1. Overview of Low-Temperature Heat Pump Distillation Equipment.
1.1 Equipment Introduction
The working operation of this equipment is to lower the boiling point of liquid using negative vacuum pressure where it can boil and evaporate at temperatures greater than 30 degrees. The heat source of the compressor is used to boil the original liquid through the heat exchanger, and the water vapor evaporated by the compressor’s cold source through the cooling heat exchanger condensed into liquid water and released through the water tank’s overflow port.
Depending on the specific gravity of water quality, the concentration and reduction rate of water can reach 95% or more. As a result, it significantly reduces an enterprise’s waste liquid treatment costs. Moreover, the equipment is compactly designed, portable, requires no external steam source or peripheral cooling water, and only requires the use of electricity and a small amount of compressed air to operate.
1.2 Equipment Features
1）Energy-saving: More than 30 degrees evaporation under vacuum environment (<-93kpa).
2）Power supply: 415V/50Hz/three-phase five-wire system.
3）Durable: The heat exchanger and kettle body are made of stainless steel, which is guaranteed to last a long time.
- Heat exchanger: stainless steel 316L (optional titanium alloy or others).
- Kettle body: stainless steel 304 or 316L (optional internal spraying Teflon).
4）Fully automated feature: The system can be operated fully automatically, monitored by the human-machine interface, with automatic cleaning and defoaming function.
2. Structure of Low-temperature Heat Pump Distillation Equipment.
Low-temperature heat pump distillation equipment mainly consists of liquid feeding, heating, distillation, slag discharge, and drainage. Through an external pump, low-temperature heat pump distillation equipment will transfer highly concentrated waste liquid into the metering device tank. When the automatic valve opens the suction kettle tank, the vacuum pressure will complete the transfer of liquid into the metering device tank. After the liquid feeding is complete, the steam valve is opened to heat the waste liquid through the jacket, allowing it to exchange heat with the moisture in the hazardous waste, so providing heat energy for dewatering.
The vacuum pump evacuates the whole link to -80 to -90kPa, the water boils and evaporates at about 45°C. The low-temperature state can avoid the secondary quality change of other substances due to high temperature. The vacuum environment makes the water evaporation conditions more effective so that the water content can be reduced faster through the stirring device to avoid coking into lumps. The heating process stirring uniform heat can be used to program the cooking cycle and batch after the kettle residue is automatically discharged through the stirring device, completing the discharge work. The water vapor evaporating from the hazardous waste is condensed and stored in the recovery water tank, and the recovered water is reused through the pump.
3. Low-temperature Heat Pump Distillation System Operation Process
After the physical and chemical treatment, the wastewater enters the raw water barrel. The raw water barrel is pumped into the low-temperature heat pump distillation equipment by the lifting pump of the low-temperature heat pump distillation equipment.
After vacuum distillation, the wastewater is pumped out by the vacuum distillation equipment suction pump and transported to the low-temperature heat pump distillation equipment transit barrel. When the liquid level is higher than the set value, the transit barrel suction pump starts to run and pump the wastewater to the RO raw water barrel, and the low-temperature heat pump distillation equipment continues to run. When the number of runs of the low-temperature heat pump distillation equipment reaches the set value, the low-temperature heat pump distillation equipment begins to discharge slag, and the concentrated liquid is pumped into the barrel for commissioning.
Due to the impact of weekly discharge tank maintenance on the low-temperature heat pump distillation equipment, as well as the fluctuation of water sources, control of the low-temperature heat pump distillation equipment is critical to controlling water production; therefore, it is necessary to attempt to maintain the flow of waste liquid in the low-temperature heat pump distillation equipment, so that after the pool’s dilution effect, the impact load of water can be effectively reduced.
Low-temperature heat pump distillation equipment needs 24×7 days of continuous operation. Therefore, it is necessary to control the flow of water from the low-temperature heat pump distillation equipment to ensure that the wastewater can be treated evenly every week to ensure the best condition. Do not treat a large amount of water in the early stages and run without water in the later stages.
4. Standard Operating Conditions of the Equipment
To maintain good treatment capacity, it is important to ensure that operating conditions such as COD, B/C, DO (dissolved oxygen) and pH are in the right range.
