The automated complex with microprocessor system of automation is designed for heating oil emulsions at their field treatment and transportation. It is developed on baseline of furnace series PTB-10 and represents the further evolution of the line of tubular furnace modules.
Technical data
| Parameter: | AKPN |
| Heat power, MW (GCal/ч) | 11,6(10) |
| Oil emulsion capacity, tons/hour (м3/ч), within: | 200–540 220–600 |
| Inlet temperature, °С, min.: | +5 |
| Outlet temperature, °С, max.: | +90 |
| Fuel: | gas, oil |
| Coil operation pressure, MPa (kgf/cm2), max.: | 6,3 (63) |
| Efficiency, %: | 85 |
| Dimensions, m (L х W х H, assembled): | 21,0 × 4,3 × 9,3 |
| Mass, tons max. |
55 |
Automated oil-heating unit allows to:
- To improve quality of operating practices and to increase service life of process equipment;
- To provide the operating practices stipulated in the operation schedule;
- To increase efficiency of personnel activity and to improve the work conditions;
- To reduce fuel consumption and to decrease volume of harmful atmospheric emissions.
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Heat exchange chamber is the volumetric metalwork consisting of welded metal profile, external and internal fencing, where the interspace is filled with heat insulating material. To increase cost efficiency of the furnace the eight coil sections made of steel seamless pipes with spiral ribbing are arranged. Coils are located symmetrically, on the left and on the right sides of direct axis of the chamber.
Operation principle of heat-exchange chamber: gas from combustion chambers in the form of flat jets comes to the internal space of furnace through the confusors. Jet speed of confusors makes 100-120 m/s, temperature is between1600 and 1700°С. Jets with high kinetic energy inject the cooled furnace gases from side bottom zones of heat-exchanging chamber providing intensive recirculation of combustion products. The process is accompanied with developed radiation-convective heat exchange between recirculation furnace gases and central sections of product coil.
By the way of reducing the temperature in the central section down to 800...900°С recirculation allows to provide balance of heat stress of heat surface and to use finned tubes and to increase average heat stress of heat surfaces up to 80 kW/m2.
The AKPN has convective section with additional coils. This feature is used to improve performance of the unit from 70 to 85%.
The partially cooled combustion products are forwarded to the convection section, where flushing single-row coils, that are cooled and vented out.
To provide the unit operation with backup liquid fuel the first two tube rows (left and right) are made without finning.
Basement module is designed for mounting of heat exchange chamber, combustion chambers, air duct assembly, pipelines and fittings to forward fuel gas to combustion chambers and ignition burners.
From high-pressure centrifugal fans the air for combustion is fed thru air duct to combustion chamber space between internal surface of the housing and external surface of the fire tube. Air flows in spiral direction down to the chamber bottom and is mixed with fuel gas, coming to the combustion chamber thru a perforated hood.
Rotation of air flow at high rate provides its highly turbulent movement in the bottom section of combustion chamber in the zone of fuel gas intake. Air is intensively mixed with gas; this provides high degree of combustion of fuel mixture.
Rotation of air flow at high rate provides its highly turbulent movement in the bottom section of combustion chamber in the zone of fuel gas intake. Air is intensively mixed with gas; this provides high degree of combustion of fuel mixture.
Liquid-fuel burner are arranged at the side walls of heat exchange chamber and designed as shelters with burners arranged inside. Shelters are used to provide required operation conditions for burners (ambient temperature, min. -10°С) and to eliminate external interference at standby.
The furnace is equipped with fan units set for operation in concurrent mode using air pipelines and hoses. Fan unit is equipped with air intake casing, vibration isolator and mounting frame to set on concrete foundation.
Automation system
The plant is equipped with microprocessor automation system based on furnace control station, providing the following main functions:
- Automatic ignition using main and backup fuel (with gas line purge and fire box ventilation);
- Automatic start-up to operation mode;
- Automatic control of set outlet temperature;
- Optimization of combustion with О2 control in effluent smoke gas;
- Coils condition check (according to the oil temperature at coil outlet);
- protection, alarm and emergency stop of the furnace;
- gas content control in stagnation zones, connection to the existing fire-control unit;
- control of air feed to combustion with inverter (variable frequency drive) when operated on main fuel.
The low level of automation system consists of sensors with standardized current output 4...0 mA, realizing monitoring and recording of the following parameters:
- Temperature and pressure in inlet and outlet collectors of the product heated;
- oil flow temperature at coil outlet;
- Gas fuel (liquid fuel) pressure downflow the control valve;
- product flowrate and fuel consumption;
- smoke gases temperature;
- flame monitoring in combustion chambers and burners;
- gas content control in heat-exchange chamber and in fan collector at the ignition point of the unit.
Industrial controller proceeds signals from sensors and controls start and stop processes of actuators. Automation system also provides automatic control of electric valves operation at oil pipelines if fire or loss of sealing of coils takes place.
The loop controlling fuel combustion mode consists of gas line control valve, temperature setting device (temperature transducer) at heated product outlet and variable-frequency electric drive.
