| Title of Invention | PRECIPITATION EQUIPMENT |
|---|---|
| Abstract | The invention provides precipitation equipment that provides an easy installation of an additional apparatus in existing equipment including a variety of structures and that permits the installation work to be accomplished in a minimum shutdown time of the existing equipment. In the precipitation equipment including the existing equipment including an existing exhaust air duct and an electrostatic precipitator newly added to the existing equipment, there are provided: a trestle installed in the vicinity of the existing exhaust air duct and supporting the additional electrostatic precipitator thereon at a predetermined height; an inflow duct for introducing an exhaust gas from the existing exhaust air duct into the electrostatic precipitator; an outflow duct for returning the exhaust gas purified by the electrostatic precipitator to the existing exhaust air duct; an inflow connecting duct for communicating the inflow duct with an upstream side of the existing exhaust air duct; and an outflow connecting duct for communicating the outflow duct with an downstream side of the existing exhaust air duct. |
| Full Text | PRECIPITATION EQUIPMENT FIELD OF THE INVENTION This invention relates to electrostatic precipitation equipment provided with an additional electrostatic precipitator for enhancing the dust precipitation performance of the existing equipment. BACKGROUND OF THE INVENTION The precipitation equipment of this type is known as a precipitator for removing dusts present in boiler exhaust gas from a thermal power plant or a variety of iron making furnaces. There is known in the art an electrostatic precipitator which is provided with an additional collector electrode at place downstream of a stationary collector electrode fixed to place in order to enhance the dust precipitation performance thereof, the additional collector electrode shaped like an endless belt and disposed orthogonal to a gas flow direction. Such electrostatic precipitators are disclosed in JP-U No.57(1982)-177550 and JP-A No.2001-321693. SUMMARY OF THE INVENTION Problems to be Solved by the Invention JP-U No.57(1982)-177550 discloses an arrangement wherein the additional collector electrode is mounted to a gas outlet of the existing electrostatic precipitator. JP-A No.2001-321693 discloses an arrangement wherein in addition to the above collector electrode shaped like the endless belt, a collector electrode made of a steel sheet or the like is added to the existing electrostatic precipitator. However, both of the above arrangements are made such that the additional collector electrode is disposed in the casing of the existing electrostatic precipitator. This not only leads to a difficult work to retrofit the existing equipment with the additional apparatus but also requires modification to increase the size of the casing. That is, the above arrangements are not adapted for large-scale modification. Fig.1 illustrates an example of ordinary existing precipitation equipment for boiler exhaust gas treatment at a thermal power plant. In the precipitation equipment, a denitrificator 2, an electrostatic precipitator 3, a desulfurizer 4 and the like are arrayed as large structures for removal of nitrogen oxides, dusts and sulfur oxides present in the exhaust gas from a boiler 1. The individual structures are interconnected by an exhaust air duct 9 through which the exhaust gas flows. Furthermore, small structures 7 are interposed between the large structures. The precipitation equipment as a whole is congested with a variety of structures. In a case where a large-scale plant modification is planned to add a new electrostatic precipitator for improving the dust precipitation performance, it is difficult to install the electrostatic precipitator at place between the large structures. In addition, the installation of the electrostatic precipitator on the ground is obstructed by the small structures. In view of the above problem in the art, it is an object of the invention to provide electrostatic precipitation equipment that facilitates the installation of an additional apparatus in the existing equipment including a variety of structures and permits the installation work to be accomplished in a minimum shutdown time of the existing equipment. BREIF DESCRIPTION OF THE INVETION According to an aspect of the invention for achieving the above object, precipitation equipment comprising existing equipment including an existing exhaust air duct and a newly added electrostatic precipitator, the precipitation equipment further comprises: a trestle installed in the vicinity of the existing exhaust air duct and supporting