Cleaning scheme of heat exchanger 1 1. Cleaning method (physical cleaning) of hanging ultra-high pressure (500-2800bar) jet heat exchanger (also known as heat exchange heat exchanger)
High pressure water jet cleaning technology for heat exchanger. Ordinary tap water is pressurized to a pressure of 500- 1500bar with a high-pressure pump, and then sprayed out at a very high speed (200-500m/s) with a special nozzle (the aperture is only 1-2 mm). The vibration energy of bundled small water flow is uniform (macro ultrasonic principle), which will not damage the tank wall and can remove salt, alkali, scale and various blockages on the inner wall of the pipeline. Cleaning with this huge energy flow is high-pressure water jet cleaning. Generally, the internal diameter of various shell-and-tube heat exchangers is φ 10-φ50mm, and the length is about 3m, 6m, 9m and 13m. We use rigid spray guns and soft guns with corresponding lengths and various nozzles similar to drill bits to suspend and clean the dirt in the pipe, and then smash it and discharge it out of the pipe with the water flow, thus effectively cleaning the dirt and blockage inside and outside the pipe, and the cleaning effect in all directions reaches 90%.
1) Application conditions:
1, the pipe hole is blocked or semi-blocked, and the structure around or at the bottom of the pipe hole is cleaned. High-pressure hard pipes or hoses with rotating nozzles are sprayed to the periphery for descaling, and the spraying reaction automatically advances for cleaning and descaling;
2. The scaling accessories at the pipe end of the pipeline are sprayed and cleaned by a surface spray gun (rotary nozzle) with a hand-held rotary high-pressure nozzle.
2) Construction conditions
65438+
2. There are no obstacles (within 2M around the tube array) where you are cleaning;
3. Your company provides access (about 3M) for power supply, water source, lighting facilities and operating equipment (high pressure cleaning machine) to the site, as well as ultra-high pressure cleaning device (2.5*5m2 container storage space).
Second, the principle flow (chemical cleaning) of circulating cleaning of oil-gas tube side and shell side of heat exchanger
1. Establish a circulation system in the pipe array;
2. The establishment of external circulation system;
3. Alkaline (food-grade) cleaning agent for oil pollution: mixed according to relevant standards;
4. Try acidic (food-grade) scale cleaning agent: mix according to relevant standards.
Ⅱ. Construction Scheme for Chemical Cleaning of Oil and Gas Side
Design materials, diameters and quantities of effective pipelines on the oil side. During the operation of the heat exchanger, the oil-gas medium on the oil side will form sludge and grease when it flows through the shell metal and tube surface of the heat exchanger, which will lead to the grease gradually depositing on the metal surface and coking, especially in the dead angle area with low flow velocity. This will cause the heat exchange efficiency of the heat exchanger to decrease gradually, which will seriously affect the heat exchange effect of the equipment. In addition, the existence of deposits can also cause corrosion under the scale, and local corrosion is an important factor to make the heat exchanger perforated.
According to the situation of site and oil scale, the circulating chemical cleaning process is selected for the gas side cleaning of heat exchanger, which has the following advantages: (1) the cleaning solution can maintain a certain temperature and concentration; The circulation of cleaning liquid has the functions of stirring, washing and stripping, which is helpful to remove oil stains and oil stains that are difficult to remove.
I. Preparation before chemical cleaning:
1, take the test tube for simulation test, and determine the test formula and cleaning scheme.
2. Clean the pumping station, raw materials, connecting hoses and other equipment and accessories to the site. Install circulating pump and clean temporary pipeline. , and connect them into a complete cleaning system.
3. Take personal protective measures. Such as protective glasses, towels, masks, rubber gloves, acid and alkali resistant work clothes, acid and alkali resistant rubber shoes, etc.
4. Prepare tools such as wrenches, wires, erasers and clamps.
5. Dismantle or effectively isolate all instruments of pre-cleaning equipment and parts not involved in cleaning.
Technical and safety disclosure shall be made to the construction personnel to make them understand the cleaning system, operating procedures, cleaning agent performance and various safety construction measures.
