JPH0345291B2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a hot experimental facility (a facility where experiments are conducted on substances and microorganisms that are harmful or dangerous to the human body).
Room-to-room micro-differential pressure control and ventilation power-saving control in facilities that require high airtight performance, such as radioactive waste processing facilities, and which have draft chambers installed for experiments or processing operations. This invention relates to power-saving control equipment for room-to-room micro-differential-pressure ventilation that enables simultaneous implementation of the following.

Air conditioning equipment for facilities that require a high level of airtightness, such as hot experimental facilities and radioactive waste processing facilities, is required to supply clean air, purify exhaust air, and to set a constant air volume in each room. Maintaining room pressure is fundamentally important. Regarding the maintenance of constant air volume and constant room pressure in each room, if this cannot be maintained, the problem of cross contamination between rooms will occur. Conventionally, constant air volume and constant room pressure were maintained by installing constant air volume valves (commonly known as CVA units) in the air supply and exhaust ducts. However, when using this constant air volume valve,
It is unavoidable that pressure loss in the duct and filter system changes over time, causing balance fluctuations.
Furthermore, if supply and exhaust are stopped for a certain room due to cleaning work or other reasons, a larger amount of air than the set amount of air will be distributed to other rooms, making it difficult to maintain a constant air volume and constant room pressure. Additionally, there is a basic problem in that this constant air flow valve is unsuitable due to its structure for control in places where static pressure of 70 mmAq or more cannot be applied to the CAV valve. Furthermore, if a draft chamber that requires forced exhaust is installed in the room, a large negative pressure will suddenly occur in the room if this draft chamber is used, and the Pressure control becomes complicated. Also, regarding the exhaust side fan of the draft chamber, if the exhaust capacity is ensured when all draft chambers are in use and the design capacity is maintained at all times, power will be wasted if there is an unused draft chamber. become.

The present invention was made with the aim of solving such problems, and is intended for facilities that require high airtight performance, such as hot experimental facilities and radioactive waste processing facilities, and that has facilities for experiments or processing operations in the room. The purpose of the present invention is to provide a small differential pressure ventilation power saving control equipment that can simultaneously perform small differential pressure control between rooms and power saving control for ventilation in a facility where a draft chamber is installed. That is, as shown in the drawing, the power-saving control equipment for ventilation with slight differential pressure between rooms of the present invention includes one or more draft chambers 2 in one room 1, and whether or not the draft chambers 2 are used can be controlled. In the air supply/exhaust equipment that maintains the differential pressure between the room 1 and the outdoors constant regardless of the situation, and at the same time controls the air volume of the exhaust fan 3 and the fan 10 according to the usage status of the draft chamber 2, each draft chamber 2
An on-off damper 5 is interposed in the exhaust duct 4 of the chamber, and the on-off damper 5 is opened and closed based on a signal from a sensor 6 that detects whether each draft chamber 2 is used. A differential pressure adjusting damper 8 is installed in the duct 7, and the opening degree of the differential pressure adjusting damper 8 is controlled based on a signal from a differential pressure detection sensor 9 that detects the differential pressure between indoor and outdoor. A variable air volume blower is used as each fan 10, and the air volume of the exhaust fan 3 and the fan 10 is controlled based on the usage status of each draft chamber 2, the change in pressure loss over time of the air supply and exhaust system, and the differential pressure between indoor and outdoor. It is characterized by being equipped with a microcomputer 11 for this purpose.

FIG. 1 shows that in addition to a chamber 1 in which a plurality of draft chambers 2 are installed, chambers for other purposes such as 1a, 1b, and 1c are arranged side by side, and supply air is distributed from an air blower 10 to all of these chambers. This shows an example in which the exhaust air from all rooms is collected and exhausted from the exhaust fan 3 at once, and the other rooms 1a to 1c are maintained at a constant air volume and constant pressure by the constant air volume valves 13. It's becoming like that. In the equipment of the present invention, supply air is introduced into the chamber 1 via the differential pressure regulating damper 8, and the exhaust air inside the chamber 1 is passed through the draft chamber 2 if it is in use, and then through the draft chamber 2. If all of the air is not in use, it is guided to the filter unit 14 through the spare exhaust duct 4a and then exhausted to the outside of the system by the exhaust fan 3. The opening degree of the differential pressure adjustment damper 8 is controlled based on a signal from a differential pressure detection sensor 9 that detects the differential pressure between the inside and outside of the room 1, for example, the differential pressure between the room and the hallway. As will be described later, this differential pressure adjustment damper 8
When the fully open state is reached, the fully open signal is input to the microcomputer 11.

