Fiberglass desulfurization equipment is mainly used in the environmental protection system of flue gas desulfurization and denitrification in thermal power plants, and currently wet desulfurization is the main method. Based on the characteristics of this process, our company can provide the following products and equipment:
On the basis of introducing advanced Italian technology, Hebei Fiberglass has proprietary technology in the localization of FRP spray pipes for FGD systems after years of research. It can replace similar imported products and significantly reduce the cost and shorten the construction period of FRP spray pipes, a key equipment in absorption towers, while ensuring product quality. Product specifications: DN10-DN4000, can be designed according to user requirements, pressure: below 4.0Mpa, temperature resistance: below 220 ℃, wear-resistant layer thickness greater than 2.5mm, color: black, green, light yellow, nozzle connection method: flange bonding
|
|
2. FRP slurry transportation pipeline
The fiberglass wear-resistant pipeline produced by Hebei Fiberglass using proprietary technology is an ideal substitute material for steel lined rubber pipelines in the lime slurry transportation pipeline system outside the wet desulfurization tower. (Butyl rubber is prone to aging and peeling, causing corrosion and pipeline blockage)
Compared with steel lined rubber pipes, fiberglass wear-resistant pipes have the following advantages:
(1) Easy to install
Fiberglass has the advantages of lightweight and high strength, with a density only 1/4 of steel. The connection methods include flange connection, socket bonding, etc., which are convenient and fast.
(2) Price advantage
The price of fiberglass wear-resistant pipes of the same specifications is only 75-90% of that of steel lined rubber pipes.
(3) No need for insulation
Fiberglass itself is a poor conductor of heat, with a thermal conductivity coefficient of only 0.48W/m ℃
Performance comparison of various materials
Material project: Fiber wrapped fiberglass reinforced plastic PVC
Thermal expansion coefficient (10-6/℃) 11.2 12.3 60-80
Thermal conductivity coefficient (W/m ℃) 0.48 11 30.21
The pipeline system used for limestone and gypsum slurry outside the tower does not require an external insulation layer, which not only saves project investment but also improves project progress.
(4) Easy maintenance and upkeep
Fiberglass wear-resistant pipes do not require maintenance, are easy to repair, and do not require external anti-corrosion treatment, while steel lined rubber pipes are not only difficult to repair but also require regular external anti-corrosion treatment.
(5) Advantages in lifespan
The service life of fiberglass pipes can reach 20 years.
(6) Product specifications
Diameter DN15-4000mm
Length: 100-12000mm
Pressure: 0-2.4Mpa
Another method is ammonia desulfurization. As it does not cause secondary pollution, the ammonia desulfurization process is gradually being applied. Firstly, the hot flue gas enters the pre washing tower and comes into contact with a saturated ammonium sulfate solution. The flue gas is cooled during this process. At the same time, ammonium sulfate crystals are precipitated due to the evaporation of water in the saturated ammonium sulfate solution.
The cooled flue gas enters the SO2 absorption tower through a defogger. In the absorption tower, ammonia is mixed with water to form ammonia solution. SO2 in the flue gas is absorbed here and reacts with ammonia to produce ammonium sulfate. Finally, the desulfurized flue gas is discharged into the atmosphere through a 120 meter high chimney. The ammonium sulfate solution is sent to the pre washing tower for recycling.
The ammonium sulfate slurry in the pre washing tower enters the dehydration system. First, dehydrate through a hydraulic cyclone, and then obtain ammonium sulfate filter cake through a centrifuge. The clear liquid recovered from the cyclone and centrifuge is returned to the pre scrubber for recycling.
The ammonium sulfate filter cake is sent to the granulation system to obtain high utilization value granular ammonium sulfate fertilizer, which is stored in a dome shaped storage bin capable of accommodating 50000 tons of ammonium sulfate before being transported by train or truck.
