CN110998186A

CN110998186A - Regenerative thermal oxidizer system and method of operating regenerative thermal oxidizer system

Info

Publication number: CN110998186A
Application number: CN201780092423.2A
Authority: CN
Inventors: 余量; 胡立舜; 薛俊利; F.何林
Original assignee: Elpai American Bidding Co
Current assignee: Elpai American Bidding Co
Priority date: 2017-06-23
Filing date: 2017-06-23
Publication date: 2020-04-10
Also published as: WO2018232722A1

Abstract

A regenerative thermal oxidizer system (100) and a method for operating a regenerative thermal oxidizer system (100) are provided. A regenerative thermal oxidizer system (100) comprising: a supply pipe (102) for supplying a supply gas flow (101); an exhaust pipe (103) for exhausting the first output gas flow; a combustion chamber (115); a first regenerator chamber (111) and a second regenerator chamber (113) in fluid communication with the combustion chamber (115); an oxidation chamber (117); and a flow control system. The oxidation chamber (117) is used to treat the residual feed gas stream as the gas stream reverses, so that emissions spikes can be avoided.

Description

Regenerative thermal oxidizer system and method of operating regenerative thermal oxidizer system

Technical Field

The present disclosure generally relates to a Regenerative Thermal Oxidizer (RTO) system and a method for operating an RTO system.

Background

Industrial emissions often contain combustible pollutants, contaminants, and/or odors (odors), such as Volatile Organic Compounds (VOCs), which, if released to the atmosphere, have the potential to contaminate the environment. The thermal and/or catalytic oxidizers raise the temperature of such industrial emissions to a temperature above the light-off temperature of the pollutants in order to oxidize the pollutants.

RTOs have been used to remove contaminants from industrial gas streams. RTOs are unique in their ability to save fuel through the use of heat exchange media. Typically, an RTO includes: a combustion chamber; at least two regenerator chambers containing a heat exchange medium; a conduit system for conveying the stream of industrial gas to and from the combustor via the regenerator chamber; and a control system. The heat exchange medium typically comprises a ceramic material.

In general, there are two-chamber type RTOs including two regenerator chambers and three-chamber type RTOs including three regenerator chambers. In the example of a two-chamber RTO, the first regenerator chamber and the second regenerator chamber are heated to a predetermined temperature. The stream of industrial gas to be cleaned then passes through the first regenerator chamber into the combustion chamber. Upon exiting the first regenerator chamber, the gases begin to approach the combustion temperature, or combustion has begun spontaneously. In the combustion chamber, the gases may be further heated via a burner, so that thermal oxidation takes place or combustion continues (if self-heating has already started). The hot clean gas leaving the combustion chamber then passes through a second regenerator chamber where the gas releases most of its heat and thus raises the temperature of the second regenerator chamber. The cooled gas stream is then exhausted from the two-chamber RTO. After a period of time, the flow of the process gas stream to be cleaned is reversed by the control system so that the second regenerator chamber receives the process gas stream to be cleaned, in which the process gas stream to be cleaned is preheated before being introduced into the combustion chamber. Preheating improves the efficiency of the system. The first regenerator chamber receives hot clean gas from the combustion chamber. The process above is repeated as the two-chamber RTO continuously and efficiently removes impurities from the process gas stream.

One problem that significantly affects the oxidation efficiency of a two-chamber RTO is that some contaminants that have not been oxidized can be released during switching of the flow direction. When the gas flow reverses, the pollutant emissions will reach a peak, since the feed gas flow present in the first or second regenerator chamber (due to preheating) has not yet been combusted and, once the reversal has occurred, will be sent to the stack. Thus, the contaminant concentration profile at the system outlet may have periodic peaks. The three-chamber type RTO can avoid periodic peaks by: the off-line chamber is purged before queuing it for the next exhaust cycle to achieve higher destruction efficiency than a two-chamber RTO. However, a three-chamber RTO is more expensive and requires more space.

There is a need for an improved RTO system and RTO operating method to address the problems noted above.

