WO2006078773A2

WO2006078773A2 - Heat recovery system for hatcheries

Info

Publication number: WO2006078773A2
Application number: PCT/US2006/001830
Authority: WO
Inventors: Michael E. Hurd
Original assignee: Chick Master International, Inc.
Priority date: 2005-01-19
Filing date: 2006-01-19
Publication date: 2006-07-27
Also published as: WO2006078773A3

Abstract

One or more heat exchangers under control of a control system (130) are utilized to heat incoming fresh air by transferring heat from heated water returned from the incubation process and exhaust air to the incoming fresh air. In this manner the amount of energy that must be supplied to cool the return water and to heat the fresh air is reduced.

Description

HEAT RECOVERY SYSTEM FOR HATCHERIES

Technical Field

The invention pertains generally to the field of egg incubators and hatcheries and in particular to environmental control systems for same.

Background

For optimal results the temperature and humidity within a hatchery must be precisely controlled. This means that the heat generated by incubating eggs and equipment needs to be dissipated to provide an ambient temperature of about 100 degrees Fahrenheit. There are two major sources of heat energy in most hatcheries, air being exhausted from setters and hatchers and water returning to a chilling compressor after completing a cooling loop through the setter and/or hatcher rooms. Water and/or air cooling are used to control the temperature in the hatchery.

Hatcheries typically run around the clock and around the calendar; and depending on the ambient temperature at any given time, large amounts of energy can be expended to heat or cool the fresh air that is taken in for the purpose of cooling the hatchery. The cooler the supply air, the greater the energy cost to heat that air to an acceptable level for introduction into a setter or hatcher. While the purpose of the air is cooling, it must nonetheless be heated to a satisfactory level (usually around 80 degrees F) to prevent thermal shock to eggs when introduced into the setters/hatchers.

The use of water cooling for setters and hatchers in a hatchery provides full control over the humidity and helpful gas contents of the setters and hatchers. Statistics support the beneficial aspects of controlled humidity and carbon dioxide presence as it applies to hatch percentages, hatch uniformity, chick size and farm growth and mortality figures.

Water cooling has historically depended upon the use of compressors to remove heat from the cooling water after it completes its cycle through the setter and hatcher the temperature at which it returns defines the amount of heat energy that must be removed from the water before it begins its next loop. This energy is considered to be a loss because it does not contribute to the maintenance of the hatchery environment.

Summary

One or more heat exchangers under control of a control system are utilized to heat incoming fresh air by transferring heat from cooling water returning from the setters and hatchers and from exhaust air to the fresh air. hi this manner the amount of energy that must be supplied to cool the return water and to heat the fresh air is reduced.

Brief Description of the Drawings

Figure 1 is a schematic illustration of a hatchery heat recovery system constructed to one embodiment of the present invention;

Figure 2 is a flowchart outlining a method for controlling a water heat recovery coil according to an embodiment of the present invention; and

Figure 3 is a flowchart outlining a method for controlling a set of dampers that route air to an air to air heat exchanger according to an embodiment of the present invention.

Detailed Description

Referring to Figure 1, a schematic diagram of a hatchery 10 that includes a heat recovery system constructed according to one embodiment of the present invention is depicted. A conventional hatchery and its environmental controls are shown as well as the additional components needed to practice the described embodiment of the invention. The conventional components will be described first.

A typical hatchery includes several rooms including setter rooms 23 (each including multiple rows of setter machines (1-6)), hatcher rooms, and egg transfer, chick processing, chick handling and chick holding rooms. Each of these rooms is maintained at controlled temperature and humidity by an air handling unit 93. Each air handling unit 93 includes a main air moving fan 51 that moves air through a heat exchanger that has a description will focus on the air supplied to the setter room or rooms 23, but it will be apparent one of skill in the art that the air supplied to the other rooms in the hatchery can be similarly treated. In the setter incubator 23 incubating eggs are maintained in an optimal environment for hatching. The typical temperature of an incubating egg is about 104 degrees Fahrenheit and the setter incubator in maintained at a temperature of about 100 degrees Fahrenheit. This temperature differential between the eggs and the setter incubator temperature means that the air in the setter incubator must be cooled, usually with incoming air that is at about 80 degrees Fahrenheit. In typical installations, the sole means of heating or cooling the air supplied to the various rooms is via the hot or cold water heat exchangers, 15, 16.

