tower countercurrent scrubbers wet reducing the amount of SOxthe limestone.

Description of the invention

The object of the present invention is an improved design and placement of mapletronics installed during the process before tomboulides for horizontal flows in the device for contact between gas and liquid.

Another object of the invention is an improved design and placement of mapletronics in one-way open tower countercurrent scrubbers wet limestone cleaning gases to effectively carry out removal of droplets of fluid the plants is improved design and placement of mapletronics in one-way open tower countercurrent scrubbers wet limestone cleaning gases to effectively carry out removal of liquid droplets from gases moving with a high velocity vertically upwards and the deviation of the direction of flow from the roof of the scrubber tower.

Another special object of the invention is to increase the performance and availability of one-way open tower countercurrent wet limestone scrubber gas cleaning to improve the speed of passing on him gases without substantial pressure drop is the result of tomanually, excessive deposits on the walls of the scrubber (especially on the roof), contamination of drop entrainment and clogging or leakage drops through humaniatarian.

Another special object of the invention is to increase the performance and availability of one-way open tower counter-current wet limestone scrubbers cleaning gases increase the speed of gases flowing through them, changing the flow of gases towards the end of tomboulides for horizontal flow and the creation of a relatively uniform velocity profile of the movement of gas included in the final humaniatarian.

A more specific object of the invention is the reduction of size and displacement which opened the flue gases and ensuring high efficiency of the process.

Another preferred variant implementation of the invention is the improvement of the work of one of the open tower countercurrent wet limestone scrubber gas cleaning by reducing the height required for the spray zone of contact in the tower, reducing the size of the system connecting channels required for re-heating normal flue gas, and ensuring the overall improved efficiency of the process.

These and other objects are realized by means of the present invention, which offers improved methods and apparatus for the wet purification of gases, in particular flushing gas streams generated by the combustion of serosoderjaschei fuels, such as coal and solid wastes.

In accordance with one of the objects of the invention offers an improved method of wet gas cleaning to reduce the content of SOxin the flue gas, including the flow of flue gas through the scrubber tower from the bottom up; the introduction of an aerosol of droplets of an aqueous slurry of finely ground calcium carbonate, calcium sulfate, calcium sulfite and other directionspublic solid materials in contact with flue gas in ve is but the flow of flue gas and collected in the liquid after contact; passing the flue gas through the single drop entrainment, located above the vertical scrubbing section and across it at an angle to the direction of flow, that reduce the number of droplets, carried away by the gas, and changing the direction of flow of flue gas. Preferred drop entrainment effectively reduces the number of droplets by at least 40%, and also changes the direction of flow of the flue gases by at least 45% relative to the vertical axis of the tower. Then the flue gas is directed through set after the drop entrainment during the process humaniatarian with good drainage for horizontal flow. In a preferred embodiment of which is open tower countercurrent wet limestone scrubber gas cleaning gas flow speed in the vertical scrubbing section exceeds approximately 4.5 meters per second.

Also in the preferred embodiment, the drop entrainment is oriented in the scrubbing tower at an angle relative to horizontal of approximately 10-45oand preferably causes a low pressure drop which is less than about 0.15 inches of water column, but at the same time removes at the x size, which can be easily removed with the help of those further along the process of tomboulides for horizontal flows.

In a preferred embodiment, the drop entrainment to collect drops due to collisions and to rotate the gas flow in the direction most appropriate for subsequent tomanually, apply one-way separator blades. Individual blades are held parallel to each other in each of several sets. The blades are oriented at an angle of about 45-55orelative to the vertical. Typically, these individual blades are a plate in the shape of a parallelogram with a smaller size from about 15 to about 23 cm and the large size of from about 60 to about 150 see the Gap between the individual blades, typically, ranges from about 40 to about 70% smaller size of the individual blades. Many separate sets of blades are preferably oriented at an angle of about 120-150orelative to each other with the creation of the configuration of the fabric weave "broken twill". In a preferred embodiment, the blades periodically washed directly spraying the blades of the wash water from both above and below.