Each draft chamber 2 has a sufficient internal space for processing and experimenting with materials that must avoid contamination, such as radioactive materials, and when in use, the door is opened to the extent that a specified air velocity can be secured at the opening and closing section. 16 and then manually close the opening/closing door 16 when use is finished. A sensor 6 is attached that operates in accordance with each opening/closing operation of the opening/closing door 16 or in conjunction with a separately provided on/off switch, and this sensor 6 detects whether each draft chamber 2 is in use or not. To detect. The detection signal is sent to the relay board 17, which slowly opens and closes the on-off damper 5 installed in the exhaust duct 4 of each draft chamber. The on-off damper 5 is an AC motor-driven damper whose opening/closing time can be adjusted from 20 seconds to 20 minutes, and its opening/closing operation is performed as slowly as possible in order to suppress fluctuations in room pressure caused by its opening/closing. and,
This on-off damper 5 is equipped with a fully open limit switch and a fully closed limit switch, and it is monitored whether the on-off damper 5 is fully open or fully closed.

On the other hand, the exhaust fan 3 and the fan 10 are variable air volume fans whose air flow can be changed steplessly, more specifically, fans or blade pitch angles that change the rotational speed of the motor of each fan in accordance with a control signal. A blower or the like is used that changes the temperature using a control signal. The figure shows an example in which the rotational speed of the blower motor is changed in accordance with a control signal by adding an inverter unit 18 that changes the power supply frequency. Inverter unit 1 for each blower
A control signal to the microcomputer 8 is output from the microcomputer 11 based on a control sequence described later. The input to the microcomputer 11 is provided by the relay board 17.
The signals include a usage status signal of the draft chamber, a signal for fully opening the differential pressure adjustment damper 8, and a signal for measuring pressure loss over time in the duct filter system from the wind speed detector 20 attached to the main exhaust duct.

Specific examples of sequence contents and calculation contents of the control system of the present invention are shown below.

"Sequence content of the control system of the present invention" (1) Monitor characteristics representative of the usage status of the draft chamber in the room 1. The characteristics representative of the operating conditions are the opening/closing sensor 6 of the opening/closing door of the draft chamber (specifically, a limit switch or proximity magnetic switch installed on the opening/closing door and the guide rail of the door, or a manual switch turned on/off by the experimenter). To detect.

(2) Information from the sensor 6 is received by the relay board 17 and used as an input signal to the microcomputer 11. This input signal is a voltage-free contact. The input signal received by the relay board 17 causes the corresponding on-off damper 5 to operate as slowly as possible by a motor drive.

(3) The differential pressure setting between Room 1 and the hallway will be determined by the static pressure balance of the air supply and exhaust ducts to Room 1. At this time, the static pressure in the air supply/exhaust system changes in proportion to the square of the air volume, so minute adjustments to the air supply volume and exhaust volume are required. This fine differential pressure control is performed by adjusting the opening degree of the differential pressure adjusting damper 8 in the air supply system. When the damper 8 is fully opened during this opening adjustment, a signal from a fully open limit switch installed on the damper 8 is used as an input signal to the microcomputer 11.

(4) In order to measure the decrease in air volume due to changes in pressure loss in the duct system (particularly filters) over time, a wind speed detector or air volume detector 20 is installed at the collecting part of the exhaust system or on the downwind side of the filter unit 14, and its analog signal is This is an input signal to the microcomputer 11. This wind speed or air volume detector 20
The signal is 0~5V (DC) or 4~20mA (DC)
It is input as a signal, and after sampling 10 times during the sampling time and excluding the minimum and maximum values by calculation by a microcomputer,
Find the average air volume using the 8 sampling values.

(5) The air supply/exhaust volume of room 1 changes depending on the usage status of the draft chamber, but in order to maintain the minimum air volume (for example, 1150m ³ /Hr), the number of draft chambers + at least one exhaust A vent is installed to allow indoor air to be sucked in even when the draft chamber is fully closed.

``Contents of calculations performed by the control system of the present invention'' The flowcharts when this calculation is performed by a microcomputer are shown in FIGS. 3 to 6. The numbers shown as procedures in the figure correspond to the numbers in the explanation section below _.
control to start up the system within the time of
4 to 6 show the main control operation repeated at the scanning timer Δt time period following FIG. 3.

(1) Calculate the required air supply/exhaust volume of the system in advance by multiplying the air supply/exhaust volume per draft chamber in room 1 by the operating condition. However, the required air supply amount and required exhaust amount for rooms other than room 1 are secured as fixed amounts.

