Printing and packaging purification workshop

The production enterprises of plastic chemical products, especially medical plastic product enterprises, have an increasing demand for clean room production and higher requirements. Therefore, when selecting clean room technology and related equipment, enterprises must consider the feasibility and economy of their technology from a long-term perspective, especially whether the technology supplier can provide a complete solution with a good input-output ratio that matches the real needs of the enterprise, and whether this technology supplier can also provide GMP standard certification.
The demand for products that can meet cleanliness levels is rapidly increasing in the current plastic chemical products market. In the past, only products used in the medical, pharmaceutical, cosmetic, and biotechnology fields were required to meet specific cleanroom standards in production. However, now this scope has been expanded to include almost all plastic components required in the automotive and optical media industries, and the cleanliness levels required for products have become increasingly strict.
1、 Project Overview
There is a CD production line in the production workshop of plastic chemical air conditioning purification engineering, and its production scale is also nationwide. It uses plastic as raw material to produce DVD discs (containing data information) at a speed of making one disc every 2 seconds, and then forms DVD disc products that are put on the market for sale after being printed on the cover. The production line technology is imported from abroad, with a total of 10 production lines introduced; Each production line is a complete set of equipment for independently producing optical discs. The entire production workshop operates continuously 24 hours a day, creating good economic and social benefits with its high output rate and high-quality DVD discs, and enriching the domestic information industry cultural market. According to the requirements of the "Code for Fire Protection Design of Buildings" and the properties of the raw materials used in the production process, this factory belongs to Class E fire hazard production factory.
2、 Design parameters
The total construction area of the CD production workshop is 2900m2, with a main production workshop area of 1800m2, an auxiliary production workshop area of 1100m2, and a floor height of 4.1m. The clean area air conditioning area of the production workshop is 1400m2, and the design parameters are:
Pressure plate workshop t=22 ℃± 2 ℃φ=50% ± 5% Grade 7 cleanliness
Printing workshop t=22 ℃± 2 ℃φ=50% ± 5% Grade 7 cleanliness
Comfortable air conditioning zone t=18-26 ℃ φ=50-60% No level
3、 Cold source system design
3.1 Equipment Overview
Chiller unit: screw type, rated cooling capacity: 615kw, two sets, one for use and one for backup
Cooling tower: ultra-low noise counterflow type, water volume 200m3/h, two units, one in use and one backup
Water water heat exchanger: corrugated plate, heat transfer capacity of 175kw, four units, dual-use and two backup
3.2 Cold source water system
3.2.1 Based on the various parameters provided by the production process equipment, the total cooling load is calculated to be 598kw. An important process requirement in the optical disc production line is 24-hour uninterrupted operation, and the safe and reliable operation of the cooling source system is the prerequisite and guarantee for achieving this requirement. Therefore, the configuration of each equipment in the cold source is considered as one for use and one for backup, ensuring reliable and continuous operation of the equipment while reducing fatigue wear and extending its service life.
The chiller unit prepares chilled water (7 ℃), which is divided into three sets of water supply pipelines after entering the water separator, and sent to three air conditioning chilled water consumption points: purification air conditioning end equipment, comfort air conditioning end equipment, and water water heat exchanger. After heat and moisture exchange, it is collected in the collector by the three sets of return pipelines, and then pressurized by the water pump and sent to the chiller unit to form a chilled water cycle. The constant pressure of the chilled water system adopts a closed expansion tank constant pressure water replenishment method. The cooling tower is placed on the floor of the outdoor equipment room together with other cold source equipment, and is elevated with a reinforced concrete foundation. The bottom of the water collection tray is slightly higher than the inlet pipe of the cooling water pump, so that the inlet pipe of the water pump is always full of flow; Install a diversion and noise reduction elbow at the fan outlet.
4、 Design of Constant Temperature and Humidity Clean Air Conditioning System
4.1 Air conditioning system mode
The main purpose of the clean air conditioning system in the optical disc production workshop is to control the number of dust particles in the air, ensure the cleanliness of the optical disc production environment, and improve the product qualification rate and quality. Therefore, based on the two main production processes of optical discs, two independent clean air conditioning systems are set up: the pressure plate workshop air conditioning system and the printing workshop air conditioning system. Two systems are equipped with their own end air treatment devices.
4.2 Division of Air Conditioning Systems
4.2.1 Adopt a full air purification air conditioning system. System flowchart. The system is equipped with one combined air conditioning unit (one motor for the supply fan and one backup), and the air treatment process is as follows: fresh air - mixed with return air - initial filtration - surface cooling - electric heating - electric humidification - supply air - medium efficiency filtration - high-efficiency filtration supply outlet - indoor.