According to what the actual content of the SOxin the flue gas, comprising (a) heat transfer from the SOx-containing flue gas with the supply of this gas through the inlet opening in the bottom section of the vertically oriented, equipped with a horizontal shaft rotary heat exchanger, this heat exchanger has a lower section and an upper section, each of which is provided with inlet and outlet openings, and a heat exchanger rotor with peripheral heat exchange surface and a horizontal axis of rotation, enabling the heat exchange surface of the rotor to move in a vertical plane between the upper and lower sections; (b) the flow of flue gas from the bottom up by scrubbing tower, the height of the spray zone of contact which is less than 6 metres; (C) introduction aerosol of droplets of an aqueous slurry of finely ground calcium carbonate, calcium sulfate, calcium sulfite and directionspublic solid materials that descend from the tower on the principle of counter-current relative to the flow of flue gas, with the aim of cleaning the specified flue gas from the SOxand get washed flue gas; (g) removing virtually all, except for minor parts, carry out the fog from the flue gas, and (d) UB>-containing flue gas to the washed flue gas.

Another object of the invention is an improved device for wet gas cleaning to reduce the content of SOxin flue gases, comprising (a) a heat exchanger, which has a lower section and an upper section, each of which is provided with inlet and outlet openings, and a heat exchanger rotor with peripheral heat exchange surface and a horizontal axis of rotation, providing a heat exchange surface of the rotor can move in a vertical plane between the upper and lower sections; (b) scrubbing tower, which has a duct inlet gas duct for gas release and vertical scrubbing section, and the height of the spray zone of contact is less than 6 metres; (b) a group of the spray devices placed inside the scrubber section, the layout which is designed for the introduction of an aerosol of an aqueous slurry of finely ground calcium carbonate, calcium sulfate, calcium sulfite and directionspublic solid materials, descending in the tower on the principle of counter-current relative to the flow of flue gas; (g) the set of one or more of capetronic the achi thread SOx-containing flue gas through the inlet opening in the lower part of the rotary heat exchanger and exhaust therefrom through the discharge outlet and the flow of flue gas from the upper part of the tower through the inlet opening in the upper part of the heat exchanger to transfer heat from the SOx-containing flue gas to the washed flue gas and removing therefrom through the discharge outlet.

Brief description of drawings

The nature and advantages of the present invention are described in more detail below with reference to the accompanying drawings, which depict:

in Fig. 1 is a schematic illustration of a preferred variant of the method according to the invention using one of the open tower countercurrent wet limestone scrubber gas cleaning;

in Fig. 2 - axonometric image of drop entrainment shown in the tower with nozzles according to Fig. 1;

in Fig. 3 - axonometric view of another variant of execution of drop entrainment according to the invention;

in Fig. 4 is a schematic illustration of a preferred variant implementation of the method and device according to the invention using one of the open tower countercurrent scrubber wet limestone tx2">

Industrial applicability

The main object of the following description of a preferred variant according to Fig. 1, which shows the process which is open tower countercurrent wet limestone cleaning gas to remove sulfur oxides, primarily SO2from flue gases. However, from the following description it is obvious that the techniques according to the invention can find application for other gas-liquid processes and scrubbers other types.

The diagram of the preferred implementation of the method according to Fig. 1 shows the flow of flue gas, such as waste from industrial or domestic boiler solid fuel coming through the duct 20 into the scrubber 100 for wet gas cleaning. The gas inside the tower expires upward vertical scrubbing section 110 in the counter-flow to the spray water slurry, which contains finely ground limestone and supplied by a set of spray nozzles 112 and 112'. In the spray tower is broken into droplets. Gas flow rate according to the invention exceed 4,5, preferably comprise from about 5 to about 6 feet per second. Such gas velocity suitable for single open tower scrub the positive quantities of an aqueous slurry, for example, at low ratios of W/,

Limestone is the preferred form of calcium carbonate, but if necessary it can be replaced with another type. In addition to limestone other possible forms of calcium carbonate are oyster shells, aragonite, calcite, chalk, marble, marl, and travertine. You can apply fossil material or produced in the production. In this description, the terms "calcium carbonate" and "limestone" are used interchangeably. In a preferred embodiment, the limestone is finely milled, preferably up to srednevekovogo of particle size less than about 8 microns at their introduction.