3. Our company can design and manufacture flue gas absorption towers (desulfurization towers) according to the technical requirements of users for the diameter and structural type of desulfurization towers. Currently, we have produced a series of desulfurization towers, which are widely used in power plant supporting flue gas and exhaust gas treatment systems. Simultaneously produced the flue gas tower and supporting flue gas ducts and accessories required for ammonia desulfurization.
|
Application of fiberglass in wet flue gas desulfurization equipment
|
Flue gas desulfurization is the main measure for controlling sulfur dioxide emissions in coal-fired power plants today. The wet limestone washing method is currently the most widely used and mature process in various countries around the world. The State Power Corporation has identified wet limestone desulfurization process as the dominant process for flue gas desulfurization in thermal power plants. In 1986, Jizhou Huaxin Glass Steel Plant (formerly Hebei Jizhou Huaxin Glass Steel Plant) introduced equipment and technology from Italy's VETRORESINA company to produce a series of fiberglass products, thereby achieving the goal of significantly reducing the cost of desulfurization equipment.
Material selection for wet flue gas desulfurization process
|
The basic principle of wet desulfurization process is that SO2, SO3, HF or other harmful components in the flue gas meet with water containing certain chemical media at high temperature and undergo chemical reactions, producing dilute sulfuric acid, sulfate or other compounds, and the flue gas temperature also drops below the dew point. This has brought serious dew point corrosion problems to the desulfurization device.
Does flue gas from thermal power plants contain SO2, NOx, HCl, and HF? Waiting for gas. Therefore, does the washing solution of the desulfurization system contain H2SO4, HCl, HF? Wait for the solution, and it contains about 20% of the solidified material. If no flue gas reheating is installed, the inlet flue gas temperature of the absorption tower can reach up to 160-180 ℃, and there is a certain dry and wet interface. The outlet flue gas temperature of the absorption tower is relatively low, around 55 ℃, below the dew point. Therefore, wet desulfurization systems have extremely strict requirements for material corrosion resistance, wear resistance, and temperature resistance. At the same time, the desulfurization system requires synchronous operation with the power plant host and main furnace, therefore, the reliability, utilization rate, and service life of the desulfurization system are also extremely high.
|
The long-term goal of desulfurization workers in various countries is to study and select suitable materials. According to their own fuel quality, environmental requirements, and economic affordability, countries also vary in the selection of materials for desulfurization equipment. The United States mainly uses nickel based alloys or carbon steel with high nickel alloy plates, Germany uses carbon steel lined with rubber and fiberglass, and Japan uses carbon steel coated with glass flake vinyl ester resin.
Domestic and foreign power, chemical, and metallurgical design and research departments have been seeking a low-cost, high-temperature resistant, and corrosion-resistant material to overcome the corrosion of desulfurization towers, flues, chimneys, and liners in wet flue gas desulfurization systems.
Fiberglass reinforced plastic, also known as fiberglass reinforced plastic (FRP or GRP), was used in the production of flue gas desulfurization devices in the early 1970s. In particular, the development of phenolic epoxy vinyl ester resin, experimental research on the unique requirements of flue gas desulfurization, and the emergence of large-diameter fiberglass winding technology have made fiberglass desulfurization devices widely used. Since 1972, glass fiber reinforced plastics made from vinyl ester resin have been successfully applied in many wet desulfurization systems.
The excellent characteristics of fiberglass reinforced plastic
Compared with metal materials or other inorganic materials, fiberglass has significant performance characteristics. It is a new type of material with both functional and structural characteristics, characterized by its light weight, high specific strength, electrical insulation, resistance to instantaneous ultra-high temperatures, slow heat transfer, sound insulation, waterproofing, easy coloring, and ability to transmit electromagnetic waves.
3.1 Corrosion resistance performance
The corrosion resistance of fiberglass mainly depends on the resin. With the continuous advancement of synthesis technology, the performance of resins is also constantly improving, especially with the birth of vinyl ester resins in the 1960s, which further improved the corrosion resistance, physical properties, and heat resistance of fiberglass. In fact, fiberglass reinforced plastic made from vinyl ester resin has been successfully used in more demanding environments than wet desulfurization systems for a long time.
3.2 Heat resistance performance
In the wet desulfurization process, high temperature is a necessary consideration because the temperature range of the mixed gas at the inlet is 160 ℃ to 180 ℃, and the components in the system have to withstand temporary high temperature rapid cooling, potential thermal damage, and the production of highly corrosive by-products, leading people to choose expensive structural materials such as high nickel alloy C-276 to meet the service life requirements.