the electrostatic precipitator thereon at a predetermined height; an inflow duct for introducing an exhaust gas from the existing exhaust air duct into the electrostatic precipitator; an outflow duct for returning the exhaust gas purified by the electrostatic precipitator to the existing exhaust air duct; and connecting ducts for communicating the respective ducts with the existing exhaust air duct. In another aspect of the invention, the precipitation equipment is characterized in that the connecting ducts include an inflow connecting duct for communicating the inflow duct with an upstream side of the existing exhaust air duct, and an outflow connecting duct for communicating the outflow duct with a downstream side of the existing exhaust air duct. In another aspect of the invention, the precipitation equipment is characterized in that the electrostatic precipitator is a moving electrode electrostatic precipitator including a moving-type collector electrode, and has a stacked structure built by stacking carried-in members on the trestle. In another aspect of the invention, the precipitation equipment is characterized in that the inflow duct and outflow duct are located above the existing exhaust air duct and are connected from above to the existing exhaust air duct via the inflow connecting duct and the outflow connecting duct, respectively. In another aspect of the invention, the precipitation equipment is characterized in that the height of the trestle is set to a value to facilitate tie-in connection between the inflow duct and the existing exhaust air duct and between the outflow duct and the existing exhaust air duct. In another aspect of the invention, the precipitation equipment is characterized in that the existing exhaust air duct is provided with a check valve for blocking the passage of internal exhaust gas in order to cause the internal exhaust gas to take a roundabout course through the electrostatic precipitator via the inflow duct and the outflow duct. ADVANTAGEOUS EFFECTS OF INVENTION The invention provides an easy installation of the additional electrostatic precipitator in the existing equipment including the existing structures and minimizes the shutdown time of the existing equipment during which the installation work for the additional electrostatic precipitator is accomplished. BREIF DESCRIPTION OF DRAWINGS Fig.1 is a schematic diagram illustrating the overall arrangement of ordinary existing precipitation equipment; Fig.2 is a schematic diagram illustrating the overall arrangement of electrostatic precipitation equipment according to an embodiment of the invention; Fig. 3 is a diagram illustrating a step of installing a trestle for installing an additional electrostatic precipitator of the above electrostatic precipitation equipment; Fig. 4 is a diagram illustrating a step of installing a lower frame of the above electrostatic precipitator; Fig. 5 is diagram illustrating a step of installing a main frame of the above electrostatic precipitator; Fig. 6 is a diagram illustrating a step of installing casing and roller beam of the above electrostatic precipitator; Fig. 7 is a diagram illustrating a step of installing electrodes of the above electrostatic precipitator; Fig. 8 is a diagram illustrating a step of installing an exhaust air duct of the above electrostatic precipitator; Fig. 9 is a plan view illustrating a positional relation between the above equipment and a crane in the installation work for the above electrostatic precipitator; and Fig.10 is a flow chart showing the steps of the installation work for the additional electrostatic precipitator of the above electrostatic precipitation equipment. DESCRIPTION OF EMBODIMENTS Fig. 2 is a schematic diagram illustrating the overall arrangement of precipitation equipment according to an embodiment of the invention for removal of dusts present in a boiler exhaust gas from a thermal power plant. In the figure, like reference characters refer to the corresponding components shown in Fig.1. The embodiment pertains to precipitation equipment including an electrostatic precipitator 8 newly added to existing precipitation equipment shown in Fig.l. A moving electrode electrostatic precipitator featuring a high dust precipitation function is employed as the additional electrostatic precipitator, a structure of which is disclosed in JP-A No.2000-342994, for example. Referring to Fig.2, the additional electrostatic precipitator 8 is installed at place between existing electrostatic precipitator 3 and desulfurizer 4 while the existing equipment is in operation. The existing apparatuses 3, 4 are communicatably interconnected by means of an existing exhaust air duct (flue) 