Baode Brazed plate heat exchanger installation guide and cleaning

1. General of Brazed Heat Exchanger installation Where possible, Baode Brazed Heat Exchanger should be mounted in the vertical position. (See Fig. 3) Install mufflers or vibration absorbers as necessary to make sure vibration cannot be transmitted to the heat exchanger. For larger connection diameters, use an expansion device in the pipeline. A rubber mounting strip can serve as a buffer between the unit and the mounting clamp. (See Fig. 4) 2. Connecting to the system • Use flexible connectors. It’s critical that vibrations from pipe work and control valves not be transferred to the heat exchanger. • Don’t over tighten female unions onto the threaded connections; excessive force will shear the connection braze. The threads are parallel. Baode advises use of a connection with the female part sealing against the top of the heat exchanger connection. (Check the chart below for maximum allowable torque.) Seal unions with O-rings or round gaskets at the end of the connection. Tape may also be used to seal the threads. • Be sure that adequate expansion/safety valves are installed into the adjacent pipe work. Baode recommends the use of expansion tanks. • If pipe work is to be soldered into the nozzles on the exchanger: – Fill the outer circuit with water; the circuit must be open to the air. – Wrap a wet towel around the base of the connection to be soldered. – Use solder containing at least 45 percent silver. – Never weld connections onto or near the exchanger. (See Fig. 5) 3. Avoiding water hammer. Sudden changes in the velocity of a noncompressible fluid (such as water) can result in “water hammer,” a condition that damages pipes, valves, heat exchangers and other equipment. The quick closing of a solenoid valve in liquid lines is a typical cause. Sudden interruptions of the fluid flow increase pressure far above normal levels. Highintensity pressure waves then move back and forth in the pipe between closure and relief points. At a relief point such as a large-diameter header, these waves can strike at extremely high speed. The shock wave produced in this way can cause substantial damage as it alternately expands and contracts the pipe lines. In brazed heat exchangers, water hammer can deform the front or back plate into a bulb shape, with resulting internal or external leakage. An air chamber or water hammer arrestor can avoid or eliminate these problems. Valves with controlled closing times or characteristics can also control the problem. (See Fig. 6) 4. Refrigeration details Condensers Refrigerant gas flows in at the top left. Condensate liquid flows out at bottom left. Water inlet is at the bottom right and water outlet at the top right. Connect water and refrigerant for countercurrent flow. Regulate and control the system via the service medium circuit. Solder connections to the refrigerant side when using Baode Brazed HeatExchangers as condensers. (See Fig. 7) Evaporators The mixture of liquid and refrigerant gas flows in at bottom left. Gas flows out at top left. Water inlet is at the top right and water outlet at bottom right. Connect water and refrigerant for countercurrent flow in most cases. Place the expansion valve near the inlet connection. The valve should be of slightly higher capacity than the unit, and should have an external pressure equalizing connection to avoid unnecessary heating. The sensor bulb located on the suction side should be insulated from ambient air. It must be sensitive enough to respond quickly to changes in gas temperature. Allow at least 500 mm between bulb and the refrigerant outlet connection. Pipe diameter between the expansion valve and the brazed exchanger should be the same as that of the liquid line. Solder connections to the refrigerant side when using Baode Brazed Heat Exchangers as evaporators. (See Fig. 8) Additional Information on Refrigeration Applications a. When operating temperatures are low, insulate the unit to keep condensation from freezing on the outer surface of the plate pack. b. Use quick-acting controls for most refrigeration applications.F Start-up Procedures 1. Close all isolation valves. 2. Fill and vent the coldest circuit first. 3. Start circulation of the cold circuit, opening isolation valves gradually. 4. Repeat the process with the hot circuit. 5. Start automatic control regulation. 6. In steam systems, drain the steam circuit before opening steam valves. This precaution helps reduce the chance of water hammer and damage to the exchanger. Shut-down Procedures 1. Close down the hot circuit by slowly adjusting the control valve. Maintain full flow on the cold circuit. 2. When the control valve is fully closed, switch off the pump. 3. Slowly close down the cold circuit, and then switch off the pump. 4. Close all isolation valves. 5. When the unit is cool, drain it completely. Cleaning When the likelihood of fouling is high (for instance, when hard water is used), clean the exchanger by circulating a cleaning liquid through it. Use a tank with a weak acid for this clean-in-place (CIP) process. A five-percent solution of phosphoric acid is a safe an effective choice for most units. If the exchanger is cleaned frequently, use a five-percent solution of oxalic acid. For best results, the cleaning solution flow rate should be at least 1.5 times the normal flow rate, preferably in backflush mode. Before restarting, flush the unit with plenty of fresh water to purge any remaining acid. Clean at regular intervals. (See Fig. 9)

copy right@ Baode Heat Exchanger Co.,Ltd. 2009