Boiler wood industries
Many wood industries use used boilers to produce steam, taking into account much cheaper investment. The price of a used boiler can reach 1/5 of the new price, certainly according to the age and technical conditions. Because the boiler is a pressure vessel, the safety factor is crucial, especially checking the safety valve condition . Is it still functioning properly or not.
Before being operated, the boiler needs to be cleaned through a cleaning process especially to remove the crust that attaches to the aisle walls and boiler fire pipes. The attached crust will inhibit heat transfer so that the formed steam is reduced, which in turn results in a decrease in boiler efficiency. After the cleaning process is complete, a press test is carried out to see if there is a leak in the boiler. Also intended to determine the condition of the safety valve.
In general, it can be said that boiler fuel needs can be met from residual wood waste production, especially in the barecore industry or sengon wood plywood . So that if it is not sufficient, it is certain that the boiler does not operate efficiently, either due to process factors or technical factors. In addition, modification of the furnace needs to be done, adjusting the boiler fuel in the form of wood waste. The combustion furnace in the form of a separate chamber which is coated with fireproof stone, is placed in front of the boiler which is connected to the fire alley. Use fire heat in the chamber, usually a water-filled pipe is used as a furnace wall and is connected to the boiler body so as to increase boiler water capacity. With such a system, the efficiency of steam utilization in used boilers can reach 50%.
In the design of making kiln dry heating systems, boilers as the main equipment must work at the optimum level of efficiency capable of providing sufficient amounts of steam at the right time. Boiler efficiency is related to combustion management, feed boiler water and load management. Efficiency needs to be sought as much as possible because it results in cheaper operational costs, therefore a periodic maintenance commitment is required for the Boiler System to always operate at optimal conditions. The following are some items in the boiler system that must be considered; Water treament, water feed ( feed water), Boiler, Blowdown,Fuel supply, air supply in the combustion chamber, and stack.
During the drying process in the kiln dry, the engineering manager needs to make the boiler operating system parameters and steam distribution criteria so that boiler efficiency is achieved:
- Steam leak
- Use of dry steam for the process
- Use steam at the lowest possible pressure
- Pipe insulation and hot process equipment
- Take advantage of Flash steam
- Selection and maintenance of correct steam traps
- Appropriate size of steam and condensate pipes
- Reducing the work that must be done steam
- Visiting a number of wood industries in various places, we found that heat-supplying boilers for kiln dry worked inefficiently. This can be seen from the use of wood waste as boiler fuel which is very large and not well controlled. Often the wood waste produced by the rest of the production is insufficient so it is necessary to buy it from a fuel wood supplier.As mentioned in the previous article, one of the factors that affect boiler efficiency is the quality of water used. Bad water contains a lot of impurities that can cause crust, stick to the walls in the boiler. Can also settle at the bottom of the boiler. The emergence of crust causes reduced heat transfer, and worse losses can cause corrosion so that leakage occurs. Generally, impurities in boiler water are CaCO 3 or CaCO 4.To reduce the increase in pollutant concentration, boiler water needs to be treated using chemicals first before being included in the boiler. And during the process of running, the act of draining the dirt or sediment collected at the bottom of the boiler or often called blowdown needs to be done. Boiler water that is discharged through blowdown also contains heat, so it needs clear criteria when blowdown can be done so that impurities can be removed without removing much of the heat contained in the water. Two parameters that indicate the formation of scale are the increase in exhaust gas temperature and high boiler water TDS. In general, any increase in exhaust temperature of 18 o C means that fuel consumption increases by 1%.
Errors in boiler water management not only result in fuel losses, but can have fatal consequences and stop operations for boiler service. To prevent this, control of water quality and boiler maintenance needs to be given serious attention by the management if it wants an boiler that supplies heat to the kiln dry to run efficiently.
The important thing in the design and operation of kiln dry is a piping system outside the heater pipe. The heater pipe which functions to transfer heat to the circulating air in kiln dry needs to get a quality steam supply (dry and the amount as needed). For this reason, here are some additional tools needed:
Header . In the form of a cylindrical pipe that functions as a “reservoir” of steam produced by the boiler, before being distributed to steam user equipment. In this case, the steam user in question is a heater pipe that is in the kiln dry room. In each boiler installation, the header is always used to maintain the stability of steam pressure. This is important considering the pressure is one of the parameters of steam quality. Also to ensure steam can be distributed evenly to all kiln dry spaces.
Steam Trap . Or “steam trap”. The heat that has been transferred to the air in the kiln dry causes the steam temperature to decrease. A decrease in temperature can also be caused by a pipe insulation system that is so poor that heat exits. As long as the pipe is steamed the pressure will also decrease. As a result, there is steam that is condensed into water. Steam traps are used to trap the condensate, and then remove it from the piping system.
Selenoid valve . Is an automatic valve that is used to regulate the amount of steam entering the heater pipe. The valve open / close function of the valve is the temperature in kiln dry, which shows the humidity level. Steam flow (which means heat supply) into the kiln dry will stop if the air is moist enough (wet), to allow this wet air to be released from the kiln dry and replaced with dry air. The fresh air that has just entered has a lower temperature, so the valve will open again. And so on until the water content (MC) of wood drops gradually until it reaches the desired target.