Second, chemical cleaning steps
Water washing-cleaning agent cleaning-water washing-cleaning end-compressor air drying
1, water flushing
(1) Remove dirt, sediment and accumulated water from the dissolving tank, and clean the dissolving tank.
(2) Start the circulating pump with industrial water, inject fresh water into the dissolving tank, the equipment to be cleaned and the whole circulation system, stop adding water, and circulate the valve to the maximum opening (the discharge valve is fully closed) for half an hour, and observe whether there is any leakage in the cleaning system. If there is any leakage, it should be handled in time.
(3) Stop the pump for half an hour, open the drain valve and try to drain the sewage in the system.
(4) Repeat the steps (2) and (3) until there are no obvious impurities in the effluent, and then the next cleaning work can be carried out.
2, cleaning agent cleaning
(1) Add clean water to the dissolving tank, start the circulating pump, and establish circulation in the cleaning system. At the same time, add metered metal corrosion inhibitor and cleaning agent into the dissolving tank, establish circulation, and heat to 50-80℃.
(2) After dosing, analyze the concentration of cleaning solution every 15 minutes to half an hour.
(3) The cleaning time of the medicament needs to be determined according to the oil pollution concentration brought by the effluent, the change of the effective components of the medicament and the flow rate. This time, due to the small diameter of the equipment inlet and outlet, the cleaning time takes about 2 ~ 5 hours. Observe the change of water quality in circulating cleaning and consider whether to extend the cleaning time or carry out secondary cleaning.
3, washing
(1) Drain the cleaning solution, add clean water to the dissolving tank for washing, and start the circulating pump to fill the whole system with clean water until there is no obvious dirt in the water.
(2) Then, when the PH value is around 7 while replenishing water, open the drain valve to drain the water in the equipment as much as possible, and the cleaning is over.
4, compressor air drying
(1) Remove and clean the connecting pipe fittings and connect compressed air.
(2) Open the drain valve of the oil cooler, and repeatedly blow dry the inside of the equipment with compressed air.
Third, waste liquid treatment
Cleaning waste liquid shall be treated in strict accordance with Party A's requirements, and then placed in the designated place.
Fourth, the construction matters needing attention
1. Construction personnel must wear labor protection articles according to regulations when entering the site, and they need to wear rubber shoes, rubber gloves, masks and goggles.
2, the construction site should have good ventilation, operation site should have convenient and sufficient water.
3. When handling corrosive drugs, it is forbidden to splash on eyes, mouth and skin. In case of accidental contact, flush with plenty of water immediately. In severe cases, seek medical attention immediately according to strong acid and alkali burns.
4. Construction drugs should be stored in a cool and ventilated place, marked "Do not move dangerous goods" and sealed for long-term storage.
Heat exchanger cleaning scheme Part II I. Basis for compiling this scheme:
1. People's Republic of China (PRC) national industry standard: HT/T2387-92 quality standard for chemical cleaning of industrial equipment.
2. People's Republic of China (PRC) and China Chemical Industry Chemical Cleaning Quality Assurance Manual.
3. People's Republic of China (PRC) Industry Standard and HGJ202-82 Code for Construction Acceptance of Degreasing Engineering by Ministry of Chemical Industry.
4. sinopec group cooling water analysis and test method.
5. The importance and necessity of cleaning the circulating water system of central air conditioning.
6. Pipeline cleaning scheme of central air conditioning circulating water system.
7. Air conditioners are mainly made of carbon steel plates and their alloys and galvanized pipes.
8. Analysis of scaling causes of heat exchanger of central air conditioner.
Second, the scale sample analysis results:
Mixture of Fe3O4 and Fe2O3, carbonate scale, grease prevention, partial sludge, silt and other impurities, garbage deposits, biological mucus and algae matrix.
