CN111536826A - Disassembly-free green cleaning process for rotary air preheater - Google Patents
Disassembly-free green cleaning process for rotary air preheater Download PDFInfo
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- CN111536826A CN111536826A CN202010422965.5A CN202010422965A CN111536826A CN 111536826 A CN111536826 A CN 111536826A CN 202010422965 A CN202010422965 A CN 202010422965A CN 111536826 A CN111536826 A CN 111536826A
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- air preheater
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- disassembly
- heat exchange
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- 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
- F28G9/00—Cleaning by flushing or washing, e.g. with chemical solvents
-
- 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
- F28G15/00—Details
- F28G15/003—Control arrangements
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Cleaning By Liquid Or Steam (AREA)
Abstract
The invention relates to a disassembly-free green cleaning process of a rotary air preheater. Comprises the following steps that (1) a spraying device is used for spraying weakly alkaline medicament into the interior from the upper part of a hot end element in an atomizing way, and the gravity of the medicament is used for infiltrating the surface of ash dirt; (2) after the current sector is soaked, the soaking operation of the next sector is carried out until the heat exchange elements of all the sectors are completely soaked; (3) flushing the heat exchange elements of each sector one by one from the upper part of the hot end element by adopting a flushing device; (4) the heat exchange elements of each sector are flushed one by one with pressurized water from the lower part of the cold end element using a hydraulic jet device. Compared with the existing cleaning process, the disassembly-free green cleaning process for the rotary air preheater has the characteristics of high descaling rate, short construction period and cleaning operation, is environment-friendly, does not cause the problem of environmental protection, saves time and labor for cleaning operation, and has small influence on production activities.
Description
Technical Field
The invention belongs to the technical field of industrial equipment cleaning, and particularly relates to a disassembly-free green cleaning process for a rotary air preheater.
Background
Coal still accounts for the most major part in the energy structure of China at present, wherein the annual coal consumption of coal-fired power generation is about 20 hundred million tons. The rotary air preheater of a large coal-fired boiler arrangement is a regenerative heat exchanger that operates in a counter-current manner. When the flue gas flows through the rotor, the flue gas releases heat to the heat storage element, and the temperature of the flue gas is reduced; when the heat storage element is rotated to the air side, heat is released again to the air, and the air temperature rises. The circulation is repeated in this way, and the heat exchange between the smoke and the air is realized. In recent years, along with the large-area popularization and implementation of boiler flue gas denitration, and other reasons such as flow field and control, the blockage problem of the heat storage element of the air preheater exists in nearly 50% of coal-fired boilers. After the blockage occurs, the exhaust gas temperature of the boiler rises, the smoke and wind resistance is increased, the energy consumption is increased and other adverse situations are caused. Because the clearance of the heat accumulation sheets (or pipes) of the air preheater is small, the ash and dirt are condensed together and firmly adhered to the heated surface, and the most conventional high-pressure water washing method is usually little in effect. The safe and economic operation of the coal-fired power generating unit can be influenced when the blockage problem is serious.
Aiming at the problem of pollution and blockage of the air preheater, the engineering mainly uses physical high-pressure (more than 10MPa) water washing, and is specifically divided into physical washing and hoisting bag disassembly washing. The above method has the following disadvantages: firstly, constructors need to enter the equipment and wash the equipment by using high-pressure water equipment, and because the heat storage plate is similar to a corrugated plate structure in form, the acting force of some positions cannot be achieved, so that the cleaning effect is poor; secondly, will hang out the heat accumulation module with hundreds of thousands of pieces, hundreds of thousands of tons of from equipment earlier and transport to the washing place, then carry out the disintegration and wash, lead to that the cleaning operation is wasted time and energy, influence normal production process.
The Chinese invention patent specification with the publication number of CN110360870A discloses a cleaning method of a rotary air preheater, which comprises the steps of preparing sulfamic acid aqueous solution and spraying sulfamic acid aqueous solution to a heat storage element of an air preheater from top to bottom, washing the heat storage element with water, preparing NaOH aqueous solution and spraying NaOH aqueous solution to the heat storage element of the air preheater from top to bottom, and washing the heat storage element with high pressure. The cleaning method adopts acid liquor and alkali liquor to dissolve the ash scale in the air preheater, and the ash scale is washed after dissolution to remove the ash scale. In the method, the sulfamic acid aqueous solution and the NaOH aqueous solution are acidic solution and alkaline solution which are not friendly to the environment, so that the waste liquid generated in the cleaning process can pollute the environment, the cost of the cleaning process is increased when the waste liquid is treated, and the burden is brought to the operation of enterprises.