Disclosure of Invention

One aspect of the present disclosure provides an RTO system. The RTO system includes: a supply pipe for supplying a supply gas stream; a discharge pipe for discharging a first output gas stream; a combustion chamber; a first regenerator chamber and a second regenerator chamber in fluid communication with the combustion chamber; an oxidation chamber having an inlet and an outlet; a flow control system configured to: controlling a changeover of the connection between the supply pipe and the first regenerator chamber and the connection between the supply pipe and the second regenerator chamber; controlling switching of the connection between the first regenerator chamber and the discharge pipe and the connection between the second regenerator chamber and the discharge pipe; and controlling switching of the connection between the first regenerator chamber and the inlet of the oxidation chamber and the connection between the second regenerator chamber and the inlet of the oxidation chamber.

Another aspect of the present disclosure provides a method for operating an RTO system. The RTO system includes: a supply pipe for supplying a supply gas stream; a discharge pipe for discharging a first output gas stream; a combustion chamber; a first regenerator chamber and a second regenerator chamber in fluid communication with the combustion chamber; and an oxidation chamber having an inlet and an outlet. The method comprises the following steps: controlling a flow of feed gas from the feed tube through the first regenerator chamber, the combustion chamber, the second regenerator chamber, and the exhaust tube; controlling the flow of residual supply gas in the first regenerator chamber to flow through the peroxidation chamber; controlling a flow of supply gas from a supply pipe through the second regenerator chamber, the combustion chamber, the first regenerator chamber, and the exhaust pipe; and controlling the flow of residual feed gas in the second regenerator chamber to flow through the oxygenation chamber.

Drawings

The foregoing and other aspects, features, and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic diagram of an RTO system according to a first embodiment of the present disclosure;

FIG. 2 is a schematic diagram of an RTO system according to a second embodiment of the present disclosure; and

fig. 3 is a flow diagram of a method for operating an RTO system according to one embodiment of the disclosure.

Detailed Description

Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms "a" and "an" do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as "about" and "substantially," will not be limited to the precise value specified. In addition, when the expression "about a first value to a second value" is used, about is intended to modify both values. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. Further, the prefix(s) "as used herein is generally intended to include both the singular and the plural of the term that it modifies, thereby including one or more of that term.

Any numerical value recited herein includes all values from the lower value to the higher value in increments of one unit if there is a separation of at least two units between any lower value and any higher value. By way of example, if it is stated that the number of components or the value of a process variable (such as, for example, temperature, pressure, time, etc.) is, for example, from 1 to 90, it is intended that values such as 15 to 85, 22 to 68, 43 to 51, 30 to 32, etc. are expressly enumerated in this specification. For values less than one, one unit is considered to be 0.0001, 0.001, 0.01, or 0.1, as appropriate. These are merely examples of what is specifically intended, and all possible combinations of numerical values between the lowest value and the highest value enumerated, are to be considered to be expressly stated in this application in a similar manner.

FIG. 1 shows an RTO system 100 according to a first embodiment of the present disclosure. The RTO system 100 includes: a supply pipe 102 for supplying a supply gas flow from a supply 101 of the supply gas flow; an exhaust pipe 103 for exhausting the first output gas stream; a combustion chamber 115; a first regenerator chamber 111; a second regenerator chamber 113; an oxidation chamber 117; and three flow control units. The source 101 supplying the gas stream may originate from an industry that may produce exhaust gases, including gas engine operations, petroleum refineries, fuel combustion, chemical processing, decomposition in biospheres and biomass, pharmaceutical plants, automotive industry, textile manufacturers, cleaning products, printing processes, painting/coating processes, electronic/semiconductor industry, etc.

