Operating Guide for the Air-Conditioning Automatic Control System at Factory No. 8 of Anhui Huamao

 

18. AX List of Intermediate Calculated Values for Analog Signals

You can set the manual condition to 【 1 ], set the manual value to the current value.

The control system monitors and compares the following parameters in real time.

Fresh air enthalpy value

Enthalpy of workshop return air

Enthalpy of process return air

Dew-point enthalpy

When the enthalpy of the fresh air is lower than the dew-point enthalpy calculated based on the workshop’s temperature and humidity, the controller instructs the air-conditioning system to switch into free-cooling mode, adjusting the workshop temperature by regulating the opening degrees of the fresh-air, return-air, and exhaust-air dampers.

When the enthalpy of the fresh air exceeds the dew-point enthalpy calculated based on the workshop’s temperature and humidity, and when the water temperature in the chilled-water supply tank at the chiller plant is lower than the calculated dew point, the controller instructs the air-conditioning system to switch to mechanical cooling mode. The workshop temperature is then adjusted by regulating the opening degree of the chilled-water valve. Meanwhile, if the enthalpy of the workshop's return air is lower than that of the fresh air, the opening degrees of the workshop's fresh-air, return-air, and exhaust-air valves will be: 0-100-0 ；

If the enthalpy of the process return air is higher than that of the fresh air, then the process fresh… - Return - The opening degree of the exhaust valve is 100-0-100 ；

The minimum setpoint for the supply-air fan speed can be appropriately reduced during winter, which has a significant effect on energy savings for air conditioning.

The return air ratio is the proportion of the return air fan speed to the supply air fan speed. The return air offset is a fixed deviation of the return air fan speed relative to the supply air fan speed. By adjusting these two parameters, you can control the positive and negative pressure within the workshop.

 

19. PID List

Proportional-integral controller—setpoints can be directly configured on the interface for each air-conditioned room.

The proportional gain, integral time, setpoint, manual mode conditions, and manual value for each controller can all be modified on this list interface. When adjusting the proportional parameters, be careful not to change the sign of the proportional gain; otherwise, it may result in reverse control action.

   When the enthalpy of the fresh air falls below the dew-point enthalpy, the free-cooling spray outlet temperature controller activates to adjust the fresh-air, return-air, and exhaust-air valves, thereby controlling the workshop temperature.

When the enthalpy of the fresh air exceeds the dew-point enthalpy and the chilled water temperature is lower than the dew-point temperature, the mechanical cooling spray outlet temperature controller activates to adjust the chilled water valve and thereby regulate the workshop temperature.

 

20.  Report

Click the 【Daily Report】 tab in the menu bar, select 【Air-Conditioned Room】 from the drop-down menu, and then choose the 【Date】 in the subsequent pop-up window to obtain the hourly parameter report for the current day.

 

21.  Curve

Click the [Curve] tab in the menu bar, select [Air-Conditioned Room] from the drop-down menu, and the pop-up window that appears will display the [Real-Time Parameter Trend Chart]. The [Grid Switch] radio button is used to choose whether to display the background grid.

[ □ T ， □ RH The checkbox is used to select whether to display the temperature or relative humidity curve.

Double-click 【 Y 】icon, In the dialog box that subsequently pops up, select.    [Lower and upper limits for parameter values], thereby modifying [ Y 】 The axis displays a scale.

At [Trend], in the [History] radio button box, click [History], then double-click [ X ] icon, and the historical curve [Start Date] will then pop up. / [Time], [End Date] / Time] Select the dialog box and choose the start and end dates for the completed historical curve. / After selecting the time, Click the [OK] button to start querying the process. This may take some time. Once the query is complete, the historical record curve will automatically pop up and display.

 

22.  Temperature and humidity setting

With 5# Take an air-conditioned room as an example:

On any workstation, in the menu bar [Air-conditioned room] Multiple choice [ 5# Air-conditioned room], enter [ 5# Air-conditioned Room interface: Double-click the text boxes on the right side of [Temperature] and [Humidity] to bring up blue text boxes (provided you are already logged in). 1 Level or 0 Level permissions—click the blue text box with your mouse, enter the desired data, and press the Enter key to confirm and complete the setting.

 

23.  Front spinning air-conditioning room adjustment

Pre-spinning air-conditioned room KT1，2，3 The volume of return air depends on the number of dust removal units that are turned on and the airflow rate of each dust removal fan.

The control system automatically monitors the on/off status of each dust removal unit, thereby calculating the basic rotational speed of the supply air fan. On this basis, the workshop differential pressure controller adjusts the system according to the differential pressure values collected by the differential pressure transmitters located inside and outside the workshop. +/- The output from the air supply offset range is superimposed onto the basic speed of the air supply fan to determine the final air supply speed, thereby avoiding excessive positive pressure in the spinning workshop caused by the start-up and shutdown of the dust removal unit. / Negative pressure.

