EP0197023A2 - Procédé et dispositif de nettoyage des échangeurs gaz-gaz - Google Patents

Procédé et dispositif de nettoyage des échangeurs gaz-gaz Download PDF

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Publication number
EP0197023A2
EP0197023A2 EP86890062A EP86890062A EP0197023A2 EP 0197023 A2 EP0197023 A2 EP 0197023A2 EP 86890062 A EP86890062 A EP 86890062A EP 86890062 A EP86890062 A EP 86890062A EP 0197023 A2 EP0197023 A2 EP 0197023A2
Authority
EP
European Patent Office
Prior art keywords
air
line
flue gas
valve
inlet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP86890062A
Other languages
German (de)
English (en)
Other versions
EP0197023A3 (fr
Inventor
Peter Cmejrek
Werner Dipl.-Ing. Gottlieb
Otto Ing. Gruber
Hermann Dipl.-Ing. Dr. Rabitsch
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Simmering Graz Pauker AG
Original Assignee
Simmering Graz Pauker AG
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Filing date
Publication date
Application filed by Simmering Graz Pauker AG filed Critical Simmering Graz Pauker AG
Publication of EP0197023A2 publication Critical patent/EP0197023A2/fr
Publication of EP0197023A3 publication Critical patent/EP0197023A3/fr
Withdrawn legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J3/00—Removing solid residues from passages or chambers beyond the fire, e.g. from flues by soot blowers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28G—CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE OR HEAT-TRANSFER CONDUITS, e.g. WATER TUBES OR BOILERS
    • F28G13/00—Appliances or processes not covered by groups F28G1/00 - F28G11/00; Combinations of appliances or processes covered by groups F28G1/00 - F28G11/00
    • F28G13/005—Appliances or processes not covered by groups F28G1/00 - F28G11/00; Combinations of appliances or processes covered by groups F28G1/00 - F28G11/00 cleaning by increasing the temperature of heat exchange surfaces