The sulfur oxides from the flue gases is absorbed by the water phase of the slurry and interact with the contained calcium with the formation primarily of calcium sulfite, which can then be oxidized with the formation of calcium sulphate. To a certain extent, the reaction proceeds in a falling droplets, but the main part of the reaction takes place in the reaction vessel 120, in which a slurry.

The washed exhaust gas flow passes through the drop entrainment 130 according to the invention, which removes a substantial part of carry out ka who administers the flow changes from vertical to almost horizontal. This has several advantages, including a weak collision of the sludge with a roof 102 scrubbing tower. Important is also the possibility to combine high speed exhaust flow with a highly efficient removal of almost horizontal stream of fine droplets of mist through a vertical tomboulides 140. In turn, the advantage of a high velocity gas flow in the vertical scrubbing section 110 is that they allow a better pseudoagouti droplets of the slurry for washing gases, increasing the duration of contact of each of the droplets from the waste stream during the height of the tower. Then washed and freed from the mist exhaust stream can be removed from the exhaust duct 150.

Without taking the necessary measures according to the invention at high gas velocities, which are suitable for improving the EDC process, problems arise with the formation of deposits on the roof 102 of the tower and tomanually of known construction. These deposits can be formed in all cases, when we carry out the liquid of the slurry becomes possible to accumulate and when it does not wash away or not give it to drain from the surface. Carry out the sludge can quickly oversaturated suline significant deposits. Large quantities of fat can increase the pressure drop while passing through the scrubber and to cause breaking large pieces and drop into the tower with nozzles that can cause damage to reservoirs, nozzles or supporting elements, and a possible drop in the reaction tank 120, where such deposits recirculation pump can be supplied to the reservoir 112 and 112', causing clogging of the spray nozzles 114.

The use of more efficient tomanually instead of drop entrainment could be considered as an effective solution, however, for the above reasons, when the vertical velocities of the gas stream from about 4.5 to about 6.0 meters per second tomanually for the most part ineffective. Without the use of the present invention a high speed is unacceptable for the deposits, which are formed on the roof 102. It can be argued that a simple washing of the roof 102 and exposed to surface fresh water would be adequate means of preventing the formation of deposits without the use of the present invention. But despite the fact that it can be really feasible, the invention has other advantages, cochise these other advantages at the same time, cleaning exposed surfaces becomes optional.

According to the invention which is a drop entrainment 130 is placed over the vertical scrubbing section 110 and across it. The design and location of drop entrainment 130 provide an opportunity to effectively reduce the number of drops of water and also to change the direction of flow of flue gases, giving them orientation, ensuring the rational use of high-performance tomboulides for horizontal flows. The drop entrainment 130 shown in Fig. 2 as oriented in the scrubber tower 100 at an angle to the horizontal. In the preferred embodiment, this angle is from about 10 to about 45ofor example, approximately 20o.

In Fig. 2 shows the preferred embodiment of the drop entrainment 130, which used one roll of separator vanes 132 for collecting droplets due to collisions, and rotation of the gas flow in the direction most appropriate for subsequent tomanually, and preferably ranges from direct collision with the upper wall 102 of the scrubbing tower. Individual blades 132 are mounted in frames 133 education sets 134, 134', and so on Variout depending on the desired weight of each set, moreover, this weight is that one or two members of staff if necessary can easily install or remove the package. Typically, one set of approximately three to six blades. These sets are placed so that they are adjacent to each other and integrally formed kapitbahay lattice. The lower edges of the frames 133 define a bottom surface 135 sets 134, etc. of the Individual vanes 132 are oriented at an angle to the vertical. Typically, the blade of this type is a rectangular plate with a smaller size from about 15 to about 23 cm and the large size of from about 60 to about 150 see the Gap between the individual blades, typically, ranges from about 40 to about 70% smaller size of the individual blades. Preferably the angle is from about 35 to about 55oand its exact value depends on the desired angle of the direction of exhaust flow.