Three. Overview of system status
Long-term operation of central air conditioning leads to rust, scaling and corrosion on the inner wall of the plate road of chilled water exchanger system; Lead to aging and damage of the board road; Especially after the inner wall of the fan coil copper tube rusts and scales, it circulates to the wall of the heat exchange plate; This leads to the decrease of water flow, heat exchange efficiency, poor refrigeration effect and increased energy consumption.
Fourth, the purpose of chemical cleaning
The chemical agent reacts with the dirt on the inner surface of the equipment to make it loose, peel off and dissolve, so as to achieve the purpose of removing the dirt, and passivation/prefilming treatment is carried out to make the system have a clean and good working environment. Eliminate the hidden danger of safe operation of air conditioning chilled water system and ensure the long-term low-cost and efficient use of equipment.
Verb (abbreviation of verb) The scope and methods of cleaning.
1. Object: cold water plate heat exchanger system.
2. Methods: Periodic constant-speed cyclic chemical cleaning method.
Six, the preparation work before chemical cleaning
1. Users help us to be more familiar with the system.
2. Before chemical cleaning, complete the qualitative and quantitative analysis of various corrosion products and scales cleaned in the system.
3. Before chemical cleaning, complete the material determination of each equipment in the system.
4. Separate the equipment and machines unrelated to cleaning from the cleaning system by adding temporary short pipes and connecting temporary bypass or blind plates.
5. In order to ensure a good cleaning process and prevent the occurrence of air resistance, the circulation system should be equipped with and confirmed with high-point exhaust holes and low-point sewage outlets.
6, in order to ensure a good cleaning process, fast and effective water supply and sewage work, temporary water supply pipeline and sewage pipeline can be configured.
Seven, chemical cleaning steps
The whole chemical cleaning process is as follows:
Hydraulic flushing (pressure test and leak detection) → sterilization cleaning → degreasing and oil removal → winding cleaning (after decontamination) → passivation/prefilming → manual treatment → reset inspection → normal operation → chemical cleaning summary.
(Note: This cleaning method abandons the practice of acid+corrosive agent in traditional industrial cleaning, and removes rust and structure. Because of its strong corrosiveness, pickling method not only has a good descaling and cleaning effect, but also causes serious corrosion to the metal matrix itself, leading to the fission of thin tubes, leaving serious hidden dangers for the operation of equipment. All-organic complex cleaning method adopts organic molecular polymer, which is highly selective to metal ions and only reacts with metal ions to generate metal complexes with high solubility, thus promoting the dissolution of rust and scale without any damage to the matrix. )
1, water flushing (pressure test, leak detection)
The purpose of water washing is to wash off the loose dirt such as dust, sediment and metal corrosion products in the system as much as possible with a large amount of water, and at the same time check whether there is leakage, air resistance and dead angle in the system, and handle the problems in time if found. When washing, irrigate at a high point and discharge in different places to control the balance of water inflow and outflow.
The speed of washing water is about 1.0m/s, and the turbidity difference between inlet and outlet water is less than 5ppm. When the turbidity curve tends to be flat, washing is over.
2, sterilization and algae cleaning
The purpose of sterilization and algae removal cleaning is to kill microorganisms in the system and peel off biological slime attached to the surface.
After all the washing liquid is discharged, fill the system with water, and then add an appropriate amount of bactericide and algaecide for circular cleaning. When the concentration in the system reaches equilibrium, it can be completed.
3, degreasing cleaning (if there is no or a small amount of grease, this step can be omitted)
The purpose of degreasing is to remove organic polymer compounds such as antirust oil and grease from the system, so that the active components in the complexing process can contact with the inner wall of the cleaning object more evenly and thoroughly, thus promoting
Dissolution of metal oxides such as rust and copper rust.
When cleaning, the flow rate of degreasing liquid should not be less than 0.6m/s, and the curves of alkalinity, oil content and temperature of degreasing liquid tend to be flat, so degreasing can be finished.
