Biomass boiler is a kind of boiler. The boiler that uses biomass energy as fuel is called biomass boiler. It is divided into biomass steam boiler, biomass hot water boiler, biomass hot blast stove, biomass heat transfer oil furnace, vertical type. Biomass boilers, horizontal biomass boilers, etc.
Biomass boiler features
1) Features of BMF boiler
The boiler uses a combustion equipment that is most suitable for biomass fuel combustion---reciprocating grate.
In the structural design of the boiler, the space of the furnace is larger than that of the traditional boiler, and the second air is arranged at a reasonable level, which is beneficial to the full combustion of a large amount of volatiles which are instantaneously precipitated during the combustion of the biomass fuel.
The control system adopts high brightness and full Chinese display, with the famous brand PLC control system as the central control unit; exchanges information with the boiler user in the man-machine dialogue mode to realize the automatic safe and reliable operation of the biomass pellet boiler.
The boiler can be equipped with a fuel (gas) ignition burner for automatic ignition.
Boiler feeding, burning, slag removal, water supply, ignition can be automatically controlled, and the operation is very convenient.
The boiler is equipped with an automatic cleaning device, which can remove the ash from the heating surface of the boiler in time to ensure efficient and stable operation of the boiler.
An economizer is arranged at the tail of the boiler, and an air preheater can also be arranged according to the needs of the user.
Compared with traditional boilers, boilers are more efficient and have a lower exhaust gas temperature.
With high-efficiency insulation materials, the boiler surface temperature is low and the heat loss is negligible.
Produced in strict accordance with Chinese national norms and standards, all pressure parts are made of high quality boiler steel.
Each boiler undergoes rigorous inspection and testing before it leaves the factory, including hydrostatic testing and X-ray testing.
It is very convenient to set up manholes, check doors, fire holes, etc.
The biggest features of biomass boilers are: energy saving, environmental protection, and easy installation and use.
2) Fuel supply
The fuel of the boiler is BMF fuel, and the fuel is sent to the top of the furnace by the conveyor, and then sent to the furnace by the screw feeder, and evenly scattered on the grate.
3) Combustion process
The fuel is sent to the furnace by the screw feeder, where it is gradually preheated due to the action of high temperature flue gas and primary air, drying, igniting and burning. During this process, a large amount of volatiles are precipitated and the combustion is severe. After the generated high-temperature flue gas washes the main heating surface of the boiler, it enters the heating surface economizer and air preheater at the tail of the boiler, enters the dust remover, and finally discharges into the atmosphere through the chimney. The unvaporized fuel moves toward the rear of the grate until it burns out, and finally a small amount of ash remaining falls into the slag tap behind the grate.
4) Environmental emissions from BMF boilers
The ash produced by BMF combustion accounts for about 1.5% of the fuel. To facilitate the discharge of ash, a spiral slag discharge machine is arranged at the rear of the boiler to achieve continuous cleaning. A dust collector is arranged in the flue of the boiler tail to ensure that the dust emission meets environmental protection requirements.
5) Efficiency
The efficiency of biomass boilers is generally above 80%. The boiler model is large, the combustion is more complete, and the efficiency of the boiler is higher. The highest level reached 88.3%, which is 15% higher than the average efficiency level of coal-fired boilers.
Biomass boiler type
At present, biomass boilers are roughly divided into two categories according to their use: one is biomass thermal energy boiler, and the other is biomass electric energy boiler.
In fact, the principles of the two are basically the same. They all obtain energy by burning biomass fuel. The first is to directly obtain thermal energy, and the second is to convert thermal energy into electrical energy. Among the two boilers, the first one is now the most widely used and the technology is relatively mature.
If you continue to subdivide, the first type of boiler, the biomass thermal boiler, can be divided into three categories:
The first category: small biomass thermal boilers. The boiler uses solidified or vaporized biomass fuel to provide heat energy in the form of hot water, which has the advantages of small volume, simple structure and low price; the disadvantage is that the energy loss is large, the fuel consumption is large, and the heat energy supply is low. It is unable to meet the needs of users with large thermal energy demand. The boiler is aimed at the heating of single-family rural households and the supply of domestic hot water.