Sets 134, etc. are designed and oriented in such a way as to provide better drainage. Separate kits are mounted to the configuration of the fabric weave "broken twill", as shown in the drawing. Sets 134, etc. preferred is but from about 125 to about 145o(most preferably approximately 140o). Design of drop entrainment relies on elements 136, whose length corresponds to the length of each of the sets. Other design support tools. Although the drawing shows a rectangular sections, scrubbing tower, typically has a circular cross-section, therefore, sets near the wall are characterized by respective rounded configuration.

Design of drop entrainment 130 provides direct contact wash the blades with stationary mounted nozzle tubes 137, equipped with spray nozzles 138, can directly spray the wash water blade from above and from below. Flushing, usually produced by connecting each of the wash reservoir separately and sequentially, one after the other, but there are other possible schemes washing. So, for example, may be acceptable at the same time the two collectors. High quality wash water and the quantity in which it is used, sufficient to reduce the content on the separating surfaces of saturated solutions of dissolved salts. Typically, the flow rate of wash fluid Wadi. Leaching of drop entrainment from above is usually carried out with a flow rate in the same interval, but less than when washing the bottom. To prevent the accumulation of gypsum deposits leaching sets the top and bottom preferably is carried out in accordance with established practice, i.e. with frequent cycles. Good drainage attained sets 134, etc., in the form of a fabric weave "broken twill", in combination with the use of high-quality wash water and with frequent washings enables operation with virtually no sludge formation. However, the procedure of washing and water parameters can be varied depending on the needs of the EDC process.

A distinctive feature of the invention is not necessary that the efficiency of separation of drop entrainment was as high as a multi-pass separators are known and used in the art, since the ability to change the direction of flow from vertical to horizontal enables the use of highly efficient humaniatarian 140 for horizontal flows. Thus, even though the efficiency of removal of material ablation is lower than this Liprimar, less than about 0.15 inches of water column, reduce the number or consolidates up to 40% of droplets smaller than 100 microns and has other advantages from the point of view of Ocidente, drainage, ease of maintenance, durability, deflection of the gas stream from the surfaces of the upper walls and roof of the tower and relatively uniform orientation of the gas flow in the direction of highly effective tomboulides 140 for horizontal flows. Preferred humaniatarian 140 deflection type, for example, with zigzag deflector of this type, which is described in the mentioned article, Jones, etc.

Another embodiment of the invention shown in Fig. 3, which presents the only set 334 blades 332, laid diagonally in a flat panel, based on the frame 333. The blades are oriented at an angle (in particular from about 15 to about 40opreferably approximately 20o) to the frame and form the same angle with the vertical, as in the embodiment of Fig. 2.

It should be noted that the sets of blades according to Fig. 3 are characterized by rather not configuration sets in the form of a fabric weave "broken twill" and flat ledges between the reference elemenary, created by the angle a and angle .

The below described preferred variant according to Fig. 4, which shows the process which is open tower countercurrent wet limestone cleaning gas to remove sulfur oxides, mainly SO2from the exhaust flow of flue gases. However, from the following description it is obvious that features of the invention provide advantages over the scrubbers other types.