The setter room 23 is adjacent to a machine chamber 24 that houses equipment associated with the incubation operation. Air can flow between the setter room 23 and the machine chamber 24 through a damper as shown. A plenum 26 on the machine chamber is in fluid communication with an exhaust duct that in conventional systems would route exhaust air pulled from the machine chamber by an exhaust fan 112 to the outside. The speed of the exhaust fan is controlled by a speed controller 119 that sets the fan speed based on a pressure differential (as determined by sensors Pl and P2) between air in the setter room 23 and air in the plenum 26 to maintain constant pressure in the setter room. In addition the position of a fresh air damper 45 is controlled by a damper controller 170 based on pressure in the setter room P3 and ambient pressure P4. It should be noted that in typical hatcheries, the damper 45 and exhaust fan 112 communicate directly with a fresh air intake and not the ductwork shown in Figure 1, which is part of the heat recovery system that will described later. According to the actual air demand of the incubators the damper can be controlled to allow more or less air re-circulated to a maintain the air pressure in the room to about 0.05" of water. The plenum 26 is normally constructed above a row of incubators. An extraction fan is controlled by the speed controller to extract the air from the room out of the roof of the building.

Cooling air is supplied to the setter room 23 from the air handler 93. The air in the setter room is re-circulated by controlling the damper 45 using an actuator 129. As shown schematically in Figure 1, a water chiller 17 is used to cool the water from setters water is returned to the chiller through warm water return pipe 85.

When the pressure in the setter room is below an optimal level as determined by pressure sensors P3 and P4 fresh air is mixed with the re-circulated setter room air as controlled by the damper 45. Both the fresh air and re-circulated air are passed over the heat exchangers 15, 16 for heating or cooling prior to entering the setter room.

Accordingly, in the conventional environmental control system, hot air was exhausted to the outside and setter room air and fresh air were either heated or cooled by a heat exchanger. Heat Recovery System

A typical hatchery that produces just over 3 million chicks per week generates (and exhausts through the roof or removes using water chillers) about 1100 KW of heat energy. In order to recover some of the heat losses incurred by conventional hatchery environmental control systems, according to the described embodiment of the present invention a heat recovery unit can be retrofitted to an existing hatchery installed or as part of a new hatchery. The heat recovery unit includes additional ducting, a primary heat recovery coil 30, a secondary air to air plate heat exchanger 20 and a controller 50 that are added to the conventional system as described below. The additional ducting features a universal mounting collar so that it can be coupled to existing air handling equipment.

As described above, a typical installation would have several air handling units mounted on the roof of the hatchery. To perform the retrofit, the air intake of each of the air handling units is coupled to a common air intake 91, which may run down the center line of the roof. Air intake is typically taken from the "clean" side of the hatchery building near the egg reception, hi some instances, it may be advantageous to install a primary air fan 94 to overcome the pressure drop across the primary heat recovery coil 30.

The primary heat recovery coil 30 is then mounted on the very front of the common air intake ducting assembly 91. The capacity of the coil 30 is selected based on the maximum output of the process and the capacity of chilled water system. A three port valve 99 modulates and controls the water volume through the heat recovery coil. As will be described in more detail below, warm water returning from the setters 99 and a pump 145 (with back up pump 146 also provided) that are controlled by the controller 50. The controller 50 causes warm water to flow through the warm water heat exchanger when the temperature of the incoming fresh air is less than the desired setter room temperature. After the warm water passes through the heat exchanger, it is routed to the chiller 17 via a warm water pipe 89 to a warm water tank 78. In this manner, the warm water from process is cooled n the primary coil 30 prior to entering the chiller, reducing the energy necessary to cool the water for supply through cold water supply pipe 81. The existing chilled water system is modified to include a second bypass water flow return line 187, which is connected via a regulation valve 220 to each row of setters or hatchers (hatchers not shown).