The thermal shock performance test (by placing two types of fiberglass laminates in a solution above 204 ℃, immediately placing them in cold water and storing them for 2 hours, and then drying the two laminates for 6 hours to determine their bending strength) showed that the fiberglass laminates made of vinyl resin retained the majority of their bending strength, and their high elongation rate gave them excellent impact resistance and a wider range of adaptability to temperature differences, pressure fluctuations, and mechanical vibrations. Fiberglass reinforced plastic made of vinyl ester resin has successfully replaced the chimney lining of wet flue gas desulfurization systems that crack due to thermal and mechanical stress. The desulfurization tower made of vinyl ester resin fiberglass can be used at higher temperatures, has a longer lifespan, and is more reliable.
The long-term use temperature of fiberglass depends on the glass transition temperature (Tg) and heat distortion temperature (HDT) of the resin matrix. The HDT of bisphenol A epoxy vinyl ester resin is higher than 105 ℃, and the HDT of phenolic modified epoxy vinyl ester resin is higher than 145 ℃. Dow in the United States? Chemical Company has developed and produced an FGD washing tower that can be used at a temperature of 220 ℃.
3.3 Wear resistance and corrosion resistance
In corrosive environments, the wear resistance of fiberglass is superior to that of steel. To improve the wear resistance of fiberglass, appropriate fillers can be added to the resin matrix. In 1987, the RWE thermal power plant located in Weisweiler, Germany adopted the lime limestone wet desulfurization process. The solid content in the lime water was about 15%. The washing tower and the pipeline for transporting lime slurry were both made of fiberglass. Due to the addition of fillers in the resin, it has good wear resistance and is still in good use today.
3.4 Price advantage of fiberglass reinforced plastic
Foreign research data shows that the cost of fiberglass is about one-third of the cost of high nickel alloys, depending on the size and type of equipment. The cost of a 4-meter diameter fiberglass absorption tower is only half that of a tower coated with high nickel alloy.
Due to its chemical corrosion resistance and lower cost compared to high nickel alloys, fiberglass has achieved good results in many wet desulfurization system devices. According to foreign data, fiberglass has been successfully applied in the following aspects of wet desulfurization systems:
① Absorption tower body, ② Lime dissolution tank,? ③ Liquid collector, defogger, ④ slurry conveying pipeline? ⑤ Flue, ⑥ Chimney
The forming process of fiberglass reinforced plastic
The horizontal fiber winding process is controlled by a microcomputer, which means that under the control of the microcomputer, the mold rotates around the axis, and the winding head carries glass fibers soaked in resin and moves back and forth along the axis direction of the mold. The speed ratio of the two movements is controlled by the microcomputer, and the number of winding layers is controlled by the microcomputer according to pre input parameters. After the resin solidifies, the product is formed on the surface of the mold.
During the molding process, the mold is parallel to the ground, hence it is called horizontal winding. The maximum diameter can reach 15 meters, solving the problem of uneven distribution of resin using vertical winding method and improving product quality. Compared with the traditional vertical winding process, the advantages of horizontal winding are manifested in the following five aspects:
|
|
Horizontal winding forming process and vertical winding forming process
1. Integrated molding:
The cylinder body is wrapped as a whole (including the upper head), with no structural layer joints. The axial and circumferential forces of the cylinder body are distributed reasonably and evenly. The overall performance of the cylinder body is good, the strength is high, there are no stress concentration areas, and the service life is long.? 1. Assembly and molding:
The cylinder is wound in sections, with each section being less than 5 meters high, and then the sections are connected and manually reinforced. There are reinforcement bands inside and outside the cylinder, forming a stress concentration zone. The manual pasting process is subject to significant human factors and is easily affected by the quality of workers.
2. Uniform resin content:
During the horizontal winding process, the processed equipment is placed horizontally and continuously rotates. Regardless of the resin content, there will be no resin dripping or high or low resin content in each structural layer.? 2. Uneven resin content:
During the processing of vertical winding equipment, the processed equipment is placed vertically, and the liquid resin will continuously drip from top to bottom due to gravity, resulting in uneven resin content in the formed equipment.