9 having a rectangular section. In the above arrangement, however, small structures 7 already exist between the existing apparatuses 3, 4, thus obstructing the installation of the additional electrostatic precipitator 8 on an installation space between the existing apparatuses 3,4. According to this embodiment, the precipitation equipment includes: a trestle 20 installed in the vicinity of the existing exhaust air duct 9 and supporting the electrostatic precipitator thereon at a predetermined height; an inlet duct 8a for introducing an exhaust gas from an upstream side (on a side of the electrostatic precipitator 3) of the existing exhaust air duct 9 into the above electrostatic precipitator 8; and an outlet duct 9b for returning the exhaust gas purified by the electrostatic precipitator 8 to a downstream side (on a side of the desulfurizer 4) of the exhaust air duct 9. The additional electrostatic precipitator 8 for equipment expansion is installed atop the trestle 20. Now, an expansion work is described with reference to Fig.3 to Fig.8. In these figures, like reference characters refer to the corresponding components shown in Fig.1 and Fig.2. In Fig. 3, the trestle 20 has a greater height H than the small structures 7 already installed on the ground in order to avoid interference with the small structures. The trestle 20 is suspended from a crane 210 and carried to place spaced a given distance from a large structure 230. The trestle 20 is installed in a manner to extend over the small structures 7. The trestle 20 is disposed at place shifted sideways from the exhaust air duct 9 (shown in section) extending orthogonal to the drawing surface (Fig.10, S10). Namely, the trestle 20 is installed at place between the large existing structure 230 and the existing exhaust air duct 9. Subsequently, a work floor 10 is installed atop the trestle 20. A drainpipe 30 is connected to the work floor 10 for draining rain water (Fig.10, S20). Indicated at 220 is some other member to be carried in by the crane 210. In Fig. 4, a lower frame 40 is carried in by the crane 210 and installed on the work floor 10 (Fig.10, S30). Installed in the lower frame 40 is a hopper 50 (S40). The hopper 50 receives falling dust particles (soot and dust particles) precipitated and collected from the exhaust gas by the electrostatic precipitator 8. In Fig. 5 , the crane 210 installs a main frame 60 on the lower frame 40 (S50). Main components of the electrostatic precipitator are installed in the main frame 60. In Fig. 6, a casing 80 is carried in by the crane 210 and fixed to a periphery of the main frame (S60). Subsequently, a lower roller beam 100 and an upper roller beam 90 are fixed to the main frame 60 (S70, S80). Indicated at 70 is a flue (duct) inlet defined by the casing 80. A flue outlet 71 (not shown in Fig. 6) is provided on an opposite side from the flue inlet 70. In Fig.7, discharge electrodes 120 are suspended from the crane 210 and carried into the casing 80 from above. The electrodes are suspendedly fixed in the main frame 60 (S90). Subsequently, moving-type collector electrodes 110 are suspended from the crane 210 and carried into the main frame from above. The collector electrodes are mounted in a manner to surround the discharge electrodes 120 (S100). Upper rollers 130 and lower rollers 140 are rotatably mounted to the corresponding upper roller beam 90 and the lower roller beam 100. The collector electrodes 110 are entrained between these upper and lower rollers and driven into rotation by the rollers for collecting the dust particles from the exhaust gas based on the principle of electrostatic precipitation. The electrostatic precipitator 8 has a stacked structure built by means of the crane 210 stacking the carried-in members on the trestle 20 in this manner. In Fig. 8, stairs 150 for a worker to go up and down are carried in by the crane 210. The stairs 150 are fixed to lateral sides of the trestle 20, the lower frame 40 and the main frame 60. A stage 160 is mounted atop the casing 80 to close an upper part of the casing (S110). The two flue inlets 70 formed at the casing 80 are connected with respective ends of two inflow flues (inflow ducts) 180 having a rectangular section (S120). In this connecting condition, the other end of each inflow duct 180 is located above (straight above) the upstream side of the existing exhaust air duct 9. The two flue (duct) outlets 71 are provided on the opposite side from the two flue inlets 70. This connecting condition of the two flues is described with reference to a plan view of Fig. 9. Fig. 9 also shows a positional relation between the equipment and the crane 210 performing the installation steps. The casing 