An air to air plate heat exchanger 20 is installed onto the air intake of each of the air handling units included in the retrofit. Recovery ducting 115 is connected to the exhaust fan 112 on the plenum 26 to route the heated exhaust air to the air plate heat exchanger 20. The air plate heat exchanger is sealed in place so that the fresh air flowing on one side is isolated from the exhaust air flowing on the other side. When the exhaust air is routed past the air plate heat exchanger, it heats the fresh air that is flowing by the other side of the plate before it mixes with the re-circulated hot air from the setter room.

For each air handling unit, the controller 50 controls the damper actuators 123, 125 and the valve/pump combination 99,145 based on the temperature of air in three zones of the system: exhaust air (from the temperature sensor T4), fresh air (from the temperature sensor Tl), and heated fresh air that has been heated by the primary heat recovery coil 30 (from the temperature sensor T2.) When the heated fresh air is below a set temperature, such as 80 degrees Fahrenheit, the controller routes heated exhaust air past the secondary air to air plate heat exchanger 20. When the heated fresh air is warm enough, the controller moves the bypass dampers 41, 42 so the exhaust air bypasses the air to air plate heat exchanger. When the fresh air is below a set temperature, such as 80 degrees Fahrenheit, the controller routes warm water to the primary heat recovery coil 30 using the valve 99 to heat the fresh air.

The controller 50 is a programmable logic controller, such as an Omron CJl, and has appropriate I/O modules for inputting the various temperatures, pressures, flow rates, valves and dampers as will be described below. The controller is also connected to a touch screen 59 that allows the user to set various parameters and a computer system 54. In addition to providing a redundant user interface for inputting parameter settings, the computer system 54 is used to make a number of calculations regarding the energy savings, provide real time data including an overview of the heat recovery process, and calculate and display trend graphs regarding energy management parameters. Connections between the computer system and the heat recovery system can be made through an RS422 4 wire connection and optionally via an Ethernet connection. Primary Heat Recovery Coil Operation

Figure 2 is a flowchart that outlines a control method 300 for operation of the three way control valve 99 that can route warm water from the setters and hatchers to the primary heat recovery coil or bypass the coil and send the water directly to the chiller system. Prior to operation, the user inputs a setting for maximum air temperature for air coming off the primary heat recover coil. This set point is denoted ST2 and it is measured with temperature sensor T2. The user also inputs low and high temperature alarm set points for T2, LAT2 and HAT2, respectively. If at any time the air coming off the primary coil falls outside the range defined by these two set points, an alarm is activated. To set up the minimum allowable flow rate for the process control pump, SFLWl, the user sets the process pump 145 to operate at approximately 15% capacity such that with no cooling load on the system, all cooling water is diverted back into the bypass line.

During operation, ambient air passes into the main air intake and passes over the primary heat recovery coil. At 310 and 320 the temperature of the air after the primary coil is measured with temperature sensor T2 and compared to the maximum set point ST2 at 330. If the air temperature is above the set point at 350 the valve 99 is closed by 10% to route less water to the coil. If the air temperature is below the set point, at 340 the ambient air temperature is measured with temperature sensor Tl. The temperature of the return water from the incubators is measured with temperature sensor FTl . At 360 if the ambient air temperature is less than that of the return water temperature then at 370 the valve is opened 10% to allow more water to flow through the primary heat recovery coil. manner the valve will be further opened to increase the flow of water through the coil as long as the ambient air temperature is less than the temperature of the water returned from the incubators, meaning that the ambient air will be warmed by the return water in the coils. Once the temperature of the air off the coil reaches the operational set point, usually about 80 degrees F, the flow into the coil is throttled back until the ambient temperature of the return water is the same as the ambient air temperature, at which point the valve position is maintained. In addition to controlling operation of the valve 99, the controller 50 calculates an actual air flow volume passing into the main air intake using an air velocity measurement made with sensor Vl and using the cross sectional area of the ducting surround the velocity sensor.