Definitions

  • the invention relates to a method and a device for cleaning gas / gas heat exchangers by temporarily heating the deposited impurities by means of a hot gas stream above their evaporation temperature, the evaporated impurities being discharged with the gas stream.
  • DeNOx systems are intended as catalytically active systems for reducing the nitrogen oxide (NO x ) content, which are also referred to as SCR systems (selective catalytic reduction) and are arranged in front of the air preheater in calorific power plants, etc. This is because the efficiency of DeNOx systems is cheapest at temperatures from 300 to 400'C.
  • the mode of operation of the SCR process is based on the introduction of NH 3 into the flue gases in the presence of a catalyst, such as WO 3 , MoO 3 , or V 2 O 5 , resulting in the following reaction equations:
  • part of the S0 2 produced during combustion is converted to S0 3 .
  • the mode of action of the catalyst is not only limited to the reaction between NH 3 and NO X , there is also an albeit slight oxidation of SO 2 to SO 3 .
  • the NH 3 introduced into the flue gas stream does not react completely according to the reaction equations given above.
  • the unreacted NH 3 referred to as NH 3 slip, combines with S0 3 to form various salts, primarily ammonium sulfate NH 4 HS0 4 , which is in liquid form at temperatures below approx. 250 ° C., especially below 230 ° C. especially in air preheaters (metal temperatures in the range of 100 to 350 ° C) with adhesive ash particles and leads to pressure drops or blockages.
  • the object of the invention is therefore to provide a method and a device for cleaning gas / gas heat exchangers with which the above disadvantages can be avoided, with a shortening of the cleaning time and cleaning of the entire heating surfaces of the heat exchanger to be achieved.
  • the process for cleaning gas / gas heat exchangers by temporarily heating the deposited impurities by means of a hot gas stream above their evaporation temperature, the evaporated impurities being discharged with the gas stream is characterized in accordance with the invention in that in the case of a heat exchanger, in particular Ljungström Kunststoffvor Anlagenr, with an upstream DeNOx
  • a heat exchanger in particular Ljungström Kunststoffvor Simon Techr
  • the entire heating surfaces of the heat exchanger, both of the heat-emitting and of the heat-absorbing region, are heated above the evaporation temperature of the impurities, in particular ammonium bisulfate.
  • the heating takes place optionally with flue gas, with hot air, with heating gas, or with a combination of these types of heating.
  • a first device for carrying out the method is characterized in that, in the case of an air preheater, a shut-off valve is provided at the air inlet and at the air outlet, and that a bypass line with a shut-off valve starts from the fresh-air line before the inlet-side shut-off valve and after the outlet-side shut-off valve into the hot air line opens out, a heat exchanger preferably being arranged in the bypass line.
  • a second device for carrying out the method is characterized in that in an air preheater a flap valve is provided at the flue gas inlet and at the flue gas outlet, and that a bypass line with a flap valve in front of the inlet side flap valve from the Flue gas line goes out and opens into the flue gas line after the outlet-side shut-off valve, a first heat exchanger being arranged in the fresh air line in front of the air preheater, the primary circuit of which is coupled to the secondary circuit of a second heat exchanger which is arranged in the flue gas line in front of the outgoing bypass line.
  • a third device for carrying out the method is characterized in that a shut-off valve is provided for an air preheater at the flue gas inlet and at the flue gas outlet, and that a bypass line with a shut-off valve starts from the flue gas line in front of the inlet-side shut-off valve and after the outlet-side shut-off valve into the flue gas line opens, a first heat exchanger being arranged in the fresh air line in front of the air preheater, the primary circuit of which is coupled to the secondary circuit of a second heat exchanger which is arranged in the bypass line.
  • a fourth device for carrying out the method is characterized in that, in the case of an air preheater, a heat source is arranged in the fresh air line upstream of the air preheater, the heat exchanger preferably being a steam air preheater or a surface burner.
  • a fifth device for carrying out the method is characterized according to the invention in that with two air preheaters at the air inlet and at the air outlet a butterfly valve is provided for each air preheater.
  • a sixth device for carrying out the method is characterized in that shutoff valves are provided in two air preheaters at the air inlet and at the air outlet as well as at the flue gas inlet and at the flue gas outlet of each air preheater, that a connecting line with a shut-off valve is provided between the hot air lines after the outlet-side shutoff valves, and that a connecting line with a butterfly valve in front of the inlet-side butterfly valve starts from each fresh air line and opens into the associated flue gas line after the outlet-side butterfly valve.
  • a bypass line with a shut-off flap in front of the inlet-side shut-off flap starts from the flue gas line and opens into the flue gas line after the outlet-side shut-off flap.
  • a seventh device for carrying out the method is characterized in that, in the case of two air preheaters, the hot air lines each have a first connecting line after the shut-off flaps on the outlet side, each having a shut-off flap, the ends of the first connecting lines being brought together and passing into a second connecting line, the end of which is divided into two third connecting lines, each having a butterfly valve, and the Ends of the third connecting lines between the inlet-side butterfly valve and the air inlet of the respective air preheater opens into the fresh air lines.
  • An eighth device for carrying out the method is characterized in that, in the case of two air preheaters, a connecting line is provided with a shut-off valve between the two air preheaters, which starts from the fresh air line between the inlet-side shut-off valve and the air inlet of one air preheater and into the hot air line of the other air preheater after its outlet-side shut-off valve opens.
  • a connecting line with a shut-off valve between the fresh air lines of both air preheaters is provided, which opens into the fresh air lines in front of the inlet-side shut-off valves or starts from them.
  • Fig. 1 denotes a boiler, which is preceded by an air preheater 2, on the inlets or outlets of which air and flue gas shut-off valves A, B, C and D are arranged.
  • a blower 3 the fresh air passes through a shut-off valve N into the fresh air line 4, and from this via the inlet-side shut-off valve A into the air preheater 2.
  • the heated air passes through the outlet-side shut-off valve B into the hot air line 5 and from there into the boiler 1.
  • the flue gases emerging from the boiler 1 enter a DeNOx system 6 and reach the air preheater 2 via the flue gas line 7 and the inlet-side shut-off valve C.