The combustion chamber 115 is positioned between the first regenerator chamber 111 and the second regenerator chamber 113 and is in fluid communication with the first regenerator chamber 111 and the second regenerator chamber 113. In some embodiments, the combustion chamber 115 is provided with one or more burners (not shown in fig. 1) to maintain high temperatures in the combustion chamber 115. The oxidation chamber 117 includes an inlet 128 and an outlet 129. Each of the first regenerator chamber 111, the second regenerator chamber 113, and the oxidation chamber 117 is provided with a heat exchange medium 120. Typically, the heat exchange medium 120 comprises a ceramic material. There are several different media options with different surface areas and pressure losses, such as random media, structured media, and monolithic (also known as honeycomb) media. In some embodiments, the heat exchange medium 120 in at least one of the first regenerator chamber 111, the second regenerator chamber 113, and the oxidation chamber 117 may include one or more VOC oxidation catalysts. Thus, oxidation of contaminants may occur at reduced temperatures within the heat exchange medium 120. Lower oxidation temperatures result in reduced fuel consumption and lower operating costs. The VOC oxidation catalysts that can be used can include noble metal catalysts (such as Pt, Pd, Pt-Pd) or metal oxides (such as Cu-Mn oxides, Mn-Mg oxides, Cu-Mg-Cr oxides, and Cu-Cr oxides).

In the RTO system 100, the first regenerator chamber 111 and the second regenerator chamber 113 are generally the same size. The oxidation chamber 117 has a smaller size than the first regenerator chamber 111 or the second regenerator chamber 113. Preferably, the size of the oxidation chamber 117 is 1% -20% of the size of the first regenerator chamber 111. More preferably, the size of the oxidation chamber 117 is 1% -10% of the size of the first regenerator chamber 111. Due to the small size of the oxidation chamber 117, the RTO system 100 has a smaller footprint (footprint) than conventional three-chamber type RTO systems. In addition, the cost of the RTO system 100 is lower than conventional three chamber type RTO systems.

The three flow control units of the RTO system 100 include a plurality of pipes and valves. Specifically, the first flow control unit includes a first inlet pipe 131 and a second inlet pipe 132, the first inlet pipe 131 and the second inlet pipe 132 being used to connect the supply pipe 102 to the first regenerator chamber 111 and the second regenerator chamber 113, respectively. The second flow control unit comprises a first outlet pipe 133 and a second outlet pipe 134, the first outlet pipe 133 and the second outlet pipe 134 being used for connecting the first regenerator chamber 111 and the second regenerator chamber 113, respectively, to the discharge pipe 103. The third flow control unit comprises a first intermediate pipe 135 and a second intermediate pipe 136, the first intermediate pipe 135 and the second intermediate pipe 136 being used for connecting the first regenerator chamber 111 and the second regenerator chamber 113, respectively, to the inlet 128 of the oxidation chamber 117. Six valves 141-146 are positioned on the first inlet pipe 131, the second inlet pipe 132, the first outlet pipe 133, the second outlet pipe 134, the first intermediate pipe 135, and the second intermediate pipe 136, respectively, to control the opening and closing of the corresponding pipes.

To start up the RTO system 100, the first step is to heat the heat exchange medium 120 in the first regenerator chamber 111, the second regenerator chamber 113, and the oxidation chamber 117 to a predetermined temperature. The operational cycle may then be repeated during operation of the RTO system 100. As an embodiment, the operation cycle comprises the steps of:

a) opening

valves

141 and 144 and closing the other valves to allow the flow of the supply gas supplied from the supply pipe 102 to flow through the first inlet pipe 131, the first regenerator chamber 111, the combustion chamber 115, the second regenerator chamber 113, the second outlet pipe 134 and the discharge pipe 103;

b) opening

valves

142 and 145 and closing the other valves to allow the residual supply gas stream in the first regenerator chamber 111 to flow through the oxidation chamber 117 and, in the oxidation chamber 117, to oxidize the residual supply gas stream in the first regenerator chamber 111;

c) opening

valves

142 and 143 and closing the other valves to allow the flow of the supply gas supplied from the supply pipe 102 to flow through the second inlet pipe 132, the second regenerator chamber 113, the combustion chamber 115, the first regenerator chamber 111, the first outlet pipe 133 and the discharge pipe 103; and

d)

valves

141 and 146 are opened and the other valves are closed to allow the flow of residual supply gas in the second regenerator chamber 113 to flow through the oxidation chamber 117 and oxidize the flow of residual supply gas in the second regenerator chamber 113 in the oxidation chamber 117.