Numerous calculations are made by the controller to estimate the amount of heat that is recovered using the heat recovery system. Using the temperature of the ambient air, the temperature off the coil and the air velocity, the controller can calculate the online heat recovered from the primary heat recovery coil in KW. This information is displayed on a monitor that is part of the computer 54. The controller also monitors the temperature of the water returned from the primary heat recovery coil and the flow rate of the water through the coil as measured by sensor FS 1. Since the controller also monitors the incoming water temperature from sensor FTl, the outgoing water temperature RT2, and the water flow rate FSl, the controller can calculate the amount of heat dissipated from the primary heat recovery coil.

Li addition to controlling the valve 99 to selectively route water the primary heat recovery coil, the controller also monitors the functioning of the valve and pumps in the system. To accomplish this, the controller monitors the water flow rate FLWl from the chilled water plant 17 and the temperature of the chilled water TCl. The temperature of the chilled water is compared to user settings LATCl and HATCl, which are low and high chilled water temperature alarm set points. For normal operation, TCl must stay within the band of LATCl and HATCl. If the flow rate out of the pump 145 falls below a minimum flow rate set by the user as SFLWl, the alarm is activated. In normal operation, FLWl should equal or exceed that of SFLWl, if not then the controller will initiate an auto changeover to the standby process pump 146. In such circumstance, this drive. However, the instigation of the auto changeover could be the result of a low flow rate from the FLWl or from the digital input indicating that the pump has failed.

Within the user settings for the water flow rate, the value of FLWl will be compared to the user settings of a user input LA-FLWl (low alarm) and HA-FLWl (high alarm). For normal operation the water flow rate must stay within the band of the settings, otherwise the alarm will be activated. The process pump capacity is controlled by monitoring the static water pressure as measured in front of the process pump (PSl) and adjusting the pump capacity to match the user setting as set in SP-PSl. A typical setting for the water pressure would be about 280 Kpa (40 PSI). The controller automatically adjusts the pump capacity according to the cooling demand of the incubator plant. Thus, a low incubator demand will start to increase the water pressure in the system in response to which the controller will compensate by dropping the pump capacity. Conversely, a higher demand will result in a drop in water pressure in response to which the controller will compensate by increasing the pump capacity. The result of this control reduces the electrical consumption of the process pump.

Within the user settings for the water pressure, the value ofPSl will be compared to the user setting of LA-PSl (low alarm) and HA-PSl (high alarm). For normal operation, the water pressure must stay within the band of the settings, otherwise the alarm will be activated. hi addition to the control of the process pump with respect to water pressure, the controller also monitors the temperature of the water returned from the incubators (FTl) and the outgoing chilled water temperature TCl. By subtracting TCl from FTl the controller calculates the temperature difference across the incubator plant. Furthermore, the controller calculates the cooling load across the incubator plant by finding the flow rate in the incubator return line, FLW1-FLW2. The controller monitors the change in temperature across the incubator plant and compares this to a user setting, DtI. While the water pressure in the system is the primary control parameter of the process pump, the controller also takes into consideration this change in temperature across the incubator plant. A very low change in temperature could indicate an excessively high flow rate while a very high change in temperature may indicate an excessively low flow rate. Such flow rate FLWl is found to be abnormally low or high, the direct control of the process pump capacity is controlled taking into consideration the change in temperature and FLWl and an alarm is activated.

The controller calculates the heat dissipation across the chilled water plant by measuring FLWl, FLW2, TCl, and TR2. The flow rate for calculation is found by subtracting FLW2 from FLWl and the change in temperature across the chilled water plant is found by subtracting TCl from TR2. Secondary Air to Air Heat Exchanger Plate Operation