The flowsheet of Fig. 4 shows the processing of the waste stream after cleaning it, as, for example, in the electrostatic precipitator or fabric filter (not shown), which provides practical destruction of the captured stream of solid particles. Cleaned flue gas then passes through the duct 421 in the heat exchanger 431, which has a lower 432 and the upper section 433. Both the lower and upper sections are provided with inlet openings (434, 437) and outlet openings (435, 436). Relatively hot gas (in particular with temperatures ranging from about 420 to about 175oC) heats the internal heat exchanger rotor 438 (shown in broken lines) with the peripheral heat-exchange surface. The rotor 438 rotates around a horizontal axis of rotation 439, allowing its heat poveshenami flue gas, used for re-heating the washed flue gas entering through the inlet opening 437 in the upper section 433 and out through the exhaust hole 436 before removing channel 422 to a chimney (not shown).

After exiting outlet 435 lower sections SOx-containing flue gas is sent to the tower 400 for wet purification of gases, where it expires upward, countercurrent to the aerosol containing finely ground limestone water slurry emitted inside vertical scrubbing section 410 a set of spray nozzles. Of section 410 of the flushing gas gas passes through the exhaust duct 420. The configuration of the tower causes the flow of flue gas passing upwards along the vertical scrubbing section. Sludge, washing the gas impinging on the vertical scrubbing section 410, gather in the reaction tank 430. The total height of the spray zone contact 411 inside the scrubber section 410 is less than 6 meters.

Limestone is the preferred form of calcium carbonate, but if necessary it can be replaced with another type. In addition to limestone other forms of calcium carbonate are oyster shells, Arago is TBE. In this description, the terms "calcium carbonate" and "limestone" are used interchangeably.

Limestone finely milled, preferably by grinding, to achieve srednevekovogo particle diameter of approximately 10 μm, most preferably 8 μm or less, when the content of particles smaller than 44 microns 99 wt.% or more. This material is solely onkodispanser for wet cleaning of gases in an open tower with counter-current expiration flow limestone slurry. More typical particle size during milling prior art corresponds srednevekovoi diameter of 15 μm or less at a content of 90 weight. % or more of particles with a size less than 44 microns. As another difference from the prior art, it should be noted that during grinding to the preferred size according to the invention receive particles srednevekovogo size less than about 6 μm at a content of 99.5 wt.% particles with a size less than 44 microns. The use of grinding to the size of the particles allows for several advantages, primarily in the processing of the slurry from the reaction tank in the hydrocyclone to remove gypsum and concentration of calcium carbonate in the form of more fine particles, as described the lower is her. The composition of this group is designed for the input of an aerosol of an aqueous slurry of finely ground calcium carbonate, calcium sulfate, calcium sulfite and directionspublic solid materials, descending in the tower in countercurrent to the flue gas stream. The drawing shows a set of spray nozzles, which are shown as consisting of three rows 412, 412' and 412" nozzles.

The nozzle preferably with a gap between the rows is less than approximately 2 m and serially alternating direction expiration of adjacent nozzles up and down. The reduction of the gap between the nozzles, reducing the number of simultaneously operating levels (preferably up to 2) and increase the speed of the upward flow of the gas inside the vertical scrubbing section provide an opportunity to keep the height of the tower in the spray zone of contact of less than 6 meters, preferably in the range of from about 4 to about 6 feet (measured from the top of the intake box to the bottom of the pan installed drop entrainment 440), which in the drawing, the position of H.

The preferred placement of the nozzles of this type are described in co-pending application for U.S. patent 08/257160 filed by the authors of this sebastodes description as a reference.

Reaction tank 430 is located below the spray device that allows you to collect the sludge at the end of the period of contact with the flue gas within the spray zone contact 411. The size of the reaction tank 430 acceptable to interact dissolved SO2with dissolved oxygen to form sulfate with subsequent interaction of sulfate with dissolved calcium ions with the formation of gypsum crystals, srednevekovoi the diameter of which at least 2 times, preferably 5 to 10 times, greater than the particle size of calcium carbonate entered as raw materials.

