How to check if the solvent recovery equipment cannot be heated when it is turned on? Direct answer: check according to the four-step sequence-power indication and insurance, temperature control setting, heating element and heat medium circulation. The four steps cover more than 90% of the failures that cannot be heated. The principle of the sequence is soft first and then hard: the inspection of non-disassembling machines such as setting and parameters is put in front, and the inspection of components and heat media that need to be stopped and disassembled is put in the back. A field multimeter plus a thermometer will do most of the first three steps. Find out the problems at this level and deal with them at this level. Don't skip the pre-inspection and replace them directly. This article makes the four-step check points clear.
First look at the panel: the power indicator is not on, check whether the equipment is powered on, the plug is in an empty state, and whether the fuse is blown; The indicator light is on but the heating does not act. Go down and check the temperature control. Three-phase heating equipment to measure the three-phase voltage, the lack of phase when the heating power is insufficient or even burning components. Don't just change the insurance when the insurance is blown. Measure the insulation and resistance of the heating element to the ground. The short-circuit state is not excluded. How many times you change the insurance will be in vain. The inspection is carried out in the power-off state. After the power-off of the capacitor and the heating large inertia parts, the capacitor and the heating large inertia parts should be left to discharge. Do not operate with electricity.
On the temperature control side, look at three points: whether the set temperature is lower than the current material temperature (it is normal not to heat when the set value is reached, this kind of false alarm is very common, first compare the set value with the actual temperature), whether the thermostat output indicates any action, and whether the sensor wiring and resistance are normal. Sensor drift will make the thermostat misjudge the temperature, compare the actual temperature in the kettle with a portable thermometer, and replace the sensor if the deviation exceeds the limit. If the thermostat has a learning function or program setting, confirm which program segment is running, and do not wait for automatic heating in manual mode. Setting class problems is the fastest to deal with and the easiest to ignore skipped check items.
Power-off measurement on the component side: the resistance values of the three groups of electric heating should be balanced and close to the nameplate value, and any group of open circuits or abnormally low resistance values should be treated as faults; If the insulation resistance to the ground is lower than the requirements, the maintenance shall be stopped. The contactor is an intermediate link: the temperature control has output but the contactor does not pull in, check the coil voltage and contact state; Contact ablation will show that it is not heated when it is heated. When replacing components, the power and installation size shall be in accordance with the original specifications. Do not use high-power parts. The distribution of heat load changes and the risk of local overheating follows.
The failure of the heat medium system is invisible: the pump does not circulate, there is air resistance in the system, and the heat medium is aging and coking, which will prevent the heat from being sent to the kettle, and the performance is also that the kettle temperature cannot be brought up. Check and see three samples: circulating pump operation and steering, expansion tank liquid level and system gas content, heat medium sampling to see viscosity and coking degree. The heat medium is detected and replaced periodically, the heat transfer efficiency of the old oil used over time decreases, and hot spots may be formed by coking on the heating surface. Heating observation after disposal: heating according to the set curve, recording the time to reach each temperature point, and comparing with the historical curve to confirm the recovery.
| Steps | Check item | Abnormal performance | disposal method |
|---|---|---|---|
| Power supply | Indicator Light Empty Opening Fuse | The light does not come on and the fuse is fused. | Replace fuse and check for short circuit |
| Power supply | Three-phase voltage | Lack of phase or low | Check the power supply line |
| Temperature control | Set and actual temperature | Set below current temperature | Correct setpoint |
| Temperature control | Sensor resistance | Drift Exceeded Limit | Replace the sensor |
| Component | Resistance and insulation | Open circuit or low insulation | Replace the heating element. |
| Execute | Contactor contacts | No pull-in upon receiving the command. | Replace the contactor. |
| Heat transfer medium | Circulation and Oil Quality | Non-cyclic or non-coking | Replace the pump and heat transfer fluid. |
A short circuit downstream has not been eliminated: ground faults in the heating element, moisture ingress in the junction box, or loose wiring terminals causing arcing can repeatedly blow the fuse. Before replacing the fuse, first measure insulation resistance and impedance to identify the root cause; do not simply try to cope by increasing the fuse rating.
Regularly use a portable thermometer to perform multi-point comparisons inside the reactor: calibrate or replace sensors if any single-point deviation exceeds the limit. Discrepancies between the displayed value and the actual temperature can directly affect product quality—don’t wait until process fluctuations occur before suspecting the instrumentation.
According to the oil quality inspection schedule, sample the oil to check viscosity, acid value, and coking level; replace the oil if any of these parameters exceed the limits. For continuously operating equipment, conduct an evaluation at least once a year, and when changing the oil, simultaneously clean the heating surfaces and pipelines to prevent coking residues from the old oil from remaining in the system.
This article by LuoyangWohong PetrochemicalEquipment Co., Ltd. arranges that the company provides design, manufacturing and operation and maintenance services for condensation recovery, membrane separation recovery and complete solvent recovery devices for chemical and pharmaceutical enterprises. If you need process evaluation or scheme configuration, please contact and exchange.
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