The RTO system 100 can further include a first heat supply pipe 139, the first heat supply pipe 139 connecting the combustion chamber 115 to the oxidation chamber 117. The first heat supply pipe 139 includes a valve 149 to control opening and closing of the first heat supply pipe 139. During operation of the RTO system 100, if the temperature of the heat exchange medium 120 in the oxidation chamber 117 is lower than the temperature at which the residual feed gas stream undergoes the oxidation reaction, the valve 149 will be opened and a portion of the high temperature gas stream from the combustion chamber 115 will be introduced into the oxidation chamber 117 to heat the heat exchange medium 120 in the oxidation chamber 117.

The oxidation chamber 117 may exhaust the high temperature second output gas stream from the outlet 129 of the oxidation chamber 117. To recover heat in the second output gas stream, in some embodiments, at least a portion of the second output gas stream may be introduced into the source 101 of the feed gas stream through a second heat supply pipe 137. Thus, the supply gas stream may be preheated before being sent to the first regenerator chamber 111 or the second regenerator chamber 113. In an alternative embodiment, the second output gas stream may be introduced to the exhaust pipe 103 for direct exhaust.

FIG. 2 shows an RTO system 200 according to a second embodiment of the present disclosure. The RTO system 200 includes: a supply pipe 202 for supplying a supply gas flow from a supply 201 of the supply gas flow; an exhaust 203 for exhausting a first output gas stream; a combustion chamber 215; the first regenerator chamber 211; a second regenerator chamber 213; an oxidation chamber 217; and a flow control system. There are several differences between RTO system 100 and RTO system 200.

The first difference is that the flow control system of RTO system 200 includes: a common switching valve 240 connected to the supply pipe 202; a first connection pipe 233 and a second connection pipe 234 for connecting the common switching valve 240 to the first regenerator chamber 211 and the second regenerator chamber 213, respectively; an outlet pipe 235 for connecting the common switching valve 240 to the discharge pipe 203; an intermediate pipe 236 for connecting the common switching valve 240 to the inlet 228 of the oxidation chamber 217; and two

valves

245, 246 positioned on outlet pipe 235 and intermediate pipe 236, respectively, to control the opening and closing of the respective pipes. The common switching valve 240 operates in two states. In the first state of the common switching valve 240, the supply pipe 202 is connected to the first connection pipe 233, and the second connection pipe 234 is connected to the outlet pipe 235 or the intermediate pipe 236. In the second state of the common switching valve 240, the supply pipe 202 is connected to the second connection pipe 234, and the first connection pipe 233 is connected to the outlet pipe 235 or the intermediate pipe 236.

The second difference is that the second output gas stream exiting the outlet 229 of the oxidation chamber 217 is introduced into the heat exchanger 260 rather than being introduced into the source 201 of the feed gas stream. In heat exchanger 260, heat contained in the second output gas stream may be transferred to the stream to be heated supplied by tube 238.

A third difference is that RTO system 200 further includes a central control system 250, with central control system 250 being used to automatically control the flow control system so that RTO system 200 operates at different stages. The central control system 250 sends control signals S1, S2, and S3 to the common switching valve 240 and the

valves

245, 246, respectively, so that the common switching valve 240 is controlled in the first state or the second state, and the

valves

245, 246 are controlled in the open state or the closed state. The operation of the RTO system 200 may be automatically controlled by a computer using the central control system 250.

The first step to start up the RTO system 200 is to heat the heat exchange medium 220 in the first regenerator chamber 211, the second regenerator chamber 213, and the oxidation chamber 217 to a predetermined temperature. An exemplary operational cycle of the RTO system 200 may include the steps of:

a) maintaining the common switching valve 240 in the first state, opening the valve 245 and closing the valve 246 to allow the flow of the supply gas supplied from the supply pipe 202 to flow through the first connection pipe 233, the first regenerator chamber 211, the combustion chamber 215, the second regenerator chamber 213, the second connection pipe 234, the outlet pipe 235 and the discharge pipe 203;

b) maintaining the common switching valve 240 in the second state, opening the valve 246 and closing the valve 245 to allow the residual supply gas stream in the first regenerator chamber 211 to flow through the oxidation chamber 217, oxidizing the residual supply gas stream in the first regenerator chamber 211 in the oxidation chamber 217;