4, complex cleaning
The purpose of complex cleaning is to make use of the high selectivity of some polymers to metal ions, and only react with metal ions to generate metal complexes with high solubility, so as to promote the dissolution of metal oxides and salt scales such as rust and patina without any damage to the metal matrix. When cleaning, the flow rate of cleaning liquid should not be less than 0.6m/s, and attention should be paid to high-point exhaust and blowdown, and low-point blowdown to prevent gas resistance and damping from affecting the cleaning effect.
Reagents: Luo cleaning agent, corrosion inhibitor, accelerator, wetting agent, penetrant and reducing agent.
5. Rinse with water after cleaning
The purpose of this flushing is to remove residual washing liquid and solid particles falling off the system, so as to remove impurities and residual liquid deposited in the short pipe.
6. Passivation/prefilming treatment
Passivation/pre-film treatment purpose-After cleaning, the metal surfaces of equipment and pipelines are in a highly active state, which is easy to recombine with oxygen and be oxidized and rusted. The function of passivation/prefilming treatment is to form a passivation/prefilming layer on the metal surface, which can inhibit the dissolution rate of the metal anode from keeping a small value, and then this surface film becomes passivation/prefilming. A complete passivation film is formed on the metal surface to achieve the purpose of rust prevention and corrosion protection. Therefore, equipment and pipelines need to be passivated/prefilmed after cleaning, and then put into use or sealed.
Additives: passivator, prefilming agent.
7. Manual cleaning and inspection
In the process of cleaning the system, there may be various insoluble solid impurities, such as stones, mud and sand, deposited on the filter and the lower elbow, so this dirt deposit will be cleaned by machinery and manpower.
8. Acceptance after chemical cleaning
(1). The acceptance team composed of Party A and Party B is the same as the acceptance.
(2). Write comments on the cleaning acceptance form, and the representatives of both parties will sign it, and the acceptance will be over.
9, reset check
After the inspection, remove or isolate the temporary system and temporary blind plate, and reset the air conditioning system to normal state for debugging.
Eight, after chemical cleaning should meet the quality standards (chemical cleaning quality requirements)
The rust removal rate is more than 98%, the scale removal rate is more than 98%, the corrosion rate of carbonic acid is less than 0.5g/ml (far better than the national standard 6g/ml), and the corrosion rate of copper is less than 0.2g/ml (far better than the national standard 2g/l), forming a complete and compact passive film.
Nine. Chemical cleaning waste liquid treatment
After neutralization (PH=6~9), it will be discharged to the sewage treatment plant designated by Party A (Party A is responsible).
Since the heat exchanger of our company was put into operation, due to various reasons, the scaling and corrosion in the heat exchanger seriously exceeded the specified range, and the deposits in the equipment were serious. The exchange effect is extremely poor, which causes hidden dangers to the safe operation of equipment. In order to improve the work efficiency and ensure the normal operation of the equipment, with the approval of the company leaders, the tube side and shell side systems of the crude benzene condensation cooler in the first phase of the professional chemical production branch were thoroughly cleaned. In order to ensure that the cleaning and maintenance can complete the maintenance task with good quality and quantity in the shortest time under the premise of safety, this construction scheme is specially formulated:
First, the construction time:
1. After the preparation is completed, the cleaning time of the heat exchanger is 1 day.
2. Construction time: May 2, 20XX1.
Second, the organization:
1, Chief Commander: Shi
Responsible for the examination and approval of the construction plan.
2. Deputy Commander: Li
Responsible for the audit of the construction plan and the coordination and command in the construction process.
3. Person in charge of construction: Li Xiaochun and Gong Hongyu.
Responsible for the formulation of the general construction plan and the organization and coordination of personnel in the construction process; Supervision and inspection in the construction process; Organize relevant personnel to carry out project acceptance and handover.
4. Person in charge of construction site: Li Shengwang Gao Dayong.
Responsible for the supervision and inspection in the project construction; Acceptance and handover of the project.
