Armoured thermocouple in the heating furnace of ketone benzene dewaxing unit of technological transformation

1 device status quo analysis

before renovation, a set of ketone benzene device actually have two electric heating furnace. One of them is to wax oil, wax material provide heat source, workshop is called 'a batch of dual-use', radiation section with partition, four 5 of the space used for heating to wax oil, the other one 5 of the space used for heating waxes, due to the feed rate of heating furnace, the requirements of the furnace temperature is different also, deviation is very big, although there is a partition, but to the radiation section of the upper and become one. Still influence each other in the operation process, the furnace outlet temperature is difficult to control, the tremendous difficulty to the operating personnel. Another one under the wax oil only provide heat source, the operation is relatively simple, relatively stable operation. Because two used in heating furnace, furnace body deformation, the lining drop and several air leakage, the surface of the furnace temperature is high, the furnace heat loss is big, the flue damper control using hand to adjust, and no waste heat recovery system, so the thermal efficiency is extremely low, before modification, furnace 1 history * high thermal efficiency is 84%, * low thermal efficiency is 76%, the furnace 2 history * high thermal efficiency is 85%, low thermal efficiency is 78%. Become the energy-consuming equipment. High exhaust temperature, smoke large displacement, high concentration of NO x in flue gas, and energy conservation, environmental protection equipment.

2 technical renovation

2. 1 the flame monitor to monitor

20 of the original design was three sets of furnace burner are installed flame monitor, once there is a fire mouth out, signal feedback to the furnace fuel gas rapid cut-off valve, the valve is closed, the heating mouth all put out the fire, to prevent tempering or steam chamber of a stove or furnace. Heating furnace after flameout, device to cut off incoming, retreat to the relative safety state, after being relighting it again to resume production, large losses for device. In addition, a flame monitor the price is in 10000 yuan of above, the cost is higher, in the case of a shortage of funds, the suggestion on each heater installed in radiation section, a flame monitor all camera at the bottom of the furnace burner and the lower part of furnace tube, the signal is introduced into the operation on a television monitor, operators can completely observe and monitor each burner combustion conditions. Disposal if abnormal case, can quickly respond, safety can be ensured and the whole furnace monitoring operation, save the installation and maintenance costs.

2. 2 furnace outlet temperature thermocouple to armoured thermocouple

the original design three sets of furnace outlet temperature of the two way two thermocouples, total export 1 measuring thermocouple, one control thermocouple, a total of 12 units are common thermocouple, considering the high outlet temperature of the furnace, * high up to 270 ℃, medium inflammable and explosive components of methyl ethyl ketone, toluene, once has the leakage, can cause a fire. Advice with armoured thermocouple, after the case is not easy to leak, to prevent the leakage problem.

2. 3 burner and shift of pilot burner gas double valve group modified

in order to guarantee heating furnace before ignition valve for reliable and fire mouth and is equipped with double valve pilot burner fuel gas. But now found in the construction of gas flow loop under two valve installed too close. Practice is not convenient, it is recommended that a valve should be installed under the gas flow loop, two way valve installed in a location near the burner, so when the normal operation of a valve normally open, two way valve with the working condition of timely adjust, convenient to operate.

2. 4 upgrade replacement of air duct control box motherboard

three heating furnace for the wind system equipped with air duct valve, pneumatic motor, a control box and often occurs in the process of running in the DCS can't operation, and the opening of the valve position is a table and DCS display value deviation is large, confirmed by the analysis of the main board version is low, frequent breakdowns, after the motherboard upgrade replacement, solved the problem.

2. 5 induced draft fan site cannot be started after cut cut or stop

induced draft fan motor frequency control, after the cut cut or stop induced draft fan for many times, found that cannot be started, can only be started after the transformer room reset, confirmed by the analysis of the electrical control cabinet no potentiometer, need not reset after add potentiometer, you are able to operate the induced draft fan motor at the scene.

2. 6 for operating experience and revision in the operating instructions

before heating furnace without waste heat recovery system, the modified installed thermocouple and flue gas waste heat recovery system, the operator is trained, but there is still a flue gas oxygen content in the process of operation, hearth negative pressure, outlet temperature of the furnace, such as volatility, not accurate operation, after a period of groping, write the operation instruction, after is feasible by practice, the operation method of revision in the operating instructions.

3 conclusion

and improve supporting facilities of the thermocouple by furnace, heating furnace thermal efficiency increased significantly, from 80% to more than 91% now, close to the design value, waste heat recovery system can run for a long period of time, the overall smooth operation of reheating furnace, the energy consumption of unit, the unit mass transfer efficiency purpose.