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Can you explain the characteristics that affect the flow of bulk solids and how? Some characteristics that affect the flow of bulk solids are moisture content where enhanced moisture content in solids makes bulk solids sticky. Absorption of the moisture sometimes by the atmosphere by some solids happens. The other characteristic is a temperature where it affects bulk solids at times when they are exposed to a specific temperature. Time at rest is a way which affects the solids when they are kept still or rest. The more rest they take, the more slowly the flow of bulk solids takes place. Particle size is one characteristic where it is easy to handle round particles than the odd and asymmetric ones. What are some common causes of gas pipeline vibration 20 carbon steel line? The upper pressure range and /or the smaller pipe diameters prompts to investigate the possibility that the gas is reaching critical flow somewhere downstream within the pipe. When a gas gets to critical flow, sonic booms (producing vibration) are expected. In fact, one of the main means by which the additional pressure in the pipe is lost. If the source is a compressor, look for surging. If the source is a tower, look for pressure cycling in the tower Look at critical flow through any control valve that may be in the line. At what temperature does water have maximum density? At 40C the density of water is 1000 kg/cum. Define octane number? It is the resistance to detonation of a fuel in a spark ignition engine compared to the isooctane-n-heptane mixture. What is the most common cause of solid size segregation in bulk solid systems? Many engineers usually point directly to the pneumatic conveying system as a source of such a problem. The truth is that in most cases, segregation occurs because of the differences in sizes of the articles. As a rule-of-thumb, if the size ratio extends outside of around 1:1.3, then there will most likely be segregation. This being said, one should inspect the equipment responsible for determining the particle size rather than the pneumatic conveying system if this problem is occurring. List the advantages and disadvantages of a PFR? Advantages of PFR are Continuous operation, high conversion rate, less cost for operation. Disadvantages of PFR are temperature gradients, high maintenance cost. What industry require filtered compressed air? Almost every chemical process, power plant food processing etc. Plant has some type of air operated device from control valves to air operated pumps and all have an air compressor delivering filtered air. What are some common problems associated with dense phase pneumatic conveying? Dense phase pneumatic conveying, typically experiences one common problem from system to system: plugging in the line due to a malfunctioning booster valve. Dense phase systems require these booster systems to introduce new, pressurized air. These boosters are nearly always accompanied by a check valve. If the check valve becomes stuck, the product is allowed to plug the line. What are some common problems associated with Dilute Phase Pneumatic Conveying? Probably the most common problem encountered in dilute phase pneumatic conveying is the wearing of the rotary valve that serves as an air lock where the product is introduced into the system. If excess air is allowed to pass by the rotary valve, this can cause bridging of the material the flow can be slowed or stopped. What is the most common carrier gas used in Pneumatic Conveying? While many applications utilize air as a carrier gas, others are not suited for using air. For example, if the substance being conveyed reactions with moisture in the air or if there is a threat of dust explosions, nitrogen is likely choice. Can you define the third law of thermodynamics? The third law states that 'As a system approaches absolute zero, the entropy of the system approaches a minimum value'. We have some pieces of metals that have been "powder coated", how does that work? Powder coatings are similar to paint, but they are usually much more durable. Rather than adding a solvent to the pigments and resins in paint, as is typically the case, powder coatings are applied to the surface in a fine granular form. They are typically sprayed on so that they stick to the surface. Once the surface has been sufficiently spraying coated, the piece is baked at high temperatures, and the pigment and resins pieces melt and form a durable, color layer. How can you keep our seawater used for heat rejection clean before entering our heat exchangers? Seawater is used as a cooling agent in condensers and coolers. Intermittent injection of chlorine gas is used to eliminate marine growth. The system is a once through type. The band screens before the suction of the pumps are supposed to eliminate scales and other suspended materials. The band screens are not properly functioning. Cooling water flow is about 2.6 million gallons per hour. The pre-screening and mobile screens are not a sufficient protection for the recirculating water. This is a very common problem. In clean salt water the biological grow in the cooling water pipes is the main problem (mussels, barnacle, algae, etc.). After the life cycle is finished, they die and blocking the condenser tubes. To solve this debris problems, use self-cleaning Debris Filters (DF) directly installed in front of the water box of the heat exchangers. What are some common problems associated with dense phase pneumatic conveying? Dense phase pneumatic conveying, typically experiences one common problem from system to system: plugging in the line due to a malfunctioning booster valve. Dense phase systems require these booster systems to introduce new, pressurized air. These boosters are nearly always accompanied by a check valve. If the check valve becomes stuck, the product is allowed to plug the line. Can you define critical radius of insulation? The critical radius of insulation is the thickness of an insulation that does not affect the convection resistance. It is the ratio of the thermal conductivity of the insulator to the convection heat transfer coefficient. Define "saltation velocity" and How is it used in designing pneumatic conveying systems? The saltation velocity is defined as the actual gas velocity (in a horizontal pipe run) at which the particles of a homogeneous solid flow will start to fall out of the gas stream. In designing, the saltation velocity is used as a basis for choosing the design gas velocity in a pneumatic conveying system. Usually, the saltation gas velocity is multiplied by a factor, which is dependent on the nature of the solids, to arrive at a design gas velocity. For example, the saltation velocity factor for fine particles may be about 2.5 while the factor could be as high as five for course particles such as soybeans could. Can you define pneumatic conveying? Pneumatic conveying is a method of moving bulk solids from one place to another with the help of a carrier gas. A differential pressure is applied inside a conveying line. The flow always moves from a region of higher to lower pressure. Explain the working of a spray condenser? A spray condenser is used for the condensation of humid water vapor by direct contact with water. The inlet water is at a temperature less than the dew point of air in the chamber. Are there any general rules for flushing slurry lines? Slurry lines should be flushed with a minimum fluid velocity of 10 ft/s and the total flushing liquid volume should equal 3-6 times the total piping volume. Can you explain barometric condenser? Single-stage or multi-stage steam-jet-ejectors are often used to create a vacuum in a process vessel. The exhaust from such ejector systems will contain steam (and perhaps other condensable vapors) as well as non-condensable vapors. Such exhaust streams can be routed into a “barometric condenser” which is a vertical vessel where the exhaust streams are cooled and condensed by direct contact with downward flowing cold water injected into the top of the vessel. The vessel is installed so that its bottom is at least 34 feet (10.4 meters) above the ground, and the effluent cooling water and condensed vapors flow through a 34-foot length of vertical pipe called a “barometric leg” into small tank called a “hotwell”. The “barometric leg” allows the effluent coolant and condensed vapors to exit no matter what the vacuum is in the process vessel. Such a system is called a “barometric condenser”. The non-condensable vapors are withdrawn from the top of the condenser by using a vacuum pump or perhaps a small steam ejector. The effluent coolant and condensed vapors are removed from the Hotwell with a pump. Can you explain condensate lift? This is a term that is usually used to indicate how much pressure is required to ‘lift’ condensate from a steam trap or other device to it’s destination at a condensate return line or condensate vessel.