Therefore, it is necessary to develop and design a green and environment-friendly cleaning process, which avoids the generation of wastewater and is environment-friendly. The effective cleaning of the air preheater equipment is a necessary means for recovering the production capacity of the equipment and ensuring continuous high-load operation of production, can effectively prolong the service life of the equipment, is beneficial to energy conservation and consumption reduction, and is an effective way for reducing safety accidents.
Disclosure of Invention
The invention provides a disassembly-free green cleaning process of a rotary air preheater, which aims to solve the technical problems in the prior art, has the advantages of high cleaning efficiency, improved cleaning effect, low energy consumption and no environmental protection problem.
The technical scheme adopted by the invention for solving the technical problems in the prior art is as follows: a disassembly-free green cleaning process of a rotary air preheater comprises the following steps of (1) atomizing and spraying a weakly alkaline medicament into the rotary air preheater from the upper part of a hot end element by using a spraying device, and infiltrating the surface of ash dirt by depending on the gravity of the medicament; (2) after the current sector is soaked, the soaking operation of the next sector is carried out until the heat exchange elements of all the sectors are completely soaked; (3) flushing the heat exchange elements of each sector one by one from the upper part of the hot end element by adopting a flushing device; (4) the heat exchange elements of each sector are flushed one by one with pressurized water from the lower part of the cold end element using a hydraulic jet device.
The invention has the advantages and positive effects that: compared with the existing cleaning process (high-pressure water washing or bale breaking cleaning), the disassembly-free green cleaning process for the rotary air preheater has the characteristics of high descaling rate, short construction period and clean operation. By adopting a weakly alkaline medicament, the acidity of the hydrolyzed ammonium bisulfate in the ash scale can be neutralized. Therefore, the supernatant fluid of the mortar generated in the cleaning process is neutral after slag-water separation, and the mortar is environment-friendly and does not cause the problem of environmental protection. Therefore, the waste liquid does not need to be subjected to advanced treatment before being discharged, the cost of the cleaning process is reduced, and the burden of enterprises is reduced. This green cleaning technology is the cleaning technology that the equipment exempted from to tear open, need not to disassemble air heater equipment in the cleaning process, sprays the facility through the hot junction component and the cold junction component of equipment and adopt supporting medicament atomizing to carry out the spraying and forward, the back flush operation of medicament on to heat transfer element, consequently washs operation labour saving and time saving, and is less to the influence of production activity.
Preferably: the method also comprises the step of pre-cleaning the air preheater before the step (1).
Preferably: and (2) before the step (1), a step of additionally installing a spraying device is also included, and after the spraying device is additionally installed, a water spraying test is carried out and the atomization effect is checked.
Preferably: the pH value of the alkalescent medicament in the step (1) is 7-9.
Preferably: and (3) after the heat exchange elements of one sector are soaked in the step (2), manually turning the air preheater to rotate, adding the chemicals and controlling the dosage of the chemicals according to the ash scale test and the small test condition.
Preferably: in the step (3), the soaking time of the heat exchange elements of each sector before flushing is more than or equal to 60 min.
Preferably: the flushing water pressure in the step (4) is 20-50 MPa.
Detailed Description
In order to further understand the contents, features and effects of the present invention, the following embodiments are described in detail.
The disassembly-free green cleaning process of the rotary air preheater disclosed by the invention adopts a mode of 'medicament infiltration + physical washing' to clean ash and scale, and specifically comprises the following steps of:
(1) spraying alkalescent medicament into the interior from the upper part of the hot end element by using a spraying device, and infiltrating the surface of the ash dirt by depending on the gravity of the medicament;
before the step, the air preheater which is shut down is cleaned, the cleaning mode can be a steam soot blowing mode or a sound wave soot blowing mode, and floating soot on a heat exchange element in the air preheater is exposed to hard soot on the inner side through cleaning operation.
