I、Photovoltaic new energy silicon wafer production process
In terms of
large aspects, the production of new photovoltaic silicon wafer,
including silicon single crystal bar production and photovoltaic new
energy silicon wafer production of two parts, broken down into the
following main processes: single crystal bar growth - single crystal bar
cutting and (Chemical etching, LP-CVD + AP-CVD) -
PTA heat treatment - backside damage treatment - polishing (ML
roughing) - grinding / grinding plate inspection - etching (LP-CVD +
AP-CVD) , ML fine polishing) - Washing - Quality
inspection - clean packaging from single crystal rod growth to the outer
diameter grinding for the silicon single crystal bar production
process, sliced after the process for the new photovoltaic silicon wafer
production process. This paper introduces the
design scheme of air conditioning and purification system and automatic
control system for the production process of PV new energy silicon
II、Air conditioning purification system
Air conditioning design is the layout of the process, the production process closely. Different types, different uses of the plant air conditioning and
purification systems have their own characteristics, the following to
introduce the new photovoltaic silicon wafer production process of air
conditioning and purification system program.
1, slicing room, chamfering room, grinding chamber only temperature control requirements, set the air-cooled heat pump split cabinet air conditioner (PAC) to ensure room temperature requirements, indoor machine placed near the workshop, then duct, Double louvres side of the air way; outdoor unit placed on the roof. The air volume of the slicing chamber is larger, and the fresh air is supplemented by the direct evaporative heat pump type roof air conditioner S1-1 and S1-2. (Air dust counting efficiency: ≥ 60%, for ≥ 1μm particles), the same roof-type air conditioner to be set up two-stage filter, air-cooled heat pump split cabinet air conditioner back air outlet at the air filter Device.
2, the furnace room, BSD room only temperature control requirements, set the air-cooled electric sub-cabinet air conditioner (PAL) to ensure that the room temperature requirements, indoor machine placed near the workshop, then the wind pipe, Air way; outdoor unit placed on the roof. The new wind is pressurized by the adjacent clean room. The workshop has dustproof requirements, air-cooled electric cabinet cabinet air conditioner back to the outlet at the mid-effect filter (atmospheric dust counting efficiency: ≥ 60% for ≥ 1μm particles).
3, grinding room inspection room temperature and humidity control requirements, set the air-cooled electric sub-cabinet air conditioner (PAL) to ensure that the room temperature requirements, the indoor unit placed near the workshop, then the wind pipe, Air way; outdoor unit placed on the roof. The new wind by the new air unit (MAU-1, 2) after treatment, connected to the air duct to the room, the relative humidity by the new fan unit to ensure. The fresh air unit is shared with the purification system. There are dustproof requirements in the workshop. The efficiency of the air filter is: ≥ 60%, for the ≥1μm particles, the fresh air unit has the coarse and medium efficiency filter.
and circulating air conditioning unit (AHU) refrigerant with 6-11 ℃
chilled water, heating with 0.2MPa steam, humidification with 0.1MPa of
clean steam humidification, clean steam from the Pure water is produced by clean steam generator.
1, CP room purification level of 7, the number of ventilation to take 30 times / hour, CP room process equipment with more acid, the use of new air conditioning unit (MAU-3) + high efficiency filter outlet (HEP-ABOX ) Air conditioning. The air flow is: fresh air inlet - coarse filter - medium efficiency filter - preheater - surface cooler - heater - clean steam humidification - blower - air supply - efficient filter air supply - clean area.
2, ML room purification level of 7, the number of ventilation to take 30 times / hour, the use of fresh air unit (MAU) + cycle unit (AHU) + high efficiency filter outlet (HEP-ABOX) air conditioning. Fresh air received from other systems sharing MAU-1,2 new wind group.
3, CP / CVD room, LP / CVD room, clean packaging between the purification level of 6, the number of ventilation to 50 times / hour, the use of fresh air unit (MAU) + cycle unit (AHU) + high efficiency filter outlet ( HEP-ABOX) air conditioning. The fresh air is connected to the MAU-1,2 new wind group shared by other systems.
4,7 level, 6 of the clean room used in the form of airflow for the top of the high efficiency filter to send air supply, the room side of the louver outlet back to the wind. The air flow process is: the new return air mixing! In the air filter - the surface cooler - blower - air duct - efficient air filter outlet - clean area - room side of the blinds back to the outlet - return air pipe - new return air mixing.
5, cleaning room, quality inspection room purification level of 7, the use of fresh air unit (MAU) + cycle unit (AHU) + fan filter unit (FFU)) air conditioning. The airflow used in the form of the top FFU air supply, the room side of the louver outlet back to the wind. FFU full rate of 33%, washing room, quality inspection room on the NH4 +, SQx concentration requirements, the need to cycle unit (AHU) to add a chemical filter. The air flow between the five cleaners is: New return air mixing - Chemical filter (NH4 +) - Chemical filter (SQx) - Medium efficiency filter - Surface cooler - Blower - Air supply - Ventilation chamber - Fan Filter Unit (FFU) - Clean Area - Room Side Blind Leaf Return - Return Air Tube - New Air Mix. The fresh air is connected to the MAU-1,2 new wind group shared by other systems.
6, in addition to CP outdoor clean room required fresh air with two new air units (MAU-1, 2) centralized treatment, fresh air centralized treatment sent to the cycle unit (AHU). The air flow is: fresh air inlet - coarse filter - medium efficiency filter - preheater - surface cooler - heater - clean steam humidifier - blower - air duct - the circulating air conditioning unit (AHU).
7, CP room, ML room, the amount of acid used in the washing room is relatively more, CP room, ML indoor efficient filter to the outlet of the diffusion plate to be made of stainless steel plate, clean indoor FFU stencils need to use stainless steel Production.
8, the other attention should be noted that the quality of the inspection room according to the requirements of the process to be used black wall panels, black roof, the corresponding use of black return air, FFU stencils need to use black stencil.
IV、Automatic control of air conditioning system for purification system
fresh air unit (MAU-1, 2) uses a variable frequency fan, which controls
the frequency converter by the static pressure sensor on the main air
supply duct. In
the access to each air volume and positive pressure control cycle unit
(AHU) are set on the new air duct electric control valve, by the
positive pressure of the clean room to adjust the opening of the
electric control valve, the clean room of the positive pressure Does not change with the change of the exhaust volume of the
production equipment. The change of the opening degree of the electric
control valve causes the static pressure change on the main air duct,
and adjusts the fan frequency of the AHU-1 according to its set value to
achieve the control purpose.
1, clean room / clean room temperature and humidity control
Clean the production of dust-free workshop humidity is by the fresh air unit MAU-1,2 to ensure that the control of the new air blower state point, according to the air supply state set value to adjust the dry steam humidifier electric actuator and the surface cooler and heating The opening of the electric two-way valve on the return pipe. The dew point temperature DPT is continuously set by checking the indoor humidity sensitive element HE. Clean the production of dust-free workshop temperature is guaranteed by the cycle unit AHU, according to the indoor temperature to adjust the surface of the cooler return valve on the opening of the electric two-way valve.
2, cooling system control
Chilled water system using a pump, with the load control method to determine the chiller and the corresponding pump, cooling tower opening number. According to set the supply and return pressure to automatically control the supply and return water between the main line pressure flow bypass valve.