How to improve steam dryness of steam injection boiler？
The conventional horizontal steam injection boiler in operation in the oil field has always adopted the traditional model. The water is heated first through the convection section and then heated and vaporized in the radiation section. The design dryness of wet steam is generally 80% – 85%.
With the increase of the service life of steam injection boiler, a large number of ash scale will adhere on the smooth tube and finned tube of convection section, which is extremely difficult to remove, resulting in poor heat transfer effect, reducing the efficiency of steam injection boiler, reducing the steam enthalpy value injected into the well,
and the steam dryness is far from reaching the design index, which can only reach about 75% – 78%, which seriously reduces the steam injection efficiency of the boiler. At the same time, the problem is the increase of smoke temperature and fuel consumption, which wastes a lot of fuel and gas resources.
At present, most ultra-heavy oil reservoirs, deep heavy oil reservoirs, and thin heavy oil reservoirs need wet steam with high pressure and above 80% dryness for oil displacement. Therefore, it is imperative to improve the dryness of existing horizontal steam injection boiler.
In view of the above defects in the existing technology, Sanjack company provides a dryness lifting device for horizontal steam injection boiler. The technical scheme is as follows: It includes pressure bearing heat exchange parts and thermal insulation parts, which are installed between the front end of the original convection section shell (b) of the horizontal steam injection boiler (E) and the rear end of the radiation section;
Steam dryness lifting device-a, original convection section shell -b, original convection section coil-c, flue gas-d, horizontal steam injection boiler-e
inlet pipe-1, outlet pipe-2, sealing and pressing cover-3, upper insulation layer-4, lower insulation layer-5
The pressure bearing heat exchange part comprises an inlet pipe (1), an outlet pipe (2), a heat exchange light pipe (8) and a connecting elbow (9). The heat exchange light pipe (8) passes through the side insulation layer (7), and the heat absorption section is the heat exchange light pipe section between the side insulation layers (7),
The sealing and pressing cover (3) is installed on the external insulation box (6) to seal the exposed pipe sections of the inlet pipe (1) and the outlet pipe (2) to prevent internal flue gas leakage; the upper insulation layer (4), the lower insulation layer (5), the external insulation box (6) and the side insulation layer (7) jointly form an insulation component.
The inlet pipe (1) is connected with one end of the heat exchange light pipe (8), and the heat exchange light pipe (8) is welded with the connecting elbow (9) to form a flow heat exchange channel and connected with the outlet pipe (2).
The heat exchange light tube (8) is made of 15CrMo alloy steel in multiple rows.
The original convection section shell (b) is internally provided with an original convection section coil (c).
The above pressure bearing heat exchange parts and thermal insulation parts form a steam dryness lifting device (a), and the right side of the steam dryness lifting device (a) is a radiation section.
The beneficial effect of the product is that the steam dryness lifting device mentioned in the utility model is installed at the rear end of the radiation section and the front end of the convection section, and the heat exchange at this part is flue gas convection heat exchange.
Since the heating surface is added at the front end of convective heat transfer, the convective heat transfer flue gas heat flux here is large, which can effectively improve the steam dryness. Although the heat flux density of flue gas here is large, the heat flux density is still small compared with the radiation section.
In this way, although the steam dryness is greatly improved, there will be no deterioration of heat transfer. It ensures that the pressure bearing pipeline can operate safely while improving the dryness. After calculation, the smoke and air resistance increases by about 1%, which will not affect the normal operation of the combustion system within the allowable range of boiler operation;
The resistance of steam water process increases by about 1.2%, which is within the allowable range of the original design and will not affect the normal operation of steam water system. The unit increases the dryness of wet steam of the original boiler by about 5%, which meets the needs of heavy oil recovery at present.
Main control function
1). Online display of steam dryness: The system can automatically calculate the steam dryness at the outlet of the radiation section according to the separated dry steam flow, and display it in real-time on the central control screen, which improves the operating safety of the system and reduces the labor intensity of operators;
2). Automatic adjustment of combustion conditions: automatically adjust the combustion output of the burner by calculating the steam dryness at the outlet of the radiant section to ensure the best-operating conditions of the boiler;
3). Safety alarm: In order to ensure the safe operation of the boiler, a number of safety alarm points are designed according to the boiler specifications. When the operating parameters of the boiler are abnormal, it can automatically and quickly alarm/shut down the boiler. At the same time, the system automatically records the time and content of the alarm. Users can inquire/dispose of at any time;
4). Focus on monitoring the tube wall temperature in the superheated steam section to prevent the boiler heat exchange tube from running over the temperature.