c) maintaining the common switching valve 240 in the second state, opening the valve 245 and closing the valve 246 to allow the flow of the supply gas supplied from the supply pipe 202 to flow through the second connection pipe 234, the second regenerator chamber 213, the combustion chamber 215, the first regenerator chamber 211, the first connection pipe 233, the output pipe 235 and the discharge pipe 203; and

d) maintaining the common switching valve 240 in the first state, the valve 246 is opened and the valve 245 is closed to allow the residual supply gas stream in the second regenerator chamber 213 to flow through the oxidation chamber 217, and in the oxidation chamber 217, the residual supply gas stream in the second regenerator chamber 213 is oxidized.

The oxidation chamber 117 in the RTO system 100 and the oxidation chamber 217 in the RTO system 200 are used to treat the residual feed gas flow that has not yet been oxidized when the gas flow is reversed. Each time the residual feed gas stream in the first or second regenerator chamber is introduced to the

oxidation chamber

117, 217 for treatment before reversing the flow direction of the feed gas stream, the contaminants in the residual feed gas stream are oxidized in the

oxidation chamber

117, 217. Therefore, the emission peak problem of the conventional two-chamber type RTO is solved. Furthermore, the

RTO systems

100, 200 of the present disclosure have a smaller footprint and reduced cost compared to conventional three-chamber RTOs. The different features of RTO system 100 and RTO system 200 may be combined in other embodiments of the disclosure.

FIG. 3 shows a flow diagram of a method 300 for operating an RTO system according to one embodiment of the present disclosure. The RTO system includes: a supply pipe for supplying a supply gas stream; a discharge pipe for discharging a first output gas stream; a first regenerator chamber and a second regenerator chamber in fluid communication with the combustion chamber; and an oxidation chamber having an inlet and an outlet. The method comprises the following steps:

step 301: controlling a flow of feed gas from the feed tube through the first regenerator chamber, the combustion chamber, the second regenerator chamber, and the exhaust tube;

step 303: controlling the flow of residual supply gas in the first regenerator chamber to flow through the peroxidation chamber;

step 305: controlling a flow of supply gas from a supply pipe through the second regenerator chamber, the combustion chamber, the first regenerator chamber, and the exhaust pipe; and

step 307: the flow of residual feed gas in the second regenerator chamber is controlled to flow through the oxidation chamber.

In some embodiments, the method 300 may further include the steps of: when the temperature in the oxidation chamber is below the temperature required for oxidation of the VOC contaminants, a high temperature gas stream is supplied from the combustion chamber to the inlet of the oxidation chamber to heat the oxidation chamber.

In some embodiments, the method 300 may further include the steps of: at least part of the second output gas stream discharged from the outlet of the oxidation chamber is supplied to the source of the feed gas stream, such that the feed gas stream in the source of the feed gas stream is preheated.

In some embodiments, the method 300 may further include the steps of: heat from the second output gas stream discharged from the outlet of the oxidation chamber is transferred to the stream to be heated such that waste heat in the second output gas stream is reused.

This written description uses examples to describe the disclosure (including the best mode) and also to enable any person skilled in the art to practice the disclosure (including making and using any devices or systems and performing any incorporated methods). The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

1. A regenerative thermal oxidizer system comprising:

a supply pipe for supplying a supply gas stream;

a discharge pipe for discharging a first output gas stream;

a combustion chamber;

a first regenerator chamber and a second regenerator chamber in fluid communication with the combustion chamber;

an oxidation chamber having an inlet and an outlet; and

a flow control system configured to:

controlling a changeover of a connection between the supply pipe and the first regenerator chamber and a connection between the supply pipe and the second regenerator chamber;

controlling switching of the connection between the first regenerator chamber and the discharge pipe and the connection between the second regenerator chamber and the discharge pipe; and is

Controlling a transition of a connection between the first regenerator chamber and the inlet of the oxidation chamber and a connection between the second regenerator chamber and the inlet of the oxidation chamber.

2. The regenerative thermal oxidizer of claim 1, wherein each of the first regenerator chamber, the second regenerator chamber, and the oxidation chamber is filled with a heat exchange medium, and at least one of the first regenerator chamber, the second regenerator chamber, and the oxidation chamber includes an oxidation catalyst.

