Vacuum Unit Water Management for Steam Sterilizer
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Solution Overview
Problem
Steam sterilizers require large quantities of cooling water to maintain efficient operation of vacuum systems, leading to excessive water usage and environmental concerns, especially in arid regions, due to the increase in water temperature from steam and condensate.
Innovation Solution
A vacuum unit with an ejector, pump, and reservoir system that includes water control valves and a perforated dispersion tube to efficiently manage water flow and temperature, allowing for reduced water consumption by introducing fresh water directly into the pump inlet and using a sensor-responsive valve to control discharge temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cool water is continuously added to the reservoir to maintain efficient ejector operation, then the ejector operates efficiently at lower temperatures, but the total volume of water in the system continually increases requiring discharge to drain
Solution Approach 1:
The water supply system is segmented into multiple controlled pathways with individual valves (first water supply passage with first valve, second water supply passage with second valve). This allows independent control of water addition to the pump versus direct addition to the drain, enabling precise management of water volume while maintaining cooling efficiency.
Solution Approach 2:
The system changes the control parameter from continuous water addition to regulated water addition through sensor-responsive valves. The temperature sensor and sensor-responsive valve dynamically adjust water flow based on actual temperature conditions, optimizing the balance between cooling efficiency and water consumption.
2Temperature
If large quantities of cooling water are added to bring effluent temperature down to required level, then effluent temperature requirement is satisfied, but significant water consumption occurs
Solution Approach 1:
A temperature sensor is installed in the drain conduit to provide real-time feedback on effluent temperature. The sensor-responsive valve uses this feedback to automatically regulate the second water supply passage, adding cooling water only when and where needed to maintain temperature below 60°C, thereby minimizing water consumption while satisfying temperature requirements.
Solution Approach 2:
The system uses its own effluent stream for cooling by introducing fresh water directly into the drain conduit where it mixes with hot effluent. This self-cooling approach eliminates the need for separate large-volume cooling systems and reduces overall water consumption.
3Stress or pressure
If water is circulated through the ejector to produce vacuum, then vacuum is generated to remove air and condensate, but water temperature increases due to steam and hot condensate introduction
Solution Approach 1:
Cool water is introduced into the pump inlet before water enters the ejector through the first water supply passage and first valve. This preliminary cooling ensures water enters the ejector at an optimal temperature for vacuum generation, counteracting the heating effect of steam and condensate mixing.
Solution Approach 2:
The pump acts as an intermediary device that receives pre-cooled water from the reservoir and delivers it to the ejector. This intermediary role allows temperature control at the source (reservoir) to be effectively transmitted to the ejector, maintaining optimal operating conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves a high vacuum level efficiently with significantly reduced water usage, maintaining discharge temperatures below 60° C. without the need for refrigeration, thus minimizing water consumption and environmental impact.
Implementation Method 1
The ejector passage has a restriction for generating a vacuum at the steam inlet when water flows through the ejector passage from the ejector inlet to the ejector outlet
Implementation Method 2
The pump has a pump inlet connected to the first reservoir outlet and a pump outlet connected to the ejector inlet. The pump produces a flow of water through the ejector passage.
Implementation Method 3
the reservoir inlet comprises a perforated tube having perforations, and connected to the ejector outlet conduit, for dispersing fluid drawn from the steam inlet into the reservoir
Implementation Method 4
a temperature sensor is located in the drain conduit, downstream from said direct connection, and the second valve is a sensor-responsive valve, connected and responsive, to the temperature sensor
Data Source
AI summary
In a vacuum unit for use in drawing a vacuum on a steam sterilizer, a pump circulates water through an ejector and a reservoir. Fresh water is injected at the pump inlet to maintain a low temperature in the ejector so that it can operate efficiently. Excess water is taken from a location adjacent the bottom of the reservoir through an internal dip tube, and passed through a U-shaped conduit that serves as a condensate trap. To maintain the water discharge temperature below a predetermined level, fresh water is injected into the U-shaped conduit through a valve controlled by a temperature sensor downstream from the water injection point.