Referring now to Figure 3, a method 400 for controlling the flow of air to the air to air plate heat exchanger 20 is outlined. At 410 and 420, the controller inputs the post coil air temperature from T2 and the user setting ST3 for air leaving the air to air plate heat exchanger. At 430, these two values are compared and the controller then controls the bypass dampers 41, 42 to obtain the user required temperature ST3 as measured at T3. At 430 if the post coil temperature is higher than or equal to the set point, the positions of the dampers are not changed. If the post coil temperature is lower than the set point, at 440 and 450 the post heat exchanger air temperature (T3) is compared to the set point (ST3) and if T3 is less than the set point, at 460 the recovery air damper 42 is opened by 10% to allow exhaust air from the setters to pass over the air to air plate heat exchanger. At the same time, at 470 the bypass damper 41 is closed by 10% to throttle back air by-passing the heat exchanger. If at 450 T3 is greater than the set point, at 455 the recovery damper 42 is closed by 10% and at 475 the bypass damper is opened by 10%. The process then waits for 30 seconds at 480 before resuming the control loop at 410. If at 450 T3 equals the set point, the process resumes at 480.

Within the user settings for the final air temperature, the value of T3 will be compared to the user settings of LA-T3 (low alarm) and HA-T3 (high alarm). For normal operation the final air temperature must stay within the band of settings, otherwise the alarm will be activated. Given that the controller can measure the final air temperature T3, the exhaust air temperature from the setters T4, the temperature of the air past the heat exchanger plate T5, and the air flow rate from Vl, the controller can calculate the air to air plate heat exchanger.

As mentioned above, the computer 54 makes numerous calculations to aid the user in determining the functional status of the heat recovery system as well as quantifying the various savings that are incurred by using the heat recovery system. A few examples of the calculations that can be made and stored as historical data include: (1) the amount of heat removed from the chilled water system return line in KW;(2) the amount of heat energy dissipated into the incoming air in KW; the efficiency of the primary heat recovery coil based on (1) and (2); (3) the financial savings in electrical energy through the reduced use of water chillers and heat dissipated into the incoming air; (4) the electrical savings due to the reduced and variable operating capacity of the pump; (5) the financial savings in gas and oil energy from the primary and secondary heat recovery systems; (6) the heat load dissipated into the return water line from the incubators and across the chilled water plant; (7) the heat dissipated from the exhaust air into the supply air; (8) the efficiency of the plate heat exchanger; and (9) the overall heat recovered, the online overall financial savings.

While the invention has been described with a degree of particularity, it is the intent that the invention includes all modifications and alterations from the disclosed design falling within the spirit or scope of the appended claims.

Claims

I claim:

1. An apparatus for controlling an ambient temperature within an egg hatchery that includes a fresh air intake, an exhaust port that exhausts heated exhaust air from the hatchery, and a water chilling system that includes a water chiller, cool water pipes that circulate cool water through the hatchery and at least one warm water return pipe that returns warm water to the water chiller, the apparatus comprising: a first heat exchanger in fluid communication with the incoming fresh that selectively transfers heat from warm water returned from the water chilling system to the incoming fresh air; a valve disposed between the first heat exchanger and the warm water return pipe that controls the flow of warm water into the first heat exchanger; and a controller that controls the valve to provide a controlled flow of warm water to . the first heat exchanger based on a temperature of the incoming fresh air and the temperature of water in the warm water return pipe to maintain the ambient temperature in the hatchery within a predetermined range of temperatures.

2. The apparatus of claim 1 wherein the first heat exchanger is incorporated into a fresh air intake duct and through which the warm water flows.

3. The apparatus of claim 1 comprising a second heat exchanger in fluid communication with the incoming fresh air and the exhaust air to transfer heat from the exhaust air to the incoming fresh air and wherein the controller controls one or more dampers to control the amount of exhaust air that flows past the second heat exchanger to maintain the ambient temperature in the hatchery within a predetermined range of temperatures. plate heat exchanger having sides that are sealed and isolated from one another to prevent mixing of exhaust air with incoming fresh air.

5. A method that recovers heat from egg incubation to heat incoming fresh air to an egg hatchery, the method comprising: passing cool water through the hatchery to cool the hatchery and selectively passing the returning water that is warmed by the hatchery through a heat exchanger; monitoring a fresh air temperature of the fresh air upstream of the heat exchanger; monitoring a warm water temperature of the warm water; and if the warm water temperature is greater than the fresh air temperature increasing the flow of warm water to the coil heat exchanger.