80 on the opposite side from the flue inlets 70 is formed with the two flue outlets 71, which are connected with respective ends of two outflow flues (outflow ducts) 181 (S120). In this connecting condition, the other end of each outflow duct 181 is located above (straight above) the downstream side of the existing exhaust air duct 9. Subsequently, the existing precipitation equipment is shut down (S130). In this shutdown state, connection portions of the existing exhaust air duct 9 are modified (S140). Specifically, an upper side of an upstream portion of the existing exhaust air duct 9 is formed with apertures 9a in opposed relation to the other ends of the respective inflow ducts 180, while an upper side of a downstream portion of the existing exhaust air duct 9 is formed with apertures 9b in opposed relation to the other ends of the respective outflow ducts 181. Thereafter, a connecting flue (inflow connecting duct) 190 having a height h shown in Fig.8 is mounted to the aperture 9a, while a connecting flue (outflow connecting duct) 191 having the height h shown in Fig. 8 is mounted to the aperture 9b (S150). Further, a check valve 9c is disposed within the existing exhaust air duct 9 substantially in the middle thereof. The check valve 9c is mounted to an upper side of the existing exhaust air duct 9 for blocking a flow of the exhaust gas. The other end of each of the inflow ducts 180 is connected to the inflow connecting duct 190 so as to communicate the inflow duct 180 with the upstream portion of the existing exhaust air duct 9. The other end of each of the outflow ducts 181 is connected to an upper end of the outflow connecting duct 191 so as to communicate the outflow duct 181 with the downstream portion of the existing exhaust air duct 9. When a main body of the additional electrostatic precipitator 8 is completed by taking the above-described installation work steps (S160), an operation test for the main body is conducted (S170). In the operation test, a voltage is applied to the electrostatic precipitator 8 to determine whether a predetermined voltage-current characteristic is obtained or not. If a spark voltage is not high enough, the electrostatic precipitator is inspected for inappropriate electrode-to-electrode distance and the like. A proper measure is implemented, followed by verification of whether a predetermined performance is achieved. After completion of the above test and mechanical adjustment, the operations of the existing precipitation equipment and the added electrostatic precipitator 8 are started (S180). In operation, the exhaust gas from the existing electrostatic precipitator 3 flows through the upstream portion of the existing exhaust air duct 9 and the inflow duct 180 and into the electrostatic precipitator 8. After purification in the electrostatic precipitator 8, the exhaust gas flows through the outflow duct 181 and into the downstream portion of the existing exhaust air duct 9. Specifically, the exhaust gas discharged from the existing electrostatic precipitator 3 does not flows directly into the existing desulfurizer 4 but takes a roundabout course through the added electrostatic precipitator 8 and into the existing desulfurizer 4. Accordingly, dust particles are collected from the exhaust gas in two steps using the existing electrostatic precipitator 3 and. the added electrostatic precipitator 8. The precipitation equipment removes dusts from the exhaust gas with high dust precipitation performance. The existing equipment takes only a short shutdown time because the shutdown time is a period between the modification of the existing exhaust air duct 9 for forming the connecting portions and the connection of the inflow ducts and the outflow ducts. The connecting duct 190 and the connecting duct 191 are interposed in a tie-in distance between the inflow duct 180 and the existing exhaust air duct 9 and a tie-in distance between the outflow duct 181 and the existing exhaust air duct 9, respectively. If either or both of the distances are subject to any dimensional error during assembly, adjustment is made by changing the height h of either one or both of the connecting duct 190 and the connecting duct 191. The height H of the trestle 20 is adjusted according to the height of the additional electrostatic precipitator 8 such that the tie-in distance between the inflow duct 180 and the existing exhaust air duct 9 and the tie-in distance between the outflow duct 181 and the existing exhaust air duct 9 may be substantially equal to the height h (to facilitate tie-in connection between the ducts). In the above-described installation steps, the individual members are carried in by the crane 210 which lifts