3. The regenerative thermal oxidizer of claim 1, wherein the size of the oxidation chamber is 1% -20% of the size of the first regenerator chamber or the second regenerator chamber.

4. The regenerative thermal oxidizer of claim 1, wherein the flow control system comprises:

a first flow control unit comprising a first inlet pipe and a second inlet pipe for connecting the supply pipe to the first regenerator chamber and the second regenerator chamber, respectively, wherein each of the first inlet pipe and the second inlet pipe comprises a respective valve;

a second flow control unit comprising a first outlet pipe and a second outlet pipe for connecting the first regenerator chamber and the second regenerator chamber, respectively, to the discharge pipe, wherein each of the first outlet pipe and the second outlet pipe comprises a respective valve; and

a third flow control unit comprising a first intermediate pipe and a second intermediate pipe for connecting the first regenerator chamber and the second regenerator chamber, respectively, to the inlet of the oxidation chamber, wherein each of the first intermediate pipe and the second intermediate pipe comprises a respective valve.

5. The regenerative thermal oxidizer of claim 1, wherein the flow control system comprises:

a common switching valve connected to the supply pipe;

first and second connection pipes for connecting the common switching valve to the first and second regenerator chambers, respectively;

an outlet pipe for connecting the common switching valve to the discharge pipe; and

an intermediate pipe for connecting the common switching valve to the inlet of the oxidation chamber,

wherein each of the outlet tube and the intermediate tube comprises a valve.

6. The regenerative thermal oxidizer system of claim 1, further comprising a central control system for controlling the flow control system such that the regenerative thermal oxidizer system operates in different stages, wherein the different stages comprise:

a stage of controlling the flow of said feed gas from said feed pipe through said first regenerator chamber, said combustion chamber, said second regenerator chamber and said discharge pipe;

a stage of controlling the flow of residual feed gas in said first regenerator chamber through said oxidation chamber;

a stage of controlling the flow of supply gas from the supply pipe through the second regenerator chamber, the combustion chamber, the first regenerator chamber and the discharge pipe; and

a stage of controlling the flow of residual feed gas in the second regenerator chamber through the oxidation chamber.

7. The regenerative thermal oxidizer system of claim 1, further comprising a first heat supply pipe connecting the combustion chamber to the oxidation chamber and configured to supply a flow of high temperature gas from the combustion chamber to the inlet of the oxidation chamber.

8. The regenerative thermal oxidizer system of claim 1, further comprising a second heat supply pipe connecting the outlet of the oxidation chamber to a source of the feed gas stream and configured to supply at least a portion of a second output gas stream discharged from the outlet of the oxidation chamber to the source of the feed gas stream.

9. The regenerative thermal oxidizer system of claim 1, further comprising a heat exchanger for transferring heat from a second output gas stream discharged from the outlet of the oxidation chamber to a stream to be heated.

10. A method for operating a regenerative thermal oxidizer system that includes a feed pipe for supplying a feed gas stream, an exhaust pipe for exhausting a first output gas stream, a combustion chamber, first and second regenerator chambers in fluid communication with the combustion chamber, and an oxidation chamber having an inlet and an outlet, the method comprising:

controlling the flow of the feed gas from the feed tube through the first regenerator chamber, the combustion chamber, the second regenerator chamber, and the exhaust tube;

controlling the flow of residual feed gas in the first regenerator chamber through the oxidation chamber;

controlling the flow of supply gas from the supply pipe through the second regenerator chamber, the combustion chamber, the first regenerator chamber, and the exhaust pipe; and

controlling a flow of residual feed gas in the second regenerator chamber through the oxidation chamber.

11. The method of claim 10, further comprising supplying a flow of high temperature gas from the combustion chamber to the inlet of the oxidation chamber to heat the oxidation chamber.

12. The method of claim 10, further comprising supplying at least a portion of a second output gas stream discharged from the outlet of the oxidation chamber to a source of the feed gas stream.

13. The method of claim 10, further comprising transferring heat from a second output gas stream discharged from the outlet of the oxidation chamber to a stream to be heated.