Solve environmental pollution and develop secondary steam energy-saving technology
At present, the heat source of the traditional conduction heating dryer mostly uses steam, heat transfer oil or hot water to heat the material. The secondary steam evaporated from the moisture in the wet material absorbs heat and contains a large amount of heat, but is discharged as exhaust gas. In fact, according to the heat balance theory of the drying process, the wall surface heat loss of the drying equipment and the heat taken away by the material are only a small part, and most of the heat is used to evaporate the water in the material. This part of the heat can be recycled after being processed. For small and medium-sized conduction heating dryers, people ignore this problem, but for large-scale conduction heating dryers, especially environmental protection and energy industries, such as municipal sludge, slime, sludge, lignite and other dry high-water, large-volume materials, The efficient use of secondary steam can significantly reduce the operating costs of the drying process.
In addition, some materials such as sludge will evaporate malodorous gases during the drying process, which seriously pollutes the environment and causes great troubles. It is very necessary to solve this problem. Due to its significant significance and feasible conditions, the project has carried out research on secondary steam multi-effect utilization energy-saving related technical solutions.
Project achievement:
1. Successfully developed a feasible secondary steam multi-effect utilization energy-saving technical solution, which can achieve the expected results;
2. Apply the multi-effect evaporation principle of the chemical industry to the field of sludge drying, and realize multi-effect drying of the conduction heating dryer. The atmospheric pressure steam evaporated from the sludge is compressed and heated, and reused as a heat source. Compared with similar products, energy saving can be achieved by more than 50%;
3. The overall scheme is as follows: a multi-stage combined dryer using a multi-layer drying unit; in the drying process, the secondary steam evaporated by the dryer is sent to the supercharging and warming device through the heat tracing tube to be heated and pressurized, and passed through The steam superheater is overheated, and the secondary steam after overheating enters the bag filter. After the first stage dust removal, it enters the electrostatic precipitator to remove dust, so that the secondary steam is removed by two stages, and then the centrifugal compressor or Roots compressor is used. Compression, so that the secondary steam saturation temperature rises, in this process the secondary steam is always kept superheated; the secondary steam saturation temperature after compression is increased, and the material is passed as a heat source to the unit layer of the dryer to dry the material;
4. The secondary steam compressed in the dryer contains non-condensable gas, and the non-condensable gas is discharged through the non-condensable gas discharge valve provided on the non-condensable gas treatment device, and the saturation pressure of the secondary steam system is ensured. ;
5. The detailed technical scheme at work is that the dry heat source is steam. At the beginning of the drying process, the valve is opened, and each unit layer of the dryer is simultaneously introduced with heat source steam, and the secondary steam is generated after the water-containing material is heated in each unit layer, and Through the drainage port of each layer, it is discharged into the secondary steam line. After the start-up, the valve is closed and the dryer is in normal operation. The upper layer of the drying unit supplies a proper amount of source steam to supplement the heat energy, and the heat energy of each layer of the drying unit in the lower layer has secondary steam. provide. The secondary steam is discharged from the exhaust port of each drying unit layer, and the secondary steam secondary steam line is connected to the heat transfer line, the secondary steam does not condense and dew condensation in the transfer line, and the secondary steam is sent to the steam through the transfer line. The superheater and the superheated secondary steam are sent to the bag filter for a dust removal. After a dust removal, the secondary dust is sent to the electrostatic precipitator for secondary dedusting. The secondary steam after the dust removal remains superheated and sent to the Roots compressor booster. The warming, the secondary steam heated by the boosting is sent as the heat source steam to the drying layer of each unit below, the condensate drain outlet of the drying unit layer is connected with the hydrophobic station, and the non-condensing gas discharge valve is connected in parallel with the hydrophobic station. Adjusting the non-condensing gas discharge valve to maintain the secondary steam pressure in the drying unit layer;
6. The excess steam is discharged after being condensed, and the non-condensable gas is passed into the boiler to extinguish the secondary pollution;
7. With the multi-effect evaporation system, the saturated steam required to process each ton of sludge can be reduced from the original 780KG to 350KG steam; the heat energy consumption can be greatly reduced, and energy saving can be achieved.