In industrial production, the selection of advanced and reasonable machinery and equipment is of great significance to ensure product quality, reduce operating and maintenance costs, improve product competitiveness and economic benefits, and promote industry development and technological progress.
Industrial design of falling film evaporator and the selection of traditional falling film evaporator design is to achieve the purpose of energy saving and consumption reduction by increasing the number of steam utilization (single effect to multiple effects). However, the increase of the effect number doubles the steel consumption and the cost. Due to the limitation of the heat transfer temperature difference, the increase of the effect number generally does not exceed seven effects. The double-effect falling film evaporator with steam jet heat pump and hydraulic jet is the design of common falling film evaporator.
The application of heat pump in falling film evaporator adopts mechanical heat compression type heat pump compression device, which can be centrifugal type and positive displacement compressor. The compression temperature difference is large. It is generally around 11 °C, which limits the number of effects of mechanical compression heat pumps to no more than three effects at most. It is also limited when evaporating solutions with a higher boiling point rise, and the structure is complex, high cost, high maintenance cost, and consumption. Due to the large amount of electricity, the steam jet heat pump is rarely used in the application of mechanical compression heat pumps. Compared with without heat pump, with heat pump, it can be equivalent to increase one effect.
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The use of dividing wall condenser and water ring vacuum pump with heat pump, coil condenser, water ring vacuum pump condenser and material preheater make full use of the heat of the secondary steam at the end effect, and reduce the consumption of cooling water. The final effect secondary steam of the multi-effect falling film evaporator with this structure is condensed into water at the same temperature (only a phase change occurs), and then discharged from the condenser. Condensed water has a high temperature and is soft water, which can be put to good use. The water ring vacuum pump sucks the non-condensable gas and a small amount of steam from the evaporator and discharges it to the atmosphere. And to maintain each effect evaporation has a certain degree of vacuum. Compared with the use of water jets, cooling water consumption and electricity consumption are lower. Take Fuyu Bright Dairy Group's two models of RNJM02-2400 double-effect falling film evaporators as an example, the evaporation capacity is 2400kg/h, SZB water ring vacuum pump, SK water ring vacuum pump and compressor, SKL direct-connected water ring vacuum pump , 2SK two-stage water ring vacuum pump, SKA water ring vacuum pump, SZ series water ring vacuum pump and other vacuum pumps are equipped with a motor power of 5.5kw, cooling water consumption of 9t/h, inlet water temperature of 10°C, and discharge temperature of 38°C, with the same capacity Compared with the double-effect falling film evaporator of the hydraulic ejector, the power is reduced by 13.5kw, and the cooling water is saved by 13 tons per hour. According to the water supply price of 1.00 yuan/ton and the drainage price of 0.80 yuan/ton, the electricity and water volume can reduce the operating cost by 143,391 yuan in one year, and the entire equipment investment can be recovered in 3 years.
Adopting tubular condenser and water-ring vacuum pump structure Adopting hybrid condenser, cooling water tower, water-ring vacuum pump with heat pump, material preheater, hybrid condenser, cooling water tower and water-ring vacuum pump Three-effect falling film evaporator, which is cooled by After the water circulation pump sends the cooling water to the water tower, the temperature of the cooling water is reduced by 8 °C, which is generally taken as 6 °C in the calculation of most evaporators. The pressure requirement of the cooling water circulating pump is not high, as long as the cooling circulating water is sent to the cooling water tower. During the working process, only the cooling water needs to be circulated through the cooling water tower, and there is almost no need to add low-temperature cold water. The water saving effect is particularly significant, especially in Water-scarce areas are even more significant.
The selection of matching pumps for multi-effect evaporators now adopts SLB, SLQB dismantling vertical double suction pumps, ISWB horizontal dismantling pipeline centrifugal pumps, ISGB vertical dismantling pipeline centrifugal pumps, ISGD, IRGD low-speed vertical pipeline pumps, ISG, IRG vertical pipeline pump, ISWD low speed horizontal pipeline centrifugal pump, ISW horizontal pipeline centrifugal pump, IS, IR horizontal single stage single suction clean water centrifugal pump, SH type double suction clean water centrifugal pump, S type double suction medium pump Open centrifugal pump, ZX clear water self-priming pump was successfully used in the production of vitamin C in the pharmaceutical factory of Jilin Songyuan Food Industry Company. The main purpose at that time was to solve the special requirement of vitamin C on the corrosion resistance of the pump. The RNJM03-5000 three-effect falling film evaporator has been applied in Longdan Group and Hailar Bright Dairy Company, and the effect has been very good. However, this fluoroplastic alloy pump only removes the water supply at the mechanical seal, and the matching motor power has little change from the previously selected pump. Later, the ICB series single-end mechanical seal stainless plate stamping pump of Wuxi Jiuyang Pump Co., Ltd. was selected, which was also used on the RNJM02-2400 double-effect falling film evaporator. h, the lift is 32m, the motor power is 2.2kw, and the other two material pumps and one condensate pump are ICB32-25-125 type pumps, with a flow rate of 3.2t/h, a lift of 20m, and a motor power of 0.55kw, making the RN-JM02-2400 The total power of the double-effect falling film evaporator is only equipped with a centrifugal pump to reduce the power by 6.75kw. It is calculated based on 300 days per year and 16 hours per day (two-shift work system), which saves 32,400 yuan in electricity bills per year. Tianxi Jiuyang ICB series pump is selected, and the effect is very good in Harbin Oil Factory.
Reasonable selection of high-pressure pump The working pressure of the high-pressure pump is generally 14MPa, and the centrifugal pump of 25MPa is generally selected. The flow selection can only meet the needs. When the high-pressure pump leaves the factory, the power of the supporting motor is designed according to its rated pressure and flow, and the working pressure is far lower than the rated pressure of the pump, so the power under the working flow and pressure is much smaller than its rated output power. Selecting a motor whose power can meet the output power needs of its work can reduce the total power of the drying system and reduce operating costs. Heilongjiang Yi'an Dairy Factory did just that. RPYP03-500 type drying unit, the traditional high-pressure pump model is GJB1-25 type, the matching motor power is 7.5kw, and Yi'an Dairy Factory uses the same type of high-pressure pump, and the success rate of replacing the matching motor is 5.5kw, so that one year can save money The electricity bill is 10,000 yuan, and the operation has been good.
Reasonable use of heat energy to preheat the intake air with exhaust air, and then preheat the intake air with the condensed water after heating the air with heating steam, and make full use of the waste heat, so as to achieve the purpose of energy saving and consumption reduction.