The second category: medium-sized biomass thermal boilers. These boilers primarily use solidified biomass fuel to provide hot water or steam. Its advantages are that the technology is relatively mature, the energy loss is small, and the heat energy supply ability is strong; the disadvantage is that some boiler fuels are coking, and the matching design is unreasonable. At present, the “Spiral Wind Fin Burner Technology” of Shandong Hill Biomass Energy Co., Ltd. has solved the problem of insufficient combustion and coking of medium-sized biomass boilers.
The third category: large biomass thermal energy boilers. There is currently no actual product for this type of boiler. The main reason is that the existing technology is not perfect, and the national policy for replacing biomass with biomass is not perfect. Therefore, it only stays in concept. It emphasizes a centralized management and centralized control of thermal energy engineering. The boiler is only used as one of the equipment to ensure the normal operation of the entire biomass thermal energy project. Therefore, it requires fuel, combustion technology, supporting technologies and related policies. Very high.
Biomass boiler combustion system
1) Feeding system
The feeding system consists of a silo, a vibrating feeder, a screw feeder, a screw feed pipe and the like.
The BMF fuel processed in the factory is transferred to the silo by a belt conveyor, and then the BMF fuel in the silo is supplied to the burner for combustion through a screw feeder. In order to ensure the stability of continuous feeding and material conveying, a vibrating feeder is connected between the silo and the screw feeder.
2) Combustion system
The combustion system consists of burners, fans, igniters and other components.
The biomass fuel first has a preheating process in the burner, and then the fuel is delivered to the furnace through the fan for combustion. BMF fuel contains a high amount of volatile matter. When the temperature in the furnace reaches the precipitation temperature of its volatile matter, the ignition of the igniter fuel can be quickly ignited under the condition of supplying air. The burner temperature control is based on the internal temperature of the furnace, and its temperature is related to the amount of air supplied when the fuel is vaporized. The adjustment of the boiler load is controlled by the adjustment of the feed amount. The flue gas after combustion enters the convective flue through the furnace to exchange heat, and then enters the dust collector for purification treatment, and finally discharges to complete the entire combustion and heat transfer process.
3) Soot blowing system
The boiler is equipped with a fully automatic soot blowing device, which can periodically purge the furnace and the pipe to ensure that no dust is formed on the surface of the pipe, thus achieving safe and efficient operation of the boiler.
4) Smoke system
Air supply system: The boiler air supply system is integrated with the burner, and the air is sent to the furnace through the blower through the blower to achieve the function of conveying fuel and supporting combustion.
Air-exhaust dust removal system: Under the action of the induced draft fan, the high-temperature flue gas generated after the completion of combustion passes through the convective heat transfer in the pipe to enter the dust collector for purification, and finally is exhausted by the chimney by the induced draft fan.
5) Automatic control system
The control system adopts high brightness and full Chinese display, with the famous brand PLC control system as the central control unit; exchanges information with the boiler user in the man-machine dialogue mode to realize the fully automatic operation of the BMF boiler.
Safety knowledge
Overview
The boiler is a thermal energy equipment with high temperature and high pressure. It is one of the special equipments. It is widely used in institutions, business enterprises and various industries. It is a dangerous and special equipment. In the event of an accident involving public safety, it will cause huge losses to the country and people’s lives and property. For public safety, people's lives and property safety, in accordance with the State Council's "Special Equipment Safety Supervision Regulations", the following matters should be noted when using boilers:
Precautions
1. The boiler shall be accompanied by the “design documents required by the safety technical specifications, the product quality certificate, the safety and maintenance instructions, and the supervision and inspection certificate (safety performance supervision and inspection certificate)”.
2. Installation, maintenance and renovation of the boiler. The unit engaged in the installation, maintenance and transformation of the boiler shall obtain the qualification certificate for the installation and maintenance of special equipment issued by the provincial quality and technical supervision bureau before it can engage in the installation, maintenance and transformation of the boiler. Before the construction, the construction unit will inform the municipality or the special equipment safety supervision and management department of the municipality directly under the jurisdiction of the construction, maintenance and transformation, and send the construction notice to the local county-level quality and technical supervision bureau for the record, and then notify the construction.