4.2.2 The suspended ceiling of the production workshop is equipped with a uniform flow orifice plate air supply outlet with a high-efficiency filter. A single-layer louvered return air outlet is installed below the return air column on the inner wall, and a residual pressure valve is installed on the wall adjacent to the outer corridor. The form of air organization is turbulent flow, with the top sending and bottom returning. Silencers are installed on both the supply and return air ducts. The indoor air exchange rate is 20 times per hour.
4.2.3 Each process equipment in the production workshop is equipped with an independent exhaust system for exhaust gas discharge. The centrifugal exhaust fan installed on the roof discharges the exhaust gas into the atmosphere, and the exhaust pipe is 2 meters higher than the roof. In order to meet the positive pressure value in the clean room, electric air valves are installed on the return main pipe and fresh air inlet pipe of the combined air conditioning unit's return section. The indoor positive pressure values are required to be 15pa for the pressure plate workshop, 10pa for the printing workshop, 5pa for the differential pressure between the two workshops and the non clean area, and 10pa for the differential pressure between the two workshops and the outdoor area.
5、 Comfort air conditioning system for auxiliary production rooms
In addition to the two clean workshops mentioned above, there are also production auxiliary rooms such as packaging workshop, office, conference room, exhibition room, reception hall, etc., all of which use fan coil units and independent fresh air systems, and are equipped with separate refrigeration supply and return water pipelines. In addition, the packaging workshop is equipped with an exhaust system to remove the odor emitted from the production of finished products, and the supplementary air is naturally supplied through external windows.
6、 Self control design
6.1 Control of Combined Air Conditioning Unit
6.1.1 The water supply pipe of the air conditioning unit is equipped with an electric three-way regulating valve. By installing a temperature sensor on the wall of the clean room to detect the indoor temperature, feedback the signal, adjust the water flow entering the air conditioning unit's surface cooler, and then use an electric heating section for precise temperature adjustment to meet the requirements of controlling the indoor temperature. Similarly, by installing a humidity sensor on the wall of the clean room to detect indoor humidity, feedback signals are sent back to adjust the opening of the three-way regulating valve (dehumidification) or open the electric two-way valve on the inlet pipe of the electric humidifier (humidification) to achieve the requirement of controlling indoor humidity.
6.1.2 The exhaust of production process equipment is intermittent, and the indoor positive pressure value also fluctuates accordingly. Therefore, based on the feedback signal transmitted by the pressure sensor installed on the wall of the clean room, the opening of the fresh air valve and return air valve on the air conditioning unit are adjusted to maintain the specified positive pressure value indoors.
6.1.3 In order to ensure the safe operation of the air conditioning unit, a interlock control between the air supply fan and the electric heater is set up: that is, the electric heater can only be put into use after the air supply fan is turned on; When the air supply fan stops running, the electric heater immediately loses power. The initial and intermediate filtration sections are equipped with resistance alarms. When the filter resistance exceeds the set value, an alarm will be triggered to remind the filter to be cleaned.
6.2 Control of Process Pure Water Cooling System
The process pure water itself is prepared in one go by a pure water machine and stored in a pure water tank. When in use, it is sucked out from the pure water tank, pressurized by a water pump, enters the first stage plate heat exchanger (cooling water cooling), enters the second stage plate heat exchanger (chilled water cooling), exchanges heat in the production equipment, and returns to the pure water tank, forming a pure water circulation system. From the perspective of energy conservation, an additional Level I cooling water heat exchange system has been installed. The main purpose is to utilize the low cooling water temperature (winter and transitional seasons) to pre cool pure water before entering the Level II chilled water heat exchange system and being cooled to the set temperature. Electric two-way valves are installed on both the cooling return pipe and the freezing return pipe, and the opening and closing of the electric valves are controlled by comparing the sizes of T3 and T4 with T1 and T2, respectively.
6.3 Control of Cooling Tower
Install a temperature sensor on the main water supply pipe of the cooling tower, and when the measured water temperature is above 30 ℃, the cooling tower fan will operate; When the measured water temperature is below 30 ℃, the cooling tower fan stops running, achieving the effect of saving operating energy consumption.
6.4 Other
The air conditioning self-control system also includes self-locking power-off control for equipment maintenance such as chiller units, water pumps, and cooling towers.
7、 Summary
7.1 The organization of airflow in a clean room is very important. When conditions permit, it should be designed as an upward supply and downward return air method, and the indoor airflow direction and uniformity should be ensured.
7.2 Reasonable determination of automatic control principles is the key to the design of constant temperature and humidity air conditioning systems; The adoption of a fully automatic control system (using the American Hollywell 988 product in this project) is an important guarantee for the project to meet the design requirements and ensure reliable and stable daily operation after completion and commissioning.
At present, the clean room has been put into use, the air conditioning system is running well, and the production situation meets the expected requirements.