Before the step, a spraying device is added, wherein the spraying device consists of a dosing device and a spraying device, and the spraying device is arranged above a moving path of a heating element of the rotary air preheater; after the spraying device is additionally arranged, a water spraying test is carried out, the atomization effect is checked, and the medicament is sprayed out from the spraying device in a fully atomized manner, so that the atomized medicament can be diffused on the surface of the heating element fully, and the medicament is prevented from flowing down rapidly from the surface of the heat exchange element in a strand manner (finally dripping from the bottom to cause the waste of the medicament).
The spraying device sprays the alkalescent medicament onto the surface of the heating element in an atomizing manner, the medicament flows downwards along the surface under the action of self gravity after being converged on the surface of the heating element, and finally the effect of infiltrating the whole surface of the heating element is achieved.
In the embodiment, the selected weakly alkaline medicament is prepared by compounding a chelating agent, a high-efficiency dispersing agent, a pH regulator and water, the pH value of the medicament is 7-9, preferably 8, and part of ammonium bisulfate contained in the ash scale is hydrolyzed into weak acidity, so that the cleaning waste liquid formed after acid-base neutralization is approximately neutral and is environment-friendly.
(2) After the current sector is soaked, the soaking operation of the next sector is carried out until the heat exchange elements of all the sectors are completely soaked;
before the step, the adhesion condition of the ash and scale on the heat exchange element is tested to obtain the thickness, components and other information of the ash and scale; the spraying device is adopted to carry out small-scale cleaning operation on the local part of the heat exchange element so as to obtain the reaction condition between the medicament and the ash and scale and further obtain the information of the medicament quantity required by the ash and scale in unit area, so that the using quantity of the alkalescent medicament required by the heat exchange element in a single sector can be determined according to the area to be cleaned (the area to be cleaned reflects the total quantity of the ash and scale).
In this step, after each sector of heat exchange elements is soaked, the air preheater is rotated to the next sector by the manual jigger and the chemicals are added simultaneously, and the dosage of the chemicals is controlled according to the information obtained by the dust and scale assay and the lab scale.
Whether the heat exchange elements of the sector are fully immersed is determined in the following way: a significant change in the appearance of the scale can be seen when fully wetted, looking up from the lower portion of the cold end element of the air preheater.
(3) Flushing the heat exchange elements of each sector one by one from the upper part of the hot end element by adopting a flushing device;
after the soaking program of the heat exchange elements of all the sectors is completed, starting from the first sector spraying the medicine, the heat exchange elements of all the sectors are washed one by adopting a washing device, and ash and dirt which become loose after the medicine is soaked are washed. And when the washing of the heat exchange element of one sector is finished, the manual barring rotates the air preheater to the next sector, and the washing operation of the next sector is repeated until the washing operation of all the sectors is finished.
In this step, the soaking time of the heat exchange elements in each sector before flushing should be greater than or equal to 60min to ensure sufficient soaking, i.e. to ensure sufficient reaction between the ash and the reagent.
In this step, the above-mentioned forward flushing (from hot end to cold end) can be performed with fire-fighting water in the plant.
(4) Reversely flushing the heat exchange elements of each sector one by using pressure water from the lower part of the cold end element by using a hydraulic jet device;
the water source of washing is pressurized by the hydraulic jet device and then sprayed out to the heat exchange element, under the action of water pressure, the wetting agent becomes loose and the ash and dirt subjected to forward washing effect falls off at an accelerated speed, and in the embodiment, the washing water pressure is 20-50 MPa, preferably 30 MPa.
The reverse flushing in the step refers to a flushing mode from a cold end to a hot end, and when the flushing of the heat exchange element of one sector is finished, the manual barring rotates the air preheater to the next sector to repeatedly perform the flushing operation of the next sector until the flushing operation of all the sectors is finished.
(5) The cleaning work of the air preheater is finished, after the air preheater equipment is dried, the light transmittance and the descaling rate are detected according to the equipment use specification, and the cleaning effect is confirmed.