3. Acceptance of boiler installation, maintenance and renovation. After the completion of the construction, the construction unit shall report the water pressure test and installation supervision of the boiler to the Special Equipment Inspection Institute of the Quality and Technical Supervision Bureau. After passing the qualification, the Quality and Technical Supervision Bureau, the Special Equipment Inspection Institute, and the County Quality and Technical Supervision Bureau will participate in the whole experience.
4. Registration of the boiler. After the boiler is accepted, the user must fill in the "Boiler (Census) Registration Form" in accordance with the "Regulations on the Registration and Use of Special Equipment", register with the Quality and Technical Supervision Bureau, and apply for the "Registration Certificate for the Safe Use of Special Equipment". .
5. Operation of the boiler. The boiler operation must be operated by a certified person who has passed the training and obtained the "Special Equipment Operator Certificate". The operation rules, eight systems and six records must be strictly observed during use.
6. Inspection of the boiler. The boiler shall be inspected once a year, and boilers that have not been inspected safely shall not be used. The safety accessories of the boiler are regularly inspected once a year. The pressure gauges are checked once every six months. Safety accessories that have not been inspected regularly shall not be used.
7. It is strictly forbidden to install the atmospheric boiler as a pressure boiler. It is strictly forbidden to use boilers with three safety accessories such as water level gauge, safety valve and pressure gauge.
Biomass boiler fuel analysis
1. The sulphur content of biomass fuel is mostly less than 0.2%. When it is extinguished, there is no need to install gas desulfurization installation, which reduces the cost and is conducive to environmental maintenance;
2, the use of biomass boiler extinguishing equipment can complete the large-scale reduction of various biomass resources, harmless, resource application, and low cost, so the biomass direct extinguishing technology has good economy. And development potential.
3, the carbon dioxide released by biomass quenching is roughly equivalent to the carbon dioxide absorbed by the photosynthesis during its growth, so it can be considered as zero emission of carbon dioxide, which helps to alleviate the greenhouse effect;
4, the extinction products of biomass are commonly used, and ash can be comprehensively applied;
Fuel extinguishing process
Because the fuel characteristics of biomass boilers are different from those of fossil fuels, the mechanism of quenching the biomass fuel during the extinction process is inevitable. The reaction speed and the composition of the extinction products are also quite different from those of fossil fuels, which are different from fossil fuels. Extinction characteristics. As shown in the above figure, the quenching process of biomass fuel is mainly divided into the precipitation and extinction of volatile matter, and the two stages of coke extinction and burnout. The former accounts for about 10% of the extinction time, while the latter accounts for 90%, and the extinction is detailed. The process is as follows: after the fuel is sent to the extinguishing chamber, the fuel is heated and precipitates moisture under the action of high temperature heat. Subsequently, the fuel continues to increase in temperature, about 250 degrees Celsius, the beginning of thermal synthesis, the precipitation of volatiles, and constitutes coke. The gaseous volatiles and the surrounding high temperature air blending are first ignited and extinguished. Under normal conditions, coke is surrounded by volatiles. The oxygen in the extinguishing chamber is not easy to penetrate into the coke appearance. As long as the extinction of the volatiles is about to end, the temperature of the coke and its surroundings is already high, and the oxygen in the air may also come into contact with the coke. The coke starts to go out, and ash is produced from time to time.
Maintenance of biomass iron pot
1. In order to make the biomass boiler lasting safe and economical operation, it is necessary to strengthen the maintenance of the biomass boiler in daily use.
2. Eliminate the phenomenon of running, running, dripping and leaking in time.
3. Regularly add oil to the movable parts such as valves and locking bolts that are exposed to prevent biting.
4. The insulation layer that has fallen off should be repaired in time.
5. Conduct an internal and external inspection of the biomass boiler every year.