 

With 1# Take the air-conditioned room as an example. ：

Unlike post-spinning, AX The nth item in the list 124 The manual condition for the item [Minimum Speed of Supply Air Fan] is [ 0 】, rather than 【 1 ], the minimum rotational speed is not set artificially, but rather... PLC The airflow adjustment range of the workshop differential pressure controller, determined automatically based on the return air volume of the dust removal unit, is shown below. AX The nth item in the list 126 Item [Airflow Offset]: The differential pressure setpoint for the workshop can be configured on the front spinning air-conditioning room interface. It is recommended to set it to slightly positive pressure.

 

Currently, the front spinning air-conditioning room is facing... 2 One question:

First, the air supply fan’s frequency converter is too old and cannot adapt. 40HZ The above rotational speed;

Second, the absence of a guide vane at the air supply outlet results in excessively high wind speeds in the area directly below the outlet, disrupting the cotton sliver. Therefore, the 【minimum speed of the supply fan】 can also be set manually. In this case, its 【manual condition】 can be set to 【 1 ], then the [minimum speed of the supply air fan] is fixed at the [manual value].

 

24.   Dust cage differential pressure and dust collection fan

With 5# Take an air-conditioned room as an example:

6 Dust of Taiwan / The dust collection fans are distributed across three spaces, so there are three dust cage differential pressure transmitters installed. AX In the list 535，537，539 The items are the first. 1，2，3 Dust collection cage / Dust collection fan start-up setpoint, AX In the list 536，538，540 The items are the first. 1，2，3 Dust collection cage / Hysteresis for dust collection fan shutdown. When the pressure difference across a particular dust cage exceeds the set value, the corresponding dust cage... / The dust collection fan starts to cycle on and off periodically, the dust cage. / See the timer list for the dust collection fan’s on/off cycle settings. 548-553 Item.

 

25 PM2.5 With fresh air filtration

There is one on the south side and one on the north side of the workshop, respectively. PM2.5 Transmitter, fine yarn air-conditioned room KT5，6 Shared North Side PM2.5 Parameter, fine yarn air-conditioned room KT9，10，11，14 Shared south side PM2.5 Parameter.

 

With 5# Take an air-conditioned room as an example:

AX The nth item in the list 533，534 Respectively PM2.5B Alarm trigger setpoint and alarm hysteresis. When outdoors PM2.5 When it exceeds the set value,

DX The nth item in the list 550 Item PM2.5 The ultra-high alarm will be triggered.

  Fresh air PM2.5 The parameter background color will turn red,

The fresh-air damper for unfiltered air will be closed.

The opening of the fresh air damper will be increased to its original size. 1.5 Twice,

5# 、 9# 、 10# The same goes for air-conditioned rooms.

 

With 11# Take an air-conditioned room as an example:

AX The nth item in the list 1108，1109 Respectively PM2.5B Alarm trigger setpoint and alarm hysteresis. When outdoors PM2.5 When it exceeds the set value,

DX The nth item in the list 1102 Item PM2.5 The ultra-high alarm will be triggered.

Fresh air PM2.5 The parameter background color will turn red,

  The non-filtered fresh air isolation damper will close.

The fresh-air filter isolation damper will open, and the blades of each isolation damper will turn red.

14# The same goes for air-conditioned rooms.

 

26 Humidity first

With 4# Take an air-conditioned room as an example:

DX The nth item in the list 421 Humidity takes priority; manual conditions always default to [ 1 】, when the manual value is set to 【 1 】time, then the current value is set to 【 1 ], at this point, even with the spray pump turned off, the workshop’s relative humidity still exceeds the standard. Under free-cooling conditions, even if the temperature surpasses the set value, Or, under mechanically cooled conditions, even if the enthalpy of the fresh air is lower than that of the return air, PLC The opening of the new return air damper will continue to be gradually reduced until the relative humidity in the workshop drops to the set value.

If the humidity priority current value is 【 0 ], if the workshop's relative humidity exceeds the standard, PLC In the end, only the sprinkler pump was shut down. 1 Various means.

Under free-cold conditions, new / The opening degree of the exhaust damper is determined by the 【free-cooling spray outlet temperature controller】.

Under mechanical cooling conditions, PLC The new and exhaust air damper positions—whether fully open or fully closed—are determined by comparing the enthalpy values of the fresh return air.

 

With 5# Take an air-conditioned room as an example:

DX The nth item in the list 551 Humidity takes priority; manual conditions always default to [ 1 】, when the manual value is set to 【 1 】at that time, the current value is set to 【 1 ], at this point, the bypass ventilation valve remains closed. If, under the condition that the spray pump is turned off, the relative humidity in the workshop still exceeds the standard, even if the temperature surpasses the set value under free-cooling conditions, Or, under mechanically cooled conditions, even if the enthalpy of the fresh air is lower than that of the return air, PLC Will continue to gradually reduce new... / Open the exhaust damper until the relative humidity in the workshop drops to the set value.

If the humidity priority current value is 【 0 ], if the relative humidity in the workshop still exceeds the standard even with the spray pump turned off, PLC The bypass ventilation valve will be gradually opened. Under free-cooling conditions, new... / The opening degree of the exhaust damper is determined by the 【free-cooling spray outlet temperature controller】. Under mechanical cooling conditions, PLC The new [air] is determined by comparing the enthalpy values of the fresh return air. / Is the exhaust damper fully open or fully closed?