6. The method of claim 5 wherein the monitoring is performed by a controller having memory and instructions for monitoring stored in the memory.

7. The method of claim 5 wherein the flow of warm water is increased by actuating a valve that controls the flow of water to the heat exchanger.

8. The method of claim 5 wherein if the warm water temperature is less than the fresh air temperature decreasing the flow of warm water to the coil heat exchanger.

9. The method of claim 8 wherein the flow of warm water is increased by actuating a valve that controls the flow of water to the heat exchanger.

10. The method of claim 5 comprising monitoring a post heat exchanger air temperature and comparing it to a maximum air temperature set point and if the post heat the flow of water to the heat exchanger.

11. The method of claim 10 comprising decreasing the flow of water to the heat exchanger if the post heat exchanger air temperature is greater than the maximum air temperature set point.

12. A method that recovers heat from egg incubation to heat incoming fresh air to an egg hatchery, the method comprising: passing cool water through the hatchery to cool the hatchery; selectively passing the returning water that is warmed by the hatchery through a heat exchanger; monitoring a fresh air temperature of the fresh air upstream of the heat exchanger; monitoring a post coil air temperature of air downstream of the heat exchanger; monitoring a warm water temperature of the warm water; comparing the post coil air temperature to a maximum post coil air temperature set point and increasing the flow of warm water to the heat exchanger if the post coil air temperature is greater than the set point; and if the post coil air temperature is less than the set point, comparing the fresh air temperature to the warm water temperature and increasing the flow of warm water to the heat exchanger if the fresh air temperature is less than the warm water temperature and decreasing the flow of warm water to the heat exchanger if the fresh air temperature is greater than the warm water temperature.

13 The method of claim 12 wherein the monitoring is performed by a controller having memory and instructions for monitoring stored in the memory. decreased by actuating a valve that controls the flow of water to the heat exchanger.

15. A method that recovers heat from egg incubation to heat incoming fresh air to an egg hatchery, the method comprising: passing fresh air into the hatchery and selectively passing exhaust air that has been heated by the hatchery past an air to air heat exchanger that is in fluid communication with the fresh air; monitoring an air temperature of the air downstream of the heat exchanger; monitoring a set point for the air downstream of the heat exchanger; and if the air temperature is greater than the set point, decreasing the flow of exhaust air past the heat exchanger.

16. The method of claim 15 wherein the monitoring is performed by a controller having memory and instructions for monitoring stored in the memory.

17. The method of claim 15 wherein the flow of exhaust air is decreased by actuating one or more dampers that control the flow of exhaust air past the heat exchanger.

18. The method of claim 15 wherein if the air temperature is less than the set point, increasing the flow of exhaust air past the heat exchanger.

19. The method of claim 18 wherein the flow of exhaust air is increased by actuating one or more dampers that control the flow of exhaust air past the heat exchanger. temperature and comparing it to the maximum air temperature set point and maintaining the flow of exhaust air at the same rate if the incoming air temperature is greater than or equal to the maximum air temperature set point.

21. A method that recovers heat from egg incubation to heat incoming fresh air to an egg hatchery, the method comprising: passing fresh air into the hatchery and selectively passing exhaust air that has been heated by the hatchery past an air to air heat exchanger that is in fluid communication with the fresh air; monitoring an incoming air temperature and comparing it to a maximum air temperature set point and maintaining the flow of exhaust air at the same rate if the incoming air temperature is greater than or equal to the maximum air temperature set point; monitoring an air temperature of the air downstream of the heat exchanger; if the downstream air temperature is greater than the set point, decreasing the flow of exhaust air past the heat exchanger; and if the downstream air temperature is less than the set point, increasing the flow of exhaust air past the heat exchanger.

22. The method of claim 21 wherein the monitoring is performed by a controller having memory and instructions for monitoring stored in the memory.

23. The method of claim 15 wherein the flow of exhaust air is decreased and increased by actuating one or more dampers that control the flow of exhaust air past the heat exchanger.