Due to the difference between the particle sizes of calcium carbonate and gypsum, and the device used to separate gypsum and concentration of calcium carbonate, as described in more detail below, the concentration of solid material in the calcium carbonate can be increased by approximately 20-50% relative to the achievable previously known counterflow structural designs. An additional advantage is that such sludge is characterized by a higher stoichiometric ratio between calcium and sulfur than in previously known systems, as a rule, the components on the call absorbed water phase of the slurry in the vertical scrubbing section 410 and interact with contained in the main component in the form of hydroxide ions with the formation of bisulphite, which may be partially oxidized in the scrubber section 410 and almost completely oxidized in the reaction tank 430 with the formation of sulfate. The presence of the main component is caused mainly by the dissolution of calcium carbonate, which occurs in the scrubber section 410, and in the reaction tank 430. In order to ensure the sufficient completeness of the reaction is preferably, as in the prior art, to use oxygen bubbling, although some oxygen can be obtained from the flue gas in the scrubber section 410. To a certain extent, the reaction proceeds in a falling droplets, but the main part of the reaction in the reaction tank 430, in which a slurry. One of the distinguishing features of the invention is that the length of stay in the reaction tank in comparison with a conventional commercial value approximately equal to 15 hours, reduced to about 6 hours Decrease length of stay in the reaction tank has a number of advantages from the point of view of simplicity of the process, machine size and quality of the gypsum obtained as a by-product.

The preferred pH value is but 5.8 to about 6.3 to. A higher pH indicates a high content of available main component in a liquid slurry and consequently to an increased ability of a liquid to absorb SO2. The advantage of the invention is that, because the calcium carbonate comes in the form of fine particles and is sent for recycling in the form of fine particles, an increased content of the main component. In previously known systems to increase the speed of reaction of calcium carbonate, typically use a low pH values, but in normal conditions due to the reduction of the number of available main component that slows down the absorption of SOxin scrubber section 410. Particles of small size provide high content of available main component even at such pH values that are lower than required, to a considerable extent thereby compensating the influence of low pH on the ability of the sludge to wash the gas.

With the reaction tank 430 and a group of spray devices, placed in a vertical scrubbing section 410, associated feeder sprayable slurry containing at least the pump 422 and communicated with him nozzle 424 for Ari this scrubbing section.

The washed exhaust stream substantially freed from captured them of liquid droplets and the direction of flow is changed by the drop entrainment 140, and then tomboulides 450. The direction of motion of the main mass of the exhaust flow is changed from vertical to almost horizontal. Then washed and freed from the mist exhaust stream can be removed in the heat exchanger 431, directing it on the frame 460 in the upper inlet 437.

Preferably, the scrubber according to the invention include one, the drop entrainment 440, that reduce the number of drops of water, and changing the direction of flow of the flue gases with this orientation, which allows efficient use of humaniatarian for horizontal flow. Capetronic of this type described above.

In line 470 air facilitates the supply of oxygen for the oxidation of calcium sulfite to calcium sulfate. The contents of the tank should preferably be mixed with conventional devices, which are not shown.

With the reaction tank 430 is reported hydrocyclone 480, which is used to remove from the reaction tank 430 part of the sludge with I plaster. Hydrocyclone 480 separates sludge discharged from the reaction tank, the recirculation flow of 482 rich in small particles of calcium carbonate, and another thread 484, containing the bulk of the relatively large particles of calcium sulfate. It is preferable to provide a rinse using is returned to the process flow, namely the recirculation flow 482. In the drawing this is indicated by the discharge pipe 485.

A preferred value of the stoichiometric ratio between calcium and sulfur in the recirculation flow 484 typically ranges from about 1.2 to about 2.0, the most preferably from about 1.3 to about 1.4. The concentration of suspended solids in the recirculating flow generally is from about 1 to about 10 wt.%, most often from about 2 to about 6 wt.%. The separation of the main mass of calcium sulfate from limestone in the hydrocyclone 482, in addition to the mentioned increase of the stoichiometric ratio and the content of the main component, reduces the amount of solid materials in the slurry.