5. Person in charge of quality supervision and inspection: Yang Zhicheng Shen Laishuan.
Responsible for the quality supervision and inspection of the construction process and the confirmation and acceptance of each process.
6. Chief Safety Officer: Wu Hengguang
Responsible for the safety work in the construction process.
7. Person in charge of site safety: Song Jianwei Ren Jianwei.
Responsible for the site safety of construction projects.
8. Chief Process Manager: Li Chunming.
Coordinate the process adjustment during maintenance.
9. Person in charge of on-site process: Cao Zhucai, Dingding.
Responsible for making process start-up and shutdown plan; Coordinate the process adjustment in the maintenance process; Establish acceptance criteria for the process; Participate in the acceptance work.
10, workshop leader: Wu Hengjie (crude benzene)
Responsible for the safety, quality and process control of the construction area.
Party B:
1. General Manager of the construction unit: Tianjiang Bridge
2. Person in charge of the construction unit: Liang Yugang, Hu Zhanping.
3. Safety supervisor of the construction unit: Miao Jianguo
4. Construction personnel: Tian Jin, Wu Dawei and Jia.
Third, the preparation work before cleaning:
1, get in touch with the factory, arrange the order of equipment cleaning and shutdown, go through the relevant construction procedures stipulated by the factory in advance, and ensure the water, electricity and other supporting facilities and auxiliary materials needed for construction.
2. With the assistance of the manufacturer, a pumping station will be established and temporary pipeline cleaning will be provided. Loose valves will be blocked by clapboards, and cleaning pumps and other rotating machinery will operate normally. Check them carefully and clean them.
3. Conditions that the constructor should meet: cleaning equipment, tools, raw materials, anti-corrosion specimens, chemical analysis instruments, communication tools and labor protection articles.
Four, chemical cleaning process and analysis and monitoring:
1, according to the field investigation, take the scale test. This cleaning refers to the chemical cleaning process of industrial equipment of Bluestar Chemical Cleaning Company and adopts the cleaning process of similar equipment of our company. (blue star series cleaning agents are added for cleaning in a large period. In order to prevent the corrosion of equipment and pipelines, a specified amount of LAN-826 patented products and other additives are added during cleaning. Such as stabilizers, penetrants, reducing agents, etc. ).
2. Monitoring: When the cleaning solution is injected into the equipment, the on-site analytical chemist should hang the corrosion test piece with the same material as the system in the liquid preparation tank, observe it at any time, test it regularly, and make original records.
Test items: hanging inspection 1 time /30 points.
Liquid inspection 1 time /30 points
Temperature 1 time/60min
Cleaning end point: it ends when the concentration no longer drops (within one hour).
3. Neutralization flushing: Neutralization flushing is mainly to make the residual liquid in the system react for the second time. Make the PH value of the liquid close to neutrality, and lay a good foundation for discharge.
Verb (abbreviation of verb) Treatment and discharge of cleaning waste liquid:
After treatment, the waste liquid reaches GB8978-88 "Industrial Three Wastes Discharge Standard" and is discharged to the designated place.
Six, chemical cleaning quality and acceptance:
1, and the recovery process requires more than 95%.
2. There is no corrosion or washing. The average corrosion rate of corroded specimens is less than 10g/m2H, which meets the cleaning quality standard of industrial equipment. Party A and Party B shall participate in the acceptance at the same time and issue a completion acceptance form.
Seven, safety measures:
1, the safety and environmental protection department shall organize the construction personnel to carry out factory-level safety education and abide by the company's various safety systems.
2. When entering the site, the labor protection articles must be dressed neatly, and it is forbidden to work after drinking. It is forbidden to sleep and play in the construction site, and do a good job in civilized construction.
3. Prepare fire extinguishers on site, ready to eliminate fire hazards at any time.
4. The relevant procedures must be handled one day in advance for the hot work and temporary electricity use of this device.
5, the construction area to do a good job of safety isolation, and make clear signs, irrelevant personnel are strictly prohibited from entering the construction site. Construction personnel are not allowed to walk around the factory, and construction is only allowed in a fixed construction area.