them up, and moves and lifts them down to required places. The assembly work can be smoothly carried out because the installation steps are adapted to the assembly work in which the additional electrostatic precipitator is built by sequentially stacking the components thereof on the trestle 20 first installed at place. Further, the inflow duct 180 and the outflow duct 181 are carried in and placed above the existing exhaust air duct 9 so that the inflow duct and the outflow duct may approach from above to be connected to the existing exhaust air duct 9 via the inflow connecting duct 190 and the outflow connecting duct 191, respectively. Therefore, the crane 210 can accomplish the assembly work efficiently. WE CLAIM 1. Precipitation equipment comprising existing equipment including an existing exhaust air duct and a newly added electrostatic precipitator, the precipitation equipment further comprising: a trestle installed in the vicinity of the existing exhaust air duct and supporting the electrostatic precipitator thereon at a predetermined height; an inflow duct for introducing an exhaust gas from the existing exhaust air duct into the electrostatic precipitator; an outflow duct for returning the exhaust gas purified by the electrostatic precipitator to the existing exhaust air duct; and connecting ducts for communicating the respective ducts with the existing exhaust air duct. 2. The precipitation equipment according to Claim 1, wherein the connecting ducts include an inflow connecting duct for communicating the inflow duct with an upstream side of the existing exhaust air duct, and an outflow connecting duct for communicating the outflow duct with a downstream side of the existing exhaust air duct. 3. The precipitation equipment according to Claim 1 or 2, wherein the electrostatic precipitator is a moving electrode electrostatic precipitator including a moving-type collector electrode, and has a stacked structure built by stacking carried-in members on the trestle. 4 . The precipitation equipment according to Claim 2 or 3, wherein the inflow duct and outflow duct are located above the existing exhaust air duct and are connected from above to the existing exhaust air duct via the inflow connecting duct and the outflow connecting duct, respectively. 5. The precipitation equipment according to any one of Claims 1 to 4, wherein the height of the trestle is set to a value to facilitate tie-in connection between the inflow duct and the existing exhaust air duct and between the outflow duct and the existing exhaust air duct. 6. The precipitation equipment according to any one of Claims 1 to 5, wherein the existing exhaust air duct is provided with a check valve for blocking the passage of internal exhaust gas in order to cause the internal exhaust gas to take a roundabout course through the electrostatic precipitator via the inflow duct and the outflow duct. The invention provides precipitation equipment that provides an easy installation of an additional apparatus in existing equipment including a variety of structures and that permits the installation work to be accomplished in a minimum shutdown time of the existing equipment. In the precipitation equipment including the existing equipment including an existing exhaust air duct and an electrostatic precipitator newly added to the existing equipment, there are provided: a trestle installed in the vicinity of the existing exhaust air duct and supporting the additional electrostatic precipitator thereon at a predetermined height; an inflow duct for introducing an exhaust gas from the existing exhaust air duct into the electrostatic precipitator; an outflow duct for returning the exhaust gas purified by the electrostatic precipitator to the existing exhaust air duct; an inflow connecting duct for communicating the inflow duct with an upstream side of the existing exhaust air duct; and an outflow connecting duct for communicating the outflow duct with an downstream side of the existing exhaust air duct. |
|---|
| Patent Number | 279399 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Indian Patent Application Number | 880/KOL/2011 | |||||||||
| PG Journal Number | 04/2017 | |||||||||
| Publication Date | 27-Jan-2017 | |||||||||
| Grant Date | 19-Jan-2017 | |||||||||
| Date of Filing | 01-Jul-2011 | |||||||||
| Name of Patentee | HITACHI PLANT TECHNOLOGIES LTD, | |||||||||
| Applicant Address | 5-2, HIGASHI-LKEBUKURO 4 -CHOME, TOSHIMA-KU, TOKYO 17O-8466, JAPAN, | |||||||||
Inventors:
|
||||||||||
| PCT International Classification Number | C09K8/52 | |||||||||
| PCT International Application Number | N/A | |||||||||
| PCT International Filing date | ||||||||||
PCT Conventions:
|
||||||||||