The main mechanism of the green cleaning process is explained as follows:
although the scale attached to the surface of the heat exchange element (heat storage plate/heat storage pipe) is hard, the scale is not very dense. The reason is that a large amount of fly ash is adhered to the ammonium bisulfate in the process of changing the ammonium bisulfate in the flue gas from liquid state to solid state, and the fly ash has larger surface area and porosity and larger moisture absorption amount;
the process utilizes the characteristic of hygroscopicity, changes the arrangement mode of ash scale molecules under the action of hydrogen bonds and molecular force through the permeation, dispersion and chelation after the infiltration of the alkalescent medicament, changes hard ash scale into loose ash slag which can flow along with water, and then carries out forward and backward washing. At this time, the dust flows in the form of slurry, and the original dust can be peeled off from the surface of the heat exchange element (heat storage plate/heat storage tube), and the slurry is separately collected and subjected to slag-water separation treatment. Because the alkalescent medicament and the ammonium bisulfate ash in the ash scale have neutralization, the cleaning waste liquid is neutral and can be discharged up to the standard without advanced treatment.
Claims (7)
1. The disassembly-free green cleaning process of the rotary air preheater is characterized by comprising the following steps of: comprises the following steps of (a) carrying out,
(1) spraying alkalescent medicament into the interior from the upper part of the hot end element by using a spraying device, and infiltrating the surface of the ash dirt by depending on the gravity of the medicament;
(2) after the current sector is soaked, the soaking operation of the next sector is carried out until the heat exchange elements of all the sectors are completely soaked;
(3) flushing the heat exchange elements of each sector one by one from the upper part of the hot end element by adopting a flushing device;
(4) the heat exchange elements of each sector are flushed one by one with pressurized water from the lower part of the cold end element using a hydraulic jet device.
2. The disassembly-free green cleaning process for the rotary air preheater as claimed in claim 1, wherein: the method also comprises the step of pre-cleaning the air preheater before the step (1).
3. The disassembly-free green cleaning process for the rotary air preheater as claimed in claim 2, wherein: and (2) before the step (1), a step of additionally installing a spraying device is also included, and after the spraying device is additionally installed, a water spraying test is carried out and the atomization effect is checked.
4. The disassembly-free green cleaning process for the rotary air preheater as claimed in claim 3, wherein: the pH value of the alkalescent medicament in the step (1) is 7-9.
5. The disassembly-free green cleaning process for the rotary air preheater as claimed in claim 4, wherein: and (3) after the heat exchange elements of one sector are soaked in the step (2), manually turning the air preheater to rotate, adding the chemicals and controlling the dosage of the chemicals according to the ash scale test and the small test condition.
6. The disassembly-free green cleaning process for the rotary air preheater as claimed in claim 5, wherein: in the step (3), the soaking time of the heat exchange elements of each sector before flushing is more than or equal to 60 min.
7. The disassembly-free green cleaning process for the rotary air preheater as claimed in claim 6, wherein: the flushing water pressure in the step (4) is 20-50 MPa.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010422965.5A CN111536826A (en) | 2020-05-19 | 2020-05-19 | Disassembly-free green cleaning process for rotary air preheater |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010422965.5A CN111536826A (en) | 2020-05-19 | 2020-05-19 | Disassembly-free green cleaning process for rotary air preheater |
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| CN111536826A true CN111536826A (en) | 2020-08-14 |
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| CN202010422965.5A Pending CN111536826A (en) | 2020-05-19 | 2020-05-19 | Disassembly-free green cleaning process for rotary air preheater |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112923392A (en) * | 2021-03-19 | 2021-06-08 | 苏州西热节能环保技术有限公司 | Method for removing hardened ash scale of boiler air preheater |
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2020
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Patent Citations (8)
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| US20110005706A1 (en) * | 2009-07-08 | 2011-01-13 | Breen Energy Solutions | Method for Online Cleaning of Air Preheaters |
| CN201622014U (en) * | 2010-03-24 | 2010-11-03 | 莫大科 | Cleaning device of rotary air heat exchanger |
| CN204593415U (en) * | 2014-12-10 | 2015-08-26 | 中国能源建设集团江苏省电力建设第一工程有限公司 | The online alkali lye flusher of air preheater |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112923392A (en) * | 2021-03-19 | 2021-06-08 | 苏州西热节能环保技术有限公司 | Method for removing hardened ash scale of boiler air preheater |
| CN112923392B (en) * | 2021-03-19 | 2022-05-17 | 苏州西热节能环保技术有限公司 | Method for removing hardened ash scale of boiler air preheater |
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Application publication date: 20200814 |