  • the flue gases emerging from the air preheater 2 reach the flue gas line 8 via the outlet-side shut-off valve D, enter a flue gas aftertreatment system 9, for example a flue gas desulfurization system, and are released into the atmosphere via a chimney 10.
  • a bypass line 11 with a butterfly valve E starts in front of the inlet-side butterfly valve A from the fresh air line 4 and opens after the outlet-side butterfly valve B into the hot air line 5.
  • butterfly valves A to D and N are open and butterfly valve E is closed.
  • butterfly valve E is opened, butterfly valves A and B are closed, while butterfly valves C, D and N remain open.
  • the air preheater 2 is thus bypassed on the air side via the bypass line 11, ie the fresh air enters the boiler 1 at a temperature of, for example, 20 ° C.
  • the flue gases enter the air preheater 2, for example at a temperature of 370 ° C., and thus heat up all Heating surfaces up to this temperature.
  • This embodiment enables a relatively simple retrofitting of existing systems.
  • a heat exchanger 12 can be installed in the bypass line 11, as a result of which the combustion air is preheated. In the example according to FIG. 1, the heating surfaces of the air preheater are therefore heated above the evaporation temperature of the ammonium hydrogen sulfate with flue gas.
  • a bypass line 13 with a shut-off flap F in front of the inlet-side shut-off flap C starts from the flue gas line 7 and opens into the flue gas line 8 after the shut-off flap D on the outlet side.
  • a first heat exchanger 14 is arranged in the fresh air line 4, the primary circuit of which is coupled to the secondary circuit of a second heat exchanger 15, which is arranged in the flue gas line 7 before the outgoing bypass line 13.
  • a circulation pump 16 is provided in the return of the first heat exchanger 14.
  • the first heat exchanger 15 can also be arranged as a heat exchanger 15 1 in the bypass line 13.
  • the butterfly valves A to D and N are open, while the butterfly valve F is closed and the circulation pump 16 is out of operation.
  • the butterfly valves C and D are closed, the butterfly valve F is opened and the circulation pump 16 is started, while the butterfly valves A and B remain open.
  • the fresh air is heated from, for example, 20 ° C. to 350 ° C. via the two heat exchangers 14 and 15 or 15 1 .
  • the flue gases entering the second heat exchanger 15 or 15 ′ for example at 380 ° C., leave it at approximately 150 ° C.
  • the heating surfaces of the air preheater are heated to approx. 350 ° C with hot air, which means that cleaning takes place more quickly since there are no contaminants such as ash, NH 3 and SO 3 in the hot air. Because there is no increase in the exhaust gas temperature, there is also no reduction in efficiency.
  • the arrangement of the second heat exchanger 15 'in the bypass line 13 has the advantage that there is no pressure loss through the heat exchanger during normal operation.
  • a heat source 17 is arranged in the fresh air line 4 in front of the air preheater 2 and is preferably designed as a steam air preheater.
  • Butterfly valves A to 0 and N remain open both in normal operation and in cleaning operation.
  • the steam air preheater is started up for cleaning.
  • the steam air preheater can be built relatively small. No bypass lines are required.
  • the fresh air enters the steam air preheater at 20 ° C and leaves it at approx. 350 ° C.
  • air preheater 2 there is an increase to approximately 360 ° C.
  • the flue gases enter the air preheater at approx. 380 ° C and leave it at approx. 360 ° C.
  • the example according to FIG. 4 is almost identical to the example according to FIG. 3. Instead of a steam air preheater, a surface burner is used as the heat source 17, so that heating with hot gas and hot air takes place.
  • two air preheaters 21 and 22 are used. Accordingly, two fans 31 and 32 with shut-off flaps N1, N2 are present in the fresh air lines 41, 42.
  • the shut-off flaps of one air preheater 21 are designated Al to D1 and those of the other air preheater 22 are designated A2 to D2.
  • the fresh air lines are designated 41.42, the hot air lines 51.52 and the flue gas lines 71.72 and 81.82, the latter opening into the flue gas line 8.
  • a connecting line 18 with a butterfly valve G is provided between the fresh air lines 41 and 42, which opens into the fresh air lines 41, 42 in front of the inlet-side shutters A1, A2.
  • the cleaning process is described for the air preheater 22, for example.
  • the butterfly valves Al to Dl, A2 to D2 and Nl, N2 are open and the butterfly valve G is closed.
  • the butterfly valves A2 and B2 are closed, while the butterfly valves A1 to D1, C2, D2 and N1, N2 remain open.
  • the butterfly valve G can optionally be open or closed in order to operate the air preheater 21 with one or both To allow blowers 31,32.
  • the fresh air is heated in the air preheater 21 at about 350 * C, and the flue gas leaves the two flue gas ducts 71,72 to about 380 ° C.
  • the flue gas leaves the air preheater 21 at approximately 150 ° C., it exits the air preheater 22 at approximately 380 ° C. In the common flue gas duct 8, a mixing temperature of about 270 ° C will set. The air preheater 22 is therefore cleaned with flue gas.
  • FIG. 7 is similar in structure to the example of FIG. 6.
  • a bypass line 91, 92 with a shut-off flap F1, F2 is added to each air preheater 21, 22, which flows from the flue gas line 71, 72 before the inlet-side shut-off valve Cl, C2 and after the exhaust-side shut-off valve D1 , D2 opens into the flue gas line 81, 82.
  • the butterfly valves C2, D2, G, K1, F1 and N2 are closed, while the butterfly valves A1 to D1, A2, B2, F2, H and K2 and N1 are open.
  • the hot air is cleaned bypassing the air preheater on the flue gas side 22.
  • the flue gas emerging from the air preheater 21 at a temperature of approximately 150 ° C. mixes with the flue gas / hot air mixture from the air preheater 22 at a temperature of approximately 370 ° C. in the common flue gas line 8 to a temperature of approximately 260 ° C.
  • the flue gas from the air preheater 21 exits at a temperature of approximately 150 ° C.
  • the air preheater 22 is flown through on the flue gas side.
  • the shut-off flaps A1 to D1, B2, C2, D2, M1, L2, Nl and N2 are open here, and the shut-off flaps A2, Ll and M2 are closed, while the shut-off flap G can again be optionally open or closed.
  • the air preheater 22 is thus flowed through on the flue gas side in comparison to operating mode a), so that the cleaning time is shortened even further.
  • the flue gas emerges from the air preheater 21 again at approximately 150 ° C. and from the air preheater 22 at approximately 360 ° C. and mixes in the common flue gas line 8 to a temperature of approximately 240 ° C.
  • the cleaning time is reduced to approximately 2 to 10 hours, depending on the degree of soiling and on the particular circuit according to FIGS. 1 to 9.
  • a single DeNOx system 6 is provided for the flue gas line coming from the boiler 1. It goes without saying that a separate DeNOx system can also be used in each case with two flue gas lines emerging from the boiler 1.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Air Supply (AREA)
  • Chimneys And Flues (AREA)
EP86890062A 1985-03-25 1986-03-13 Procédé et dispositif de nettoyage des échangeurs gaz-gaz Withdrawn EP0197023A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT882/85 1985-03-25
AT88285 1985-03-25