There should be no large particles of suspended solids or harder colloids in the wastewater entering the cryogenic heat pump distillation equipment. If this is present, it will lead to abrasion or even damage to the cryogenic heat pump distillation equipment during operation. Therefore, other debris in the pool needs to be cleared promptly, and large particles of solids entering the pool need to be strictly controlled.
5. Equipment Parameters Specification Table
6. Operation Management Project
The operating performance of the cryogenic heat pump distillation equipment varies with the raw water quality and operating conditions. To maintain the stable operating condition of the low-temperature heat pump distillation equipment’s membrane, the following management items need to be recorded, to clarify the operating performance of the low-temperature heat pump distillation equipment under specific water quality conditions.
6.1 The following are examples of O&M items.
1) Vacuum level.
2) Output water flow rate i.e., flux.
3) Low-temperature heat pump distillation equipment water quality (BOD5, CODcr, turbidity, oil, pH, etc.).
4) Low-temperature heat pump distillation equipment water temperature.
5) Raw water quality (BOD5, CODcr, turbidity, oil, TN, TP, pH, etc.).
6) DO (dissolved oxygen concentration).
It is recommended that the above items be recorded and filed as routine items, especially for the differential pressure across the membrane, once per shift, to keep track of the membrane contamination and decide whether to carry out chemical cleaning.
6.2 Daily inspection of low-temperature heat pump distillation equipment
To ensure the stable operation of the membrane’s components and the long-term stable performance of the wastewater treatment system, the operations management personnel are required to make sure that the following items are monitored accordingly:
1) Before the operation, the low-temperature heat pump distillation equipment must be checked making sure that the electricity & gas-related piping is connected in place, and there should be no obvious air leakage.
2) The corresponding items should be accurately observed such as the total amount of raw liquid required, the flow of distilled water, the storage of concentrated liquid, and the location of the transfer.
3) Set a good number of separations.
4) When the equipment is not used for a long time, it needs to be cleaned 3-5 times by clicking on the operation in automatic mode.
7. Maintenance Management of Low-temperature Heat Pump Distillation Equipment.
7.1 Precautions during maintenance
When performing maintenance work, be sure to observe safety tips.
When performing maintenance work, be sure to observe safety tips:
1) To avoid any potential hazards, maintenance work should be performed when the equipment is shut down.
2) As part of the Safety precaution procedure, a warning sign must be installed in the area where maintenance is being performed. Example, “Attention, maintenance work in progress!”.
7.2 Daily maintenance
Normally, the evaporation system only needs to be maintained by adding or replacing consumables, such as defoamer, filter cotton, etc. Other parts are only repaired or replaced in case of damage. Under normal circumstances, the following tasks can be done regularly:
1) Check all connections to see if they are leaking or have corrosion.
2) Tighten all applicable fasteners or connections.
3) Examine the immediate environment, paying special attention to places designated for safety.
All maintenance must be carried out by authorized personnel of the Division. The purpose of maintenance is to allow the machine to operate safely for a long period.
Consumables and major maintenance parts
|4||Reactor level probe|
|5||Tank level switch|
|9||Defoamer||Regular flushing with a high-pressure water gun|
|10||Filter cotton||Consumables / Reusable after cleaning|
Daily Maintenance Program
|1||Check all connections for leaks or corrosion||At each inspection|
|2||Filter cotton is regularly replaced and cleaned||Replace the filter cotton weekly or every (n) week according to the actual condition of the filter cotton|
|3||Defoamer flushing regularly||Clean the defoamer when replacing the filter cotton, depending on the situation|
|4||Defoamer addition||Add defoamer in time when defoamer barrel liquid level is lower than 1/3|
|5||Clean the heat exchanger coils in the kettle||1. Run cleaning mode every (n) week according to the heat exchanger coil attachment to the cleaning process.
2. Oil scale can be cleaned with alkali.
3. To thoroughly remove the accumulated dirt, acid cleaning can be used instead of alkali cleaning.
|6||Reactor liquid level probe unplugged and scrubbed||When system overhaul or probe adhesion failure|
|7||Refrigeration system maintenance||Every 1-2 years|
|Precautions for daily use||