Required supply air volume Q = Q _B + _i 〓 ⁱ⁼¹ q _i ×a _i +Q _c Q _B ; Supply air volume in other rooms q _i ; Supply air volume per draft chamber _ai Parameter indicating usage status In use: 1 Not in use; 0 Q _c ; Corrected air volume In this case, when the full open limit switch of the differential pressure control valve 8 installed on the air supply side is on, the corrected air volume Q _c
is added to the required supply air volume. When the full open limit switch is OFF, Q _c =0. When adding the corrected air volume, it is checked each time that the supplied air volume does not exceed the design air volume of the blower 10, and if it does, it is set as the design air volume.

Required exhaust air volume R = R _B + _i 〓 ^{i = 1} q _i × a _i However, R _B ; Exhaust air volume in other rooms (2) When the sensor 6, which represents the usage status of the draft chamber, issues an open signal, If the full-open limit switch of the on-off damper 5, which slowly opens and closes the motor drive, is also open, the on-off damper is fully open, but if the full-open limit switch is closed, the on-off damper is not open, as illustrated in Figure 2. It's on the way. Similarly, if 6, which represents the use state of the draft chamber, issues a close signal and the fully closed limit switch of the on-off damper 5, which slowly opens and closes the motor drive, is also closed, the on-off damper is fully closed. If the full-close limit switch is open, the on-off damper is in the middle of closing, as also shown in FIG. The time from full open to fully closed of the on-off damper, which opens and closes slowly, is divided into at least 10 equal parts, and the air volume in each equal part is stored in advance in the microcomputer. The exhaust air volume per bar can be calculated using the following formula.

q _i = q ₀ × E _r (N) However, q ₀ is the exhaust air volume per draft chamber when the on-off damper is fully opened, and E _r (N) is 10
The air volume ratio to the air volume at the Nth fully open position when divided into equal parts is shown.

(3) Calculate the total pressure loss and rotation speed of the air supply system ducts, air conditioners, and other parts using the required air supply air volume.

Air supply system pressure drop ΔP _Q0 = ΔP _Q1 +ΔP _Q2 +ΔP _F1 ...(Blower static pressure at design) ΔP _Q = ΔP _Q1 +ΔP _Q2 (Q/Q ₀ ) ² +ΔP _F1 (Q/Q ₀ ) ...(During operation) ) However, ΔP _Q1 is from the air blower 10 to the CAV unit 13.
A fixed amount of pressure drop in the duct up to chambers 1, 1a, 1b, and 1c containing.

Q ₀ is the air supply volume of the blower at the time of design.

ΔP _Q2 is calculated from the air supply fan 10 by subtracting ΔP _F1 and ΔP _Q1 from the maximum (designed) pressure drop ΔP _Q0 in the air supply system.
Room 1, 1a, 1b containing CAV unit 13,
Pressure loss in the duct up to 1c.

ΔP _F1 indicates the design final pressure drop of the filter unit installed on the air supply side.

The number of rotations of the blower 10 is calculated relative to the amount of air supplied.

Air blower rotation speed (feedforward control) N _Q = K _Q N _Q0 × (ΔP _Q / ΔP _Q0 ) ^1/2 → 4 to 20 mA signal output Here, N _Q0 is the design of the electric motor of the air blower 10 K and _Q indicate the rotation speed and the air supply air volume coefficient.

(4) Calculate the total pressure loss and rotation speed of the exhaust system duct, filter unit, and other parts using the required exhaust air volume.

Exhaust system pressure drop ΔP _R0 = ΔP _R1 + ΔP _R2 + ΔP _F2 ... (static pressure of exhaust fan at design) ΔP _R = ΔP _R1 + ΔP _R2 (R/R ₀ ) ² + ΔP _F2 (R/R ₀ ) ... (operation) However, ΔP _R0 is the pressure drop between chambers 1a, 1b, 1c, chamber 1 and the exhaust fan 3 including the filter unit 14, and _R0 is the displacement of the exhaust fan at the time of design.

ΔP _R1 is the fixed pressure drop of the duct system from rooms 1a, 1b, 1c and room 1 to the exhaust fan 3, and ΔP _R2 is the maximum (designed) pressure drop of the air supply system ΔP _R0 to ΔP _F2 and ΔP _R1 . Excluding exhaust fan 3 to room 1
The duct pressure loss between a, 1b, 1c and chamber 1, ∆P _F2 , represents the design final pressure loss of the filter unit installed on the exhaust side.

The rotation speed of the exhaust fan 3 with respect to the exhaust air volume R is calculated. Exhaust fan rotation speed (feedforward control) N _R = K _R N _R0 × (ΔP _R / ΔP _R0 ) ^1/2 → 4 to 20 mA signal output Here, N _R0 is the design of the electric motor of exhaust fan 3 The rotation speed and K _R indicate the exhaust air volume coefficient.