 

27.  Free cooling and mechanical temperature control

With 5# Take the air-conditioned room and the refrigeration station as examples:

5# Air-conditioned room AX In the list

501 For Fresh air enthalpy value

503 For dew-point enthalpy value

514 For 1# Enthalpy of workshop return air

515 For 2# Enthalpy of workshop return air

516 Enthalpy value of process return air

521 To calculate the dew point

When 5# After the set values for temperature and humidity in the air-conditioned workshop are determined, the controller automatically calculates the corresponding dew point and dew-point enthalpy. The controller continuously compares the fresh-air enthalpy with the dew-point enthalpy:

 

If the enthalpy of the fresh air is less than the dew-point enthalpy. The controller directs the air conditioning system to operate in free-cooling mode. At this moment, DX In the list 503 Start the ice machine. And 502 The current values for the mechanical cooling mode are all 【 0 ], the free cold spray outlet temperature controller adjusts the process and the workshop’s new - Return - The opening degree of the exhaust valve is controlled.

When the workshop temperature exceeds the set value, the free-cooling spray outlet temperature controller first fully opens the supply and exhaust air dampers for the process (while simultaneously partially closing the return air damper). If the workshop temperature still remains above the set value, the controller then further increases the opening of the supply and exhaust air dampers for the workshop (while simultaneously further reducing the opening of the workshop return air damper).

When the workshop temperature falls below the setpoint, the free-cooling spray outlet temperature controller first partially closes the fresh-air and exhaust-air dampers in the workshop (while simultaneously opening the return-air damper). If the workshop temperature still remains below the setpoint, the controller then further partially closes the process fresh-air and exhaust-air dampers (while simultaneously opening the process return-air damper). Meanwhile, the minimum speed of the sprinkler pump is set to... AC List 524 Sprinkler pump free-cooling minimum setpoint (default value) 1 ) Decision.

 

If the enthalpy of the fresh air is higher than the dew-point enthalpy, After a delay ( TI List 504 Ice machine start delay: Default value 600 seconds later, DX In the list 503 The current value of the ice machine is 【 1 ], the controller simultaneously compares the water temperature of the chilled water supply main that has been collected ( AI List 406 Ice water temperature), when this water temperature exceeds the set dew point temperature ( AC List 521 When calculating the dew point, it indicates that the water temperature is too high and the mechanical cooling conditions are not met. A pop-up message will appear on the air-conditioned room interface. Please turn on the air conditioner! 】Tip: At this moment DX In the list 502 Mechanical cooling mode The current value is 【 0 】, If the water temperature of the main supply pipe at the chilled water station is collected ( AI List 508 The ice water temperature is lower than the set dew point temperature. AC List 521 Calculate the dew point), after a delay ( TI List: 506 Mechanical cooling mode start delay: Default value 600 seconds) DX In the list 502 Mechanical cooling mode The current value becomes 【 1 ], at this point, the controller instructs the air conditioning system to switch to mechanical cooling mode; the air conditioning room interface [ Please turn on the air conditioner! The prompt has disappeared.

PID In the list 504 The mechanical cold spray outlet temperature controller is activated and adjusted. AO In the list 505 The ice-water valve adjusts the workshop temperature. Meanwhile ， The minimum speed of the sprinkler pump is determined by: AC List 525 Minimum setpoint for mechanical cooling of the sprinkler pump (Default value) 75 ) Decision 。 At this point, if the enthalpy of the workshop return air is lower than that of the fresh air, then the workshop’s fresh... - Return - The opening degree of the exhaust valve is 0-100-0 ; If the enthalpy of the process return air is higher than that of the fresh air, then the process fresh... - Return - The opening degree of the exhaust valve is 100-0-100.

It is worth noting that, under mechanical cooling mode, It is advisable to... AX Under the list 527 Set the minimum speed setting for the supply air fan to a lower value, adopt a large temperature difference and small air volume supply mode, and use chilled water to thoroughly cool and dehumidify the air. Subsequently, adjust the relative humidity in the workshop by increasing or decreasing the air volume.

 

As the seasons change, the enthalpy of the fresh air drops below the dew-point enthalpy corresponding to the set temperature and humidity values in the workshop. The controller then initiates a delay ( TI List: 505 Default delay time for ice machine shutdown   600 seconds later, DX In the list 503 The current value of the ice machine startup has changed to 0 , turn off the refrigeration system, After a further delay ( TI List: 507 Default delay value for mechanical cooling mode shutdown 600 seconds later, DX In the list 502 Mechanical cooling mode Returns the current value 0 The controller instructs the air conditioning system to return to free-cooling mode, closes the chilled-water valve, and switches the workshop’s temperature control cooling source to outdoor fresh air.

 

28.   Post-spinning - Heat transfer in the front spinning process

4# When the temperature in the air-conditioned room falls below the set value during winter, PLC First, gradually close the fresh-air and exhaust-air dampers, then gradually open the connecting duct. 5# The regulating damper on the return air duct of the fine spinning process in the air-conditioned room should be adjusted until the temperature in the roving workshop rises back to the set value. When the temperature in the roving workshop exceeds the set value, PLC First, close the return air damper.