The above description illustrates how any expert in the art may make variations of its execution, which become obvious to a person skilled in the art from the present description. However, it should be noted that all such obvious modifications and embodiments of the subject scope of the invention defined by the attached claims. This means that the formula of the invention includes all of the claimed elements and stages in any arrangement or sequence that applies to achieve its goals, unless the context otherwise.

1. The method of wet flue gas cleaning to reduce the content of SOxincluding the flow of flue gas through the scrubber tower from the bottom up, the introduction of an aerosol of droplets of an aqueous slurry of finely ground calcium carbonate, calcium sulfate, calcium sulfite and directionspublic inert materials in contact with flue gas in a vertical scrubbing section in countercurrent to the flue gas stream, the collection of sludge in the form of liquid after contact with the gas stream, characterized in that the flue gas stream after contacting and passing them vertical scrubbing section is passed through the single drop entrainment, located above the vertical scrubbing section orthogonal to it under at the x gas and to reject the flow direction of the flue gas from the vertical.

2. The method according to p. 1, characterized in that the drop entrainment is adapted to reduce the number of droplets, at least 40% and the deviation of the direction of flow of the flue gases, at least at 45ofrom the vertical axis of the tower.

3. The method according to p. 1, characterized in that the flue gas in the form of a horizontal flow drain through humaniatarian located in the process after the drop entrainment.

4. The method according to p. 1, characterized in that the bulk of the gas is served by scrubbing tower at a rate greater than approximately 4.5 m/s

5. The method according to p. 1, characterized in that the drop entrainment in the scrubber tower is oriented relative to the horizontal at an angle of about 10 to 45o.

6. The method according to p. 1, characterized in that the drop entrainment causes a pressure drop less than about 0.15 inches of water column and removes or merges, at least 40% of the droplets, the average size of which Sauter is less than approximately 100 microns.

7. The method according to p. 1, characterized in that the drop entrainment used one roll of separator blades to collect droplets due soudaine blades fixed in parallel to each other in each of the multiple sets.

8. The method according to p. 1, characterized in that the drop entrainment has a single separator vanes that are mounted with the formation of bundles and oriented at an angle of about 35 - 55orelative to the vertical, and the gap between them is approximately 40 to 70% smaller size of the individual blades.

9. The method according to p. 1, characterized in that the drop entrainment has many separate sets of blades, and these sets are oriented relative to each other at an angle of about 120 - 150oWith, forming the configuration weave fabric "broken asparagus."

10. The method according to p. 1, characterized in that the blades of drop entrainment periodically washed with a direct spray wash water on the top and bottom.

11. Device for gas-liquid contact with the vertical scrubbing section, characterized in that above the scrubber section and across it placed the single drop entrainment so as to provide a reduction being carried away by the gas drops and the change of direction of the flow of flue gases, the drop entrainment installed humaniatarian for drainage horizontal flow of gases.

12. The device according to p. 11, differently is Alenia flow of flue gases by at least 30ofrom the vertical axis of the tower.

13. The device according to p. 11, characterized in that it is a single open counterflow tower for wet limestone scrubber and has at least one drop entrainment and vertically oriented humaniatarian, where the specified drop entrainment reduces the number of droplets by at least 40% and the deviation of the direction of flow of flue gases by at least 30ofrom the vertical axis of the tower.

14. The device according to p. 11, characterized in that the drop entrainment in the scrubber tower is oriented at an angle of about 10 - 45orelative to horizontal.

15. The device according to p. 11, characterized in that the drop entrainment has many of the separating blades for the collection of droplets due to collisions, and rotation of the gas flow in the direction most suitable for subsequent separation of the fog, and the blades are fixed parallel to each other in each of the many kits and oriented at an angle of about 35 - 55orelative to the vertical.

16. The device according to p. 15, characterized in that the individual blades are rectangular plates with smaller size, about the R between the individual blades is from about 40 to 70% smaller size of the individual blades.