6, the construction site equipped with towels, soap, gloves and other items, to avoid harm to the operator.
7, aerial work safety:
7. 1, wear flexible clothes for aerial work, fasten your seat belt and hang it in a safe and secure place.
7.2. The materials used for aerial work should be stacked in a balanced way, and the tools should be put into the tool bag conveniently. It is forbidden to throw objects up and down, and measures should be taken to prevent falling objects.
7.3, aerial work wrench should use rigid hand, such as using live newspaper hand, tied up with a rope.
8. Party A and Party B shall not have disputes. If there are any objections, they shall contact the superior leaders in time to solve them.
9. Oxygen cylinders and acetylene cylinders on the construction site should be placed separately, with a distance of more than 5m.
10, all kinds of electrical equipment must have good insulation and grounding, and cables are not allowed to be damaged or connected.
1 1. Construction personnel are required to strictly implement the process handover system to ensure quality step by step.
12. The construction personnel are required to deal with the quality problems existing in the construction, and must rework until they are qualified.
13. Construction personnel are required to make technical disclosure before construction.
14. It is forbidden for construction personnel to switch the valves and switches of the current operating system without permission.
15. There shall be no sundries on each platform, and they shall be cleaned up in time after work every day.
16. Party B shall be responsible for any accident during the on-site work.
Eight. List of clean heat exchangers
Phase I crude benzene: a condensing cooler.
Cleaning scheme of heat exchanger Chapter 4 (1) Cleaning scheme The scheme of high-pressure water jet cleaning heat exchanger equipment should be based on the principles of practicality, safety and environmental protection. At the same time, it should be considered comprehensively according to the project budget, technical strength and hydropower situation on the job site.
① The cleaning equipment is equipped with a tubular heat exchanger. The high-pressure water jet cleaning system consists of a high-pressure pump, a high-pressure hose, a pedal valve soft gun spray bar, a rigid spray bar and a nozzle. According to the cleaning needs, determine the driving mode and working parameters of the high-pressure pump. According to the structural form, installation size, size specification and fouling state of the heat exchanger, the corresponding nozzle and actuator are selected.
② Determination of cleaning process Heat exchanger cleaning mainly refers to tube side cleaning and shell side cleaning. According to the structural state, select the appropriate high-pressure water generator. For hard dirt, high pressure and small flow rate are adopted, and for parts with light scale, such as fins outside air coolers, low pressure and large flow rate can be selected; Generally, medium pressure and flow rate are used for cleaning.
When cleaning the pipeline completely blocked by hard dirt, the nozzle with front opening and rigid nozzle should be selected. For pipelines that are completely blocked or blocked by loose dirt, it is advisable to use flexible spray bars with nozzles that open forward and backward at the same time.
According to the structure and scaling of heat exchanger, shimmy jet, abrasive jet and shovel jet can achieve twice the result with half the effort. At present, the cleaning width of shovel jet can reach 600-1000 mm.
The surface of the top cover and tubesheet of the heat exchanger can be cleaned by hand-held spray gun. If the centralized spray bar is used, the cleaning effect is better.
(3) Safety measures for cleaning operation On the premise that the high-pressure water generator is in good condition, the accessories of the cleaning system must be complete and reliable, and the actuator is flexible and effective. The heat exchanger to be cleaned should be completely disconnected from the process system. The working medium in the heat exchanger must be cleaned whether the equipment is cleaned on site or hoisted on site, and there must be no residue that may cause combustion and explosion or release harmful gases and dirt when it meets water.
The cleaning project must comply with the Safety Specification for High Pressure Water Jet Cleaning Operation. The work site must be equipped with warning signs and guardrails to keep an effective safe distance. Operators should wear protective clothing.
④ The assessment of the cleaning quality of courseware parts, such as the cover, tubesheet, nozzle and the outer surface of heat exchanger, is usually made by direct inspection.