Publications (2)

Publication Number Publication Date
EP0197023A2 true EP0197023A2 (fr) 1986-10-08
EP0197023A3 EP0197023A3 (fr) 1986-12-30

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ID=3502001

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Application Number Title Priority Date Filing Date
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2790257A1 (fr) * 1999-02-26 2000-09-01 Kvaerner Process France Sa Procede d'elimination de sels, notamment de sulfates et de pyrosulfates d'ammonium
US6183707B1 (en) * 1992-06-08 2001-02-06 Biothermica International Inc. Incineration of waste gases containing contaminant aerosols
CN106224989A (zh) * 2016-07-22 2016-12-14 河北省电力建设调整试验所 一种在线清除燃煤电厂空预器中硫酸氢铵堵灰的方法
CN109210555A (zh) * 2017-07-03 2019-01-15 大唐保定热电厂 电站锅炉脱硝投运空气预热器在线干烧清堵系统和技术
CN113739190A (zh) * 2021-09-08 2021-12-03 中电投新疆能源化工集团五彩湾发电有限责任公司 一种回转式空预器防堵系统

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2947522A (en) * 1955-05-12 1960-08-02 Keller John Donald Recuperators
JPS5934280B2 (ja) * 1977-07-13 1984-08-21 三菱重工業株式会社 空気−ガス熱交換器の自動清浄装置
JPS5495058A (en) * 1978-01-12 1979-07-27 Ishikawajima Harima Heavy Ind Co Ltd Elimination of adhering ammonium salt from air preheater
JPS5843320A (ja) * 1981-09-10 1983-03-14 Babcock Hitachi Kk 脱硝装置
JPS58217199A (ja) * 1982-06-10 1983-12-17 Baanaa Internatl:Kk ロ−タの清浄方法及びその装置

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6183707B1 (en) * 1992-06-08 2001-02-06 Biothermica International Inc. Incineration of waste gases containing contaminant aerosols
FR2790257A1 (fr) * 1999-02-26 2000-09-01 Kvaerner Process France Sa Procede d'elimination de sels, notamment de sulfates et de pyrosulfates d'ammonium
CN106224989A (zh) * 2016-07-22 2016-12-14 河北省电力建设调整试验所 一种在线清除燃煤电厂空预器中硫酸氢铵堵灰的方法
CN106224989B (zh) * 2016-07-22 2018-07-20 河北省电力建设调整试验所 一种在线清除燃煤电厂空预器中硫酸氢铵堵灰的方法
CN109210555A (zh) * 2017-07-03 2019-01-15 大唐保定热电厂 电站锅炉脱硝投运空气预热器在线干烧清堵系统和技术
CN113739190A (zh) * 2021-09-08 2021-12-03 中电投新疆能源化工集团五彩湾发电有限责任公司 一种回转式空预器防堵系统
CN113739190B (zh) * 2021-09-08 2024-05-28 中电投新疆能源化工集团五彩湾发电有限责任公司 一种回转式空预器防堵系统

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EP0197023A3 (fr) 1986-12-30

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