(5) For rising feedforward control,
The rotational speed of the exhaust fan 3 is controlled in feedback manner by checking whether the exhaust air volume Rm measured by the wind speed detector 20 matches the required exhaust air volume R.

At that time, set dead zones L ₁ and L ₂ around the required air volume. Then, the deviation e is calculated using the following equation.

e = Rm - R (measured value of exhaust air volume - calculated value of exhaust air volume) Under conditions where the deviation is e < L ₁ or e > L ₂ (when it is outside the set dead zone), the rotation speed of the exhaust fan after correction is calculated using the following formula.

N _R (t)=N _R (t-Δt) +{k+Δt/T _i +T _D /Δt}e(t) −{k+2T _D /Δt}e(t-Δt) +{T _D /Δt}e( t-2Δt) Here, N _R (t) indicates the calculated value of the rotation speed of the exhaust fan at time t. N _R (t-Δt) is the rotation speed of the exhaust fan calculated at scanning time Δt before time t, and e(t), e(t-
Δt) and e(t−2Δt) are time t and (t
−Δt) time and (t−2Δt) time. K is a proportional constant for feedback control, T _i is an integral time, T _D is a differential time, and Δt is a scanning time. The scanning time means the time interval for measuring the deviation, and in this case it is set to 1 second.

(6) Make corrections at each control time until the deviation value falls within the specified dead zone. This makes it possible to follow the reduction in air volume due to filter clogging.

(7) After completing the operation in (5) above, monitor the usage status of the draft chamber and if there is any change, Q=Q _B + _i 〓 ⁱ⁼¹ q _i ×a _i +Q _c R=R _B + _i 〓 ⁱ⁼¹ By calculating q _i ×a _i , the air volume is suppressed and the process returns to step (2).

As described above, when the power-saving control equipment for room-to-room differential pressure ventilation of the present invention is operated, it is necessary to maintain high airtightness in a room where there is a forced exhaust draft chamber whose usage conditions change. It is possible to maintain the room at a constant set differential pressure, prevent cross-contamination between rooms, and at the same time reduce the power of the exhaust fan to the minimum necessary while keeping up with the decrease in air volume due to changes in pressure loss over time in the duct system where the filter is located. consumption can be limited to a limited amount. In addition, even when the air supply is stopped for sterilization or decontamination, the differential pressure in the space is always maintained constant, eliminating the risk of cross-contamination. Control and ventilation power saving control can be carried out with automatic control.

[Brief explanation of drawings]

Fig. 1 is an equipment layout system diagram showing an embodiment of the power-saving control equipment for room differential pressure ventilation of the present invention, Fig. 2 is a diagram for explaining the opening/closing state of the on-off damper, and Figs. 3 to 6 are 1 is a series of flowcharts showing an example of calculations performed by a microcomputer when controlling the equipment of the present invention. 1... Highly airtight room, 2... Draft chamber,
3...Exhaust fan, 4...Exhaust duct, 5...On/off damper, 6...Draft chamber usage state detection sensor, 7...Air supply duct, 8...Differential pressure adjustment damper, 9...Differential pressure detection Sensor, 10...Blower, 11...Microcomputer, 17...Relay board, 18...Inverter unit.

Claims (1)

[Claims] 1 One or more draft chambers 2 are provided in one chamber 1, and the differential pressure between the chamber 1 and the outside is maintained constant regardless of whether or not the draft chamber 2 is used, and at the same time the draft chamber 2 is used. In the supply and exhaust equipment that controls the air volume of the exhaust fan 3 and the fan 10 according to the situation, an on-off damper 5 is installed in the exhaust duct 4 of each draft chamber 2, and this on-off damper 5 is installed in the exhaust duct 4 of each draft chamber 2. Sensor 6 that detects whether it is being used
The opening and closing operations are performed based on the signals from the chamber 1.
A differential pressure adjusting damper 8 is interposed in the air supply duct 7 to the air outlet, and the opening degree of the differential pressure adjusting damper 8 is controlled based on a signal from a differential pressure detection sensor 9 that detects the differential pressure between indoor and outdoor. Variable air volume fans are used as the exhaust fan 3 and the fan 10, and the air volume of the exhaust fan 3 and the fan 10 is controlled based on the usage status of each draft chamber 2, the pressure loss over time of the air supply and exhaust system, and the indoor-outdoor pressure differential. A power-saving control device for ventilation with a slight differential pressure between rooms, which is equipped with a microcomputer 11 for controlling the ventilation based on the following.