3. The rationality of the product's laminated structure.
Our company's equipment inner lining is made of steel molds and sprayed with Venus spray guns, with high resin content, smooth inner surface, and no capillary phenomenon. The structural layer is formed by impregnating the structural resin with alkali free and untwisted glass fiber winding yarn and then winding it in both circumferential and transverse directions. The resin content is 35 ± 5%.? 3. The laminated structure of the product is unreasonable.
Vertical winding is used on site to form each structural layer in one go using wooden molds. The layers between each structural layer are not clearly defined, and the resin content is difficult to control.
4. The upper head has strong load-bearing capacity.
The horizontal winding cylinder and the head are reinforced as a whole, and the winding yarn forms a flower bud like wrapping on the head of the equipment, with emphasis on strengthening each stress concentration area. Is the head capable of withstanding wind, snow, and operational loads? 4. The bearing capacity of the upper head is weak.
The cylinder and head are manufactured and assembled separately before being placed on the foundation. The wind load, snow load, and operational load capacity of the upper head are much smaller than those of the bedroom winding process formed as a whole.
5. Corrosion resistance.
The inner lining layer is made of indoor steel molds and sprayed with Venus spray guns, which are not affected by outdoor environmental temperature, humidity, and sandstorms, ensuring easy quality assurance. The inner lining has a high degree of curing, good mechanical properties, and corrosion resistance.? 5. Corrosion resistance.
The formation of wooden molds on the construction site of the lining is affected by the temperature, humidity, and sandstorms of the site environment. The inner lining is prone to impurities such as sand and dust. After the equipment is put into use, it will react chemically with the medium for a long time, forming pits on the inner surface of the inner lining, which poses a hidden danger for future leakage.
Application of fiberglass reinforced plastic in flue gas desulfurization equipment
1. Application situation abroad
The United States was the first country to apply fiberglass reinforced plastic in the field of flue gas desulfurization, starting in the 1970s. In the 1980s, there was a craze in Europe for manufacturing desulfurization equipment using fiberglass reinforced plastic,? In 1984, the German company BASF decided to adopt the Wellman Lord wet scrubbing tower at its coal-fired power plants located in Ludwigshafen and Marl. Each power plant will build 2 washing towers with a diameter of 9.5 meters and a height of 35.5 meters. At that time, after 18 months of laboratory research (simulating usage environment), it was expected to last for at least 20 years without maintenance.
In November 1987, BASF and Owens from Europe? Corning Fiberglass Company co hosted an experience exchange meeting on fiberglass equipment for desulfurization in London, affirming the role of fiberglass and promoting its application in the field of flue gas desulfurization.
Many companies in the world, such as Monsanto, Bischof, Babcock, BASF, Fiberdur Vanck, ABB? Plastillon and other companies widely use fiberglass to manufacture flue gas ducts, absorption towers, spray pipes, defoggers, slurry pipelines, and wet chimneys for flue gas desulfurization in smelters, paper mills, and waste incinerators. In flue gas desulfurization of thermal power plants, slurry conveying pipelines and defoggers are commonly produced using fiberglass reinforced plastic. In recent years, due to the emergence of large-diameter fiberglass winding technology (container diameters can range from 3.6m to 15m), foreign utility companies have become increasingly interested in the production of fiberglass for the main components of desulfurization systems in thermal power plants, such as absorption towers and oxidation tanks.
In the early 1990s, fiberglass desulfurization equipment was becoming increasingly large-scale, such as Plastillon's plan to manufacture desulfurization absorption towers with a diameter of 20 meters. A 166MW unit in a power plant in Germany is equipped with a limestone slurry absorption tower (without a pre washing tower) manufactured by Plastillon, with a diameter of 10 meters and a height of 34.8 meters. It was put into operation in 1993. The CT-121 jet bubbling bed flue gas desulfurization tower (100MW, without pre washing tower) in the second phase of the US Clean Coal Technology Demonstration Program (CCT -? II) is also made of fiberglass and was put into operation in October 1992, proving that the fiberglass absorption tower is reliable both structurally and chemically.
|
|