18. The device under item 17, characterized in that the drop entrainment has many separate sets of blades.

19. The device under item 18, characterized in that the separate sets of blades are oriented relative to each other preferably at an angle of about 120 - 150owith the creation of the configuration weave fabric "broken asparagus."

20. The device according to p. 11, characterized in that it further comprises a spray device for washing the blades of drop entrainment direct spray wash water on the top and bottom.

21. The method of reducing the content of SOxin the flue gas wet gas cleaning, including heat transfer from the SOx-containing flue gas, purified from captured them solid materials, by submission of this gas in the rotary heat exchanger having upper and lower sections with holes for input and output of gas and heat exchange rotor with peripheral heat exchange surface, the flow of flue gas from the bottom, up one-way-flow open-scrubbing tower, the introduction of an aerosol of droplets of an aqueous slurry of finely ground calcium carbonate, calcium sulfate, calcium sulfite and directionspublic solid materials in kooga gas, collection of sludge in the reaction tank, the separation of crystals of calcium sulfate and the return of the recirculation flow in the scrubbing zone and the flow of flue gas from the top of the tower in a heat exchanger with heat transfer from containing SOxflue gas washed flue gas, characterized in that the rotary heat exchanger is placed vertically with obtaining the horizontal axis of rotation, while the heat exchanger rotor with peripheral heat exchange surface has a horizontal axis of rotation which transfer the heat exchange surface of the rotor in a vertical plane between the upper and lower sections, the height of the gas purification zone support less than 6 m, srednevekovoi particle size of calcium carbonate in aqueous suspension support less than about 10 microns, in the collection of the sludge in the reaction tank allow crystal growth of calcium sulfate until while srednevekovoi diameter of these crystals of calcium sulfate will not exceed at least 2 times the size of the particles of calcium carbonate entered as raw material before separating the crystals of calcium sulfate and return recirculation flow in the scrubbing zone, and the pH of the suspension in the reaction of the particles of finely ground calcium carbonate when its input is less than about 8 microns.

23. The method according to p. 21, characterized in that the molar ratio between calcium and sulfur in the recirculation flow exceeds approximately 1.3.

24. The method according to p. 21, characterized in that the sludge is removed from the reaction vessel, is passed through a hydrocyclone to obtain a recycle stream rich in small particles of calcium carbonate, which is returned to the reaction vessel, and a stream rich in relatively large particles of calcium sulfate, which is then removed.

25. The method according to p. 24, characterized in that the molar ratio between calcium and sulfur in the recirculation flow exceeds approximately 1.3, srednevekovoi the particle size of finely ground calcium carbonate is less than about 8 microns, srednevekovoi particle size of the calcium carbonate in the reaction vessel is from about 2 to 6 μm, and the aerosol is supplied from the nozzles on two levels.

26. Wet flue gas cleaning to reduce the content of SOxcontaining a rotary heat exchanger having upper and lower sections with holes for input and output of gas and heat exchange rotor with peripheral heat-exchange surface, scrubbing basei scrubbing section group spray devices for introducing a spray of an aqueous slurry of finely ground calcium carbonate, of calcium sulfate, calcium sulfite and directionspublic solid materials, in countercurrent to the flue gas stream in the tower, and a duct for conveying a stream containing SOxflue gas through the inlet opening in the lower part of the rotary heat exchanger and exhaust gas through the exhaust opening in the upper part of the heat exchanger to transfer heat from containing SOxflue gas washed flue gas and removing therefrom through the outlet opening, characterized in that the rotary heat exchanger is oriented vertically with obtaining the horizontal axis of rotation of the rotor, enabling the heat exchange surface of the rotor to move in a vertical plane between the upper and lower sections, it is equipped with a drop entrainment, and the height of the section of the spray from contacting the upper part of the inlet duct to the bottom of the drop entrainment is less than 6 m

 

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