The cost of a single ton of steam consumed in soybean crushing plant accounts for about 40% of the cost of soybean processing, and steam consumption is one of the important indicators of the level of production process equipment and management level of the plant. Low steam consumption is close to 200 kg/T material, while high steam consumption is up to 265 kg/T, with a 30% difference between high and low. The level of steam consumption is closely related to the product yield and product quality, as well as other electricity and solvent consumption. Why is there such a big difference in steam consumption between plants, and does the very low consumption mean that the level of production process equipment and management is relatively high?
1. Steam consumption is more a reflection of the level of operation and management
In crushing plants with output higher than 1,500 tons per day, there is no qualitative difference in the level of equipment and operation between peers, and the level of steam consumption is more a reflection of the level of operation and management.
Steam consumption in large plants depends first of all on the number of days the plant is continuously on, i.e., the level of capacity utilization, because the longer the press plant is on to preheat the equipment piping, the lower the consumption of various kinds, and conversely, the more frequently the plant is turned on due to equipment failure and shutdown, the higher the steam consumption is bound to be. Maintain continuous and stable production, the higher the utilization rate of equipment, production consumption, labor costs, the lower the quality is also more stable, often the plant production and operation plan is strong, the more stable the quality, consumption is relatively low, equipment maintenance and overhaul in order, the front-line workers work well organized, but also can produce results. On the contrary, poorly planned production and operation, the quality is not stable, consumption is also relatively high, the departments pull each other’s strings, employee fatigue and complaints, and even prone to production safety and quality safety accidents.
2. The impact of process equipment on steam consumption
Process and equipment selection affects the production of consumption indicators, the same amount of processing, the more equipment used, with more heat equipment, piping, conveying equipment, more steam will be used, such as 3000 tons of processing plant, with two tempering tower than with a tempering tower consumes more steam, DT and DC separate, than a single DTDC steam consumption is high.
Equipment installation process, most of the heat equipment, pipelines are insulated, but leachers, cold dry box, hot beans, hot embryo conveyor some plants insulated, some not insulated, also have an impact on energy consumption.
Some factories have gross oil degumming and phospholipid drying equipment in the leaching workshop, while others do not, and the steam statistics are not of the same caliber, which also causes some differences.
Some plants leaching plant mixed oil evaporation and condensation system vacuum, steam vacuum using steam power, some plants use a mechanical vacuum pump, different processes caused by the difference in steam consumption.
The location of the steam flow meter installed in the workshop has an impact on the assessment and measurement of steam consumption.
3. Site management and maintenance
Poor site management, such as the presence of steam, water running and dripping, is bound to affect steam consumption. Safety valves, regulators, pressure relief valves are working properly, and related instruments and other need to be adjusted regularly. The heat exchange surface of the heat exchanger needs to be checked and cleaned regularly, and if there is scaling, it will affect the heat exchange effect.
4. Waste heat utilization
Out of the workshop hot oil, condensate, wastewater, exhaust gas, etc. entrained heat, most of the factory degumming oil or steam extraction of gross oil, cooking tank discharge of wastewater are carried out heat recovery. Recently, many factories have carried out heat recovery of hot air discharged from DC and hot air discharged from puffing cold dry box to reduce steam consumption.
Some plants have made use of steam condensate tank flash steam, and some have made use of condensate waste heat. Currently, the use of steam condensate to heat air heaters and preheat the upper beans of the tempering tower has become popular, CHEMSTA believe that the use of waste heat from condensate in plants with their own boilers is not necessary, and more attention should be paid to the quality of condensate in their own boilers. Condensate is fully returned to the boiler room for recycling, and if condensate is brought down in the heat department, it looks like the steam consumption of the press shop is low, but it has to be reheated again when it returns to the boiler room, and there is no change in coal consumption, but rather an increase in electricity consumption.
5. Own boiler vs. purchased steam
Most pressing plants use purchased steam, which is usually superheated steam from a cogeneration plant, while the boilers in own pressing plants produce saturated steam, usually at a steam pressure of 8 to 11 kg (gauge pressure). The steam from the power plant is more than 10% higher than the steam enthalpy of the own boiler, plus the steam condensate from the thermal power plant does not need to return to the thermal power plant, the crushing plant needs to make full use of the heat of the condensate and use the water for other industrial water such as cooling water tower replenishment water, while the plant with its own boiler does not need to use the temperature difference of the condensate, so the same process equipment, own boiler compared to purchased steam, steam consumption will be reduced by about 10%.
The level of steam consumption in soybean crushing plants is not a matter of the production plant alone, but a reflection of the level of operation and management of the entire plant, and keeping production continuous and stable with a high start-up rate is an important factor in the level of steam consumption. According to the law of conservation of energy, the energy required by the workshop depends on the heat taken away by the finished product, the heat discharged from exhaust gas and waste water, and the less the heat, the less the steam used by the workshop.
There is no need for the production department to blindly compare, and the management department should not over-emphasize on benchmarking. The situation of each factory is very different, and excessive saving of steam may even affect the quality of products, the rate of grease and solvent consumption.
For more than 40 years, we have built hundreds of soybean oil plants, some of which are able to work continuously for more than 350 days per year, greatly improving production efficiency.