At present, most of the 17.2Mpa, 21 MPa conventional saturated oilfield steam injection boilers are of traditional structure.

The design dryness is usually 80%, the design efficiency is 88%, and the exhaust gas temperature is 220 ℃.

With the increase of the service life of steam injection generaters, their dryness and thermal efficiency have far failed to meet the original design requirements.

The energy consumption per ton of steam increased significantly and the steam injection efficiency decreased significantly.

In view of the existing steam injection boiler with traditional structure, our company has carried out the transformation of drying and efficiency increasing.

The average oilfield steam injection generater dryness is increased by 10%-15% and the overall thermal efficiency is increased by more than 5%. It has reached a new level in dryness, efficiency and energy saving of steam injection boiler.

Conventional Oilfield Steam Boiler Faults

The conventional steam injection boiler is prone to the following faults after running for a long time.

1). As the last part of boiler flue gas process, convection section is scoured by flue gas for a long time;

2). The convection section adopts finned tube structure, the gap between fins is small, and the dust in flue gas is used to gather;

3). The flue gas contains moisture, as well as sulfur dioxide, nitrogen oxides, unburned carbon particles, other dust and other particles in the smoke. After mixing with these particles and water, the solid coking is firm and firm, and it is not easy to fall off.

4). Finned tube is located at the tail of convection section, which is the key heat absorbing component. With the convective heat transfer of flue gas in the front section of convection section, the temperature of flue gas decreases gradually, and the particles carried in the flue gas are easy to settle and gather on the finned tube, and it is not easy to wash away the accumulated dust due to the low velocity of flue gas.

5). As the exhaust gas temperature is too high, the fin temperature increases, the fin overheating, oxidation and corrosion are serious, which shortens the fin life, and some of the fins fall off in large area. The heat transfer efficiency is greatly reduced.

High-dryness Steam Injection Boiler Working Principle

In order to solve the above problems, we design the high dryness steam injection boiler according to the following scheme.

By adding the superheated section coil, 75% of the dry steam from the radiation section will be heated in the convection section, so that the steam injection dryness can be as high as 85%; if the dryness of 75% remains unchanged, the energy absorbed in the superheated section is to reduce the fuel consumption; because the heat absorption of the steam with high dryness is carried out in the convection section, there is no scaling, the heat transfer effect is good, and the operation is safer. There absorption of heat in the superheated section can greatly reduce the exhaust gas temperature and improve the overall thermal efficiency of the boiler.

Combined with the structural characteristics of the existing vertical convection section steam injection boilers, we add a enhanced dryness section at the lower part of the original detachable convection section and the upper part of the transition section.

Two rows of bare tube are arranged in the lower part of the convection section to absorb the outlet flue gas temperature of the radiation section and to improve the feed water temperature and steam dryness of the convection heating surface of the oilfield injection boiler. The superheated section is located between the convection section and the transition section at a height of 550 mm, which ensures that the height of boiler transportation is not exceeded after the installation. The enhanced dryness section is staggered by 14 seamless steel pipes with 89*12. This arrangement increases the heating area without increasing the water resistance. The total weight of the superheated section is 2116Kg and can be made removable and fixed as required. The legs of the overheated section are mounted on the legs of the transition section.

High-dryness Steam Injection Boiler Parameter

1). Rated evaporation:         9.2 t/h~30t/h

2). Rated steam pressure:     10MPa~26 MPa

3). Rated steam temperature:  390℃

4). Rated thermal efficiency:   ≥91%

5). Steam Dryness:           ＞85%

6). Fuel:                     Oil and Gas Dual Use

7). Control mode:             PLC + touch screen + industrial computer

8). Loading mode:            Trailer/Skid

9). Operative Mode:           Subcritical/Supercritical

High-dryness Steam Injection Boiler Advantage

1) Enhanced dryness section can reduce the exhaust gas temperature of the steam injection boiler and improve the thermal efficiency of the boiler;

2) Dryness and oxygen content in flue gas are applied to ensure stable and balanced operation of thermal efficiency, so that steam injection boilers are always operating in a state of high thermal efficiency, achieving the purpose of energy saving and efficiency increase;

3) Only two rows of heat exchanger bare tubes are added to the unit, with the overall height raised by 550 mm. For the mobile steam injection boiler, it does not exceed the upper plane of the water-water heat exchanger and does not affect transportation.

4) The installation position of the device is relatively independent and located on the upper part of the transition section, which is convenient for maintenance and replacement.